Acrylic copolymer suitable for stain and water resistance

Abstract

An article is described comprising a substrate and a. surface layer. The surface layer comprises an acrylic copolymer comprising a) 20-80 wt.% of polymerized units of a (meth)acrylate monomer(s) comprising a C12-C22 hydrocarbon group; and b) 10-70 wt.% of polymerized units of (meth)acrylate monomer(s) comprising a terminal amine group; and optionally other (meth)acrylate monomer(s). Also described is an aqueous acrylic copolymer solution and a method of surface treating a substrate.

Description

[0001] PA102270W002

[0002] ACRYLIC COPOLYMER SUIT ABLE FOR STAIN AND WATER RESISTANCE

[0003] Summary

[0004] In one embodiment, an article is described comprising a substrate and a surface layer. The surface layer comprises an acrylic copolymer comprising a) 20-80 wt.% of polymerized units of a (meth)acrylate monomer(s) comprising a C12-C22 hydrocarbon group; b) 10-70 wt.% of polymerized units of (meth)acrylate monomer(s) comprising a terminal amine group; and optionally other (meth)acrylate monomer(s).

[0005] In some embodiments, a) comprises a (meth)acrylate monomer comprising a C12-C22 hydrocarbon group having a Tg ranging from -30 to 60°C. In some embodiments, a) comprises a methacrylate monomer comprising a C12-C22 hydrocarbon group.

[0006] In some embodiments, the (meih)aerylate monomer of b) has the general structure: wherein R}is hydrogen or methyl; and n range from 2-4; and

[0007] R5is independently hydrogen or a C1 -C4 alkyl group.

[0008] In some embodiments, the acrylic copolymer farther comprises at least 5, 10, 15, 20, 25, 30, or 35 wt.% of c) polymerized units of other (meth)acrylate monomer(s), such as aromatic monomers comprising a single aromatic ring. (e.g. benzyl). In some embodiments, b) and c) comprise methacrylate monomers.

[0009] In another embodiment, an aqueous acrylic copolymer solution is described comprises the acrylic copolymer described herein.

[0010] In another embodiment, a method of surface-treating a substrate is described comprising applying the aqueous acrylic copolymer solution to a surface of the substrate and allowing the solution to dry.

[0011] Brief Description of the Drawings

[0012] FIG. 1 is a graph of intrinsic viscosity of a solution polymerized acrylic copolymer at different concentrations of initiator.

[0013] Monomers Comprising Hydrocarbon Group

[0014] The acrylic copolymer comprises polymerized units of a (meth)acry1ate monomer comprising a (e.g., long-chain) C12-C22 hydrocarbon group. The C12-C22 hydrocarbon group is linear or branched and optionally comprises cyclic moieties. The (meth)acrylate monomer comprising a C12-C22 hydrocarbon group typically has the formula: wherein R5is hydrogen or methyl; and

[0015] Rzis a C12-C22 hydrocarbon group.

[0016] The hydrocarbon group is typically saturated and may be characterized as an alkyl group. In some embodiments, the hydrocarbon group comprises at least 18 (e.g. contiguous) carbon atoms. The carbon atoms of the (meth)acrylate group are not included in the number of contiguous carbon atoms. Representative examples include octadecyl (meth)acrylate (also known as stearyl (meth)acrylate), nonadecyl (meth)acrylate, (meth)eicosanyl acrylate, (meth)behenyl acrylate, and the like. Such monomers typically have a molecular weight no greater than 1000, 900, 800, 700, 600 or 500 g / mole.

[0017] Notably, the (e.g. alkyl) hydrocarbon group is a terminal alkyl group. Such alkyl group is also linear, rather than branched. Further, the monomer is a monofunctional ethylenically unsaturated monomer, having a single ethylenically unsaturated (e.g. (meth)acrylate) group. The ethylenically unsaturated group CH2=CR!- is typically bonded to the alkyl group through an ester linking group - (CO)O-.

