|Publication number||WO2000069930 A1|
|Publication date||23 Nov 2000|
|Filing date||12 May 2000|
|Priority date||14 May 1999|
|Also published as||CA2372056A1, CN1367801A, EP1183286A1|
|Publication number||PCT/2000/13159, PCT/US/0/013159, PCT/US/0/13159, PCT/US/2000/013159, PCT/US/2000/13159, PCT/US0/013159, PCT/US0/13159, PCT/US0013159, PCT/US013159, PCT/US2000/013159, PCT/US2000/13159, PCT/US2000013159, PCT/US200013159, WO 0069930 A1, WO 0069930A1, WO 2000/069930 A1, WO 2000069930 A1, WO 2000069930A1, WO-A1-0069930, WO-A1-2000069930, WO0069930 A1, WO0069930A1, WO2000/069930A1, WO2000069930 A1, WO2000069930A1|
|Inventors||Morgan Mark Hughes, Kim Louis Walton, Christian Daniel|
|Applicant||Dupont Dow Elastomers L.L.C.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (9), Referenced by (31), Classifications (44), Legal Events (14)|
|External Links: Patentscope, Espacenet|
HIGHLY CRYSTALLINE EAODM IN ERPOLYMERS
FIELD OF THE INVENTION
This invention relates to random ethylene/alpha (α) -olefin/polyene (EAODM) interpolymers containing at least 84 weight percent (wt%) ethylene and the use of such interpolymers in combination with other polyolefins, rubbers, and thermoplastic formulations . This invention also relates to crosslinked or cured EAODM interpolymers and the use of such crosslinked interpolymers to produce fabricated articles including, but not limited to, wire and cable products, foams, automotive components, tubing, tapes, laminates, coatings and films. This invention further relates to blends of the polymers of this invention with both natural and synthetic polymers, especially to thermoplastic polyolefins (TPO) . This invention additionally relates to EAODM polymers that are grafted with other monomers, such as unsaturated carboxylic acid monomers, and the use of such grafted interpolymers as, for example, impact modifiers, compatibilizers and adhesion promoters.
BACKGROUND OF THE INVENTION
Polyolefins are used in numerous applications including, but not limited to, wire and cable insulation, automotive interior skins, impact modification of other polyolefins, foams, and films. Many of these applications demand ever-increasing improvements in heat resistance. One method to improve polyolefin heat resistance involves crosslinking or curing the polyolefin using either a source of radiation such as electron beam (EB) radiation, gamma radiation or ultraviolet (UV) radiation, or a heat- activated chemical crosslinking agent such as a peroxide. Additionally, when the polyolefin contains unsaturation, the heat-activated chemical crosslinking agent may be sulfur, a phenolate, or a silicon hydride. Manufacturers of cured elastomeric parts engage in an ongoing search for polyolefins with improved curing characteristics that provide one or more additional benefits such as faster productivity to reduce manufacturing costs .
For polyethylene (PE) , an increase in crosslink density typically requires using more peroxide or an increased level of radiation exposure, both of which increase cost. Those who work with PE desire an effective, but more economical approach.
The interpolymers of this invention have unsaturated sites that permit grafting of polar materials onto the interpolymer backbone. Skilled artisans recognize that nonpolar polyolefins, particularly PE, provide poor substrates for application of polar coating materials such as paint. In order for paint to effectively adhere to PE, PE surfaces are usually treated to improve compatibility using techniques such as flame surface treatment and corona discharge. An alternate technique changes the polymer itself and involves grafting polar materials onto the polymer backbone . SUMMARY OF THE INVENTION
One aspect of the present invention is an interpolymer composition comprising a random EAODM interpolymer that comprises (a) ethylene in an amount of from 84 to 99 weight percent (wt%) , (b) an α-olefin containing from 3 to 20 carbon atoms (C3.20) in an amount within a range of from greater than (>) 0 to less than (<) 16 wt%, and (c) a polyene in an amount of from > 0 to 15 wt%, all percentages being based upon interpolymer weight and selected to total 100 weight percent, the interpolymer having a crystallinity > 16 percent and a glass transition temperature (TB) of -45° centigrade (°C) or greater. By way of example, a Tg of -40°C is > a Tg of -45°C. For comparison, an EAODM having 85 wt% ethylene, 10 wt% propylene, and 5 wt% diene has a 91.5 mol% ethylene content. The resulting interpolymers may, if desired, be crosslinked chemically using agents such as peroxides, sulfur, phenolates and silicon hydrides or by radiation using any of EB, gamma and UV radiation.
As used herein, "interpolymer" refers to a polymer having polymerized therein at least three monomers. It includes, without limitation, terpolymers and tetrapolymers . A "copolymer" has polymerized therein two monomers .
When crosslinked, the ethylene interpolymers of this invention exhibit improved mechanical strength, heat resistance, and cure properties relative to crosslinked ethylene interpolymers prepared from the same monomers but with a lower ethylene content.
DETAILED DESCRIPTION OF THE INVENTION
Skilled artisans recognize that polyolefins with unsaturation have greater crosslinking efficiency than those that lack unsaturation. Improved crosslink efficiency generally translates into faster cure, increased mechanical strength, and, for an end use manufacturer, increased productivity. The EAODMs of the present invention, when blended with polyolefins, provide a means to increase polyolefin crosslink density without resorting to conventional techniques such as using more peroxide or increasing radiation exposure .
Polymer crystallinity has an impact on physical properties such as tensile strength, green strength, and flex modulus. Reductions in polymer crystallinity typically lead to a corresponding reduction in tensile strength, green strength, and flex modulus. Commercially available polyolefins, such as high density polyethylene (HDPE) , typically have a crystallinity within a range of 45% to 95%. Conventional EAODM polymers have a crystallinity within a range of 0% to 16%. When such conventional EAODM polymers are blended with HDPE or another crystalline polyolefin, the resulting blend has a reduced crystallinity relative to the crystalline polyolefin. By way of contrast, the EAODMs of the present invention have a crystallinity, measured by Differential Scanning Calorimetry (DSC) , within a range of from > 16 wt% to <75 wt%, preferably from > 19 wt% to 40 wt% .
Unless otherwise stated herein, a numerical range includes both endpoints .
EAODM interpolymers suitable for this invention include polymers having polymerized therein ethylene, at least one C3.20, preferably C3.10, α-olefin, and at least one polyene. Skilled artisans can readily select appropriate monomer combinations for any desired interpolymer so long as the interpolymer meets the requirements, such as the ethylene content and crystallinity requirements stated herein.
The EAODM interpolymers of this invention have an ethylene content of at least 84 wt%, preferably at least 88 wt%, and more preferably at least 90 wt%, but in no event more than 99 wt% ethylene. The ethylene content may vary up or down by a few percentage points depending upon amount and weight of polyene in the EAODM. In general, choices for amounts of ethylene, α-olefin and polyene provide a ratio of ethylene to α-olefin of at least 95:5, preferably > 95:5. EAODMs with > 84 wt% ethylene possess a DSC crystallinity as described above. It is believed that this crystallinity provides much of the polymer's mechanical strength. Polymer crystallinity increases lead to proportional increases in polymer Tg. The interpolymers of this invention have a Tg, as measured by DSC, of > -45° Centigrade (°C) , preferably > -40°C. Skilled artisans recognize that endothermic melting peaks obscure Tg as polymer crystallinity increases . As such, there is no meaningful upper limit for T . The α-olefin may be either an aliphatic or an aromatic compound and may contain vinylic unsaturation or a cyclic compound, such as cyclobutene, cyclopentene, or norbornene, including norbornene substituted in the 5 and 6 position with a Cx_20 hydrocarbyl group. The α-olefin is preferably a C3_20 aliphatic compound, more preferably a C3_16 aliphatic compound and still more preferably a C3_10 aliphatic compound such as propylene, isobutylene, butene-1, pentene-1, hexene-1, 3-methyl-l-pentene, 4-methyl-l- pentene, octene-1, decene-1 and dodecene-1. Other preferred ethylenically unsaturated monomers include 4- vinylcyclohexene, vinylcyclohexane, norbornadiene, and mixtures thereof . The most preferred α-olefins are propylene, butene-1, hexene-1 and octene-1. The α- olefin content is preferably from > 0 to < 16wt%, more preferably from 1 wt% to 10 wt%, and most preferably from 2 wt% to 8 wt% , based on total interpolymer weight .
The polyene, sometimes referred to as a diolefin or a diene monomer, is desirably a C4.40 polyene. The polyene is preferably a nonconjugated diolefin, but may be a conjugated diolefin. The nonconjugated diolefin can be a C6.15 straight chain, branched chain or cyclic hydrocarbon diene. Illustrative nonconjugated dienes are branched chain acyclic dienes such as 2-methyl-l, 5-hexadiene, 6- methyl-1, 5-heptadiene, 7-methyl-l, 6-octadiene, 3,7- dimethyl-1, 6-octadiene, 3 , 7-dimethyl-1, 7-octadiene, 5 , 7-dimethyl-l, 7-octadiene, and mixed isomers of dihydromyrcene; single ring alicyclic dienes such as 1, 4-cyclohexadiene, 1, 5-cyclooctadiene and 1,5- cyclododecadiene; multi-ring alicyclic fused and bridged ring dienes such as tetrahydroindene, methyl tetrahydroindene, dicyclopentadiene (DCPD) , bicyclo- (2 , 2 , 1) -hepta-2 , 5-diene (norbornadiene or NBD) , methyl norbornadiene; alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbornenes such as 5-methylene-2- norbornene (M B) , 5-ethylidene-2-norbornene (ENB) , 5- propenyl-2-norbornene, 5-isopropylidene-2-norbornene, 5- (4-cyclopentenyl) -2-norbornene and 5-cyclohexylidene- 2-norbornene. When the diolefin is a conjugated diene, it can be 1, 3-pentadiene, 1, 3-butadiene, 2-methyl-l, 3- butadiene, 4-methyl-l, 3-pentadiene, or 1,3- cyclopentadiene . The diene is preferably a nonconjugated diene selected from ENB and NBD, more preferably, ENB. The EAODM polyene monomer content is preferably within a range of from > 0 to < 5 mole percent (mol%) , based on moles of ethylene, α-olefin and. On a weight basis, the EAODM polyene monomer content equates to the mole percent limitations and will vary depending upon weight of the polyene. Broadly speaking, the polyene content is from > 0 to 15 wt%, more preferably from 0.3 to 12 wt%, and most preferably from 0.5 to 10 wt% based on interpolymer weight. When the polyene monomer is ENB, a monomer content of from > 0 to < 11 wt%, based on interpolymer weight, generally equates to the >0 to < 3 mol% range .
Molecular weight distribution (MWD) is a well-known variable in polymers. It is sometimes described as the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (i.e., Mw/Mn) and can be measured directly or more routinely by measuring polymer melt index (I) using ASTM D-1238 (190°C /10 kilograms (kg)) for l10 and ASTM D-1238 (190°C /2.16 kg) for I2. and calculating the I10/I2 ratio. Polymers having a narrow MWD exhibit higher toughness, better optics, and higher crosslink efficiencies than polymers with the same monomer composition, but a comparatively broader MWD. The MWD values of the interpolymers of this invention, prepared with metallocene catalysts, particularly constrained geometry catalysts (CGCs) , are from > 1 to 15, preferably from > 1 to 10 and most preferably from > 1 to 4.
