Radically polymerizable polymer and photosensitive resin composition

Abstract

To provide a radically polymerizable polymer capable of yielding a photosensitive resin composition with low viscosity and superior temporal stability even when fine particles with small diameters are incorporated into the photosensitive resin composition.SOLUTION: A radically polymerizable polymer according to the present invention is a radically polymerizable polymer including a structural unit derived from an unsaturated monomer having an acid group and a structural unit having a cyclic structure in the main chain, including a polymerizable double bond in a side chain, and exhibiting a weight average molecular weight of 18000 or less, and satisfies either: that a proportion of a structural unit derived from an acrylic monomer is 30 to 90 mol% based on 100 mol% of all structural units constituting the main chain of the radically polymerizable polymer; or a molar ratio of the structural unit derived from an acrylic monomer to the structural unit derived from a methacrylic monomer (acrylic monomer-derived structural unit / methacrylic monomer-derived structural unit) in all structural units constituting the main chain of the radically polymerizable polymer is from 0.5 to 10.5.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a radically polymerizable polymer and a photosensitive resin composition containing the radically polymerizable polymer. [Background technology]

[0002] Curable resin compositions that can be cured by heat or active energy rays have been studied for various applications, such as color filters used in liquid crystal displays and solid-state imaging devices, inks, printing plates, printed wiring boards, semiconductor devices, photoresists, and other various optical members and electric and electronic devices, and excellent curable resin compositions have been developed according to the properties required for each application.

[0003] Patent Document 1 describes a radiation-sensitive resin composition containing an alkali-soluble resin, a 1,2-quinonediazide compound, and a radical scavenger, and discloses that the alkali-soluble resin is a copolymer obtained by copolymerizing an unsaturated carboxylic acid, an unsaturated compound containing an epoxy group, a maleimide compound, and the like. Patent Document 2 discloses an active energy ray-curable photosensitive resin composition containing a (meth)acrylate having a cyclic ether skeleton, an alkyl (meth)acrylate in which the alkyl group has 1 to 24 carbon atoms, a (meth)acrylic resin which is a copolymer of at least two kinds of radically polymerizable monomers, and a polymerization initiator. Patent Document 3 discloses a radical polymerizable polymer which is a polymer having a constitutional unit derived from an unsaturated monomer having an acid group, a constitutional unit derived from an unsaturated monomer having a cyclic ether structure of five or more members, a constitutional unit having a ring structure in the main chain, and a polymer having a polymerizable double bond in the side chain, and which has a weight average molecular weight of 19,000 or less, and a photosensitive resin composition containing the same. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2011 / 046230 [Patent Document 2] JP 2013-36024 A [Patent Document 3] JP 2023-057930 A Summary of the Invention [Problem to be solved by the invention]

[0005] Photosensitive resin compositions generally contain inorganic fine particles, but the present inventors have studied and found that when small particles having a particle size of 100 nm or less are blended into a photosensitive resin composition, the transparency of the cured product is good, but the initial viscosity of the photosensitive resin composition increases and the stability over time after storage is poor, resulting in poor handling. On the other hand, when relatively large particles having a particle size of about 600 nm are blended into a photosensitive resin composition, the initial viscosity of the photosensitive resin composition decreases, and the stability over time after storage is good, but the transparency deteriorates, making it difficult to apply to optical components, electric and electronic devices, etc. Therefore, the present inventors have repeatedly studied whether it is possible to provide a polymer that can provide a photosensitive resin composition with low viscosity and excellent stability over time, even when small particles having a particle size of 100 nm or less are blended into the photosensitive resin composition to improve the transparency of the cured product. However, even when the resins and radical polymerizable polymers described in Patent Documents 1 to 3 are used, there is still room for improvement in obtaining a photosensitive resin composition with low viscosity and excellent stability over time.

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a radically polymerizable polymer that can give a photosensitive resin composition that has low viscosity and excellent stability over time, even when small particles having a particle size of 100 nm or less are blended into the photosensitive resin composition. [Means for solving the problem]

[0007] The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a radically polymerizable polymer having constitutional units derived from an unsaturated monomer having an acid group and constitutional units having a ring structure in the main chain, having a polymerizable double bond in a side chain, and having a weight-average molecular weight of a predetermined amount or less, wherein a ratio of constitutional units derived from an acrylic monomer in 100 mol % of all constitutional units constituting the main chain of the radically polymerizable polymer satisfies 30 to 90 mol %, or a ratio of constitutional units derived from an acrylic monomer to constitutional units derived from a methacrylic monomer in all constitutional units constituting the main chain of the radically polymerizable polymer (constituent units derived from an acrylic monomer / constituent units derived from a methacrylic monomer) satisfies a molar ratio of 0.5 to 10.5, even when small particles are blended in the photosensitive resin composition, thereby completing the present invention.

[0008] According to the present inventor's investigation, it is believed that the viscosity of the photosensitive resin composition increases due to the interaction between particles, since the surface area of ​​particles with a small particle size is large relative to the particle size. It is presumed that the radical polymerizable polymer acts on the particle surface by using a structural unit having a ring structure in the main chain and a polymerizable double bond in the side chain as the base resin of the photosensitive resin composition, and by increasing the proportion of structural units derived from acrylic monomers in the main chain in particular, the radical polymerizable polymer acts on the particle surface, making it possible to reduce the viscosity of the photosensitive resin composition and improve its stability over time. For these reasons, it is believed that the resins of Patent Documents 1 and 2 that do not have polymerizable double bonds in the side chain and the radical polymerizable polymer of Patent Document 3 that has a low proportion of structural units derived from acrylic monomers in the main chain could not obtain a photosensitive resin composition with low viscosity and excellent stability over time.

[0009] That is, the present invention is defined by the following configuration requirements. [1] A radical polymerizable polymer having a structural unit derived from an unsaturated monomer having an acid group and a structural unit having a ring structure in the main chain, and having a polymerizable double bond in the side chain, the proportion of structural units derived from acrylic monomers is 30 to 90 mol % in 100 mol % of all structural units constituting the main chain of the radical polymerizable polymer, A radically polymerizable polymer having a weight average molecular weight of 18,000 or less. [2] A radical polymerizable polymer having a constitutional unit derived from an unsaturated monomer having an acid group and a constitutional unit having a ring structure in the main chain, and having a polymerizable double bond in the side chain, In all the constituent units constituting the main chain of the radical polymerizable polymer, the ratio of the constituent units derived from acrylic monomers to the constituent units derived from methacrylic monomers (constituent units derived from acrylic monomers / constituent units derived from methacrylic monomers) is 0.5 to 10.5 in terms of molar ratio; A radically polymerizable polymer having a weight average molecular weight of 18,000 or less. [3] The radical polymerizable polymer according to [1] or [2], wherein the structural unit having a ring structure in the main chain is a structural unit derived from an N-substituted maleimide monomer. [4] The radical polymerizable polymer according to any one of [1] to [3], further comprising a structural unit derived from an unsaturated monomer having a cyclic ether structure with five or more members. [5] The radical polymerizable polymer according to any one of [1] to [4], further comprising a structural unit derived from an unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group. [6] The radical polymerizable polymer according to any one of [1] to [5], further comprising a structural unit derived from an unsaturated monomer having a cyclohexyl group. [7] The radical polymerizable polymer according to any one of [1] to [6], which has an acid value of 30 to 200 mg KOH / g. [8] The radically polymerizable polymer according to any one of [1] to [7], having a double bond equivalent of 330 to 1600 g / mol. [9] A photosensitive resin composition comprising the radical polymerizable polymer according to any one of [1] to [8], a polyfunctional monomer, a polymerization initiator, inorganic fine particles, and a solvent.

[10] The inorganic fine particles include inorganic fine particles (P1) having an average particle diameter (d50, by number) of 100 nm or less, The photosensitive resin composition according to [9], wherein the content of the inorganic fine particles (P1) is 5 to 60 mass % in 100 mass % of the photosensitive resin composition. Effect of the Invention

[0010] The radical polymerizable polymer of the present invention can form a photosensitive resin composition having low viscosity and excellent stability over time even when particles having a small particle size are blended into the photosensitive resin composition. Therefore, the radical polymerizable polymer and the photosensitive resin composition of the present invention can be suitably used in applications such as resist materials, various coating agents, paints, etc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. It should be noted that a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[0012] In this specification, the numerical range "Min to Max" means a range equal to or greater than the minimum value Min and equal to or less than the maximum value Max. Furthermore, when suitable numerical values ​​are described stepwise for the upper and lower limit values, a suitable numerical range is also a suitable numerical range obtained by appropriately combining the upper and lower limit values ​​described separately.

[0013] In this specification, "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid", and "(meth)acrylate" means "acrylate and / or methacrylate".

[0014] In this specification, the term "(meth)acrylic monomer" refers to a monomer having an acryloyl group (HC=CH-C(=O)-) and / or a methacryloyl group (HC=C(CH)-C(=O)-), such as acrylic acid (i.e., vinyl carboxylic acid) or its ester, methacrylic acid (i.e., α-methyl carboxylic acid) or its ester, etc.

[0015] In this specification, the term "vinyl monomer" refers to a monomer other than a (meth)acrylic monomer having a vinyl group. For example, crotonic acid (i.e., β-methyl carboxylic acid) corresponds to a methyl-substituted vinylcarbonyl group like a methacryloyl group, but does not correspond to an acryloyl group or a methacryloyl group, and is therefore classified as a vinyl monomer.

[0016] In this specification, the term "structural unit derived from an unsaturated monomer" refers to, for example, a structure in which a polymerizable double bond of an unsaturated monomer is opened by a polymerization reaction. The structure in which a polymerizable double bond is opened refers, for example, to a structure in which a carbon-carbon double bond (C=C) becomes a single bond (-CC-). The unsaturated monomer is not particularly limited as long as it is a monomer having a polymerizable double bond, and examples of the unsaturated monomer include (meth)acrylic monomers and vinyl monomers.

[0017] Each of the structural units shown below may be used alone or in combination of two or more kinds.

[0018] 1. Radical polymerizable polymers The radical polymerizable polymer of the present invention is a radical polymerizable polymer having a constitutional unit derived from an unsaturated monomer having an acid group and a constitutional unit having a ring structure in the main chain, and having a polymerizable double bond in the side chain, and is characterized in that the proportion of constitutional units derived from an acrylic monomer is 30 to 90 mol% in 100 mol% of all constitutional units constituting the main chain of the radical polymerizable polymer, and the weight average molecular weight is 18000 or less. (a) The proportion of constitutional units derived from an acrylic monomer is 30 mol% or more, (b) the radical polymerizable polymer has constitutional units derived from an unsaturated monomer having an acid group and a constitutional unit having a ring structure in the main chain, and has a polymerizable double bond in the side chain, and (c) the weight average molecular weight is 18000 or less, which greatly contribute to the reduction of viscosity of the photosensitive resin composition and the improvement of stability over time. Although the reason is unclear, it is considered that the radical polymerizable polymer satisfying (a) to (c) acts on the particle surface and affects the dispersibility of the particles.

[0019] In the total 100 mol% of the structural units constituting the main chain of the radical polymerizable polymer, the proportion of the structural units derived from the acrylic monomer is preferably 35 to 80 mol%, more preferably 40 to 75 mol%, and even more preferably 45 to 70 mol%. Within the above range, a photosensitive resin composition having low viscosity and excellent stability over time is easily obtained. In addition, the higher the proportion of the structural units derived from the acrylic monomer, the more desirable.

[0020] In this specification, the constitutional unit derived from a (meth)acrylic monomer more specifically means a constitutional unit derived from an unsaturated monomer having a (meth)acryloyl group. The ratio of the constitutional unit derived from a (meth)acrylic monomer to all constitutional units constituting the main chain is determined, for example, from the amount of monomer charged, various analyses such as NMR, etc.

[0021] The radical polymerizable polymer of the present invention is a radical polymerizable polymer having a constitutional unit derived from an unsaturated monomer having an acid group and a constitutional unit having a ring structure in the main chain, and having a polymerizable double bond in the side chain, and is characterized in that, in all constitutional units constituting the main chain of the radical polymerizable polymer, the ratio of constitutional units derived from an acrylic monomer to constitutional units derived from a methacrylic monomer (constitutional units derived from an acrylic monomer / constitutional units derived from a methacrylic monomer) is 0.5 to 10.5 in molar ratio, and the weight average molecular weight is 18000 or less. As in the above, (d) constitutional units derived from an acrylic monomer / constitutional units derived from a methacrylic monomer being 0.5 or more, (e) the radical polymerizable polymer having constitutional units derived from an unsaturated monomer having an acid group and constitutional units having a ring structure in the main chain, and having a polymerizable double bond in the side chain, and (f) the weight average molecular weight being 18000 or less greatly contribute to lowering the viscosity of the photosensitive resin composition and improving the stability over time. It is believed that the radically polymerizable polymer satisfying (d) to (f) acts on the particle surface and affects the dispersibility of the particles.

