Photosensitive resin composition

Abstract

To provide a photosensitive resin composition which has a low refractive index after curing and is excellent in patterning properties.SOLUTION: The photosensitive resin composition contains: (A) nano-silica particles which have been surface-treated with a silane coupling agent having a photoradically polymerizable functional group and have an average primary particle diameter of 100 nm or less; (B) a photoradically curable resin having a carboxyl group and a photoradically polymerizable functional group; and (C) a photoradical polymerization initiator. The photosensitive resin composition contains the component (A) in an amount of 55-95 wt.% in the solid content.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a photosensitive resin composition.

Background Art

[0002] In the display field and optical components such as lenses, when light from the outside is reflected on the surface, the visual effect is impaired. In order to reduce light reflection, a device has been made to laminate a low refractive index film on the surface. As a material for the low refractive index film, fluorine-based polymers have been studied, but fluorine-based polymers have a refractive index of about 1.37 to 1.46 at a wavelength of 589 nm, and the refractive index is slightly high. In addition, the regulation of the use of PFAS is being promoted due to its potential danger to the human body, and a low refractive index film containing no fluorine is required.

[0003] Patent Document 1 discloses a photosensitive resin composition containing hollow particles or porous particles and capable of forming a low refractive index pattern. Patent Document 2 discloses a photocurable composition for nanoimprinting, which contains colloidal silica and a photocurable monomer containing a compound having a (meth)acryloyloxy group.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a photosensitive resin composition having a low refractive index after curing and excellent patterning properties.

Means for Solving the Problems

[0006] The inventors of the present invention have found that when a photosensitive resin composition containing (A) nanosilica particles having an average primary particle diameter of 100 nm or less and surface-treated with a silane coupling agent having a photoradical polymerizable functional group, (B) a photoradical curable resin having a carboxyl group and a photoradical polymerizable functional group, and (C) a photoradical polymerization initiator is cured, a cured film having a low refractive index and excellent patterning properties can be obtained, and thus completed the present invention.

[0007] That is, the present invention includes the following aspects. <1> A photosensitive resin composition containing (A) nanosilica particles having an average primary particle diameter of 100 nm or less and surface-treated with a silane coupling agent having a photoradical polymerizable functional group, (B) a photoradical curable resin having a carboxyl group and a photoradical polymerizable functional group, and (C) a photoradical polymerization initiator, containing 55 to 95% by weight of the component (A) in the solid content, a photosensitive resin composition.

[0008] <2> The photosensitive resin composition according to item 1, wherein the component (A) is treated with 0.1 to 60 parts by weight of a silane coupling agent containing a photoradical polymerizable functional group with respect to 100 parts by weight of the nanosilica particles.

[0009] <3> The photosensitive resin composition according to item 1 or 2, wherein the photoradical polymerizable functional groups of the component (A) and the component (B) are (meth)acrylic groups.

[0010] <4> A cured film having a refractive index of 1.49 or less, which is obtained by curing the photosensitive resin composition according to item 1 or 2.

[0011] <5> A laminate having the cured film according to item 4.

Advantages of the Invention

[0012] When the photosensitive resin composition of the present invention is cured, a cured film having a low refractive index and excellent patterning properties can be formed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0014] <<Photosensitive Resin Composition>> The photosensitive resin composition of the present invention is (A) Nano-silica particles with an average primary particle diameter of 100 nm or less, surface-treated with a silane coupling agent having a photo-radical polymerizable functional group, (B) A photo-radical curable resin having a carboxyl group and a photo-radical polymerizable functional group, and (C) A photo-radical polymerization initiator, and is characterized in that the component (A) is contained in an amount of 55 to 95% by weight in the solid content.

[0015] <Nano-silica Particles> The nano-silica particles reduce the refractive index of the cured film composed of the photosensitive resin composition. As the nano-silica particles, spherical solid silica particles, hollow silica particles, beaded silica particles, mesoporous silica particles, etc. can be used. In the present invention, since surface treatment is performed with a silane coupling agent having a photo-radical polymerizable functional group, even if spherical solid silica particles are used, a cured film with a low refractive index can be obtained. Further, if hollow silica particles having cavities inside, beaded silica particles in which a plurality of silica single particles are connected in a beaded shape and have a large surface area, or mesoporous silica particles are used, a cured film with a low refractive index can be easily obtained.

