Solvent-free organic-inorganic hybrid resin composition and cured film

Abstract

The invention provides a solvent-free organic-inorganic hybrid resin composition. The solvent-free organic-inorganic hybrid resin composition can provide a member having a high elastic modulus. The solvent-free organic-inorganic hybrid resin composition comprises the following components (A)-(C), and can obtain a self-supporting resin film after being fired at 230 DEG C or lower. (A) silica particles having an average primary particle diameter of 15-100 nm, and sulfate ions adhering to the silica particles as calculated by formula 1 below being 30 ppm or less; particle-attached sulfate ion (ppm) = combustion ion chromatography (ppm)-free ion chromatography (ppm) (Formula 1); (B) an epoxy resin having two or more epoxy groups and having a number average molecular weight of 150-3000 (inclusive); and (C) a curing agent.

Description

Technical Field

[0001] The present invention relates to a solvent-free organic-inorganic hybrid resin composition, a cured film obtained from the resin composition, and a method for producing the cured film. Background Art

[0002] In recent years, the electronic components used in electronic products such as display devices such as liquid crystal display devices and organic EL display devices, semiconductor devices, automatic correction digital cameras, noise reduction wireless headphones, high-precision inkjet printers, etc., are accompanied by high functionality, and need miniaturization, high precision, thin film (patent documentation 1,2,3,4). The required characteristics of these electronic components are supported by the electronic material resin composition of the resin represented by polyimide, acrylic acid, epoxy, and the resin composition need to possess the various mechanical properties such as fine processing, high elastic modulus, high toughness, high flexibility, transparency, low linear expansion coefficient, adhesion, water resistance (patent documentation 5,6,7). Wherein, high elastic modulus and high toughness are derived from the crystallinity and crosslinking in the composition after firing, and the internal structure of the composition required for both is opposite, and therefore it is difficult to take both into account only by resin component. Therefore, in order to take both into account, it has been proposed to add the scheme (patent documentation 8) of giving mechanical characteristics by nanoparticles represented by silica particles in the system.

[0003] In the future, as electronic products become smaller, more highly integrated, and thinner, the silica particles used to impart these properties will also need to have high compatibility (dispersibility) with resins from the perspective of molding processability. Furthermore, resin compositions and nano-silica particles will need to achieve higher elastic moduli than before.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-115080

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2022-147628

[0008] Patent Document 3: Japanese Patent No. 635872

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 2011-754

[0010] Patent Document 5: Japanese Patent Application Laid-Open No. 2017-179280

[0011] Patent Document 6: International Publication No. 2022 / 06741

[0012] Patent Document 7: Japanese Patent No. 5969375

[0013] Patent Document 8: Japanese Patent Application Laid-Open No. 2021-084322 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] The present invention has been developed in view of the above circumstances, and provides a solvent-free organic-inorganic hybrid resin composition capable of providing a member having a high elastic modulus.

[0016] Means of solving the problem

[0017] The present inventors have conducted intensive studies to solve the above problems and have found that a composition obtained from a silica particle dispersion obtained by ultrafiltration can exhibit a high elastic modulus without changing the silica particle system, thereby completing the present invention.

[0018] Therefore, the present invention provides the following solvent-free organic-inorganic hybrid resin composition and a cured film obtained from the resin composition.

[0019] 1. A solvent-free organic-inorganic hybrid resin composition comprising the following components (A) to (C), which can produce a self-supporting resin film after being sintered at a temperature below 230°C.

[0020] (A) silica particles, wherein the average primary particle size of the silica particles is 15 to 100 nm, and the amount of sulfate ions attached to the silica particles calculated by the following (Formula 1) is 30 ppm or less;

[0021] Particle-attached sulfate ion (ppm) = combustion ion chromatogram (ppm) - free ion chromatogram (ppm) (Formula 1);

[0022] (B) an epoxy resin having two or more epoxy groups and a number average molecular weight of 150 to 3000;

[0023] (C) Curing agent.

[0024] 2. The organic-inorganic hybrid resin composition according to 1, wherein the sodium content in the silica particles (A) is 50 ppm / SiO2 to 3000 ppm / SiO2.

[0025] 3. The organic-inorganic hybrid resin composition according to 1 or 2, wherein the silica particles (A) have a sphericity of 0.8 or greater.

[0026] 4. The organic-inorganic hybrid resin composition according to any one of 1 to 3, comprising 10% by mass or more of (A) silica particles relative to the total mass of the resin composition.

[0027] 5. The organic-inorganic hybrid resin composition according to any one of 1 to 4, wherein the epoxy resin (B) is at least one liquid epoxy resin selected from bisphenol A epoxy resin, bisphenol F epoxy resin, and alicyclic epoxy resin.

[0028] 6. The organic-inorganic hybrid resin composition according to any one of 1 to 5, wherein the curing agent (C) is any one selected from the group consisting of anhydride curing agents and amine curing agents.

[0029] 7. The organic-inorganic hybrid resin composition according to any one of 1 to 6, wherein the silica particles (A) are made from an organic solvent-dispersed silica sol obtained by solvent replacement by ultrafiltration.

[0030] 8. The organic-inorganic hybrid resin composition according to any one of 1 to 7, wherein the (A) silica particles are silica particles surface-modified with an organosilicon compound.

[0031] 9. The organic-inorganic hybrid resin composition according to any one of 1 to 8, wherein the (A) silica particles are silica particles surface-modified with phenyltrimethoxysilane.

[0032] 10. The organic-inorganic hybrid resin composition according to any one of 1 to 9, wherein the number of methoxy groups bonded to the particle surface of the (A) silica particles is 0.5 to 2.5 per nm. 2 .

[0033] 11. A cured film obtained from the hybrid resin composition according to any one of 1 to 10.

[0034] 12. A method for producing a cured film, comprising the step of baking the hybrid resin composition according to any one of 1 to 10.