[0022] The ratio of the constitutional units derived from the acrylic monomer to the constitutional units derived from the methacrylic monomer (constitutional units derived from the acrylic monomer / constitutional units derived from the methacrylic monomer) is preferably 0.7 to 7, more preferably 0.9 to 5, and even more preferably 1.1 to 3, in terms of molar ratio. Within this range, a photosensitive resin composition having low viscosity and excellent stability over time is easily obtained. In addition, the higher the ratio, the more desirable it is.

[0023] In the total 100 mol % of all structural units constituting the main chain of the radical polymerizable polymer, the proportion of structural units derived from methacrylic monomers is preferably 5 to 60 mol %, more preferably 10 to 50 mol %, and even more preferably 20 to 40 mol %. Within the above range, it is possible to provide a cured product with improved hardness, transparency, and adhesion.

[0024] The radical polymerizable polymer of the present invention has constitutional units derived from acrylic monomers and constitutional units derived from methacrylic monomers, and the total of constitutional units derived from acrylic monomers and constitutional units derived from methacrylic monomers is preferably 35 to 95 mol%, more preferably 40 to 94 mol%, even more preferably 50 to 93 mol%, and even more preferably 70 to 92 mol% in 100 mol% of all constitutional units constituting the main chain of the radical polymerizable polymer. If it is within the above range, a photosensitive resin composition having low viscosity and excellent stability over time can be easily obtained.

[0025] 1.1 Structural units derived from unsaturated monomers having acid groups The structural unit derived from the unsaturated monomer having an acid group is used to improve the alkaline developability of the resin. The acid group is not particularly limited as long as it is a functional group that exhibits acidity in water, and examples thereof include a carboxy group, a sulfonic acid group, and a phosphoric acid group, and the carboxy group is preferred.

[0026] The unsaturated monomer is not particularly limited as long as it is a monomer having a polymerizable double bond, and includes (meth)acrylic monomers, vinyl monomers, etc., and (meth)acrylic monomers are preferred, and acrylic monomers are more preferred. If it is an acrylic monomer, it is easy to make the ratio of the structural unit derived from the acrylic monomer and the ratio of the structural unit derived from the acrylic monomer / the structural unit derived from the methacrylic monomer within a desired range.

[0027] As the unsaturated monomer having an acid group, a (meth)acrylic monomer having a carboxy group, a vinyl monomer having a carboxy group, etc. are preferable, and a (meth)acrylic monomer having a carboxy group is more preferable. Examples of the (meth)acrylic monomer having a carboxy group include (meth)acrylic acid, and compounds in which a polycarboxylic acid is further esterified to an ester of (meth)acrylic acid and a polyol. The polyol may be a mono- or poly-C such as ethylene glycol, diethylene glycol, propanediol, or dipropanediol. 2-4 The polycarboxylic acids include alkanediols, and ethylene glycol is preferred. The polycarboxylic acids include C carboxylic acids such as oxalic acid, malonic acid, succinic acid, and glutaric acid. 1-10 Alkanedicarboxylic acids; hexahydrophthalic acid, etc. 6-10 Cycloalkanedicarboxylic acids; C such as phthalic acid 6-10 Examples of the compound in which a polyvalent carboxylic acid is further ester-bonded to an ester of (meth)acrylic acid and a polyol include 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, and 2-(meth)acryloyloxyethyl phthalic acid. Examples of the vinyl monomer having a carboxy group include vinyl monocarboxylic acids such as crotonic acid; vinyl dicarboxylic acids such as itaconic acid, maleic acid, and fumaric acid; and the like.

[0028] As the (meth)acrylic monomer having a carboxy group, (meth)acrylic acid is preferred, and acrylic acid is particularly preferred.

[0029] In addition, a structural unit obtained by reacting a structural unit derived from an unsaturated monomer having an acid group with a compound containing a reactive group (such as an epoxy group) and a polymerizable unsaturated double bond, which will be described later, and then reacting the resulting hydroxy group with a polyvalent carboxylic acid also has an acid group. However, since such a structural unit contains an unsaturated double bond, in the present invention, it is not included in the structural unit derived from an unsaturated monomer having an acid group.

[0030] The content of the structural unit derived from the unsaturated monomer having an acid group is preferably 0.5 to 50 mass%, more preferably 1 to 45 mass%, even more preferably 2 to 40 mass%, and even more preferably 5 to 35 mass% in 100 mass% of all structural units constituting the main chain of the radical polymerizable polymer. When the content of the structural unit derived from the unsaturated monomer having an acid group (particularly, a carboxy group) is within the above range, the viscosity of the obtained polymer does not become too high, and the handleability becomes good. Furthermore, the developability with an alkaline substance becomes better.

[0031] 1.2 Building blocks with ring structures in the main chain The structural unit having a ring structure in the main chain is a structural unit derived from an unsaturated monomer (including an unsaturated monomer having a ring structure in the main chain) capable of introducing a ring structure into the main chain of a polymer, and is preferably, for example, a structural unit derived from an N-substituted maleimide monomer, a dialkyl-2,2'-(oxydimethylene)diacrylate monomer (also called an ether dimer), or an α-(unsaturated alkoxyalkyl)acrylate monomer (preferably an alkyl-(α-allyloxymethyl)acrylate monomer). The structural unit having a ring structure in the main chain makes the radical polymerizable polymer into an alkali-soluble resin capable of providing a cured product having excellent heat resistance, hardness, inorganic fine particle dispersibility, etc.

[0032] The structural unit derived from the N-substituted maleimide monomer is useful for reducing the viscosity of the polymer, and can improve the hardness, transparency, and adhesion of the cured product. The N-substituted maleimide monomer is a monomer having a double bond-containing ring structure in the molecule, and examples thereof include: N-alkylmaleimides such as N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, Nt-butylmaleimide, and N-laurylmaleimide (preferably, N 1-12 alkylmaleimides); N-cycloalkylmaleimides such as N-cyclopropylmaleimide, N-cyclobutylmaleimide, N-cyclopentylmaleimide, and N-cyclohexylmaleimide (preferably, NC 3-20 cycloalkylmaleimides); N-arylmaleimides such as N-phenylmaleimide (preferably N-C 6-12 arylmaleimides); N-Aralkylmaleimides such as N-benzylmaleimide (preferably N-C 7-12 aralkylmaleimides); As the N-substituted maleimide monomer, N-cycloalkylmaleimide, N-arylmaleimide, and N-aralkylmaleimide are preferred in terms of excellent adhesion and dispersibility, and NC 6-10 Cycloalkylmaleimide, N-phenylmaleimide, and N-benzylmaleimide are more preferred, and N-phenylmaleimide and N-benzylmaleimide are even more preferred. In terms of excellent transparency, N-cycloalkylmaleimide, N-arylmaleimide, and N-aralkylmaleimide are preferred, and NC 6-10 Cycloalkylmaleimides, N-phenylmaleimide, N-benzylmaleimide are more preferred, and N-cyclohexylmaleimide is even more preferred.

[0033] The N-alkylmaleimide and N-cycloalkylmaleimide may have a substituent, and examples of the substituent include a phenyl group, a benzyl group, and a hydroxy group. The N-arylmaleimide and N-aralkylmaleimide may have a substituent, and examples of the substituent include an alkyl group, a nitro group, a hydroxy group, an alkoxy group, a carboxy group, and a halogeno group. Specifically, for example, N-benzylmaleimides having a substituent include alkyl-substituted benzylmaleimides such as p-methylbenzylmaleimide and p-butylbenzylmaleimide, phenolic hydroxyl group-substituted benzylmaleimides such as p-hydroxybenzylmaleimide, halogen-substituted benzylmaleimides such as o-chlorobenzylmaleimide, o-dichlorobenzylmaleimide and p-dichlorobenzylmaleimide, etc. Furthermore, N-phenylmaleimides having a substituent include alkyl-substituted phenylmaleimides such as p-methylphenylmaleimide and p-butylphenylmaleimide, phenolic hydroxyl group-substituted phenylmaleimides such as p-hydroxyphenylmaleimide, halogen-substituted phenylmaleimides such as o-chlorophenylmaleimide, o-dichlorophenylmaleimide and p-dichlorophenylmaleimide, etc.

[0034] Dialkyl-2,2'-(oxydimethylene)diacrylate monomers and α-(unsaturated alkoxyalkyl)acrylate monomers are monomers that undergo cyclic polymerization to form polymers having a ring structure in the main chain. In the present invention, the constitutional units derived from dialkyl-2,2'-(oxydimethylene)diacrylate monomers and α-(unsaturated alkoxyalkyl)acrylate monomers are not included in the constitutional units derived from unsaturated monomers having a cyclic ether structure of 5 or more members.

[0035] As the dialkyl-2,2'-(oxydimethylene)diacrylate monomer, it is preferable to use, for example, dimethyl-2,2'-[oxybis(methylene)]bis-2-propenoate, etc., from the viewpoints of little coloration, dispersibility, and industrial availability.

[0036] As the α-(unsaturated alkoxyalkyl)acrylate monomer, for example, an alkyl-(α-allyloxymethyl)acrylate monomer, an alkyl-(α-methallyloxymethyl)acrylate monomer, or the like is preferable. Specifically, α-allyloxymethylacrylic acid, methyl α-allyloxymethylacrylic acid, ethyl α-allyloxymethylacrylic acid, n-propyl α-allyloxymethylacrylic acid, i-propyl α-allyloxymethylacrylic acid, n-butyl α-allyloxymethylacrylic acid, s-butyl α-allyloxymethylacrylic acid, t-butyl α-allyloxymethylacrylic acid, n-amyl α-allyloxymethylacrylic acid, s-amyl α-allyloxymethylacrylic acid, t-amyl α-allyloxymethylacrylic acid, neopentyl α-allyloxymethylacrylic acid, n-hexyl α-allyloxymethylacrylic acid, s-hexyl α-allyloxymethylacrylic acid, n-heptyl α-allyloxymethylacrylic acid, n-octyl α-allyloxymethylacrylic acid, s-octyl α-allyloxymethylacrylic acid, t-octyl α-allyloxymethylacrylic acid, 2-ethyl α-allyloxymethylacrylic acid, Preferred are chain-like saturated hydrocarbon group-containing α-(allyloxymethyl)acrylates such as ethylhexyl, capryl α-allyloxymethylacrylate, nonyl α-allyloxymethylacrylate, decyl α-allyloxymethylacrylate, undecyl α-allyloxymethylacrylate, lauryl α-allyloxymethylacrylate, tridecyl α-allyloxymethylacrylate, myristyl α-allyloxymethylacrylate, pentadecyl α-allyloxymethylacrylate, cetyl α-allyloxymethylacrylate, heptadecyl α-allyloxymethylacrylate, stearyl α-allyloxymethylacrylate, nonadecyl α-allyloxymethylacrylate, eicosyl α-allyloxymethylacrylate, ceryl α-allyloxymethylacrylate, and melissyl α-allyloxymethylacrylate, and more preferred are methyl α-allyloxymethylacrylate (also referred to as α-(allyloxymethyl)methylacrylate).

[0037] The content of the structural unit having a ring structure in the main chain is preferably 1.5 to 60 mass% of the total structural units constituting the main chain of the radical polymerizable polymer, more preferably 3 mass% or more, even more preferably 5 mass% or more, even more preferably 7 mass% or more, and even more preferably 50 mass% or less, even more preferably 35 mass% or less, and even more preferably 25 mass% or less. When the content of the structural unit having a ring structure in the main chain is within the above range, the viscosity of the radical polymerizable polymer and the photosensitive resin composition containing the polymer is low, and the handleability (applicability) is good, and it is possible to give a cured product with improved hardness, transparency, and adhesion. More preferably, when the content of the structural unit having a ring structure in the main chain is within the above range, it becomes a radical polymerizable polymer with excellent heat resistance, and a photosensitive resin composition containing the polymer, and it is possible to give a cured product with excellent heat resistance, and the dispersibility of inorganic fine particles is improved in the photosensitive resin composition.

[0038] 1.3 Structural units derived from unsaturated monomers having a cyclic ether structure with five or more members The radical polymerizable polymer of the present invention may have a constitutional unit derived from an unsaturated monomer having a cyclic ether structure of 5 or more members. By having a constitutional unit derived from an unsaturated monomer having a cyclic ether structure of 5 or more members, the viscosity can be further reduced and the coatability can be further improved.

[0039] The cyclic ether structure contained in the unsaturated monomer having a cyclic ether structure of 5 or more members is not particularly limited as long as it is 5 or more members, and may be a monocyclic ring, a polycyclic ring, or a condensed ring. The unsaturated monomer having a cyclic ether structure of 5 or more members may have one or two or more cyclic ether structures of 5 or more members. The cyclic ether structure is preferably a 5-10 membered ring, more preferably a 5-8 membered ring, even more preferably a 5-membered ring or a 6-membered ring, and even more preferably a furan ring, a tetrahydrofuran ring, a dioxolane ring, a pyran ring, a tetrahydropyran ring, or a dioxane ring, and even more preferably a tetrahydrofuran ring, a dioxolane ring, a tetrahydropyran ring, or a dioxane ring, and even more preferably a tetrahydrofuran ring or a dioxolane ring. The dioxolane ring is preferably a 1,3-dioxolane ring, and the dioxane ring is preferably a 1,3-dioxolane ring or a 1,4-dioxane ring, and more preferably a 1,3-dioxane ring. The cyclic ether structure may have a substituent such as an alkyl group (which may be linear, branched, or alicyclic) or an alkoxy group, and the substituent preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms.

