JP2008201864A - Coating composition and optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition providing a cured film having excellent curability, abrasion resistance, scratch resistance, transparency and curability at the vicinity of the surface of a coated film in usual air, and having excellent preservation stability, and to provide a high-quality optical film including the coated layer of the coating composition. <P>SOLUTION: The coating composition contains (A) organic-inorganic composite fine particles, (B) a polyfunctional (meth)acrylate, (C) a polymerization initiator and (D) a polyfunctional thiol. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coating composition, an optical film, an antireflection film, a polarizing plate, an optical filter for plasma display, and an image display device.

  In recent years, a material that is excellent in wear resistance and curability and gives a transparent cured film has been demanded as a coating material. In order to meet such a demand, many materials have been proposed in which reactive fine particles obtained by modifying the surface of various inorganic fine particles (for example, silica fine particles such as colloidal silica) with a polymerizable functional group have been proposed.

  For example, Patent Document 1 discloses the use of a composition containing acrylate and particles obtained by modifying the surface of colloidal silica with methacryloxysilane as a photocurable coating material.

  However, the radical polymerization type cured coating material as described above has a problem that the curing reaction is inhibited by dissolved oxygen in the cured coating material, oxygen in the air, etc., and the curability near the coating film surface is poor. In particular, when performing thin film coating with a thickness of 1 μm or less, for example, it is highly necessary to perform a curing reaction in an inert gas atmosphere such as nitrogen. Therefore, development of a radical polymerization type coating composition that is excellent in wear resistance and curability and gives a transparent cured film, and is excellent in curability near the surface of the coating film even in normal air. Is strongly desired.

Patent Document 2 describes a curing system in which a polyvalent thiol is combined with a polymer having an alkenyl group. However, this curing system requires large amounts of polyvalent thiols. For this reason, in the coating composition of patent document 2, there exists a problem that storage stability worsens or it is inferior to transparency by presence of a large amount of polyvalent thiol.
Japanese Patent Publication No.62-21815 JP 2004-285113 A

  The present invention has been made in order to solve the above-described conventional problems, and the object of the present invention is curability, abrasion resistance, scratch resistance, transparency, and the vicinity of the coating film surface in normal air. An object of the present invention is to provide a high-quality optical film including a coating composition that provides a cured film having excellent curability and excellent storage stability, and a coating layer of such a coating composition.

  The coating composition of the present invention comprises (A) organic-inorganic composite fine particles; (B) polyfunctional (meth) acrylate; (C) polymerization initiator; (D) polyfunctional thiol.

  In preferable embodiment, the said polyfunctional thiol is 0.1-15 mass% with respect to the sum total of the said organic inorganic composite fine particle and the said polyfunctional (meth) acrylate in the solid content ratio.

  In a preferred embodiment, the organic-inorganic composite fine particles include core particles composed of inorganic core particles or organic-inorganic composites, and an organic substance bonded to at least a part of the surface of the core particles.

  In a more preferred embodiment, the organic-inorganic composite fine particles have a polymerizable functional group. In a more preferred embodiment, the polymerizable functional group is an ethylenically unsaturated group.

  In a preferred embodiment, the organic substance bonded to at least a part of the surface of the core particle is an organic polymer.

In a more preferred embodiment, the organic polymer is an acrylic polymer.
In a more preferred embodiment, the organic polymer has a polymerizable functional group in its side chain. In a more preferred embodiment, the polymerizable functional group is bonded to the main chain of the organic polymer via a urethane bond.

  According to another aspect of the present invention, an optical film is provided. This optical film includes a coating layer of the coating composition.

  According to another aspect of the present invention, a low refractive index coating composition is provided. This low refractive index coating composition is the coating composition, wherein the organic polymer has a portion containing a fluorine atom.

  According to another aspect of the present invention, an antireflection film is provided. This antireflection film includes a coating layer of the low refractive index coating composition.

  According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate includes a polarizer and the antireflection film.

  According to another aspect of the present invention, an optical filter for a plasma display is provided. The optical filter for plasma display includes a support and the antireflection film.

  According to another aspect of the present invention, an image display device is provided. The image display device includes at least one selected from the antireflection film, the polarizing plate, and the optical filter.

  According to this invention, it is set as the composition containing the mixing | blending which has not existed conventionally (A) organic-inorganic composite fine particle, (B) polyfunctional (meth) acrylate, (C) polymerization initiator, and (D) polyfunctional thiol. By providing a coating film having excellent curability, abrasion resistance, scratch resistance, transparency, and a cured film having excellent curability near the surface of the coating film in normal air, and having excellent storage stability. can do.

[A. Organic-inorganic composite fine particles
Any appropriate organic-inorganic composite fine particles can be employed as the organic-inorganic composite fine particles in the present invention. Preferably, fine particles having core particles composed of inorganic core particles or organic-inorganic composites, and organic substances bonded to at least a part of the surface of the core particles are exemplified. Any appropriate fine particles can be adopted as the fine particles having the core particles made of the inorganic core particles or the organic-inorganic composite and the organic substance bonded to at least a part of the surface of the core particles. For example, (1) using a silanol group of colloidal silica as described in JP-A-9-100111 and JP-A-2004-256653, an organic substance is made inorganic by using a silane coupling agent, an isocyanate compound, or the like. Fine particles obtained by combining with core particles, and (2) a metal oxide precursor (metal alkoxide, etc.) in the presence of a compound having a polysiloxane group (may be a polymer or not a polymer). Examples thereof include fine particles obtained by a condensation reaction.

  As described above, the organic-inorganic composite fine particles in the present invention are preferably fine particles having inorganic core particles or core particles made of an organic-inorganic composite and organic substances bonded to at least a part of the surface of the core particles. Among these, fine particles having a polymerizable functional group are preferable. This polymerizable functional group is preferably an ethylenically unsaturated group. This is because the production is easy and the curability of the particles is excellent.

  The organic substance bonded to at least a part of the surface of the core particle is more preferably an organic polymer. More preferably, the organic polymer has a polymerizable functional group in its side chain. In the present specification, “bonding between the core particle and the organic polymer” means that a chemical bond is formed between the organic polymer and the core particle, not physical adhesion. The chemical bond is generated means that, for example, when the composite fine particles are washed with a solvent, the organic polymer is not substantially detected in the washing solution. The organic polymer has a polymerizable functional group in its side chain. In other words, the polymerizable functional group is not directly bonded to the surface of the core particle, but an organic polymer is interposed between the polymerizable functional group and the core particle.

(A-1. Inorganic core particles)
The said inorganic core particle is particle | grains comprised from arbitrary appropriate inorganic substances (For example, a metal simple substance, an inorganic oxide, an inorganic carbonate, an inorganic sulfate, an inorganic phosphate). The inorganic substance is preferably an inorganic oxide. In the present specification, the “inorganic oxide” refers to various oxygen-containing metal compounds in which a metal element mainly forms a three-dimensional network through bonds with oxygen atoms. As the metal element constituting the inorganic oxide, for example, an element selected from Group II to VI of the Periodic Table of Elements is preferable,
An element selected from III to V groups is more preferable. Among these, an element selected from Si, Al, Ti, and Zr is particularly preferable. Most preferred is silica in which the metal element is Si. It is easy to manufacture and easy to obtain. The core particle may be composed of one kind of inorganic oxide or may be composed of two or more kinds of inorganic oxides.

  The core particle has any suitable shape (for example, spherical shape, needle shape, plate shape, scale shape, and crushed particle shape). The average particle diameter of the core particles is preferably 5 to 200 nm, more preferably 5 to 100 nm, and most preferably 5 to 50 nm. When the average particle diameter of the core particles is less than 5 nm, the surface energy of the composite fine particles becomes high, and the composite fine particles tend to aggregate. If the average particle diameter of the core particles exceeds 200 nm, the transparency of the resulting coating may be reduced.

  The variation coefficient (particle size distribution) of the particle diameter of the core particles is preferably 50% or less, more preferably 40% or less, and most preferably 30% or less. If the coefficient of variation exceeds 50% (if the particle size distribution of the core particles is too large), the resulting coating film surface becomes uneven and the smoothness of the coating film may be lost.

(A-2. Organic polymer)
The organic polymer is bonded to at least a part of the surface of the core particle. An organic polymer is bonded to the surface of the core particle, and an organic functional group (preferably, an ethylenically unsaturated group) is introduced into the polymer side chain (that is, organic between the polymerizable functional group and the core particle). By interposing a polymer), a much larger amount of functional groups can be introduced into the composite fine particles than in the past. As a result, a coating film having very excellent hardness can be obtained. In the present invention, a part of the organic polymer may be encapsulated in the core particles. In this case, moderate flexibility and toughness can be imparted to the core particles. The presence / absence of the organic polymer in the core particle is determined by, for example, measuring the specific surface area of the core particle after the composite fine particles are heated at 500 to 700 ° C. to thermally decompose the organic polymer, and the theoretical value of the specific surface area of the core particle ( It can be confirmed by comparing with (calculated from the diameter of the core particle measured by TEM or the like). Specifically, when the organic polymer is encapsulated in the core particle, a large number of pores are generated in the core particle due to the thermal decomposition of the organic polymer, so the specific surface area of the core particle after the thermal decomposition is lower than the theoretical value. Is also quite large.

  The organic polymer can have any suitable structure (eg, linear, branched, cross-linked structure). Specific examples of organic polymers include acrylic polymers, styrene polymers, olefin polymers (eg, polyethylene, polypropylene), polyesters (eg, polyethylene terephthalate), vinyl polymers (polyvinyl acetate, polyvinyl chloride), polychlorinated polymers. Examples include vinylidene and copolymers thereof. You may use the polymer which modified these partially by functional groups, such as an amino group, an epoxy group, a hydroxyl group, and a carboxyl group. Acrylic polymers are preferred. The acrylic polymer has an appropriate coating film forming ability and is suitable for use in a film forming composition such as a paint. Examples of the acrylic unit (repeating unit) in the acrylic polymer include a methyl (meth) acrylate unit and an ethyl (meth) acrylate unit. According to the acrylic polymer having such a repeating unit, the stain resistance of the coating can be improved.

