Copolymer and method for producing the copolymer

Abstract

The purpose of the present invention is to provide: a resin composition which exhibits good developing performance when used as a photosensitive material, which has excellent storage stability, and which yields a cured product having excellent solvent resistance even if cured at a low temperature; a copolymer that is useful for preparing this resin composition; and a method for producing the copolymer. This copolymer contains a constituent unit (a) having a group represented by formula (1) or formula (2), a constituent unit (b) having a hydroxyl group and a constituent unit (c) having an acid group, and has a glass transition temperature of 30ºC or lower.

Description

[Technical Field]

[0001] The present invention relates to copolymers, resin compositions, color filters, image display elements, and methods for producing copolymers. This application claims priority based on Japanese Patent Application No. 2020-215472, filed in Japan on December 24, 2020, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Generally, organic electroluminescent (EL) display devices (especially the WRGB method, which combines white-emitting organic EL and color filters), image display elements such as liquid crystal display elements, integrated circuit elements, and image imaging elements such as solid-state image sensors are provided with color filters, black matrices, color filter protective films, photospacers, liquid crystal alignment protrusions, or films and fine patterns such as microlenses and insulating films for touch panels.

[0003] In recent years, with the increasing flexibility and wearability of displays, there has been a shift from glass to organic materials such as resins in substrate materials. Organic materials have inferior heat resistance compared to glass. Therefore, in components formed by heat-curing a resin composition on a substrate, it is desirable to lower the temperature at which the resin composition is heat-cured, depending on the heat resistance of the substrate made of organic material. For example, conventionally, color filters were formed by heat-curing a resin composition on a substrate at a temperature of 210 to 230°C. However, when forming color filters on a flexible substrate made of resin, the substrate has poor heat resistance, so it is required to heat-cur the resin composition at a temperature of 80 to 150°C.

[0004] In particular, in the color filter used in an organic EL display device, in order to enhance color reproducibility, there is a tendency to increase the content of the colorant contained in the resin composition. Generally, a resin composition containing a large amount of a colorant is difficult to be photocured. Therefore, in the resin composition used for the color filter of an organic EL display device, it is even more important to be cured by crosslinking with heat. From this, in the resin composition used for the color filter of an organic EL display device, particularly, the need to improve the thermosetting property at low temperatures is increasing.

[0005] Conventionally, as the resin composition used as a material for a color filter, for example, those described in Patent Document 1 and Patent Document 2 exist. Patent Document 1 discloses a photosensitive coloring composition containing the following (a) to (e). (a) A polymerization initiator having an absorption coefficient at 365 nm in methanol of 1.0×10 , , ,

[0007] , , , , mL / gcm or more, (b) a polymerization initiator having an absorption coefficient at 365 nm in methanol of 1.0×10 2 mL / gcm or less and an absorption coefficient at 254 nm of 1.0×10 3 mL / gcm or more, (c) a compound having an unsaturated double bond, (d) an alkali-soluble resin, (e) a colorant. Patent Document 2 discloses a photosensitive composition for a color filter containing a compound containing a furyl group, a compound containing a photopolymerizable functional group, a photopolymerization initiator, and a colorant.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, conventional resin compositions did not yield cured products with good developability and storage stability when used as photosensitive materials, nor did they produce cured products with excellent solvent resistance when cured at low temperatures. The present invention has been made in view of the above circumstances, and aims to provide a resin composition that has good developability when used as a photosensitive material, excellent storage stability, and yields a cured product with excellent solvent resistance even when cured at low temperatures, a copolymer useful for preparing this resin composition, and a method for producing the copolymer. Furthermore, the present invention aims to provide a color filter having a colored pattern made from a cured resin composition that exhibits good developability and excellent solvent resistance even when cured at low temperatures, and an image display element equipped with the color filter. [Means for solving the problem]

[0008] The present invention includes the following embodiments. [1] A constituent unit (a) having a group represented by the following formula (1) or formula (2), A constituent unit (b) having a hydroxyl group, It contains a constituent unit (c) having an acid group, A copolymer characterized by having a glass transition temperature of 30°C or lower.

[0009] [ka] (In formula (1), R 1 and R 2 Each of these independently represents an alkyl group having 1 to 10 carbon atoms. * represents a linking site.

[0010] [ka] (In formula (2), R 3 (* represents an alkyl group with 1 to 10 carbon atoms. * represents a linking site.)

[0011] [2] The copolymer according to [1], wherein the constituent unit (b) is a constituent unit derived from hydroxyalkyl (meth)acrylate. [3] The copolymer according to [1] or [2], wherein the constituent unit (c) is a constituent unit derived from an unsaturated carboxylic acid. [4] The copolymer according to any one of [1] to [3], wherein the constituent unit (a) is a constituent unit derived from a compound having a group represented by formula (1) or formula (2) and a (meth)acryloyloxy group.

[0012] [5] A copolymer according to any one of [1] to [4], containing 1 to 40 mol% of the constituent unit (a), 1 to 60 mol% of the constituent unit (b), and 1 to 60 mol% of the constituent unit (c). [6] The copolymer according to any one of [1] to [5], wherein the molar ratio of the total amount of ester groups contained in the group represented by formula (1) or formula (2) to the total amount of hydroxyl groups contained in the constituent unit (b) is 10:90 to 90:10. [7] A copolymer according to any of [1] to [6], having a weight-average molecular weight of 1,000 to 50,000.

[0013] A resin composition comprising a copolymer (A) described in any of [1] to [7] and a solvent (B), wherein the solvent (B) contains a hydroxyl group-containing solvent. [9] The resin composition according to [8], further comprising a reactive diluent (C) and a photopolymerization initiator (D).

[10] The resin composition according to [9], further containing a coloring agent (E).

[0014]

[11] With respect to 100 parts by mass of the total amount of copolymer (A) and reactive diluent (C), The copolymer (A) is 10 to 90 parts by mass. The solvent (B) is 30 to 1000 parts by mass. The reactive diluent (C) is 10 to 90 parts by mass. The photopolymerization initiator (D) is 0.1 to 30 parts by mass. The resin composition according to

[10] , wherein the colorant (E) is contained in an amount of 3 to 80 parts by mass.

[0015]

[12] A color filter comprising a cured product of the resin composition according to

[10] or

[11] .

[13] An image display element comprising the color filter according to

[12] .

[0016]

[14] A solvent heating step (I) of heating the solvent (B-1) to 60 to 90°C to prepare the heated solvent (B-1h), A monomer solution in which a monomer (m-a) having a group represented by the following formula (1) or the following formula (2), a hydroxy group-containing monomer (m-b), and an acid group-containing monomer (m-c) are dissolved in a solvent (B-2) is dropped into the heated solvent (B-1h), and A dropping polymerization step (II) of dropping a polymerization initiator solution in which a polymerization initiator is dissolved in the solvent (B-2) into the solvent (B-1h) to form a mixed solution, A post-polymerization step (III) of reacting the mixed solution at 60 to 90°C for 1 to 5 hours while stirring, A method for producing a copolymer, wherein one or both of the solvent (B-1) and the solvent (B-2) contain a hydroxy group-containing solvent.

[0017] [Chemical formula] (In formula (1), R 1 and R 2 each independently represent an alkyl group having 1 to 10 carbon atoms. * represents a linking site.)

[0018] [Chemical formula] (In formula (2), R 3 represents an alkyl group having 1 to 10 carbon atoms. * represents a linking site.)

[0019]

[15] The method for producing a copolymer according to

[14] , wherein in the solvent heating step (I), a chain transfer agent is added to the solvent (B-1) before the temperature is raised. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a resin composition that has good alkali developability when used as a photosensitive material, excellent storage stability, and yields a cured product with excellent solvent resistance even when cured at low temperatures, a copolymer useful for preparing this resin composition, and a method for producing the copolymer. Furthermore, according to the present invention, it is possible to provide a color filter having a colored pattern made of a cured product of a resin composition that has good alkali developability and yields a cured product with excellent solvent resistance even when cured at low temperatures, and an image display element equipped with the color filter. [Modes for carrying out the invention]

[0021] The copolymer, method for producing the copolymer, resin composition, color filter, and image display element of the present invention will be described in detail below. However, the present invention is not limited to the embodiments shown below.

[0022] In this specification, "(meth)acrylate" refers to either acrylate or methacrylate. Similarly, "(meth)acrylic acid" refers to either acrylic acid or methacrylic acid.

[0023] <Copolymer (A)> The copolymer (A) of this embodiment contains a constituent unit (a) having a group represented by the following formula (1) or the following formula (2) (hereinafter also simply referred to as "constituent unit (a)"), a constituent unit (b) having a hydroxyl group (hereinafter also simply referred to as "constituent unit (b)"), and a constituent unit (c) having an acid group (hereinafter also simply referred to as "constituent unit (c)").

[0024] [ka] (In formula (1), R 1 and R 2 Each of these independently represents an alkyl group having 1 to 10 carbon atoms. * represents a linking site.

[0025] [ka] (In formula (2), R 3 (* represents an alkyl group with 1 to 10 carbon atoms. * represents a linking site.)

[0026] <Constituent unit (a)> The constituent unit (a) is a constituent unit derived from a monomer (ma) (hereinafter also simply referred to as "monomer (ma)") having a group represented by formula (1) or formula (2) above. The group represented by formula (1) or formula (2) of the constituent unit (a) contained in copolymer (A) undergoes transesterification with the hydroxyl group of constituent unit (b) by thermal curing of the resin composition containing copolymer (A), thereby creating a crosslinked structure. Therefore, a cured film with excellent solvent resistance can be obtained from a resin composition containing copolymer (A) even when cured at a low temperature of 50°C to 150°C.

[0027] R in equation (1) above 1 and R 2 Each of these is an alkyl group having 1 to 10 carbon atoms. 1 and R 2 Each of them is preferably an alkyl group having 2 to 6 carbon atoms, and more preferably an alkyl group having 2 to 3 carbon atoms, R 1 and R 2 It is most preferable that both are ethyl groups having 2 carbon atoms. R 1 and R 2 When is an ethyl group, when the resin composition containing copolymer (A) is heat-cured, R 1 and R 2The ethanol is produced by transesterification with the hydroxyl group of constituent unit (b). The ethanol produced during the thermal curing of the resin composition is preferable because it is easily evaporated and removed by the heating required to thermally cure the resin composition.

[0028] Also, R in equation (2) above 3 R is an alkyl group having 1 to 10 carbon atoms. 3 The group is preferably an alkyl group having 2 to 6 carbon atoms, more preferably an alkyl group having 2 to 3 carbon atoms, and even more preferably an ethyl group having 2 carbon atoms. R 3 When is an ethyl group, when the resin composition containing copolymer (A) is heat-cured, R 3 The ethanol is produced by transesterification with the hydroxyl group of constituent unit (b). The ethanol produced during the thermal curing of the resin composition is preferable because it is easily evaporated and removed by the heating required to thermally cure the resin composition.

[0029] The monomer (ma) that gives the constituent unit (a) is not particularly limited, as long as it is a compound copolymerizable with the hydroxyl group-containing monomer (mb) and acid group-containing monomer (mc) described later. As the monomer (ma), for example, from the viewpoint of reactivity when synthesizing copolymer (A), a monomer having a group represented by formula (1) or formula (2) above and an ethylenically unsaturated bond can be used. Specifically, examples of groups having an ethylenically unsaturated bond include a vinyl group and a (meth)acryloyloxy group.

[0030] Examples of monomers (ma) having a group represented by formula (1) or formula (2) above and an ethylenically unsaturated bond include reaction products of ethylenically unsaturated group-containing isocyanate compounds with malonic acid diesters or acetoacetate esters. These monomers (ma) may be used individually or in combination of two or more.

[0031] The isocyanate compound containing an ethylenically unsaturated group that generates the monomer (ma) is preferably a compound represented by the following formula (3).

[0032] [ka] (In formula (3), R 4 R represents a hydrogen atom or a methyl group. 5 -CO-, -COOR 6 -(Here, R 6 ) or -COO-R 7 O-CONH-R 8 -(Here, R 7 R is an alkylene group with 2 to 6 carbon atoms. 8 This represents an alkylene group having 2 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, which may have substituents.

