Organopolysiloxane and photocurable coating composition

Abstract

To provide: an organopolysiloxane having a photocurable (meth)acrylic group; and a photocurable coating composition that contains the organopolysiloxane and yields a cured film having excellent appearance, transparency, scratch resistance, adhesion, water repellency, antifouling properties, and weather resistance.SOLUTION: The present invention relates to photocurable (meth)acrylic group-containing organopolysiloxane represented by general formula (1) in the figure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to organopolysiloxanes and photocurable coating compositions. [Background technology]

[0002] In recent years, there has been a demand for curable compositions that can form cured films having excellent coatability, appearance, transparency, scratch resistance, surface slippage, low curling, adhesion, chemical resistance, and the like, and that can be used as protective coatings for the surfaces of various substrates such as various plastics (polycarbonate, polymethyl methacrylate, polystyrene, polyester, polyolefin, epoxy resin, melamine resin, triacetyl cellulose resin, ABS resin, AS resin, norbornene-based resin, etc.), metal, wood, etc., and that are capable of forming cured films having excellent weather resistance. Furthermore, it is desirable to have the above properties satisfied by a photocurable composition that can be cured in a short time with less energy than a heat-curable composition that takes a relatively long time to cure and requires a lot of energy.

[0003] A well-known example of a typical photocurable coating composition is a photocurable (meth)acrylic composition that uses a multifunctional (meth)acrylate. The photocurable (meth)acrylic composition contains one or more multifunctional (meth)acrylates and a photopolymerization initiator, and forms a coating by crosslinking through photopolymerization of the (meth)acrylic groups in the multifunctional (meth)acrylate, thereby exhibiting excellent curability, scratch resistance, hardness, and chemical resistance.

[0004] By blending these photocurable (meth)acrylic coating compositions with a fluorine-based additive having a perfluoropolyether group as a water-repellent and antifouling group and a (meth)acrylic group, it is possible to obtain a coating that has not only the above properties but also water-repellent and antifouling properties (Patent Documents 1 and 2). Also known as a fluorine-based additive is a compound in which cyclic polysiloxanes are linked by divalent perfluoropolyether chains (Patent Document 3).

[0005] In recent years, the use of perfluoroalkyl and polyfluoroalkyl compounds (PFAS), which constitute fluorine-based additives, has been partially restricted worldwide due to their high bioaccumulation and persistence. Polysiloxane-based additives have been proposed as an alternative to fluorine-based additives, and it is known that blending polysiloxane-based additives into (meth)acrylic coating compositions can impart smoothness, slipperiness, water repellency, water slippage, and the ability to wipe off fingerprints and oil-based dyes (Patent Documents 4 to 9).

[0006] However, although these examples disclose various organopolysiloxanes having (meth)acryloyl groups at one end, both ends, or in the side chain of the polysiloxane, there are hardly any known examples that, when incorporated into a photocurable (meth)acrylic coating composition, satisfy all of the following requirements: appearance, transparency, scratch resistance, adhesion, water repellency, stain resistance, and weather resistance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-053114 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-138112 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-285501 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-121013 [Patent Document 5] Japanese Patent Application Laid-Open No. 2013-023547 [Patent Document 6] Japanese Patent Application Laid-Open No. 2015-196748 [Patent Document 7] International Publication No. 2015 / 152288 [Patent Document 8] International Publication No. 2018 / 181645 [Patent Document 9] International Publication No. 2018 / 181650 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an organopolysiloxane having a photocurable (meth)acrylic group, and a photocurable coating composition containing the organopolysiloxane that gives a cured film having excellent appearance, transparency, scratch resistance, adhesion, water repellency, stain resistance, and weather resistance. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a photocurable (meth)acrylic group-containing organopolysiloxane represented by the following general formula (1): [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2 is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

[0010] Such organopolysiloxanes have multiple photocurable (meth)acrylic groups at one end, and therefore cured films obtained from compositions containing them have excellent appearance, transparency, scratch resistance, adhesion, water repellency, stain resistance, and weather resistance.

[0011] In the present invention, it is preferable that in the general formula (1), X is a group represented by the following formula (2) or (3), and Q is a group represented by any one of the following formulas (4), (5), and (6). [ka] (In the formula, * 1 represents a bond to the silicon atom in the general formula (1), 2 represents a bond to the oxygen atom in the urethane group of the general formula (1). [ka] (In the formula, * 5 represents a bond to Z in the general formula (1), 6 represents a bond to the nitrogen atom in the urethane group of the general formula (1).

[0012] Such organopolysiloxanes are preferred because they are easy to synthesize and the raw materials are readily available.

[0013] In this case, it is preferable that in the general formula (1), X is a group represented by the formula (2), Q is a group represented by the formula (6), a is 2, and b is 1.

[0014] In this case, it is preferable that in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (4), a is 1, and b is 2.

[0015] In this case, it is preferable that in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (6), a is 2, and b is 2.

[0016] As the organopolysiloxane of the present invention, those such as those mentioned above are more preferred.

[0017] The present invention also provides a photocurable coating composition, comprising: (A) an organopolysiloxane represented by the following general formula (1): (B) a polyfunctional (meth)acrylate compound other than the component (A), and (C) a photopolymerization initiator, The photocurable coating composition contains the above-mentioned component (A), and the content of the component (A) is 0.01 to 20 mass % relative to the total amount of compounds having a photocurable reactive group in the composition. [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2 is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

[0018] Such a photocurable coating composition provides a cured film having excellent appearance, transparency, scratch resistance, adhesion, water repellency, stain resistance, and weather resistance.

[0019] In the present invention, it is preferable that in the general formula (1), X is a group represented by the following formula (2) or (3), and Q is a group represented by any one of the following formulas (4), (5), and (6). [ka] (In the formula, * 1 represents a bond to the silicon atom in the general formula (1), 2 represents a bond to the oxygen atom in the urethane group of the general formula (1). [ka] (In the formula, * 5 represents a bond to Z in the general formula (1), 6 represents a bond to the nitrogen atom in the urethane group of the general formula (1).

[0020] Such photocurable coating compositions are preferred because they are easy to synthesize and the raw materials are readily available.

[0021] In the present invention, it is preferable that the composition further contains (D) an ultraviolet absorber.

[0022] Such a photocurable coating composition is preferred because it improves the weather resistance of the cured film.

[0023] In this case, it is preferable that the component (D) has a hydroxyphenyltriazine structure.

[0024] In this case, it is more preferable that the component (D) has a hydroxyphenyltriazine structure and a (meth)acryloyloxy group.

[0025] Such component (D) forms crosslinks with the components (A) and (B) and is incorporated into the cured film without bleeding or falling off, thereby providing long-term weather resistance.

[0026] In this case, the content of the component (D) relative to the total amount of compounds having a photocurable reactive group in the composition is preferably 1 to 30% by mass.

[0027] Such a photocurable coating composition can provide a cured film with excellent coating appearance and weather resistance.

