Laminated body including low refractive index film and manufacturing method thereof

Abstract

To provide a coating composition that is capable of forming a film with high adhesion and a low refractive index on a substrate by forming a coating film with a specific thickness using a coating composition containing irregularly shaped silica particles, and a transparent laminate having a low refractive index, which is obtained by coating the coating composition and curing a resulting material.SOLUTION: There is provided a transparent laminate on a substrate, which is configured to: contain silica particles derived from silica sol; and have a ratio (D1) / (D2) of a particle diameter (D1) measured by a dynamic light scattering method to a particle diameter (D2) measured by a nitrogen gas adsorption method of 2 or greater in the silica particles, a refractive index of 1.20 to 1.33, a film thickness of 100 to 2000 nm, and an adhesion in which a remaining percentage of squares obtained by etching a cross cut of 25 squares of 1 mm×1 mm onto a cured film on an obtained substrate and pasting and peeling off with an adhesive tape is become (20 to 25) / (25). A total light transmittance is 93% or greater. A value of HAZE is 2.0 or less. A carbon content is 1 mass% or less based on a content of SiO2 of silica particles.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a laminate including a low refractive index film and a method for producing the same. [Background technology]

[0002] Laminates having low refractive index films are used in various display panels such as liquid crystal display panels and organic EL displays, as well as window glass, optical lenses, image sensors, etc., to prevent the transfer of external light and improve image quality.

[0003] As low refractive index film materials for anti-reflection coating applications, for example, fluororesin-based low refractive index film materials including fluoropolymers (Patent Documents 1 to 3), low refractive index film materials including metal oxides and resins (Patent Documents 4 to 5), and low refractive index film materials using metal oxides, fluorine-containing organic compounds, or the like in a single layer have been disclosed (Patent Documents 6 to 7).

[0004] When a metal oxide or a fluorine-containing organic compound is used as a single layer, a gas phase method such as a vacuum deposition method, an ion-assisted deposition method, or a sputtering method has been used. However, this method has a drawback in that the production cost is high because the equipment required is expensive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 59-189108 [Patent Document 2] Japanese Patent Application Publication No. 7-331115 [Patent Document 3] Japanese Patent Publication No. 2-19801 [Patent Document 4] Patent Publication No. 2007-052345 [Patent Document 5] International Publication No. 2014 / 042129 [Patent Document 6] Patent Publication No. 2009-92746 [Patent Document 7] International Publication No. 2021 / 024834 Summary of the Invention [Problem to be solved by the invention]

[0006] To provide a coating composition containing irregularly shaped silica particles, capable of forming a coating film having high adhesion and a low refractive index on a substrate by forming a coating film with a specific thickness, and to provide a transparent laminate having a low refractive index formed by applying and curing the coating composition. [Means for solving the problem]

[0007] According to a first aspect of the present invention, there is provided a transparent laminate on a substrate, comprising silica particles derived from a silica sol, the silica particles having a ratio (D1) / (D2) of a particle size (D1) measured by a dynamic light scattering method to a particle size (D2) measured by a nitrogen gas adsorption method of 2 or more, the silica particles having a refractive index of 1.20 to 1.33, a film thickness of 100 to 2000 nm, and adhesion such that 25 cross-cuts of 1 mm x 1 mm are formed in the cured coating film obtained on the substrate, and the proportion of remaining masses after application and peeling of an adhesive tape is (20 to 25) / (25); As a second aspect, the transparent laminate according to the first aspect, wherein a ratio (D1) / (D2) of a particle diameter (D1) measured by a dynamic light scattering method to a particle diameter (D2) measured by a nitrogen gas adsorption method is 5 to 100; As a third aspect, the transparent laminate according to the first aspect or the second aspect, which has a total light transmittance of 93% or more; As a fourth aspect, the transparent laminate according to any one of the first to third aspects, which has a haze of 2.0 or less; As a fifth aspect, the transparent laminate according to any one of the first to fourth aspects, in which the carbon content is 1 mass % or less relative to the SiO2 of the silica particles; As a sixth aspect, there is provided a coating composition for a transparent laminate for forming the transparent laminate according to any one of the first to fifth aspects, the coating composition comprising silica particles and a solvent, and a coating thickness obtained by applying the coating composition having a SiO concentration of 1 to 15% by mass as a test condition and then baking the composition at 50 to 130° C.; As a seventh aspect, the coating composition for a transparent laminate according to the sixth aspect, in which the solvent is water or an alcohol having 1 to 5 carbon atoms which may contain an ether bond; and According to an eighth aspect, there is provided a method for producing a transparent laminate, comprising coating a substrate with the coating composition for a transparent laminate according to any one of the first to seventh aspects, and curing the coating composition at a temperature of 50 to 130°C. Effect of the Invention

