Copolymers, curable resin compositions, and cured products

Abstract

Provided are a copolymer having excellent storage stability that cures at a relatively low temperature and has excellent solvent resistance of the cured product, a curable resin composition that includes the copolymer, and a cured product thereof. The copolymer includes a structural unit (A) derived from an unsaturated carboxylic acid or an anhydride thereof and a structural unit (B) derived from an epoxy compound represented by formula (b1) (in the formula, Rb1 represents a hydrogen atom or a C1-7 alkyl group. Rb2 represents a divalent hydrocarbon group that optionally includes a hetero atom. Rb3 represents a divalent organic group having two or more epoxy groups.).

Description

[Technical Field]

[0001] The present invention relates to a copolymer, a curable resin composition containing the copolymer, and a cured product thereof. This application claims priority to Japanese Patent Application No. 2019-183122, filed in Japan on October 3, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] In the field of manufacturing various electronic devices that require submicron-order microfabrication, such as VLSI, there is a growing demand for even higher density and integration of devices. Therefore, the demand for photolithography technology, a method for forming fine patterns, is increasing. On the other hand, electronic components such as liquid crystal display elements, integrated circuit elements, and solid-state image sensors are provided with protective films to prevent degradation and damage, interlayer insulating films to insulate between layered wiring, planarizing films to flatten the element surface, and insulating films to maintain electrical insulation.

[0003] In liquid crystal display elements having interlayer insulating films, such as TFT-type liquid crystal display elements, a polarizing plate is placed on a glass substrate, a transparent conductive circuit layer such as ITO and thin-film transistors (TFTs) are formed, and the substrate is covered with an interlayer insulating film to form the back plate. On the other hand, a polarizing plate is placed on a glass plate, patterns of a black matrix layer and a color filter layer are formed as needed, and then a transparent conductive circuit layer and an interlayer insulating film are sequentially formed to form the top plate. The back plate and the top plate are then placed opposite each other with a spacer in between, and liquid crystal is sealed between the two plates during manufacturing.

[0004] One method for increasing the sensitivity of radiation-sensitive resin compositions (resists), which are used for forming fine patterns, is the use of chemically amplified resists that utilize photoacid generators as photosensitive agents. For example, a resin composition containing a resin with structural units having epoxy groups and a photoacid generator is used. Upon exposure, protonic acid is generated from the photoacid generator, which cleaves the epoxy groups and causes a crosslinking reaction. This makes the resin insoluble in the developer, and a pattern is formed. In this way, a dramatic increase in sensitivity is achieved compared to conventional resists with a photoreaction efficiency (reaction per photon) of less than 1. Currently, most resists being developed are of the chemically amplified type and are being used in the development of highly sensitive materials that can handle the shortening of the wavelength of exposure light sources.

[0005] Insulating films, such as interlayer insulating films used in TFT-type liquid crystal display elements and integrated circuit elements, require fine patterns (microfabrication). Generally, radiation-sensitive resin compositions are used as materials for forming these insulating films. Such radiation-sensitive resin compositions are required to have high radiation sensitivity to improve productivity. If the insulating film has low solvent resistance, swelling, deformation, and delamination from the substrate due to organic solvents will occur, causing serious problems in the manufacturing of liquid crystal display elements and integrated circuit elements. Therefore, excellent solvent resistance is required for insulating films.

[0006] In response to such requirements, Patent Document 1 discloses a copolymer of (a) an unsaturated carboxylic acid and / or an unsaturated carboxylic acid anhydride, (b) a radical polymerizable compound having an epoxy group, and (c) another radical polymerizable compound, wherein glycidyl methacrylate is used as component (b).

[0007] Furthermore, Patent Document 2 discloses a copolymer of an alicyclic epoxy group-containing polymerizable unsaturated compound and a radical polymerizable compound, in which (3,4-epoxycyclohexyl)methyl methacrylate is used as the alicyclic epoxy group-containing polymerizable unsaturated compound.

[0008] Furthermore, Patent Document 3 describes a copolymer comprising (A) monomer units containing alkali-soluble groups and (B) monomer units corresponding to epoxy group-containing polymerizable unsaturated compounds, wherein the copolymer comprises a carboxyl group and 3,4-epoxytricyclo[5.2.1.0 2,6 A copolymer containing structural units having a decane ring is disclosed. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 6-43643 [Patent Document 2] Japanese Patent Publication No. 2003-76012 [Patent Document 3] Japanese Patent Publication No. 2006-193718 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, the copolymers disclosed in Patent Documents 1 and 2 had a problem in that, when stored at room temperature (23°C), their weight-average molecular weight increased over time, possibly due to the progression of a self-polymerization reaction. For this reason, they had to be stored under low-temperature conditions of -20°C or below. Furthermore, the cured products also had poor solvent resistance. Hereafter, an increase in weight-average molecular weight due to storage will be referred to as "poor storage stability." Conversely, the fact that the weight-average molecular weight does not increase (or increases only slightly) even after long-term storage will be referred to as "excellent storage stability."

[0011] Furthermore, the copolymer of Patent Document 3 is composed of a carboxyl group and 3,4-epoxytricyclo[5.2.1.0 2,6 Due to the poor reactivity of the decane ring with the epoxy group, the solvent resistance of the cured product can be low depending on the curing temperature. Therefore, in order to impart the desired solvent resistance to the cured product, it was necessary to cure the copolymer under high-temperature conditions.

[0012] Therefore, an object of the present invention is to provide a copolymer having excellent storage stability, curing even at a relatively low temperature, and excellent solvent resistance of the cured product, a curable resin composition containing the copolymer, and a cured product thereof.

Means for Solving the Problems

[0013] The present inventors have found that a copolymer containing specific structural units has excellent storage stability, cures even at a relatively low temperature, and has excellent solvent resistance of the cured product, and completed the present invention.

[0014] That is, in the present invention, a structural unit (A) derived from an unsaturated carboxylic acid or its anhydride and the following formula (b1)

Chemical Formula

[0015] The epoxy compound is represented by the following formula (b3)

Chemical Formula

[0016] The copolymer of the present invention preferably further comprises a constituent unit (C) derived from at least one compound selected from the group consisting of (c1) to (c4) below. (c1) Styrene which may be substituted with alkyl groups (c2)N-substituted maleimide (c3) N-vinyl compound (c4) The following formula (2) [ka] (In the formula, R 11 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. 12 (where X represents a monovalent hydrocarbon group which may contain heteroatoms.) Unsaturated carboxylic acid derivatives represented by

[0017] The copolymer of the present invention preferably has a content of 2 to 60% by weight of component unit (A), a content of 10 to 98% by weight of component unit (B), and a content of 0 to 88% by weight of component unit (C) relative to the total number of component units constituting the copolymer.

[0018] The present invention also provides a curable resin composition comprising the copolymer.

[0019] The curable resin composition preferably further contains a cationic polymerization initiator.

[0020] The present invention also provides a cured product of the curable resin composition. [Effects of the Invention]

[0021] The copolymer of the present invention exhibits excellent storage stability, cures at relatively low temperatures, and the cured product has excellent solvent resistance. Furthermore, the curable resin composition containing the copolymer exhibits excellent storage stability, cures at relatively low temperatures, and the cured product has excellent solvent resistance. Moreover, the cured product of the curable resin composition has excellent solvent resistance. [Modes for carrying out the invention]

[0022] <Copolymer> The copolymer of the present invention is a copolymer comprising a constituent unit (A) derived from an unsaturated carboxylic acid or its anhydride and a constituent unit (B) derived from an epoxy compound represented by formula (b1). The copolymer of the present invention may further contain a constituent unit (C) derived from at least one compound selected from the group consisting of (c1) to (c4). Furthermore, it may also contain a constituent unit (D) described below as a constituent unit other than constituent units (A) to (C).

[0023] [Constituent Unit (A)] The constituent unit (A) can be introduced into the copolymer by polymerizing an unsaturated carboxylic acid or its acid anhydride (a) with an epoxy compound (b) represented by the formula (b1).

[0024] The unsaturated carboxylic acid or its acid anhydride (a) is not particularly limited, but examples include α,β-unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; α,β-unsaturated dicarboxylic acids such as itaconic acid, maleic acid, and fumaric acid; anhydrides of α,β-unsaturated monocarboxylic acids such as methacrylic anhydride; and anhydrides of α,β-unsaturated dicarboxylic acids such as maleic anhydride and itaconic anhydride. Among these, acrylic acid and methacrylic acid are particularly preferred from the viewpoint of copolymerizability and developability. The unsaturated carboxylic acid or its acid anhydride (a) can be used alone or in combination of two or more.

[0025] The proportion (content) of constituent unit (A) in the copolymer is not particularly limited, but for example, it is preferably 2 to 60% by weight, more preferably 3 to 40% by weight, even more preferably 5 to 25% by weight, and particularly preferably 10 to 20% by weight relative to the total amount of constituent units constituting the copolymer. When the proportion of constituent unit (A) is above the lower limit, the proportion of the portion that becomes alkali-soluble after irradiation becomes sufficient, and the developability tends to be excellent. When the proportion of constituent unit (A) is below the upper limit, excessive development is suppressed, and the solvent resistance tends to be excellent. In this invention, the proportion of constituent unit in the copolymer is based on the weight of the compound (monomer) used in copolymerization. For example, the proportion of constituent unit (A) in the copolymer means the ratio of the amount of unsaturated carboxylic acid or its acid anhydride (a) used to the total amount (100% by weight) of the compound used in copolymerization.

[0026] [Constituent Unit (B)] The constituent unit (B) can be introduced into the copolymer by polymerizing an epoxy compound (b) represented by the following formula (b1) with an unsaturated carboxylic acid or its acid anhydride (a). [ka]

[0027] In formula (b1), R b1 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2R represents a divalent hydrocarbon group which may contain heteroatoms. b3 This represents a divalent organic group having two or more epoxy groups.