[0040] The unsaturated monomer is not particularly limited as long as it is a monomer having a polymerizable double bond, and examples thereof include (meth)acrylic monomers and vinyl monomers, with (meth)acrylic monomers being preferred.

[0041] When the radical polymerizable polymer has a constitutional unit derived from an unsaturated monomer having a cyclic ether structure of 5 or more members, the radical polymerizable polymer preferably has a cyclic ether structure of 5 or more members in a side chain. In addition, the cyclic ether structure of 5 or more members may be bonded to the main chain via a chain-like linker (e.g., an organic group containing an ester bond) as necessary. For example, in the case of a (meth)acrylic monomer, -COO- containing a (meth)acryloyl group corresponds to the linker.

[0042] In the case of a (meth)acrylic monomer, the linker may be, for example, *-COO-**, *-COO-C 1-6 Alkylene group -**, *-COO-C1-6 Examples of the linker include an alkylene group -COO-**, and more preferably -COO-** and -COO-CH2-**. In the case of a vinyl monomer, examples of the linker include -O-, -OC 1-6 Alkylene group -**, *-OC 1-6 Examples include an alkylene group -COO-**, and -O- and *-O-CH2-** are preferred. In the above formula, * indicates the bonding position to the main chain, and ** indicates the bonding position to the cyclic ether structure.

[0043] As the unsaturated monomer having a cyclic ether structure of 5 or more members, a (meth)acrylic monomer having a tetrahydrofuran ring, a dioxolane ring, and / or a dioxane ring is preferable, and a (meth)acrylic monomer having a tetrahydrofuran ring and / or a dioxolane ring is more preferable.

[0044] Examples of (meth)acrylic monomers having a tetrahydrofuran ring structure include tetrahydrofurfuryl (meth)acrylate, γ-caprolactone modified tetrahydrofurfuryl (meth)acrylate, etc., and commercially available products such as Light Acrylate THF-A (manufactured by Kyoeisha Chemical Co., Ltd.) may be used. Examples of (meth)acrylic monomers having a dioxolane ring structure include (2-methyl-2-ethyl-1,3-dioxolane-4-yl)methyl (meth)acrylate, (2,2-cyclohexyl-1,3-dioxolane-4-yl)methyl (meth)acrylate, etc., and commercially available products such as MEDOL10 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) may be used. Examples of (meth)acrylic monomers having a dioxane ring structure include dioxane glycol di(meth)acrylate, (5-ethyl-1,3-dioxolane-5-yl)methyl (meth)acrylate, etc.

[0045] As the (meth)acrylic monomer having a cyclic ether structure having a 5 or more membered ring, a monomer having a glass transition temperature of a homopolymer of the monomer is preferably from -30 to 100°C, more preferably from -20 to 90°C.

[0046] The content of the structural unit derived from the unsaturated monomer having a cyclic ether structure of 5 or more members is preferably 0 to 60 mass%, more preferably 1 to 50 mass%, even more preferably 3 to 30 mass%, and even more preferably 5 to 20 mass% in 100 mass% of all structural units constituting the main chain of the radical polymerizable polymer. When the content of the structural unit derived from the unsaturated monomer having a cyclic ether structure of 5 or more members is within the above range, it is possible to provide a photosensitive resin composition having low viscosity and good stability over time. Furthermore, when the content is within the above range, the dispersibility of inorganic fine particles in the photosensitive resin composition is good.

[0047] 1.4 Structural units derived from unsaturated monomers having a hydroxyalkyl group containing a secondary hydroxyl group The radical polymerizable polymer of the present invention may have a structural unit derived from an unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group. A structural unit derived from an unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group is useful for providing a photosensitive resin composition having low viscosity and excellent stability over time. Incidentally, "containing a secondary hydroxyl group" means that the hydroxy group (alcoholic hydroxyl group) of the hydroxyalkyl group is bonded to a secondary carbon atom to which two carbon atoms are bonded. In addition, when the hydroxyalkyl group is directly bonded to a carbon atom of the main chain of the radical polymerizable polymer or a carbon atom of a carbonyl group, an amide group, or the like, it is sufficient that the secondary hydroxyl group is contained in the state in which these carbon atoms and the hydroxyalkyl group are bonded.

[0048] Examples of the alkyl group in the hydroxyalkyl group include linear or branched alkyl groups such as ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, and 2-methylhexyl group. An alkyl group having 2 to 10 carbon atoms is preferable, a linear alkyl group having 2 to 10 carbon atoms is more preferable, and a linear alkyl group having 3 to 6 carbon atoms is even more preferable.

[0049] Examples of hydroxyalkyl groups containing a secondary hydroxyl group include a 2-hydroxypropyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, a 2,3-dihydroxybutyl group, a 2-hydroxypentyl group, a 3-hydroxypentyl group, a 4-hydroxypentyl group, a 4-hydroxyhexyl group, and a 5-hydroxyhexyl group.

[0050] The unsaturated monomer is not particularly limited as long as it is a monomer having a polymerizable double bond, and examples thereof include (meth)acrylic monomers, vinyl monomers, etc., with (meth)acrylic monomers being preferred and methacrylic monomers being more preferred.

[0051] As the unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group, a (meth)acrylic monomer having a hydroxyalkyl group containing a secondary hydroxyl group is more preferred. As the (meth)acrylic monomer having a hydroxyalkyl group containing a secondary hydroxyl group, for example, (meth)acrylic monomers having one hydroxyl group such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-hydroxybutyl (meth)acrylate; (meth)acrylic monomers having two or more hydroxyl groups such as 2,3-dihydroxypropyl (meth)acrylate and 2,3-dihydroxybutyl (meth)acrylate can be mentioned, and (meth)acrylic monomers having one hydroxyl group are preferred, and methacrylic monomers having one hydroxyl group are more preferred.

[0052] The content ratio of the structural unit derived from the unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group is preferably 0 to 35 mass%, more preferably 0.5 to 30 mass%, even more preferably 1 to 25 mass%, and even more preferably 3 to 20 mass% in 100 mass% of all structural units constituting the main chain of the radical polymerizable polymer. When the content ratio of the structural unit derived from the unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group is within the above range, it is possible to provide a photosensitive resin composition having low viscosity and good stability over time. More preferably, when the content ratio is within the above range, it is possible to provide a radical polymerizable polymer having excellent heat resistance (particularly, thermal decomposition resistance) and a photosensitive resin composition containing the polymer, and to provide a cured product having excellent heat resistance.

[0053] 1.5 Structural units derived from unsaturated monomers having a cyclohexyl group The radical polymerizable polymer of the present invention may have a structural unit derived from an unsaturated monomer having a cyclohexyl group. The structural unit derived from an unsaturated monomer having a cyclohexyl group is useful for obtaining a photosensitive resin composition having low viscosity and good stability over time.

[0054] The unsaturated monomer having a cyclohexyl group is not particularly limited as long as it has at least one cyclohexyl group. The unsaturated monomer is not particularly limited as long as it is a monomer having a polymerizable double bond, and includes (meth)acrylic monomers, vinyl monomers, etc., and (meth)acrylic monomers are preferred.

[0055] When the radical polymerizable polymer has a structural unit derived from an unsaturated monomer having a cyclohexyl group, the radical polymerizable polymer preferably has a cyclohexyl group in a side chain. The cyclohexyl group is bonded to the main chain directly or, if necessary, via a chain-like linker (e.g., an organic group containing an ester bond). For example, in the case of a (meth)acrylic monomer, -COO- containing a (meth)acryloyl group corresponds to the linker.

[0056] In the case of a (meth)acrylic monomer, examples of the chain linker include *-COO-**, *-COO-C 1-6 Alkylene group -**, *-COO-C 1-6 Examples of the linker include an alkylene group -COO-**, and more preferably -COO-** and -COO-CH2-**. In the case of a vinyl monomer, examples of the linker include -O-, -OC 1-6 Alkylene group -**, *-OC 1-6 Examples include an alkylene group -COO-**, and -O- and *-O-CH2-** are preferred. In the above formula, * indicates the bonding position to the main chain, and ** indicates the bonding position to the cyclohexyl group.

[0057] As the unsaturated monomer having a cyclohexyl group, a (meth)acrylic monomer having a cyclohexyl group is preferable, and examples thereof include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, etc., with cyclohexyl (meth)acrylate being preferable and cyclohexyl methacrylate being more preferable.

[0058] The content ratio of the constitutional unit derived from the unsaturated monomer having a cyclohexyl group is preferably 0 to 50 mass% in 100 mass% of all constitutional units constituting the main chain of the radical polymerizable polymer, preferably 1 to 50 mass%, more preferably 3 to 45 mass%, even more preferably 5 to 40 mass%, and even more preferably 7 to 35 mass%. When the content ratio of the constitutional unit derived from the unsaturated monomer having a cyclohexyl group is within the above range, it is easy to give a photosensitive resin composition having low viscosity and good stability over time. More preferably, when the content ratio of the constitutional unit derived from the unsaturated monomer having a cyclohexyl group is within the above range, it becomes a radical polymerizable polymer having excellent heat resistance, and a photosensitive resin composition containing the polymer, and it is possible to give a cured product having excellent heat resistance, and the dispersibility of inorganic fine particles in the photosensitive resin composition is improved.

[0059] In the total 100% by mass of all structural units constituting the main chain of the radical polymerizable polymer, the total content ratio of structural units derived from unsaturated monomers having an acid group, structural units having a ring structure in the main chain, structural units derived from unsaturated monomers having a cyclic ether structure with a 5-membered ring or more, structural units derived from unsaturated monomers having a hydroxyalkyl group containing a secondary hydroxyl group, and structural units derived from unsaturated monomers having a cyclohexyl group is preferably 15% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, and even more preferably 80% by mass or more, and there is no particular upper limit, and it may be 100% by mass, and is preferably 95% by mass or less. If it is within the above range, it is easy to obtain a photosensitive resin composition with low viscosity and good stability over time.

[0060] 1.6 Building blocks derived from other copolymerizable monomers The radically polymerizable polymer of the present invention may have a constituent unit derived from a copolymerizable monomer other than the above-mentioned constituent unit derived from an unsaturated monomer having an acid group, the constituent unit having a ring structure in the main chain, the constituent unit derived from an unsaturated monomer having a cyclic ether structure with five or more members, the constituent unit derived from an unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group, and the constituent unit derived from an unsaturated monomer having a cyclohexyl group.

[0061] Examples of other copolymerizable monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl methyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, and the like. (Meth)acrylic acid esters such as thenyloxyethyl and dicyclopentanyl (meth)acrylate; primary hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; (meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N-methylol(meth)acrylamide; polystyrene, polymethyl(meth)acrylate, polyethylene oxide, polypropylene oxide, Examples of the vinyl ether include macromonomers having a (meth)acryloyl group at one end of a polymer molecular chain, such as polysiloxane, polycaprolactone, and polycaprolactam; conjugated dienes, such as 1,3-butadiene and isoprene; vinyl esters, such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; vinyl ethers, such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, 2-hydroxyethyl vinyl ether, and 4-hydroxybutyl vinyl ether; N-vinyl compounds, such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylimidazole, N-vinylmorpholine, and N-vinylacetamide; and unsaturated isocyanates, such as isocyanatoethyl (meth)acrylate and allyl isocyanate.

[0062] The radical polymerizable polymer may also contain structural units derived from monomers such as aromatic vinyls, such as styrene, vinyl toluene, and α-methyl styrene; olefins, such as ethylene and propylene; vinyl halides, such as vinyl chloride; and vinyl cyanides, such as acrylonitrile, to the extent that heat resistance is not impaired.

[0063] The radical polymerizable polymer may also have a structural unit derived from a monomer having a cyclic ether structure of a three-membered ring or a four-membered ring. As the monomer having a cyclic ether structure of a three-membered ring or a four-membered ring, a monomer having an epoxy group is preferable from the viewpoint of ease of curing by heat or light. Examples of the monomer having an epoxy group include glycidyl (meth)acrylate and 3,4-epoxycyclohexyl (meth)acrylate.

[0064] As the other copolymerizable monomers, among these, methyl (meth)acrylate and benzyl (meth)acrylate are preferred in terms of transparency and heat resistance, and primary hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate are preferred in terms of viscosity reduction.

[0065] The content of structural units derived from other monomers is preferably 0 to 60 mass%, more preferably 0.3 to 50 mass%, even more preferably 0.5 to 40 mass%, and even more preferably 1 to 30 mass%, based on 100 mass% of all structural units constituting the main chain of the radical polymerizable polymer.

[0066] In addition, the radical polymerizable polymer is preferably a polymer that does not lose weight even when heated. For this reason, in the radical polymerizable polymer, the content ratio of the structural unit derived from a monomer containing tertiary carbon, such as t-butyl (meth)acrylate and t-amyl (meth)acrylate, is preferably low. This is because the O-C bond between the oxygen atom adjacent to the (meth)acryloyl group and the tertiary carbon atom adjacent thereto is easily broken by heating. The content ratio of the structural unit derived from the monomer containing tertiary carbon is not particularly limited depending on the application, but from the viewpoint of reducing the thermal weight loss rate and transparency, it is preferably 0 to 5 mass%, more preferably 0 to 3 mass%, even more preferably 0 to 1 mass%, and particularly preferably substantially not contained, in 100 mass% of all structural units constituting the main chain of the radical polymerizable polymer.

