Alkali-soluble resins, photosensitive resin compositions, their manufacturing methods, cured products, components for display devices, and display devices.

Abstract

The present invention provides an alkali-soluble resin with excellent photocurability and capable of providing a cured product with a high refractive index, and a photosensitive resin composition. The present invention is an alkali-soluble resin having an aromatic ring structure represented by formula (1) and a polymerizable unsaturated bond structure represented by formula (2), wherein the equivalent of the polymerizable unsaturated bond is 700~8000 g / equivalent (in formula (1), R1 represents an ester bond, an oxygen atom, a sulfur atom, or a nitrogen atom that may have a substituent; R2 represents an aromatic group that may have a substituent; R3 is a hydrogen atom or a group represented by formula (3); in formula (2), R4, R5 and R6 are the same or different, representing a hydrogen atom or a hydrocarbon group with 1 to 6 carbon atoms; R7 and R8 are the same or different, representing a direct bond or a divalent organic group; R9 is a hydrogen atom or a group represented by formula (3); at least one of R3 and R9 is a group represented by formula (3); in formula (3), R10 represents a divalent hydrocarbon group that may have a substituent).

Description

Alkali-soluble resin, photosensitive resin composition, method for producing the same, and uses thereof The present invention relates to an alkali-soluble resin, a photosensitive resin composition, a method for producing the same, and uses thereof. Specifically, the present invention relates to an alkali-soluble resin, a photosensitive resin composition, a method for producing the same, a cured product having excellent photocurability and capable of providing a cured product with a high refractive index, a component for a display device using the same, and a display device. Regarding alkali-soluble resins or photosensitive resin compositions, various studies have been conducted on their application to various optical components such as filters, inks, printing plates, printed wiring boards, semiconductor elements, photoresists, organic insulating films, and organic protective films used in, for example, liquid crystal display devices or solid imaging elements, and resins or resin compositions having excellent characteristics required for each application have been developed. In recent years, the miniaturization, thinning, and energy saving of optical components or electrical and electronic devices have been continuously advanced, and as a result, higher-grade performance has been required for various components used. In order to meet such requirements, research has been conducted on alkali-soluble resins that are materials for various components. To date, alkali-soluble resins that meet various requirements have been developed. For example, Patent Document 1 describes a modified epoxy resin having excellent heat resistance, moisture resistance, and flexibility, which is obtained by reacting an epoxy resin (i) having two or more epoxy groups in one molecule, a phenol (ii) having a substituent containing an aryl group, and an unsaturated monocarboxylic acid (iii). Further, for example, Patent Document 2 describes a solder resist film that can provide excellent heat resistance, adhesion, developability, electroless plating resistance, electrical properties, moisture absorption resistance, etc., and a photocurable and thermosetting composition that can be alkali-developed, which contains a photosensitive prepolymer, etc. The photosensitive prepolymer is obtained by reacting the alcoholic hydroxyl group of the reaction product of an epoxy compound having two or more epoxy groups in one molecule, a specified phenol compound and / or naphthol compound, and a monocarboxylic acid containing an unsaturated group with a polycarboxylic anhydride. [Prior Art Documents] [Patent Documents] Patent Document 1: Japanese Patent Application Laid-Open No. 11-49840 Patent Document 2: Japanese Patent Application Laid-Open No. 11-315107 [Problems to be Solved by the Invention] However, regarding these conventional alkali-soluble resins, the refractive index is relatively low. When used for optical applications that require a high refractive index, a relatively high refractive index of about 1.60 is required, but such requirements have not been fully met. Further, in recent years, when an alkali-soluble resin is used for optical applications such as filter applications, higher performance such as higher brightness and higher contrast of the display panel is strongly required, and in order to better exhibit the physical properties of the cured film, it is more desirable that the curing reaction can proceed sufficiently. The present invention has been made in view of the above circumstances, and an object thereof is to provide an alkali-soluble resin having excellent photocurability and capable of providing a cured product with a high refractive index, and a photosensitive resin composition. [Technical means for solving problems] The present inventors have conducted various studies on alkali-soluble resins, and as a result, have found that by having a specific aromatic ring-containing structure and a polymerizable unsaturated bond-containing structure, and the polymerizable unsaturated bond equivalent being in a specific range, excellent photocurability can be achieved and a cured product with a high refractive index can be provided, thereby completing the present invention. That is, the present invention provides an invention in the following aspect. [1] An alkali-soluble resin, characterized by having an aromatic ring-containing structure represented by the following formula (1) and a polymerizable unsaturated bond-containing structure represented by the following formula (2), and the polymerizable unsaturated bond equivalent being 700 to 8000 g / equivalent. (In formula (1), R 1 represents an ester bond, an oxygen atom, a sulfur atom, or a nitrogen atom which may have a substituent; R 2 represents an aromatic group which may have a substituent; R 3 is a hydrogen atom or a group represented by formula (3); in formula (2), R 4 , R 5 and R 6 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; R 7 and R 8 are the same or different and represent a direct bond or a divalent organic group; R 9 is a hydrogen atom or a group represented by formula (3); R 3 and R 9 at least one of which is a group represented by formula (3); in formula (3), R 10(A divalent hydrocarbon group which may have a substituent) [2] The alkali-soluble resin described in [1] above is characterized in that its acid value is 30 to 150 mgKOH / g. [3] The alkali-soluble resin described in [1] or [2] above is characterized in that its epoxy equivalent exceeds 10,000 g / equivalent. [4] The alkali-soluble resin described in any one of [1] to [3] above is characterized in that its main chain structure has a novolak structure. [5] A photosensitive resin composition characterized by containing the alkali-soluble resin described in any one of [1] to [4] above, a polymerizable compound, and a photoinitiator. [6] A cured product characterized by being obtained by curing the alkali-soluble resin described in any one of [1] to [4] above or the photosensitive resin composition described in [5] above. [7] A member for a display device characterized by containing the cured product described in [6] above. [8] A display device characterized by containing the member for a display device described in [7] above. [9] A method for producing an alkali-soluble resin, which is a method for producing an alkali-soluble resin, and is characterized in that: the production method includes a first step of reacting an epoxy resin (a) having two or more epoxy groups in one molecule with a compound (b) containing an aromatic group and an unsaturated monocarboxylic acid (c), and a second step of reacting the reaction product obtained in the first step with a polyanhydride (d); the usage amounts of the compound (b) containing an aromatic group and the unsaturated monocarboxylic acid (c) in the first step are adjusted so that the polymerizable unsaturated bond equivalent of the obtained alkali-soluble resin becomes 700 to 8,000 g / equivalent.

[10] A method for producing a photosensitive resin composition, which is a method for producing a photosensitive resin composition, and is characterized in that: the production method includes a step of producing an alkali-soluble resin having a polymerizable unsaturated bond equivalent of 700 to 8,000 g / equivalent by the method for producing an alkali-soluble resin described in [9] above, and a step of mixing the obtained alkali-soluble resin, a polymerizable compound, and a photoinitiator.

[11] An alkali-soluble resin characterized by having a structure containing an aromatic ring represented by the following formula (4) and a structure containing a polymerizable unsaturated bond represented by the following formula (2). (In formula (4), R 23 represents an aromatic group which may have a substituent; R 24 is a hydrogen atom or a group represented by formula (3); in formula (2), R 4 , R 5 and R 6 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; R 7 and R 8 are the same or different and represent a direct bond or a divalent organic group; R 9 is a hydrogen atom or a group represented by formula (3); R 24 and R 9 at least one of them is a group represented by formula (3); in formula (3), R 10 represents a divalent hydrocarbon group which may have a substituent)

[12] A resin, characterized in that: it has a structure containing an aromatic ring represented by the following formula (1'), and a structure containing a polymerizable unsaturated bond represented by the following formula (2'), and the polymerizable unsaturated double bond equivalent is 600 to 7000 g / equivalent. (In formula (1'), R 1 represents an oxygen atom or a sulfur atom; R 2 represents an aromatic group which may have a substituent; in formula (2'), R 4 , R 5 and R 6 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; R 7 and R 8 are the same or different and represent a direct bond or a divalent organic group)

[13] A photosensitive resin composition, characterized in that it contains the resin, an alkali-soluble resin, a polymerizable compound, and a photoinitiator described in the above

[12] .

[14] A cured product, characterized in that: it is obtained by curing the photosensitive resin composition described in the above

