(METH)acrylic resin, photosensitive resin composition, and resin cured film

Abstract

A (meth)acrylic resin comprising: a structural unit (a-1) that has a halogen-substituted phenyl group and that is represented by formula (1) (in the formula, X represents a hydrogen atom, an alkyl group having 1-4 carbon atoms, or a halogen atom, Y represents a single bond or a divalent organic group, R1, R2, R3, R4, and R5 each independently represent H, Br, or I, and at least one of R1, R2, R3, R4, and R5 represents Br or I); and a structural unit (X) having a curable group.

Description

(Meth)acrylic resin, photosensitive resin composition, and resin cured film

[0001] The content of the present disclosure relates to a (meth)acrylic resin, a photosensitive resin composition, and a resin cured film.

[0002] In recent years, with the widespread use of liquid crystal displays, extensive research has been conducted on color filters used as components of liquid crystal displays, overcoat layers provided on these color filters, interlayer insulating films, etc. (for example, Patent Document 1 and Patent Document 2). High refractive indices are often required for these materials. In some cases, hardness suitable for their applications is also required for overcoat layers and the like.

[0003] Japanese Patent Application Laid-Open No. 2019-53266 Japanese Patent Application Laid-Open No. 2023-147017

[0004] However, further improvement has been demanded for materials that兼备 both high refractive index and high hardness.

[0005] An object of the present disclosure is to provide a resin capable of forming a cured film having a high refractive index and high hardness. Another object is to provide a photosensitive resin composition capable of obtaining a resin cured film having a high refractive index and high hardness. Furthermore, an object is to provide a resin cured film having a high refractive index and high hardness.

[0006] The content of the present disclosure includes the following aspects. [1] A structural unit (a-1) represented by formula (1) having a halogen-substituted phenyl group: (In the formula, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom, Y is a single bond or a divalent organic group, and R １ 、R ２ 、R ３ 、R ４ 、and R ５ are each independently H, Br, or I, provided that R １ 、R ２ 、R ３ 、R ４ 、and R ５[1] A (meth)acrylic resin having a structural unit (X) having a curable group, and at least one of the following being Br or I. [2] The (meth)acrylic resin according to [1], wherein the halogen-substituted phenyl group equivalent is 350 to 2000 g / mol. [3] The (meth)acrylic resin according to [1] or [2], wherein the curable group of the structural unit (X) is a thermosetting group. [4] In formula (1), R １ , R ３ , and R ５ I is R ２ , and R ４ is H, or R １ , R ２ , R ３ , R ４ , and R ５A (meth)acrylic resin according to any one of [1] to [3], wherein the (meth)acrylic resin is Br. [5] A (meth)acrylic resin according to any one of [1] to [4], wherein the structural unit (X) includes a structural unit (a-2) having an epoxy group, and the epoxy equivalent is 100 to 10000 g / mol. [6] A (meth)acrylic resin according to any one of [1] to [5], wherein the structural unit (X) includes a structural unit (a-2) having an epoxy group, and the structural unit (a-1) is 10 to 95 mol% and the structural unit (a-2) is 5 to 90 mol% with respect to 100 mol% of the total structural units. [7] A (meth)acrylic resin according to [6], wherein the curable group of the structural unit (X) is a thermosetting group and a photocurable group, and the (meth)acrylic resin has a structure in which an ethylenically unsaturated compound (e) having a group that reacts with the epoxy group is added to at least a part of the epoxy group of the structural unit (a-2). [8] The (meth)acrylic resin according to [7], wherein the (meth)acrylic resin has a structure in which a polybasic acid or polybasic anhydride (h) is added to at least a portion of the hydroxyl group formed by ring-opening of the epoxy group of the structural unit (a-2). [9] The (meth)acrylic resin according to any one of [1] to [8], wherein the curable group of the structural unit (X) is a photocurable group.

[10] The (meth)acrylic resin according to any one of [1] to [9], wherein the structural unit (X) includes a structural unit having an ethylenically unsaturated group, and the ethylenically unsaturated group equivalent is 100 to 10000 g / mol.

[11] The (meth)acrylic resin according to

[10] , wherein the structural unit (X) includes a structural unit having an ethylenically unsaturated group, the structural unit (a-1) is 10 to 95 mol%, the (meth)acrylic resin has a structure in which an ethylenically unsaturated compound (f) having a group that reacts with the acid group is added to a part of the acid group of a (meth)acrylic resin precursor (PA2) having 5 to 90 mol% of a structural unit (a-3) having an acid group, the amount of the ethylenically unsaturated compound (f) is 1 to 70 mol per 100 mol of the structural unit (a-3) of the (meth)acrylic resin precursor (PA2), and the amount of the ethylenically unsaturated compound (f) added is 5 to 100 mol per 100 mol of the structural unit (a-3) of the (meth)acrylic resin precursor (PA2).

[12] A photosensitive resin composition comprising: (meth)acrylic resin (A), a reactive diluent (B), a photopolymerization initiator (C), and a solvent (D), wherein the (meth)acrylic resin (A) is the (meth)acrylic resin described in any of [1] to

[11] .

[13] The photosensitive resin composition according to

[12] , wherein the content of the (meth)acrylic resin (A) is 10 to 99% by mass, the content of the reactive diluent (B) is 1 to 90% by mass, the content of the reactive diluent (B) is 1 to 90% by mass, the content of the photopolymerization initiator (C) is 0.1 to 30 parts by mass, the content of the photopolymerization initiator (C) is 0.1 to 30 parts by mass, the content of the solvent (D) is 30 to 1000 parts by mass, the content of the solvent (D) is 30 to 1000 parts by mass, the total of the components excluding the solvent (D).

[14] A resin-cured film comprising a cured product of the photosensitive resin composition described in

[12] or

[13] .

[0007] According to this disclosure, it is possible to provide a resin that can form a cured film having a high refractive index and high hardness. Furthermore, it is possible to provide a photosensitive resin composition that can obtain a resin cured film having a high refractive index and high hardness. Moreover, it is possible to provide a resin cured film having a high refractive index and high hardness.

[0008] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments shown below.

[0009] In the present disclosure, when "~" is used for a numerical range, the numerical values at both ends are the upper limit value and the lower limit value, respectively, and are included in the numerical range. When multiple upper limit values or lower limit values are described, a numerical range can be formed from all combinations of the upper limit value and the lower limit value. Similarly, when multiple numerical ranges are described, separate numerical ranges can be formed by individually selecting and combining the upper limit value and the lower limit value from these numerical ranges.

[0010] In the present disclosure, "(meth)acrylic acid" means methacrylic acid or acrylic acid, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyloxy" means acryloyloxy or methacryloyloxy. In the present disclosure, "(poly)alkylene glycol" means alkylene glycol or polyalkylene glycol.

[0011] In the present disclosure, the "ethylenically unsaturated bond" means a double bond formed between carbon atoms excluding the carbon atoms forming an aromatic ring, the "ethylenically unsaturated group" means a group having an ethylenically unsaturated bond, and the "ethylenically unsaturated compound" means a compound having an ethylenically unsaturated bond.

[0012] In the present disclosure, the "structural unit" means a unit derived from the polymerizable compound itself used as a monomer or a unit obtained by further modifying the unit derived from the polymerizable compound itself used as a monomer after polymerization.

[0013] <(Meth)acrylic resin (A)> The (meth)acrylic resin (A) of one embodiment has a structural unit (a-1) represented by formula (1) having a halogen-substituted phenyl group (simply referred to as "structural unit (a-1)". The same applies to other structural units): (In the formula, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom, Y is a single bond or a divalent organic group, R １ , R ２ , R ３ , R４ , and R ５ Each of these is independently H, Br, or I, except R １ , R ２ , R ３ , R ４ , and R ５ At least one of the members is Br or I.) and a copolymer having a curable group structural unit (X). The (meth)acrylic resin (A) may optionally contain a structural unit having an epoxy group (a-2), a structural unit having an acid group (a-3), other structural units other than structural units (a-1) to (a-3) (a-4), or a combination of two or more of these as the curable structural unit (X).

[0014] (Meth)acrylic resin (A) may have a structure in which an ethylenically unsaturated compound (e) (also simply referred to as "ethylenically unsaturated compound (e)") having a group that reacts with the epoxy group is attached to at least a portion of the epoxy group of a (meth)acrylic resin precursor (PA1) which contains structural unit (a-1), a structural unit having an epoxy group (a-2), and optionally other structural units (a-4). A structural unit having this structure is a structural unit (X) having a curable group. In this embodiment, (meth)acrylic resin (A) may have a structure in which a polybasic acid or polybasic acid anhydride (h) is attached to at least a portion of the hydroxyl group formed by ring-opening of the epoxy group. A structural unit having this structure is a structural unit (a-3) having an acid group.

[0015] The (meth)acrylic resin (A) may have a structure in which an ethylenically unsaturated compound (f) (also simply called "ethylenically unsaturated compound (f)") having a group that reacts with the acid group is attached to a portion of the acid group of a (meth)acrylic resin precursor (PA2) which contains structural unit (a-1), a structural unit having an acid group (a-3), and optionally other structural units (a-4). The structural unit having this structure is a structural unit (X) having a curable group.

[0016] The halogen-substituted phenyl group equivalent of (meth)acrylic resin (A) is preferably 350 g / mol or more, more preferably 400 g / mol or more, and even more preferably 500 g / mol or more. The halogen-substituted phenyl group equivalent of (meth)acrylic resin (A) is preferably 2000 g / mol or less, more preferably 1500 g / mol or less, and even more preferably 1000 g / mol or less. When the halogen-substituted phenyl group equivalent is 350 g / mol or more, the content of curable groups in (meth)acrylic resin (A) is ensured, and a resin cured film having the desired hardness can be obtained. When the halogen-substituted phenyl group equivalent is 2000 g / mol or less, a resin cured film having high tropism can be obtained. The halogen-substituted phenyl group equivalent of (meth)acrylic resin (A) is preferably 350 to 2000 g / mol, more preferably 400 to 1500 g / mol, and even more preferably 500 to 1000 g / mol.

