JP2006016480A - Curable composition and transparent substrate having cured coated film of the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable composition capable of forming a coating film excellent in hardness and close adhesion and capable of constituting a stable coating hardly forming precipitation, and also a transparent substrate having the cured coated film excellent in hardness and close adhesion by using the same on its surface. <P>SOLUTION: This curable composition is constituted by a cationic polymerizable compound with porous silica fine particles of which surfaces are modified with an organic group. The coated film obtained by curing the curable composition is formed on the surface of the transparent substrate. As the cationic polymerizable compound, a compound having at least 2 oxetane rings in its molecule, a compound having silyl group in its molecule or its hydrolytic condensate is used preferably. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a curable composition suitable as a material for an antireflection film. Moreover, this invention relates to the transparent base material which has the cured film of this curable composition, especially an antireflection film on the surface.

Conventionally, as one method for imparting antireflection performance to a transparent substrate such as glass or resin, it is known to form a film containing porous silica fine particles on the surface thereof. For example, in JP-A-7-48527 (Patent Document 1) and JP-A-7-133105 (Patent Document 2), the coating film is formed using a curable composition containing porous silica fine particles and a binder component. It is disclosed to form. JP-A-2003-145682 (Patent Document 3) and JP-A-2003-147268 (Patent Document 4) disclose the use of a cationically polymerizable compound as a binder component in the curable composition. Yes.
JP 7-48527 A JP 7-133105 A JP 2003-145682 A JP 2003-147268 A

  However, the conventional curable composition may not always have sufficient hardness and adhesion to the substrate. Further, when configured as a paint, precipitation of porous silica fine particles is likely to occur and it may be difficult to apply to a substrate. SUMMARY OF THE INVENTION An object of the present invention is to provide a curable composition that can form a coating having excellent hardness and adhesion, and can constitute a stable paint that does not easily precipitate. Another object of the present invention is to provide a transparent substrate having on its surface a cured film having excellent hardness and adhesion, using the curable composition thus obtained.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by constituting a curable composition from a cationically polymerizable compound and porous silica fine particles surface-modified with an organic group. It came to complete. That is, the present invention provides a curable composition containing a cationically polymerizable compound and porous silica fine particles whose surface is modified with an organic group. Moreover, this invention provides the base material with a film by which the film formed by hardening | curing this curable composition is formed on the surface of a transparent base material.

  The curable composition of this invention is excellent in the hardness and adhesiveness of the film formed, and can comprise the stable coating material with which precipitation is hard to produce. And the transparent base material which has the film which is excellent in hardness and adhesiveness on the surface can be obtained by using this curable composition.

  The cationically polymerizable compound that is one of the essential components of the curable composition of the present invention is a compound that is cured by cationic polymerization, and has at least one cationically polymerizable functional group in the molecule. Examples of the cationic polymerizable functional group include a vinyl ether group, an epoxy group, an oxetane ring, an aziridine ring, a lactone ring, and an oxazoline ring. A cationically polymerizable compound may be used individually by 1 type, and may be used as a 2 or more types of mixture.

  Of these, oxetane compounds are preferably used because of their high curing speed. An epoxy compound is also preferably used, and it is effective to use an oxetane compound and an epoxy compound in combination. In this case, the epoxy compound is usually used in an amount of 30 parts by weight or less, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the oxetane compound.

  The oxetane compound is a compound having at least one oxetane ring in the molecule, and preferable examples thereof include those represented by the following formulas (I) to (III).

In the formula, R ¹ represents a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, an allyl group, an aryl group or a furyl group, m represents an integer of 1 to 4, Z represents an oxygen atom or a sulfur atom, R ² represents a monovalent to tetravalent organic group depending on the value of m, n represents an integer of 1 to 5, p represents an integer of 0 to 2, and R ³ represents hydrogen or an inert monovalent group. Represents an organic group, and R ⁴ represents a hydrolyzable functional group. When R ¹ , Z, R ³ or R ⁴ appears multiple times in one molecule, they may be the same or different.