[0016] The average primary particle diameter of the nano-silica particles is 100 nm or less, preferably 60 nm or less. When the average primary particle diameter is 100 nm or less, the transparency of the photosensitive resin composition tends to be high, and since the light for curing easily passes through, the curability tends to be excellent. The lower limit of the average primary particle diameter is not particularly limited, but is generally 5 nm or more.

[0017] <Surface treatment> As the nano-silica particles, those surface-treated with a silane coupling agent having a photo-radical polymerizable functional group are used. Examples of the hydrolyzable silyl group contained in the silane coupling agent include a dialkoxysilyl group and a trialkoxysilyl group. The number of carbon atoms of the alkyl group constituting these alkoxysilyl groups is preferably 1 to 4, more preferably 1 to 2.

[0018] The hydrolyzable silyl group and the photo-radical polymerizable functional group of the silane coupling agent are bonded via a direct bond, an alkylene such as ethylene, propylene, or butylene; an arylene such as phenylene or biphenylene; an oxyalkylene such as oxyethylene or oxypropylene. Among these, bonding via an alkylene is preferable.

[0019] Examples of the photo-radical polymerizable functional group contained in the silane coupling agent include a (meth)acryloyl group and a vinyl group.

[0020] Specific examples of the silane coupling agent having a (meth)acryloyl group include 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, and the like.

[0021] Specific examples of the silane coupling agent having a vinyl group include vinyltrimethoxysilane and vinyltriethoxysilane.

[0022] Among the above silane coupling agents, a silane coupling agent having a (meth)acryloyl group is preferable in terms of compatibility with the resin component and photocrosslinkability, and 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane are more preferable.

[0023] In the surface treatment of nano-silica particles with a silane coupling agent, hydrolysis of the hydrolyzable silyl group of the silane coupling agent generates silanol groups, and dehydration condensation is formed between these silanol groups and the silanol groups of the nano-silica particles. As a result, nano-silica particles having a photoradical polymerizable functional group via a siloxane bond on the surface are obtained.

[0024] The reaction of the surface treatment can be carried out in one step by coexisting the silane coupling agent and the nano-silica particles in a solvent, hydrolyzing the hydrolyzable silyl group of the silane coupling agent, and performing dehydration condensation between the silanol group of the silane coupling agent and the silanol group of the nano-silica particles. Specifically, for example, methods such as immersing nano-silica particles in a solution containing a silane coupling agent, spraying a solution containing a silane coupling agent onto the nano-silica particles, and adding a silane coupling agent to a dispersion of the nano-silica particles can be mentioned.

[0025] The temperature condition during the reaction of the surface treatment is preferably 20 to 100 °C, more preferably 40 to 60 °C. The time condition is preferably 5 to 20 hours, more preferably 10 to 15 hours. In the reaction of the surface treatment, the amount of the silane coupling agent used is preferably 0.1 to 60 parts by weight, more preferably 1 to 40 parts by weight, based on 100 parts by weight of the solid content of the nano-silica particles.

[0026] The surface treatment can be carried out under acidic or basic conditions. The acidic condition is preferably pH 2 to 5, more preferably pH 3 to 4. For pH adjustment, aqueous solutions of formic acid, hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, boric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, etc. can be used.

[0027] The basic condition is preferably pH 8 to 12, more preferably pH 8 to 10. For pH adjustment, aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, calcium hydroxide, calcium oxide, calcium carbonate, etc. can be used.

[0028] The reaction system for surface treatment can contain water. The amount of water is preferably 0.05 to 50 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the total amount of the silane coupling agent and the nanosilica particles. In addition to water, an organic solvent can be used as the solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, 1-propanol, isopropyl alcohol, and butanol; ethers such as tetrahydrofuran; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol monobutyl ether; alkylene glycol monoalkyl ether acetates such as methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, propylene glycol methyl ether acetate, and 3-methoxybutyl-1-acetate; aromatic hydrocarbons such as toluene and xylene; and ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, and cyclohexanone.

