TW202104277A - Aqueous dispersion of polymeric particles and method of preparing the same - Google Patents

Abstract

An aqueous dispersion of polymeric particles comprising an acrylic polymer and a polyurethane, wherein the acrylic polymer comprises, by weight based on the weight of the acrylic polymer, from 0.1% to 10% of structural units of a (meth)acrylate functional siloxane, from 0.1% to 8% of structural units of a multiethylenically unsaturated monomer, and structural units of a monoethylenically unsaturated nonionic monomer; wherein the polymeric particles have a Tg of 0℃ or lower, and the weight ratio of polyurethane to acrylic polymer in the polymeric particles is from 20:80 to 99:1; a method of preparing the aqueous dispersion; and an aqueous coating composition comprising the aqueous dispersion.

Description

Aqueous dispersion of polymer particles and preparation method thereof

The present invention relates to an aqueous dispersion of polymer particles and a preparation method thereof.

Waterborne acrylic polymer emulsions are used in a wide range of coating applications. For example, acrylic emulsion polymers can be used in applications such as leather basecoats to create adhesion and early film softness. However, these polymers have limited use in leather top coatings that require balanced flexibility and abrasion resistance properties. Only increasing the glass transition temperature (Tg) of acrylic emulsion polymer can improve abrasion resistance, but adversely affect the resulting flexibility and softness of the coating produced, especially at low temperatures (for example, -10°C or lower) . In many applications such as automobiles, the coating composition is also required to provide a substrate with a relatively low flat finish, with a gloss of 2.0 or lower on the 60° Gardner Gloss scale. Therefore, there is still a need to provide aqueous dispersions that are particularly suitable for coating compositions that provide coatings with a balance of flexibility, abrasion resistance, and low gloss.

The present invention provides a novel aqueous dispersion containing polymer particles of acrylic polymer and polyurethane, which can be prepared by incorporating a specific amount of polyurethane during the polymerization process of the acrylic polymer. An aqueous coating composition containing such an aqueous dispersion can provide coatings made therefrom, which have a balanced cold bally flexibility rating of 3 (-10°C), Abrasion resistance as indicated by wet rubbing fastness and Gakushin rubbing fastness which are both shown as level 3, and preferably a glossiness (60°) of 2.0 or lower. These characteristics can be measured according to the test method described in the example section below.

（I） 其中R₁ 為直鏈或分支鏈C₁ -C₁₀ 伸烷基，R₂ 為氫或甲基，n為0至100，p為0至100，其限制條件為n+p為5至100； 0.1重量%至8重量%之多烯系不飽和單體之結構單元，及 單烯系不飽和非離子型單體之結構單元； 其中該等聚合物粒子之Tg為0℃或更低，且該等聚合物粒子中聚胺基甲酸酯與丙烯酸聚合物之重量比為20:80至99:1。In the first aspect, the present invention is an aqueous dispersion of polymer particles, which contains acrylic polymer and polyurethane, wherein the acrylic polymer contains: 0.1% to 10% by weight based on the weight of the acrylic polymer Weight% of the structural unit of (meth)acrylate functional silicone of formula (I),

(I) Where R ₁ is a linear or branched C ₁ -C ₁₀ alkylene, R ₂ is hydrogen or methyl, n is 0 to 100, p is 0 to 100, and the restriction is that n+p is 5 To 100; 0.1% to 8% by weight of structural units of polyethylenically unsaturated monomers and structural units of monoethylenically unsaturated nonionic monomers; wherein the Tg of the polymer particles is 0°C or more Low, and the weight ratio of polyurethane to acrylic polymer in the polymer particles is 20:80 to 99:1.

（I） 其中R₁ 為直鏈或分支鏈C₁ -C₁₀ 伸烷基，R₂ 為氫或甲基，n為0至100，p為0至100，其限制條件為n+p為5至100； 0.1重量%至8重量%之多烯系不飽和單體之結構單元，及 單烯系不飽和非離子型單體之結構單元； 其中該等聚合物粒子之Tg為0℃或更低，且該等聚合物粒子中聚胺基甲酸酯與丙烯酸聚合物之重量比為20:80至99:1。In the second aspect, the present invention is a method of preparing the aqueous dispersion of the first aspect. The method includes forming an acrylic polymer in an aqueous medium by emulsion polymerization in the presence of polyurethane to obtain an aqueous dispersion of polymer particles comprising acrylic polymer and polyurethane, wherein Based on the weight of the acrylic polymer, the acrylic polymer contains: 0.1% to 10% by weight of the structural unit of the (meth)acrylate functional silicone of formula (I),

(I) Where R ₁ is a linear or branched C ₁ -C ₁₀ alkylene, R ₂ is hydrogen or methyl, n is 0 to 100, p is 0 to 100, and the restriction is that n+p is 5 To 100; 0.1% to 8% by weight of structural units of polyethylenically unsaturated monomers and structural units of monoethylenically unsaturated nonionic monomers; wherein the Tg of the polymer particles is 0°C or more Low, and the weight ratio of polyurethane to acrylic polymer in the polymer particles is 20:80 to 99:1.

In the third aspect, the present invention is an aqueous coating composition comprising the aqueous dispersion of the first aspect, which further includes a matting agent, an additional polyurethane dispersion, and a hand-feel adjustment Agent, thickener, leveling agent, crosslinking agent or mixtures thereof.

The term "aqueous" dispersion in this context means particles dispersed in an aqueous medium. The "aqueous medium" herein includes water and 0 to 30% by weight of water-miscible compounds based on the weight of the medium, such as ethanol, glycol, glycol ether, glycol ester, and the like.

"Acrylic acid" as used herein includes (meth)acrylic acid, alkyl (meth)acrylate, (meth)acrylamide, (meth)acrylonitrile and modified forms thereof, such as acrylic acid (meth)hydroxyalkane ester. Throughout this document, the phrase "(meth)acryloyl" refers to both "methacryloyl" and "acryloyl". For example, (meth)acrylic acid refers to both methacrylic acid and acrylic acid, and methyl (meth)acrylate refers to both methyl methacrylate and methyl acrylate.

，其中虛線表示結構單元與聚合物主鏈之連接點。The "structural unit" of the named monomer, also known as "polymerization unit", refers to the residue of the monomer after polymerization (ie, polymerized monomer or monomer in polymerized form). For example, the structural unit of methyl methacrylate is shown in the figure:

, Where the dotted line indicates the connection point between the structural unit and the polymer backbone.

The aqueous dispersion of the present invention includes polymer particles, which include acrylic polymer and polyurethane (also referred to as "aqueous polyurethane/acrylic mixed dispersion"). The polymer particles can be obtained by forming an acrylic polymer in an aqueous medium by emulsion polymerization in the presence of polyurethane, usually a dispersion of polyurethane particles.

（I） 其中R₁ 為直鏈或分支鏈C₁ -C₁₀ 伸烷基，R₂ 為氫或甲基，n為0至100，p為0至100，其限制條件為n+p為5至100。R₁ 可為直鏈或分支鏈C₁ -C₈ 、C₁ -C₆ 或C₁ -C₃ 伸烷基，較佳地為-(CH₂ )₃ -。n及p可各自獨立地為0至60、0至50、0至40、0至30或0至20。較佳地，n+p為5至60、8至50、10至40、10至30或10至20。The acrylic polymer suitable for the present invention may contain one or more structural units of (meth)acrylate functional silicone of formula (I):

(I) Where R ₁ is a linear or branched C ₁ -C ₁₀ alkylene, R ₂ is hydrogen or methyl, n is 0 to 100, p is 0 to 100, and the restriction is that n+p is 5 To 100. R ₁ can be linear or branched C ₁ -C ₈ , C ₁ -C ₆ or C ₁ -C ₃ alkylene, preferably -(CH ₂ ) ₃ -. n and p may each independently be 0-60, 0-50, 0-40, 0-30, or 0-20. Preferably, n+p is 5-60, 8-50, 10-40, 10-30 or 10-20.

Based on the weight of the acrylic polymer, the acrylic polymer suitable for the present invention may contain 0.1% by weight or more, 0.2% by weight or more, 0.3% by weight or more, 0.4% by weight or more, 0.5% by weight or More, 0.6% by weight or more, 0.7% by weight or more, 0.8% by weight or more, 0.9% by weight or more, 1.0% by weight or more, 1.1% by weight or more, 1.2% by weight or more More, 1.5% by weight or more, or even 2% by weight or more, and at the same time 10% by weight or less, 9.0% by weight or less, 8.0% by weight or less, 7.0% by weight or less, 6.0% by weight % Or less, 5.0% by weight or less or even 4.0% by weight less (meth)acrylate functional silicone structural units.