The EAODM interpolymers of this invention have a melting point (mpt) of > 70°C. The mpt is desirably > 80°C, preferably > 85°C. The mpt is desirably < 135°C, preferably < 125°C. Mpts of < 70°C effectively exclude certain applications that require a relatively high upper service temperature (UST) such as wire and cable jacketing materials with an UST requirement > 70°C. Skilled artisans recognize that a theoretical upper melt point limit is established by HDPE homopolymer with a mpt of approximately 135°C (varies with polymer molecular weight) .
The EAODM interpolymers of this invention have a heat of fusion > 11 calories per gram (cal/g) . The heat of fusion is desirably > 12 cal/g, and preferably > 13 cal/g. The heat of fusion may be as great as 30 cal/g or even higher depending on a variety of factors, one of which is interpolymer crystallinity.
The EAODM interpolymers of this invention can be produced using one or more metallocene or constrained geometry (CGC) catalyst in combination with an activator, in solution, slurry, or gas phase processes . The catalysts are preferably mono- or bis- cyclopentadienyl, indenyl, or fluorenyl transition metal (preferably Group 4) catalysts, and more preferably mono-cyclopentadienyl, mono-indenyl or mono- fluorenyl CGCs . The solution process is preferred. US patent 5,064,802; WO93/19104 (US serial number 8,003, filed January 21, 1993), and WO95/00526 disclose constrained geometry metal complexes and methods for their preparation. Variously substituted indenyl containing metal complexes are taught in WO95/14024 and W098/49212. The relevant teachings of all of the foregoing patents and their corresponding US patent applications are hereby incorporated by reference. In general, polymerization may be accomplished at conditions well known in the art for Ziegler-Natta or Kaminsky-Sinn type polymerization reactions, that is, temperatures from 0-250°C, preferably 30-200°C, and pressures from atmospheric to 10,000 atmospheres (1013 megapascals (MPa)).
Suspension, solution, slurry, gas phase, solid state powder polymerization or other process conditions may be employed if desired. A support, especially silica, alumina, or a polymer (especially poly (tetrafluoroethylene) or a polyolefin) may be employed, and desirably is employed when the catalysts are used in a gas phase polymerization process . The support is preferably employed in an amount sufficient to provide a weight ratio of catalyst (based on metal) : support within a range of from 1:100,000 to
1:10, more preferably from 1:50,000 to 1:20, and most preferably from 1:10,000 to 1:30. In most polymerization reactions, the molar ratio of catalyst :polymerizable compounds employed is from 10" 12: 1 to 10"l:l, more preferably from 10"9:1 to 10"5:1. Inert liquids serve as suitable solvents for polymerization. Examples include straight and branched-chain hydrocarbons such as isobutane, butane, pentane, hexane, heptane, octane, and mixtures thereof; cyclic and alicyclic hydrocarbons such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof; perfluorinated hydrocarbons such as perfluorinated C4.10 alkanes; and aromatic and alkyl- substituted aromatic compounds such as benzene, toluene, xylene, and ethylbenzene . Suitable solvents also include liquid olefins that may act as . monomers or comonomers including butadiene, cyclopentene, 1-hexene, 1-hexane, 4-vinylcyclohexene, vinylcyclohexane, 3- methyl-1-pentene, 4-methyl-l-pentene, 1, 4-hexadiene, 1- octene, 1-decene, styrene, divinylbenzene, allylbenzene, and vinyltoluene (including all isomers alone or in admixture) . Mixtures of the foregoing are also suitable. If desired, normally gaseous olefins can be converted to liquids by application of pressure and used herein.
The catalysts may be utilized in combination with at least one additional homogeneous or heterogeneous polymerization catalyst in the same reactor or in separate reactors that are connected in series or in parallel to prepare polymer blends having desirable properties. An example of such a process is disclosed in WO 94/00500 at page 29 line 4 to page 33 line 17. The process uses a continuously stirred tank reactor (CSTR) connected in series or parallel to at least one other CSTR or tank reactor. WO 93/13143 (at page 2 lines 19-31) teaches polymerizing monomers in a first reactor using a first CGC having a first reactivity and polymerizing monomers in a second reactor using a second CGC having a second reactivity and combining the products from the two reactors. Page 3, lines 25-32 of WO 93/13143 provides teachings about the use of two CGCs having different reactivities in one reactor. WO 97/36942 (page 4 line 30 through page 6 line 7) teaches the use of a two loop reactor system. The relevant teachings of such applications and their corresponding U.S. patent applications are incorporated herein by reference. . Additionally, the same catalyst may be utilized in both reactors operating at different processing conditions . The EAODM interpolymers of this invention may be combined with other natural or synthetic polymers into a blend that contains from 2 to 98 wt% of such EAODM interpolymer (s) based on total blend weight. The natural and synthetic polymers can be natural rubber, styrene-butadiene rubber (SBR) , butadiene rubber, butyl rubber, polyisoprene, polychloroprene (neoprene) , or homopolymers of monoolefins or a mixture of two or more monoolefins, preferably a C2.20 α-olefin monomer. The α- olefin monomer is more preferably selected from the group consisting of ethylene, propylene-1, butene-1, hexene-1 and octene-1. Olefin homopolymers or polyolefins include, for example, polyethylene, polypropylene, and polybutene. Illustrative copolymers of two, and interpolymers of at least three, different monoolefins include ethylene/propylene, ethylene/butene, ethylene/hexene and ethylene/octene copolymers, ethylene/propylene/carbon monoxide polymers, ethylene/styrene interpolymers, and ethylene/vinyl acetate copolymers. The EAODM interpolymers of this invention may also be blended with conventional ethylene/propylene/diene monomer (EPDM) or EAODM interpolymers that have an ethylene content < 80 wt% . The preferred polyolefins for blending with interpolymers of this invention polyethylene (PE) , polypropylene (PP) and blends thereof. The term "PE" includes HDPE, low density polyethylene (LDPE) , linear low density polyethylene (LLDPE) , medium density polyethylene (MDPE) , and ultra low density polyethylene (ULDPE) . The interpolymers of this invention and blends thereof can be crosslinked or cured using conventional procedures and compounds .
Suitable peroxides for crosslinking or curing include a series of vulcanizing and polymerization agents that contain α, α' -bis (t-butylperoxy) - diisopropylbenzene and are available from Hercules, Inc. under the trade designation VU CUP™, a series of such agents that contain dicumyl peroxide and are available from Hercules, Inc. under the trade designation Di-cup™ as well as Lupersol™ peroxides made by Elf Atochem, North America and Trigonox™ organic peroxides made by Moury Chemical Company. The Lupersol™ peroxides include Lupersol™ 101 (2,5- dimethyl-2 , 5-di (t-butylperoxy) hexane) , Lupersol™130 (2 , 5-dimethyl-2, 5-di (t-butylperoxy) hexyne-3 ) and
Lupersol™575 (t-amyl peroxy-2-ethylhexonate) . Other suitable peroxides include 2 , 5-dimethyl-2 , 5-di- (t-butyl peroxy) exane, di-t-butylperoxide, 2 , 5-di (t-amyl peroxy) -2 , 5-dimethylhexane, 2 , 5-di- (t-butylperoxy) -2 , 5- diphenylhexane , bis (alpha-methylbenzyl) peroxide, benzoyl peroxide, t-butyl perbenzoate and bis(t- butylperoxy) -diisopropylbenzene.
The peroxide can be added by any conventional means known to skilled artisans. If processing oil is used in preparing polymer blends and other compositions that include an EAODM interpolymer of the invention, the peroxide may be injected during processing of the blend or composition as a solution or dispersion in the processing oil or another dispersing aid. The peroxide can also be fed into a processing apparatus at a point where the polymer blend or composition is in a melt state. Concentrations of peroxide in a solution or dispersion may vary over a wide range, but a 20 to 40 wt% concentration, based on solution or dispersion weight, provides acceptable results. The solution or dispersion can also be admixed with, and allowed to imbibe on, dry and dry blended polymer pellets. If the peroxide is a liquid, it may be used as is without first preparing a solution or dispersion in, for example, a processing oil. In other words, one can add a liquid peroxide to a high speed blender together with dry polymer pellets, subject the blender contents to mixing action for a short period of time and then allow the contents to rest until imbibing action is regarded as sufficiently complete. One may regard the absence of a separate, discernible liquid peroxide fraction as being sufficiently complete. On a small scale, mixing occurs in a Welex Papenmeier Type TGAHK20 blender (Papenmeier Corporation) for a period of 30-45 seconds, followed by a rest period of 30 minutes. A more preferred procedure involves introducing the peroxide as a solid into a compounding apparatus together with polymer pellets as the pellets enter a compounding apparatus such as at the throat of an extruder. An alternate preferred procedure includes a step of adding the peroxide to a polymer melt in a compounding apparatus such as a Haake, a Banbury mixer, a Farrel continuous mixer or a Buss kneader. One can also introduce a previously formed dry blend of a solid peroxide and polymer pellets to the apparatus. The peroxide is suitably present in an amount within a range of from 0.05 to 10 wt%, based upon total weight of polymer in the blend or composition. Low levels of peroxide may show no measurable gel content as measured by boiling xylene extraction, but will still evidence discernible rheology improvements relative to the same composition save for the peroxide. In other words, the amount of peroxide should be sufficient to effect at least partial crosslinking of the EAODM interpolymers of this invention. A peroxide content in excess of 10 wt% tends to yield materials that are too brittle for practical use.
For efficient peroxide crosslinking, a sample needs to be subjected to heat for a time sufficient to decompose the peroxide thus generating free radicals for crosslinking. Depending on the peroxide, crosslinking can be initiated a temperatures ranging from 70°C to 80°C for a low temperature peroxide to as high as 220°C to 230°C using a high temperature peroxide. The crosslinking time can vary from as little as a few minutes to as long as 30 minutes. One skilled in the art can determine the required time and temperature for peroxide crosslinking based on known half-life temperature data for different peroxides.
Sulfur and phenolates (alkylphenol formaldehyde resins) and silicon hydrides serve as functional alternatives to peroxides . Sulfur produces satisfactory results at levels of 1-8 wt%, based on total weight of polymer in the blend or composition. Phenolates such as 2 , 6-dihydroxymethyl alkylphenol also produce satisfactory results at levels of 1-15 wt%, based on total weight of polymer in the blend or composition. Silicon hydrides produce satisfactory results at levels of 1-10%, based on total weight of polymer in the blend or composition. As noted above, crosslinking may also occur via EB irradiation. One advantage of using EB irradiation is that, if desired, a crosslinked polymer system with at least partial crosslinking of the EAODM interpolymers of the present invention can be made without using peroxide or any other crosslinking additives. Suitable doses of EB irradiation range from 0.1 megarad (Mrad) to 30 Mrad, preferably from 0.1 Mrad to 10 Mrad, more preferably from 0.1 Mrad to 8 Mrad, and most preferably from 0.1 Mrad to < 5 Mrad. While one may use a dosage in excess of 30 Mrad, e.g. 70
Mrad, doing so simply increases cost without providing sufficient offsetting physical property improvements to justify the increased cost. The actual irradiation dose required depends upon several variables including the source and intensity of the irradiation, the polymer being crosslinked, the thickness of the material or article, and environmental and other factors . The preferred source of irradiation is a high energy beam from an electron accelerator. High energy beams give an adequate curing dosage and rates of processing as high as 1200 meters per minute. Various types of high power electron linear accelerators are commercially available. Since the radiation levels required to accomplish crosslinking in EAODMs of the present invention are relatively low, small power units, such as the Electrocurtain® Processor from Energy Sciences, Inc., Wilmington, Mass., provide sufficient radiation. As noted above, other sources of high energy radiation, such as gamma rays may also be used.
