JP2005325199A - Active energy ray-curable coating composition and method for forming protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curable coating composition capable of forming an inorganic film in a short time which is excellent in appearance, transparency, adhesiveness to substrates and scratch resistance. <P>SOLUTION: The coating composition comprises methyl silicates (A) represented by formula (1) (wherein Me denotes a methyl group and n denotes an integer of 3-20), alkoxysilanes (B) represented by the formula (2): R<SP>1</SP><SB>a</SB>Si(OR<SP>2</SP>)<SB>4-a</SB>(2) (wherein R<SP>1</SP>denotes an organic group containing a 1-10C alkyl group, a halogenated alkyl group, an aryl group, an epoxy group, a vinyl group, a (meth)acryloyl group, a mercapto group, an amino group, an isocyanate group or a polyoxyalkylene group; R<SP>2</SP>denotes a 1-5C alkyl group or a 1-4C acyl group; and a denotes 1-3) and an active energy ray-sensitive cation polymerization initiator (C). There is also provided a method for forming a protective film by applying the coating composition to a plastic substrate followed by irradiation with an active energy ray. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an active energy ray-curable coating composition capable of forming a transparent protective film having excellent scratch resistance in a short time, and a protective film forming method using the coating composition.

  In recent years, transparent plastic materials such as acrylic resin and polycarbonate resin, which are excellent in crush resistance and light weight, have been widely used as an alternative to transparent glass. However, since the transparent plastic material has a lower surface hardness than glass, it has a problem that the surface is easily damaged.

  Therefore, many attempts have been made to improve the scratch resistance of plastic materials. As one of the most common methods, a method of forming a protective film composed of a siloxane bond on the surface of a substrate by utilizing hydrolysis of an alkoxysilane compound and subsequent condensation reaction is widely known (Patent Document 1). 2). However, these methods have a problem in productivity because a heating time of several tens of minutes to several hours is required to form a protective film. There is also a problem in product management that the storage stability of the coating composition is not good.

In order to solve these problems, for example, a composition containing an alkoxysilane compound having a polymerizable functional group such as (meth) acryloyl group or vinyl group in the molecule, and forming a protective film in a short time by light irradiation. Has been proposed (see Patent Document 3). However, this film does not necessarily have sufficient performance such as adhesion to a substrate and scratch resistance. Further, a composition has been proposed which contains a linear inorganic oligomer (alkyl silicate) having a siloxane skeleton and a cationic polymerization initiator as essential components, and is cured by irradiation with active energy rays to form a protective film ( (See Patent Document 4). However, in the formation of such an inorganic coating, there is a problem that cracks due to curing shrinkage are likely to occur. Patent Document 4 also proposes a composition of an alkyl silicate and an epoxy compound that is a cation-reactive compound. However, it has insufficient scratch resistance and adhesion to a substrate, and is a transparent film. There is a problem that it is difficult to obtain.
JP 48-26822 A JP 55-94971 A JP-A-8-302284 JP 2001-348515 A

  The present invention has been made to solve the above-described problems in the prior art. That is, an object of the present invention is to provide an active energy ray-curable coating composition capable of forming an inorganic film excellent in appearance, transparency, adhesion to a substrate, and scratch resistance in a short time, and for this coating It is providing the protective film formation method using a composition.

  As a result of intensive studies to achieve the above object, the inventors of the present invention are based on a composition containing a specific methyl silicate, a specific alkoxysilane, and an active energy ray-sensitive cationic polymerization initiator. It was found that a film having a good appearance, scratch resistance, and adhesion to a substrate can be formed by applying an active energy ray and irradiating with active energy rays, thereby completing the present invention.

  That is, the present invention relates to methyl silicates (A) represented by the following general formula (1),

(In the formula, Me represents a methyl group, and n represents an integer of 3 to 20.)
Alkoxysilanes (B) represented by the following general formula (2),
R ¹ _a Si (OR ² ) _4-a (2)
(Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms, halogenated alkyl group, aryl group, epoxy group, vinyl group, (meth) acryloyl group, mercapto group, amino group, isocyanate group, and polyoxyalkylene group) An organic group containing a group selected from the group consisting of: R ² represents an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms, and a represents an integer of 1 to 3. ),and,
Active energy ray-sensitive cationic polymerization initiator (C)
An active energy ray-curable coating composition containing

  Furthermore, this invention is a protective film formation method which apply | coats the said composition for coating to a base material, irradiates an active energy ray, and forms a protective film.