[0035] 13. A silica sol comprising silica particles dispersed in an organic solvent, wherein the silica particles have an average primary particle size of 15 to 100 nm, a sulfate ion content adhering to the silica particles as calculated by the following (Equation 1) of 30 ppm or less, and a sodium content in the silica particles of 50 ppm / SiO2 to 3000 ppm / SiO2;

[0036] Particle-attached sulfate ion (ppm) = combustion ion chromatogram (ppm) - free ion chromatogram (ppm) (Formula 1).

[0037] 14. The silica sol according to 13, wherein the silica particles have a sphericity of 0.8 or greater.

[0038] 15. The silica sol according to 13 or 14, which is a material for forming a self-supporting composition for forming a resin thin film.

[0039] Effects of the Invention

[0040] According to the present invention, a member exhibiting a high elastic modulus and a composition providing the member can be provided. DETAILED DESCRIPTION

[0041] The solvent-free organic-inorganic hybrid resin composition of the present invention comprises the following components (A) to (C), and can provide a self-supporting film after being fired at 230° C. or lower.

[0042] (A) silica particles, wherein the average primary particle size of the silica particles is 15 to 100 nm, and the amount of sulfate ions attached to the silica particles calculated by the following (Formula 1) is 30 ppm or less;

[0043] Particle-attached sulfate ion (ppm) = combustion ion chromatogram (ppm) - free ion chromatogram (ppm) (Formula 1);

[0044] (B) an epoxy resin having two or more epoxy groups and a number average molecular weight of 150 to 3000;

[0045] (C) Curing agent.

[0046] <(A) Silica Particles>

[0047] The silica particles as component (A) are derived from a silica sol using an organic solvent as a dispersion medium. The silica sol using an organic solvent as a dispersion medium can be used in the form of an organic solvent-dispersed sol (organic solvent-dispersed silica sol, described below) in which colloidal silica particles are dispersed in an organic solvent. The organic solvent-dispersed silica sol used in the present invention can be produced by ultrafiltration of a water-dispersed silica sol produced by known methods (e.g., ion exchange, peptization, hydrolysis, reaction (oxidation) methods, etc.), followed by replacement with methanol and then with an organic solvent other than methanol.

[0048] Ultrafiltration is a method that uses an ultrafiltration membrane to remove solvents or molecules smaller than the membrane's pore size. Silica sol production using ultrafiltration is carried out by supplying an organic solvent (replacement solvent) such as methanol, in which the silica particles are to be dispersed, while allowing the pre-replacement solvent of the silica sol, such as water, to pass through the ultrafiltration membrane and be removed from the system. During this process, impurities dissolved in the solvent, such as sulfate ions, described later, are removed along with the pre-replacement solvent (such as water). Meanwhile, components dispersed in the solvent, such as the silica particles, remain in the system, resulting in solvent replacement. This produces silica sol replaced with the supplied organic solvent.

[0049] The ultrafiltration membrane used in ultrafiltration can be made of polypropylene, nylon, ceramics, etc. Any material can be used as long as it is insoluble in the solvent of the silica sol before and after the substitution. From the perspective of productivity, ceramics are preferred. For example, as the material of the ultrafiltration membrane (filter), ceramic materials such as aluminum oxide and titanium dioxide can be used. From the perspective of productivity, the shape of the filter membrane is preferably cylindrical. As for the pore size of the filter, any size can be used as long as the silica particles are not filtered and do not cause filter clogging.

[0050] Note that sulfate ions may be added as a stabilizer to commercially available aqueous silica sols, and thus ultrafiltration is preferably performed to remove sulfate ions from the system so that the amount of sulfate ions adhering to the silica particles is reduced to a predetermined amount or less.

[0051] On the other hand, by rapidly replacing the aqueous silica sol obtained from water glass with an alcohol solvent having 1 to 4 carbon atoms before adding sulfuric acid as a stabilizer, a silica sol dispersed in an alcohol having 1 to 4 carbon atoms can be obtained in which the concentration of free sulfate ions in the system is reduced to 10 ppm / SiO2 or less. In this case, rapid replacement with the alcohol solvent as the dispersion solvent is necessary from the perspective of silica sol stability.

[0052] The silica particles used in the present invention have an average primary particle size of 15 nm to 100 nm, and can be set to, for example, 15 nm to 55 nm. From the perspective of obtaining a thin film with high transparency with good reproducibility, the average primary particle size is preferably 15 nm to 50 nm, more preferably 15 nm to 45 nm, further preferably 15 nm to 35 nm, and even more preferably 15 nm to 30 nm.

[0053] In the present invention, the average primary particle size of the silica particles is an average value of primary particles calculated from specific surface area values ​​measured by a nitrogen adsorption method.

[0054] The silica particles used in the present invention have a sulfate ion content of 30 ppm or less, preferably 15 ppm or less, attached to the silica particles as calculated by the following (Formula 1).

[0055] Particle-attached sulfate ion (ppm) = combustion ion chromatogram (ppm) - free ion chromatogram (ppm) (Formula 1)

[0056] The above-mentioned "combustion ion chromatography" (ppm) is to collect the gas generated by burning and decomposing silica sol dispersed in an organic solvent as a sample into an absorption liquid, and then analyze the amount of sulfur (ppm) in the silica sol by ion chromatography. The sulfur content (SO4) converted from the sulfur content is used as the sulfur ion. 2- ) amount (ppm).

[0057] In addition, "free ion chromatography" (ppm) is measured by ion chromatography by adding an appropriate amount of water to a silica sol dispersed in an organic solvent as a sample, and the sulfate ions (SO4 2- ) amount (ppm) and the value obtained by analysis.

[0058] In addition, in this specification, sulfate ion is abbreviated as "SO4".

[0059] The silica particles used in the present invention preferably have a sodium content (concentration) of 50 ppm / SiO2 to 3000 ppm / SiO2, more preferably 200 ppm / SiO2 to 3000 ppm / SiO2, and even more preferably 300 ppm / SiO2 to 2500 ppm / SiO2. Using silica particles with a sodium content (concentration) of 3000 ppm / SiO2 or less is preferred because it does not affect the electrical properties of electronic materials. The sodium content of the silica particles can be adjusted to a specified level by contacting a water-dispersed silica sol with a cation exchange resin.