The acrylic polymer suitable for the present invention may contain one or more structural units of polyethylenically unsaturated monomers. "Polyethylenically unsaturated monomer" means that the monomer has two or more ethylenically unsaturated bonds. Examples of suitable polyethylenically unsaturated monomers include allyl (meth)acrylate, hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate Base) acrylate, butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, divinylbenzene, allyl(meth)acrylamide, (meth)acrylic acid Allyloxyethyl, crotonyl (meth)acrylate, diallyl maleate or a mixture thereof. The preferred polyethylenically unsaturated monomer is allyl methacrylate. Based on the weight of the acrylic polymer, the acrylic polymer may contain 0.1% by weight to 8% by weight, for example, 0.1% by weight or more, 0.2% by weight or more, 0.3% by weight or more, 0.4% by weight or more, 0.5% by weight or more, 0.6% by weight or more, 0.7% by weight or more, 0.8% by weight or more, 0.9% by weight or more, 1.0% by weight or more, 1.1% by weight or more, 1.2 % By weight or more, 1.3% by weight or more, 1.4% by weight or more, 1.5% by weight or more, 1.6% by weight or more, 1.7% by weight or more, 1.8% by weight or more, 1.9% by weight % Or more, or even 2.0% by weight or more, and at the same time 8.0% by weight or less, 7.5% by weight or less, 7.0% by weight or less, 6.5% by weight or less, 6.0% by weight or less , 5.5% by weight or less, 5.0% by weight or less, 4.5% by weight or less, 4.0% by weight or less, 3.5% by weight or less, 3.0% by weight or less, or even 2.5% by weight or more A small amount of structural units of polyethylenically unsaturated monomers.

The acrylic polymer suitable for the present invention may contain one or more structural units of monoethylenically unsaturated nonionic monomers. The term "non-ionic monomer" as used herein refers to a monomer that does not carry an ionic charge between pH=1-14. Suitable examples of ethylenically unsaturated nonionic monomers include (meth)acrylic acid alkyl esters, which preferably have an alkyl group containing 1 to 32 carbon atoms, such as (meth)acrylic acid C ₁ -C ₁₈ Alkyl ester, C ₁ -C ₁₂ alkyl ester of (meth)acrylic acid or C ₁ -C ₄ alkyl ester of (meth)acrylic acid, such as methyl acrylate, methyl methacrylate, ethyl acrylate, methyl acrylate Ethyl acrylate, 2-ethylhexyl acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, decyl acrylate, isodecyl methacrylate , Isobornyl (meth)acrylate, lauryl (meth)acrylate and stearyl (meth)acrylate; (meth)acrylonitrile; vinyl aromatic monomers, including styrene and substituted styrene Or mixtures thereof; butadiene; ethylene, propylene, alpha-olefins, such as 1-decene; and vinyl monomers, such as vinyl acetate, vinyl butyrate, vinyl chloride, vinylidene chloride, vinyl neodecanoate Esters and other vinyl esters, cycloalkyl (meth)acrylates, including cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, dihydrodicyclopentadiene (meth)acrylate, Trimethylcyclohexyl (meth)acrylate, tert-butyl(meth)cyclohexyl acrylate; or a combination thereof. The preferred monoethylenically unsaturated nonionic monosystem is selected from the group consisting of butyl acrylate, butyl methacrylate, methyl methacrylate, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate Esters and mixtures thereof. Based on the weight of the acrylic polymer, the acrylic polymer may contain 72% by weight or more, 77% by weight or more, 80% by weight or more, 82% by weight or more, 84% by weight or more, 85% by weight % Or more, 90% by weight or more, or even 92% by weight or more, and at the same time 99.8% by weight or less, 99.7% by weight or less, 99.6% by weight or less, 99.5% by weight or less , 99% by weight or less, 98.5% by weight or less, or even 98% by weight or less of the structural units of monoethylenically unsaturated nonionic monomers.

The acrylic polymer suitable for the present invention may contain one or more monoethylenically unsaturated functional monomers (which carry at least one functional group selected from the group consisting of amide, ureido, carboxyl, carboxylic anhydride, hydroxyl, sulfonic acid, The structural units of sulfonate, phosphoric acid or phosphate group), their salts or mixtures thereof, these monomers are different from the monoethylenically unsaturated nonionic monomers described above. Examples of suitable monoethylenically unsaturated functional monomers include α,β-ethylenically unsaturated carboxylic acids, which include acid-bearing monomers such as methacrylic acid, acrylic acid, itaconic acid, maleic acid or Fumaric acid; or monomers with acid-forming groups, which are produced or subsequently converted into such acid groups, such as acid anhydride, (meth)acrylic anhydride or maleic anhydride; vinyl phosphonic acid; alkene Propyl phosphoric acid; phosphoalkyl (meth)acrylate, such as phosphoethyl (meth)acrylate, phosphopropyl (meth)acrylate, phosphobutyl (meth)acrylate; salts thereof; and mixtures thereof; CH ₂ =C(R)-C(O)-O-(R ^l O) _q -P(O)(OH) ₂ , where R=H or CH ₃ , R ¹ = alkylene and q=1- 10, such as SIPOMER PAM-100, SIPOMER PAM-200, SIPOMER PAM-300 and SIPOMER PAM-600 all available from Solvay; (meth)acrylic acid phosphate alkoxy esters, such as phosphate glycol (Meth) acrylate, phosphate-based diethylene glycol (meth)acrylate, phosphate-based triethylene glycol (meth)acrylate, phosphate-based propylene glycol (meth)acrylate, phosphate-based dipropylene glycol (meth) ) Acrylate, phosphate tripropylene glycol (meth)acrylate, and its salt; sodium styrene sulfonate, sodium vinyl sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamidoamine Sodium salt of 2-methyl-1-propanesulfonic acid, ammonium salt of 2-propenamido-2-methyl-1-propanesulfonic acid; sodium salt of allyl ether sulfonate; acrylamide , Methacrylamide, monosubstituted (meth)acrylamide, N-methacrylamide, N-ethacrylamide, N-isopropylacrylamide, N-butylacrylamide Amine, N-tertiary butyl acrylamide, N-2-ethylhexyl acrylamide, N,N-dimethyl acrylamide, N,N-diethyl acrylamide; hydroxyl functionality (formula Yl)alkyl acrylates, such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; ureido functional monomers, such as hydroxyethyl ethylene urea methacrylate, hydroxyethyl ethylene urea Acrylic esters, such as SIPOMER WAM II, methacrylamide ethyl ethylene urea or mixtures thereof. Preferred ethylenically unsaturated functional monomers are acrylic acid, sodium styrene sulfonate, acrylamide, methacrylamide, methacrylic acid or mixtures thereof. Although it is possible for acrylic polymers to include structural units of monoethylenically unsaturated functional monomers (such as carboxylic acid monomers), preferred acrylic polymers contain structures that are substantially absent of monoethylenically unsaturated functional monomers unit. As used herein, substantially absent means that based on the weight of the acrylic polymer, the structural unit of the monoethylenically unsaturated functional monomer is less than 10% by weight, less than 6% by weight, less than 5% by weight, less than 3% by weight, Less than 1% by weight, less than 0.5% by weight, less than 0.2% by weight, less than 0.1% by weight or even zero.

In some embodiments, based on the weight of the acrylic polymer, the acrylic polymer suitable for the present invention may include: 0.2% to 10% by weight of (meth)acrylate functional silicone structural units, 0.2% by weight Up to 8% by weight of the structural units of polyethylenically unsaturated monomers (such as allyl methacrylate) and 72% to 99.6% by weight of the structural units of monoethylenically unsaturated nonionic monomers, and optionally 0 Up to 10% by weight of structural units of monoethylenic functional monomers (such as α,β-ethylenically unsaturated carboxylic acids). Preferably, based on the weight of the acrylic polymer, the acrylic polymer in the polymer particles contains: 0.2% to 8% by weight of (meth)acrylate functional silicone structural units, 0.2% to 8% by weight % Of the structural units of polyethylenically unsaturated monomers, 84% by weight to 99.6% by weight of the structural units of monoethylenically unsaturated nonionic monomers, and optionally 0 to less than 5% by weight of monoethylenically unsaturated monomers The structural unit of a functional monomer.

The polyurethane suitable for use in the present invention may be the reaction product of one or more polyols and one or more isocyanate compounds. "Polyol" refers to any product having two or more hydroxyl groups per molecule. Polyols suitable for preparing polyurethane can include polyether diols, polyester diols, polycarbonate polyols, multifunctional polyols or mixtures thereof. The polyol can be selected from polyether polyols, polyester polyols, polycarbonate polyols or mixtures thereof.

Polyether polyols suitable for the preparation of polyurethanes may contain -C-O-C- groups. It can be achieved by combining a starting compound containing reactive hydrogen atoms (such as water or glycol) with alkylene oxide (such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin) Or a mixture thereof). Preferred polyether polyols include poly(propylene glycol), polytetrahydrofuran, and copolymers of poly(ethylene glycol) and poly(propylene glycol) with a molecular weight of 400 to 3,000. Suitable glycols for preparing polyether polyols may include alkylene glycols, preferably ethylene glycol, diethylene glycol and butylene glycol.

Polyester polyols suitable for the preparation of polyurethanes are generally esterified products prepared by reacting organic polycarboxylic acids or their anhydrides with a stoichiometric excess of diols. Examples of suitable polyester polyols suitable for preparing polyurethanes include poly(glycol adipate), poly(ethylene terephthalate) polyol, polycaprolactone polyol, alkyd Resin polyols, phthalic acid polyols, sulfonated and phosphonate polyols and mixtures thereof. Diols suitable for preparing polyester polyols include those diols described above for preparing polyether polyols. Suitable carboxylic acids suitable for preparing polyester polyols may include dicarboxylic acids, tricarboxylic acids and anhydrides, such as maleic acid, maleic anhydride, succinic acid, glutaric acid, glutaric anhydride, and adipic acid. Acid, suberic acid, pimelic acid, azelaic acid, sebacic acid, chlorobridge acid, 1,2,4-butane-tricarboxylic acid, phthalic acid, phthalic acid isomers, phthalic acid Dicarboxylic anhydride, fumaric acid, dimerized fatty acid (such as oleic acid) and the like or mixtures thereof. Preferred polycarboxylic acids suitable for preparing polyester polyols include aliphatic and aromatic dibasic acids.