In the formulas (I) to (III), when R ¹ is an alkyl group, the carbon number thereof can be about 1 to 6, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, and the like. Can be mentioned. The fluoroalkyl group can also have about 1 to 6 carbon atoms. Furthermore, the aryl group is typically a phenyl group or a naphthyl group, and these may be substituted with other groups.

The organic group represented by R ² in the formula (I) is not particularly limited. For example, when m is 1, an alkyl group, a phenyl group, a naphthyl group, etc., and when m is 2, the number of carbon atoms is 1. -12 linear or branched alkylene groups, linear or branched poly (alkyleneoxy) groups, phenylene groups, biphenyl groups, naphthylene groups, etc., when m is 3 or 4, Valent functional groups.

The inactive monovalent organic group represented by R ³ in the formula (III) typically includes an alkyl group having 1 to 4 carbon atoms, and a hydrolyzable function represented by R ^4. Examples of the group include an alkoxy group having 1 to 5 carbon atoms such as a methoxy group and an ethoxy group, and a halogen atom such as a chlorine atom and a bromine atom.

  The epoxy compound is a compound having at least one epoxy group in the molecule. For example, phenyl glycidyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, vinylcyclohexene dioxide, 1,2,8,9-di- Examples thereof include epoxy limonene, 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexyl) adipate and the like.

  As the cationic polymerizable compound, a polyfunctional cationic polymerizable compound having at least two cationic polymerizable functional groups in the molecule is preferably used, and among them, a polyfunctional oxetane compound having at least two oxetane rings in the molecule is preferably used. Preferably used. Moreover, as a cationically polymerizable compound, the compound which has a silyl group in a molecule | numerator, and its hydrolysis condensate are used preferably, Especially, the oxetane compound which has a silyl group in a molecule | numerator, and its hydrolysis condensate are used preferably. In particular, a silsesquioxane compound having a plurality of oxetane rings in the molecule (network-like polysiloxane compound) obtained by hydrolytic condensation of the oxetane compound represented by the formula (III) in the presence of an alkali and water. Is suitable as a material used in the present invention because it gives a hard coating.

  The porous silica fine particles, which are another essential component of the curable composition of the present invention, are porous fine particles made of silica, and the surface thereof is modified with an organic group. The surface-modified porous silica fine particles are prepared by treating the porous silica fine particles with a compound having an organic group and capable of reacting with a hydroxyl group on the surface of the porous silica fine particles to form a chemical bond. be able to.

  The porous silica fine particles used as a raw material are not particularly limited, but those having a refractive index of about 1.2 to 1.4 and an average particle size in the range of 5 nm to 10 μm are preferably used. In the case of forming, those having an average particle diameter in the range of 5 nm to 100 nm are more preferable. The porous silica fine particles are obtained by hydrolyzing alkoxysilane in the presence of an alkali, as shown in Patent Document 1, for example, and are highly entangled and branched to form a polymer. Alternatively, as shown in Patent Document 2, the surface of the porous silica fine particles may have a double structure in which the surface is covered with a coating such as silica that is not porous. In particular, the porous silica fine particles coated on the surface are preferably used because the pore inlets of the particles are blocked and the porosity inside the particles is maintained.

  Examples of the compound for modifying the surface of the porous silica fine particle with an organic group include a hydrolyzable organosilicon compound represented by the following formula (IV).

(R ⁵ ) _q Si (H) _r (R ⁶ ) _4-qr (IV)

In the formula, R ⁵ represents an organic group, R ⁶ represents a hydrolyzable functional group, q represents an integer of 1 to 3, r represents an integer of 0 to 2, and q + r exceeds 3. Absent. When R ⁵ or R ⁶ appears multiple times in one molecule, they may be the same or different.