[0028] R b1 Examples of C1-C7 alkyl groups in include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, pentyl, hexyl, and heptyl groups. From the viewpoint of copolymerizability and reactivity, R b1 The hydrogen atom, methyl group, or ethyl group is preferred.

[0029] R b2 In a divalent hydrocarbon group which may contain a heteroatom, the heteroatom may be bonded to the terminal of the hydrocarbon group or interposed between the carbon atoms constituting the hydrocarbon group. The heteroatom is not particularly limited, but examples include a nitrogen atom, an oxygen atom, and a sulfur atom. b2 It may have substituents.

[0030] R b2Examples of divalent hydrocarbon groups that may contain heteroatoms include linear or branched alkylene groups such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene (alkylene groups having 1 to 12 carbon atoms are preferred, alkylene groups having 1 to 6 carbon atoms are more preferred, and alkylene groups having 1 to 3 carbon atoms are particularly preferred); and cycloalkylene groups such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene (cycloalkylene groups having 3 to 12 carbon atoms are preferred, and cycloalkylene groups having 4 to 10 carbon atoms are more preferred). Examples include cycloalkylene groups having 5 to 8 carbon atoms, which are particularly preferred; oxyalkylene groups such as oxymethylene groups, oxyethylene groups, and oxypropylene groups (oxyalkylene groups having 1 to 12 carbon atoms are preferred, and oxyalkylene groups having 1 to 6 carbon atoms are more preferred); thioalkylene groups such as thiomethylene groups, thioethylene groups, and thiopropylene groups (thioalkylene groups having 1 to 12 carbon atoms are preferred, and thioalkylene groups having 1 to 6 carbon atoms are more preferred); aminoalkylene groups such as aminomethylene groups, aminoethylene groups, and aminopropylene groups (aminoalkylene groups having 1 to 12 carbon atoms are preferred, and aminoalkylene groups having 1 to 6 carbon atoms are more preferred); and divalent groups formed by the bonding of two or more of these. Among these, linear alkylene groups having 1 to 3 carbon atoms are preferred, and ethylene groups are more preferred from the viewpoint of storage stability.

[0031] R b3This is a divalent organic group having two or more epoxy groups. That is, it is a divalent organic group having at least two epoxy groups. The epoxy groups are preferably epoxy groups other than alicyclic epoxy groups. This is because ordinary epoxy groups (epoxy groups other than alicyclic epoxy groups) have superior reactivity compared to alicyclic epoxy groups, which leads to the copolymer of the present invention exhibiting good curability even at relatively low temperatures. Furthermore, in the epoxy compound (b) represented by formula (b1), if the structure around the epoxy groups is crowded, the reactivity of the epoxy groups decreases. Therefore, by using epoxy groups other than alicyclic epoxy groups to improve curability, good solvent resistance and curability can be achieved. An alicyclic epoxy group refers to a group composed of two adjacent carbon atoms and an oxygen atom constituting an alicyclic ring, such as a cyclohexene oxide group. The at least two epoxy groups may be the same or different. 3b It may have substituents.

[0032] R b3 Because the divalent organic group in has two or more epoxy groups, the amount of epoxy groups per molecule of acrylic monomer increases, and therefore the crosslinking density of the cured copolymer containing the monomer as a constituent unit increases. For this reason, the formed cured film takes on a dense structure, which is thought to improve solvent resistance. Note that the number of epoxy groups in epoxy compound (b) represented by formula (b1), i.e., R b3 The number of epoxy groups in the divalent organic group is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. Being within this preferred range tends to result in good solvent resistance and curability.

[0033] R b3 Examples of organic groups in this context include hydrocarbon groups, heterocyclic groups, and divalent groups formed by the bonding of two or more of these groups via single bonds or linking groups.

[0034] Examples of the hydrocarbon groups include linear or branched alkylene groups such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene (e.g., alkylene groups having 1 to 12 carbon atoms); monocyclic or polycyclic cycloalkylene groups such as 1,2-cyclopentylene and 1,2-cyclohexylene (e.g., cycloalkylene groups having 3 to 12 carbon atoms); and arylene groups such as phenylene. Examples of the heterocyclic groups include 5 to 10-membered heterocycloalkylene groups and heteroarylene groups containing at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur atoms (e.g., heterocycles containing oxygen atoms such as furan rings; heterocycles containing nitrogen atoms such as pyrrole rings and pyridine rings; and groups obtained by removing two hydrogen atoms from the structural formula of heterocycles containing sulfur atoms such as thiophene rings). Examples of the linking groups include heteroatoms such as nitrogen atoms, oxygen atoms, and sulfur atoms (e.g., ether bonds (-O-), thioether bonds (-S-), etc.), carbonyl groups (-CO-), ester bonds (-COO-), amide bonds (-CONH-), and carbonate bonds (-OCOO-).

[0035] That is, R b3 This indicates a divalent group in which at least two hydrogen atoms in these organic groups are substituted with epoxy groups.

[0036] R b3 Preferably, the group has two or more epoxy groups, and the two or more hydrocarbon groups are linked via a linking group containing an oxygen atom (particularly an ether bond). In this case, the two or more hydrocarbon groups other than the epoxy group are preferably linear or branched alkylene groups (particularly alkylene groups with 1 to 4 carbon atoms in the main chain), monocyclic or polycyclic cycloalkylene groups (particularly cycloalkylene groups with 5 to 8 carbon atoms) which may have substituents such as alkyl groups, and more preferably ethylene groups, cyclohexene groups, and norbornene groups which may have substituents. The two or more hydrocarbon groups may be the same or different. Note that the number of carbon atoms in the main chain of the alkylene group is R b2This refers to the number of carbon atoms in the shortest carbon chain of the alkylene group, from the carbon atom bonded to the O- to the carbon atom bonded to the OH.

[0037] Examples of the epoxy compound (b) include the compound represented by the following formula (b2).

[0038] [ka]

[0039] In formula (b2), R b1 This is R in equation (b1). b1 This is similar to what was described above, and represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 This is R in equation (b1). b2 This is similar to what was described earlier, and represents a divalent hydrocarbon group which may contain heteroatoms. b4 represents a divalent hydrocarbon group that is identical or different, has an epoxy group, and may also contain a heteroatom. nb1 represents an integer of 2 or more.

[0040] R b4 In this context, a divalent hydrocarbon group having an epoxy group and possibly containing heteroatoms means a divalent hydrocarbon group in which one or more hydrogen atoms are substituted for an epoxy group and which may contain heteroatoms. The epoxy group is preferably an epoxy group other than an alicyclic epoxy group. 4b It may have substituents.

[0041] R b4Examples of divalent hydrocarbon groups that may contain heteroatoms include linear or branched alkylene groups such as methylene, methylmethylene, dimethylmethylene, and ethylene (alkylene groups with 1 to 8 carbon atoms are preferred, and alkylene groups with 2 to 4 carbon atoms are more preferred); monocyclic or polycyclic cycloalkylene groups such as 1,2-cyclopentylene (cycloalkylene groups with 3 to 12 carbon atoms are preferred, cycloalkylene groups with 4 to 10 carbon atoms are more preferred, and cycloalkylene groups with 5 to 8 carbon atoms are particularly preferred); oxyalkylene groups such as oxymethylene, oxyethylene, and oxypropylene; thioalkylene groups such as thiomethylene, thioethylene, and thiopropylene; aminoalkylene groups such as aminomethylene, aminoethylene, and aminopropylene; and divalent groups formed by the bonding of two or more of these. b4 This represents a group in which at least one hydrogen atom of a divalent hydrocarbon group, which may contain these heteroatoms, is substituted with an epoxy group.

[0042] R b4 In this context, the divalent hydrocarbon groups, excluding epoxy groups and which may contain heteroatoms, are preferably linear or branched alkylene groups (particularly alkylene groups with 1 to 4 carbon atoms in the main chain), monocyclic or polycyclic cycloalkylene groups (particularly cycloalkylene groups with 5 to 8 carbon atoms) which may have substituents such as alkyl groups, and more preferably ethylene groups, cyclohexene groups, and norbornene groups which may have substituents. Note that the R in two or more parentheses with nb1 is b4 They may be the same or they may be different.

[0043] From the viewpoint of storage stability, the epoxy compound (b1) is preferably a compound represented by the following formula (b3) or a compound represented by the following formula (b4). The epoxy compound (b1) can be used alone or in combination of two or more types.

[0044] [ka]

[0045] In equation (b3), R b1 This is R in equation (b1). b1 This is similar to what was described above, and represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 This is R in equation (b1). b2 This is similar to what was described earlier, and represents a divalent hydrocarbon group which may contain heteroatoms. b5 R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, either identical or different. b6 represents a divalent hydrocarbon group, which may be the same or different and may contain single bonds or heteroatoms. nb2 and nb3 are each integers greater than or equal to 0, and the sum of nb2 and nb3 is 2 or greater. The oxirane ring may have an alkyl group having 1 to 6 carbon atoms.

[0046] [ka]

[0047] In formula (b4), R b1 This is R in equation (b1). b1 This is similar to what was described above, and represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 This is R in equation (b1). b2 This is similar to what was described earlier, and represents a divalent hydrocarbon group which may contain heteroatoms. b7 R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, either identical or different. b8 is a group bonded to ring Z, which may be the same or different, and may contain single bonds or heteroatoms, representing a divalent hydrocarbon group. m is an integer from 1 to 3. Ring Z represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms. nb4 is an integer of 2 or more. The oxirane ring may have an alkyl group having 1 to 6 carbon atoms. Ring Z is R b7 and R b8 The other group may be an alkyl group having 1 to 6 carbon atoms.