The isocyanate compound suitable for preparing polyurethane has an average of two or more isocyanate groups, preferably two to three isocyanate groups per molecule. Isocyanate compounds generally contain about 5 to 20 carbon atoms and include aliphatic, cycloaliphatic, aryl-aliphatic and aromatic polyisocyanates, oligomers thereof, or mixtures thereof. Preferred isocyanate compounds are diisocyanates such as toluene diisocyanate, hexamethylene isocyanate and isophorone isocyanate.

Suitable aliphatic isocyanate compounds in the present invention may include, for example, ω-alkylene diisocyanates having 5 to 20 carbon atoms, such as hexamethylene-1,6-diisocyanate, 1,12-dodecane diisocyanate Isocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate Isocyanates and mixtures thereof. Preferred aliphatic polyisocyanates are hexamethylene-1,6-diisocyanate, 2,2,4-trimethyl-hexamethylene-diisocyanate, 2,4,4-trimethyl-hexamethylene -Based diisocyanates or mixtures thereof. Examples of suitable cycloaliphatic isocyanate compounds include dicyclohexylmethane diisocyanate (such as DESMODUR polyisocyanate from Covestro), isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3 -Bis-(isocyanatomethyl)cyclohexane or mixtures thereof. Preferably, the cycloaliphatic isocyanate compound is selected from dicyclohexylmethane diisocyanate and isophorone diisocyanate. Examples of suitable araliphatic isocyanate compounds include m-tetramethyl xylene diisocyanate, p-tetramethyl xylene diisocyanate, 1,4-xylene diisocyanate, 1,3-xylene diisocyanate or Its mixture. The preferred araliphatic isocyanate compound is tetramethyl xylene diisocyanate. Examples of suitable aromatic isocyanate compounds include 4,4'-dibenzylidene diisocyanate, toluene diisocyanate, isomers thereof, naphthalene diisocyanate, oligomeric forms thereof, or mixtures thereof. The preferred aromatic isocyanate compound is toluene diisocyanate.

The polyurethane dispersion suitable for the present invention can be prepared by techniques known in the art, for example, first by making at least one polyol and at least one isocyanate compound described above in a catalyst, a solvent, or the like. The reaction is carried out in the presence of the mixture to prepare polyurethane; as the case may be, the obtained polyurethane is usually dispersed in water in the presence of a surfactant; and as the case is, the polyurethane is dispersed in the water Add polyamine before, during, and/or after.

The hydroxyl number (OH) of the polyurethane suitable for the present invention can be, for example, 0 mgKOH/g to 50 mgKOH/g, such as 40 mgKOH/g or lower or 30 mgKOH/g or lower, as by Measured by ASTM D 1957-86 (2001) method. The acid value of the polyurethane suitable for the present invention can be 10 mgKOH/g to 100 mgKOH/g, such as 10 mgKOH/g or more, 15 mgKOH/g or more, or even 20 mgKOH/g or More, as determined by ASTM D 974 (2008) method.

The number average molecular weight of the polyurethane suitable for the present invention can be 2,000 g/mol or more, 3,000 g/mol or more, 4,000 g/mol or more, 5,000 g/mol or more, 6,000 g/mol or more, 8,000 g/mol or more, or even 10,000 g/mol or more, as measured by gel permeation chromatography (GPC) and polystyrene standards. Polyurethane is usually supplied in the form of an aqueous dispersion. The particle size of the polyurethane particles in the aqueous polyurethane dispersion can be in the range of 30 nm to 500 nm, 40 nm to 300 nm, or 50 nm to 100 nm. The particle size in this article means the average particle size as measured by the Brookhaven 90Plus particle size analyzer described in the Examples section below.

The weight ratio of polyurethane to acrylic polymer in the polymer particles can be 20:80 to 99:1, 22.5:77.5 to 95:5, 25:75 to 90:10, 27.5:72.5 to 87.5:12.5 , 30:70 to 85:15, 32.5:67.5 to 82.5:17.5, 35:65 to 80:20, 40:60 to 77.5:22.5, 42.5:57.5 to 75:25, 45:55 to 70:30, 47.5 : 52.5 to 65:35, 50:50 to 60:40 or 50:50 to 55:45.

The aqueous dispersion of polymer particles of the present invention can be prepared by emulsion polymerization of monomers used to prepare acrylic polymers in an aqueous medium in the presence of polyurethane. During polymerization, acrylic polymer grafted polyurethane can be formed. Without being bound by theory, after the polymerization process, the acrylic polymer is embedded in the polymer particles. The emulsion polymerization techniques used to prepare acrylic polymers are well known in the art. The temperature suitable for emulsion polymerization can be lower than 100°C, in the range of 15 to 95°C, or in the range of 30 to 90°C. The monomers used in the preparation of acrylic polymers may include the (meth)acrylate siloxanes, polyethylenically unsaturated monomers, monoethylenically unsaturated nonionic monomers, and optionally monoethylenic monomers as described above. Unsaturated functional monomer. The total weight concentration of the monomers used to prepare the acrylic polymer is equal to 100%. The weight ratio of polyurethane to the total weight of the monomers used to prepare the acrylic polymer may be the same as the weight ratio of polyurethane to acrylic polymer as described above, for example, between 20:80 and Within 99:1.

The preparation of the aqueous dispersion of polymer particles can be carried out by first providing polyurethane, preferably an aqueous dispersion of polyurethane, and then loading and Polymerize a mixture of monomers forming structural units of acrylic polymer to obtain an aqueous dispersion of polymer particles. The mixture of monomers may include the monomers described above, (meth)acrylate functional silicones, polyethylenically unsaturated monomers, and monoethylenically unsaturated nonionic monomers. The monomer mixture used to prepare the acrylic polymer can be added without water or in the form of an emulsion in water; or added in one or more ways or continuously, linearly or non-linearly or a combination thereof during the polymerization reaction period. The temperature suitable for the emulsion polymerization process can be lower than 100°C, in the range of 15 to 95°C, or in the range of 30 to 90°C. The above-described multi-stage free radical polymerization using monomers can be used, wherein at least two stages are formed sequentially, and the multi-stage free radical polymerization generally results in the formation of a multi-stage polymer comprising at least two polymer compositions.

In emulsion polymerization, free radical initiators can be used. The emulsion polymerization method can be thermally initiated or redox initiated emulsion polymerization. Examples of suitable free radical initiators include hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate and/or alkali metal persulfate, sodium perborate, perphosphoric acid and salts thereof; The ammonium or alkali metal salt of potassium permanganate and peroxodisulfuric acid. Based on the total weight of the monomers, the free radical initiator can usually be used in a content of 0.01 to 3.0% by weight. A redox system comprising the initiator described above together with a suitable reducing agent can be used in the polymerization process. Examples of suitable reducing agents include sodium formaldehyde sulfoxylate, ascorbic acid, erythorbic acid, alkali metal and ammonium salts of sulfur-containing acids (such as sodium sulfite, bisulfite, thiosulfate, bisulfite, sulfide, hydrosulfide Or disulfinate, formamidine sulfinic acid, acetone bisulfite), glycolic acid, hydroxymethanesulfonic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid and the salts of the foregoing acids . Metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium or cobalt can be used to catalyze redox reactions. A chelating agent for metals can be used as appropriate.

In emulsion polymerization, one or more surfactants can be used. The surfactant can be added before or during the polymerization of the monomer or a combination thereof. It is also possible to add a part of the surfactant after the polymerization. These surfactants may include anionic and/or nonionic emulsifiers. Examples of suitable surfactants include alkali metal or ammonium salts of alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates; alkyl sulfonic acids; sulfosuccinates; fatty acids; polymerizable interfacial activity Agent; and ethoxylated alcohol or phenol. Based on the total weight of the monomers used to prepare the acrylic polymer, the surfactant used is usually 0.1% to 6% by weight, or 0.3% to 1.5% by weight.

In emulsion polymerization, one or more chain transfer agents can be used. Examples of suitable chain transfer agents include 3-mercaptopropionic acid, dodecyl mercaptan, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, thiophenol, alkyl azelate or mixtures thereof . The chain transfer agent can be used in an effective amount to control the molecular weight of the acrylic polymer, for example, 0 to 2.5% by weight, 0.03% to 1% by weight, or 0.05% to 1% by weight based on the total weight of the monomers used to prepare the acrylic polymer. 0.5% by weight.

After the completion of the emulsion polymerization, the obtained aqueous dispersion of polymer particles can be neutralized to a pH value of at least 6, 6 to 10, or 7 to 9 with one or more bases as a neutralizing agent. The base can cause partial or complete neutralization of the ionic or latent ionic groups of the acrylic polymer. Examples of suitable bases include ammonia; alkali metal or alkaline earth metal compounds, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, zinc oxide, magnesium oxide, sodium carbonate; primary, secondary and tertiary amines, such as triethylamine, Ethylamine, propylamine, monoisopropylamine, monobutylamine, hexylamine, ethanolamine, diethylamine, dimethylamine, di-n-propylamine, tributylamine, triethanolamine, dimethoxyethylamine, 2-ethoxyethane Amine, 3-ethoxypropylamine, dimethylethanolamine, diisopropanolamine, morpholine, ethylenediamine, 2-diethylaminoethylamine, 2,3-diaminopropane, 1,2- Propylenediamine, neopentanediamine, dimethylaminopropylamine, hexamethylenediamine, 4,9-dioxododecane-1,12-diamine, polyethylenediimine or polyvinylamine; aluminum hydroxide ; And its mixtures. The aqueous dispersion of polymer particles of the present invention preferably has a coagulum content of 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or even 0.25% or less.