[0018] In some embodiments, the acrylic copolymer comprises polymerized units of a (meth)acrylate monomer comprising a C12-C22 hydrocarbon group, wherein a homopolymer of such monomer has a Tg ranging from -30 to 60°C. Monomers comprising at least 18 (e.g. contiguous) carbon atoms are typically solid at room temperature and have a relatively low melting point (i.e. 22, 23, 24, or 25°C).

[0019] In some embodiments, R!is methyl. Notably methacrylate monomers typically have a higher glass transition temperature (Tg) than the acrylate monomer with the same long-chain hydrocarbon group. For example stearyl acrylate has a Tg of -58°C; whereas stearyl methacrylate has a Tg of 32°C. Another high Tg (meth)acrylate monomer having a hydrocarbon group with at least 18 carbon atoms is amidoethyl stearate (meth)acrylate, having a melting point of 92°C.

[0020] The acrylic copolymer typically comprises polymerized units of (meth)acryiate monomer(s) comprising a C12-C22 hydrocarbon group in an amount of at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65 or 70 wt.% based on the total weight of the acrylic copolymer (or the monomer mixture thereof.) In some embodiments, acrylic copolymer comprises polymerized units of (meth)acrylate monomer(s) comprising a C12-C22 hydrocarbon group in an amount no greater than 70, 65, 60, 55, 50, 45 or 40 wt.%. When the amount is too nigh, the aqueous acrylic copolymer composition may be a dispersion, or the solution / dispersion is hazy. In preferred embodiments, the aqueous acrylic copolymer composition is a transparent solution. Upon removal of the water, a clear thin protective layer is formed on the surface the composition is applied to.

[0021] In some embodiments, the (meth)acrylate monomer(s) comprising a terminal alkyl group with at least 18 (e.g. contiguous) carbon atoms may be purchased from a supplier and due to the purity being less than 100%, it may contain a small concentration of other (e.g. C5-C17 or C10-C17 or C12-C17) alkyl (meth)acrylate monomers. Monomers Comprising Terminal Amine Group

[0022] The acrylic copolymer comprises polymerized units of (meth)acrylate monomerfs) comprising a terminal amine group. Such monomer may have the general formula: wherein R? is hydrogen or methyl; and n is 2-4; and

[0023] R5is independently hydrogen or a Cl to C4 alkyl group.

[0024] In some embodiments, n is 2.

[0025] In some embodiments, both R'’ groups are methyl. In another embodiment, both R;' groups are ethyl. In another embodiment, one R;’ group is hydrogen and the other is (e.g., tertiary) butyl.

[0026] In one embodiment, the monomer having a terminal amine group is N,N-dimethylaminoethyl methacrylate DMAEMA, reported by Sigma as having a Tg of 19°C.

[0027] In another embodiment, the monomer is diethylaminoethyl methacrylate DMAE.MA, depicted as follows:

[0028] The acrylic copolymer typically comprises polymerized units of (meth)acrylate monomei(s) comprising a terminal amine group in an amount of at least 5, 6, 7, 8, 9, or 10 wt.% based on the total weight of the acrylic copolymer (or the monomer mixture thereof.) In some embodiments, the acrylic copolymer comprises polymerized units of (meth)acrylate monomer(s) comprising a terminal amine group in an amount of at least 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 wt.% based on the total weight of the acrylic copolymer (or the monomer mixture thereof.) In some embodiments, the acrylic copolymer comprises polymerized units of (meth)acrylate monomer(s) comprising a terminal amine group in an amount no greater than 60. 55, 50, 45, 40, or 35 wt.%. When the amount is too high, the amount of polymerized units of (meth)acrylate monomers) comprising a C12-C22 hydrocarbon group is too low, resulting in the acrylic copolymer not exhibiting the desired properties of stain resistance, water resistance, sufficiently high state water contact angles, or a combination of such properties. When the amount is too low, a hazy liquid rather than a transparent solution is formed.

[0029] As demonstrated by the forthcoming examples, when (meth)aeryiamide monomers such as N.hfo dimefhylacxylamtde (DMAA) and N-[3-(dimethylamino)propyl]methacrylainide (DMAPMA), were used in place of (meth)acrylate monomer(s) comprising a terminal amine group, solid gels rather than aqueous copolymer solutions were formed. However, it is surmised that smaller concentration (e.g., less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5 or 0.1 wt.%) of (meth)acrylamide monomers may be suitable in combination with monomers comprising a terminal amine.