Examples of the organic group represented by R ⁵ include alkyl groups, alkenyl groups such as allyl groups and vinyl groups, and aryl groups such as phenyl groups. Moreover, the substituted alkyl group by which these groups were substituted by various functional groups, a substituted alkenyl group, a substituted aryl group, etc. can also be mentioned. In particular, when the organic group represented by R ⁵ appears multiple times in one molecule (when q is 1 or 2), at least one of them is an acryloyloxy group, a methacryloyloxy group, an epoxy ring or an oxetane ring. It is preferable that it contains.

Examples of the hydrolyzable functional group represented by R ⁶ include an alkoxy group having 1 to 5 carbon atoms such as a methoxy group and an ethoxy group, an acyloxy group such as an acetoxy group and a propionyloxy group, a chlorine atom, Examples thereof include a halogen atom such as a bromine atom and a substituted silylamino group such as a trimethylsilylamino group. Well-known hydrolyzable organosilicon compounds are roughly classified into alkoxysilane compounds, halogenated silane compounds, acyloxysilane compounds, and silazane compounds.

  Specific hydrolyzable silicon compounds include, for example, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, and trifluoropropyl. Trimethoxysilane, heptadecatrifluorodecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-ethyl 3-[{3- (triethoxysilyl) propoxy} methyl ] Oxetane, 3-methacryloyloxy propyl trimethoxy silane, 3-methacryloyloxypropyl methyl dimethoxysilane, 3-methacryloyloxypropyl triethoxysilane, 3-acrylic such acryloyloxy propyl trimethoxy silane. These may be used alone or in combination of two or more.

  Further, the hydrolyzable silicon compound may be a monomer as shown here, an oligomer of about a dimer to a 10-mer or a polymer such as a polymer having a degree of polymerization exceeding 10. Also good. Further, it may be a hydrolysis product obtained by hydrolyzing the organosilicon compound as described above. The hydrolysis product can be produced by adding an acid such as hydrochloric acid, phosphoric acid or acetic acid or a base such as sodium hydroxide or sodium acetate to the organosilicon compound.

  The surface modification of the porous silica fine particles with the hydrolyzable organosilicon compound can be carried out, for example, by mixing the two and adding an acid such as hydrochloric acid as necessary, followed by heat treatment. The amount of the hydrolyzable organosilicon compound used is usually about 1 to 50 parts by weight, preferably about 3 to 30 parts by weight with respect to 100 parts by weight of the porous silica fine particles. When the amount of the hydrolyzable organosilicon compound used is too small, the surface of the porous silica fine particles is not sufficiently modified, and when the curable composition is used as a paint, precipitation is likely to occur and stability may be low. . Also, if the amount of the hydrolyzable organosilicon compound used is too large, hydrolysis of the compound alone is likely to occur, and the smoothness and strength of the resulting film may not be sufficient due to the influence of the single hydrolyzate. is there.

  As a hydrolyzable organosilicon compound, the surface contains an acryloyloxy group, a methacryloyloxy group, an epoxy ring or an oxetane ring by using an organic group containing an acryloyloxy group, a methacryloyloxy group, an epoxy ring or an oxetane ring. Porous silica fine particles modified with an organic group can be obtained. Such porous silica fine particles are more preferably used because they have a high affinity with the cationic polymerizable compound and can form a bond.

  The amount ratio between the cationically polymerizable compound and the porous silica fine particles whose surface is modified with an organic group is appropriately adjusted. Usually, the former is used in the range of 10 to 90% by weight and the latter in the range of 10 to 90% by weight. . In the case of forming an antireflection film as a cured coating, the amount ratio of the two is adjusted so that the refractive index of the coating is preferably 1.20 to 1.45, more preferably 1.25 to 1.41. Is good. If the amount of porous silica fine particles whose surface is modified with an organic group is too small, the refractive index will not be small, and it will be difficult to obtain an effect as an antireflection film. If the amount is too large, the strength of the coating will be low. May decrease.

  The curable composition of the present invention may contain additives such as a stabilizer, an antioxidant, and a colorant as necessary. In particular, silicone oil is preferably used as an additive for improving the coatability and the slipperiness of the surface of the cured film to obtain a hard film having higher scratch resistance.