[0008] Silica particles having a ratio (D1) / (D2) of particle size measured by dynamic light scattering method (D1) to particle size measured by nitrogen gas adsorption method (D2) of 2 or more, typically 5 to 100, are irregular silica particles, and a coating composition containing irregular silica particles is applied onto a substrate, followed by drying and curing to form a three-dimensional silica particle structure on the substrate. The formation of the three-dimensional silica particle structure is carried out by coating a coating composition containing an aqueous silica sol containing the silica particles onto a substrate, whereby an aqueous solvent or atmospheric gas (e.g., air) is entrained in the matrix (structure) between the three-dimensional silica particles, and the matrix is ​​dried and cured to form cavities in the matrix. These cavities are made of air, and the refractive index of the coating containing these matrices formed on the substrate is lower than that of a coating having a structure made of dense silica.

[0009] When forming a three-dimensional matrix (structure) between silica particles on a substrate, for example, by using a spin coating method, the coating composition spreads in a circular shape from the application part while entraining air, forming a coating film with the above structure. Similarly, a similar phenomenon is observed when using a bar coater.

[0010] In addition, if the substrate is flat, air bubbles are formed in the film by entraining air using the spin coating method or bar coating method, and the cavities become air layers after drying and hardening, resulting in a coating with a low refractive index. A similar phenomenon is also formed in an inclined substrate having an inclined surface when the coating composition flows down the inclined surface, and air is entrained in the coating film, forming cavities after drying and hardening, resulting in a coating with a low refractive index.

[0011] The formation of a three-dimensional matrix (structure) between silica particles on a substrate is related to the concentration of silica particles in the coating composition, which in turn is related to the film thickness of the resulting coating (laminate). That is, whether the silica particles in the coating composition are at a low or high concentration, it is difficult to form a three-dimensional matrix (structure) between silica particles on a substrate, and it is thought to be achieved at a specific silica concentration (e.g., 1 to 15 mass%), resulting in the formation of a low refractive index film with a specific film thickness (e.g., 100 to 2000 nm) on the substrate.

[0012] The laminate formed from the above coating composition has a specific amount of organic components (1% by mass or less relative to the SiO2 content in the laminate), which affects the formation of three-dimensional silica particles and silica particle matrix (structure) after drying and adhesion. That is, when the amount of volatile organic components increases, the matrix is ​​not sufficiently formed, or when the organic components require a high curing temperature and are not sufficiently cured at low temperatures, the adhesion decreases in the laminate in which the curing is not complete. In the present invention, when the transparent substrate is an organic resin substrate as the substrate, high-temperature baking is not possible, and it is required that the amount of organic components is a certain amount or less during low-temperature baking. Therefore, it is required to produce a coating film using a coating composition that is 1% by mass or less relative to the SiO2 content in the laminate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention comprises silica particles derived from a silica sol, the silica particles having a ratio (D1) / (D2) of a particle size (D1) measured by a dynamic light scattering method to a particle size (D2) measured by a nitrogen gas adsorption method of 2 or more, a refractive index of 1.20 to 1.33, a film thickness of 100 to 2000 nm, and adhesion such that 25 cross-cuts of 1 mm x 1 mm are formed in the cured coating obtained on the substrate, and the remaining mass ratio after application and peeling of an adhesive tape is (20 to 25) / (25).

