JP7468407B2 - Transparent coating composition, transparent coating film, and article having said film - Google Patents

Description

The present invention relates to a coating composition containing a silicone acrylic copolymer resin, a coating film obtained by drying the composition, and an article having the coating. More specifically, the present invention relates to a coating composition, a coating film, and an article having the coating that can impart excellent touch, gloss, and high transparency by applying the composition to the surface of a substrate such as leather or resin, and that does not impair the appearance of the article having the coating film even when the article is pulled.

Conventionally, silicone resins have been used to impart sliding properties to substrates such as leather and resins. A known method for improving the abrasion resistance and lubricity of leather is to knead silicone components such as silicone oil or silicone powder into the resin when manufacturing the leather. For example, JP 2007-138326 A (Patent Document 1) successfully improved abrasion resistance in a synthetic leather manufactured by kneading acrylic-silicone copolymer particles into a urethane elastomer. However, in this case, the manufacturing process becomes complicated because the powder is kneaded into the resin. Also, in order to achieve abrasion resistance, it is necessary to increase the amount of acrylic-silicone copolymer particles added.

To solve this problem, there is a method of coating the surface of leather such as natural leather or synthetic leather with a resin or the like. Japanese Patent Application Laid-Open No. 2007-314919 (Patent Document 2) discloses that abrasion resistance is improved by coating artificial leather with a surface finishing agent made of an aqueous polyurethane resin to which a crosslinking agent and a polyether-modified silicone have been added. However, in this case, the hydrophilicity of the surface finishing agent becomes strong, and there is a concern that the stain resistance of the leather surface will be lost, for example, when dark-colored beverages or liquids such as coffee are attached, the color of the liquid will transfer to the leather, or when clothing is rubbed against the leather, the color of the fibers will transfer to the leather.

Furthermore, coating the leather surface with resin or the like is also known as a method for improving the stain resistance of leather. JP 2010-241963 A (Patent Document 3) discloses blending acrylic resin, acrylic silica resin, acrylic polysiloxane resin, and silicone-based tactile agent, etc., and applying the mixture to natural leather. JP 2008-308785 A (Patent Document 4) discloses forming a silicone resin film on the surface of synthetic leather made of urethane resin. However, water-based coating agents have insufficient water resistance and stain resistance.

International Publication WO 2019/244321 (Patent Document 5) discloses synthetic leather coated with a treatment liquid in which a base resin and a silicone acrylic resin are dissolved in an organic solvent. Compared to conventional methods, the stain resistance is improved, but the coating agent is not transparent in this method, so there is a problem that the appearance of the substrate is impaired when a dark-colored substrate is used. There is also a problem that the coated leather turns white when pulled, so there is room for improvement.

JP 2007-138326 A JP 2007-314919 A JP 2010-241963 A JP 2008-308785 A International Publication No. 2019/244321

The present invention has been made in consideration of the above circumstances, and aims to provide a coating composition that has excellent touch, gloss, and high transparency, a coating film that does not whiten even when pulled, and an article having the coating.

As a result of intensive research into achieving the above object, the present inventors have discovered that in a coating composition containing a silicone acrylic copolymer resin, by setting the range of grafting points to be grafted to an organopolysiloxane (silicone resin) within a predetermined range and dissolving the silicone acrylic copolymer resin obtained by graft polymerizing an acrylic monomer in an organic solvent, the coating composition has excellent touch, gloss, and high transparency, and a coating film made of the coating composition and an article having the coating do not whiten even when pulled, which has led to the present invention.

（式中、Ｒ¹は、互いに独立に、置換もしくは非置換の炭素数１～２０の１価炭化水素基であり、Ｒ²は、互いに独立に、炭素数２～６のアルケニル基、又は、炭素原子に結合する水素原子の一部がメルカプト基、アクリロキシ基もしくはメタクリロキシ基で置換されている炭素数１～６のアルキル基であり、Ｘは互いに独立に、置換もしくは非置換の炭素数１～２０の１価炭化水素基、炭素数１～２０のアルコキシ基、又はヒドロキシル基であり、Ｙは互いに独立に、上記Ｘで定義される基、又は－［Ｏ－Ｓｉ（Ｘ）₂］_g－Ｘで示される基であり、ｇは１～２００の正数であり、Ｘ及びＹで示される基のうち少なくとも２個はヒドロキシル基であり、Ｚは互いに独立に、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基又はヒドロキシル基であり、ａは０以上の正数であり、ａ～ｄの合計数に対して、ｂは９０．００％以上９９．９０％未満となる正数であり、ｃは０．０４％超０．７０％以下となる正数であり、及び、ｄは０．０１％以上０．３０％以下となる正数であり、上記各シロキサン単位の結合順序は制限されるものでない。）
２．上記透明性コーティング組成物を基材に塗工し、５～５０μｍの塗膜を形成するときの、該塗膜を有する基材のヘイズ値Ｈ₁と、塗膜を有しない基材のヘイズ値Ｈ₀との差（Ｈ₁－Ｈ₀）が５．０以下である上記１記載の透明性コーティング組成物。
３．上記式（１）で示されるオルガノポリシロキサンにおいて、ａの値が０～１，０００の正数であり、ｂの値が１００～１５，０００の正数であり、ｃの値が１～１０の正数であり、ｄの値が１～２の正数である上記１又は２記載の透明性コーティング組成物。
４．上記式（１）で示されるポリオルガノシロキサンが、環状オルガノシロキサン、α，ω－ジヒドロキシシロキサンオリゴマー、α，ω－ジアルコキシシロキサンオリゴマー又はアルコキシシランと、下記一般式（２）で示されるシランカップリング剤との重合物である上記１～３のいずれかに記載のコーティング組成物。
Ｒ³ _(4-e-f)Ｒ⁴ _fＳｉ（ＯＲ⁵）_e （２）
（式中、Ｒ³はメルカプト基、アクリロキシ基もしくはメタクリロキシ基置換の炭素数１～６のアルキル基であり、Ｒ⁴は炭素数１～４のアルキル基であり、Ｒ⁵は炭素数１～４のアルキル基であり、ｅは２又は３、ｆは０又は１で、ｅ＋ｆは２又は３である。）
５．上記の環状オルガノシロキサン、α，ω－ジヒドロキシシロキサンオリゴマー、α，ω－ジアルコキシシロキサンオリゴマー又はアルコキシシラン１００質量部に対して、上記式（２）で示されるシランカップリング剤を０．１～１．５質量部を重合させて上記重合物を得る上記４記載の透明性コーティング組成物。
６．上記式（１）で示されるオルガノポリシロキサンの重合体１モルあたりの架橋点が２～１０点である上記１～５のいずれかに記載の透明性コーティング組成物。
７．上記（ａ１）成分のポリオルガノシロキサンの粘度測定による重量平均分子量（Ｍｗ）が５～１００万である上記１～６のいずれかに記載の透明性コーティング組成物。
８．上記一般式（１）で示されるオルガノポリシロキサンのａの値が０である上記１～７のいずれかに記載の透明性コーティング組成物。
９．上記（ａ２）成分のアクリル系単量体のガラス転移温度（Ｔｇ）が６０℃以上である上記１～８のいずれかに記載の透明性コーティング組成物。
１０．上記（Ａ）シリコーンアクリル共重合樹脂の固形分換算の配合量と上記（Ｂ）有機溶剤との配合量が、重量比で（Ａ）：（Ｂ）＝０．１：９９．９～４０：６０である上記１～９のいずれかに記載の透明性コーティング組成物。
１１．上記１～１０のいずれかに記載のコーティング組成物を乾燥してなるコーティング被膜。
１２．上記１１記載のコーティング被膜を有する合成皮革または樹脂物品。 Accordingly, the present invention provides a coating composition containing a silicone acrylic copolymer resin, a coating film obtained by drying the composition, and an article having the coating film.
1. A transparent coating composition comprising: (A) (a1) a silicone acrylic copolymer resin, which is a polymer containing 50 to 70 parts by mass of an organopolysiloxane represented by the following general formula (1) and (a2) 30 to 50 parts by mass of an acrylic acid ester monomer and/or a methacrylic acid ester monomer; and (B) one or more organic solvents selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene, xylene, ethyl acetate, and propylene glycol monoethyl ether acetate .