[13] . [Effects of the Invention] The alkali-soluble resin and the photosensitive resin composition of the present invention have excellent photocurability, can provide a cured product with a high refractive index, a component for a display device containing the above cured product, and a display device. Further, the manufacturing method of the alkali-soluble resin of the present invention can easily manufacture an alkali-soluble resin having excellent photocurability and a high refractive index. The following describes the preferred embodiments of the present invention in detail. However, the present invention is not limited to the following description and can be appropriately modified and applied without changing the gist of the present invention. Furthermore, a form obtained by combining two or more of the following preferred embodiments of the present invention also belongs to the preferred embodiments of the present invention. In this specification, "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid", and "(meth)acrylate" means "acrylate and / or methacrylate". Also, in this specification, the numerical range "Min to Max" means not less than the minimum value Min and not more than the maximum value Max. Furthermore, for the upper limit value and the lower limit value, when preferably numerical values are described step by step, a numerical range formed by appropriately combining the upper limit value and the lower limit value described respectively is also a preferred numerical range. 1. Alkali-soluble resin <First alkali-soluble resin> The first alkali-soluble resin of the present invention is characterized in that it has a structure containing an aromatic ring represented by the above formula (1) and a structure containing a polymerizable unsaturated bond represented by the above formula (2), and the polymerizable unsaturated bond equivalent is 700 to 8000 g / equivalent. The first alkali-soluble resin of the present invention is considered to have excellent photocurability and a high refractive index for the following reasons. That is, since the first alkali-soluble resin of the present invention has a specific structure containing an aromatic ring, a cured product with a high refractive index can be provided. Furthermore, it is speculated that the reason is that the side chain has a polymerizable unsaturated bond in a specified range, so the photocurability is excellent, and the crosslinking density becomes high during curing, thereby obtaining a cured product with an even higher refractive index. In the above formula (1), R 1 represents an ester bond, an oxygen atom, a sulfur atom, or a nitrogen atom that may have a substituent. Examples of the above substituent may include: an alkyl group, an aralkyl group, an aryl group, a thioester group, a thioether group, a disulfide group, an alkoxy group, an amino group or its salt, a halogen atom, a trifluoromethyl group, a benzamino group, a boric acid group, a hydroxyl group, a mercapto group, a thiocyanate group, an alkylthiocyanate group, an isothiocyanate group, a thiourea group, a sulfonic acid group, a carboxyl group, an aldehyde group, a heterocyclic group, or a group formed by combining them. Among them, in terms of obtaining a higher refractive index, R 1 is preferably an oxygen atom or a sulfur atom, more preferably a sulfur atom. Also, if a sulfur atom is present, it can act as an antioxidant, so weather resistance can be imparted to the resin. R 2Represents an aromatic group which may have substituents. The above-mentioned aromatic group only needs to have an aromatic ring structure, and can be a monocyclic ring or a polycyclic ring. Also, heteroatoms may be included. The rings of the aromatic group constituting the polycyclic ring may be condensed with each other, may be bonded by a single bond, or may be linked in a form of sharing one carbon atom. Also, as long as the rings of the aromatic group constituting the polycyclic ring contain at least an aromatic ring, it may be a group composed only of aromatic rings, or may be a group composed of aromatic rings and non-aromatic rings. Examples of the above-mentioned aromatic group include monovalent groups formed by removing one hydrogen atom from benzene-based aromatic compounds, non-benzene-based aromatic compounds, and heteroaromatic compounds. Examples of the above-mentioned benzene-based aromatic compounds include hydrocarbon compounds containing a benzene ring, such as monocyclic hydrocarbon compounds like benzene; condensed ring hydrocarbon compounds like naphthalene, anthracene, terphenyl, pyrene; polycyclic hydrocarbon compounds like biphenylene, fluorene, etc. Examples of the above-mentioned non-benzene-based aromatic compounds include hydrocarbon compounds containing unsaturated cyclic compounds other than the benzene ring, such as annulene, azulene. Examples of the above-mentioned heteroaromatic compounds include unsaturated cyclic compounds containing elements other than carbon atoms and hydrogen atoms, such as oxygen atoms, nitrogen atoms, sulfur atoms, etc. For example, it can be cited: furan, thiophene, pyrrole, pyrazole, imidazole, pyridine, , pyrimidine, pyr , 1,2,3-triazole, thiazole, thiadiazole, tetrazole and other monocyclic heteroaromatic compounds; carbazole, benz , oxazole, purine, azulene, benzofuran, isobenzofuran, benzothiophene, benzotriazole, isobenzothiophene, indole, isoindole, benzimidazole, benzothiazole and other polycyclic hetero compounds, etc. Among them, as the above-mentioned aromatic group, a monovalent group formed by removing one hydrogen atom from a benzene-based aromatic compound is preferred, phenyl, naphthyl, biphenyl are more preferred, phenyl and biphenyl are further preferred, and phenyl is the most preferred. The carbon number of the above-mentioned aromatic group is preferably 1 to 30, more preferably 2 to 20, and further preferably 6 to 12. Examples of the substituents that the above-mentioned aromatic group may have include: alkyl group, aralkyl group, aryl group, thioester group, thioether group, disulfide group, alkoxy group, amino group or its salt, halogen atom, trifluoromethyl group, benzylideneamino group, boronic acid group, hydroxyl group, mercapto group, thiocyanate group, alkylthiocyanate group, isothiocyanate group, thiourea group, sulfonic acid group, carboxyl group, aldehyde group, heterocyclic group, or a group formed by combining them. Among them, an alkyl group is preferred. The carbon number of the above-mentioned substituents is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. The above-mentioned aromatic group may have one or two or more of the above-mentioned substituents. As specific examples of the aromatic group which may have the above substituents, in addition to the above specific aromatic groups, for example, aromatic hydrocarbon groups such as tolyl, xylyl, benzyl, phenethyl, diphenylmethyl, triphenylmethyl, styryl, cinnamyl, etc. may be cited. Further, as specific examples of the aromatic group which may have the above substituents, monovalent groups formed by removing one hydrogen atom from the following aromatic compounds may be cited: thiocyanate compounds such as benzyl thiocyanate; isothiocyanate compounds such as phenyl isothiocyanate, benzyl isothiocyanate, 3,4-difluorophenyl isothiocyanate; trityl mercaptan, 4-aminobenzenethiol, 4-fluorobenzenethiol, 2,4-difluorobenzenethiol, 2-amino-4-(trifluoromethyl)benzenethiol hydrochloride, 3,5-dichlorobenzenethiol, bis(3,5-dichlorophenyl) disulfide, 4-methoxybenzenethiol, 3-mercapto-4-methyl-1,2,4-triazole, 4-bromobenzenethiol, 2-mercaptobenzene Thiol compounds such as oxazole, 2,6-dimethylbenzenethiol, 4,4',4''-(1,3,5,2,4,6-trioxatriborinane-2,4,6-tolyl)tribenzenethiol, 1,3,5-tris[3-(2-mercaptoethylthio)propyl] isocyanate, 6-amino-8-mercaptopurine, 4-mercaptobenzamide, 4-mercaptophenylboronic acid, 2-naphthalenethiol, diphenyldisulfide; Thiol carboxylic acid compounds such as S-phenyl thioacetate; Sulfonyl halogen compounds such as 2-mesitylene sulfonyl chloride; Sulfonic acid compounds such as benzenesulfonic acid; Thiourea compounds such as diphenylthiourea; Thiadiazole compounds such as 2,5-dimercapto-1,3,4-thiadiazole, 2-thioacetic acid-5-mercapto-1,3,4-thiadiazole, 2,5-dithioacetic acid-1,3,4-thiadiazole; Azide compounds such as 4-dodecylbenzenesulfonyl azide, 4-acetamidobenzenesulfonyl azide, diphenylphosphoric azide; Tetrazole compounds such as 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 1-methyl-5-ethyl-1H-tetrazole, 1-methyl-5-mercapto-1H-tetrazole, 1-phenyl-5-mercapto-1H-tetrazole, 1-(2-dimethylaminoethyl)-5-mercapto-1H-tetrazole, 2-methoxy-5-(5-trifluoromethyl-1H-tetrazol-1-yl)-benzaldehyde, 5,5'-di-1H-tetrazole diammonium salt, 4,5-bis(5-tetrazolyl)-[1,2,3]triazole, 5,5'-azobis-1H-tetrazole, 1-methyl-5-benzoyl-1H-tetrazole, (1-methyl-1H-tetrazol-5-yl)phenylmethanone oxime (E+Z), 5-ethylthio-1H-tetrazole, 1-benzyl-5-phenyl-1H-tetrazole; Tetrahydrothiazole compounds such as 2,4-thiazolidinedione, 2-thio-4-thiazolidinone, 2-imino-4-thiazolidinone; 4-Thiazolecarboxylic acid; Ketone compounds such as 2-hydroxyacetophenone, 4-hydroxyacetophenone, 2-hydroxypropiophenone, 4-hydroxypropiophenone; Dicarboxyaldehyde compounds such as 2,6-naphthalenedicarboxyaldehyde, 2,7-naphthalenedicarboxyaldehyde; Triphenylmethyl chloride compounds such as triphenylmethyl chloride, 4,4'-dimethoxytriphenylmethyl chloride. Among them, as R 2 Preferably, it is an aromatic hydrocarbon group which may have a substituent, more preferably a phenyl group, a naphthyl group, a biphenyl group which may have a substituent, and still more preferably a phenyl group, a biphenyl group which may have a substituent. R 3 is a hydrogen atom or a group represented by the above formula (3). In the above formula (3), R 10 represents a divalent hydrocarbon group which may have a substituent. Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Examples of the divalent aliphatic hydrocarbon group include methylene, ethylene, propylene, isopropylene, butylene, isobutylene, t-butylene, pentylene, neopentylene, hexamethylene, heptylene, octylene, 2-ethylhexylene, nonylene, decylene, undecylene, dodecylene, etc., or alkenylene such as vinylidene, propenylene, isopropenylene, butenylene, butadienylene, pentenylene, hexenylene, heptenylene, etc. Examples of the divalent alicyclic hydrocarbon group include cycloalkylene such as cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, norbornylidene, adamantylene, etc., or subcycloalkyl such as cyclopentylene, cyclohexylene, etc. Examples of the divalent aromatic hydrocarbon group include arylene such as phenylidene, methylphenylidene, naphthylidene, etc., or styryl, biphenylene, etc. Among them, the divalent hydrocarbon group is preferably a divalent aliphatic hydrocarbon group or a divalent alicyclic hydrocarbon group, more preferably a divalent aliphatic hydrocarbon group, and still more preferably an alkylene group. The carbon number of the divalent hydrocarbon group is preferably 2 to 20, more preferably 2 to 8, and still more preferably 2. Examples of the substituent that the divalent hydrocarbon group may have include a carboxyl group, a hydroxyl group, an alkoxy group, a halogen atom, a hydrocarbon group having 1 to 7 carbon atoms, etc. In the above formula (2), R 4 、R 5 and R 6 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. The hydrocarbon group having 1 to 6 carbon atoms is preferably an aliphatic hydrocarbon group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms. Among them, R 4 and R 5 is preferably a hydrogen atom, R 6 is preferably a hydrogen atom or a methyl group. In the above formula (2), R 7 and R 8 are the same or different and represent a direct bond or a divalent organic group. As R 7 and R 8 The divalent organic group represented may be exemplified by a divalent hydrocarbon group, or a group formed by combining a divalent hydrocarbon group with a bond such as -O-, -CO-, -COO-, -NH-, -SO- or -SO 2 - etc. As the above divalent hydrocarbon group, the same groups as those described above may be exemplified. The above divalent hydrocarbon group may also contain two or more kinds. Among them, as the above divalent organic group, a divalent hydrocarbon group, or a group formed by combining a divalent hydrocarbon group with at least one bond selected from the group consisting of -O-, -CO- and -COO- is preferred. As the above group formed by combining a divalent hydrocarbon group with at least one bond selected from the group consisting of -O-, -CO- and -COO-, for example, -R a -COO-R b -, -R a -O-(CO)-R b - (wherein, R a and R b are the same or different and represent a divalent hydrocarbon group having 1 to 20 carbon atoms) etc. R 7 and R 8 are preferably a direct bond, a divalent hydrocarbon group, or a group formed by combining a divalent hydrocarbon group with at least one bond selected from the group consisting of -O- and -COO-, more preferably a direct bond or a divalent aliphatic hydrocarbon group, and still more preferably a direct bond. In the above formula (2), R 9 is a hydrogen atom or the group represented by the above formula (3). Also, the above R 3 and R 9At least one of them is a group represented by the above formula (3). The group represented by the above formula (3) has a carboxyl group which is an acid group. The resin has alkali solubility by having such a group. By adjusting the amount of such an acid group, the alkali-soluble resin becomes a resin excellent in developability. Preferably, the first alkali-soluble resin has a novolak structure in its main chain structure. The novolak structure refers to a structure in which a benzene ring or a naphthalene ring and a divalent hydrocarbon group which may have a substituent are bonded in the main chain to form a repeating unit. As the alkali-soluble resin having the aromatic ring-containing structure represented by the above formula (1) and the polymerizable unsaturated bond-containing structure represented by the above formula (2), specifically, an alkali-soluble resin having a structural unit (A) represented by the following formula (a) and a structural unit (B) represented by the following formula (b) can be preferably exemplified. (In the formula, A represents a benzene ring or a naphthalene ring; R 1 ~R 9 are the same as those described above respectively; R 11 and R 14 are the same or different and represent a divalent hydrocarbon group having 1 to 20 carbon atoms; R 12 and R 15 are the same or different and represent a substituent bonded to A; a represents the number of R 12 and is an integer of 0 to 5; b represents the number of R 15 and is an integer of 0 to 5; when there are two or more R 12 and R 15 respectively, they may be the same or different from each other; R 13 and R 16 are the same or different and represent a direct bond or a divalent organic group) In this specification, a "structural unit" means a repeating unit constituting an alkali-soluble resin. In the above formulas (a) and (b), A represents a benzene ring or a naphthalene ring. From the viewpoint of the balance between high refractive index and developability, A is preferably a benzene ring. In the above formulas (a) and (b), R 11 and R 14Represents a divalent hydrocarbon group having 1 to 20 carbon atoms. Examples of the above divalent hydrocarbon group include the same groups as the above divalent hydrocarbon group. Among them, in terms of easy availability, as R 11 and R 14 The above divalent hydrocarbon group represented is preferably a divalent aliphatic hydrocarbon group, more preferably an alkylene group. The number of carbon atoms of the above divalent hydrocarbon group is preferably 1 to 14, more preferably 1 to 10, and even more preferably 1. Regarding the above divalent hydrocarbon group, at least one of the atoms constituting the hydrocarbon group may also be substituted with an oxygen atom, a nitrogen atom, a sulfur atom, or a halogen atom. Further, the above divalent hydrocarbon group may also have a substituent such as an alkoxy group. R 12 and R 15 Are the same or different and represent substituents bonded to A. Examples of the substituents bonded to A include a hydroxyl group or an organic group having 1 to 20 carbon atoms. Examples of the above organic group having 1 to 20 carbon atoms include those having 1 to 20 carbon atoms among those obtained by making the above divalent organic group monovalent. Among them, in terms of good curability, R 12 and R 15 The substituents represented are preferably -OH, -O-CH 2 -(C 2 H 3 O), -CR c R d -(C 6 H 4 )-O-CH 2 -(C 2 H 3 O), -CR c R d -(C 6 H 4 )-OH (wherein, R c and R d are the same or different and each represents a hydrogen atom or a methyl group), or an aliphatic hydrocarbon group having 1 to 20 carbon atoms, preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and particularly preferably a methyl group. In the above formula (a), a represents the number of substituents R 12 and is an integer of 0 to 5. From the viewpoint of good developability, a is preferably 0 to 3, more preferably 1 to 3, and still more preferably 1. When a is 2 or more, that is, when there are two or more Rs 12 in the case of 12 Rs may be the same as or different from each other. In the above formula (b), b represents the number of substituents R 15 and is an integer of 0 to 5. From the viewpoint of good developability, b is preferably 0 to 3, more preferably 1 to 3, and still more preferably 1. When b is 2 or more, that is, when there are two or more Rs 15 in the case of 15 Rs may be the same as or different from each other. R 13 and R 16 are the same or different and each represents a direct bond or a divalent organic group. Examples of the above divalent organic group include the same groups as the above divalent organic group. Among them, R 13 and R 16 are preferably a direct bond. The above first alkali-soluble resin may have one or more of the above structural units (A). The content of the structural unit (A) in the above alkali-soluble resin is preferably 51 to 93 mol%, more preferably 55 to 92 mol%, still more preferably 60 to 91 mol%, still more preferably 60 to 90 mol%, particularly preferably 60 to 80 mol%, and most preferably 60 to 75 mol% based on 100 mol% of all the structural units. The above first alkali-soluble resin may have one or more of the above structural units (B). The content of the structural unit (B) in the above alkali-soluble resin is preferably 7 to 49 mol%, more preferably 8 to 45 mol%, still more preferably 9 to 40 mol%, and still more preferably 10 to 40 mol% based on 100 mol% of all the structural units. The above-mentioned first alkali-soluble resin may further have other constituent units (C) in addition to the above-mentioned constituent units (A) and (B), and the above-mentioned alkali-soluble resin may have one or more than two kinds of constituent units (C). Examples of the above-mentioned constituent unit (C) include a constituent unit represented by the following formula (c). (In the formula, A represents a benzene ring or a naphthalene ring; R 3 is the same as the above; R 17 represents a divalent hydrocarbon group having 1 to 20 carbon atoms; R 18 represents a substituent bonded to A; c represents the number of R 18 and is an integer of 0 to 5; when there are two or more R 18 , they may be the same or different from each other; R 19 represents a direct bond or a divalent organic group; R 20 represents an organic group) Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the above R 17 include the same groups as the divalent hydrocarbon group having 1 to 20 carbon atoms represented by the above R 11 , preferably a divalent aliphatic hydrocarbon group, more preferably an alkylene group. Examples of the substituent represented by the above R 18 include the same groups as the substituent represented by the above R 12 , preferably -OH, -O-CH 2 -(C 2 H 3 O), -CR c R d -(C 6 H 4 )-O-CH 2 -(C 2 H 3 O), -CR c R d -(C 6 H 4 )-OH (wherein R c and R d are the same or different and represent a hydrogen atom or a methyl group), or an aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, still more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and particularly preferably a methyl group. In the above formula (c), c represents the number of substituents R 18 and is an integer of 0 to 5. From the viewpoint of good developability, c is preferably 0 to 3, more preferably 1 to 3, and still more preferably 1. When c is 2 or more, that is, when there are two or more R 18 cases, R 18 may be the same as or different from each other. R 19 represents a direct bond or a divalent organic group. Examples of the divalent organic group represented by R 19 include the same groups as those represented by the above R 13 Among them, R 19 is preferably a direct bond. R 20 represents an organic group. Examples of the organic group represented by R 20 include those obtained by converting the above divalent organic group into a monovalent group, etc. Among them, a group having an acid group is preferred. Also preferred is a group having no double bond. By appropriately selecting the organic group of R 20 , the developability or the reactivity of the double bond can be controlled. Examples of the above acid group include functional groups that undergo a neutralization reaction with alkaline water, such as a carboxyl group, a phenolic hydroxyl group, a carboxylic anhydride group, a phosphoric acid group, and a sulfonic acid group. Among them, from the viewpoint of good developability, a carboxyl group or a carboxylic anhydride group is preferred, and a carboxyl group is more preferred. Examples of the group having the above acid group include -R e -R f (wherein R e represents a divalent organic group, R f groups represented by (wherein represents an acid group), etc. Examples of the above divalent organic group include the same groups as the above organic groups. Among them, a group composed of a combination of a divalent hydrocarbon group and at least one selected from the group consisting of -O- and -COO- is preferred. Also, R 20 The organic group represented is preferably a functional group having a free radical scavenging ability or an ultraviolet absorbing ability. By having such a functional group, the weather resistance of the resin can be improved. Examples of the above functional group include: hindered phenol group, hindered amine