[0017] The halogen-substituted phenyl group equivalent of (meth)acrylic resin (A) is the mass of (meth)acrylic resin (A) per mole of halogen-substituted phenyl groups in (meth)acrylic resin (A). The halogen-substituted phenyl group equivalent is obtained by dividing the mass of (meth)acrylic resin (A) by the number of halogen-substituted phenyl groups in (meth)acrylic resin (A) (g / mol). In this disclosure, the halogen-substituted phenyl group equivalent of (meth)acrylic resin (A) is a theoretical value calculated from the amount of raw materials used in the production of (meth)acrylic resin (A).

[0018] In embodiments in which the structural unit (X) of (meth)acrylic resin (A) contains a structural unit (a-2) having an epoxy group, the epoxy equivalent of (meth)acrylic resin (A) is preferably 100 g / mol or more, more preferably 500 g / mol or more, and even more preferably 1000 g / mol or more. The epoxy equivalent of (meth)acrylic resin (A) is preferably 10000 g / mol or less, more preferably 8000 g / mol or less, and even more preferably 6000 g / mol or less. When the epoxy equivalent is 100 g / mol or more, the content of structural unit (a-1) in (meth)acrylic resin (A) is ensured, and a resin cured film with high tropism can be obtained. When the epoxy equivalent is 10000 g / mol or less, the content of curable groups in (meth)acrylic resin (A) is ensured, and a resin cured film with the desired hardness can be obtained. The epoxy equivalent of (meth)acrylic resin (A) is preferably 100 to 10,000 g / mol, more preferably 500 to 8,000 g / mol, and even more preferably 1,000 to 6,000 g / mol.

[0019] The epoxy equivalent of (meth)acrylic resin (A) is the mass of (meth)acrylic resin (A) per mole of epoxy groups in (meth)acrylic resin (A). The epoxy equivalent is obtained by dividing the mass of (meth)acrylic resin (A) by the number of epoxy groups in (meth)acrylic resin (A) (g / mol). In this disclosure, the epoxy equivalent of (meth)acrylic resin (A) is a theoretical value calculated from the amount of raw materials used when manufacturing (meth)acrylic resin (A).

[0020] In embodiments in which the structural unit (X) of (meth)acrylic resin (A) contains a structural unit having an ethylenically unsaturated group, the ethylenically unsaturated group equivalent of (meth)acrylic resin (A) is preferably 100 g / mol or more, more preferably 500 g / mol or more, and even more preferably 1000 g / mol or more. The ethylenically unsaturated group equivalent of (meth)acrylic resin (A) is preferably 10000 g / mol or less, more preferably 8000 g / mol or less, and even more preferably 6000 g / mol or less. When the ethylenically unsaturated group equivalent is 100 g / mol or more, the content of structural unit (a-1) in (meth)acrylic resin (A) is ensured, a resin-cured film with high tropism can be obtained, and the storage stability of the photosensitive resin composition containing (meth)acrylic resin (A) is good. If the ethylenically unsaturated group equivalent is 10,000 g / mol or less, the content of curable groups in the (meth)acrylic resin (A) can be ensured, and a resin-cured film with the desired hardness can be obtained. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) is preferably 100 to 10,000 g / mol, more preferably 500 to 8,000 g / mol, and even more preferably 1,000 to 6,000 g / mol.

[0021] The ethylenically unsaturated group equivalent of (meth)acrylic resin (A) is the mass of (meth)acrylic resin (A) per mole of ethylenically unsaturated groups in (meth)acrylic resin (A). The ethylenically unsaturated group equivalent is obtained by dividing the mass of (meth)acrylic resin (A) by the number of ethylenically unsaturated groups in (meth)acrylic resin (A) (g / mol). In this disclosure, the ethylenically unsaturated group equivalent of (meth)acrylic resin (A) is a theoretical value calculated from the amount of raw materials used in the production of (meth)acrylic resin (A).

[0022] In embodiments where (meth)acrylic resin (A) has a structural unit (a-3), and embodiments where (meth)acrylic resin (A) has a structure in which a polybasic acid or polybasic anhydride (h) is added to at least a portion of the hydroxyl group formed by ring-opening of the epoxy group, the acid value of (meth)acrylic resin (A) is preferably 10 KOH mg / g or more, more preferably 20 KOH mg / g or more, and even more preferably 30 KOH mg / g or more. The acid value of (meth)acrylic resin (A) is preferably 300 KOH mg / g or less, more preferably 200 KOH mg / g or less, and even more preferably 150 KOH mg / g or less. When the acid value of (meth)acrylic resin (A) is 10 KOH mg / g or more, the developability of the photosensitive resin composition containing (meth)acrylic resin (A) is good. When the acid value of (meth)acrylic resin (A) is 300 KOH mg / g or less, the photosensitive resin composition containing (meth)acrylic resin (A) has good storage stability.

[0023] The acid value of (meth)acrylic resin (A) is measured according to JIS K 6901:2008 5.3. That is, the acid value represents the number of mg of potassium hydroxide required to neutralize the acidic components contained in 1 g of (meth)acrylic resin (A).

[0024] The weight-average molecular weight (Mw) of (meth)acrylic resin (A) is preferably 1,000 or more, more preferably 2,000 or more, and even more preferably 4,000 or more. The weight-average molecular weight of (meth)acrylic resin (A) is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 10,000 or less. When the weight-average molecular weight of (meth)acrylic resin (A) is 1,000 or more, the patternability of the photosensitive resin composition containing (meth)acrylic resin (A) is good. When the weight-average molecular weight of (meth)acrylic resin (A) is 50,000 or less, the storage stability of the photosensitive resin composition containing (meth)acrylic resin (A) is good.

[0025] The molecular weight distribution (Mw / Mn) of (meth)acrylic resin (A) is preferably 1.3 or higher, more preferably 1.5 or higher, even more preferably 1.7 or higher, and particularly preferably 1.9 or higher. The molecular weight distribution (Mw / Mn) of (meth)acrylic resin (A) is preferably 5.0 or lower, more preferably 4.0 or lower, and even more preferably 3.5 or lower. When the molecular weight distribution (Mw / Mn) of (meth)acrylic resin (A) is 1.3 or higher, it is easy to control the manufacturing conditions during the synthesis of (meth)acrylic resin (A). When the molecular weight distribution (Mw / Mn) of (meth)acrylic resin (A) is 5.0 or lower, the storage stability of the photosensitive resin composition containing (meth)acrylic resin (A) is good.

[0026] In this disclosure, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are measured using gel permeation chromatography (GPC) under the following conditions and obtained using a standard polystyrene calibration curve. Column: Two Showdex® LF-804 columns (Resonac Corporation) connected in series. Column temperature: 40°C. Sample: 0.2% by mass tetrahydrofuran solution of the substance to be measured. Developing solvent: Tetrahydrofuran. Detector: Differential refractometer (Showdex® RI-71S) (Resonac Corporation). Flow rate: 1 mL / min.

[0027] The refractive index of (meth)acrylic resin (A) is preferably 1.55 or higher, more preferably 1.58 or higher, and even more preferably 1.60 or higher. The refractive index of (meth)acrylic resin (A) may be 2.00 or lower, 1.80 or lower, or 1.75 or lower.

[0028] In this disclosure, the "refractive index" of the resin (polymer) alone is the value calculated by the following method. Specifically, the refractive index of a resin composition (sample) containing the resin and solvent is measured under the following conditions, and then the refractive index of the solvent is measured under the following conditions. Next, the resin content (solids) in the sample is measured according to JIS K 6901:2008 5.11, and the refractive index of the resin alone contained in the sample is calculated using the following formula. Measuring instrument: J-357 Automatic Refractometer (Rudolph Research Analytical) Measurement wavelength: 589 nm Measurement temperature: 25°C Refractive index of resin alone = (Refractive index of sample - Refractive index of solvent) ÷ Solids × 100 + Refractive index of solvent

[0029] [Structural unit (a-1) represented by formula (1) having a halogen-substituted phenyl group] Structural unit (a-1) is represented by formula (1). In the formula, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom, preferably a hydrogen atom or a methyl group. Y is a single bond or a divalent organic group. Examples of divalent organic groups represented by Y include an alkanediyl group having 1 to 20 carbon atoms, and a group having -O-, -(C=O)-, -(C=O)O-, -O(C=O)O-, -NH-, -C(=O)NH-, -NH(C=O)O-, -NH(C=O)NH- between the carbon-carbon bonds of the alkanediyl group having 1 to 20 carbon atoms, or between the alkanediyl group and the halogen-substituted phenyl group. Y is preferably a single bond or -R-NHC(=O)O-, and R is (CH ２ ) ｎ And n is an integer from 0 to 4. １ , R ２ , R ３ , R ４ , and R ５ Each of these is independently H, Br, or I, except R １ , R ２ , R ３ , R ４ , and R ５ At least one of them is Br or I. １ , R ２ , R ３ , R ４ , and R５ Preferably, three or more of these are independently Br or I, and R １ , R ３ , and R ５ I is R ２ , and R ４ is H, or R １ , R ２ , R ３ , R ４ , and R ５ It is more preferable that it is Br. The structural unit (a-1) may be only one type or two or more types.

[0030] An example of a preferred structural unit (a-1) is shown below.

[0031] The structural unit (a-1) is derived from the monomer represented by formula (ma-1) (hereinafter also simply referred to as monomer (ma-1). The same applies to other monomers). In the formula, X, Y, R １ , R ２ , R ３ , R ４ , and R ５ This is as explained in equation (1).