(In the formula, R ¹ 's are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R ² 's are each independently an alkenyl group having 2 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms in which some of the hydrogen atoms bonded to the carbon atoms are substituted with mercapto groups, acryloxy groups, or methacryloxy groups, X's are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and Y's are each independently a group defined for X above, or -[O-Si(X) ₂ ] _g -X, g is a positive number from 1 to 200, at least two of the groups represented by X and Y are hydroxyl groups, Z is each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxyl group, a is a positive number of 0 or more, b is a positive number that is 90.00% or more and less than 99.90% with respect to the total number of a to d, c is a positive number that is more than 0.04% and 0.70% or less, and d is a positive number that is 0.01% or more and 0.30% or less, and the bonding order of the above siloxane units is not limited.
2. The transparent coating composition according to claim 1 , wherein when the transparent coating composition is applied to a substrate to form a coating film having a thickness of 5 to 50 μm, the difference (H ₁ -H ₀ ) between the haze value H ₁ of the substrate having the coating film and the haze value H ₀ of the substrate not having the coating film is 5.0 or less.
3. The transparent coating composition according to 1 or 2 above, wherein in the organopolysiloxane represented by the formula (1), the value of a is a positive number from 0 to 1,000, the value of b is a positive number from 100 to 15,000, the value of c is a positive number from 1 to 10, and the value of d is a positive number from 1 to 2 .
4. The coating composition according to any one of 1 to 3 above, wherein the polyorganosiloxane represented by the formula (1) is a polymer of a cyclic organosiloxane, an α,ω-dihydroxysiloxane oligomer, an α,ω-dialkoxysiloxane oligomer, or an alkoxysilane and a silane coupling agent represented by the following general formula ( 2 ):
R ³ _(4-ef) R ⁴ _f Si (OR ⁵ ) _e (2)
(In the formula, ^R3 is a mercapto, acryloxy or methacryloxy substituted alkyl group having 1 to 6 carbon atoms, ^R4 is an alkyl group having 1 to 4 carbon atoms, ^R5 is an alkyl group having 1 to 4 carbon atoms, e is 2 or 3, f is 0 or 1, and e+f is 2 or 3.)
5. The transparent coating composition according to 4 above, wherein 0.1 to 1.5 parts by mass of a silane coupling agent represented by the above formula (2) is polymerized with 100 parts by mass of the above cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α, ω- dialkoxysiloxane oligomer, or alkoxysilane to obtain the above polymer.
6. The transparent coating composition according to any one of 1 to 5 above, wherein the organopolysiloxane polymer represented by the formula (1) has 2 to 10 crosslinking points per 1 mole.
7. The transparent coating composition according to any one of 1 to 6 above, wherein the polyorganosiloxane of component (a1) has a weight average molecular weight (Mw) of 50,000 to 1,000,000 as determined by viscosity measurement.
8. The transparent coating composition according to any one of 1 to 7 above, wherein the value of a in the organopolysiloxane represented by the general formula (1) is 0.
9. The transparent coating composition according to any one of 1 to 8 above, wherein the glass transition temperature (Tg) of the acrylic monomer of component (a2) is 60° C. or higher.
10. The transparent coating composition according to any one of 1 to 9 above, wherein the blending amount of the silicone acrylic copolymer resin (A) calculated on solid content and the blending amount of the organic solvent (B) are in a weight ratio of (A):(B)=0.1: 99.9 to 40:60.
11. A coating film obtained by drying the coating composition according to any one of 1 to 10 above.
12. A synthetic leather or resin article having the coating film according to 11 above.

The coating composition of the present invention is a coating composition that can impart excellent tactile sensation and high transparency when used as a coating film by dissolving a specific silicone acrylic copolymer resin in an organic solvent, and does not cause whitening or impair the appearance even when an article having the coating film is pulled.

The coating composition of the present invention contains (A) a specific silicone acrylic copolymer resin and (B) an organic solvent. Each component is described in detail below.

(A) Silicone acrylic copolymer resin is a polymer of an organopolysiloxane represented by a specific formula and an acrylic monomer, and is preferably obtained by emulsion graft polymerization of a mixture of (a1) an organopolysiloxane represented by the following general formula (1) and (a2) an acrylic monomer.