[0048] R b5 and R b7The alkyl group having 1 to 6 carbon atoms in the compound is not particularly limited, but examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, pentyl group, hexyl group, etc.

[0049] R b6 and R b8 The divalent hydrocarbon group in which heteroatoms may be present is, for example, a linear or branched alkylene group such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, trimethylene, butylene, pentylene, and hexylene (alkylene groups having 1 to 18 carbon atoms are preferred, alkylene groups having 2 to 12 carbon atoms are more preferred, and alkylene groups having 3 to 8 carbon atoms are particularly preferred); or a cycloalkylene group such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene (cycloalkylene groups having 3 to 12 carbon atoms are preferred, and cycloalkylene groups having 4 to 10 carbon atoms are particularly preferred). Examples include: a C5-C8 cycloalkylene group is more preferred; an oxyalkylene group such as an oxymethylene group, oxyethylene group, or oxypropylene group (an oxyalkylene group having 1 to 12 carbon atoms is preferred, and an oxyalkylene group having 1 to 6 carbon atoms is more preferred); a thioalkylene group such as an thiomethylene group, thioethylene group, or thiopropylene group (an thioalkylene group having 1 to 12 carbon atoms is preferred, and an thioalkylene group having 1 to 6 carbon atoms is more preferred); an aminoalkylene group such as an aminomethylene group, aminoethylene group, or aminopropylene group (an aminoalkylene group having 1 to 12 carbon atoms is preferred, and an aminoalkylene group having 1 to 6 carbon atoms is more preferred); and a divalent group formed by the bonding of two or more of these.

[0050] R b6 From the viewpoint of storage stability, linear or branched alkylene groups having 1 to 18 carbon atoms are preferred, and more preferably linear or branched alkylene groups having 3 to 8 carbon atoms. b8 From the viewpoint of storage stability, a single bond is preferable.

[0051] Examples of alicyclic hydrocarbon rings having 3 to 20 carbon atoms in ring Z include cycloalkane rings with 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 12 members) such as cyclopropane rings, cyclobutane rings, cyclopentane rings, cyclohexane rings, and cyclooctane rings; monocyclic alicyclic hydrocarbon rings with 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 10 members) such as cycloalkene rings, cyclopropene rings, cyclobutene rings, cyclopentene rings, and cyclohexene rings; adamantane rings; norbornane rings, norbornene rings, bornane rings, isobornane rings, tricyclo[5.2.1.0 2,6 ] Decane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 ] Rings containing norbornane rings such as dodecane rings; perhydroindene rings, decalin rings (perhydronaphthalene rings), perhydrofluorene rings (tricyclo[7.4.0.0 3,8 [Tridecane ring), perhydroanthracene ring, or other polycyclic aromatic condensed rings are hydrogenated (preferably fully hydrogenated rings); tricyclo[4.2.2.1 2,5 Examples include 2-6 ring bridged hydrocarbon rings, such as bicyclic, tricyclic, and tetracyclic bridged hydrocarbon rings (e.g., bridged hydrocarbon rings with 6-20 carbon atoms), such as undecane rings. Among these, 5-12 membered cycloalkane rings or norbornane rings are preferred from the viewpoint of storage stability.

[0052] nb2 and nb3 are integers greater than or equal to 0. The sum of nb2 and nb3 is not particularly limited as long as it is 2 or greater, but is preferably between 2 and 20, more preferably between 2 and 12, even more preferably between 2 and 8, particularly preferably between 2 and 4, and most preferably 3.

[0053] nb4 is not particularly limited as long as it is an integer of 2 or greater, but for example it is preferably 2 to 20, more preferably 2 to 12, even more preferably 2 to 8, particularly preferably 2 to 4, and most preferably 3. m is not particularly limited as long as it is an integer of 1 to 3, but for example it is preferably 1.

[0054] In the compounds represented by formula (b3) and formula (b4), the C1-C6 alkyl group that the oxirane ring may have is not particularly limited, but examples include C1-C6 alkyl groups. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, pentyl group, hexyl group, and the like.

[0055] Examples of C1-C6 alkyl groups that ring Z may have include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, pentyl, and hexyl groups.

[0056] In the compounds represented by formula (b3) and formula (b4), it is preferable that a hydrocarbon chain with a certain number of carbon atoms exists between the main chain of the polyethylene oxide group and the epoxy group. That is, in the compound represented by formula (b3), R b6 The alkylene group has good storage stability because it is a linear or branched alkylene group having 1 to 18 carbon atoms (more preferably 3 to 8 carbon atoms). Furthermore, in the compound represented by formula (b4), the ring Z has good storage stability because it is a 5 to 12-membered cycloalkane ring or norbornane ring. This is thought to be because when the hydrocarbon chain between the polyethylene oxide group main chain and the epoxy group is of the above type, the structure around the epoxy group becomes crowded, reducing its reactivity and thus improving storage stability. On the other hand, the compound has the characteristic of curing even at relatively low temperatures during the curing stage.

[0057] Specific examples of compounds represented by formula (b3) include the following compounds: [ka] [ka]

[0058] Specific examples of compounds represented by formula (b4) include the following: [ka] [ka] [ka]

[0059] The proportion (content) of constituent unit (B) in the copolymer is not particularly limited, but for example, it is preferably 10 to 98% by weight, more preferably 20 to 95% by weight, even more preferably 30 to 90% by weight, and most preferably 40 to 90% by weight relative to the total constituent units of the copolymer. When the proportion of constituent unit (B) is above the lower limit, the amount of epoxy groups contained in the copolymer is suitable for curing, so it cures even at relatively low temperatures, and the crosslinked structure of the cured product becomes denser, resulting in a tendency for excellent solvent resistance. When the proportion of constituent unit (B) is below the upper limit, the amount of hydroxyl groups contained in the copolymer is appropriate, so it tends to have excellent solvent resistance, especially to highly polar solvents. In addition, the copolymer becomes hydrophilic, so it tends to have excellent developability (fast development speed and less residue).

[0060] [Constituent Unit (C)] The constituent unit (C) is derived from at least one compound selected from the group consisting of styrene (c1), which may be substituted with an alkyl group, N-substituted maleimide (c2), N-vinyl compound (c3), and an unsaturated carboxylic acid derivative (c4) represented by formula (2). The constituent unit (C) has functions such as imparting hardness to the cured product (cured film), facilitating copolymerization reactions, increasing solubility in solvents, and improving adhesion to the substrate.

[0061] The constituent unit (C) can be introduced into the copolymer by polymerizing at least one compound selected from the group consisting of (c1) to (c4) together with an unsaturated carboxylic acid or its anhydride (a) and an epoxy compound represented by formula (b1).

[0062] (Styrene(c1)) The alkyl group in styrene(c1), which may be substituted with an alkyl group, is not particularly limited, but examples include C1-C7 alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, and hexyl groups. Among these, C1-C4 alkyl groups such as methyl or ethyl groups are preferred, and methyl groups are more preferred. The alkyl group may be bonded to either the vinyl group or the benzene ring of styrene.

[0063] Typical examples of styrene(c1) which may be substituted with alkyl groups include styrene, α-methylstyrene, and vinyltoluene (o-vinyltoluene, m-vinyltoluene, p-vinyltoluene). Among these, styrene is preferred. Styrene(c1) which may be substituted with alkyl groups can be used alone or in combination of two or more types.

[0064] (N-substituted maleimide (c2)) Examples of N-substituted maleimides (c2) include compounds represented by the following formula (3). [ka]

[0065] In formula (3), R 21 This indicates a monovalent organic group.

[0066] Examples of the monovalent organic group include hydrocarbon groups and heterocyclic groups. Examples of hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, and hexyl groups (e.g., alkyl groups with 1 to 6 carbon atoms); cycloalkyl groups such as cyclopentyl, cyclohexyl, cyclooctyl, adamantyl, and norbornyl groups; aryl groups such as phenyl groups; aralkyl groups such as benzyl groups; and groups formed by the bonding of two or more of these groups. Examples of heterocyclic groups include 5 to 10-membered heterocycloalkyl groups and heteroaryl groups containing at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur atoms.

[0067] The N-substituted maleimide (c2) is not particularly limited, but examples include N-alkyl maleimides such as N-methyl maleimide, N-ethyl maleimide, and N-propyl maleimide; N-cycloalkyl maleimides such as N-cyclopentyl maleimide, N-cyclohexyl maleimide, N-cyclooctyl maleimide, N-adamantyl maleimide, and N-norbornyl maleimide; N-aryl maleimides such as N-phenyl maleimide; and N-aralkyl maleimides such as N-benzyl maleimide. Among these, N-cyclohexyl maleimide is preferred. The N-substituted maleimide (c2) can be used alone or in combination of two or more types.

[0068] (N-vinyl compound (c3)) The N-vinyl compound (c3) is not particularly limited, but examples include N-vinylformamide, N-vinylacetamide, N-vinylisopropylamide, N-vinyl-N-methylacetamide, N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpiperidone, and N-vinylcaprolactam. The N-vinyl compound (c3) can be used alone or in combination of two or more.

[0069] (Unsaturated carboxylic acid derivative (C4)) The unsaturated carboxylic acid derivative (c4) can be represented by the following formula (2). [ka]

[0070] In formula (2), R 11 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. 12 represents a monovalent hydrocarbon group which may contain a heteroatom. X represents a heteroatom.

[0071] R 11 Examples of C1-C7 alkyl groups in R include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, and hexyl groups. 11 Hydrogen atoms or methyl groups are particularly preferred.

[0072] R 12 Examples of monovalent hydrocarbon groups that may contain heteroatoms include alkyl groups, heteroalkyl groups, alkenyl groups, cycloalkyl groups, heterocycloalkyl groups, aryl groups, and groups in which two or more of these are linked. 12 The carbon atoms in this bond to X.