[0032] The content of structural unit (a-1) in (meth)acrylic resin (A) can be appropriately determined depending on the application. The content of structural unit (a-1) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 40 mol% or more, based on 100 mol% of the total structural units of (meth)acrylic resin (A). The content of structural unit (a-1) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less. If the content of structural unit (a-1) is 10 mol% or more, the refractive index of (meth)acrylic resin (A) is increased, and a resin cured film with a high refractive index can be obtained. If the content of structural unit (a-1) is 95 mol% or less, the content of curable groups in (meth)acrylic resin (A) is ensured, and a resin cured film with the desired hardness can be obtained. The content of structural unit (a-1) in (meth)acrylic resin (A) is preferably 10 to 95 mol%, more preferably 20 to 90 mol%, even more preferably 30 to 80 mol%, and particularly preferably 40 to 80 mol%. In embodiments in which (meth)acrylic resin (A) has a structure to which an ethylenically unsaturated compound (e) is added, when the total structural units of the (meth)acrylic resin precursor (PA1) are set to 100 mol%, the content of structural unit (a-1) in the (meth)acrylic resin precursor (PA1) is the same as the above range. In embodiments in which (meth)acrylic resin (A) has a structure to which an ethylenically unsaturated compound (f) is added, when the total structural units of the (meth)acrylic resin precursor (PA2) are set to 100 mol%, the content of structural unit (a-1) in the (meth)acrylic resin precursor (PA2) is the same as the above range.

[0033] [Structural unit (X) having a curable group] The structural unit (X) having a curable group is not particularly limited as long as it does not have a halogen-substituted phenyl group and is a structural unit having a curable group. There may be only one type of structural unit (X) or two or more types.

[0034] The curable group of structural unit (X) may be a thermosetting group or a photocurable group. Examples of thermosetting groups include ethylenically unsaturated groups, epoxy groups, hydroxyl groups, and isocyanate groups. Examples of photocurable groups include ethylenically unsaturated groups, epoxy groups, and benzophenone groups. The curable group may be a thermosetting and photocurable group that possesses both thermosetting and photocuring properties. The thermosetting and photocuring properties depend on the curing mode of the curable group and the type of curing agent or initiator that can be applied in combination with the curable group. For example, epoxy groups have cationic polymerizability and function as both thermosetting and photocurable groups depending on the type of curing agent or initiator used. Ethylenelycol unsaturated groups have radical polymerizability and function as both thermosetting and photocurable groups depending on the type of curing agent or initiator used.

[0035] The content of structural units (X) in the (meth)acrylic resin (A) can be appropriately determined depending on the application. The content of structural units (X) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, based on 100 mol% of the total structural units of the (meth)acrylic resin (A). The content of structural units (X) is preferably 90 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. When the content of structural units (X) is 5 mol% or more, the content of curable groups in the (meth)acrylic resin (A) is ensured, and a resin cured film having the desired hardness can be obtained. When the content of structural units (X) is 90 mol% or less, the refractive index of the (meth)acrylic resin (A) is increased, and a resin cured film having a high refractive index can be obtained. The content of structural units (X) in the (meth)acrylic resin (A) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, even more preferably 20 to 70 mol%, and particularly preferably 20 to 60 mol%.

[0036] (Structural unit (a-2) having an epoxy group) In one embodiment, structural unit (X) includes structural unit (a-2) having an epoxy group. Structural unit (a-2) having an epoxy group is not particularly limited as long as it does not have a halogen-substituted phenyl group or an acid group and has an epoxy group. Structural unit (a-2) may be one type or two or more types. Structural unit (a-2) is a structural unit derived from an epoxy group-containing monomer (ma-2).

[0037] Monomer (ma-2) is an ethylenically unsaturated compound having an epoxy group and lacking a halogen-substituted phenyl group. Examples of ethylenically unsaturated compounds having an epoxy group include (meth)acrylic acid ester derivatives containing an epoxy group such as oxyranyl (meth)acrylate, glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 2-ethylglycidyl (meth)acrylate, 2-oxyranylethyl (meth)acrylate, 2-glycidyloxyethyl (meth)acrylate, 3-glycidyloxypropyl (meth)acrylate, 4-glycidyloxybutyl (meth)acrylate, and glycidyloxyphenyl (meth)acrylate; and 3,4-epoxycyclohexyl (meth)acrylate. Examples include epoxy group-containing (meth)acrylates such as acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 2-(3,4-epoxycyclohexyl)ethyl (meth)acrylate, 2-(3,4-epoxycyclohexylmethyloxy)ethyl (meth)acrylate, 3-(3,4-epoxycyclohexylmethyloxy)propyl (meth)acrylate, and other epoxy group-containing alicyclic carbocyclic compounds containing an epoxy group such as a 3,4-epoxycyclohexane ring; vinyl ether compounds containing an epoxy group; and allyl ether compounds containing an epoxy group. The monomer (ma-2) may be used alone or in combination of two or more types.

[0038] As monomers (ma-2), epoxy group-containing (meth)acrylates such as oxyranyl (meth)acrylate, glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 2-ethylglycidyl (meth)acrylate, 2-oxyranyl ethyl (meth)acrylate, 2-glycidyloxyethyl (meth)acrylate, 4-glycidyloxybutyl (meth)acrylate, glycidyloxyphenyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate are preferred from the viewpoint of polymerizability and ease of availability, and glycidyl (meth)acrylate, 4-glycidyloxybutyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate are more preferred.

[0039] When the total structural units of (meth)acrylic resin (A) are set to 100 mol%, the content of structural unit (a-2) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. The content of structural unit (a-2) is preferably 90 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. When the content of structural unit (a-2) is 5 mol% or more, the content of curable groups in (meth)acrylic resin (A) is ensured, and a resin cured film having the desired hardness can be obtained. When the content of structural unit (a-2) is 90 mol% or less, the refractive index of (meth)acrylic resin (A) is increased, and a resin cured film having a high refractive index can be obtained. The content of structural unit (a-2) in (meth)acrylic resin (A) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, even more preferably 20 to 70 mol%, and particularly preferably 20 to 60 mol%.

[0040] [Structural unit having an acid group (a-3)] The (meth)acrylic resin (A) may contain a structural unit having an acid group (a-3). The structural unit having an acid group (a-3) is not particularly limited as long as it does not have a halogen-substituted phenyl group or an epoxy group and has an acid group. There may be only one type of structural unit (a-3) or two or more types. The structural unit (a-3) is a structural unit derived from an acid group-containing monomer (ma-3). By having structural unit (a-3) in the (meth)acrylic resin (A), developability can be imparted to the photosensitive resin composition containing the (meth)acrylic resin (A).

[0041] Examples of acid groups that the structural unit (a-3) may possess include carboxyl groups, sulfol groups, and phosphol groups. Among these acid groups, carboxyl groups are preferred due to their availability. Carboxyl groups can also function as thermosetting groups when combined with, for example, isocyanate crosslinking agents, but in this disclosure they are treated as acid groups.

[0042] Monomer (ma-3) is an ethylenically unsaturated compound that does not have a halogen-substituted phenyl group or epoxy group, but has an acid group. Examples of monomer (ma-3) include unsaturated carboxylic acids or their anhydrides, unsaturated sulfonic acids, and unsaturated phosphonic acids.

[0043] Examples of monomers (ma-3) include unsaturated carboxylic acids or their anhydrides such as (meth)acrylic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl succinic acid, α-bromo(meth)acrylic acid, β-furyl(meth)acrylic acid, crotonic acid, propiolic acid, cinnamic acid, α-cyanocinnamic acid, maleic acid, maleic anhydride, monomethyl maleate, monoethyl maleate, monoisopropyl maleate, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, and citraconic anhydride; unsaturated sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid, tert-butylacrylamidosulfonic acid, and p-styrenesulfonic acid; and unsaturated phosphonic acids such as vinylphosphonic acid. Monomers (ma-3) may be used alone or in combination of two or more.

[0044] As the monomer (ma-3), an unsaturated carboxylic acid is preferred, and (meth)acrylic acid is more preferred, because it is readily available and can impart excellent alkali developability to a photosensitive resin composition containing (meth)acrylic resin (A).

[0045] When the total structural units of (meth)acrylic resin (A) are set to 100 mol%, the content of structural unit (a-3) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. The content of structural unit (a-3) is preferably 90 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. When the content of structural unit (a-3) is 5 mol% or more, the developability of the photosensitive resin composition containing (meth)acrylic resin (A) is good. When the content of structural unit (a-3) is 90 mol% or less, the refractive index of (meth)acrylic resin (A) is increased, and a resin cured film with a high refractive index can be obtained. The content of structural unit (a-3) in (meth)acrylic resin (A) is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, even more preferably 20 to 70 mol%, and particularly preferably 20 to 60 mol%.

[0046] [Introduction of ethylenically unsaturated groups using (meth)acrylic resin precursor (PA1)] In some embodiments, (meth)acrylic resin (A) can be obtained by adding an ethylenically unsaturated compound (e) to at least a portion of the epoxy group using a (meth)acrylic resin precursor (PA1) containing structural unit (a-1) and structural unit (a-2).

[0047] (Ethylene-unsaturated compound (e) having a group that reacts with epoxy groups) Ethylene-unsaturated compound (e) has a group that reacts with epoxy groups and an ethylenically unsaturated group. There may be only one type of ethylenically unsaturated compound (e) or two or more types. By adding ethylenically unsaturated compound (e) to the (meth)acrylic resin precursor (PA1), an ethylenically unsaturated group is introduced into the (meth)acrylic resin (A).

[0048] Acidic groups are preferred as functional groups that have reactivity with epoxy groups.

[0049] As the ethylenically unsaturated compound having an acid group, for example, compounds listed as acid group-containing monomer (ma-3) and a preferred range can be used. The ethylenically unsaturated compound (e) may be used alone or in combination of two or more types.

[0050] When the total structural units of the (meth)acrylic resin precursor (PA1) are set to 100 mol%, the content of structural unit (a-2) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. The content of structural unit (a-2) is preferably 90 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. When the content of structural unit (a-2) is 5 mol% or more, the content of curable groups in the (meth)acrylic resin (A) is ensured, and a resin cured film having the desired hardness can be obtained. When the content of structural unit (a-2) is 90 mol% or less, the refractive index of the (meth)acrylic resin (A) is increased, and a resin cured film having a high refractive index can be obtained.