  The molecular weight (number average molecular weight) of the organic polymer is preferably 200,000 or less, more preferably 50,000 or less, and most preferably 3,000 to 30,000. If the molecular weight is in such a range, a large amount of functional groups can be introduced into the side chain at appropriate intervals, so that composite fine particles having extremely excellent curability can be obtained, and the dispersion of the composite fine particles can be obtained. Stability can be maintained well.

  The organic polymer preferably has a polymerizable functional group in its side chain. In other words, it is preferable that the polymerizable functional group is not directly bonded to the surface of the core particle, but an organic polymer is interposed between the polymerizable functional group and the core particle. By adopting such a structure, it is possible to obtain composite fine particles having extremely excellent curability and capable of achieving both adhesion and dispersion stability. Preferably, the polymerizable functional group is an ethylenically unsaturated group. Specific examples of the ethylenically unsaturated group include a terminal vinyl group, an allyl group, a (meth) acryl group, an α-substituted acryl group, an ethylene group, and an acetylene group. These ethylenically unsaturated groups may be introduced singly into the organic polymer side chain, or may be introduced in combination of two or more.

  The polymerizable functional group may be directly bonded to the organic polymer, or may be bonded through any appropriate bond. Preferably, the polymerizable functional group is bonded to the organic polymer main chain via a urethane bond. In this case, the polymerizable functional group can be introduced with very high reaction efficiency without causing gelation or the like.

  The content of the polymerizable functional group in the composite fine particles is preferably 0.1 to 5 mmol / g, more preferably 0.7 to 3 mmol / g, per 1 g of the composite fine particles. With such a content, composite fine particles having an excellent balance between curability and dispersion stability can be obtained.

(A-3. Manufacturing method of organic-inorganic composite fine particles)
Arbitrary suitable manufacturing methods can be employ | adopted for the method of manufacturing the organic inorganic composite fine particle in this invention. As an example of a specific embodiment, a case where the organic-inorganic composite fine particles have a polymerizable functional group will be described. In one embodiment, a step of reacting a silicon-containing polymer having a functional group having active hydrogen and a polysiloxane group in the side chain with an isocyanate compound having a polymerizable functional group (preferably an ethylenically unsaturated group). And reacting the reaction product with a metal compound capable of forming a metal oxide by hydrolysis (Method 1). In another embodiment, a step of reacting a silicon-containing polymer having a functional group having active hydrogen and a polysiloxane group in a side chain with a metal compound capable of generating a metal oxide by hydrolysis; and a reaction product thereof And a step of reacting an isocyanate compound having a polymerizable functional group (preferably an ethylenically unsaturated group) (Method 2). Method 1 is preferred. This is because the reaction efficiency is high and the polymerizable functional group can be efficiently introduced into the side chain of the organic polymer on the surface of the composite fine particles. Hereinafter, for the sake of simplicity, Method 1 will be mainly described.

  The main chain of the silicon-containing polymer is mainly composed of carbon, and carbon atoms participating in the main chain bond occupy 50 to 100 mol% of the main chain, and the balance is N, O, S, Si, P, or the like. Those composed of elements are preferred for reasons such as availability. The structure and specific examples of the main chain of the silicon-containing polymer are as described for the organic polymer in the above section B. The organic polymer described in the above section A-2 is derived from the main chain of the silicon-containing polymer.

  Representative examples of the functional group having active hydrogen include a hydroxyl group, a carboxyl group, an amino group, and a mercapto group. Hydroxyl groups are preferred. This is because the introduction of the silicon-containing polymer into the side chain is easy and the reactivity with the isocyanate compound is excellent. The functional group may be directly bonded to the main chain of the silicon-containing polymer, or may be bonded via any appropriate group (for example, a methylene group).

  Content of the said functional group in a silicon-containing polymer becomes like this. Preferably it is 10-80 mol%, More preferably, it is 30-60 mol%. Within such a range, composite fine particles having a polymerizable functional group with a desired content can be obtained.

In the present specification, the “polysiloxane group” refers to a group containing a number of siloxane bonds that can form core particles capable of obtaining the effects of the present invention. Therefore, the “polysiloxane group” is not only a group in which two or more Si atoms are connected in a linear or branched manner by a polysiloxane bond (Si—O—Si—O bond), but also a polyfunctional siloxane. It also includes a group containing one Si atom constituting a bond (for example, (linking chain) -R-Si- (OR) ₃ : R is any suitable substituent). Preferably, the polysiloxane group has a structure containing a polysiloxane bond and containing at least one Si-OR ¹ group. Here, R ¹ is at least one group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, and a substituted or unsubstituted acyl group, and when R ¹ is plural in one molecule, R ¹ May be the same or different. The number of carbon atoms of the alkyl group or acyl group as R ¹ may be an appropriate number depending on the purpose. The carbon number is preferably 1-5. This is because the hydrolysis rate of the R ¹ O group is fast. Specific examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an iso-propyl group, a butyl group, a sec-butyl group, a tert-butyl group, and a pentyl group. Specific examples of the acyl group having 1 to 5 carbon atoms include an acetyl group and a propionyl group. Specific examples of the substituent for the alkyl group or acyl group include alkoxy groups such as methoxy group and ethoxy group; acyl groups such as acetyl group and propionyl group; and halogens such as chlorine and bromine. R ¹ is preferably a hydrogen atom, a methyl group or an ethyl group, and most preferably a methyl group. This is because the hydrolysis and condensation rate of the R ¹ O group is further increased.

Any appropriate number of Si atoms contained in the polysiloxane group can be adopted depending on the purpose. The average number of Si atoms per polysiloxane group is preferably 4 or more, and more preferably 11 or more. It is because it becomes possible to contain many said Si-OR ¹ groups. The average number of R ¹ O groups in ^one Si—OR group is preferably 5 or more, more preferably 20 or more, per molecule of silicon-containing polymer. Since the R ¹ O group is a functional group that can be hydrolyzed and / or condensed, the greater the number of R ¹ O groups, the more reactive and condensing reaction points, and the stronger the bond between the polymer and the core particles.

  Specific examples of the polysiloxane group include a polymethylmethoxysiloxane group, a polyethylmethoxysiloxane group, a polymethylethoxysiloxane group, a polyethylethoxysiloxane group, a polyphenylmethoxysiloxane group, and a polyphenylethoxysiloxane group.

It is preferable that all the Si atoms in the polysiloxane group are bonded only to the R ¹ O group except for the bond to the organic chain or the polysiloxane bond (Si—O—Si bond). As a result, the ionicity of the Si atom is further increased. As a result, the hydrolysis / condensation rate of the R ¹ O group is increased, and the reactive sites in the silicon-containing polymer are increased, thereby obtaining core particles having a stronger skeleton. Because. Specific examples of such a polysiloxane group include a polydimethoxysiloxane group, a polydiethoxysiloxane group, a polydiiso-propoxysiloxane group, and a poly n-butoxysiloxane group.

  The Si atom in the polysiloxane group may be directly bonded to the organic chain (for example, a Si—C bond may be formed), or may be bonded through any appropriate group or atom ( For example, a Si—O—C bond may be formed). Preferably, the Si atom is directly bonded to the organic chain. This is because the binding site is less susceptible to undesired reactions (for example, hydrolysis and exchange reaction).

  Content of the said polysiloxane group in a silicon-containing polymer becomes like this. Preferably it is 0.5-10 mol%, More preferably, it is 0.5-5 mol%. If it is such a range, the core particle which has desired intensity | strength, a shape, size, etc. will be obtained.

  The molecular weight (number average molecular weight) of the silicon-containing polymer is preferably 200,000 or less, more preferably 50,000 or less, and particularly preferably 10,000 to 30,000. If the molecular weight is too high, it may not dissolve in the organic solvent. If the molecular weight is too low, the amount of polymerizable functional groups introduced may be insufficient.

  The silicon-containing polymer can be produced by any appropriate method. Specific examples include a method of radical (co) polymerizing a radically polymerizable monomer in the presence of a polymerizable polysiloxane. Here, the polymerizable polysiloxane is obtained by partially hydrolyzing and condensing a silane compound and a polymerizable functional group-containing silane coupling agent.

  Any appropriate silane compound can be adopted as the silane compound as long as desired core particles can be obtained. Specific examples of the silane compound include tetramethoxysilane, tetraethoxysilane, ethoxytrimethoxysilane, triethoxymethoxysilane, diethoxydimethoxysilane, tetraiso-propoxysilane, tetrabutoxysilane, trimethoxyhydroxysilane, and triethoxyhydroxysilane. , Methoxytriacetoxysilane, dimethoxydiacetoxysilane, trimethoxyacetoxysilane, and tetraacetoxysilane. Tetramethoxysilane is particularly preferred. A silane compound may be used independently and may be used in combination of 2 or more type.

  Specific examples of the polymerizable functional group-containing silane coupling agent include acryloxypropyltrimethoxysilane, acryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, and methacryloxypropyltriethoxysilane. The polymerizable functional group-containing silane coupling agent may be used alone or in combination of two or more.

  The hydrolysis / condensation reaction between the silane compound and the polymerizable functional group-containing silane coupling agent may be performed under any appropriate conditions. Typically, the hydrolysis / condensation reaction is performed in a solution. Here, the solution is a solution obtained by dissolving a silane compound and a polymerizable functional group-containing silane coupling agent in water and / or an organic solvent. Specific examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, dioxane and ethyl ether; Examples include alcohols such as methanol, ethanol, iso-propyl alcohol, n-butanol, ethylene glycol and propylene glycol; and halogenated hydrocarbons such as methylene chloride and chloroform. An organic solvent may be used independently and may be used in combination of 2 or more type.