[0029] The amount of the nanosilica particles having an average primary particle diameter of 100 nm or less, surface-treated with a silane coupling agent having a photo-radical polymerizable functional group and contained in the photosensitive resin composition, is 55 to 95% by weight in the solid content, preferably 60 to 90% by weight. If it is less than 55% by weight, the refractive index tends to be high. If it exceeds 95% by weight, the developability tends to decrease. Here, the solid content refers to the non-volatile components excluding the solvent.

[0030] <Photo-radical curable resin> The photosensitive resin composition contains a photo-radical curable resin having a carboxyl group and a photo-radical polymerizable functional group as a binder. The photo-radical polymerizable functional group contributes to the curing of the binder and at the same time retains the surface-treated nanosilica particles in the cured film. The carboxyl group contributes to the alkali solubility of the cured film.

[0031] As the radical-polymerizable functional group of the photo-radical curable resin, those having a carbon-carbon double bond are preferred, and (meth)acrylic groups and vinyl groups are more preferred. Examples of the photo-radical curable resin containing a carboxyl group and a (meth)acrylic group include (meth)acrylic acid, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, β-carboxyethyl acrylate, ω-carboxypolycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, ethylene oxide-modified succinic acid acrylate, or polymers thereof. Examples of the photo-radical curable resin containing a carboxyl group and a (meth)acrylic group include carboxyl group-containing acrylic copolymers having an alicyclic skeleton, and products containing this resin include Cyclomer P(ACA)Z250 (manufactured by Daicel Corporation, solid content 45%, Mw 22,000), Cyclomer P(ACA)Z300 (manufactured by Daicel Corporation, solid content 39%, Mw 21,000), and Cyclomer P(ACA)Z320 (manufactured by Daicel Corporation, solid content 39%, Mw 23,000). Examples of the photo-radical curable resin containing a carboxyl group and a vinyl group include vinyl acrylate, vinyl acetate, or polymers thereof.

[0032] Moreover, it is preferable that both the radical-polymerizable functional group of the (A) surface-treated nano-silica particles and the radical-polymerizable functional group of the (B) photo-radical curable resin are (meth)acrylic groups. At this time, there are effects such as improvement in the compatibility between the nano-silica particles and other components and insolubilization due to the formation of three-dimensional crosslinking.

[0033] The photo-radical curable resin preferably has an acid value of 20 to 300 mgKOH / g, more preferably 30 to 200 mgKOH / g, and even more preferably 40 to 150 mgKOH / g. If it is less than 20 mgKOH / g, the developability tends to significantly decrease, and if it exceeds 300 mgKOH / g, the solubility tends to be too high.

[0034] The weight average molecular weight of the photo-radical curable resin is preferably from 1,000 to 100,000, more preferably from 5,000 to 50,000, and even more preferably from 8,000 to 50,000. If the weight average molecular weight is less than 1,000, the coatability tends to decrease, and if it exceeds 100,000, the developability tends to decrease.

[0035] The amount of the photo-radical curable resin contained in the photosensitive resin composition is preferably 3 to 70 parts by weight, more preferably 3 to 50 parts by weight, and even more preferably 5 to 40 parts by weight with respect to 100 parts by weight of the (A) surface-treated nano-silica particles. If the amount of the photo-radical curable resin is less than 3 parts by weight, the curing tends to be insufficient, and if it exceeds 70 parts by weight, the yellowing tends to become stronger.

[0036] <Photo-radical polymerization initiator> The photo-radical polymerization initiator generates free radicals upon irradiation with light and promotes the polymerization of the (A) surface-treated nano-silica particles and the (B) photo-radical curable resin.

[0037] Examples of the photo radical polymerization initiator include 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)], 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and the like. Product names containing these include Irgacure OXE01, Irgacure OXE02, Irgacure OXE03, Irgacure OXE04 (manufactured by BASF), and the like.

[0038] The amount of the photo radical polymerization initiator contained in the photosensitive resin composition is preferably 0.1 to 25 parts by weight, more preferably 0.5 to 15 parts by weight, and even more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the total amount of (A) surface-treated nano silica particles, (B) a carboxyl group, and a photo radical curable resin having a photo radical polymerizable functional group.