[0033] R in equation (3) 4 This represents a hydrogen atom or a methyl group. R in equation (3) 5 -CO-, -COOR 6 - or -COO-R 7 O-CONH-R 8 - indicates that R 6 R is an alkylene group with 1 to 6 carbon atoms. 7 R is an alkylene group with 2 to 6 carbon atoms. 8 R is an alkylene group having 2 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, which may have substituents. Among these, R in formula (3) 5 -COOR 6 - is preferable R 5 ga-COOR 6 -If R 6 This is preferably an alkylene group having 1 to 4 carbon atoms.

[0034] Examples of isocyanate compounds containing an ethylenically unsaturated group represented by the above formula (3) include 2-isocyanatoethyl (meth)acrylate, 2-isocyanatopropyl (meth)acrylate, 3-isocyanatopropyl (meth)acrylate, 2-isocyanato-1-methylethyl (meth)acrylate, 2-isocyanato-1,1-dimethylethyl (meth)acrylate, 4-isocyanatocyclohexyl (meth)acrylate, and (meth)acryloyl isocyanate.

[0035] Furthermore, as the ethylenically unsaturated group-containing isocyanate compound represented by formula (3) above, equimolar (1 mole:1 mole) reaction products of 2-hydroxyalkyl (meth)acrylate and diisocyanate compound can also be used. The alkyl group contained in the 2-hydroxyalkyl (meth)acrylate above is preferably an ethyl group or an n-propyl group, with the ethyl group being more preferred. Examples of the diisocyanate compounds above include hexamethylene diisocyanate, 2,4-(or 2,6-)tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 3,5,5-trimethyl-3-isocyanatomethylcyclohexyl isocyanate (IPDI), m-(or p-)xylene diisocyanate, 1,3-(or 1,4-)bis(isocyanatomethyl)cyclohexane, lysine diisocyanate, and the like.

[0036] Among these ethylenically unsaturated group-containing isocyanate compounds, 2-isocyanatoethyl (meth)acrylate, 2-isocyanatopropyl (meth)acrylate, 3-isocyanatopropyl (meth)acrylate, 2-isocyanato-1-methylethyl (meth)acrylate, 2-isocyanato-1,1-dimethylethyl (meth)acrylate, 4-isocyanatocyclohexyl (meth)acrylate, and (meth)acryloyl isocyanate are preferred, with 2-isocyanatoethyl (meth)acrylate and 2-isocyanatopropyl (meth)acrylate being more preferred. These ethylenically unsaturated group-containing isocyanate compounds may be used individually or in combination of two or more.

[0037] Examples of malonic acid diesters to be reacted with ethylenically unsaturated group-containing isocyanate compounds include dimethyl malonate, diethyl malonate, di(n-propyl) malonate, and di(i-propyl) malonate. Diethyl malonate or dimethyl malonate are preferred due to their availability, cost, and quality. Examples of acetoacetate esters to be reacted with ethylenically unsaturated group-containing isocyanate compounds include methyl acetoacetate and ethyl acetoacetate.

[0038] The reaction between an ethylenically unsaturated group-containing isocyanate compound and a malonic acid diester or acetoacetate ester can be carried out with or without the presence of a solvent. When the above reaction is carried out using a solvent, a solvent that is inert to the isocyanate group should be used. In the above reaction, organometallic salts such as tin, zinc, and lead, or tertiary amines may be used as catalysts. The above reaction can generally be carried out at temperatures of -20 to 150°C, and preferably at temperatures of 25 to 130°C. A sufficient reaction rate can be obtained if the reaction temperature is above -20°C. Furthermore, if the reaction temperature is below 150°C, polymerization of the starting material having a C=C (double bond) can be prevented, which prevents the monomer (ma) that gives the constituent unit (a) generated after the reaction from gelling.

[0039] <Constituent unit having a hydroxyl group (b)> The constituent unit (b) containing a hydroxyl group in copolymer (A) does not have a group represented by formula (1) or formula (2) above, but has a hydroxyl group. Constituent unit (b) is a constituent unit derived from a monomer (mb) having a hydroxyl group (hereinafter also simply referred to as "monomer (mb)") (except for those corresponding to constituent unit (a)). The hydroxyl group of constituent unit (b) contained in copolymer (A) undergoes transesterification with the group represented by formula (1) or formula (2) of constituent unit (a) by thermal curing of the resin composition containing copolymer (A), thereby creating a crosslinked structure.

[0040] The monomer (mb) that gives the constituent unit (b) is not particularly limited, as long as it does not have a group represented by formula (1) or formula (2) above, and has a polymerizable unsaturated bond and a hydroxyl group. Examples of monomers (mb) include (meth)acrylic acid ester derivatives having a hydroxyl group. Specific examples of such monomers (mb) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. These monomers (mb) may be used individually or in combination of two or more.

[0041] Among the monomers listed above, hydroxyalkyl (meth)acrylate is preferred as the monomer (mb) from the viewpoint of its reactivity in synthesizing copolymer (A), the low-temperature curability of the resin composition containing copolymer (A), and its availability. Preferred hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, with 4-hydroxybutyl (meth)acrylate being more preferred from the viewpoint of reducing the glass transition temperature of copolymer (A).

[0042] <Constituent unit having an acid group (c)> The constituent unit (c) containing an acidic group in copolymer (A) does not have a group represented by formula (1) or formula (2) above, nor a hydroxyl group, but has an acidic group. Constituent unit (c) is a constituent unit derived from a monomer (mc) having an acidic group (hereinafter also simply referred to as "monomer (mc)") (except for those corresponding to constituent units (a) and (b)). The inclusion of constituent unit (c) in copolymer (A) results in good alkali developability when the resin composition containing copolymer (A) is used as a photosensitive material.

[0043] Examples of acidic groups that can be present in constituent unit (c) include carboxyl groups, sulfol groups, and phosphol groups. Among these acidic groups, carboxyl groups are preferred for constituent unit (c) due to their availability. The monomer (mc) that gives the constituent unit (c) is not particularly limited, as long as it does not have a group represented by formula (1) or formula (2) above, nor a hydroxyl group, and has a polymerizable unsaturated bond and an acid group. Examples of monomers (mc) include unsaturated carboxylic acids or their anhydrides, unsaturated sulfonic acids, unsaturated phosphonic acids, and the like.

[0044] Examples of monomers (mc) include unsaturated carboxylic acids or their anhydrides such as (meth)acrylic acid, α-bromo(meth)acrylic acid, β-furyl(meth)acrylic acid, crotonic acid, propiolic acid, cinnamic acid, α-cyanocinnamic acid, maleic acid, maleic anhydride, monomethyl maleate, monoethyl maleate, monoisopropyl maleate, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, and citraconic anhydride; unsaturated sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid, tert-butylacrylamidosulfonic acid, and p-styrenesulfonic acid; and unsaturated phosphonic acids such as vinylphosphonic acid. These monomers (mc) may be used individually or in combination of two or more.

[0045] As for the monomer (mc), among these monomers, it is preferable to use an unsaturated carboxylic acid, and more preferably (meth)acrylic acid, because it is readily available and the resin composition containing copolymer (A) has excellent alkali developability.

[0046] Here, we will explain the proportions of constituent units (a), (b), and (c) contained in copolymer (A). The proportion of constituent units (a) contained in copolymer (A) is not particularly limited, but is preferably 1 to 40 mol%, more preferably 5 to 30 mol%, and most preferably 10 to 20 mol%. The proportion of constituent units (b) contained in copolymer (A) is not particularly limited, but is preferably 1 to 60 mol%, more preferably 10 to 50 mol%, and most preferably 20 to 40 mol%. The proportion of constituent units (c) contained in copolymer (A) is not particularly limited, but is preferably 1 to 60 mol%, more preferably 10 to 50 mol%, and most preferably 15 to 40 mol%.

[0047] Therefore, copolymer (A) preferably contains 1 to 40 mol% of constituent unit (a), 1 to 60 mol% of constituent unit (b), and 1 to 60 mol% of constituent unit (c). In the copolymer (A) of this embodiment, when the proportion of constituent units (a) and (b) is 1 mol% or more, when the resin composition containing copolymer (A) is heat-cured, the hydroxyl group of constituent unit (b) and the group represented by formula (1) or formula (2) of constituent unit (a) undergo transesterification. As a result, a sufficiently crosslinked structure is formed. Therefore, a resin composition containing copolymer (A) containing 1 mol% or more of each of constituent units (a) and (b) yields a cured product with good solvent resistance even when heat-cured at low temperatures.

[0048] When the proportion of constituent unit (a) in copolymer (A) is 40 mol% or less, the storage stability of the resin composition containing copolymer (A) is improved. Furthermore, when the proportion of constituent unit (a) is 40 mol% or less, it becomes easier to ensure sufficient content of constituent units (b) and (c). Therefore, the effects of including constituent units (b) and (c) become easier to obtain.

[0049] Furthermore, if the proportion of constituent unit (b) in copolymer (A) is 60 mol% or less, gelation during the polymerization reaction for producing copolymer (A) can be prevented. In addition, excessive cross-linking structures are not formed by the transesterification reaction between constituent unit (a) and constituent unit (b), resulting in better storage stability of the resin composition containing copolymer (A). Moreover, if the proportion of constituent unit (b) is 60 mol% or less, it becomes easier to ensure sufficient content of constituent unit (a) and constituent unit (c). Therefore, the effects of including constituent unit (a) and constituent unit (c) are more easily obtained.

[0050] If the proportion of constituent unit (c) in copolymer (A) is 1 mol% or more, the resin composition containing copolymer (A) will have a sufficiently fast alkaline development rate. If the proportion of constituent unit (c) in copolymer (A) is 60 mol% or less, the alkaline development rate of the resin composition containing copolymer (A) is moderately suppressed, making it easier to form fine patterns. Furthermore, if the proportion of constituent unit (c) in copolymer (A) is 60 mol% or less, it becomes easier to ensure the content of constituent unit (a) and constituent unit (b). For this reason, even when cured at low temperatures, the resin composition containing copolymer (A) is more likely to yield a cured product with superior solvent resistance.

[0051] In copolymer (A), the molar ratio of ester groups to hydroxyl groups ((a):(b)) is preferably 10:90 to 90:10, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40. The molar ratio of ester groups to hydroxyl groups ((a):(b)) is the molar ratio of the total amount of ester groups represented by formula (1) or formula (2) in constituent unit (a) to the total amount of hydroxyl groups contained in constituent unit (b). When the molar ratio of ester groups to hydroxyl groups ((a):(b)) is within the above range, when the resin composition containing copolymer (A) is heat-cured, a cross-linked structure is more easily formed by transesterification between the hydroxyl groups of constituent unit (b) and the groups represented by formula (1) or formula (2) in constituent unit (a). As a result, a cured product with even better solvent resistance can be obtained.

[0052] The total amount of constituent unit (a) and constituent unit (b) contained in copolymer (A) is preferably 20 to 80 mol%, more preferably 20 to 60 mol%, and even more preferably 25 to 40 mol%. When the total amount of constituent unit (a) and constituent unit (b) is 20 to 80 mol%, the resin composition containing copolymer (A) has better storage stability, and even when cured at low temperatures, a cured product with excellent solvent resistance can be obtained. In addition, it becomes easier to ensure a sufficient content of constituent unit (c), making it easier to obtain a resin composition with better alkali developability when used as a photosensitive material.

[0053] When a resin composition containing copolymer (A) also contains a compound having a hydroxyl group as a reactive diluent (C) in addition to copolymer (A), it is preferable that the total amount of hydroxyl groups on the constituent units (b) contained in copolymer (A) be reduced in proportion to the amount of hydroxyl groups contained in the reactive diluent (C). Specifically, the molar ratio of the total amount of ester groups in formula (1) or formula (2) of constituent unit (a) to the total amount of hydroxyl groups contained in the resin composition is preferably 10:90 to 90:10, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40. The total amount of hydroxyl groups contained in the resin composition is the sum of the hydroxyl groups of constituent unit (b) and the hydroxyl groups contained in the reactive diluent (C). When the above molar ratio is within the above range, when the resin composition containing copolymer (A) is heat-cured, a cross-linked structure is more easily formed by transesterification between the hydroxyl groups contained in the resin composition and the group represented by formula (1) or formula (2) of constituent unit (a). As a result, a cured product with even better solvent resistance can be obtained.

[0054] <Other constituent units (d)> The copolymer (A) of this embodiment may optionally contain other copolymerizable constituent units (d) (excluding those corresponding to constituent units (a) to (c)) along with constituent units (a) to (c).