group, benzotriazole group, tri yl group, cyanoacrylate group, melamine group, benzoate group, etc. As R 20 The carbon number of the represented organic group is preferably 1 to 20, more preferably 1 to 16, still more preferably 2 to 12. By positioning the acid group represented by the above R f at a position far from the main chain of the alkali-soluble resin, the developability can be improved. The above first alkali-soluble resin may have one or more of the above structural units (C). The content rate of the above structural unit (C) is preferably 0 to 20 mol%, more preferably 0.1 to 20 mol%, still more preferably 0.5 to 15 mol%, and still more preferably 1 to 10 mol% relative to all structural units of 100 mol%. Also, the above first alkali-soluble resin may also have a structural unit (D) represented by the following formula (d). By using the introduction of the above structural unit (D) for chain extension, the resin can be designed to have an arbitrary molecular weight. In the above formula (d), L represents a direct bond or a linking group. R 21 and R 22 are the same or different and represent substituents. d represents the number of R 21 and is an integer of 0 to 4. e represents the number of R 22 and is an integer of 0 to 4. In the case where there are plural R 21 and R 22 they may be the same as or different from each other respectively. Examples of the linking group include: an alkylene group, an arylene group, a heteroarylene group, or a divalent bond such as -O-, -CO-, -S-, -SO-, -SO - 2 , -NH-, or a combination thereof. The alkylene group is preferably an alkylene group having 1 to 20 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms. It may be linear, branched, or cyclic. The alkylene group and the arylene group may also have substituents. The substituents are not particularly limited, and examples include halogen atoms such as fluorine, chlorine, and iodine atoms, or alkyl groups. The structural unit (D) represented by the above formula (d) is preferably a structural unit derived from any one compound selected from bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, and bisphenol Z, more preferably a structural unit derived from bisphenol S, bisphenol A, or bisphenol F, and still more preferably a structural unit derived from bisphenol S. Examples of the structural unit (D) preferably include structural units represented by the following formula (d-1), (d-2), or (d-3). When the first alkali-soluble resin has the structural unit (D), the content of the structural unit (D) is preferably 0.1 to 10 mol%, more preferably 0.2 to 5 mol%, and still more preferably 0.5 to 2 mol% with respect to 100 mol% of all structural units. The polymerizable unsaturated bond equivalent of the first alkali-soluble resin is 700 to 8000 g / equivalent. By having the polymerizable unsaturated bond equivalent within the above range, the photocurability of the alkali-soluble resin can be improved. In terms of reducing the brittleness of the cured product, the polymerizable unsaturated bond equivalent of the alkali-soluble resin is preferably 750 to 6000 g / equivalent, more preferably 800 to 5000 g / equivalent, still more preferably 900 to 4000 g / equivalent, and still more preferably 900 to 2000 g / equivalent. ​​​​​​​​​​The above-mentioned polymerizable unsaturated bond equivalent is the mass of the solid content of the alkali-soluble resin solution per 1 mol of polymerizable unsaturated bonds of the above-mentioned alkali-soluble resin. In this specification, the above-mentioned polymerizable unsaturated bond means a polymerizable double bond. The mass of the solid content of the alkali-soluble resin solution refers to the mass of the monomer components constituting the alkali-soluble resin. The above-mentioned polymerizable unsaturated bond equivalent can be obtained by dividing the mass (g) of the alkali-soluble resin solid content of the alkali-soluble resin solution by the amount of polymerizable unsaturated bonds (mol) of the alkali-soluble resin. Also, it can be calculated by measuring the number of ethylenic double bonds contained in 1 g of the alkali-soluble resin according to the test method of iodine value described in JIS K 0070:1992. The acid value of the above-mentioned first alkali-soluble resin is preferably 30 to 150 mgKOH / g. In terms of further improving the developability, the above acid value is more preferably 40 to 120 mgKOH / g, and even more preferably 45 to 90 mgKOH / g. The above acid value is the acid value per 1 g of resin solid content obtained by measurement using the neutralization titration method with a potassium hydroxide (KOH) solution, and can be obtained by the method described in the following examples. The epoxy equivalent of the above-mentioned first alkali-soluble resin is preferably more than 10000 g / equivalent. If the epoxy equivalent is within the above range, the alkali-soluble resin of the present invention hardly has epoxy groups. Therefore, the storage stability is good. The epoxy equivalent of the above-mentioned alkali-soluble resin is more preferably more than 13000 g / equivalent. The above epoxy equivalent can be obtained by the method according to JIS K7236:2001, and can also be obtained by dividing the mass (g) of the resin solid content by the number of moles (mol) of epoxy groups contained in the resin. The weight average molecular weight of the above-mentioned first alkali-soluble resin is preferably 1000 to 100000. In terms of good curability, the weight average molecular weight of the above-mentioned alkali-soluble resin is more preferably 2000 to 50000, even more preferably 3000 to 20000, even more preferably 3500 to 15000, and particularly preferably 4000 to 10000. The above weight average molecular weight can be obtained by gel permeation chromatography (GPC). Regarding the glass transition temperature (Tg) of the above-mentioned first alkali-soluble resin, in terms of improving the film strength, it is preferably 40°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. In terms of good developability, it is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. The glass transition temperature (Tg) of the above-mentioned first alkali-soluble resin is preferably 40 to 300°C, more preferably 60 to 250°C, and even more preferably 80 to 200°C. The above glass transition temperature can be obtained by the method according to JIS-K7121. <Second alkali-soluble resin> The second alkali-soluble resin of the present invention is characterized by having a structure containing an aromatic ring represented by the following formula (4) and a structure containing a polymerizable unsaturated bond represented by the following formula (2). (In formula (4), R 23 represents an aromatic group which may have a substituent; R 24 is a hydrogen atom or a group represented by formula (3); in formula (2), R 4 , R 5 and R 6 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; R 7 and R 8 are the same or different and represent a direct bond or a divalent organic group; R 9 is a hydrogen atom or a group represented by formula (3); R 24 and R 9 at least one of them is a group represented by formula (3); in formula (3), R 10 represents a divalent hydrocarbon group which may have a substituent) It is considered that the reason why the second alkali-soluble resin of the present invention has excellent photocurability and can provide a cured product with a high refractive index is that: by having the structure of formula (4) containing a sulfur atom and an aromatic group, the refractive index of the cured product can be made higher, and by having the structure of formula (2), the photocurability can be made good. In the above formula (4), R 23 represents an aromatic group which may have a substituent. Examples of the aromatic group which may have a substituent represented by R 23 are the same as the aromatic group which may have a substituent represented by R 2 in the above formula (1). In the above formula (4), R 24 is a hydrogen atom or a group represented by formula (3). The group represented by the above formula (3) is the same as the group represented by formula (3) described in the item of the above <First alkali-soluble resin>. The structure containing a polymerizable unsaturated bond represented by the above formula (2) is the same as the structure containing a polymerizable unsaturated bond represented by formula (2) described in the item of the above <First Base-Soluble Resin>. Similar to the above first base-soluble resin, the above second base-soluble resin preferably has a novolak structure in the main chain structure. As the base-soluble resin having the structure containing an aromatic ring represented by the above formula (4) and the structure containing a polymerizable unsaturated bond represented by the above formula (2), a base-soluble resin having a structural unit (E) represented by the following formula (e) and the structural unit (B) described in the item of the above <First Base-Soluble Resin> can be preferably exemplified. (In the formula, A represents a benzene ring or a naphthalene ring; R 23 and R 24 are the same as those above respectively; R 25 represents a divalent hydrocarbon group having 1 to 20 carbon atoms; R 26 represents a substituent bonded to A; f represents the number of R 26 and is an integer of 0 to 5; when there are two or more R 26 , they may be the same or different from each other; R 27 represents a direct bond or a divalent organic group) In the formula, A represents a benzene ring or a naphthalene ring, preferably a benzene ring. As the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R 25 , a group the same as the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R 11 in the formula (a) described in the item of the above <First Base-Soluble Resin> can be exemplified. As the substituent represented by R 26 , a group the same as the substituent represented by R 12 in the above formula (a) can be exemplified. f represents the number of R 26 and is an integer of 0 to 5. From the aspect of good developability, f is preferably 0 to 3, more preferably 1 to 3, and preferably 1. The above-mentioned second alkali-soluble resin may have one or more of the above-mentioned structural units (E). The content ratio of the above-mentioned structural unit (E) in the above-mentioned second alkali-soluble resin is preferably 1 to 99 mol%, more preferably 20 to 95 mol%, still more preferably 40 to 93 mol%, still more preferably 50 to 90 mol%, particularly preferably 60 to 85 mol%, and most preferably 60 to 80 mol% with respect to 100 mol% of all the structural units. The content ratio of the above-mentioned structural unit (B) in the above-mentioned second alkali-soluble resin is preferably 1 to 80 mol%, more preferably 2 to 70 mol%, still more preferably 3 to 50 mol%, still more preferably 5 to 40 mol%, particularly preferably 10 to 40 mol%, and most preferably 15 to 40 mol% with respect to 100 mol% of all the structural units. In addition, the above-mentioned second alkali-soluble resin may have other structural units in addition to the above-mentioned structural units (E) and (B). Examples of the above-mentioned other structural units include the structural unit (C) or the structural unit (D) described in the item of the above-mentioned <first alkali-soluble resin>. When the above-mentioned second alkali-soluble resin has the above-mentioned structural unit (C) and / or the structural unit (D), their content ratios are preferably the same as those in the above-mentioned first alkali-soluble resin. The polymerizable unsaturated bond equivalent of the above-mentioned second alkali-soluble resin is preferably 300 to 8000 g / equivalent, more preferably 500 to 6000 g / equivalent, still more preferably 700 to 5000 g / equivalent, still more preferably 800 to 4000 g / equivalent, particularly preferably 800 to 2000 g / equivalent. The acid value, epoxy equivalent, weight average molecular weight, and glass transition temperature of the above-mentioned second alkali-soluble resin are preferably the same as those of the above-mentioned first alkali-soluble resin, respectively. 2. Method for producing alkali-soluble resin <Method for producing first alkali-soluble resin> The method for producing the first alkali-soluble resin of the present invention is not particularly limited as long as the above-mentioned first alkali-soluble resin can be obtained. In terms of efficiently producing the first alkali-soluble resin of the present invention, a production method preferably including the following steps is preferred. (1) The first step of reacting an epoxy resin (a) having two or more epoxy groups in one molecule with an aromatic group-containing compound (b) and an unsaturated monocarboxylic acid (c) (2) The second step of reacting the reaction product obtained in the above-mentioned first step with a polyanhydride (d) Further, in the above-mentioned production method, the first alkali-soluble resin of the present invention can be produced by adjusting the usage amounts of the aromatic group-containing compound (b) and the unsaturated monocarboxylic acid (c) in the above-mentioned first step so that the polymerizable unsaturated bond equivalent of the obtained alkali-soluble resin becomes 700 to 8000 g / equivalent. The method for manufacturing such a first alkali-soluble resin, that is, the method for manufacturing an alkali-soluble resin, is also one of the present inventions, and is characterized in that: the manufacturing method includes a first step of reacting an epoxy resin (a) having two or more epoxy groups in one molecule with an aromatic group-containing compound (b) and an unsaturated monocarboxylic acid (c), and a second step of reacting the reaction product obtained in the first step with a polyanhydride (d), and adjusting the usage amounts of the aromatic group-containing compound (b) and the unsaturated monocarboxylic acid (c) in the first step so that the polymerizable unsaturated bond equivalent of the obtained alkali-soluble resin becomes 700 to 8000 g / equivalent. Hereinafter, each step will be described. In the method for manufacturing the first alkali-soluble resin of the present invention, the epoxy resin (a) having two or more epoxy groups in one molecule as the starting material is not particularly limited, and any known epoxy resin having two or more epoxy groups in one molecule can be used, and examples thereof include: bisphenol type epoxy resin; biphenyl type epoxy resin; alicyclic epoxy resin; polyfunctional glycidylamine resins such as tetraglycidylaminodiphenylmethane; polyfunctional glycidyl ether resins such as tetraphenyldiglycidyl ether ethane; phenolic novolak type epoxy resin or cresol novolak type epoxy resin; reaction products of polyphenolic compounds obtained by condensation reactions of phenolic compounds such as phenol, o-cresol, m-cresol, and naphthol with aromatic aldehydes having phenolic hydroxyl groups and epichlorohydrin; reaction products of polyphenolic compounds obtained by addition reactions of phenolic compounds with diene compounds such as divinylbenzene or dicyclopentadiene and epichlorohydrin; those obtained by epoxidizing the ring-opening polymer of 4-vinylcyclohexene-1-oxide with a peracid; epoxy resins having heterocycles such as triglycidyl isocyanurate. Further, those obtained by bonding two or more molecules of these epoxy resins through reactions with chain extenders such as polyacids, polyphenolic compounds, polyfunctional amino compounds, or polyvalent thiols can also be used. Or, it can also be a homopolymer or copolymer of a monomer having an epoxy group such as (meth)acrylic glycidyl ester or 3,4-epoxycyclohexylmethyl (meth)acrylate. Among them, in order to increase the photocurability by increasing the number of ethylenic unsaturated bonds (polymerizable unsaturated double bonds) in one molecule of the alkali-soluble resin, it is preferable to use a novolak type epoxy resin as the raw material. As the epoxy resin (a) having two or more epoxy groups in one molecule as the above-mentioned starting material, in terms of making the developability and photocurability of the obtained alkali-soluble resin more excellent, it is preferably an epoxy resin having an epoxy equivalent of 500 g / equivalent or less. More preferably, it is an epoxy resin having an epoxy equivalent of 400 g / equivalent or less, and still more preferably, it is an epoxy resin having an epoxy equivalent of 300 g / equivalent or less. As the above-mentioned compound (b) containing an aromatic group, there is no particular limitation as long as it is a compound having an aromatic group and a group capable of reacting with an epoxy group, and examples thereof include the above-mentioned aromatic compounds and the like. As the above-mentioned aromatic group, examples thereof include the above-mentioned group having an aromatic ring structure. As the group capable of reacting with an epoxy group, examples thereof include an acid group, an amino group, a hydroxyl group, and the like. As the above-mentioned acid group, examples thereof include a carboxyl group, a phenolic hydroxyl group, a mercapto group, and the like, and preferably, a phenolic hydroxyl group and a mercapto group are exemplified. The above-mentioned compound containing an aromatic group is preferably the above-mentioned acid compound containing an aromatic group and an acid group. As the above-mentioned compound containing an aromatic group, there is no particular limitation as long as it is a compound capable of imparting the above-mentioned structure containing an aromatic ring to the obtained resin, and preferably, examples thereof include phenolic derivatives such as phenylphenol, thiophenol derivatives such as toluenethiol and benzenethiol, and alcohol derivatives such as hydroxybenzyl alcohol. Among them, in terms of兼顾较高的折射率及高速显影性 with respect to the formed thioether bond, thiophenol derivatives are preferred, and benzenethiol is most preferred. These may be used alone or in combination of two or more. Furthermore, when hydroxybenzyl alcohol is used or used in combination, an acid group chain-extended by reacting a polyanhydride can be introduced into the alkali-soluble resin in the following step (2). Since such an acid group is located at a position far from the main chain, the developability or the reactivity during hardening becomes good. As the above-mentioned unsaturated monocarboxylic acid (c), there is no particular limitation as long as it has an unsaturated bond and a carboxyl group, and preferably, it has 3 to 20 carbon atoms. More preferably, it has 3 to 10 carbon atoms, and still more preferably, it has 3 to 4 carbon atoms. Examples of the above-mentioned unsaturated monocarboxylic acid (c) include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, β-acryloyloxypropionic acid, a reaction product of a (meth)acrylic acid hydroxyalkyl ester having one hydroxyl group and one (meth)acryloyl group and a dianhydride, a reaction product of a polyfunctional (meth)acrylate having one hydroxyl group and two or more (meth)acryloyl groups, and the like. Among them, those having a (meth)acryloyl group such as acrylic acid and methacrylic acid are preferred. In terms of enabling the obtained alkali-soluble resin to provide a cured product having particularly excellent solvent resistance, methacrylic acid is particularly preferred. These may be used alone or in combination of two or more. The addition of the above-mentioned compound (b) containing an aromatic group and the above-mentioned unsaturated monocarboxylic acid (c) can be added together, or added in portions or sequentially. In terms of suppressing side reactions, it is preferably added in portions or sequentially. In the method for producing the alkali-soluble resin of the present invention, in the first step of reacting an epoxy resin (a) having two or more epoxy groups in one molecule with an aromatic group-containing compound (b) and an unsaturated monocarboxylic acid (c), the epoxy resin (a) can be reacted with the unsaturated monocarboxylic acid (c), and then reacted with the aromatic group-containing compound (b). The unsaturated monocarboxylic acid (c) and the aromatic group-containing compound (b) can be reacted with the epoxy resin (a) together, or the epoxy resin (a) can be reacted with the aromatic group-containing compound (b), and then reacted with the unsaturated monocarboxylic acid (c). In the above first step, when the epoxy resin (a) is reacted with the aromatic group-containing compound (b), the addition amount of the aromatic group-containing compound (b) is preferably such that the acid group in the aromatic group-containing compound (b) becomes 0.51 to 0.93 moles relative to 1 chemical equivalent (mole equivalent) of the epoxy group of the epoxy resin (a), more preferably 0.55 to 0.92 moles, still more preferably 0.6 to 0.91 moles, still more preferably 0.6 to 0.9 moles, particularly preferably 0.6 to 0.8 moles, and most preferably 0.6 to 0.75 moles. Regarding the reaction between the epoxy resin (a) and the aromatic group-containing compound (b), the reaction tank is purged with an inert gas such as nitrogen to reduce the oxygen concentration and carry out the reaction, thereby accelerating the reaction rate. The oxygen concentration in the reaction tank is preferably 1% by volume or less, more preferably 0.5% by volume or less, and still more preferably 0.3% by volume or less. In order to reduce the oxygen concentration in the reaction solution, it is also preferable to bubble an inert gas such as nitrogen through the solution. In the above first step, it is preferable that the total usage amount of the aromatic group-containing compound (b) and the unsaturated monocarboxylic acid (c) is 0.8 to 1.2 moles relative to 1 mole of the epoxy group of the epoxy resin (a). By using such a ratio, it is easy to make the curability of the finally obtained alkali-soluble resin and the physical properties of the cured product good. It is preferably 0.85 to 1.15 moles, and more preferably 0.9 to 1.1 moles. By adjusting the usage amounts of the aromatic group-containing compound (b) and the unsaturated monocarboxylic acid (c) in the above first step in this way, an alkali-soluble resin having a polymerizable unsaturated bond equivalent of 700 to 8000 g / equivalent can be obtained. As described