  The hydrolysis / condensation reaction may be carried out without a catalyst or using a catalyst. Preferably, a catalyst is used. Examples of the catalyst include an acidic catalyst and a basic catalyst. Specific examples of the acidic catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; organic acids such as acetic acid, propionic acid, oxalic acid, and p-toluenesulfonic acid; and acidic ion exchange resins. Specific examples of basic catalysts include ammonia; organic amine compounds such as triethylamine and tripropylamine; alkali metal compounds such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, sodium hydroxide, and potassium hydroxide. A basic ion exchange resin or the like. Acidic catalysts are preferred. This is because it is easy to control partial hydrolysis / condensation reactions. A catalyst may be used independently and may be used in combination of 2 or more type.

  The reaction temperature of the hydrolysis / condensation reaction is preferably 60 to 100 ° C., and the total reaction time is preferably 3 to 6 hours. The reaction temperature may be controlled to be constant or may be changed stepwise. As described above, a polymerizable polysiloxane is obtained.

  Next, a radically polymerizable monomer is radically (co) polymerized in the presence of the polymerizable polysiloxane to obtain a silicon-containing polymer. Examples of the radical polymerizable monomer include acrylic monomers, styrene monomers, olefin monomers, vinyl monomers, and monomers that form polyester (for example, dicarboxylic acid and diamine). Acrylic monomers are preferred. This is because composite fine particles having an appropriate coating film forming ability can be obtained. Specific examples of acrylic monomers include acrylic carboxylic acids such as (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth) acrylate. (Meth) acrylic acid such as n-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl tridecyl (meth) acrylate Esters: Epoxy group-containing (meth) acrylic esters such as glycidyl (meth) acrylate; (meth) acrylonitrile, (meth) acrylamide, N-methylolacrylamide, N-butoxymethylacrylamide, diacetone acrylamide, (meth) acrylic acid 2-ethyl sulfonateAn acrylic monomer may be used independently and may be used in combination of 2 or more type. In the present invention, it is preferable to copolymerize the acrylic monomer and an acrylic monomer having a functional group containing active hydrogen. A typical example of an acrylic monomer having a functional group containing active hydrogen is a hydroxyl group-containing acrylic monomer. Specific examples of the hydroxyl group-containing acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and caprolactone-modified hydroxy (meth) acrylate. (Meth) acrylic acid monoester of ester diol obtained from phthalic acid and propylene glycol.

  The ratio (molar ratio) of acrylic monomer / functional group (for example, hydroxyl group) -containing acrylic monomer in the copolymerization is preferably 90/10 to 20/80, more preferably 70/30 to 40/60. When the ratio of the functional group-containing acrylic monomer is too small, the amount of the polymerizable functional group introduced into the composite fine particles becomes insufficient, and as a result, the curability of the composite fine particles may be insufficient. If the ratio of the functional group-containing acrylic monomer is too large, the stability of the silicon-containing polymer may be insufficient.

  Arbitrary appropriate conditions can be employ | adopted as polymerization conditions of a radically polymerizable monomer (for example, acrylic monomer). In this way, a polymer (silicon-containing polymer) having a functional group containing active hydrogen (for example, a hydroxyl group) and a polysiloxane group in the side chain is obtained.

Next, the silicon-containing polymer is reacted with an isocyanate compound having a polymerizable functional group (preferably an ethylenically unsaturated group) to introduce a polymerizable functional group into the polymer side chain. More specifically, a polymerizable functional group derived from an isocyanate compound is introduced into the polymer side chain by an addition reaction between a functional group (for example, a hydroxyl group) having active hydrogen in the polymer side chain and an isocyanate group. Examples of the polymerizable functional group contained in the isocyanate group include an acryloyl group and a methacryloyl group. Specific examples of the isocyanate compound having a polymerizable functional group include acryloxymethyl isocyanate, methacryloxymethyl isocyanate, acryloxyethyl isocyanate, methacryloxyethyl isocyanate, acryloxypropyl isocyanate, methacryloxypropyl isocyanate, 1,1-bis ( Acryloxymethyl) ethyl isocyanate. A typical reaction scheme is as follows. Arbitrary appropriate conditions can be employ | adopted as reaction conditions of the said addition reaction. In this way, a silicon-containing polymer having a polymerizable functional group in the side chain is obtained.

  Finally, a composite fine particle is obtained by reacting the silicon-containing polymer having a polymerizable functional group in the side chain with a metal compound capable of generating a metal oxide by hydrolysis. A metal compound can be converted into a metal oxide by hydrolysis and further condensed with a polysiloxane group in a polymer side chain to form a three-dimensional network. As a result, core particles having a strong skeleton are formed, and composite fine particles are obtained. Specific examples of such a metal compound include metal halides, metal nitrates, metal sulfates, metal ammonium salts, organometallic compounds, alkoxy metal compounds, and derivatives thereof. A metal compound may be used independently and may be used in combination of 2 or more type.

Preferably, the metal compound is a compound represented by the following general formula (1) or a derivative thereof:
(R ² O) _m MR ³ _3n-m (1)
In the formula (1), M is a group III, group IV or group V metal element of the periodic table, and is preferably at least one metal element selected from Si, Al, Ti and Zr. Each R ² is independently a hydrogen atom, or a substituted or unsubstituted alkyl group or acyl group. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an iso-propyl group, a butyl group, a sec-butyl group, a tert-butyl group, and a pentyl group. Specific examples of the acyl group include an acetyl group and a propionyl group. R ² is particularly preferably a hydrogen atom, a methyl group or an ethyl group, and most preferably a methyl group. This is because the hydrolysis and condensation rate of the R ² O group is fast. R ³ is each independently a substituted or unsubstituted alkyl group, cycloalkyl group, aryl group or aralkyl group. The alkyl group is the same as described above. Specific examples of the cycloalkyl group include a cyclohexyl group. Specific examples of the aryl group include a phenyl group, a tolyl group, and a xylyl group. Specific examples of the aralkyl group include a benzyl group. Examples of the substituent for the alkyl group, cycloalkyl group, aryl group and aralkyl group include alkoxy groups such as methoxy group and ethoxy group, amino group, nitro group, epoxy group and halogen. n is the valence of the metal element M, and m is an integer of 1 to n. When there are a plurality of R ² and / or R ³ in one molecule, R ² and / or R ³ may be the same or different.

  Specific examples of the metal compound include methyltriacetoxysilane, dimethyldiacetoxysilane, trimethylacetoxysilane, tetraacetoxysilane, tetramethoxysilane, tetraethoxysilane, tetraiso-proxysilane, tetrabutoxysilane, methyltrimethoxysilane, Phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydimethylsilane, dimethoxymethylphenylsilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldiethoxysilane, dimethoxydiethoxysilane, aluminum trimethoxide, aluminum triethoxide, aluminum triiso -Propoxide, aluminum tributoxide, dimethylaluminum methoxide, tetramethoxytitanium, tetraeth Xititanium, tetraiso-propoxytitanium, tetrabutoxytitanium, tetra (2-ethylhexyloxy) titanium, diethoxysibutoxytitanium, iso-proxy titanium trioctarate, diiso-propoxytitanium diacrylate, tributoxytitanium stearate, Examples include zirconium acetate, tetramethoxyzirconium, tetraethoxyzirconium, tetraiso-propoxyzirconium, and tetrabutoxyzirconium. Specific examples of the derivative of the metal compound represented by the general formula (1) include diiso-propoxytitanium diacetylacetonate, oxytitanium diacetylacetonate, dibutoxytitanium bistriethanolamate, dihydroxytitanium dilactoate, zirconium acetylacetonate. , Acetylacetone zirconium butoxide, triethanolamine zirconium butoxide, and aluminum acetylacetonate.

  The metal compound is particularly preferably a silane compound in which M is Si in the general formula (1) and derivatives thereof. Most preferred are tetramethoxysilane and tetraethoxysilane. This is because it is easily available and does not contain halogen or the like, so that it does not adversely affect the physical properties of the production apparatus and the final product.

  Arbitrary appropriate conditions can be employ | adopted as reaction conditions of the said silicon-containing polymer and the said metal compound. Typically, the reaction is performed in the presence of an organic solvent and / or water. Therefore, the composite fine particles are typically obtained in the form of a dispersion. Specific examples of the solvent are as listed above.

  The ratio of core particles / organic polymer in the composite fine particles obtained as described above is preferably 90/10 to 40/60, more preferably 80/20 to 50/50. When the ratio of the core particles is too high, the introduction amount of the polymerizable functional group may be insufficient, and as a result, the curability of the composite fine particles may be insufficient. When the ratio of the organic polymer is too high, the hardness of the obtained coating film may be insufficient.

[B. Multifunctional (meth) acrylate]
As the polyfunctional (meth) acrylate in the present invention, any appropriate (meth) acrylate may be adopted as long as it has two or more (meth) acrylate groups in the molecule. As specific examples, for example, 1,6-hexanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (Meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, poly (butanediol) di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, triethylene glycol di Di (meth) acrylates such as (meth) acrylate, triisopropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, bisphenol A di (meth) acrylate; Trimethylo Tri (meth) acrylates such as propanetri (meth) acrylate, pentaerythritol monohydroxytri (meth) acrylate, trimethylolpropane triethoxytri (meth) acrylate; pentaerythritol tetra (meth) acrylate, di-trimethylolpropanetetra Tetra (meth) acrylates such as (meth) acrylate; Penta (meth) acrylates such as dipentaerythritol (monohydroxy) penta (meth) acrylate; Hexa (meth) acrylates such as dipentaerythritol hexa (meth) acrylate ; Only one type of polyfunctional (meth) acrylate may be used, or two or more types may be used in combination.