  ADVANTAGE OF THE INVENTION According to this invention, the active energy ray-curable coating composition which can form the inorganic film excellent in the external appearance, transparency, the adhesiveness to a base material, and abrasion resistance in a short time can be obtained. In addition, if this coating composition is applied to a substrate and irradiated with active energy rays, a protective coating excellent in appearance, transparency, adhesion to the substrate, and scratch resistance on the substrate in a short time. Can be formed in a short time.

  The methyl silicates (A) used in the present invention are compounds represented by the general formula (1). Specifically, it is obtained by hydrolyzing tetrafunctional tetramethoxysilane and polycondensing linearly. In general formula (1), n represents the number of repeating units of methyl silicates and is an integer of 3 to 20. In particular, n is preferably an integer of 4 to 10. This methyl silicate (A) can also be used individually by 1 type, and can also be used in mixture of multiple types.

The alkoxysilane (B) used in the present invention is a compound represented by the general formula (2). Specifically, it is a compound in which ¹ to 3 organic groups (—R ¹ ) and ¹ to 3 alkoxy groups or acyloxy groups (—OR ² ) are bonded directly to Si atoms. By blending these, toughness or flexibility is imparted to the coating.

  Specific examples of the alkoxysilanes (B) include methyltriethoxysilane, methyltrimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and 2- (3,4-epoxy. (Cyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, p-styryltriethoxysilane, p-styryl Methoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane , 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, trimethylethoxysilane, triethylethoxysilane and the like. Of these, methyltrimethoxysilane, phenyltrimethoxysilane, and dimethyldimethoxysilane are preferred from the viewpoints of high hydrolysis / condensation rate and imparting toughness and flexibility to the resulting coating and making it difficult for cracks to occur. Alkoxysilanes (B) may be used alone or in combination of two or more.

  Although the compounding quantity of alkoxysilane (B) is not specifically limited, The inside of the range of 10-2000 mass parts is preferable with respect to 100 mass parts of (A) component, and the inside of the range of 100-1000 mass parts is more preferable. If it is 10 mass parts or more, generation | occurrence | production of the crack of a film will be suppressed. Moreover, if it is 2000 mass parts or less, the film excellent in abrasion resistance can be obtained.

  The active energy ray-sensitive cationic polymerization initiator (C) used in the present invention generates an acid by active energy rays such as visible light, ultraviolet rays, and heat rays, and forms methyl silicates (A) and alkoxysilanes (B). It is a compound that causes a polycondensation reaction. Among these, a photo-sensitive cationic polymerization initiator that generates an acid by irradiation with visible light or ultraviolet light, and a heat-sensitive cationic polymerization initiator that generates an acid by heat rays are preferable. In particular, a photosensitive cationic polymerization initiator is more preferable because it has high activity and does not cause thermal deterioration of the plastic material.

  Preferred examples of the photosensitive cationic polymerization initiator include diaryl iodonium salts, triaryl sulfonium salts, monoaryl dialkyl sulfonium salts, triaryl selenonium salts, tetraaryl phosphonium salts, aryl diazonium salts, and the like. Specific examples of diaryliodonium salts include Irgacure 250 (trade name, manufactured by Ciba Specialty Chemicals Co., Ltd.). Specific examples of the triarylsulfonium salt include Adekaoptomer SP-150 and SP-170 (above, trade name, manufactured by Asahi Denka Kogyo Co., Ltd.).

  The compounding amount of the active energy ray-sensitive cationic polymerization initiator (C) is not particularly limited, but is 0.01 to 10 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). Within the range is preferable. If it is 0.01 mass part or more, it will fully harden | cure by irradiation of an active energy ray, and there exists a tendency for a favorable protective film to be obtained. Moreover, if it is 10 mass parts or less, about the physical property of the protective film obtained by hardening, there is no coloring in particular, and it exists in the tendency for surface hardness and abrasion resistance to become favorable. Furthermore, the compounding amount is more preferably in the range of 0.05 to 5 parts by mass from the viewpoint of good curability and a protective film having good performance.