[0028] In the present invention, it is also preferable that the composition does not contain a compound containing a fluorine atom.

[0029] Such a photocurable coating composition is preferable in terms of environmental properties because it does not contain fluorine atoms. [Effects of the Invention]

[0030] According to the present invention, by adding a specific photocurable (meth)acrylic group-containing organopolysiloxane, it is possible to obtain a photocurable coating composition that gives a cured film with excellent appearance, transparency, scratch resistance, adhesion, water repellency, stain resistance, and weather resistance. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a 1H-NMR spectrum chart of the photocurable (meth)acrylic group-containing organopolysiloxane synthesized in Synthesis Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0032] As described above, there has been a need for the development of a photocurable coating composition that provides a cured film having excellent appearance, transparency, scratch resistance, adhesion, water repellency, stain resistance, and weather resistance, and an organopolysiloxane contained in the composition.

[0033] As a result of extensive research conducted by the present inventors to achieve the above object, they discovered that a coating composition containing an organopolysiloxane containing a specific photocurable (meth)acrylic group can provide a cured film having the above-mentioned excellent properties, and thus completed the present invention.

[0034] That is, the present invention is a photocurable (meth)acrylic group-containing organopolysiloxane characterized by being represented by the following general formula (1). [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

[0035] The present invention also provides a photocurable coating composition, comprising: (A) an organopolysiloxane represented by the following general formula (1): (B) a polyfunctional (meth)acrylate compound other than the component (A), and (C) a photopolymerization initiator, and the content of component (A) is 0.01 to 20 mass % relative to the total amount of compounds having a photocurable reactive group in the composition. [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2 is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

[0036] The present invention will be described in detail below, but the present invention is not limited thereto.

[0037] [Organopolysiloxane] The organopolysiloxane of the present invention is a photocurable (meth)acrylic group-containing organopolysiloxane, and is represented by the following general formula (1). [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2 is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

[0038] The organopolysiloxane of the present invention has two or more (meth)acryloyl groups at one end, and is capable of reacting with a radically polymerizable compound to form a three-dimensional crosslinked structure.

[0039] In the above general formula (1), R 1 are each independently selected from alkyl groups having 1 to 4 carbon atoms and aryl groups having 6 to 10 carbon atoms, and specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl; and aryl groups such as phenyl, tolyl, and xylyl; preferably, they are methyl or phenyl, and more preferably, they are methyl. 2 is an alkyl group having 1 to 8 carbon atoms, preferably a methyl group or an n-butyl group, and more preferably an n-butyl group.

[0040] In the above general formula (1), X is a divalent or trivalent saturated hydrocarbon group. One or more atoms selected from oxygen atoms and nitrogen atoms may be present in the molecular chain, and the group may be linear, branched, or cyclic. A divalent or trivalent saturated hydrocarbon group having 1 to 20 carbon atoms is preferred. Among these, in consideration of ease of synthesis and availability of raw materials, it is more preferred that X is a group represented by the following formula (2) or (3).

[0041] [ka] (In the formula, * 1 represents a bond to the silicon atom in the general formula (1), 2 represents a bond to the oxygen atom in the urethane group of the general formula (1).

[0042] In the general formula (1), each Q is independently an (a+1)-valent saturated hydrocarbon group. An oxygen atom or a nitrogen atom may be present in the molecular chain, and the group may be linear, branched, or cyclic. Examples include linear or branched divalent or trivalent saturated hydrocarbon groups having 1 to 10 carbon atoms, such as -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH-, -CH2CH2CH2CH2-, -CH2CH2-O-CH2CH2-, -CH<, -CH2CH<, -CH(CH3)CH<, -C(CH3)(CH2-)2, and -C(CH3)[(CH2)-]2. Note that "<" indicates two bonds. Among these, in consideration of ease of synthesis and availability of raw materials, Q is preferably a group represented by any one of the following formulas (4), (5), and (6), and more preferably a group represented by the following formula (4) or (6).

[0043] [ka] (In the formula, * 5 represents a bond to Z in the general formula (1), 6 represents a bond to the nitrogen atom in the urethane group of the general formula (1).

[0044] In the general formula (1), each Z is independently an acryloyloxy group or a methacryloyloxy group, of which the acryloyloxy group is preferred because of its excellent photocurability.

[0045] In the above general formula (1), a represents the number of Z's bonded to Q, and b represents the number of groups containing a urethane group bonded to X. a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time; when b is 1, a is 2, and when b is 2, a is 1 or 2. If n is outside this range, three-dimensional crosslinking will not occur during curing of the coating film, and the resulting cured film will have poor scratch resistance and water repellency durability, as well as poor crack resistance. n is an integer from 0 to 200, preferably an integer from 3 to 100, and more preferably an integer from 8 to 60. If n is outside this range, the water repellency, stain resistance, and appearance of the cured coating film may be poor.

[0046] It is preferable that in the general formula (1), X is a group represented by the formula (2), Q is a group represented by the formula (6), a is 2, and b is 1; that in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (4), a is 1, and b is 2; or that in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (6), a is 2, and b is 2.

[0047] Examples of organopolysiloxanes of the general formula (1) above are those that are easy to obtain as raw materials, have compatibility with relatively highly polar binders such as polyfunctional (meth)acrylates, and have excellent photocurability, and include compounds represented by the following formulas (8) to (13).

[0048] [ka] (wherein n is the same as above.)

[0049] [ka] (wherein n is the same as above.)

[0050] There are no particular limitations on the method for producing the organopolysiloxane of general formula (1). For example, it can be obtained by a general urethane reaction. Among these, the preferred production method is described below.

[0051] First, an organopolysiloxane precursor having a carbinol group at one end of the molecular chain, represented by the following general formula (14), is prepared. [ka] (In the formula, R 1 , R 2 , X, b, and n are the same as above.)

[0052] Next, it is preferable to react the hydroxyl group bonded to X in the precursor of general formula (14) above with an isocyanate group of a compound represented by general formula (15) below to obtain the organopolysiloxane of the present invention represented by general formula (1) above. [ka] (In the formula, Q, Z, and a are the same as above.)

[0053] Specific examples of the general formula (15) include 2-acryloyloxyethyl isocyanate {trade name "Karenz AOI" (manufactured by Resonac Co., Ltd.)}, 2-methacryloyloxyethyl isocyanate {trade name "Karenz MOI" (manufactured by Resonac Co., Ltd.)}, 2-(2-methacryloyloxyethyloxy)ethyl isocyanate {trade name "Karenz MOI-EG" (manufactured by Resonac Co., Ltd.)}, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate {trade name "Karenz BEI" (manufactured by Resonac Co., Ltd.)}.

[0054] In the above reaction, the temperature at which the general formula (14) and the general formula (15) are reacted is preferably in the range of 10 to 120°C, more preferably in the range of 40 to 100°C, for the purposes of preventing polymerization of the (meth)acryloyl group during the reaction and promoting the reaction.