[C. Polymerization initiator)
As the polymerization initiator in the present invention, any appropriate type of initiator may be employed depending on the purpose. Specific examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator. A polymerization initiator may be used independently and may be used in combination of 2 or more type. In the coating composition of the present invention, a photopolymerization initiator is preferred. Specific examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, benzophenone compounds, anthraquinone compounds, phosphine oxide compounds, xanthone compounds, thioxanthone compounds, and ketal compounds. Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl) Propionyl) -benzyl] -fe L} -2-methylpropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholinophenyl) -butan-1-one, benzophenone, p-phenylbenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) ) -Phenylphosphine oxide, 2, , 6-Trimethylbenzoyldiphenylphosphine oxide, xanthone, thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl Examples include ketal and acetophenone dimethyl ketal. Examples of commercially available products include Irgacure 127, 184, 369, 379, 500, 651, 784, 819, 851, 907, 1300, 1800, 1870, 2959, OXE01, OXE02, DAROCUR1173 (above, manufactured by Ciba Specialty Chemicals), etc. Is mentioned. The polymerization initiator is contained in the composition at a ratio of preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the solid content of the coating composition.

[D. Multifunctional thiol]
As the polyfunctional thiol in the present invention, any appropriate kind of polyfunctional thiol can be adopted depending on the purpose. Only one type of polyfunctional thiol may be used, or two or more types may be used in combination.

  Any appropriate polyfunctional thiol can be adopted as the polyfunctional thiol as long as it is a compound having two or more mercapto groups in one molecule.

  The polyfunctional thiol is preferably a thiol compound having a specific mercapto group-containing group, wherein the mercapto group-containing group has a carbon atom at the α-position and / or β-position with respect to the mercapto group (-SH). It is a structure having a substituent. At least one of the substituents is preferably an alkyl group. The “structure in which the carbon atom at the α-position and / or β-position with respect to the mercapto group (—SH) has a substituent” means a structure branched at the α-position and / or β-position with respect to the mercapto group, That is, it means a so-called branched structure in which the α-position and / or β-position carbon of the mercapto group is bonded to three or more atoms other than hydrogen. The case where “at least one of the substituents is an alkyl group” means that at least one of the substituents other than the main chain at the α-position and / or β-position with respect to the mercapto group is an alkyl group. The “main chain” means the longest chain structure composed of atoms other than hydrogen containing a mercapto group.

  The mercapto group-containing group is preferably a group represented by the general formula (1).

上記一般式（１）中、Ｒ^１およびＲ^２は各々独立して水素原子または炭素数１〜１０のアルキル基を表し、その少なくとも一方はアルキル基である。すなわち、Ｒ^１およびＲ^２がともに水素原子となることはない。なお、Ｒ^１およびＲ^２がともにアルキル基の場合は、両者は同じであっても異なっていても良い。ｍは０または１〜２の整数、好ましくは０または１であり、ｎは０または１、好ましくは０である。

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, at least one of which is an alkyl group. That is, R ¹ and R ² are not both hydrogen atoms. In addition, when both R ¹ and R ² are alkyl groups, both may be the same or different. m is 0 or an integer of 1 to 2, preferably 0 or 1, and n is 0 or 1, preferably 0.

The alkyl group having 1 to 10 carbon atoms that can be adopted by R ¹ and R ² may be linear or branched, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and iso-propyl. Group, n-butyl group, iso-butyl group, tert-butyl group, n-hexyl group and n-octyl group. Preferably, it is a methyl group or an ethyl group.

The polyfunctional thiol is more preferably a carboxylic acid derivative structure such that the mercapto group-containing group represented by the general formula (1) is represented by the following general formula (2).

Such a polyfunctional thiol is preferably an ester of a mercapto group-containing carboxylic acid represented by the following general formula (3) and an alcohol.

  As said alcohol, polyfunctional alcohol is preferable.

  Examples of the polyfunctional alcohol include alkylene glycol (wherein the alkylene group preferably has 2 to 10 carbon atoms, and the carbon chain thereof may be branched), diethylene glycol, glycerin, dipropylene glycol, trimethylol. Examples include propane, pentaerythritol, and dipentaerythritol. Examples of the alkylene glycol include ethylene glycol, trimethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, and tetramethylene glycol.

  The polyfunctional alcohol is preferably alkylene glycol having 2 carbon atoms in the alkylene main chain such as ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, and trimethylolpropane.

  Examples of the mercapto group-containing carboxylic acid of the general formula (2) include 2-mercaptopropionic acid, 3-mercaptobutyric acid, 2-mercaptoisobutyric acid, and 3-mercaptoisobutyric acid.

  Specific examples of the polyfunctional thiol having the structure of the general formula (1) include the following compounds.

  Examples of the hydrocarbon dithiol include 2,5-hexanedithiol, 2,9-decanedithiol, and 1,4-bis (1-mercaptoethyl) benzene.

  Examples of the compound having an ester bond structure include di (1-mercaptoethyl ester) phthalate, di (2-mercaptopropyl ester) phthalate, di (3-mercaptobutyl ester) phthalate, and di (3-mercapto phthalate). Isobutyl ester).

  The polyfunctional thiol having the structure represented by the general formula (1) is preferably ethylene glycol bis (3-mercaptobutyrate), propylene glycol bis (3-mercaptobutyrate), diethylene glycol bis (3-mercaptobutyrate), for example. ), Butanediol bis (3-mercaptobutyrate), octanediol bis (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptobutyrate), pentaerythritol tetrakis (3-mercaptobutyrate), dipentaerythritol Hexakis (3-mercaptobutyrate), ethylene glycol bis (2-mercaptopropionate), propylene glycol bis (2-mercaptopropionate), diethylene glycol bis (2-mercaptotop) Pionate), butanediol bis (2-mercaptopropionate), octanediol bis (2-mercaptopropionate), trimethylolpropane tris (2-mercaptopropionate), pentaerythritol tetrakis (2-mercaptopropionate) ), Dipentaerythritol hexakis (2-mercaptopropionate), ethylene glycol bis (3-mercaptoisobutyrate), propylene glycol bis (3-mercaptoisobutyrate), diethylene glycol bis (3-mercaptoisobutyrate) , Butanediol bis (3-mercaptoisobutyrate), octanediol bis (3-mercaptoisobutyrate), trimethylolpropane tris (3-mercaptoisobutyrate), pentaerythris Tall tetrakis (3-mercaptoisobutyrate), dipentaerythritol hexakis (3-mercaptoisobutyrate), ethylene glycol bis (2-mercaptoisobutyrate), propylene glycol bis (2-mercaptoisobutyrate), diethylene glycol Bis (2-mercaptoisobutyrate), butanediol bis (2-mercaptoisobutyrate), octanediol bis (2-mercaptoisobutyrate), trimethylolpropane tris (2-mercaptoisobutyrate), pentaerythritol tetrakis (2-mercaptoisobutyrate), dipentaerythritol hexakis (2-mercaptoisobutyrate), ethylene glycol bis (4-mercaptovalerate), propylene glycol bis (4 -Mercaptoisovalerate), diethylene glycol bis (4-mercaptovalerate), butanediol bis (4-mercaptovalerate), octanediol bis (4-mercaptovalerate), trimethylolpropane tris (4-mercaptovalerate) , Pentaerythritol tetrakis (4-mercaptovalerate), dipentaerythritol hexakis (4-mercaptovalerate), ethylene glycol bis (3-mercaptovalerate), propylene glycol bis (3-mercaptovalerate), diethylene glycol bis ( 3-mercaptovalerate), butanediol bis (3-mercaptovalerate), octanediol bis (3-mercaptovalerate), trimethylolpropane tris (3-mercaptobarate) Rate), pentaerythritol tetrakis (3-mercapto valerate), dipentaerythritol hexakis (3-mercapto valerate) and the like.

  Any appropriate molecular weight can be adopted as the molecular weight of the polyfunctional thiol. Preferably it is 200-1000.

  Arbitrary appropriate manufacturing methods can be employ | adopted as a manufacturing method of the said polyfunctional thiol. For example, an ester of a mercapto group-containing carboxylic acid and an alcohol is obtained by reacting the mercapto group-containing carboxylic acid represented by the general formula (2) and an alcohol according to a conventional method to form an ester. be able to. About the conditions of ester reaction, it can select suitably from arbitrary appropriate reaction conditions.

  Any appropriate commercially available product may be used as the polyfunctional thiol. For example, “Karenz MT” series manufactured by Showa Denko KK, specifically, for example, “Karenz MT BD1”, “Karenz MT NR1”, and “Karenz MT PE1” can be mentioned.

[E. Coating composition)
(E-1. Coating composition)
The coating composition of this invention contains the said organic inorganic composite fine particle, the said polyfunctional (meth) acrylate, the said polymerization initiator, and the said polyfunctional thiol. If necessary, it may further contain a solvent.

  In the coating composition of the present invention, the organic / inorganic composite fine particles are contained in an amount of preferably 10 to 500 parts by mass, more preferably 20 to 200 parts by mass with respect to 100 parts by mass of the polyfunctional (meth) acrylate. By setting the content ratio of the organic / inorganic composite fine particles and the polyfunctional (meth) acrylate in the coating composition of the present invention within the above range, the dispersion stability is excellent and the curability, wear resistance, and scratch resistance are excellent. It can be set as the coating composition which gives the cured film which was excellent in compatibility and was excellent.

  In the coating composition of the present invention, the polyfunctional thiol is preferably 0.1 to 15% by mass, more preferably 0.1% by mass with respect to the total of the organic-inorganic composite fine particles and the polyfunctional (meth) acrylate, as a solid content ratio. It is 5-10 mass%, More preferably, it is 1-5 mass%. By making the content ratio of the polyfunctional thiol in the coating composition of the present invention within the above range, the dispersion stability is excellent, and the curability, abrasion resistance, scratch resistance, transparency, and normal air Thus, a cured film having excellent curability near the surface of the coating film can be obtained, and a coating composition having excellent storage stability can be obtained. If the content ratio of the polyfunctional thiol in the coating composition of the present invention is too large, there may be a problem in storage stability, the design freedom of the coating composition may be constrained, a bad odor may occur, May be worse.

