CA1296455C - Polymer emulsion containing an interpenetrating polymer network - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An aqueous polymer comprising 5 to 95% on a solids by weight basis of a first polymer network intertwined on a molecular scale with a different polymer network is obtained by allowing an emulsion mixture of a second monomer emulsion with a first polymer emulsion containing an active cross-linking agent to equilibriate before polymerizing the emulsion mixture. the resulting polymer emulsion is useful as a binder, adhesive or coating.

Description

12~55 SUN-173 (Chemical) (7-go) POLYMER EMULSION CONTAINING AN
INTERPENETRATING POLYMER NETWORK

BACKGROUND OF THE INVENTION
This invention relates to a process for pre-paring a polymer emulsion containing colloidally sus-pended therein an interpenetrating polymer network wherein a first polymer network is intertwined on a molecular scale with a second polymer network and op-tionally additional polymer networks. The polymer emulsion of this invention is useful as binder of fi-bers or fabrics, especially fiberfill.
Fiberfill is a generic term used to describe a variety of nonwoven fabrics for a variety of end uses. The common feature of all fiberfill products is a measure of loft or thickness in the fabric. This loft is a characteristic of value because it imparts insulation to outerwear and bed quilt stuffing, cush-ioning in furniture padding, dust holding capacity to filter media and resiliency to scrubbing pads. The most common construction of a fiberfill product is a loosely garnetted, cross-lapped or air laid web of 6 to 30 denier polyester staple fibers which is bonded (locked in its particular fiber arrangement) by an emulsion polymer binder. Fiberfill products can be made with other fibers, e.g. polyamide, cellulose ace-tate, rayon, glass, alone or in blends with each other.
Some fiberfill is sold without a bonding agent but the .

.

~2~45~

material will lack durability, tensile strength and re-siliency when compared to a bonded product. Bonding methods other than emulsion polymers, such as needle punching, and meltable fibers and powders are also used, but the polymer emulsion method produces the op-timum strength/loft ratios for the majority of fiber-fill markets.
The polymer emulsion product used as the binder is usually one of the following chemical types:
polyvinylacetate, acrylic copolymers, styrene-butadiene copolymers or polyvinylchloride. Polyvinylacetate is the most common binder and in recent years it has been made white enough and strong enough to replace most of the acrylic polymer traditionally used. Polyvinylchlo-ride is used where flame resistance is of prime concern and styrene-butadiene copolymers are used for special rubbery applications.
The characteristic of initial loft is unaf-fected by the chemical type of the binder used. How-ever, initial loft is not the loft of value. Fiberfill products in their normal use are compressed, reducing the initial loft, and released many times. The true value of loft is how thick the fiberfill web is after repeated compression/recovery cycles. One drawback of current polymer bonded fiberfill technology is that temperatures over 100F will soften the binder and cause the fiberfill product to permanently lose loft if it is compressed at this elevated temperature. Temper-atures of up to 180F are encountered in the shipping and use of many fiberfill products. Typically a fiber-fill product, which may lose only 15% of its initial loft if compressed and released at 80F, will lose more than 80~ of its loft if tested the same way at only 120F. Higher temperatures are expected to even more dramatically damage this loft recovery.

The polymer emulsion prepared by the process of this invention provides a binder compound for fiber-fill which provides improved resiliency and loft recov-ery to the bonded fiberfill products. This polymer emulsion is useful in bonding textile fibers in a fi-berfill product or in any nonwoven product or even any traditional woven or knitted textile fabric.

SU~MARY OF THE INVENTION
Briefly, the present invention provides a process for preparing a polymer emulsion containing an interpenetrating polymer network by forming a first polymer emulsion, mixing a second monomer emulsion with the first polymer emulsion, allowing the emulsion mix-ture to equilibrate and polymerizing the emulsion mix-ture providing a first polymer network which is inter-twined on a molecular scale with the second polymer network.

DETAILED DESCRIPTION ~F THE INVENTION
The aqueous polymer emulsion containing an interpenetrating polymer network is prepared by forming a first polymer emulsion. The first polymer emulsion can be prepared by conventional batch, semi-continuous or continuous polymerization procedures. These are taught, for example in U.S. Patent No. 2,754,280, 2,795,564, 3,732,184, and in the book entitled "The Applications of Synthetic Resin Emulsion" by H. Warson, Ernest Benn Limited, London, 1972, pp. 85 to 132. The first polymer emulsion can be formed by polymerizing a monomer or a mixture of monomers (herein called a first monomer) with an active crosslinking agent. Alterna-tively the first polymer emulsion can be formed by emulsifying a polymer.

,:

5~5 The first polymer emulsion is mixed with a second monomer emulsion and then the emulsion mixture is allowed to equilibrate. By equilibration is meant allowing sufficient time for the second monomer to be-come absorbed into the first polymer. The mixing and equilibration allows the second monomer emulsion to be thoroughly mixed and dispersed throughout the first polymer emulsion on a molecular scale.
Then, after thorough mixing and equilibration the emulsion mixture is polymerized providing a first polymer network which is intertwined on a molecular scale with the second polymer network, i.e. an inter-penetrating polymer network is formed. Optionally, a third monomer emulsion can then be mixed in, equili-brated, followed by polymerization or further addition-al monomer emulsions can likewise be intertwined in the polymer networks. When the polymer emulsion is subse-quently applied, dried and heated the physical and chemical bonding of the first polymer network with the second polymer network is completed.
Because of the interpenetrating network formed, desirable physical properties are achieved.
Dual Tg (glass transition temperature) properties have been observed wherein the polymer has the Tg of both the first polymer and the second polymer. This is es-pecially useful in the application of the polymer emul-sion wherein modulus, tensile strength and desirable film forming properties can be adjusted by varying the ratio of the first and second polymers comprised in the interpenetrating network. Because the first and second networks are intertwined on a molecular scale higher tensile strength has been observed as well as higher modulus and higher impact strength at temperatures in-termediate the Tg's of the first polymer and the second polymer.

lX~55 The monomers which are polymerized in accor-dance with the present invention are vinyl monomers, ethylenically unsaturated compounds. Examples of mono-ethylenically unsaturated monomers are: vinyl esters of alkanoic acids having from 1 to about 18 carbon atoms, such a vinyl formate, vinyl acetate, vinyl pro-pionate, vinyl butyrate, vinyl isobutyrate, vinyl val-erate, vinyl 2-ethylhexanoate, vinyl isooctanoate, vi-nyl nonoate, vinyl decanoate, vinyl pivalate, vinyl ester (e.g. Versatic Acid-TM, a branched carboxylic acid, marketed by the Shell Oil Corporation), vinyl laurate, and vinyl stearate; also alpha-olefins, such as ethylene, propylene, butylene, isobutylene, and pentene and the like; also maleate, fumarate, and ita-conate esters of Cl-C8 alcohols, such as dibutyl male-ate, dibutyl fumarate, dibutyl itaconate; also alkyi acrylates with an alkyl group having from 1 to 18 car-bon atoms, such as methyl, ethyl, n-butyl, sec-butyl, the various isomeric pentyl, hexyl, heptyl, and octyl (especially 2-ethylhexyl), lauryl, cetyl, stearyl and like groups; also alkyl esters of methacrylic acid with an alkyl group having from 1 to about 18 carbon atoms, such as methyl~ ethyl, propyl, n-butyl, n-hexyl, 2-ethylhexyl, n-octyl, lauryl, cetyl, stearyl and like groups, also vinyl alkyl ethers, having an alkyl group with 1 to 18 carbon atoms, such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and stearyl vinyl ether. Examples of monomers also include diene mono-mers, such as butadiene, chloroprene, isoprene and sim-ilar compounds. Other monomers include aromatic vinyl monomers, such as styrene, alpha-methylstyrene, vinyl toluene, 2-bromostyrene, and p-chlorostyrene; also acrylonitrile, also vinyl halide monomers, such as vi-nyl chloride and vinylidene chloride; also benzyl .

~ 55 acrylate and t-butyl acrylate; also vinyl esters of aromatic acids, such as vinylbenzoate.
Preferably the polymer present in the first polymer emulsion is either polymethyl methacrylate, polyvinyl acetate, polystyrene or polyacrylo nitrile or copolymers of these with other monomers mentioned above, while the second polymer differs from the first polymer and preferably is based upon a monomer such as acrylo nitrile, methyl methacrylate, butyl acrylate, styrene or mixtures thereof.
In order to obtain desirable dual Tg proper-ties, the polymer in the first polymer emulsion and the polymer derived from the second monomer emulsion can be chosen so, for example, one has a Tg greater than the other. Different pairs of polymers can be chosen to exhibit useful properties over different temperature ranges. For example, because of polystyrene's higher Tg, upon interpenetrating a polyvinyl acetate network it will extend the modulus and reduce distortion of the matrix at elevated temperatures.
In general, the various combinations of mono-mers can be chosen for the first polymer emulsion or the second monomer emulsion. However, the monomer chosen for the first monomer emulsion cannot be an in-hibitor to the polymerization of the monomer in the second monomer emulsion. Since acrylo nitrile is an inhibitor to the polymerization of vinyl acetate, the vinyl acetate must be in the first polymer emulsion while the acrylo nitrile is in the second monomer emul-sion. Thus, in a preferred embodiment, the first poly-mer emulsion contains vinyl acetate or vinylacetate-butylacrylate while the second monomer emulsion con-tains either styrene, methyl methacrylate, acrylo ni-trile or acrylo nitrile-butylacrylate.

Advantageously, this process of the present invention provides a interpenetrating network of poly-mers which are generally physically incompatible in that the polymers are not soluble in one another. In addition, this process provides a means of combining polymers which cannot be formed by copolymerization of their monomers. For example, vinyl acetate and styrene cannot be copolymerized and mixing or blending of the two polymers does not result in a polymer having desir-able properties (e.g. poor tensile strength).
The first polymer emulsion and optionally the second monomer emulsion contain an active crosslinking agent. By the term ~active crosslinking agent" is meant a functional monomer which immediately provides crosslinking and branching of the polymer during the initial formation of the emulsion polymer to increase the molecular weight of the emulsion polymer. Subse-quent drying or other curing techniques are not re-quired for the crosslinking and branching of the emul-sion polymer by the active crosslinking agent. Mono-mers of this type generally comprise compounds which contain 2 to 5 ethylenically unsaturated groups in one molecule separated by an ester or ether group, or by an aromatic or nitrogenous ring structure, where the un-saturated groups are capable of undergoing additional polymerization by free radical means. Suitable active crosslinking agents include alkylene glycol diacrylates and methacrylates, such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, propylkene glycol dia-crylate, triethylene glycol dimethacrylate etc., 1,3-glycerol dimethacrylate, l,l,l-trimethylol propane di-methacrylate, l,l,l-trimethylol ethàne diacrylate, pentaerythritol trimethacrylate, sorbitol pentametha-crylate, methylene bisacrylamide, methylene bismetha-crylamide, divinyl benzene, vinyl methacrylate, vinylcrotonate, vinyl acrylate, divinyl adipate; also di-and tri-allyl compounds, such a triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, allyl metha-crylate, allyl acrylate, diallyl maleate, diallyl fuma-rate, diallyl itaconate, diallyl malonate, diallyl car-bonate, triallyl citrate, triallyl aconitate; also di-vinyl ether, ethylene glycol divinyl ether and the like. The amount of active crosslinking agent in the polymer emulsion of the present invention is from about 0.01 to 0.5 percent, preferably from about 0.05 to 0.25 percent by weight of the polymer.
The first polymer emulsion or the second mon-omer emulsion, preferably both, additionally contain a latent crosslinking agent. By the term "latent cross-linking agent" is meant a polyfunctional monomer wherein a portion of the functionality enters into the polymerization with other monomers in the polymer emul-sion, with the residual functionality causing cross-linking of the polymer upon the subsequent application of energy generally by applying heat, e.g. by drying and curing of the latex particles, often in the pres-ence of a catalyst, or by applying radiation, the la-tent crosslinking agent provides thermosetting charac-teristics to the polymer emulsion. Upon the subsequent application of energy the latent crosslinking agent forms and insoluble crosslinking network, with the crosslinking being triggered generally by heat or radi-ation after the polymer emulsion has been formed and applied. Examples of latent crosslinking agents are:
N-alkylolamides of alpha, beta ethylenically unsatu-rated carboxylic acids having 3-10 carbons, such as N-methylol acrylamide, N-ethanol acrylamide, N-propanol acrylamide, N-methylol methacrylamide, N-ethanol meta-.

g crylamide, N-methylol maleamide, N-methylol maleamic acid, N-methylol maleamic acid esters; the N-alkylol amides of the vinyl aromatic acids, such as N-methylol-p-vinylbenzamide and the like; also N-(alkoxymethyl) acrylates and methacrylates, where the alkyl group has from 1-8 carbon atoms, such as N-(methoxymethyl) acryl-amide, N-(butyoxymethyl) acrylamide, N-(methoxymethyl~
methacrylamide, N-(butoxymethyl) allyl car~omate and N-(methoxymethyl) allyl carbamate, and mixtures of these monomers with allyl carbamate, acrylamide or methacryl-amide. EpOxy containing monoethylenically unsaturated compounds, such as glycidyl acrylate, glycidyl metha-crylate and vinyl glycidyl ether function as latent crosslinking monomers in conjunction with mono- and di-ethylenically unsaturated carboxylic acids, such as acrylic methacrylic and itaconic acid, when catalyzed with an alkaline catalyst, such as potassium or sodium carbonate, diethylenetriamine and the like. Hydroxy-ethyl acrylate, hydroxypropyl acrylate and the corre-sponding methacrylates provide latent crosslinking when combined with N-alkylolamides of alpha, beta ethyleni-cally unsaturated acids having 3-10 carbon atoms or with the acids themselves by ester formation. Another ~roup of latent crosslinking monomers is described in U.S. Patents No. 3,678,098 and 4,009,314. These are cationic chlorohydrin compounds having the following formula:

~CH
CH = C- COO-A- N - CH - CH - CH ~Y)where R-methyl or H
¦ 2 ~ 1 2 A-alkylene CH OH X X,Y=halogen 3 ~ .
The crosslinking reaction of these monomers is also catalyzed by ~he alkaline compounds mentioned above.
. . , " :~

:

ss The amount of latent crosslinking agent in the polymer of the present invention is about from 0.5 to 10 per-cent, preferably from about 2 to 6 percent by weight of the polymer.
The emulsions of the present invention are prepared in the presence of suitable anionic, cationic or nonionic emulsifiers or mixtures thereof. Optional-ly, protective colloids, illustrated by polyvinyl alco-hol and hydroxyethyl cellulose, may also be present.
Suitable nonionic emulsifying agents include alkylphe-noxypolyethoxyethanols having alkyl groups of about 10 to 60 carbon atoms and 10 to 6 or more oxyethylene units, such as octylphenoxypolyethoxyethanols, methyl-octylphenoxypolyethoxyethanols, nonylphenoxypolyethoxy-ethanols, dodecylphenoxypolyethoxyethanols; also ethy-lene oxide derivatives of long chained carboxylic acids, such as lauric, myristic, palmitic, oleic, and stearic acid, containing 10 to 60 oxyethylene units per molecule; also analogous ethylene oxide condensates of long-chained alcohols, such as octyl, decyl, lauryl, stearyl and cetyl alcohols, ethylene oxide derivatives of etherified or esterified polyhydroxy compounds hav-ing a hydrophobic component, such as lauric, myristic, palmitic, oleic, and stearic acid, containing 10 to 60 oxyethylene units per molecule; also analogous ethylene oxide condensates of long-chained alcohols, such as octyl, decyl, lauryl, stearyl, and cetyl alcohols, eth-ylene oxide derivatives of etherified or esterified polyhydroxy com~ounds having a hydrophobic hydrocarbon chain, such as sorbitan monostearate containing 10 to 60 oxyethylene units; also block copolymers of ethylene oxide and propylene oxide comprising a hydrophobic propylene oxide section combined with one or more hy-drophilic ethylene oxide sections. ~uitable anionic ~ 5 emulsifying agents include higher fatty alcohol sul-fates, such as sodium lauryl sulfate the alkylaryl sul-fonates, such as the sodium salt of t-octylphenyl sul-fonate, the sodium dioctyl sulfosuccinates, disodium fatty alkyl alkanolamide sulfosuccinate, and the ammo-nium salt of a sulfate or phosphat~ ester of an alkyl-phenoxy poly(ethyleneoxy) ethanol, where the oxyethy-lene content is from 3 to 30 moles per alkylphenol.
Suitable cationic emulsifiers include N-dodecyl tri-methyl ammonium chloride, and N-vinyl benzyl trimethyl ammonium chloride and the like. Generally, the polymer emulsions of this invention contain from 1 to 10 per-cent, preferably from 3 to 6 percent, emulsifiers based on the weight of the monomers (solids).
In the polymerization process used in making the first polymer emulsion of the invention an aqueous phase is prepared first containing water, a small por-tion of a nonionic emulsifier, sometimes also mixture of anionic and nonionic emulsifiers, and a very small amount of ferrous sulfate, being a redox component in the finishing catalyst system for the polymer emulsion.
The aqueous phase is purged well with nitrogen, and heated to polymerization temperatures (e.g. 60 to 70C). A small portion of monomer, is then added fol-lowed by a suitable amount of initial catalyst, most often from about 1 to 3 percent based on the weight of the initial monomer charge. Often it is advantageous to use potassium persulfate as the catalyst because the resulting polymer has better resistance to heat discol-oration. But sodium or ammonium persulfates can also be used. After the emulsion polymerization has initi-ated, the rest of the monomers are gradually added to the reaction mixture, often emulsified in water togeth-er with the latent crosslinking agents and the active crosslinking agents. Generally, the gradual addition of the monomers is carried out over a time period of one to five hours. More catalyst solution is also added gradually to maintain the polymerization reac-tion. Often cooling is applied to the reaction vessel by means of a waterbath to remove the excess heat of polymerization. Usually, a total of 0.2 to 1 percent of catalyst based on the weight of the monomers, is added over the course of the emulsion polymerization.
After all the monomer has been added optionally a small amount of an organic peroxide, such as t-butyl hydro-peroxide and cumene hydroperoxide, and the like can be added for the finishing step, together with a small amount of a reducing agent, such as sodium metabisul-fate, sodium formaldehyde sulfoxylate and zinc formal-dehyde sulfoxylate. In place of an organic peroxide, hydrogen peroxide or persulfates, such as potassium, sodium or ammonium persulfates may also be used. The terminal catalyst necessary to finish the reaction is generally about 10 to 30 percent by weight of the total amount of catalyst consumed during the reaction. The reducing agent is ordinarily added in the necessary equivalent amount. Normally no buffering agent is re-quired to keep the pH between 3 and 5. If necessary, dilute ammonia may be added from time to time to adjust the pH within those limits. Other auxiliary agents may be added to the finished polymer emulsion, such as de-foamers, biocides and the like.
After the first polymer emulsion is cooled a second monomer emulsion is introduced into the reactor as fast as possible containing water, monomer or mix-ture of monomers, emulsifiers and a small amount of ferrous sulfate (redox component).

q;455 Following thorough mixing and equilibration (e.g. 10 to 60 minutes) of the first and second emul-sions a second polymerization step is initiated by the addition of catalyst solution and then the reducing solution.
The polymer emulsion of this invention gener-ally contains from 5 to 95%, preferably 20 to 80~ on a solids by weight basis of the first polymer emulsion.
The polymer emulsions of the present inven-tion are useful as binders, adhesives and coatings.
These polymer emulsions when used as binders provide high temperature resiliency to bonded fiberfill prod-ucts. The polymer emulsions are useful in bonding tex-tile fibers in a fiberfill product or other nonwoven product or even in traditional woven or knitted textile fabrics. Generally, based on the weight of the fiber-fill product the binder can comprise 2 to 50%.