[0073] Examples of the alkyl groups include alkyl groups having 1 to 23 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, hexyl, octyl, decyl, dodecyl, isodecyl, lauryl, and stearyl groups.

[0074] Examples of the aforementioned heteroalkyl groups include -(R 13 -O)pR 14 group (in the formula, R 13 R represents an alkylene group with 1 to 12 carbon atoms. 14 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. p represents an integer of 1 or more. ), -R 15 -NR 16 R 17 group (in the formula, R 15 R represents an alkylene group with 1 to 12 carbon atoms. 16 and R 17These each represent either the same or different hydrogen atoms or alkyl groups having 1 to 4 carbon atoms.

[0075] Examples of the aforementioned alkenyl group include alkenyl groups having 2 to 23 carbon atoms, such as allyl groups, 3-butenyl groups, and 5-hexenyl groups.

[0076] Examples of the cycloalkyl groups include cyclopentyl groups, cyclohexyl groups, cyclooctyl groups, adamantyl groups, norbornyl groups, and other cycloalkyl groups having 3 to 12 carbon atoms.

[0077] Examples of the heterocycloalkyl group include groups containing cyclic ether structures such as oxetane rings, oxolane rings, oxane rings, and oxepan rings (for example, cyclic ether-containing groups with three or more members).

[0078] Examples of the aryl group include aryl groups having 6 to 12 carbon atoms, such as phenyl groups and naphthyl groups.

[0079] Examples of heteroatoms in X include nitrogen atoms, oxygen atoms, and sulfur atoms.

[0080] The unsaturated carboxylic acid derivative (c4) represented by formula (2) is not particularly limited, but examples include alkyl-containing (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; alkylamino-containing (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and N,N-diisopropylaminoethyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. , hydroxyl group-containing (meth)acrylates such as 4-hydroxybutyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, isooctyloxydiethylene glycol (meth)acrylate, phenoxytriethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and other polyalkylene glycol (meth)acrylates having heteroalkyl groups; alkenyl group-containing (meth)acrylates such as allyl (meth)acrylate; cyclohexyl (meth)acrylate, 1-adamantyl (meth)acrylate, isobolonyl (meth)acrylate, tricyclo[5,2,1,0 2,6(meth)acrylates having monocyclic or polycyclic cycloalkyl groups such as decane-8-ol (meth)acrylate; (meth)acrylates having epoxy groups (oxyranyl groups) such as glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 2-ethylglycidyl (meth)acrylate, 2-glycidyloxyethyl (meth)acrylate, 3-glycidyloxypropyl (meth)acrylate, glycidyloxyphenyl (meth)acrylate, oxetanyl (meth)acrylate, 3 -Methyl-3-oxetanyl(meth)acrylate, 3-ethyl-3-oxetanyl(meth)acrylate, (3-methyl-3-oxetanyl)methyl(meth)acrylate, (3-ethyl-3-oxetanyl)methyl(meth)acrylate, 2-(3-methyl-3-oxetanyl)ethyl(meth)acrylate, 2-(3-ethyl-3-oxetanyl)ethyl(meth)acrylate, 2-[(3-methyl-3-oxetanyl)methyloxy]ethyl(meth)acrylate, 2-[(3-ethyl-3-oxetanyl )methyloxy]ethyl (meth)acrylate, 3-[(3-methyl-3-oxetanyl)methyloxy]propyl (meth)acrylate, 3-[(3-ethyl-3-oxetanyl)methyloxy]propyl (meth)acrylate, and other (meth)acrylates having an oxetanyl group, such as tetrahydrofurfuryl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 2-( (Meth)acrylates having heterocycloalkyl groups (e.g., cyclic ether-containing groups of 3 or more members), such as (meth)acrylates containing alicyclic epoxy groups, such as 3,4-epoxycyclohexyl)ethyl (meth)acrylate, 2-(3,4-epoxycyclohexylmethyloxy)ethyl (meth)acrylate, and 3-(3,4-epoxycyclohexylmethyloxy)propyl (meth)acrylate; (meth)acrylates having aryl groups, such as phenyl (meth)acrylate and benzyl (meth)acrylate;Examples of alkoxysilyl group-containing (meth)acrylates include 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, and 8-(meth)acryloxyoctyltrimethoxysilane. The unsaturated carboxylic acid derivative (c4) represented by formula (2) can be used alone or in combination of two or more. Among these, methyl (meth)acrylate is preferred.

[0081] The proportion (content) of constituent unit (C) in the copolymer is not particularly limited, but for example, it is preferably 0 to 88% by weight relative to the total constituent units of the copolymer, more preferably 1 to 60% by weight, even more preferably 5 to 40% by weight, particularly preferably 10 to 30% by weight, and most preferably 15 to 25% by weight. When the proportion of constituent unit (C) is 1% by weight or more (particularly 5% by weight or more), functions such as imparting hardness to the cured product (cured film), facilitating the copolymerization reaction, increasing solubility in the solvent, and improving adhesion to the substrate are effectively expressed. When the proportion of constituent unit (C) is below the above upper limit, the proportions of constituent units (A) and (B) become relatively larger, so the functions of constituent units (A) and (B) are effectively expressed.

[0082] [Component Unit (D)] The copolymer of the present invention may contain a constituent unit (D) other than the constituent units (A) to (C) described above. Examples of constituent unit (D) include constituent units derived from (meth)acrylamide and (meth)acrylonitrile.

[0083] If the copolymer of the present invention contains constituent unit (A) and constituent unit (B) but does not contain constituent unit (C), the total amount of constituent unit (A) and constituent unit (B) is preferably 90% by weight or more, more preferably 95% by weight or more, even more preferably 99% by weight or more, and may be substantially 100% by weight, relative to the total amount of constituent units constituting the copolymer. Furthermore, if the copolymer of the present invention contains constituent unit (A), constituent unit (B), and constituent unit (C), the total amount of constituent units (A) to (C) is preferably 90% by weight or more, more preferably 95% by weight or more, even more preferably 99% by weight or more, and may be substantially 100% by weight, relative to the total amount of constituent units constituting the copolymer.

[0084] The weight-average molecular weight (Mw) of the copolymer is not particularly limited, but is preferably 1,000 to 200,000, more preferably 3,000 to 100,000, even more preferably 5,000 to 50,000, and particularly preferably 8,000 to 20,000. The molecular weight distribution (ratio of weight-average molecular weight to number-average molecular weight: Mw / Mn) of the copolymer is not particularly limited, but is preferably 6.0 or less (e.g., 1.1 to 6.0), more preferably 1.5 to 5.0, and even more preferably 2.0 to 4.0. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) can be measured, for example, by GPC using polystyrene as a standard substance, and are preferably measured by the method used in the examples.

[0085] The copolymer of the present invention is useful as a material for forming protective films and insulating films because its cured product has excellent solvent resistance and high insulating properties. Furthermore, because its cured product has excellent storage stability, the copolymer of the present invention is useful as a binder resin or pigment dispersion resin.

[0086] <Method for producing copolymers> The copolymer of the present invention can be produced by copolymerizing an unsaturated carboxylic acid or its anhydride (a), an epoxy compound represented by formula (b1) (b), at least one compound selected from the group consisting of (c1) to (c4) as needed, and a compound corresponding to the constituent unit (D). Hereinafter, compounds that can be introduced into copolymers such as unsaturated carboxylic acid or its anhydride (a) may be collectively referred to as "monomers".

[0087] In the production method of the present invention, the copolymerization reaction of monomers may be carried out in the presence of a polymerization initiator. Conventional or known radical polymerization initiators can be used as the polymerization initiator, and examples include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), diethyl-2,2'-azobis(2-methylpropionate), and dibutyl-2,2'-azobis(2-methylpropionate); organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl peroxypivalate, and 1,1-bis(t-butylperoxy)cyclohexane; and hydrogen peroxide. When a peroxide is used as a radical polymerization initiator, it may be combined with a reducing agent to form a redox-type initiator. Among these, azo compounds are preferred, and 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobis(2-methylpropionate) are more preferred.

[0088] The amount of polymerization initiator used is not particularly limited as long as it does not hinder a smooth copolymerization reaction, but for example, 1 to 20 parts by weight and more preferably 3 to 15 parts by weight per 100 parts by weight of the total amount of monomers.

[0089] The copolymerization reaction of the present invention can be carried out by conventional methods used in the production of acrylic polymers or styrene polymers, such as solution polymerization, bulk polymerization, suspension polymerization, bulk-suspension polymerization, emulsion polymerization, etc. The monomers and the polymerization initiator may each be supplied to the reaction system in one batch, or a part or all of them may be dropped into the reaction system. For example, a method of dropping a solution in which a polymerization initiator is dissolved in a polymerization solvent into a monomer or a mixed solution of a monomer and a polymerization solvent maintained at a constant temperature for polymerization, or a method of dropping a solution in which a monomer and a polymerization initiator are previously dissolved in a polymerization solvent into a polymerization solvent maintained at a constant temperature for polymerization (dropwise polymerization method), etc. can be adopted.