  Any appropriate solvent can be adopted as the solvent. Specific examples include, for example, aromatic hydrocarbons such as benzene, toluene and xylene; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, dioxane and ethyl ether; methanol , Ethanol, iso-propyl alcohol, n-butanol, ethylene glycol, propylene glycol and other alcohols; and halogenated hydrocarbons such as methylene chloride and chloroform. A solvent may be used only by 1 type and may use 2 or more types together.

  The coating composition of the present invention may further contain any appropriate monofunctional polymerizable compound depending on the purpose. Specific examples of the monofunctional polymerizable compound include acrylamide, (meth) acryloylmorpholine, 7-amino-3,7-dimethyloctyl (meth) acrylate, isobutoxymethyl (meth) acrylate, and isobornyloxyethyl (meth). Acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethyldiethylene glycol (meth) acrylate, t-octyl (meth) acrylamide, diacetone (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) Acrylate, lauryl (meth) acrylate, dicyclopentadiene (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, N, N-dimethyl (meth) acrylamide Tetrachlorophenyl (meth) acrylate, 2-tetrachlorophenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tetrabromophenyl (meth) acrylate, 2-tetrabromophenoxyethyl (meth) acrylate, 2-trichlorophenoxyethyl (Meth) acrylate, tribromophenyl (meth) acrylate, 2-tribromophenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, vinylcaprolactam, N-vinylpyrrolidone, Phenoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, pentachlorophenyl (meth) acrylate, pentabromophenyl (meth) acrylate , Polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, bornyl (meth) acrylate, and compounds represented by methyl triethylene diglycol (meth) acrylate.

  The coating composition of the present invention may further contain any appropriate additive depending on the purpose. Specific examples of additives include leveling agents, pigments, pigment dispersants, UV absorbers, antioxidants, viscosity modifiers, light stabilizers, metal deactivators, peroxide decomposing agents, fillers, and reinforcement. Agent, plasticizer, lubricant, anticorrosive agent, rust inhibitor, emulsifier, mold release agent, fluorescent whitening agent, organic flame retardant, inorganic flame retardant, anti-dripping agent, melt flow modifier, electrostatic Examples thereof include an inhibitor, a slipping imparting agent, an adhesion imparting agent, an antifouling agent, a surfactant, an antifoaming agent, a polymerization inhibitor, a photosensitizer, a surface improver, and a silane coupling agent. In addition, when using an ultraviolet absorber, it cannot be overemphasized that it is used in the quantity of the grade which does not inhibit the polymerization (curing) reaction of organic-inorganic composite fine particles and polyfunctional (meth) acrylate.

  The coating composition of the present invention may further contain any appropriate organic or inorganic fine particles. Typically, such organic or inorganic fine particles are used to impart functions (for example, refractive index adjustment, conductivity, antiglare property) according to the purpose to the obtained coating layer. Specific examples of fine particles useful for increasing the refractive index of the coating layer and imparting conductivity include zinc oxide, titanium oxide, zirconium oxide, aluminum oxide, tin oxide, tin-doped indium oxide, antimony-doped tin oxide, indium-doped zinc oxide, Examples include indium oxide and antimony oxide. Specific examples of the fine particles useful for lowering the refractive index of the coating layer include magnesium fluoride, silica, and hollow silica. Specific examples of the fine particles useful for imparting antiglare properties include inorganic particles such as calcium carbonate, barium sulfate, talc and kaolin; silicon resin, melamine resin, benzoguanamine resin, acrylic resin, polystyrene resin and the like in addition to the fine particles described above. Organic fine particles such as these copolymer resins can be mentioned. These fine particles may be used alone or in combination of two or more.

  The coating composition of the present invention is, for example, a hard coating agent such as a transfer foil film, a plastic optical component, a touch panel, a film-type liquid crystal element, a plastic molding, a low refractive index coating agent for an antireflection film, and a coating agent for a light diffusion film. Can be suitably used.

The coating composition of the present invention is less susceptible to inhibition of the curing reaction by dissolved oxygen in the composition or oxygen in the air. For this reason, it is excellent in curability near the coating film surface. In addition, even if the curing reaction is not performed in an inert gas atmosphere such as nitrogen (for example, in normal air or in an atmosphere with a high oxygen concentration of 1000 ppm or more), it has excellent curability near the coating surface and is practical. It is possible to provide a coating film having appropriate hardness and scratch resistance. Such an effect is particularly useful when performing thin film coating with a thickness of 1 μm or less, for example. Further, the organic / inorganic composite fine particles in the coating composition of the present invention have inorganic core particles and an organic polymer bonded to at least a part of the surface of the core particles, and the organic polymer is polymerizable in the side chain. In the case of using organic-inorganic composite fine particles having a functional group, in which the polymerizable functional group is bonded to the organic polymer main chain via a urethane bond, the above effect is further exhibited. There is a case.
In the coating composition of the present invention, the ratio of the inorganic content in the solid content is preferably 25 to 60% by mass, more preferably 30 to 55% by mass, and further preferably 35 to 50% by mass. In the coating composition of the present invention, if the proportion of the inorganic content in the solid content is too large, the scratch resistance of the coating layer may be reduced. In the coating composition of the present invention, if the proportion of the inorganic content in the solid content is too small, the hardness of the coating layer may be lowered.

(E-2. Low refractive index coating composition)
As described above, the coating composition of the present invention can be suitably used as a low refractive index coating agent. In the present specification, such a composition is referred to as a “low refractive index coating composition”. The refractive index at a wavelength of 550 nm of a film having a thickness of 0.1 μm formed by the low refractive index coating composition of the present invention is preferably 1.25 to 1.40, more preferably 1.25 to 1. 35. By using the organic / inorganic composite fine particles in the present invention, such refractive index is caused by voids in the organic / inorganic composite fine particles and / or in the film formed from the low refractive index coating composition containing the organic / inorganic composite fine particles. Is expressed.

  The organic / inorganic composite fine particles are basically as described above, but when used in a low refractive index coating composition, the organic polymer preferably has a portion containing a fluorine atom. This is because the refractive index of the organic-inorganic composite fine particles is lowered, and the refractive index of the coating film can be further lowered. Such organic-inorganic composite fine particles can be obtained by copolymerizing a radical polymerizable monomer containing a fluorine atom when producing a silicon-containing polymer. The radically polymerizable monomer containing a fluorine atom can be copolymerized in a proportion of preferably 3 to 95 parts by mass, more preferably 5 to 80 parts by mass with respect to 100 parts by mass of the total amount of the radical polymerizable monomer. If it is less than 3 parts by mass, there is a possibility that it does not sufficiently contribute to lowering the refractive index. When it exceeds 95 parts by mass, the particles tend to aggregate. As the radical polymerizable monomer containing a fluorine atom, an acrylic monomer having a perfluoroalkyl group is preferred. As the perfluoroalkyl group, a perfluoromethyl group, a perfluoroethyl group, a perfluorobutyl group, a perfluorohexyl group, a perfluorooctyl group, a perfluorodecyl group, a perfluorododecyl group, and a perfluorotetradecyl group are preferable. Such a monomer may be used independently and may be used in combination of 2 or more type. Specific examples of the acrylic monomer having a fluorine atom include 2,2,2-trifluoroethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate.

  In the low refractive index coating composition, the organic / inorganic composite fine particles are preferably composed of 100 to 500 parts by mass, more preferably 100 to 300 parts by mass with respect to 100 parts by mass of the polyfunctional (meth) acrylate. Contained in the product. If it is 100 parts by mass or less, there is a possibility that voids in the coating are not filled with polyfunctional (meth) acrylate and the refractive index is not lowered. If it is 500 parts by mass or more, the scratch resistance of the film may be insufficient.

[F. Optical film)
The optical film of the present invention includes a coating layer of the coating composition. Typically, this optical film includes a substrate and a coating layer. The coating layer is typically formed by applying the coating composition and then drying and curing. A typical example of the substrate is a plastic film. Specific examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl Alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluororesin film, nylon A film, an acrylic resin film, etc. are mentioned. A polyethylene terephthalate film, a polyethylene naphthalate film, a triacetyl cellulose film, a polycarbonate film, and an acrylic resin film are preferable. It is because it is easily available and excellent in transparency. The base material may be a sheet shape or a plate shape depending on the application.

  Preferably, the substrate can be subjected to any appropriate surface treatment depending on the purpose. Specific examples of surface treatment include surface concavo-convex treatment by sandblasting, solvent treatment, etc .; surface oxidation treatment such as corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment; resin composition For example, primer treatment with a product.

  Any appropriate application method can be adopted as the application method of the coating composition. Specific examples include spin coating, dipping, spraying, slide coating, bar coating, roll coating, gravure coating, meniscus coating, flexographic printing, screen printing, and bead coating.

Arbitrary appropriate methods and conditions can be employ | adopted as said drying and hardening method. Typically, after applying the coating composition, the solvent is evaporated and dried at 0 to 200 ° C., and a curing treatment is performed with heat and / or radiation. In the case of radiation, it is preferable to use ultraviolet rays or electron beams. When using the coating composition of this invention, the hardening process by an ultraviolet-ray is especially preferable. In this case, the irradiation amount of ultraviolet rays is preferably 10 to 10,000 mJ / cm ² , more preferably 100 to 2000 mJ / cm ² . In one embodiment, the ultraviolet irradiation is performed in a state where part or all of the atmosphere is replaced with an inert gas. As a result, oxygen inhibition at the surface can be suppressed. As the inert gas, nitrogen gas is preferable. The thickness of the coating layer to be formed can vary depending on the purpose, but is preferably 50 nm to 100 μm.