A polymer emulsion is prepared as follows containing a polymer which is an interpenetrating net-work of polyvinyl acetate and polystyrene.
The following was charged to a 100 gal. (379 liter) stainless steel pilot reactor equipped with a variable agitator, temperature control system, feed-pumps, means for purging the reactor with nitrogen, and a jacket for heating and cooling:

Water 150 lbs. (63.5 kg) Trito~ 305 (1) 6 lbs. 10 oz. (3 kg) Emcol K8300 (2) 8 oz. (227 g) The contents of the reactor were heated to 67C after which the reactor was purged with nitrogen. After the ~ ' ' _ SS

heat-up and purge the following monomer was added ~o the reactor:

Vinyl acetate 26 lbs. (11.8 kg) This was followed by the addition of the initial cata-lyst solution:

Water 10 lbs. (4.5 kg) Potassium persulfate 8 oz. (227 g) The polymerization initiated within 5 minutes as indi-cated by a 2C rise in temperature of the reactor. The following first monomer emulsion, made up previously, was then added gradually by means of an addition pump at a rate of 1.56 lbs. (.71 kg)/minute over a 3 1/2 hour period:

Water 58 lbs. (26.3 kg) Emcol X8300 (2) 8 lbs. 8 oz. (3.9 kq) Triton X 305 (1) 2 lbs. 4 oz. (1.0 kg) N-Methylol acrylamide (49%)19 lbs. (8.6 kg) Acrylamide (50%) 2 lbs. (0.9 kg) Monoethylmaleate 12 oz. (340 g) JPS Sequesterant (5)5 oz. (142 g) Vinyl acetate 238 lbs. (108 kg) Triallyl cyanurate5 oz. (142 g) The temperature of the reactor content was allowed to rise to 80C and was maintained there by the gradual addition at a rate of 0.362 lbs. (0.164 kg)/minute over a 3 1/2 hour period of thé foliowing catalyst solution:

~ q~5 Water 75 lbs. (34 kg) Potassium persulfate 9 oz. (255 g) After 3 1/2 hours, when all the first monomer emulsion and catalyst solution had been added to the reactor the following finishing catalyst solution was added:

Water 1 lb. (.45 kg) Potassium persulfate 2 oz. (57 g) The temperature of the batch was maintained at 80C for an additional 30 minutes, after which the first polymer emulsion was cooled at 60C. At this point a second monomer emulsion was introduced into the reactor, as fast as possible, in about 10 minutes, and mixed with the first polymer emulsion. The second monomer emul-sion had been prepared before containing:

Water 50 lbs. (22.7 kg) E~col K8300 (2) 3 lbs. (1.4 kg) Triton X 305 (1) 3 lbs. (1.4 kg) N-Methylol acrylamide (49%)5 lbs. (2.3 kg) Styrene 100 lbs. (45.4 kg) Ferrous sulfate 1 gram (28 g) The temperature of the reactor content was maintained at 60C and allowed to equilibrate (1/2 hour) while the reactor was again purged with nitrogen after which the following catalyst solution was added to the reactor:

Water 19 lbs. (8.6 kg) Potassium persulfate 1 lb. (0.5 kg) t-butyl hydroperoxide 8 oz. (227 g) ~?~ 55 The second polymerization step was initiated by adding half of the following reducing solution:

Water 16 lbs. (7.3 kg) Hydrosulfite AWC (3) 6 oz. (170 g) The temperature of the batch increased rapidly to 80C, at which point the other half of the reducing solution was added to the reactor. The temperature of the batch was then maintained at about 80C for an additional 30 minutes, after which the polymer emulsion was cooled to room temperature. The following post-add was then added:
Water 4 lbs. (1.8 kg) zinc nitrate solution in water 50% 14 oz, (397 g) Phosphoric acid 7 oz. (198 g) followed by a second post-add as follows:

Water 2 lbs. (0.9 kg) Proxel GXL (4) 1 1/2 oz. ~43 g) Formaldehyde (37%) 1 1/2 oz. (43 g) A total of 55 lbs. (24.9 kg) of rinsewater was added to the emulsion for clean up of the pumps and lines.
Notes: (1) Triton X 305 is a 70 percent solution in water of an octylphenoxypolyethoxyethanol containing 30 moles of oxyethanol per mole of octyl phenol. It is supplied by the Rohm & Haas Company.
~2) Emcol R8300 is a 40 percent solution in water of disodium fatty alkyl alkanolamide s sulfosuccinate supplied by the Witco Chemi-cal Company.
(3) Hydrosulfite AWC is a brand of sodium formaldehyde sulfoxylate supplied by the Diamond Shamrock Company.
(~) Proxel GXL is a biocide supplied by the ICI Company.
(5) JPS Sequesterant is a brand of diethy-lenetriamine pentaacetic acid supplied by the Intex Products Company.

The polymer emulsion thus obtained had the following properties:

solids (30 min. at 130C drying) 46.3%
pH 3.5 viscosity (Brookfield at 50 RPM)78 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30C) (6) 1.5 dl/g particle size (by light transmis-sion (7) 0.33 microns Notes: (6) In measuring the intrinsic viscosity, a 1 ml sample of the polymer emulsion is added to 100 ml of N-methyl pyrrolidone, and the mixture is agitated and filtered. The flow-time of the solution so prepared is then compared to 30C with the flowtime of the N-methyl pyrrolidone solvent using a Ubbelohde viscometer (obtained from the Cannon Instrument Company) the relative vis-cosity is the fraction obtained by dividing the flowtime of the solution by the flowtime of the solvent. The Huggins equation is then used to calculate the intrinsic viscos-s ity from the relative viscosity measurement and from the polymer solids content in grams per 100 ml of solution. The use of the Huggins equation for intrinsic viscosity calculations is described in detail in the "Encyclopedia for Polymer Science and Tech-nology", (Wiley, New York, 1971) Vol. 15, page 634.
(7) The particle size was measured by light transmission using a Beckman spectrophotome-ter (Spectronic 20). The method is de-scribed in detail in "Official Digest of the Paint and Varnish Industry", February 1959, pages 200-213.

A polymer emulsion is prepared containing a polymer which is an interpenetrating network of polyvi-nyl acetate and polymethyl methacrylate.
The following was charged to a 100 gal. (379 liter) stainless steel pilot reactor equipped with a variable agitator, temperature control system, feed-pumps, means for purging the reactor with nitrogen, and a jacket for heating and cooling:

Water 140 lbs. (63.5 kg) Triton X 305 (1) 6 lbs. 10 oz. (3 kg) Emcol K8300 (2) 8 oz. (227 g) ;; ' ~ ~:
The contents of the reactor were heated to 67C after which the reactor was purged with nitrogen. After the heat-up and purge the following monomer was added to the reactor:

-Vinyl acetate 26 lbs. (11.8 kg) This was followed by the addition of the initial cata-lyst solution:

Water 10 lbs. (~.5 kg) Potassium persulfate 8 oz, (~27 g) The polymerization initiated within 5 minutes as indi-cated by a 2C rise in temperature of the reactor. The following ~irst monomer emulsion, made up previously, was then added gradually by means of an addition pump at a rate of 1.56 lbs. (.71 kg)/minute over a 3 1/2 hour period:

Water 58 lbs. (26.3 kg) Emcol K8300 (2) 8 lbs. 8 oz. (3.9 kg) Triton X 305 (1) 2 lbs. 4 oz. (1.0 kg) N-Methylol acrylamide (49%)19 lbs. (8.6 kg) Acrylamide (50%) 2 lbs. (0.9 kg) Monoethylmaleate 12 oz. (340 g) JPS Sequesterant (5)5 oz. (142 g) Vinyl acetate 238 lbs. (108 kg) Triallyl cyanurate5 oz. (142 g) The temperature of the reactor content was allowed to ~ rise to 80C and was maintained there by the gradual : addition at a rate of 0.362 lbs. (0.164 kg)/minute over a 3 1/2 hour period of the following catalyst solution:

`~ Water 75 lbs. (34 kg) ~ ~ Potassium persulfate 9 oz. (255 g) .

~ S5 After 3 1/2 hours, when all the first monomer emulsion and catalyst solution had been added to the reactor the following finishing catalyst solution was added:

Water 1 lb. (.45 kg) Potassium persulfate l l/2 oz. (57 g) The temperature of the batch was maintained at 80C for an additional 30 minutes, after which the first polymer emulsion was cooled at 60C. At this point a second monomer emulsion was introduced into the reactor as fast as possible, in about lO minutes, and thoroushly mixed with the first polymer emulsion. The second monomer emulsion had been prepared before containing:

Water 50 lbs. (22.7 kg) Emcol R8300 (2) 3 lbs. (1.4 kg) Triton X 305 (1) 3 lbs. (1.4 kg) N-Methylol acrylamide (49%)5 lbs. (2.3 kg) Methyl methacrylate 100 lbs. (45.4 kg) Ferrous sulfate 1 gram (28 g) The temperature of the reactor content was maintained at 60C and allowed to equilibrate (about l /2 hour), while the reactor was again purged with nitrogen after which the following catalyst solution was added to the reactor:

Water 19 lbs. (8.6 kg) Potassium persulfate 1 lb. (0.5 kg) t-butyl hydroperoxide 8 oz. (227 g) ? ~ 5 The second polymerization step was initiated by adding half of the following reducing solution:

Water 16 lbs. (7.3 kg) Hydrosulfite AWC (3) 6 oz. (170 g) The temperature of the batch increased rapidly to 80C, at which point the other half of the reducing solution was added to the reactor. The temperature of the batch was then maintained at about 80C for an additional 30 minutes, after which the polymer emulsion was cooled to room temperature. The following post-add was then added:
Water 4 lbs. (1.8 kg) Zinc nitrate solution in water 50%14 oz. (397 g) Phosphoric acid7 oz. (198 g) followed by a second post-add as follows:

Water 2 lbs. (0.9 kg) Proxel G~L (4) 1 1/2 oz. (43 g) Formaldehyde (37%) 1 1/2 oz. (43 g) A total of 60 lbs. (24.9 kg) of rinsewater was added to the emulsion for c}ean up of the pumps and lines.

The polymer emulsion thus obtained had the following properties:

solids (30 min. at 130C drying) 45.0%
pH 4.0 viscosity (Brookfield at 50 RPM) 32 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30C) (6) 2.3 dl/g . 55 particle size (by light transmis-sion ~7) 0.27 microns A typical fiberfill product for quilt stuff-ing was constructed of 6 denier 2" staple length poly-ester fiber with garnetted and crosslapped webs to a weight of 4 oz./yd.2. This web was then spray bonded wit a commercially available polyvinylacetate emulsion polymer (SUNCRY~W 41SP from Sun Chemical Corpora-tion), and the polymer emulsion as prepared in Examples 1 and 2, producing a final fiberfill product composed of 82% fibers and 18% bonding polymer.
The binder mix is prepared in a tank by di-luting the emulsions with water to a 22% nonvolatile content. This mix is pumped with reciprocating airless pumps at a pressure of 300 psi and delivered through spray nozzles of .018" diameter which traverse the polyester fiber web. The polyester web is passed under the traversing sprays so as to achieve a uniform appli-cation of the bonding mix. The web and applied mix are passed through a forced air oven to remove the water and coalesce the binder polymer onto the fibers. The web is turned over and the process repeated on the back side. Finally the web is passed through the oven a third time to cure the binder, rendering it durable and resistant to water and solvent interactions.
- The residual loft value was simulated by the following test. Ten inch by ten inch squares of the fiberfill material are cut and stacked vertically. The height of this stack is measured (Hl). The stack is then compressed by placing weights on top of the stack.
A typical weight of 20 pounds usually reduces the ini-tial stack height by 50 to 75%. The stack is left in ~...

`5 this compressed state for a period of time (1 hour is typical) at a stated temperature and then the weight is removed. The stack of fiberfill is allowed to recover for a further period of time (10 minutes is typical?
and the height is again measured tH2 ) . The % recovery is stated as a ratio of the final height to the initial height: H2 x 100 = % recovery.
Hl Table 1 shows % recovery values of a 6 layer stack compressed with 0.2 psi (20 lbs. on a 10" x 10"
square) for 16 hours and then allowed to recover for 1 hour at the stated temperatures.

Table 1 Polvvinyl acetate ExamPle 2 Exam~le 1 72F 85% 85% 85%
110F 37% 46% 59%

Although all the binders~are affected by temperature the polyvinyl acetate bonded fiberfill loses more loft at 110F.

A more detailed study was made of the binder utilizing the polymer emulsion prepared in Example 1 on a slightly different fabric, a 50/S0 blend of 6 and 15 denier polyester. Web preparation and bonding were similar to Example 3. Finished fiberfill weight for this furniture pad material was 18 oz./yd.2 with a fiber content of 81% and a binder content of 19%.
The same loft recovery test was conducted at 120F with compression for 6 hours under various com-pression loads and recovery measured both immediately and after 6 hours. Again the polymer of Example 1 shows considerably more loft recovery at this tempera-ture under all compression loads as compared to a bind-er utilizing a polyvinyl acetate emulsion polymer (PVAC) as shown in Table 2.

Table 2 Compression ~ inq 0.02 PSi 0.05 PSi 0.15 PSi polymer type PVAC Example 1 PVAC Example 1 PVAC Example 1 immediate recovery 69% 77% 55% 68% 14% 27%
6 hour recovery 69% 80% 58% 70% 16% 29%

SUPPLEMENTARY DISCLOSURE
. . .

Another area in which polymer binders are useful is in the manufacture of glass fiber mats.
Nonwoven fiber mats made from glqss staple fibers are finding uses in many markets. The attributes of glass fiber include non-combustibility, inertness to aqueous and most solvent environments, high tensile strength per unit weight, among others, which have led to glass fiber use in building products (e.g. roofing materials, insulation, and flooring), home furnishing, protective apparel and fabrics, and filtration materials. Glass fiber mats are used alone (as in insulation or filtra-tion constructions) in conjunction with other fabrics (as in drapery or apparel constructions) or as part of an intimate joining with other materials (as in roofing shingles or vinyl flooring). In any of these ultimate uses the strength and integrity ~f the glass fiber mat is very important to the successful performance of the finished article.
Glass fibers themselves are known for their high tensile strength and inertness to reaction with other materials. Since they are generally not avail-able in crimped form, these features make bonding the glass fiber mats into integral networks of adequate strength, flexibility and toughness a difficult task.
This bonding is customarily accomplished with polymer emulsions or other thermosetting resins such as urea formaldehyde, melamine formaldeh~de and phenol formal-dehyde resins and the like.
~30 Insulation products re~uire a maximum dead air space per unit weight. This must not only be .