[0055] The monomer (md) that provides the other constituent unit (d) (hereinafter also simply referred to as "monomer (md)") preferably does not contain blocking agents such as compounds having a blocked isocyanate group. If the copolymer (A) contains constituent units derived from a blocking agent, the blocking agent may remain in the cured product obtained by coating, exposing, developing, and then heating the resin composition containing it. The blocking agent remaining in the cured product may adversely affect the insulating properties of the cured product or degrade the solvent resistance of the cured product. In addition, the blocking agent remaining in the cured product may cause dark spots due to degassing in an image display element equipped with a color filter having a colored pattern made of the cured product.

[0056] Specific examples of monomers (md) that provide other constituent units (d) include aromatic vinyl compounds, cyclic olefins having a norbornene structure, dienes, (meth)acrylic acid esters, (meth)acrylic acid esters, (meth)acrylamide, vinyl compounds, unsaturated dicarboxylic acid diesters, monomaleimides, glycidyl (meth)acrylate, (meth)acrylic acid anilide, (meth)acrylonitrile, acrolein, and the like. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, o-vinyltoluene, p-vinyltoluene, o-chlorostyrene, m-chlorostyrene, methoxystyrene, p-nitrostyrene, p-cyanostyrene, and p-acetylaminostyrene. Examples of cyclic olefins having a norbornene structure include norbornene (bicyclo[2.2.1]hept-2-ene), 5-methylbicyclo[2.2.1]hept-2-ene, and tetracyclo[4.4.0.1 2,5 .1 7,10 ] Dodeca-3-ene, 8-ethyltetracyclo[4.4.0.1 2,5.1 7,10 ] Dodeca-3-ene, dicyclopentadiene, tricyclo[5.2.1.0 2,6 Deca-8-en, tricyclo[4.4.0.1 2,5 ]Undeca-3-ene, tricyclo[6.2.1.0 1,8 ]Undeka-9-ene, tetracyclo[4.4.0.1 2,5 .1 7,10 .0 1,6 ] Dodeca-3-ene, 8-ethylidenetetracyclo[4.4.0.1 2,5 .1 7,12 ] Dodeca-3-ene, pentacyclo[6.5.1.1 3,6 .0 2,7 .0 9,13 Examples include pentadeca-4-en. Examples of dienes include butadiene, isoprene, and chloroprene. Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, benzyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, rosin (meth)acrylate, norbornyl (meth)acrylate, 5-ethylnorbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate. Examples include acrylates, tetrahydrofurfuryl (meth)acrylate, 1,1,1-trifluoroethyl (meth)acrylate, perfluoroethyl (meth)acrylate, perfluoro-n-propyl (meth)acrylate, 3-(N,N-dimethylamino)propyl (meth)acrylate, triphenylmethyl (meth)acrylate, phenyl (meth)acrylate, cumyl (meth)acrylate, 4-phenoxyphenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol mono (meth)acrylate, biphenyloxyethyl (meth)acrylate, naphthalene (meth)acrylate, anthracene (meth)acrylate, and ethoxylated phenyl (meth)acrylate. Examples of (meth)acrylamide include (meth)acrylamide, (meth)acrylate N,N-dimethylamide, (meth)acrylate N,N-diisopropylamide, and (meth)acrylate anthracenilamide. Examples of vinyl compounds include vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, N-vinylpyrrolidone, vinylpyridine, vinyl acetate, and vinyltoluene. Examples of unsaturated dicarboxylic acid diesters include diethyl citraconate, diethyl maleate, diethyl fumarate, and diethyl itaconate. Examples of monomaleimides include N-phenylmaleimide, N-cyclohexylmaleimide, N-laurylmaleimide, and N-(4-hydroxyphenyl)maleimide.

[0057] Among these, it is preferable to use (meth)acrylic acid ester as the monomer (md), and from the viewpoint of adjusting the glass transition temperature of copolymer (A) to 30°C or below, it is preferable that the glass transition temperature of the homopolymer be -20°C or below, and it is particularly preferable to use 2-ethylhexyl (meth)acrylate or 4-hydroxybutyl acrylate. These monomers (md) may be used alone or in combination of two or more.

[0058] If copolymer (A) contains other constituent units (d), the proportion is not particularly limited, but is preferably greater than 0 mol% to 80 mol%, more preferably 10 to 60 mol%, and most preferably 15 to 50 mol%. By including other constituent units (d) in copolymer (A), properties such as solvent resistance in the cured product of the resin composition containing copolymer (A) can be appropriately improved. When the content of other constituent units (d) is 80 mol% or less, it becomes easier to ensure the content of constituent units (a) to (c), and the effects of including constituent units (a) to (c) become more pronounced.

[0059] (Weight average molecular weight (Mw)) The weight-average molecular weight of copolymer (A) in terms of polystyrene is not particularly limited, but is preferably 1,000 to 50,000, more preferably 3,000 to 40,000. When the weight-average molecular weight of copolymer (A) is 1,000 or more, the alkali developability is good when the resin composition containing copolymer (A) is used as a photosensitive material, and pattern defects are less likely to occur after alkali development. On the other hand, when the weight-average molecular weight of copolymer (A) is 50,000 or less, the development time is appropriate when the resin composition containing copolymer (A) is used as a photosensitive material, and practicality is ensured.

[0060] (Glass transition temperature (Tg)) The glass transition temperature (Tg) of copolymer (A) is 30°C or lower, preferably 20°C or lower, and more preferably 0°C or lower. If the glass transition temperature of copolymer (A) is above 30°C, it adversely affects the curability at low temperatures. For this reason, the glass transition temperature of copolymer (A) is set to 30°C or lower. The glass transition temperature of copolymer (A) is preferably -50°C or higher, more preferably -40°C or higher, and even more preferably -30°C or higher. If the glass transition temperature of copolymer (A) is -50°C or higher, the resin composition containing copolymer (A) will yield a cured film with excellent heat resistance.

[0061] (Acid value) The acid value of copolymer (A) (JIS K6901 5.3) can be selected as appropriate. When the resin composition containing copolymer (A) is used as a photosensitive material, the acid value of copolymer (A) is preferably 20 to 300 KOH mg / g, and more preferably 30 to 200 KOH mg / g. If the acid value of copolymer (A) is 20 KOH mg / g or higher, the alkali developability is good when the resin composition containing copolymer (A) is used as a photosensitive material. On the other hand, if the acid value of copolymer (A) is 300 KOH mg / g or lower, when the resin composition containing copolymer (A) is used as a photosensitive material, the exposed portion (photocured portion) becomes less likely to dissolve in the alkaline developer, resulting in a good pattern shape.

[0062] (Equivalent number of the base represented by formula (1) or formula (2) above) Copolymer (A) contains a group represented by formula (1) or formula (2) in its molecule. The equivalent number of the group represented by formula (1) or formula (2) can be selected as appropriate, but is preferably 300 to 6000, and more preferably 1000 to 3000. When the equivalent number of the group represented by formula (1) or formula (2) is 300 or more, if there are a sufficient number of hydroxyl groups in the resin composition containing copolymer (A), then by thermal curing, a sufficiently cross-linked structure is formed by transesterification between the hydroxyl groups in the resin composition and the group represented by formula (1) or formula (2) of the constituent unit (a). As a result, a cured product with even better solvent resistance can be obtained.

[0063] The equivalent number of groups represented by formula (1) or formula (2) in copolymer (A) is the mass of copolymer (A) per mole of groups represented by formula (1) or formula (2) contained in copolymer (A). The equivalent number of groups represented by formula (1) or formula (2) can be determined by dividing the mass of copolymer (A) by the number of moles of groups represented by formula (1) or formula (2) contained in copolymer (A) (g / mol). The equivalent number of groups represented by formula (1) or formula (2) is a theoretical value calculated from the amount of monomer (ma) charged. In practice, as described in the method for producing copolymer (A) later, some of the groups represented by formula (1) or formula (2) in copolymer (A) are transesterified with hydroxyl groups derived from monomer (mb), or with hydroxyl groups of hydroxyl group-containing solvents that can be used as solvent (B-1) and / or solvent (B-2).

[0064] <Method for producing copolymer (A)> The copolymer (A) of this embodiment can be produced, for example, by using a method in which the solvent heating step (I), dropwise polymerization step (II), and post-polymerization step (III) are carried out in this order. (Solvent heating process (I)) The solvent (B-1) is heated to 60-90°C to prepare the heated solvent (B-1h). In the solvent heating step (I), the chain transfer agent described later may be added to the solvent (B-1) before heating. By adding the chain transfer agent to the solvent (B-1) before heating, the degree of polymerization of the copolymer (A) synthesized in the dropwise polymerization step (II) and the post-polymerization step (III) can be controlled. The concentration of the chain transfer agent in the solvent (B-1) can be, for example, 0.1 to 10% by mass, and is not particularly limited.

[0065] (Drop polymerization step (II)) Droplet polymerization is carried out by stirring the heated solvent (B-1h) and adding the polymerization initiator solution dropwise to the heated solvent (B-1h) along with the monomer solution to form a mixed solution. The monomer solution is prepared by dissolving a monomer (ma) having a group represented by formula (1) or formula (2) above, a hydroxyl group-containing monomer (mb), an acid group-containing monomer (mc), and a monomer (md) used as needed, in a solvent (B-2). The polymerization initiator solution is prepared by dissolving the polymerization initiator in solvent (B-2). In the method for producing copolymer (A) of this embodiment, either or both of solvent (B-1) and solvent (B-2) contain a hydroxyl group-containing solvent.

[0066] In the sublime polymerization step (II), the chain transfer agent solution described later may be added dropwise instead of the chain transfer agent that can be added in the solvent heating step (I). The chain transfer agent solution is obtained by dissolving the chain transfer agent in solvent (B-2). Alternatively, in the solvent heating step (I), a portion of the chain transfer agent to be used in the production of copolymer (A) may be added to solvent (B-1) and then heated, and in the sublime polymerization step (II), the remaining portion of the chain transfer agent to be used, after removing a portion, may be dissolved in solvent (B-2) to create a chain transfer agent solution, which may be added dropwise to the heated solvent (B-1h).

[0067] (Post-polymerization step (III)) After the monomer solution and polymerization initiator solution have been added dropwise, the mixed solution is reacted at 60-90°C for 1-5 hours while stirring.

[0068] "Solvent (B-1)" The solvent (B-1) used in the solvent heating step (I) may consist solely of a hydroxyl group-containing solvent, solely of a solvent that does not contain a hydroxyl group, or both a hydroxyl group-containing solvent and a solvent that does not contain a hydroxyl group. It is preferable that solvent (B-1) contains a hydroxyl group-containing solvent, and more preferably consists solely of a hydroxyl group-containing solvent.

[0069] Examples of hydroxyl group-containing solvents include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; hydroxyl group-containing carboxylic acid esters such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl hydroxyethyl acetate, and methyl 2-hydroxy-3-methylbutyrate; 3-methoxy-1-butanol; and diethylene glycol.

[0070] Among these hydroxyl group-containing solvents, primary and / or secondary alcohol solvents and ether-based solvents are preferred because they have a high effect in inhibiting the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) in the dropwise polymerization step (II) and / or post-polymerization step (III). In particular, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and 3-methoxy-1-butanol are more preferred. These hydroxyl group-containing solvents may be used individually or in combination of two or more.

[0071] Examples of solvents that do not contain hydroxyl groups include (poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and tetrahydrofuran; ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone; and methyl 3-methoxypropionate, 3-ethyl ether. Examples include esters such as methyl toxypropionate, ethyl ethoxyacetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, ethyl acetate, n-butyl acetate, i-propyl acetate, i-butyl acetate, n-amyl acetate, i-amyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutyrate; aromatic hydrocarbons such as toluene and xylene; and carboxylic acid amides such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0072] Among solvents that do not contain hydroxyl groups, ether-based solvents are preferred from the viewpoint of availability, cost, and quality, and propylene glycol monomethyl ether acetate and diethylene glycol methyl ethyl ether are more preferred. These solvents that do not contain hydroxyl groups may be used individually or in combination of two or more.