[0030] Optional Monomers

[0031] The acrylic copolymer may optionally comprise polymerized units of other (meth)acrylate monomeifs), i.e. monomers that do not comprise a C12-C22 hydrocarbon group or a terminal amine group.

[0032] Examples of other monomers include (meth)acrylate monomer(s) include a hydrocarbon group comprising less than 12 carbon atoms. The C12-C22 hydrocarbon group is linear or branched and optionally comprises cyclic moieiies. Illustrative monomers include for example methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, octyl(meth)acrylate, nonyl(meth)acrylate, isoboniyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0033] In some embodiments, the acrylic copolymer may comprise polymerized units of aromatic (meth)acrylate monomer(s), i.e., monomer comprising an aromatic group. The aromatic group may comprise a single aromatic ring, such as in the case of benzyd (meth)acrylate. Benzyl methacrylate, reported to have a Tg of 54°C.

[0034] In some embodiments, the optional monomer(s) are methacrylate monomers.

[0035] Notably, ODMA, benzyl methacrylate and the monomer comprising a terminal amine described above are considered to be hydrophobic monomers. Thus, in typical embodiments, at least 90, 95, 96. 97, 98, or 99 wt.% of the total polymerized units of the acrylic copolymer are polymerized hydrophobic units. The acrylic copolymer typically comprises little or no polymerized units of (meth)acrylate or (rneth)acrylamide monomers having a hydrophilic group. Common hydrophilic groups include for example Cl -C4 alkoxy groups and C2-C6 oxyalkylene group suc h as polyalkylene glycol mono(meth)acrylate, polyalkylene glycol di(meth) acrylate, and / or polyalkylene glycol mono(meth)acrylamide. The amount (meth)acryhc monomers having a hydrophilic group is typically no greater than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 wt.%. The acrylic copolymer may also lack monomer comprising an ion-donating groups such monomers having a carboxyl, sulfonic acid, or phosphoric acid group. Thus, the (meih)acrylate monomer comprising the terminal amine may be the sole polar monomer of the acrylic copolymer.

[0036] In typical embodiments, the acrylic copolymer is prepared by free radical solution polymerization in an organic solvent. Suitable organic solvents include acetone, alcohols such as isopropanol and 3- methoxy-3-methyl-l-butanol; glycols such as propylene glycol methyl ether, dipropylene glycol methyl ether, and Dowanoi™ glycol ethers (PM, PnP, and PnB).

[0037] A free-radical initiator is utilized in the solution polymerization. Suitable free radical initiators include for example Vazo™ 67 (an oil-soluble 2,2 :’-azobis(methylbutyronitrile), polymerizations of large molecular weight polymers), isooctyl thioglycolate CAS number 25103- 09-7 (1OTG) j, and mercapto ethanol. The amount of free-radical initiator is typically at least 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7. In some embodiments, the amount of free-radical initiator is no greater than 2, 1.5, or 1 wt.%. With reference to FIG. 1, as the concentration of initiator increase, the intrinsic viscosity can decrease. At preferred concentrations the intrinsic viscosity is relatively flat. The optimal concentration of each initiator or combination of initiators can be determined experimentally.

[0038] After the copolymer is formed via solution polymerization, the amine group of the amine containing monomer is neutralized with acid, combined with water, followed by / removing the organic solvent. Acetic acid is a preferred acid for neutralization. The amount of acid can depend on the amount of amine containing monomer. The weight ratio of amine containing monomer to (acetic)acid is typically at least 2.4: 1, 2.5:1., or 2.6:1. Typically, the minimum amount of acid is utilized, such that the solution has a pH of 6-7. The resulting solution is transparent and comprises about 20-30 wt.% solids of acrylic copolymer.

[0039] In some embodiments, the copolymer has the formula:

[0040] CH3COO wherein x, y, and z are the number of repeat units corresponding to the wt.% of the polymerized units described above. In some embodiments, z is zero.