~3 : ~
~ - 25 -achieved in the initial production, but be retained after the insulation product has been compres~ed for storage and shipment and subsequently placed in service as insulation in a building or machinery construction.
The binding chemical in this case must not distort or deform in various handling operations. To date, urea-formaldehyde resins have provided this binding function most economically.
Nonwoven fabrics cover a wide array of products including consumer goods like mattress dust shields, disposable diaper cover fabrics, cleaning towels, carpets, draperies and industrial and commer-cial goods like wipe cloths, tirq cords, conveyor belts, hospital fabrics, etc. The ability to engineer cost-effective fabrics through one or several nonwoven production processes have allowed for rapid growth of nonwoven textiles in recent years. The technology for nonwoven production includes filament or staple fibers processed through a dry or wet-lay sheet formation step and bonded by thermal, mechanical or chemical means.
Lamination of nonwovens to other nonwovens, film sheets or traditional woven or knitted textiles are often still classified as nonwovens.
One of the major nonwoven bonding methods is to treat a staple or filament fiber sheet with an emul-sion polymer. When the emulsion is dried or otherwise reduced (coacervation) the polymer forms intimate bond-ing of the fibers. This polymer deposition modifies the strength, stiffness, environmental resistance, elongation and many other characteristics of the fiber fabric sheet. The fiber can be from a great variety of the fiber fabric sheet. The fiber can be from a great , B

~ 55 variety of compositions, e.g. rayon, wood pulp (cellu-lose), cotton, nylon, polyester, glass and graphite.
In the case of carded staple fiber, the polymer usually contributes most of the strength and toughness charac-ter in the resulting nonwoven. In wet-laid wood pulp fiber products, the polymer is able ~o provide the nonwoven with strength and resistance to aqueous and solvent environments which the untreated nonwoven would not have. In glass mat, nonwovens traditionally bonded with a urea-formaldehyde resin, addition of emulsion polymers alters the toughness of the resulting non-woven. Even in filament or staple fiber nonwovens which are bonded by mechanical (i.e. needle punching) or thermal (e.g. spun bonded) techniques and are formed into useful nonwoven fabrics without a chemical treat-ment, an additional application of an emulsion polymer can enhance or produce other valuable characteristics such as stretch resistance or non-slip character.
A great variety of emulsion polymers have been used to treat nonwovens. Traditional polymer - compositions have been based on: acrylate and metha-crylate ester copolymers; styrene-acrylate ester copol-ymers; styrene-butadiene copolymers; acrylonitrile copolymers of the above; vinylacetate polymers; vinyl-acetate-acrylate ester polymers; vinylacetate-ethylene copolymers; vinyl chloride polymers; vinyl chloride-ethylene copolymers and vinyl chloride-acrylate ester copolymers. All the above emulsion polymers have found use in nonwoven fabrics based primarily on the particu-lar characteristics which the polymer can contribute to the nonwoven. Some are used because they simply con-tribute stren~th at the lowest cost level. Particular 2~

5~5 examples include (1) the use of an acrylate ester co-polymer to bond polyester staple fiber for quilt stuff-ing and insulation; (2) the use of a vinylacetate-ethy-lene copolymer to give wet strength to wood pulp non-wovens used as paper towels; (3) the use of a vinyl-chloride based polymer to bond staple polyester fibers for flame retardant filter media; and (4) the use of a styrene-butadiene copolymer to bond high denier nylon fibers for extra tough floor polishing fabrics.
The polymer emulsion can also be used as a binder of fabric or fibers for other nonwoven products including insulation, filters, construction fabrics, roofing materials, paper towels, carpets as well as other nonwoven fabrics.
In the preparation of ~ coated cellulosic web, e.g. a paper web, there is used a pigment, such as clay or the like, sometimes with other materials such as, for example, a soluble pyrophosphate which may act to disperse the pigment in water and stabilize the pigment in water. This mixture, commonly termed a pigment "slip" or, since it usually contains clay, a clay "slip", is then compounded with a binder or adhe-sive material to produce a composition known in the art as a coating "color", which is useful for coating a cellulosic web, e.g. a paper or paperboard web. Sub-stantial quantities of the binder are used, and accord-ingly, the composition and characteristics of the bind-er are of great importance in de~ermining the ~ualities of the finished coated web. It is important that the binder contributes to the coating or the finished coat-ing web a high degree of brightness, smoothness and gloss, and a good finish and feel after calendaring.
B

n addition to these basic qualities required in coat-ings, the coating color must flow smoothly and evenly so that it can be applied to the cellulosic web at sufficiently high speeds to be economical in ordinary coating processes; and the coating must have high strength, to permit subsequent printing on the coated paper without "picking, n i.e. it must have good "pick"
characteristics.
Polymer emulsions are useful as a coating binder for paper and paperboard. Paper is coated to provide a smoother surface with lncreased strength, whiteness and absorbability in order to provide a bet-ter surface on which to print. Coating formulations for paper and paperboard can contain a variety of bind-ers including all-latex binders, protein-latex binders, all-starch binders or latex-starch blends. The end use of the paper and, in particular, the method by which it will be printed, may determine which binder type is used in the coating. The major printing method is the offset method in which both water (fountain solution) and an oil based ink are applied to the paper coating.
The rate of absorption of the water layer and the ink into the coating is critical to ~roducing a desirable high quality printing.
Styrene-butadiene copolymers are commonly used latex binders, followed by polyvinylacetate, vinylacetate-acrylic copolymers, ethylene-vinylacetate copolymers and all acrylic polymer emulsions. Styrene-butadiene and vinylacetate binders are widely used because of their low cost. The major drawback of sty-rene-butadiene binders is the poor water absorption giving high SIWA brightness values. High SIWA (simul-:::

2g .

~2964sS

taneous ink and water absorption test) brightness val-ues mean the coating did not absorb the initially ap-plied water layer and the subsequent ink application failed to penetrate this layer and absorb into the coating. The incomplete ink covqrage produces a weak or spotty image. Vinyl acetate binders are often too water absorbent, resulting in press roll fountain solu-tion milking. This problem is the converse of the high SIWA brightness problem. Fountain solution milking occurs when the coating absorbs so much water (fountain solution), that the coating becomes solubilized in the fountain solution and the binder and clay so dissolved give the solution a ~milky" appearance. This condition can be predicted by the Adams Wet Rub Test.
The polymer emulsion can also be used in a coating, especially as a coating binder for paper and paperboard. Other types of coatings in which the poly-mer emulsion would be useful include various industrial coatings such as maintenance coatings (e.g. for metal tanks, pipelines and other metal structures), coil coatings, can coatings, appliance coatings (e.g. for refrigerators, washing and drying machines), wood coat-ings (e.g. wood panels or furniture), floor coatings and sealers (e.g. floor polishes), automotive coatings (e.g. primers, top coats), leather coatings, concrete sealers and coatings, marine coatings, as well as trade sale coatings such as house points, both exterior and interior.
Another area in which polymer emulsions are useful is in a coating especially as a binder for in-dustrial and architectural coatings. Industrial and architectural coatings are applied to surfaces of all ~ 30 SS

types, such as metal, wood, concrete, stone, plastic, plasterboard, glass and the like, to provide protection and decoration. Polymer emulsions are now used by industry as the binder of choice in a great variety of waterborne coatings because they are environmentally very desirable. Since solvent emissions into the atmo-sphere are a major concern, waterborne coatings are preferred to reduce such solvent emissions. Although organic solvent based coatings can still be used, these coating systems have become increasingly uneconomical, because expensive antipollution devices, such as after-burners or solvent recovery devices, have to be in-stalled.
In architectural coatings which are for exterior coatings, acrylic polymer emulsions dominate because they have been used for many years and their outdoor properties such as ultraviolet resistance and lack of embrittlement with time have been proven on test fences and in actual practice for many years.
Other polymer emulsions such as vinyl acetate-ethylene-vinyl chloride terpolymers have also found increasing use in outdoor architectural coatings because they have also shown to possess excellent properties. Indoor architectural coatings mostly co~tain vinyl acetate-ethylene copolymer- or vinyl ace~ate-acrylic copolymer emulsions.
The polymer emulsions that are used for industrial coatings include polyvinyl acetate and poly-vinyl acetate copolymers for wood panel finishes, be-cause they can be sanded better than most acrylic coat-ings. Polyacrylates are used in maintenance coatings for metal tan~s and pipes, and as primers for automo-B

1~&455 biles. These are often deposited by electrocoating processes. Furniture finishes, appliance coatings and the like are also based on polyacrylates. There are some areas in the industrial coatings filed where poly-mer emulsions have not yet been successfully used such as in coil prime- and top coatinS~s. Coil coating prim-ers are applied to continuous co~ls of ~are metal, such a steel or aluminum stock, to protect the uncoated metal prior to fabricating the primed metal. Often a top coat is also applied so that the metal sheet is completely coated prior to sending it to a metal fabri-cator who converts it to useful metal products. It is important for coil coatings to withstand the rigorous fabricating process, when the coated metal is converted to articles such as metal cabinets and the like, with-out damaging the previously appIied coating. The coat-ed metal is often bent and drawn during the fabricating process and therefore must possess toughness and exten-sibility. Many coatings will se~arate from the metal in places during this process which often necessitates an expensive refinishing procedure. Although solvent-based coil coatings have been used predominantly in the past, economics and environmental considerations dic-tate that aqueous coil coatings, primers as well as topcoats, are most desirable for industrial use.
Printing inks will generally contain a pigment or dyestuff and a vehicle as well as supplemen-tal ingredients to impart special characteristics to inks such as driers, waxes, lubricants, reducing oils, antioxidants, gums, starches and surface active agents.
The function of the vehicle is to act as a carrier for the pigment and as a binder to affix the pigment to the ~ 55 printed surface. The vehicle ca~ contain in various combinations, resins, oils and sqlvents depending upon the printing method. For example a flexographic vehi-cle can contain either alcohols, water, or other fast evaporating solvents with suitable resins and ~ums, while a gravure vehicle can contain low boiling hydro-carbon solvents with gums and resins.
Printing inks use natural or synthetic resins to impart the properties of hardness, gloss, adhesion and flexibility which is important in the formulation of binders for the pigments. Synthetic resins are prepared by polymerization involving condensation or addition reactions between relatively small molecules.
Various synthetic resins are uti~ized in different ink applications. For example, pure phenolic resins are used in conjunction with tung oil as a varnish for letterpress and lithographic inks, rosin modified phe-nolic resins have widespread use in all types of ink vehicle systems; alkyd resins are used in paste inks;
polystyrene resins and copolymers thereof (e.g. with maleic anhydride) can be made water soluble for use in water based inks; thermoplastic polyamides are used in liquid inks; and acrylic and methacrylic polymers and copolymers thereof are used in flexographic, photogra-vure and tinprinting inks and high gloss lacquers. The resins are often used in combina~ion with other resins or film forms to impart the properties desired for a particular application.
Another area in which polymer emulsions are useful is in industrial and household adhesives espe-cially as bases for white glues, wood adhesives, pack-aging adhesives, film and foil adhesives and pressure sensitive and contact adhesives.

B

Adhesives can be prepared from a wide variety of synthetic organic polymers. Often these are blended to provide adhesive compositions displaying specific properties desired by the user. Adhesives containing vinyl acetate emulsions and copolymers thereof possess excellent adhesion to many porous and nonporous sub-strates such as paper, wood, metal, foil, plastic, ceramic, cloth, felt, leather, cqrk, glass and the like. Often such emulsions can be used with little, if any, modifications. Sometimes, however, it is neces-sary to alter either their physical properties and/or their application characteristics. To that end thick-eners, plasticizers, tackifyers and other polymer emul-sions are often added.
Wood adhesives generally contain polymer emulsions, primarily polyvinyl acetate emulsions, which have iar~ely replaced the traditionally used wood adhe-sives which were based on animal glues. The polyvinyl acetate emulsions can be used as is, especially if polyvinyl alcohol is present as the emulsifier. Often additional polyvinyl alcohol is a!lso added later to increase the track and the heat resistance of the adhe-sive.
Laminating adhesives are used to produce composites of plastic films consisting of polyethylene, polypropylene, polyvinylidene chloride, polystyrene, polyester, and polyvinyl alcohol-ethylene films. The laminates are often used in food packaging applica-tions. Laminating adhesives are also used to bond polyvinyl chloride films to wood to form decorative panels. Many laminating adhesives consist of plasti-cized homopolymer- and copolymer emulsions of vinyl ~ 55 acetate, such as vinyl acetate-ethylene copolymer emul-sions or vinyl acetate-butyl acrylate copolymer emul-sions.
Packaging adhesives arq used in the production of paper cartons and plastic bags for food packaging, corrugated cardboard boxes for general pack-aging use, blister packages and the li~e, because they combine excellent specific adhesion with ease of use on high speed packaging machinery. Here also homo- and copolymer emulsions of polyvinyl acetate are widely used.
Pressure sensitive and contact adhesives are used on pressure sensitive tapes, to adhere labels to metal and glass objects, such as cans and bottles, to laminate plastic surfaces to woot~, and like applica-tions. These adhesives often arq based on acrylate copolymer emulsions, vinyl acetate copolymer emulsions, styrene-butadiene and chloroprene emulsions, and the like.
Although copolymerization of vinyl acetate with vinyl acrylates, ethylene, vinyl chloride and maleate- and fumarate esters of lower alcohols can provide many superior polymers when they are used as adhesive bases, there remains the problem of not being able to readily copolymerize styrene, a very economical monomer, and acrylonitrile, methyl methacrylate, or chloroprene with vinyl acetate, alone or in combination with ethylene, in order to increase the modulus at elevated temperatures of the resulting polymer. One of the disadvantages of vinyl acetate polymers in general is its lack of hardness at elevated temperatures, that is, the vinyl acetate polymers soften too readily when t .'p ' ',., ~ 5~

the temperature of use is increased even modestly, for example, to 50DC. The reason for this thermoplasticity at elevated temperatures is the relative low ~lass transition temperature of polyvinyl acetate of about 30C. It has long been desired to raise the modulus at elevated temperatures of vinyl acetate homo- and copol-ymers, but no economical comonomer to accomplish the hardening of vinyl acetate polymer is commercially available. Styrene would be a very desirable como-nomer, because, besides having e~cellent physical prop-erties such as clarity and stiff~ess at elevated tem-peratures, it is also a very economical comonomer. It is, therefore, desirable to use as much as possible of styrene and the other low cost monomers together with vinyl acetate in adhesive formulations.
In addition, the polymer emulsion is useful in preparing superior and economic adhesive bases, for use in household and industrial applications.
This polymer emulsion is useful in adhesive compositions, particularly adhesive compositions used as wood adhesives, packaging adhesives, film and foil adhesives and pressure sensitive and contact adhesives.
The first polymer emul~ion heretofore described can be formed by emulsifying a polymer.
Examples of emulsified polymers include polyethylene emulsions, polyester emulsions, polyurethane emulsions and the like.
In some embodiments, the polymer present in the first polymer emulsion is either polymethyl, metha-crylate, polyvinyl acetate, polybutylacrylate, vinyl-chloride-ethylene copolymer, vinylacetate-ethylene copolymer, polystyrene or polyacrylonitrile or copoly-mers of these with other monomers mentioned above.

~ 9~55 The second monomer can either be added as an emulsion to the first polymer emulsion or as monomers which are emulsified during mixing with the first-poly-mer emulsion. Water, emulsifier and a small amount of ferrous sulfate (redox component) can be added either with the second monomer or after equilibration. The second monomer emulsion can contain either styrene, methyl methacrylate, acrylo-nitrile or butylacrylate, or mixtures thereof.
Catalyst solution (and redox component in certain systems) is added gradually to maintain the polymerization reaction. Often cooling is applied to the reaction vessel by means of a waterbath to remove the excess heat of polymerization. Usually, a total of 0.2 to 1 percent of catalyst (0.2 to 1% of redox compo-nent in certain systems) based on the weight of the monomers, is added over the cour~e of the emulsion polymerization.
Normally, no buffering agent is required to keep the pH between 3 and 5, If necessary, dilute ammonia or a dilute solution of sodium acetate or sodi-um bicarbonate may be added from time to time to adjust the pH within those limits, When used as a nonwoven binder or adhesive, the first and second polymer emulsions preferably con-tain 30-90% and 10-70%, respectively, on a solids by weight basis, when as a coating composition or printing ink, 60-95% and 5-40%, respectively.
The polymer emulsions ,Ire also useful as binders for a wide array of nonwr~ven products including insulation, filters, construction fabrics, roofing materials, paper towels, carpets and other nonwoven $55 fabrics. These binders can also contain thermosetting resins such as urea-formaldehyde resins, glyoxal res-ins, melamine resins and phenol formaldehyde resins, as well as wetting agents (surfactants such as polyethy-leneoxideoctylphenol), colorants (pigments such as phthalocyanine blue), defoamers (oil emulsions), foam aids (e.g. sodium layryl sulphate), biocides, as well as extenders (e.g. calcium carbonate, clay, kaolin, etc.) and other specialty performance additives (e.g.-silicon emulsions for friction control).
When the resultant polymer emulsion is to be used in a coating, preferred pol~mer combinations in-clude wherein the first polymer network contains either a polyvinylacetate, a vinylacetate-ethylene copolymer, a polyvinyl propionate or a vinylacetate-acrylic copol-ymer (preferably where the acrylic comonomer is a methyl, ethyl, butyl or 2-ethyl hexyl acrylate) and wherein the second polymer network contains either polystyrene, an acrylonitrile-acrylate copolymer, a styrene-butadiene copolymer or a styrene acrylic copol-ymer. In a preferred polymer combination the first polymer contains an ethylene-vinylacetate copolymer and the second polymer contains polystyrene, preferably at level of 5 to 40% on a solids by weight basis of the emulsion.
The coating containing the polymer emulsion can be used to provide a smoother surface and increased strength, whiteness and gloss to a paper or paperboard product. In addition to the polymer emulsion binder, the coating can contain proteins, polyvinyl alcohols, alginates, resins or modified or unmodified starches as binders, Other conventional ingredients can be includ-ed in the coating such as pigments (including titanium dioxide and/or calcium carbonate), lubricants (e.g.
calcium stearate), insolubilizers (e.g. glyoxal resins to crosslink starch), defoamers, biocides (to pre~ent mildew), preservatives and the like. Paper can be treated with the coating by a va~iety of coating tech-niques including size press, air knife coating, blade coating, gravure coating, puddle coating, spray or kiss roll. Some specialty papers apply polymer emulsions with or without fillers with these processes. The unique characteristics of these specialty papers can be enhanced and/or deliYered at a lower cost by using the polymer emulsions of this invention. The unique char-acteristics of these specialty papers can be enhanced and/or delivered at a lower cost by using the polymer emulsions of this invention.
In preparing coating compositions the emulsions of the present invention are often prepared by copolymerizing the principal monomers also with specialty monomers to obtain speqial properties. Thus wet adhesion promoting monomers, corrosion inhibiting monomers, flame retarding monomers and dyestuff mono-mers can also be incorporated into the emulsion polymer by copolymerization with the principle monomers. Exam-ples of wet adhesion promoting monomers are disclosed in U.S. Patent No, 4,426,503; U.S. Patent No. 4,429,095 and U.S. Patent No. 4,260,533. Examples of corrosion inhibiting monomers are disclosed in U.S. Patent No.
3,202,534 and U.S. Patent No. 3,224,908. Examples of flame retarding monomers are disclosed in U.S. Patent No. 3,892,578 and U.S. Patent No. 4,386,036. Examples of dyestuff monomers are disclosed in U.S. Patent No.
3,557,048.

~.~
I ~ .~ ~
~ ~ 9 39 l~fi~55 An ethylenically unsat~rated carboxylic acid is also preferably added to the polymer emulsions to provide mechanical stability to ~he emulsion. General-ly, an ethylenically unsaturated mono- or dicarboxylic acid may be used to provide the carboxyl functionality to the copolymer. Examples of suitable acids include the monocarboxylic ethylenically unsaturated acids such as acrylic, crotonic, and methacrylic acids the dicar-boxylic ethylenically unsaturated acids such as maleicr fumaric, itaconic, and citraconic acid, as well as the half esters of these carboxylic acids with Cl-C12 alco-hols. Examples of these monomeric acids are monometh-ylmaleate, monoethylmaleate, monobutylmaleate, and mono(2-ethylhexyl)maleate and th~ like. The polymer emulsions preferably contain from 0.1 to 0.5 percent of unsaturated carboxylic acids based on the weight of the monomers (solids).
Because of their unique mechanical properties, such as dual glass transition temperatures and relatively high moduli with exceptional tou~hness and solvent resistance, the polymer emulsions of this invention are useful in coatings particularly as bind-ers in industrial and architectural coatings. The polymer emulsions of this invention provide coatings with improved impact resistance, wear and resistance to damage from bending when they arq used on metals, and improved resistance to dimensional changes and ability to be sanded when they are used as wood coatings.
Interior and exterior architectural coatings made with the polymer emulsions of this invention have exception-al scrubbability, They are also hydrolysis resistant which makes them suitable to coat concrete.

r.
.