Measure the condensate content according to the test method described in the example section below. The Tg of the polymer particles in the aqueous dispersion of the present invention may be 0°C or lower, such as -2°C or lower, -5°C or lower, -8°C or lower, or even -10°C or lower. Low, and at the same time, -60°C or higher, -55°C or higher, -50°C or higher, -45°C or higher, -40°C or higher, -35°C or higher, -30°C Or higher, -28°C or higher, or even -25°C or higher. The Tg value of the polymer particles is measured by DSC as described in the Examples section below.

The particle size of the polymer particles in the aqueous dispersion of the present invention can be 30 nanometers (nm) or more, 40 nm or more, 50 nm or more, or even 60 nm or more, and at the same time 800 nm or more Smaller, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 150 nm or less, or even 120 nm or less small. The particle size herein means the average particle size determined by the Brookhaven 90Plus particle size analyzer as described in the Examples section below.

The present invention also relates to an aqueous coating composition comprising an aqueous dispersion of polymer particles as described above. Based on the solid weight of the water-based coating composition, the water-based coating composition may contain 20% by solid weight or more, 25% by solid weight or more, 30% by solid weight or more, or even 35% by solid weight or more. More, and at the same time 80% solids by weight or less, 70% by solids by weight or less, 60% by solids by weight or less, 50% by solids or less, or even 40% by solids by weight of polymer particles .

The aqueous coating composition of the present invention may further comprise an additional polyurethane dispersion. The polyurethane dispersion may be the same as or different from those polyurethane dispersions used to prepare the above-described aqueous dispersions of polymers. Based on the total solid weight of the coating composition, an additional polyurethane dispersion of 0 to 80 solids weight %, 5 solids weight% to 50 solids weight %, or 10 solids weight% to 40 solids weight% may be present In the water-based coating composition.

The aqueous coating composition of the present invention may further include one or more thickeners, also known as "rheology modifiers". Examples of suitable thickeners include alkali-swellable emulsions (ASE); hydrophobically modified alkali-swellable emulsions (HASE); associative thickeners, such as hydrophobically modified ethoxylated urethanes (HEUR) ; And cellulose thickeners, such as methyl cellulose ether, hydroxymethyl cellulose (HMC), hydroxyethyl cellulose (HEC), hydrophobically modified hydroxyethyl cellulose (HMHEC), carboxymethyl cellulose Sodium Sulfate (SCMC), Sodium Carboxymethyl 2-Hydroxyethyl Cellulose, 2-Hydroxypropyl Methyl Cellulose, 2-Hydroxyethyl Methyl Cellulose, 2-Hydroxybutyl Methyl Cellulose, 2-Hydroxyethyl Base ethyl cellulose and 2-hydroxypropyl cellulose. The preferred thickener is HEUR, HASE or ASE. Based on the total solid weight of the water-based coating composition, the thickener can be 0 to 7 solid weight%, 0.01 solid weight% to 6 solid weight%, 0.1 solid weight% to 5 solid weight%, 0.2 solid weight% to 4 solids % By weight, or 0.5% by solid weight to 3% by solid weight.

The aqueous coating composition of the present invention may also contain one or more leveling agents. "Leveling agent" refers to a chemical substance that enables the coating composition to wet the substrate more uniformly and reduce surface defects. Examples of suitable leveling agents include polydimethylsiloxane, modified polydimethylsiloxane, polyacrylates, fluorocarbon surfactants or mixtures thereof. Based on the total solid weight of the coating composition, the leveling agent can be 0 to 10% by weight, 0.1% to 7% by weight, 0.3% to 6% by weight, 0.5% to 5% by weight, or 0.7% by weight to 4% by weight is present.

The aqueous coating composition of the present invention may further include one or more matting agents. The term "matting agent" in this article refers to any inorganic or organic particles that provide a matt effect. According to ASTM E2651-10 (2010) Standard Guide for Powder Particle Size Analysis, the average particle size of the matting agent is usually 3.5 microns or longer. Suitable matting agents suitable for use in the present invention may include silicon dioxide matting agents, polyurea matting agents, polyacrylate matting agents, polyethylene matting agents, polytetrafluoroethylene matting agents and mixtures thereof. Preferred matting agents are silicon dioxide matting agents, polyacrylate matting agents, polyurea matting agents and mixtures thereof. Suitable commercially available matting agents can include ACEMATT TS-100 and OK520 silica matting agents available from Evonik, DEUTERON MK polyurea matting agents available from Deuteron, and SYLOID Silica available from Grace Davison 7000 matting agent, polyacrylate-based PARALOID ^TM PRD 137B emulsion available from The Dow Chemical Company (PARALOID is a trademark of Dow Chemical Company); HDPE/plastic-based ULTRALUBE D277 emulsion, lignite-based Wax/PE/plastic ULTRALUBE D818 emulsion, and PE/ester matting agent-based ULTRALUBE D860 emulsion both available from Keim-Additec; and their mixtures. Based on the solid weight of the aqueous coating composition, the matting agent may be 2 solid weight% or more, 3 solid weight% or more, 4 solid weight% or more, or even 5 solid weight% or more, and at the same time 60% solids by weight or less, 50% solids by weight or less, 40% solids by weight or less, 30% solids by weight or less, 25% solids by weight or less, 20% solids by weight or less, 15 solids It is present in an amount of weight% or less, or even 10 solid weight% or less.

The aqueous coating composition of the present invention may also contain one or more hand feeling modifiers. "Hand-feel modifier" refers to a chemical added to the coating formulation for the purpose of making the dry film made of it have a desirable hand-feel. Examples of suitable hand-feel modifiers include silicones, wax emulsions, polyacrylic acid polymers, and mixtures thereof. Based on the total solid weight of the coating composition, the feel modifier may be 0 to 40 solid weight%, 2 solid weight% to 30 solid weight%, 4 solid weight% to 25 solid weight%, or 6 solid weight% to 20 solid weight% % By weight is present.

The aqueous coating composition of the present invention may further include one or more crosslinking agents. Examples of suitable crosslinking agents include polyfunctional aziridines, polycarbodiimides or polyisocyanates. The polyisocyanate crosslinking agent may include the isocyanate compound described above when preparing the polyurethane dispersion, preferably in an oligomeric form, and more preferably a water-dispersible polyisocyanate. The polyisocyanate suitable for use in the present invention may have an average of two or more isocyanate (NCO) groups, and preferably has two to four isocyanate groups per molecule. Polyisocyanates generally contain 5 to 100 carbon atoms, 10 to 80 carbon atoms, or 15 to 50 carbon atoms. The polyisocyanate is preferably an aliphatic or cycloaliphatic polyisocyanate. More preferably, the polyisocyanate is a hexamethylene diisocyanate homopolymer, a hexamethylene diisocyanate adduct, an isophorone diisocyanate homopolymer, an isophorone diisocyanate adduct or a mixture thereof. Based on the total solid weight of the water-based coating composition, the cross-linking agent in the water-based coating composition can be 0-50% by solid weight, for example, 5% by solid weight or more, 10% by solid weight or more, 15% by solid weight % Or more, 20 solid weight% or more, 25 solid weight% or more, or even 30 solid weight% or more, and at the same time 50 solid weight% or less, 45 solid weight% or less, 40 Solid weight% or less, or even 35 solid weight% or less is present.

The aqueous coating composition of the present invention may further include one or more coalescing agents. Examples of suitable coalescents include 2-n-butoxyethanol, dipropylene glycol n-butyl ether, propylene glycol n-butyl ether, dipropylene glycol methyl ether, propylene glycol methyl ether, propylene glycol n-propyl ether, diethylene glycol monobutyl ether, ethylene two Alcohol monobutyl ether, ethylene glycol monohexyl ether, triethylene glycol monobutyl ether, dipropylene glycol n-propyl ether, n-butyl ether or mixtures thereof. Based on the total weight of the coating composition, the coalescing agent may be present in an amount of 0% to 15% by weight, 0.01% to 10% by weight, or 0.1% to 5% by weight.

The aqueous coating composition of the present invention may further include pigments and/or synergists. In this context, "pigment" refers to a granular inorganic material that can substantially contribute to the opacity or hiding power of the coating. The refractive index of such materials is usually greater than 1.8. The inorganic pigment may include, for example, titanium dioxide (TiO ₂ ), zinc oxide, iron oxide, zinc sulfide, barium sulfate, barium carbonate, or mixtures thereof. In a preferred embodiment, the pigment used in the present invention is TiO ₂ . TiO ₂ usually exists in two crystal forms, anatase and rutile. TiO ₂ can also be obtained as a concentrated dispersion. The aqueous coating composition may also contain one or more synergists. The "synergist" herein refers to a granular material with a refractive index less than or equal to 1.8 and greater than 1.3. Examples of suitable synergists include calcium carbonate, clay, calcium sulfate, aluminosilicate, silicate, zeolite, mica, diatomaceous earth, solid or hollow glass, ceramic beads, nepheline syenite, feldspar, diatom Earth, calcined diatomaceous earth, talc (hydrated magnesium silicate), silica, alumina, kaolin, pyrophyllite, perlite, barite, wollastonite, opaque polymers (such as those available from Dow Chemical The company’s ROPAQUE™ Ultra E (ROPAQUE is a trademark of The Dow Chemical Company) or its mixture. Based on the total solid weight of the coating composition, the pigment and/or synergist may be present in a combined amount of 0 to 30% by weight, 2% to 25% by weight, or 4% to 20% by weight.