[0014] The laminate preferably has a total light transmittance of 93% or more, typically 93 to 99%. The total light transmittance (%) indicates the amount of light transmitted through the laminate relative to the amount of light before transmission, assuming that the amount of light before transmission is 100%.

[0015] The above-mentioned film thickness is 100 to 2000 nm in a dry state. A thick film has a problem of reduced transmittance, and a thin film has problems in terms of film strength and durability.

[0016] When the present invention is used to cover a transparent substrate, high transmittance is required, and therefore a total light transmittance of 93% or more is preferable.

[0017] Transparency is also affected by the haze (cloudiness) of the laminate. This depends on the state of the silica particles used in the coating composition, and is achieved by using a silica sol in which colloidal silica particles are dispersed in an aqueous medium. In the present invention, the haze of the laminate can be made 2.0 or less by using an aqueous medium containing irregularly shaped colloidal silica particles. Typically, it is 0.08 to 2.0.

[0018] The laminate can achieve both refractive index and adhesion by making the carbon content 1% by mass or less relative to the SiO2 of the silica particles. The carbon content can be determined by elemental analysis.

[0019] The transparent laminate is laminated on a transparent substrate (base material), and the transparent substrate may be glass or a transparent resin. Examples of the transparent resin include polyacrylic resin, polycarbonate resin, polyethylene terephthalate resin, polyester resin, polyvinyl chloride resin, and polystyrene resin. In particular, polymethyl methacrylate resin is a preferred example.

[0020] The coating composition for forming the transparent laminate on the substrate contains silica particles and a solvent, and the coating composition has a SiO2 concentration of 1 to 15 mass% as a test condition. After coating the coating composition, the coating composition is baked at 50 to 130°C, or 50 to 100°C, or 50 to 90°C, or 50 to 80°C, or 60 to 80°C to obtain the above coating thickness.

[0021] The coating composition can be cured at the above temperature to produce a transparent laminate.

[0022] For example, examples of the coating method include spin coating and bar coating. Examples of the spin coating method include coating using a spin coater with a rotor rotation speed of 600 to 3500 rpm. Examples of the bar coating method include coating using a bar coater that will give a thickness of 1 to 6 μm in a wet state. Typically, such a wet film thickness is achieved at a bar coater moving speed of 20 to 150 mm / sec or 40 to 120 mm / sec, and for example, a wet coating film with a thickness of 4 μm can be achieved at a bar coater moving speed of 80 mm / sec. The composition can be applied to a substrate by, for example, flow coating, spray coating, screen printing, casting, curtain coating, roll coating, gravure coating, dipping, slit coating, ink jet coating, or the like.

[0023] The silica particles derived from silica sol include silica particles having a ratio (D1) / (D2) of the particle size measured by dynamic light scattering method (D1) to the particle size measured by nitrogen gas adsorption method (D2), of 2 or more, typically 2 to 100, or 5 to 100, or 5 to 50. These silica particles having a (D1) / (D2) ratio of 2 or more are elongated silica particles. Silica particles having a (D1) / (D2) ratio of less than 2 are spherical or nearly spherical silica particles. In the present invention, the above physical properties can be achieved by using elongated silica particles.

[0024] Examples of such silica particles include irregular silica particles in which the major axis is greater than the minor axis, and chain silica particles in which silica particles are linked in a chain shape. It is preferable that the particle size (D1) measured by dynamic light scattering is in the range of 40 to 500 nm, and the particle size (D2) measured by nitrogen gas adsorption is in the range of 5 to 40 nm. In the present invention, it is basically desirable to not contain any organic components, but it is possible to include a carbon content of 1 mass% or less relative to the SiO2 of the silica particles. Examples of organic components added to the laminate so that the carbon content is 1 mass% or less include silane compounds as coating components for silica particles, surfactants, and organic solvent components that are adsorbed onto the silica particles.