[0041] The molecular weight can be calculated from the intrinsic viscosity (i.e., IV) using the Mark -Chrysrian equation:

[0042] [IV] = KMawherein M is molecular weight. The values of the Mark-Houwink parameters, a and K, depend on the particular polymer-solvent system. Such values can be determined experimentally. For most flexible polymers, a is greater than 0.5 and less than 0.8 . For semi-flexible polymers a is greater than 0.8 but less than 2 or 1.5.

[0043] With reference to FIG. 1, the intrinsic viscosity can be at least 0.2, 0.3, or 0.4. In typical embodiments, the intrinsic viscosity is no greater than 0.8, 0.7, 0.6, 0.5, or 0.4.

[0044] In some embodiments, the acrylic copolymer may have a weight average molecular weight of at l e as t 50 , 00 ; 60 , 000 ; 70 , 000 ; 80 , 000 , or 85 , 000 g / mo l e . T h e molecular weight of the MMA copolymer may range up to 100,000; 150,000; 200,000; 250,000; 300,000; 350,000; 400,000; 450,000, or 500,000 g / mole. Weight average molecular weights of the acrylic polymer can be measured, for example, by gel penneation chromatography (i.e., size exclusion chromatography (SEC). Typical methods of surface-treating a substrate comprise applying the aqueous acrylic copolymer solation to a surface of the substrate and allowing the solution to dry. The composition is typically dilute, comprising at least 1, 5, 10, 15, 20, or 25 wt.% of the acrylic copolymer. However, the composition may optionally be more concentrated, comprising at least 50, 60, 70 wt.% or greater of the acrylic copolymer.

[0045] The aqueous composition may be applied to the substrate with any suitable method such as immersion coating, spray coating, foam coating, flood coating or applied with a brush or roller.

[0046] After drying, the amount of acrylic copolymer on the surface of the substrate is typically at least 1, 2, 3, 4, or 5 microns. In some embodiments, the coating typically has a thickness of no greater than 75, 50, 25, or 10 microns.

[0047] The exemplified compositions are especially useful for wood and stone. Wood is a hard, fibrous material with a natural grain pattern. Wood is a natural material that comes from trees. It is primarily composed of cellulose fibers held together by lignm. Paper is a man-made material produced from wood pulp or other sources of fiber like cotton or recycled paper. The fibers in paper are typically shorter and more processed than those in wood. Stone mean a rock, a piece of rock (such as granite, or marble, limestone, or a combination thereof), or composite material such as quartz composites, cement, ceramic, brick, plaster, and grout.

[0048] How'ever, the composition may' be useful for other substrates. In some embodiments, the substrate is a woven or non-woven substrate comprising natural fibers (e.g. cotton, hemp, wool and silk); and / or synthetic fibers. The synthetic fibers may' comprise organic polymers such as polyamide, polyester, polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride and polypropylene; as well as semi-synthetic fibers such as rayon and acetate. Inorganic fibers include for example glass fibers, carbon fibers and ceramic fibers. The substrate may comprise a mixture of fibers. Illustrative articles include textiles, a filters (e.g. electrostatic filters), protective masks, and paper.

[0049] Other substrates include organic (e.g. thermoplastic) films and leather as well as fuel cell components (e.g. gaseous diffusion electrode and a gaseous diffusion support). Advantageously the aqueous composition and acrylic copolymer thereof provide stain resistance and water resistance in the absence of comprising silicone or fluorine. Notably, the composition may- have a stain rating of 2, 3, 4 or 5 (1 = severe staining, 5 = no staining) when tested with expresso, tea, red wine, olive oil, or mineral oil.

[0050] The static water contact angle of transparent polydimethylsiloxane based protective coatings typically range from 130 to 137 degrees. Higher molecular weight polydimethylsiloxane based protective coatings can have static water contact angles up to 146 degrees, yet can be hazy rather than transparent. The acrylic copolymer described herein have static water contact angles comparable to polydimethylsiloxane based protective coatings. The static water contact angle is typically at least 125, 126, 127, 128, 129, or 130 degrees. In some embodiments, the static water contact angle is at least 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149 or 150 degrees, as well as any range of such static water contact angles. A continuous film of the copolymer typically has higher values than when applied to the surface of a porous substrate.