[0090] It is preferable that the copolymer of the present invention is obtained by subjecting the monomers to a copolymerization reaction in a polymerization solvent. The polymerization solvent can be appropriately selected according to the monomer composition, etc. For example, ethers (chain ethers such as diethyl ether; ethylene glycol mono- or dialkyl ethers, diethylene glycol mono- or dialkyl ethers, propylene glycol mono- or dialkyl ethers, propylene glycol mono- or diaryl ethers, dipropylene glycol mono- or dialkyl ethers, tripropylene glycol mono- or dialkyl ethers, 1,3-propanediol mono- or dialkyl ethers, 1,3-butanediol mono- or dialkyl ethers, 1,4-butanediol mono- or dialkyl ethers, glycerin mono-, di- or trialkyl ethers, etc., glycol ethers; cyclic ethers such as tetrahydrofuran, dioxane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, C 5-6 cycloalkanediol mono- or diacetate, C 5-6Carboxylic acid esters such as cycloalkane dimethanol mono or diacetate; ethylene glycol monoalkyl ether acetate, ethylene glycol mono or diacetate, diethylene glycol monoalkyl ether acetate, diethylene glycol mono or diacetate, propylene glycol monoalkyl ether acetate, propylene glycol mono or diacetate, dipropylene glycol monoalkyl ether acetate, dipropylene glycol mono or diacetate, 1,3-propanediol monoalkyl ether acetate, 1,3-propanediol mono or diacetate, 1,3-butanediol monoalkyl ether acetate, 1,3-butanediol mono or diacetate, 1,4-butanediol monoalkyl ether acetate, 1,4-butanediol mono or diacetate, glycerin mono, di or triacetate, glycerin mono or di C 1-4 (Alkyl ether di or monoacetate, tripropylene glycol monoalkyl ether acetate, tripropylene glycol mono or diacetate, and other glycol acetates or glycol ether acetates, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 3,5,5-trimethyl-2-cyclohexen-1-one, etc.), amides (N,N-dimethylacetamide, N,N-dimethylformamide, etc.), sulfoxides (dimethyl sulfoxide, etc.), alcohols (methanol, ethanol, propanol, C 5-6 Cycloalkanediol, C 5-6 Examples include cycloalkane dimethanol, hydrocarbons (such as aromatic hydrocarbons like benzene, toluene, and xylene; aliphatic hydrocarbons like hexane; alicyclic hydrocarbons like cyclohexane, etc.); and mixed solvents thereof.

[0091] The reaction temperature in the polymerization reaction can be appropriately selected depending on the type and composition of the monomers and is not particularly limited, but for example, 30 to 150°C is preferred.

[0092] The reaction solution containing the copolymer obtained by the above method can be purified by precipitation or reprecipitation as necessary. The solvent used for precipitation or reprecipitation may be an organic solvent, water, or a mixture thereof. Examples of organic solvents include hydrocarbons (aliphatic hydrocarbons such as pentane, hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene), halogenated hydrocarbons (aliphatic halogenated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride; halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene), nitro compounds (nitromethane, nitroethane, etc.), nitriles (acetonitrile, benzonitrile, etc.), ethers (chain ethers such as diethyl ether, diisopropyl ether, and dimethoxyethane; cyclic ethers such as tetrahydrofuran and dioxane), ketones (acetone, methyl ethyl ketone, diisobutyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.), carbonates (dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), alcohols (methanol, ethanol, propanol, isopropyl alcohol, butanol, etc.), carboxylic acids (acetic acid, etc.), and mixed solvents containing these solvents.

[0093] <Curable resin composition> The curable resin composition of the present invention is characterized by containing the copolymer of the present invention. It may also contain curable compounds other than the copolymer of the present invention, a cationic polymerization initiator, and a solvent.

[0094] The curable compounds other than the copolymers of the present invention are not particularly limited, but examples include polyfunctional vinyl compounds, polyfunctional thiol compounds, and polyfunctional epoxy compounds.

[0095] The polyfunctional vinyl compound is not particularly limited as long as it is a compound having two or more vinyl groups, but examples include: di(meth)acrylates of alkylene glycols such as ethylene glycol and propylene glycol; di(meth)acrylates of polyalkylene glycols such as polyethylene glycol and polypropylene glycol; di(meth)acrylates of hydroxylated polymers such as hydroxypolybutadiene at both ends, hydroxypolyisoprene at both ends, and hydroxypolycaprylactone at both ends; glycerin, 1,2,4-butanetriol, and trimethylol. Examples include poly(meth)acrylates of trivalent or higher polyhydric alcohols such as alkanes, tetramethylolalkanes, pentaerythritol, and dipentaerythritol; poly(meth)acrylates of polyalkylene glycol adducts of trivalent or higher polyhydric alcohols; poly(meth)acrylates of cyclic polyols such as 1,4-cyclohexanediol and 1,4-benzenediol; and oligo(meth)acrylates such as polyester(meth)acrylate, epoxy(meth)acrylate, urethane(meth)acrylate, and silicone resin(meth)acrylate. Polyfunctional vinyl compounds can be used alone or in combination of two or more.

[0096] The polyfunctional thiol compounds are not particularly limited as long as they are compounds having two or more thiol groups, but examples include hexanedithiol, decanedithiol, 1,4-butanediol bisthiopropionate, 1,4-butanediol bisthioglycolate, ethylene glycol bisthioglycolate, ethylene glycol bisthiopropionate, trimethylolpropane tristhioglycolate, trimethylolpropane tristhiopropionate, trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, tris(2-hydroxyethyl) isocyanurate trimercaptopropionate, and 1,4-dimethylmercaptobenzene. Examples include 2,4,6-trimercapto-s-triazine, 2-(N,N-dibutylamino)-4,6-dimercapto-s-triazine, tetraethylene glycol bis-3-mercaptopropionate, trimethylolpropane tris-3-mercaptopropionate, tris(3-mercaptopropynyloxyethyl) isocyanurate, pentaerythritol tetrakiss-3-mercaptopropionate, dipentaerythritol tetrakiss-3-mercaptopropionate, 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and pentaerythritol tetrakiss(3-mercaptobutyrate). Polyfunctional thiol compounds can be used individually or in combination of two or more.

[0097] The polyfunctional epoxy compound is not particularly limited as long as it is a compound having two or more epoxy groups, but for example, glycidyl ether type epoxy compounds [glycidyl ethers produced by the reaction of polyhydroxy compounds (bisphenols, polyhydric phenols, alicyclic polyhydric alcohols, aliphatic polyhydric alcohols, etc.) with epichlorohydrin (e.g., (poly)C such as ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, etc.] 2-4Alkylene glycol diglycidyl ethers; diglycidyl ethers of polyhydric phenols such as resorcinol and hydroquinone; diglycidyl ethers of alicyclic polyhydric alcohols such as cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenols; bisphenols (such as 4,4'-dihydroxybiphenyl and bis(hydroxyphenyl)alkanes like bisphenol A) or their C 2-3 Examples include diglycidyl ethers of alkylene oxide adducts, novolac-type epoxy resins (phenol novolac-type or cresol novolac-type epoxy resins, etc.), glycidyl ester-type epoxy compounds, alicyclic epoxy compounds (or cyclic aliphatic epoxy resins), heterocyclic epoxy resins (triglycidyl isocyanurate (TGIC), hydantoin-type epoxy resins, etc.), and glycidylamine-type epoxy compounds [reaction products of amines and epichlorohydrin, for example, N-glycidyl aromatic amines {tetraglycidyldiaminodiphenylmethane (TGDDM), triglycidylaminophenol (TGPAP, TGMAP, etc.), diglycidylaniline (DGA), diglycidyltoluidine (DGT), tetraglycidylxylylenediamine (TGMXA, etc.), etc.}, and N-glycidyl alicyclic amines (tetraglycidylbisaminocyclohexane, etc.)]. Polyfunctional epoxy compounds can be used alone or in combination of two or more.

[0098] Examples of the cationic polymerization initiators include photocatalytic cationic polymerization initiators and thermal cationic polymerization initiators.

[0099] A photocationic polymerization initiator is a compound that generates acid upon irradiation with light, thereby initiating the curing reaction of a curable compound contained in a curable resin composition. It consists of a cation portion that absorbs light and an anion portion that is the source of acid generation. Photocationic polymerization initiators can be used alone or in combination of two or more types.

[0100] Examples of the photo cationic polymerization initiator include diazonium salt compounds, iodonium salt compounds, sulfonium salt compounds, phosphonium salt compounds, selenium salt compounds, oxonium salt compounds, ammonium salt compounds, bromine salt compounds, and the like.

[0101] Examples of the anion part of the photo cationic polymerization initiator include, for example, [(Y) s B(Phf) 4-s - (where Y represents a phenyl group or a biphenylyl group; Phf represents a phenyl group in which at least one hydrogen atom is substituted with at least one selected from a perfluoroalkyl group, a perfluoroalkoxy group, and a halogen atom; s is an integer of 0 to 3), BF4 - , [(Rf) k PF 6-k - (Rf: an alkyl group in which 80% or more of the hydrogen atoms are substituted with fluorine atoms, k: an integer of 0 to 5), AsF6 - , SbF6 - , SbF5OH - and the like.

[0102] ​​Examples of photocationic polymerization initiators include (4-hydroxyphenyl)methylbenzylsulfonium tetrakis(pentafluorophenyl)borate, 4-(4-biphenylylthio)phenyl-4-biphenylylphenylsulfonium tetrakis(pentafluorophenyl)borate, 4-(phenylthio)phenyldiphenylsulfonium phenyltris(pentafluorophenyl)borate, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium phenyltris(pentafluorophenyl)borate, diphenyl[4-(phenylthio)phenyl]sulfonium tris(pentafluoroethyl)trifluorophosphate, diphenyl[4-(phenylthio)phenyl]sulfonium tetrakis(pentafluorophenyl)borate, diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, and 4-(4-biphenylylthio)phenyl-4-biphenylylphenylsulfonium Examples include tris(pentafluoroethyl)trifluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide, phenyltris(pentafluorophenyl)borate, [4-(2-thiooxantonylthio)phenyl]phenyl-2-thiooxantonylsulfonium, phenyltris(pentafluorophenyl)borate, and 4-(phenylthio)phenyldiphenylsulfonium hexafluoroantimonate.