[0025] The composition is a silica sol in which silica is dispersed in a medium, and the medium can be water or a water-soluble organic solvent. The water-soluble organic solvent can be, for example, an alcohol, glycol, ether, ester, ketone, a nitrogen-containing solvent, or an aromatic solvent. Specifically, the organic solvent can be exemplified by methanol, ethanol, propanol, ethylene glycol, propylene glycol, glycerin, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, acetone, methyl ethyl ketone, dimethylformamide, N-methyl-2-pyrrolidone, toluene, xylene, and dimethylethane. In particular, the solvent can be preferably water or an alcohol having 1 to 5 carbon atoms that may contain an ether bond. Examples of the alcohol having 1 to 5 carbon atoms which may contain an ether bond include methanol, ethanol, i-propanol, n-propanol, and propylene glycol monomethyl ether. In the present invention, the metal oxide particles (A) can also be coated with at least one compound selected from the group consisting of hydrolysates of silane coupling agents represented by formulas (1) to (3) and acrylic polymers.

[0026] [ka]

[0027] In formula (1), R 3 each represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, or a cyano group, and is bonded to a silicon atom by a Si-C bond; R 4 each represents an alkoxy group, an acyloxy group, or a halogen group; a represents an integer of 1 to 3; In formula (2) and formula (3), R 5 and R 7are each an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms and bonded to a silicon atom by a Si-C bond, and R 6 and R 8 each represents an alkoxy group, an acyloxy group, or a halogen group; Y represents an alkylene group, an NH group, or an oxygen atom; b is an integer of 1 to 3; c is an integer of 0 or 1; and d is an integer of 1 to 3.

[0028] The alkyl group is an alkyl group having 1 to 18 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, a cyclobutyl group, a 1-methyl-cyclopropyl group, a 2-methyl-cyclopropyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, a 1-ethyl- n-Propyl, cyclopentyl, 1-methylcyclobutyl, 2-methylcyclobutyl, 3-methylcyclobutyl, 1,2-dimethylcyclopropyl, 2,3-dimethylcyclopropyl, 1-ethylcyclopropyl, 2-ethylcyclopropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl , 2,2-dimethyl-n-butyl, 2,3-dimethyl-n-butyl, 3,3-dimethyl-n-butyl, 1-ethyl-n-butyl, 2-ethyl-n-butyl, 1,1,2-trimethyl-n-propyl, 1,2,2-trimethyl-n-propyl, 1-ethyl-1-methyl-n-propyl, 1-ethyl-2-methyl-n-propyl, cyclohexyl, 1-methyl-cyclopentyl, 2-methyl-cyclopentyl, 3-methyl-cyclopentyl, 1-ethyl-cyclobutyl, 2-ethyl-cyclobutyl cyclopropyl, 3-ethyl-cyclobutyl, 1,2-dimethyl-cyclobutyl, 1,3-dimethyl-cyclobutyl, 2,2-dimethyl-cyclobutyl, 2,3-dimethyl-cyclobutyl, 2,4-dimethyl-cyclobutyl, 3,3-dimethyl-cyclobutyl, 1-n-propyl-cyclopropyl, 2-n-propyl-cyclopropyl, 1-i-propyl-cyclopropyl, 2-i-propyl-cyclopropyl, 1,2,2-trimethyl-cyclopropyl, 1,2,3-trimethyl-cyclopropyl, 2,2,Examples of the cyclopropyl group include, but are not limited to, 3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl-1-methyl-cyclopropyl group, 2-ethyl-2-methyl-cyclopropyl group, 2-ethyl-3-methyl-cyclopropyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, and octadecyl group. Furthermore, examples of the alkylene group include alkylene groups derived from the above-mentioned alkyl groups.