  Specific examples of the optical film include a hard coat film, an antiglare film, an antireflection film, a polarizing plate, an optical filter, and a light diffusion film used in an image display device. Specific examples of the image display device include a liquid crystal display device (LCD), a cathode ray tube display device (CRT), a plasma display panel (PDP), and an electroluminescence display (ELD). Hereinafter, typical optical films will be specifically described.

(F-1. Hard coat film)
In one embodiment, the optical film of the present invention is a hard coat film. The hard coat film is a film imparted with physical strength by applying the above coating composition to a substrate and then drying and curing to form a hard coat layer.

  The thickness of the hard coat layer can be appropriately designed according to the application. The thickness of the hard coat layer is preferably 1 to 10 μm, more preferably 1 to 5 μm. The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. If necessary, the hard coat film may contain any appropriate additive in the substrate and / or the hard coat layer, and further has any appropriate coating layer on the surface of the hard coat layer. Also good. The coating layer may be a single layer or two or more layers. By using the additive and / or the coating layer, for example, performance such as antistatic property, antifouling property, slipperiness and antiglare property can be imparted. Alternatively, antiglare properties can be imparted by forming irregularities on the surface of the hard coat layer. The hard coat layer imparted with the antiglare property can be suitably used, for example, as an antiglare layer of an antireflection film. A film having a hard coat layer imparted with an antiglare property can be suitably used as an antiglare film, for example. Furthermore, such a hard coat film can also be used as a base material for an antireflection film.

(F-2. Antireflection film)
In another embodiment, the optical film of the present invention is an antireflection film. The antireflection film is a laminate having a low refractive index layer formed by applying the low refractive index coating composition on at least one side of a substrate, followed by drying and curing. The low refractive index layer may be formed directly on the substrate, or may be formed via another layer. The other layer may be a single layer or two or more layers. Specific examples of the other layer include a layer having a refractive index different from that of the low refractive index layer. In the antireflection film of the present invention, the refractive index of the other layers is often larger than the refractive index of the low refractive index layer. By providing such a layer, reflection can be reduced in a wider wavelength range. Furthermore, the low refractive index layer can be preferably formed as the outermost layer of the antireflection film. Therefore, specific examples of the preferred laminated structure of the antireflection film include base material / low refractive index layer, base material / high refractive index layer / low refractive index layer, base material / medium refractive index layer / high refractive index layer / low. Examples include a refractive index layer. In the present specification, the high refractive index layer means a layer having a higher refractive index than the low refractive index layer, and the middle refractive index layer is higher than the low refractive index layer and has a high refractive index layer. Refers to a layer having a lower refractive index. The thickness of the medium refractive index layer or the high refractive index layer is preferably 0.05 to 0.20 μm. The refractive index of the middle refractive index layer or the high refractive index layer is preferably 1.45 to 2.00. More specifically, the refractive index of the middle refractive index layer is preferably 1.45 to 1.80, and the refractive index of the high refractive index layer is preferably 1.60 to 2.00. In one embodiment, the medium refractive index layer or the high refractive index layer may be formed from a composition comprising polyfunctional (meth) acrylate and high refractive index fine particles. Typical examples of the high refractive index fine particles include metal oxide fine particles. Specific examples include zinc oxide, titanium oxide, zirconium oxide, aluminum oxide, tin oxide, tin-doped indium oxide, indium-doped zinc oxide, indium oxide, and antimony oxide. By adjusting the content of the fine particles, the refractive index of the medium refractive index layer or the high refractive index layer can be controlled. By imparting conductivity to the fine particles, the medium refractive index layer or the high refractive index layer can also function as an antistatic layer. In another embodiment, the medium refractive index layer or the high refractive index layer has a high refractive index such as titanium oxide or zirconium oxide formed by a vapor deposition method such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). It can be set as the vapor deposition film of an inorganic oxide.

  The antireflection film of the present invention may have still another layer having any appropriate function depending on the purpose. The further other layer is provided at any appropriate position of the laminate according to the purpose. Specific examples of the other layers include a hard coat layer, an antiglare layer, an antistatic layer, and an antifouling layer. The hard coat layer is preferably formed using a coating agent containing polyfunctional (meth) acrylate. The antiglare layer is preferably formed using a coating agent containing particles and polyfunctional (meth) acrylate. Various inorganic particles, organic particles, and organic / inorganic composite particles can be used as the particles. Further, the hard coat layer and the antiglare layer described above can be used as the hard coat layer and the antiglare layer.

The antistatic layer prevents the generation of static electricity, thereby preventing dust and dirt from adhering to the antireflection film, and / or external electrostatic interference when the antireflection film is incorporated in an image display device. To prevent. As the performance of the antistatic layer, the surface resistance after formation of the antireflection film is preferably 10 ¹² Ω / □ or less. Even if the surface resistance is 10 ¹² Ω / □ or more, the adhesion of dust and dust can be improved to some extent as compared with the case where no antistatic layer is provided.

  The antistatic layer is generally formed from an antistatic resin composition containing a film forming component (typically a resin component) and an antistatic agent. Any appropriate resin capable of forming a film may be employed as the resin component. Specific examples of the antistatic agent include a cationic antistatic agent having a cationic group such as a quaternary ammonium salt, a pyridinium salt, and first to third amino groups; a sulfonate group, a sulfate ester base, and a phosphate ester base. Anionic antistatic agents having an anionic group such as phosphonic acid group; amphoteric antistatic agents such as amino acid type and aminosulfate ester type; nonionic antistatic agents such as amino alcohol type, glycerin type and polyethylene glycol type; Surfactant-type antistatic agents such as organometallic compounds (for example, tin or titanium alkoxides) or metal chelate compounds (for example, acetylacetonate salts of organometallic compounds); and high molecular weights of the above antistatic agents Examples thereof include molecular type antistatic agents. Also, polymerizable antistatic agents such as tertiary amino groups, quaternary ammonium groups or monomers or oligomers having a metal chelate moiety and a polymerizable functional group, and organometallic compounds such as coupling agents having a polymerizable functional group Agents can also be used. Further, metal oxide fine particles such as zinc oxide, titanium oxide, tin oxide, tin-doped indium oxide, antimony-doped tin oxide, indium-doped zinc oxide, indium oxide, and antimony oxide can be used. By containing the antistatic agent in the coating composition, the hard coat layer and the antiglare layer can also serve as the antistatic layer.

  The antireflection film of the present invention is preferably as the total light transmittance is higher and / or the haze is lower. Therefore, it is desirable that each layer constituting the antireflection film (laminate) is as excellent as possible in transparency.

(F-3. Polarizing plate)
In yet another embodiment, the optical film of the present invention is a polarizing plate. The polarizing plate has a polarizer and the antireflection film provided on at least one of the polarizers. The antireflection film also serves as a protective film for the polarizing plate. As the polarizer, any appropriate polarizer can be used as long as it has a polarization function (a function of allowing only light having a polarization plane in a certain direction to pass). A typical example of the polarizer is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film is typically a stretched film of a polyvinyl alcohol film containing a dichroic substance (typically iodine or a dichroic dye). The polyvinyl alcohol polarizing film is formed by forming a polyvinyl alcohol aqueous solution and uniaxially stretching it while immersing it in, for example, an iodine solution, or uniaxially stretching after dyeing, and is preferably subjected to a durability treatment with a boron compound. Is used.

  The polarizing plate of the present invention can be produced by any appropriate method. For example, the antireflection film of the present invention may be treated with an alkali and bonded to both surfaces of the polyvinyl alcohol polarizing film using a completely saponified polyvinyl alcohol adhesive (water-soluble adhesive). The alkali treatment refers to a treatment in which the antireflection film is immersed in a high-temperature strong alkaline solution in order to improve the wettability of the adhesive and improve the adhesiveness. At this time, by providing a peelable protective film (for example, a polyester resin film such as polyethylene terephthalate) on the surface of the low refractive index layer of the antireflection film, it can be protected from erosion due to dirt or alkali.

(F-4. Optical filter for plasma display)
In yet another embodiment, the optical film of the present invention is an optical filter for a plasma display (PDP). The optical filter for PDP typically has a support and an antireflection film provided on the support. Specific examples of the support include glass. The antireflection film is preferably the antireflection film described above. By using the antireflection film of the present invention, an optical filter for PDP having excellent antireflection performance and excellent scratch resistance can be obtained. The low refractive index coating composition may be directly applied to a support to form a low refractive index layer.

  Preferably, the PDP optical filter further has a near-infrared absorbing film, an electromagnetic wave shielding film and / or a visible light absorbing film on the support. These films are typically provided between the support and the antireflection film. PDP has a problem that near infrared rays having a wavelength of 800 nm to 1000 nm are generated during plasma discharge, and this near infrared rays cause malfunction of a remote control for home appliances. By providing a near-infrared absorbing film, such a problem can be reduced or eliminated. The PDP performs plasma discharge in a gas mainly composed of a rare gas (particularly neon) sealed inside the panel, and R, G, B provided in the cells inside the panel by vacuum ultraviolet rays generated at that time. In this light emission process, electromagnetic waves unnecessary for the operation of the PDP are simultaneously emitted. By providing an electromagnetic wave shielding film, such a problem can be reduced or eliminated.

  The near infrared absorbing film is typically formed from a composition containing a near infrared absorbing dye and a binder. Specific examples of the near infrared absorbing dye include dyes such as cyanine, polymethine, squarylium, porphyrin, dithiol metal complex, phthalocyanine, and diimonium. Any appropriate resin can be adopted as the binder. A resin capable of forming a highly transparent film is preferred. Specific examples include polyolefin resins such as polyethylene; styrene resins; vinyl resins such as (meth) acrylic acid ester polymers; polyamide resins such as nylon; polyurethane resins; polyester resins; polycarbonate resins; Resin, polyvinyl acetal resin.