[0073] If the solvent (B-1) used in the solvent heating step (I) contains a hydroxyl group-containing solvent, the content of the hydroxyl group-containing solvent in the solvent (B-1) is preferably 10 to 100% by mass, more preferably 20 to 90% by mass, and even more preferably 40 to 80% by mass. If the content of the hydroxyl group-containing solvent is 10% by mass or more, a sufficient effect of inhibiting the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) is obtained in the dropwise polymerization step (II) and / or post-polymerization step (III). If the solvent (B-1) contains a solvent that does not contain hydroxyl groups, the effect of increasing the amount of ester group derived from monomer (ma) in the copolymer (A) and improving the amount of crosslinking reaction by the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) when curing the resin composition is obtained.

[0074] "Temperature of solvents and mixed solutions" In the manufacturing method of this embodiment, in the solvent heating step (I), solvent (B-1) is placed in the reaction vessel and the temperature is raised to 60-90°C. In the dropwise polymerization step (II) and post-polymerization step (III), the mixed solution is stirred and reacted at 60-90°C for 1-5 hours. The temperature of the solvent (B-1h) in the solvent heating step (I) and the temperature of the mixed solution in the dropwise polymerization step (II) and the post-polymerization step (III) may be the same or different.

[0075] In this embodiment, the temperature of the solvent (B-1h) in the solvent heating step (I) is 60°C or higher, and the temperature of the mixed solution in the dropwise polymerization step (II) and post-polymerization step (III) is 60°C or higher. Therefore, the polymerization reaction of monomers (ma) to (mc) and monomers (md) used as needed proceeds sufficiently in the dropwise polymerization step (II) and post-polymerization step (III).

[0076] Since the temperature of the solvent (B-1h) in the solvent heating step (I) is 90°C or lower, and the temperature of the mixed solution in the dropwise polymerization step (II) and post-polymerization step (III) is 90°C or lower, the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) can be suppressed in the dropwise polymerization step (II) and post-polymerization step (III). Furthermore, when the above temperature is 90°C or lower, if the reaction product of an ethylenically unsaturated group-containing isocyanate compound and a malonic acid diester or acetoacetate ester is used as monomer (ma), the following effect can be obtained. That is, in the dropwise polymerization step (II) and post-polymerization step (III), the dissociation of the malonic acid diester or acetoacetate ester from the group represented by formula (1) or formula (2) above, and the generation of an isocyanate group can be prevented. Therefore, it is possible to prevent the copolymer (A) from gelling during production by the reaction of the isocyanate group generated by the dissociation of the group represented by formula (1) or formula (2) with the hydroxyl group derived from monomer (mb) or the acid group derived from monomer (mc).

[0077] In the dropwise polymerization step (II), the polymerization initiator solution and the monomer solution are added dropwise to the solvent (B-1h) heated to 60-90°C in the solvent heating step (I) to form a mixed solution and carry out polymerization. In the dropwise polymerization step (II), the chain transfer agent solution may also be added dropwise to the heated solvent (B-1h) to form a mixed solution containing the chain transfer agent.

[0078] In the dropwise polymerization step (II), it is preferable to simultaneously dropwise add the polymerization initiator solution and the monomer solution to the heated solvent (B-1h). In this case, the molecular weight of the copolymer (A) can be controlled with high precision, and the copolymer (A) can be prevented from gelling during the manufacturing process. In the dropwise polymerization step (II), when the chain transfer agent solution is added dropwise to the heated solvent (B-1h), the chain transfer agent solution may be added dropwise at the same time as the polymerization initiator solution and the monomer solution. Alternatively, the chain transfer agent solution may be added dropwise before or after the polymerization initiator solution and the monomer solution.

[0079] The dropping rates of the polymerization initiator solution, monomer solution, and chain transfer agent solution can be appropriately determined according to the reaction scale, such as the volume of the reaction vessel and the volumes of the heated solvent (B-1h), polymerization initiator solution, monomer solution, and chain transfer agent solution. For example, when using a 1 L reaction vessel, the dropping rates of the polymerization initiator solution, monomer solution, and chain transfer agent solution are preferably 0.1 to 5 mL / min. The dropping time for the polymerization initiator solution, monomer solution, and chain transfer agent solution can be, for example, 30 minutes to 1 hour. The dropping rates and dropping times of the polymerization initiator solution, monomer solution, and chain transfer agent solution may be different for each, or some or all of them may be the same.

[0080] In this embodiment, the polymerization initiator solution, the monomer solution, and the chain transfer agent solution, which is used as needed, are each prepared separately. (Polymerization initiator solution) The polymerization initiator solution is prepared by dissolving the polymerization initiator in solvent (B-2). Polymerization initiators are not particularly limited, but examples include 2,2'-azobis(2,4-dimethylvaleronitrile), azobisisobutyronitrile, azobisisovaleronitrile, benzoyl peroxide, and t-butylperoxy-2-ethylhexanoate. These polymerization initiators may be used individually or in combination of two or more.

[0081] The concentration of the polymerization initiator in the polymerization initiator solution is preferably such that a uniformly concentrated mixed solution can be easily obtained. For example, it can be 16 to 50% by mass, and is not particularly limited. The amount of polymerization initiator solution used is preferably 0.5 to 20 parts by mass of polymerization initiator per 100 parts by mass of the total amount of monomer charged, and more preferably 1.0 to 10 parts by mass. The total amount of monomer charged is the mass of monomers (ma) to (md) in the monomer solution.

[0082] (Monomer solution) The monomer solution is prepared by dissolving a monomer (ma) having a group represented by formula (1) or formula (2) above, a hydroxyl group-containing monomer (mb), an acid group-containing monomer (mc), and a monomer (md) used as needed, in solvent (B-2). The monomers (ma) to (md) can be those exemplified in the section on copolymers (A).

[0083] The monomer solution may be prepared by dissolving each monomer (ma) to (md) individually in solvent (B-2) and then mixing them, or by mixing the monomers (ma) to (md) and then dissolving them in solvent (B-2). The total concentration of monomers (ma) to (md) in the monomer solution is preferably such that a uniformly concentrated mixed solution can be easily obtained. For example, it can be 50 to 95% by mass, but is not particularly limited.

[0084] The proportions of each monomer (ma) to (mc) used in the production of copolymer (A) are not particularly limited, but it is preferably 1 to 40 mol% of monomer (ma), 1 to 60 mol% of monomer (mb), and 1 to 60 mol% of monomer (mc), more preferably 5 to 30 mol% of monomer (ma), 10 to 50 mol% of monomer (mb), and 10 to 50 mol% of monomer (mc), and even more preferably 10 to 20 mol% of monomer (ma), 20 to 40 mol% of monomer (mb), and 15 to 40 mol% of monomer (mc).

[0085] When copolymer (A) contains constituent units (d), there are no particular restrictions on the proportions of each monomer (ma) to (md) used in the production of copolymer (A), but it is preferable that monomer (ma) be 1 to 40 mol%, monomer (mb) be 1 to 60 mol%, monomer (mc) be 1 to 60 mol%, and monomer (md) be more than 0 to 80 mol%, more preferably monomer (ma) be 5 to 30 mol%, monomer (mb) be 10 to 50 mol%, monomer (mc) be 10 to 50 mol%, and monomer (md) be 10 to 60 mol%, and even more preferably monomer (ma) be 10 to 20 mol%, monomer (mb) be 20 to 40 mol%, monomer (mc) be 15 to 40 mol%, and monomer (md) be 15 to 50 mol%.

[0086] (Chain transfer agent solution) The chain transfer agent solution is prepared by dissolving the chain transfer agent in solvent (B-2). In the dropwise polymerization step (II), the degree of polymerization of copolymer (A) synthesized in the post-polymerization step (III) can be controlled by adding the chain transfer agent solution dropwise. Therefore, copolymer (A) within a desired molecular weight range can be easily produced. The chain transfer agent is not particularly limited, but for example, polyfunctional thiols can be preferably used. A polyfunctional thiol is a compound having two or more mercapto groups in its molecule.

[0087] Polyfunctional thiols are not particularly limited, but examples include thioglycolic acid, 1,2-ethanedithiol, 1,4-bis(3-mercaptobutyryloxy)butane, tetraethylene glycol bis(3-mercaptopropionate), trimethylolethanetris(3-mercaptobutyrate), trimethylolpropanetris(3-mercaptobutyrate), trimethylolpropanetris(3-mercaptopropionate), and pentae. Examples include lysritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, and dipentaethythritol hexakis(3-mercaptopropionate).

[0088] Among the above, pentaerythritol tetrakis(3-mercaptobutyrate) and / or thioglycolic acid, or pentaerythritol tetrakis(3-mercaptopropionate) is preferred as the chain transfer agent, from the viewpoint of ease of availability, cost, and quality. The concentration of the chain transfer agent in the polymerization initiator solution is preferably such that a uniformly concentrated mixed solution can be easily obtained. For example, it can be 0.1 to 10% by mass, and is not particularly limited.

[0089] The amount of chain transfer agent solution used is preferably 0.5 to 20 parts by mass, and more preferably 1.0 to 10 parts by mass, of the total amount of monomer charged in the mixed solution. The total amount of monomer charged is, that is, the mass of monomers (ma) to (md) in the monomer solution. By using the amount of chain transfer agent solution within the above range, copolymers (A) with a desired molecular weight range can be easily produced in the post-polymerization step (III).

[0090] "Solvent (B-2)" The solvent (B-2) used in the dropwise polymerization step (II) can be the same as the solvent (B-1) used in the solvent heating step (I). The solvent (B-2), like solvent (B-1), may consist solely of a hydroxyl group-containing solvent, solely of a solvent without hydroxyl groups, or a mixture of both a hydroxyl group-containing solvent and a solvent without hydroxyl groups. It is preferable that the solvent (B-2) contains a hydroxyl group-containing solvent, and more preferably consists solely of a hydroxyl group-containing solvent.

[0091] In the method for producing copolymer (A) of this embodiment, either or both of the solvents (B-1) and (B-2) contain a hydroxyl group-containing solvent. Therefore, if the solvent (B-1) used in the solvent heating step (I) does not contain a hydroxyl group-containing solvent, the solvent (B-2) used in the dropwise polymerization step (II) contains a hydroxyl group-containing solvent.

[0092] The content of the hydroxyl group-containing solvent in the total amount of solvent (B-1) used in the solvent heating step (I) and solvent (B-2) used in the dropwise polymerization step (II) is preferably 10 to 100% by mass, more preferably 20 to 90% by mass, and even more preferably 40 to 80% by mass. When the content of the hydroxyl group-containing solvent is 10% by mass or more, a sufficient effect of inhibiting the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) is obtained in the dropwise polymerization step (II) and / or post-polymerization step (III). If one or both of solvent (B-1) and solvent (B-2) contain a solvent that does not contain hydroxyl groups, when the content of the hydroxyl group-containing solvent is 90% by mass or less, an effect is obtained in which the amount of ester group derived from monomer (ma) in the copolymer (A) is increased, and the amount of crosslinking reaction by the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) is increased when curing the resin composition.

[0093] In the manufacturing method of this embodiment, since the solvent (B-1) used in the solvent heating step (I) and / or the solvent (B-2) used in the dropwise polymerization step (II) contains a hydroxyl group-containing solvent, the following effects can be obtained. When monomers (ma), (mb), (mc), and optionally monomer (md) are polymerized at 60-90°C in a mixed solution containing a hydroxyl group-containing solvent, the ester groups derived from monomer (ma) readily undergo transesterification with the hydroxyl groups of the hydroxyl group-containing solvent. Thus, in the dropwise polymerization step (II) and / or post-polymerization step (III), a portion of the ester groups of the group represented by formula (1) or formula (2) on monomer (ma) undergoes transesterification with the hydroxyl groups of the hydroxyl group-containing solvent.

[0094] When an ester group derived from a monomer (ma) undergoes a transesterification reaction with a hydroxyl group-containing solvent, the mixed solution contains a group derived from the ester group of the monomer (ma) (R in formula (1)). 1 and R 2 , or R in equation (2) 3 An alcohol containing ) is produced. Since this reaction is reversible, a portion of the produced alcohol undergoes a transesterification reaction (reverse reaction) with the compound produced by the transesterification reaction, producing a monomer (ma) and a hydroxyl group-containing solvent. As a result, even if the ester group derived from monomer (ma) undergoes a transesterification reaction with the hydroxyl group of the hydroxyl group-containing solvent, it is presumed that an appropriate amount of the ester group derived from monomer (ma) remains in the mixed solution.