[0029] The aryl group is an aryl group having 6 to 30 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, an anthracene group, and a pyrene group. The alkenyl group is an alkenyl group having 2 to 10 carbon atoms, and examples of the alkenyl group include ethenyl group, 1-propenyl group, 2-propenyl group, 1-methyl-1-ethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group, 1-methyl-2-propenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-n-propylethenyl group, 1-methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3 Examples of the aryl group include, but are not limited to, 1-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, and 2-methyl-2-pentenyl group.

[0030] The alkoxy group includes an alkoxy group having 1 to 10 carbon atoms, such as a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, an s-butoxy group, a t-butoxy group, an n-pentyloxy group, a 1-methyl-n-butoxy group, a 2-methyl-n-butoxy group, a 3-methyl-n-butoxy group, a 1,1-dimethyl-n-propoxy group, a 1,2-dimethyl-n-propoxy group, a 2,2-dimethyl-n-propoxy group, a 1-ethyl-n-propoxy group, and an n-hexyloxy group, but is not limited to these.

[0031] Examples of the acyloxy group having 2 to 10 carbon atoms include, but are not limited to, a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, an i-propylcarbonyloxy group, an n-butylcarbonyloxy group, an i-butylcarbonyloxy group, an s-butylcarbonyloxy group, a t-butylcarbonyloxy group, an n-pentylcarbonyloxy group, a 1-methyl-n-butylcarbonyloxy group, a 2-methyl-n-butylcarbonyloxy group, a 3-methyl-n-butylcarbonyloxy group, a 1,1-dimethyl-n-propylcarbonyloxy group, a 1,2-dimethyl-n-propylcarbonyloxy group, a 2,2-dimethyl-n-propylcarbonyloxy group, a 1-ethyl-n-propylcarbonyloxy group, an n-hexylcarbonyloxy group, a 1-methyl-n-pentylcarbonyloxy group, and a 2-methyl-n-pentylcarbonyloxy group. The halogen group includes fluorine, chlorine, bromine, iodine, and the like.

[0032] The above-mentioned (meth)acryloyl group refers to both an acryloyl group and a methacryloyl group. Examples of organic groups having a (meth)acryloyl group include a 3-methacryloxypropyl group and a 3-acryloxypropyl group. An example of the organic group having a mercapto group is a 3-mercaptopropyl group. Examples of organic groups having an amino group include a 2-aminoethyl group, a 3-aminopropyl group, an N-2-(aminoethyl)-3-aminopropyl group, an N-(1,3-dimethyl-butylidene)aminopropyl group, an N-phenyl-3-aminopropyl group, and an N-(vinylbenzyl)-2-aminoethyl-3-aminopropyl group.

[0033] An example of the organic group having a ureido group is a 3-ureidopropyl group. An example of the organic group having a cyano group is a 3-cyanopropyl group. The above formulas (2) and (3) are preferably compounds capable of forming trimethylsilyl groups on the surface of silica particles. Examples of such compounds include the following.

[0034] [ka]

[0035] In the above formula, R 12 is an alkoxy group, examples of which include a methoxy group and an ethoxy group. Preferred functional groups are trimethylsilyl, monomethylsilyl, dimethylsilyl, methacryloxypropylsilyl, and phenyl groups, and corresponding silane compounds include hexamethyldisilazane, hexamethylsiloxane, hexamethyldisiloxane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, acryloxypropyltrimethoxysilane, acryloxypropyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

[0036] The (meth)acrylic polymer is a homopolymer or copolymer of (meth)acrylic acid or a (meth)acrylic acid ester, and R of the ester is 1 COOR 2 In the formula, R1 is an alkyl group having 1 to 10 carbon atoms, and R 2Examples of the alkyl group include a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aliphatic cyclic alkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 29 carbon atoms which may have an oxygen atom, a glycidyl group, a (meth)acrylic group having 3 to 10 carbon atoms, and a hydroxyalkyl group having 2 to 10 carbon atoms.