[0067] 1.7 Polymerizable double bond The radical polymerizable polymer of the present invention has a polymerizable double bond in a side chain. The radical polymerizable polymer can be cured by heat or light due to the polymerizable double bond in the side chain, and when the radical polymerizable polymer is contained in a photosensitive resin composition, the sensitivity to light is improved, the polymer can be cured with a smaller amount of light, and the mechanical strength of the obtained cured product can be improved.

[0068] The polymerizable double bond of the side chain can be introduced, for example, by reacting a compound having a polymerizable double bond with a structural unit derived from an unsaturated monomer. Specifically, it can be introduced by adding at least one reactive group (i.e., a group that reacts with an acid group) selected from the group consisting of an epoxy group, an oxazoline group, and a hydroxyl group, and a compound containing a polymerizable unsaturated double bond to a base polymer having an acid group (e.g., a polymer having a structural unit derived from an unsaturated monomer having a group that reacts with an acid group such as an epoxy group) to introduce the polymerizable double bond. It can also be introduced by adding a compound containing an acid group and a polymerizable unsaturated double bond to a base polymer having a group that reacts with an acid group (preferably an epoxy group) (e.g., a polymer having a structural unit derived from an unsaturated monomer having a group that reacts with an acid group such as an epoxy group). Hereinafter, the compound containing a reactive group and a polymerizable unsaturated double bond, and the compound containing an acid group and a polymerizable unsaturated double bond are collectively referred to as "addition compound". When the addition compound is reacted with the base polymer, a double bond and a hydroxy group are generated in the side chain. This hydroxy group may further be esterified with a compound having a carboxy group (preferably an unsaturated polycarboxylic acid such as maleic anhydride; a saturated polycarboxylic acid such as succinic anhydride; etc.).

[0069] Since the radically polymerizable polymer of the present invention has an acid group, a method of introducing a polymerizable double bond by adding a compound containing a reactive group and a polymerizable unsaturated double bond is preferred. As the polymerizable unsaturated double bond, a double bond possessed by a (meth)acryloyl group is preferred from the viewpoint of reactivity during curing.

[0070] Examples of the compound containing a reactive group and a polymerizable unsaturated double bond include compounds having a hydroxyl group and a double bond, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and allyl alcohol; compounds having an epoxy group and a double bond, such as glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and allyl glycidyl ether; compounds having an oxazoline group and a double bond, such as vinyloxazoline and isopropenyloxazoline; and the like. As the compound containing a reactive group and a polymerizable unsaturated double bond, a compound having an epoxy group and a carbon-carbon double bond, such as glycidyl (meth)acrylate, allyl glycidyl ether, α-ethyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl acrylate (e.g., "Cyclomer A400" manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl methacrylate (e.g., "Cyclomer M100" manufactured by Daicel Corporation), o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, etc., is preferred, and glycidyl (meth)acrylate and 3,4-epoxycyclohexylmethyl (meth)acrylate are more preferred from the viewpoints of high reactivity during curing, ease of reaction control, and ease of availability. Examples of the compound containing an acid group and a polymerizable unsaturated double bond include the same examples as those given above as the unsaturated monomer having an acid group. The addition compound may be used alone or in combination of two or more kinds.

[0071] The amount of the additive compound used is preferably 5 to 120 parts by mass, more preferably 5 to 80 parts by mass, and even more preferably 5 to 60 parts by mass, relative to 100 parts by mass of the total constitutional units of the base polymer (precursor polymer of the radical polymerizable polymer). The amount of the compound containing a reactive group and a polymerizable unsaturated double bond used is preferably 0.01 to 0.95 mol, more preferably 0.05 to 0.90 mol, and even more preferably 0.1 to 0.80 mol, relative to 1 mol of constitutional units derived from an unsaturated monomer having an acid group contained in the base polymer. The amount of the compound containing an acid group and a polymerizable unsaturated double bond used is preferably 0.01 to 1.2 mol, more preferably 0.1 to 1.0 mol, and even more preferably 0.3 to 0.9 mol, relative to 1 mol of constitutional units derived from an unsaturated monomer having a group reactive with an acid group contained in the base polymer. By setting the amount of the addition compound used within the above range, the exposure sensitivity, developability, and storage stability of the resulting photosensitive resin composition can be improved, and further the adhesion and hardness of the cured product can be improved.

[0072] Examples of the structural unit having a double bond in its side chain include structural unit A formed from any combination of a structural unit derived from an unsaturated monomer having an acid group or a structural unit derived from an unsaturated monomer having a group reactive with an acid group and an addition compound, and structural unit B formed from any combination of the structural unit A and the compound having a carboxy group. A structural unit formed by adding glycidyl (meth)acrylate to a structural unit derived from (meth)acrylic acid (equivalent to a structural unit formed by adding (meth)acrylic acid to a structural unit derived from glycidyl (meth)acrylate) is preferred as structural unit A, and a structural unit formed by ester-bonding maleic anhydride to a hydroxyl group in this preferred structural unit A is preferred as structural unit B.

[0073] The content of the structural unit having a double bond in the side chain is preferably 10 to 70 mass% of the total structural units constituting the main chain of the radical polymerizable polymer (100 mass%), more preferably 15 mass% or more, even more preferably 20 mass% or more, and more preferably 65 mass% or less, even more preferably 60 mass% or less. When the content of the structural unit having a double bond in the side chain is within the above range, the exposure sensitivity, developability, and storage stability of the obtained photosensitive resin composition can be improved, and the adhesion and hardness of the cured product can also be improved.

[0074] 1.8 Characteristics of radical polymerizable polymers The double bond equivalent of the radical polymerizable polymer is preferably 330 to 1600 g / equivalent (mol). When the double bond equivalent is within the above range, the curability (sensitivity to heat and light) of the radical polymerizable polymer is good, and the adhesion of the cured product is further improved. In addition, coloring during curing can be reduced, and transparency can be improved. From the viewpoint of achieving both curability and storage stability, the double bond equivalent is preferably 350 g / equivalent or more, more preferably 380 g / equivalent or more, and even more preferably 400 g / equivalent or more, and is preferably 1500 g / equivalent or less, more preferably 1400 g / equivalent or less, and even more preferably 1300 g / equivalent or less.

[0075] In this specification, the double bond equivalent is the mass (g) of the solid content of the polymer solution per 1 mol of double bonds in the polymer. The mass of the solid content of the polymer solution may be, for example, the total mass of each monomer component constituting the polymer. The double bond equivalent can be obtained by dividing the mass (g) of the solid content of the polymer solution by the amount of double bonds (mol) of the polymer. Specifically, the double bond equivalent can be obtained by confirming the structure of the monomer constituting the base polymer, such as the unsaturated monomer having an acid group used in the polymerization, and the structure of the addition compound used as necessary, and from the masses thereof. It can also be measured by various analyses such as titration, elemental analysis, NMR, and IR, or by differential scanning calorimetry. For example, it may be calculated by measuring the number of ethylenic double bonds contained in 1 g of the polymer in accordance with the iodine value test method described in JIS K 0070:1992.

[0076] The double bond equivalent is a value that serves as a measure of the amount of double bonds contained in a molecule. For compounds (polymers) of the same molecular weight, the larger the double bond equivalent value, the fewer the amount of double bonds introduced.

[0077] The weight average molecular weight (Mw) of the radical polymerizable polymer is 18000 or less, preferably 17000 or less, more preferably 15000 or less, even more preferably 13000 or less, and even more preferably 12000 or less, and the lower limit is preferably 3000 or more, more preferably 4000 or more, and even more preferably 5000 or more. When the weight average molecular weight is within the above range, a photosensitive resin composition having low viscosity and good stability over time is easily obtained.

[0078] The number average molecular weight (Mn) of the radically polymerizable polymer is preferably 1000 to 7000, more preferably 1500 or more, even more preferably 2000 or more, even more preferably 2500 or more, and more preferably 5500 or less, even more preferably 4500 or less, even more preferably 4000 or less.

[0079] The dispersity (Mw / Mn) of the radically polymerizable polymer is preferably from 1.2 to 4.6, more preferably 1.5 or more, even more preferably 1.8 or more, and more preferably 4.2 or less, even more preferably 3.8 or less.

[0080] The weight-average molecular weight and number-average molecular weight can be determined, for example, by gel permeation chromatography (GPC) using polystyrene as the standard substance, tetrahydrofuran (THF) as the eluent, HLC-8220GPC (manufactured by Tosoh Corporation), and a column TSKgel SuperHZM-N (manufactured by Tosoh Corporation).

[0081] The acid value of the radical polymerizable polymer is preferably 30 to 200 mgKOH / g, more preferably 35 mgKOH / g or more, even more preferably 40 mgKOH / g or more, even more preferably 45 mgKOH / g or more, and more preferably 180 mgKOH / g or less, even more preferably 170 mgKOH / g or less, and even more preferably 160 mgKOH / g or less. When the acid value is within the above range, the dispersibility of the radical polymerizable polymer and inorganic fine particles in the photosensitive resin composition is improved, the viscosity is suppressed, the coating property is excellent, and the adhesion of the obtained cured product is also improved. In addition, the alkali solubility is improved, so the developability is also improved.

[0082] The acid value of the radical polymerizable polymer can be obtained by, for example, using a 0.1N KOH aqueous solution as a titrant, measuring the acid value of the polymer solution with an automatic titrator (e.g., Hiranuma Sangyo Co., Ltd., product name "COM-555"), and calculating the acid value per solid content from the acid value of the polymer solution and the solid content of the polymer solution. The solid content of the polymer solution can be obtained, for example, as follows. First, about 0.3 g of the polymer solution is weighed out in an aluminum cup, about 1 g of acetone is added to dissolve it, and then it is naturally dried at room temperature. Then, it is dried at 140°C for 3 hours using a hot air dryer (e.g., Espec Corporation, product name "PHH-101"), and then it is allowed to cool in a desiccator and the mass is measured. The solid content concentration (non-volatile content) of the polymer solution is calculated from the amount of mass loss.

[0083] The thermal weight loss rate of the radical polymerizable polymer is preferably 5.0% by mass or less, more preferably 3.2% by mass or less, even more preferably 3.0% by mass or less, and even more preferably 2.8% by mass or less, and there is no particular lower limit, and it may be 0% by mass. When the thermal weight loss rate is within the above range, the heat resistance (particularly, thermal decomposition resistance) is high.

[0084] The thermal weight loss rate of the radically polymerizable polymer can be determined, for example, by dropping a solution of 2 g of polymer solution and 4 g of tetrahydrofuran into 60 g of hexane, separating and removing the precipitated resin (polymer), vacuum drying overnight at 40°C, weighing 10 mg of the resulting resin powder, and measuring the weight loss rate at 230°C for 30 minutes under a nitrogen atmosphere using a thermogravimetric analyzer TGA-50 (manufactured by SHIMADZU).

[0085] The use of the radical polymerizable polymer of the present invention is not particularly limited, but it can be suitably used for various uses such as printing plate making, protective films for color filters, and liquid crystal display panel manufacturing such as color filters and black matrices. In particular, the obtained cured film has high hardness and high transparency, so it is very useful as a protective film or insulating film in various display devices. The display device is not particularly limited, but for example, a liquid crystal display device, a solid-state imaging device, a touch panel display device, etc. are preferable. As the touch panel display device, a capacitance type display device is particularly preferable.

[0086] 2. Method for producing radical polymerizable polymer The radical polymerizable polymer is obtained by polymerizing the monomer components that are the constituent units. As the polymerization method, a commonly used method such as bulk polymerization, solution polymerization, emulsion polymerization, etc. can be used, and it may be appropriately selected according to the purpose and use. Among them, solution polymerization is preferable because it is industrially advantageous and easy to adjust the molecular weight, etc. As the polymerization mechanism of the monomer components, a polymerization method based on a mechanism such as radical polymerization, anionic polymerization, cationic polymerization, coordination polymerization, etc. can be used, but a polymerization method based on a radical polymerization mechanism is preferable because it is industrially advantageous.

[0087] The polymerization initiation method in the polymerization reaction may be to supply the energy required for polymerization initiation to the monomer components from an active energy source such as heat, electromagnetic waves (infrared rays, ultraviolet rays, X-rays, etc.), or electron beams, and further, by using a polymerization initiator in combination, the energy required for polymerization initiation can be significantly reduced and reaction control becomes easier, which is preferable. A chain transfer agent may also be used in combination. The molecular weight of the radical polymerizable polymer obtained by polymerization can be controlled by adjusting the amount and type of the polymerization initiator, the polymerization temperature, and the type and amount of the chain transfer agent.

[0088] When polymerization is performed by a solution polymerization method, the solvent used for polymerization is not particularly limited as long as it is inactive in the polymerization reaction, and may be appropriately selected depending on polymerization conditions such as the polymerization mechanism, the type and amount of the monomer used, the polymerization temperature, and the polymerization concentration. However, when a solvent is used as a diluent or the like in the subsequent production of a photosensitive resin composition, it is efficient and preferable to use the solvent in the solution polymerization of the monomer components.