[0095] When the monomer (ma) has a group represented by formula (1), for example, R in formula (1) 1 When the hydroxyl group of the hydroxyl group-containing solvent undergoes a transesterification reaction, the R in formula (1) of the resulting compound 1 The group that reacted with it becomes sterically hindered, and R in equation (1) 2This makes it less likely for the transesterification reaction between the monomer (ma) and the hydroxyl group to occur. As a result, when the monomer (ma) has a group represented by formula (1), it is presumed that only a portion of the ester groups derived from the monomer (ma) undergoes a transesterification reaction with the hydroxyl group of the hydroxyl group-containing solvent, leaving an appropriate amount of ester groups derived from the monomer (ma) remaining.

[0096] Thus, in this embodiment, in the dropwise polymerization step (II) and / or post-polymerization step (III), the ester group derived from monomer (ma) undergoes a transesterification reaction with the hydroxyl group of the hydroxyl group-containing solvent, so the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) is moderately inhibited. Therefore, gelation of the copolymer (A) during the manufacturing process can be prevented in the post-polymerization step (III). In addition, the storage stability of the resin composition containing copolymer (A) is improved.

[0097] Furthermore, in this embodiment, the transesterification reaction in the dropwise polymerization step (II) and / or post-polymerization step (III) is moderately inhibited, thereby preventing a decrease in the ester groups derived from monomer (ma) and hydroxyl groups derived from monomer (mb) before the resin composition containing copolymer (A) is thermally cured. As a result, copolymer (A) is obtained in which a moderate amount of ester groups derived from monomer (ma) and hydroxyl groups derived from monomer (mb) remain. In addition, the compound produced by the transesterification reaction between the ester groups derived from monomer (ma) and the hydroxyl groups of the hydroxyl group-containing solvent forms a crosslinked structure by transesterification with monomer (mb). Therefore, by thermally curing the resin composition containing copolymer (A), a sufficiently crosslinked structure is formed by transesterification between the ester groups derived from monomer (ma) and the hydroxyl groups derived from monomer (mb), resulting in a cured product with good solvent resistance.

[0098] The amounts of solvent (B-1) used in the solvent heating step (I) and solvent (B-2) used in the dropwise polymerization step (II) are not particularly limited, but for 100 parts by mass of the total amount of monomer charged (i.e., the mass of monomers (ma) to monomers (md) in the monomer solution), the total amount of solvent (B-1) and solvent (B-2) is preferably 30 to 1,000 parts by mass, and more preferably 50 to 800 parts by mass. When the total amount of solvent (B-1) and solvent (B-2) is 1,000 parts by mass or less per 100 parts by mass of the total amount of monomer charged, the viscosity of the reaction solution containing copolymer (A) obtained in the post-polymerization step (III) will be appropriate. Furthermore, by keeping the total amount of solvent (B-1) and solvent (B-2) at 1,000 parts by mass or less, the decrease in molecular weight of copolymer (A) due to chain transfer action can be suppressed when the chain transfer agent solution is added dropwise in the dropwise polymerization step (II). Furthermore, by ensuring that the total amount of solvent (B-1) and solvent (B-2) is 30 parts by mass or more per 100 parts by mass of the total amount of monomer charged, abnormal polymerization reactions in the post-polymerization step (III) can be prevented, and the polymerization reaction can be carried out stably. As a result, it is possible to prevent the copolymer (A) from gelling during production, and a colorless copolymer (A) can be obtained.

[0099] In the manufacturing method of this embodiment, in the post-polymerization step (III), the mixed solution obtained in the dropwise polymerization step (II) is reacted at 60-90°C for 1-5 hours while stirring. The reaction time in the post-polymerization step (III) can be 1-5 hours, preferably 1-4 hours, and more preferably 2-3 hours. When the reaction time is 1-5 hours, copolymer (A) having an appropriate molecular weight can be produced in good yield.

[0100] The copolymer (A) of this embodiment contains a constituent unit (a) having a group represented by formula (1) or formula (2) above, a constituent unit (b) having a hydroxyl group, and a constituent unit (c) having an acid group, and has a glass transition temperature of 30°C or lower. For this reason, the resin composition containing the copolymer (A) of this embodiment has good alkali developability when used as a photosensitive material, excellent storage stability, and a cured product with excellent solvent resistance can be obtained even when cured at low temperatures.

[0101] In the production method for copolymer (A) of this embodiment, the solvent (B-1) used in the solvent heating step (I) and / or the solvent (B-2) used in the dropwise polymerization step (II) are solvents containing a hydroxyl group. In the solvent heating step (I), the solvent (B-1) is heated to 60-90°C, and in the post-polymerization step (III), the mixed solution is reacted at 60-90°C. As a result, in the dropwise polymerization step (II) and / or the post-polymerization step (III), the transesterification reaction between the ester group derived from monomer (ma) and the hydroxyl group derived from monomer (mb) is moderately inhibited. As a result, copolymer (A) of this embodiment is obtained that sufficiently contains constituent units (a) having the group represented by formula (1) or formula (2) above and constituent units (b) having a hydroxyl group.

[0102] In contrast, conventional methods used when using solvents in copolymer polymerization selected solvents that did not react with monomers. Therefore, in conventional techniques, there was no reaction between monomers and solvents when copolymerizing copolymers using solvents. Consequently, conventional techniques did not anticipate utilizing reactions between monomers and solvents, and there was no method to control the properties of copolymers by utilizing reactions between monomers and solvents.

[0103] <Resin composition> Next, the resin composition of this embodiment will be described. The resin composition of this embodiment contains the copolymer (A) and the solvent (B). The resin composition of this embodiment may further contain not only a copolymer (A) and a solvent (B), but also a reactive diluent (C) and a photopolymerization initiator (D). Such a resin composition can preferably be used as a photosensitive resin composition. The resin composition of this embodiment may further contain a colorant (E) in addition to the copolymer (A) to the photopolymerization initiator (D). Such a resin composition can be preferably used as a material for forming colored patterns such as color filters, black matrices, and black column spacers.

[0104] (Solvent (B)) In the resin composition of this embodiment, solvent (B) includes a hydroxyl group-containing solvent. Solvent (B) may consist solely of a hydroxyl group-containing solvent. In the resin composition of this embodiment, because solvent (B) includes a hydroxyl group-containing solvent, the ester group of the constituent unit (a) of copolymer (A) undergoes a transesterification reaction with the hydroxyl group of the hydroxyl group-containing solvent contained in solvent (B). This moderately inhibits the transesterification reaction between the ester group of constituent unit (a) and the hydroxyl group of constituent unit (b), thereby improving storage stability.

[0105] The hydroxyl group-containing solvent used as solvent (B) is not particularly limited as long as it contains a hydroxyl group, and the same solvents that can be used as solvent (B-1) and solvent (B-2) in the process of producing copolymer (A) can be used. Examples of solvents that do not contain a hydroxyl group and can be used as solvent (B) are the same solvents that can be used as solvent (B-1) and solvent (B-2) in the process of producing copolymer (A).

[0106] The proportion of hydroxyl group-containing solvent in solvent (B) can be set in the same manner as the proportion of hydroxyl group-containing solvent in solvent (B-1) used in the process of producing copolymer (A). Solvent (B) may be the same as or different from solvent (B-1) and / or solvent (B-2) used in the process of producing copolymer (A).

[0107] The resin composition of this embodiment can be produced by appropriately mixing copolymer (A) isolated from a reaction solution containing copolymer (A) obtained in a postpolymerization step (III) for producing copolymer (A), with solvent (B). In this embodiment, the resin composition may be the reaction solution containing copolymer (A) obtained during the production of copolymer (A). In this case, it is not necessary to isolate copolymer (A) from the reaction solution. Furthermore, if solvent (B-1) and / or solvent (B-2) used in the production of copolymer (A) are present in the reaction solution, solvent (B-1) and / or solvent (B-2) in the reaction solution can be used as solvent (B) as is. Solvent (B) may be added to the reaction solution as needed.

[0108] In the resin composition of this embodiment, the amounts of copolymer (A) and solvent (B) can be appropriately adjusted according to the intended use of the resin composition. In the resin composition of this embodiment, for example, it is preferable to contain 30 to 1,000 parts by mass of solvent (B) per 100 parts by mass of copolymer (A), and more preferably 50 to 800 parts by mass. When the solvent (B) content is 30 parts by mass or more, the viscosity of the resin composition becomes appropriate. Furthermore, by setting the amount of solvent (B) to 30 parts by mass or more, abnormal polymerization reactions can be prevented, the curing of the resin composition can be performed stably, and discoloration and gelation of the resin composition can be prevented. When the solvent (B) content is 1,000 parts by mass or less, the viscosity of the resin composition can be controlled within an appropriate range.

[0109] (Reactive diluent (C)) The reactive diluent (C) is included together with the photopolymerization initiator (D) as needed. The reactive diluent (C) is a compound having at least one polymerizable ethylenically unsaturated group as a polymerizable functional group in its molecule. The reactive diluent (C) may be a monofunctional monomer or a polyfunctional monomer, and is preferably a polyfunctional monomer having multiple polymerizable functional groups. By using a resin composition containing the reactive diluent (C), viscosity can be easily adjusted. Furthermore, by using a resin composition containing the reactive diluent (C), the adhesion of the cured resin composition to the substrate can be improved, and the strength of the cured resin composition can be adjusted.

[0110] Monofunctional monomers used as reactive diluents (C) include (meth)acrylamide, methylol(meth)acrylamide, methoxymethyl(meth)acrylamide, ethoxymethyl(meth)acrylamide, propoxymethyl(meth)acrylamide, butoxymethoxymethyl(meth)acrylamide, methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, and 2-phenoxy-2-hydroxypropyl(meth)acrylate. Examples include (meth)acrylates such as ropyrus (meth)acrylate, 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, glycerin mono(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, glycidyl(meth)acrylate, 2,2,2-trifluoroethyl(meth)acrylate, 2,2,3,3-tetrafluoropropyl(meth)acrylate, and half(meth)acrylates of phthalic acid derivatives; aromatic vinyl compounds such as styrene, α-methylstyrene, α-chloromethylstyrene, and vinyltoluene; and carboxylic acid esters such as vinyl acetate and vinyl propionate. These monofunctional monomers may be used individually or in combination of two or more.

[0111] Polyfunctional monomers used as reactive diluents (C) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, and trimethylolpropane. Di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane, 2-hydroxy-3-(meth)acryloyloxypropyl(meth) Examples include acrylates, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, diglycidyl phthalate diglycidyl ester di(meth)acrylate, glycerin triacrylate, glycerin polyglycidyl ether poly(meth)acrylate, urethane (meth)acrylate (i.e., tolylene diisocyanate), reaction products of trimethylhexamethylene diisocyanate and hexamethylene diisocyanate with 2-hydroxyethyl (meth)acrylate, tri(meth)acrylate of tris(hydroxyethyl) isocyanurate, and other (meth)acrylates; aromatic vinyl compounds such as divinylbenzene, diallyl phthalate, and diallylbenzene phosphonate; dicarboxylic acid esters such as divinyl adipate; triallyl cyanurate, methylene bis(meth)acrylamide, (meth)acrylamide methylene ether, and condensates of polyhydric alcohols with N-methylol(meth)acrylamide. These polyfunctional monomers may be used individually or in combination of two or more.

[0112] Among these monomers, from the viewpoint of improving the development form and curability of the resin composition, it is preferable to use a polyfunctional (meth)acrylate as the reactive diluent (C), and it is more preferable to use one or more selected from trimethylolpropane tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0113] When the resin composition contains a reactive diluent (C), the amounts of each component are preferably such that, per 100 parts by mass of the total amount of copolymer (A) and reactive diluent (C), copolymer (A) is 10 to 90 parts by mass, solvent (B) is 30 to 1,000 parts by mass, and reactive diluent (C) is 10 to 90 parts by mass; more preferably, copolymer (A) is 20 to 80 parts by mass, solvent (B) is 50 to 800 parts by mass, and reactive diluent (C) is 20 to 80 parts by mass; and even more preferably, copolymer (A) is 30 to 75 parts by mass, solvent (B) is 100 to 700 parts by mass, and reactive diluent (C) is 25 to 70 parts by mass. When the amounts of each component are within the above ranges, a resin composition with appropriate viscosity is obtained, which can be suitably used for various coatings, adhesives, binders for printing inks, etc.