.

SS

In general, coating formulations are prepared by first dispersing the prime pigments as well as the extender pigment, or a mixture of pigments in water.
Prime pigments include both rutile and anatase grades of titanium dioxide, and zinc oxide, as well as the color pigments: Hansa Yellow, phthalocyanine blue and green, quinacridones such as Red B, Red Y, Violet R, and Orange RK; also Cadmium Red, Chrome Yellow, Molyb-date Orange, Ferric Oxide, Carbo~ Black: also metallic pigments such as aluminum, bronzq and stainless steel flake. Extender pigments include calcium carbonate, calcium silicate, mica, clay silica, barium sulfate and the like.
Dispersants, both organic and inorganic types, are used to facilitate the dispersion of the pigments in water. Inorganic dispersants include, tetrapotassium pyrophosphate, potassium tripolyphos-phate and the like. Organic dispersants include, alka-li or ammonium salts of polycarboxylic acids, such as polymethacrylic acid, polyacrylic acid, and maleic anhydride-isobutylene copolymers; also ditertiary acetylenic glycols and the like. After the pigments are well dispersed other auxiliary materials are often added to the pigment slurry, for example, wetting agents, to facilitate the wetting of surfaces to be coated as well as wetting the hydrophobic pigments used in the coating. Wetting agents include surface active agents such as sulfosuccinates, ethylene oxide conden-sates of alkylphenols, and the like. Filming aids are-also often added to the coating. These include ethy-lene glycol monobutyl ether, diethylene glycol monobu-tyl ether, hexylene glycol, 2-ethylhexyl acetate and ~ 41 the like. Plasticizers are added often, such as dibu-tyl phthalate, dioctyl phthalate, to soften hard poly-mers more permanently. Defoameræ such as 2-ethyl hexa-nol are also employed when neede~. Thickeners are added to control the coating viscosity: these include high molecular weight polyacrylic acids; cellulosics, such as carboxymethylcellulose or hydroxyethyl cellu-lose, or polyvinyl alcohol. Biocides to prevent mil-dew, and preservatives to prevent degradation of thick-eners and surface active agents are also often added.
The polymer emulsion is then added to the pigment dis-persions with slight agitation, followed by the addi-tion of crosslinking resins such as malamine formalde-hyde or urea formaldehyde resins. The pH of the coat-ing is often ad~usted with amines such as triethanol amine or morpholine and the like, or aqueous ammonia solution.
The coating is applied by various coating methods, Coating methods are described in detail in the "Encyclopedia of Polymer Science and Engineering"
Second Edition, John Wiley, New York (1985, Volume 3, pages 552-615). They include roller coating, reverse roller coating, blade coating, knife coating, dip coat-ing, kiss roll coating, spray coating, electrodeposi-tion and often, application of the coating by paint brush or roller.
Industrial coatings are applied in a factory to various substrates such as all~minum- or steel sheets, or wood panels, also to automobiles, applianc-es, and machines, such as farm implements, and the like. Marine coatings are applied to ships and other surfaces coming in contact with water. Oil tanks, ~ 42 ~ 55 pipelines, fences and the like are often coated in place. Cans and bottles, made from both glass and plastic, can be coated in an automatic coating line.
Architectural coatings are those coatings which are put on structures such as houses and build-ings which are built using a variety of building mate-rials such as wood, metals, concrete, stone and the like. The polymer emulsions of this invention are ` particularly suited for coating these materials. Some times the coatings are used without pigments as so-called clear coatings.
The polymer emulsions of this invention, because of the aforementioned excellent physical prop-erties, and because of their generally lower cost, are uniquely suitable for a wide variety of coatings.
The polymer emulsions of this invention are also useful as binders in printing ink compositions.
The polymer emulsion provides a carrier for the pigment in the ink and acts as a binder in affixing the pigment to the printed surface. Printinq inks prepared with the polymer emulsions upon printing show high gloss and good heat resistance and coverage of the paper.
A printing ink composi~ion will contain generally 5 to 95%, preferably 20 to 60% of the polymer emulsion (wet basis, 45% solids) or 2 to 45%, prefera-bly 5 to 30~, of the polymer on a solids basis by total weight of the printing ink. The printing ink addition-ally contains pigment as well as supplemental ingredi-~ ents to impart special characteristics including iso-; 30 propyl alcohol, driers, waxes, lubricants, reducing oils, antioxidants, binders, gums, starches, surface active agents as well as other resins. In a preferred .

~ 43 '~

.

i L~ 55 embodiment the polymer emulsion is combined with one of the following resins to impart superior printing prop-erties: alkyds, urethanes, styrene-maleic anhydride resin and styrene-acrylic acid resins. In a preferred embodiment the printing ink is wqter-based ink and preferably a flexographic ink.
Because of their unique mechanical properties, such as dual glass transition temperatures and relatively high moduli with exceptional toughness, the polymer emulsions of this invention are useful in adhesives.
~ base for an exceptionally strong wood adhesive can be prepared by using as the first polymer network a vinyl acetate-ethylene copolymer emulsion having as the protective colloid polyvinyl alcohol, to which is added monomeric styrene, an active and/or latent crosslinking agent such as; divinyl benzene, triallyl cyanurate, N-methylol aqrylamide and the like, and optionally more protective colloids and emulsifi-ers. This mixture is then polymerized, resulting in a vinyl acetate-ethylene/styrene interpenetrating network (IPN). Suitable vinyl acetate- ethylene emulsions, useful to provide the first polymer network, may be prepared according to U.S. Patent Nos. 3,708,388 and 4,339,552. Commercially available vinyl acetate- ethy-lene emulsions may also be used as the first polymer network. Preferably, the polymer emulsions providing the first polymer network. Preferably, the polymer emulsions providing the first polymer network. Prefer-ably, the polymer emulsions providing the first polymer network have a glass transition ~emperature of -40 to +30C. The first polymer network should contain a B
~4 ~ 55 significant amount of gel (porti~n of polymer network which is insoluble in solvents for the polymer) gener-ally from 5 to 100%, preferably from 20 to 100% of the polymer network, indicating the polymer contains a crosslinked polymer network. In the case of polyvinyl alcohol protected emulsions, it is not always necessary to have an additional active crosslinking agent present in the polymer of the first network, since when vinyl acetate is polymerized in the presence of polyvinyl alcohol the resulting polymer contains extensive amounts of gel because of crosslinking of the polymer by a grafting reaction of vinyl ~cetate to polyvinyl alcohol and thus the polyvinyl a~cohol behaves like an active crosslinking agent. The polyvinyl acetate emul-sions generally contain from 0.5 to 6 percent, prefera-bly from 2 to 4 percent, of polyvinyl alcohol based on the whole emulsion. Other protective colloids,-such as hydroxyethyl cellulose, sodium carboxymethyl cellulose, water soluble styrenated acrylics, and polyvinyl pyrro-lidone may be substituted for the polyvinyl alcohol.
The total amount of protective colloid is chosen to give a final viscosity to the emulsion which makes it suitable for the adhesive application, for which it is intended, generally from 100 to ~000 cps as measured by a Brookfield viscometer.
Other bases for wood adhesives may be ; prepared by using as the first polymer network a homo-polymer emulsion of vinyl acetate, containing a protec-tive colloid and small amounts of surface active agents. These emulsions may be prepared using a proce-dure taught in U.S. Patents 3,844,990 and 4,219,455.
;~ The second polymer network consists of polystyrene, ~ 45 polymethyl methacrylate, polyacrylonitrile, polychloro-prene, polybutadiene or copolymers thereof, alone or in combination. The same protective colloids and their amounts as mentioned above may be used.
The aforementioned emulsions, containin~ an interpenetrating network, may be used ~as is~, or when necessary, may be further compour~ded to ~ive desired adhesive properties. For specif~c end uses a variety of plasticizers, solvents, tackifyers, extenders, thickeners, water resistance improvers, heat resistance improvers, preservatives, antifoams, fillers, and fire retardants may be added to the emulsion.
Plasticizers perform a variety of functions in the finished adhesive such as increasing the adhe-sion to specific surfaces, increasing the dry and wet tack of the adhesive, and increasing or decreasing the open time and speed of set time of the adhesive. Open time is the maximum time lapse, between applying the adhesive and bringing the substr~tes together, within which a satisfactory bond can be achieved, whereas speed of set time is the time the adhesive takes to develop the adhesive bond after the adhesive is applied and the surfaces have been united. Normally a higher concentration of plasticizer is incorporated when hard-er polymers are used, whereas lower concentrations of plasticizers will be incorporated when softer polymers are used. In the latter case, often no plasticizer is used at all because the comonomer used with vinyl ace-tate to soften the polymer, such as ethylene or butyl acrylate, functions as plasticizer. The plasticizers which can be used in the adhesiv~ compositions include organic compounds such as acetyl triethyl citrate, : ~:

~ , 46 .

monobutyl benzene sulphonamide; also organic phosphate esters such as triphenyl phosphate; high molecular weight polyesters such as the polyesters resulting from the condensation of polybasic organic acids, such as adipic, sebacic and terphthalic acids, with polyhydric alcohols such as ethylene glycol, or with polyamines, such as hexamethylene diamine; organic esters of tri-ethylene glycol such as triethylene glycol(2-ethylbuty-rate) and triethylene glycol di(2-ethylhexanoate~;
phthalyl substituted glycolates such as methyl phthalyl ethyl glycolate and butyl phthalyl butyl glycolate;
phthalic acid esters, such as dibutyl phthalate, butyl benzyl phthalate, dimethoxyethyl phthalate and dibut-oxyglycol phthalate; low molecular weight polyethylene glycols; and phenyl ethers of polyethylene glycols.
Other plasticizers may also be used provided they are compatible with the IPN containing polymer emulsion.
Solvents, besides thickening the adhesive, act as temporary plasticizers to improve the film form-ing characteristics of the emulsion. Solvents are also added to the adhesive to dissolve a wax or resin coat-ing on the substrate to be bonded in order to allow the adhesive to wet and penetrate the substrate surface adequately for good adhesion. Chlorinated aliphatic solvents, such as perchlorethylene, trichlorethylene, l,l,l-trichlorethane aromatic solvents such as tolu-ene; ester solvents such as ethyl acetate, isopropyl acetate, butyl acetate are the most widely used sol-vents for this purpose. Occasionally, small amounts of water-miscible solvents are used. They include ace-tone, methyl- and ethyl alcohol, ethylene glycol mono-ethyl ether, and also ethylene glycol and propylene ~ 55 glycol. Low boiling solvents such as ethyl acetate allow the full bond strength to be developed more rap-idly than high boiling solvents.
Tackifiers increase the tackiness and the set-speed of adhesives. They include rosin or rosin derivatives, phenolic resins and the like.
Thickeners are added to the adhesive to increase the viscosity of the adhesive for proper ap-plication, They can also lower ~he cost of the adhe-sive by allowing the solids of t~e adhesive to be low-ered while maintaining the viscosity necessary for proper application. Thickeners include polyvinyl alco-hols, both fully and partially hydrolized grades, often together with small amounts of boric acid or its metal salts; also hydroxyethyl cellulose, sodium carboxyme-thyl cellulose, water soluble styrenatéd acrylics, polyacrylamide, polyacrylic acid salts, sodium algi-nate, methyl cellulose, polyvinyl methylether and-poly-vinyl pyrrolidone.
Fillers are added to the polymer emulsion adhesives to increase the solids content of the adhe-sive, to reduce penetration of the adhesive into the substrate, to reinforce the adhesive polymer, to reduce tackiness and to prevent blocking. Fillers include starch flour, bentonite, calcium silicate, clay, calci-um carbonate, talc, wood flour, and the like. Disper-sants, such as sodium tripolyphosphates or sodium poly-acrylates are often added to aid in the dispersion of the fillers.
The water resistance of adhesives can be improved by adding organic compounds to the adhesive composition which react with the polymer in the adhe-B
~ 48 12~ 55 sive such as glyoxal, glyoxal de~ivatives, certain Werner type chromium complexes in isopropanol, 2-hy-droxyadipaldehyde, dimethylol et~ylene urea, melamine-formaldehyde condensates, urea-f~rmaldehyde condensates and the like. Preservatives, antifoams and fire retar-dants, well known in the art, are also often added to the adhesive composition.
Heretofore the heat resistance of an adhesive bond has been improved by adding a latent cr~sslinking agent such as N-methylol acrylamide and an acidic cata-lyst such as chromium nitrate to the adhesive composi-tion. However, especially in wood adhesives, the addi-tion of a colored metal salt is objectionable, since it is preferred that the dried glueline be colorless. The heat resistance of adhesives, that is the resistance to deformation and creep at elevateq temperature, can be improved without these objectionqble and undesirable features by using the polymer emulsion of this inven-tion, such as vinyl acetate-ethylene copolymer/styrene interpenetrating network (IPN) containing emulsion.
The polystyrene network when intertwined with the poly-vinyl acetate homo- or copolymer network will signifi-cantly increase the modulus of the resulting IPN poly-mer at elevated temperatures, which result in a consid-; erable increase in heat resistance.
In preparation of the adhesive, the ingredients may be simply intermixed with the polymer emulsion. Additional water may ~e added to the adhe-sive composition to obtain the p~oper viscosity for the 3~ application of the adhesive, which in a preferred for-muIation the adhesive may contain from 50 to 55 percent solids. A wax emulsion may also be added to improve ~964~5 fluidity and aid in obtaining better spread control in application of the adhesive.
The polymer emulsions of this invention, because of the aforementioned excellent properties, and because of their generally lower cost, are uniquely suitable for a wide variety of adhesive compositions.
The invention is illustrated by the following additional examples.

An ethylene-vinyl acetate copolymer emulsion was prepared. The following was charged to a 10 gal.
stainless steel pressure reactor equipped with a vari-able agitator, temperature control system, feedpumps, means for urging the reactor with nitrogen and pressur-izing with ethylene, and an internal coil for heating and cooling.

Water 9250 g Triton X 405 (8) 120 ~
Triton X 100 (9) 85 g Ferrous sulfate 0.2 g The contents of the reactor were heated to 40C, the reactor was purged with nitrogen once, and then the reactor was pressurized with ethylene to 800 psi. After the heat-up, purge and pressurization, 1000 g of the following monomer emulsion, made up pre-viously, was added to the reactor:

.

~B

l~fi~55 Water (deionized) 2600 g Emcol K8300 (2) 100 ~
Triton X 405 (8) 220 g Triton X 100 (9) 150 g N-Methylol acrylamide (49%) 565 g Acrylamide (50%) 565 g Sodium persulfate 46 g Vinyl acetate 7700 g Triallyl cyanurate 12 g This was followed by the addition of the following initial catalyst solution:

Water (deionized) 385 g Sodium persulfate 38 g The polymerization was initiated by adding an activator solution at a rate of ~.25 gJmin as follows:

Water (deionized) 420 g Hydrosulfite AWC (3) 25 g The polymerization initiated within 5 minutes as indicated by a rise in the reactor temperature. The rest of the monomer emulsion was then added gradually by means of an addition pump at a rate of 30 g/minute over a 3 hour period. The temperature of the reactor content was allowed to rise to 60C and was maintained there by the addition of the above mentioned activator solution as needed. At this point the ethylene pres-sure rose to 900 psi and was maintained there by set-ting the ethylene supply valve to 900 psi. A total of 445 g of the activator solution was used.

~2~ 5S

After 3 hours, when all the monomer emulsion and activator solution had been added to the reactor the following finishing catalyst solution was added:

Water (deionized) 77 9 Sodium persulfate 8 g t-butyl hydroperoxide 7.5 g Triton X 405 (8) 2 g followed by addition of the following finishing activa-tor solution:

Water (deionized) 77 g Hydrosulfite AWC (3) 8 g The temperature of the batch was maintained at 60C for an additional hour after which the free vinyl acetate monomer concentration had fallen below 1%. The polymer emulsion was then cooled to 30C and the ethylene vented from the reactor to ambient pres-sure. The emulsion had the following properties:

solids (30 min at 130C
drying 42.1 pH 5.85 viscosity (Broo~field at 50 RPM) 142 cps intrinsic viscosity measured in N-methyl pyrrolidone at (30C)(6) 0.8 dl/g particle size (by light transmission (10) 0.14 microns ethylene content of 18.5% solids by the copolymer weight .