  The coating composition of the present invention can further contain an epoxy compound (D). In addition to the component (A) and the component (B), by further blending the epoxy compound (D), the curability of the coating composition is further improved, and toughness is imparted to the resulting film, and cracks are prevented. Occurrence is suppressed.

  The epoxy compound (D) is not particularly limited as long as it contains an epoxy group in the molecule. Specific examples thereof include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol. Diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, diglycerin tetraglycidyl ether, trimethylolpropane triglycidyl ether, 2,6-diglycidyl phenyl ether, sorbitol triglycidyl ether, triglycidyl isocyanurate , Diglycidylamine, diglycidylbenzylamine, diglycidyl phthalate ester Bisphenol A diglycidyl ether, butadiene dioxide, dicyclopentadiene dioxide, 3,4-epoxycyclohexenecarboxylic acid and ethylene glycol diester, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3, 4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, dicyclopentadiene epoxide glycidyl ether, pentaerythritol polyglycidyl ether, bisphenol List adducts of type A epoxy resin and ethylene oxide, phenol novolac type epoxy resin, cresol novolac type epoxy resin, etc. It can be. Among these, those containing two or more epoxy groups in the molecule are preferable from the viewpoint that the curing rate is high and the resulting protective coating has good scratch resistance. An epoxy compound (D) may be used individually by 1 type, or may be used in combination of 2 or more type.

  Although the compounding quantity of an epoxy compound (D) is not specifically limited, The inside of the range of 0-200 mass parts is preferable with respect to 100 mass parts of (A) component, and the inside of the range of 10-100 mass parts is more preferable.

  The coating composition of the present invention preferably further contains a polymer compound (E). By mix | blending this, a softness | flexibility is provided to a film and generation | occurrence | production of a crack is suppressed. Examples of the polymer compound (E) include polyacrylic polymers, polyvinyl polymers, polyether polymers, polydialkylsiloxanes (silicone resins), and the like.

  Although the compounding quantity of a high molecular compound (E) is not specifically limited, The inside of the range of 0-50 mass parts is preferable with respect to 100 mass parts of (A) component, and the inside of the range of 1-10 mass parts is more preferable.

  The coating composition of the present invention preferably further contains a polymerizable vinyl compound (F) and an active energy ray-sensitive radical polymerization initiator (G). By blending the polymerizable vinyl compound (F) together with the active energy ray-sensitive radical polymerization initiator (G), the active energy ray curability of the coating composition is further improved, and the resulting protective film is tough. Is granted.

  The polymerizable vinyl compound (F) is a compound that has a polymerizable double bond group in the molecule and undergoes radical polymerization upon irradiation with active energy rays. The structure of the polymerizable vinyl compound (F) is not particularly limited as long as it has a polymerizable double bond group in the molecule. In particular, a monofunctional or polyfunctional (meth) acrylate compound containing an acryloyl group or a methacryloyl group in the molecule is preferable from the viewpoint of a high polymerization rate.

  Specific examples of monofunctional (meth) acrylate compounds include phenyl (meth) acrylate, benzyl (meth) acrylate, phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, paracumylphenol ethylene oxide modified (meth) acrylate, Isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (Meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethyl Sil (meth) acrylate, n-hexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, Tetrahydrofurfuryl (meth) acrylate, phosphoethyl (meth) acrylate, etc. are mentioned.