[0060] The sodium content (ppm) in the silica particles can be measured by subjecting a silica sol dispersed in an organic solvent as a sample to acid and heat treatment to remove the silica component, and then using an atomic absorption spectrophotometer.

[0061] It should be noted that in this application specification, the unit [ppm / SiO2] expressing concentration or content is the value obtained by dividing the sodium content measured by an atomic absorption spectrophotometer by the silica concentration in the silica sol dispersed in an organic solvent, and the sodium content relative to silica is expressed as ppm / SiO2.

[0062] The silica particles used as component (A) in the present invention preferably have a sphericity of 0.8 or greater, for example, 0.8 to 1.00, preferably 0.8 to 0.97 or 0.85 to 1.00.

[0063] Sphericity is defined as the ratio of the minimum diameter to the maximum diameter of a particle (minimum diameter / maximum diameter). In the present invention, the maximum diameter and minimum diameter of each of the target silica particles are measured by image analysis, and the average value of the sphericity of each particle (N ≥ 500) is calculated as the sphericity.

[0064] In addition, the silica particles used as component (A) in the present invention preferably have an organosilicon compound bound to the particle surface of 0.5 to 2.5 particles / nm in terms of dispersibility in the resin as described later. 2 .

[0065] <Organic Solvent Dispersed Silica Sol>

[0066] The silica sol used in the present invention is a dispersion of the above-mentioned silica particles dispersed in an organic solvent. It should be noted that the silica sol dispersed in the organic solvent is also the subject of the present invention.

[0067] Examples of the organic solvent include alcohols, ketones, hydrocarbons, amides, ethers, esters, cyclic esters, and amines.

[0068] Examples of the alcohols include alcohols having 2 to 5 carbon atoms, and specific examples include ethanol, isopropyl alcohol, and n-butanol.

[0069] Examples of the ketones include ketones having 1 to 5 carbon atoms, and specific examples include methyl ethyl ketone and methyl isobutyl ketone.

[0070] Examples of the hydrocarbons include toluene, xylene, n-pentane, n-hexane, and cyclohexane.

[0071] Examples of the amides include N,N-dimethylacetamide, N,N-dimethylformamide, N,N-dimethylacrylamide, 4-acryloylmorpholine, N,N-diethylacrylamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone.

[0072] Examples of the ethers include ethylene glycol monomethyl ether and propylene glycol monomethyl ether.

[0073] Examples of the esters include ethyl acetate and butyl acetate.

[0074] Examples of the cyclic esters include γ-butyrolactone and the like.

[0075] Examples of the amines include triethylamine, tributylamine, N,N-dimethylaniline, pyridine, and picoline.

[0076] As the organic solvent, ketones are preferred, and methyl ethyl ketone and methyl isobutyl ketone are particularly preferred, from the viewpoints of compatibility with the resin described below and ease of distillation removal during composition preparation.

[0077] As a method for solvent replacement of the silica sol dispersed in the alcohol having 1 to 4 carbon atoms with the organic solvent, there is mentioned a method of supplying the solvent to be replaced while removing the alcohol solvent having 1 to 4 carbon atoms under reduced pressure.

[0078] <Organic silicon compounds>

[0079] Furthermore, at least a portion of the surface of the silica particles contained in the silica sol may be modified with an organosilicon compound or its hydrolyzate. Surface modification with an organosilicon compound renders the silica particle surface hydrophobic, thereby improving dispersibility even in water-insoluble organic solvents. For example, the surface-modified particles have a structure in which the organosilicon compound is bonded to the hydroxyl groups on the silica particle surface.

[0080] As the organosilicon compound used in the surface modification treatment, publicly known organosilicon compounds and other silane compounds known as silane coupling agents can be used, and the type thereof is appropriately selected depending on the application, the type of solvent, etc. Multiple organosilicon compounds may be used in combination.

[0081] Specific examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-vinylphenyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3- Aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-[methoxy-poly(ethyleneoxy)propyl]trimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, etc.

[0082] Specific examples of the silane compounds include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane, hexamethyldisiloxane, and hexamethyldisilazane.

[0083] Among them, for example, phenyltrimethoxysilane can be mentioned as a preferred example.

[0084] The amount of surface treatment (modification) performed with the above-mentioned organosilicon compound, that is, the amount of the organosilicon compound covering or bonding to the surface of the silica particles, is calculated based on the amount of silica particles per nm. 2 The surface area can be set to, for example, a range of about 0.5 to 2.5.

[0085] The method for producing surface-modified silica particles, i.e., the method for covering the surface of the silica particles with the above-mentioned organosilicon compound (surface treatment), is not particularly limited. For example, by adding at least one of the above-mentioned organosilicon compounds and, if necessary, a highly soluble solvent such as ketones to an organic solvent dispersion of the silica particles and mixing them, hydrolysis and condensation of the organosilicon compound can occur, thereby surface-modifying the silica particles.

[0086] The amount of organic silicon compound added at this time can be as follows: 2 The surface area of ​​the silica particles is modified by adding the organosilicon compound to the system so that the number of particles per 1 nm is about 0.5 to 2.5. 2 The organosilicon compound is added to the silica particles in an amount of 0.5 to 10.0, or 1.0 to 8.0, or 1.0 to 6.0 particles per 1 nm of surface area. It should be noted that the residual organosilicon compound that does not contribute to surface modification may exist in the system. The preferred amount of organosilicon compound added is 100 to 100 particles per 1 nm of surface area. 2 There are 1.0 to 6.0 on the surface area.

[0087] The hydrolysis of the organosilicon compound can be complete or partial, but water is required. Preferably, about 1 mol or more of water is added per mol of the hydrolyzable groups, [Si-O-Si] bonds, or [Si-N-Si] bonds in the organosilicon compound. Alternatively, the water contained in the organic solvent can be utilized.

[0088] When using an organosilicon compound having a hydrolyzable group, complete or partial hydrolysis may be performed, but water is required. It is preferred to add about 1 mol or more of water per mol of the hydrolyzable group in the organosilicon compound. Alternatively, the water contained in the organic solvent may be utilized.