（式中、Ｒ¹は、互いに独立に、置換もしくは非置換の炭素数１～２０の１価炭化水素基であり、Ｒ²は、互いに独立に、炭素数２～６のアルケニル基、又は、炭素原子に結合する水素原子の一部がメルカプト基、アクリロキシ基もしくはメタクリロキシ基で置換されている炭素数１～６のアルキル基であり、Ｘは互いに独立に、置換もしくは非置換の炭素数１～２０の１価炭化水素基、炭素数１～２０のアルコキシ基、又はヒドロキシル基であり、Ｙは互いに独立に、上記Ｘで定義される基、又は－［Ｏ－Ｓｉ（Ｘ）₂］_g－Ｘで示される基であり、ｇは１～２００の正数であり、Ｘ及びＹで示される基のうち少なくとも２個はヒドロキシル基であり、Ｚは互いに独立に、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基又はヒドロキシル基であり、ａは０以上の正数であり、ａ～ｄの合計数に対して、ｂは９０．００％以上９９．９０％未満となる正数であり、ｃは０．０４％超０．７０％以下となる正数であり、及び、ｄは０．０１％以上０．３０％以下となる正数であり、上記各シロキサン単位の結合順序は制限されるものでない。） Here, (a1) organopolysiloxane is represented by the following general formula (1).

(In the formula, R ¹ 's are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R ² 's are each independently an alkenyl group having 2 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms in which some of the hydrogen atoms bonded to the carbon atoms are substituted with mercapto groups, acryloxy groups, or methacryloxy groups, X's are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and Y's are each independently a group defined for X above, or -[O-Si(X) ₂ ] _g -X, g is a positive number from 1 to 200, at least two of the groups represented by X and Y are hydroxyl groups, Z is each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxyl group, a is a positive number of 0 or more, b is a positive number that is 90.00% or more and less than 99.90% with respect to the total number of a to d, c is a positive number that is more than 0.04% and 0.70% or less, and d is a positive number that is 0.01% or more and 0.30% or less, and the bonding order of the above siloxane units is not limited.

Here, R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and specifically includes alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl groups; alkenyl groups such as vinyl and allyl groups; aryl groups such as phenyl, tolyl, and naphthyl groups; Examples of such groups include alkenylaryl groups such as phenyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, alkenylaralkyl groups such as vinylbenzyl group, vinylphenylpropyl group, and the like, and groups in which some or all of the hydrogen atoms are substituted with halogen atoms such as fluorine, bromine, chlorine, etc., acryloxy group, methacryloxy group, carboxyl group, alkoxy group, alkenyloxy group, amino group, alkyl or alkoxy- or (meth)acryloxy-substituted amino group, etc. ^R1 is preferably a methyl group.

^R2 is a mercapto, acryloxy or methacryloxy substituted alkyl group having 1 to 6 carbon atoms. Specifically, mercaptopropyl, acryloxypropyl, methacryloxypropyl and the like are preferred.

X is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, or hydroxyl group, and examples of the unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms include the same as those exemplified for R ¹ , and specific examples of the alkoxy group having 1 to 20 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a decyloxy group, a tetradecyloxy group, etc. X is preferably a hydroxyl group, a methyl group, a butyl group, or a phenyl group.

Y is X or the same or different group represented by --[O--Si(X) ₂ ] _d --X, where d is a positive number of 0 to 1,000, preferably 0 to 200. In the present invention, from the viewpoint of crosslinkability, one molecule, i.e., the above-mentioned X and Y, has at least two, preferably 2 to 4 hydroxyl groups, and it is preferable that they are present at both ends.

Z is an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxyl group, preferably a hydroxyl group or a methyl group.

In the above formula (1), a is a positive number equal to or greater than 0, preferably equal to or greater than 0% and equal to or less than 9.00% of the total number of a through d, more preferably equal to or greater than 0% and equal to or less than 0.10%, and even more preferably equal to 0.

b is a positive number that is 90% or more and less than 99.90% of the total number of a through d, preferably a positive number that is 95.00-99.90%, and more preferably a positive number that is 99.00-99.90%.

c is a positive number that is more than 0.04% and not more than 0.70% of the total number of a to d, preferably a positive number that is 0.05 to 0.50%, and more preferably a positive number that is 0.06 to 0.30%. If the value of c is 0.04% or less, the copolymerizability of (a1) organopolysiloxane and (a2) acrylic monomer decreases, causing a problem of the coating film becoming white due to a decrease in the transparency of the coating film, and also causing a problem of poor dispersion of the silicone component in organic solvents such as N,N-dimethylformamide. On the other hand, if the value of c exceeds 0.70%, there are problems such as a deterioration in the slipperiness of the coating film and a decrease in solubility in solvents. That is, in the present invention, high transparency can be imparted to the coating film by designing c to be within the above range, that is, by designing the grafting points in the silicone chain to be within the above range.

d is a positive number that is 0.01% or more and 0.30% or less, preferably 0.01% to 0.20%, and more preferably 0.02% to 0.10%, relative to the total number of a to d.

In the above organopolysiloxane, ^R2 is a group that reacts with the (meth)acrylic acid ester described below. The organopolysiloxane having the unit represented by the above formula (1) may be branched, and may contain T units (RSiO3 _/2 ) and Q units (SiO4 _/2 ) in addition to the above D units and M units, as long as the effects of the present invention are not impaired. A linear organopolysiloxane consisting only of the above D units and M units is preferred.

If a is greater than 1,000, the lubricating properties of the resulting cured product may be insufficient. Therefore, a is a positive number from 0 to 1,000, preferably a positive number from 0 to 200, and more preferably 0.
If b is less than 100, the flexibility of the cured product will be poor, and if it is more than 15,000, the slipperiness obtained will decrease due to an increase in resistance caused by the viscosity. Therefore, b is a positive number from 100 to 15,000, further from 100 to 10,000, and preferably from 1,700 to 4,400.
c is a positive number from 1 to 10, preferably from 2 to 5. If this value is less than 1, the copolymerizability of (a1) organopolysiloxane and (a2) acrylic monomer decreases, resulting in a decrease in the transparency of the coating film, which causes the coating film to whiten, and the dispersion of the silicone component in an organic solvent such as N,N-dimethylformamide may become poor. In addition, crosslinking between (a2) acrylic monomers becomes difficult to occur, which may cause a problem of whitening when the coating film is stretched. If it exceeds 10, the crosslink density between (a2) acrylic monomer compositions increases, which may cause a decrease in dispersibility in the solvent and a decrease in the sliding component, resulting in a deterioration in slipperiness. The arrangement of the repeating units may be block or random.