  Specific examples of the polyfunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di ( (Meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di ( (Meth) acrylate, 2,2-bis [4- (meth) acryloyloxyphenyl] -propane, 2,2-bis [4- (meth) acryloyloxyethoxyphenyl] -propane, 2,2-bis [4- (Meth) acryloyloxydiethoxyphenyl] -propane, 2,2-bis [4- (meth) acryloyloxypentaethoxyphenyl] -propane, 2,2-bis [4- (meth) acryloyloxyethoxy-3-phenylphenyl ] -Propane, bis [4- (meth) acryloylthiophenyl] sulfide, bis [4- (meth) acryloyloxyphenyl] -sulfone, bis [4- (meth) acryloyloxyethoxyphenyl] -sulfone, bis [4- (Meth) acryloyloxydiethoxyphenyl] -sulfone, bis [4- (meth) acryloyloxypentaethoxyphenyl] -sulfone, bis [4- (meth) acryloyloxyethoxy-3-phenylphenyl] -sulfone, bis [4 -(Meth) acryloyloki Ethoxy-3,5-dimethylphenyl] -sulfone, bis [4- (meth) acryloyloxyphenyl] -sulfide, bis [4- (meth) acryloyloxyethoxyphenyl] -sulfide, bis [4- (meth) acryloyloxy Pentaethoxyphenyl] -sulfide, bis [4- (meth) acryloyloxyethoxy-3-phenylphenyl] -sulfide, bis [4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl] -sulfide, 2,2 -Bis [4- (meth) acryloyloxyethoxy-3,5-dibromophenylpropane], trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, dipentaeryth Toruhekisa (meth) acrylate.

  Among these, polyfunctional (meth) acrylates are more preferable from the viewpoints of good curability and excellent scratch resistance of the resulting protective coating. As the polymerizable vinyl compound (F), one type may be used alone, or several types may be mixed and used.

  Although the compounding quantity of a polymeric vinyl compound (F) is not specifically limited, The inside of the range of 0-200 mass parts is preferable with respect to 100 mass parts of (A) component, and the inside of the range of 1-100 mass parts is more preferable. .

  The active energy ray-sensitive radical polymerization initiator (G) is a component that generates active radical species in response to active energy rays and initiates polymerization of the polymerizable vinyl compound (F). Among these, a photosensitive radical polymerization initiator that generates radicals in response to visible light or ultraviolet rays is preferable because it has high activity and does not cause thermal deterioration of the plastic substrate.

  Specific examples of the active energy ray-sensitive radical polymerization initiator (G) include 3,3-dimethyl-4-methoxy-benzophenone, benzyldimethyl ketal, isoamyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate, Benzophenone, p-methoxybenzophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, methylphenylglyoxylate, ethylphenylglyoxylate 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1,2,4,6-trimethylbenzoyldiphenyl A phosphine oxide etc. are mentioned. Among them, methylphenylglyoxylate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, benzyl Dimethyl ketal and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are more preferable from the viewpoint of curing rate. This active energy ray-sensitive radical polymerization initiator (G) may be used alone or in combination of two or more.

  The blending amount of the active energy ray-sensitive radical polymerization initiator (G) is not particularly limited, but is preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the component (F). When the blending amount is 0.01 parts by mass or more, it is preferable from the viewpoint of the curing rate by active energy ray irradiation, and when it is 10 parts by mass or less, it is preferable from the viewpoint of scratch resistance of the resulting film. More preferably, it exists in the range of 0.05-5 mass parts.

  The coating composition of the present invention can contain an organic solvent for the purpose of adjusting the solid content concentration, improving the dispersion stability, improving the coating property, and improving the adhesion to the substrate. Examples of the organic solvent include alcohols, ketones, ethers, esters, cellosolves, aromatic compounds, and the like.

  Specifically, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, t-butyl alcohol, benzyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxy Methoxy) ethanol, 2-butoxyethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, di Propylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol Rumonomethyl ether, diacetone alcohol, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, acetophenone, diethyl ether, di Propyl ether, diisopropyl ether, dibutyl ether, dihexyl ether, anisole, phenetole, tetrahydrofuran, tetrahydropyran, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether , Diethylene glycol dibutyl ether, glycerin ether, methyl acetate, ethyl acetate, propylene acetate , Isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, pentyl acetate, isopentyl acetate, 3-methoxybutyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, methyl propionate, ethyl propionate, butyl propionate, Examples include γ-butyrolactone, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-phenoxyethyl acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, benzene, toluene, xylene and the like. These organic solvents may be used alone or in combination of two or more.

  The content of the organic solvent is preferably in the range of 0 to 1000 parts by mass, and more preferably in the range of 0 to 100 parts by mass with respect to 100 parts by mass in total of the components (A) to (G). If this is 1000 parts by mass or less, the problem that the solid content becomes too low and the coating film becomes thin is less likely to occur, and a protective coating with good scratch resistance tends to be obtained.