In addition to the components described above, the aqueous coating composition of the present invention may further include any one or a combination of the following additives: buffering agent, neutralizing agent, freezing/thawing additives, moisturizers, antifungal agents, Biocides, anti-skinning agents, coloring agents, antioxidants, plasticizers, thixotropic agents, adhesion promoters and abrasive agents. Based on the solid weight of the aqueous coating composition, these additives may be present in a combined amount of 0 to 10 solid weight%, 0.3 solid weight% to 5 solid weight%, or 0.5 solid weight% to 3 solid weight%.

The solid content of the aqueous coating composition can be in the range of 10% to 60% by weight, 15% to 50% by weight, or 25% to 45% by weight based on the weight of the coating composition.

The aqueous coating composition of the present invention can be mixed with an aqueous dispersion of polymer particles and other optional components, such as matting agents, thickeners, leveling agents and/or crosslinking agents as described above To prepare. The components can be mixed in any order in the aqueous coating composition to provide the aqueous coating composition of the present invention. Any of the above-mentioned optional components may also be added to the composition during or before mixing to form an aqueous coating composition.

The aqueous coating composition of the present invention can be applied to construction substrates or industrial substrates, including, for example, flexible substrates including leather (such as natural leather, artificial leather, synthetic leather, and vinyl leather), such as leather upholstery. , Such as automotive upholstery, metal, plastic, foam material, stone, elastic substrate, fabric, paper, cardboard, cardboard, wood or by any known method, such as brushing, dipping, rolling And spraying cementitious substrate. The coating composition is especially suitable for the surface treatment of automobile leather. The water-based coating composition can be applied to unprocessed or undercoated leather, such as mineral tanned leather or vegetable tanned leather, including full-grain leather, polished or modified grain leather, by roller coating or knife coating , And layered leather; or applied to paper; by curtain coater and spraying methods, such as air atomization spraying, air spraying, airless spraying, high-volume low-pressure spraying, and airless airless spraying. The aqueous coating composition can be directly applied to the leather or indirectly coated on the primer layer. The primer can be a conventional primer, including (meth)acrylic polymer, polyurethane, polyacrylonitrile, polybutadiene, polystyrene, polyvinyl chloride, polyvinylidene chloride, Polyvinyl acetate and combinations thereof.

The present invention also provides a method for preparing a coating on a substrate (coated with a primer layer as appropriate), the method comprising: applying the aqueous coating composition of the present invention to the substrate, and drying the applied coating composition, Or let it dry to produce a coating. The substrate is preferably a leather surface. The water-based coating composition can provide a coating with cold Barre flexibility (-10°C), wet rubbing fastness and Gakushin rubbing fastness (all shown as level 3). The water-based coating composition can also provide a gloss of 2.0 or lower, preferably 1.6 or lower, 1.5 or lower, 1.4 or lower, 1.3 or lower or even 1.2 on the 60° Gardner gloss scale. Or lower coating. These characteristics are measured according to the test method described in the example section below. The present invention also relates to a method of using an aqueous coating composition, the method comprising forming an aqueous coating composition, applying the aqueous coating composition to the leather surface, and drying the applied coating composition, or allowing it to dry. Drying can be performed in a known manner, such as air drying or thermal drying at a temperature that will not damage the substrate (for example, 50 to 130°C, 60 to 125°C, or 70 to 120°C).

Instance Some embodiments of the present invention will now be described in the following examples, where unless otherwise specified, all parts and percentages are by weight. The following materials are used in the examples: The BAYDERM Finish 91UD dispersion (40% solids) available from The Dow Chemical Company is a polyurethane dispersion with an average particle size of about 60-80 nm, as described by Brookhaven 90Plus particle size analysis as described below Measured by the instrument.

Sodium lauryl sulfate (SLS) available from Solvay is used as a surfactant.

Sodium laurylbenzene sulfonate (DS-4) available from Solvay is used as a surfactant.

Methyl methacrylate (MMA), butyl acrylate (BA), acrylic acid (AA), methacrylic acid (MAA) and allyl methacrylate (ALMA) are all monomers available from The Dow Chemical Company.

BRUGGOLITE FF6 reducing agent can be purchased from Brueggemann Chemical.

Kathon LXE (1.5% solids) and Kathon LX (14.2% solids) biocides are available from The Dow Chemical Company.

，其中n+p = 12~25。The reactive polysiloxane available from The Dow Chemical Company (hereinafter referred to as "RS 123") has the following structure,

, Where n+p = 12~25.

Silok 3560 methacrylate polysiloxane available from Guangzhou Silok Polymer Co., Ltd. is a crosslinkable polysiloxane resin with reactive functional organopolysiloxanes (molecular weight: about 60000 and Unsaturation: about 4.5%).

Silok 3572 allyl polyether polysiloxane available from Guangzhou Silok Polymer Co., Ltd. contains unsaturated groups (-CH ₂ CH=CH ₂ ), and has a molecular weight of about 8000 and an unsaturation of about 0.5% .

Aquaderm Fluid H (100% solids) available from Lanxess Chemical is a polysiloxane/polyether copolymer leveling agent.

OPTI-MATTTM UD-4 duller (25% solids) available from The Dow Chemical Company is an aqueous dispersion of a combination of an organic dulling agent and silica.

^{ROSILK ™} 2229 feel modifier (58% solids) purchased from The Dow Chemical Company is a water-based silicone emulsion.

^{ACRYSOL TM} RM-819W thickener (23% solids) purchased from The Dow Chemical Company is a hydrophobically modified ethoxylated urethane.

ACRYSOL RM-2020 thickener (20% solids) available from The Dow Chemical Company is a non-ionic urethane rheology modifier.

BINDER LS-3486-HS (51% solids) purchased from The Dow Chemical Company is a reactive aliphatic polyisocyanate resin, which is provided in ethyl 3-ethoxypropionate as a crosslinking agent.

OPTI-MATT, ROSILK, HYDRHOLAC and ACRYSOL are trademarks of The Dow Chemical Company.

The following standard analytical equipment and methods are used in the examples. Differential scanning calorimetry (DSC) method

DSC is used to measure the Tg of polymers. Under nitrogen (N ₂ ) atmosphere, analyze 5-10 milligrams (mg) samples in a sealed aluminum pan on a TA instrument DSC Q2000 equipped with an autosampler. The Tg measurement is carried out in three cycles. The cycles include: from -60 to 200°C at a rate of 10°C/min, followed by holding for 5 minutes (the first cycle); and from 200 to-at a rate of 10°C/min 60°C (the second cycle); and at a rate of 10°C/min from -60 to 200°C (the third cycle). The Tg is obtained from the third cycle by taking the midpoint of the heat flow versus temperature conversion as the Tg value.

Particle size measurement By using the Brookhaven 90Plus particle size analyzer (which uses photon correlation spectroscopy (light scattering of sample particles) technology), the particle size of the polymer particles in the aqueous polymer dispersion is measured. This method involves diluting 2 drops of the aqueous polymer dispersion to be tested in 20 ml of 0.01 M NaCl solution, and further diluting the resulting mixture in the sample colorimetric tube to achieve the desired counting rate (K) (for example, in the 10- For diameters in the range of 300 nm, the K range is 250 to 500 counts per minute, and for diameters in the range of 300-500 nm, the K range is 100 to 250 counts per minute). Next, the particle size of the aqueous polymer dispersion is measured and reported as the average diameter based on strength.

Condensate content of the aqueous dispersion of polymer particles The aqueous dispersion of polymer particles is filtered through a 44 micron (325 mesh) screen. The residue remaining on the screen was washed with water and placed in an oven at 150°C for 15 minutes. The coagulum content is determined by dividing the dry weight of the residue on the screen by the initial total wet weight of the aqueous dispersion. The lower the coagulum content, the more stable the polymerization process when preparing the aqueous dispersion.

Characteristics of the coating composition First, with 66 g/m² (6 g/ft² ) Spray the primer on the leather substrate. The primer layer consists of deionized (DI) water (100 g), Bayderm Finish CTG (870 g, 28% solids) (dispersion of polyurethane, polyacrylic acid and other additives, Lanxess Chemical), Aquaderm additives SF (30 g, 50% solids) (used for soft and waxy-touch silicone emulsion, Lanxess Chemical), EUDERM Black BN pigment dispersion (100 g, 23% solids) (Lanxess Chemical), BINDER LS- 3486-HS (30 g, 51% solids) and RM-2020 thickener in an amount of 0-10 g (to adjust the viscosity of the primer layer to 25 seconds measured by the viscosity cup (Ford #4)) constitute. Next, the coating composition to be tested is adjusted to 20 g/m² (1.8 g/ft² ) Was sprayed onto the obtained primer twice, each time dried at 90°C for 5-10 minutes. After further drying for 2 days at room temperature, the finished leather samples were tested according to the following methods:

Gloss Use a gloss meter (BYK Gardner USA 25 MICRO-TRI-GLOSS meter, catalog number 4520) to measure the gloss (60°) of the finished leather samples. The maximum acceptable gloss (60°) is 2.0.