Crosslinking may additionally occur via UV irradiation. In this embodiment the interpolymer composition of this invention may, preferably, contain at least one photoinitiator agent. Suitable photoinitators include, but are not limited to, benzophenone, ortho- and Para-methoxybenzophenone, dimethylbenzophenone, dimethoxy- benzophenone, diphenoxybenzophenone, acetophenone, o-methoxy- acetophenone , acenaphthenequinone, methyl ethyl ketone, valerophenone, hexanophenone, (x- phenyl-butyrophenone, p-morpholinopropiophenone, dibenzosuberone, 4- morpholinobenzophenone, benzoin, benzoin methyl ether, 3-o morpholinodeoxybenzoin, p-diacetylbenzene, 4- aminobenzophenone, 4'- methoxyacetophenone, (x- tetralone, 9-acetylphenanthrene, 2-acetyl- phenanthrene, I O-thioxanthenone, 3-acetyl- phenanthrene, 3-acetylindole, 9-fluorenone, I - indanone, 1, 3 , 5-triacetylbenzene, thioxanthen-9-one, xanthene-9-one, 7-H- benzfde] anthracen-7-one, benzoin tetrahydrophyranyl ether, 4,4'- bis (dimethylamino) - benzophenone, F-acetonaphthone, 2 ' acetonaphthone, acetonaphthone and 2 , 3-butanedione, benz [alanthracene- 7,12-dione, 2,2- dimethoxy-2-phenylacetophenone, (x, (x- diethoxy-acetophenone, cw- dibutoxyacetophenone, anthraquinone, isopropylthioxanthone and the like. Polymeric initiators include poly(ethylene/carbon monoxide), oligo[2- hydroxy-2- methyl-1- [4- (1- methylvinyl)phenyllpropanone] , polymethy1vinyl ketone, and polyvinylaryl ketones . Use of a photoinitiator is preferable in combination UV irradiation because it generally provides faster and more efficient crosslinking.
Preferred photoinitiators that are commercially available include benzophenone, anthrone, xanthone, and others, the Irgacure™ series of photoinitiators from Ciba-Geigy Corp., including 2 , 2-dimethoxy-2- phenylacetophenone (Irgacure 65 1); 1 - hydroxycyclohexylphenyl ketone (Irgacure 184) and 2- methyl- 1- [4- (methylthio)phenyll-2-moropholino propan- I - one (Irgacure 907). The most preferred photoinitiators will have low migration from the formulated resin, as well as a low vapor pressure at extrusion temperatures and sufficient solubility in the polymer or polymer blends to yield good crosslinking efficiency. The vapor pressure and solubility, or polymer compatibility, of many familiar photoinitiators can be easily improved if the photoinitiator is derivatized. The derivatized photoinitiators include, for example, higher molecular weight derivatives of benzophenone, such as 4- phenylbenzophenone, 4- aflyloxybenzophenone, 4-dodecyloxybenzophenone and the like. The photoinitiator can be covalently bonded to the interpolymer of this invention or to a polymer diluent, as described herein below. The most preferred photoinitiators will, therefore, be substantially non- migratory from the polymeric material .
The radiation should be emitted from a source capable of emitting radiation of the wavelength of from 170 to 400 nanometers (nm) . The radiation dosage should be at least 0. 1 Joule per cm2 (J/ cm2) and preferably from 0.5 to 10 (J/ cm2) and most preferably from 0.5 to about 5 (J/ cm2) . The dosage required on a particular application will depend on the configuration of the layer in the film, the composition of the layer, the temperature of the film being irradiated and the particular wavelength used. The dosage required to cause crosslinking to occur for any particular set of conditions can be determined by the artisan.
European Patent Application 0 490 854 A2 teaches a continuous process for crosslinking polyethylene with UV light.
The EAODM interpolymers of this invention may be modified by or grafted with other monomers. Any unsaturated compound that is organic and contains at least one ethylenic unsaturation (e.g., at least one double bond) and at least one carbonyl group (--C=0)or is an unsaturated alkoxysilane, and that will graft to an EAODM interpolymer can be used. The grafted interpolymers can be blended with other natural or synthetic polymers in the same manner as ungrafted EAODM interpolymers .
Monomers that are suitable for grafting or modification include unsaturated carboxylic acids, as well as anhydrides, esters and salts, both metallic and nonmetallic, of such acids and unsaturated alkoxysilanes . The unsaturated carboxylic acid monomers preferably contain ethylenic unsaturation that is conjugated with a carbonyl group. These acids include, for example, maleic acid, fumaric acid, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, alpha-methyl crotonic acid, and cinnamic acid. The unsaturated alkoxysilanes include, for example, vinyltrimethoxysilane and vinyltriethoxysilane. The monomer is most preferably maleic anhydride.
The grafted EAODM interpolymers have a minimum unsaturated compound or grafted monomer content of > 0.01 wt %, and preferably > 0.05 wt %, based on grafted EAODM interpolymer weight. The unsaturated compound content can vary upward from the minimum according to convenience, but is typically ≤ 10 wt%, and is preferably < 5 wt%, more preferably < 2 wt% based on grafted EAODM interpolymer weight. The unsaturated compound can be grafted to the EAODM interpolymer by any known technique, such as those taught in U.S. Pat. No. 3,236,917 and U.S. Pat. No. 5,194,509, the relevant teachings of which are incorporated into and made a part of this application by reference. For example, in the '917 patent, the polymer is introduced into a two-roll mixer and mixed at a temperature of 60°C. The unsaturated organic compound is then added along with a free radical initiator, such as, benzoyl peroxide, and the components are mixed at 30°C until the grafting is complete. In the '509 patent, the procedure is similar except that the reaction temperature is higher, e.g., 210° to 300°C, and a free radical initiator is not used or is used at a reduced concentration. An alternative and preferred method of grafting is taught in U.S. Pat. No. 4,950,541, the relevant parts of which are incorporated into and made a part of this application by reference. The λ541 patent teaches, at column 4, lines 16 through 28, use of a twin-screw devolatilizing extruder as a mixing apparatus. When using such an apparatus, the EAODM interpolymer and the unsaturated compound are suitably mixed together and reacted within the extruder at temperatures above the EAODM interpolymer mpt and in the presence of a free radical initiator. The unsaturated compound is preferably injected into molten EAODM within an extruder zone that is maintained under pressure.
In another embodiment of this invention, the graft-modified EAODM interpolymer is dry blended or melt blended with another thermoplastic polymer, and then molded or extruded into a shaped article. Such other thermoplastic polymers include any polymer with which the grafted EAODM interpolymer is compatible, and include both olefin and non-olefin polymers and engineering thermoplastics, as well as grafted and ungrafted versions of such polymers. The amount of graft-modified EAODM interpolymer that is blended with one or more other polymers varies and depends upon many factors, including the nature of the other polymer (s), the intended end use of the blend, the presence or absence of additives and, if present, the nature of such additives . In those applications in which the grafted ethylene interpolymer is blended with other polyolefin polymers, e.g. a non-grafted ethylene interpolymer or a conventional polyolefin polymer (LLDPE, HDPE, PP) , the blend composition comprises ≤ 70 wt % graft-modified ethylene interpolymer (s) , preferably ≤ 50 wt%, and most preferably < 30 wt %, based on total weight of blended polymers . The presence of the graft-modified EAODM interpolymer in these blends, both for engineered materials and wire and cable compositions, provides impact and/or strength properties to the materials and compositions . In other embodiments, the graft-modified
EAODM interpolymer comprises from a relatively minor amount (e.g. 10 wt%) , up to 100 wt % of the finished article. In those applications in which paintability of a finished article is important, a graft-modified EAODM interpolymer content within a range of 10 to 50 wt %, based on the total weight of the finished article, provides satisfactory results relative to an otherwise unpaintable molded article, e.g. an article prepared from a polyolefin such as polyethylene, polypropylene, etc. A graft-modified EAODM interpolymer content of < 10 wt% provides little or no benefit in terms of improving polyolefin paintability. Conversely, while graft-modified EAODM contents of > 50 wt%, e.g. > 70 wt%, may be used, finished article properties such as flex modulus may be unacceptably low while others such as heat distortion may be too high relative to articles prepared without the graft- modified EAODM interpolymer.
The EAODM interpolymers of this invention, whether graft-modified or not and whether blended with other polymers or not, may be compounded with any one or more of materials conventionally added to polymers. These materials include, for example, process oils, plasticizers, specialty additives and pigments. These materials may be compounded with such EAODM interpolymers or blends containing the same either before or after EAODM interpolymer crosslinking occurs. Selection of such materials and addition of the same to EAODM interpolymers and compounds including such interpolymers lies well within a skilled artisan's competence .
Process oils are often used to reduce any one or more of viscosity, hardness, modulus and cost of a composition. The most common process oils have particular ASTM designations depending upon whether they are classified as paraffinic, naphthenic or aromatic oils. An artisan skilled in the processing of elastomers in general and EAODM compositions in particular will recognize which type of oil will be most beneficial. A useful amount of process oil lies within a range of from > 0 to 200 parts by weight, per 100 parts by weight of EAODM interpolymer.
A variety of specialty additives may be advantageously blended with interpolymers of this invention to prepare useful compositions of matter.
The specialty additives include antioxidants; surface tension modifiers; anti-block agents; lubricants; antimicrobial agents such as organometallics, isothtazolones, organosulfurs and mercaptans; antioxidants such as phenolics, secondary amines, phophites and thioesters; antistatic agents such as quaternary ammonium compounds, amines, and ethoxylated, propoxylated or glycerol compounds; fillers and reinforcing agents such as carbon black, glass, metal carbonates such as calcium carbonate, metal sulfates such as calcium sulfate, talc, clay or graphite fibers; hydrolytic stabilizers; lubricants such as fatty acids, fatty alcohols, esters, fatty amides, metallic stearates, paraffinic and microcrystalline waxes, silicones and orthophosphoric acid esters; mold release agents such as fine-particle or powdered solids, soaps, waxes, silicones, polyglycols and complex esters such as trimethylolpropane tristearate or pentaerythritol tetrastearate; pigments, dyes and colorants; plasticizers such as esters of dibasic acids (or their anhydrides) with monohydric alcohols such as o- phthalates, adipates and benzoates; heat stabilizers such as organotin mercaptides, an octyl ester of thioglycolic acid and a barium or cadmium carboxylate; ultraviolet light stabilizers used as a hindered amine, an o-hydroxy-phenylbenzotriazole, a 2-hydroxy,4- alkoxyenzophenone, a salicylate, a cynoacrylate, a nickel chelate and a benzylidene malonate and oxalanilide; and zeolites, molecular sieves and other known deodorizers . A preferred hindered phenolic antioxidant is Irganox ™ 1076 antioxidant, available from Ciba-Geigy Corp. Each of the above additives, if used, is present in an amount of from > 0 to < 45 wt%, based on total composition weight, desirably from 0.001 to 20 wt%, preferably from 0.01 to 15 wt% and more preferably from 0.1 to 10 wt%. While more than one specialty additive may be present, amounts of each additive are selected to yield a total additive content of < 90 wt%, based on total composition weight. The EOADMs of this invention or blends thereof with other polymers may be compounded with one or more other materials and additives and fabricated into a variety of shapes including, without limitation, extruded profiles, parts, sheets, belts, wire and cable insulation, foams, shrink tubing and films using any one of a number of conventional procedures for processing thermoplastic or thermoset elastomers. The EAODMs, blends and resulting compounds can also be formed, spun or drawn into films, fibers, multi-layer laminates or extruded sheets, coatings or thin layer co-extruded sheets, or compounded with one or more organic or inorganic substances, on any machine suitable for such purposes. Any of the above shapes may be multi-layered. The following examples illustrate but do not, either explicitly or by implication, limit the present invention. Unless otherwise stated, all parts (pbw) and percentages (wt%) are by weight, on a total weight basis. Examples (Ex.) of the present invention are identified by Arabic numerals and letters of the alphabet identify comparative examples (Co p. Ex.)