Such organopolysiloxane (a1) is preferably used in the form of an emulsion, and may be a commercially available product or may be synthesized. When synthesizing, it can be carried out by a known emulsion polymerization method, and can be easily synthesized by emulsifying and dispersing, for example, a cyclic organosiloxane that may have a halogen atom such as a fluorine atom, a (meth)acryloxy group, a carboxyl group, an alkoxy group, an alkenyloxy group, a hydroxyl group, an amino group, or the like, an α,ω-dihydroxysiloxane oligomer, an α,ω-dialkoxysiloxane oligomer, an alkoxysilane, or the like, and a silane coupling agent represented by the following general formula (2) in water using a surfactant, and then adding a catalyst such as an acid as necessary to carry out a polymerization reaction.
R ³ _(4-ef) R ⁴ _f Si (OR ⁵ ) _e (2)
(In the formula, ^R3 is a mercapto, acryloxy or methacryloxy substituted alkyl group having 1 to 6 carbon atoms, ^R4 is an alkyl group having 1 to 4 carbon atoms, ^R5 is an alkyl group having 1 to 4 carbon atoms, e is 2 or 3, f is 0 or 1, and e+f is 2 or 3.)

Specific examples of the cyclic organosiloxane include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), 1,1-diethylhexamethylcyclotetrasiloxane, phenylheptamethylcyclotetrasiloxane, 1,1-diphenylhexamethylcyclotetrasiloxane, 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5,7-tetracyclohexyltetramethylcyclotetrasiloxane, tris(3,3,3-trifluoropropyl)trimethylcyclotrisiloxane, 1,3,5,7-tetra(3-methacryloxypropyl)tetramethylcyclotetrasiloxane, and 1,3,5,7-tetra(3-methacryloxypropyl)tetramethylcyclotetrasiloxane. Examples of the tetramethylcyclotetrasiloxane include 1,3,5,7-tetra(3-acryloxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(3-carboxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(3-vinyloxypropyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(p-vinylphenyl)tetramethylcyclotetrasiloxane, 1,3,5,7-tetra[3-(p-vinylphenyl)propyl]tetramethylcyclotetrasiloxane, 1,3,5,7-tetra(N-acryloyl-N-methyl-3-aminopropyl)tetramethylcyclotetrasiloxane, and 1,3,5,7-tetra(N,N-bis(lauroyl)-3-aminopropyl)tetramethylcyclotetrasiloxane. Octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane are preferably used.

Specific examples of silane coupling agents include acrylic silanes such as γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropyltripropoxysilane, γ-(meth)acryloxypropyltriisopropoxysilane, γ-(meth)acryloxypropyltributoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxypropylmethyldiisopropoxysilane, and γ-(meth)acryloxypropylmethyldibutoxysilane; mercaptosilanes such as γ-mercaptopropylmethyldimethoxysilane and γ-mercaptopropyltrimethoxysilane; and oligomers obtained by condensation polymerization of these may be preferably used because they suppress the generation of alcohol. Here, (meth)acryloxy refers to acryloxy or methacryloxy.

These silane coupling agents are preferably used in an amount of 0.1 to 1.5 parts by mass, and more preferably 0.1 to 1.0 part by mass, per 100 parts by mass of cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, or alkoxysilane.

By copolymerizing the silane coupling agent, an organopolysiloxane having the siloxane unit c in formula (1) is obtained, and the effect of grafting the monomer of component (a2) is obtained.

In the above reaction, a known polymerization catalyst may be used as the catalyst for polymerization. Among them, strong acids are preferred, such as hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, citric acid, lactic acid, and ascorbic acid. Dodecylbenzenesulfonic acid, which has emulsifying ability, is preferred.
The amount of the acid catalyst used is preferably 0.01 to 10 parts by mass, and more preferably 0.2 to 2 parts by mass, per 100 parts by mass of the cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, or alkoxysilane.

The surfactant used in the polymerization may be an anionic surfactant such as sodium lauryl sulfate, sodium laureth sulfate, N-acylamino acid salts, N-acyltaurate salts, aliphatic soaps, or alkyl phosphates, among which those that are easily soluble in water and do not have a polyethylene oxide chain are preferred. More preferred are N-acylamino acid salts, N-acyltaurate salts, aliphatic soaps, or alkyl phosphates, and particularly preferred are sodium lauroyl methyl taurate, sodium myristoyl methyl taurate, or sodium lauryl sulfate.
The amount of the anionic surfactant used is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α,ω-dialkoxysiloxane oligomer, or alkoxysilane.

The polymerization temperature is preferably 50 to 75°C, and the polymerization time is preferably 10 hours or more, more preferably 15 hours or more. Furthermore, it is particularly preferable to age the polymerized solution at 5 to 30°C for 10 hours or more after polymerization. The pH of the resulting polymerized solution is preferably 6 to 8.

The weight average molecular weight of the resulting organopolysiloxane (a1), as determined by viscosity measurement, is preferably from 50,000 to 1,000,000, and more preferably from 100,000 to 500,000.
By adjusting the weight average molecular weight to this range, a coating agent that imparts the excellent slipperiness characteristic of silicone can be obtained. Note that, in the present invention, the weight average molecular weight (Mw) determined by viscosity measurement can be calculated from the specific viscosity ηsp (25°C) of a toluene solution of the organopolysiloxane at a concentration of 1 g/100 ml.
ηsp=(η/η0)-1
(η0: viscosity of toluene η: viscosity of solution)
ηsp = [η] + 0.3 [η] ²
[η] = 2.15 × 10 ⁻⁴ M ^0.65
Specifically, 20 g of the emulsion is mixed with 20 g of IPA (isopropyl alcohol), the emulsion is broken, the IPA is discarded, and the remaining rubber-like organopolysiloxane is dried at 105°C for 3 hours. This is made into a toluene solution of organopolysiloxane with a concentration of 1 g/100 ml, and the viscosity is measured at 25°C using an Ubbelohde viscometer. The molecular weight can be calculated by substituting the viscosity into the above formula (References: Nakamuta, Nikka, 77 858 [1956], Doklady Akad. Nauk. USSR 89 65 [1953]).

In the above reaction, for example, when octamethyltetrasiloxane is used as the cyclic organosiloxane and γ-methacryloxypropylmethyldimethoxysilane is used as the silane coupling agent, the reaction proceeds as follows.

In the present invention, specific examples of (a2) acrylic acid ester monomers and/or methacrylic acid ester monomers (hereinafter sometimes referred to as "acrylic components") include methyl methacrylate, ethyl methacrylate, butyl methacrylate, allyl methacrylate, t-butyl methacrylate, glycidyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, stearyl methacrylate, behenyl methacrylate, ureido methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, t-butyl acrylate, glycidyl acrylate, isodecyl acrylate, hexyl acrylate, lauryl acrylate, dodecyl acrylate, stearyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, ethyl diglycol acrylate, dihydrocyclopentadiethyl acrylate, etc. These may be used alone or in combination of two or more.