  Examples of the silicone oil include dimethyl silicone oil, phenylmethyl silicone oil, alkyl / aralkyl modified silicone oil, fluorosilicone oil, polyether modified silicone oil, fatty acid ester modified silicone oil, methyl hydrogen silicone oil, silanol group-containing silicone oil, Alkoxy group-containing silicone oil, phenol group-containing silicone oil, methacryl-modified silicone oil, amino-modified silicone oil, carboxylic acid-modified silicone oil, carbinol-modified silicone oil, epoxy-modified silicone oil, mercapto-modified silicone oil, fluorine-modified silicone oil, poly Examples include ether-modified silicone oil. These silicone oils may be used alone or in combination of two or more.

  The addition amount of the silicone oil is appropriately adjusted, but is usually 0.01 to 50 parts by weight with respect to 100 parts by weight of the total amount of the cationic polymerizable compound and the porous silica fine particles whose surface is modified with an organic group. is there. If the amount of silicone oil added is too large, the strength of the coating may be reduced.

  As the polymerization initiator for curing the curable composition of the present invention, an initiator that generates cations by irradiation with ultraviolet rays is preferably used. As such an initiator, for example, an onium salt such as a diazonium salt, a sulfonium salt, or an iodonium salt represented by the following formulas is preferably used.

ArN ₂ ⁺ Z ⁻ ,
^{_{(R) 3 S + Z -}} ,
(R) ₂ I ⁺ Z ^-

In the formula, Ar represents an aryl group, R represents an aryl group or an alkyl group having 1 to 20 carbon atoms, and when R appears multiple times in one molecule, they may be the same or different, and Z ⁻ is Represents a non-basic and non-nucleophilic anion.

In the above formulas, the aryl group represented by Ar or R is typically phenyl or naphthyl, and these may be substituted with an appropriate group. Specific examples of the anion represented by Z ⁻ include tetrafluoroborate ion (BF ₄ ⁻ ), tetrakis (pentafluorophenyl) borate ion (B (C ₆ F ₅ ) ₄ ⁻ ), and hexafluorophosphate ion. (PF ₆ ⁻ ), hexafluoroarsenate ion (AsF ₆ ⁻ ), hexafluoroantimonate ion (SbF ₆ ⁻ ), hexachloroantimonate ion (SbCl ₆ ⁻ ), hydrogen sulfate ion (HSO ₄ ⁻ ), perchloric acid And ions (ClO ₄ ⁻ ).

  Since many of these various initiators are commercially available, such commercial products can be used. Examples of commercially available initiators include “Syracure UVI-6990” sold by Dow Chemical Japan Co., Ltd., “Adekaoptomer SP-150” and “Adekaoptomer SP-150” sold by Asahi Denka Kogyo Co., Ltd., respectively. Adekaoptomer SP-170 ”,“ RHODORSIL PHOTOINITIATOR 2074 ”sold by Rhodia Japan Co., Ltd.

  The initiator is usually added at a ratio of about 0.1 to 30 parts by weight, preferably about 0.5 to 20 parts by weight with respect to 100 parts by weight of the cationic polymerizable compound. If the amount of the initiator is too small, the ultraviolet polymerizable property of the cationic polymerizable compound is not sufficiently exhibited, and even if the amount is too large, the effect of increasing the amount is not recognized, which is economically disadvantageous. This is not preferable because there is a possibility of deteriorating the optical characteristics.

  As described above, the curable composition of the present invention containing a cationically polymerizable compound, porous silica fine particles whose surface is modified with an organic group, and other components as necessary, has a hardness, It can be suitably used as a material for forming a cured film excellent in adhesion, particularly an antireflection film.

  Examples of the transparent substrate include a resin substrate such as polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, methyl methacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin, triacetyl cellulose resin, and inorganic glass. An inorganic base material such as In particular, methyl methacrylate-styrene copolymer resin is small in expansion and contraction due to moisture absorption, and is suitable as a base material for an antireflection plate.