[0055] The reaction time is not particularly limited, but is preferably 1 to 12 hours, more preferably 2 to 8 hours.

[0056] The above reaction may be carried out in the presence of a catalyst, if necessary, and examples thereof include di-n-octyltin oxide, dibutyltin dilaurate, iron(III) acetylacetonate, bismuth(III) octoate, titanium(IV) 2-ethylhexyloxide, 1,4-diazabicyclo[2.2.2]octane, 2,2'-dimorpholinodiethyl ether, triethylamine, etc. These catalysts may be used alone or in combination of two or more.

[0057] The amount of catalyst used is preferably in the range of 0 to 10,000 ppm, more preferably 100 to 5,000 ppm, based on the total amount of the compounds represented by the general formula (14) and the general formula (15).Within this range, the reaction proceeds easily, side reactions are less likely to occur, and the coloration of the product is reduced.

[0058] The reaction may be carried out in the presence of a solvent, if necessary. The solvent preferably does not have a group reactive with an isocyanate group, and examples thereof include hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), ethers (diethyl ether, tetrahydrofuran, 1,4-dioxane, etc.), esters (ethyl acetate, butyl acetate), and ketones (methyl ethyl ketone, methyl isobutyl ketone). These solvents may be used alone or in combination of two or more.

[0059] Furthermore, the above reaction may be carried out with the addition of a polymerization inhibitor, if necessary, to suppress polymerization of the (meth)acryloxy group. The polymerization inhibitor may be any one that has been conventionally used for acrylic compounds. Examples of the polymerization inhibitor include phenolic polymerization inhibitors such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, 2-tert-butylhydroquinone, 4-methoxyphenol, and 2,6-di-tert-butyl-p-cresol. These polymerization inhibitors may be used alone or in combination of two or more. The amount of the polymerization inhibitor is not particularly limited, but is preferably 5 to 1,000 ppm, more preferably 20 to 500 ppm, based on the mass of the resulting compound.

[0060] Furthermore, polymerization can also be suppressed by carrying out the reaction under air or nitrogen containing 4% oxygen, and these may be used in combination.

[0061] It is desirable to react the above general formula (14) and the above general formula (15) in equimolar amounts, but this is not a limitation, and the amount of the above general formula (15) to be reacted may be adjusted depending on the number of hydroxyl groups that can react with the isocyanate group in the above general formula (14). However, in consideration of storage stability when made into a coating composition, it is preferable to adjust the ratio of the above general formula (14) to the above general formula (15) so that no isocyanate group remains in the reaction product.

[0062] [Photocurable coating composition] The present invention provides a photocurable coating composition comprising: (A) an organopolysiloxane represented by the above general formula (1), (B) a polyfunctional (meth)acrylate compound other than the component (A), and (C) a photopolymerization initiator, The photocurable coating composition contains the above-mentioned component (A), and the content of the component (A) is 0.01 to 20 mass % relative to the total amount of compounds having a photocurable reactive group in the composition.

[0063] The content of component (A) is in the range of 0.01 to 20% by mass, preferably 0.1 to 20% by mass, and more preferably 1 to 16% by mass, based on the total amount of compounds having a photocurable reactive group in the entire composition. Examples of compounds having a photocurable reactive group include acrylic compounds and methacrylic compounds. For example, among components (A) to (C), components (A) and (B) correspond to compounds having a photocurable reactive group. If the content of component (A) is outside this range, the resulting cured film may have poor water repellency and stain resistance, may not exhibit the durability of these properties, and may also have poor scratch resistance and adhesion to substrates.

[0064] In the present invention, it is preferable that in the general formula (1), X is a group represented by the formula (2) or (3), and Q is a group represented by any one of the following formulas (4), (5), and (6):

[0065] [(B) Component] Component (B) is a polyfunctional (meth)acrylate compound other than component (A) that functions as a binder.

[0066] Specific examples of the component (B) include neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol (number of repeating units (hereinafter referred to as "k") = 2 to 15) di(meth)acrylate, polypropylene glycol (k = 2 to 15) di(meth)acrylate, polybutylene glycol (k = 2 to 15) di(meth)acrylate, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, trimethylolpropane diacrylate, bis(2 ... (2-(meth)acryloxyethyl)-hydroxyethyl-isocyanurate, trimethylolpropane tri(meth)acrylate, tris(2-(meth)acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy poly(meth)acrylates such as epoxy di(meth)acrylates obtained by reacting bisphenol A diepoxy with (meth)acrylic acid, 1,Urethane tri(meth)acrylate obtained by reacting 2-hydroxyethyl (meth)acrylate with a trimer of 6-hexamethylene diisocyanate, urethane di(meth)acrylate obtained by reacting isophorone diisocyanate with 2-hydroxypropyl (meth)acrylate, urethane hexa(meth)acrylate obtained by reacting isophorone diisocyanate with pentaerythritol tri(meth)acrylate, urethane di(meth)acrylate obtained by reacting dicyclomethane diisocyanate with 2-hydroxyethyl (meth)acrylate, dicyclomethane diisocyanate, urethane dimeth ... Examples of suitable poly(meth)acrylates include urethane poly(meth)acrylates such as urethane di(meth)acrylates obtained by reacting a urethane reaction product of fluoromethane diisocyanate and poly(k=6-15)tetramethylene glycol with 2-hydroxyethyl (meth)acrylate, polyester (meth)acrylates obtained by reacting trimethylolethane with succinic acid and (meth)acrylic acid, and polyester poly(meth)acrylates such as polyester (meth)acrylates obtained by reacting trimethylolpropane with succinic acid, ethylene glycol, and (meth)acrylic acid.

[0067] The content of component (B) is preferably 10 to 99% by mass, more preferably 15 to 90% by mass, based on the total amount of compounds having a photocurable reactive group in the entire composition. Within this range, a cured film having excellent coating appearance, scratch resistance, substrate adhesion, and weather resistance is obtained.

[0068] [(C) component] The photopolymerization initiator (C) may be appropriately selected from those having excellent compatibility and curability in the photocurable coating composition. Specific examples include carbonyl compounds such as benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzil, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, benzil dimethyl ketal, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, methylphenyl glyoxylate, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; tetrahydrofuran; and the like. Examples of suitable amines include sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; phosphate compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 and camphorquinone. These compounds can be used alone or in combination of two or more, and can be combined as desired depending on the required coating film performance.

[0069] The content of component (C) is preferably an amount that allows for an appropriate curing rate of the resulting coating film, improves the scratch resistance and adhesion to the substrate of the cured film, and prevents coloration and a decrease in weather resistance. The content is preferably 0.1 to 20 mass%, more preferably 1 to 15 mass%, based on the total amount of compounds having a photocurable reactive group in the composition.

[0070] [(D) component] The photocurable coating composition of the present invention preferably further contains (D) an ultraviolet absorber, as needed, to improve the weather resistance of the cured film. The component (D) can be used alone or in combination of two or more.