[0103] Examples of photocationic polymerization initiators include: "Cyracure UVI-6970", "Cyracure UVI-6974", "Cyracure UVI-6990", "Cyracure UVI-950" (all manufactured by Union Carbide, USA), "Irgacure 250", "Irgacure 261", "Irgacure 264" (all manufactured by BASF), "CG-24-61" (manufactured by Ciba-Geigy), "Optomer SP-150", "Optomer SP-151", "Optomer SP-170", "Optomer SP-171" (all manufactured by ADEKA Corporation), and "DAICAT "II" (manufactured by Daicel Corporation), "UVAC1590", "UVAC1591" (both manufactured by Daicel Cytec Corporation), "CI-2064", "CI-2639", "CI-2624", "CI-2481", "CI-2734", "CI-2855", "CI-2823", "CI-2758", "CIT-1682" (all manufactured by Nippon Soda Co., Ltd.), "PI-2074" (manufactured by Rhodia Corporation, tetrakis(pentafluorophenyl) borate) Commercially available products such as toluicumyliodonium salt, "FFC509" (manufactured by 3M), "BBI-102", "BBI-101", "BBI-103", "MPI-103", "TPS-103", "MDS-103", "DTS-103", "NAT-103", "NDS-103" (all manufactured by Midori Chemical Co., Ltd.), "CD-1010", "CD-1011", "CD-1012" (all manufactured by Sartomer, USA), "CPI-100P", "CPI-101A" (both manufactured by Sunapro Co., Ltd.) can be used.

[0104] A thermal cationic polymerization initiator is a compound that generates acid when subjected to heat treatment, thereby initiating the curing reaction of a curable compound contained in a curable resin composition. It consists of a cation part that absorbs heat and an anion part that is the source of acid generation. Thermal cationic polymerization initiators can be used alone or in combination of two or more types.

[0105] Examples of thermal cationic polymerization initiators include iodonium salt compounds and sulfonium salt compounds.

[0106] Examples of cationic moieties for thermal cationic polymerization initiators include 4-hydroxyphenyl-methyl-benzylsulfonium ions, 4-hydroxyphenyl-methyl-(2-methylbenzyl)sulfonium ions, 4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium ions, and p-methoxycarbonyloxyphenyl-benzyl-methylsulfonium ions.

[0107] Examples of the anionic portion of the thermal cationic polymerization initiator can be the same as those of the anionic portion of the photocatalytic cationic polymerization initiator.

[0108] Examples of thermal cationic polymerization initiators include 4-hydroxyphenyl-methyl-benzylsulfonium phenyltris(pentafluorophenyl)borate, 4-hydroxyphenyl-methyl-(2-methylbenzyl)sulfonium phenyltris(pentafluorophenyl)borate, 4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium phenyltris(pentafluorophenyl)borate, and p-methoxycarbonyloxyphenyl-benzyl-methylsulfonium phenyltris(pentafluorophenyl)borate.

[0109] The content of cationic polymerization initiators (total amount if two or more types are included) is preferably, for example, 0.1 to 10.0 parts by weight, more preferably 0.1 to 5.0 parts by weight, even more preferably 0.2 to 3.0 parts by weight, and particularly preferably 0.2 to 1.0 parts by weight, relative to the total amount of curable compounds (100 parts by weight) contained in the curable resin composition. If the content of cationic polymerization initiators falls below the above range, the curability tends to decrease. On the other hand, if the content of cationic polymerization initiators exceeds the above range, the cured product tends to become more prone to discoloration.

[0110] As solvents, ethers (diethyl ether; ethylene glycol mono or dialkyl ether, diethylene glycol mono or dialkyl ether, propylene glycol mono or dialkyl ether, propylene glycol mono or diaryl ether, dipropylene glycol mono or dialkyl ether, tripropylene glycol mono or dialkyl ether, 1,3-propanediol mono or dialkyl ether, 1,3-butanediol mono or dialkyl ether, 1,4-butanediol mono or dialkyl ether, glycerin mono, di or trialkyl ether, and other glycol ethers; cyclic ethers such as tetrahydrofuran and dioxane), esters (methyl acetate, ethyl acetate, butyl acetate, isoamyl acetate, ethyl lactate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, C 5-6 Cycloalkanediol mono or diacetate, C 5-6 Carboxylic acid esters such as cycloalkane dimethanol mono or diacetate; ethylene glycol monoalkyl ether acetate, ethylene glycol mono or diacetate, diethylene glycol monoalkyl ether acetate, diethylene glycol mono or diacetate, propylene glycol monoalkyl ether acetate, propylene glycol mono or diacetate, dipropylene glycol monoalkyl ether acetate, dipropylene glycol mono or diacetate, 1,3-propanediol monoalkyl ether acetate, 1,3-propanediol mono or diacetate, 1,3-butanediol monoalkyl ether acetate, 1,3-butanediol mono or diacetate, 1,4-butanediol monoalkyl ether acetate, 1,4-butanediol mono or diacetate, glycerin mono, di or triacetate, glycerin mono or di C 1-4You can use alkyl ether di or monoacetate, glycol acetates such as tripropylene glycol monoalkyl ether acetate, tripropylene glycol mono or diacetate, or glycol ether acetates, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 3,5,5-trimethyl-2-cyclohexen-1-one, etc.), or mixed solvents thereof.

[0111] In addition to the components mentioned above, the curable resin composition of the present invention may also contain, for example, resins such as novolac resins, phenolic resins, imide resins, and carboxyl group-containing resins, radical polymerization initiators, curing agents, curing accelerators, and additives (fillers, defoamers, flame retardants, antioxidants, ultraviolet absorbers, colorants, stress reducers, flexibility imparters, waxes, resins, crosslinking agents, halogen trapping agents, leveling agents, wetting improvers, etc.).

[0112] The copolymer content in the curable resin composition of the present invention is not particularly limited, but is, for example, 3 to 40% by weight. Furthermore, the copolymer content relative to the total amount of curable compounds contained in the curable resin composition is not particularly limited, but is preferably 20% by weight or more, more preferably 30% by weight or more, even more preferably 40% by weight or more, and particularly preferably 50% by weight or more.

[0113] [Cured product] By curing the curable resin composition of the present invention, a cured product with excellent physical properties can be obtained. For example, the curable resin composition can be applied to various substrates or plates using conventional coating methods such as a spin coater, dip coater, roller coater, or slit coater to form a coating film, and then the cured product can be obtained by curing the coating film. Curing can be performed, for example, by irradiating the curable resin composition with light and / or heat treatment.

[0114] The aforementioned light irradiation uses, for example, a mercury lamp, xenon lamp, carbon arc lamp, metal halide lamp, sunlight, electron source, laser light source, LED light source, etc., with an integrated irradiation dose of, for example, 500 to 5000 mJ / cm².2 It is preferable to irradiate within the range where this occurs.

[0115] The aforementioned heat treatment is preferably carried out at a temperature of, for example, 60 to 300°C (preferably 100 to 250°C) for, for example, 1 to 120 minutes (preferably 1 to 60 minutes).

[0116] Examples of substrates or base materials include silicon wafers, metals, plastics, glass, and ceramics. The thickness of the cured coating film is preferably 0.05 to 20 μm, and more preferably 0.1 to 10 μm.

[0117] The cured product (cured coating) of the present invention has excellent solvent resistance and high insulating properties, making it useful as a protective film or insulating film. [Examples]

[0118] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The weight-average molecular weight (polystyrene equivalent) and molecular weight dispersion (weight-average molecular weight Mw / number-average molecular weight Mn) of the copolymer were measured using the following apparatus. Equipment: Detector: RID-20A (Shimadzu Corporation) Pump: LC-20AD (Shimadzu Corporation) System controller: CBM-20Alite (Shimadzu Corporation) Degasser: DGU-20A3 (Shimadzu Corporation) Auto Injector: SIL-20A HT (Shimadzu Corporation) Column: Shodex KF-806L (Showa Denko) Eluent: THF (tetrahydrofuran) 0.8 ml / min Temperature: Oven: 40℃, RI: 40℃ Detector: RI Examples 1 and 2 are provided for reference only.

[0119] [Synthesis Example 1 / Preparation of Monomer B1] (first step) A solution containing 213 g of 1,2-epoxy-9-decene and 60 g of 2-hydroxyethyl methacrylate was charged and maintained at 38°C. 18 g of ethyl acetate solution containing 1.9 g of boron trifluoride diethyl ether complex was added dropwise over 2 hours, and the mixture was stirred for 3 hours. Then, 250 g of ethyl acetate and 220 g of water were added and stirred, after which the organic phase was recovered. The organic phase weighed 526 g. Gas chromatography concentrations of 2-hydroxyethyl methacrylate and ethyl acetate in the organic phase were 0.9% by weight and 48.3% by weight, respectively. The remaining 50.8% by weight was considered to be the 1,2-epoxy-9-decene adduct of 2-hydroxyethyl methacrylate (crude product) and used in the next step. 1 The average number of 1,2-epoxy-9-decene added to the adduct, as determined by 1H-NMR, was 3.0.

[0120] (Second process) To the solution obtained by dissolving 140 mg of methoquinone in 200 g of the 1,2-epoxy-9-decene adduct of 2-hydroxyethyl methacrylate (crude product) obtained in the first step, 143 g of ethyl acetate solution of 28 wt% peracetic acid was added over 2 hours while maintaining the internal temperature below 50°C. The mixture was then stirred at 55°C for 7 hours. After confirming the disappearance of the starting material (1,2-epoxy-9-decene adduct of 2-hydroxyethyl methacrylate) by NMR, the mixture was cooled to room temperature, washed once with 340 g of water, and the aqueous layer was separated. Then, 120 g of 10 wt% aqueous sodium hydroxide solution was added to the organic layer for washing, and the aqueous layer was separated. The organic layer was then washed twice with water, and the aqueous layer was separated again. Finally, 70 g of the target monomer B1 was obtained by removing low-boiling components such as solvents using an evaporator at 40°C, 10 mmHg, and for 2 hours. The yield was 80%. The yield was calculated by comparing the actual yield of monomer B1 obtained with the theoretical yield calculated from the amount of raw material (2-hydroxyethyl methacrylate) used.