  The shape of the transparent substrate is not particularly limited, but a sheet or film is typical. The substrate surface may be a flat surface, may be a curved surface such as a convex lens or a concave lens, or may be provided with fine irregularities. When the transparent substrate is a resin substrate, a film such as a scratch-resistant layer (so-called hard coat layer) may be formed in advance on the surface.

  The coating is preferably formed by applying and curing the curable composition of the present invention on the surface of the transparent substrate. For this purpose, it is necessary to form the composition as a paint. This paint is preferably prepared by dissolving or dispersing a cationically polymerizable compound, porous silica fine particles whose surface is modified with an organic group, and, if necessary, other components in a solvent. Since the surface of the porous silica fine particle is modified with an organic group, the coating composition of the curable composition of the present invention is less likely to precipitate and has excellent stability during storage and application.

  The solvent is used to adjust the concentration and viscosity of the paint, the film thickness after curing, and the like. The solvent to be used may be appropriately selected. For example, alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, isobutanol, and t-butanol, 2-ethoxyethanol, 2-butoxyethanol , Alkoxy alcohols such as 3-methoxypropanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ketols such as diacetone alcohol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, Examples thereof include aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate. The amount of the solvent used is appropriately selected according to the material of the substrate, the shape, the coating method, the film thickness of the target film, etc., but is usually a porous polymer whose surface is modified with an organic group. Is about 20 to 10000 parts by weight per 100 parts by weight of the total amount of the fine silica particles.

  By applying such paint to the surface of the substrate, a coating film composed of a cationic polymerizable compound and porous silica fine particles whose surface is modified with an organic group is formed. In order to apply the paint to the surface of the substrate, for example, a micro gravure coating method, a roll coating method, a dipping coating method, a flow coating method, a spin coating method, a die coating method, a cast transfer method, a spray coating method, etc. are used. That's fine.

Next, ultraviolet rays are irradiated to cure the coating film. Although the ultraviolet irradiation time is not particularly limited, it is usually in the range of about 0.1 to 60 seconds. Ultraviolet rays can usually be irradiated in an atmosphere of about 10 to 40 ° C. Moreover, the irradiation energy of the ultraviolet-rays to irradiate is about 50-3000mJ / cm < ² > normally. When the irradiation amount of ultraviolet rays is too small, the curing becomes insufficient and the strength of the film is lowered. On the other hand, if the amount of irradiation with ultraviolet rays is too large, the coating film and the base material are deteriorated, and there is a possibility that optical characteristics and mechanical properties are lowered, which is not preferable.

  When the coating material contains a solvent, the ultraviolet ray may be irradiated while the coating film contains the solvent, or may be irradiated after the solvent is volatilized. When the solvent is volatilized, it may be left at room temperature or may be dried by heating at about 30 to 100 ° C. The drying time is appropriately selected according to the material, shape, coating method, target film thickness, and the like of the substrate. After the cured film is formed by irradiation with ultraviolet rays, heat treatment may be further performed to make the cured film stronger. The heating temperature and time are appropriately selected, but are usually about 50 to 120 ° C. and about 30 minutes to 24 hours.

  The formed cured film has a film thickness of usually 0.01 to 20 μm, more preferably 0.01 to 10 μm. If the film thickness is too small, it will be difficult to show the properties as a cured film. If it is too large, the adhesion may be lowered or defects such as cracks may occur, which is not preferable. In particular, when a film is formed as an antireflection film, the film thickness is preferably in the range of 0.01 to 1 μm. If the film thickness is too small or too large, the function as an antireflection film is likely to deteriorate.

  The transparent substrate having a cured film thus obtained can be used for various applications, and is particularly suitably used as a front plate of a display such as a projection television.