[0051] The amount of ethylenically unsaturated compound (e) is preferably 5 moles or more, more preferably 10 moles or more, and even more preferably 20 moles or more, per 100 moles of structural units of (meth)acrylic resin precursor (PA1). The amount of ethylenically unsaturated compound (e) is preferably 90 moles or less, more preferably 80 moles or less, even more preferably 70 moles or less, and particularly preferably 60 moles or less, per 100 moles of structural units of (meth)acrylic resin precursor (PA1). When the amount of ethylenically unsaturated compound (e) is 5 moles or more, the curability of (meth)acrylic resin (A) can be increased. When the amount of ethylenically unsaturated compound (e) is 90 moles or less, the refractive index of (meth)acrylic resin (A) can be increased, and a resin cured film with a high refractive index can be obtained.

[0052] The amount of ethylenically unsaturated compound (e) added is preferably 60 moles or more, more preferably 70 moles or more, and even more preferably 90 moles or more, per 100 moles of structural units (a-2) of the (meth)acrylic resin precursor (PA1). The amount of ethylenically unsaturated compound (e) added is 100 moles or less, may be 99 moles or less, or 95 moles or less, per 100 moles of structural units (a-2) of the (meth)acrylic resin precursor (PA1). When the amount of ethylenically unsaturated compound (e) added per 100 moles of structural units (a-2) of the (meth)acrylic resin precursor (PA1) is 60 moles or more, the curability of the (meth)acrylic resin (A) can be improved.

[0053] [Introduction of ethylenically unsaturated groups using (meth)acrylic resin precursor (PA2)] In some embodiments, (meth)acrylic resin (A) can be obtained by adding an ethylenically unsaturated compound (f) to an acid group using a (meth)acrylic resin precursor (PA2) containing structural units (a-1) and (a-3).

[0054] (Ethylene-unsaturated compound (f) having a group that reacts with an acid group) The ethylenically unsaturated compound (f) has a group that reacts with an acid group and an ethylenically unsaturated group. The ethylenically unsaturated compound (f) may be one type or two or more types. By adding the ethylenically unsaturated compound (f) to the (meth)acrylic resin precursor (PA2), an ethylenically unsaturated group is introduced into the (meth)acrylic resin (A).

[0055] Examples of functional groups that react with acidic groups include epoxy groups, oxetanyl groups, hydroxyl groups, and isocyanate groups. Among these, epoxy groups are preferred from the viewpoint of ease of synthesis of (meth)acrylic resin (A).

[0056] As the ethylenically unsaturated compound having an epoxy group, for example, compounds listed as epoxy group-containing monomer (ma-2) and a preferred range can be used. The ethylenically unsaturated compound (f) may be used alone or in combination of two or more types.

[0057] When the total structural units of the (meth)acrylic resin precursor (PA2) are set to 100 mol%, the content of structural unit (a-3) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. The content of structural unit (a-3) is preferably 90 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. When the content of structural unit (a-3) is 5 mol% or more, the content of curable groups in the (meth)acrylic resin (A) is ensured, and a resin cured film having the desired hardness can be obtained. When the content of structural unit (a-3) is 90 mol% or less, the refractive index of the (meth)acrylic resin (A) is increased, and a resin cured film having a high refractive index can be obtained.

[0058] The amount of ethylenically unsaturated compound (f) is preferably 1 mole or more, more preferably 5 moles or more, and even more preferably 10 moles or more, per 100 moles of structural units of (meth)acrylic resin precursor (PA2). The amount of ethylenically unsaturated compound (f) is preferably 70 moles or less, more preferably 60 moles or less, and even more preferably 50 moles or less, per 100 moles of structural units of (meth)acrylic resin precursor (PA2). When the amount of ethylenically unsaturated compound (f) per 100 moles of structural units of (meth)acrylic resin precursor (PA2) is 1 mole or more, the curability of (meth)acrylic resin (A) can be increased. When the amount of ethylenically unsaturated compound (f) per 100 moles of structural units of (meth)acrylic resin precursor (PA2) is 70 moles or less, the refractive index of (meth)acrylic resin (A) can be increased, and a resin cured film with a high refractive index can be obtained.

[0059] The amount of ethylenically unsaturated compound (f) added is preferably 5 moles or more, more preferably 10 moles or more, and even more preferably 20 moles or more, per 100 moles of structural units (a-3) of the (meth)acrylic resin precursor (PA2). The amount of ethylenically unsaturated compound (f) added is 100 moles or less, preferably 90 moles or less, and more preferably 70 moles or less, per 100 moles of structural units (a-3) of the (meth)acrylic resin precursor (PA2). When the amount of ethylenically unsaturated compound (f) added per 100 moles of structural units (a-3) is 5 moles or more, the curability of the (meth)acrylic resin (A) can be improved. When the amount of ethylenically unsaturated compound (f) added per 100 moles of structural units (a-3) is 90 moles or less, the content of acid groups in the (meth)acrylic resin (A) can be ensured, and good developability can be imparted to the photosensitive resin composition containing the (meth)acrylic resin (A).

[0060] [Introduction of acid groups utilizing hydroxyl groups generated by ring-opening of epoxy groups] In some embodiments, an ethylenically unsaturated compound (e) is added to at least a portion of the epoxy groups of a (meth)acrylic resin precursor (PA1), and a polybasic acid or polybasic acid anhydride (h) is further added to at least a portion of the hydroxyl groups generated by ring-opening of the epoxy groups, thereby obtaining a (meth)acrylic resin (A) having carboxyl groups as acid groups. In these embodiments, since it is easy to adjust the amount of carboxyl groups introduced by the polybasic acid or polybasic acid anhydride (h), the developability of the photosensitive resin composition containing the (meth)acrylic resin (A) can be adjusted to a desired range.

[0061] (Polybasic acid or polybasic anhydride (h)) A polybasic acid or polybasic anhydride (h) is a compound having two or more carboxyl groups or its anhydride. There may be only one polybasic acid or polybasic anhydride (h), or there may be two or more.

[0062] Examples of polybasic acids include adipic acid, itaconic acid, methylitaconic acid, succinic acid, oxalic acid, malonic acid, phthalic acid, fumaric acid, maleic acid, ethyl maleic acid, chlormaleic acid, citraconic acid, glutaric acid, tartaric acid, glutamic acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 4-methylhexahydrophthalic acid, 2-norvonene-5,6-dicarboxylic acid, 4-[2-(methacryloyloxy)ethoxycarbonyl]phthalic acid, and cyclohexanetricarboxylic acid. Examples of polybasic acid anhydrides include the anhydrides of the polybasic acids mentioned above. These compounds may be used individually or in combination of two or more. From the viewpoint of availability, itaconic anhydride, methylitaconic anhydride, succinic anhydride, maleic anhydride, ethyl maleic anhydride, chlormaleic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, 2-norvonene-5,6-dicarboxylic acid anhydride, 4-[2-(methacryloyloxy)ethoxycarbonyl]phthalic anhydride, and cyclohexanetricarboxylic acid anhydride are preferred. From the viewpoint of hardness of the cured resin film, polybasic acid anhydrides having an alicyclic structure are preferred. From the viewpoint of increasing the amount of carboxyl groups introduced and improving low-temperature curability, tetrahydrophthalic anhydride and cyclohexanetricarboxylic acid anhydride are more preferred.

[0063] The amount of polybasic acid or polybasic acid anhydride (h) is preferably 5 moles or more, more preferably 10 moles or more, and even more preferably 15 moles or more, when the structural units of the (meth)acrylic resin precursor (PA1) are considered to be 100 moles. The amount of polybasic acid or polybasic acid anhydride (h) is preferably 50 moles or less, more preferably 40 moles or less, and even more preferably 30 moles or less, when the structural units of the (meth)acrylic resin precursor (PA1) are considered to be 100 moles. When the amount of polybasic acid or polybasic acid anhydride (h) is 5 moles or more, the developability of the photosensitive resin composition containing (meth)acrylic resin (A) is good. When the amount of polybasic acid or polybasic acid anhydride (h) is 50 moles or less, the storage stability of the photosensitive resin composition containing (meth)acrylic resin (A) is good.

[0064] The amount of polybasic acid or polybasic acid anhydride (h) added is preferably 10 moles or more, more preferably 20 moles or more, and even more preferably 30 moles or more, when the ethylenically unsaturated compound (e) is considered to be 100 moles. The amount of polybasic acid or polybasic acid anhydride (h) added is preferably 90 moles or less, more preferably 70 moles or less, and even more preferably 60 moles or less, when the ethylenically unsaturated compound (e) is considered to be 100 moles. When the amount of polybasic acid or polybasic acid anhydride (h) added is 10 moles or more, the developability of the photosensitive resin composition containing (meth)acrylic resin (A) is good. When the amount of polybasic acid or polybasic acid anhydride (h) added is 90 moles or less, the storage stability of the photosensitive resin composition containing (meth)acrylic resin (A) is good.

[0065] [Other structural units (a-4)] (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), and (meth)acrylic resin precursor (PA2) may, if necessary, have other structural units (a-4) other than structural units (a-1) to (a-3). Other structural units (a-4) do not have halogen-substituted phenyl groups, acid groups, or epoxy groups, and are structural units derived from other monomers (ma-1) to (ma-3) that can copolymerize with monomers (ma-1) to (ma-3). Structural units (a-4) can be used to adjust the physical properties of (meth)acrylic resin (A) or to impart functionality to (meth)acrylic resin (A).

[0066] Examples of monomers (ma-4) include aromatic vinyl compounds, cyclic olefins having a norbornene structure, dienes, (meth)acrylic acid esters, (meth)acrylamides, vinyl compounds, unsaturated dicarboxylic acid diesters, monomaleimides, (meth)acrylamides, (meth)acrylonitriles, and acrolein.