above, in the first step of the method for producing the first alkali-soluble resin of the present invention, the reaction of the aromatic group-containing compound (b) and the unsaturated monocarboxylic acid (c) with the epoxy resin (a) can be carried out either first or simultaneously. These reactions can be carried out in the presence or absence of a diluent such as the following polymerizable compound or solvent, in the coexistence of a polymerization inhibitor such as hydroquinone or oxygen, and a reaction catalyst such as a tertiary phosphine, trimethylphosphine, tributylphosphine, triphenylphosphine, etc., lithium chloride, a quaternary ammonium salt, a quaternary phosphonium salt, etc., usually at 60 to 140°C. In terms of reaction efficiency, stability during the reaction, and storage stability of the alkali-soluble resin, a tertiary phosphine is preferably used as the reaction catalyst, and triphenylphosphine is particularly preferably used. The amount of the above reaction catalyst is not particularly limited, and is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and still more preferably 0.2 to 2 parts by mass, relative to 100 parts by mass of the epoxy resin (a) having two or more epoxy groups in one molecule. Also, in the first step, a polymerization inhibitor can be used. There is no particular limitation on the polymerization inhibitor, and known ones can be used. For example, benzoquinone, hydroquinone compounds (e.g., hydroquinone, hydroquinone monomethyl ether, p-tert-butylhydroquinone, benzoquinone, etc.), phenol compounds (e.g., 2,6-di-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), etc.), catechol compounds (e.g., p-tert-butylcatechol, etc.), amine compounds (e.g., N,N-diethylhydroxylamine, etc.), 1,1-diphenyl-2-picrylhydrazyl, tri-p-nitrobenzyl, phenothiazine , piperidine 1-oxyl compounds (e.g., 2,2,6,6-tetramethylpiperidine 1-oxyl, etc.), oxygen, etc. When the above polymerization inhibitor is used in the first step, the amount of the polymerization inhibitor used is preferably 0.001 to 1% by mass, more preferably 0.01 to 0.5% by mass, relative to 100% by mass of the epoxy resin (a) having two or more epoxy groups in one molecule. The above reaction can also be carried out in a solvent. Examples of the reaction solvent include: hydrocarbons such as toluene and xylene; cellosolves such as cellosolve and butyl cellosolve; carbitols such as carbitol and butyl carbitol; esters such as cellosolve acetate, carbitol acetate, (di)propylene glycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate, dimethyl adipate, etc.; ketones such as methyl isobutyl ketone and methyl ethyl ketone; ethers such as (di)ethylene glycol dimethyl ether, etc. The reaction temperature in the above first step is not particularly limited as long as the reaction proceeds, and is preferably 40 to 140 °C. By carrying out the reaction at such a temperature, the reaction can be efficiently promoted. The reaction temperature is more preferably 50 to 135 °C, and even more preferably 60 to 130 °C. Also, in the above first step, the epoxy resin (a) and the aromatic group-containing compound (b) or the unsaturated monocarboxylic acid (c) may also be reacted with a carboxylic acid having no double bond. By reacting with the carboxylic acid having no double bond, the double bond equivalent, epoxy equivalent, glass transition temperature, etc. of the alkali-soluble resin can be adjusted. Examples of the carboxylic acid having no double bond include propionic acid, acetic acid, butyric acid, capric acid, 2-ethylhexyl carboxylic acid, etc. Also, in the above first step, the epoxy resin (a) and the aromatic group-containing compound (b) or the unsaturated monocarboxylic acid (c) may also be reacted with an acid compound having a functional group having a free radical scavenging ability or an ultraviolet absorbing ability. By reacting with such an acid compound, weather resistance can be imparted to the resin. Examples of the functional group having a free radical scavenging ability or an ultraviolet absorbing ability include the functional groups having a free radical scavenging ability or an ultraviolet absorbing ability described above. Examples of the acid group of the above acid compound include the acid groups described above, and among them, a carboxyl group is preferred. Specific examples of the acid compound having a functional group having a free radical scavenging ability or an ultraviolet absorbing ability include, for example: 3,5-di-tert-butyl-4-hydroxybenzoic acid, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 3-methylsalicylic acid, trimethylhydroquinone, 3-phenylsalicylic acid, 4-hydroxy-3,5-dimethylbenzoic acid, 3,5-di-tert-butylsalicylic acid, mycophenolic acid, xanthohumol, 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid monoethyl ester, etc. Among them, 3,5-di-tert-butyl-4-hydroxybenzoic acid and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid are preferred. In the second step of the method for producing the alkali-soluble resin, by reacting the reaction product (intermediate) obtained in the above first step with a polyanhydride (d), the polyanhydride (d) can react with the hydroxyl groups present in the reaction product to obtain the alkali-soluble resin of the present invention into which a carboxyl group is introduced. The obtained alkali-soluble resin can be alkali-developed, and thus can be used as an alkali-developable curable resin for image formation or the like. There is no particular limitation on the polyanhydride (d) used in the above second step, and those having 3 to 30 carbon atoms are preferred. Those having 4 to 20 carbon atoms are more preferred, and those having 4 to 10 carbon atoms are even more preferred. Examples of the above polyanhydride (d) include: phthalic anhydride, succinic anhydride, octenyl succinic anhydride, pentadecenyl succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, 3,6-endomethylene tetrahydrophthalic anhydride, methylendomethylene tetrahydrophthalic anhydride, tetrabromophthalic anhydride, 1,2,4-benzenetricarboxylic anhydride and other dibasic anhydrides; aliphatic or aromatic tetracarboxylic dianhydrides such as biphenyltetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, etc. One or more of these polyanhydrides can be used. Among them, it is preferable to use a dibasic anhydride. Also, in terms of making the obtained alkali-soluble resin provide a cured product with particularly excellent solvent resistance, polyanhydrides such as phthalic anhydride, which have a cyclic structure in the alkali-soluble resin, are particularly preferred. In the above second step, it is preferable that the polyanhydride (d) reacts at a ratio of 0.1 mol or more and 1.1 mol or less per 1 chemical equivalent of the hydroxyl group of the reaction product obtained in the reaction of the first step. By reacting the polyanhydride (d) in this way, the addition reaction of the polyanhydride (d) can be carried out efficiently, and carboxyl groups can be appropriately introduced into the obtained alkali-soluble resin. The reaction between the reaction product obtained in the reaction of the first step and the polyanhydride (d) in the above second step, similar to the reaction of the first step, can be carried out in the presence or absence of a diluent such as the following polymerizable compound or solvent, and in the coexistence of the above polymerization inhibitor or reaction catalyst as needed. In the above second step, a reaction catalyst can also be used. Preferably, it is a tertiary phosphine, and more preferably, it is triphenylphosphine. The reaction temperature in the above second step is not particularly limited as long as the reaction proceeds. Preferably, it is 45 to 130 °C. By carrying out the reaction at such a temperature, the reaction can be promoted efficiently. The reaction temperature is more preferably 50 to 120 °C, and even more preferably 55 to 110 °C. Also, when the above alkali-soluble resin has the above structural unit (D), for example, the epoxy resin (a) can be chain-extended by previously reacting the epoxy resin (a) with a compound capable of introducing the above structural unit (D) before the above first step, and the alkali-soluble resin having the above structural unit (D) can be produced by supplying the chain-extended epoxy resin (a) to the above first step. Examples of the compound capable of introducing the above structural unit (D) include the above bisphenol compounds that are the source of the structural unit (D). In the above reaction, a reaction catalyst can also be used. Examples of the reaction catalyst used in this reaction include the same ones as those used in the above first step or second step. As long as the above first step and second step are included, the manufacturing method of the above first alkali-soluble resin may also include other steps. <Method for Manufacturing Second Alkali-Soluble Resin> As the method for manufacturing the above second alkali-soluble resin, the following method can be cited. Regarding the compound containing an aromatic group, a compound containing a sulfur atom is used, and the polymerizable unsaturated bond equivalent of the alkali-soluble resin is not limited to 700 to 8000 g / equivalent. Other than this, it includes the same first step and second step as the manufacturing method of the above first alkali-soluble resin. The compound (b') containing an aromatic group used in the manufacturing method of the above second alkali-soluble resin preferably contains a sulfur atom. The compound (b') containing an aromatic group is preferably among the compounds (b) containing an aromatic group used in the manufacturing method of the above first alkali-soluble resin, and is a compound in which the group capable of reacting with an epoxy group contains a sulfur atom. The compound (b') containing an aromatic group is preferably a compound containing the above aromatic group and a mercapto group. Also, in the first step of the manufacturing method of the above second alkali-soluble resin, the addition amount of the compound (b') containing an aromatic group is preferably such that, relative to 1 chemical equivalent (molar equivalent) of the epoxy group of the epoxy resin (a), the acid group in the compound (b') containing an aromatic group becomes 0.01 to 0.99 mol and reacts, more preferably 0.2 to 0.95 mol, still more preferably 0.4 to 0.93 mol, still more preferably 0.6 to 0.9 mol, particularly preferably 0.6 to 0.85 mol, and most preferably 0.6 to 0.80 mol. In the above second alkali-soluble resin, the polymerizable unsaturated bond equivalent is not limited, but by adjusting the usage amounts of the compound (b') containing an aromatic group and the unsaturated monocarboxylic acid (c) in the above first step, an alkali-soluble resin with a polymerizable unsaturated bond equivalent of 300 to 8000 g / equivalent can be obtained. The manufacturing method of the alkali-soluble resin of the present invention described above includes the above first step and second step. As the reaction product (intermediate) obtained in the above first step, a resin having a structure containing an aromatic ring represented by the following formula (1') and a structure containing a polymerizable unsaturated bond represented by the following formula (2'), and having a polymerizable unsaturated double bond equivalent of 600 to 7000 g / equivalent is preferably cited. (In formula (1'), R 1 represents an oxygen atom or a sulfur atom; R 2 represents an aromatic group which may have a substituent; in formula (2'), R 4 、R 5 and R 6 R, which may be the same or different, represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; 7 and R 8 which may be the same or different, represent a direct bond or a divalent organic group), and such a resin is also one of the present invention, having excellent photocurability and capable of providing a cured product with a high refractive index. R in the above formula (1') 1 and R 2 are the same as those in the above formula (1), and R in the above formula (2') 4 ~R 8 are the same as those in the above formula (2). The polymerizable unsaturated bond equivalent of the above resin is not particularly limited, preferably 650 to 6000 g / equivalent, more preferably 700 to 5000 g / equivalent, and still more preferably 750 to 4000 g / equivalent. As the resin having a structure containing an aromatic ring represented by the above formula (1'), resins having a structural unit (A') in which "-CH-O-R 3 " in the above formula (a) is "-CH-OH" can be preferably cited. As the content rate of the structural unit (A') in the above resin, a range similar to the content rate of the above structural unit (A) can be preferably cited. As the resin having a structure containing a polymerizable unsaturated bond represented by the above formula (2'), resins having a structural unit (B') in which "-CH-O-R 9 " in the above formula (b) is "-CH-OH" can be preferably cited. As the content rate of the structural unit (B') in the above resin, a range similar to the content rate of the above structural unit (B) can be preferably cited. The above resin may further have the above structural unit (C) and structural unit (D). 3. Photosensitive resin composition A photosensitive resin composition containing the first and / or second alkali-soluble resin, a polymerizable compound, and a photoinitiator of the present invention is also one of the present invention. Since the photosensitive resin composition of the present invention contains the above alkali-soluble resin, it has excellent photocurability and can provide a cured product with a high refractive index. Hereinafter, the first alkali-soluble resin and the above second alkali-soluble resin of the present invention will also be collectively referred to as the alkali-soluble resin of the present invention. The content of the above-mentioned first and / or second alkali-soluble resin is not particularly limited and can be appropriately set according to the use or the composition of other components. For example, relative to the total solid content of the photosensitive resin composition of 100% by mass, it is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, still more preferably 15 to 75% by mass, and particularly preferably 15 to 70% by mass. Furthermore, in this specification, the "total solid content" means the total amount of components that form the cured product (components other than solvents or curing catalysts that volatilize during the formation of the cured product). (Polymerizable compound) The above-mentioned polymerizable compound is a low-molecular compound having a polymerizable unsaturated bond (also referred to as a polymerizable unsaturated group) that can be polymerized by irradiation with active energy rays such as free radicals, electromagnetic waves (such as infrared rays, ultraviolet rays, X-rays, etc.), and electron rays. For example, a monofunctional compound having 1 polymerizable unsaturated group in the molecule and a polyfunctional compound having 2 or more polymerizable unsaturated groups can be cited. Examples of the above-mentioned monofunctional compound include N-substituted maleimide monomers; (meth)acrylates; (meth)acrylamides; unsaturated monocarboxylic acids; unsaturated polycarboxylic acids; unsaturated monocarboxylic acids with a chain extension between the unsaturated group and the carboxyl group; unsaturated acid anhydrides; aromatic vinyls; conjugated dienes; vinyl esters; vinyl ethers; N-vinyl compounds; unsaturated isocyanates, etc. Also, monomers having an active methylene or active methylene group can be used. Examples of the above-mentioned polyfunctional compound include the following compounds, etc. Difunctional (meth)acrylate compounds such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, bisphenol A epoxy alkane di(meth)acrylate, bisphenol F epoxy alkane di(meth)acrylate; Trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, ethylene oxide adduct of trimethylolpropane tri(meth)acrylate, ethylene oxide adduct of ditrimethylolpropane tetra(meth)acrylate, ethylene oxide adduct of pentaerythritol tetra(meth)acrylate, ethylene oxide adduct of dipentaerythritol hexa(meth)acrylate, propylene oxide adduct of trimethylolpropane tri(meth)acrylate, propylene oxide adduct of ditrimethylolpropane tetra(meth)acrylate, propylene oxide adduct of pentaerythritol tetra(meth)acrylate, propylene oxide adduct of dipentaerythritol hexa(meth)acrylate, ε-caprolactone adduct of trimethylolpropane tri(meth)acrylate, ε-caprolactone adduct of ditrimethylolpropane tetra(meth)acrylate, ε-caprolactone adduct of pentaerythritol tetra(meth)acrylate, ε-caprolactone adduct of dipentaerythritol hexa(meth)acrylate, succinic acid modified dipentaerythritol pentacrylate, succinic acid modified pentaerythritol triacrylate, phthalic acid modified dipentaerythritol pentacrylate, phthalic acid modified pentaerythritol triacrylate, the following formula: Modified products of dipentaerythritol hexaacrylate and other trifunctional or higher polyfunctional (meth)acrylate compounds represented by; Ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerol trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide adduct of trimethylolpropane trivinyl ether, ethylene oxide adduct of ditrimethylolpropane tetravinyl ether, ethylene oxide adduct of pentaerythritol tetravinyl ether, ethylene oxide adduct of dipentaerythritol hexavinyl ether and other polyfunctional vinyl ethers; 2-Vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 5-vinyloxypentyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenylmethyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyethoxyethoxyethoxy)ethyl (meth)acrylate and other (meth)acrylate esters containing vinyl ether groups; Ethylene glycol diallyl ether, diethylene glycol diallyl ether, polyethylene glycol diallyl ether, propylene glycol diallyl ether, butylene glycol diallyl ether, hexylene glycol diallyl ether, bisphenol A epoxy alkane diallyl ether, bisphenol F epoxy alkane diallyl ether, trimethylolpropane triallyl ether, ditrimethylolpropane tetraallyl ether, glycerol triallyl ether, pentaerythritol tetraallyl ether, dipentaerythritol pentaallyl ether, dipentaerythritol hexaallyl ether, ethylene oxide adduct trimethylolpropane triallyl ether, ethylene oxide adduct ditrimethylolpropane tetraallyl ether, ethylene oxide adduct pentaerythritol tetraallyl ether, ethylene oxide adduct dipentaerythritol hexaallyl ether and other polyfunctional allyl ethers; (Meth)acrylic acid allyl ester and other (meth)acrylate esters containing allyl groups; Tris(acryloyloxyethyl) isocyanurate, tris(methacryloyloxyethyl) isocyanurate, ethylene oxide adduct tris(acryloyloxyethyl) isocyanurate, ethylene oxide adduct tris(methacryloyloxyethyl) isocyanurate and other polyfunctional (meth)acryloyl group-containing isocyanurates; Triallyl isocyanurate and other polyfunctional allyl group-containing isocyanurates; Polyfunctional amino ester (meth)acrylate esters obtained by the reaction of polyfunctional isocyanates such as tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate with (meth)acrylate esters containing hydroxyl groups such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate; Polyfunctional aromatic vinyls such as divinylbenzene. These polymerizable compounds can be used alone or in combination of two or more. Among the above polymerizable compounds, from the viewpoint of further improving the curability of the photosensitive resin composition, it is preferably to use polyfunctional polymerizable compounds. The functional number of the above polyfunctional polymerizable compound is preferably 3 or more, more preferably 4 or more. Also, the above functional number is preferably 10 or less, more preferably 8 or less. The above functional group number is preferably 3 to 10, more preferably 4 to 8. The molecular weight of the above polymerizable compound is not particularly limited, and from the viewpoint of operation, for example, it is preferably 2000 or less. As the above-mentioned polyfunctional polymerizable compound, from the viewpoints of reactivity, economy, availability, etc., it is preferably exemplified by compounds having (meth)acryloyl groups such as polyfunctional (meth)acrylate compounds, polyfunctional amine ester (meth)acrylate compounds, and (meth)acryloyl group-containing isocyanurate compounds, and more preferably exemplified by polyfunctional (meth)acrylate compounds. By including a compound having a (meth)acryloyl group, the above-mentioned photosensitive resin composition becomes more excellent in photosensitivity and curability, and a cured product having further high hardness and high transparency can be obtained. As the above-mentioned polyfunctional polymerizable compound, it is further preferable to use a polyfunctional (meth)acrylate compound having three or more functional groups. The content of the above-mentioned polymerizable compound is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and further preferably 15 to 40% by mass based on 100% by mass of the total solid content of the photosensitive resin composition. (Photoinitiator) As specific examples of the above-mentioned photoinitiator, for example, 2-methyl-1-[4-(methylthio)phenyl]-2-N- quinolinylpropan-1-one ("IRGACURE (registered trademark) 907", manufactured by BASF), 2-benzyl-2-dimethylamino-1-(4-N- quinolinylphenyl)-butan-1-one ("IRGACURE369", manufactured by BASF), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4- Aminoketone compounds such as (quinolin-4-yl)phenyl)butan-1-one (「IRGACURE379」, manufactured by BASF); Benzil ketal compounds such as 2,2-dimethoxy-1,2-diphenylethane-1-one (「IRGACURE651」, manufactured by BASF), methyl phenylglyoxylate (「DAROCUR MBF」, manufactured by BASF); Hydroxyketone compounds such as 1-hydroxycyclohexyl phenyl ketone (「IRGACURE184」, manufactured by BASF), 2-hydroxy-2-methyl-1-phenylpropan-1-one (「DAROCUR1173」, manufactured by BASF), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one (「IRGACURE2959」, manufactured by BASF), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)benzyl]phenyl}-2-methylpropan-1-one (「IRGACURE127」, manufactured by BASF), 1-hydroxycyclohexyl phenyl ketone + benzophenone (「IRGACURE500」, manufactured by BASF); and other alkylphenone compounds exemplified in paragraphs