Ex. 1-4 and Comp. Ex. A-D
Polymer Preparation Examples 1-4, Interpolymers of this invention and Comparative Example A were prepared using a 3.8 liter (1) stirred reactor providing for continuous addition of reactants and continuous removal of polymer solution, devolatilization, and polymer recovery. The catalyst system was a (t-butylamido) - dimethyl (η5-2-methyl-s-indacen-l-yl) silanetitanium (II) 1, 3-pentadiene CGC, a tris (pentafluorophenyl) borane (FAB) co-catalyst and a modified methylalumoxane (MMAO) scavenging compound. Tables ID to 4 show physical properties for Examples 1-4 and Comparative Example A.
Ethylene (C2) , propylene (C3) , and hydrogen (H2) were combined into one stream before introducing the stream into a diluent mixture comprising a mixed alkane solvent (Isopar-E™, available from Exxon Chemicals Inc.) and polyene (ENB) to form a combined feed mixture . The combined feed mixture was continuously injected into a reactor. The catalyst (Cat) and a blend of the cocatalyst (Cocat) and scavenging compound (Scav) were combined into a single stream, which was continuously injected into the reactor.
Table IA shows flow rates for solvent, C2, C3, and ENB in pounds per hour (phr) . Table IB shows concentrations and flow of Cat, Cocat and Scav in parts per million (ppm) and pounds per hour (phr) , respectively. Table IB also shows Cocat/Cat and Scav/Cat ratios. Table IC shows hydrogen flow, in standard cubic centimeters per minute (seem) , amount of polymer produced in phr, Reactor Temperature (Temp) in °C, and Reactor Pressure in megapascals (MPa) .
A reactor exit stream was continuously introduced into a separator to continuously separate molten polymer from the solvent and unreacted C2, C3, H2 and ENB. The molten polymer was cooled in a water bath or pelletizer, the cooled polymer was strand chopped or pelletized and the resulting solid pellets were collected.
*Based only on C2 and C3 content
* Measured in accordance with ASTM D1646 (ML1+4 at 125°C)
Using EB irradiation, the (a) interpolymers of Ex 1-4 and (b) polymers of Comp. Ex. B-D were crosslinked. Comp. Ex. B is an elastomeric ethylene/octene copolymer (Engage® 8003 available from DuPont Dow Elastomers L.L.C.) with a density of 0.885 grams per cubic centimeter (g/cc) , a melt index (MI) or I2 of 1 decigram per minute (dg/min) , a GPC molecular weight (Mw) of 125,000, and a MWD of 2.0. Comp. Ex. C is a LLDPE ( an ethylene/octene copolymer available from The Dow Chemical Company as Dowlex 2045) with a density of 0.92 g/cc, a MI or I2 of 1 dg/min, a GPC molecular weight (M of 110,000, and a MWD of 4.0. Comp. Ex. D is an ethylene-vinyl acetate (EVA) copolymer (Elvax® 460 available from E. I. du Pont de Nemours and Company) with a density of 0.941 g/cc, a MI of 2.5 dg/min, a GPC molecular weight (MJ of 80,000, a MWD of 5, and a vinyl acetate content of 18 wt% . MI measurements employ ASTM D1238 at 190°C or a modified version thereof (for the EVA copolymers) . Two identical sets of plaques were prepared from each of Ex. 1-4 and Comp. Ex. B-D. The plaques were compression molded to a thickness of 0.125 inch (0.32 centimeter (cm)) using the following cycle: heat at 190°C for three minutes with no pressure; apply a pressure of 18,200 kg while maintaining the temperature at 190°C; water cool to ambient temperature (about 25°C) while maintaining the 18,200 kg pressure; and release the pressure. One set of seven plaques was used as a control (without irradiation) ; the other set of seven plaques were EB irradiated at a dosage of 2 Mrad. The data in Table 5 compare the irradiated and non- irradiated plaques .
Hot creep was measured as described in Insulated Cable Engineers Association Publication T-28- 562, Published 3/81, revised 1/83. The hot creep test involves hanging a weight on a dumbbell test specimen to yield a stress of 29 pounds per square inch (psi) (200 kilopascals (kPa) ) in an oven heated to 200°C. At low levels of crosslinking in the specimen, the specimen elongates up to 600% and then bottoms out in the oven. As used in Table 5 below, "Failed" means that the sample in question bottomed out in the oven. At higher levels of crosslinking, the specimen displays less elongation and provides a measurable percentage elongation. "Hot" creep measurements provide an indication of the degree of crosslinking as hot creep and degree of crosslinking are inversely related. In other words , a decrease in hot creep value equates to an increase in the degree of crosslinking. The insoluble gel fraction (gel content) was measured as described in ASTM D 2765 using hot xylene as the solvent.
- means not measured The data in Table 5 show that the EAODM interpolymers of Examples 1-4 have a higher cross- linking response to EB irradiation (i.e. more efficiently cross-linked as indicated by % gel) than the polymers of Comp. Ex. B and C. With one exception (Ex 2), the EAODM polymers provide acceptable hot creep performance.
A theoretical explanation of the differences between Ex 2 and Ex 4 builds upon a base established by the difference in crystallinity prior to crosslinking. The interpolymer of Ex. 2 has a crystallinity of 20.5% whereas the interpolymer of Ex. 4 has a crystallinity of 39.9%. As noted in the Radiation Technology Handbook, Richard Bradley, Marcel Dekker, Inc., 1984 at page 106, EB curing tends to occur in non-crystalline regions of a polymer. ENB , due to its large size relative to C2 and the α-olefin monomers, appears to reside in amorphous or non-crystalline regions of the EAODM polymers. As such, even with equal percentages of ENB, a more highly crystalline polymer (e.g. Ex. 4 relative to Ex. 2) should provide a greater concentration of ENB in its amorphous regions. This may, in turn, yield a higher potential for crosslinking. As noted above, an increase in crosslinking leads to a reduction in elongation in hot creep testing. In view of a relatively lower crosslinking potential, one means of improving the hot creep test results of the Ex. 2 interpolymer involves increasing the radiation dosage from 2 Mrad to a level of > 4 Mrad.
Four sample compositions, Ex. 5-8 , respectively, were prepared from the interpolymers of Ex.l to 4 by blending each EAODM interpolymer with 2 wt% Lupersol® 130 peroxide (2 , 5-Dimethyl-2 , 5 dibutylperoxy hexyne-3 available from Elf Atochem) using a 200 gram (g) Haake mixer. The blends were prepared at a temperature of 130° C by mixing for 4 minutes at a rotor speed of 20 revolutions per minute (rpm) . After preparing the four sample compositions, each composition was pressed into a 0.32 cm plaque for curing trials using a modified procedure. The modified procedure employed the following cycle: heat at 130°C for two minutes while applying a pressure or force of 18,200 kg; water cool to ambient temperature (about 25°C) over a period of three minutes while maintaining the 18,200 kg pressure; and release the pressure. A sample from each uncured plaque was saved for oscillating disk rheometer (ODR) testing in accordance with American Society for Testing and Materials (ASTM) test D-2084. The plaques were cured using the following cycle: heat at 180°C under an applied force of 18,200 kg for 20 minutes; cool to ambient temperature over a three minute period while maintaining the 18,200 kg applied force; and release the applied force. The percent gel analysis and hot creep elongation were determined (See Table 6) . See Table 7 for ODR data. Plaques prepared from the interpolymers of Ex. 1-4, but no peroxide, have less than 2% gel and fail the hot creep test.
Table 6 Plaque Properties
The results shown in Tables 6 and 7 confirm that EAODM polymers of this invention can be cross- linked using peroxides. The ODR data show that an increase in EAODM polymer ethylene content results in a higher delta (Δ) torque value. (See Table 1 for ethylene contents.) Skilled artisans recognize that an increase in Δ torque value corresponds to an increase in the degree of crosslinking. This allows one to use a lower level of peroxide to obtain a desired degree of crosslinking than that required for EAODM polymers with a lower ethylene content. Higher crosslinking can be obtained with less peroxide which is an expensive component, thus allowing the end user to obtain similar crosslink density at a lower cost. By way of contrast, conventional EAODM polymers prepared from the same monomers, but with an ethylene content of 80 wt% or less, should yield lower Δ torque values and require correspondingly greater amounts of peroxide to attain the same crosslink level.
Examples 9-10 and Comp. Ex, E
The sampled composition of Ex. 9 was prepared from a blend of 90 wt% of the Comp. Ex. C polymer and 10 wt% Ex. 1. The sample composition of Ex. 10 was prepared from a blend of 70 wt% of the Comp. Ex. C polymer and 30 wt% Ex. 1. 100 wt% of the Comp. Ex. C polymer was used as a control and designated as Comp Ex E . The blends were prepared by tumble dry blending polymer pellets, melt compounding the dry blended pellets in a Leistriz Micro 18 millimeter (mm) co- rotating twin screw extruder with Haake 9000 torque rheometer drive to provide an extruded rod. The extrusion conditions are shown in Table 8 below:
The extruded rod was cooled in a water bath and the cooled rod was pelletized. Plaques were prepared using the procedure described above in Ex. 1- 4. One plaque of each example was EB irradiated at a dosage of 1 Mrad and one plaque from each example was EB irradiated at a dosage 2 Mrad using a ten megavolt (MeV) EB unit. One plaque from each example free of irradiation exposure was saved for use as a control . The degree of crosslinking was used as in Examples 1-4
The results in Table 9 demonstrate that the addition of 10-30 wt% of an EAODM interpolymer representative of the present invention can boost the gel response (degree of crosslinking) to EB irradiation in LLDPE (Comp. Ex. E) . The gel levels for the compositions of Exs . 9 and 10 at a 1 Mrad dose and Ex 9 at a 2 Mrad dose fall within a 20-60 wt% gel content range preferred for free rise foam expansion. Gel levels of 30-40 wt% are more preferred. (Reference: Polymeric Foams , D. Klempner and K. Frish, ed. , Chapter 9, pp. 201-203, Hanser Publishers, 1991). An increase in gel response at a low EB dosage, such as 1 Mrad, should significantly increase the capacity of existing EB units. Skilled artisans can readily determine optimal levels of EAODM and radiation dosage for LLDPE and other polymers disclosed herein.