[0089] Suitable examples of the solvent include the following compounds, and one or more of these can be used. Monoalcohols such as methanol, ethanol, isopropanol, n-butanol, and s-butanol; glycols such as ethylene glycol and propylene glycol; cyclic ethers such as tetrahydrofuran and dioxane; glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, and 3-methoxybutanol; glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol dimethyl ether, and propylene glycol diethyl ether; ethylene glycol monomethyl ether acetone esters of glycol monoethers such as ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, and 3-methoxybutyl acetate; alkyl esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl lactate, ethyl lactate, butyl lactate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl acetoacetate, and ethyl acetoacetate;Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, etc.; aliphatic hydrocarbons such as hexane, cyclohexane, octane, etc.; amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.;

[0090] Among the above-mentioned solvents, monoalcohols and glycol monoether esters are more preferred, and glycol monoether esters are even more preferred. In particular, as the solvent, propylene glycol monomethyl ether acetate and isopropanol are preferred, and propylene glycol monomethyl ether acetate is particularly preferred, from the viewpoints of solubility, transparency, and chain transfer agent action.

[0091] The amount of the solvent used in the polymerization reaction is preferably 50 to 1000 parts by mass, more preferably 100 to 500 parts by mass, per 100 parts by mass of the total mass of the monomer components. During the polymerization reaction, the amount of the solvent and each monomer component is preferably set so that the final solid concentration (non-volatile content concentration) of the polymer solution is 10 to 70% by mass. In terms of productivity and polymerizability, the final solid concentration is more preferably 20 to 65% by mass, and even more preferably 25 to 60% by mass.

[0092] The polymerization initiator is not particularly limited as long as it is a commonly used one, and examples thereof include organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, and t-butylperoxy-2-ethylhexanoate; azo compounds such as 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobis(2-methylpropionate); etc. These polymerization initiators may be used alone or in combination of two or more. The amount of initiator used may be appropriately set depending on the combination of monomers used, reaction conditions, the molecular weight of the target polymer, etc., and is not particularly limited. However, in order to obtain a polymer having a weight average molecular weight of several thousand to several tens of thousands without gelation, the amount of initiator used is preferably 0.1 to 18 parts by mass relative to 100 parts by mass of the total mass of the monomer components, more preferably 0.5 parts by mass or more, even more preferably 1.5 parts by mass or more, even more preferably 2.2 parts by mass or more, more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less.

[0093] When polymerizing the monomer components, a chain transfer agent that is commonly used may be added as necessary to adjust the molecular weight. Examples of the chain transfer agent include mercaptan-based chain transfer agents such as n-dodecyl mercaptan, mercaptopropionic acid, mercaptoacetic acid, and methyl mercaptoacetate; thiol-based chain transfer agents such as 2-mercaptoethanol, thioglycolic acid, 3-mercaptopropionic acid, thiosalicylic acid, 1-thioglycerol, and 4-aminothiophenol; and α-methylstyrene dimer. As the chain transfer agent, n-dodecyl mercaptan and mercaptopropionic acid are preferred because they have a high chain transfer effect, can reduce residual monomers, and are easily available. When a chain transfer agent is used, the amount of the chain transfer agent used may be appropriately set according to the combination of monomers used, reaction conditions, the molecular weight of the target polymer, etc., and is not particularly limited. However, in order to obtain a polymer having a weight average molecular weight of several thousand to several tens of thousands without gelation, the amount is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the total mass of the monomer components. In addition, in order to increase the transparency of the radical polymerizable polymer of the present invention, the amount of the thiol-based chain transfer agent is preferably 1 part by mass or less, more preferably 0.1 part by mass or less, and particularly preferably substantially free of the thiol-based chain transfer agent, relative to 100 parts by mass of the total mass of the monomer components. In the radical polymerizable polymer of the present invention, it is preferable to radically polymerize the above-mentioned monomer components using the above-mentioned polymerization initiator and without using a thiol-based chain transfer agent.

[0094] The order of addition of the monomer components and the polymerization initiator in the polymerization is not particularly limited. A method in which all the monomer components are charged into a solvent at once and then polymerized, a method in which the remaining monomer components are continuously or gradually added to a reaction vessel in which a solvent and a portion of the monomer components have been charged in advance, and the like can be employed.

[0095] The pressure during the polymerization reaction is not particularly limited, and the reaction may be carried out under either normal pressure or pressure. The temperature during the polymerization reaction varies depending on the type and composition ratio of the monomers used and the type of the solvent used, but is usually preferably in the range of 20 to 150°C, more preferably 40 to 125°C.

[0096] In the case where the addition compound is reacted to contain a polymerizable double bond in the side chain after obtaining a base polymer by the polymerization step, the method of addition reaction of the addition compound is not particularly limited. For the addition reaction, a known method may be appropriately adopted, but for example, it is preferable to add the addition compound to the reaction liquid obtained in the polymerization step and react at 60 to 140°C (more preferably 70 to 130°C). In addition, it is preferable to use catalysts such as amine compounds such as triethylamine and dimethylbenzylamine; ammonium salts such as tetraethylammonium chloride; phosphonium salts such as tetraphenylphosphonium bromide; amide compounds such as dimethylformamide; phosphines such as tri-n-propylphosphine, tri-n-butylphosphine, diphenylmethylphosphine, and triphenylphosphine. Furthermore, it is also preferable to use a polymerization inhibitor such as methylhydroquinone or oxygen in the addition reaction.

[0097] In the case where the compound having a carboxy group is reacted after the addition reaction, the amount of the compound having a carboxy group used is not particularly limited, and it is preferable to set it so that the acid value of the obtained radical polymerizable polymer is in the above-mentioned range.

[0098] 3. Photosensitive resin composition The present invention also relates to a photosensitive resin composition containing the above-mentioned radical polymerizable polymer, a polyfunctional monomer, a polymerization initiator, inorganic fine particles, and a solvent, and is preferably a negative photosensitive resin composition. The use of the photosensitive resin composition of the present invention is not particularly limited, but it is suitably used as a material for forming a protective film for a color filter, a liquid crystal display element, an integrated circuit element, a solid-state imaging element, etc.

[0099] 3.1 Radical polymerizable polymers The photosensitive resin composition of the present invention contains, as a radical polymerizable polymer, a polymer (R1) having a constitutional unit derived from an unsaturated monomer having an acid group and a constitutional unit having a ring structure in the main chain and having a polymerizable double bond in a side chain, in which the proportion of constitutional units derived from an acrylic monomer is 30 to 90 mol % in 100 mol % of all constitutional units constituting the main chain of the radical polymerizable polymer, and a weight average molecular weight of 18000 or less. The photosensitive resin composition of the present invention also contains, as a radical polymerizable polymer, a polymer (R2) having a constitutional unit derived from an unsaturated monomer having an acid group and a constitutional unit having a ring structure in the main chain and having a polymerizable double bond in a side chain, in which the proportion of constitutional units derived from an acrylic monomer to constitutional units derived from a methacrylic monomer in all constitutional units constituting the main chain of the radical polymerizable polymer (constitutional units derived from an acrylic monomer / constitutional units derived from a methacrylic monomer) is 0.5 to 10.5 in molar ratio, and the weight average molecular weight is 18000 or less. The photosensitive resin composition may contain either the polymer (R1) or the polymer (R2), or both the polymer (R1) and the polymer (R2). By containing the radically polymerizable polymer of the present invention, the photosensitive resin composition has low viscosity and excellent stability over time, even when particles having a small particle size are blended.

[0100] The content of the radical polymerizable polymer in the photosensitive resin composition is preferably 5 to 70 mass%, more preferably 8 to 65 mass%, further preferably 10 to 50 mass%, even more preferably 12 to 45 mass%, and still more preferably 15 to 40 mass%, based on 100 mass% of the total solid content of the photosensitive resin composition. When the content of the radical polymerizable polymer is within the above range, the effects of the present invention can be more significantly exhibited.

[0101] 3.2 Multifunctional monomers The polyfunctional monomer contained in the photosensitive resin composition of the present invention is a low molecular weight compound having a polymerizable unsaturated bond (also referred to as a polymerizable unsaturated group) that can be polymerized by irradiation of active energy rays such as free radicals, electromagnetic waves (e.g., infrared rays, ultraviolet rays, X-rays, etc.), and electron beams. For example, a polyfunctional compound having two or more polymerizable unsaturated groups in the molecule can be mentioned. The molecular weight is not particularly limited, but from the viewpoint of handling, for example, it is preferably 3000 or less, more preferably 2000 or less. Among them, a polyfunctional (meth)acrylate compound having two or more functions (hereinafter also simply referred to as a "polyfunctional (meth)acrylate compound") is particularly preferred. A polyfunctional (meth)acrylate compound is a compound having two or more (meth)acryloyl groups in one molecule. By including a polyfunctional monomer (particularly a polyfunctional (meth)acrylate compound), the photosensitive resin composition becomes more excellent in photosensitivity and curability, and it is possible to obtain a cured product with extremely high hardness and high transparency. The functionality of the polyfunctional (meth)acrylate compound is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. From the viewpoint of further suppressing cure shrinkage, the functionality is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

[0102] Examples of polyfunctional monomers include (di)ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, ε-caprolactone-added trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, propylene oxide-added pentaerythritol and polyfunctional (meth)acrylates such as pentaerythritol tetra(meth)acrylate, ε-caprolactone-added pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-added dipentaerythritol hexa(meth)acrylate, propylene oxide-added dipentaerythritol hexa(meth)acrylate, ε-caprolactone-added dipentaerythritol hexa(meth)acrylate, tris(hydroxyethyl)isocyanurate tri(meth)acrylate, propylene oxide-added ditrimethylolpropane tetra(meth)acrylate, and ε-caprolactone-added ditrimethylolpropane tetra(meth)acrylate.Among these, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-added dipentaerythritol hexa(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added ditrimethylolpropane tetra(meth)acrylate, propylene oxide-added pentaerythritol tetra(meth)acrylate, propylene oxide-added dipentaerythritol hexa(meth)acrylate, ε-caprolactone-added trimethylolpropane tri(meth)acrylate, ε-caprolactone-added ditrimethylolpropane tetra(meth)acrylate, ε-caprolactone-added pentaerythritol tetra(meth)acrylate, and ε-caprolactone-added dipentaerythritol hexa(meth)acrylate are preferred.

[0103] The content ratio of the polyfunctional monomer in the photosensitive resin composition is not particularly limited, and may be appropriately set according to the type of polyfunctional monomer and radical polymerizable polymer used, the use and purpose of the photosensitive resin composition, etc. The content ratio of the polyfunctional monomer in the photosensitive resin composition is preferably 2 to 85 mass% in 100 mass% of the total solid content of the photosensitive resin composition, more preferably 5 mass% or more, even more preferably 10 mass% or more, even more preferably 15 mass% or more, and more preferably 75 mass% or less, even more preferably 60 mass% or less, even more preferably 50 mass% or less, and even more preferably 40 mass% or less, from the viewpoint of, for example, being superior in developability and plate making property.

[0104] The content of the polyfunctional monomer is preferably 20 to 500 parts by mass relative to 100 parts by mass of the radical polymerizable polymer, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 50 parts by mass or more, and from the viewpoint of further improving the developability, it is more preferably 400 parts by mass or less, even more preferably 300 parts by mass or less, even more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less. When the content of the polyfunctional monomer relative to the radical polymerizable polymer is within the above range, a cured product with higher surface hardness is obtained, and in combination with the preferred weight average molecular weight of the radical polymerizable polymer being 3000 or more, the developability is further improved.

[0105] 3.3 Polymerization initiator The photosensitive resin composition of the present invention contains a polymerization initiator, and can initiate polymerization by irradiating light or applying heat to form a cured product. The photosensitive resin composition of the present invention can also be thermally cured by using a known thermal polymerization initiator, but it is preferable to add a photopolymerization initiator to photocure the cured product so that the cured product can be microfabricated or imaged by photolithography. In this respect, it is preferable to use a photopolymerization initiator as the polymerization initiator.

[0106] As the thermal polymerization initiator, known ones can be used, and examples thereof include organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, t-butyl peroxybenzoate, lauroyl peroxide, etc.; azo compounds such as azobisisobutyronitrile, etc. For thermal polymerization applications, a curing accelerator may be mixed into the composition and used, and examples of such curing accelerators include tertiary amines, cobalt naphthenate, cobalt octylate, etc.

[0107] As the photopolymerization initiator, known ones can be used, for example, acetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2- Acetophenones such as dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone}, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether benzoins such as benzophenone, o-benzoyl methyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, (4-benzoylbenzyl)trimethylammonium chloride, and other benzophenones; 2- Thioxanthones such as isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride; acylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide;Examples of the oxime esters include 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine; titanocenes such as bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium; and phenylglyoxylic methyl esters. Among these, from the viewpoint of hardness and heat resistance, acetophenones, oxime esters, and titanocenes are preferred, acetophenones are more preferred, aminoacetophenones are even more preferred, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone are even more preferred. ;

[0108] Particularly preferred specific polymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one ("IRGACURE907", manufactured by BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 ("IRGACURE369", manufactured by BASF), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl) aminoacetophenones such as 2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium (IRGACURE 784, BASF); and oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)] (IRGACURE OXE01, BASF).

