WO2010090615A1

WO2010090615A1 - Aqueous dispersion of organoclay

Info

Publication number: WO2010090615A1
Application number: PCT/US2008/074390
Authority: WO
Inventors: Stephen Horton; Robert Graves
Original assignee: Polyone Corporation
Priority date: 2009-02-05
Filing date: 2009-02-05
Publication date: 2010-08-12

Abstract

An aqueous dispersion of organoclay is disclosed, using an organoclay selected based on the type of intercalant used to intercalate the clay platelets. The intercalant used has both amino end groups and carboxylic end groups. Excellently dispersed and pourable dispersions result.

Description

AQUEOUS DISPERSION OF ORGANOCLAY

CLAIM OF PRIORITY

[0001] This application claims priority from U.S. Provisional Patent

Application Serial Number 60/969,632 bearing Attorney Docket Number 12007017 and filed on September 2, 2007, which is incorporated by reference.

FIELD OF THE INVENTION

[0002] This invention concerns an aqueous dispersion of organoclay.

BACKGROUND OF THE INVENTION

[0003] The mixture of organoclays and polymers, commonly called nanocomposites, is highly desired because the organoclays can contribute stiffness and toughness properties to polymers for extruded or molded articles. Polyolefins for molded or extruded articles have been useful since the mid-20^th Century. Organoclays, smectite inorganic clays intercalated with organic ions, such as quaternary ammonium, have become useful in the last decade. [0004] Organoclays are expensive functional additives for polymers.

Nonetheless, several others have taught the use of organoclays as additives for polymers such as polyolefins and polyamides, among other resins. Representative examples of such prior work include U.S. Pat. No. 6,462,122 (Qian et al.) and U.S. Pat. No. 6,906,127 (Liang et al.) These prior works were invented by employees of Nanocor, Inc., a leader in the field of organoclays. [0005] Nanocor, Inc. offers a variety of organoclays for use with thermoset polymers and thermoplastic polymers, identifying compatibility with resins, presumably based on the intercalants used with the inorganic clay. Within the former category, among others, is Nanomer brand PGN organoclay, stated to be compatible with water based products for use in the coatings and primers market. Within the latter category, among others, is Nanomer brand I.24TL organoclay, stated to be compatible with polyamide 6 as an "in-reactor" grade, meaning that the organoclay is suitable for in situ during the polymerization of polyamide 6 from caprolactam. As stated in its Lit. N-609 Technical Data Sheet, Nanocor, Inc. reports that its Nanomer I.24TL nanoclay is a surface modified montmorillonite mineral specifically formulated for use in making nylon 6 nanocomposites via the polymerization method. Nanocor, Inc. reports that I.24TL clay will swell in epsilon-caprolactam and exfoliate completely during condensation polymerization. Nanocor, Inc. further reports that I.24TL contains a unique surface treatment which will participate in polymer chain propagation. The surface treatment with the clay leaves carboxylic end-groups available for reaction with amino groups after caprolactam ring opening. The result in an in- situ polymerization of polyamide 6 is a tethered or bound systems, in polymer molecules terminate at the clay surface.

SUMMARY OF THE INVENTION

[0006] What the art needs is an aqueous dispersion of organoclay for use in polymer coating systems.

[0007] Unexpectedly, the present invention has solved this problem by using an organoclay that is useful in the in-situ polymerization of polyamide nanocomposites.

[0008] Even more unexpectedly, other organoclays are not useful, including those recommended by Nanocor, Inc. for water based products, especially for the coatings and primers markets.

[0009] Thus, one aspect of this invention is an organoclay dispersion comprising: (a) aqueous based carrier and (b) organoclay containing a multi- charged spacing/coupling agent comprising a multi-onium ion compound having at least one ammonium ion and at least one oxonium ion. [00010] Another aspect of the present invention is any organoclay dispersion described above where the organoclay is formed using an intercalant having both amino end groups and carboxylic end groups. [00011] Another aspect of the present invention is a polymer coating system comprising the organoclay dispersion described above. [00012] Features and advantages of the invention will be explained below while discussing the embodiments.

EMBODIMENTS OF THE INVENTION [00013] Dispersion Carrier

[00014] Any aqueous-based carrier is a candidate for use in the present invention. There may be reasons why one of ordinary skill in the art of polymer coating systems would select pure or deionized water as the carrier or would select a mixture of water and a volatile organic solvent, depending on the coating to be formed on a substrate. Preferably, water is used. More preferably, deionized water is used. [00015] Organoclavs

[00016] Organoclay is obtained from inorganic clay from the phyllosilicate family, which have a unique morphology, featuring one dimension in the nanometer range. Montmorillonite clay is the most common member of the phyllosilicate clay family. The montmorillonite clay particle is often called a platelet, meaning a sheet-like structure where the dimensions in two directions far exceed the particle's thickness.