  In addition, the coating composition of the present invention includes polymer fine particles, colloidal silica, colloidal metal, photosensitizer (for example, anthracene compound, thioxanthone compound, anthraquinone compound, naphthalene compound, if necessary. , Pyrene compounds, etc.), fillers, dyes, pigments, pigment dispersants, flow regulators, leveling agents, antifoaming agents, UV absorbers, light stabilizers, antioxidants, gel particles, fine particle powders, etc. May be.

  The coating composition of the present invention is applied to the surface of a base material made of, for example, plastic (film thickness of about 0.5 to 100 μm), and then cured by irradiation with active energy rays to form a protective film. be able to.

  The coating composition can be applied by a conventionally known method, for example, spray, roll coater, gravure coater, flexo, screen, spin coater, flow coater, electrostatic coating or the like.

  Examples of active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, incandescent lamps, xenon lamps, halogen lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, gallium lamps, and excimer lasers. Can be used as a light source. Electron beams, β rays, γ rays and the like can also be used. One type of active energy ray may be used alone, or a plurality of different types may be used. When different types of active energy rays are used, they may be irradiated simultaneously or sequentially. Moreover, you may heat simultaneously with active energy ray irradiation, and you may heat using a dryer etc. before and after active energy ray irradiation.

  The coating composition of the present invention is based on, for example, metals, cans, plastics, paper, wood materials, inorganic materials, electrodeposition coating plates, laminate plates, films such as PET (polyethylene terephthalate) and polyolefins, or combinations thereof. It can be applied to a material as a paint material or an ink material.

  Examples of the present invention will be described in detail below, but the present invention is not limited thereto. In the following description, “part” means “part by mass”.

<Example 1>
[Preparation of active energy ray-curable coating composition]
As methyl silicates (A), tetramethoxysilane average heptamer, average molecular weight of about 789 methyl silicate (Corcoat Co., Ltd., trade name: methyl silicate 53A, hereinafter abbreviated as “MS53A”), 10 parts, alkoxysilanes (B ) 20 parts methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 136, trade name KBM-13, hereinafter abbreviated as “MTMS”), phenyltrimethoxysilane (manufactured by Toray Dow Corning Silicone Co., Ltd.) Product name AY43-040, hereinafter abbreviated as "PhTMS") 2 parts, active energy ray sensitive cationic polymerization initiator (C) as photocation initiator Irgacure 250 (trade name, manufactured by Ciba Specialty Chemicals Co., Ltd., hereinafter 1 part of “IRG250”), silicone surfactant as leveling agent (Nihon Uni) Chromatography (trade name) manufactured by L-7001) 0.05 parts were homogeneously mixed γ- butyrolactone 2 parts as a solvent, to prepare an active energy ray-curable coating composition.

[Formation of film]
An appropriate amount of this coating composition was dropped onto an acrylic plate (Mitsubishi Rayon Co., Ltd., Acrylite (registered trademark) EX) having a length of 10 cm, a width of 10 cm, and a thickness of 3 mm, and a bar coating method (Bar Coater No. 50). Application) so that a 4-5 μm-thick film was obtained, and air-dried at room temperature for about 30 minutes.

[Curing of coating]
Furthermore, using a 120 W / cm high-pressure mercury lamp equipped with a conveyor (manufactured by Oak Manufacturing Co., Ltd., UV irradiation device, Handy UV-1200, QRU-2161 type), UV light with an integrated light quantity of 1000 mJ / cm ² was irradiated. A cured coating was obtained. The amount of ultraviolet irradiation was measured with an ultraviolet light meter (manufactured by Oak Manufacturing Co., Ltd., UV-351 type, peak sensitivity wavelength 360 nm).

[Evaluation of coating]
The obtained cured film (protective film) was evaluated by the following method.

1) Appearance The acrylic plate having a cured film was visually observed for the presence of transparency, cracks, and whitening, and evaluated according to the following criteria.
“◯”: Transparent and free from cracks and whitening defects (good).
“X”: An opaque part, a defect such as a crack or whitening (defect).

2) Film thickness The cross section of the acrylic board which has a cured film was observed with the scanning electron microscope, and the film thickness was measured.