  As a specific example of the electromagnetic wave shielding film, a film obtained by patterning a metal mesh on a film by a technique such as etching or printing and smoothing with a resin; a metal vapor deposited on a fiber mesh in a resin An embedding film is mentioned.

  The optical filter for PDP of the present invention may further have a shock absorbing layer. Alternatively, the shock absorbing layer may be used instead of the support. It is preferable to use it instead of the support. The impact absorbing layer is used to protect the PDP from external impacts. Examples of the material constituting the shock absorbing layer include ethylene-vinyl acetate copolymer, acrylic resin, polyvinyl chloride, urethane resin, and silicon resin. Details of the material constituting the shock absorbing layer are described in, for example, Japanese Patent Application Laid-Open No. 2004-246365 or Japanese Patent Application Laid-Open No. 2004-264416.

  The optical filter for PDP of the present invention may have any appropriate configuration (laminated structure) depending on the purpose. Typical configurations include antireflection film / near infrared absorption film / support, antireflection film / near infrared absorption film / electromagnetic wave shielding film / support, antireflection film / electromagnetic wave shielding film / near infrared absorption film / support. Is mentioned.

  For example, an optical filter for PDP having the configuration of an antireflection film / near infrared absorption film / support can be produced by the following method: (i) Applying the above composition on the support side of the antireflection film and drying Forming a laminate of an antireflection film / near-infrared absorbing film and laminating the laminate on a support, or (ii) applying and drying the composition on the support and drying the support / near A method of forming a laminate of infrared absorbing films and laminating an antireflection film on the laminate. In the lamination, the films to be laminated may be bonded with an adhesive or an adhesive, or may be bonded by heating and melting each film. At the time of lamination, the surface of each film may be subjected to physical treatment (for example, corona treatment, plasma treatment), and an anchor coat layer (for example, highly polar polymer such as polyethyleneimine, oxazoline polymer, polyester, cellulose, etc.) It may be formed.

  The PDP optical filter of the present invention may be used by being placed on the front side of the PDP, or may be used by being bonded via an adhesive or a pressure-sensitive adhesive.

[G. (Image display device)
The image display device of the present invention includes at least one selected from the antireflection film, the polarizing plate, and the optical filter. In one embodiment, the image display device has the antireflection film on the outermost surface. According to such an embodiment, external light reflection can be satisfactorily reduced. In another embodiment, the image display device includes the antireflection film on one or more surfaces of a component that is provided therein and has an interface with air. According to such an embodiment, the reflected light inside the apparatus can be satisfactorily reduced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on mass. Moreover, the evaluation items in the examples are as follows.

(1) Pencil hardness A pencil scratch test was performed in accordance with JIS-K5400, and evaluation by scratches was performed.

(2) Steel Wool Resistance Using Suga Test Machine Co., Ltd., Gakushin Type Abrasion Resistance Tester, how to scratch # 0000 steel wool after reciprocating 10 or 20 times with a load of 200 g Visually evaluated.
A: There are no scratches.
B: 1 to 5 scratches.
C: 6-10 scratches.
D: 11-20 scratches.
E: There are 21 or more scratches.

(3) Haze It measured using the haze meter (Nippon Denshoku Co., Ltd. product, NDH2000) based on JIS-K7105.

(4) Total light transmittance Based on JIS-K7361, it measured using the haze meter (Nippon Denshoku Co., Ltd. product, NDH2000).

(5) Appearance The appearance of the coating film surface was visually observed to evaluate coating unevenness.
○: No coating unevenness is observed.
Δ: Uneven coating is observed.
X: Significant uneven coating is observed.

(6) Stability 30 ml of the coating composition was stored at 40 ° C. in the dark. Two weeks later, the presence or absence of aggregates was observed and evaluated.
○: Aggregates are not confirmed.
Δ: Some aggregates are confirmed.
X: The thing with which an aggregate is confirmed remarkably.

(7) Film thickness Measure the film reflectivity in the range of 400-800 nm using an interference film thickness measuring device (F20, manufactured by Filmetrics), quote the nk-Cauchy dispersion formula, The film thickness of the coating layer was obtained by calculating from the measured value of the reflectance spectrum by the non-linear least square method.

(8) Thiol content The content ratio (% by mass) of the polyfunctional thiol with respect to the total solid content of the organic-inorganic composite fine particles and the polyfunctional (meth) acrylate was defined as the thiol content.

[About abbreviations of polyfunctional thiols in the table]
Abbreviations of polyfunctional thiols in the table shown below are as follows.
PE1: “Karenz MT PE1” manufactured by Showa Denko KK (pentaerythritol tetrakis (3-mercaptobutyrate)
BD1: “Karenz MT BD1” (1,4-bis (3-mercaptobutyryloxy) butane) manufactured by Showa Denko KK
NR1: “Karenz MT NR1” (1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) − produced by Showa Denko KK Trion)

Reference Example 1 Synthesis of Fine Particle Dispersion (S-1) << Synthesis of Polymerizable Polysiloxane (M-1) >>
In a 300 ml four-necked flask equipped with a stirrer, a thermometer and a condenser tube, 144.5 g of tetramethoxysilane, 23.6 g of γ-methacryloxypropyltrimethoxysilane, 19.0 g of water, 30.0 g of methanol, Amberlyst 15 ( 5.0 g of a trade name, a cation exchange resin manufactured by Organo Corporation) was added, and the mixture was stirred at 65 ° C. for 2 hours to be reacted. After the reaction mixture was cooled to room temperature, a distillation column, a cooling tube connected to the distillation column and an outlet were provided instead of the cooling tube, and the temperature inside the flask was raised to about 80 ° C. over 2 hours under normal pressure. Was kept at the same temperature until no more spilled. Furthermore, the reaction was further proceeded by holding at a pressure of 2.67 × 10 kPa and a temperature of 90 ° C. until methanol did not flow out. After the reaction mixture was cooled again to room temperature, Amberlyst 15 was filtered off to obtain a polymerizable polysiloxane (M-1) having a number average molecular weight of 1,800.

<< Synthesis of silicon-containing polymer (P-1) >>
Into a 1 liter flask equipped with a stirrer, dripping port, thermometer, cooling pipe and nitrogen gas inlet port, 260 g of butyl acetate as an organic solvent was introduced, nitrogen gas was introduced, and the flask internal temperature was heated to 95 ° C. while stirring. did. Next, a solution prepared by mixing 12 g of polymerizable polysiloxane (M-1), 112 g of butyl acrylate, 187 g of 2-hydroxyethyl methacrylate and 2.5 g of 2,2′-azobis (2-methylbutyronitrile) was added through the dropping port 3 It was added dropwise over time. After the dropwise addition, stirring was continued for 1 hour at the same temperature. Then, 0.2 g of 2,2′-azobis (2-methylbutyronitrile) was added to the reaction mixture twice every 30 minutes, and the reaction mixture was further added for 2 hours. Copolymerization was conducted by heating to obtain a solution in which a silicon-containing polymer (P-1) having a number average molecular weight of 12,000 and a mass average molecular weight of 27,000 was dissolved in butyl acetate. The solid content of the obtained solution was 48.2%.

<< Synthesis of unsaturated group-containing silicon-containing polymer (P-2) >>
Into a 1 liter flask equipped with a stirrer, a dripping port, a thermometer, a cooling pipe and a nitrogen gas inlet, 400 g of silicon-containing polymer (P-1) is introduced, nitrogen gas is introduced, and the temperature inside the flask is increased to 70 with stirring. Heated to ° C. Next, 55 mg of dibutyltin laurate was added to the flask, and then a butyl acetate solution of 142 g of acryloxyethyl isocyanate (Karenz AOI, Showa Denko KK) was added dropwise over 1 hour with stirring. After completion of the dropwise addition, stirring was continued for 6 hours at the same temperature to advance the reaction. After the reaction, methanol was added to the system to adjust the solid content to 45% to obtain a solution in which the unsaturated group-containing silicon-containing polymer (P-2) was dissolved in butyl acetate.

<< Preparation of composite fine particle dispersion >>
200 g of butyl acetate and 50 g of methanol were charged into a 500 ml four-necked flask equipped with a stirrer, two dropping ports (dropping port a and dropping port b), and a thermometer, and the internal temperature was adjusted to 40 ° C. Next, while stirring the inside of the flask, 10 g of a butyl acetate solution of unsaturated group-containing silicon-containing polymer (P-2), 18 g of tetramethoxysilane and 5 g of butyl acetate (raw material liquid A) were added from the dropping port a to 25 A mixed liquid (raw material liquid B) of 5 g% ammonia water, 15 g methanol, and 10 g deionized water was dropped from the dropping port b over 2 hours. After dropping, a distillation column, a cooling tube connected to the distillation column and an outlet are provided instead of the cooling tube, and the temperature inside the flask is raised to 70 ° C. under a pressure of 40 kPa. The mixture was distilled off to 30% to obtain a dispersion (S-1) in which composite fine particles were dispersed in butyl acetate. The obtained composite fine particles had an average particle size of 22.1 nm and an inorganic core particle / organic polymer ratio of 61/39. Evaluation was performed by the following method.

<Measurement of the ratio of inorganic core particles to organic polymer>
Elemental analysis was performed on the composite fine particle dispersion (S-1) dried at 130 ° C. for 24 hours under a pressure of 1.33 × 10 kPa, and ash was determined as the content of inorganic core particles in the composite fine particles.
<Measurement of average particle size>
Using a solution obtained by diluting 1 g of the composite fine particle dispersion (S-1) with 99 g of n-butyl acetate, the particles were photographed with a transmission electron microscope, the diameters of 100 randomly selected particles were read, and the average Was determined as the average particle size.