[0067] Examples of aromatic vinyl compounds include styrene, α-methylstyrene, o-vinyltoluene, p-vinyltoluene, o-chlorostyrene, m-chlorostyrene, methoxystyrene, p-nitrostyrene, p-cyanostyrene, and p-acetylaminostyrene.

[0068] Examples of cyclic olefins having a norbornene structure include norbornene(bicyclo[2.2.1]hept-2-ene), 5-methylbicyclo[2.2.1]hept-2-ene, and tetracyclo[4.4.0.1 ２，５ 1. ７，１０ ] Dodeca-3-ene, 8-ethyltetracyclo[4.4.0.1 ２，５ 1. ７，１０ ] Dodeca-3-ene, dicyclopentadiene, tricyclo[5.2.1.0 ２，６ Deca-8-en, tricyclo[4.4.0.1 ２，５ ]Undeca-3-ene, tricyclo[6.2.1.0 １，８ ]Undeka-9-ene, tetracyclo[4.4.0.1 ２，５ 1. ７，１０ . 0 １，６ ] Dodeca-3-ene, 8-ethylidenetetracyclo[4.4.0.1 ２，５ 1. ７，１２ ] Dodeca-3-ene and pentacyclo[6.5.1.1 ３，６ . 0 ２，７ . 0 ９，１３ ] Pentadeca-4-ene is one example.

[0069] Examples of dienes include butadiene, isoprene, and chloroprene.

[0070] Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, benzyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, rosin (meth)acrylate, norbornyl (meth)acrylate, 5-ethylnorbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, and tricyclodecanyl (meth)acrylate. Examples include acrylates, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 1,1,1-trifluoroethyl (meth)acrylate, perfluoroethyl (meth)acrylate, perfluoro-n-propyl (meth)acrylate, 3-(N,N-dimethylamino)propyl (meth)acrylate, triphenylmethyl (meth)acrylate, phenyl (meth)acrylate, cumyl (meth)acrylate, 4-phenoxyphenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol mono (meth)acrylate, biphenyloxyethyl (meth)acrylate, anthracene (meth)acrylate, and ethoxylated phenyl (meth)acrylate.

[0071] Examples of (meth)acrylamides include (meth)acrylamide, (meth)acrylate N,N-dimethylamide, (meth)acrylate N,N-diisopropylamide, and (meth)acrylate anthracenylamide.

[0072] Examples of vinyl compounds include vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, N-vinylpyrrolidone, vinylpyridine, vinyl acetate, and vinyltoluene.

[0073] Examples of unsaturated dicarboxylic acid diesters include diethyl citraconate, diethyl maleate, diethyl fumarate, and diethyl itaconate.

[0074] Examples of monomaleimides include N-phenylmaleimide, N-cyclohexylmaleimide, and N-laurylmaleimide.

[0075] The monomer (ma-4) may be used alone or in combination of two or more types.

[0076] From the viewpoint of the refractive index of the (meth)acrylic resin (A), the monomer (ma-4) is preferably a compound whose refractive index when formed as a homopolymer is 1.5 or higher, and more preferably a compound whose refractive index is 1.55 or higher. Specific examples of such compounds include vinyltoluene (refractive index of homopolymer 1.58), styrene (refractive index of homopolymer 1.58), and benzyl methacrylate (refractive index of homopolymer 1.56).

[0077] When (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), or (meth)acrylic resin precursor (PA2) contains structural unit (a-4), the content of structural unit (a-4) is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, based on 100 mol% of the total structural units of (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), or (meth)acrylic resin precursor (PA2). The content of structural unit (a-4) is preferably 50 mol% or less, more preferably 30 mol% or less, and even more preferably 20 mol% or less, based on 100 mol% of the total structural units of (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), or (meth)acrylic resin precursor (PA2). When the content of structural unit (a-4) is 1 mol% or more, the desired function can be imparted to (meth)acrylic resin (A). If the content of structural unit (a-4) is 50 mol% or less, the content of structural units (a-1) to (a-3) can be ensured, thereby obtaining a (meth)acrylic resin (A) and a resin-cured film having a high refractive index, and, if necessary, good developability can be imparted to the photosensitive resin composition containing (meth)acrylic resin (A).

[0078] <Photosensitive Resin Composition> The photosensitive resin composition of one embodiment contains the above-mentioned (meth)acrylic resin (A), a reactive diluent (B), a photopolymerization initiator (C), and a solvent (D). The photosensitive resin composition can be cured by light irradiation to form a cured resin film.

[0079] The content of (meth)acrylic resin (A) in the photosensitive resin composition is preferably 10% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more, relative to the total of (meth)acrylic resin (A) and reactive diluent (B). The content of (meth)acrylic resin (A) is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, relative to the total of (meth)acrylic resin (A) and reactive diluent (B). When the content of (meth)acrylic resin (A) is within the above range, the viscosity of the photosensitive resin composition becomes within a range suitable for handling, and in addition, the photocurability is also improved. The content of (meth)acrylic resin (A) in the photosensitive resin composition is preferably 10 to 99% by mass, more preferably 40 to 95% by mass, and even more preferably 60 to 90% by mass, relative to the total of (meth)acrylic resin (A) and reactive diluent (B).

[0080] [Reactive Diluent (B)] The reactive diluent (B) may be any low molecular weight compound having at least one ethylenically unsaturated group, and is not particularly limited. In this disclosure, a low molecular weight compound is a compound with a molecular weight of less than 1000. Examples of ethylenically unsaturated groups include vinyl groups, allyl groups, and (meth)acryloyloxy groups. From the viewpoint of improving curability, a polyfunctional reactive diluent having multiple ethylenically unsaturated groups is preferred. Specific examples of the reactive diluent (B) include aromatic vinyl compounds; aromatic allyl compounds such as diallyl phthalate and diallylbenzenephosphonate; vinyl carboxylates such as vinyl acetate and vinyl adipate; monofunctional (meth)acrylates; polyfunctional (meth)acrylates; and triallyl cyanurate.

[0081] Specific examples of aromatic vinyl compounds include styrene, α-methylstyrene, α-chloromethylstyrene, vinyltoluene, and divinylbenzene.

[0082] Specific examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, β-hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate.

[0083] Specific examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and tri(meth)acrylate of tris(hydroxyethyl) isocyanurate.

[0084] For the reactive diluent (B), a polyfunctional (meth)acrylate is preferred to improve reactivity, and at least one selected from the group consisting of dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate is more preferred.

[0085] The reactive diluent (B) may be used alone or in combination of two or more types.

[0086] The content of reactive diluent (B) in the photosensitive resin composition is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total of (meth)acrylic resin (A) and reactive diluent (B). The content of reactive diluent (B) is preferably 90% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less, relative to the total of (meth)acrylic resin (A) and reactive diluent (B). When the content of reactive diluent (B) is within the above range, the viscosity of the photosensitive resin composition becomes within a range suitable for handling, and in addition, the photocurability is also improved. The content of reactive diluent (B) in the photosensitive resin composition is preferably 1 to 90% by mass, more preferably 5 to 60% by mass, and even more preferably 10 to 40% by mass, relative to the total of (meth)acrylic resin (A) and reactive diluent (B).

[0087] [Photopolymerization initiator (C)] The photopolymerization initiator (C) is not particularly limited, but examples include: ethanolone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl-]-,1-(O-acetyloxime); benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, and other benzoin and its alkyl ethers; acetophenone compounds such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 4'-(1-t-butyldioxy-1-methylethyl)acetophenone; 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one; 2-benzyl-2-dimethylamino-1-(4-mol Examples include pholinophenyl)butanone-1; anthraquinone compounds such as 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone, and 1-chloroanthraquinone; xanthones; thioxanthone compounds such as thioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; ketal compounds such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenone compounds such as benzophenone, 4-(1-t-butyldioxy-1-methylethyl)benzophenone, and 3,3',4,4'-tetrakis(t-butyldioxycarbonyl)benzophenone; and acylphosphine oxide-based photopolymerization initiators. The photopolymerization initiator (C) may be used alone or in combination of two or more types.

[0088] The content of the photopolymerization initiator (C) in the photosensitive resin composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, based on 100 parts by mass of the total of the (meth)acrylic resin (A) and the reactive diluent (B). The content of the photopolymerization initiator (C) in the photosensitive resin composition is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the total of the (meth)acrylic resin (A) and the reactive diluent (B). When the content of the photopolymerization initiator (C) is 0.1 parts by mass or more, a photosensitive resin composition with good photocurability can be obtained. When the content of the photopolymerization initiator (C) is 30 parts by mass or less, it is possible to prevent adverse effects on the physical properties of the cured product of the photosensitive resin composition due to an excessive amount of the photopolymerization initiator (C).

[0089] [Solvent (D)] Examples of solvent (D) include ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; diethylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether and diethylene glycol mono-n-butyl ether; triethylene glycol monomethyl ether; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and propylene glycol monoethyl ether; dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether; tripropylene glycol monoalkyl ethers such as tripropylene glycol monoethyl ether; 3-methoxy-1-butanol; (poly)alkylene glycol monoalkyl ether; hydroxyl group-containing carboxylic acid esters such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl hydroxyethyl acetate, methyl 2-hydroxy-3-methylbutyrate; and diethylene glycol Hydroxyl group-containing organic solvents such as ethanol; and (poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and tetrahydrofuran; methyl ethyl ketone, cyclohexanone, 2 Ketones such as -heptanone and 3-heptanone; esters such as methyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl ethoxyacetate, methyl-3-methoxybutyl acetate, methyl-3-methoxybutylpropionate, ethyl acetate, n-butyl acetate, i-propyl acetate, i-butyl acetate, n-amyl acetate, i-amyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutyrate;Examples include aromatic hydrocarbons such as toluene and xylene; and hydroxyl-free organic solvents such as carboxylic acid amides such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. Solvent (D) may be used alone or in combination of two or more.