[0114] (Photopolymerization initiator (D)) The photopolymerization initiator (D) is not particularly limited, but examples include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin butyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 4-(1-t-butyldioxy-1-methylethyl)acetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1; 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone, and 1-chloro Examples include anthraquinones such as anthraquinone; thioxanthones such as xanthone, thioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone, 4-(1-t-butyldioxy-1-methylethyl)benzophenone, and 3,3',4,4'-tetrakis(t-butyldioxycarbonyl)benzophenone; acylphosphine oxides; and ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime). These photopolymerization initiators (D) may be used alone or in combination of two or more.

[0115] If the resin composition contains a photopolymerization initiator (D), its content is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 15 parts by mass, based on 100 parts by mass of the total amount of copolymer (A) and reactive diluent (C).

[0116] (Coloring agent (E)) A colorant (E) is included as needed. The colorant (E) is not particularly limited as long as it is soluble or dispersed in the solvent (B), and examples include dyes and pigments. Depending on the color of the cured product of the target resin composition, only one type of colorant (E) may be used, or two or more types may be used in combination. The colorant (E) may be a dye only, a pigment only, or a combination of a dye and a pigment.

[0117] As dyes, it is preferable to use acidic dyes having acidic groups such as carboxylic acids and sulfonic acids, salts of acidic dyes with nitrogen compounds, or sulfonamide forms of acidic dyes, from the viewpoint of solubility in solvent (B) and alkaline developer, interaction with other components in the resin composition, and heat resistance.

[0118] Examples of such dyes include acid alizarin violet N; acid black 1, 2, 24, 48; acid blue 1, 7, 9, 25, 29, 40, 45, 62, 70, 74, 80, 83, 90, 92, 112, 113, 120, 129, 147; acid chrome violet K; acid Fuchsin; acid green 1, 3, 5, 25, 27, 50; acid orange 6, 7, 8, 10, 12, 50, 51, 52, 56, 63, 74, 95; acid red1, 4, 8, 14, 17, 18, 26, 27, 29, 31, 34, 35, 37, 42, 44, 50, 51, 52, 57, 69, 73, 80, 87, 88, 91, 92, 94, 97, 103, 111, 11 4,129,133,134,138,143,145,150,151,158,176,183,198,211,215,216,217,249,252,257,260,266,274;acid violet 6B, 7, 9, 17, 19;acid Examples include yellow 1, 3, 9, 11, 17, 23, 25, 29, 34, 36, 42, 54, 72, 73, 76, 79, 98, 99, 111, 112, 114, 116; food yellow 3 and its derivatives. Among these dyes, it is preferable to use azo, xanthene, anthraquinone, or phthalocyanine acid dyes. These dyes may be used individually or in combination of two or more, depending on the color of the cured resin composition to be used.

[0119] Examples of pigments include yellow pigments such as CI Pigment Yellow 1, 3, 12, 13, 14, 15, 16, 17, 20, 24, 31, 53, 83, 86, 93, 94, 109, 110, 117, 125, 128, 137, 138, 139, 147, 148, 150, 153, 154, 166, 173, 194, 214; orange pigments such as CI Pigment Orange 13, 31, 36, 38, 40, 42, 43, 51, 55, 59, 61, 64, 65, 71, 73; and CI Pigment Red 9, 97, 105, 122, 123, 144, 149, 166, 168 Examples include red pigments such as 176, 177, 180, 192, 209, 215, 216, 224, 242, 254, 255, 264, and 265; blue pigments such as CI Pigment Blue 15, 15:3, 15:4, 15:6, and 60; violet pigments such as CI Pigment Violet 1, 19, 23, 29, 32, 36, and 38; green pigments such as CI Pigment Green 7, 36, 58, and 59; brown pigments such as CI Pigment Brown 23 and 25; and black pigments such as CI Pigment Black 1 and 7, carbon black, titanium black, and iron oxide. These pigments may be used individually or in combination of two or more, depending on the desired color of the cured resin composition.

[0120] When a pigment is used as the coloring agent (E), a known dispersant may be included in the resin composition from the viewpoint of improving the dispersibility of the pigment. As the dispersant, it is preferable to use a polymer dispersant that has excellent dispersion stability over time. Examples of polymer dispersants include urethane-based dispersants, polyethyleneimine-based dispersants, polyoxyethylene alkyl ether-based dispersants, polyoxyethylene glycol diester-based dispersants, sorbitan aliphatic ester-based dispersants, and aliphatic-modified ester-based dispersants.

[0121] As polymer dispersants, commercially available products such as EFKA (manufactured by EFKA Chemicals BV), Disperbyk-161 (manufactured by Bic Chemie), Disparon (manufactured by Kusumoto Chemicals Co., Ltd.), and SOLSPERSE (manufactured by Zeneca) may be used. The type and amount of dispersant should be set appropriately according to the type of pigment used, etc.

[0122] When the resin composition contains a colorant (E), its content is preferably 3 to 80 parts by mass, more preferably 5 to 70 parts by mass, and even more preferably 10 to 60 parts by mass, based on 100 parts by mass of the total amount of copolymer (A) and reactive diluent (C). The resin composition containing copolymer (A) of this embodiment has excellent storage stability, and even when cured at low temperatures, a cured product with excellent solvent resistance can be obtained. For this reason, for example, the content of the colorant (E) can be 20 parts by mass or more, based on 100 parts by mass of the total amount of copolymer (A) and reactive diluent (C). A resin composition containing 20 parts by mass or more of colorant (E) can be used as a material for a color filter to improve the color reproducibility of an image display element equipped with a color filter.

[0123] In addition to the components described above, the resin composition of this embodiment may also contain known additives such as coupling agents, leveling agents, and thermal polymerization inhibitors to impart predetermined properties. The amount of these additives is not particularly limited as long as it does not hinder the effects of the present invention.

[0124] Since the resin composition of this embodiment contains copolymer (A) of this embodiment, the crosslinking reaction proceeds sufficiently even at low temperatures. Therefore, the resin composition of this embodiment can be cured at low temperatures. Specifically, the resin composition of this embodiment is preferably cured at a temperature of 150°C or lower, more preferably 100°C or lower, and most preferably 80°C or lower. When the curing temperature of the resin composition is 150°C or lower, the amount of energy required to cure the resin composition is reduced. Furthermore, if the resin composition contains a colorant (E) with poor heat resistance, the deterioration of the colorant (E) due to thermal curing can be suppressed, and a cured product in which the original properties of the colorant (E) are exhibited can be easily obtained. Therefore, a variety of materials can be used as the colorant (E). In addition, when forming a cured product by coating the resin composition onto a substrate and thermal curing it, a cured product can be formed even if the substrate is made of a material with poor heat resistance. Therefore, a variety of materials can be used as the substrate, such as resin for flexible displays.

[0125] The resin composition of this embodiment is preferably cured at a temperature of 50°C or higher, more preferably at 60°C or higher, and even more preferably at 70°C or higher. When the curing temperature of the resin composition is 50°C or higher, a sufficiently cross-linked structure is formed by transesterification in a short time, and a cured product with good solvent resistance can be efficiently formed. The heating time (curing time) for curing the resin composition of this embodiment can be appropriately determined according to the size and thickness of the cured product, the curing temperature, etc., and can be, for example, 10 minutes to 4 hours, and preferably 20 minutes to 2 hours.

[0126] The resin composition of this embodiment can be manufactured by mixing the above components using a known mixing apparatus. The solvent contained in each component used as a raw material when manufacturing the resin composition of this embodiment can be used as solvent (B). If the resin composition of this embodiment contains components other than copolymer (A) and solvent (B), it may be manufactured, for example, by adding a reactive diluent (C), a photopolymerization initiator (D), and a colorant (E) to a resin composition containing a previously manufactured copolymer (A) and solvent (B) and mixing them together.

[0127] The resin composition of this embodiment contains copolymer (A) of this embodiment, and therefore exhibits excellent storage stability, and a cured product with excellent solvent resistance can be obtained even when cured at low temperatures. Accordingly, the resin composition of this embodiment can be preferably used as a material for, for example, color filters, black matrices, color filter protective films, photospacers, liquid crystal alignment protrusions, microlenses, insulating films for touch panels, adhesives for electronic materials around flexible printed circuit boards, and adhesive sheets.

[0128] When the resin composition of this embodiment contains the copolymer (A), solvent (B), reactive diluent (C), and photopolymerization initiator (D), it can be preferably used as a photosensitive material with good alkali developability. In particular, it is suitable as a resist used in color filters incorporated into organic electroluminescent (EL) displays (for black pixel defining layer (PDL)), liquid crystal display devices, and solid-state imaging devices using charge-coupled elements (CCD) and complementary metal-oxide-semiconductor (CMOS) elements.

[0129] Furthermore, when the resin composition of this embodiment contains the copolymer (A), solvent (B), reactive diluent (C), photopolymerization initiator (D), and colorant (E), a colored pattern can be formed consisting of a cured product with excellent solvent resistance at low temperatures. Therefore, the degradation of the colorant (E) due to thermal curing is suppressed, and a colored pattern can be formed in which the original properties of the colorant (E) are exhibited. Accordingly, the above resin composition can be preferably used as a photosensitive material for color filters.

[0130] <Color Filter> Next, the color filter of this embodiment will be described. The color filter of this embodiment includes a substrate, a plurality of pixels consisting of three coloring patterns formed on the substrate: a red (R) pattern, a green (G) pattern, and a blue (B) pattern, a black matrix formed at the boundary of each coloring pattern, and a protective film formed on the pixels and the black matrix.

[0131] As the substrate, known substrates can be used, such as glass substrates, silicon substrates, polycarbonate substrates, polyester substrates, polyamide substrates, polyamide-imide substrates, polyimide substrates, aluminum substrates, printed circuit boards, array substrates, etc. In the color filter of this embodiment, an organic substrate with a relatively low heat resistance temperature, such as a polycarbonate substrate, polyester substrate, polyamide substrate, polyamide-imide substrate, or polyimide substrate, which is suitable as a flexible substrate, can be used.

[0132] In the color filter of this embodiment, the black matrix and the three color patterns forming each pixel are color patterns made of a cured product of the resin composition of this embodiment, which contains the copolymer (A), solvent (B), reactive diluent (C), photopolymerization initiator (D), and colorant (E). The protective film is not particularly limited, and any known film can be used.

[0133] Next, the manufacturing method of the color filter of this embodiment will be described with an example. To manufacture the color filter of this embodiment, first, a colored pattern that will serve as the black matrix and three colored patterns that will form each pixel are formed on the substrate. First, the colored pattern that will serve as the black matrix is ​​formed on the substrate, and then, within the area demarcated by the black matrix, the red, green, and blue patterns that will form each pixel are formed, respectively. The order in which the red, green, and blue patterns are formed is not particularly limited.

[0134] Each colored pattern can be formed by photolithography using the resin composition of this embodiment. Specifically, the resin composition of this embodiment is applied to a substrate to form a coating film. Next, the coating film is exposed to light through a photomask having a predetermined pattern shape, and the exposed portion is photocured. Then, the unexposed portion of the coating film is removed by alkaline development using an alkaline aqueous solution. After that, the exposed portion of the coating film is heated and cured by baking. Through these steps, a colored pattern having a predetermined shape and consisting of cured resin composition of this embodiment is obtained.

[0135] The method for applying the resin composition to form a colored pattern is not particularly limited, and for example, screen printing, roll coating, curtain coating, spray coating, spin coating, etc., can be used. After applying the resin composition, the coating film may be heated using a heating means such as a circulating oven, infrared heater, or hot plate, if necessary, to volatilize and remove the solvent (B) contained in the coating film. Heating to remove solvent (B) from the coating film can be performed at a temperature of, for example, 50°C to 120°C. Heating to remove solvent (B) from the coating film can also be performed for, for example, 30 seconds to 30 minutes. The heating temperature and heating time for removing solvent (B) from the coating film can be appropriately set according to the composition of the resin composition, the thickness of the coating film, etc.