[0037] Also, surfactants can be used. Examples of the surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ethers such as polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether, polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, Examples of suitable surfactants include nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorosurfactants such as EFTOP EF301, EF303, and EF352 (trade names, manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, R-30, and R-40 (trade names, manufactured by DIC Corporation); Fluorad FC430 and FC431 (trade names, manufactured by Sumitomo 3M Limited); Asahiguard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (trade names, manufactured by Asahi Glass Co., Ltd.); and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0038] Silicone surfactants can also be used. Silicone surfactants are compounds having a repeating unit containing a siloxane bond in the main chain. The weight average molecular weight of the silicone surfactants can be in the range of 500 to 50,000. These may be modified silicone surfactants, and examples of such surfactants include those having an organic group introduced into the side chain and / or end of a polysiloxane. Examples of the organic group include an amino group, an epoxy group, an alicyclic epoxy group, a carbinol group, a mercapto group, a carboxyl group, an aliphatic ester group, an aliphatic amide group, and a polyether group. Silicone surfactants include Toray Silicone DC3PA, Toray Silicone SH7PA, Toray Silicone DC11PA, Toray Silicone SH21PA, Toray Silicone SH28PA, Toray Silicone SH29PA, Toray Silicone SH30PA, and Toray Silicone SH8400 (all manufactured by Toray Dow Corning Co., Ltd.), Silwet l-77, L-7280, L-7001, L-7002, L-7200, L-7210, L-7220, L-7230, L7500, L-7600, L-7602, L-7604, L-7605, L-7622, ​​L-765 7, L-8500, and L-8610 (all manufactured by Momentive Performance Materials Co., Ltd.), KP-341, KF-6001, and KF-6002. (all manufactured by Shin-Etsu Silicones Co., Ltd.), BYK307, BYK323, BYK330 (all manufactured by BYK-Chemie). EXAMPLES

[0039] [Refractive index measurement] The measurement was performed using an ellipsometer, a multi-angle spectroscopic ellipsometer VASE manufactured by J.A. Woollam Japan. [Measuring average particle size by dynamic light scattering method] Dynamic light scattering measurement device: Zetasizer manufactured by Malvern Instruments Ltd. was used for measurement.

[0040] [Measurement of average primary particle size (particle size by nitrogen gas adsorption method)] The specific surface area of ​​the silica sol powder dried at 300° C. was measured using a specific surface area measuring device Monosorb (registered trademark) MS-16 (manufactured by Yuasa Ionics Co., Ltd.). [HAZE measurement] The measurement was performed using a haze meter NDH8000 manufactured by Nippon Denshoku Industries Co., Ltd. [Measurement of organic content] The coating was stripped and the carbon content was determined using elemental analysis. [Film Thickness Measurement] The apparatus used was a multi-angle spectroscopic ellipsometer VASE manufactured by J.A. Woollam Japan.

[0041] [Measurement of total light transmittance] The measurement was performed using a haze meter NDH8000 manufactured by Nippon Denshoku Industries Co., Ltd. [Carbon Content] The silica sol dried at 110° C. was subjected to elemental analysis. [Measurement of Adhesion] The cured film was cross-cut with 25 holes at 1 mm intervals, and adhesive tape (product name: Cellophane Tape, manufactured by Nichiban Co., Ltd.) was firmly attached to the cross-cut area, after which the adhesive tape was quickly peeled off and the cured film was checked for peeling after the adhesive tape was peeled off. The evaluation criteria are as follows: (◯) indicates good adhesion, and (×) indicates poor adhesion. (○): No peeling at all, or peeling was confirmed in 5 or less of 25 stitches. (×): Peeling was observed in 6 or more of 25 stitches.