Regarding the above (a2) component, the glass transition temperature (Tg) of the acrylic polymer (also called "polymer of acrylic component") obtained by polymerizing the acrylic component of the (a2) component is preferably 60°C or higher, and more preferably 70°C or higher. If this Tg is less than 60°C, there is a risk that part of the resin will dissolve when the silicone acrylic copolymer resin is powdered.

The acrylic polymer's glass transition temperature (Tg) calculated using the Fox formula is specifically the glass transition temperature calculated by the following formula: That is, when the glass transition temperature (K) of the acrylic polymer is Tg, the homopolymer glass transition temperatures (K) of the n types of acrylic monomers used are Tg1, Tg2, ... Tgn, and the contents (mass%) of the acrylic monomers are P1, P2, ... Pn, it is expressed by the following formula (I).
(P1+P2+....Pn)/Tg=(P1/Tg1)+(P2/Tg2)+....+(Pn/Tgn) (I)
Here, P1+P2+ . . . Pn=100 (mass %), and the homopolymer glass transition temperature (K) of each of the above acrylic monomers can be measured based on JIS K7121.

The organopolysiloxane of formula (1) obtained as described above preferably has 2 to 10 crosslinking points, and more preferably 3 to 5 crosslinking points, per mole of polymer, and can be graft polymerized with component (a2).

The silicone acrylic graft copolymer resin, which is component (A), is first prepared by graft polymerizing (a2) an acrylic monomer onto (a1) an organopolysiloxane obtained as described above. In this case, it is preferable to emulsion-graft polymerize (a2) component onto (a1) component.

In this case, the mass ratio of the organopolysiloxane of formula (1) to the acrylic acid ester monomer and/or methacrylic acid ester monomer during graft polymerization is 50:50 to 70:30, and preferably 60:40 to 70:30. If the silicone component is less than 50 in mass ratio, sufficient sliding properties may not be achieved.

The radical initiator used in the graft polymerization includes persulfates such as potassium persulfate and ammonium persulfate, hydrogen persulfate water, t-butyl hydroperoxide, and hydrogen peroxide. If necessary, a redox system using a reducing agent such as sodium sulfite, Rongalite, L-ascorbic acid, tartaric acid, sugars, and amines in combination can also be used. The amount of the radical initiator used is preferably 0.1 to 5 mass % of the total amount of component (a2), and more preferably 0.5 to 3 mass %.

The surfactant already contained in the emulsion when the organopolysiloxane is prepared is sufficient for graft polymerization, but to improve stability, anionic surfactants such as sodium lauryl sulfate, sodium laureth sulfate, N-acylamino acid salts, N-acyltaurine salts, aliphatic soaps, and alkyl phosphates can be added. Nonionic emulsifiers such as polyoxyethylene lauryl ether and polyoxyethylene tridecyl ether can also be added. When a surfactant is added, the amount used is preferably 0.1 to 5% by mass of component (a2).

In addition, a chain transfer agent can be added to adjust the molecular weight and graft rate of the graft polymer.

The graft polymerization temperature is preferably 25 to 55°C, more preferably 25 to 40°C. The polymerization time is preferably 2 to 10 hours, more preferably 4 to 8 hours.

The silicone acrylic copolymer resin obtained in this manner is a polymer in which component (a2) is randomly grafted to component (a1).

The silicone acrylic copolymer resin obtained above preferably has a solid content of 30 to 50% by mass in the emulsion. The viscosity of this emulsion (25°C) is preferably 10 to 5,000 mPa·s or less, more preferably 50 to 1,000 mPa·s. The viscosity can be measured with a rotational viscometer. The average particle size of this emulsion is preferably 1 μm or less, and preferably 0.1 μm (100 nm) to 0.3 μm (300 nm). The pH is preferably 6 to 8. The average particle size can be measured with a laser diffraction/scattering type particle size distribution measuring device.

Since the obtained silicone acrylic graft copolymer resin is in the form of an emulsion, the dispersion is concentrated by methods such as heat dehydration, filtration, centrifugation, decantation, etc., and then washed with water as necessary. The moisture is then removed by heat drying under normal or reduced pressure, spray drying in which the dispersion is sprayed into an air stream, or heat drying using a fluid heat medium, and the resin is dried once and powdered. The drying temperature is preferably 50 to 200°C. If the obtained powder is slightly aggregated, it may be crushed using a suitable grinder such as a jet mill, ball mill, or hammer mill.

The silicone acrylic graft copolymer resin may be washed to remove residual cyclic organosiloxanes and surfactants. In this case, the solvent is preferably an alcohol-based organic solvent or a hydrocarbon-based organic solvent, and examples of the solvent include lower alcohols with 1 to 4 carbon atoms and aliphatic hydrocarbons with 5 to 20 carbon atoms. Specifically, methanol, ethanol, isopropyl alcohol, hexane, and isododecane are more preferable. The washing method is, for example, to collect 100 parts by mass of the powder in a beaker, add at least 5 times the mass of the above solvent, stir for several hours, and then filter by suction. It is more effective to wash the powder with the same solvent or with a water-soluble solvent such as an alcohol-based solvent. In this case, the washing is usually performed at room temperature (25°C), but heating may be used depending on the circumstances.

If washed, it is dried again and powdered, but the filtered powder can be simply dried in a dryer at a temperature of 40°C to 200°C for several hours, or a fluidized bed dryer can be used.

The silicone acrylic copolymer resin obtained in this manner preferably has an average particle size of 100 μm or less, and more preferably 10 to 50 μm. The average particle size can be measured using a laser diffraction/scattering type particle size distribution measuring device.

The weight-average molecular weight (Mw) of the silicone acrylic copolymer resin is preferably 50,000 to 500,000. If the molecular weight is less than 50,000, precipitation on the rubber compound surface may become intense, and if it exceeds 500,000, the friction reduction effect may be insufficient. The weight-average molecular weight (Mw) is measured by mixing the emulsion with isopropyl alcohol (IPA), extracting the oil, drying, and then dissolving 1 g of the mixture in 100 mL of toluene, using the measured kinetic viscosity at 25°C as the molecular weight of dimethyl silicone.