[0089] A catalyst may be used when hydrolyzing and condensing the organosilicon compound. As the hydrolysis catalyst, a chelate compound, an organic acid, an inorganic acid, an organic base, or an inorganic base may be used alone or in combination. More specifically, for example, aqueous hydrochloric acid, acetic acid, or aqueous ammonia solution may be used.

[0090] From the viewpoint of improving the solubility of the organosilicon compound and the surface modification rate, the surface modification step of the silica particles is preferably performed at the stage of an alcohol sol having 1 to 4 carbon atoms.

[0091] It should be noted that in the above-mentioned silica particles, the number of alkoxy groups, such as methoxy groups, bonded to the particle surface can be set to 0.5 to 2.5 per nm. 2 .

[0092] Here, the alkoxy groups (e.g., methoxy groups) bonded to the particle surface include not only those derived from the organosilicon compound (alkoxy-containing silane compound) used for surface modification but also, if the silica particles contained in the resin composition of the present invention are alcohol-sol, those formed by the alcohol (e.g., methanol) bonding to the particle surface in the form of alkoxy groups (e.g., methoxy groups). Therefore, the amount of alkoxy group bonding can be measured regardless of the presence or absence of such surface modification.

[0093] The amount of alkoxy (methoxy) bonds can be obtained by allowing a strong base such as sodium hydroxide to act on target silica particles and measuring the amount of alcohol derived from free alkoxy groups.

[0094] <(B) Epoxy Resin>

[0095] The epoxy resin as component (B) of the composition of the present invention has two or more epoxy groups and a number average molecular weight of 150 or more, for example, 200 or more. Examples of such epoxy resins include epoxy resins used as reactive diluents.

[0096] Among such epoxy resins, examples of polyfunctional epoxy reactive diluents having two epoxy groups include bisphenol-A epoxy resins, bisphenol-F epoxy resins, bisphenol-S epoxy resins, bisphenol-AS epoxy resins, bisphenol-AD epoxy resins, tetrabromobisphenol-A epoxy resins, and other bisphenol-type epoxy resins, and hydrogenated bisphenol-type epoxy resins obtained by hydrogenating these resins; oxazolidinone epoxy resins obtained by reacting bisphenol-A epoxy resins with bifunctional isocyanates; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,2-butanediol diglycidyl ether, 1,3-butanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 2,3-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether. ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,4-cyclohexanedimethanol diglycidyl ether; alkylene glycol type epoxy resins such as diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether; resorcinol diglycidyl ether, hydroquinone diglycidyl ether, 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl diglycidyl ether, diglycidyl ether of 1,6-dihydroxynaphthalene, diglycidyl ether of 9,9-bis(4-hydroxyphenyl)fluorene, diglycidyl aniline, biphenyl type epoxy resins, and naphthalene type epoxy resins.

[0097] Examples of the polyfunctional epoxy reactive diluent having three or more epoxy groups include novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and naphthol novolac-type epoxy resins; triglycidyl ether of tris(p-hydroxyphenyl)methane, tetraglycidyl ether of tetra(p-hydroxyphenyl)ethane, triglycidyl isocyanurate, triglycidyl ether of glycerol, and tetraglycidyl ether of pentaerythritol; and glycidylamine compounds such as tetraglycidyldiaminodiphenylmethane, tetraglycidylm-xylenediamine, triglycidylm-aminophenol, and triglycidylp-aminophenol.

[0098] In addition, as the epoxy resin having two or more epoxy groups, a commercially available compound can be used from the viewpoint of easy availability. Specific examples (trade names) are listed below, but are not limited to these: epoxy resins having amino groups, such as YH-434 and YH-434L (manufactured by Tohto Kasei Co., Ltd. (now Nippon Steel Chemicals Co., Ltd.)); alicyclic epoxy resins having a cyclohexene oxide structure, such as Epirote GT-401, Epirote GT-403, Epirote GT-301, Epirote GT-302, Celokiside 2021, and Celokiside 3000 (manufactured by Daicel Co., Ltd.); jER (registered trademark) 1001, jER 1002, jER 1003, jER 1004, jER 1007, and jER Bisphenol A type epoxy resins such as 828 (manufactured by Mitsubishi Chemical Corporation); bisphenol F type epoxy resins such as jER (registered trademark) 807 (manufactured by Mitsubishi Chemical Corporation); Denacole EX-252 (manufactured by Nagasekemtech Co., Ltd.), CY175, CY177, CY179, Aladait CY-182, Aladait CY-192, Aladait CY-184 (manufactured by CIBA-GEIGY AG), Epichrome 200, Epichrome 400 (manufactured by DIC Corporation), jER (registered trademark) 871, jER Alicyclic epoxy resins such as 872 (the above products are manufactured by Mitsubishi Chemical Co., Ltd.), ED-5661 and ED-5662 (the above products are manufactured by Syracuse Chemical Co., Ltd.);コールEX-611、デナコールEX-612、デナコールEX-614、デナコールEX-622、デナコールEX-411、デナコールE X-512、Dynamic EX-522、Dynamic EX-421、Dynamic EX-313、Dynamic EX-314、Dynamic EX-3 Trivalent epoxy compounds having a triazine skeleton such as aliphatic polyglycidyl ethers such as 21 (manufactured by Nissan Chemical Co., Ltd.) and TEPIC (registered trademark) (manufactured by Nissan Chemical Co., Ltd.).

[0099] Among these epoxy resins, the number average molecular weight of the epoxy resin is 150 to 3000. From the perspective of handling, the number average molecular weight is preferably 150 to 2000, and more preferably 200 to 1000. When the number average molecular weight is 3000 or more, the viscosity becomes high, making handling difficult. In addition, as a physical state, a liquid epoxy resin is preferred, and a liquid epoxy resin selected from any one of bisphenol A epoxy resin, bisphenol F epoxy resin, and alicyclic epoxy resin is particularly preferred.

[0100] The amount of epoxy resin added is preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and even more preferably 20 to 40 parts by mass per 100 parts by mass of the silica particles. By setting the amount of epoxy resin added within the above range, the composition can be adjusted to any viscosity.