[0051] The invention is illustrated by the following non-limiting examples:

[0052] Materials of Examples:

[0053] Stearylmethacrylate (ODMA) available from BASF and Miw’on.

[0054] Benzylmethacrylate (BzMA) available from Evonik, Miwon, and European Chemical Marketing (ECEM).

[0055] Dimethylaminoethyl methacrylate (DMAEMA) available from Sigma-Aldrich and TCI. Diethylaminoethyl methacrylate (DMAEMA) available from Sigma-Aldrich and TCI N,N'-dimethylacrylamide (DMAM) available from ECEM.

[0056] N-[3-(dimethylamino)propyl)methacrylamide (DMAPMA) available from ECEM.

[0057] Vazo™ 67 an oil-soluble 2,2’-azobis(methylbutyronitrile) (AMBN) initiator from free radical polymerizations available from Chemours.

[0058] Synthesis Examples:

[0059] Example 1:

[0060] In a 5-liter 3 necked RB flask, equipped with cooler, stirrer, temperature control and nitrogen atmosphere the following products were added: 300g (33 wt.% of copolymer) ODMA, 300g (33 wt.%) BzMA, 300g (33 wt.%) DMAEMA, 600g acetone and 9g V-67 initiator. The reactor was purged with nitrogen and heated to reflux temperature. The products were reacted overnight, initial reflux temperature was 65°C. After the reaction, 114g acetic acid and 2700g water was added and the acetone stripped at 65°C under reduced pressure. When all the acetone was shipped, a clear slightly yellowish solution with about 30 wt.% solids (900 g total monomer / 2814 g of water and acid) was obtained. The final product contained less than 0,1% of each of the monomers. Other examples were prepared la the same way as Example 1 using 60 g of acetone. 180 g of water. 0.6 grams of V-67 initiator, arid the amounts of components as described in the following tables. The wt.% of the monomers based on the total monomer mixture / polymerized copolymer reported is parenthesis and the wt. ratio of amine containing monomer to acetic acid.

[0061] Table 1 -Ex, 1-10, Cl and C2

[0062]

[0063] Evaluation of stain resistance:

[0064] To the surface treated stone surfaces, drops of staining solutions were applied. 3 different stone types were used: marble, granite, and limestone. As staining solutions, express© coffee with sugar and milk, lemon thee, red wine, olive oil and mineral oil was used. 3 drops of the staining solutions were put on the surface, and left on the stone surface for 4 hours. The surfaces of the stones were cleaned after 4 hours.

[0065] First the non-penetrated and non-dried stains were removed with a dry paper towel, and in a second stage the surface was scrubbed with a wet sponge. The cleaned surfaces were then left to dry overnight, and then the intensity of the residual stains was rated.

[0066] Table 3 A - Staining Test Results

[0067] Table 3B ■■■ Staining Test Results

[0068] Table 3C - Staining Test Results

[0069] Rating 1 -- Severe Stain; Rating 5 - No visible stain. Product application:

[0070] The polymer solutions made above were diluted to 10% polymer solids in water. These solutions were applied with a paint brush on the surface of HDF (high-density fiberboard). The HDF surface was coated with the polymer solution, and then the impregnated HDF was left to dry at room temperature for minimum 48 hrs.

[0071] Evaluation of water and soap resistance:

[0072] To evaluate the effectiveness of the polymer to render the impregnated MDF surface resistant to swelling by contact with water, a paper towel was put on the surface of the MDF, the paper towel was then soaked with water and kept wet for 8 hours. After 8 hrs. the wet paper towel was allowed to dry on the HDF surface, and after 24 hrs. the surface was checked for swelling. The same test was repeated, but instead of water a detergent solution was used (1% Dreft in water)

[0073] Table 3D - Water Resistance

[0074] Rating I - Severe irreversible swelling; Rating 5 - No swelling

[0075] Examples 1-12 were also evaluated with other stain resistance tests and found to have good staining resistance and water solubility when applied to stone and wood surfaces.