(B) Examples of organic solvents include amide compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; ether compounds such as 1,4-dioxane, 1,3-dioxolane, and tetrahydrofuran; ketone compounds such as methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; and acetate esters such as ethyl acetate and propylene glycol monoethyl ether acetate. The organic solvents may be used alone or in combination.

The amount of the specific silicone acrylic copolymer resin (A) is not particularly limited as long as it is an amount that can be dissolved in the organic solvent (B), but it is preferably 1 to 60 parts by weight, and more preferably 5 to 50 parts by weight, per 100 parts by weight of the organic solvent (B).

The coating composition of the present invention is obtained by mixing and dissolving (A) a silicone acrylic copolymer resin and (B) an organic solvent using a known mixing and preparation method such as a propeller stirrer, homogenizer, ball mill, or bead mill.

In addition, the coating composition of the present invention may contain other resins than component (A), pigments, matting agents, antioxidants, UV absorbers, antifreeze agents, pH adjusters, preservatives, defoamers, antibacterial agents, antifungal agents, light stabilizers, antistatic agents, plasticizers, flame retardants, thickeners, surfactants, organic solvents such as film-forming aids, other resins, etc., within the scope of not affecting the performance.

When the coating composition of the present invention thus obtained is applied or immersed on one or both sides of a substrate such as synthetic leather or resin, and then dried (room temperature to 150°C), it can impart excellent tactile feel and gloss, and is characterized by the fact that the appearance of the article having the coating film is not impaired even when pulled.

Here, synthetic leather is made of a base material on which vinyl chloride resin and polyurethane are formed, and examples of resin base materials that can be used include poly(meth)acrylic acid esters such as polymethyl methacrylate, polycarbonate, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyester, cellulose, diethylene glycol bisallyl carbonate polymer, acrylonitrile-butadiene-styrene polymer, polyurethane, and epoxy resin. Drying methods include leaving the material at room temperature for 1 to 10 days, but from the viewpoint of rapidly progressing hardening, a method of heating at a temperature of 20 to 150°C for 1 second to 10 hours is preferred. In addition, when the resin base material is made of a material that is prone to deformation or discoloration due to heating, drying at a relatively low temperature of 20 to 100°C is preferred.

The method for applying the coating composition of the present invention to a substrate is not particularly limited, but examples include application methods using various coaters such as gravure coaters, bar coaters, blade coaters, roll coaters, air knife coaters, screen coaters, and curtain coaters, spray application, immersion, brush application, etc.

The amount of the coating composition of the present invention applied to a substrate is not particularly limited, but in general, in terms of solid content, from the standpoints of antifouling properties, application workability, etc., it is preferable to apply the composition in an amount of preferably 1 to 300 g/ ^m2 , more preferably 5 to 100 g/ ^m2 , or to form a film with a thickness of 1 to 500 μm, preferably 5 to 100 μm, and then naturally dry or heat dry at 100 to 200° C.

The coating film produced using the coating composition of the present invention is characterized by its transparency. That is, when the coating composition of the present invention is applied to a substrate to form a coating film having a thickness of 5 to 50 μm, it is preferable that the difference (H ₁ -H ₀ ) between the haze value H ₁ of the substrate having the coating film and the haze value H ₀ of the substrate having no coating film is 5.0 or less.

The coating composition of the present invention is characterized in that when used on synthetic leather or resin products, it can impart excellent tactile feel and gloss, and the appearance of the product having the coating film is not impaired even when pulled.

There are no particular limitations on the substrate to which the coating composition of the present invention is applied, but by using synthetic leather or resin products with a thickness of 0.1 to 10 mm, the performance of not damaging the appearance even when pulled is effectively exhibited.

The present invention will be specifically explained below with reference to manufacturing examples, examples, and comparative examples, but the present invention is not limited to the following examples. In the following examples, parts and % respectively indicate parts by mass and % by mass.

[(A) Production of silicone acrylic copolymer resin]
[Production Example 1]
(a1) Preparation of emulsion composition containing organopolysiloxane
600g of octamethylcyclotetrasiloxane, 0.96g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a non-volatile content of 46.4% after drying at 105°C for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel. The structure of the organopolysiloxane obtained by the above polymerization reaction was confirmed by ^1H -NMR (frequency 600MHz, room temperature, cumulative number 128) and ^29Si -NMR (frequency 600MHz, room temperature, cumulative number 5000) (apparatus name: JNM-ECA600, measurement solvent: _CDCl3 ). The weight average molecular weight (Mw) of organopolysiloxane (a1) was measured as described above and is shown in Table 1.

Preparation of silicone acrylic graft copolymer resin (A) in Preparation Example 1 While dropping methyl methacrylate/2-hydroxyethyl methacrylate at a mass ratio of 98/2 over 2 to 10 hours to make 30 parts by mass relative to 70 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization to obtain an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 200 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Preparation Example 1). The glass transition temperature (Tg) of the homopolymer of methyl methacrylate (MMA) was 105°C, and the glass transition temperature (Tg) of the homopolymer of 2-hydroxyethyl methacrylate (2-HEMA) was 55°C.

[Production Example 2]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 1.44g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to pH 6-8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.9% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-flowable soft gel.

(A) Production of silicone acrylic graft copolymer resin in Production Example 2 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to make 30 parts by mass per 70 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 192 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Production Example 2).

[Production Example 3]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.9% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-flowable soft gel.

(A) Production of silicone acrylic graft copolymer resin in Production Example 3 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to make 30 parts by mass per 70 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 184 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Production Example 3).

[Production Example 4]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 0.96g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.4% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

(A) Production of silicone acrylic graft copolymer resin in Production Example 4 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours so that the amount was 50 parts by mass relative to 50 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 192 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Production Example 4).

[Production Example 5]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 46.1% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-flowable soft gel.

(A) Preparation of silicone acrylic graft copolymer resin in Production Example 5 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 to 50 parts by mass to the silicone emulsion composition obtained above over 2 to 10 hours, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 198 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Production Example 5).

[Production Example 6]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 0.60g of hexamethyldisiloxane, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 44.6% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Preparation of silicone acrylic graft copolymer resin (A) in Preparation Example 6 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to 70 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction to effect acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 198 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Preparation Example 6).

[Production Example 7]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 7°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a non-volatile content of 46.1% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Preparation of silicone acrylic graft copolymer resin (A) in Preparation Example 7 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to make 30 parts by mass relative to 70 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 185 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Preparation Example 7).

[Production Example 8]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 4.73g of methyltrimethoxysilane, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to pH 6-8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.0% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Preparation of silicone acrylic graft copolymer resin (A) in Preparation Example 8 While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to make 30 parts by mass per 70 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 179 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Preparation Example 8).