~.............. 52 i2~55 Notes: (8) Triton X 405 is a 70 percent solution in water of an octylphenoxypolyethoxyethanol containing 30 moles of oxyethanol per mole of octylphenol. It is supplied by the Rohm &
Haas Company.
(9) Triton X 100 is an octylphenoxypolyethoxyet~hanol containing 10 moles of oxyethanol per ~mole of octylphenol.
It is supplied by the Rohm & Haas Company.
(10) The particle size was measured by light transmission using a Coulter Counter In the following examples an interpenetrating network containing varying amounts of vinyl acetate-ethylene copolymer (from Example 5) with polystyrene was prepared.
The following was charged to a 1 liter glass reactor equipped with a variable agitator, temperature control system, feedpumps, and a water bath for heat-ing and cooling:

~:

, 5~

EXAMPT~c Vinyl acetate-ethylene copolymer (Ex. 5) 290.1 g250.9 g250.9 g 205.3 g Water (deionized) 9.7 g 23.1 g44.3 g 54.6 g Emcol K8300 (2)0.4 g0.8 g 1.4 g 1.8 g Triton x 305 (1) 0.4 g 0.8 g 1.4 g 1.8 9 N-Methylol acrylamide(40%) 0.7 g 1.4 g 2.4 g 3.0 g Styrene 13.9 g 27.8 g 47.7 g 60.6 g Divinyl benzene 0.015 g 0.025 g 0.05 g 0.06 Potassium persulfate0.15 g 0.3 g 0.5 g 1.3 g t-Butyl hydroperoxide0.07 g 0.2 g 0.3 g 0.4 g The batch was heated to 55~C, and allowed to equilibrate for 15 minutes, after which the following activator solution was added:

Water 2.2 g 4.7 9 8.1 g 10.3 9 Hydrosulfite AW~:(3) 0.06 g 0.1 g 0.2 g 0.25 g After leaving the batch at 57C for 2.5 hours the above activator charge was repeated. The batch was then cooled to room temperature. The interpene-trating network containing emulsions had the following properties:

% vinyl acetate-ethylene copolymer 90 80 70 60 % poly~styrene 10 20 30 40 solids (30 min at 130C
drying 44.0% 45.2% 42.6% 38.7%
p~ 4.7 5.1 5.5 6.2 viscosity (Brookfield at 50 RPM) 165 cps 237 cps 264 ~ 277 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30C)(6)0.64dl/g0.82dl/g 0.80dl/g 0.78d1/g particle size (by light transmission) (10)-microns 0.14 0.16 0.19 0.28 free styrene 0.02% 0.6% 0.5% 0 One widely used test for evaluating the strength given to a nonwoven by an emulsion polymer treatment is the TAPPI Useful Method 656. This method is a saturation treatment and the information obtained can be translated to other nonwoven treatment methods like print bonding, spray bonding, wet-end coacerva-tion, etc. The new copolymer emulsions were evaluated in TAPPI UM 656 using the following specifications and modifications to the method: All emulsions were run at a pH of 4; emulsion solids were adjusted to provide a 20% dry add-on when padded through an Atlas Laboratory Wringer LW-l; the treated nonwoven (Whatman filter paper) was then dried and cured at 150C for 5 minutes in an AHIBA-Mathis forced air oven type LTF the strength and elongation of the treated nonwovens were determined on both dry and wet (after a 3 minute soak .
~,,,.~ ~
YjJ 55 ~296455 S~

in a 1% Aerosol OT-75 solution) fabrics with an IN~TRO~) Model 1130 tester (gage length 2.5cm with extension rate of 5cm/min); and the values reported are an aver-age of 5 determinations.
In the following Table: A is an ~0%/20%
blend of the vinyl acetate-ethylene copolymer of Exam-ple 5 with polystyrene; B is a 60%/40~ blend of vinyl-acetate-ethylene copolymer (Ex. 5) with polystyrene;
and C is a commercial acrylate ester copolymer (Rhoplex HA-12 from Rohm and Haas Company) which is used to bond polyester and rayon staple fibers.

Ex. 5 Ex. 7 A Ex. 9 B C
Dry Strength 6.7 8.1 7.6 9.2 8.1 8.4 Wet Strength 3.4 4.1 3.3 4.2 3.8 4.1 : j This example shows that the second polymerization of styrene in the vinylacetate-ethylene copolymer enhances the strength of the potential non-woven binder. Although simple blend systems of poly-styrene and the vinylacetate-ethvlene copolymer show an increased strength with polystyrene content, the inter-penetrating network (IPN) systems show an even greater increase in strength. An all acrylic latex (C) of similar stiffness to the 60i40 IPN of Example 9 gave a strength value midway between the blend (B) and the 60/40 IPN of Example 9.

In order to demonstrate the suitability of the interpenetrating network (IPN) polymers in bonding other types of nonwoven fabrics, a 0.50z./yd polyester iC ., .

s~

staple fiber sheet made from DuPont Type 54w Merge number 113 D93 (a 1.5 inch-1.5 denier fiber) was satu-ration bonded with various polymers.
When padded in an Atlas Laboratory Wringer LW-l to achieve an add-on of 35% by weight, the follow-ing tensile strength results were obtained in grams per inch of width.

Example 5 Exam~le 8 Example 9 Dry Strength 396 405 478 Wet Strength 148 210 223 Although this substrate is considerably more viable than the substrate used in TAPPI UM656 in Exam-ple 10, the effect of a second polymerization of sty-rene to form an interpenetrating network with a vinyl-acetate-ethylene copolymer is to increase nonwoven strength. More importantly the example demonstrates that a variety of nonwoven products can be prepared with the IPN polymer emulsion.

Still other nonwovens are fully useful fabrics without an emulsion polymer treatment. A clas-sic example is a needle punched filament polyester fabric which is used for geotextile applications, and industrial fabrics. However, this material, per se, is not able to be used for many applications; such as saturation with hot asphalt, because it stretches too much when under tension in the 350F asphalt bath.
Such a fabric can be treated with the IPN polymer emul-sion to increase the interfiber bond strength and re-duce the stretch in the hot asphalt bath.

~ ~ 57 =~,~ ,...

The suitability of the IPN polymer emulsion and the improvement offered over a traditional polymer emulsion were evaluated in a typical high temperature stretch test. A filament polyester mat which had been needle punched was saturated with various latexes to achieve a dry binder add-on of 22% by weight. The finished fabric weight was 20~ gfim ~ After padding on a Butterworth 2 roll padder, 1 dip-l nip, the fabrics were dried and cured at-400F for 3 minutes in an AHIBA-Mathis LTF forced oven. High temperature stretch was evaluated at two tension levéls. Tension was de-veloped in a constant elongation device - INSTRON Model 1130. Two by six inch (six inches in machine direc-tion) samples were used with a gage length of 10 cm and a jaw separation rate of 10cm/min., and a chart speed of 50 cm/min. All tests were conducted in an environ-mental cabinet with a temperature of 180C. The sample and cabinet were allowed to equi?ibrate on minute after entering the test sample and aft~r the cabinet returned to 180C. The extension of the sample was recorded when the tension reaches the 5000 and 8000 gram levels.
The performance of a polyvinylacetate polymer emulsion (represented by SUNCRYL RW41SP which is sold by Sun Chemical Corporation) can be improved by a sec-ond stage polymerization forming an IPN with methyl methacrylate (see Example 2). Suncryl SA 220 is a traditional styrene-butylacrylate copolymer (sold by Sun Chemical Corporation) with a hardness value similar to Suncryl RW 41SP and the IPN of Example 2.

12~6~55 Untreated SUNCRYL SUNCRYL ExamPle 2 (RW 41SP) (SA 220) 5000gm load14.3 8.8 20.8 6.1 8000gm load19.5 27.9 37,3 14.3 The above table shows that the second stage polymerization forming an IPN can dramatically alter the stretch performance of a basic nonwoven fabric.

A glass fiber mat without binders is prepared as follows:
1) 2.8 ~rams of type M glass fiber of 16 micron diameter and 1.25 inch staple length are mixed in 300 ml. of water;
2) The fiber slurry is mixed 1 minute in a commercial Waring blender;
3) Separately a polyester scrim fabric (40 x 40 mesh/in.2) is treated with a silicone release coating made with a bath of 12% Norane Silicone (30%
solids emulsion of methyl hydrogen polysiloxane) and 3%
Catalyst EC (20% solids dispersion of zinc stearate) and cured for 2 minutes at 340F;
4) a 9" x 18" scrim is placed in a Noble &
Wood paper hand sheet former and the unit is closed;
5) lOjO00 mls of water and 10 mls of 10%
Katapol PN-430 (polyoxyethylated alkylamine from GAF
Corporation) solution is added with mixing 6) The fiberglass slurry is added and mixed;
and 7) This diluted slurry is then dropped through the scrim forming the unbonded glass fiber mat.
, ' ~
J

Aqueous bonding solutions are traditionally prepared by reducing a commercial U-F (urea-formalde-hyde) binder from its supplied strength (55~) to 30%
non-volatile content or, if being tested, mixing with an appropriate thermoplastic emulsion copolymer prior to dilution to 30% solids. These bonding solutions are simple mixtures conducted under agitation at room tem-perature. These mixtures are then further reduced to 4% solids with agitation just prior to immersing the glass mat to be treated.
Other glass mat products require different binding systems. The use of urea-formaldehyde binders has been the historical bonding system for glass mat for shingle roofing substrate or for built-up roofing fabrics. Urea-formaldehyde resins have been used for these fabrics but exhibit some deficiencies:
1) The fabrics are too brittle, causing breakouts in production;
2) These fabrics are not flexible and cause breakage in roofing installation;
3) U-F bonded glass mats are high in tensile strength but lack overall toughness; and 4) U-F bonded glass mats lose strength when exposed to water.
One way to overcome these deficiencies in U-F
bonded glass mats for roofing products is to include a thermoplastic polymer as a portion of the regular U-F
glass binder. The thermoplastic polymer modifies the U-F resin's brittleness and, more importantly, greatly increases the mat's strength when exposed to heat and moisture.

~ 60 ~9 Çi~55 The following procedures describe the preparation and testing of glass fiber nonwoven mats suitable for roofing fabrics (bo~h for shingle and fur BUR, built up roofing, applications). The glass fiber mats bonded with a U-F resin (55~ solids) were compared to mats bonded with U-F and various emulsion polymers.

Wet Weiqht ~ry Weiqht U-F resin 55 grams 30 grams Emulsion polymer21.4 grams 10 grams Water 923.6 qrams 0 qrams 1000 grams 40 grams Note that the IPN polymer emulsion represents 25% of the total dry binder content in this Example.
This glass fiber mat was bonded with 20% by weight dry add-on of binder. The following procedure was used:
1) The bonding bath was prepared, reduced to 4% solids, and placed in an open pan (conveniently 1000 mls of bonding solution in an 11 x 16 x 1 inch pan);
2) The glass mat sandwiched between layers of scrim was immersed in the bonding solution;
3) The mat was removed and blotted to 225-250% wet pick-up (pick-up was based on the total scrim plus fiber glass mat weight);
4) The mat with scrims still intact was dried and cured 3 minutes at 300F; and 5) The scrims were then peeled away leaving an integrally bonded glass mat fiber.
The following items are recorded through this process.

"~ ""'''3 ~ 61 ~2~455 A. original scrim weight B. scrim with unbonded glass mat weight C. final scrim with bonded glass mat weight % binder = CB-A X 100 -1 These bonded glass mats were then tested in an appropriate evaluation series including wet and dry tensile strength in TAPPI Method UM 656 (4 inch gauge length) and tear strength in ASTM Method D-689. Since all bonding mixes are aqueous, the bonding ingredients are based on soluble U-F reins and emulsion polymer products.
A commercially used U-F resin was used alone and blended with a commercial acrylate ester emulsion polymer (Rhoplex GL655 sold by Rohm and Haas), a sty-rene-acrylic emulsion copolymer (Suncryl SA-220), a polyvinylacetate emulsion copolymer (Suncryl RW 41SP) and the polyvinylacetate-styrene interpenetrating net-work (IPN) polymer emulsion of Example 1. All the thermoplastic components had polymer Tg's in the 25-50C range The U-F resin provides a standard for :~ comparison: , Dry Tensile 4.2 + 1.3 Wet Tensile 2.7 + .9 % Wet/Dry 64%
Tear Strength 285 , : B;~ ~ 62 .,, :

12~455 UF Resin with Rhoplex SUNACRYL SUNACRYL IPN Polymer GL 655 SA-220 RW 41SPof Example 1 Dry 4.6 + 1.5 6.0 + 1.6 5.5 + 1.45.9 + 1.7 Wet 5.1 + 2.8 4.5 + 2.4 2.9 +` .25.4 + 1.3 % Wet/Dry 111% 75% 53% 92 Tear 483 371 427 461 These res~lts show that adding thermoplastic copolymers to the U-F resin improves the dry and wet tensile and the tear strength of the glass fiber mats.
The single most important measure of glass mat performance is wet tensile strength. This corre-lates well with higher Tg copolymers with hydrophobic character. The traditional copolymers show increasing wet strength in the order: 1) vinylacetate copolymer;
2) styrene-butyl acrylate copolymer; and 3) methylmeth-acrylate-ethylacrylate copolymer. The vinylacetate-styrene interpenetrating network copolymer showed an even better wet strength performance. These two mono-mers have not previously been combined in a single IPN
copolymer system for bonding glass mat nonwovens. Such an IPN copolymer demonstrates a valuable utility in providing ade~uate glass mat performance properties in a lower cost polymer composition when compared to sty-rene-acrylic or all acrylic copolymers.

Ethylene-vinylacetate copolymer emulsions, Examples E and I, were prepared as follows:
The following was charged to a 10 gal.
stainless steel pressure reactor equipped with a vari-able agitator set at 60 rpm, temperature control sys-,~ ~

~ 63 tem, feedpumps, means for purging the reactor with nitrogen and pressurizing with ethylene, and an inter-nal coil for heating and cooling:

Example I Example E
Water (deionized) 7500 g. 7500 g.
Emcol K8300 (2) 120 g. 120 g.
Triton X 405 (8) 85 g. 85 g.
Tamol SN (9) 17 g. 17 g.
Ferrous Sulfate(10% Solution) 8 g.8 g.

The contents of the reactor were heated to 45-50C, the reactor was purged with nitrogen once, and with ethy-lene twice to 10 psi. followed by the addition of:

Example I ExamPle E
Vinyl acetate 400 g. 400 g.

The reactor was then pressurized with ethylene to 800 psi. This was followed by the addition of the follow-ing initial catalyst solution:

Example I Example E
` Water (deionized) 200 g. 200 g.
~ 20 Ammonium persulfate 13 g. 13 g.

;~ ~ The polymerization was initiated by adding an activator solution at a rate of 5 g/min. which was made up as ~ follows:

:~;

.

ss Example I Example E
Water (deionized) 1500 g. 1500 g.
Hydrosulfite AWC (3) 50 g. 50 g.

The polymerization initiated within 5 minutes as indi-cated by a rise in reactor temperature.
The following monomer emulsion, prepared previously was then added gradually by means of an addition pump at a rate of 43 g/min. over a 3 hour period.

ExamPle I ExamPle E
Water (deionized) 4000 g.4000 g.
Emcol K8300 (2) 250 g. 250 g.
Monoethyl maleate 140 g. 140 g.
Ammonium hydroxide (28%) 9 g.9 g.
Vinyl acetate 8300 g. 8300 g.
Triallyl cyanurate 1 g. 1 g.
Ammonium persulfate 100 g.100 g.

The temperature of the reactor content was allowed to rise to 55C and was maintained there by the addition of the above mentioned activator solution as needed.
At this point the ethylene pressure rose to 900 psi and was maintained there by setting the ethylene supply valve to 900 psi for Example E and to 1100 psi for Example I. A total of 1500g for Example I and 881g for Example E of the activator solut~on was used.
After 3-3 1/2 hours, wpen all the monomer emulsion and activator solution had been added to the reactor the following finishing catalyst solution was added:

:: B

.

Example I ~x~
Water (deionized) 400 g. 200 g.
Ammonium persulfate 25 g. 20 g.
t-butyl hydroperoxide 15 g. 5 g. .

followed by addition of the following finishing activa-tor solution:

Example I Example E
Water (deionized) 400 g. 200 g.
Hydrosulfite AWC (4) ~0 g. 10 g.

The temperature of the batch was maintained at 60C for an additional hour after which the free vinyl acetate monomer concentration had fallen below 1%. The polymer emulsion was then cooled to 30C and the ethylene vent-ed from the reactor to ambient pressure. The following solution was then added to the batch:

Exam~le I ExamPle E
Water (deionized) 500 g. 500 g.
Triton X 405 (8) 85 g. 85 g.
Ammonium hydroxide (28%) F g. 50 g.

The ethylene-vinylacetate copolymer emulsions had the following properties:

:::

~ ~ 66 .

5~rj _ ~3 _ Example I ExamPle E
solids(30 min at 130C drying) 44.6% 42.3%
pH 7.4 6.8 - viscosity (Brookfield at 50 RPM) 41.6 cps 30.4 cps intrinsic viscosity, (measured in 1.50 dl/g 1.56 dl/g N-methyl pyrrolidone at 30C) (6) particle size (by light 0.13microns 0.13microns transmission) (40) ethylene content of the copolymer 18.5% 8.8%

Polymer emulsions were prepared containing an interpenetrating network of vinylacetate-ethylene copolymer and varying amounts of polystyrene.
The following was charged to a 1 liter glass reactor equipped with a variable agitator, temperature J control system, feedpumps, and a water bath for heating and cooling:

Ex. B Ex. C Ex. D
Airfle ~ 00 HS (1131819.8 g1611.3 g1392.2 g Water (deionized)474.4 g568.7 9 361.2 g Emcol K8300 (2) 7.3 g 14.7 g 21.7 g Triton X 405 (8)4.4 g 8.8 g 13.0 g Sipomer DS 10 (12)1.6 g 1.6 g 4.8 g Monoethyl maleate1.2 g 2.4 g 3.6 g Styrene 112.2 g 223.3 g 330.6 g Divinyl benzene 0.12g 0.22g 0.32g Ammonium persulfate1.9 g 3.8 g 5.7 g t-Butyl hydroperoxide0.5 g 0.9 g 104 g The batch was heated to 55C, after equilibration the following activator solution was added:

12~5S

Water (deionized) 4.9 g 9,7 g 14.4 g Hydrosulfite AWC (3) 1.0 9 2.0 g 2.9 9 After leaving the batch at 8QC for 2-5 hours it was then cooled to room temperature and the following solu-tion was added:

Ex. B Ex. C Ex. D
Water 26.1 9 26.1 g 26.1 9 Triton X 405 (8) 13.2 9 13.2 g 13.2 g Ammonium hydroxide(28%) 9.4 9 9.4 g 9.4 g Formaldehyde (37%) 0.7 g 0.7 g 0.7 g Proxel GCL (13) 1.4 g 1.4 g 1.4 9 the interpenetrating network containing emulsions had the following properties:

Ex. B Ex. C Ex. D
solids(30 min at 130C
drying) 45.5% 45.3% 45.4%
pH 5.2 7.9 4.9 viscosity (Brookfield at 50RPM) 49.6 cps 53.6 cps 37.6 cps intrinsic viscosity (measured in N-methyl pyrrolidone at ! 30C) (6) 1.14dl/g O.99dl/g 1.24dl/g particle size (10) 0.16microns 0.18microns O.l9micron free styrene 0.01% 0.11% 0.26%
total polystyrene content 10% 20% 30 Notes: (11) Airflex 100 HS is a vinyl acetate-ethylene copolymer emulsion having an ap-proximate ethylene content of about 15%. It is supplied by Air Products and Chemicals Corp.
(12) Spinner DS 10 is a brand of sodium dodecyl benzene sulfonate supplied by the Alcolac Chemical Co.
(13) Proxel GXL is a biocide supplied by ICI.