Example 11 and Comp. Ex. F-G
Comp. Ex. F, which contains 100 wt% propylene copolymer (Profax 8623, commercially available from Himont with a melt flow rate (ASTM D 1238) of 2, a density of 0.9 g/cc (ASTM D 792A-2) and a flexural modulus (ASTM D 790B) of 140,000 psi (965 MPa)), was used as a control. The compositions of Comp. Ex. G and Ex. 11 each contain 70 wt% of the Comp. Ex. F copolymer and 30 wt% of a second polymer (the copolymer of Comp. Ex. C. for Comp. Ex. G and the interpolymer of Ex. 1 for Ex. 11) . Test plaques were prepared using the procedure of Ex. 1-4. One set was retained as a control (no irradiation) and the remaining sets were exposed to respective EB irradiation dosages of 2, 5, and 10 Mrads . The gel content was determined using the procedure described in Ex. 1-4. Table 10 summarizes the gel test results.
The copolymer of Comp. Ex. F in Table 10 shows no gel response to e-beam irradiation. Polypropylenes are known to undergo chain scissioning rather than crosslinking under EB irradiation. (Reference: Radiation Technology Handbook, at pages 114-129). The composition of Comp. Ex. G exhibits some irradiation response, but at 5-10 Mrad of dosage. On the other hand, the sample composition of Ex. 11 exhibits an irradiation response at 2 Mrad dosage comparable to that of the Comp. Ex. G composition at 10 Mrad. Other EAODMs that represent the present invention, when combined with the polypropylene of Ex 11 or with other polymers disclosed herein, should yield similar results.
Example 12 and Comp. Example H Table 11 summarizes flexural modulus (ASTM D-
790) and tensile/elongation (ASTM D-638) properties for the interpolymers of Comp. Ex. A and Ex 3, and the compositions of Comp. Ex. H and Ex. 12. The sample compositions for Comp. Ex. H and Ex. 12, respectively, were prepared by blending 30 wt% of the Comp. Ex. A interpolymer and the Ex. 3 interpolymer with 70 wt% of the Comp. Ex. C copolymer using the apparatus and process of Ex. 5-8 save for increasing the time to 5 minutes, the temperature to 190° C and the rotor speed to 40 rpm. The interpolymers of Comp. Ex. A and Ex. 3, and the compositions of Comp. Ex. H and Ex. 12 were converted into test plaques using the procedure of Ex. 1-4 and the plaques were subjected to flexural modulus and tensile/elongation testing.
The data in Table 11 show that the interpolymers of Ex. 3 has better mechanical strength than the interpolymer Comp. Ex. A, as indicated by a higher flexural modulus and tensile properties. This superiority remains after blending with the copolymer of Comp. Ex. C as shown by comparing the properties for Comp. Ex. H with those for Ex. 12.
Example 13-14 and Comp. Ex. I-J
The interpolymers of each of Comp. Ex. A and Example 3 was blended with 2 wt%, based on polymer weight, peroxide (Lupersol® 130, a 2,5 Dimethyl-2 , 5-di- (t-butylperoxy) hexyne-3 available from Elf Atochem) to give, respectively, Comp. Ex. I and Ex. 13 using the apparatus and procedure of Ex 12 , save for reducing the temperature to 130° C and the rotor speed to 10 rpm.
In the same manner, blends for Ex. 14 and Comp. Ex. J were prepared from 70 wt% of the copolymer of Comp. Ex. C and, respectively, 30 wt% of the Ex. 3 interpolymer and the Comp. Ex. A interpolymer together with 2 wt% of the same peroxide, based on combined polymer weight. The blends were converted into test plaques and the plaques were exposed to curing conditions using the procedure of Ex. 5-8. Table 12 summarizes flexural modulus and tensile/elongation testing results.
The data in Table 12 show the peroxide cured interpolymer of Ex. 13 has superior mechanical properties as compared to that of Comp. Ex. I. The peroxide cured blend composition (Ex. 14) also has superior mechanical properties as compared to the peroxide cured blend composition of Comp. Ex. J. These superior physical properties are even more surprising considering that the interpolymer of Comp. Ex. A used in these blends has a much higher Mw (higher Mooney) than the EAODMs of this invention. These improved mechanical properties will allow the such EAODMs to be used in blends with other polymers disclosed herein where retention of mechanical properties is important. Examples of such improved blends include more stable cross-linked polyolefin foams, higher strength cross- linked wire & cable jackets, and stiffer and more rigid cross-linked articles. Example 15 and Comparative Example K
The interpolymer of Ex. 3 was blended with a polypropylene (PP) homopolymer (Profax™ PD- 191, available from Himont) in a 70/30 (PP/Ex 3) weight ratio to make the composition of Ex. 15 using the apparatus and procedure of Ex. 9 and 10. The extrudate was compression molded into two sets of test plaques using the procedure described above for irradiation tests . The PP homopolymer was compression molded alone for two sets of Comp. Ex. K test plaques. One set of test plaques was subjected to EB irradiation at a dosage of 2 Mrad. IZOD bars were cut from all test plaques and the bars were tested for notched IZOD impact strength (ASTM D-256 - Method A) at two different temperatures (23°C and 0°C) . Table 13 summarizes the IZOD test results in kilojoules per meter (kJ/m) .
These results clearly show that the interpolymers of the present invention improve IZOD impact strength of polypropylene both before and after irradiation. Similar results are expected with this and other EAODMs of this invention when blended with any of the other polymers disclosed herein. Ex. 16-18 and Comp . Ex. L-P
Three interpolymers (Comp. Exs . L, M and N) each having an ethylene content below 75 wt% were prepared using the method of Comp. Ex. A and Exs. 1-4. The composition and physical properties for the interpolymers of Comp. Ex. L-N are described in Tables 14 and 15.
The compositions of Ex. 16, 17 and 18 were prepared from blends of varying amounts of the interpolymer of Comp. Ex. N and the interpolymers of Exs. 1, 3 and 4, respectively. The composition of Comp. Ex. P was prepared from a blend of the interpolymers of Comp. Exs. M and N. The amounts of each polymer were selected such that the average wt % ethylene of the blend was about 70 wt %. The blends were prepared using a Haake mixer. The polymers were added to the mixer set at a temperature of about 120 °C . The rotor speed was 30 rpm. The polymers were melted and blended at these conditions for 10 minutes at which point the temperature of the mixer was reduced to about 100 °C and the rotor speed was increased to 60 rpm.
The compositions of Ex. 16-18 and Comp. Ex. P were prepared by adding Carbon Black and Oil to the mixer and allowing it to mix for about 3 minutes. Sulfur and other curatives were added to the mixer and allowed to mix for about 2 minutes. After a total of 15 minutes, the rotor was stopped and the uncured blends were removed from the mixer. A composition containing 100 wt% interpolymer of Comp. Ex. L and designated as Comp. Ex. 0 was prepared using the same apparatus and method. Table 16 summarizes the composition of blend Ex. 16-18 and Comp. Ex. O-P.
The cure (vulcanization) properties of Ex. 16-18 were determined on a rotorless cure meter (moving die rheometer - MDR) according to ASTM D-5289,at a temperature of 160 °C . The minimum torque (MJ and maximum torque (M , both in Newton-meters (N-M) , and time to reach 95 % of maximum torque (T95) values are shown in Table 17.
Test specimens for the retraction at low temperature test (TR) were prepared and tested according to ASTM D-1329. The test specimens were cut from vulcanized plaques prepared from each composition. Each molded plaque was vulcanized at 160 °C for a total time equal to T95 plus 3 minutes. The temperatures at which the test specimens retracted 50 % (TR50) are shown in Table 18.
The results in Tables 17 and 18 show the interpolymers of this invention can be vulcanized at approximately the same rate as the Comparative EPDM (Comp. Ex. 0) and comparative EPDM blend (Comp. Ex. P) with the added benefit of superior TR50 values. Surprisingly, the temperature of retraction data show that the addition of a crystalline EAODM polymer results in improved performance for the vulcanized blend. A lower temperature of retraction indicates a more elastic or more rubber like material at low temperature . The improved low temperature performance is unexpected since the retraction temperature should increase as the tendency to crystallize increases.
The interpolymers of Exs. 19-21 were prepared using the method of Exs. 1-4 but at a production rate ten times (10X) greater than that of Exs. 1-4 (i.e. the reactor was ten times larger and the flow rates were ten times greater) . Tables 19-22 show the composition and physical properties for Exs. 19-21.
*Based only on C, and C, content ,
* Measured in accordance with ASTM D1646 (MLlt4 at 252C)
Ex. 22-30 and Comp. Ex. Q-T The interpolymers of Ex. 1, 3, 19 and 20 were blended with various polymers and additives to yield the compositions of Exs. 22-30. The various polymers were blended with additives and, in some instances other polymers, to yield the compositions of Comp. Exs. Q, R, S and T. The compositions of Exs. 22-30 and Comp. Exs. Q-T are shown in Tables 23-25. The low density polyethylene (LDPE) , Petrothene NA 940000, was obtained from Equistar Corporation. This LDPE polymer has a melt flow rate of 0.25, a polymer density of 0.918 and a crystalline melt point of 104 °C. The natural rubber, SMR CV-60, was obtained from Akrochem Corporation and is characterized as a 60 Mooney, viscosity stabilized Standard Malaysian Rubber (SMR) . The styrene-butadiene rubbers (SBR) , Plioflex 1712 and Plioflex 1502, were obtained from Goodyear Tire and
Rubber Company. Plioflex 1712 is characterized as a 46 Mooney viscosity SBR polymer extended with about 37.5 parts per hundred (phr) aromatic process oil. The Plioflex 1502 is characterized as a 50 Mooney viscosity SBR polymer . The polybutadiene rubber was obtained from Aldrich Chemical. The additives were carbon black, oil, zinc oxide, stearic acid, and sulfur curatives consisting of Butyl Zimate or Methyl Zimate (a dimethyl dithiocarbonate available from RT Vanderbilt) , MBT, TMTD and sulfur.
The various polymers, interpolymers of Exs. 1, 3, 19 and 20, if any, carbon black, oil, zinc oxide and stearic acid were added to a Farrel BR Banbury mixer. The temperature of the Banbury was about 120 °C to 150 °C . The rotor speed was set to about 80 rpm. The mix was blended for about 5 minutes . The mix was removed from the Banbury and sheeted on a Reliable roll mill. The roll mill was set at a temperature of about 110 °C. The rotor speed was set to about 10 rpm. The sheet was cut into strips and added to the Farrel BR Banbury mixer. During this mixing step, the sulfur curatives were added at a Banbury temperature of about 100 °C to about 110 °C. The rotor speed was set to about 30 rpm. The. mix was blended for about 2 minutes. The mix was removed and sheeted on a Reliable roll mill. The roll mill was set at a temperature of about 100 °C to 110 °C. The rotor speed was set to about 10 rpm. The sheet prepared from each blend was allowed to cool and subsequently submitted for additional tests .
The vulcanization properties of the interpolymers of Ex. 22-30 and Comp. Ex. Q-T were determined on a rotorless cure meter (moving die rheometer - MDR) according to ASTM D-5289. These vulcanization properties were determined at a temperature of 160 °C. The minimum torque (MJ , maximum torque (MJ and time to reach 90 % of maximum torque (T90) values for each blend are shown in Table 26.