[0042] (Preparation of particle dispersion 1) Pure water was added to a long and thin silica sol using water as a dispersion medium (Nissan Chemical Co., Ltd., particle size (D1) measured by dynamic light scattering method: 65 nm, particle size (D2) measured by nitrogen gas adsorption method: 12 nm, (D1) / (D2) = 5.4, SiO2 concentration: 15 mass%, pH 10.3), and the mixture was stirred at room temperature until completely uniform, to obtain particle dispersion 1.

[0043] (Preparation of particle dispersion 2) Pure water was added to a long and thin silica sol using water as a dispersion medium (Nissan Chemical Co., Ltd., particle size (D1) measured by dynamic light scattering method: 65 nm, particle size (D2) measured by nitrogen gas adsorption method: 12 nm, (D1) / (D2)=5.4, SiO2 concentration: 15 mass%, pH: 2.6), and the mixture was stirred at room temperature until completely uniform, to obtain particle dispersion 2.

[0044] (Preparation of particle dispersion 3) PGME was added to a long and thin silica sol using propylene glycol monomethyl ether (PGME) as a dispersion medium (Nissan Chemical Co., Ltd., particle size (D1) measured by dynamic light scattering method was 65 nm, particle size (D2) measured by nitrogen gas adsorption method was 12 nm, (D1) / (D2) = 5.4, SiO2 concentration was 15 mass%, pH when PGME and pure water were mixed in a mass ratio of 1:1 was 3.6), and the mixture was stirred at room temperature until completely uniform, to obtain particle dispersion 3.

[0045] (Preparation of Particle Dispersion 4) Spherical silica sol with water as a dispersion medium (Nissan Chemical Co., Ltd., particle size (D2) measured by nitrogen gas adsorption method: 10 to 20 nm, pH 9.5 to 10.5, SiO2 concentration 30% by mass). (Substrate for coating) The resulting dispersion was applied to a quartz substrate and a silicon substrate.

[0046] (Method of applying the coating) The coating was prepared using a spin coater or a bar coater. The coating was prepared using a spin coater as the coating device (1), and the coating was prepared using a bar coater to a wet thickness of 4 μm (2). (Method of drying the coating) The coating obtained as described above was dried at a given temperature for 1 minute. The coating preparation conditions are shown in Table 1 below.

[0047] [Table 1] Table 1 ---------------------------------------------------------------------------------- Particle dispersion Solid content Coating method Processing method Firing temperature Example 1 Dispersion 1 3 mass% 1 1000 rpm 100°C Example 2 Dispersion 2 15% by weight 1 600 rpm 100° C. Example 3 Dispersion 3 15% by mass 1 3000 rpm 100° C. Example 4 Dispersion 3 3% by mass 1 1000 rpm 120° C. Example 5 Dispersion 1 3% by mass 2 80 mm / sec 60°C Example 6 Dispersion 1 1% by weight 2 80 mm / sec 60°C Comparative Example 1 Dispersion 1 20% by mass 1 600rpm 60℃ Comparative Example 2 Dispersion 1 0.01% by mass 2 80mm / sec 60℃ Comparative example 3 Dispersion liquid 4 9% by mass 1 2000rpm 60℃ ----------------------------------------------------------------------------------

[0048] In Table 1, "Dispersion 1" indicates that particle dispersion 1 was used, "Dispersion 2" indicates that particle dispersion 2 was used, "Dispersion 3" indicates that particle dispersion 3 was used, and "Dispersion 4" indicates that particle dispersion 4 was used. The "solid content" indicates that the above particle dispersions 1, 2, 3, and 4 were used at the concentrations shown in Table 1, respectively, diluted with pure water in the case of an aqueous solvent, and diluted with PGME in the case of a PGME solvent.

[0049] "Coating method" indicates that coating method 1 is a spin coating method using a spin coater, and coating method 2 is a bar coating method using a bar coater. "Processing method" indicates the rotation speed of the spin coater in the case of Coating method 1, and indicates that spin coating was performed at a specified rotation speed for 30 seconds, while in the case of Coating method 2, it indicates the thickness of the bar coater. "Baking temperature" indicates the baking temperature after coating, and indicates that baking was performed at the specified temperature for 1 minute.