[0101] <(C) Curing Agent>

[0102] The component (C) of the composition of the present invention is a curing agent for the epoxy resin (B).

[0103] Curing agents can be roughly divided into three types: polyaddition type curing agents, catalyst type curing agents, and condensation type curing agents, and one or more types of these can be used.

[0104] Examples of such curing agents include acid anhydride-based, amine-based, phenolic resin-based, polyamide resin-based, imidazole-based, and polythiol-based curing agents.

[0105] These curing agents can be used in such an amount that the curing groups of the curing agent that react with the epoxy groups are in a ratio of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, relative to the epoxy groups of the epoxy resin (B).

[0106] Even if these curing agents are solid, they can be used by dissolving them in a solvent. However, after curing the resin composition of the present invention, there is a possibility that the density of the cured product will decrease due to evaporation of the above-mentioned solvent, and the strength and water resistance will decrease due to the formation of pores. Therefore, it is preferred that the curing agent itself is liquid at room temperature and normal pressure.

[0107] Specific examples of the curing agent are as follows.

[0108] As the acid anhydride, an acid anhydride of a compound having multiple carboxyl groups in the molecule is preferred. Examples of such acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, ethylene glycol ditrimellitate, glycerol trimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride (also known as methyl-5-norbornene-2,3-dicarboxylic anhydride, methylnadic anhydride, methylbicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride (also known as hydrogenated methylnadic anhydride), methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic anhydride, and chlorendic anhydride. These may be used alone or in combination of two or more.

[0109] Among these, preferred are methyltetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride (also known as methyl-5-norbornene-2,3-dicarboxylic anhydride, methylnadic anhydride, or methylnadic anhydride), methylbicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride (also known as hydrogenated methylnadic anhydride), methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, methylhexahydrophthalic anhydride, or a mixture of methylhexahydrophthalic anhydride and hexahydrophthalic anhydride, which are liquid at room temperature and pressure. The viscosity of these liquid anhydrides, as measured at 25°C, is approximately 10 to 1000 mPa·s.

[0110] Examples of the amines include piperidine, N,N-dimethylpiperazine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menthenediamine, isophoronediamine, diaminodicyclohexylmethane, 1,3-diaminomethylcyclohexane, xylylenediamine, m-phenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

[0111] Among them, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menthene diamine, isophoronediamine, diaminodicyclohexylmethane, etc., which are liquid at room temperature and pressure, can be preferably used.

[0112] Examples of the phenolic resin include phenol novolac resin and cresol novolac resin.

[0113] Examples of the polyamide resin include polyamide amines produced by condensation of a dimer acid and a polyamine and having a primary amine and a secondary amine in the molecule.

[0114] Examples of the imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, and epoxyimidazole adducts.

[0115] The polythiol is, for example, a polythiol having a thiol group at the end of a polypropylene glycol chain or a polythiol having a thiol group at the end of a polyethylene glycol chain, and is preferably a liquid polythiol.

[0116] Among these curing agents, acid anhydride curing agents and amine curing agents are preferred because they are liquid at normal temperature and pressure.

[0117] In addition, when obtaining the above-mentioned cured product, a curing aid (also called a curing accelerator) may be appropriately used in combination. Examples of the curing aid include organic phosphorus compounds such as triphenylphosphine and tributylphosphine, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide and diethyl tetrabutylphosphonium dithiophosphate, 1,8-diazabicyclo(5,4,0)undec-7-ene, a salt of 1,8-diazabicyclo(5,4,0)undec-7-ene and octanoic acid, zinc octanoate, and quaternary ammonium salts such as tetrabutylammonium bromide.

[0118] These curing aids may be contained in a ratio of 0.001 to 0.1 parts by mass per 1 part by mass of the curing agent, or in a ratio of 0.001 to 0.1 equivalents per epoxy group of the epoxy resin.

[0119] <Solvent-free organic-inorganic hybrid resin composition>

[0120] The solvent-free organic-inorganic hybrid resin composition of the present invention is obtained by adding an epoxy resin having two or more epoxy groups and a curing agent to a silica sol containing an organic solvent as a dispersion medium (organic solvent-dispersed silica sol), and then distilling off the dispersion medium (organic solvent of the silica sol) to form a dispersion in which silica particles are dispersed in the epoxy resin.

[0121] In the solvent-free organic-inorganic hybrid resin composition, the amount of the silica particles (calculated as SiO2) is 10% by mass or more, for example, 10% by mass or more and 50% by mass or less, 10% by mass or more and 25% by mass or less.

[0122] The solvent-free organic-inorganic hybrid resin composition of the present invention is, as described above, a composition comprising the aforementioned components (A) to (C) in a preferred embodiment. Furthermore, except where unavoidable, the composition preferably contains as little solvent as possible. If the resin composition of the present invention contains a solvent, the amount thereof can be controlled to be 0.1% by mass or less relative to the total amount of the composition.

[0123] The resin composition of the present invention may further contain other epoxy compounds, surfactants, adhesion promoters, and the like as needed within a range that does not impair the effects of the present invention.

[0124] Self-supporting resin film (cured film)

[0125] The solvent-free organic-inorganic hybrid resin composition of the present invention described above can be coated on a substrate or filled into an injection mold and then heated (fired) to obtain a self-supporting resin film having a high elastic modulus.

[0126] Furthermore, the above-mentioned resin film, that is, a resin film (cured film) comprising the above-mentioned silica particles, epoxy resin, and curing agent is also an object of the present invention.

[0127] Examples of the substrate used in the production of the resin film include plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene resins, etc.), metals, stainless steel (SUS), wood, paper, glass, silicon wafers, and stone slabs.

[0128] Especially when used as a substrate material for electronic devices, glass or silicon wafers are preferred because existing equipment can be utilized. Furthermore, glass is more preferred because the resulting resin film exhibits good releasability from the substrate. The linear expansion coefficient of the substrate is preferably 30 ppm / °C or less, and even more preferably 20 ppm / °C or less, to prevent warping of the substrate after coating.