[0121] [Synthesis Example 2 / Creation of Monomer B2] (first step) A solution containing 200 g of 1,2-epoxy-4-vinylcyclohexane and 70 g of 2-hydroxyethyl methacrylate was charged and maintained at 38°C. 18 g of ethyl acetate solution containing 1.9 g of boron trifluoride diethyl ether complex was added dropwise over 2 hours, and the mixture was stirred for 3 hours. Then, 252 g of ethyl acetate and 224 g of water were added and stirred, after which the organic phase was recovered. The organic layer weighed 524 g. Gas chromatography concentrations of 2-hydroxyethyl methacrylate and ethyl acetate in the organic phase were 1.2% by weight and 47.8% by weight, respectively. The remaining 51% by weight was used in the next step as a 1,2-epoxy-4-vinylcyclohexane adduct of 2-hydroxyethyl methacrylate (crude product). 1 The average number of 1,2-epoxy-4-vinylcyclohexane additions to the adduct, as determined by 1H-NMR, was 3.0.

[0122] (Second process) To the solution obtained by dissolving 140 mg of methoquinone in 200 g of the crude product of the 1,2-epoxy-4-vinylcyclohexane adduct of 2-hydroxyethyl methacrylate obtained in the first step, 182 g of ethyl acetate solution of 28 wt% peracetic acid was added over 2 hours while maintaining the internal temperature below 50°C. The mixture was then stirred at 55°C for 7 hours. After confirming the disappearance of the starting material (1,2-epoxy-4-vinylcyclohexane adduct of 2-hydroxyethyl methacrylate) by NMR, the mixture was cooled to room temperature, washed once with 400 g of water, and the aqueous layer was separated. The organic layer was then washed with 132 g of 10 wt% aqueous sodium hydroxide solution, the aqueous layer was separated, and the organic layer was washed twice with water to separate the aqueous layer. Finally, low-boiling point components such as solvents were removed using an evaporator at 40°C, 10 mmHg, and for 2 hours to obtain 94.0 g of the target monomer B2. The yield was 84%. The yield was calculated by comparing the actual yield of monomer B2 obtained with the theoretical yield calculated from the amount of raw material (2-hydroxyethyl methacrylate) used.

[0123] [Example 1] A nitrogen atmosphere was created by flowing an appropriate amount of nitrogen into a 1 L flask equipped with a reflux condenser, a dropping funnel, and a stirrer. 150 parts by weight of propylene glycol monomethyl ether acetate was placed in the flask and heated to 80°C while stirring. Then, a solution of 10 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) dissolved in 40 parts by weight of propylene glycol monomethyl ether acetate, and a solution of 15 parts by weight of acrylic acid (AA) as monomer and 85 parts by weight of monomer B1 dissolved in 10 parts by weight of propylene glycol monomethyl ether acetate were added dropwise to the flask using a dropping pump over approximately 4 hours. After the addition was complete, the solution was maintained at the same temperature for 4 hours, and then cooled to room temperature to obtain a copolymer solution with a solid content of 35.7% by weight. The weight-average molecular weight Mw of the resulting copolymer was 10,500, and the molecular weight dispersion was 3.25.

[0124] [Example 2] The same procedure as in Example 1 was followed, except that 15 parts by weight of acrylic acid (AA) and 85 parts by weight of monomer B2 were used as monomers, to obtain a copolymer solution with a solid content of 35.1% by weight. The weight-average molecular weight Mw of the resulting copolymer was 10,300, and the molecular weight dispersion was 3.56.

[0125] [Example 3] The same procedure as in Example 1 was followed, except that 15 parts by weight of acrylic acid (AA), 65 parts by weight of monomer B2, and 20 parts by weight of styrene (ST) were used as monomers, to obtain a copolymer solution with a solid content of 34.1% by weight. The weight-average molecular weight Mw of the resulting copolymer was 8,800, and the molecular weight dispersion was 3.18.

[0126] [Example 4] The same procedure as in Example 1 was followed, except that 15 parts by weight of acrylic acid (AA), 65 parts by weight of monomer B2, and 20 parts by weight of methyl methacrylate (MMA) were used as monomers, to obtain a copolymer solution with a solid content of 34.8% by weight. The weight-average molecular weight Mw of the resulting copolymer was 9,700, and the molecular weight dispersion was 3.10.

[0127] [Example 5] The same procedure as in Example 1 was followed, except that 15 parts by weight of acrylic acid (AA), 65 parts by weight of monomer B2, and 20 parts by weight of N-cyclohexylmaleimide were used as monomers, to obtain a copolymer solution with a solid content of 35.2% by weight. The weight-average molecular weight Mw of the resulting copolymer was 9,400, and the molecular weight dispersion was 3.20.

[0128] [Comparative Example 1] A 1 L flask equipped with a reflux condenser, dropping funnel, and stirrer was supplied with an appropriate amount of nitrogen to create a nitrogen atmosphere. 150 parts by weight of propylene glycol monomethyl ether acetate was added, and the flask was heated to 65°C while stirring. Then, a solution of 10 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) dissolved in 40 parts by weight of propylene glycol monomethyl ether acetate, and a solution of 15 parts by weight of acrylic acid (AA), 65 parts by weight of glycidyl methacrylate (GMA), and 20 parts by weight of methyl methacrylate (MMA) dissolved in 10 parts by weight of propylene glycol monomethyl ether acetate were added dropwise to the flask using a dropping pump over approximately 4 hours. After the addition was complete, the flask was maintained at the same temperature for approximately 4 hours, and then cooled to room temperature to obtain a copolymer solution with a solid content of 34.5% by weight. The weight-average molecular weight Mw of the resulting copolymer was 8,000, and the molecular weight dispersion was 1.90.

[0129] [Comparative Example 2] The same procedure as in Comparative Example 1 was followed, except that 15 parts by weight of acrylic acid (AA), 60 parts by weight of 3,4-epoxycyclohexylmethyl methacrylate (cyclomer M100), and 20 parts by weight of methyl methacrylate (MMA) were used as monomers, to obtain a copolymer solution with a solid content of 33.8% by weight. The weight-average molecular weight Mw of the resulting copolymer was 8,200, and the molecular weight dispersion was 1.91.

[0130] [Comparative Example 3] 15 parts by weight of acrylic acid (AA) as monomer, 60 parts by weight of 3,4-epoxytricyclo[5.2.1.0 2,6] Decane-9-yl acrylate and 3,4-epoxytricyclo[5.2.1.0 2,6 The same procedure as in Example 1 was followed, except that a mixture of decane-8-yl acrylate (monomer B3) and 20 parts by weight of methyl methacrylate (MMA) were used to obtain a copolymer solution with a solid content of 35.1% by weight. The weight-average molecular weight Mw of the resulting copolymer was 9,300, and the molecular weight dispersion was 2.04.

[0131] <Evaluation Test> The following evaluation tests were performed using the copolymer solutions obtained in the examples and comparative examples. The results are shown in Table 1. In the table, the numbers in the monomer composition column represent parts by weight.

[0132] (1) Storage stability test The weight-average molecular weight of the copolymer solutions obtained in the examples and comparative examples was measured, and after storage in a constant temperature bath at 23°C for one month, the weight-average molecular weight was measured again, and the rate of increase in weight-average molecular weight during that period was calculated using the following formula. P: Weight-average molecular weight before storage (immediately after manufacturing), Q: Weight-average molecular weight after storage Weight average molecular weight increase rate (%)={(Q / P)×100}-100

[0133] (2) Solvent resistance test - 1 Test specimens were prepared by applying the copolymer solutions obtained in the examples and comparative examples to a glass plate using a spin coater, and then heating and curing them at 150°C for 30 minutes. The thickness of the cured coating was 4 μm.

[0134] One drop each of γ-butyrolactone (γ-BL) and N-methylpyrrolidone (NMP) was added to each test specimen, and it was left for 10 minutes. After washing with water, if there was no change at all in the area where the solvent was applied, it was marked as ◎; if a slight solvent trace remained but could be wiped away, it was marked as ○; if a solvent trace remained and could not be wiped away, it was marked as △; and if the entire surface was discolored, it was marked as ×.

[0135] (3) Solvent resistance test - 2 The solvent resistance of each test specimen was evaluated in the same manner as in Solvent Resistance Test-1, except that the heat curing temperature during specimen preparation was set to 230°C.

[0136] [Table 1]

[0137] As shown in Examples 1-5 of Table 1, the copolymer of the present invention exhibits high storage stability. Furthermore, even at a curing temperature of 150°C, it shows good solvent resistance, similar to that at 230°C. On the other hand, as shown in Comparative Examples 1 and 2, copolymers that do not contain component (B) of the present invention as a constituent unit have low storage stability. In Comparative Example 3, the inclusion of monomer B3 (EDCPA) as a constituent unit resulted in high storage stability of the copolymer and good solvent resistance at a curing temperature of 230°C. However, it became clear that the solvent resistance decreased when the curing temperature was lowered to 150°C, as curing was not sufficient.