[0090] Among these solvents (D), it is preferable to use compounds having an ether structure from the viewpoint of ease of availability, cost, and stability during resist preparation. More specifically, it is preferable to use at least one selected from the group consisting of propylene glycol monomethyl ether acetate, diethylene glycol methyl ethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and 3-methoxy-1-butanol.

[0091] The content of solvent (D) in the photosensitive resin composition is preferably 30 parts by mass or more, and more preferably 50 parts by mass or more, based on 100 parts by mass of the total components excluding solvent (D). The content of solvent (D) in the photosensitive resin composition is preferably 1,000 parts by mass or less, and more preferably 800 parts by mass or less, based on 100 parts by mass of the total components excluding solvent (D). When the content of solvent (D) is 30 parts by mass or more, the viscosity of the photosensitive resin composition can be kept within an appropriate range. When the content of solvent (D) is 1,000 parts by mass or less, the solvent (D) can be easily removed when removing the solvent (D) from a coating film formed by applying the photosensitive resin composition to a substrate.

[0092] [Other Components] The photosensitive resin composition may include, as needed, known additives such as curing aids, coupling agents, leveling agents, and polymerization inhibitors, in addition to (meth)acrylic resin (A), reactive diluent (B), photopolymerization initiator (C), and solvent (D). The amount of additives is not particularly limited, as long as it does not hinder the effects of the present invention.

[0093] In one embodiment, the photosensitive resin composition contains a polyfunctional thiol as an epoxy curing aid or a photoradical or thermal radical curing aid. Examples of polyfunctional thiols include pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinan-2,4,6-trione, and trimethylolpropane tris(3-mercaptobutyrate).

[0094] In one embodiment, the photosensitive resin composition contains (meth)acrylic resin (A), which allows for the production of a resin-cured film having high hardness and a high refractive index. Therefore, a resin-cured film with a high refractive index can be obtained without the need to use inorganic particles to improve the refractive index of the resin-cured film, or to use a dispersant to disperse the inorganic particles. In one embodiment, the photosensitive resin composition is substantially free of inorganic particles or does not contain inorganic particles. "Substantially free" means that the inorganic particle content in the photosensitive resin composition is less than 1% by mass, less than 0.5% by mass, or less than 0.1% by mass.

[0095] <Meth)acrylic resin (A) production method> In one embodiment, (meth)acrylic resin (A) can be produced by a method that includes the step of copolymerizing monomer (ma-1), monomer (ma-2), and optionally other monomer (ma-4).

[0096] In another embodiment, (meth)acrylic resin (A) can be produced by a method comprising the steps of: copolymerizing monomer (ma-1), monomer (ma-2), and optionally other monomer (ma-4) to obtain a (meth)acrylic resin precursor (PA1); and adding an ethylenically unsaturated compound (e) to at least a portion of the epoxy groups of the structural unit (a-2) of the (meth)acrylic resin precursor (PA1) to obtain (meth)acrylic resin (A). In this embodiment, after adding the ethylenically unsaturated compound (e), a polybasic acid or polybasic acid anhydride (h) may be added to at least a portion of the hydroxyl groups formed by ring-opening of the epoxy groups to obtain (meth)acrylic resin (A).

[0097] In another embodiment, (meth)acrylic resin (A) can be produced by a method comprising the steps of: copolymerizing monomer (ma-1), monomer (ma-3), and optionally other monomer (ma-4) to obtain a (meth)acrylic resin precursor (PA2); and adding an ethylenically unsaturated compound (f) to a portion of the acid group of structural unit (a-3) of (meth)acrylic resin precursor (PA2) to obtain (meth)acrylic resin (A).

[0098] The proportions of structural units (a-1), (a-2), (a-3), and (a-4) contained in (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), or (meth)acrylic resin precursor (PA2) are equivalent to the proportions of each monomer (ma-1), monomer (ma-2), monomer (ma-3), and monomer (ma-4) in the total amount of all monomers used as raw materials for (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), or (meth)acrylic resin precursor (PA2).

[0099] The proportion of each monomer used in the copolymerization reaction to form (meth)acrylic resin (A), (meth)acrylic resin precursor (PA1), or (meth)acrylic resin precursor (PA2) is not particularly limited.

[0100] When monomer (ma-2) is used, preferably monomer (ma-1) is 10 to 95 mol% and monomer (ma-2) is 5 to 90 mol%, more preferably monomer (ma-1) is 20 to 90 mol% and monomer (ma-2) is 10 to 80 mol%, even more preferably monomer (ma-1) is 30 to 80 mol% and monomer (ma-2) is 20 to 70 mol%, and particularly preferably monomer (ma-1) is 40 to 80 mol% and monomer (ma-2) is 20 to 60 mol%.

[0101] When monomer (ma-3) is used, preferably monomer (ma-1) is 10 to 95 mol% and monomer (ma-3) is 5 to 90 mol%, more preferably monomer (ma-1) is 20 to 90 mol% and monomer (ma-3) is 10 to 80 mol%, even more preferably monomer (ma-1) is 30 to 80 mol% and monomer (ma-3) is 20 to 70 mol%, and particularly preferably monomer (ma-1) is 40 to 80 mol% and monomer (ma-3) is 20 to 60 mol%.

[0102] The copolymerization reaction can be carried out in or without a solvent according to radical polymerization methods known in the art. For example, the monomer can be dissolved in an organic solvent, a polymerization initiator (i) can be added to the solution, and the polymerization reaction can be carried out at 50 to 150°C for 1 to 20 hours.

[0103] As the solvent used in the copolymerization reaction, the same solvent as solvent (D) described above can be used. Other examples include propylene glycol monoaryl ether, 1,3-propanediol monoalkyl ether, 1,3-butanediol monoalkyl ether, 1,4-butanediol monoalkyl ether, glycerin monoalkyl ether, glycerin dialkyl ether, methanol, ethanol, propanol, C5-6 cycloalkanol, C5-6 cycloalkanediol, C5-6 cycloalkanedimethanol, ethyl lactate, and diacetone alcohol, which are hydroxyl group-containing organic solvents. "C5-6 cycloalkane" means that the cycloalkyl group has 5-6 carbon atoms. The solvents may be used individually or in combination of two or more.

[0104] The polymerization initiator (i) that can be used in the copolymerization reaction is not particularly limited, but examples include azobisisobutyronitrile, azobisisovaleronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), benzoyl peroxide, and t-butylperoxy-2-ethylhexanoate. The polymerization initiator (i) may be used alone or in combination of two or more. The amount of polymerization initiator (i) used is generally 0.5 to 20 parts by mass, preferably 1.0 to 18 parts by mass, per 100 parts by mass of the total amount of monomer charged. A chain transfer agent (n), such as thioglycolic acid, may also be used in combination in the copolymerization reaction.

[0105] As a method for adding an ethylenically unsaturated compound (e) to at least a portion of the epoxy groups of a (meth)acrylic resin precursor (PA1), and optionally subsequently adding a polybasic acid or polybasic acid anhydride (h), and as a method for adding an ethylenically unsaturated compound (f) to a portion of the acid groups of a (meth)acrylic resin precursor (PA2), known addition reactions can be used. For example, after adding a polymerization inhibitor (j) and a catalyst (k) to the reaction solution in which the copolymerization reaction has been carried out, an ethylenically unsaturated compound (e), an ethylenically unsaturated compound (f), a polybasic acid or polybasic acid anhydride (h) can be added as the compound to be added, and the addition reaction can be carried out under conditions of room temperature (23°C) to 150°C, preferably 50 to 120°C.

[0106] Polymerization inhibitors (j) are added to prevent side reactions of the introduced ethylenically unsaturated groups. Examples of polymerization inhibitors (j) include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, and dibutylhydroxytoluene.

[0107] Examples of catalysts (k) include quaternary ammonium salts such as triethylbenzylammonium chloride; phosphorus compounds such as triphenylphosphine, tris(2,6-dimethoxyphenyl)phosphine, triparathylphosphine, tricyclohexylphosphine, and tetraphenylphosphonium salts; and organometallic compounds containing metals such as chromium and tin. The amount of catalyst (k) used is preferably 0.1 to 12 parts by mass, and more preferably 0.2 to 6.0 parts by mass, per 100 parts by mass of the monomer used in the copolymerization reaction of the (meth)acrylic resin precursor (PA1) or (meth)acrylic resin precursor (PA2), as well as the ethylenically unsaturated compound (e) and the ethylenically unsaturated compound (f).

[0108] <Method for producing a photosensitive resin composition> The photosensitive resin composition of one embodiment can be produced by mixing a (meth)acrylic resin (A), a reactive diluent (B), a photopolymerization initiator (C), a solvent (D), and additives as needed, using a known mixing apparatus.

[0109] When manufacturing a photosensitive resin composition, the reaction solution used to manufacture (meth)acrylic resin (A) can be used as a raw material. In this case, the solvent contained in the reaction solution can be used as part or all of the solvent (D) contained in the photosensitive resin composition.

[0110] When producing a photosensitive resin composition, (meth)acrylic resin (A) isolated from a reaction solution containing (meth)acrylic resin (A) by a known method may be used as a raw material.

[0111] Since the photosensitive resin composition contains (meth)acrylic resin (A) having a high refractive index, it can form a resin cured film with a high refractive index.

[0112] The photosensitive resin composition contains a (meth)acrylic resin (A) having curable groups, a reactive diluent (B), and a photopolymerization initiator (C). Therefore, upon irradiation with light, the curable groups contained in the (meth)acrylic resin (A) and the reactive diluent (B) react or polymerize, resulting in good photocurability.

[0113] If the (meth)acrylic resin (A) contained in the photosensitive resin composition has an acid value, the photosensitive resin composition has good alkali developability. Because such a photosensitive resin composition has excellent alkali developability, for example, it can be applied to a substrate to form a coating film, exposed through a photomask corresponding to a predetermined pattern shape, developed in an alkaline aqueous solution for the unexposed areas, and then baked to form a cured resin product having a predetermined pattern shape.