[0129] The coating method for coating the solvent-free organic-inorganic hybrid resin composition on the substrate is not particularly limited. Examples thereof include cast coating, spin coating, blade coating, dip coating, roll coating, rod coating, die coating, inkjet coating, and printing methods (such as relief printing, gravure printing, lithography, and screen printing). These methods can be appropriately used depending on the intended purpose.

[0130] As the injection mold, one preferably includes a fluororubber spacer having a thickness of about 1 mm inserted between two glass plates treated with a fluorine-based mold release agent.

[0131] Examples of the injection mold include a glass plate and a metal mold.

[0132] The above-mentioned heating temperature is preferably below 230°C. When it exceeds 230°C, the necessary dimensional stability and mechanical properties are lacking, and the target resin film may not be obtained. The heating temperature can be set to, for example, above 40°C and below 230°C, and can also be set to, for example, above 40°C and below 200°C. In addition, if the heat resistance and linear expansion coefficient characteristics of the obtained resin film are taken into consideration, it is preferred that the coated resin composition is heated at 40°C to 100°C for 5 minutes to 2 hours, and then the heating temperature is directly increased in stages, and finally heated at a temperature above 140°C and below 180°C for 5 minutes to 2 hours. In this way, by heating at temperatures above two stages, namely, the stage of drying the solvent and the stage of promoting molecular orientation, low thermal expansion characteristics can be exhibited.

[0133] The apparatus used for heating includes, for example, a hot plate, an oven, etc. The heating atmosphere may be air or an inert gas such as nitrogen, and may be under normal pressure or reduced pressure. Different pressures may be applied at each stage of heating.

[0134] The thickness of the resin film is not particularly limited, but is usually 3 mm or less, preferably about 1 μm to 1.5 mm, and more preferably about 5 μm to 1.3 mm. The coating thickness before heating and the spacer are adjusted to form a resin film of a desired thickness.

[0135] The method for peeling the thus formed resin film from the substrate is not particularly limited, and examples thereof include a method of cooling the resin film together with the substrate, a method of peeling by cutting a slit in the film, and a method of peeling by applying tension with a roller.

[0136] The resin film having a high elastic modulus according to a preferred embodiment of the present invention thus obtained exhibited a significantly higher elastic modulus of 1.4 GPa in a tensile test, compared to the 1.2 GPa obtained using a conventional silica sol that had undergone solvent exchange by gas blowing. The resin film of the present invention is characterized by the fact that, using a silica sol dispersed in an organic solvent obtained by solvent exchange by ultrafiltration as the silica particle raw material, the concentration of sulfate ions adhering to the silica particles is significantly lower than that of silica particles made from conventional silica sols that had undergone solvent exchange by gas blowing.

[0137] The solvent-free organic-inorganic hybrid resin composition of the present invention described above can provide a resin film having the above-mentioned properties and can therefore be suitably used as a material for a resin film useful as an electronic material.

[0138] Example

[0139] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[0140] [Determination of SiO2 concentration]

[0141] A silica sol dispersed in an organic solvent (methanol, MEK) was placed in a crucible, dried at 130°C, and then calcined at 1000°C. The calcined residue was measured and the SiO2 concentration (%) was calculated.

[0142] [Measurement of average primary particle size (nitrogen adsorption particle size)]

[0143] The methanol-dispersed silica sol was dried at 300° C. to obtain a powder. The specific surface area was measured using a specific surface area measuring apparatus, MONOSOB (registered trademark) MS-16 (manufactured by Yuasa Ionics Co., Ltd.), and the average primary particle size (nm) was determined.

[0144] [Viscosity measurement]

[0145] The viscosity (mPa·s) of silica sol dispersed in an organic solvent (methanol, MEK) was measured using an Ostwald viscometer.

[0146] [Measurement of average particle size by dynamic light scattering]

[0147] The average particle size of the silica sol dispersed in methyl ethyl ketone (MEK) was measured by dynamic light scattering. The sol was diluted with MEK to a predetermined concentration and measured using a dynamic light scattering particle size analyzer (ZETASIZER Nano series, manufactured by Malvern Instruments LTD).

[0148] [pH measurement]

[0149] The pH of the silica sol dispersed in methyl ethyl ketone (MEK) was measured using a pH meter (MM-43X, manufactured by DKK Toa Co., Ltd.) on a mixture of the silica sol, methanol, and pure water at a mass ratio of 1:1:1. The pH measured by this method is referred to as pH (1+1+1).

[0150] [Water content]

[0151] The amount of water (%) contained in the silica sol dispersed in an organic solvent (methanol, MEK) was measured by Karl Fischer titration using a Karl Fischer titrator (manufactured by Kyoto Electronics Co., Ltd., trade name: MKA-610).

[0152] [Organic solvent content]

[0153] The content (%) of the organic solvent (methanol) in the silica sol dispersed in methyl ethyl ketone (MEK) was measured by gas chromatography (Shimadzu Corporation, GC-2014s).

[0154] [Analysis method for the amount of methoxy groups bonded to the particle surface]

[0155] To 4 ml of silica sol dispersed in methyl ethyl ketone (MEK), 20 ml of n-hexane was added, and the mixture was centrifuged (5000 rpm, 30 minutes). The supernatant was discarded to isolate the precipitate. The precipitate was further redissolved in 4-8 ml of acetone, and then 10 ml of n-hexane was added again. The precipitate was isolated by centrifugation (5000 rpm, 30 minutes). This operation was repeated twice. The resulting precipitate was dried in a vacuum dryer at 60°C for 4 hours, and then in a dryer at 150°C for 2 hours to obtain a dry powder.

[0156] 0.2 g of the powder obtained above was mixed with 5 mL of 0.1 N sodium hydroxide aqueous solution and 5 mL of pure water. After standing at room temperature for 1 day, the methanol contained in the solution was measured by gas chromatography to determine the methoxy group bond amount per unit area of ​​the silica surface (number / nm). 2 ).