Reference Example 2 Synthesis of Fine Particle Dispersion (S-2) Under a nitrogen stream, 28 parts of 3-acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to MEK-ST (Nissan Chemical Co., Ltd.). 400 parts of methyl ethyl ketone-dispersed colloidal silica, silica concentration 30%) and 8 parts of 0.002 N hydrochloric acid were added and stirred for 24 hours to obtain dispersion (S-2).

Reference Example 3 Synthesis of Fine Particle Dispersion (S-3) MEK-ST (manufactured by Nissan Chemical Co., Ltd., methyl ethyl ketone-dispersed colloidal silica, silica concentration 30%) was used as the fine particle dispersion (S-3).

[Example 1]
<< Preparation of coating composition >>
In a solution obtained by dissolving 7.5 g of dipentaerythritol hexaacrylate (DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.) in 30 g of methyl ethyl ketone (MEK), a photopolymerization initiator (Irgacure 907 (Irg907), manufactured by Ciba Specialty Chemicals) 0.5 g Solution in 19.3 g of methyl ethyl ketone, a solution in which 0.1 g of pentaerythritol tetrakis (3-mercaptobutyrate) (Karenz MT PE1, Showa Denko KK) is dissolved in 4.4 g of methyl ethyl ketone, a fine particle dispersion (S- 1) 50 g was mixed and diluted with 658 g of methyl ethyl ketone to prepare a coating composition (1) having a solid content of 3%. The results are shown in Table 1.

<< Evaluation of Coating Composition >>
A solution in which 7 g of dipentaerythritol hexaacrylate was dissolved in 14 g of methyl ethyl ketone and a solution in which 0.3 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) was dissolved in 3 g of methyl ethyl ketone were mixed to prepare a coating composition. . This coating composition was applied to a polyethylene terephthalate (PET) film (Cosmo Shine A4300, manufactured by Toyobo Co., Ltd .: thickness 188 μm) using a bar coater. The coating layer was dried at 100 ° C. for 15 minutes and then cured by irradiating with 250 mJ / cm ² of ultraviolet light with a high-pressure mercury lamp to form a hard coat layer. The coating composition (1) was applied to the hard coat layer side of the PET film / hard coat layer laminate using a bar coater. The coating layer was dried at 100 ° C. for 15 minutes and then cured by irradiating with 750 mJ / cm ² of ultraviolet light with a high-pressure mercury lamp to form a coating layer (1) having a film thickness of about 100 nm. The obtained coating layer (1) was evaluated for haze, total light transmittance, pencil hardness, steel wool resistance, storage stability, and appearance. The evaluation results are shown in Table 2.

[Examples 2 to 7]
Coating compositions (2) to (7) were prepared in the same manner as in Example 1 except that they were blended as shown in Table 1. Coating layers (2) to (7) were formed from the obtained coating compositions (2) to (7) in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 1]
A coating composition (C1) was prepared in the same manner as in Example 1 except that it was blended as shown in Table 1. A coating layer (C1) was formed from the obtained coating composition (C1) in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 8
In Example 2, the coating composition (2) was applied and dried, and then irradiated with ultraviolet rays of 750 mJ / cm ² with a high-pressure mercury lamp, except that nitrogen gas was introduced and the oxygen concentration was adjusted to 1%. In the same manner as in Example 2, a coating layer (8) was formed. The coating layer (8) was evaluated in the same manner as in Example 2. The results are shown in Table 3 together with the results of Example 2.

Example 9
In Example 2, after the coating composition (2) was applied and dried, nitrogen gas was introduced and the oxygen concentration was adjusted to 0.1% when 750 mJ / cm ² ultraviolet rays were irradiated with a high-pressure mercury lamp. The coating layer (9) was formed in the same manner as in Example 2 except for the above. The coating layer (9) was evaluated in the same manner as in Example 2. The results are shown in Table 3.

Example 10
In Example 2, after the coating composition (2) was applied and dried, nitrogen gas was introduced to adjust the oxygen concentration to 0.01% when 750 mJ / cm ² of ultraviolet light was irradiated with a high-pressure mercury lamp. The coating layer (10) was formed in the same manner as in Example 2 except for the above. The coating layer (10) was evaluated in the same manner as in Example 2. The results are shown in Table 3.

[Examples 11 to 13]
Coating compositions (11) to (13) were prepared in the same manner as in Example 2 except that they were blended as shown in Table 4. Coating layers (11) to (13) were formed from the obtained coating compositions (11) to (13) in the same manner as in Example 2, and evaluated in the same manner as in Example 2. The results are shown in Table 5 together with Example 2.

Example 14
A coating composition (14) was prepared in the same manner as in Example 1 except for blending as shown in Table 6. A coating layer (14) was formed from the obtained coating composition (14) in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 7.

[Comparative Examples 2 to 4]
Coating compositions (C2) to (C4) were prepared in the same manner as in Example 1 except that they were blended as shown in Table 6. Coating layers (C2) to (C4) were formed from the obtained coating compositions (C2) to (C4) in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 7.

Example 15
<< Preparation of coating composition >>
In a solution obtained by dissolving 7.5 g of dipentaerythritol hexaacrylate (DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.) in 30 g of methyl ethyl ketone (MEK), a photopolymerization initiator (Irgacure 907 (Irg907), manufactured by Ciba Specialty Chemicals) 0.5 g In 19.3 g of methyl ethyl ketone, a solution of 0.6 g of pentaerythritol tetrakis (3-mercaptobutyrate) (Karenz MT PE1, Showa Denko KK) in 21.9 g of methyl ethyl ketone, a fine particle dispersion (S- 1) 50 g was mixed and diluted with 106 g of methyl ethyl ketone to prepare a coating composition (15) having a solid content of 10%. The results are shown in Table 8.

<< Evaluation of Coating Composition >>
The coating composition (15) was applied to a polyethylene terephthalate (PET) film (Cosmo Shine A4300, manufactured by Toyobo Co., Ltd .: thickness 188 μm) using a bar coater. The coating layer was dried at 100 ° C. for 15 minutes and then cured by irradiating with 250 mJ / cm ² ultraviolet rays with a high-pressure mercury lamp to form a coating layer (15) having a thickness of about 3 μm. The coating layer (15) obtained was evaluated for haze, total light transmittance, pencil hardness, steel wool resistance, and appearance. Table 9 shows the evaluation results.

[Comparative Example 5]
A coating composition (C5) was prepared in the same manner as in Example 15 except for blending as shown in Table 8. A coating layer (C5) was formed from the obtained coating composition (C5) in the same manner as in Example 15 and evaluated in the same manner as in Example 15. The results are shown in Table 9.

[Evaluation]
From Table 1 and Table 2, it can be seen that when the polyfunctional thiol is not used (Comparative Example 1), the effect of the present invention is not sufficiently exhibited, and in particular, the scratch resistance is inferior. Moreover, when the amount of thiols of the polyfunctional thiol increases (Examples 4 and 7), the storage stability tends to decrease.
From Table 3, it can be seen that a thin film coating layer having practical hardness and scratch resistance can be obtained without using an inert gas atmosphere by using the coating composition of the present invention (Example 8). -10).
When Table 4 and Table 5 are seen, when the ratio of the inorganic content in solid content in the coating composition of this invention increases, there exists a tendency for the abrasion resistance of a coating layer to fall, In solid content in the coating composition of this invention. It turns out that there is a tendency for the hardness of a coating layer to fall, when the ratio of the inorganic content of becomes small (Example 2, Examples 11-13).
Tables 6 and 7 show that the effect of the present invention can be sufficiently exhibited even when organic-inorganic composite fine particles in which the organic substance bonded to at least a part of the core particle surface is not an organic polymer are used (Example 14). ). Moreover, it turns out that the effect of this invention cannot fully be expressed when a mere inorganic particle is used (comparative example 2).
From Table 8 and Table 9, it can be seen that the effect of the present invention can be sufficiently exhibited not only in the case of a thin coating but also in the case of a relatively thick coating (about 3 μm) (Example 15).

  The composite fine particles and coating composition of the present invention are a transfer foil film, a plastic optical component, a touch panel, a film type liquid crystal element, a hard coating agent such as a plastic molding, a low refractive index coating agent for an antireflection film, and a coating for a light diffusion film. It can be suitably used as an agent.

Claims (15)

(A) Organic-inorganic composite fine particles;
(B) polyfunctional (meth) acrylate;
(C) a polymerization initiator;
(D) a polyfunctional thiol;
A coating composition comprising:   The coating composition according to claim 1, wherein the polyfunctional thiol is 0.1 to 15% by mass with respect to the total of the organic-inorganic composite fine particles and the polyfunctional (meth) acrylate in a solid content ratio.   The coating composition according to claim 1, wherein the organic-inorganic composite fine particles include core particles composed of inorganic core particles or an organic-inorganic composite, and an organic substance bonded to at least a part of the surface of the core particles.   The coating composition according to claim 3, wherein the organic-inorganic composite fine particles have a polymerizable functional group.   The coating composition according to claim 4, wherein the polymerizable functional group is an ethylenically unsaturated group.   The coating composition according to any one of claims 3 to 5, wherein the organic substance bonded to at least a part of the surface of the core particle is an organic polymer.   The coating composition according to claim 6, wherein the organic polymer is an acrylic polymer.   The coating composition according to claim 6 or 7, wherein the organic polymer has a polymerizable functional group in a side chain thereof.   The coating composition according to claim 8, wherein the polymerizable functional group is bonded to the main chain of the organic polymer via a urethane bond.   An optical film comprising a coating layer of the coating composition according to claim 1.   The coating composition according to any one of claims 6 to 9, wherein the organic polymer has a portion containing a fluorine atom.   An antireflection film comprising a coating layer of the low refractive index coating composition according to claim 11.   A polarizing plate comprising a polarizer and the antireflection film according to claim 12.   An optical filter for a plasma display, comprising a support and the antireflection film according to claim 12.   An image display device comprising at least one selected from the antireflection film according to claim 12, the polarizing plate according to claim 13, and the optical filter according to claim 14.