[0071] The component (D) is not particularly limited as long as it absorbs ultraviolet light, and examples thereof include hydroxybenzophenones, hydroxybenzotriazoles, cyanoacrylates, hydroxyphenyltriazines, etc. Specific examples include 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-benzyloxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, hydroxybenzophenones such as 2,2'-dihydroxy-4,4'-diethoxybenzophenone, 2,2'-dihydroxy-4,4'-dipropoxybenzophenone, 2,2'-dihydroxy-4,4'-dibutoxybenzophenone, 2,2'-dihydroxy-4-methoxy-4'-propoxybenzophenone, 2,2'-dihydroxy-4-methoxy-4'-butoxybenzophenone, and 2,3,4-trihydroxybenzophenone; hydroxybenzotriazoles such as 2-(2-hydroxy-5-t-octylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole; cyanoacrylates such as ethyl-2-cyano-3,3-diphenylacrylate and 2-ethylhexyl-2-cyano-3,3-diphenylacrylate; 2-(2-hydroxy-4-hexyloxyphenyl)-4,6- Examples of suitable hydroxyphenyl triazines include diphenyl triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and 2-[2-hydroxy-4-(1-octyloxycarbonylethoxy)phenyl]-4,6-bis(4-phenylphenyl)-1,3,5-triazine, among which hydroxyphenyl triazines are preferred. These may be used alone or in combination of two or more.

[0072] Component (D) is preferably an ultraviolet absorber having a hydroxyphenyltriazine structure, and more preferably an ultraviolet absorber having a hydroxyphenyltriazine structure and a (meth)acryloyloxy group. Such an ultraviolet absorber forms crosslinks with components (A) and (B) and is incorporated into the cured film without bleeding or falling off, thereby providing long-term weather resistance.

[0073] Specific examples of hydroxybenzophenones having a (meth)acryloyloxy group include 2-hydroxy-4-(2-(meth)acryloxyethoxy)benzophenone, 2-hydroxy-4-(4-(meth)acryloxybutoxy)benzophenone, 2,2'-dihydroxy-4-(2-(meth)acryloxyethoxy)benzophenone, 2,4-dihydroxy-4'-(2-(meth)acryloxyethoxy)benzophenone, 2,2',4-trihydroxy-4'-(2-(meth)acryloxyethoxy)benzophenone, 2-hydroxy-4-(3-(meth)acryloxy-2-hydroxypropoxy)benzophenone, and 2-hydroxy-4-(3-(meth)acryloxy-1-hydroxypropoxy)benzophenone.

[0074] Specific examples of hydroxybenzotriazoles having a (meth)acryloyloxy group include 2-(2'-hydroxy-5'-(meth)acryloxyphenyl)-2H-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-(meth)acryloxymethylphenyl)-2H-benzotriazole, 2-[2'-hydroxy-5'-(2-(meth)acryloxyethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(2-(meth)acryloxyethyl)phenyl]-5-chloro-2H-benzotriazole, and 2-[2'-hydroxy-3'-methyl-5'-(8-(meth)acryloxyoctyl)phenyl]-2H-benzotriazole.

[0075] Specific examples of hydroxyphenyltriazines having a (meth)acryloyloxy group include a reaction product of 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine with 2-acryloyloxyethyl isocyanate (e.g., Synthesis Example 1 in Japanese Patent No. 6354665), a reaction product of 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine with 1,1-bis(acryloyloxyethyl) Examples of such an amine include a reaction product of 2-[4-{(hydroxy-3-dodecyloxypropyl)oxy}-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine with 2-acryloyloxyethyl isocyanate and a reaction product of 2-[4-{(hydroxy-3-dodecyloxypropyl)oxy}-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine with 1,1-bis(acryloyloxymethyl)ethyl isocyanate (for example, Synthesis Example 1 of Japanese Patent No. 6156214).

[0076] The content of component (D) relative to the total amount of compounds having a photocurable reactive group in the composition is preferably 1 to 30 mass %, more preferably 5 to 20 mass %, which results in a cured film with excellent coating appearance and weather resistance.

[0077] [(E) component] The photocurable coating composition of the present invention may optionally contain one or more components selected from (E) organopolysiloxanes having (meth)acryloyl groups but not urethane bonds, and silica particles surface-modified with alkoxysilanes having (meth)acryloyl groups but not urethane bonds, in order to improve the transparency, scratch resistance, adhesion to substrates, durability, etc. of the cured film.

[0078] An organopolysiloxane having a (meth)acryloyl group but no urethane bond can be obtained, for example, by (co)hydrolytic condensation of an alkoxysilane having a (meth)acryloyl group but no urethane bond, or a mixture with other silanes.

[0079] In addition, silica particles surface-modified with an alkoxysilane having a (meth)acryloyl group but not a urethane bond can be obtained by a method of (co)hydrolytic condensation of an alkoxysilane having a (meth)acryloyl group but not a urethane bond, or a mixture with other silanes, in the presence of colloidal silica, or by a method of dry-treating silica powder with such an alkoxysilane.

[0080] Specific examples of alkoxysilanes having a (meth)acryloyl group but no urethane bond include 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, (meth)acryloxymethyltrimethoxysilane, (meth)acryloxymethyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 8-(meth)acryloxyoctyltrimethoxysilane, and 8-(meth)acryloxyoctyltriethoxysilane.

[0081] As component (E), in consideration of obtaining a cured film excellent in compatibility with other components, heat resistance, chemical resistance, durability, and adhesion to the substrate, 3-(meth)acryloxypropyltrimethoxysilane alone or its (co)hydrolysis condensation product with other silanes, or a product obtained by (co)hydrolysis condensation of 3-(meth)acryloxypropyltrimethoxysilane alone or with other silanes in the presence of colloidal silica, are suitable. These may be used alone or in combination of two or more, and can be combined as desired depending on the required cured film performance.

[0082] When component (E) is used, its amount is preferably more than 0 to 30% by mass or less, more preferably 1 to 25% by mass, based on the total amount of compounds having a photocurable reactive group in the composition, taking into consideration the transparency, scratch resistance, substrate adhesion, durability, etc. of the cured film. When component (E) is added to the photocurable coating composition of the present invention, component (E) is also treated as a compound having a photocurable reactive group, and the above amount is determined accordingly.

[0083] The photocurable coating composition of the present invention may contain a monofunctional (meth)acrylate compound, if necessary, to improve the transparency, flexibility, and substrate adhesion of the cured film. Specific examples of the monofunctional (meth)acrylate compound include methyl (meth)acrylate, ethyl (meth)acrylate, s-butyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, morpholyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, Examples of the mono(meth)acrylate include mono(meth)acrylates such as diethylaminoethyl (meth)acrylate, tricyclodecane (meth)acrylate, polyethylene glycol mono(meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, allyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenyl (meth)acrylate; and mono(meth)acrylate compounds such as an adduct of phthalic anhydride and 2-hydroxyethyl (meth)acrylate.