[0039] The photosensitive resin composition can be obtained by mixing (A) surface-treated nano silica particles, (B) a photo radical curable resin, (C) a photo radical polymerization initiator, and, if necessary, optional components described later. The mixing can be carried out by stirring and mixing using a stirrer, kneading using a roll mill, or the like. The mixing order of each component is not particularly limited. The temperature during mixing is preferably 1 to 60°C.

[0040] <Optional component> The photosensitive resin composition of the present invention may optionally contain other components in addition to (A) surface-treated nanosilica particles, (B) a photo-radical curable resin, and (C) a photo-radical polymerization initiator. Examples of other components include solvents, leveling agents, inorganic fine particles other than (A) surface-treated nanosilica particles, conductive polymers, carbon materials, and the like.

[0041] Examples of the solvent include water; alcohols such as methanol, ethanol, 2-propanol, and butanol; ethers such as tetrahydrofuran; glycol ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol monobutyl ether; alkylene glycol monoalkyl ether acetates such as methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, propylene glycol methyl ether acetate, and 3-methoxybutyl-1-acetate; aromatic hydrocarbons such as toluene and xylene; and ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, and cyclohexanone. These solvents may be used alone or in combination of two or more.

[0042] When the photosensitive resin composition of the present invention contains a solvent, its content is not particularly limited and can be appropriately adjusted so that the solid content ratio of the photosensitive resin composition becomes a desired value. The solid content ratio of the photosensitive resin composition of the present invention is not particularly limited, but is preferably 1 to 80% by weight, and more preferably 5 to 30% by weight. If the solid content ratio is less than 1% by weight, the film thickness may be insufficient, and if it exceeds 80% by weight, film formation may be difficult.

[0043] The leveling agent is not particularly limited. For example, siloxane compounds such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyether-ester-modified hydroxyl group-containing polydimethylsiloxane, polyether-modified acrylic group-containing polydimethylsiloxane, polyester-modified acrylic group-containing polydimethylsiloxane, perfluoropolydimethylsiloxane, perfluoropolyether-modified polydimethylsiloxane, perfluoropolyester-modified polydimethylsiloxane; fluorine-based compounds such as perfluoroalkyl carboxylic acid, perfluoroalkyl polyoxyethylene ethanol; polyether-based compounds such as polyoxyethylene alkyl phenyl ether, propylene oxide polymer, ethylene oxide polymer; carboxylic acids such as coconut oil fatty acid amine salt, gum rosin; ester-based compounds such as castor oil sulfate esters, phosphate esters, alkyl ether sulfates, sorbitan fatty acid esters, sulfonate esters, succinate esters; sulfonate compounds such as alkyl aryl sulfonate amine salts, dioctyl sodium sulfosuccinate; phosphate compounds such as sodium lauryl phosphate; amide compounds such as coconut oil fatty acid ethanolamide; acrylic compounds, etc. The compounding amount of the leveling agent is preferably 0.001 to 5% by weight, more preferably 0.01 to 1% by weight, based on the solid content of the photosensitive resin composition.

[0044] Examples of the inorganic fine particles other than the surface-treated nano silica particles (A) include metal oxide fine particles, nitrides, composite oxides composed of two or more metal elements, compounds in which a metal oxide is doped with a different element, and the like. Specific examples of the metal oxide fine particles include zirconium oxide (ZrO2), titanium oxide (TiO2), silicon oxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3, FeO, Fe3O4), copper oxide (CuO, Cu2O), zinc oxide (ZnO), yttrium oxide (Y2O3), niobium oxide (Nb2O5), molybdenum oxide (MoO3), indium oxide (In2O3, In2O), tin oxide (SnO2), tantalum oxide (Ta2O5), tungsten oxide (WO3, W2O5), lead oxide (PbO, PbO2), bismuth oxide (Bi2O3), cerium oxide (CeO2, Ce2O3), antimony oxide (Sb2O5, Sb2O5), germanium oxide (GeO2, GeO), and the like. The compounding amount of the inorganic fine particles is preferably 0.1 to 35 parts by weight with respect to 100 parts by weight of the surface-treated nano silica particles (A).