  Examples of the present invention will be described below, but the present invention is not limited thereto. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

Reference Example 1 (Preparation of porous silica fine particles whose surface is modified with an organic group containing a methacryloyloxy group)
A liquid mixture of 100 g of silica sol having an average particle diameter of 5 nm and a SiO2 concentration of 20% and 1900 g of pure water was heated to 80 ° C. The pH of this mixed solution was 10.5, and 9000 g of a 1.17% sodium silicate aqueous solution as SiO2 and 9000 g of a 0.83% sodium aluminate aqueous solution as Al2O3 were simultaneously added to this mixed solution. Meanwhile, the temperature of the reaction solution was kept at 80 ° C. The pH of the reaction solution rose to 12.5 immediately after the addition, and hardly changed thereafter. After completion of the addition, the reaction solution was cooled to room temperature and washed with an ultrafiltration membrane to prepare a SiO 2 .Al 2 O 3 core particle dispersion with a solid content concentration of 20%.

  1700 g of pure water was added to 500 g of this core particle dispersion and heated to 98 ° C., and while maintaining this temperature, the sodium silicate aqueous solution was dealkalized with a cation exchange resin and had a SiO 2 concentration of 3.5%. Addition of 3000 g of silicic acid solution to form a first silica coating layer on the surface of the core particles, followed by washing with an ultrafiltration membrane, dispersion of the core particles formed with the first silica coating layer having a solid content concentration of 13% A liquid was prepared.

  1500 g of pure water was added to 500 g of the dispersion of core particles on which the first silica coating layer had been formed, and concentrated hydrochloric acid (concentration 35.5%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, the aluminum salt dissolved in the ultrafiltration membrane was separated, and the solvent was replaced with ethanol using the ultrafiltration membrane, so that the solid content concentration was 20%. A dispersion of porous silica fine particles on which the first silica coating layer was formed was prepared. The thickness of the first silica coating layer of the porous silica fine particles was 2 nm, the average particle size was 30 nm, the Al / Si molar ratio was 0.0021, and the refractive index was 1.31. Here, the average particle diameter was measured by a dynamic light scattering method, and the refractive index was measured by the following method.

[Measurement method of refractive index of fine particles]
(1) Take a dispersion of fine particles in an evaporator and evaporate the dispersion medium.
(2) This is dried at 120 ° C. to obtain a powder.
(3) Two or three drops of standard refractive liquid (Series A, AA manufactured by CARGILL) with a known refractive index are dropped on a glass plate, and the powder is mixed therewith.
(4) The above operation (3) is performed with various standard refractive liquids, and the refractive index of the standard refractive liquid when the mixed liquid becomes transparent is the refractive index of the fine particles.

  Next, methanol was added to the dispersion of the porous silica fine particles formed with the first silica coating layer obtained above to dilute to a solid content concentration of 10%, and 3-methacryloyloxypropyltrimethoxy was added to 205 g of this dispersion. 1.25 g of silane was mixed and stirred at 60 ° C. for 3 hours. Thereafter, the solvent was replaced with isopropyl alcohol using an ultrafiltration membrane and concentrated to prepare a dispersion of porous silica fine particles having a solid content concentration of 20% and modified with an organic group containing a methacryloyloxy group. . This dispersion was used in Example 1.

Reference Example 2 (Preparation of porous silica fine particles whose surface is modified with an organic group containing an oxetane ring)
In the same manner as in Reference Example 1, a dispersion of core particles on which a first silica coating layer having a solid concentration of 13% was formed was prepared, 1125 g of pure water was added to 500 g of this dispersion, and concentrated hydrochloric acid (concentration 35. 5%) was added dropwise to adjust the pH to 1.0, and dealumination was performed. Subsequently, while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, the dissolved aluminum salt was separated using an ultrafiltration membrane to prepare a dispersion of porous silica particles on which the first silica coating layer was formed.