[0084] to

[0086] of Japanese Patent Laid-Open No. 2013-227485; Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyl oxime) (「OXE01」, manufactured by BASF), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyl oxime) (「OXE02」, manufactured by BASF), 1,2-octanedione, 1-[4-(phenylthio)-, 2-,(O-benzoyl oxime)], ethanone (「OXE03」, manufactured by BASF), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyl oxime) (「OXE04」, manufactured by BASF); Benzophenone compounds; Benzoin compounds; 9-oxothio compounds; Halomethylated tri compounds; Halomethylated 1,2,4-oxadiazole compounds; Biimidazole compounds; Titanocene compounds; Benzoate compounds; Acridine compounds; Phosphine oxide compounds, etc. Among them, aminoketone compounds and oxime ester compounds are preferred. The above photoinitiators can be used alone or in combination of two or more. The content of the above photoinitiator is preferably 0.3 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 8% by mass with respect to the total solid content of the photosensitive resin composition of 100% by mass. The photosensitive resin composition of the present invention contains at least the above alkali-soluble resin, polymerizable compound, and photoinitiator, and may further contain one or more other components as needed. Also, each of the contained components can be used singly or in combination of two or more. Hereinafter, other components will be described. (Polyfunctional thiol compound) The above photosensitive resin composition may further contain a polyfunctional thiol compound. When the above alkali-soluble resin containing a polymerizable unsaturated bond in the side chain and a polyfunctional thiol compound are included, an ene-thiol reaction occurs upon exposure or heating, and the crosslinking density can be increased. Especially when an acrylate-based polymerizable unsaturated bond exists in the resin, the ene-thiol reaction proceeds well. As the above polyfunctional thiol compound, a compound having two or more mercapto groups in one molecule and a molecular weight of 200 to 1000 is preferred, and a tri- to penta-functional secondary thiol is particularly preferred. By adding such a polyfunctional thiol compound to the above photosensitive resin composition, the curability and storage stability can be further improved. Examples of the above polyfunctional thiol compound include: butanediol bis(thiopropionate), ethylene glycol bis(thiopropionate), trimethylolpropane tris(thiopropionate), pentaerythritol tetrakis(thiopropionate), pentaerythritol tetrakis(3-mercaptobutyrate) (Karenz (registered trademark) PE-1), 1,4-bis(3-mercaptobutyryloxy)butane (Karenz BD-1), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-tri -2,4,6(1H,3H,5H)-trione (Karenz NR-1) and other mercaptopropionate derivatives. Further, as the above polyfunctional thiol compound, a compound having no hydroxyl group and / or aromatic ring in the molecule is preferred. Commercially available products of the above polyfunctional thiol compound can also be used. For example, "THIOKALCOL 20" manufactured by Kao Corporation, "Karenz MT (registered trademark) PE1", "Karenz MT BD1", "Karenz MT NR1", "TPMB", "TEMB" manufactured by Showa Denko K.K., "TMMP", "TEMPIC", "PEMP", "EGMP-4", "DPMP", "TMMP II-20P", "PEMP II-20P", etc. manufactured by SC Organic Chemistry Co., Ltd. The content of the above polyfunctional thiol compound is preferably 0.3 to 15% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 8% by mass relative to the total amount of the solid components of the photosensitive resin composition of 100% by mass. (Metal Oxide Particles) Further, the above photosensitive resin composition preferably contains metal oxide particles. By including metal oxide particles in the above photosensitive resin composition, a cured product with a higher refractive index can be provided. Also, the photosensitivity and dielectric properties are improved. The reason is not clear, but it is speculated that the reason is that if the refractive index difference between the resin and the metal oxide particles becomes smaller, light loss caused by Rayleigh scattering, etc. can be reduced during exposure. Since the resolution is not impaired even when the metal oxide particles are highly filled in the photosensitive resin composition, the dielectric properties can be improved. Examples of the above metal oxide particles include oxide particles of a light-transmissive metal having a relatively high refractive index and containing atoms such as Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, Nb, Mo, W, Zn, B, Al, Si, Ge, Sn, Pb, Sb, Bi, and Te. Among them, in terms of providing a cured product with an even higher refractive index, the above metal oxide particles more preferably contain at least one metal element selected from the group consisting of Ti, Al, Zr, Zn, Sn, Ce, and Si. Further, from the viewpoint of providing a cured film with a relatively high relative dielectric constant, it is more preferably to contain Zr, and from the viewpoint of providing a cured film with high hardness, it is more preferably to contain Si. The above metal oxide can be an oxide of a single metal, a solid solution of two or more oxides, or a composite oxide. Examples of single metal oxides include: aluminum oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), indium oxide (In 2 O 3 ), zinc oxide (ZnO), tin oxide (SnO 2 ), lanthanum oxide (La 2 O 3 ), yttrium oxide (Y 2 O 3), cerium oxide (CeO 2 ), magnesium oxide (MgO), silicon oxide (SiO 2 ), etc. Examples of solid solutions of two or more oxides include ITO, ATO, etc. Examples of composite oxides include barium titanate (BaTiO 3 ), perovskite (CaTiO 3 ), spinel (MgAl 2 O 4 ), etc. Among them, in terms of providing a cured product with a high refractive index, a high relative dielectric constant, or high hardness, zirconia particles (ZrO 2 particles) and / or silica particles (SiO 2 particles) are preferred. In terms of improving the dispersibility in the photosensitive resin composition, the above metal oxide particles are preferably surface-modified metal oxide particles. The surface modification of the above metal oxide particles can be obtained by known methods such as a method of mixing the above metal oxide particles and a surface modifier in a solvent, or a method of performing a hydrothermal reaction in the presence of water. The above surface modifier is not particularly limited, and examples include known coupling agents, surfactants, carboxylic acid compounds, etc. The surface modifier can be used alone or in combination of two or more. Among them, in terms of further improving the dispersibility of the above metal oxide particles, the above surface modifier is preferably a carboxylic acid compound. Examples of the above carboxylic acid compound include carboxylic acids or (meth)acrylic acids that may have substituents. Examples of the above substituents include: ester group, ether group, amide group, thioester group, thioether group, carbonate group, aminoester group, or ureido group, etc. Further, examples of the above carboxylic acid compound include: aliphatic carboxylic acids or cyclic carboxylic acids such as acetic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, 2-ethylhexanoic acid, 2-methylheptanoic acid, 4-methyloctanoic acid, salicylic acid, naphthenic acid, capric acid, lauric acid, etc. The above metal oxide particles are preferably the metal oxide particles described in Japanese Patent Application Laid-Open No. 2013-216858. The crystallite diameter of the above metal oxide particles is preferably 1 to 20 nm, more preferably 1 to 15 nm, and still more preferably 1 to 10 nm. The above crystallite diameter can be determined by X-ray diffraction analysis. The number-average primary particle diameter of the above metal oxide particles is preferably less than 30 nm, more preferably 1 to 25 nm, still more preferably 3 to 20 nm, still more preferably 5 to 20 nm, and particularly preferably 5 to 15 nm. The number-average primary particle diameter can be determined by the following method: using a transmission electron microscope (TEM), a field emission transmission electron microscope (FE-TEM), a field emission scanning electron microscope (FE-SEM), etc. to magnify and observe the metal oxide particles, randomly selecting 100 particles to measure the length in the major axis direction, and calculating the arithmetic average thereof. The refractive index of the above metal oxide particles is preferably 1.70 to 2.70, more preferably 1.90 to 2.70. The specific surface area of the above metal oxide particles is preferably 10 to 400 m 2 / g, more preferably 20 to 200 m 2 / g, still more preferably 30 to 150 m 2 / g. The content of the above metal oxide particles is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, still more preferably 20 to 80% by mass, based on 100% by mass of the total solid content of the alkali-soluble resin composition. Furthermore, the above photosensitive resin composition may optionally contain other components in addition to the above components. Examples of the above other components include: solvents; colorants (pigments, dyes); dispersants; heat resistance improvers; leveling agents; developing aids; coupling agents such as silane-based, aluminum-based, and titanium-based coupling agents; fillers; thermosetting resins such as phenolic resins, polyvinylphenols, epoxy compounds, and epoxy resins; plasticizers; polymerization inhibitors; ultraviolet absorbers; antioxidants; matting agents; defoaming agents; antistatic agents; lubricants; surface modifiers; thixotropy imparting agents; thixotropy imparting aids; quinone diazide compounds; polyphenol compounds; cationic polymerizable compounds; thermal acid generators, etc. These can be used alone or in combination of two or more. These other components can be appropriately selected from known ones and their usage amounts can also be appropriately set. Furthermore, a photosensitive resin composition (also referred to as photosensitive resin composition (x)) containing the reactant (intermediate) of the above first step, an alkali-soluble resin, a polymerizable compound, and a photoinitiator is also one of the present invention. The alkali-soluble resin contained in the above photosensitive resin composition (x) is not particularly limited, and known alkali-soluble resins can be used, or the alkali-soluble resin of the present invention described above can also be used. Examples of the polymerizable compound and the photoinitiator contained in the photosensitive resin composition (x) described above are the same as those described above. The content of each of these components may be the same as that described above. Furthermore, the photosensitive resin composition (x) described above may also contain other components. Examples of other components are the same as those of the photosensitive resin composition described above. The content of each of these components may be appropriately set. 4. Method for producing the photosensitive resin composition There is no particular limitation on the method for producing the photosensitive resin composition of the present invention, and a known method may be used. For example, a method of mixing and dispersing the above-mentioned respective components using various mixers or dispersers may be cited. There is no particular limitation on the mixing and dispersing steps, and they may be carried out by a known method. Furthermore, other steps that are usually carried out may also be included. Among them, a preferred method for producing the photosensitive resin composition preferably includes the following steps: by the method for producing the above-mentioned alkali-soluble resin, producing an alkali-soluble resin having a polymerizable unsaturated bond equivalent of 700 to 8000 g / equivalent, or when R 1 is a sulfur atom, the polymerizable unsaturated bond equivalent is 300 to 8000 g / equivalent; mixing the obtained alkali-soluble resin, polymerizable compound, and photoinitiator. Such a method for producing the photosensitive resin composition is also one of the present invention. If the alkali-soluble resin or the photosensitive resin composition of the present invention is used, a cured product having a relatively high refractive index and excellent curability can be provided. Such a cured product obtained by curing the alkali-soluble resin or the photosensitive resin composition of the present invention is also one of the present invention. Furthermore, the photosensitive resin composition (x) described above can also provide a cured product having a relatively high refractive index and excellent curability. Such a cured product of the photosensitive resin composition (x) is also one of the present invention. When the above-mentioned cured product is a cured film, its film thickness is preferably 0.1 to 50 μm, more preferably 0.5 to 40 μm, and even more preferably 1 to 30 μm. There is no particular limitation on the method for obtaining the above-mentioned cured product, and a known method may be used. For example, the following methods may be cited: for those obtained by coating or forming the above-mentioned alkali-soluble resin or photosensitive resin composition on a substrate, heating, irradiation with active energy rays such as ultraviolet rays, or a combination thereof is used to cure it to obtain a cured product. Among them, a preferred method for producing the cured product preferably includes the steps of coating the above-mentioned photosensitive resin composition on a substrate to form a coating film, irradiating the formed coating film with light, and heating the light-irradiated coating film. There is no particular limitation on the above-mentioned substrate, and it may be appropriately selected according to the purpose or use. For example, substrates made of various materials such as glass plates and plastic plates may be cited. The method of coating the above photosensitive resin composition on a substrate to form a coating film is not particularly limited, and known methods such as spin coating, slit coating, roll coating, and flow casting coating can be used. Preferably, after coating the above photosensitive resin composition on a substrate, the coated material is dried to form a coating film. The above drying can be carried out by known methods. For example, a hot plate, an IR oven, a convection oven, etc. can be used. The drying conditions can be appropriately selected according to the boiling point of the solvent component contained, the type of the curing component, the film thickness, the performance of the dryer, etc. Usually, it is preferably carried out at a temperature of 50 to 160 °C for 10 seconds to 300 seconds. The method of irradiating light on the formed coating film is not particularly limited, and known methods can be used. Examples of the light source of the actinic ray used for light irradiation include: lamp light sources such as xenon lamps, halogen lamps, tungsten filament lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, medium-pressure mercury lamps, low-pressure mercury lamps, carbon arcs, and fluorescent lamps; laser light sources such as argon ion lasers, YAG lasers, excimer lasers, nitrogen lasers, helium cadmium lasers, and semiconductor lasers, etc. When irradiating light on the above coating film, light irradiation can also be carried out through a photomask. As the photomask, a mask formed with a light-shielding portion according to the target pattern can be used. After irradiating light through the photomask, there may also be a step of removing the unirradiated portion by developing with a developer. The irradiated portion is hardened by light irradiation, and the hardened product is insoluble or hardly soluble in the developer. On the other hand, since the unirradiated portion is dissolved in the developer, it can be removed by the developing treatment to obtain a patterned hardened film. The developing treatment can usually be carried out at a developing temperature of 10 to 50 °C by methods such as dipping development, spray development, brush development, and ultrasonic development. The above developer is not particularly limited as long as it can dissolve the above photosensitive resin composition. Usually, an organic solvent or an alkaline aqueous solution is used, and a mixture thereof can also be used. Furthermore, when using an alkaline aqueous solution as the developer, it is preferably washed with water after development. Examples of the organic solvent or the alkaline aqueous solution are the same as those described in JP-A-2015-157909. After the above light irradiation, it is preferable to heat the coating film at 160 °C or lower. The heating temperature of the coating film is more preferably 150 °C or lower. In terms of maintaining the curability, the lower limit of the heating temperature is preferably 70 °C or higher, and more preferably 80 °C or higher. The above heating temperature is preferably 70 to 160 °C, and more preferably 80 to 150 °C. The heating time is not particularly limited. For example, it is preferably set to 5 to 60 minutes. Also, the heating method is not particularly limited. For example, known heating machines such as a hot plate, a convection oven, and a high-frequency heater can be used. 5. Use The alkali-soluble resin and the photosensitive resin composition of the present invention can obtain a cured product with excellent curability and a relatively high refractive index. Therefore, the above alkali-soluble resin and photosensitive resin composition can be applied to uses that require curability or a relatively high refractive index. Furthermore, the alkali-soluble resin and the photosensitive resin composition of the present invention have a relatively fast development speed and can also be applied to uses that require developability. Therefore, they are suitable for use as optical materials, especially suitable for use as resists. The photosensitive resin composition of the present invention is suitable for use as a negative type and also suitable for use as a positive type. The alkali-soluble resin and the photosensitive resin composition of the present invention, which have a high refractive index, can be widely applied to, for example: magnetic recording materials, catalyst materials, ultraviolet absorption materials, dental materials, contact lenses, intraocular lenses, high-refractive lenses for glasses, optical computing, optical