[00017] Any swellable layered silicate material that sufficiently ion- exchanges with an onium ion spacing agent is a candidate for the clay portion of the organoclay. Preferably, the ion exchange at the internal platelet faces can increase the interlayer spacing between adjacent phyllosilicate platelets at least about 30 nm, preferably at least about 0.5 nm. Useful swellable layered materials include phyllosilicates, such as smectite clay minerals, e.g., montmorillonite, particularly sodium montmorillonite; magnesium montmorillonite and/or calcium montmorillonite; nontronite; beidellite; volkonskoite; hectorite; saponite; sauconite; sobockite; stevensite; svinfordite; vermiculite; and the like. Other useful layered materials include micaceous minerals, such as illite and mixed layered illite/smectite minerals, such as rectorite, tarosovite, ledikite and admixtures of illites with the clay minerals named above.

[00018] Inorganic clay becomes commercially significant if intercalated with an organic intercalant to become an organoclay. An intercalate is a clay- chemical complex wherein the clay gallery spacing has increased, due to the process of surface modification by an intercalant. Under the proper conditions of temperature and shear, an intercalate is capable of exfoliating in a resin matrix, such as LLDPE or other polyethylenes, or in the circumstance of this invention, the aqueous-based carrier.

[00019] An intercalant is an organic or semi-organic chemical capable of entering the montmorillonite clay gallery and bonding to the surface. Exfoliation describes a dispersion of an organoclay (surface treated inorganic clay) in a matrix. In this invention, organoclay is exfoliated at least to some extent.

[00020] In exfoliated form, organoclay platelets have a flexible sheet- type structure which is remarkable for its very small size, especially the thickness of the sheet. The length and breadth of the particles range from 1.5 μm down to a few tenths of a micrometer. However, the thickness is astoundingly small, measuring only about a nanometer (a billionth of a meter). These dimensions result in extremely high average aspect ratios (200 - 500). Moreover, the miniscule size and thickness mean that a single gram contains over a million individual particles.

[00021] It has been found unexpectedly that only a certain type of intercalant is useful in making an intercalate or organoclay for the present invention. As the Examples will report below, the type of intercalant used to make the organoclay becomes significant to success in making organoclay dispersion of the present invention. [00022] The type of specific intercalants used by Nanocor, Inc. in its commercial products appear to be trade secrets. Nonetheless, by comparing its trade literature with its patent literature, it appears that the intercalant specifically useful for the present invention is a multi-charged spacing/coupling agent comprising a multi-onium ion compound having at least one ammonium ion and at least one oxonium ion. One organoclay commercially available from Nanocor, Inc. that utilizes a multi-charged spacing/coupling agent comprising a multi-onium ion compound having at least one ammonium ion and at least one oxonium ion is sold as Nanomer brand I.24TL organoclay, specifically identified to be suitable as an in-reactor grade for use with polyamide. [00023] As explained in the Lit. N-609 Technical Data Sheet, the surface treatment by the intercalant results in attachment to the clay by amino ends of the intercalant, leaving carboxylic acid end-groups available for reaction with amino groups of caprolactam after ring-opening. Thus, the intercalant has both amino ends and carboxylic acid ends.

[00024] As explained in U.S. Pat. No. 6,906,127 (Liang et al.) at Col. 8,

Line 52 to Col. 8, Line 67; Col. 9, Line 1 to Line 20; and Example 1, the text of which is specifically incorporated by reference herein, the preferred multi- charged spacing/coupling agent can be a multi-onium ion compound that include at least two primary, secondary, tertiary or quaternary ammonium, phosphonium, sulfonium, and/or oxonium ions according to Formula 2 shown at Col. 8, Line 60. As explained at Example 1, the intercalant used was protonated amino-dodecanoic acid.

[00025] Therefore, commercially available organoclays for the present invention are intercalates which employ intercalants having the following formula:

Iv₁ R₂

Z¹ - X⁺ - R - Y⁺ - Z² R₃ R₄ [00026] wherein X⁺ is an ammonium radical,

[00027] wherein Y⁺ is an oxonium radical,

[00028] wherein R is an alkylene, aralkylene or substituted alkylene charged atom spacing moiety, straight or branched, preferably ranging from C₃ to C₂₄ and mixtures of moieties thereof,

[00029] wherein R₁, R₂, R₃,and R₄ are moieties, same or different, selected from the group consisting of hydrogen, alkyl, aralkyl, benzyl, substituted benzyl, e.g., straight or branched chain alkyl-substituted and halogen-substituted; ethoxylated or propoxylated alkyl; ethoxylated or propoxylated benzyl, e.g., 1-10 moles of ethoxylation or 1-10 moles of propoxylation, and

[00030] wherein Z¹ and Z², same or different, may be non-existent, or may be any of the moieties described for R₁, R₂, R₃ or R₄ or one or more positively charged atoms or onium ion molecules.

[00031] More particularly, this invention benefits from commercially available organoclays that are taught to have intercalants with both amino end groups and carboxylic end groups.

[00032] Most preferably, this invention benefits from protonated amino- carboxylic acid intercalated phyllosilicate, especially montmorillonite, and even more especially when the carboxylic acid has from about 8 to about 16 carbon atoms and preferably about 10 to about 14 carbon atoms.