  A mixture of 1500 g of a dispersion of porous silica particles on which the first silica coating layer is formed, 500 g of pure water, 1750 g of ethanol, and 626 g of 28% ammonia water is heated to 35 ° C., and then 104 g of ethyl silicate is added. Then, the surface of the first silica coating layer of the porous silica fine particles is formed with a second silica coating layer by hydrolysis polycondensate of ethyl silicate, then concentrated with an ultrafiltration membrane, and the solid content concentration is 20% by weight. A dispersion of porous silica fine particles on which the second silica coating layer was formed was prepared. The porous silica fine particles have a first silica coating layer thickness of 2 nm, a second silica coating layer thickness of 8 nm, an average particle size of 46 nm, an Al / Si molar ratio of 0.0019, and a refractive index of 1.31. Met.

  Next, methanol is added to the dispersion of the porous silica fine particles formed with the second silica coating layer obtained above to dilute to a solid content concentration of 10%, and 3-ethyl 3-[{ 3- (Triethoxysilyl) propoxy} methyl] oxetane (1.3 g) was mixed and stirred at 60 ° C. for 3 hours. Thereafter, the solvent was replaced with isopropyl alcohol using an ultrafiltration membrane and concentrated to prepare a dispersion of porous silica fine particles having a solid content concentration of 20% modified with an organic group containing an oxetane ring. This dispersion was used in Example 2.

Reference Example 3 (Preparation of porous silica fine particles whose surface is not modified with an organic group)
In the same manner as in Reference Example 1, a dispersion of core particles on which a first silica coating layer having a solid concentration of 13% was formed was prepared, 1125 g of pure water was added to 500 g of this dispersion, and concentrated hydrochloric acid (concentration 35. 5%) was added dropwise to adjust the pH to 1.0, and dealumination was performed. Next, while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, the aluminum salt dissolved in the ultrafiltration membrane is separated, and the solvent is replaced with isopropyl alcohol using the ultrafiltration membrane, so that the solid content concentration is 20%. A dispersion of porous silica fine particles on which the first silica coating layer was formed was prepared. The thickness of the first silica coating layer of the porous silica fine particles was 2 nm, the average particle size was 30 nm, the Al / Si molar ratio was 0.0021, and the refractive index was 1.31. This dispersion was used in Example 3.

Example 1
(A) Preparation of curable composition 275 parts of a dispersion of porous silica fine particles whose surface having a solid content of 20% obtained in Reference Example 1 was modified with an organic group containing a methacryloyloxy group, 3-ethyl- 3-[{3- (triethoxysilyl) propoxy} methyl] oxetane [hydrolysis condensate of the compound of formula (III) wherein R ¹ = ethyl, R ⁴ = ethoxy, n = 3, p = 0] 32 parts of oxetanylsilsesquioxane (obtained from Toagosei Co., Ltd.), 3,4-epoxycyclohexylmethyl 3 ', 4'-epoxycyclohexanecarboxylate ("CYRACURE UVR-6105" obtained from Dow Chemical Japan) 13 parts, p-cumyl-p-tolyliodonium tetrakis (pentafluorophenyl) borate ["RHODORSIL PHOTOINITI obtained from Rhodia Japan Ltd." ATOR 2074 "(polymerization initiator)], 5 parts epoxy-modified silicone oil [" X-22-163A "obtained from Shin-Etsu Chemical Co., Ltd.], 4170 parts isopropyl alcohol, and 2-butoxyethanol Was mixed to obtain a curable composition paint. The paint was stored in a cool and dark place for 1 month, but no change was observed in the paint, such as the formation of a precipitate.

(B) Preparation of base material with coating Methyl methacrylate-styrene copolymer resin plate [“Acryase MS” manufactured by Nippon Acryase Co., Ltd.] containing about 40% of styrene unit was added to the paint obtained in (a) above. It was immersed, dip coated at a pulling rate of 18 cm / min, dried at room temperature for 1 minute or more, and then dried at 60 ° C. for 10 minutes. After drying, ultraviolet rays were irradiated with an energy of about 500 mJ / cm ² with a high-pressure mercury lamp (“UVC-3533” manufactured by USHIO INC.) To obtain a coated substrate having antireflection performance. This coated substrate was evaluated by the following method, and the results are shown in Table 1.