.

SS

~1 0 r~ > ~ ~ ~
, 0 ~ o ~ o o o ~ X U~ o W ~o ~ ~ rO W ,~
Q~ ..
V~
o O ~ ~ cr~ X
~J ~ 0 ~ ~ 0 0 ~ N ~ O
10 .,, I o ~ o ~D O O O O X Ir~ O
~ ~ W ~
Q ~ O I~
a~ ~ o ~ ~1 ~, . o N
YO ' ~ ~3 ~ ~ ~i 0 ~ O W

~ ~ .

~,c u~ I eP o ~ o o o t:n x u~ o ~1 ~ N ~ ~: W ,_1 Q~ O
O I ~ o ~ ~ o ~ ~1 0 o ~
~0 p, ~ ~ S I ~ I ~ O ~ O .0 0 .C WX ~
~1 h tq O ~
O P~ ~ 10 w ~ O ac7` ~ ~ ~ ~ C71 . -~
~ ~ ~~ X 1~ 1 ~1 o ~ o o o ~ X u7 o W ~ O ,~ W N --I ~ W
Vl .,1 0 h C
a E3 a~ aJ a~
o V ~ W

O ~ `' , O
P. ~ ~J `
m ~0 ~ D

C ~ o '~ N

V ~ o ~

o ~ . ,, ss ~ o~ ~ ~
~ o ~ ~ i o o u~
F~C o OD ~ ~ ~ ~: ~ ,~
~ o ~d~ ~ ~i O O
, _I~ ~ ~ ~ _~ ~1 u~ ~1 ~
, ~ o o o o ~ ~ ~ ~i o o O

~1 ~1 ~ N ~i o O
~ u a a.~Vl OD 00 ~1 ~ S ~1 ~
~ ,~ ~ ~ O O

a~~ cn a~ ~D ~ ~ ~
~1 N O O O ~3 ~I t~ ~i 0 0 L~
O
- ~
~q U
~ ~ O
s~
~1) ~ 10 Ul ~
q ~1 ,~ ..
O

"
a u u~
U ~
'~ O ~ ~ _ a~ ~ o o ~ ,-- ~ ~ a~

.,,, ~ .~, _ o ~
u7 ~ a _ U O o ~ ~ o ~ ~

.,,, ~ ~ X L. ~ X ~ ~ ~3 O ~ o ~

:
O.

~1 ~1 æd' ~

o~ ~ o~O

..
U~
a~
,.

¦ U~ dl ~ <~ ~
~ dl U~ a~ . o o cn d ~

~¦ ~ d~ 0~o ~ ~3 N ~ ~
,C '~ _i l? ¦ ~ O O ~1 o o o '~, ~ N U~ o o N --i i~
~; ~ O

0~
O O
U
Q~

O

, ,~ .

:~

.`55 /

A series of paper coating formulations were made with vinylacetate-ethylene copolymer emulsions (Example 14) and with the same copolymer emulsions after a second stage polymerization with styrene to form an interpenetratin~ polymer network (IPN) of the copolymer emulsion with polystyrene (see Examples 15 and 16). Three basic vinylacetate-ethylene (VAE) emul-sions were used as follows: a commercial product, Airflex lOOHS sold by Air Products and Chemicals Corp., containing about 15% ethylene and with a Tg of ~5C; an emulsion containing 8.8% ethylene (Example E) and with a Tg of 15C; and an emulsion containing 18.5% ethylene (Example I) and with a Tg of 0C. All three VAE copol-ymer emulsions were further swelled by styrene monomer and polymerized as described in Examples B-D, F-H and J-L (Examples 15 and 16). The particle sizes and of the VAE and IPN emulsions are summarized as follows:

Example Emulsion DescriPtion Particle Size(l) A Airflex lOOHS (15% Ethylene) 0.160 um B with 10% Styrene 0.162 um C with 20% Styrene 0.182 um D with 30% Styrene 0.192 um E VAE with 8.8% Ethylene 0.13~ um F with 10% Styrene 0.148 um with 20% Styrene 0.205 um H with 30% Styrene 0.292 um : I VAE with 18.5% Ethylene 0.127 um J with 10% Styrene 0.149 um K with 20% Styrene 0.191 um L with 30% Styrene 0.207 um ~ ~ .

- ,~o~-All emulsions of Examples A through L were made into paper coating formulas of the following dry composition:

- Dry Weiqht (qms.) Kaolin Clay 350.0 Anionic Dispersant5.3 Ethoxylated Starch7.0 Emulsion from Examples A-L 18.9 As in standard paper coating formulation, the clay (ground clay, 92-94% finer than 2 microns) and dispersant (Dispe ~ -40 from Allied Corporation) were ground together in a Kady Mill at 70~ solids for 30 minutes. Separately the starch (Penford Gu~80 from Penick & Ford Ltd.) was slurried at 25% solids and cooled at 190F for 20 minutes. This starch mix was added to the clay and dispersant mix and agitated. The polymer emulsions were then added to this composite mix and the coating formulation diluted to 64~ solids for coating.
The relative performance of a paper in a printing press can be simulated in various laboratory tests. Offset printing is demanding on paper coatings.
The coating is first wet with a water/alcohol solution and then printed with a thick, tacky ink. The multi-color printing there may be four or five applications in less than a second on a high speed press.
A 50#/ream groundwood-free base sheet was coated with 8# dry coat weight (CIS, coated on one side) on a bench paper coater made by Modern Metalcraft Company. This coated paper was then calendered 2 nips , ~

i5 at 150F under a 600 pli pressurq in a cotton/steel calender. After conditioning 24 pours under standard paper test conditions the paper coatings were tested for sheet gloss, smoothness, porosity, pick strength, Adam wet rub resistance, printed ink gloss and SIWA
brightness. Sheet gloss, smoothness and porosity showed little variation between the vinylacetate-ethy-lene (VAE) emulsions and the interpenetrating polymer network (IPN) emulsions formed by the second stage polymerization with styrene.
The effect of the second stage polymerizations in forming the IPN emulsions was appar-ent in pick strength, Adam wet rub resistance, printed ink gloss, and SIWA brightness tests. The results are as follows:

IGT Pick Adam's Wet 75Ink SIWA (6) Strength (3) Rub (4) Gloss (5) Brightness A 22 72 96 51.5 B 28 136 97 49.6 C 23 190 96 53.3 D 22 196 91 55.5 E 22 72 96 51.5 F 29 124 96 49.8 G 22 126 91 52.2 - H 16 390 81 59.5 I 20 165 92 52.3 J 26 111 96 54.0 K 25 155 94 56.1 L 22 219 91 61.3 An additional evaluation compares the IPN
emulsion with physical blends of an equivalent composi-tion (i.e. blend of the vinylacetate-ethylene copolymer B

1~9~455 with a corresponding level of polystyrene). The blends are designated with an (').

IGT Pick Adam's Wet 75Ink SIWA (17) Strength (14) Rub (15) Gloss (16) Brightness H(IPN) 16 390 81 59.5 ~'(81end) 13 206 81 56.3 J(IPN) 26 111 96 54.0 J'(Blend) 26 251 91 58.9 L(IPN) 22 219 91 61.3 L'(Blend) 13 296 80 58.9 Notes (14) The coating must be strong enough not to 'pick' when the ink applicator rolls off the surface.
This is especially important on high speed presses and with tackier inks. The IGT pick strength (reported as a product of velocity and viscosity - VVP) is determined by using differ-ent viscosity oils and applying them at differ-ent speeds until the coating fails (picks).
This establishes the coati~g's pick strength.
Pick strength was measured on an AlC2-5 Model IGT pick tester sold by Techno Graphic Instru-ments. The test was run with a setting of 2m/s using LV oil and a pressure setting of 50 kg.
LV oil is polybutene with a viscosity of 2~2 poise at 23C. Pick Values in VVP (velocity-viscosity product as defined by IGT) are report-ed.
(15) The coating must accept the water solution but not soften or release pigment to the press (called 'milking' by printers). This is simu-~r 7 6 s lated by the Adams wet rub test in which the coating is wetted and rubbed mildly for 20 seconds. The amount of 'milking' is measured by the qmount of coating removed (in milligrams) or by thq opacity of the water solution.
~16) The ink must wet the coating but not absorb into the paper and lose its sharpness. This is mea-sured as ink gloss on a glossmeter. Printed ink gloss was determined by placing a 4.8 um ink film on the coated paper and measuring gloss on a 75 Gardner Glossmeter II.
(17) In actual practice the ink may be applied over a previous water layer. If the paper does not absorb water sufficiently, the ink will not apply and the coating layer will remain un-printed. The simultaneous application of ink over water and subsequent ~easure of coverage is measured by SIWA brightness. High brightness numbers indicate less complete ink coverage because the unprinted coating is brighter than the ink. SIWA brightness is a simulation of an offset printing process conducted on an IGT pick tester. A droplet of water is overprinted with ink (Control-Lith II Blue f rom GPI Division of Sun Chemical Corporation) on a 15 micron print-ing disc at 2m/s. The brightness of the over-printed area is then measured on a GP Photovolt brightness meter. Higher prightness values indicate higher water holdout tendencies.
In all cases the second styrene polymerization forming the $PN emulsion increased the IGT pick strength. In fact, levels of about 10% sty-.

~ ~ 77 rene produced a maximum coating strength in all three vinylacetate-ethylene systems. Increasing from 10% to 30% styrene reduced pick strength back to the level of the original vinylacetate-ethylene emulsion probably due to the increased particle size at higher styrene levels. Both particle size and polymer composition affect paper coatings. Generally, with a given polymer composition, smaller polymer particle sizes will pro-duce higher strength paper coatings. Here, for the various IPN polymers the particl~ size/strength rela-tionship is not clear because of the differing polymer compositions. However, it is clear that the second polymerization of the IPN polymers increased the paper coating strength since even though the particle size increased, the IGT peek strength was greater than in the non-IPN polymer paper coatings.
Adam's wet rub results deteriorated with increasing styrene levels for Examples A-D and E-H but showed improvement in Examples J and X. Ink gloss (75) also showed increases at lower levels of styrene, but a subsequent decrease in gloss at higher styrene levels. SIWA brightness increased with increasing styrene levels, with two systems decreasing slightly at low styrene levels, but increasing rapidly with further increases of styrene levels. In the above Examples IPN
emulsions containing 10% styrene produced peak values in IGT strength and ink gloss.
Blending a polystyrene emulsion with the vinylacetate-ethylene copolymer emulsion did not pro-duce the same results as forming an IPN emulsion with polystyrene in a second phase polymerization. The differences (shown in the last table) are most pro-~ ' ~ B ` 78 5~ -nounced in IGT pick strength, Adam's wet rub and 75 ink gloss, These are the three most important measures for predicting offset press runnability of coated pa-pers and the improvements show the potential value of this invention on paper coating applications. Impor-tantly this IPN emulsion can deliver excellent perfor-mance at a low cost since the starting materials are relatively low cost polymers.

A polyvinyl acetate emulsion was prepared as follows.
The following was charged to a 100 gallon stainless steel pilot reactor e~uipped with a variable agitator, temperature control system, feedpumps, means for purging the reactor with nitrogen, and a jacket for heating and cooling:

Water 140 lbs. (63.5 kg) Triton X 305 (1) 6 lbs. 10 oz. (3 kg) Emcol K8300 (2) 8 oz. (227 g) The contents of the reactor were heated to 67C after which the reactor was purged with nitrogen.
After the heat-up and purge the following monomer was added to the reactor:

Vinyl acetate 26 lbs. (11.8 kg) This was followed by the addition of the initial catalyst solution:

~9~4`55 Water 10 lbs. (4.5 kg) Potassium persulfate 8 oz. (227 g) The polymerization initiated within 5 minutes indicated by a rise in temperature of the reactor. The following monomer emulsion, made up previously, was then added gradually by means of an addition pump at a rate of 1.56 lbs./minute over a 3~ hour period:

~ater 58 lbs. (26.3 kg) Emcol K8300(2) 8 lbs. 8 oz. (3.9 kg) Triton X 305(1) 2 lbs. 4 oz. (1.0 kg) N-methylol acrylamide (49%) 19 lbs. (8.6 kg) Acrylamide (50%) 2 lbs. (0.9 kg?
Monoethylmaleate 12 oz. (340 g) JPS Sequesterent(5) 5 oz. (142 g) Vinyl acetate 238 lbs. (108 kg) Triallyl cyanurate 5 oz. (142 g) The temperature of the reactor content was allowed to rise to 80C and was maintained there by the gradual addition at a rate of 0.362 lbs./minute over a 3~ hour period of the following catalyst solution:

Water 75 lbs. (34 kg) Potassium persulfate 9 oz. (225 g) After 3~ hours, when all the monomer emulsion and catalyst solution has been added to the reactor the following finishing catalyst solution was added:

Water 1 lb. (.45 kg) Potassium persulfate 2 oz. (57 g) The temperature of the batch was maintained at 80C for an additional 30 minutes, after which the polymer emulsion was cooled to 30C.
The copolymer emulsion thus obtained had the following properties:

solids (30 min at 130C drying 43.9%
pH 5.5 viscosity (Brookfield at 50 RPM) 36.8 cps A polystyrene emulsion was prepared as follows:
The following was charged to a 3 liter stainless steel laboratory reactor equipped with a variable agitator, temperature control system, feed-pumps, means for purging the reactor with nitrogen, and a waterbath for heating and cooling:

~ater 850 g Triton X 305(1) 18 9 Ferrous sulfate 1 9 (1% so~ution in water) : The contents of the reactor were heated to : 68C after which the reactor was purged with nitrogen.
~; After the heat-up and purge the Pollowing monomer was added to the reactor:

.

..

5~ri Styrene 129 g This was followed by the addition of the initial catalyst solution:

Water 129 9 Potassium persulfate 2,6 g The polymerization initiated within 5 minutes as indicated by a rise in temperature of the reactor.
The following monomer emulsion, made up previously, was then added gradually by means of an addition pump at a rate of 9 g/minute over a 3 hour period:

Water 284 g Emcol ~8300(2) 40 g Triton X 305(1) 30 9 N-Methylol acrylamide (49%) 93 g Acrylamide (50%) 10 g Styrene 1148 9 Itaconic acid 15 g Triallyl cyanurate 1.2 g Ammonium hydroxide (28%) to a pH of 3.6 ~: 20 The temperature of the reactor content was ;:~ allowed to rise to 74~75C and was maintained there by ~: the gradual addition at a rate of 0.73 g/minute over a ~:~ 3 hour period of the following catalyst solution:

Water 129 g Potassium persulfate 2 g followed by a reducing solution Water 2 g Hydrosulfite AWC(3) 0.5 g The temperature of the batch was maintained at 70C for an additional 30 minutes, after which the polymer emulsion was cooled to room temperature. The copolymer emulsion thus obtained had the following properties:
solids (30 min at 130C drying) 44.9%
pH 5.5 viscosity (Brookfield at 50 RPM) 46.4 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30C 1.44 dl/g particle size (by light transmission 0.16 microns free styrene monomer 0.25%

A blend was made by mixing the following polymer emulsions:

emulsion of Example 18 817.2 g emulsion of Example 19 532.8 g The emulsion blend had the following properties:

.

; ' .

~ 83 solids (30 min at 130C drying) 44.3%
pH 5.25 viscosity (Brookfield at 50 RPM) 40 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30C) 1.21 dl/g particle size 0.18 micron An emulsion containing a polymer which is an interpenetrating network of 60% polyvinyl acetate and 40% polystyrene was prepared as follows:
The following was charged to a 3 liter stainless steel laboratory reactor equipped with a variable agitator, temperature control system, feed-pumps, means for purging the reactor with nitrogen, and a water bath for heating and cooling:

Water 462 g Triton X 305(1) 18 g Emcol K8300(2) 0.6 g . 20 The contents of the reactor were heated to 67C after which the reactor was purged with nitrogen.
After the heat-up and purge the following monomer was added to the reactor:

Vinyl acetate 72 g This was followed by the addition of the initial catalyst solution:

D
D

Water 24 g Potassium persulfate 1.32 g The polymerization initiated within 5 minutes as indicated by a rise in temperature of the reactor.
The following monomer emulsion, made up previously, was then added gradually by means of an addition pump at a rate of 7.11 g/minute over a 126 minute period:

Water 158 g Emcol K8300 (2) 22.8 g Triton X 305(1) 5.88 g N-Methylol acrylamide (49~) 51.6%
Acrylamide (50%) 6 g Monoethylmaleate 1.98 g Vinyl acetate 648 g Triallyl cyanurate 0.72 g The temperature of the reactor content was allowed to rise to 80C and was maintained there by the gradual addition at a rate of 1.16 g/minute over a 126 minute period of the following catalyst solution:

Water 144 g Potassium persulfate 1.56 g ~ ~ I
The temperature of the batch was maintained : at 80C for an additional 30 minutes, after which the polymer emulsion was cooled to 60C and an additional :~ 240 g of water was added. Then a second monomer emul-sion was introduced into the reactor as fast as possi-ble, in about 10 minutes, which also had been prepared before as follows:
.

, ~64ss Water 216 g Emcol K8300(2) 21.6 9 Triton X 305(1) 21.6 g N-Methylol acrylamide (49~) 36 g Styrene 489 9 Divinylbenzene 0.48 g Sipomer DS-10(12) 7.2 g Itaconic acid 7,2 g The temperature of the reactor content was maintained at 60C while the.reactor was again purged with nitrogen. Then the following catalyst solution was added to the reactor:

Water 180 g Potassium persulfate 7.2 g t-butyl hydroperoxide 2.4 g The second polymerization step was initiated`
by adding half of the followin~ reducing solution:
.