[0157] [Analysis Method for Sodium Content in Silica Particles]

[0158] The methanol-dispersed silica sol was collected in a platinum dish, and ultrapure water, hydrochloric acid, sulfuric acid, and hydrofluoric acid were added and heated to remove the silica component. Ultrapure water was then added to adjust the concentration to prepare the measurement stock solution. The measurement stock solution was diluted to a specified ratio, and the sodium content in the silica sol was measured using an atomic absorption spectrophotometer (55BAA, SpectrAA, manufactured by Agilent Technologies). The sodium concentration relative to silica (ppm / SiO2) was then calculated by dividing the sodium concentration by the silica concentration in the silica sol.

[0159] [Analysis Method of Sulfate Ion Amount Adhering to Silica Particles]

[0160] 25-50 μL of MEK-dispersed silica sol and 0.1 g of tungsten oxide (WO3) were treated using a combustion apparatus (AQF-2100H, GA-210, manufactured by Nitto Seiko Electron Technology). The generated gas was absorbed into 5 mL of an absorbing liquid. The absorbing liquid was analyzed using ion chromatography (Integrion, manufactured by ThermoFisher Scientific) to determine the sulfur content (ppm) in the silica sol. The SO4-equivalent value was calculated from the obtained sulfur content and designated as the combustion ion chromatogram "A" (ppm).

[0161] Next, 0.1 g of MEK-dispersed silica sol and 5 mL of water were measured and mixed. After removing the precipitate with a syringe filter, the sample was analyzed using ion chromatography (Integrion, manufactured by Thermo Fisher Scientific) to measure the amount of SO4 free formed in the sol (ppm) as the free ion chromatogram "B".

[0162] The particle-attached sulfate ion "C" (ppm) was calculated from the following formula 1.

[0163] C=AB···(Formula 1)

[0164] [Analysis method for the amount of free sulfate ions in silica sol]

[0165] Using the target silica sol (methanol-dispersed silica sol), ion chromatography analysis was performed in the same manner as for the MEK-dispersed silica sol described above. The amount of SO₄ (ppm) released in the methanol-dispersed silica sol was measured. This amount was divided by the silica concentration in the silica sol to calculate the amount of sulfate ions (SO₄) released in the methanol-dispersed silica sol (ppm / SiO₂).

[0166] [Sphericity measurement method]

[0167] The number of silica particles in a methanol-dispersed silica sol was measured using a TEM (JEM-1400 Flash, manufactured by JEOL Ltd.) and an image analyzer (LUZEX-AP, manufactured by Nileko Co., Ltd.) was used to analyze the particles. The maximum and minimum diameters of each particle were measured, and the average value of [minimum diameter / maximum diameter] was calculated.

[0168] Example 1

[0169] Snotex (registered trademark) O-40 (average primary particle size 22 nm, pH 2-3, silica concentration 40% by mass, manufactured by Nissan Chemical Industries, Ltd.) was prepared.

[0170] 14,000 g of the silica sol was replaced with methanol by ultrafiltration. Replacement was completed when the water content in the sol reached 0.5%, yielding 14,000 g of methanol-dispersed silica sol. The resulting methanol-dispersed silica sol 1 had a SiO concentration of 40.6% by mass, a water content of 0.5% by mass, a viscosity of 5.4 mPa·s, a sodium content within the silica particles of 2210 ppm / SiO, and a free SO₄ content of 0.7 ppm / SiO₂. Furthermore, the average primary particle size was 21.4 nm, and the sphericity was 0.89.

[0171] 1000 g of the methanol sol was placed in a 2 L eggplant flask. While stirring the sol with a magnetic stirrer, 24.7 g of ultrapure water was added. Then, 49.6 g of phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-103) was added, and the liquid temperature was maintained at 60°C for 2 hours. Then, 0.57 g of diisopropylethylamine was added while stirring, and the liquid temperature was maintained at 62°C for 2 hours.

[0172] Then, while the solvent was evaporated by a rotary evaporator at a reduced pressure of 500 to 450 Torr and a bath temperature of 80° C., MEK was supplied to replace the dispersion medium of the sol with MEK. This yielded a transparent MEK-dispersed silica sol 1 (SiO 40.4 mass%, viscosity (20° C.) 2.0 mPa·s, pH (1+1+1) 7.5, water content 0.1 mass%, methanol content 0.1 mass%, average particle size as determined by dynamic light scattering 30 nm, and methoxy group bond count on the silica particles 1.2 / nm). 2 ).

[0173] Tables 1 and 2 show various physical properties of the methanol-dispersed silica sol 1 and the MEK-dispersed silica sol 1.

[0174] Comparative Example 1

[0175] 1000 g of Snotex (registered trademark) O-40 (average primary particle size 22 nm, pH 2-3, silica concentration 40% by mass, manufactured by Nissan Chemical Industries, Ltd.) described in Example 1 was placed in a 2 L glass reactor equipped with a stirrer, condenser, thermometer, and two inlets. While the sol in the reactor was boiling, methanol vapor generated from a separate boiler was continuously blown into the silica sol in the reactor, gradually raising the liquid level while replacing the water with methanol. The replacement was completed when the volume of the distillate reached 9 L, yielding 1100 g of methanol-dispersed silica sol 2. The resulting methanol-dispersed silica sol 2 had a SiO concentration of 40.7 mass%, a water content of 2.1 mass%, a viscosity of 2.2 mPa·s, a sodium content within the silica particles of 2200 ppm / SiO, and a free SO₄ content of 450 ppm / SiO₂. Furthermore, the average primary particle size was 21.9 nm, and the sphericity was 0.89.

[0176] 1000 g of the methanol sol was placed in a 2 L eggplant flask, and while stirring the sol with a magnetic stirrer, ultrapure water was not added. A series of operations, including the addition of phenyltrimethoxysilane, the addition of diisopropylethylamine, and the replacement of the dispersion medium of the sol, were carried out in the same manner as in Example 1. A transparent MEK-dispersed silica sol 2 (SiO2 40.7 mass%, viscosity (20°C) 2.1 mPa·s, pH (1+1+1) 6.7, water content 0.1 mass%, methanol content 0.1 mass%, particle size as determined by dynamic light scattering method 32 nm, and methoxy group bonding number on the silica particles 2.2 / nm) was obtained. 2 ).