[0109] These polymerization initiators may be used alone or in combination of two or more.

[0110] The content of the polymerization initiator in the photosensitive resin composition may be appropriately set according to the use or purpose of the photosensitive resin composition, and is not particularly limited. The content ratio of the polymerization initiator in the photosensitive resin composition is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more, based on the total solid content of the photosensitive resin composition (100% by mass), from the viewpoint of obtaining a cured product with excellent heat resistance. In addition, from the viewpoint of the balance between the influence of the decomposition product of the polymerization initiator and the economic efficiency, the content is preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0111] 3.4 Inorganic fine particles The inorganic fine particles refer to fine particles containing an inorganic component, and examples thereof include metals (including metalloids), their salts (carbonates, sulfates, etc.), and their oxides. Among these, metal salts or oxides are preferred, and metal oxides are more preferred. In addition, one molecule may contain one or two or more metal atoms, and when two or more are present, one or two or more types may be present. Since the photosensitive resin composition of the present invention contains inorganic fine particles, it is possible to form a cured product having excellent hardness.

[0112] Examples of metals include silicon (metalloid), titanium, zirconium, calcium, barium, aluminum, etc., and silicon, zirconium, titanium, and aluminum are more preferred. From the viewpoint of further increasing the surface hardness, it is more preferred to contain at least silicon. Examples of metal salts include calcium carbonate and barium sulfate, and examples of metal oxides include silicon oxide (silica, etc.), titanium oxide, aluminum oxide, and zirconium oxide (zirconia, etc.). It is particularly preferred that the inorganic fine particles contain silicon oxide, and they may be composite metal oxides further containing metal atoms other than silicon. In addition, the inorganic fine particles are preferably metal oxide particles having hydroxyl groups on the surface, and more preferably silica fine particles. If the metal oxide particles have hydroxyl groups on the surface, the affinity with the radical polymerizable polymer contained in the photosensitive resin composition is further improved. It is preferred that the silica fine particles are surface-modified by carboxylic acid modification or amino group modification, and it is more preferred that the silica fine particles have (meth)acryloyloxy groups bonded to silicon atoms via divalent linking groups by surface modification.

[0113] The average particle size (d50, by number, hereinafter also simply referred to as "average particle size") of the inorganic fine particles (primary particles) is preferably 1 to 700 nm. When the average particle size of the inorganic fine particles is within the above range, the inorganic fine particles have excellent dispersibility and dispersion stability in the photosensitive resin composition, and a cured product with high transparency can be formed. The average particle size can be measured, for example, by using a laser diffraction particle size distribution analyzer. The average particle size can be determined directly by magnifying and observing inorganic fine particles with a transmission electron microscope (TEM), a field emission transmission electron microscope (FE-TEM), a field emission scanning electron microscope (FE-SEM), or the like, randomly selecting 100 primary particles, measuring their length in the major axis direction, and using the particle size distribution data to determine the 50% particle size (median size).

[0114] The photosensitive resin composition preferably contains inorganic fine particles (P1) having an average particle size of 100 nm or less. The average particle size of the inorganic fine particles (P1) is preferably 10 to 90 nm, more preferably 20 to 80 nm, and further preferably 30 to 70 nm. By containing inorganic fine particles (P1) having a small particle size, the photosensitive resin composition can form a cured product having excellent transparency. Furthermore, the photosensitive resin composition containing the radical polymerizable polymer of the present invention can exhibit low viscosity and excellent stability over time even if it contains inorganic fine particles (P1) having a small particle size.

[0115] The content of the inorganic fine particles (P1) in 100% by mass of the photosensitive resin composition is, for example, 5 to 60% by mass, preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and further preferably 18 to 30% by mass. Within the above range, the photosensitive resin composition can form a cured product having excellent transparency.

[0116] The photosensitive resin composition may contain inorganic fine particles (P2) having an average particle size of more than 100 nm and not more than 700 nm. The average particle size of the inorganic fine particles (P2) is preferably 200 to 680 nm, more preferably 300 to 650 nm, and further preferably 400 to 620 nm. By containing inorganic fine particles (P2) having a relatively large particle size, it is expected that the viscosity of the photosensitive resin composition can be reduced and the stability over time can be improved.

[0117] The content of the inorganic fine particles (P2) in 100% by mass of the photosensitive resin composition is, for example, 5% by mass or more, preferably 10 to 60% by mass, more preferably 20 to 45% by mass, and further preferably 25 to 35% by mass. Within the above range, it is easy to provide a photosensitive resin composition having low viscosity and excellent stability over time.

[0118] The photosensitive resin composition preferably contains either inorganic fine particles (P1) or inorganic fine particles (P2), or both, and more preferably contains both inorganic fine particles (P1) and inorganic fine particles (P2). The inorganic fine particles (P1) and inorganic fine particles (P2) make it easy to provide a photosensitive resin composition having low viscosity and excellent stability over time, and to form a cured product having excellent transparency.

[0119] When the photosensitive resin composition contains both inorganic fine particles (P1) and inorganic fine particles (P2), the mass ratio of the inorganic fine particles (P1) to the inorganic fine particles (P2) is preferably 1:99 to 99:1, more preferably 15:85 to 85:15, and even more preferably 35:65 to 65:35, i.e., inorganic fine particles (P1):inorganic fine particles (P2). The higher the content ratio of the inorganic fine particles (P1), the easier it is to form a cured product with excellent transparency. The higher the content ratio of the inorganic fine particles (P2), the easier it is to provide a photosensitive resin composition with low viscosity and excellent stability over time.

[0120] The inorganic fine particles may be in the form of a dried powder or in the form of a dispersion dispersed in an organic solvent (e.g., colloidal silica, etc.), but from the viewpoint of the dispersion stability of the photosensitive resin composition, it is preferable to use the inorganic fine particles in the form of a dispersion dispersed in an organic solvent. That is, it is preferable that the inorganic fine particles are contained in the photosensitive resin composition as an organic solvent dispersion.

[0121] Examples of the particle shape of the inorganic fine particles include spherical, granular, elliptical, cubic, rectangular, pyramidal, needle-like, columnar, rod-like, cylindrical, scale-like, plate-like, thin flake-like, etc. From the viewpoint of dispersibility in a solvent, etc., the particle shape of the inorganic fine particles is preferably spherical, granular, or columnar.

[0122] When inorganic fine particles are used in the form of a dispersion, the organic solvent (dispersion medium) used may be, for example, any of the solvents contained in the photosensitive resin composition described below. As the organic solvent, only one type may be used, or two or more types may be used in combination.

[0123] The organic solvent dispersion can be obtained by thoroughly dispersing inorganic fine particles in an organic solvent, but commercially available products may also be used. For example, organosilica sols using methyl ethyl ketone as a dispersion medium, such as MEK-ST, MEK-ST-L, MEK-ST-ZL, MEK-ST-UP, and MEK-AC-2140Z; organosilica sols using methyl isobutyl ketone as a dispersion medium, such as MIBK-ST and MIBK-SD-L; organosilica sols using ethyl acetate as a dispersion medium, such as EAC-ST; organosilica sols using methanol as a dispersion medium, such as methanol silica sol and MA-ST-M; organosilica sols using isopropanol as a dispersion medium, such as IPA-ST and IPA-ST-L; organosilica sols using ethylene glycol as a dispersion medium, such as EG-ST; X Examples of organosilica sols include organosilica sols using xylene / n-butanol as a dispersion medium, such as BA-ST; organosilica sols using alkylene glycol monoalkyl ether as a dispersion medium, such as NPC-ST-30 and PGM-ST; organosilica sols using dimethylacetamide as a dispersion medium, such as DMAC-ST; organosilica sols using toluene as a dispersion medium, such as TOL-ST; organosilica sols using propylene glycol monomethyl ether acetate as a dispersion medium, such as PMA-ST; and organosilica sols using propylene glycol monomethyl ether as a dispersion medium, such as PGM-AC-4130Y (all manufactured by Nissan Chemical Industries, Ltd.).

[0124] From the viewpoints of developability, transparency, etc., the content of inorganic fine particles in the photosensitive resin composition (solid content) is preferably 5 to 70 mass% relative to the total solid content of the photosensitive resin composition (100 mass%), more preferably 10 mass% or more, even more preferably 15 mass% or more, and more preferably 60 mass% or less. Furthermore, when silicon-containing microparticles (preferably silica microparticles) are used as the inorganic microparticles, the content (solid content) of the silicon-containing microparticles is preferably 50 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more, out of 100 mass% total amount of inorganic microparticles in the photosensitive resin composition, and there is no particular upper limit, with 100 mass% being preferred.

[0125] When inorganic fine particles are used in the form of a dispersion, the amount of organic solvent used should be an amount that can sufficiently disperse the inorganic fine particles, and for example, is preferably 50 to 600 parts by mass, more preferably 70 parts by mass or more, even more preferably 100 parts by mass or more, and more preferably 550 parts by mass or less, and even more preferably 500 parts by mass or less, relative to 100 parts by mass of inorganic fine particles.

[0126] 3.5 Solvents The photosensitive resin composition of the present invention contains a solvent as a diluent. When the radical polymerizable polymer is obtained by a solution polymerization method, the radical polymerizable polymer may be used as a polymer solution without being separated from the solvent, and the solvent contained in the polymer solution may be the solvent contained in the photosensitive resin composition. When inorganic fine particles are used in the form of a dispersion, the organic solvent contained in the dispersion may be the solvent contained in the photosensitive resin composition. When the photosensitive resin composition contains a solvent derived from the polymer solution or the dispersion of inorganic fine particles, a solvent may be further added or may not be added.

[0127] The solvent is not particularly limited as long as it can uniformly dissolve or disperse components such as the radical polymerizable polymer, the polyfunctional monomer, the polymerization initiator, and the inorganic fine particles. Specific examples of the solvent include monoalcohols such as methanol, ethanol, isopropanol, n-butanol, and s-butanol; glycols such as ethylene glycol and propylene glycol; cyclic ethers such as tetrahydrofuran and dioxane; glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, and 3-methoxybutanol; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether. glycol ethers such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, 3-methoxybutyl acetate and other glycol monoether esters;Examples of the solvent include alkyl esters such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl lactate, ethyl lactate, butyl lactate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl acetoacetate, and ethyl acetoacetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as hexane, cyclohexane, and octane; halogenated hydrocarbons such as methylene chloride, chloroform, and 1,2-dichlorobenzene; and sulfoxide solvents such as dimethyl sulfoxide. Examples of the solvent contained in the photosensitive resin composition include monoalcohols and esters of glycol monoethers, more preferably esters of glycol monoethers, and even more preferably propylene glycol monomethyl ether acetate.

[0128] The total content of the solvent in the photosensitive resin composition may be appropriately set according to the optimum viscosity when the photosensitive resin composition is used, and is preferably 50 to 1200 parts by mass, more preferably 100 to 900 parts by mass, relative to 100 parts by mass of the radical polymerizable polymer. If the total content of the solvent in the photosensitive resin composition is within the above range, the handling property and storage stability of the composition, as well as the efficiency during the coating operation, are improved.

[0129] 3.6 Multifunctional epoxy compounds The photosensitive resin composition of the present invention may further contain a polyfunctional epoxy compound. When the radical polymerizable polymer has an acid group, the polyfunctional epoxy compound reacts with the acid group to promote the curing of the photosensitive resin composition. The polyfunctional epoxy compound is a compound having two or more epoxy groups in one molecule.

[0130] Examples of polyfunctional epoxy compounds include those described in JP 2019-174761 A (paragraph number 0076). Specific examples of polyfunctional epoxy compounds include bisphenol A type epoxy resins (e.g., jER828, jER834, jER1001, and jER1004 manufactured by Mitsubishi Chemical Corporation), brominated epoxy resins (e.g., jERYL903 manufactured by Mitsubishi Chemical Corporation), novolac type epoxy resins (e.g., jER152 and jER154 manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins (e.g., jER807 manufactured by Mitsubishi Chemical Corporation), hydrogenated bisphenol A type epoxy resins (e.g., Epotohto ST-2004, ST-2007, and S manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), and the like. T-3000), glycidylamine type epoxy resins (e.g., jER604 manufactured by Mitsubishi Chemical Corporation), alicyclic epoxy resins (e.g., Celloxide 2021P manufactured by Daicel Corporation), trihydroxyphenylmethane type epoxy resins (e.g., YL-933 manufactured by Mitsubishi Chemical Corporation), bixylenol type or biphenol type epoxy resins or mixtures thereof (e.g., YL-6056, YX-4000, YL-6121 manufactured by Mitsubishi Chemical Corporation), bisphenol S type epoxy resins (e.g., EBPS-200 manufactured by Nippon Kayaku Co., Ltd.), Bisphenol A novolac type epoxy resin (e.g., jER157S manufactured by Mitsubishi Chemical Corporation), tetraphenylolethane type epoxy resin (e.g., jERYL-931 manufactured by Mitsubishi Chemical Corporation), heterocyclic epoxy resin (e.g., TEPIC manufactured by Nissan Chemical Industries, Ltd.), diglycidyl phthalate resin (e.g., Blenmar DDT manufactured by NOF Corporation), tetraglycidyl xylenoylethane resin (e.g., ZX-1063 manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.), naphthalene group-containing epoxy resin (e.g., ESN-190, ESN- 360), epoxy resins having a dicyclopentadiene skeleton (e.g., HP-7200 and HP-7200H manufactured by DIC), glycidyl methacrylate copolymer epoxy resins (e.g., CP-50S and CP-50M manufactured by NOF Corporation), copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate, epoxy-modified polybutadiene rubber derivatives (e.g., Epolead PB-3600 manufactured by Daicel Corporation), and CTBN-modified epoxy resins (e.g., YR-102 and YR-450 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).These may be used alone or in combination of two or more. Of the polyfunctional epoxy compounds, bisphenol A type epoxy resins are preferred.