[00033] Optional Additives

[00034] The organoclay dispersion of the present invention can include conventional plastics additives in an amount that is sufficient to obtain a desired processing or performance property for the ultimate polymer coating system, but in a manner that does not disrupt the dispersion of the organoclay into the aqueous based carrier.

[00035] The amount should not be wasteful of the additive nor detrimental to the processing or performance of the compound. Those skilled in the art of liquid thermoplastics compounding, without undue experimentation but with reference to such treatises as Plastics Additives Database (2004) from Plastics Design Library (www.williamandrew.com), can select from many different types of additives for inclusion into the organoclay dispersion of the present invention.

[00036] Non-limiting examples of optional additives include adhesion promoters; biocides, if any, (antibacterials, fungicides, and mildewcides), defoaming agents; anti-static agents; bonding, blowing and foaming agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants, if any; impact modifiers; initiators; lubricants; micas; pigments, colorants and dyes; plasticizers; polymer resins in particulate form; processing aids; release agents; silanes, titanates and zirconates; slip and anti-blocking agents; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.

[00037] Table 1 shows ranges of acceptable, desirable, and preferred weight percents of the various ingredients for addition to a mixer, relative to the total weight of the organoclay dispersion, all being expressed as approximate values. Because the additives are optional, the low end of each range is zero.

[00038] Processing

[00039] The preparation of compounds of the present invention is uncomplicated. The compound of the present invention can be made in batch operations using a mixer, such as a Cowels high speed mixer operating at ambient temperature. Order of ingredients promotes dispersion, beginning with the aqueous based carrier, followed sequentially by any optional dispersing aid, organoclay, and any optional anti-foaming agent.

USEFULNESS OF THE INVENTION

[00040] An organoclay dispersion of the present invention can be used alone or mixed with other liquid-based polymer coating systems to make films, sheets, coated surfaces, molded articles, etc.

[00041] Further embodiments of the invention are described in the following Examples.

EXAMPLES

[00042] Table 2 shows the ingredients used for Comparative Examples A and B and Example 1. Table 3 shows the recipes used. Table 4 shows the processing conditions and results.

[00043] The type of intercalant used in the three commercially available organoclays from Nanocor, Inc. was dispositive of the success of dispersion. Only the protonated amino-carboxylic acid intercalated montmorillonite clay resulted in a well-dispersed and pourable dispersion.

[00044] What is utterly unexpected is that an organoclay designed for in- situ polymerization of polyamide (Nanomer I.24TL) would work, and a more conventional melt-compounding grade (Nanomer I.30T) or a grade designed for water-based products (Nanomer PGN) would not. The present invention benefits from that unpredictable and surprising result. [00045] The invention is not limited to the above embodiments. The claims follow.

Claims

What is claimed is:

1. An organoclay dispersion, comprising:

(a) aqueous based carrier and

(b) organoclay containing a multi-charged spacing/coupling agent comprising a multi-onium ion compound having at least one ammonium ion and at least one oxonium ion.

2. The dispersion of Claim 1, wherein the organoclay is formed using an intercalant having both amino end groups and carboxylic end groups.

3. The dispersion of Claim 1, wherein the organoclay is an intercalate which employ an intercalant having the formula:

R₁ R₂

Z¹ - X⁺ - R - Y⁺ - Z² R₃ R₄

wherein X⁺ is an ammonium radical, wherein Y⁺ is an oxonium radical, wherein R is an alkylene, aralkylene or substituted alkylene charged atom spacing moiety, straight or branched, preferably ranging from C₃ to C₂₄ and mixtures of moieties thereof, wherein R₁, R₂, R₃,and R₄ are moieties, same or different, selected from the group consisting of hydrogen, alkyl, aralkyl, benzyl, substituted benzyl, e.g., straight or branched chain alkyl-substituted and halogen-substituted; ethoxylated or propoxylated alkyl; ethoxylated or propoxylated benzyl, e.g., 1- 10 moles of ethoxylation or 1-10 moles of propoxylation, and wherein Z¹ and Z², same or different, may be non-existent, or may be any of the moieties described for R₁, R₂, R₃ or R₄ or one or more positively charged atoms or onium ion molecules.

4. The dispersion of any of Claims 1-3, wherein the organoclay is a protonated amino-carboxylic acid intercalated phyllosilicate.

5. The dispersion of Claim 4, wherein the carboxylic acid has from about 8 to about 16 carbon atoms.

6. The dispersion of Claim 4, wherein the carboxylic acid has from about 10 to about 12 carbon atoms.

7. The dispersion of Claim 4, wherein the organoclay is protonated amino-dodecanoic acid intercalated montmorillonite.

8. The dispersion of any of Claims 1-6, wherein the organoclay comprises a mineral selected from the group consisting of montmorillonite; nontronite; beidellite; volkonskoite; hectorite; saponite; sauconite; sobockite; stevensite; svinfordite; vermiculite; illite; rectorite; tarosovite; ledikite; and admixtures thereof.

9. The dispersion of any of the Claims above, wherein the aqueous- based carrier is water.

10. A polymer coating system comprising the organoclay dispersion of any of Claims 1-9.