[Reflectance]
The surface opposite to the measurement surface of the coated substrate is roughened with steel wool, black paint is applied and dried, and then the absolute specular reflection spectrum at an incident angle of 5 ° on the measurement surface is measured with an ultraviolet-visible spectrophotometer [ Measurement was performed using “UV-3100” manufactured by Shimadzu Corporation, and the minimum value of the reflectance and the wavelength indicating the reflectance were obtained, and the refractive index and the film thickness were calculated.

[Adhesion]
On the surface of the substrate with a coating, cut a 1 mm square 100 grid pattern cut so as to penetrate the cured coating with a cutter knife, and paste cellophane tape (made by Nichiban Co., Ltd., 24 mm width) on this, It peeled in the perpendicular direction and evaluated by the peeling number per 100 grids.

[Abrasion resistance]
Cover the tip of the eraser of an eraser wear tester (manufactured by Honko Seisakusho Co., Ltd.) with gauze, and reciprocate the surface of the coated substrate while applying a pressure of 49 N / cm ² , and scratches are confirmed on the surface. It was evaluated by the number of round trips. A total of 6 evaluations were performed, and the number of reciprocations in each evaluation was up to 1000, and the maximum and minimum values of the reciprocations were shown.

Example 2
Instead of the dispersion of porous silica fine particles whose surface having a solid content concentration of 20% obtained in Reference Example 1 was modified with an organic group containing a methacryloyloxy group, the solid content concentration of 20% obtained in Reference Example 2 was used. A curable composition paint was obtained in the same manner as in Example 1 (a) except that a dispersion of porous silica fine particles whose surface was modified with an organic group containing an oxetane ring was used. The paint was stored in a cool and dark place for 1 month, but no change was observed in the paint, such as the formation of a precipitate.

  Next, in place of the curable composition obtained in Example 1 (a), the same operation as in Example 1 (b) was performed except that the curable composition obtained above was used. A substrate was obtained and evaluated. The results are shown in Table 1.

Comparative Example 1
Instead of the dispersion of porous silica fine particles whose surface having a solid content concentration of 20% obtained in Reference Example 1 was modified with an organic group containing a methacryloyloxy group, the solid content concentration of 20% obtained in Reference Example 3 was used. A curable composition paint was obtained in the same manner as in Example 1 (a) except that a dispersion of porous silica fine particles on which the first silica coating layer was formed was used. When this paint was stored in a cool and dark place, precipitation occurred after one day.

  Next, in place of the curable composition obtained in Example 1 (a), the same operation as in Example 1 (b) was performed except that the curable composition obtained above was used. A substrate was obtained and evaluated. The results are shown in Table 1.

Claims (8)

  A curable composition comprising a cationically polymerizable compound and porous silica fine particles whose surface is modified with an organic group.   The curable composition according to claim 1, wherein the cationically polymerizable compound comprises a compound having at least two oxetane rings in the molecule.   The curable composition according to claim 1 or 2, wherein the cationic polymerizable compound comprises a compound having a silyl group in the molecule or a hydrolysis condensate thereof.   The curable composition according to any one of claims 1 to 3, wherein the porous silica fine particles have a double structure in which the surface is coated, and the coated surface is modified with an organic group.   The curable composition according to any one of claims 1 to 4, wherein the organic group that modifies the surface of the porous silica fine particle is an organic group containing an acryloyloxy group, a methacryloyloxy group, an epoxy ring, or an oxetane ring.   A film-coated substrate, wherein a film formed by curing the curable composition according to any one of claims 1 to 5 is formed on a surface of a transparent substrate.   The coated substrate according to claim 6, wherein the transparent substrate is a methyl methacrylate-styrene copolymer resin. The base material with a film according to claim 6 or 7, wherein the film has a refractive index of 1.20 to 1.45 and a film thickness of 0.01 to 1 µm and has an antireflection function.