Test specimens for abrasion resistance were prepared and tested according to ISO 4649-1985 (E) . The test specimens were cut from vulcanized plaques prepared from each blend. Each molded plaque was vulcanized at 160 °C for a total time equal to T90 plus 5 minutes. The plaque size was 7.6 cm by 7.6 cm at a thickness of about 6.5 mm. The abrasion data are shown in Table 27 and are reported as volume loss relative to a standard. A lower value is considered to be indicative of higher resistance to abrasive wear.
Examples 22-30 demonstrate that the addition of crystalline EAODM of this invention to different rubber formulations (such as natural rubber, styrene- butadiene rubber and polybutadiene rubber) imparts improved abrasion resistance and performance when compared to those blends not containing these polymers and does so without affecting the vulcanization performance as shown in Table 26. Applications where abrasion resistance is needed and improved abasion resistance would be advantageous include pneumatic tires, footwear, and conveyor belts.
Ex 31-44 and Comp. Ex. U
Examples 31-44 demonstrate the utility of interpolymers of this invention in foam applications . Data have been obtained on different crosslinked formulations. Typical methods for crosslinking foam formulations containing EAODM polymers include peroxide, sulfur, vinylalkoxysilane, hydrosilation, phenolic, electron beam, gamma and ultraviolet radiation. The foam data demonstrate the utility and enhanced foaming capability of crystalline EAODM polymers especially when blended with other ethylene interpolymers including low density polyethylene (LDPE) , ethylene-vinyl acetate (EVA) , ethylene copolymers such as ethylene-octene and ethylene-butene, ethylene-styrene, LLDPE and HDPE polymers. These data also demonstrate the enhanced foaming capability of crystalline EAODM polymers when blended with polypropylene polymers including homopolymers and copolymers. Other types of foaming agents (e.g. carbonates) could be used giving rise to either closed or open cell foams.
The low density polyethylene (LDPE) in Ex. 40 was Petrothene NA 940000, obtained from Equistar
Corporation. The typical properties for this LDPE polymer are a melt flow rate of 0.25, a polymer density of 0.918 and a crystalline melt point of 104 °C. The ethylene-vinyl acetate copolymer in Ex. 39 was Elvax 460, obtained from E. I. du Pont de Nemours and
Company. The typical properties for this EVA polymer are a density of 0.941 g/cc, a melt flow rate of 2.5 dg/min, a GPC molecular weight (Mw) of 80,000 and molecular weight distribution of 5.0 and a vinyl acetate content of 18 wt %. The interpolymers of Ex. 19, 20, and 21 were blended as shown in Table 28 on a Farrel BR Banbury mixer. For Examples 31-33, foaming agent and activators were added to the Farrel BR Banbury mixer at a melt temperature of about 130 °C. For Examples 34 and 35, and Comp. Ex. U, polypropylene and foaming agent were added to the Farrel BR Banbury mixer at a melt temperature of about 175 °C. After about 5 minutes of mixing, each formulation was removed from the Banbury and sheeted on a Reliable roll mill. From these sheets, two compression molded test plaques were prepared. The plaque size was 12.7 cm by 12.7 cm at a thickness of about 0.3175 cm. One set of test plaques were electron beam irradiated at 2 Mrad while the other set of test plaques were electron beam irradiated at 5 Mrad. After irradiation, the plaques were tested for gel content using the Standard Test Method for Determination of Gel Content as described in ASTM D- 2765 test method. The gel content for each plaque after irradiation is shown in Table 29.
Bun foams were prepared from Examples 31-33, irradiated at both 2 Mrad and 5 Mrad. 5.1 cm by 5.1 cm test samples were cut from the compression molded, irradiated test plaques and placed in a mold cavity of the same size and thickness . The cavity mold was placed into a heated, hydraulic molding press set at a temperature of 165 °C with a molding pressure of 20,000 lbs. (9100 Kg) . The cavity mold was left in the press for about 10 minutes and the pressure then quickly released. The sample was removed from the press and allowed to freely expand. After expansion, the foam density of each sample was determined by weighing a known volume. The foam density data are shown in Table 30.
Table 30 shows the interpolymer blends of Ex. 31- 33 can be foamed after irradiation crosslinking and there is an optimum irradiation dosage depending on ethylene content and amount of gel content. For polymers of this invention, a low irradiation dosage is preferred in order to obtain optimum foam densities .
Hot air oven, free rise foams were prepared from Ex. 31-35 and Comp. Ex. U irradiated at 2 Mrad. Test samples, 2.54 cm by 2.54 cm in size, were cut from the compression molded, irradiated test plaques. For Ex. 31-33, the test samples were placed in a hot air oven at a temperature of 180 °C for about 10 minutes. For Ex. 34-35 and Comp. Ex. U, the test samples were placed in a hot air oven at a temperature of 220 °C for about 10 minutes. The foamed test samples were removed from the oven and the foam density of each sample was determined by weighing a known volume. The foam density data are shown in Table 31.
Table 31 shows hot air oven free rise foams can be prepared from interpolymers and interpolymer blends of this invention. The foam density data show blends containing interpolymers of this invention exhibit lower foam density. The foam density data for the polypropylene blends show the improved foaming of the blend samples containing the inventive interpolymers (Ex. 34 and 35) as compared to the polypropylene blend sample (Comp. Ex. U) . It would be expected that polymers of this invention could be blended with other ethylene polymers such as LDPE, EVA, LLDPE, EAODM, ethylene alpha-olefin copolymers and terpolymers , ethylene-styrene and HDPE and subsequently irradiated to give foamed articles having low foam densities.
The formulations shown in Table 32 were prepared using the combination of a Farrel BR Banbury mixer and a Haake Rheocord 9000 mixer. All of the formulation components except the peroxide were premixed using a Farrel BR Banbury mixer at a melt temperature of about 130 °C. After about 5 minutes of mixing, each blend was removed from the Banbury and sheeted on a Reliable roll mill . These sheets were then diced into irregular cubes of about 2 cm in size. For the peroxide addition, each premixed sample (as cubes) was added to a Haake Rheocord mixed and allowed to melt before the addition of the Di-Cup 40 KE a dicumyl peroxide. The conditions for blending on the Haake mixer were a melt temperature of 130 °C and a rotor speed of about 5 rpm. After about 5 minutes of melt blending, each sample was removed from the Haake and allowed to cool .
Each formulation sample was compression molded at a pre-molding temperature of 130 °C using a heated hydraulic press . The mold cavity used for this was about 10.2 cm by 10.2 cm with a thickness of 1.3 cm. After molding at 130 °C, the mold cavity containing the sample was then crosslinked at a temperature of 160 °C using a total pressure of about 20,000 lbs. The cavity mold containing the sample was left in the press for a time of about 20 minutes. After this time, the pressure was quickly released. The sample was removed from the press and allowed to freely expand. For each foamed sample, the % gel content and foam density values were determined as previously described. These data are shown in Table 33.
The data in Table 33 demonstrates foams can be prepared from examples of this invention using peroxide crosslinking. Optimum amounts of peroxide can be adjusted depending on the interpolymer added and desired foam density. The formulations shown in Table 34 were prepared using the combination of a Farrel BR Banbury mixer and a Haake Rheocord 9000 mixer. All of the formulation components except the sulfur curatives were premixed using a Farrel BR Banbury mixer at a melt temperature of about 130 °C. After about 5 minutes of mixing, each formulation was removed from the Banbury and sheeted on a Reliable roll mill. These sheets were then diced into irregular cubes of about 2 cm in size. For the addition of the sulfur curatives, each premixed sample (as cubes) was added to a Haake Rheocord mixed and allowed to melt before the addition of the sulfur curatives . The conditions for blending on the Haake mixer were a melt temperature of 130 °C and a rotor speed of about 5 rpm. After about 5 minutes of melt blending, each sample was removed from the Haake and allowed to cool.
Each blend sample was compression molded into a plaque at a pre-molding temperature of 130 °C using a heated hydraulic press. The plaque size was about 12.7 cm by 12.7 cm at a thickness of about 0.3175 mm. From each plaque, smaller test samples were cut. These test samples were 2.54 cm by 2.54 cm in size with a thickness of 0.3175 cm. These test samples were placed in a hot air oven at a temperature of 200 °C for about 5 minutes. The foamed test samples were removed from the oven and submitted for testing. For each foamed sample, the % gel content and foam density values were determined as previously described. Results are shown in Table 35.
Table 35 demonstrates that sulfur crosslinking of polymers of this invention can produce acceptable foamed articles . Optimum amounts of sulfur curatives can be adjusted depending on the interpolymer and desired foam density. Interpolymers of this invention can be blended with other ethylene polymers such as LDPE and EVA (other ethylene polymers would include LLDPE, ethylene alpha-olefin copolymers, ethylene- styrene and HDPE) , other sulfur curable natural or synthetic rubbers, and subsequently sulfur crosslinked to give foamed articles having low foam densities.
Ex. 45 47
An ethylene-butene- ethylidene norbornene terpolymer of this invention was prepared in a manner similar to Ex. 1-4. The composition and properties for the EAODM polymer are shown in Table 36.
The interpolymer of Ex. 45 was blended- with sulfur and phenolic curatives/accelerators in a Haake Rheocord 9000 mixer to make the formulations of Ex. 46 and 47. The formulation of Ex. 46 was prepared using the interpolymer of Ex. 45, sulfur curative and accelerators. The formulation of Ex.47 was prepared using the interpolymer of Ex. 45, phenolic curatives and accelerators . The conditions for blending on the Haake mixer were a melt temperature of 130 °C and a rotor speed of about 5 rpm. The polymer was added to the mixer and allowed to melt. After about 3 minutes, the sulfur or phenolic curatives and accelerators were added. After about 2 minutes of melt blending, the sample was removed from the mixer and allowed to cool . The sulfur and phenolic formulations are shown in Table 37.
The blends were tested for vulcanization properties using Standard Test Method for Rubber Property Vulcanization Using Rotorless Meter as described in ASTM D-5289 (moving die rheometer - MDR) . The blend of Ex. 46 with sulfur curative and accelerators was tested at a temperature of 160 °C. The blend of Ex. 47 with phenolic curatives and accelerators was tested at a temperature of 200 °C. The minimum torque (MJ , maximum torque (MJ and time to reach 95 % of maximum torque (T9J values are shown in Table 38.