Water go g Hydrosulfite AWC(4) 3.6 g The temperature of the batch increased rapidly to 80C, at which point the other half of the reducing solution was added to the reactor. The tem-perature of the batch was then maintained at about 80C
for an additional 30 minutes, after which the polymer emulsion was cooled to room temperature. The following post-add was then added:

~: :
.s~ J 86 ss Water 5 g Proxel GXL(13) 0.25 g Formaldehyde 0.25 g The interpenetrating network copolymer emulsion thus obtained had the following properties:

solids (30 minutes at 130C
drying) 4.25 g pH 5.5 viscosity (Brookfield at 50 RPM) 670 cps intrinsic viscosity (measured in N-~g~hyl pyrrolidone at 30C 0.85 dl/g Particle size (10) 0,37 microns An ethylene-vinyl acetate copolymer emulsion was prepared as follows:
The following was charged to a 10 gal.
i stainless steel pressure reactor equipped with a vari-able agitator, temperature control system, feedpumps, means for purging the reactor.with nitrogen and pres-surizing with ethylene, and an internal coil for heat-ing and cooling:

Water (deionized) 9250 g ~: Triton X 405(8) 120 g Triton X 100(18) 85 g Ferrous sulfate 0.2 9 ~:

~, ,;
~ 8 7 " .

~ 55 The contents of the reactor were heated to 40C, the reactor was purged wit~ nitrogen once, and then the reactor was pressurized with ethylene to 800 psi. After the heat-up, purge and pressurization, 1000 g of the following monomer emulsion made up previ-ously, was added to the reactor:

Water (deionized) 2600 g Emcol K8300(2) 100 9 Triton X 405(8) 220 g Triton X 100(18) 150 g N-Methylol acrylamide(49%) 565 g Acrylamide (50%) 565 g Sodium persulfate 46 g Vinyl acetate 7700 9 Triallyl cyanurate 12 g This was followed by the addition of the following initial catalyst solution:

Water (deionized) 385 9 Sodium persulfate 38 g The polymerization was initiated by adding an activator solution at a rate of 1.2S g/min as follows:
.
Water (deionized) 420 g Hydrosulfite AWC(3) 25 g The polymerization initiated within 5 minutes as indicated by a rise in the reactor temperature. The rest of the monomer emulsion was then added gradually B

i4~5 by means of an addition pump at a rate of 30 g/minute over a 3 hour period. The temperature of the reactor content was allowed to rise to 60C and was maintained there by the addition of the above mentioned activator solution as needed. At this point the ethylene pres-sure rose to 900 psi and was maintained there by set-ting the ethylene supply valve to 900 psi. A total of 445 g of the activator solution was used.
After 3 hours, when al~ the monomer emulsion and activator solution had been ~dded to the reactor the following finishing catalyst~solution was added:
.

Water 77 g Sodium persulfate 8 g t-butyl hydroperoxide 7.5 g Triton X 405(8) 2 g followed by addition of the following finishing activa-tor solution:

Water (deionized) 77 g Hydrosulfite AWC(3) 8 g The temperature of the batch was maintained at 60C for an additional hour after which the free vinyl acetate monomer concentration had fallen below 1~. The polymer emulsion was then cooled to 30C and the ethylene vented from the reactor to ambient pres-sure. The ethylene vinyl acetate copolymer emulsion had the following properties:

, .

i455 solids (30 minutes at 130C
drying) 42.1%
pH 5.85 viscosity (Brookfield at 50 RPM) 142 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30 QC 0.8 dl/g particle size 0.14 microns ethylene content of the copolymer 18.5%
Note (18) Triton X 100 is an octylphonoxy polyeth-oxyethanol containing 10 moles of oxyethanol per mole of octylphenol. It is supplied by the Rohm and Haas Company.

An emulsion containing a polymer which is an interpenetrating network of an e~hylene-vinyl acetate copolymer and polystyrene was prépared as follows:
The following was charged to a 1 liter glass reactor equipped with a variable agitator, temperature control system, feedpumps, and a water bath for heating and cooling:

~ Emulsion of Example 22 250.9 g ; Water (deionized) 44.3 g Emcol K8300(2) 1.4 g Triton X 30s(1) 1.4 g N-Methylol acrylamide(49%) 2.4 g Styrene 47.7 g Divinyl benzene 0.05 g Potassium persulfate0.5 g t-butyl hydroperoxide0.3 g '~ :

~'`' 90 ~ ., ss The batch was heated to 55C after which the following activator solution was added:

Water (deionized) 8.1 g Hydrosulfite AWC(3) 0.2 ~

After leaving the batch at 57C for 3 hours the above activator and catalyst charge was repeated and kept at 65C for an additional hour. The batch was then cooled to room temperature. The interpenetrating network containing emulsion ha~ the following proper-ties:

solids (30 minutes at 130DC
drying) 42,6%
pH 5,5 viscosity (Brookfield at 50 RPM) 264 cps intrinsic viscosity (measured in N~thyl pyrrolidone at 30C 0.80 dl/g : particle size(l) 0.19 microns free styrene 0.5%

A blend was made by mixing the following polymer emulsions:

emulsion of Example 22 2115.7 g , emulsion of Example 19 884.3 g The emulsion blend had the following properties:

~ 1 .

1~ j5 solids (30 minutes at 130C
drying) 43.7%
pH 5.4 viscosity (Broo~field at 50 RPM) 123 cps The following aqueous coatings were prepared using the emulsions of Example 18 (polyvinyl acetate), 20 (blend of polyvinyl acetate and polystyrene), 21 (IPN of polyvinyl acetate and polystyrene), 23 (IPN of ethylene-vinyl acetate copolymer and polystyrene) and 24 (blend of ethylene-vinyl acetate copolymer and poly-styrene).
The emulsions and the emulsion blend were formulated into aqueous coatings in the following man-ner. To a titanium dioxide slurry was added water, butyl cellosolve (were applicable), and then the emul-sion was added under agitation. The following table lists the amounts.

Amount of Ingredient (grams) lurry(l9) Water cellosolve(20) Emulsion M (Ex. 18) 239.9 62 --- 400 N (Ex. 23) 245.9 65.4 --- 400 O (Ex. 21) 235.4 64.5 8 400 P (Ex. 20) 239.9 54 --- 400 Q (Ex. 24) 239.4 53 --- 400 Note: (19) The titanium dioxide slurry (78.2% sol-ids) contained 65% rutile titanium dioxide, 6.6~ methacrylate resin and 6.6% butyl cello-~:

::

solve. It was sold under the name "TitaniumDioxide White 1060Q" by Universal Color Disper-sions Company.

Note: (20) Butyl cellosolve is a brand of ethylene glycol monobutyl ether sold by Union Carbide Corporation.

The coatings were applied to steel panels (QD
panels made by the Q-Pane Company) by drawing down the liquid coating compositions with an eight mil doctor blade. The panels were oven dried at 130F for 20 minutes and then baked for 3 minutes at 300F. The following tests were used to evaluate the panels:
Abrasion resistance (wear): ASTM Test No.
D-986, falling sand method. The higher the number, the better the abrasion resistance.
Reverse and direct impact resistance: ASTM
Test D-2794. The higher the number the better the impact resistance.
Adhesion: ASTM Test D-3359. The ~ of film removed with tape is measured with a lower number indi-cating better adhesion.
Gloss: ASTM Test D-523. The higher the number the better the gloss.
Film Hardness by penci~: ASTM Test D-3363.
lB is the softest rating, and 6H is the hardest rating.
Modulus of the polymer: The modulus was measured at 40C (Elx108) determined using a dynamic mechanical thermal analyzer made by Polymer Laborato-ries Limited. The higher number indicates a stiffer polymer film.
.
::
B

~ 55 The next table lists the results of the tests:

Pencil Impact Hardness Direct/ Scratch/
Sample Mbdulus Adhesion Reverse Wear Gouge Gloss M 3.41 7.50.5/0.5 31.8 2H/5H 47.1 N 10.7 2.5 80+/ - 59.2 2B~HB 39.3 0 2.08 ~ 20 1.5/1.5 22.2 2H/3H 57.0 P 2.41 29 0.5/0.5 21.8 2HJ5H 36.6 Q 7.36 0 - /80+ 69.0 2B/HB 18.5 Although the film of the interpenetrating network of the vinyl acetate-ethylene copolymer and polystyrene (sample N), is relatively soft the modulus of the film is surprisingly height, denoting a stiff film. The impact resistance and wear properties of this polymer are also outstanding. The blend of poly-vinyl acetate and polystyrene (sample P) is inferior to the interpenetrating network of ~olyvinyl acetate and polystyrene (sample O) in impact resistance and wear, although the modulus of the films are about equal. The gloss of the coatings of the IPN samples N and O when compared to their respective blends in samples P and Q
showed a significant increase. These results show that the emulsions containing the interpenetrating networks can be used to provide superior coatings binders.

; ~ An interpenetrating network of a vinyl acetate-ethylene copolymer (80%) and polystyrene (20%) ~ \
~ ~ 94 s~

was prepared as follows. The following was charged to a 1 liter glass reactor equipped with a variable agita-tor, temperature control system, feedpumps, and a.water bath for heating and cooling:

Joncryl 678(28.4%)(18) 214.6 g Ethylene-vinylacetate copolymer emulsion (Ex. E) 276.7 9 The batch was heated to 70C, after which the following was added:

Styrene 29.4 g Divinyl benzene 0.02 9 After equilibration (15 minutes) the following catalyst solution was added:

Water (deionized) 8.3 g Potassium persulfate 0.8 g Ammonium hydroxide (28%) 0.09 9 After leaving the batch at 75C for 5 hours the free styrene monomer had decreased to less than 1%, after which the batch was cooled to room temperature.
The interpenetrating polymer network containing emulsion had the following properties:

' ~

t .~!J 95 ~ s solids (30 min at 130C drying) 49.9%
pH 8.5 viscosity (Brookfield at 50 RPM) 1806 cps intrinsic viscosity (measure~ ~n N-methyl pyrrolidone at 30C 6 .89 dl/g free styrene 0.3~

Note: (18) Joncryl 678 is a water-soluble, styrenated acrylic resin sold by the Johnson Wax Corp. It was dissolved in ammonia w,ater to the concentra-tion indicated.

A control emulsion was prepared by blénding the following:

Joncryl 678 (29.4%)(18) 144.8 9 Ethylene-vinylacetate copolymer emulsion (Ex. E) 250 9 Suncryl 7500(19) 54.8 9 The control emulsion had the following properties:

solids (30 min at 130C drying) 46.1%
pH 8.2 viscosity (Brookfield at 50 RPM) 1050 cps Note: (19) Suncryl 7500 is a polystyrene emulsion sold by Sun Chemical Corp. for use as an ink binder. (20) Suncryl 67800 is a styrene-acry-late copolymer emulsion sold by Sun Chemical Corp. for usé as an ink binder.

Using the emulsions of Examples 26 and 27 and Suncryl 7500 (19) and Suncryl 7800(20), the following printing inks were prepared: To ~0 9 of emulsion was added 10 g of isopropyl alcohol and mixed by hand for 5 minutes. To 35 g of this mixturq was added 15 g of a 45.4% solids dispersion in water of the pigment Red Lake C. The ink was stirred by hand for another 5 minutes.
The inks were then applied to a black and white test paper with a Nr. 6 Meyer rod and allowed to dry for about 5 minutes. All inks covered the test paper well and showed equal color value. The gloss was then measured with a Glossgard II, 75 glossmeter (Gardner Instrument Division, SilYer Springs, Mary-land). The glossmeter was first calibrated to a gloss reading of 50.1. The following gloss readings were obtained:

Ink BinderGloss Readinq Heat Resistance Emulsion of Ex. 2680.9 pass Emulsion of Ex. 2777.5 fail Suncryl 7500(19)55.8 pass Suncryl 7800(20)81.7 pass The heat resistance, which is the resistance of alumi-num foil to adhere to the emulsion coated paperboard when subjected to heat and pressure, was measured as follows. The emulsion was appliqd to a piece of clay coated paperboard with a Nr. 6 Meyer rod and allowed to dry for 5 minutes. After this time a piece of aluminum foil was placed on the dried polymer film and then :

..
~1 .

heat-sealed to the paperboard with a Sentinel Heat Sealer (Packaging Industries, Hyannis, Massachusetts), using a pressure of 20 psi and a temperature of 25C.
After cooling the sample to ambient temperature the aluminum foil was carefully lifted up. Any paperboard which still had pieces of aluminum foil adhering to it was judged a failure. The results are ~abulated in the above table.
The ink made using the IPN emulsion of Example 26 had a much higher gloss than the commercial polystyrene emulsion (Suncryl 7500) and equal gloss to the more expensive styrene-acryl~c copolymer emulsion (Suncryl 7800). The blend of the vinyl acetate-ethy-lene copolymer with the polystyrene emulsion (Example 27) had an inferior gloss to the IPN emulsion. The heat resistance of the blend of emulsions (Example 27) was inferior to that of the IPN emulsion.

A polymer emulsion containing an interpenetrating network of vinyl acetate-ethylene copolymer and polystyrene was prepared.
The following was charged to a 1 liter glass reactor equipped with a variable agitator, temperature control system, feedpumps, and a water bath for heating and cooling:

' ,. ,. ~

s Airflex 400 (11) 336 g Water (deionized) 58.2 g Galvatol 20-30 (9.3%)(12) 8.4 Galvatol 20-60 (11.1%)(13) 8.4 Styrene 43.6 g Divinyl benzene 0.5 g Hydrosulfite AWC(3) 0.6 g After mixing, the batch was allowed to equilibrate for 10 minutes and heated to 51C, after which the following catalyst solution was added over 30 minutes:

Water (deionized) 6.7 g Hydrogen peroxide (50%) 0.5 g After the catalyst addition was completed an additional amount of redox agent in water was added as follows:

Water (deionized) 52 g Hydrosulfite AWC(3~ 0.2 g The batch was then heated for an additional 10 minutes at 58C after which it was cooled to room temperature.
The interpenetrating network containing emulsion had the following properties: -D

.

~ 5 solids (30 min at 130C drying) 50.2%
pH 5.5 viscosity (Brookfield at 50 RPM) 1184 CpS
particle size (10) 2.1 microns A polymer emulsion containing an interpenetrating network of vinyl acetate-ethylene copolymer and polystyrene was prepared.
The following was charged to a 1 liter glass reactor equipped with a variable agitator, temperature control system, feedpumps, and a water bath for heating and cooling:

Airflex 400(11) 336 g Water (deionized) 81.9 g Galvatol 20-30 (9,3%)(12) 15.4 Galvatol 20-60 (11.1~)(13) 15.4 Styrene 79.9 g Divinyl benzene 0.4 g Hydrosulfite AWC(3) 1.1.9 After mixing, the batch was allowed to : equilibrate for 10 minutes and heated to 50C, after which the following catalyst solution was added over 30 minutes:
:
:: Water (deionized) 12.3 g ~; Hydrogen peroxide (50~) 0.9 g After the catalyst addition was completed, 50 ~; ~ g of water were added to the batch. The batch was then \

5~;

heated for an additional 30 minutes at 56C after which it was cooled to room temperature.
The interpenetrating network containing emulsion had the following properties:

solids (30 min at 130C drying) 55.4%
pH ~.9 viscosity (Brookfield at 50 RPM) 4890 cps particle size (10) `! 2.2 microns EXAMPLE ~1 An ethylene-vinyl acetate copolymer emulsion was prepared. The following was charged to a 10 gal.
stainless steel pressure reactor equipped with a vari-able agitator set at 60 rpm, temperature control sys-tem, feedpumps, means for purging the reactor with nitrogen and pressurizing with ethylene, and an inter-nal coil for heating and cooling:

Water (deionized) 7500 g Emcol K8300 (2) 120 g Triton X 405 (8) 85 g Tamol SN (14) 17 g Ferrous sulfate (10% Solution) 8 g The contents of the reactor were heated to 50C, the reactor was purged with nitrogen once, and with ethylene twice to 10 psi, followed by the addition of:

Vinyl acetate 400 g . ,_.un~ 1 01 ~.~ _ ' '''' , ~æ96455 The reactor was then pressurized with ethylene to 800 psi. This was fo~lowed by the addition of the initial catalyst solution:

Water (deionized) 7500 9 Ammonium persulfate . 13 g The polymerization was initiated by adding an activator solution at a rate of 5 g/min which was made up as follows:

Water (deionized) 1500 g Hydrosulfite AWC (3) 50 g . The polymerization ini~iated within 5 minutes as indicated by a rise in reactor temperature.
The following monomer emulsion, prepared previously was then added gradually by means of an addition pump at a rate of 43 g/minutes over a 3 hour period:

Water (deionized) 4000 g Emcol K8300 (2) 250 g Monoethyl maleate 140 g Ammonium hydroxide (28%) 9 9 Vinyl acetate 8300 9 Triallyl cyanurate 1 g Ammonium persulfate 100 g : : The temperature of the reactor content was allowed to rise to 55C and was maintained there by the addition of the above mentioned activator solution as ; ~

~ B~ '102 needed. At this point, the ethylene pressure rose to 900 psi and was maintained there by setting the ethy-lene supply valve to 900 psi. A total of 1500 g of the activator solution was used.
After 3 hours, when all the monomer emulsion and activator solution had been added to the reactor, the following finishing catalyst solution was added:

Water (deionized~ 400 g Ammonium persulfate 25 g t-butyl hydroperoxide 15 g followed by addition of the following finishing activa-tor solution:

Water (deionized) 400 g Hydrosulfite AWC (3) 20 g The temperature of the batch was maintained at 60C for an additional hour after which the free vinyl acetate monomer concentration had fallen below 1%. The polymer emulsion was thqn cooled to 30C and the ethylene vented from the reactor to ambient pres-sure. The following solution was then added to the -batch:

Water (deionized) 500 g Triton X 405 (8) 85 g Ammonium hydroxide (28%) 50 g The emulsion had the following properties:

, ~ 5 solids (30 min at 130C drying) 44.6%
pH 7.4 viscosity (Brookfield at 50 RPM) 41.6 cps intrinsic viscosity (measured in N-methyl pyrrolidone at (30C)(6) 1.50 dl/g particle size (10) 0.13 microns ethylene content of the copolymer 18.5%
Glass transition temperature (15) 0C

A polymer emulsion containing a polymer which is an interpenetrating network of a vinyl acetate-ethy-lene copolymer (70%) and polystyrene(30%) was prepared.
The following was charged to a 1 liter glass reactor equipped with a variable agitator, temperature control system, feedpumps, and a water bath for heating and cooling:

Emulsion of Example 31 1503 g Water (deionized) 120.1 9 Monoethyl maleate 2.1 g Styrene 283.5 g Divinyl benzene 0.29 g Ammonium persulfate 4.3 g t-Butyl hydroperoxide 2.1 g After mixing, the batch was allowed to : equilibrate for.10 minutes and heated to 55C, after :~ ~ which the following activator so~ution was added:

: Water (deionized) 108.9 g Hydrosulfite AWC(3) 2.1 g ' $~;~

s~

After the initiation was observed by an increase in temperature the following emulsifier solu-tion was added over 15 minutes:

Water (deionized) 63.3 9 Emcol K8300(2) 19.2 g Triton X 405(8) 13.5 g Sipomer DS 10 (16) 4.3 9 After leaving the batch at 58C for 2 hours, it was then cooled to room temperature and the follow-ing solution was added:

Water 29.2 g Triton X 405 (8) 14.9 g Ammonium hydroxide (28%) 10.7 g Formaldehyde (37%) 0.7 g Proxel GXL(4) 1.4 g The interpenetrating network containing emulsion had the following properties:

solids (30 min at 130C drying) 45.4%
pH 3.6 viscosity (Brookfield at 50 RPM) 40.8 CpS
intrinsic viscosity (measured in N-methyl pyrrolidone at 30C)(6) 1.43 dl/g partiCle size (10) 0.20 microns :: .