[0045] Examples of the conductive polymer include polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylene vinylene, polynaphthalene, their derivatives, and composites of these with dopants, etc. Poly(3,4-disubstituted thiophene) or a composite of poly(3,4-disubstituted thiophene) and a polyanion is preferred. The compounding amount of the conductive polymer is preferably 0.1 to 35 parts by weight with respect to 100 parts by weight of the surface-treated nano silica particles (A).

[0046] Examples of the carbon material include carbon nano materials, graphene, fullerene, and the like. The compounding amount of the carbon material is preferably 0.1 to 35 parts by weight with respect to 100 parts by weight of the surface-treated nano silica particles (A).

[0047] <<Cured film>> The cured film of the present invention is obtained by curing the photosensitive resin composition and has a refractive index of 1.49 or less. The refractive index is 1.49 or less, preferably 1.45 or less. The lower limit of the refractive index is not limited, but is generally 1.20 or more. The refractive index of the cured film is a value measured at a wavelength of 589 nm.

[0048] The cured film can be obtained by applying the photosensitive resin composition to a substrate and then photocuring it. The application to the substrate can be carried out by common methods such as bar coating, dip coating, spin coating, slit coating, inkjet, etc. The light irradiation amount for curing is not particularly limited, and for example, a light irradiation amount of 5 to 2000 mJ / cm 2 can be mentioned.

[0049] The thickness of the cured film is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm. If the thickness is less than 0.1 μm, the film may not remain after development, and if it exceeds 10 μm, the patterning property may deteriorate.

[0050] Examples of the material of the substrate on which the cured film is formed include glass, polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate, and modified polyester, polyolefin resins such as polyethylene (PE) resin, polypropylene (PP) resin, polystyrene resin, and cyclic olefin resin, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK) resin, polysulfone (PSF) resin, polyether sulfone (PES) resin, polycarbonate (PC) resin, polyamide resin, polyimide resin, acrylic resin, and triacetyl cellulose (TAC) resin. The thickness of the substrate is not particularly limited, but is preferably 50 to 200 μm.

[0051] <<Laminate>> The laminate of the present invention is characterized by having the cured film. The laminate may have, in addition to the cured film, an adhesive layer, a conductive layer, an antireflection layer, and the like. Since the laminate has a low refractive index and excellent patterning properties, it can be suitably used as a protective layer, an antistatic layer in optical applications, and insulation in electronic devices and semiconductors.

Examples

[0052] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the following examples. Hereinafter, "parts" or "%" means "parts by weight" or "% by weight" unless otherwise specified.

[0053] (1) Materials used (1-1) Nano silica particles Spherical silica particles (propylene glycol monomethyl ether dispersed silica sol, SiO2 30%, average primary particle diameter 12 nm, manufactured by Nissan Chemical Industries, Ltd., PGM-ST) Bead-shaped silica particles (propylene glycol monomethyl ether dispersed silica sol, SiO2 15%, average primary particle diameter 12 nm, manufactured by Nissan Chemical Industries, Ltd., PGM-ST-UP) (1-2) Silane coupling agent 3-Acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-5103) (1-3) Photo radical curable resin Carboxyl group-containing acrylic resin (manufactured by Daicel Corporation, Cyclomer P(ACA)Z250) (1-4) Photo radical polymerization initiator 1,2-Octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)] (manufactured by BASF, Irgacure OXE01)

[0054] (2) Surface treatment of nano silica particles (Production Examples 1 to 4) Each component shown in Table 1 was mixed and stirred at 50°C for 12 hours to obtain a nano silica particle dispersion liquid surface-treated with a silane coupling agent.

[0055]

Table 1

[0056] (3) Preparation of photosensitive resin compositions (Examples 1 to 6, Comparative Examples 1 to 4) Each component was mixed at the weight ratios shown in Table 2 below, propylene glycol monomethyl ether was used as the solvent, and the total solid content was adjusted to 20% by weight to obtain a photosensitive resin composition. In Table 2, (A) surface-treated nanosilica particles, nanosilica particles, and (B) photo-radical curable resin indicate the weight ratios of the solid content.