[0114] Photosensitive resin compositions are extremely useful as materials for forming components of image display elements, such as color filter protective films, insulating films, photospacers, liquid crystal alignment protrusions, microlenses, and insulating films for touch panels.

[0115] <Cured Resin Film> The cured resin film of one embodiment is a cured product of the above-mentioned photosensitive resin composition.

[0116] A resin-cured film can be manufactured, for example, by applying a photosensitive resin composition to a substrate, volatilizing and removing the solvent (D) to form a coating film, exposing the coating film to light-curing, and then performing a baking treatment.

[0117] When forming a resin-cured film having a predetermined pattern shape, a (meth)acrylic resin (A) having an acid value can be used, and for example, the method shown below can be used. That is, a photosensitive resin composition is applied to a substrate, and the solvent (D) is evaporated and removed to form a coating film. Next, the coating film is exposed to light through a photomask having a predetermined pattern shape to photocur the exposed portion. Then, the unexposed portion of the coating film is developed with an alkaline aqueous solution. After that, the developed coating film is subjected to a baking treatment to form a resin-cured film having a predetermined pattern shape.

[0118] When manufacturing a cured resin film, known methods can be used for the method of applying the photosensitive resin composition, the method of exposing the applied film to light, and the method of developing the film.

[0119] The baking conditions performed when manufacturing a cured resin film can be appropriately determined according to the composition of the photosensitive resin composition, the thickness of the coated film, the material of the substrate, and so on. The baking process can be carried out at a temperature of, for example, 70°C to 250°C.

[0120] The baking process performed when manufacturing the resin-cured film can be carried out for, for example, 10 minutes to 4 hours, preferably 20 minutes to 2 hours, and can be appropriately determined depending on the composition of the photosensitive resin composition, the temperature of the baking process, the thickness of the coated film, etc.

[0121] The resin-cured film can preferably be used as a transparent film, protective film, insulating film, overcoat, photospacer, or component of a microlens.

[0122] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0123] The materials used in the example are as follows: TIPA: 2,4,6-triiodophenyl acrylate PBrPA: 2,3,4,5,6-pentabromopenylate GMA: glycidyl methacrylate (Tokyo Chemical Industries, Ltd.) AA: acrylic acid (Tokyo Chemical Industries, Ltd.) MAA: methacrylic acid (Kuraray Co., Ltd.) PQMA: 4-hydroxyphenyl methacrylate (Resonac Co., Ltd.) Light acrylate NMT-A: 1-naphthylmethyl acrylate (Kyoeisha Chemical Co., Ltd.) NVC: N-vinylcarbazole (Nisshoku Techno Fine Chemical Co., Ltd.) EEA: 2-(2-ethoxyethoxy)ethyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) St: styrene (Tokyo Chemical Industries, Ltd.) TCDMA: tricyclodecanyl methacrylate (Resonac Co., Ltd.) BZMA: benzyl methacrylate (Tokyo Chemical Industries, Ltd.) THPA: tetrahydrophthalic anhydride SA: Succinic anhydride V-601: 2,2'-Azobis(2-methylpropionic acid)dimethyl (NOF Co., Ltd.) TBO: t-Butyl peroxy-2-ethylhexanoate (NOF Co., Ltd.) MEHQ: Hydroquinone monomethyl ether TPP: Triphenylphosphine CyP: Cyclopentanol DPHA: Dipentaerythritol hexaacrylate (Product name: A-DPH, Shin Nakamura Kogyo Co., Ltd.) Irgacure (trademark) OXE02: Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl-]-,1-(O-acetyloxime) (BASF Japan Ltd.) PGMEA: Propylene glycol monomethyl ether acetate (Kuraray Co., Ltd.) Karenz (registered trademark) MT NR1: 1,3,5-Tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinan-2,4,6-trione (Resonac Co., Ltd.)

[0124] An example of the synthesis of (meth)acrylic resin (A) is shown below.

[0125] [Example 1] 110.0 g of cyclopentanol as solvent (D) was placed in a flask equipped with a stirring device, a dropping funnel, a condenser, a thermometer, and a gas inlet tube. The mixture was stirred while purging with nitrogen gas and the temperature was raised to 98°C.

[0126] Next, a raw material monomer solution was prepared by mixing 188.5 g (90 mol%) of TIPA as monomer (ma-1), 5.7 g (10 mol%) of glycidyl methacrylate as monomer (ma-2), 190.0 g of cyclopentanol as solvent (D), and 5.8 g (3 parts by mass per 100 parts by mass of the total monomer components) of 2,2'-azobis(2-methylpropionic acid)dimethyl as polymerization initiator (i).

[0127] The entire volume of the prepared raw material monomer solution was added dropwise over 1 hour using a dropping funnel to solvent (D) in a flask under atmospheric pressure and nitrogen gas atmosphere. After the addition was complete, the solution in the flask was polymerized at 98°C for 5 hours while stirring to obtain a liquid containing (meth)acrylic resin (A) and solvent (D). The acid value, weight-average molecular weight, molecular weight distribution, epoxy equivalent, ethylenically unsaturated group equivalent, and halogen-substituted phenyl group equivalent of (meth)acrylic resin (A) were determined by the method described above. The results are shown in Table 1.

[0128] [Examples 2 to 6, Example 10, Comparative Examples 1 to 3] Liquids containing (meth)acrylic resin (A) or (cA) and solvent (D) were obtained using the same procedure as in Example 1, except that the types and compositions of monomers were changed as shown in Table 1 or Table 2. The results are shown in Tables 1 and 2.

[0129] [Example 7] 104.0 g of cyclopentanol as solvent (D) was placed in a flask equipped with a stirring device, a dropping funnel, a condenser, a thermometer, and a gas inlet tube, and the mixture was stirred while purging with nitrogen gas, and the temperature was raised to 98°C.

[0130] Next, a raw material monomer solution was prepared by mixing 149.2 g (60 mol%) of TIPA as monomer (ma-1), 26.9 g (40 mol%) of glycidyl methacrylate as monomer (ma-2), 176 g of cyclopentanol as solvent (D), and 10.6 g (6 parts by mass per 100 parts by mass of the total monomer components) of 2,2'-azobis(2-methylpropionic acid)dimethyl as polymerization initiator (i).

[0131] The entire volume of the prepared raw material monomer solution was added dropwise over 1 hour using a dropping funnel to solvent (D) in a flask under atmospheric pressure and nitrogen gas atmosphere. After the addition was complete, the solution in the flask was stirred and polymerized at 98°C for 5 hours to obtain a liquid containing (meth)acrylic resin precursor (PA1) and solvent (D).

[0132] In a flask at atmospheric pressure under a nitrogen gas atmosphere, a liquid containing (meth)acrylic resin precursor (PA1) and solvent (D) was added. 0.6 g of hydroquinone monomethyl ether as a polymerization inhibitor (j) (0.3 parts by mass per 100 parts by mass of the total monomer component and ethylenically unsaturated compound (e)), 0.6 g of triphenylphosphine as a catalyst (k) (0.3 parts by mass per 100 parts by mass of the total monomer component and ethylenically unsaturated compound (e)), and 13.4 g of acrylic acid as the ethylenically unsaturated compound (e) were added. The mixture was reacted at 110°C for 10 hours with stirring to obtain a liquid containing (meth)acrylic resin (A) and solvent (D). 20.2 g of cyclopentanol was added to this liquid to prepare a solution of (meth)acrylic resin (A) with a solid content of 40%. The results are shown in Table 1.

[0133] [Example 8] 85.4 g of cyclopentanol as solvent (D) was placed in a flask equipped with a stirring device, a dropping funnel, a condenser, a thermometer, and a gas inlet tube, and the mixture was stirred while purging with nitrogen gas, and the temperature was raised to 98°C.

[0134] Next, a raw material monomer solution was prepared by mixing 114.0 g (50 mol%) of TIPA as monomer (ma-1), 30.8 g (50 mol%) of glycidyl methacrylate as monomer (ma-2), 144.7 g of cyclopentanol as solvent (D), and 8.7 g (6 parts by mass per 100 parts by mass of the total monomer components) of 2,2'-azobis(2-methylpropionic acid)dimethyl as polymerization initiator (i).

[0135] The entire volume of the prepared raw material monomer solution was added dropwise over 1 hour using a dropping funnel to solvent (D) in a flask under atmospheric pressure and nitrogen gas atmosphere. After the addition was complete, the solution in the flask was stirred and polymerized at 98°C for 5 hours to obtain a liquid containing (meth)acrylic resin precursor (PA1) and solvent (D).

[0136] To a liquid containing a (meth)acrylic resin precursor (PA1) and solvent (D) in a flask at atmospheric pressure under a nitrogen gas atmosphere, 0.5 g of hydroquinone monomethyl ether as a polymerization inhibitor (j) (0.3 parts by mass per 100 parts by mass of the total monomer component and ethylenically unsaturated compound (e)), 0.5 g of triphenylphosphine as a catalyst (k) (0.3 parts by mass per 100 parts by mass of the total monomer component and ethylenically unsaturated compound (e)), and 30.2 g of acrylic acid as ethylenically unsaturated compound (e) were added, and the reaction was continued at 110°C for 10 hours with stirring.

[0137] Next, 16.5 g of tetrahydrophthalic anhydride was added to the flask as polybasic acid anhydride (h), and the mixture was reacted at 110°C for 2 hours to obtain a liquid containing (meth)acrylic resin (A) and solvent (D). 69.9 g of cyclopentanol was added to this liquid to prepare a solution of (meth)acrylic resin (A) with a solid content of 40%. The results are shown in Table 1.

[0138] [Comparative Example 4] A liquid containing (meth)acrylic resin (cA) and solvent (D) was obtained using the same procedure as in Example 8, except that the types and compositions of the monomer, ethylenically unsaturated compound (e), and polybasic acid anhydride (h) were changed as shown in Table 2. The results are shown in Table 2.