[0131] The content ratio of the polyfunctional epoxy compound in the photosensitive resin composition is not particularly limited, and may be appropriately set depending on the type of radical polymerizable polymer used, the use and purpose of the photosensitive resin composition, etc. The content ratio of the polyfunctional epoxy compound in the photosensitive resin composition is preferably 0.5 to 30 mass%, more preferably 3 to 20 mass%, and further preferably 5 to 15 mass% in 100 mass% of the total solid content of the photosensitive resin composition.

[0132] 3.7 Other ingredients The photosensitive resin composition of the present invention may contain other components other than the radical polymerizable polymer, the polyfunctional monomer, the polymerization initiator, the inorganic fine particles, and the solvent. The other components are not particularly limited as long as they do not impair the effects of the present invention, and examples thereof include known additives such as fillers such as aluminum hydroxide, talc, clay, and barium sulfate, quantum dot particles, pigments, dyes, defoamers, coupling agents, leveling agents, sensitizers, release agents, lubricants, plasticizers, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, polymerization inhibitors, polymerization retarders, polymerization accelerators, thickeners, dispersants, and surfactants. As the pigment, various organic pigments and / or inorganic pigments can be used, and as the dye, various organic dyes and / or inorganic dyes can be used. The pigments and dyes may be natural or synthetic dyes. The other components may be used alone or in combination of two or more.

[0133] The other components may include a polymer other than the above-mentioned radical polymerizable polymer. When a polymer other than the above-mentioned radical polymerizable polymer is included, the content of the radical polymerizable polymer of the present invention is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and preferably less than 100% by mass, based on 100% by mass of the total amount of the polymer.

[0134] 4. Method for preparing photosensitive resin composition The method for preparing the photosensitive resin composition of the present invention is not particularly limited, and any known method may be used. For example, a method of mixing and dispersing a radical polymerizable polymer, a polyfunctional monomer, a polymerization initiator, inorganic fine particles, a solvent, and other components as necessary, using a known mixer or disperser may be mentioned. The mixing and dispersing step is not particularly limited, and the components used may be mixed and dispersed all at once, or a part of the components may be mixed first, and then the remaining components may be added and mixed and dispersed. Examples of the dispersing machine include a paint conditioner, a bead mill, a roll mill, a ball mill, a jet mill, a homogenizer, a kneader, a blender, and the like. In addition, other steps that are usually performed when preparing a photosensitive resin composition may be further included. It is preferable to filter the obtained photosensitive resin composition using a filter or the like to remove fine dust.

[0135] When the photosensitive resin composition contains a colorant such as a pigment or a dye, it is preferable to prepare the composition through a colorant dispersion process. The colorant dispersion process may, for example, be a method in which a colorant (preferably an organic pigment), a dispersant, and a solvent are weighed out in predetermined amounts, and the colorant is dispersed into fine particles using a dispersing machine to obtain a liquid colorant dispersion (also called a mill base).

[0136] The colorant dispersion step preferably includes a method in which the colorant is kneaded and dispersed using a roll mill, kneader, blender, or the like, and then finely dispersed using a media mill such as a bead mill filled with beads of 0.01 to 1 mm to obtain a mill base.

[0137] When the photosensitive resin composition is prepared using the mill base, a method can be mentioned in which a composition (preferably a transparent liquid) in which components other than the colorant contained in the mill base, such as a radical polymerizable polymer, a polyfunctional monomer, a polymerization initiator, and inorganic fine particles, are mixed and dispersed using a mixer or disperser, is mixed with the mill base to prepare a uniform dispersion solution, thereby obtaining the photosensitive resin composition.

[0138] The viscosity of the photosensitive resin composition may be appropriately set depending on the desired thickness of the cured film, but for example, in a photosensitive resin composition with a solid content (non-volatile content) adjusted to 40 mass%, the viscosity at 25°C after preparation of the photosensitive resin composition (hereinafter also referred to as "initial viscosity") is preferably 100 mPa·s or less, more preferably 50 mPa·s or less, even more preferably 20 mPa·s or less, even more preferably 18 mPa·s or less, and preferably 1 mPa·s or more, more preferably 3 mPa·s or more. By setting the initial viscosity of the photosensitive resin composition within the above range, the handling property and the coating workability are improved.

[0139] According to the radical polymerizable polymer of the present invention, a photosensitive resin composition having excellent stability over time can be provided. For example, a photosensitive resin composition is provided in which the solid content (non-volatile content) is adjusted to 40 mass % and then the viscosity at 25°C after storing at 60°C for 24 hours (hereinafter also referred to as "viscosity after 24 hours at 60°C") is preferably 100 mPa·s or less, more preferably 50 mPa·s or less, even more preferably 25 mPa·s or less, and even more preferably 20 mPa·s or less. The lower limit of the viscosity after 24 hours at 60°C is not particularly limited, but may be 1 mPa·s or more, or may be 3 mPa·s or more.

[0140] Furthermore, the radical polymerizable polymer of the present invention provides a photosensitive resin composition that has a low viscosity increase rate, calculated based on the following formula, and has good stability over time. For example, in a photosensitive resin composition that contains 20 mass% of inorganic fine particles (P1) having an average particle size of 100 nm or less and 30 mass% of inorganic fine particles (P2) having an average particle size of more than 100 nm and not more than 7000 nm, based on 100 mass% of the photosensitive resin composition, the viscosity increase rate is preferably less than 130%, more preferably 120% or less, even more preferably 110% or less, and even more preferably 105% or less, and the lower limit is not particularly limited, but may be 100% or more. Viscosity increase rate (%) = (viscosity after 24 hours at 60°C) / (initial viscosity) x 100

[0141] 5. Cured product A cured product (e.g., a cured film) can be obtained by curing the radical polymerizable polymer and / or photosensitive resin composition of the present invention. Specifically, the radical polymerizable polymer and / or photosensitive resin composition of the present invention can be applied to a substrate to form a coating layer, and the coating layer can be cured and dried to form a cured film.

[0142] Examples of materials used for the substrate include transparent materials such as glass, acrylic resin, polycarbonate resin, polyester resin (eg, PET, etc.), and polystyrene resin, and metal materials such as aluminum, copper, iron, and stainless steel.

[0143] Examples of a method for applying the composition to a substrate include methods using a spin coater, a bar coater, a gravure coater, a roll coater, a knife coater, an applicator, and the like.

[0144] A drying step may be further carried out before curing the coating layer, and the drying temperature in this step is preferably 40 to 180° C., more preferably 60 to 120° C., and further preferably 70 to 100° C. The drying time is preferably 0.5 to 30 minutes, and more preferably 1 to 10 minutes.

[0145] The coating layer can be cured by irradiating the coating layer with active energy rays using, for example, an ultra-high pressure mercury lamp, etc. The amount of active energy rays to be irradiated is not particularly limited and can be appropriately set depending on the purpose and use of the photosensitive resin composition, the amount of polymerization initiator used, etc. For example, the ultraviolet irradiation intensity (converted to 365 nm illuminance) is 10 to 2000 mJ / cm 2 is preferably 20 to 1500 mJ / cm 2 is more preferred.

[0146] Drying after curing is preferably performed by heating (post-baking), and the heating temperature is preferably 90 to 200° C., more preferably 100 to 190° C., and even more preferably 120 to 180° C. The heating time is preferably 10 to 120 minutes, and more preferably 20 to 90 minutes. By further heating after curing, the cured film can be further hardened, and the hardness and adhesion can be further improved.

[0147] The film thickness of the cured film is preferably 0.1 to 150 μm, more preferably 0.5 to 120 μm, and even more preferably 0.5 to 100 μm. By setting the film thickness of the cured film within the above range, it is possible to fully meet the demand for low height of members and displays using the cured film.

[0148] Specifically, the light transmittance of the cured product is preferably 20% or more, more preferably 50% or more, even more preferably 55.5% or more, and even more preferably 60% or more, with the upper limit being 100%. If the light transmittance is within the above range, the cured product will have high transparency. Since the cured film formed from the radical polymerizable polymer and / or photosensitive resin composition of the present invention has high transparency, for example, even when a laminate including the cured film is used in a touch panel, the display performance is not deteriorated and a clear image can be displayed.

[0149] It is also suitable to form a laminate such as a color filter using a cured product (for example, a cured film) formed from the radically polymerizable polymer and / or photosensitive resin composition of the present invention.

[0150] The color filter is preferably in the form of having a cured product of a radical polymerizable polymer and / or a photosensitive resin composition on a substrate. In the color filter, the cured product is particularly suitable as a segment that requires coloring, such as a black matrix or each pixel of red, green, blue, yellow, etc., and is also suitable as a segment that does not require coloring, such as a photospacer, a protective layer, and an alignment control rib.

[0151] Examples of substrates used in color filters include glass substrates such as white plate glass, blue plate glass, alkali-reinforced glass, and silica-coated blue plate glass; sheets, films, or substrates made of thermoplastic resins such as polyester, polycarbonate, polyolefin, polysulfone, ring-opening polymers of cyclic olefins, and hydrogenated products thereof; sheets, films, or substrates made of thermosetting resins such as epoxy resins and unsaturated polyester resins; metal substrates such as aluminum plates, copper plates, nickel plates, and stainless steel plates; ceramic substrates; semiconductor substrates having photoelectric conversion elements; glass substrates having a coloring material layer on the surface (e.g., color filters for LCDs); and the like. Among these, from the viewpoint of heat resistance, glass substrates and sheets, films, or substrates made of heat-resistant resins are preferred. In addition, a transparent substrate is preferred as a substrate for a color filter. The substrate may be subjected to corona discharge treatment, ozone treatment, chemical treatment with a silane coupling agent, or the like, as necessary.

[0152] It is preferable to form the color filter by photolithography, specifically, for each pixel of one color (i.e., for each pixel of one color), a method including a step of disposing a photosensitive resin composition on a substrate (also called a disposing step), a step of irradiating the photosensitive resin composition disposed on the substrate with light (also called a light irradiation step), a step of developing with a developer (also called a developing step), and a step of heating (also called a heating step) is adopted, and it is preferable to adopt a manufacturing method in which the same method is repeated for each color. Note that the order of forming the pixels of each color is not particularly limited.

[0153] The photosensitive resin composition containing the radical polymerizable polymer of the present invention has low viscosity and excellent stability over time, and the photosensitive resin composition can form a cured product with excellent transparency. Therefore, the radical polymerizable polymer and the photosensitive resin composition of the present invention can be suitably used in applications such as resist materials, various coating agents, and paints. In addition, since the radical polymerizable polymer has an acid group such as a carboxy group, it can be suitably used as an alkali development type negative resist material for producing color pixels of color filters, black matrices, overcoats, photospacers, optical waveguides, etc. EXAMPLES

[0154] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the present invention by making appropriate modifications within the scope of the above and below-mentioned aims, and all of these modifications are included in the technical scope of the present invention.

[0155] First, the measurement and evaluation methods employed in the following examples and comparative examples will be described. (1) Weight average molecular weight (Mw), number average molecular weight (Mn) Measurements were performed by gel permeation chromatography (GPC; HLC-8220GPC, manufactured by Tosoh Corporation) using tetrahydrofuran as an eluent and a TSKgel SuperHZM-N (manufactured by Tosoh Corporation) column, and calculations were made in terms of standard polystyrene.

[0156] (2) Solids (non-volatile content) About 0.3 g of the copolymer solution prepared in the examples and comparative examples was weighed into an aluminum cup, dissolved in about 1 g of acetone, and then naturally dried at room temperature. After that, it was dried at 140°C for 3 hours using a hot air dryer (product name: PHH-101, manufactured by Espec Corporation), cooled in a desiccator, and weighed. From the weight loss, the weight of the solid content (non-volatile content; resin) of the copolymer solution was calculated.

[0157] (3) Acid value 1.5 g of the copolymer solution prepared in each of the Examples and Comparative Examples was precisely weighed out, dissolved in a mixed solvent of 90 g of acetone and 10 g of water, and titrated with a 0.1 N KOH aqueous solution. The titration was performed using an automatic titrator (product name: COM-555, manufactured by Hiranuma Sangyo Co., Ltd.), and the acid value per 1 g of polymer was calculated from the solid content concentration (mg KOH / g).