[Comparative Production Example 1]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 0.48g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.4% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 1 (A) Preparation of silicone acrylic graft copolymer resin While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to 70 parts by mass of the silicone emulsion composition obtained above to obtain 30 parts by mass, peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 180 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 1).

[Comparative Production Example 2]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 24.00g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to pH 6-8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 46.4% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 2 (A) Preparation of silicone acrylic graft copolymer resin While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to 70 parts by mass of the silicone emulsion composition obtained above to obtain 30 parts by mass, peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, thereby obtaining an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 193 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 2).

[Comparative Production Example 3]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 0.48g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 46.1% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 3 (A) Preparation of silicone acrylic graft copolymer resin While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to 50 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, to obtain an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 190 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 3).

[Comparative Production Example 4]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 12.00g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 46.7% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 4 (A) Preparation of silicone acrylic graft copolymer resin While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to 50 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, to obtain an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 186 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 4).

[Comparative Production Example 5]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 12.00g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 46.7% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 4 (A) Preparation of silicone acrylic graft copolymer resin While dropping methyl methacrylate/2-hydroxyethyl methacrylate in a mass ratio of 98/2 over 2 to 10 hours to 50 parts by mass of the silicone emulsion composition obtained above, a peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, to obtain an approximately 45% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 186 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 4).

[Comparative Production Example 5]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to pH 6-8 with 18g of 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.9% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-flowable soft gel.

Comparative Production Example 5 (A) Preparation of silicone acrylic graft copolymer resin: Peroxide and reducing agent were added to 100 parts by mass of the silicone emulsion composition obtained above at room temperature for 2 to 10 hours to carry out an oxidation-reduction reaction and acrylic graft copolymerization to obtain a silicone resin emulsion containing about 43% silicone acrylic graft copolymer resin. The average particle size of this emulsion was 252 nm. This was spray-dried to obtain a silicone resin powder (Comparative Production Example 5).

[Comparative Production Example 6]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.9% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 6 (A) Preparation of silicone acrylic graft copolymer resin Methyl methacrylate/2-hydroxyethyl methacrylate was added dropwise over 2 to 10 hours in a mass ratio of 98/2 to 90 parts by mass of the silicone emulsion composition obtained above, while adding peroxide and a reducing agent at room temperature to carry out an oxidation-reduction reaction and acrylic graft copolymerization, to obtain an approximately 44% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 179 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 6).

[Comparative Production Example 7]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.9% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 7 (A) Preparation of silicone acrylic graft copolymer resin : Methyl methacrylate/2-hydroxyethyl methacrylate was added dropwise over 2 to 10 hours in a mass ratio of 98/2 to 80 parts by mass of the silicone emulsion composition obtained above, while adding peroxide and a reducing agent at room temperature to carry out an oxidation-reduction reaction to effect acrylic graft copolymerization, thereby obtaining an approximately 44% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing a silicone acrylic graft copolymer resin. The average particle size of this emulsion was 246 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 7).

[Comparative Production Example 8]
(a1) Preparation of Emulsion Composition Containing Organopolysiloxane
600g of octamethylcyclotetrasiloxane, 2.41g of 3-methacryloxypropyldimethoxysilane oligomer, 6.0g of sodium lauryl sulfate dissolved in 54g of pure water, and 6.0g of dodecylbenzenesulfonic acid dissolved in 54g of pure water were charged into a 2L polyethylene beaker, and after uniform emulsification with a homomixer, 454g of pure water was gradually added to dilute, and the mixture was passed through a high-pressure homogenizer three times at a pressure of 300kgf/ ^cm2 to obtain a uniform white emulsion. This emulsion was transferred to a 2L glass flask equipped with a stirrer, thermometer, and reflux condenser, and polymerized at 55°C for 24 hours, then aged at 20°C for 24 hours, and neutralized to a pH of 6 to 8 with 18g of a 10% aqueous sodium carbonate solution to obtain a silicone emulsion composition. This emulsion had a nonvolatile content of 45.9% after drying at 105° C. for 3 hours, and the organopolysiloxane in the emulsion was in the form of a non-fluid soft gel.

Comparative Production Example 8 (A) Preparation of silicone acrylic graft copolymer resin While dropping methyl methacrylate/2-hydroxyethyl methacrylate at a mass ratio of 98/2 over 2 to 10 hours to 30 parts by mass of the silicone emulsion composition obtained above to obtain 70 parts by mass, peroxide and a reducing agent were added at room temperature to carry out an oxidation-reduction reaction to effect acrylic graft copolymerization, thereby obtaining an approximately 44% acrylic silicone resin emulsion (acrylic modified organopolysiloxane) containing silicone acrylic graft copolymer resin. The average particle size of this emulsion was 254 nm. This was spray-dried to obtain a silicone acrylic copolymer resin powder (Comparative Production Example 8).

[Examples 1 to 8, Comparative Examples 1 to 8]
The silicone acrylic copolymer resins of Production Examples 1 to 8 and Comparative Production Examples 1 to 8 were each dispersed in methyl ethyl ketone (MEK) or N,N-dimethylformamide (DMF) at 10% by mass to prepare coating compositions (n=10).

<Method of evaluating dispersibility>
The mixture was allowed to stand at room temperature for 24 hours, and the presence or absence of separation of the liquid after 24 hours was confirmed and evaluated.
◯: No separation ×: Separation (It is preferable that the components of the coating agent do not separate.)

[Coating film formation]
The methyl ethyl ketone coating compositions of Examples 1 to 7 and Comparative Examples 1 to 8 were applied to polyurethane synthetic leather (thickness 1 mm) with a doctor knife to a dry thickness of about 15 μm, and dried at 120° C. for 1 minute to form a coating film on the polyurethane synthetic leather.

The resulting coating film was evaluated using the methods described below. The results are shown in Tables 3 and 4.

<Method of measuring gloss>
The polyurethane synthetic leather on which the coating film was formed was visually evaluated.
○: A luxurious gloss is observed.
△: Some gloss is observed.
×: Almost no effect is observed.

<Method of measuring texture>
The polyurethane synthetic leather on which the coating film was formed was touched with a finger and subjected to a sensory evaluation.
○: A characteristic good slippery feeling is observed.
△: A somewhat good slippery feeling is observed.
×: Resistance is felt on the finger and there is no slippery feeling.