[0057] (4) Evaluation method (4-1) Refractive index The obtained photosensitive resin composition was applied onto a silicon wafer substrate using a spin coater, and exposed under the condition of 500 mJ / cm 2 to cure the photosensitive resin composition, thereby obtaining a laminate composed of the substrate and the cured film. The film thickness of the cured film was 1 μm. The refractive index at a film thickness of 1 μm and a wavelength of 589 nm was measured using an ellipsometer (Model M-2000U, manufactured by J.A. Woollam Co., Ltd.). The results are shown in Table 2.

[0058] (4-2) Patterning property The obtained photosensitive resin composition was applied onto a silicon wafer substrate using a spin coater, and exposed under the condition of 500 mJ / cm 2 through a photomask to cure the photosensitive resin composition in the exposed area. Then, it was immersed in a 2.35 wt% aqueous solution of tetramethylammonium hydroxide (TMAH), and a pattern was formed by a developing process to remove the photosensitive resin composition in the non-exposed area, thereby obtaining a laminate composed of the substrate and the patterned cured film. The film thickness of the cured film was 1 μm. The pattern was observed with a microscope (Model VHX-5000, manufactured by Keyence Corporation) and evaluated according to the following criteria. The results are shown in Table 2. ○: Pattern shape can be confirmed (100 μmL / S) ×: Pattern shape cannot be confirmed (100 μmL / S)

[0059]

Table 2

[0060] In Comparative Examples 1 and 3, as a result of using non-surface-treated nanosilica particles, the nanosilica particles peeled off from the cured film, and the surface appearance of the cured film was poor. In Comparative Example 2, a silane coupling agent was added to the composition of Comparative Example 1, but the surface appearance of the cured film was poor. In Comparative Example 4, since no nanosilica particles were contained, the refractive index of the cured film was high. In Examples 1 to 6, the refractive index was sufficiently reduced and the patterning property was good.

[0061] The cross-section of the cured film of Example 4 was observed with a scanning electron microscope (Regulus 8220 manufactured by Hitachi High-Technologies Corporation). As shown in Fig. 1 (magnification: 100,000 times) and Fig. 2 (magnification: 200,000 times), a large number of void structures were confirmed. It is considered that the refractive index of the cured film was lowered by these void structures.

[0062] The present invention may include, for example, the following aspects. <1> (A) Nanosilica particles having an average primary particle diameter of 100 nm or less, surface-treated with a silane coupling agent having a photo-radical polymerizable functional group, (B) A photo-radical curable resin having a carboxyl group and a photo-radical polymerizable functional group, and (C) A photo-radical polymerization initiator, containing 55 to 95% by weight of the component (A) in the solid content, A photosensitive resin composition.

[0063] <2> The photosensitive resin composition according to item 1, wherein the component (A) is treated with 0.1 to 60 parts by weight of a silane coupling agent containing a photo-radical polymerizable functional group with respect to 100 parts by weight of the nanosilica particles.

[0064] <3> The photosensitive resin composition according to item 1 or 2, wherein the photo-radical polymerizable functional groups of the component (A) and the component (B) are (meth)acrylic groups.

[0065] A cured film having a refractive index of 1.49 or less, which is obtained by curing the photosensitive resin composition according to any one of Items <4> 1 to 3.

[0066] <5>A laminate having the cured film according to Item 4.

Claims

1. (A)Nanoscale silica particles with an average primary particle diameter of 100 nm or less, surface-treated with a silane coupling agent having a photo-radical polymerizable functional group, (B)A photo-radical curable resin having a carboxyl group and a photo-radical polymerizable functional group, and (C)A photo-radical polymerization initiator, containing 55 to 95% by weight of the component (A) in the solid content, A photosensitive resin composition.

2. The photosensitive resin composition according to Claim 1, wherein the component (A) is treated with 0.1 to 60 parts by weight of a silane coupling agent containing a photo-radical polymerizable functional group with respect to 100 parts by weight of the nanoscale silica particles.

3. The photosensitive resin composition according to Claim 1 or 2, wherein the photo-radical polymerizable functional groups of the component (A) and the component (B) are (meth)acrylic groups.

4. A cured film having a refractive index of 1.49 or less, obtained by curing the photosensitive resin composition according to Claim 1 or 2.

5. A laminate having the cured film according to Claim 4.

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