Wet rubbing fastness test The wet rubbing fastness is measured in accordance with ASTM D 5053-03 (2009) (Standard Test Method for Color Fastness to Crocking Leather). Rubbing fastness (Satra Footware Technical Center Model STM421) was used for wet rubbing fastness testing. Remove the 11.5 cm×3.5 cm sample from the finished skin. In order to determine the finish fastness of the prepared leather samples, a 1.5 cm×1.5 cm felt friction pad was soaked in water and placed on the friction head of the equipment (the total weight of the friction head is 1 kg). To complete the test, insert the leather sample into the rubbing fastness tester and stretch it by 10%, apply a water-soaked felt friction pad to the finished surface of the leather sample, and complete 300 rubbing cycles.

Visually evaluate the finished surface of the leather sample for evaluation. Visually evaluate the pigment transfer of the felt friction pad used for the test compared to the control felt friction pad (unused felt friction pad). The wet rubbing fastness rating is 1-3: 1 It means that the top coating and the bottom coating are completely damaged, so the felt friction pad is black and the damaged bottom coating is attached; 2 It means that the top coating is damaged and the bottom coating is slightly damaged, making the felt friction pad slightly black; 3 means that the top coating and the bottom coating do not show damage, so that the felt friction pad shows no change in color.

Cold Barre flexibility By making the leather sample undergo 30,000 cycles of repeated deflection at -10°C, cold Baricol is measured according to ASTM D6182-00 (2010) (Standard Test Method for Flexibility and Adhesion of Finished Leather) flexibility. After flexing, the leather sample was observed with the naked eye to assess damage to the surface of the leather sample. Finishes showing no cracks or white cracks are evaluated as "pass". Otherwise, cracks or white cracks on the veneer are assessed as "unqualified".

Gakushin rubbing fastness Gakushin rubbing fastness was performed by using GT-7020 from Gotech according to the following procedure: fix the abrasive cloth (#6 tube cloth) to the platen, and fix a piece of the finished leather sample obtained above to the head. Bring the tube cloth into contact with the finished leather sample, and put a total head weight of 1 kilogram (kg) above the leather in place. Start the test, and the platen moves back and forth at a rate of 30 cycles per minute (min), so that the tube cloth can rub on the surface of the leather sample under a pressure of 1 kg. Approximately 9,000 cycles are applied for each leather sample. The leather sample processed in Example 2 (prepared as follows) was set as a standard sample, with a grade of 3, and other leather samples with Gakushin characteristics equivalent to or better than that of Example 2 were rated at 3.

Gakushin characteristics are rated on a scale of 1-3: 1 It means that the top coat and bottom coat of the finished leather sample are completely damaged and the leather substrate is exposed, so the friction area of the tube cloth is black; 2 It means that the top coating of the leather sample is damaged and the bottom coating is partially damaged, so the friction area of the tube cloth is slightly black; 3 It means that the top coat and bottom coat of the finished leather sample do not show damage, so there is no color change in the rubbing area of the tube cloth.

Example (Ex) 1 Polymer Dispersion 1 (PD-1) By combining SLS surfactant (18 g, 28%), deionized water (126 g), MMA (150 g), BA (352 g), RS 123 (5 g) and ALMA (10 g) are mixed together to produce a stable monomer emulsion to prepare a monomer emulsion. Add 91UD (1285 g, 40% solids) and deionized water (395 g) to a 5-liter four-necked round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 28-32°C under a nitrogen atmosphere. The monomer emulsion (322 g) was fed into the flask over 25 minutes and kept for 30 minutes. Mix with EDTA salt (0.039 g) in deionized water (5 g) and FeSO ₄ .7H ₂ O (0.010 g) and hydrogen peroxide in deionized water (5 g). The solution of tertiary butyl oxide (t-BHP) (0.3 g t-BHP (70% solution) in 16 g deionized water) and the solution of Bruggolite FF6 (FF6) (0.2 g FF6 in 16 g deionized water) are both Add to the flask. After 20 minutes, the monomer emulsion (322 g) was fed into the flask over 25 minutes and kept for 30 minutes. Add a solution of t-BHP (0.3 gt-BHP (70% solution) in 16 g deionized water) and a solution of FF6 (0.2 g FF6 in 16 g deionized water) into the flask. At the end of the polymerization, a solution of t-BHP (1.65 g t-BHP (70% solution) in 40 g deionized water) and a solution of FF6 (1 g FF6 in 41 g deionized water) were added to In the flask, followed by a solution of Kathon LXE (2.6 g (1.5% solution) in 15 g of deionized water) to obtain a polymer dispersion.

Example 2 PD-2 The polymer dispersion of Example 2 was prepared as in Example 1, but the monomer emulsion was prepared by mixing SLS surfactant (18 g, 28%), deionized water (123 g), BA (339 g), ALMA ( 10 g), RS 123 (10 g) and MMA (146 g) are mixed together to produce a stable monomer emulsion.

Example 3 PD-3 The polymer dispersion of Example 3 was prepared as in Example 1, but the monomer emulsion was prepared by mixing SLS surfactant (18 g, 28%), deionized water (123 g), BA (329 g), ALMA ( 10 g), RS 123 (25 g) and MMA (141 g) are mixed together to produce a stable monomer emulsion.

Example 4 PD-4 The polymer dispersion of Example 4 was prepared as in Example 1, but the monomer emulsion was prepared by mixing SLS surfactant (18 g, 28%), deionized water (123 g), BA (356 g), ALMA ( 10 g), RS 123 (1 g) and MMA (150 g) are mixed together to produce a stable monomer emulsion.

Example 5 PD-5 The polymer dispersion of Example 5 was prepared as in Example 1, but the monomer emulsion was prepared by mixing SLS surfactant (18 g, 28%), deionized water (123 g), BA (354.5 g), ALMA ( 10 g), RS 123 (2.5 g) and MMA (149 g) are mixed together to produce a stable monomer emulsion.

Example 6 PD-6 By mixing SLS surfactant (11 g, 28%), deionized water (74 g), BA (204 g), ALMA (6 g), RS 123 (6 g) and MMA (88 g) together To produce a stable monomer emulsion to prepare the monomer emulsion. Add 91UD (2269 g, 40% solids) and deionized water (232 g) to a 5-liter four-necked round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 28-32°C under a nitrogen atmosphere. The monomer emulsion (189 g) was fed into the flask over 25 minutes and kept for 30 minutes. FeSO in deionized water (5 g) mixed with EDTA salt (0.023 g) in deionized water (5 g)₄ .7H₂ O (0.006 g), t-BHP solution (0.17 g t-BHP (70% solution) in 9 g deionized water) and FF6 solution (0.12 g FF6 in 9 g deionized water) were added to the flask. After 20 minutes, the monomer emulsion (189 g) was fed into the flask over 25 minutes and kept for 30 minutes. Add a solution of t-BHP (0.17 gt-BHP (70% solution) in 9 g deionized water) and a solution of FF6 (0.12 g FF6 in 9 g deionized water) into the flask. At the end of the polymerization, a solution of t-BHP (0.97 g t-BHP (70% solution) in 23 g deionized water) and a solution of FF6 (0.58 g FF6 in 24 g deionized water) were added to In the flask, a solution of Kathon LXE (1.56 g (1.5% solution) in 9 g deionized water) was followed to obtain a polymer dispersion.

Example 7 PD-7 By mixing SLS surfactant (11 g, 28%), deionized water (74 g), BA (204 g), ALMA (6 g), RS 123 (6 g) and MMA (88 g) together To produce a stable monomer emulsion to prepare the monomer emulsion. Add 91UD (324 g, 40% solids) and deionized water (232 g) to a 5-liter four-necked round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 28-32°C under a nitrogen atmosphere. The monomer emulsion (189 g) was fed into the flask over 25 minutes and kept for 30 minutes. FeSO in deionized water (5 g) mixed with EDTA salt (0.023 g) in deionized water (5 g)₄ .7H₂ O (0.006 g), t-BHP solution (0.17 g t-BHP (70% solution) in 9 g deionized water) and FF6 solution (0.12 g FF6 in 9 g deionized water) were added to the flask. After 20 minutes, the monomer emulsion (189 g) was fed into the flask over 25 minutes and kept for 30 minutes. Add a solution of t-BHP (0.17 gt-BHP (70% solution) in 9 g deionized water) and a solution of FF6 (0.12 g FF6 in 9 g deionized water) into the flask. At the end of the polymerization, a solution of t-BHP (0.97 g t-BHP (70% solution) in 23 g deionized water) and a solution of FF6 (0.58 g FF6 in 24 g deionized water) were added to In the flask, a solution of Kathon LXE (1.56 g (1.5% solution) in 9 g deionized water) was followed to obtain a polymer dispersion.