[0084] The photocurable coating composition of the present invention may further contain other additives depending on the object of the present invention, such as antifouling agents, water repellents, leveling agents, colorants, pigments, antioxidants, anti-yellowing agents, bluing agents, defoamers, thickeners, anti-settling agents, antistatic agents, surfactants, adhesion promoters, infrared absorbers, light stabilizers, flexibility-imparting agents, curing catalysts, and metal oxide particles.

[0085] In the present invention, it is also preferable that the composition does not contain a compound containing a fluorine atom.

[0086] The photocurable coating composition of the present invention may be used as is or diluted with an organic solvent. The organic solvent is preferably selected and used depending on the coating method. For example, when used for spray coating, it is preferable to use any combination of alcohol-based solvents such as isobutanol, glycol-based solvents such as propylene glycol monomethyl ether, ester-based solvents such as n-butyl acetate, ketone-based solvents such as methyl isobutyl ketone, and aromatic solvents such as toluene to adjust the viscosity of the photocurable coating composition to 20 mPa·s or less. When used for application by shower flow coating or dip coating, it is preferable to adjust the viscosity of the photocurable coating composition to 100 mPa·s or less.

[0087] The photocurable coating composition of the present invention can be applied to various substrates and cured to produce a cured film. During photocuring, the photocurable coating composition is applied to the substrate to form a specified film thickness, and then, after volatilizing the solvent as necessary, the composition is irradiated with ultraviolet light, electron beams, or the like using a high-pressure mercury lamp, metal halide lamp, LED lamp, or the like. The irradiation atmosphere may be air or an inert gas such as nitrogen or argon.

[0088] Examples of substrates include organic resins such as plastic molded bodies, wood-based products, fibers, ceramics, glass, metals, and composites thereof, and the coating composition of the present invention can be suitably used for various plastic materials, although it is not particularly limited thereto.

[0089] In particular, it can be suitably used for polycarbonate resin, polystyrene resin, acrylic resin, modified acrylic resin, urethane resin, thiourethane resin, polycondensation product of halogenated bisphenol A and ethylene glycol, acrylic urethane resin, halogenated aryl group-containing acrylic resin, sulfur-containing resin, polyalkylene terephthalate resin, cellulose resin, amorphous polyolefin resin, and composite resins thereof.

[0090] Furthermore, it is also possible to use resin substrates whose surfaces have been treated, specifically, those that have been subjected to chemical conversion treatment, corona discharge treatment, flame treatment, plasma treatment, or acid or alkaline solution treatment, and it is also possible to use laminates whose surface layer is coated with a type of resin different from that of the substrate body.

[0091] Specific examples of the laminate include a laminate in which an acrylic resin layer or a urethane resin layer is present on the surface layer of a polycarbonate resin substrate produced by a coextrusion method or a lamination method, and a laminate in which an acrylic resin layer is present on the surface layer of a polyester resin substrate.

[0092] The photocurable coating composition may be applied directly to the surface of a substrate, or may be applied via a primer layer, an ultraviolet absorbing layer, a printing layer, a recording layer, a heat ray shielding layer, an adhesive layer, an inorganic vapor deposition film layer, or the like, as needed.

[0093] The coating method can be appropriately selected from known coating methods such as a spin coater, comma coater, lip coater, roll coater, die coater, knife coater, blade coater, rod coater, kiss coater, gravure coater, screen coating, dip coating, and cast coating.

[0094] There are no particular restrictions on the thickness of the cured film produced from the photocurable coating composition of the present invention, but for the purposes of preventing coating film defects and exhibiting sufficient scratch resistance, as well as maintaining stable adhesion over the long term and preventing the occurrence of cracks, the thickness is preferably 0.1 to 50 μm, and more preferably 1 to 30 μm.

[0095] Furthermore, if necessary, other coating layers such as an adhesive layer, an ultraviolet absorbing layer, a printing layer, a recording layer, a heat ray shielding layer, a pressure-sensitive adhesive layer, an inorganic vapor deposition film layer, a water- and oil-repellent layer, or a hydrophilic antifouling layer may be formed on the surface of the cured film of the photocurable coating composition of the present invention.

[0096] As described above, the cured film obtained from the photocurable coating composition of the present invention has excellent scratch resistance. To obtain even greater scratch resistance, an inorganic vapor deposition film layer may be coated on the cured film.

[0097] The inorganic vapor deposition film layer is not particularly limited as long as it is formed by a dry film formation method, and examples thereof include layers whose main component is at least one or more metals containing elements such as Si, Ti, Zn, Al, Ga, In, Ce, Bi, Sb, B, Zr, Sn, and Ta, or oxides, nitrides, and sulfides of these metals. Further examples thereof include diamond-like carbon film layers, which have high hardness and excellent insulating properties.

[0098] The method for laminating the inorganic vapor deposition film layer is not particularly limited as long as it is a dry film formation method, and examples thereof include physical vapor deposition methods such as resistance heating vapor deposition, electron beam vapor deposition, molecular beam epitaxy, ion beam deposition, ion plating, and sputtering, and chemical vapor deposition methods such as thermal CVD, plasma CVD, photo CVD, epitaxial CVD, atomic layer CVD, and catCVD.

[0099] An article coated with a cured film of the photocurable coating composition of the present invention thus obtained can have excellent water repellency, stain resistance, scratch resistance, and weather resistance, particularly weather crack resistance.

[0100] The photocurable coating composition of the present invention is preferably used as a photocurable coating composition for articles to be used outdoors.

[0101] In particular, it is preferably used for surface coating of automobile headlamp lenses, vehicle sensor covers, and resin glass.The substrate for these is polycarbonate, which is commonly used because it has high impact resistance, heat resistance, transparency, and lightness.However, polycarbonate is lacking in performance such as chemical resistance, weather resistance, and scratch resistance, so it is preferable to coat the surface with the coating composition of the present invention to improve these performances.

[0102] Furthermore, polycarbonates coated with a coating film made from the photocurable coating composition of the present invention can prevent yellowing and weather-resistant cracking of the coating film, and further exhibit excellent water repellency and stain resistance, and are lightweight and easily moldable, so they can be used in a wide variety of applications, such as automobile headlamp lenses, vehicle sensors, vehicle windows, outdoor signs, window glass for greenhouses and outdoor buildings, terrace and garage roofs, balconies, and instrument covers. [Example]

[0103] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass", respectively. The devices used in the examples are as follows.