[0136] When exposing the coated film, a known negative-type mask can be used as a photomask. When exposing the coated film, it is preferable to use active energy rays such as ultraviolet light or excimer laser light. The light source used for exposure is not particularly limited, and for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, metal halide lamps, etc., can be used. The energy dose irradiated onto the coated film can be appropriately selected according to the thickness of the coated film, the composition of the resin composition, etc., for example, 30 to 2000 mJ / cm². 2 It can be done this way.

[0137] The alkaline aqueous solution used for alkaline development is not particularly limited and can be, for example, aqueous solutions of sodium carbonate, potassium carbonate, calcium carbonate, sodium hydroxide, potassium hydroxide; aqueous solutions of amine compounds such as ethylamine, diethylamine, and dimethylethanolamine; or aqueous solutions of p-phenylenediamine compounds such as tetramethylammonium, 3-methyl-4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamideethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline, and their sulfates, hydrochlorides, or p-toluenesulfonates, which can be appropriately selected depending on the composition of the resin composition. These alkaline aqueous solutions may contain, if necessary, defoaming agents and surfactants as additives. Furthermore, in this embodiment, it is preferable to wash the substrate with water to remove the alkaline aqueous solution and then dry it before performing baking after alkaline development with an alkaline aqueous solution.

[0138] In this embodiment, the temperature at which the exposed portion of the coating film is heated and cured by baking can be appropriately selected depending on the thickness of the coating film, the composition of the resin composition, and so on. In this embodiment, since the coating film is formed using a resin composition containing copolymer (A) of this embodiment, the exposed portion of the coating film can be cured even at low temperatures.

[0139] The temperature at which the exposed portion of the coating film is heated can be, for example, 210°C or lower, and may be 150°C or lower, 100°C or lower, or even 80°C or lower, as needed. When the temperature at which the exposed portion of the coating film is heated is 210°C or lower, materials with low heat resistance, such as substrates with low heat resistance, can be used as the material for the color filter. When the temperature at which the exposed portion of the coating film is heated is 150°C or lower, the amount of energy required to cure the coating film is reduced, which is preferable. Furthermore, when the temperature at which the exposed portion of the coating film is heated is 150°C or lower, color patterns containing colorants (E) with poor heat resistance, which were conventionally difficult to use as materials for color patterns, can be formed while suppressing the degradation of the colorants (E). In addition, when the temperature at which the exposed portion of the coating film is heated is 150°C or lower, color patterns can be formed on substrates with poor heat resistance, which were conventionally difficult to use as substrates for color filters.

[0140] The temperature at which the exposed portion of the coating film is heated is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher. When the temperature at which the exposed portion of the coating film is heated is 50°C or higher, the copolymer (A) and the reactive diluent (C) are sufficiently crosslinked, resulting in good solvent resistance of the colored pattern and a good pattern shape. Furthermore, when the temperature at which the exposed portion of the coating film is heated is 50°C or higher, the exposed portion of the coating film can be heated in a short time, and the colored pattern can be manufactured efficiently. The heating time for the exposed portion of the coating film can be appropriately selected depending on the heating temperature of the exposed portion of the coating film, the thickness of the coating film, the composition of the resin composition, etc. For example, it can be 10 minutes to 4 hours, preferably 20 minutes to 2 hours.

[0141] Next, a protective film is formed on the colored pattern that forms the black matrix and the three colored patterns that form each pixel, using a known method. The color filter of this embodiment can be obtained through the above steps.

[0142] In this embodiment, the color filter has three color patterns and a black matrix forming each pixel, which are made of a cured product of the resin composition of this embodiment containing the copolymer (A), solvent (B), reactive diluent (C), photopolymerization initiator (D), and colorant (E). The resin composition of this embodiment has good alkali developability, and a cured product with excellent solvent resistance can be obtained even when cured at low temperatures. Therefore, in this embodiment, pixels and a black matrix can be formed using a method of curing the resin composition at low temperatures, which increases the range of materials that can be used for the color filter.

[0143] Therefore, the color filter of this embodiment may, for example, contain a colorant (E) with poor heat resistance and have pixels and / or a black matrix having a good pattern shape. Furthermore, by forming the pixels and black matrix using a method of curing the resin composition at a low temperature, a color filter can be made that includes a substrate made of a material with poor heat resistance.

[0144] In contrast, when forming a colored pattern using a conventional resin composition instead of the resin composition of this embodiment, if the temperature at which the exposed portion of the coated film is heated and cured is less than 210°C, the solvent resistance of the cured colored pattern will be insufficient. Therefore, when forming a colored pattern using a conventional resin composition, it was not possible to heat the exposed portion of the coated film to a temperature of 210°C or lower. Consequently, with conventional techniques, it was difficult to use a colorant (E) with poor heat resistance as the material for the colored pattern. Furthermore, it was also difficult to use a substrate with poor heat resistance as the substrate for the color filter.

[0145] In this embodiment, the color filter was described using as an example a case in which the coloring pattern has pixels and a black matrix made of a cured resin composition containing the copolymer (A) of this embodiment, a solvent (B), a reactive diluent (C), a photopolymerization initiator (D), and a colorant (E). However, instead of the photopolymerization initiator (D), a resin composition containing a curing accelerator and a known epoxy resin may be used.

[0146] In this case, for example, a colored pattern can be formed by the method shown below. First, a resin composition is applied to a substrate by an inkjet method to form a coating film having a predetermined pattern shape. Next, the coating film is heated and cured. By the above method, a colored pattern having a desired shape and consisting of a cured resin composition can be formed. Resin compositions containing a curing accelerator and a known epoxy resin instead of a photopolymerization initiator (D) also yield cured products with excellent solvent resistance even when cured at low temperatures. Therefore, in this case as well, pixels and black matrices can be formed using a method that cures the resin composition at low temperatures, increasing the options for materials that can be used for color filters.

[0147] <Image display element> Next, the image display element of this embodiment will be described. Examples of liquid crystal display elements used as image display elements in this embodiment include a first substrate having a color filter and a first electrode formed on its surface, and a second substrate having a second electrode formed on its surface, arranged with the first electrode and the second electrode facing each other via a spacer, and a liquid crystal composition sandwiched between the first substrate and the second substrate. In the liquid crystal display element of this embodiment, the color filter of this embodiment is provided as the color filter. In the liquid crystal display element of this embodiment, known components other than the color filter can be used.

[0148] The liquid crystal display element of this embodiment can be manufactured, for example, using the manufacturing method shown below. First, a color filter and a first electrode are formed on the first substrate in that order. The color filter can be formed using the manufacturing method described above. The first electrode can be formed using a known method. Next, a second electrode and a spacer are formed on the second substrate by a known method. Subsequently, the first substrate and the second substrate are bonded together with the first electrode and the second electrode facing each other, and a liquid crystal composition is injected between the first substrate and the second substrate to seal them. The liquid crystal display element of this embodiment is obtained through the above steps.

[0149] Since the liquid crystal display element of this embodiment is equipped with the color filter of this embodiment, the pixels and black matrix of the color filter can be formed using a method of curing the resin composition at a low temperature. Therefore, it is possible to use materials with poor heat resistance as materials that can be used for the liquid crystal display element, and the range of usable materials can be increased.

[0150] In the embodiments described above, a liquid crystal display element was used as an example of the image display element of this embodiment. However, the image display element of this embodiment is not limited to a liquid crystal display element, as long as it is equipped with the color filter of this embodiment. The image display element of this embodiment may be, for example, an organic EL display element, or a solid-state imaging device using a CCD element or CMOS element. [Examples]

[0151] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

[0152] [Synthesis Example 1] A flask equipped with a stirring device, dropping funnel, condenser, thermometer, and gas inlet tube contained 212.5 g of propylene glycol monomethyl ether (manufactured by Sankyo Chemical Co., Ltd.) as solvent (B-1), and was stirred while purging with nitrogen gas, and the temperature was raised to 78°C (solvent heating step (I)).

[0153] Next, 26.9 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (polymerization initiator) was dissolved in 77.3 g of propylene glycol monomethyl ether as solvent (B-2) to prepare a polymerization initiator solution. Furthermore, 41.0 g (13 mol%) of MOI-DEM, 37.4 g (26 mol%) of 4-hydroxybutyl acrylate, 19.8 g (23 mol%) of methacrylic acid, and 69.9 g (38 mol%) of 2-ethylhexyl acrylate (2EHA) were dissolved in 60.5 g of propylene glycol monomethyl ether as solvent (B-2) and then mixed to obtain a monomer solution. Subsequently, dropwise polymerization was carried out by simultaneously adding the polymerization initiator solution and the monomer solution to the flask containing the solvent (B-1h) heated to 78°C, using a dropping funnel, while stirring the solvent (B-1h) in the flask, to form a mixed solution (dropwise polymerization step (II)). The dropping rate for both the polymerization initiator solution and the monomer solution was 1.7 ml / min.

[0154] After the dropwise addition was complete, the mixed solution was stirred and reacted at 78°C for 3 hours to produce copolymer (A) (post-polymerization step (III)). To the reaction solution containing the copolymer (A) obtained in this way, propylene glycol monomethyl ether as solvent (B) was added so that the non-solvent components accounted for 35% by mass, thereby obtaining the polymer composition of Synthesis Example 1.

[0155] [Synthesis Examples 2-11, Comparative Synthesis Examples 1-3] Polymer compositions for Synthesis Examples 2-11 and Comparative Synthesis Examples 1-3 were obtained in the same manner as for Synthesis Example 1, except that the materials listed in Tables 1-3 were used in the proportions listed in Tables 1-3.

[0156] [Synthesis Example 12] In a flask equipped with a stirrer, dropping funnel, condenser, thermometer, and gas inlet tube, 212.5 g of propylene glycol monomethyl ether (manufactured by Sankyo Chemical Co., Ltd.) as solvent (B-1) and 1.75 g of thioglycolic acid as a chain transfer agent were added, and the mixture was stirred while purging with nitrogen gas, and the temperature was raised to 78°C (solvent heating step (I)).

[0157] Next, 26.9 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (polymerization initiator) was dissolved in 77.3 g of propylene glycol monomethyl ether as solvent (B-2) to prepare a polymerization initiator solution. Furthermore, 63.0 g (20 mol%) of MOI-DEM, 57.6 g (40 mol%) of 4-hydroxybutyl acrylate, 17.2 g (20 mol%) of methacrylic acid, and 36.8 g (20 mol%) of 2-ethylhexyl acrylate (2EHA) were dissolved in 60.5 g of propylene glycol monomethyl ether as solvent (B-2) to prepare monomer solutions. Subsequently, dropwise polymerization was carried out by simultaneously adding the polymerization initiator solution and the monomer solution to the flask containing the solvent (B-1h) heated to 78°C, using a dropping funnel, while stirring the solvent (B-1h) in the flask, to form a mixed solution (dropwise polymerization step (II)). The dropping rate for both the polymerization initiator solution and the monomer solution was 1.7 ml / min.

[0158] After the dropwise addition was complete, the mixed solution was stirred and reacted at 78°C for 3 hours to produce copolymer (A) (post-polymerization step (III)). To the reaction solution containing the copolymer (A) obtained in this way, propylene glycol monomethyl ether as the solvent (B) was added so that the non-solvent components accounted for 35% by mass, thereby obtaining the polymer composition of Synthesis Example 12.

[0159] [Table 1]

[0160] [Table 2]

[0161] [Table 3]

[0162] In Tables 1 to 3, (ma) indicates a monomer having a group represented by formula (1) or formula (2) above. (mb) indicates a monomer containing a hydroxyl group. (mc) indicates a monomer containing an acid group. (d) indicates other monomers that do not fall under (ma), (mb), or (mc). Furthermore, in Tables 1 to 3, (equivalent number of formulas (1) and (2)) indicates the equivalent number of the group represented by formula (1) or formula (2) contained in the molecule of copolymer (A).

[0163] The materials used in Tables 1 to 3 are as follows: • MOI-DEM: Karenz (registered trademark) MOI-DEM (reaction product of 2-isocyanatoethyl methacrylate and diethyl malonate, manufactured by Showa Denko Corporation) • AOI-DEM: Karenz (registered trademark) AOI-DEM (reaction product of 2-isocyanatoethyl acrylate and diethyl malonate, manufactured by Showa Denko Corporation) • 4-Hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation) • 2-hydroxyethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) • 2-hydroxyethyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) • 2-hydroxypropyl acrylate (HOP-A(N)) (manufactured by Kyoeisha Chemical Co., Ltd.) • Methacrylic acid (manufactured by Kuraray Co., Ltd.) • Acrylic acid (manufactured by Toagosei Co., Ltd.)