Example 8 PD-8 By mixing SLS surfactant (11 g, 28%), deionized water (74 g), BA (204 g), ALMA (6 g), RS 123 (6 g) and MMA (88 g) together To produce a stable monomer emulsion to prepare the monomer emulsion. Add 91UD (504 g, 40% solids) and deionized water (232 g) to a 5-liter four-necked round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 28-32°C under a nitrogen atmosphere. The monomer emulsion (189 g) was fed into the flask over 25 minutes and kept for 30 minutes. FeSO in deionized water (5 g) mixed with EDTA salt (0.023 g) in deionized water (5 g)₄ .7H₂ O (0.006 g), t-BHP solution (0.17 g t-BHP (70% solution) in 9 g deionized water) and FF6 solution (0.12 g FF6 in 9 g deionized water) were added to the flask. After 20 minutes, the monomer emulsion (189 g) was fed into the flask over 25 minutes and kept for 30 minutes. Add a solution of t-BHP (0.17 gt-BHP (70% solution) in 9 g deionized water) and a solution of FF6 (0.12 g FF6 in 9 g deionized water) into the flask. At the end of the polymerization, a solution of t-BHP (0.97 g t-BHP (70% solution) in 23 g deionized water) and a solution of FF6 (0.58 g FF6 in 24 g deionized water) were added to In the flask, a solution of Kathon LXE (1.56 g (1.5% solution) in 9 g deionized water) was followed to obtain a polymer dispersion.

Comparison (Comp) Examples 1-5 and 8 The polymer dispersions of Comparative Examples 1-5 and 8 were prepared as in Example 1, but the monomer emulsion used was prepared as follows:

Comparative example 1 CPD-1 By mixing SLS surfactant (18 g, 28%), deionized water (126 g), BA (357 g), ALMA (10 g) and MMA (149 g) together to produce a stable monomer emulsion Prepare monomer emulsion.

Comparative example 2 CPD-2 By mixing SLS surfactant (18 g, 28%), deionized water (123 g), BA (352 g), RS 123 (10 g) and MMA (154 g) together to produce a stable monomer emulsion To prepare the monomer emulsion. Comparative example 3 CPD-3 By mixing SLS surfactant (18 g, 28%), deionized water (126 g), BA (340 g), ALMA (10 g), Silok 3560 (27 g) and MMA (139 g) together To produce a stable monomer emulsion to prepare the monomer emulsion.

Comparative Example 4 CPD-4 was prepared by combining SLS surfactant (18 g, 28%), deionized water (123 g), BA (135 g), ALMA (10 g), RS 123 (10 g) and MMA ( 360 g) are mixed together to produce a stable monomer emulsion to prepare a monomer emulsion.

Comparative Example 5 CPD-5 was combined with SLS surfactant (18 g, 28%), deionized water (146 g), BA (339 g), ALMA (10 g), Silok 3572 (10 g) and MMA ( 146 g) are mixed together to produce a stable monomer emulsion to prepare a monomer emulsion.

Comparative Example 8 CPD-8 By mixing SLS surfactant (11 g, 28%), deionized water (74 g), BA (182 g), ALMA (6 g), RS 123 (45 g) and MMA (70 g) together A stable monomer emulsion is produced to prepare the monomer emulsion.

Comparative Example 6 CPD-6 By combining SLS surfactant (37 g, 28%), DS-4 surfactant (37 g, 22.5%), deionized water (321 g), BA (958 g), RS 123 (9.3 g) and AA (34.8 g) was mixed together to produce a stable monomer emulsion to prepare a monomer emulsion. Put deionized water (1212 g) in a 5-liter four-necked round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 33-37°C under a nitrogen atmosphere. The monomer emulsion (345 g) was fed into the flask over 5 minutes. FeSO in deionized water (4 g)₄ .7H₂ O (0.008 g), ammonium persulfate (APS) solution (0.25 g APS in 24 g deionized water) and Lykopon solution (0.5 g Lykopon in 24 g deionized water) were added to the flask. After 20 minutes, the monomer emulsion (1052 g) and t-BHP solution (0.55 gt-BHP (70% solution) in 8 g deionized water) and sodium formaldehyde sulfoxylate (SSF) solution (0.44 g SSF in 24 g deionized water) into the flask. After 30 minutes, 248 g of MMA was fed into the flask over 5 minutes. A solution of t-BHP (1.13 gt-BHP (70% solution) in 12 g deionized water) and a solution of SSF (0.86 g SSF in 28 g deionized water) were added to the flask. At the end of the polymerization, a solution of t-BHP (1.87 g t-BHP (70% solution) in 28 g deionized water) and a solution of FF6 (1.62 g FF6 in 32 g deionized water) were added to the flask after 30 minutes Then, a solution of SLS (88 g, 28%) and triethylamine (23 g) in 168 g of deionized water, and a solution of Kathon LX (0.35 g (14.2% solution) in 16 g of deionized water) to A polymer dispersion is obtained.

Comparative Example 7 CPD-7 The polymer dispersion of Comparative Example 7 was prepared as in Comparative Example 6, but the monomer emulsion was prepared by combining SLS surfactant (37 g, 28%), DS-4 surfactant (37 g, 22.5%), and Ionized water (321 g), MMA (88 g), BA (953 g), RS 123 (19 g) and AA (35 g) are mixed together to produce a stable monomer emulsion.

Comparative Example 9 CPD-9 By mixing SLS surfactant (11 g, 28%), deionized water (74 g), MMA (88 g), BA (204 g), RS 123 (6 g) and ALMA (6 g) together To produce a stable monomer emulsion to prepare the monomer emulsion. Add 91UD (134 g, 40% solids) and deionized water (232 g) to a 5-liter four-neck round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 28-32°C under a nitrogen atmosphere. The monomer emulsion (194.5 g) was fed into the flask over 25 minutes and kept for 30 minutes. FeSO in deionized water (3 g) mixed with EDTA salt (0.0232 g) in deionized water (3 g)₄ .7H₂ O (0.0058 g), t-BHP solution (0.174 g t-BHP (70% solution) in 9.5 g deionized water) and FF6 solution (0.116 g FF6 in 10 g deionized water) were added to the flask. After 20 minutes, 194.5 g of monomer emulsion was fed into the flask over 25 minutes and kept for 30 minutes. Add a solution of t-BHP (0.17 gt-BHP (70% solution) in 9.3 g deionized water) and a solution of FF6 (0.12 g FF6 in 10 g deionized water) into the flask. At the end of the polymerization, a solution of t-BHP (0.97 g t-BHP (70% solution) in 23 g deionized water) and a solution of FF6 (0.58 g FF6 in 24 g deionized water) were added to In the flask, followed by a solution of Kathon LXE (0.9 g (1.5% solution) in 10 g of deionized water) to obtain a polymer dispersion.

Comparative Example 10 CPD-10 By combining SLS surfactant (22 g, 28%), deionized water (234 g), BA (590 g), MMA (241 g), RS 123 (18 g), AA (18 g), MAA ( 9 g) and ALMA (17.8 g) are mixed together to produce a stable monomer emulsion to prepare a monomer emulsion. Put deionized water (550 g) and SLS (9 g, 28%) in a 5-liter four-necked round bottom flask equipped with a paddle stirrer, thermocouple, nitrogen inlet, and reflux condenser, and start stirring. The contents of the flask were heated to 78-82°C under a nitrogen atmosphere. The monomer emulsion (92 g), ammonium bicarbonate solution (4.7 g in 41 g deionized water) and APS solution (4 g in 13 g deionized water) were fed into the flask over 3 minutes. After 65 minutes, feed the monomer emulsion (1057.8 g) and t-BHP solution (0.63 gt-BHP (70% solution) in 8 g deionized water) and FF6 solution (0.27 g FF6 in 8 g deionized water). Into the flask. At the end of the polymerization, mix with EDTA salt (0.0038 g) in deionized water (3 g) and FeSO in deionized water (3 g)₄ .7H₂ O (0.0021 g), t-BHP solution (0.11 g t-BHP (70% solution) in 8 g deionized water) and FF6 solution (0.05 g FF6 in 8 g deionized water) are added to the flask, Subsequent ammonia solution (6 g (25% solution) in 10 g deionized water), Kathon LXE solution (2 g (1.5% solution) in 10 g deionized water) and 91UD (2225 g, 40% solids), To obtain a polymer dispersion.

Comparative Example 11 CPD-11 The polymer dispersion of Comparative Example 11 was prepared as in Comparative Example 9, but the monomer emulsion was prepared by mixing SLS surfactant (11 g, 28%), deionized water (74 g), BA (204 g), MMA (88 g), RS 123 (6 g) and ALMA (6 g) are mixed together to produce a stable monomer emulsion; and to 5 liters equipped with paddle stirrer, thermocouple, nitrogen inlet and reflux condenser Add 91UD (84 g, 40% solids) and deionized water (232 g) to the four-neck round bottom flask, and start stirring.