[0104] (1) GPC measurement conditions Apparatus: Tosoh Corporation HLC-8320GPC Column: Tosoh Corporation TSKgel G4000HXL + G3000HXL + G2000HXL + G2000HXL (inner diameter 6 mm, length 150 mm) Developing solution: tetrahydrofuran Column tank temperature: 40℃ Flow rate: 1mL / min Detector: Refractive Index (RI) Standard: Monodisperse polystyrene (2) Proton nuclear magnetic resonance spectrum ( 1 H-NMR) measurement conditions Equipment: BRUKER AVANCE III 400 Solvent: CDCl3 Internal standard: tetramethylsilane (TMS) (3) Infrared absorption spectrum (IR) measurement conditions Apparatus: Thermo Fisher Nicolet 6700 (4) Kinematic viscosity measurement conditions The values ​​were measured at 25°C using a Cannon-Fenske viscometer in accordance with JIS Z 8803:2011. (5) Average particle diameter measurement conditions Equipment: Nikkiso UPA-EX150 Method: The particle dispersion was diluted with methanol to a particle concentration of 1% by mass, and after irradiating with ultrasound for 10 minutes, measurements were taken to calculate the volume-based median particle diameter (D50).

[0105] [1] Synthesis of organopolysiloxane (component (A)) [Synthesis Example 1] A 500 mL brown glass reactor equipped with a stirrer, thermometer, reflux condenser, and dropping funnel was charged with 53.4 g of a mono-end-carbinol-modified dimethylpolysiloxane (hydroxyl value 21.0 mgKOH / g) represented by the following formula (16), 0.02 g of t-butylhydroxytoluene as a polymerization inhibitor, and 0.02 g of di-n-octyltin oxide as a urethanization catalyst, and the mixture was heated and stirred until the internal temperature reached 70°C. 4.8 g of 1,1-(bisacryloyloxymethyl)ethyl isocyanate (Resonac Corporation, Karenz BEI, molecular weight 239) was then added. The mixture was then allowed to react at 80°C for 5 hours. After cooling to 25°C, IR spectroscopy revealed an absorption peak (2,260 cm) derived from the isocyanate group. -1) had almost completely disappeared, confirming the consumption of the raw material Karenz BEI. Next, 0.3 g of silica gel (trade name: Silica Gel 60N (spherical, neutral) particle size 40-100 μm, manufactured by Kanto Chemical Co., Inc.) was added, and the mixture was stirred at room temperature for 1 hour to adsorb the tin catalyst, which was then removed by filtration, yielding 56.8 g of colorless, transparent organopolysiloxane A-1. The kinematic viscosity of organopolysiloxane A-1 was 87.3 mm 2 / s, and the non-volatile content was 99.5%. 1 The structure of A-1 confirmed by H-NMR measurement is shown in the following formula (17). 1 FIG. 1 shows a H-NMR spectrum. [ka]

[0106] [Synthesis Example 2] A 500 mL brown glass reactor equipped with a stirrer, thermometer, reflux condenser, and dropping funnel was charged with 44.5 g of a one-end dicarbinol-modified dimethylpolysiloxane (hydroxyl value 126 mg KOH / g) represented by the following formula (18), 0.02 g of t-butylhydroxytoluene as a polymerization inhibitor, and 0.02 g of di-n-octyltin oxide as a urethanization catalyst, and the mixture was heated and stirred until the internal temperature reached 70°C. To this mixture, 14.1 g of 2-acryloyloxyethyl isocyanate (manufactured by Resonac Corporation, Karenz AOI, molecular weight 141) was added dropwise over 30 minutes. The mixture was then allowed to react at 80°C for 5 hours. After cooling to 25°C, IR spectroscopy revealed an absorption peak (2,260 cm) derived from the isocyanate group. -1 ) had almost completely disappeared, confirming the consumption of the raw material Karenz AOI. Next, 0.3 g of silica gel (trade name: Silica Gel 60N (spherical, neutral) particle size 40-100 μm, manufactured by Kanto Chemical Co., Inc.) was added, and the mixture was stirred at room temperature for 1 hour to adsorb the tin catalyst, which was then removed by filtration, yielding 54.0 g of colorless, transparent organopolysiloxane A-2. The kinematic viscosity of organopolysiloxane A-2 was 474 mm 2 / s, and the non-volatile content was 99.4%.1 The structure of A-2 confirmed by H-NMR measurement is shown in the following formula (19). [ka]

[0107] [Synthesis Example 3] A 500 mL brown glass reactor equipped with a stirrer, thermometer, reflux condenser, and dropping funnel was charged with 50.5 g of a one-end dicarbinol-modified dimethylpolysiloxane (hydroxyl value 37.0 mgKOH / g) represented by the following formula (20), 0.02 g of t-butylhydroxytoluene as a polymerization inhibitor, and 0.02 g of di-n-octyltin oxide as a urethanization catalyst, and the mixture was heated and stirred until the internal temperature reached 70°C. To this was added dropwise 8.0 g of 1,1-(bisacryloyloxymethyl)ethyl isocyanate (Resonac Corporation, Karenz BEI, molecular weight 239) over 30 minutes. The mixture was then allowed to react at 80°C for 5 hours. After cooling to 25°C, IR spectroscopy revealed an absorption peak (2,260 cm) derived from the isocyanate group. -1 ) had almost completely disappeared, confirming the consumption of the raw material Karenz BEI. Next, 0.3 g of silica gel (trade name: Silica Gel 60N (spherical, neutral) particle size 40-100 μm, manufactured by Kanto Chemical Co., Inc.) was added, and the mixture was stirred at room temperature for 1 hour to adsorb the tin catalyst, which was then removed by filtration, yielding 55.2 g of colorless, transparent organopolysiloxane A-3. The kinematic viscosity of organopolysiloxane A-3 was 2241 mm 2 / s, and the non-volatile content was 99.6%. 1 The structure of A-3 confirmed by H-NMR measurement is shown in the following formula (21). [ka]

[0108] [Synthesis Example 4] Synthesis of acryloyl group-containing organopolysiloxane E-1 without urethane bonds 142 g of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 500 g of isopropyl alcohol, 0.1 g of p-methoxyphenol, 1.0 g of tetramethylammonium hydroxide, and 20 g of deionized water were combined and reacted at 20°C for 24 hours to obtain a colorless, transparent liquid. The mixture was concentrated by distillation under reduced pressure to obtain organopolysiloxane E-1, a colorless, transparent liquid.

[0109] [Synthesis Example 5] Synthesis of silica particles E-2 surface-treated with acryloyl group-containing silane A mixture of 2.8 g of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 95.6 g of methyl ethyl ketone-dispersed silica sol (MEK-ST, manufactured by Nissan Chemical Industries, Ltd., average particle size 45 nm, silica concentration 30%), and 0.1 g of ion-exchanged water was stirred at 80°C for 3 hours, after which 1.4 g of trimethyl orthoformate was added and the mixture was heated and stirred at the same temperature for an additional hour to obtain a dispersion of surface-treated silica particles E-2. The solids content of the resulting dispersion was 32% by mass, and the average particle size of the surface-treated silica particles E-2 was 45 nm.

[0110] [2] Preparation of coating composition and production of coated article [Examples 1-1 to 1-7, Comparative Examples 1-1 to 1-6] The following components (A) to (F) were mixed with stirring at room temperature in the amounts shown in Tables 1 and 2, and then filtered through a filter paper to prepare coating compositions (X1 to X7, R1 to R6).