3) Scratch resistance The surface of the acrylic plate having a cured coating was rubbed 10 times with # 0000 steel wool at a pressure of 9.8 × 10 ⁴ Pa, and the degree of scratches generated in the range of 1 cm × 3 cm was observed. And evaluated according to the following criteria.
“A”: hardly scratched “B”: 1 to 9 scratches. There is a glossy surface.
“C”: 10 to 99 scratches are found. There is a glossy surface.
“D”: There are over 100 scratches. There is a glossy surface.
“E”: The glossy surface disappears.
4) Adhesiveness of base material After making 100 squares by making cuts of 11 vertical and horizontal at 1mm intervals with a razor blade on the cured film on the surface of the acrylic board, and making close contact with the cellophane tape, 45 degrees before It peeled off rapidly in the direction, and the number of squares remaining without peeling the cured film was measured and evaluated according to the following criteria.
“◯”: There is no peeled cell (good adhesion).
“Δ”: 1 to 5 peeled squares (medium adhesion).
“×”: 6 or more peeled cells (poor adhesion).

  As a result, the coating film of this example had good appearance, scratch resistance, pencil hardness, and substrate adhesion. The results are shown in Table 1.

<Example 2>
As component (A), instead of 10 parts of MS53A, 10 parts of tetramethoxysilane average tetramer, methyl silicate having an average molecular weight of about 470 (product name: methyl silicate 51, hereinafter referred to as “MS51”, manufactured by Colcoat Co., Ltd.) Except for blending, the coating composition was prepared, the film was formed and cured, and the film was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 3>
Example (B), except that 2 parts of dimethyldimethoxysilane (manufactured by Toray Dow Corning Silicone Co., Ltd., trade name AY43-004, hereinafter abbreviated as “DMDMS”) was blended in place of 2 parts of PhTMS. In the same manner as in Example 1, the coating composition was prepared, the film was formed / cured, and the cured film was evaluated. The results are shown in Table 1.

<Example 4>
(B) As a component, preparation of a coating composition, formation / curing of a film, and evaluation of a cured film were performed in the same manner as in Example 2 except that 2 parts of DMDMS was blended instead of 2 parts of PhTMS. The results are shown in Table 1.

<Example 5>
(B) Component PhTMS is not blended, except that one part of polyethylene glycol diglycidyl ether (Nagase Sangyo Co., Ltd., trade name Denacol EX-821, hereinafter abbreviated as “PEGDG”) is blended as component (D). In the same manner as in Example 1, preparation of a coating composition, formation / curing of a film, and evaluation of a cured film were performed. The results are shown in Table 1.

<Example 6>
(B) Component PhTMS was not blended, but Example 1 was used except that 1 part of polyethylene glycol (trade name PEG600, hereinafter referred to as “PEG600”) manufactured by Wako Pure Chemical Industries, Ltd. was blended as component (E). In the same manner as described above, the coating composition was prepared, the film was formed and cured, and the cured film was evaluated. The results are shown in Table 1.

<Example 7>
(B) Component PhTMS is not blended, and as component (F), 6 parts of dipentaerythritol hexaacrylate (manufactured by Toa Gosei Co., Ltd., trade name Aronix M-400, hereinafter abbreviated as “DPHA”), (G) component Preparation of a coating composition in the same manner as in Example 1 except that 0.2 part of a photo radical polymerization initiator (trade name Irgacure 184, hereinafter abbreviated as “IRG184”) manufactured by Ciba Specialty Chemicals was added. The film formation / curing and the evaluation of the cured film were carried out. The results are shown in Table 1.

<Comparative Example 1>
A composition was prepared by mixing only 10 parts of MS53A as component (A) and 0.3 part of IRG250 as component (C). Using this composition, a film was formed and cured in the same manner as in Example 1. Since the obtained cured film was markedly cracked and immediately peeled off, the subsequent film evaluation was not performed. The results are shown in Table 2.

<Comparative example 2>
A composition was prepared by mixing only 10 parts of MS51 as component (A) and 0.3 part of IRG250 as component (C). Using this composition, a film was formed and cured in the same manner as in Example 1. Since the obtained cured film was markedly cracked and immediately peeled off, the subsequent film evaluation was not performed. The results are shown in Table 2.