memory media, antireflection films, conformal coatings, microlens arrays, automotive topcoats, paints, coating agents, hair cosmetics, gradient refractive index optical components and dynamic gradient refractive index components, nanoimprint materials, photocurable plastics, polymer compounds for holographic recording, surface coatings for glass, transparent coatings for solar cells, plastic lenses, printing plates, semiconductor light-emitting elements (light-emitting diodes, organic light-emitting diodes, laser diodes), light guiding paths (both planar and "fiber" geometries), semiconductor components, light diffusing members, prism sheets, hard coatings, optical wiring members, diffraction gratings, sealing materials for LEDs, etc., pressure-sensitive adhesives, protective films used on the surfaces of glasses, films, and sheets used in sensor components such as CCD / CMOS or display components such as displays, photocurable resins (OCR) used for bonding liquid crystal and other image display components and plastic cover plates, reflective protective films used for transparent electrodes, etc., to prevent refractive index matching of the skeleton where the ITO electrode of the touch panel can be seen, anti-caking layers, antireflection films for displays, interlayer insulating films for semiconductors, and various other uses. Among them, the alkali-soluble resin and the photosensitive resin composition of the present invention are suitable for use as curable resins or resin compositions for forming semiconductor components or optical materials, especially suitable for use as curable resins or resin compositions for optical materials. In the present invention, the "optical material" refers to materials used in components constituting devices in the field of optics or in the fields of electrical and electronic devices, etc. For example, it refers to materials used in filters, light extraction layers, black matrices, optical spacers, black column spacers, photoresists, protective films (overcoats), planarization layers for TFTs, insulating films for TFTs, surface coatings of optical lenses, etc. used in liquid crystals, organic ELs, quantum dots, mini / micro LED display devices / solid-state imaging elements / touch panel display devices, etc. The alkali-soluble resin of the present invention can also be preferably used for applications using photolithography due to its alkali solubility, and since it can form a cured film having high refractive index, high hardness, and high transparency, the photosensitive resin composition of the present invention is most preferably a curable resin composition for filters, light extraction layers, and color conversion layers for organic EL display devices. The alkali-soluble resin of the present invention can be preferably used as a high-refractive-index member that can be subjected to photolithography and has high transparency. Among them, the above-mentioned alkali-soluble resin and photosensitive resin composition are preferably for display devices, and a display device member and a display device including a cured product of the above-mentioned photosensitive resin composition are also one of the present invention. In addition, the above-mentioned alkali-soluble resin and photosensitive resin composition can be preferably used for various optical components such as inks, printed wiring boards, insulating films, films, organic protective films, etc. or components constituting electrical and electronic devices, etc. Examples Examples are disclosed below to explain the present invention in more detail, but the present invention is not limited to these examples. The various evaluation methods used in this example are as described below. <Weight average molecular weight> The weight average molecular weight (Mw) is determined by gel permeation chromatography (GPC) using polystyrene as a standard substance. The measurement conditions are as described below. Apparatus: Gel permeation chromatography apparatus HLC-8320GPC (manufactured by Tosoh Corporation) Column: TSKgel SuperHZM-M (manufactured by Tosoh Corporation) Detector: RI detector for liquid chromatography Measurement temperature: 40°C Solvent: THF (tetrahydrofuran) Sample concentration: 0.05 g / 10 cc Sample side flow rate: 0.6 ml / min <Acid value> Weigh accurately 3 g of the resin solution, dissolve it in a mixed solvent of 90 g of acetone and 10 g of water, and use 0.1N aqueous KOH solution as the titrant for titration. The titration is carried out using an automatic titrator (trade name: COM-555, manufactured by Hiranuma Sangyo Co., Ltd.). Calculate the acid value (mgKOH / g) per 1 g of the solid content based on the acid value of the resin solution and the solid content of the resin solution. Furthermore, the solid content of the resin solution is determined by the following method. That is, weigh approximately 1 g of the resin solution into an aluminum cup, add approximately 3 g of acetone to dissolve it, and then dry it naturally at room temperature. Subsequently, use a vacuum dryer (manufactured by EYELA Co., Ltd., trade name: VOS-301SD) to dry it at 140 °C under vacuum for 1.5 hours, then place it in a desiccator to cool and measure the mass. Calculate the solid content (mass%) of the resin solution from the mass reduction amount. <Polymerizable unsaturated bond equivalent> It is calculated by dividing the mass (g) of the resin solid content by the amount of polymerizable unsaturated bonds (mol) of the resin. <Epoxy equivalent> The solid content conversion value is determined by the method based on JIS K7236:2001. <Refractive index (resin)> Using a spin coater (manufactured by Mikasa Co., Ltd., 1H-D7), uniformly coat the resin solution in Table 1 on a glass substrate with a size of 5 cm square (soda-lime glass AS-2K, manufactured by ToShin Riko Co., Ltd.). Dry the coated plate at 90 °C for 3 minutes to obtain a laminate. After removing the resin composition attached to the end of the glass substrate, use a Perfect Oven thermostat (manufactured by ESPEC Co., Ltd.) to heat-treat the obtained laminate at 95 °C for 60 minutes, and cool it to room temperature to obtain a laminate with a coating film thickness of 0.5 μm. Use the following device to calculate the refractive index value of the coating film at a light wavelength of 589 nm by simulating the reflectivity of the coating film based on the Fresnel formula from the reflectivity caused by the interference of the measured coating film. Device: Film thickness measurement system F-20 manufactured by FILMETRICS Co., Ltd. Standard fiber stage SS-1 (spot diameter 1.5 mm). <Refractive Index (Photosensitive Resin Composition)> Using a spin coater (manufactured by Mikasa Co., Ltd., 1H-D7), the photosensitive resin compositions with the compositions shown in Tables 2 and 4 were uniformly coated on a 5 cm square glass substrate (soda-lime glass AS-2K, manufactured by ToShin Riko Co., Ltd.). After drying the coated plate at 90 °C for 3 minutes, it was exposed using a high-pressure mercury lamp at 100 mJ to obtain a laminate having a coating film formed on the glass substrate. After removing the resin composition adhering to the ends of the glass substrate, the obtained laminate was heat-treated at 95 °C for 60 minutes using a Perfect Oven thermostat (manufactured by ESPEC Corporation) and cooled to room temperature to obtain a laminate with a coating film thickness of 0.5 μm. The obtained laminate was used as a measurement sample, and the refractive index value was determined by the same method as the refractive index of the above resin. <Solvent Resistance> The photosensitive resin composition with the composition shown in Table 3 was spin-coated on a 5 cm square glass substrate, dried at 100 °C for 3 minutes, exposed using a high-pressure mercury lamp at 200 mJ, and then heat-treated (post-curing) at 150 °C for 40 minutes to obtain a cured film with a film thickness of 2 μm. Subsequently, the cured film was immersed in 20 g of propylene glycol monomethyl ether (PGME) at 40 °C for 10 minutes and then taken out. For the immersion liquid (PGME) after taking out the cured film, the absorbance was measured using a spectrophotometer UV3100 (manufactured by Shimadzu Corporation). The larger the value of the absorbance, the more colorant dissolved in the immersion liquid, and the solvent resistance of the photosensitive resin composition was evaluated to be lower. <Development Rate> After coating the photosensitive resin composition on a 10 cm square glass substrate by the spin coating method and performing heat treatment (90 °C, 3 minutes), through a mask with an opening of 30 μm lines and spaces (line and space) provided at a distance of 50 μm from the coating film, using a UV aligner (manufactured by Dainippon Kagaku Kenkyusho Co., Ltd., trade name "MA-1100") equipped with a 2.0 kW ultra-high pressure mercury lamp, at 60 mJ / cm 2Exposure is performed with the exposure dose (365 nm illuminance conversion), and a 0.05% potassium hydroxide aqueous solution is spread using a spin coater to dissolve and remove the unexposed portion, and the remaining exposed portion is washed with pure water for 10 seconds to perform development, thereby evaluating the developability. Specifically, the coated film developed in the above manner隔着 a photomask is observed using a surface roughness meter (manufactured by Ryoka Systems, trade name "VertScan2.0"), and the spreading time of the 0.05% potassium hydroxide aqueous solution required for the unexposed portion to be lost is set as the development time. ◎: Development time is less than 20 seconds. ○: Development time is 20 seconds or more and less than 30 seconds. △: Development time is 30 seconds or more and less than 40 seconds. ×: Development time is 40 seconds or more <Weather resistance> Using a spin coater (manufactured by Mikasa Co., Ltd., 1H-D7), the photosensitive resin composition solution in Table 4 is uniformly coated on a 5 cm square glass substrate (soda-lime glass AS-2K, manufactured by ToShin Riko Co., Ltd.). The coated plate is dried at 100 °C for 3 minutes to obtain a laminate. After removing the resin composition adhering to the end of the glass substrate, the obtained laminate is exposed with a high-pressure mercury lamp at 100 mJ. Heat treatment is performed at 230 °C for 30 minutes using a Perfect Oven thermostat (manufactured by ESPEC Corporation) and cooled to room temperature to obtain a laminate with a coating film thickness of 2 μm. The obtained laminate is set as a measurement sample, and a weather resistance test is carried out using the following apparatus, conditions, and evaluation method. Apparatus: Xenon Weather Meter X25 (manufactured by Suga Test Instruments) Conditions: Temperature inside the chamber 50 °C, humidity inside the chamber 17%, irradiance 0.45 kW / m 2 , 200 hours Evaluation method: The film thickness reduction rate (%) before and after the test is measured using a film thickness measurement system F-20 manufactured by FILMETRICS. The smaller the value, the better the weather resistance is evaluated. <Measurement of mass reduction rate> Using a TG-DTA (thermogravimetry-differential thermal analysis) apparatus, the zirconia particles are heated from room temperature to 800 °C at 10 °C per minute in an air environment, and the mass reduction rate of the particles is measured. Based on this mass reduction rate, the ratio of the compound for surface modification of the zirconia particles and the ratio of the zirconia particles are obtained. (Synthesis Example 1) Production of alkali-soluble resin (A-1) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, condenser tube, and dropping funnel inlet, 132.1 g of propylene glycol monomethyl ether acetate and 206 g (1 mol of epoxy group) of cresol novolac type epoxy resin (trade name "YDCN-704A", manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent 206 g / eq) were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged with nitrogen bubbling until the oxygen concentration became 0.5% by volume or less, and 102.1 g (0.6 mol) of o-phenylphenol and 1 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing in a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 28.8 g (0.4 mol) of acrylic acid, 0.7 g of triphenylphosphine, 0.3 g of Antage W-400 (manufactured by Kawaguchi Chemical Industry Co., Ltd.) as a polymerization inhibitor, and 12.4 g of propylene glycol monomethyl ether acetate were added to carry out an addition reaction, and the reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 41.9 g (0.42 mol) of succinic anhydride and 108.2 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 7 hours to complete the reaction, and further 771.7 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-1). Various physical properties of the obtained alkali-soluble resin (A-1) are shown in Table 1. (Synthesis Example 2) Production of alkali-soluble resin (A-2) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, cooling tube, and dropping tank inlet, 138.7 g of propylene glycol monomethyl ether acetate and 206 g (1 mol of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the temperature was raised to 120 °C by heating. After the temperature of the reaction vessel reached 120 °C, while maintaining this temperature, the system was purged by nitrogen bubbling until the oxygen concentration became 0.5 vol% or less, and 110.6 g (0.65 mol) of o-phenylphenol, 6.9 g (0.05 mol) of p-hydroxyphenyl-2-ethanol, and 1 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 21.6 g (0.3 mol) of acrylic acid, 0.7 g of triphenylphosphine, 0.3 g of Antage W-400, and 9.3 g of propylene glycol monomethyl ether acetate were added to carry out an addition reaction, and the reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 42.9 g (0.43 mol) of succinic anhydride and 110.8 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100 °C for 7 hours to complete the reaction, and then 790.5 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-2). Various physical properties of the obtained alkali-soluble resin (A-2) are shown in Table 1. (Synthesis Example 3) Production of alkali-soluble resin (A-3) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping tank inlet, 142.9 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolak type epoxy resin "YDCN-704A" as used in Example 1 were added, and the temperature was raised to 120°C by heating. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged by nitrogen bubbling until the oxygen concentration became 0.5% by volume or less, and 126.0 g (0.74 mole) of o-phenylphenol, 1.4 g (0.01 mole) of p-hydroxyphenyl-2-ethanol, and 1.1 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 18.0 g (0.25 mole) of acrylic acid, 0.7 g of triphenylphosphine, 0.4 g of Antage W-400, and 7.7 g of propylene glycol monomethyl ether acetate were added to carry out an addition reaction, and the reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 43.7 g (0.44 mole) of succinic anhydride and 112.8 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 7 hours to complete the reaction. Further, 804.7 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-3). Various physical properties of the obtained alkali-soluble resin (A-3) are shown in Table 1. (Synthesis Example 4) Production of alkali-soluble resin (A-4) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, cooling tube, and dropping tank inlet, 134.3 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged by nitrogen bubbling until the oxygen concentration became 0.5% by volume or less, and 93.6 g (0.55 mole) of o-phenylphenol, 13.8 g (0.1 mole) of p-hydroxyphenyl-2-ethanol, and 1 g of triphenylphosphine were added for an addition reaction. The reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing in a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 25.2 g (0.35 mole) of acrylic acid, 0.7 g of triphenylphosphine, 0.3 g of Antage W-400, and 10.8 g of propylene glycol monomethyl ether acetate were added for an addition reaction. The reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 29.6 g (0.3 mole) of succinic anhydride and 100.3 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 7 hours to complete the reaction. Further, 750.1 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-4). Various physical properties of the obtained alkali-soluble resin (A-4) are shown in Table 1. (Synthesis Example 5) Production of alkali-soluble resin (A-5) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, cooling tube, and dropping tank inlet, 116.6 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged by nitrogen bubbling until the oxygen concentration became 0.5% by volume or less, and 66.1 g (0.6 mole) of benzenethiol and 0.9 g of triphenylphosphine were added for an addition reaction. The reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing in a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 28.8 g (0.4 mole) of acrylic acid, 0.6 g of triphenylphosphine, 0.3 g of Antage W-400, and 12.4 g of propylene glycol monomethyl ether acetate were added for an addition reaction. The reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 37.4 g (0.37 mole) of succinic anhydride and 96.6 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 7 hours to complete the reaction. Further, 689.2 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-5). Various physical properties of the obtained alkali-soluble resin (A-5) are shown in Table 1. (Synthesis Example 6 for an alkali-soluble resin) Production of alkali-soluble resin (A-6) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping tank inlet, 203.6 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy groups) of the same cresol novolak type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 100 °C. After the temperature of the reaction vessel reached 100 °C, it was maintained for 30 minutes to dissolve the resin. While cooling the temperature to 70 °C, the system was purged with nitrogen. 