[0139] [Example 9] 105.3 g of cyclopentanol as solvent (D) was placed in a flask equipped with a stirring device, a dropping funnel, a condenser, a thermometer, and a gas inlet tube, and the mixture was stirred while purging with nitrogen gas, and the temperature was raised to 98°C.

[0140] Next, a raw material monomer solution was prepared by mixing 160.9 g (60 mol%) of TIPA as monomer (ma-1), 17.5 g (40 mol%) of methacrylic acid as monomer (ma-3), 178.4 g of cyclopentanol as solvent (D), and 10.7 g (6 parts by mass per 100 parts by mass of the total monomer components) of 2,2'-azobis(2-methylpropionic acid)dimethyl as polymerization initiator (i).

[0141] The entire volume of the prepared raw material monomer solution was added dropwise over 1 hour using a dropping funnel to solvent (D) in a flask under atmospheric pressure and nitrogen gas atmosphere. After the addition was complete, the solution in the flask was stirred and polymerized at 98°C for 5 hours to obtain a liquid containing (meth)acrylic resin precursor (PA2) and solvent (D).

[0142] In a flask at atmospheric pressure under a nitrogen atmosphere, a liquid containing (meth)acrylic resin precursor (PA2) and solvent (D) was added. 0.6 g of hydroquinone monomethyl ether as a polymerization inhibitor (j) (0.3 parts by mass per 100 parts by mass of the total monomer component and ethylenically unsaturated compound (e)), 0.6 g of triphenylphosphine as a catalyst (k) (0.3 parts by mass per 100 parts by mass of the total monomer component and ethylenically unsaturated compound (e)), and 10.9 g of glycidyl methacrylate as ethylenically unsaturated compound (f) were added. The mixture was reacted at 110°C for 5 hours with stirring to obtain a liquid containing (meth)acrylic resin (A) and solvent (D). 16.3 g of cyclopentanol was added to this liquid to prepare a solution of (meth)acrylic resin (A) with a solid content of 40%. The results are shown in Table 1.

[0143] [Comparative Example 5] A liquid containing (meth)acrylic resin (cA) and solvent (D) was obtained using the same procedure as in Example 9, except that the type and composition of the monomer and ethylenically unsaturated compound (f) were changed as shown in Table 2. The results are shown in Table 2.

[0144]

[0145]

[0146] [Examples 11-20, Comparative Examples 6-10] The (meth)acrylic resin (A) from Examples 1-10, or the (meth)acrylic resin (cA) from Comparative Examples 1-5, dipentaerythritol hexaacrylate as a reactive diluent (B), Irgacure® OXE02 as a photopolymerization initiator (C), propylene glycol monomethyl ether acetate as a solvent (D), and Karenz® MT NR1 as a curing aid were mixed in the compositions shown in Table 3 (unit: parts by mass) to prepare the photosensitive resin compositions of Examples 11-20 and Comparative Examples 6-10. The amounts of (meth)acrylic resin (A) or (cA) shown in Table 3 do not include the amount of solvent (D). The amount of solvent (D) shown in Table 3 is the sum of the amount of solvent (D) contained in the liquid containing (meth)acrylic resin (A) or (cA) obtained in Examples 1 to 10 or Comparative Examples 1 to 5, and the amount of solvent (D) added during the preparation of the photosensitive resin composition.

[0147] (1) Evaluation of transmittance Each photosensitive resin composition was spin-coated onto a 5 cm square glass substrate (alkali-free glass substrate) so that the average thickness of the cured resin film was 2.0 μm. The solvent was then evaporated by heating at 100°C for 3 minutes to form a coated film. Next, the entire coated film was exposed to light (wavelength 365 nm, exposure dose 200 mJ / cm²). ２ After photocuring, a resin-cured film was obtained by baking at 230°C for 30 minutes.

[0148] Measurements were taken using a UV-1650PC spectrophotometer (Shimadzu Corporation). Measurement target: The above-mentioned cured resin film. Measurement conditions: Measurement wavelength (wavelength range) 380-780 nm.

[0149] (2) Each pencil hardness photosensitive resin composition was spin-coated onto a 5 cm square glass substrate (alkali-free glass substrate), and then heated at 70°C for 3 minutes to evaporate the solvent and form a coating film. Next, the entire coating film was exposed to light (wavelength 365 nm, exposure dose 200 mJ / cm²). ２ After photocuring, the glass substrate having the photocured coating film was left to stand in an 85°C dryer for 30 minutes to heat-cur the coating film (post-baking step), thereby obtaining a resin-cured film with a thickness of 2.5 μm.

[0150] The pencil hardness of the cured resin film was measured using a pencil hardness tester (No. 553-M, manufactured by Yasuda Seiki Seisakusho) in accordance with JIS K 5600-5-4:1999.

[0151] (3) Refractive index: The refractive index refers to the refractive index of the (meth)acrylic resin (A) or (cA) measured using a refractometer. The refractive index of a resin composition (sample) containing (meth)acrylic resin (A) or (cA) and solvent (D) is measured under the following conditions, and then the refractive index of solvent (D) is measured under the following conditions. Next, the content (solids) of (meth)acrylic resin (A) or (cA) contained in the sample is measured in accordance with JIS K 6901:2008 5.11, and the refractive index of the (meth)acrylic resin (A) or (cA) alone contained in the sample is calculated using the following formula. Measuring instrument: J-357 Automatic Refractometer (Rudolph Research Analytical) Measurement wavelength: 589 nm Measurement temperature: 25°C Refractive index of (meth)acrylic resin (A) or (cA) alone = (Refractive index of sample - Refractive index of solvent (D)) ÷ Solids content × 100 + Refractive index of solvent (D)

[0152] (4) Overall Evaluation The photosensitive resin compositions were comprehensively evaluated according to the following criteria: A: Pencil hardness of H or higher and refractive index of 1.55 or higher B: Pencil hardness of less than H or refractive index of less than 1.55

[0153] The results are shown in Table 3.

[0154]

Claims

1. Structural unit (a-1) represented by formula (1) having a halogen-substituted phenyl group: (In the formula, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom, Y is a single bond or a divalent organic group, and R １ , R ２ , R ３ , R ４ , and R ５ are each independently H, Br, or I, provided that at least one of R １ , R ２ , R ３ , R ４ , and R ５ is Br or I.) and a structural unit (X) having a curable group. A (meth)acrylic resin having these.

2. The (meth)acrylic resin according to claim 1, wherein the halogen-substituted phenyl group equivalent is 350 to 2000 g / mol.

3. The (meth)acrylic resin according to claim 1 or 2, wherein the curable group of the structural unit (X) is a thermosetting group.

4. In equation (1), R １ , R ３ , and R ５ I is R ２ , and R ４ is H, or R １ , R ２ , R ３ , R ４ , and R ５ The (meth)acrylic resin according to claim 1 or 2, wherein is Br.

5. The (meth)acrylic resin according to claim 1 or 2, wherein the structural unit (X) includes a structural unit (a-2) having an epoxy group, and the epoxy equivalent is 100 to 10,000 g / mol.

6. The (meth)acrylic resin according to claim 1 or 2, wherein the structural unit (X) includes a structural unit (a-2) having an epoxy group, and the structural unit (a-1) is present in an amount of 10 to 95 mol% and the structural unit (a-2) is present in an amount of 5 to 90 mol% based on 100 mol% of the total structural units.

7. The (meth)acrylic resin according to claim 6, wherein the curable groups of the structural unit (X) are thermosetting groups and photocurable groups, and the (meth)acrylic resin has a structure in which an ethylenically unsaturated compound (e) having a group that is reactive with the epoxy group is attached to at least a portion of the epoxy group of the structural unit (a-2).

8. The (meth)acrylic resin according to claim 7, wherein the (meth)acrylic resin has a structure in which a polybasic acid or polybasic anhydride (h) is added to at least a portion of the hydroxyl group formed by ring-opening of the epoxy group of the structural unit (a-2).

9. The (meth)acrylic resin according to claim 1 or 2, wherein the curable group of the structural unit (X) is a photocurable group.

10. The (meth)acrylic resin according to claim 1 or 2, wherein the structural unit (X) includes a structural unit having an ethylenically unsaturated group, and the equivalent amount of the ethylenically unsaturated group is 100 to 10,000 g / mol.

11. The (meth)acrylic resin according to claim 10, wherein the structural unit (X) includes a structural unit having an ethylenically unsaturated group, the structural unit (a-1) is present in an amount of 10 to 95 mol%, the (meth)acrylic resin has a structure in which an ethylenically unsaturated compound (f) having a group that reacts with the acid group is added to a part of the acid group of a (meth)acrylic resin precursor (PA2) having 5 to 90 mol% of a structural unit (a-3) having an acid group, the amount of the ethylenically unsaturated compound (f) is 1 to 70 mol per 100 mol of the structural unit (a-3) of the (meth)acrylic resin precursor (PA2), and the amount of the ethylenically unsaturated compound (f) added is 5 to 100 mol per 100 mol of the structural unit (a-3) of the (meth)acrylic resin precursor (PA2).

12. A photosensitive resin composition comprising (meth)acrylic resin (A), a reactive diluent (B), a photopolymerization initiator (C), and a solvent (D), wherein the (meth)acrylic resin (A) is the (meth)acrylic resin described in claim 1 or 2.

13. The photosensitive resin composition according to claim 12, wherein, with respect to 100% by mass of the total of the (meth)acrylic resin (A) and the reactive diluent (B), the content of the (meth)acrylic resin (A) is 10 to 99% by mass, the content of the reactive diluent (B) is 1 to 90% by mass, the content of the photopolymerization initiator (C) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of the (meth)acrylic resin (A) and the reactive diluent (B), and the content of the solvent (D) is 30 to 1000 parts by mass with respect to 100 parts by mass of the total of the components excluding the solvent (D).

14. A resin-cured film comprising a cured product of the photosensitive resin composition according to claim 12.

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