[0076] Other examples were prepared in the same way as Example 1 using 100 g of acetone, and 1 .58 grams of V-67 initiator, and the amounts of components as described in the following table.

[0077] Intrinsic viscosity (i.e., IV) - was measured at 25°C with a Cannon-Fenske viscometer of SI analytics, type 520 03, series number 108 85 30.

[0078] Static Contact Angles - were measured with a Kruss DSA100S drop size analyzer. A (74 x 5.25 mm) piece of printing paper was soaked in a 0.55 % solids in EtOAc solutions (that were used for the

[0079] IV measurements) and allowed to air dry overnight horizontally. The Young- Laplace contact angles were determined with 5 pl drops of distilled water at the upper side of the dried papers The contact angles at the bottomside is about 6 to 10 degrees higher than the upper side. Table 4 ~ Examples 14-26, C5, and 06

[0080] FIG. 1 depicts the intrinsic viscosity of other examples that were prepared in the same way as Example 1 with ODMA (33 wt.%), (33 wt.%) ot'BzMA, and DMAEMA (33.3 wt.%) and different concentrations of Vazo 67 initiator. This same composition was prepared 5 times with 0.7 wt.% Vazo 67. The intrinsic viscosity was consistent, ranging from 0.42 to 0.44. The static water contact angle was also consistent; ranging from 127.25 to 132.73.

Claims

What is claimed is:

1. An article comprising a substrate and a surface layer comprising an acrylic copolymer comprising: a) 20-80 wt.% of polymerized units of a (meth)acrylate monomers) comprising a C12-C22 hydrocarbon group: and b) 10-70 wt.% of polymerized units of (meth)acrylate monomers) comprising a terminal amine group; c) optionally other (meth)acrylate monomeris).

2. The article of claim I wherein a) comprises a (meth)acrylate monomer comprising a C12-C22 hydrocarbon group wherein a homopolymer thereof has a Tg ranging from -30 to 60°C.

3. The article of claims 1-2 wherein a) comprises a methacrylate monomer comprising a C12-C22 hydrocarbon group.

4. The article of claims 1-3 wherein the C I 2-C22 hydrocarbon group is linear or branched and optionally comprises cyclic moieties.

5. The article of claims 1 -4 wherein b) comprises a (meth)acrylate monomer having the general structure:Ci L (CR!)C( =O)O(CH2)nN(R3)2wherein R? is hydrogen or methyl; and n range from 2-4; andR~' is independently hydrogen or a Cl to C4 alkyl group.

6. The article of claims 1-5 wherein c) comprises at least 5, 10, 15, 20, 25, 30, or 35 wt.% of polymerized units of (methjacrylate monomer(s) comprising an aromatic group.

7. The article of claims 1 -6 the aromatic group is a single aromatic ring.

8. The article of claims 1-7 wherein b) and c) comprise methacrylate monomers.

9. The article of claims 1 -8 wherein the acrylic copolymer improves the water resistance and / or stain resistance.

10. The article of claims 1-8 wherein the substrate comprises wood or stone.1 1. An aqueous acrylic copolymer solution, wherein the copolymer comprises:a) 20-80 wt.% of polymerized units of a (meth)acrylote monomer(s) comprising a C12-C22 hydrocarbon group; and b) 10-70 wt.% of polymerized unit of (meth )acry late monomer(s) comprising a terminal amine; optionally other (me th) acrylate monomers).

12. The aqueous composition of claim 11 further characterized by claims 2-9.

13. The aqueous composition of claims 11-12 wherein the solution has a pH of 6-7.

14. The aqueous composition of claims 1-13 wherein the intrinsic viscosity ranges from 0.3 to 0.5.

15. The aqueous composition of claims 1-13 wherein the acrylic copolymer and solution are free of silicone and fluorine.

16. A method of surface-treating a substrate comprising: applying the aqueous acrylic copolymer solution of claims 1 i ~15 to a surface of the substrate and allowing the solution to dry.

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