[0158] (4) Thermogravimetric reduction rate A solution of 2 g of the copolymer solution prepared in each of the Examples and Comparative Examples, plus 4 g of tetrahydrofuran, was added dropwise to 60 g of hexane, and the precipitated resin (copolymer) was separated, taken out, and vacuum dried overnight at 40° C. 10 mg of the resulting resin powder was weighed, and the weight loss rate at 230° C. for 30 minutes under a nitrogen atmosphere was measured using a thermogravimetric analyzer TGA-50 (manufactured by SHIMADZU).

[0159] (5) Viscosity The viscosity of the photosensitive resin composition was measured at 25° C. using a cone-plate type rotational viscometer (TVE22LT, manufactured by Toki Sangyo Co., Ltd.). The cone plate used was a standard rotor (name: 1°34′×R=24). First, the viscosity of the photosensitive resin composition was measured after preparation and was defined as the initial viscosity. After preparation of the photosensitive resin composition, the viscosity was measured after storage at 60°C for 24 hours and was defined as the viscosity after 24 hours at 60°C. The viscosity increase rate was calculated based on the following formula to evaluate the stability over time of the photosensitive resin composition. Viscosity increase rate (%) = (viscosity after 24 hours at 60°C) / (initial viscosity) x 100

[0160] (6) Double bond equivalent It was determined by dividing the mass (g) of the solid content of the copolymer solution by the amount of double bonds (mol) of the copolymer.

[0161] (7) Transmittance Using a glass substrate as a blank, the transmittance of the formed cured product was measured with a spectrophotometer UV3100 (manufactured by Shimadzu Corporation) to determine the transmittance at 400 nm.

[0162] <Copolymerization monomers / addition monomers> In the following, the copolymerizable monomers and the addition monomers will be described using abbreviations, which stand for the following compounds: "PMI": N-phenylmaleimide "CHMI": N-cyclohexylmaleimide "AOMA": methyl (α-allyloxymethyl)acrylate "AA": acrylic acid "MAA": methacrylic acid "HPMA": 2-hydroxypropyl methacrylate "THFA": Tetrahydrofurfuryl acrylate "THFMA": Tetrahydrofurfuryl methacrylate "CHA": Cyclohexyl acrylate "CHMA": Cyclohexyl methacrylate "VT": Vinyl toluene "M100": 3,4-epoxycyclohexylmethyl methacrylate ("Cyclomer M100" manufactured by Daicel Corporation) "GMA": glycidyl methacrylate

[0163] <Preparation of copolymer solution> [Example 1] A separable flask equipped with a cooling tube was prepared as a reaction vessel. On the other hand, 15.0 g of PMI, 31.0 g of AA, 13.0 g of THFA, 31.0 g of CHMA, 10.0 g of HPMA, and 6 g of t-butylperoxy-2-ethylhexanoate (trade name: Perbutyl (registered trademark) O, manufactured by Nippon Oil & Fats Corporation, hereinafter also referred to as "PBO") were charged as a monomer composition into a monomer dropping vessel and mixed by stirring. 233g of propylene glycol methyl ether acetate (hereinafter also referred to as "PGMEA") was charged into the reaction vessel, and after replacing with nitrogen, the temperature of the reaction vessel was raised to 90°C by heating in an oil bath while stirring. After the temperature of the reaction vessel stabilized at 90°C, the monomer composition was dripped. While maintaining the temperature at 90°C, the monomer composition was dripped over 180 minutes. After the monomer composition dripping was completed, 0.5g of PBO was added. After another 30 minutes, the reaction vessel was heated to 115°C. After maintaining 115°C for 1 hour, a gas inlet tube was attached to the separable flask, and bubbling of oxygen / nitrogen = 7 / 93 (v / v) mixed gas was started. Next, 33.0g of GMA, 0.2g of Antage W-400 (manufactured by Kawaguchi Chemical Industry Co., Ltd.) as a polymerization inhibitor, and 0.4g of triphenylphosphine (hereinafter also referred to as "TPP") as a catalyst were charged into the reaction vessel, and the reaction was carried out at 115°C for 14 hours. The copolymer solution (A-1) containing 36.2% by weight of resin (solid content) was obtained. The properties of the obtained copolymer are shown in Table 1.

[0164] [Example 2] A copolymer solution (A-2) was obtained in the same manner as in Example 1, except that the types and amounts of the copolymerization monomer and the addition monomer were changed to those shown in Table 1. The properties of the obtained copolymer are shown in Table 1.

[0165] [Example 3] A copolymer solution (A-3) was obtained in the same manner as in Example 1, except that the types and amounts of the copolymerization monomer and the addition monomer were changed to those shown in Table 1. The properties of the obtained copolymer are shown in Table 1.

[0166] [Example 4] A copolymer solution (A-4) was obtained in the same manner as in Example 1, except that the types and amounts of copolymerization monomers and addition monomers were as shown in Table 1, and the amount of PBO added to the monomer composition was changed from 6 g to 10 g. The properties of the obtained copolymer are shown in Table 1.

[0167] [Example 5] A copolymer solution (A-5) was obtained in the same manner as in Example 1, except that the types and amounts of copolymerization monomers and addition monomers were as shown in Table 1, the amount of PBO added to the monomer composition was changed from 6 g to 10 g, and 0.4 g of TPP was added and reacted at 115° C. for 21 hours. The properties of the obtained copolymer are shown in Table 1.

[0168] [Example 6] A copolymer solution (A-6) was obtained in the same manner as in Example 1, except that the types and amounts of copolymerization monomers and addition monomers were as shown in Table 1, the amount of PBO added to the monomer composition was changed from 6 g to 4 g, and 0.4 g of TPP was added and reacted at 115° C. for 21 hours. The properties of the obtained copolymer are shown in Table 1.

[0169] [Example 7] A copolymer solution (A-7) was obtained in the same manner as in Example 1, except that the types and amounts of the copolymerization monomer and the addition monomer were changed to those shown in Table 1. The properties of the obtained copolymer are shown in Table 1.

[0170] [Example 8] A copolymer solution (A-8) was obtained in the same manner as in Example 1, except that the types and amounts of copolymerization monomers and addition monomers were as shown in Table 1, and the amount of PBO added to the monomer composition was changed from 6 g to 5 g. The properties of the obtained copolymer are shown in Table 1.

[0171] [Comparative Example 1] A copolymer solution (A-9) was obtained in the same manner as in Example 1, except that the types and amounts of copolymerization monomers and addition monomers were as shown in Table 1, and the amount of PBO added to the monomer composition was changed from 6 g to 8 g. The properties of the obtained copolymer are shown in Table 1.

[0172] [Comparative Example 2] A copolymer solution (A-10) was obtained in the same manner as in Example 1, except that the types and amounts of copolymerization monomers and addition monomers were as shown in Table 1, and the amount of PBO added to the monomer composition was changed from 6 g to 2 g. The properties of the obtained copolymer are shown in Table 1.

[0173] [Comparative Example 3] A separable flask equipped with a cooling tube was prepared as a reaction vessel. Meanwhile, 15.0 g of PMI, 25.0 g of AA, 10.0 g of HPMA, 28.0 g of CHMA, 22.0 g of VT, and 6 g of PBO were charged into a monomer dropping vessel as a monomer composition and mixed with stirring. 233g of PGMEA was charged into the reaction vessel, and after replacing with nitrogen, the temperature of the reaction vessel was raised to 90°C by heating in an oil bath while stirring. After the temperature of the reaction vessel stabilized at 90°C, the monomer composition was added dropwise. While maintaining the temperature at 90°C, the monomer composition was added dropwise over 180 minutes. After completion of the dropwise addition of the monomer composition, 0.5g of PBO was added. After another 30 minutes, the reaction vessel was heated to 115°C. After maintaining the temperature at 115°C for 1 hour, it was cooled to room temperature to obtain a copolymer solution (A-11) containing 30.3% by weight of resin (solid content). The properties of the obtained copolymer are shown in Table 1.

[0174] [Comparative Example 4] A copolymer solution (A-12) was obtained in the same manner as in Example 1, except that the types and amounts of the copolymerization monomer and the addition monomer were changed to those shown in Table 1. The properties of the obtained copolymer are shown in Table 1.

[0175] [Comparative Example 5] A copolymer solution (A-13) was obtained in the same manner as in Example 1, except that the types and amounts of the copolymerization monomer and the addition monomer were changed to those shown in Table 1. The properties of the obtained copolymer are shown in Table 1.

[0176] [Table 1]

[0177] [Example 9] (Preparation of Photosensitive Resin Composition) The binder resin was 3.31 g of copolymer solution (A-1) (i.e., 1.2 g of resin solids), the inorganic fine particles were 2.67 g of PGM-AC-4130Y (surface-treated silica 30 mass% propylene glycol monomethyl ether dispersion, Nissan Chemical Industry Co., Ltd., non-volatile content 0.8 g, particle diameter (d50, number basis) 50 nm), 1.71 g of SFP-30MHE (surface-treated silica, Denka Co., Ltd., non-volatile content 1.2 g, particle diameter (d50, number basis) 600 nm), and the polyfunctional monomer was dipentaerythritol hexaacrylate (hereinafter A photosensitive resin composition (B1) was prepared by adding 0.4 g of bisphenol A epoxy resin (trade name: jER828, manufactured by Mitsubishi Chemical Corporation) as a polyfunctional epoxy compound, 0.36 g of bisphenol A type epoxy resin (trade name: IRGACURE (registered trademark) 907, manufactured by BASF Japan Ltd., hereinafter also referred to as "Irg907") as a photopolymerization initiator, and diluting with PGMEA to a non-volatile content of 40% by weight, thereby preparing a photosensitive resin composition (B1).

[0178] (Formation of hardened film) The photosensitive resin composition (B1) was applied onto a 5 cm square glass substrate using a spin coater and dried in an oven at 80° C. for 3 minutes. After drying, the composition was irradiated with 1 J / cm 2 using a UV aligner (product name: TME-150RNS, manufactured by TOPCON) equipped with a 2.0 kW ultra-high pressure mercury lamp. 2 (365 nm illuminance equivalent). After UV irradiation, the coating was post-cured at 160°C for 1 hour to completely cure the coating. The transmittance of the resulting cured coating (coating) with a thickness of 100 μm was measured. The results are shown in Table 2.

[0179] [Examples 10 to 19, Comparative Examples 6 to 10] Photosensitive resin compositions (B2) to (B16) were prepared in the same manner as in Example 9, except that the composition of the photosensitive resin composition was changed as shown in Table 2, and cured films were formed using the obtained photosensitive resin compositions. Table 2 shows the viscosity of the photosensitive resin compositions and the permeability test results of the cured films.

[0180] [Table 2] [Industrial Applicability]

[0181] The radically polymerizable polymer and photosensitive resin composition of the present invention can be applied, for example, to resist materials, and can be suitably used in the fields of optics and electric / electronics.

Claims

1. A radical polymerizable polymer having a structural unit derived from an unsaturated monomer having an acid group and a structural unit having a ring structure in its main chain, and having a polymerizable double bond in its side chain, the proportion of structural units derived from acrylic monomers is 30 to 90 mol % in 100 mol % of all structural units constituting the main chain of the radical polymerizable polymer, A radically polymerizable polymer having a weight average molecular weight of 18,000 or less.

2. A radical polymerizable polymer having a structural unit derived from an unsaturated monomer having an acid group and a structural unit having a ring structure in its main chain, and having a polymerizable double bond in its side chain, In all of the structural units constituting the main chain of the radical polymerizable polymer, the ratio of structural units derived from acrylic monomers to structural units derived from methacrylic monomers (structural units derived from acrylic monomers / structural units derived from methacrylic monomers) is 0.5 to 10.5 in terms of molar ratio, A radically polymerizable polymer having a weight average molecular weight of 18,000 or less.

3. 3. The radical polymerizable polymer according to claim 1, wherein the structural unit having a ring structure in the main chain is a structural unit derived from an N-substituted maleimide monomer.

4. 3. The radical polymerizable polymer according to claim 1, further comprising a structural unit derived from an unsaturated monomer having a cyclic ether structure with five or more members.

5. 3. The radical polymerizable polymer according to claim 1, further comprising a structural unit derived from an unsaturated monomer having a hydroxyalkyl group containing a secondary hydroxyl group.

6. 3. The radical polymerizable polymer according to claim 1, further comprising a structural unit derived from an unsaturated monomer having a cyclohexyl group.

7. 3. The radical polymerizable polymer according to claim 1, having an acid value of 30 to 200 mgKOH / g.

8. 3. The radical polymerizable polymer according to claim 1, having a double bond equivalent of 330 to 1600 g / mol.

9. A photosensitive resin composition comprising the radical polymerizable polymer according to claim 1 or 2, a polyfunctional monomer, a polymerization initiator, inorganic fine particles, and a solvent.

10. The inorganic fine particles include inorganic fine particles (P1) having an average particle diameter (d50, by number) of 100 nm or less, 10. The photosensitive resin composition according to claim 9, wherein the content of the inorganic fine particles (P1) is 5 to 60 mass% in 100 mass% of the photosensitive resin composition.

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