[0164] • 2EHA: 2-Ethylhexyl acrylate (manufactured by Toagosei Co., Ltd.) • TCDMA: Tricyclo[5.2.1.0 2,6 Decanyl-8-methacrylate (manufactured by Hitachi Chemical Co., Ltd.) • GMA: Glycidyl methacrylate (manufactured by NOF Corporation) • MOI-BP: Karenz (registered trademark) MOI-BP (2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate, manufactured by Showa Denko Corporation) • MOI-BM: Karenz (registered trademark) MOI-BM (2-"0-(1'-methylpropyleneneamino)carboxyamino]ethyl methacrylate, manufactured by Showa Denko Corporation)

[0165] The polymer compositions of Synthesis Examples 1-12 and Comparative Synthesis Examples 1-3, shown in Tables 1-3, were evaluated by measuring their weight-average molecular weight (Mw), glass transition temperature (Tg), storage stability, and acid value using the methods described below. The results are shown in Tables 1-3, respectively.

[0166] <Weight average molecular weight (Mw)> The weight-average molecular weight (Mw) of copolymer (A) contained in the polymer compositions of Synthesis Examples 1-12 and Comparative Synthesis Examples 1-3 was measured. The weight-average molecular weight is the weight-average molecular weight on a standard polystyrene basis, measured using gel permeation chromatography (GPC) under the following conditions. Column: SHODEX® LF-804 + LF-804 (manufactured by Showa Denko Corporation) Column temperature: 40℃ Sample: 0.2% by mass solution of copolymer with tetrahydrofuran Developing solvent: tetrahydrofuran Detector: Differential refractometer (Showdex® RI-71S) (manufactured by Showa Denko Corporation) Flow rate: 1mL / min

[0167] <Glass transition temperature (Tg)> The polymer compositions of Synthesis Examples 1-12 and Comparative Synthesis Examples 1-3 were coated onto glass substrates and dried at 50°C under reduced pressure for 24 hours. Afterward, they were redissolved in acetone and dried again at 50°C under reduced pressure for 24 hours. The solid content of the copolymer solution, from which volatile components had been removed, was measured using a DSC (Differential Scanning Calorimeter, measuring instrument: Seiko DSC6200) under a nitrogen stream at a heating rate of 10°C / min in accordance with JIS-K7121 (intermediate glass transition temperature). The obtained result was defined as the glass transition temperature (Tg) of copolymer (A).

[0168] <Storage stability> After preparation, equal amounts of the polymer compositions from Synthesis Examples 1-12 and Comparative Synthesis Examples 1-3, each containing 35% by mass of components other than the solvent, were measured into glass containers. The containers were then sealed to prevent dust from entering and prepared as samples. After measuring the viscosity of each sample, they were left to stand in a constant temperature incubator maintained at 12°C for 3 months. The viscosity of each sample after 3 months of standing was then measured again. Viscosity was measured using an E-type viscometer (RE-80L, manufactured by Toki Sangyo, cone No. 3) at 25°C and a rotation speed of 10 rpm.

[0169] For each sample, the viscosity increase rate {(1 - (viscosity after 3 months of standing / viscosity before standing)) × 100 (%)} was calculated relative to the viscosity before standing in the incubator, and evaluated according to the following criteria. ◎: Thickening rate of 10% or less ○: Thickening rate 10.1%~20% △: Thickening rate of 20.1% or more

[0170] As shown in Tables 1 to 3, the polymer compositions of Synthesis Examples 1 to 12 and Comparative Synthesis Examples 1 to 3 all received a storage stability rating of ◎ or ○, confirming that they possess excellent storage stability.

[0171] <Acid value> The acid values ​​of the polymer compositions from Synthesis Examples 1-12 and Comparative Synthesis Examples 1-3 were measured and used as the acid values ​​of copolymer (A). This is the acid value of the curable polymer, measured according to JIS K6901 5.3. In other words, the acid value represents the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 gram of copolymer.

[0172] [Examples 1-12, Comparative Examples 1-3] The polymer compositions of Synthesis Examples 1-12 and Comparative Synthesis Examples 1-3 shown in Tables 1-3 were mixed with (B) propylene glycol monomethyl ether acetate as a solvent, (C) a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (Kayarad DPHA, manufactured by Nippon Kayaku Co., Ltd.) as a reactive diluent, (D) ethanoone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(o-acetyloxime) (manufactured by BASF Japan Ltd.) as a photopolymerization initiator, and (E) a dye (VALIFAST BLUE 2620) as a coloring agent, in the proportions shown in Table 4, to prepare the resin compositions of Examples 1-12 and Comparative Examples 1-3.

[0173] [Table 4]

[0174] The copolymer (A) shown in Table 4 does not include the amount of solvent contained in the reaction solution used to produce copolymer (A). The amount of solvent (B) shown in Table 4 is the sum of the solvent contained in the polymer composition (propylene glycol monomethyl ether) and the solvent added during the production of the resin composition (propylene glycol monomethyl ether acetate). The proportion of hydroxyl group-containing solvent in solvent (B) shown in Table 4 is 79.1% by mass.

[0175] The alkali developability and solvent resistance of the resin compositions of Examples 1-12 and Comparative Examples 1-3 were evaluated by the following method. (1) Alkaline developability The resin compositions of the examples and comparative examples were spin-coated onto a 5cm x 5cm square glass substrate (alkali-free glass substrate) to form a coated film with a thickness of 2.5 μm after exposure. The solvent in the coated film was then evaporated and removed by heating at 100°C for 3 minutes.

[0176] Next, a photomask with a predetermined pattern is placed 100 μm away from the coated film, and ultraviolet light with a wavelength of 365 nm is applied to the coated film through this photomask at an energy dose of 40 mJ / cm². 2 The material was irradiated and exposed, and the exposed area was photocured. Next, an aqueous solution containing 0.1% by mass of sodium carbonate was sprayed at a temperature of 23°C and a pressure of 0.3 MPa to dissolve the unexposed areas and develop the image. Subsequently, the image was baked at 100°C for 20 minutes to form the desired pattern.

[0177] Then, the residue after alkaline development was identified by observing the pattern using a Hitachi High-Technologies Corporation S-3400 electron microscope and evaluated according to the following criteria. The results are shown in Table 5. ○: No residue in unexposed areas ×: Residue present in unexposed areas

[0178] (2) Solvent resistance The resin compositions of the examples and comparative examples were spin-coated onto a 5cm x 5cm square glass substrate (alkali-free glass substrate) to form a coated film with a thickness of 2.5 μm after exposure. The solvent in the coated film was then evaporated and removed by heating at 100°C for 3 minutes.

[0179] Next, the coated film is exposed to ultraviolet light with a wavelength of 365 nm at an energy dose of 40 mJ / cm². 2 The exposed areas were photocured by irradiation. Subsequently, the coated film was cured by baking at 80°C for 30 minutes or at 100°C for 20 minutes to form a cured film. The prepared cured film was immersed in 20 g of propylene glycol monomethyl ether at 23°C for 15 minutes. The color change (ΔEab) before and after immersion was measured using a UV-1650PC spectrophotometer (manufactured by Shimadzu Corporation), and solvent resistance was evaluated based on the results. The results are shown in Table 5.

[0180] [Table 5]

[0181] As shown in Table 5, the cured films obtained by curing the resin compositions of Examples 1 to 12 showed good alkali developability. Furthermore, the cured films obtained by curing the resin compositions of Examples 1 to 12 showed good solvent resistance, with a ΔEab of less than 3 in both cases: when the curing temperature was 80°C for 30 minutes, and when the temperature was 100°C for 20 minutes.

[0182] On the other hand, the cured films obtained by curing the resin compositions of Comparative Examples 1 to 3 showed good alkali developability, but when the curing temperature of the coated film was 80°C and the curing time was 30 minutes, the ΔEab was 3 or higher, indicating insufficient solvent resistance. [Industrial applicability]

[0183] The present invention provides a resin composition that exhibits good alkali developability when used as a photosensitive material, excellent storage stability, and yields a cured product with excellent solvent resistance even when cured at low temperatures; a copolymer useful for preparing this resin composition; and a method for producing the copolymer. Furthermore, the present invention provides a colored pattern made from a cured resin composition that exhibits good alkali developability and yields a cured product with excellent solvent resistance even when cured at low temperatures, a color filter having the same, and an image display element equipped with the color filter. The resin composition of the present invention can be preferably used in a wide range of applications as a material for transparent films, protective films, insulating films, overcoats, photospacers, black matrices, black column spacers, and resists for color filters.

Claims

1. A constituent unit (a) having a group represented by the following formula (1) or formula (2), A constituent unit (b) derived from hydroxyalkyl (meth)acrylate, It contains a constituent unit (c) having an acid group, The material contains 1 to 40 mol% of the aforementioned constituent unit (a), 1 to 60 mol% of the aforementioned constituent unit (b), and 1 to 60 mol% of the aforementioned constituent unit (c). A copolymer characterized by having a glass transition temperature of 30°C or lower. 【Chemistry 1】 (In formula (1), R １ and R ２ Each of these independently represents an alkyl group having 1 to 10 carbon atoms. * represents a linking site. 【Chemistry 2】 (In formula (2), R ３ (* represents an alkyl group with 1 to 10 carbon atoms. * represents a linking site.)

2. The copolymer according to claim 1, wherein the constituent unit (c) is a constituent unit derived from an unsaturated carboxylic acid.

3. The copolymer according to claim 1 or 2, wherein the constituent unit (a) is a constituent unit derived from a compound having a group represented by formula (1) or formula (2) and a (meth)acryloyloxy group.

4. The copolymer according to any one of claims 1 to 3, wherein the molar ratio of the total amount of ester groups contained in the group represented by formula (1) or formula (2) to the total amount of hydroxyl groups contained in the constituent unit (b) is 10:90 to 90:

10.

5. The copolymer according to any one of claims 1 to 4, wherein the weight-average molecular weight is 1,000 to 50,000.

6. A copolymer (A) according to any one of claims 1 to 5 and a solvent (B) are contained, A resin composition characterized in that the solvent (B) contains a hydroxyl group-containing solvent.

7. The resin composition according to claim 6, further comprising a reactive diluent (C) and a photopolymerization initiator (D).

8. The resin composition according to claim 7, further containing a coloring agent (E).

9. With respect to 100 parts by mass of the total amount of the copolymer (A) and the reactive diluent (C), The copolymer (A) is 10 to 90 parts by mass. The solvent (B) is 30 to 1000 parts by mass. The reactive diluent (C) is 10 to 90 parts by mass. The photopolymerization initiator (D) is 0.1 to 30 parts by mass. The resin composition according to claim 8, wherein the coloring agent (E) is contained in 3 to 80 parts by mass.

10. A color filter characterized by having a colored pattern made of a cured product of the resin composition described in Claim 8 or Claim 9.

11. An image display element characterized by comprising the color filter described in Claim 10.

12. Solvent heating step (I) involves raising the temperature of solvent (B-1) to 60-90°C to prepare the heated solvent (B-1h), A monomer solution obtained by dissolving a monomer (m-a) having a group represented by the following formula (1) or formula (2), a hydroxyalkyl (meth)acrylate (m-b), and an acid group-containing monomer (m-c) in solvent (B-2) is added dropwise to the heated solvent (B-1h), A dropwise polymerization step (II) involves dissolving the polymerization initiator in the solvent (B-2) to obtain a polymerization initiator solution, which is then dropwise added to the solvent (B-1h) to form a mixed solution. The process includes a post-polymerization step (III) in which the mixed solution is reacted at 60 to 90°C for 1 to 5 hours while being stirred. A method for producing a copolymer, characterized in that either one or both of the solvent (B-1) and the solvent (B-2) contain a hydroxyl group-containing solvent. 【Transformation 3】 (In formula (1), R １ and R ２ Each of these independently represents an alkyl group having 1 to 10 carbon atoms. * represents a linking site. 【Chemistry 4】 (In formula (2), R ３ (* represents an alkyl group with 1 to 10 carbon atoms. * represents a linking site.)

13. The method for producing a copolymer according to claim 12, wherein in the solvent heating step (I), a chain transfer agent is added to the solvent (B-1) before the temperature is raised.

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