99.2 g (0.9 mole) of benzenethiol and 0.2 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 5 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 7.2 g (0.1 mole) of acrylic acid, 1.3 g of triphenylphosphine, and 0.3 g of Antage W-400 were added to carry out an addition reaction, and the reaction was carried out at 120 °C for 16 hours to complete the reaction. After cooling to room temperature, 27.5 g (0.275 mole) of succinic anhydride and 23.5 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 110 °C for 7 hours to complete the reaction. Further, 284.9 g of propylene glycol monomethyl ether acetate was added to obtain an alkali-soluble resin solution (A-6). Various physical properties of the obtained alkali-soluble resin (A-6) are shown in Table 1. (Synthesis Example 7 for an alkali-soluble resin) Production of alkali-soluble resin (A-7) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping tank inlet, 215.9 g of propylene glycol monomethyl ether acetate and 231 g (1 mole of epoxy groups) of NC-7000-L (a naphthalene-containing novolak type epoxy resin, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 231.0 g / equivalent) were added, and the mixture was heated to 100 °C. After the temperature of the reaction vessel reached 100 °C, it was maintained for 30 minutes to dissolve the resin. While cooling the temperature to 70 °C, the system was purged with nitrogen. 92.5 g (0.84 mole) of benzenethiol and 0.2 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 5 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 11.5 g (0.16 mole) of acrylic acid, 1.3 g of triphenylphosphine, and 0.3 g of Antage W-400 were added to carry out an addition reaction, and the reaction was carried out at 120 °C for 16 hours to complete the reaction. After cooling to room temperature, 27.5 g (0.275 mole) of succinic anhydride and 27.2 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 110 °C for 7 hours to complete the reaction. Further, 303.9 g of propylene glycol monomethyl ether acetate was added to obtain an alkali-soluble resin solution (A-7). Various physical properties of the obtained alkali-soluble resin (A-7) are shown in Table 1. (Synthesis Example 8 for Alkali-Soluble Resin (A-8)) Production of Alkali-Soluble Resin (A-8) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping tank inlet, 135.6 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged with nitrogen, and 108.9 g (0.64 mole) of p-phenylphenol, 1.4 g (0.01 mole) of p-hydroxyphenyl-2-ethanol, and 1 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing in a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 25.2 g (0.35 mole) of acrylic acid, 0.7 g of triphenylphosphine, 0.3 g of Antage W-400, and 10.8 g of propylene glycol monomethyl ether acetate were added to carry out an addition reaction, and the reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 102.3 g (0.67 mole) of tetrahydrophthalic anhydride and 149.5 g of propylene glycol monomethyl ether acetate were added and reacted at 100°C for 10 hours to complete the reaction, and then 904.1 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-8). Various physical properties of the obtained alkali-soluble resin (A-8) are shown in Table 1. (Synthesis Example 9 for Alkali-Soluble Resin (A-9)) Production of Alkali-Soluble Resin (A-9) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping tank inlet, 135 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged with nitrogen, and 102.1 g (0.6 mole) of o-phenylphenol, 6.9 g (0.05 mole) of p-hydroxyphenyl-2-ethanol, and 1 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing in a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 30.1 g (0.35 mole) of methacrylic acid, 0.7 g of triphenylphosphine, 0.3 g of Antage W-400, and 12.9 g of propylene glycol monomethyl ether acetate were added to carry out an addition reaction, and the reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 57.5 g (0.57 mole) of succinic anhydride and 120.5 g of propylene glycol monomethyl ether acetate were added and reacted at 100°C for 8 hours to complete the reaction, and then 820.2 g of propylene glycol monomethyl ether was added to obtain an alkali-soluble resin solution (A-9). Various physical properties of the obtained alkali-soluble resin (A-9) are shown in Table 1. (Synthesis Example 10) Production of alkali-soluble resin (A-10) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, cooling tube, and dropping tank inlet, 310.5 g of propylene glycol monomethyl ether acetate was added. After purging with nitrogen, the temperature was raised to 90°C by heating. On the other hand, as dropping tank (A), a mixture of 70.0 g of methyl methacrylate (MMA), 142.2 g of glycidyl methacrylate (GMA) (1 mol of epoxy group), and 4.2 g of tert-butyl peroxy-2-ethylhexanoate ("PERBUTYL (registered trademark) O" manufactured by NOF Corporation) was prepared by stirring and mixing in a beaker. As dropping tank (B), a mixture of 2.1 g of n-dodecyl mercaptan (nDM) and 7.8 g of propylene glycol monomethyl ether acetate was prepared by stirring and mixing. After the temperature of the reaction vessel reached 90°C, while maintaining this temperature, dropping was started from the dropping tank over 3 hours to carry out polymerization. One hour after the completion of dropping, the inside of the reaction vessel was maintained at 90°C, and then the temperature was raised to 115°C, and curing was carried out for 90 minutes. Thereafter, it was cooled to room temperature, and while bubbling nitrogen, 74.9 g (0.68 mol) of benzenethiol and 0.9 g of triphenylphosphine were added to carry out an addition reaction, and the reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 23.1 g (0.32 mol) of acrylic acid, 0.5 g of triphenylphosphine, and 0.5 g of Antage W-400 were added to carry out an addition reaction, and the reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 38.7 g (0.39 mol) of succinic anhydride was added, and the reaction was carried out at 100°C for 7 hours to complete the reaction, obtaining an alkali-soluble resin solution (A-10). Various physical properties of the obtained alkali-soluble resin (A-10) are shown in Table 1. (Synthesis Example 11) Production of Resin Intermediate (A-11) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping funnel inlet, 116.6 g of propylene glycol monomethyl ether acetate and 206 g (1 mol of epoxy group) of the same cresol novolak type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged by nitrogen bubbling until the oxygen concentration became 0.5% by volume or less. 66.1 g (0.6 mol) of benzenethiol and 0.9 g of triphenylphosphine were added and an addition reaction was carried out. The reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 28.8 g (0.4 mol) of acrylic acid, 0.6 g of triphenylphosphine, 0.3 g of Antage W-400, and 12.4 g of propylene glycol monomethyl ether acetate were added and an addition reaction was carried out. The reaction was carried out for 16 hours to complete the reaction, and a resin intermediate (A-11) was obtained. Various physical properties of the obtained resin intermediate (A-11) are shown in Table 1. (Synthesis Example 12) Production of Alkaline Soluble Resin (A-12) In a reaction vessel equipped with a thermometer, a stirrer, a gas inlet tube, a cooling tube, and a dropping funnel inlet, 181.5 g of propylene glycol monomethyl ether acetate and 206 g (1 mol of epoxy group) of the same cresol novolak type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged by nitrogen bubbling until the oxygen concentration became 0.5% by volume or less. 66.1 g (0.6 mol) of benzenethiol and 0.9 g of triphenylphosphine were added and an addition reaction was carried out. The reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 28.1 g (0.39 mol) of acrylic acid, 2.8 g (0.01 mol) of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoic acid, 0.6 g of triphenylphosphine, 0.3 g of Antage W-400, and 16.6 g of propylene glycol monomethyl ether acetate were added and an addition reaction was carried out. The reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 37.4 g (0.37 mol) of succinic anhydride and 24.3 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 7 hours to complete the reaction. Further, 290.8 g of propylene glycol monomethyl ether was added to obtain an alkaline soluble resin solution (A-12). Various physical properties of the obtained alkaline soluble resin (A-12) are shown in Table 1. (Comparative Synthesis Example 1) Production of Comparative Alkali-Soluble Resin (B-1) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, condenser, and dropping funnel inlet, 117.5 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged with nitrogen, 68.1 g (0.4 mole) of o-phenylphenol and 1 g of triphenylphosphine were added, and an addition reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 43.2 g (0.6 mole) of acrylic acid, 0.6 g of triphenylphosphine, 0.3 g of Antage W-400, and 18.5 g of propylene glycol monomethyl ether acetate were added, and an addition reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 39.5 g (0.39 mole) of succinic anhydride and 101.9 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 7 hours to complete the reaction. Further, 726.8 g of propylene glycol monomethyl ether was added to obtain a comparative alkali-soluble resin solution (B-1). Various physical properties of the obtained alkali-soluble resin (B-1) are shown in Table 1. (Comparative Synthesis Example 2) Production of Comparative Alkali-Soluble Resin (B-2) In a reaction vessel equipped with a thermometer, stirrer, gas inlet tube, condenser, and dropping funnel inlet, 157.6 g of propylene glycol monomethyl ether acetate and 206 g (1 mole of epoxy group) of the same cresol novolac type epoxy resin "YDCN-704A" as used in Example 1 were added, and the mixture was heated to 120°C. After the temperature of the reaction vessel reached 120°C, while maintaining this temperature, the system was purged with nitrogen, 161.7 g (0.95 mole) of o-phenylphenol and 1.1 g of triphenylphosphine were added, and an addition reaction was carried out for 8 hours to complete the reaction. Thereafter, while blowing a nitrogen-air mixed gas adjusted to an oxygen concentration of 7%, 3.6 g (0.05 mole) of acrylic acid, 0.7 g of triphenylphosphine, 0.4 g of Antage W-400, and 1.5 g of propylene glycol monomethyl ether acetate were added, and an addition reaction was carried out for 16 hours to complete the reaction. After cooling to room temperature, 46.2 g (0.46 mole) of succinic anhydride and 119.2 g of propylene glycol monomethyl ether acetate were added, and the reaction was carried out at 100°C for 10 hours to complete the reaction. Further, 850.4 g of propylene glycol monomethyl ether was added to obtain a comparative alkali-soluble resin solution (B-2). Various physical properties of the obtained alkali-soluble resin (B-2) are shown in Table 1. (Examples 1 to 12, Comparative Examples 1 to 2) Using the resins of Synthesis Examples 1 to 12 and Comparative Synthesis Examples 1 to 2, a photosensitive resin composition was prepared with the composition shown in Table 2, and the refractive index of the resin was measured by the above method. The results are shown in Table 2. (Examples 13 to 39, Comparative Examples 3 to 6) With the compositions (solid content amounts) shown in Table 3 or Table 4, the resin solutions obtained in the Synthesis Examples and Comparative Synthesis Examples, dipentaerythritol hexaacrylate, a photopolymerization initiator (Irgacure (registered trademark) OXE-02, manufactured by BASF), Pigment Dispersion 1 or a zirconia particle dispersion liquid, and propylene glycol monomethyl ether acetate were mixed to obtain Photosensitive Resin Compositions 1 to 31. The above Pigment Dispersion 1 and zirconia particle dispersion liquid were prepared by the following methods. (Preparation of Pigment Dispersion 1) 12.9 parts of propylene glycol monomethyl ether acetate, 0.4 part of Disparlon DA-7301 as a dispersant, 2.25 parts of C.I. Pigment Green 58 as a coloring agent, and 1.5 parts of C.I. Pigment Yellow 138 were mixed and dispersed for 3 hours using a paint shaker, thereby obtaining Pigment Dispersion 1. (Preparation of Zirconia Particle Dispersion Liquid) Production Example 1 (Production of Coated Zirconia Nanoparticles Coated with 2-Ethylhexanoic Acid and / or a Carboxylate Salt Derived from 2-Ethylhexanoic Acid (Coated ZrO 2 Particles 1)) A zirconium 2-ethylhexanoate mineral oil solution (782 g, zirconium 2-ethylhexanoate content 44% by mass, manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) was mixed with pure water (268 g). The obtained mixed solution was added to an autoclave equipped with a stirrer, and the atmosphere in the autoclave was replaced with nitrogen. Thereafter, the mixed solution was heated to 180°C and held at this temperature for 16 hours (autoclave internal pressure was 0.94 MPa) to carry out a reaction, generating zirconia particles. Subsequently, the reaction mixture after the reaction was taken out, the precipitate accumulated at the bottom was separated by filtration and washed with acetone, and then dried. After dispersing the dried precipitate (100 g) in toluene (800 mL), it became a turbid solution. Next, as a purification step, it was filtered again using quantitative filter paper (manufactured by ADVANTEC Toyo Co., Ltd., No. 5C) to remove coarse particles and the like in the precipitate. Furthermore, the filtrate was concentrated under reduced pressure to remove toluene, thereby recovering white zirconia nanoparticles 1 (coated ZrO 2 Particles 1). The obtained coated ZrO was analyzed using an XRD diffraction pattern 2The crystal structure of Particle 1 was confirmed, and diffraction lines belonging to tetragonal and monoclinic crystals were detected. According to the intensity of the diffraction lines, the ratio of tetragonal crystal to monoclinic crystal was 54 / 46, and its particle size (crystallite diameter) was 5 nm. The coated ZrO measured by an electron microscope (FE-TEM JEM-2100F TEM manufactured by JEOL Ltd., magnification 600,000 times) 2 The average particle size (number-average primary particle size) of Particle 1 was 12 nm. Also, the obtained coated ZrO was analyzed by infrared absorption spectroscopy 2 Particle 1, and as a result, absorption from C-H and absorption from COOH were confirmed. It is considered that this absorption is due to 2-ethylhexanoic acid on the coated surface of the coated ZrO 2 Particle 1 and / or carboxylate from 2-ethylhexanoic acid. Furthermore, according to the above <Measurement of mass reduction rate>, the mass reduction rate of the coated ZrO 2 Particle 1 was 12 mass%. Therefore, it is known that 2-ethylhexanoic acid on the coated surface of the coated ZrO 2 Particle 1 and / or carboxylate from 2-ethylhexanoic acid is 12 mass% of the whole coated ZrO 2 Particle 1. Production Example 2 (Production of zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate from 2-ethylhexanoic acid and 2-acryloyloxyethyl succinate (coated ZrO 2 Particle 2)) The coated ZrO obtained in Production Example 1 above 2 Particle 1 (10 g) and 2-acryloyloxyethyl succinate (1.5 g) were stirred and mixed in propylene glycol monomethyl ether acetate (12 g, hereinafter referred to as "PGMEA") until uniformly dispersed. Subsequently, by adding n-hexane (36 g), the dispersed particles were aggregated to make the solution turbid, and the aggregated particles were separated from the turbid liquid using filter paper. Thereafter, the separated aggregated particles were added to n-hexane (36 g) and stirred for 10 minutes, and then the aggregated particles were separated using filter paper. The obtained particles were dried in vacuo at room temperature to prepare zirconia nanoparticles (coated ZrO) that had been surface-treated with 2-ethylhexanoic acid and / or carboxylate from 2-ethylhexanoic acid and 2-acryloyloxyethyl succinate 2 Particle 2). The obtained coated ZrO 2Particle 2 was dispersed in deuterated chloroform as a measurement sample, and 1 1H-NMR analysis was performed. As a result, the molar ratio of 2-ethylhexanoic acid and / or carboxylate from 2-ethylhexanoic acid to 2-acryloyloxyethyl succinate was found to be 24:76. The mass reduction rate of the coated ZrO 2 particles 2 measured according to the above <Measurement of mass reduction rate> was 18% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate from 2-ethylhexanoic acid, and 2-acryloyloxyethyl succinate coating the coated zirconia particles were 18% by mass of the whole coated zirconia particles. The coated ZrO 2 particles 2 (7 g), methyl ethyl ketone (3 g), and DISPER BYK-111 (manufactured by BYK Japan Co., 0.14 g) were blended and stirred evenly to obtain a zirconia particle dispersion. The number average primary particle diameter of the above coated ZrO 2 particles 2 measured by an electron microscope was 12 nm. Using the obtained photosensitive resin compositions 1 to 15, the development rate and solvent resistance were evaluated by the above method. The results are shown in Table 3. Using the obtained photosensitive resin compositions 16 to 31, the development rate, refractive index, and weather resistance were evaluated by the above method. The results are shown in Table 4. [Table 1] The descriptions in Table 1 are as follows. YDCN-704A: Cresol novolak type epoxy resin (epoxy equivalent 206 g / equivalent) NC-7000-L: Naphthalene-containing novolak type epoxy resin (epoxy equivalent 231.0 / equivalent) [Table 2] [Table 3] [Table 4] According to Tables 1 to 4, the alkali-soluble resins of the examples having a structure with a specified aromatic ring and a structure with a polymerizable unsaturated bond and a polymerizable unsaturated bond equivalent of 700 to 8000 g / equivalent and the cured products of the photosensitive resin compositions containing the same have a high refractive index of about 1.6. In particular, a resin having a structure containing a sulfur atom and a benzene ring has a high refractive index. By adding metal oxide particles, the development speed deteriorates slightly, but the refractive index further increases. Also, the solvent resistance and developability of the alkali-soluble resins of the examples are good. The photosensitive resin composition using a resin having a structure containing a sulfur atom and a benzene ring has good weather resistance. Furthermore, when using a resin having a functional group with a free radical scavenging ability, very good results are obtained. Also, the resin intermediate (A-11) of Synthesis Example 11 is a synthesis intermediate of the resin (A-5) of Synthesis Example 5 and does not have alkali solubility. Therefore, if this resin is used alone, it does not have developability when preparing a photosensitive resin composition, but it can impart high refractive index properties or high solvent resistance to the photosensitive resin composition. When used in combination with other alkali-soluble resins, a photosensitive resin composition excellent in developability can be prepared. None None