[0111] Component (A) A-1: Organopolysiloxane obtained in Synthesis Example 1 A-2: Organopolysiloxane obtained in Synthesis Example 2 A-3: Organopolysiloxane obtained in Synthesis Example 3 A'-4 (comparative component): one-terminal methacrylic-modified organopolysiloxane represented by the following formula (22): [ka] A'-5 (comparative component): acryl-modified organopolysiloxane at both ends represented by the following formula (23): [ka] A'-6 (comparative component): A mixture containing 80% by mass of a one-terminal acrylic-modified organopolysiloxane represented by the following formula (24), 15% by mass of a diacrylate represented by the following formula (25), and 5% by mass of a non-functional organosiloxane represented by the following formula (26): [ka] A'-7 (comparative component): acryl-modified organopolysiloxane at both ends represented by the following formula (27): [ka]

[0112] (B) Component B-1: Pentaerythritol triacrylate (Shin-Nakamura Chemical Co., Ltd., A-TMM-3L) B-2: 1,6-hexanediol diacrylate (A-HD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0113] (C) Component C-1: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IGM, OmniradTPO) C-2: 1-Hydroxycyclohexylphenyl ketone (IGM, Omnirad184)

[0114] (D) Component D-1: 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine (BASF, Tinuvin 405) D-2: A hydroxyphenyltriazine derivative represented by the following formula (28): [ka]

[0115] (E) Component E-1: Acryloyl group-containing organopolysiloxane obtained in Synthesis Example 4 E-2: Surface-treated silica particles obtained in Synthesis Example 5 (32% by mass dispersion in methyl ethyl ketone)

[0116] (F) Additives F-1: Polyether silicone leveling agent (Shin-Etsu Chemical Co., Ltd., Leveling Agent A)

[0117] The coating compositions obtained in the above Examples and Comparative Examples were applied to the surface of a polycarbonate NF-2000 sheet (2 mm thick x 15 cm long x 10 cm wide) manufactured by Mitsubishi Engineering Plastics Corporation by flow coating, then air-dried for 5 minutes, heated at 60°C for 3 minutes, and then irradiated with 2,500 mJ / cm using a high-pressure mercury lamp. 2 The coating film was cured by irradiating it with light at an irradiation dose of 1000 mW / cm2, and the obtained test pieces were subjected to the following evaluations. The results are shown in Tables 1 and 2. Furthermore, to evaluate weather resistance, an Eye Super UV Tester W-151 manufactured by Iwasaki Electric Co., Ltd. was used, and the test pieces were subjected to the following evaluations under the conditions of [black panel temperature 63°C, humidity 50% RH, illuminance 50 mW / cm2]. 2 The test was carried out for 100 hours under the following conditions: [5 hours of rain, 10 seconds per hour] → [1 hour at a black panel temperature of 30°C and a humidity of 95%RH]. After the weather resistance test, the coating film was evaluated for the following evaluation items: coating appearance, haze, water contact angle, and wipeability with a marker.

[0118] (1) Coating appearance The coating film was visually inspected to determine whether or not there was any abnormality. ○: No abnormalities △: Slight unevenness ×: Abnormalities such as foreign matter, unevenness, cracks, and peeling are present

[0119] (2) Hayes The haze of the coating film was measured using a haze meter NDH5000SP manufactured by Nippon Denshoku Industries Co., Ltd. A haze of 1.5 or less was considered to be acceptable.

[0120] (3) Water contact angle A 2 μL droplet of pure water was brought into contact with the coating film and the contact angle was measured using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd. A contact angle of 95° or more was considered to be acceptable.

[0121] (4) Easy to wipe off with a marker A line of approximately 2 cm was written on the coating using Zebra Corporation's Hi-Mackey (registered trademark) black, and then wiped twice with Nippon Paper Crecia Co., Ltd.'s Kaydry (registered trademark). The appearance was then visually observed and judged according to the following criteria. ○: No marks left behind and can be wiped off cleanly △: Mostly wiped off, but traces are visible ×: Almost no wiping

[0122] (5)SW resistance Using a Gakushin abrasion tester AB-301 manufactured by Tester Sangyo Co., Ltd., steel wool No. 0000 was attached and the haze was measured after 11 round trips with a load of 500 g. The difference in haze value before and after the test was taken as the scratch resistance. A haze difference of 7 or less was considered to be acceptable.

[0123] (6) Adhesion Using a razor blade, 25 grids were made in the coating film by cutting six cuts vertically and six cuts horizontally at 2 mm intervals, and after firmly adhering the film with Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd.), the film was rapidly peeled off at a 90° angle towards the user. The number of grids (X) that remained without peeling off the coating film was recorded as X / 25.

[0124] [Table 1]

[0125] [Table 2]

[0126] The coating films obtained from the coating compositions (X1 to X7) of the present invention in Examples 1-1 to 1-7 were excellent in initial appearance, haze, SW resistance, adhesion, water contact angle, and marker wiping ability. In particular, the water contact angle after weathering tests was high at over 95°, and no deterioration in marker wiping ability was observed. This result is presumably due to the fact that the organopolysiloxane (component A) has multiple acrylic groups at one end, which allows the wet coating film to form a gradient structure with the multifunctional acrylate binder (component B), resulting in concentration at the coating film surface and strong three-dimensional crosslinking between component A and the binder, making the film less susceptible to deterioration. Furthermore, the reaction of only one end of the organopolysiloxane (component A) with the binder results in a structure in which siloxane chains stand up on the coating film surface, resulting in a high concentration of the siloxane component at the coating film surface.

[0127] On the other hand, the coating film of Comparative Example 1-1 (R1), which did not contain the organopolysiloxane of the present invention as component (A), was naturally inferior in water contact angle and marker wipeability. Furthermore, because R1 did not contain the UV absorber (component (D)), cracks occurred in the coating film after the weather resistance test.

[0128] In addition, in Comparative Example 1-2 (R2), in which the organopolysiloxane of component (A) was blended at 25% relative to the total amount of compounds having photocurable reactive groups in the composition, the blending amount was too high, resulting in unevenness in the appearance of the coating film and high haze.

[0129] Comparative Examples 1-3 to 1-6 (R3 to R6), which used an (A) component other than the organopolysiloxane of the present invention, exhibited coating unevenness, high haze, poor SW resistance, low water contact angle, and poor marker wiping ability. Furthermore, the water contact angle after weathering tests also decreased significantly. R3 used an organopolysiloxane with monofunctional terminals as component (A), and the functional group was a methacrylic group, which is less UV-reactive than an acryloyl group. This likely resulted in insufficient crosslinking with the binder, phase separation from the binder, and easy removal of component (A) during SW resistance and weathering tests. R4 used an organopolysiloxane with acrylic groups at both ends as component (A). Initial evaluation was favorable, but the water contact angle and marker wiping ability decreased after weathering tests. This is presumably because component (A) has acrylic groups at both ends, preventing siloxane chains from rising up on the coating surface, making it difficult for the coating to thicken. R5 contains an organopolysiloxane that does not contain (meth)acrylic groups, which is thought to be why the coating film exhibited slight unevenness and high haze. It also showed poor water contact angle and wipeability with a marker. R6 uses an organopolysiloxane with acryloyl groups at both ends as component (A), which resulted in poor water contact angle and wipeability with a marker. This is thought to be due to the low content of dimethylpolysiloxane units in component (A). The water contact angle also decreased after the weathering test, which is thought to be because the acrylic groups at both ends prevented the siloxane chains from rising up on the coating film surface, making it difficult for the coating to thicken.