<Comparative Example 3>
As an alternative to component (A), 10 parts of tetraethoxysilane average pentamer, ethyl silicate (trade name ethyl silicate 40, hereinafter referred to as “ES40”, manufactured by Colcoat Co., Ltd.) having an average molecular weight of about 745, component (C) A composition was prepared by mixing only 0.3 part of IRG250. Using this composition, a film was formed and cured in the same manner as in Example 1, but could not be cured. The results are shown in Table 2.

<Comparative example 4>
As an alternative to component (A), 10 parts of tetraethoxysilane average decamer, ethyl silicate having an average molecular weight of about 1400 (Corcoat Co., Ltd., trade name: ethyl silicate 48, hereinafter abbreviated as “ES48”), component (C) A composition was prepared by mixing only 0.3 part of IRG250. Using this composition, a film was formed and cured in the same manner as in Example 1, but could not be cured. The results are shown in Table 2.

<Comparative Example 5>
8 parts of MS51 as component (A), 2 parts of alicyclic bifunctional epoxy resin (manufactured by Daicel Chemical Industries, Ltd., trade name Celoxide 2021P, hereinafter abbreviated as “2021P”) as component (D), (C ) A composition was prepared by mixing only 0.3 part of IRG250 as a component. Using this composition, film formation / curing and evaluation of the cured film were carried out in the same manner as in Example 1. The results are shown in Table 2.

Abbreviations in Table 1 and Table 2:
“MS53A”: methyl silicate having an average tetramethoxysilane heptamer and an average molecular weight of about 789 (product name: methyl silicate 53A, manufactured by Colcoat Co., Ltd.)
“MS51”: Methyl silicate having an average tetramethoxysilane tetramer and an average molecular weight of about 470 (trade name Methyl silicate 51, manufactured by Colcoat Co., Ltd.)
“MTMS”: Methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 136, trade name KBM-13)
“PhTMS”: Phenyltrimethoxysilane (made by Toray Dow Corning Silicone Co., Ltd., trade name AY43-040)
“DMDMS”: dimethyldimethoxysilane (made by Toray Dow Corning Silicone Co., Ltd., trade name AY43-004)
“IRG250”: Photo-cationic polymerization initiator (product name: Irgacure 250, manufactured by Ciba Specialty Chemicals Co., Ltd.)
“PEGDG”: Polyethylene glycol diglycidyl ether (manufactured by Nagase Sangyo Co., Ltd., trade name Denacol EX-821)
“PEG600”: Polyethylene glycol (trade name PEG600, manufactured by Wako Pure Chemical Industries, Ltd.)
“DPHA”: Dipentaerythritol hexaacrylate (trade name Aronix M-400, manufactured by Toagosei Co., Ltd.)
“IRG184”: photoradical polymerization initiator (product name: Irgacure 184, manufactured by Ciba Specialty Chemicals)
“2021P”: alicyclic bifunctional epoxy resin (manufactured by Daicel Chemical Industries, Ltd., trade name: Celoxide 2021P)
“ES40”: tetrasilicate silane average pentamer, ethyl silicate having an average molecular weight of about 745 (product name: ethyl silicate 40, manufactured by Colcoat Co., Ltd.)
“ES48”: Ethyl silicate having an average tetraethoxysilane decamer and an average molecular weight of about 1400 (product name: Ethyl silicate 48, manufactured by Colcoat Co., Ltd.)

Claims (2)

Methyl silicates (A) represented by the following general formula (1),

(In the formula, Me represents a methyl group, and n represents an integer of 3 to 20.)
Alkoxysilanes (B) represented by the following general formula (2),
R ¹ _a Si (OR ² ) _4-a (2)
Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an aryl group, an epoxy group, a vinyl group, a (meth) acryloyl group, a mercapto group, an amino group, an isocyanate group and a polyoxyalkylene group. An organic group containing a group selected from the group consisting of: R ² represents an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms, and a represents an integer of 1 to 3. ),and,
Active energy ray-sensitive cationic polymerization initiator (C)
A composition for an active energy ray-curable coating comprising:   A method for forming a protective film, comprising applying the coating composition according to claim 1 to a substrate and irradiating an active energy ray to form a protective film.