[0177] Tables 1 and 2 show various physical properties of the methanol-dispersed silica sol 2 and the MEK-dispersed silica sol 2.

[0178] [Production of epoxy cured products]

[0179] MEK-dispersed silica sol 1 (20 g) and 18.1 g of epoxy resin (jER828) were added to an eggplant-shaped flask and dissolved. The solvent was then removed using an evaporator (bath temperature 80°C, 300-30 Torr) to obtain an epoxy resin-dispersed monomer sol. 10 g of the resulting epoxy resin-dispersed monomer sol, 5.3 g of an acid anhydride curing agent (MH-700, manufactured by Shin Nippon Rika Co., Ltd.), and 0.07 g of a phosphonium salt-based curing accelerator (PX-4ET, manufactured by Nippon Chemical Industry Co., Ltd.) were placed in a container and stirred and mixed using a vacuum degassing machine (V-mini300, manufactured by EME Corporation) to obtain a varnish (solventless organic-inorganic hybrid resin composition). The obtained varnish was injected into an injection mold (a 1 mm thick fluororubber spacer was inserted between two glass plates treated with a fluorine-based mold release agent) and heated at 70°C for 2 hours, 90°C for 2 hours, and 150°C for 8 hours to obtain an epoxy resin cured product.

[0180] The same operation as above was carried out on the MEK-dispersed silica sol 2 of Comparative Example 1 to obtain an epoxy resin cured product.

[0181] Reference example without silica particles: As Neat, an epoxy resin (jER828) 10 g, an acid anhydride curing agent (MH-700) 7.9 g, and a phosphonium salt curing agent (PX-4ET) 0.10 g were used to obtain an epoxy resin cured product in the same manner as in Example 1.

[0182] Table 3 shows the composition of each cured product.

[0183] [Tensile test of cured epoxy resin]

[0184] Each cured epoxy resin product was cut into pieces 10 mm wide and 70 mm long and subjected to a tensile test using a desktop universal testing machine (AGS-5kNXSTD, manufactured by Shimadzu Corporation) to evaluate the elastic modulus (GPa). The tensile test was performed at a tensile speed of 10 mm / min, using a metal plate (1 kN) as the tensile fixture, and a 10 mm distance between the fixtures.

[0185] The obtained results are shown in Table 3.

[0186] Table 1 Physical properties of methanol-dispersed silica sol

[0187] [Table 1]

[0188]

[0189] Table 2 Physical properties of MEK-dispersed silica sol

[0190] [Table 2]

[0191]

[0192] Table 3 Epoxy resin curing material composition and tensile test

[0193] [Table 3]

[0194]

[0195] As can be seen from the results in Table 3, the cured product of Example 1, which used an epoxy resin-dispersed monomer sol containing silica particles with a sulfate ion content of 30 ppm or less attached to the silica particles, was confirmed to have an improved elastic modulus compared to the cured product of Comparative Example 1 containing silica particles with a high content of attached sulfate ions and the cured product of Neat using only epoxy resin (without silica particles).

Claims

1. A solvent-free organic-inorganic hybrid resin composition comprising the following components (A) to (C), which can produce a self-supporting resin film after being sintered at a temperature below 230°C. (A) silica particles, wherein the average primary particle size of the silica particles is 15 to 100 nm, and the amount of sulfate ions attached to the silica particles calculated by the following (Formula 1) is 30 ppm or less; (B) an epoxy resin having two or more epoxy groups and a number average molecular weight of 150 to 3000; (C) a curing agent, Particle-attached sulfate ion (ppm) = combustion ion chromatogram (ppm) - free ion chromatogram (ppm) (Formula 1). 2 . The organic-inorganic hybrid resin composition according to claim 1 , wherein the sodium content in the silica particles (A) is 50 ppm / SiO 2 to 3000 ppm / SiO 2 . The organic-inorganic hybrid resin composition according to claim 1 or 2, wherein the silica particles (A) have a sphericity of 0.8 or greater. The organic-inorganic hybrid resin composition according to any one of claims 1 to 3, comprising 10% by mass or more of (A) silica particles based on the total mass of the resin composition. 5 . The organic-inorganic hybrid resin composition according to claim 1 , wherein the epoxy resin (B) is at least one liquid epoxy resin selected from bisphenol A epoxy resin, bisphenol F epoxy resin and alicyclic epoxy resin. 6 . The organic-inorganic hybrid resin composition according to claim 1 , wherein the curing agent (C) is any one selected from the group consisting of anhydride curing agents and amine curing agents. 7 . The organic-inorganic hybrid resin composition according to claim 1 , wherein the silica particles (A) are made of an organic solvent-dispersed silica sol obtained by solvent replacement by ultrafiltration. 8 . The organic-inorganic hybrid resin composition according to claim 1 , wherein the silica particles (A) are silica particles surface-modified with an organosilicon compound. 9 . The organic-inorganic hybrid resin composition according to claim 1 , wherein the silica particles (A) are silica particles surface-modified with phenyltrimethoxysilane.

10. The organic-inorganic hybrid resin composition according to any one of claims 1 to 9, wherein the number of methoxy groups bonded to the surface of the silica particles (A) is 0.5 to 2.5 per nm 2 . 11 . A cured film obtained from the hybrid resin composition according to claim 1 . 12 . A method for producing a cured film, comprising the step of baking the hybrid resin composition according to claim 1 .

13. A silica sol comprising silica particles dispersed in an organic solvent, wherein the silica particles have an average primary particle size of 15 to 100 nm, a sulfate ion content adhering to the silica particles as calculated by the following (Equation 1) of 30 ppm or less, and a sodium content in the silica particles of 50 ppm / SiO2 to 3000 ppm / SiO2; Particle-attached sulfate ion (ppm) = combustion ion chromatogram (ppm) - free ion chromatogram (ppm) (Formula 1). The silica sol according to claim 13 , wherein the silica particles have a sphericity of 0.8 or greater. The silica sol according to claim 13 or 14, which is a material for forming a self-supporting composition for forming a resin thin film.

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