<Method for measuring tensile whitening>
Before washing with water: A black polyurethane synthetic leather (thickness 1 mm) having a coating film formed thereon was pulled strongly, and the change in color tone of the part under tension was visually evaluated.
After washing with water: A black polyurethane synthetic leather (manufactured by Zhejiang Luoxing Co., Ltd.) having a coating film formed thereon was rubbed and washed under running water for 1 minute, the water was wiped off, and the leather was dried at room temperature for 24 hours. After that, the leather was pulled strongly and the color change in the tensioned area was visually evaluated.
○: No whitening is observed.
△: Localized whitening is observed.
×: Overall whitening is observed.

<Method of measuring friction coefficient>
A 100 g metal indenter was brought into contact perpendicularly with the polyurethane synthetic leather on which the coating film was formed using a HEIDON TYPE-38 (manufactured by Shinto Scientific Co., Ltd.), and the frictional force was measured when the indenter was moved at 3 cm/min. The friction coefficient was calculated from the frictional force.
The preferred ranges of the static and dynamic friction coefficients of polyurethane synthetic leather are 0.01 to 2.0 for the static friction coefficient and 0.01 to 1.5 for the dynamic friction coefficient.

<Method for measuring coating transparency>
A coating composition was prepared by dissolving 10 parts of the silicone acrylic resin obtained in Production Examples 1 to 8, Comparative Production Examples 1 to 4, and Comparative Production Examples 6 to 8 in methyl ethyl ketone, and the coating composition was applied to a PET film (Toray Lumirror μ Film T60, thickness 100 μm) or a glass plate (2 mm) with a doctor knife to a thickness of about 15 μm, and dried at 120° C. for 1 minute to form a coating film on the PET film or glass plate. For Comparative Production Example 5, the coating composition was not obtained because it was insoluble in methyl ethyl ketone. The total light transmittance of the PET film or glass plate on which the coating film was formed was measured using COH400 (using a halogen lamp manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with a method conforming to JIS K 7105, and the haze value was calculated from the light transmittance. A preferred range of haze values that can maintain the transparency of a coating film is a difference (H 1 -H 0 ) between the haze value H ₁ of a substrate having a coating film and the haze value H ₀ of a substrate having _no coating film when the coating composition is applied to the substrate to form a coating film having a thickness of ₅ to 50 μm, of 5.0 or less, preferably 3.0 or less.

As shown in Tables 3 and 4, the coating compositions of the present invention (Examples 1 to 8) have excellent touch, gloss, and high transparency, and have a coating film that does not whiten even when pulled, making them ideal for coating synthetic leather or resin articles.

Claims (12)

A transparent coating composition comprising: (A) (a1) a silicone acrylic copolymer resin, which is a polymer containing 50 to 70 parts by mass of an organopolysiloxane represented by the following general formula (1) and (a2) 30 to 50 parts by mass of an acrylic acid ester monomer and/or a methacrylic acid ester monomer; and (B) one or more organic solvents selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene, xylene, ethyl acetate, and propylene glycol monoethyl ether acetate .

(In the formula, R ¹ 's are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R ² 's are each independently an alkenyl group having 2 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms in which a portion of the hydrogen atoms bonded to the carbon atoms are substituted with a mercapto group, an acryloxy group, or a methacryloxy group, X's are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and Y's are each independently a group defined for X above, or -[O-Si(X) ₂ ] _g -X, g is a positive number from 1 to 200, at least two of the groups represented by X and Y are hydroxyl groups, Z is each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxyl group, a is a positive number of 0 or more, b is a positive number that is 90.00% or more and less than 99.90% with respect to the total number of a to d, c is a positive number that is more than 0.04% and 0.70% or less, and d is a positive number that is 0.01% or more and 0.30% or less, and the bonding order of the above siloxane units is not limited. The transparent coating composition according to claim 1, wherein when the transparent coating composition is applied to a substrate to form a coating film having a thickness of 5 to 50 μm, the difference (H ₁ -H ₀ ) between the haze value H ₁ of the substrate having the coating film and the haze value H ₀ of the substrate not having the coating film is 5.0 or less. 3. The transparent coating composition according to claim 1, wherein, in the organopolysiloxane represented by formula (1), the value of a is a positive number from 0 to 1,000, the value of b is a positive number from 100 to 15,000, the value of c is a positive number from 1 to 10, and the value of d is a positive number from 1 to 2. The coating composition according to any one of claims 1 to 3, wherein the polyorganosiloxane represented by the formula (1) is a polymer of a cyclic organosiloxane, an α,ω-dihydroxysiloxane oligomer, an α,ω-dialkoxysiloxane oligomer, or an alkoxysilane and a silane coupling agent represented by the following general formula ( 2 ):
R ³ _(4-ef) R ⁴ _f Si (OR ⁵ ) _e (2)
(In the formula, ^R3 is a mercapto, acryloxy or methacryloxy substituted alkyl group having 1 to 6 carbon atoms, ^R4 is an alkyl group having 1 to 4 carbon atoms, ^R5 is an alkyl group having 1 to 4 carbon atoms, e is 2 or 3, f is 0 or 1, and e+f is 2 or 3.) The transparent coating composition according to claim 4, wherein the polymer is obtained by polymerizing 0.1 to 1.5 parts by mass of the silane coupling agent represented by the formula (2) with 100 parts by mass of the cyclic organosiloxane, α,ω-dihydroxysiloxane oligomer, α, ω -dialkoxysiloxane oligomer, or alkoxysilane. 6. The transparent coating composition according to claim 1, wherein the organopolysiloxane polymer represented by the formula (1) has 2 to 10 crosslinking points per 1 mole. 7. The transparent coating composition according to claim 1, wherein the polyorganosiloxane of component (a1) has a weight average molecular weight (Mw) of 50,000 to 1,000,000 as determined by viscosity measurement. 8. The transparent coating composition according to claim 1, wherein the value of a in the organopolysiloxane represented by the general formula (1) is 0. 9. The transparent coating composition according to claim 1, wherein the acrylic monomer of component (a2) has a glass transition temperature (Tg) of 60° C. or higher. 10. The transparent coating composition according to any one of claims 1 to 9, wherein the blending amount of the silicone acrylic copolymer resin (A) calculated as a solid content and the blending amount of the organic solvent (B) are in a weight ratio of (A):(B)=0.1:99.9 to 40:60 . A coating film obtained by drying the coating composition according to any one of claims 1 to 10 . A synthetic leather or resin article having the coating film according to claim 11 .