[0050] [Table 2] Table 2 ---------------------------------------------------------------------------------- TT HAZE Film thickness Adhesion Refractive index Carbon content Example 1 94.3 0.12 106 〇 1.24 0.1% or less Example 2 94.3 0.47 1475 〇 1.28 0.1% or less Example 3 94.6 0.12 532 〇 1.28 0.1% or less Example 4 94.5 0.10 104 〇 1.22 0.1% or less Example 5 94.5 0.51 198 〇 1.21 0.1% or less Example 6 94.6 0.12 221 〇 1.23 0.1% or less Comparative Example 1 --- --- --- × --- --- Comparative example 2 96.0 0.06 75 × 1.23 0.1% or less Comparative example 3 VV 145 〇 1.45 V ----------------------------------------------------------------------------------

[0051] In Table 2, "TT" is the total light transmittance (%), which indicates the amount of light transmitted through the laminate relative to the light before transmission, assuming that the light before transmission is 100%. "HAZE" is a number that indicates the degree of turbidity (cloudiness) of a transparent material, and is measured with a haze meter. "Film thickness" was measured by measuring the film thickness (nm) of the coating film after baking. "Adhesion" was measured by the above-mentioned measuring method. The "refractive index" was measured by the above-mentioned measuring method. "Carbon content" indicates the amount (mass%) of carbon-containing components relative to the SiO2 of the silica particles. "---" indicates that no coating was formed and measurement was not possible. "V" indicated not measured. [Industrial Applicability]

[0052] It is possible to provide a coating composition that contains irregularly shaped silica particles and is capable of forming a coating film having high adhesion and a low refractive index on a substrate by forming a coating film at a specific thickness, and a transparent laminate having a low refractive index formed by applying and curing the coating composition.

Claims

1. A transparent laminate on a substrate, comprising silica particles derived from a silica sol, wherein the ratio (D1) / (D2) of the particle diameter (D1) measured by the dynamic light scattering method to the particle diameter (D2) measured by the nitrogen gas adsorption method of the silica particles is 2 or more, the refractive index is 1.20 to 1.33, the film thickness is 100 to 2000 nm, and the remaining mass ratio by making a 25-cell cross-cut of 1 mm×1 mm in the cured film on the obtained substrate and attaching and peeling an adhesive tape is (20 - 25) / (25), having adhesion.

2. The transparent laminate according to claim 1, wherein the ratio (D1) / (D2) of the particle diameter (D1) measured by the dynamic light scattering method to the particle diameter (D2) measured by the nitrogen gas adsorption method is 5 to 100.

3. The transparent laminate according to claim 1, wherein the total light transmittance is 93% or more.

4. The transparent laminate according to claim 1, wherein the HAZE is 2.0 or less.

5. The transparency laminate according to claim 1, wherein the carbon content is 1% by mass or less with respect to SiO of the silica particles. ２ of the silica particles.

6. A coating composition for forming a transparent laminate according to any one of claims 1 to 5, the coating composition comprising silica particles and a solvent, and the coating composition having SiO as a test condition ２ The coating composition for a transparent laminate, characterized in that it has a coating film thickness after firing at 50 to 130 °C after coating a coating composition having a concentration of 1 to 15% by mass.

7. The coating composition for a transparent laminate according to claim 6, wherein the solvent is water or an alcohol having 1 to 5 carbon atoms which may contain an ether bond.

8. A method for producing a transparent laminate, comprising coating a substrate with the coating composition for a transparent laminate according to claim 6 and curing at a temperature of 50 to 130°C.

9. A method for producing a transparent laminate, comprising coating a substrate with the coating composition for a transparent laminate according to claim 7 and curing at a temperature of 50 to 130°C.