Claims

1. An alkali-soluble resin, characterized in that it has a structure containing an aromatic ring as represented by the following formula (4) and a structure containing polymerizable unsaturated bonds as represented by the following formula (2), (in formula (4), R23 represents an aromatic group that may have substituents; R24 is a hydrogen atom or a group represented by formula (3); in formula (2), R4, R5 and R6 are the same or different and represent hydrogen atoms or hydrocarbon groups with 1 to 6 carbon atoms; R7 and R8 are the same or different and represent directly bonded or divalent organic groups; R9 is a hydrogen atom or a group represented by formula (3); at least one of R24 and R9 is a group represented by formula (3); in formula (3), R10 represents a divalent hydrocarbon group that may have substituents).

2. The alkali-soluble resin in Request 1 has an acid value of 30–150 mgKOH / g.

3. The alkali-soluble resin in claim 1 has an epoxy equivalent exceeding 10,000 g / equivalent.

4. The alkali-soluble resin of claim 1 has a main chain structure with a phenolic varnish structure.

5. The alkali-soluble resin of claim 1 has a polymerizable unsaturated bond equivalent of 300 to 8000 g / equivalent.

6. A photosensitive resin composition, characterized in that it comprises the alkali-soluble resin of claim 1, a polymerizable compound, and a photopolymerization initiator.

7. A cured material, characterized in that it is formed by curing the alkali-soluble resin of claim 1 or the photosensitive resin composition of claim 6.

8. A component for a display device, characterized in that it comprises the hardened material of claim 7.

9. A display device, characterized in that it includes the display device component of claim 8.

10. A method for manufacturing an alkali-soluble resin, characterized in that: the manufacturing method includes a first step of reacting an epoxy resin (a) having two or more epoxy groups in one molecule with an aromatic compound (b') and an unsaturated monocarboxylic acid (c), and a second step of reacting the reaction product obtained in the first step with a polyacid anhydride (d), wherein the aromatic compound (b') is a compound containing an aromatic group and a mercapto group.

11. A method for manufacturing a photosensitive resin composition, characterized in that: the manufacturing method includes the steps of manufacturing an alkali-soluble resin by the method for manufacturing an alkali-soluble resin according to claim 10, and the steps of mixing the obtained alkali-soluble resin, a polymerizable compound and a photopolymerization initiator.

12. A resin, characterized in that: it has a structure containing an aromatic ring as represented by the following formula (1') and a structure containing a polymerizable unsaturated bond as represented by the following formula (2'), wherein the equivalent of the polymerizable unsaturated double bond is 600 to 7000 g / equivalent, (in formula (1'), R1 represents a sulfur atom; R2 represents an aromatic group that may have substituents; in formula (2'), R4, R5 and R6 are the same or different, representing hydrogen atoms or hydrocarbon groups having 1 to 6 carbon atoms; R7 and R8 are the same or different, representing direct bonds or divalent organic groups).

13. A photosensitive resin composition, characterized in that it comprises the resin of claim 12, an alkali-soluble resin, a polymerizable compound, and a photopolymerization initiator.

14. A hardened material, characterized in that it is formed by hardening the photosensitive resin composition of claim 13.