;~ A polystyrene emulsion was prepared. The :~ following was charged to a 3 liter stainless steel ~ \

~296455 laboratory reactor equipped with a variable agitator, temperature control system, feedpumps, means for purg-ing the reactor with nitrogen, and a waterbath for heating and cooling:

Water 850 g Triton X 305(1) 18 g Ferrous sulfate (1% solution in water) 1 g The contents of the reactor were heated to 68C after which the reactor was purged with nitrogen.
After the heat-up and purge, the followin~ monomer was added to the reactor:

Styrene . 129 g This was followed by the addition of the initial cata-lyst solution:

Water 129 g Potassium persulfate 2.6 g The polymerization initiated within 5 minutes as indicated by a rise in temperature of the reactor.

The following monomer emulsion, made up previously, was then added gradually by means of an addition pump at a rate of 9 g/minute over a 3 hour period:

~ .
:

~ 106 Water 284 g Emcol K8300( ) 40 g Triton X 305(1) 30 g Acrylamide (50~) 60 g Styrene 1148 g Itaconic acid 15 g Triallyl cyanurate 1.2 9 Ammonium hydroxide (28~)to a pH of 3.6 The temperature of the reactor content was allowed to rise to 74-75C and was maintained there by the gradual addition at a rate of 0.73 g/minute over a 3 hour period of the following catalyst solution:

Water 129 g Potassium persulfate 2 g After 3 hours, when all the monomer emulsion had been added to the reactor, the following finishing catalyst solution was added:

Water 20 g t-Butyl hydroperoxide 1 g followed by a reducing solution:

Water 2 g : Hydrosulfite AWC(3) 0.5 g ~: The temperature of the batch was maintained at 73C for an additional 30 minutes, after which the ~:polymer emulslon was cooled to room temperature. The ;S

copolymer emulsion thus obtained had the following properties:

solids (30 min at 130C drying) 45.5%
pH 4.0 viscosity (Brookfield at 50RPM) 38 cps intrinsic viscosity (measured in N-methyl pyrrolidone a~ 30OC)(6) 1.3 dl/g particle size (10) 0.17 micron An emulsion blend was made by mixing the following polymer emulsions:

emulsion of Example 31 1349 g emulsion of Example 33 566.9 g The emulsion blend had the following properties:

solids (30 min at 130C drying) 44.2%
pH 4.25 viscosity (Brookfield at 50 RPM) 40 cps :~ An emulsion blend was made by mixing the following polymer emulsions:

Airflex 400(11) 525.4 g ~:~ emulsion of Example 33 274.6 g :~ ~ The emulsion blend had the following properties:
, :: !
;~

~ 108 5~

solids (30 min at 130~ drying) 43.8 pH 5.5 viscosity (Brookfield at 50 RPM) 1292 cps ~ote: (11) Airflex 400 is a vinyl acetate-ethylene copolymer emulsion having an approximate ethy-lene content of 18.5%. It is supplied by Air Products and Chemicals Corporation.

(12) Gelvatol 20-30 is a partially hydrolyzed polyvinyl alcohol supplied by the Monsanto Com-pany.

(13) Gelvatol 20-60 is a ~artially hydrolyzed polyvinyl alcohol supplieq by the Monsanto Com-pany.

(14) Tamol SN is a dispersant supplied by the Rohm & Haas Company.

(15) The glass transition temperature (Tg) of the polymer was determined by reading the peak tan delta value measured by DMTA (Dynamic Me-chanical Thermal Analyzer) on a Polymer Labora-tories DMTA apparatus operating at a frequency of 1 Hertz.

(16) Sipomer DS 10 is a brand of sodium dodecylbenzene sulfonate supplied by the Alcolac Chemical Company.

, .

:

~ ~ 109 : .

(17) Vinac XX 210 is a vinyl acetate homopolymer emulsion. It is supplied by Air Products and Chemicals Corporation.

The emulsions of Examples 29, 30 and 35, as well as Airflex 400(11) and Vinac XX210(17) were used without modification as a wood adhesive. Two mood blocks each, made from ~ inch plywood, measuring 2 inches by inches, were coated half with the emulsion using a #6 Meyer rod. The woodblocks were then united at the emulsion coated surfaces and clamped together with a ~C"
clamp. The wood assembly was then allowed to dry at ambient temperature for 24 hours. After this time the clamp was removed and the woodblocks were broken apart.
It was then determined how much wood fiber tear (wood failure) occurred and a percentage figure was assigned.
The following table lists the results:
Test Emulsion % Woad Failure Emulsion of Example 30 (IPN)100%
Emulsion of Example 29 (IPN)90%
Airflex 400 (11) 50%
Vinac XX 210 (17) 20~
Emulsion of Example 35 (Blend) none It can be seen from these results that the emulsions containing the IPN provided superior wood adhesives when compared to the blend of polyvinyl acetate-ethylene copolymer and polystyrene, and also compared to commerically available emulsions.

:

55`

The emulsions of Examples 32 and 34 were tested without further modification as laminating adhe-sives for cloth to cloth and cloth to polyester film laminates. The specimens to be 71ued together were coated with the emulsions using a #6 Meyer rod and were then air dried, after which they were hot pressed at a temperature of 110C for 1 minute at 1500 psi. They were then allowed to condition at 50% relative humidity and 72F for 24 hours. The tensile strength of the glued specimens were tested with an Instron tensile tester at a crosshead speed of 20 cm per minute with a 5000 g load cell with the following results:

Emulsion Tensile Strenath ~ka/cm2) cloth cloth to to clothPE film Emulsion of Example 32 (IPN) 12.2 12.89 Emulsion of Example 34 (Blend) 7.39 8.43 .
It can be seen that the IPN containing emulsion provided a stronger laminating adhesive than the emulsion containing the blend of polyvinyl acetate-ethylene and polystyrene.

A polymer emulsion was prepared containing a polymer which was an interpenetr~ting networ~ of a vinyl acetate-ethylene copolymer and a styrene/2-ethyl hexyl acrylate copolymer. The following was charged to a 1 liter glass reactor equipped with a variable agita-tor, temperature control system, feedpumps, and a water bath for heating and cooling:
' F'~ ~.
~i \ ' ~ 55 Emulsion of Example 31 250 g Water (deionized) 25.1 g Triton X-305(1) 0.8 g Emcol K 8300(2) 0.8 g N-methyl acrylamide (49%) 1.4 g Styrene 6.9 g 2-Ethyl hexyl acrylate 20.9 g Divinyl benzene 0.06 g Itaconic acid 0.3 g Potassium persulfate 0.3 g t-Butyl hydroperoxide 0.1 g The batch was heated to 62C, equilibrated for 10 minutes, after which the following activator solution was added:

Water (deionized) 2.6 g Hydrosulfite AWC(3) 0.} g After keeping the batch for one hour at 65C
. an additional activator solution was added as follows:

Water (deionized) 5 g ~ydrosulfite AWC(3) 0.1 g ` After leaving the batch at 65C for an additional 15 minutes, it was cooled to room tempera-: ture.

he interpenetrating network containing emulsion had the following properties:

~ ~:

1~2 *~5S

solids (30 min at 130C drying) 43.9%
pH 4.05 viscosity (Brookfield at 50 RPM) 40 cps intrinsic viscosity (measured in N-methyl pyrrolidone a~ 30C)(6) 0.8 dl/q particle size(7) 0.19 micron A styrene/2-ethyl hexyl acrylate copolymer emulsion was prepared. The following was charged to a 3 liter stainless steel laboratory reactor equipped with a variable agitator, temperature control system, feedpumps, means for purging the reactor with nitrogen, and a waterbath for heating and cooling:

Water 555 g Triton X 305(11 10.1 g Ferrous sulfate (1% so~ution in water) 1 g : The contents of the reactor were heated to 68~C after which the reactor was purged with nitrogen.
~: After the heat-up and purge the following monomer was added to the reactor:

Styrene 15.8 g : 2-Ethyl hexyl acrylate 55.8 g This was followed by the addition of the initial catalyst solution:

~: 113 Water 71.6 9 Potassium persulfate 1,4 g The polymerization initiated within 5 minutes as indicated by a rise in temperature of the reactor.
The following monomer emulsion, made up previouslyl was then added gradually by means of an addition pump at a rate of 5.1 g/minute over a 3 hour period:

Water 2157.6 9 Emcol K8300(3) 22.2 9 Triton X 305(1) 16.7 9 N-methylol acrylamide (49%) 72.2 g Acrylamide (50%) 5.6 y Styrene 140.2 g 2-Ethyl hexyl acrylate 497 g Itaconic acid 8.3 g Triallyl cyanurate 0.7 g The temperature of the reactor content was allowed to rise to 74-76C and was maintained there by the gradual addition at a rate of 0.4 g/minute over a 3 hour period of the following catalyst solution:

~: 'Water 71.6 g Potassium persulfate 1.1 9 After 3 hours, when all the monomer emulsion :; had been added to the reactor the following finishing ~ : catalyst solution was added:
: ::

,~

~ ~ 114 ~.2~ ;5 Water (deionized) 5 9 Hydrosulfite AWC (3) 0.8 g The temperature of the batch was maintained at 78C for an additional 30 minutes, after which the polymer emulsion was cooled to room temperature. The copolymer emulsion thus obtained had the following properties:

solids (30 min at 130C drying) 36.4%
pH 4.0 viscosity (Brookfield at 50 RPM) 26 cps intrinsic viscosity (measured in N-methyl pyrrolidone at 30C)(6) 0.23 dl/g particle size (by light transmission)(7) 0.13 micron A blend was made by mixing the following polymer emulsions:

Emulsion of Example 31 387.1 g Emulsion of Example 39 112.9 g : The emulsion blend had the following : properties:

~:: solids (30 min at 130C drying) 42.2%
: pH 4.45 ^,,``, The emulsions of Exampl~s 38 and 40 were tested as pressure sensitive adheFives as follows: A 8 1/2 x 11 sheet of Mylar film (po~yethylene terephtha-late film ~y E.I. DuPont De Nemours & Company) was washed with soapy water, dried and coated with the emulsion using a #20 Meyer rod. After air drying the coated film overnight, two 1 inch by 6 inch strips of the coated Mylar film were cut. One was put coated face down on the coated side of the other Mylar strip and rolled with a 4 pound roller 5 times (adhesive sandwiched in the center). Scotch adhesive tape (no.
810 Magic Transparent Tape by the 3M Corporation) was used as the control. The 180 peel was then measured using an Instron tensile tester at 8 inches/minute pull with a 5000 g loàd cell.
The following table lists the results:

Tape Tensile Strenath (kq~cm ) Emulsion of Example 38 (IPN) 17.2 Emulsion of Example 40 (Blend) 12.6 Scotch Tape 14.8 It can be seen that the IPN containinq emulsion provided a stronger pressure sensitive adhe-sive than the emulsion containing the blend of polyvi-nyl acetate-ethylene and polystyrene - 2-ethyl hexyl acrylate. It even provided a st~onger pressure sensi-tive adhesive than the commerFial Scotch adhesive tape.

:: ~

Claims (45)

1. Process for preparing an aqueous polymer comprising:
a) forming a first polymer emulsion con-taining an active crosslinking agent;
b) mixing a second monomer emulsion with the first polymer emulsion;
c) allowing the emulsion mixture to equilibrate; and d) then polymerizing the emulsion mix-ture providing a first polymer net-work which is intertwined on a molec-ular scale with the second polymer network, wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95%
on a solids by weight basis of the emulsion mixture.

2. Process of claim 1 wherein the first polymer emulsion is formed by polymerizing a first mon-omer emulsion.

3. Process of claim 1 wherein the first polymer emulsion is formed by emulsifying a polymer.

4. Process of claim 1 wherein the first polymer emulsion comprises 20 to 80% on solids by weight basis of the emulsion mixture.

5. Process of claim 1 wherein the second monomer emulsion contains a crosslinking agent selected from the group consisting of an active crosslinking agent, a latent crosslinking agent, and mixture there-of.

6. Process of claim 5 wherein at least one of the first polymer emulsion and the second monomer emulsion contains a latent crosslinking monomer.

7. Process of claim 6 wherein the polymer in the first polymer emulsion is chosen from the group consisting of polymethyl methacrylate, polyvinyl acetate, polystyrene, polyacrylo nitrile and copolymers thereof.

8. Process of claim 7 wherein the monomer in the second monomer emulsion is chosen from the group consisting of acrylo nitrile, methyl methacrylate, butylacrylate, styrene and mixtures thereof.

9. Process of claim 1 wherein the first polymer emulsion is based upon a monomer which is not an inhibitor to polymerization of the momer in the second monomer emulsion.

10. Process of claim 1 wherein the first polymer emulsion contains polyvinyl acetate and the second monomer emulsion contains a monomer selected for the group consisting of styrene, methyl methacrylate, butylacrylate, acrylo nitrile and mixtures thereof.

11. Process of claim 1 wherein the first polymer emulsion is based upon a monomer which is incompatible with the monomer in the second monomer in the second monomer emulsion in that they cannot be copolymerized.

12. Process as in one of claims 1, 5 or 6 further comprising applying the polymer emulsion to a substrate, then drying and heating to complete the bonding of the first and second networks.

13. Process of claim 12 wherein the polymer emulsion is further applied to a substrate as a binder, adhesive or coating.

14. Process of claim 13 wherein the polymer emulsion is further applied to a substrate chosen from the group consisting of textile fibers, non-woven fabrics, woven fabrics and knitted textile fabrics.

15. A fiberfill product comprising a fiberfill bound by a binder comprising an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network, wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion mixture.

16. Product of claim 15 wherein the polymer of the first polymer network is chosen from the group consisting of polymethyl methacrylate, polyvinyl acetate, polystyrene, polyacrylo nitrile and copolymers thereof.

17. Product of claim 16 wherein the polymer of the second polymer network is different from the first polymer and is chosen from the group consisting of polyacrylo nitrile, polymethyl methacrylate, polybutylacrylate, polystyrene and copolymers thereof.

18. Product of claim 15 wherein the first polymer and second polymer are incompatible in that they cannot be copolymerized.

19. An aqueous polymer emulsion comprising: a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network, wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion mixture.

20. Polymer emulsion of claim 19 wherein the polymer of the first polymer network is chosen from the group consisting of polymethyl methacrylate, polyvinyl acetate, polystyrene, polyacrylo nitrile and copolymers thereof.

21. Product of claim 20 wherein the polymer of the second polymer network is different from the first polymer and is chosen from the group consisting of polyacrylo nitrile, polymethyl methacrylate, polybutylacrylate, polystyrene and copolymers thereof.

22. Product of claim 19 wherein the first polymer and second polymer are incompatible in that they cannot be copolymerized.

CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE:

23. A nonwoven product comprising a fiber or fabric bound by a binder comprising an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network, wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion.

24. Product of claim 23 wherein the fiber is made from a composition chosen from the group consisting of glass, rayon, cotton, nylon, polyester, graphite and wood.

25. Product of claim 23 wherein the monomers of the first polymer and second polymer cannot be copolymerized.

26. Product of claim 25 wherein the first polymer comprises 30 to 90% and the second polymer comprises 10 to 70% on a solids by weight basis of the emulsion.

27. A glass fiber nonwoven mat bound by a binder comprising an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network, wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion.

28. Product of claim 27 wherein the monomers of the first polymer and second polymer cannot be copolymerized.

29. Product of claim 27 wherein the first polymer network contains a vinyl acetate-ethylene copolymer.

30. A coating composition comprising: an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion.

31. Composition of claim 30 wherein the coating composition is a paper or paperboard coating composition.

32. Composition of claim 31 further comprising a pigment.

33. Composition of claim 31 further comprising a binder chosen from the group consisting of proteins, resins, polyvinyl alcohol, alginates and starches.

34. An industrial and architectural coating composition comprising: an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion.

35. Composition of claim 34 further comprising: a pigment and a dispersant for the pigment.

36. Composition of claim 35 further comprising a wetting agent.

37. A printing ink composition comprising: a piqment and an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion.

38. Composition of claim 37 wherein the printing composition is a water-based printing ink composition.

39. Composition of claim 38 further comprising a water-soluble protective colloid.

40. Composition of claim 38 further comprising a binder chosen from the group consisting of proteins, resins, polyvinyl alcohol, alginates and starches.

41. Composition of claim 38 wherein the polymer emulsion comprises 2 to 45% on a solids by weight basis of the printing ink composition.

42. An adhesive composition comprising an aqueous polymer emulsion containing a first polymer network containing an active crosslinking agent which is intertwined on a molecular scale with a second polymer network, wherein the second polymer differs from the first polymer and the first polymer comprises 5 to 95% on a solids by weight basis of the emulsion.

43. Composition of claim 42 further comprising a protective colloid.

44. Composition of claim 43 further comprising a plasticizer, a solvent and a filler.

45. Composition of claim 43 wherein the protective colloid is selected from the group consisting of polyvinyl alcohol, hydroxyethyl cellulose, sodium carboxymethyl cellulose, styrenated acrylics and polyvinyl pyrrolidone.