The characteristics of the polymer dispersion obtained above are given in Table 1. As shown in Table 1, compared with other polymer dispersions, the polymer dispersions of Comparative Example 8 (0.69%) and Comparative Example 11 (0.85%) exhibited much higher coagulum content. Table 1. Properties of polymer dispersion Polymer dispersion Tg (℃) ¹ Particle size, nm pH solid Viscosity (centipoise) ² Condensate content Example 1 -19 65 8.0 40% 49 0.04% Example 2 -10.7 74 8.1 40.2% 47 0.04% Example 3 -14 72 7.84 39.7% 56 ＜0.01% Example 4 -11.9 77 8.0 40.62% 77 0.003% Example 5 -10.9 72 7.99 40.8% 80 0.0007% Example 6 -22.6 69 8.07 39.9% 275 0 Example 7 -16.4 86 7.66 39.35% 36 0.25% Example 8 -15.3 78 7.81 39.51% 38 0.06% Comparative example 1 NA 71 8.0 40% 42 ＜0.01% Comparative example 2 NA 69 7.98 40.1% 55 ＜0.01% Comparative example 3 NA 71 8.11 40.3% 55 ＜0.01% Comparative example 4 47.3 74 7.95 39.7% 58 ＜0.01% Comparative example 5 NA 72 7.83 39.8% 59 ＜0.01% Comparative example 6 NA 105 7.45 36.5% 65 0.035% Comparative example 7 NA 109 7.45 36.7% 59 0.015% Comparative example 8 NA 70 8.45 39.7% 60 0.69% Comparative example 9 NA 104 7.4 40.1% 32 0.11% Comparative example 10 NA 114 8.0 40.1% 160.5 0.05% Comparative example 11 NA 105 7.21 40.52% 36 0.85% ¹ The Tg of the polymer particles in the obtained polymer dispersion is measured by DSC as described above. ² by lines viscosity at 25 deg.] C Brookfield at 60 rpm (Brookfield) # 1 measurements.

Coating composition Add Aquaderm Fluid H leveling agent (16 g) to the deionized water in the container and stir for a few minutes. Under stirring (200 revolutions per minute (rpm)), OPTI-MATT UD-4 matting agent (426.2 g) and ROSIILK 2229 feel modifier (60 g) were sequentially added to the container, and then the prepared aqueous polymer was added Dispersion (213.1 g). Then BINDER LS-3486-HS (128 g) was added to the container under stirring (200 rpm) to form a mixture. Finally, add ACRYSOL RM-819W thickener (3.3 g) to the mixture to adjust the viscosity, ideally as measured by using a viscosity test cup (Ford #4) for 24 to 25 seconds as the target to obtain Coating composition (Coating Examples 1-8 and Comparative Coating Examples 1-11). The type of polymer dispersion used to prepare each coating composition is given in Table 2. These coating compositions on leather were evaluated according to the test method described above, and the characteristics are given in Table 2.

As shown in Table 2, the polymer dispersion (CPD-1) of the structural unit without RS 123 additive provides poor wet rubbing fastness and cold Barre flexibility performance. Polymer dispersions (CPD-3 and CPD-5) containing structural units of other types of reactive polysiloxanes provide poor Gakushin performance and/or wet rubbing fastness and cold Barre flexibility performance. The polymer dispersion (CPD-2) without the structural unit of ALMA provides poor Gakushin and wet rubbing fastness as well as cold Barre flexibility performance. The polymer dispersion (CPD-4) with too high Tg provides leather with poor Gakushin rubbing fastness and cold barre flexibility performance. The polymer dispersions (CPD-6 and CPD-7) prepared in the absence of PUD provide leather with poor cold barre flexibility performance. The polymer dispersion containing 15% RS 123 structural unit (CPD-8) and the blend of acrylic polymer and PUD (CPD-10) all provide poor Gakushin rubbing fastness and cold Barre flexibility performance Of leather. A polymer dispersion containing 15% polyurethane (CPD-9) or a polymer dispersion containing 10% polyurethane (CPD-11) provides poor Gakushin rubbing fastness performance. In contrast, the polymer dispersions of Examples 1-8 all provide coatings with satisfactory wet rubbing fastness, cold Barley flexibility, Gakushin rubbing fastness and gloss. Table 2. Characteristics of coating composition (on leather substrate) Coating composition Type of polymer dispersion Color fastness to wet rubbing Cold Barre flexibility Glossiness (60º) Gakushin rubbing fastness Coating example 1 PD-1 (Example 1) 3 qualified 1.2 3 Coating example 2 PD-2 (Example 2) 3 qualified 1.1 3 Coating example 3 PD-3 (Example 3) 3 qualified 1.0 3 Coating example 4 PD-4 (Example 4) 3 qualified 1.1 3 Coating example 5 PD-5 (Example 5) 3 qualified 1.2 3 Coating example 6 PD-6 (Example 6) 3 qualified 1.0 3 Coating example 7 PD-7 (Example 7) 3 qualified 1.0 3 Coating example 8 PD-8 (Example 8) 3 qualified 1.0 3 Comparative coating example 1 CPD-1 (Comparative Example 1) 1 Unqualified 1.4 3 Comparative coating example 2 CPD-2 (Comparative Example 2) 1 Unqualified 1.6 1 Comparative coating example 3 CPD-3 (Comparative Example 3) 2 Unqualified 1.0 1 Comparative coating example 4 CPD-4 (Comparative Example 4) 3 Unqualified 1.6 1 Comparative coating example 5 CPD-5 (Comparative Example 5) 3 qualified 1.5 2 Comparative coating example 6 CPD-6 (Comparative Example 6) 3 Unqualified 1.1 3 Comparative coating example 7 CPD-7 (Comparative Example 7) 3 Unqualified 1.1 3 Comparative coating example 8 CPD-8 (Comparative Example 8) 3 Unqualified 1.2 2 Comparative coating example 9 CPD-9 (Comparative Example 9) 3 qualified 1.3 2 Comparative coating example 10 CPD-10 (Comparative Example 10) 3 Unqualified 1.4 2 Comparative coating example 11 CPD-11 (Comparative Example 11) 3 qualified 1.2 2

no

no

Claims (11)

An aqueous dispersion of polymer particles, comprising acrylic polymer and polyurethane, wherein based on the weight of the acrylic polymer, the acrylic polymer contains: 0.1% to 10% by weight of formula (I) The structural unit of (meth)acrylate functional silicone,

(I) Where R ₁ is a linear or branched C ₁ -C ₁₀ alkylene, R ₂ is hydrogen or methyl, n is 0 to 100, p is 0 to 100, and the restriction is that n+p is 5 To 100; 0.1% to 8% by weight of structural units of polyethylenically unsaturated monomers; and structural units of monoethylenically unsaturated nonionic monomers; wherein the Tg of the polymer particles is 0°C or more Low, and the weight ratio of polyurethane to acrylic polymer in the polymer particles is 20:80 to 99:1. The aqueous dispersion of claim 1, wherein R ₁ in formula (I) is a linear or branched C ₁ -C ₆ alkylene group, and n+p is in the range of 8 to 50. According to the aqueous dispersion of claim 1, wherein, based on the weight of the acrylic polymer, the acrylic polymer contains 0.2% to 8% by weight of the structural unit of the (meth)acrylate functional silicone. The aqueous dispersion of claim 1, wherein the polymer particles are obtained by forming the acrylic polymer in an aqueous medium by emulsion polymerization in the presence of the polyurethane. Such as the aqueous dispersion of claim 1, wherein the polyethylenically unsaturated monosystem is selected from the group consisting of allyl (meth)acrylate, hexanediol di(meth)acrylate, ethylene glycol di (Meth)acrylate, neopentyl glycol di(meth)acrylate, butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, divinylbenzene, allyl Alkyl (meth)acrylamide, allyloxyethyl (meth)acrylate, crotonyl (meth)acrylate, diallyl maleate, and mixtures thereof. Such as the aqueous dispersion of claim 1, wherein the monoethylenically unsaturated nonionic monosystem is selected from the group consisting of butyl acrylate, butyl methacrylate, methyl methacrylate, methyl acrylate, acrylic acid Ethyl, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and mixtures thereof. Such as the aqueous dispersion of claim 1, wherein the weight ratio of polyurethane to acrylic polymer in the polymer particles is 30:70 to 85:15. Such as the aqueous dispersion of claim 1, wherein the particle size of the polymer particles is 30 nm to 800 nm. The aqueous dispersion of claim 1, wherein, based on the weight of the acrylic polymer, the acrylic polymer contains: 0.2% to 8% by weight of the structural unit of the (meth)acrylate functional silicone, 0.2% by weight % To 8% by weight of the structural units of the polyethylenically unsaturated monomer and 84% to 99.6% by weight of the structural units of the monoethylenically unsaturated nonionic monomer. A method for preparing an aqueous dispersion as claimed in any one of claims 1 to 9, which comprises forming an acrylic polymer in an aqueous medium by emulsion polymerization in the presence of polyurethane to obtain an acrylic polymer And the aqueous dispersion of polyurethane polymer particles, wherein, based on the weight of the acrylic polymer, the acrylic polymer contains: 0.1% to 10% by weight of (meth) of formula (I) The structural unit of acrylate functional silicone,

(I) Where R ₁ is a linear or branched C ₁ -C ₁₀ alkylene, R ₂ is hydrogen or methyl, n is 0 to 100, p is 0 to 100, and the restriction is that n+p is 5 To 100; 0.1% to 8% by weight of structural units of polyethylenically unsaturated monomers and structural units of monoethylenically unsaturated nonionic monomers; wherein the Tg of the polymer particles is 0°C or more Low, and the weight ratio of polyurethane to acrylic polymer in the polymer particles is 20:80 to 99:1. An aqueous coating composition comprising the aqueous dispersion as claimed in any one of claims 1 to 9, which further comprises a matting agent, an additional polyurethane dispersion, a feel modifier, a thickening agent, and a leveling agent Agent, crosslinking agent or mixtures thereof.