The data in Table 38 show the EAODM of Ex. 45 can be vulcanized with sulfur and phenolic curative/accelerators. Other types of crosslinking could be used including peroxide, irradiation (E-beam, gamma, UV) , silane, and hydrosilation. Possible end- use applications for these polymers would be in polyolefin foams (footwear, automotive interior) , vulcanized rubber blends (tires, weatherstripping) , crosslinked polyolefin blends (films, fiber, tubing) , and thermoplastic vulcanizates (TPV's)
The interpolymer of Ex. 20 was vulcanized using hydrosilation curative and platinum catalyst. First, the interpolymer of Ex. 20 (100 pph) was added to a Haake Rheocord 9000 mixer and allowed to melt at a melt temperature of 130 °C. After about 3 minutes, the hydrosilation curative (3 pph silicon hydride Type 1107 Fluid from Dow Corning) and platinum catalyst (20 ppm of SIP 6831.0 from Gelest, Inc.) were added and allowed to mix at a rotor speed of about 5 rpm. After about 5 minutes of melt blending, sample was removed from the mixer and allowed to cool to give the vulcanized interpolymer of Ex. 48 and was tested for vulcanization properties using Standard Test Method for Rubber Property Vulcanization Using Rotorless Meter as described in ASTM D-5289 (moving die rheometer - MDR) . The composition of polymer blended with hydrosilation curative and catalyst was tested at a temperature of 190 °C. The minimum torque (MJ was 0.04 N-m, the maximum torque (MJ was 0.1 N-m., and time to reach 95 % of maximum torque (T9J was 16.50 min. These results that interpolymers of this invention can be successfully cured using hydrosilylation vulcanization.
Ex. 49 and Comp. Ex. V
The following comparative example and example compare the biaxial orientation of linear low density polyethylene (LLDPE) to a blend of LLDPE with interpolymers of this invention. The subsequent utility of both in shrink film applications also is compared . The interpolymer of Ex. 19 was blended with the LLDPE of Comp. Ex. C in a 10/90 weight ratio, respectively, to prepare the blend of Ex. 49. Blending was done in a 64mm 36/1 L/D (Length/Diameter) single screw extruder. The following conditions were used on the 64 mm extruder: Barrel Temperature Zones were Zone 1 = 82 °C, Zone 2 = 127 °C, Zones 3-5 = 190 °C with Screen Changer Temperature = 204 °C and Adapter and Die Temperature = 218 °C. The extruder speed was 31 rpm. Strands were extruded, water quenched, then chopped into pellets. These pelletized compounds were extruded into sheeting using a 50 mm 24/1 L/D single screw extruder. Extruder barrel temperature zones were Zone 1 = 216 °C, Zone 2 = 238 °C, Zone 3 = 249 °C, Adapter and Die Temperature = 218 °C. The extruder speed was 34 rpm at 19.5 amps. The Casting Roll Temperature was 39 °C, the die width was 30.5 cm., sheet thickness was 0.64mm, and sheet width was 52.4 cm
Sheets of the blends of Ex. 49 and the LLDPE of Comp. Ex. C were rolled onto cardboard cores. These sheets were then electron beam irradiated at 4.0 Mrad dosage at a line speed of 6.1 m/min to produce irradiated sheets of the blend of Ex. 49 and the LLDPE of Comp. Ex. V. The irradiated sheeting was then oriented in the machine direction (MDO) to a 5:1 draw ratio using a series of heated rollers with differential roll speed. The conditions for the MDO draw were a preheat temperature of 98.3 °C , slow draw rolls running at 2.4m/min. and 109 °C, fast draw rolls running at 12.3 m/min. and 109 °C, annealing roll at 12.3 m/min. and 36 °C, chill roll at 12.3 m/min and 19.4 °C. Sheet thickness was 0.13 mm.
The MDO drawn sheet was oriented in the transverse direction using a tender frame device heated via convection oven and equipped with a horizontal chain and flexible grip system for transverse direction orientation (TDO) . Conditions used for TDO stretching for Comp. Ex. V was a preheat temperature of 113 °C, a stretch temperature of 113 °C, and an annealing temperature of 96 °C . Conditions used for TDO stretching for the blend of Ex. 49 was a preheat temperature of
116 °C, a stretch temperature of 116 °C, and an annealing temperature of 99 °C . The films were cooled via circulating ambient air prior to windup. Film thickness was 0.025 mm. The films were tested for crosslinked gel in accordance with ASTM D-2765, Method A. The film of Ex. 49 had and average gel content of 25.41%. The film of Comp. Ex. V had an average gel content of 0.68%. These results show the large increase in crosslinking ability of blends containing polymers of this invention.
The tensile strength at break of the film of Ex. 49 and Comp. Ex. V was measured in the MDO and TDO, according to ASTM D-882. The results are shown in Table 39. The film of Ex. 49 exhibited higher tensile strength at break in both the MDO and TDO than Comp. Ex. V.
Shrink tension was measured in the MDO at 125 °C, according to ASTM D2838, Method A. The film of Ex. 49 had a MDO shrink tension of 1.73 Mpa and Comp. Ex. V had a MDO shrink tension of 1.13 Mpa. Thus, electron beam irradiated biaxially oriented films containing the inventive high crystalline interpolymers exhibit higher levels of crosslinking, tensile strength at break, and shrink tension, than films lacking the inventive interpolymers. These interpolymers of the invention can be used as blend components or alone to exhibit high gel response to electron beam irradiation for biaxially oriented shrink films.
Ex. 50-51 and Comp. Ex. W-X
The interpolymer of Ex. 20 was blended with a LDPE, LD 400.09 (available from Exxon Chemical Company), having a melt index of 2.8 dg/min and a density of 0.917 g/cc and a high density polyethylene (HDPE) , Sclair 59A (available from Nova Chemicals) , having a melt index of 0.7 dg/min, and a density of 0.962 g/cc. The blend with the LDPE yielded the composition designated Ex. 50 and the one with the HDPE yielded the composition designated Ex. 51. 100 wt% of the LDPE was designated Comp. Ex. W. 100 wt% of the HDPE was designated Comp. Ex. X. The blend compositions were prepared on a Werner Pfleiderer ZSK- 30 co-rotating twin screw extruder with a medium-high shear screw configurations . The blend compositions are shown in Table 40 and blend conditions are shown in Table 41.
The pelletized blends in Table 40, after being mixed and pelletized according to Table 41, were extrusion processed into sheeting using a 50 mm 24/1 L/D Killion single screw extruder fitted with a 15 cm wide sheet die. Conditions used to extrude these sheets is shown in Table 42.
One millimeter thick sheeting of Comp. Ex. W-X and the blends of Ex. 50-51 was produced and cooled on a Killion 25 cm wide three roll stack. The sheets were then irradiated via electron beam to 2 Mrad dosage . The irradiated sheets were tested for gel response as measured according to ASTM D2765, Method A. Results are shown in Table 43. The sheeting samples containing polymers of this invention exhibit much higher gel levels than Comp. Ex. W and X which contain no polymers of this invention.
The irradiated sheeting was cut into 20 cm x 10 cm strips . These strips were drawn in the machine direction in a United tensile testing machine equipped with an environmental chamber. The tensile testing machine was fitted with a multihead grip capable of gripping across the 10 cm width. Prior to drawing, the sample was allowed to preheat in the environmental chamber at the preset temperature for ten minutes. The preset environmental chamber temperature for each blend is shown in Table 44. Different chamber temperatures were used depending upon the type of polyethylene used. The chamber temperature was set at or near the melting point of the polyethylene. After the ten minute preheat time, the sheeting samples were drawn to a 2:1 draw ratio in the machine direction using a crosshead speed of 50 mm/min. Immediately after reaching a 2:1 draw ratio, the crosshead was stopped, the environmental chamber was opened, and the samples, still under tension, were cooled with air from pressure lines. The stretched sheeting samples were tested for shrink tension at 150 °C according to ASTM D2838, Method A. Table 45 shows the shrink tension results. The shrink tension was four to five times higher for examples of this invention (Ex. 50-51) than for Comp. Ex. W-X which contained no polymers of this invention. High crystalline EAODM can be used in blends with either LDPE, HDPE, or other polyethylenes to yield shrink articles such as shrink sleeves, shrink tubing, shrink lining, etc. with higher cross-link and shrink tension at equal orientation and electron beam dose levels .
Ex. 52 The interpolymer of Ex. 2 (85pph) was mixed on a two roll mill with 1 part 4-chlorobenzophenone and 15 parts hexanediol diacrylate to provide the formulation of Ex. 52. Slabs of 2 mm thickness were then pressed from the formulation. The slab was then exposed to an 80 W/cm 5 cm long UV lamp. The lamp was placed 10 cm from the slab and the exposure time was 4 minutes. After exposure, the crosslinked interpolymer of Ex.52 had a compression set (25% deflection) at 125 °C for 70 hrs . of 45%. These results clearly indicate that the highly crystalline EAODM based compounds of this invention can be crosslinked using ultraviolet light.
Ex. 53-56 and Comp. Ex. Y
The interpolymers of Ex. 2, 19, and 20 were grafted with maleic ahydride. 240 grams of each interpolymer were added to a Haake Mixer at a temperature of 200 °C . The rotor speed was set to 50 rpm. The polymer was allowed to melt for about 1 minute, followed by addition of 7.2 grams of maleic anhydride. This operation was conducted with the metal ram in the closed position. After about 5 minutes, the rotor was stopped and grafted interpolymer of Ex. 53-55 was removed from the Haake mixer. The amount of grafted maleic anhydride on each polymer was determined using infrared absorbance with the interpolymers of Ex. 53 having 0.35 wt%, Ex. 54 having 0.40 wt% , and Ex. 55 having 0.50 wt % maleic anhydride.
The interpolymers of Ex. 53 and Ex. 2 were blended with a polyamide polymer (Capron 8200 obtained from Allied Signal) . The polyamide polymer was pre-dried at 70 °C for 24 hours before using. The interpolymer of Ex. 53 and Ex. 2 were granulated in a K-Tron granulator to an average diameter of about 0.1875 inches before extruder blending. The blend was prepared on a 18 millimeter Haake co-rotating twin screw extruder having a 30:1 L/D ratio. The extruder speed was set at 50 rpm. The zone temperatures were profiled from 240 °C to 260 °C from the feed throat to the die. The melt temperature at the die was about 260 °C . The extruder was equipped with a two hole die, water bath, air knife and strand chopper. The molten polymer strands were cooled in the water bath and pelletized to an average pellet size of about 0.125 inches to give Comp. Ex. Y (80 wt% Capron 8200 and 20 wt% interpolymer of Ex. 2) and the interpolymer blend of Ex. 56 (80 wt% Capron 8200 and 20 wt% grafted interpolymer of Ex. 53) . The grafted interpolymer of Ex. 56 and Comp. Ex. Y were injection molded on an Arburg Injection Molding machine using a standard ASTM mold. IZOD test bars were molded at a standard thickness of 0.125 inches. The molding conditions were 260 °C melt temperature with an 80 °C mold temperature. The injection molded IZOD test bars were notched and tested for impact properties at room temperature according to ASTM conditions . The room temperature IZOD impact properties are shown in Table 46. The maleic anhydride grafted interpolymers of this invention can impact modify a polyamide polymer (Nylon 6) . When the interpolymers of this invention are not grafted with maleic anhydride, compatibility is poor and is reflected in the poor IZOD impact performance.
These examples compare the adhesion of low density polyethylene LDPE, HDPE and EAODM polymers of this invention to a styrene-butadiene rubber (SBR) substrate. The styrene-butadiene rubber (SBR), Plioflex 1502, was obtained from Goodyear Tire and Rubber Company. The Plioflex 1502 sample is characterized as a 50 Mooney viscosity styrene- butadiene rubber. The LDPE, Petrothene NA 940000, was obtained from Equistar Corporation. The typical properties for this LDPE polymer are a melt flow rate of 0.25, a polymer density of 0.918 and a crystalline melt point of 104 °C. The HDPE, Petrothene LR 73200, was obtained from Equistar Corporation. The typical properties for this HDPE polymer are a melt flow of 0.30, a polymer density of 0.955 and a crystalline melting point of 125 °C .