[0138] The components used in the examples and comparative examples are described below. Monomer B1: (See Synthesis Example 1) Monomer B2: (See Synthesis Example 2) GMA: Glycidyl methacrylate (manufactured by NOF Corporation) Cyclomer M100: 3,4-Epoxycyclohexylmethyl methacrylate (manufactured by Daicel Corporation) Monomer B3: 3,4-Epoxytricyclo[5.2.1.0 2,6 ] Decane-9-yl acrylate and 3,4-epoxytricyclo[5.2.1.0 2,6 A mixture of decane-8-yl acrylate (product name "E-DCPA", manufactured by Daicel Corporation) ST: Styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) MMA: Methyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) CHMI:N-Cyclohexylmaleimide (manufactured by Nippon Shokubai Co., Ltd.) MMPGAC: Propylene glycol monomethyl ether acetate (manufactured by Daicel Corporation)

[0139] In summary, the configuration of the present invention and its variations are described below. [1] A constituent unit (A) derived from an unsaturated carboxylic acid or its anhydride, and formula (b1) (wherein R b1 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 R represents a divalent hydrocarbon group which may contain heteroatoms. b3 A copolymer containing a constituent unit (B) derived from an epoxy compound represented by ), which represents a divalent organic group having two or more epoxy groups. [2] The epoxy compound is of formula (b2) (wherein R b1 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 R represents a divalent hydrocarbon group which may contain heteroatoms. b4 represents a divalent hydrocarbon group which is the same or different, has an epoxy group and may also contain a heteroatom. nb1 represents an integer of 2 or more. The copolymer is the compound represented by [1]. [3] The epoxy compound is of formula (b3) (wherein R b1 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 R represents a divalent hydrocarbon group which may contain heteroatoms. b5 R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, either identical or different. b6 represents a divalent hydrocarbon group which may be the same or different and may contain single bonds or heteroatoms. nb2 and nb3 are each integers greater than or equal to 0, and the sum of nb2 and nb3 is 2 or greater. The oxirane ring may have an alkyl group having 1 to 6 carbon atoms.) and compounds represented by formula (b4) (wherein R b1 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. b2 R represents a divalent hydrocarbon group which may contain heteroatoms. b7 R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, either identical or different. b8is a group bonded to ring Z, which may be the same or different, and may contain single bonds or heteroatoms, representing a divalent hydrocarbon group. m is an integer from 1 to 3. Ring Z represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms. nb4 is an integer of 2 or more. The oxirane ring may have an alkyl group having 1 to 6 carbon atoms. Ring Z is R b7 and R b8 The copolymer according to [1] or [2], which may have an alkyl group having 1 to 6 carbon atoms as a group other than the one represented by ). [4] The copolymer according to [3], wherein the compound represented by formula (b3) is one of the following compounds. [ka] [ka] [5] The copolymer according to [3] or [4], wherein the compound represented by formula (b4) is one of the following compounds. [ka] [ka] [ka] [6] The copolymer according to any one of [1] to [5], further comprising a constituent unit (C) derived from at least one compound selected from the group consisting of (c1) to (c4). (c1) Styrene which may be substituted with alkyl groups (c2)N-substituted maleimide (c3) N-vinyl compound (c4) Formula (2) (where R 11 R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. 12(where X represents a monovalent hydrocarbon group which may contain heteroatoms.) Unsaturated carboxylic acid derivatives represented by [7] The copolymer according to [6], wherein the styrene which may be substituted with the alkyl group is at least one selected from the group consisting of styrene, α-methylstyrene, and vinyltoluene (o-vinyltoluene, m-vinyltoluene, p-vinyltoluene). [8] The copolymer according to [6] or [7], wherein the N-substituted maleimide is at least one selected from the group consisting of N-alkyl maleimides such as N-methyl maleimide, N-ethyl maleimide, and N-propyl maleimide; N-cycloalkyl maleimides such as N-cyclopentyl maleimide, N-cyclohexyl maleimide, N-cyclooctyl maleimide, N-adamantyl maleimide, and N-norbornyl maleimide; N-aryl maleimides such as N-phenyl maleimide; and N-aralkyl maleimides such as N-benzyl maleimide. [9] The copolymer according to any one of [6] to [8], wherein the N-vinyl compound is at least one selected from the group consisting of N-vinylformamide, N-vinylacetamide, N-vinylisopropylamide, N-vinyl-N-methylacetamide, N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpiperidone, and N-vinylcaprolactam.

[10] The copolymer according to any one of [1] to [9], wherein the proportion (content) of constituent unit (A) in the copolymer is 2 to 60% by weight, 3 to 40% by weight, 5 to 25% by weight, or 10 to 20% by weight relative to the total constituent units of the copolymer.

[11] The copolymer according to any one of [1] to

[10] , wherein the proportion (content) of constituent unit (B) in the copolymer is 10 to 98% by weight, 20 to 95% by weight, 30 to 90% by weight, or 40 to 90% by weight relative to the total constituent units of the copolymer.

[12] The copolymer according to any one of [6] to

[11] , wherein the proportion (content) of constituent unit (C) in the copolymer is 0 to 88% by weight, 1 to 60% by weight, 5 to 40% by weight, 10 to 30% by weight, or 15 to 25% by weight, relative to the total constituent units of the copolymer.

[13] The copolymer according to any one of [6] to

[12] , wherein the content of component (A) is 2 to 60% by weight, the content of component (B) is 10 to 98% by weight, and the content of component (C) is 0 to 88% by weight, relative to the total structural units of the copolymer.

[14] The copolymer according to any one of [6] to

[13] , further comprising a constituent unit (D) other than the constituent units (A) to (C) as a constituent unit derived from (meth)acrylamide or (meth)acrylnitrile.

[15] The copolymer according to any one of [1] to

[14] , wherein the copolymer includes constituent unit (A) and constituent unit (B), but does not include constituent unit (C), and the total amount of constituent unit (A) and constituent unit (B) is 90% by weight or more, 95% by weight or more, 99% by weight or more, or substantially 100% by weight, relative to all constituent units constituting the copolymer.

[16] The copolymer according to any one of [6] to

[15] , wherein, if it includes constituent unit (A), constituent unit (B), and constituent unit (C), the total amount of constituent units (A) to (C) is 90% by weight or more, 95% by weight or more, 99% by weight or more, or substantially 100% by weight, relative to all constituent units constituting the copolymer.

[17] A copolymer according to any one of [1] to

[16] , wherein the weight-average molecular weight (Mw) is 1,000 to 200,000, 3,000 to 100,000, 5,000 to 50,000, or 8,000 to 20,000.

[18] The copolymer according to any one of [1] to

[17] , wherein the molecular weight distribution of the copolymer (ratio of weight-average molecular weight to number-average molecular weight: Mw / Mn) is 6.0 or less (e.g., 1.1 to 6.0), 1.5 to 5.0, or 2.0 to 4.0. A curable resin composition comprising the copolymer described in any one of [1] to

[18] .

[20] The curable resin composition according to

[19] further comprising a cationic polymerization initiator.

[21] A cured product of a curable resin composition as described in

[19] or

[20] . [Industrial applicability]

[0140] The copolymer of the present invention exhibits excellent storage stability, cures at relatively low temperatures, and the cured product has excellent solvent resistance. Furthermore, the curable resin composition containing the copolymer exhibits excellent storage stability, cures at relatively low temperatures, and the cured product has excellent solvent resistance. Moreover, the cured product of the curable resin composition has excellent solvent resistance.

Claims

1. A constituent unit (A) derived from an unsaturated carboxylic acid or its anhydride, and the following formula (b1) 【Chemistry 1】 (In the formula, R ｂ１ R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. ｂ２ R represents a divalent hydrocarbon group which may contain a heteroatom. ｂ３ This refers to a divalent organic group having two or more epoxy groups (excluding alicyclic epoxy groups). It comprises a constituent unit (B) derived from an epoxy compound represented by and a constituent unit (C) derived from at least one compound selected from the group consisting of (c1) to (c4) below, A copolymer in which the content of constituent unit (A) is 2 to 40% by weight relative to the total constituent units of the copolymer, and the content of constituent unit (C) is greater than 0 and 40% by weight or less. (c1) Styrene which may be substituted with an alkyl group (c2) N-substituted maleimide (c3) N-vinyl compound (c4) The following formula (2) 【Chemistry 4】 (In the formula, R １１ R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. １２ (where X represents a monovalent hydrocarbon group that may contain heteroatoms.) Unsaturated carboxylic acid derivatives represented by

2. The epoxy compound is of the following formula (b3) 【Chemistry 2】 (wherein, R ｂ１ represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. R ｂ２ represents a divalent hydrocarbon group which may contain a hetero atom. R ｂ５ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. R ｂ６ are the same or different and each represents a single bond or a divalent hydrocarbon group which may contain a hetero atom. nb2 and nb3 each represent an integer of 0 or more, and the sum of nb2 and nb3 is 2 or more. The oxirane ring may have an alkyl group having 1 to 6 carbon atoms.) Compounds represented by the following formula (b4) 【Transformation 3】 (In the formula, R ｂ１ R represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms. ｂ２ R represents a divalent hydrocarbon group which may contain a heteroatom. ｂ７ R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, either identical or different. ｂ８ is a group bonded to ring Z, which may be the same or different, and may contain single bonds or heteroatoms, representing a divalent hydrocarbon group. m is an integer from 1 to 3. Ring Z represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms. nb4 is an integer of 2 or more. The oxirane ring may have an alkyl group having 1 to 6 carbon atoms. Ring Z is R ｂ７ and R ｂ８ (Other groups may include alkyl groups having 1 to 6 carbon atoms.) The copolymer according to claim 1, which is at least one selected from the group consisting of compounds represented by .

3. The copolymer according to claim 1 or 2, wherein the content of constituent unit (B) relative to all constituent units constituting the copolymer is 10 to 98% by weight.

4. A curable resin composition comprising the copolymer according to any one of claims 1 to 3.

5. The curable resin composition according to claim 4, further comprising a cationic polymerization initiator.

6. A cured product of the curable resin composition described in claim 4 or 5.

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