[0130] The present specification includes the following aspects. [1]: A photocurable (meth)acrylic group-containing organopolysiloxane, characterized in that it is represented by the following general formula (1): [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200. [2]: The organopolysiloxane according to [1] above, characterized in that, in the general formula (1), the X is a group represented by the following formula (2) or (3), and the Q is a group represented by any one of the following formulas (4), (5), and (6): [ka] (In the formula, * 1 represents a bond to the silicon atom in the general formula (1), 2 represents a bond to the oxygen atom in the urethane group of the general formula (1). [ka] (In the formula, * 5 represents a bond to Z in the general formula (1), 6 represents a bond to the nitrogen atom in the urethane group of the general formula (1). [3]: The organopolysiloxane according to [2] above, characterized in that, in the general formula (1), X is a group represented by the formula (2), Q is a group represented by the formula (6), a is 2, and b is 1. [4]: The organopolysiloxane according to [2] above, characterized in that, in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (4), a is 1, and b is 2. [5]: The organopolysiloxane according to [2] above, wherein, in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (6), a is 2, and b is 2. [6]: A photocurable coating composition, (A) an organopolysiloxane represented by the following general formula (1): (B) a polyfunctional (meth)acrylate compound other than the component (A), and (C) a photopolymerization initiator, and the content of component (A) is 0.01 to 20 mass % relative to the total amount of compounds having a photocurable reactive group in the composition. [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R 2 is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted by one or more atoms selected from oxygen and nitrogen atoms in the molecular chain, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted by an oxygen atom or nitrogen atom in the molecular chain, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200. [7]: The photocurable coating composition according to [6] above, characterized in that, in the general formula (1), X is a group represented by the following formula (2) or (3), and Q is a group represented by any one of the following formulas (4), (5), and (6): [ka] (In the formula, * 1 represents a bond to the silicon atom in the general formula (1), 2represents a bond to the oxygen atom in the urethane group of the general formula (1). [ka] (In the formula, * 5 represents a bond to Z in the general formula (1), 6 represents a bond to the nitrogen atom in the urethane group of the general formula (1). [8]: The photocurable coating composition according to the above [6] or [7], further comprising (D) an ultraviolet absorber. [9]: The photocurable coating composition according to the above [8], wherein the component (D) has a hydroxyphenyltriazine structure.

[10] : The photocurable coating composition according to the above [9], wherein the component (D) has a hydroxyphenyltriazine structure and a (meth)acryloyloxy group.

[11] : The photocurable coating composition according to any one of [8] to

[10] above, wherein the content of component (D) relative to the total amount of compounds having a photocurable reactive group in the composition is 1 to 30 mass%.

[12] : The photocurable coating composition according to any one of [6] to

[11] above, characterized in that the composition does not contain a compound containing a fluorine atom.

[0131] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A photocurable (meth)acrylic group-containing organopolysiloxane, characterized in that it is represented by the following general formula (1): 【Chemistry 1】 (In the formula, R １ are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R ２ is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted in the molecular chain by one or more atoms selected from oxygen and nitrogen atoms, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted in the molecular chain by an oxygen atom or a nitrogen atom, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

2. 2. The organopolysiloxane according to claim 1, wherein, in the general formula (1), X is a group represented by the following formula (2) or (3), and Q is a group represented by any one of the following formulas (4), (5), and (6): 【Chemistry 2】 (In the formula, * １ represents a bond to the silicon atom in the general formula (1), and * ２ represents a bond to the oxygen atom in the urethane group of the general formula (1). 【Transformation 3】 (In the formula, * ５ represents a bond to Z in the general formula (1), and * ６ represents a bond to the nitrogen atom in the urethane group of the general formula (1).

3. 3. The organopolysiloxane according to claim 2, wherein, in the general formula (1), X is a group represented by the formula (2), Q is a group represented by the formula (6), a is 2, and b is 1.

4. 3. The organopolysiloxane according to claim 2, wherein, in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (4), a is 1, and b is 2.

5. 3. The organopolysiloxane according to claim 2, wherein, in the general formula (1), X is a group represented by the formula (3), Q is a group represented by the formula (6), a is 2, and b is 2.

6. 1. A photocurable coating composition comprising: (A) an organopolysiloxane represented by the following general formula (1): (B) a polyfunctional (meth)acrylate compound other than the component (A), and (C) a photopolymerization initiator, and the content of component (A) is 0.01 to 20 mass% relative to the total amount of compounds having a photocurable reactive group in the composition. 【Chemistry 4】 (In the formula, R １ are each independently a group selected from an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms, and R ２ is an alkyl group having 1 to 8 carbon atoms, X is a divalent or trivalent saturated hydrocarbon group which may be interrupted in the molecular chain by one or more atoms selected from oxygen and nitrogen atoms, Q are each independently an (a+1)-valent saturated hydrocarbon group which may be interrupted in the molecular chain by an oxygen atom or a nitrogen atom, Z are each independently an acryloyloxy group or a methacryloyloxy group, a and b are each independently 1 or 2, but a and b cannot both be 1 at the same time, when b is 1, a is 2, and when b is 2, a is 1 or 2, and n is an integer from 0 to 200.

7. The photocurable coating composition according to claim 6, characterized in that, in the general formula (1), X is a group represented by the following formula (2) or (3), and Q is a group represented by any one of the following formulas (4), (5), and (6): 【Transformation 5】 (In the formula, * １ represents a bond to the silicon atom in the general formula (1), and * ２ represents a bond to the oxygen atom in the urethane group of the general formula (1). 【Transformation 6】 (In the formula, * ５ represents a bond to Z in the general formula (1), and * ６ represents a bond to the nitrogen atom in the urethane group of the general formula (1).

8. 7. The photocurable coating composition according to claim 6, further comprising (D) an ultraviolet absorber.

9. 9. The photocurable coating composition according to claim 8, wherein the component (D) has a hydroxyphenyltriazine structure.

10. 10. The photocurable coating composition according to claim 9, wherein the component (D) has a hydroxyphenyltriazine structure and a (meth)acryloyloxy group.

11. 9. The photocurable coating composition according to claim 8, wherein the content of component (D) is 1 to 30 mass% based on the total amount of compounds having a photocurable reactive group in the composition.

12. 12. The photocurable coating composition according to claim 6, wherein the composition does not contain a compound containing a fluorine atom.

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