Compression molded plaques were prepared from each of the styrene-butadiene rubber, LDPE, HDPE and the interpolymers of Ex. 1, 3, 19, and 20. The plaques were 15.2 cm by 15.2cm having a thickness of about 3.17 mm. Adhesion test specimens, 2.54 cm (width) by 5.58cm (length) were cut from the plaques. The adhesion of the LDPE, HDPE, and the interpolymers of Ex. 1, 3, 19, and 20 to the SBR was evaluated by placing three test specimens of each polymer type in contact with the styrene-butadiene rubber. The polymer to styrene- butadiene rubber laminates were placed in an oven set at 150 °C . After one hour, the polymer to styrene- butadiene rubber laminates were removed from the oven, allowed to cool and manually checked for adhesion. The adhesion test was conducted using a manual 90 degree pull. The level of adhesion was determined by evidence of cohesive failure between the test polymers and the styrene-butadiene rubber substrate. The LDPE (Comp. Ex. Z) and HDPE (Comp. Ex. AA) laminates showed no adhesion whereas laminates of Ex. 58, 59, 60, and 61 (prepared from interpolymers of Ex. 1, 3, 19, and 20 respectively) exhibited adhesion. Furthermore, better adhesion was obtained as ethylene content of the crystalline EAODM polymer was increased. Adhesion of the crystalline EAODM polymers would be important in a number of different elastomer applications including tires e.g., as the low permeability inner liner), automotive weatherstrip (e.g., in the low COF (Coefficient of Friction) and wear resistant layer) , vulcanized rubber composites (e.g., in windshield wiper blades and engine motor mounts) and other laminated or coextruded articles.
Ex. 62 and Comp. Ex. AB
15 wt% of the interpolymer of Ex. 1 (15 wt%) was blended with 85 wt% Nordel IP 4770 EPDM which is available from DuPont Dow Elastomers) on a Farral ID Banbury to give blend Ex. 62. The typical properties for Nordel IP 4770 are an ethylene content of 70 wt% and a Mooney Viscosity ML (1+4) @ 125 °C of 70. 100 wt% Nordel IP 4770 was used as a control and designated Comp. Ex. AB. The blend of Ex. 62 and the polymer of Comp. Ex. AB each were extruded on a Davis- Standard extruder using a standard rubber screw (L/D is 20:1) at a screw speed of 17 RPM using a weatherstripping die. Barrel temperatures were 65.5 °C in zone 1, 71 °C in zone 2, 82°C in zone 3 and a die temperature of 37.8 °C. Extruder speed was 81.3 mm/sec Post die measurements were taken 15 cm from the die. End of line measurements were taken about 6 m from the die after the extruded material went through a room temperature air blowing chamber. The interpolymer blend of Ex. 62 had a post die height of 4.76 mm and an end of line height of 4.76 mm whereas Comp. Ex. AB had a post die height of 5.56 mm and an end of line height of 3.97 mm.
The addition of the interpolymer of Ex. 1 to Comp. Ex. AB improves both the tensile green strength (Table 47) and collapse resistance of the material, both of which are desirable improvement for profile extrusion applications such as hose and weatherstripping because the profiles need to maintain their die shape until the materials can be cured.
Ex. 63-72 and Comp. Ex. AC-AD
The blends in Table 48 were prepared using a "right side up mix procedure" (polymers and resins charged before fillers and oils) in a Reliable (B size, 1.7 L chamber volume), tangential-rotor internal mixer operating at 70 rpm. Ingredient weights were adjusted to provide 70% fill of the mixer volume. Amorphous EPDM interpolymers, Nordel IP 4570 and Nordel IP 4770 were used. Typical properties of Nordel IP 4570 are an ethylene content of 50 wt% and a Mooney Viscosity ML (1+4) at 125°C of 70. The amorphous interpolymers and crystalline interpolymers of the invention were charged to the mixer first, followed by the fillers (carbon black, calcium carbonate) and oil. The ram was lowered and the blends mixed to 88°C. At 88°C the ram was raised and the throat and ram were swept of loose fillers. The ram was lowered and the compounds discharged at 127°C and sheeted off on a 40.6 cm mill. The compounds were conditioned at 23 °C for 24 hours before addition of curatives. The compounds were charged to the mixer and mixed to 66°C. The ram was raised and swept, then the curatives added. The ram was lowered and the compounds were taken to 88°C and the throat and ram were swept . The ram was lowered and the compounds discharged at 104°C and sheeted off on a 40.6 cm mill.
The procedure for determining green strength of the blends in Table 48 was based upon ASTM D412 with the following modifications. The blends were pressed in a mold for 0.5 minute at 115°C. The mold was then cooled for 2 minutes before pressed sheets were removed. Pressed sheets were 1.91 - 21.6 mm thick. Test samples were cut from the sheet using a die 12.7 mm wide by 114.3 mm long. The samples were stressed at a rate of 127 mm/min. The stress at low strains (10 - 50 % strain) provides a good indication of "green- strength" as defined in extrusion processes.
The formulations of Ex. 63-72 (Table 49) show increasing hardness, 100% modulus, and green strength with increasing levels of interpolymers of the invention. These increases are greater than would be predicted by the blend's average ethylene level, as compared to results achieved with a pure 50% or 70% ethylene polymer. Consequently, higher hardness and modulus levels can be achieved at lower average ethylene levels . Lower ethylene levels provide improved low temperature sealing performance as measured by Temperature Retraction and Compression Set.
Ex. 73-76 and Comp. Ex. AE- AF
Some applications require compositions of high hardness (i.e. Shore D hardness greater than about 40) . Ex. 73-76 and Comp. Ex. AE-AF demonstrate that compositions of the invention exhibit properties which are advantageous for high hardness applications .
The interpolymer of Comp. Ex. AE is Nordel IP 4725P, an EPDM available from DuPont Dow Elastomers. The interpolymer of Comp. Ex. AF is Nordel IP 4520, another EPDM available from DuPont Dow Elastomers. A comparison of compositional and physical properties for the interpolymers of Ex. 1, 4 and 20 and Comp. Ex. AE and AF is shown in Table 50.
The interpolymers of Ex. 1, 4, and 20 were blended with Comp. Ex. AE and AF . The blends were prepared in 2 stages in a 1.2 liter internal mixer (Shaw - Intermix K0) . The filling coefficient was 64%. In a first stage, the masterbatch was prepared in a semi-conventional method in which all ingredients except sulfur, CaC03 and curatives were introduced into the mixer at 40 rpm, then sulfur and CaC03 were introduced 30 sec. before the Black Incorporation Time (BIT) and dumped 90 sec. after BIT or at 120 °C. The BIT is the time required to incorporate the filler during the mixing operation. However, BIT is more than just an indication of the mixing cycle time; it also indicates mixing efficiency and filler dispersion rate. On a plot of the mixing curve with time on the x-axis and power on the y-axis, the power consumption reaches a peak during the course of the mixing operation. The time at which the power occurs is the BIT.
In a second stage, the sulfur and curatives were added to the masterbatch in the internal mixer at 30rpm, then discharged after 2 minutes or at 11°C. Table 51 shows the composition of the blends and Table 52 shows the blend ratios for the various polymers used.
The results in Tables 53 and 54 show that incorporation of the interpolymers of Ex. 1, 4, or 20 into the interpolymers of Comp. Ex. AE and AF increases the tensile strength, modulus, tear strength, and hardness of the blends Ex. 73-76 over that of the Comp. Ex. interpolymers. Hardness levels above about a 40(?) Shore D permit such polymers to be used in high hardness automotive or building weather-stripping applications. For such applications, the mixing operation has to be fast (productivity) and efficient (good dispersion of the fillers is required so as to match surface aspect requirements). Surprisingly, blends of the inventive interpolymers with Comp. Ex. AE and AF provided fast carbon black incorporation (short BIT) and efficient mixing dispersion. In contrast, a pure inventive interpolymer (Ex. 1) had a BIT approximately twice that of the blended products . One would expect compression set and low temperature performance (TR) of Comp. Ex. AE-AF to suffer with the addition of high crystalline material. However, as Table 54 shows, both compression set and TR values are essentially unchanged when the interpolymer of Comp. Ex. AE is blended with the interpolymers of the invention. When a lower crystallinity EAODM is used (Comp. Ex. AF) , but with a higher loading of high crystalline material (Ex. 76) to obtain the same total crystallinity of the interpolymer blends of Ex. 74 and 75, the low temperature compression set and TR values actually improve considerably, even though the interpolymer blend of Ex. 76 has the highest weight percent of high crystalline material at 50 wt% . Additionally, roll mill processing improved considerably, as the compound provides better banding on the equipment. Total crystallinity of the blends of Ex. 74-76 remained constant at around 19%, which was comparable to the interpolymer of Ex.l at 20% crystallinity. These types of properties find applications in fields such as profiles, injection molding parts, hoses, and belts where such improvements are often advantageous .
Ex. 77 and Comp. Ex. AG-AH The interpolymer of Ex. 7 was injection molded into 0.5 inch (12.7 mm) by 0.25 inch (6.35 mm) bars for impact testing according to ASTM D 4020. These bars were exposed to 5 Mrads e-beam irradiation to produce irradiated interpolymer Ex. 77. Comp. Ex. AG is a commercially available
0.962 density, 17.5 melt index, high density polyethylene with Mn of 17,700 and Mw of 58,600 (A ATHON 6017 available from Equistar) . Comp. Ex. AG was injection molded under conditions similar to those used to mold the interpolymer of Ex. 7. Comp. Ex. AH is a commercially available 0.25 inch (6.35 mm) thick ultra-high molecular weight, HDPE sheet obtained from Laboratory Supply Corporation and was cut into 0.5 inch (12.7 mm) bars for testing. The irradiated interpolymer of Ex. 77, along with an interpolymer of Ex. 7 which was not irradiated, were tested for impact strength along with Comp. Ex. AG and AH according to ASTM D 4020, with the modification that a falling weight was used instead of a pendulum. The falling weight was 5.42 Kg and was dropped a distance of 73.66 cm. The impact energy was 39.2 Newtons .
Table 55 shows the impact strength of interpolymers of this invention are significantly better than the interpolymer of Comp. Ex. AG and AH. Table 55 also reveals that irradiation at 5 Mrads produces a vulcanized interpolymer having essentially equivalent impact performance to the nonirradiated interpolymer of Ex. 7.
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|International Classification||C08L23/06, C08F255/02, B32B27/32, C08F277/00, C08F255/08, C08L23/08, C08F279/00, C08J3/28, C08L23/00, C08F210/18, C08L21/00, C08J5/00, C08L23/16, C08F255/06, C08L23/04, C08L51/06, B32B27/28, C08F255/00|
|Cooperative Classification||C08L23/16, C08F255/02, C08L23/06, C08F277/00, C08F255/08, C08F279/00, C08L23/08, C08F210/18, C08L51/06, C08L2314/06, B32B27/32, C08L23/0815, C08L23/04, C08F255/00, C08L21/00|
|European Classification||C08L23/16, C08L23/08, C08L51/06, C08L23/04, B32B27/32, C08F277/00, C08F255/02, C08F279/00, C08F255/08, C08F255/00, C08F210/18|
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