Copolymer and thermosetting resin composition

Abstract

To provide a thermosetting resin composition exhibiting a high refractive index without lowering transmittance due to a long-wavelength shift of an absorption wavelength, while retaining high heat resistance.SOLUTION: There is provided a copolymer having structural units represented by formula (1) to formula (3), and a thermosetting resin composition containing the copolymer, wherein R0 represents a hydrogen atom or a methyl group, R2 represents a single bond or an alkylene group having 1 to 6 carbon atoms, R3 represents a blocked isocyanate group, R4 represents a single bond or an alkylene group having 1 to 6 carbon atoms, R5 represents a hydrocarbon group having 1 to 20 carbon atoms having a hydroxyl group as a substituent or the like, L represents a divalent linking group having 1 to 6 carbon atoms, m represents an integer of 0 to 4, n represents an integer of 1 to 3, and A1 represents a phenanthrene group or a naphthalene group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copolymer and a thermosetting resin composition containing the copolymer, and more particularly to a copolymer having a high refractive index, a thermosetting resin composition containing the copolymer, and a microlens using the same. [Background technology]

[0002] BACKGROUND ART Conventionally, curable resin materials have been used in a variety of applications, for example, as planarizing films and microlenses in image display devices and optical devices. These curable resin materials can be cured to exhibit various properties by using specific partial structures of the curable resin or by selecting the types of additives used in combination. Such cured products are required to have good transparency, solvent resistance, and a high refractive index.

[0003] To obtain a resin with a high refractive index, it is common to introduce sulfur atoms or aromatic rings fused to polycyclic rings. However, the introduction of sulfur atoms reduces heat resistance, and the introduction of aromatic ring groups fused to polycyclic rings reduces solubility and transmittance due to the shift in absorption wavelength to longer wavelengths.

[0004] Under these circumstances, for example, Patent Document 1 discloses a resin (copolymer) containing a structural unit represented by the following formula (a1), a structural unit represented by the following formula (a2), and a structural unit represented by the following formula (a3): Patent Document 1 describes that it is possible to provide a curable resin that has good curability and can form a cured product with a high refractive index, and a method for manufacturing a microlens using the resin (Patent Document 1, paragraph

[0013] ).

[0005] [ka]

[0006] (In formulas (a1), (a2), and (a3), R 1are each independently a hydrogen atom or a methyl group, and R 2 is a single bond or an alkylene group having 1 to 5 carbon atoms, and R 3 is a blocked isocyanate group, and R 4 is a divalent hydrocarbon group, and R 5 is a single bond or a divalent linking group, and R 6 is an organic group containing two or more benzene rings. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-203913 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the refractive index of the cured film disclosed in Patent Document 1 is not necessarily sufficient, and the performance when used as a microlens is poor. Under these circumstances, an object of the present invention is to provide a thermosetting resin composition that can form a cured product with a higher refractive index, in particular a cured product with a higher refractive index, without a decrease in transmittance due to a longer absorption wavelength, while maintaining high heat resistance. [Means for solving the problem]

[0009] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found a composition that can maintain a high refractive index without impairing the transmittance in a practical brightness range due to the shift in absorption wavelength to longer wavelengths, by introducing an aromatic ring group fused to a polycycle into an optimal substitution position. The present invention was completed based on the above findings.

[0010] That is, the present invention is summarized as follows. [1] A copolymer having a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3). [ka] (In the formula, R 0 each independently represents a hydrogen atom or a methyl group, R 2 represents a single bond or an alkylene group having 1 to 6 carbon atoms, and R 3 represents a blocked isocyanate group, and R 4 represents a single bond or an alkylene group having 1 to 6 carbon atoms, and R 5 represents a hydrocarbon group having 1 to 20 carbon atoms and having a hydroxy group as a substituent, or a phenyl group having a hydroxy group as a substituent, and the hydrocarbon group having 1 to 20 carbon atoms may be linear, branched, or cyclic. L represents a divalent linking group having 1 to 6 carbon atoms, which may be branched. m represents an integer of 0 to 4, and n represents an integer of 1 to 3. A 1 represents a phenanthrene group or a naphthalene group. [2] The copolymer according to [1] above, wherein m is 0 or 1 and n is 2 or 3 in the copolymer. [3] The formula (1) in the copolymer is the following formula (4), and A 2 and each represent a hydrogen atom, a phenanthrene group, or a naphthalene group, and at least two of them are phenanthrene groups or naphthalene groups. [ka] (In the formula, R 0 represents a hydrogen atom or a methyl group; L represents a divalent linking group having 1 to 6 carbon atoms which may be branched; m represents an integer of 0 to 4; A 2 each represents a hydrogen atom, a phenanthrene group, or a naphthalene group, and at least two of them are phenanthrene groups or naphthalene groups. [4] A 2 The copolymer according to the above [3], wherein three of the groups are phenanthrene groups or naphthalene groups. [5] In the structural unit represented by the formula (1), the m is 1, and A 1The copolymer according to any one of the above [1] to [4], wherein is a phenanthrene group or a naphthalene group, and n is 3. [6] The copolymer according to any one of the above [1] to [5], which contains at least 20 mol % of structural units represented by the formula (1) based on all structural units of the copolymer. [7] The copolymer according to any one of the above [1] to [6], wherein the copolymer has a weight average molecular weight of 2,000 to 200,000. [8] A thermosetting resin composition containing the copolymer according to any one of the above [1] to [7]. [9] The thermosetting resin composition according to [8] above, further comprising a surfactant.

[10] The thermosetting resin composition according to the above [8] or [9], which is for use in a planarizing film.

[11] The thermosetting resin composition according to the above [8] or [9], which is for use in a microlens.

[12] A cured product obtained by heating the thermosetting resin composition according to [8] or [9] above.

[13] A planarizing film made from the thermosetting resin composition according to

[10] above.

[14] A microlens made from the thermosetting resin composition according to

[11] above.

[15] A compound represented by the following formula (5): [ka] (In the formula, R 0 represents a hydrogen atom or a methyl group, L represents a divalent linking group having 1 to 6 carbon atoms which may be branched, m represents an integer of 0 to 4, and a plurality of A 2 Two of them are phenanthrene groups, and A is a group other than phenanthrene groups. 2 is a hydrogen atom.)

[16] The compound according to

[15] above, wherein the phenanthrene group has the following structure: [ka] [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a thermosetting resin composition that has a high refractive index, while maintaining high heat resistance and without a decrease in transmittance due to a shift in absorption wavelength to a longer wavelength. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 10 is a diagram showing the relationship between the wavelength of light and the internal transmittance in an example. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following describes in detail the embodiments of the present invention. Note that the following description is an example (typical example) of the embodiment of the present invention, and the present invention is not limited to the contents thereof as long as it does not depart from the gist of the present invention.

[0014] [Copolymer] The copolymer of the present invention has a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3). Hereinafter, the structural unit represented by the following formula (1) may be referred to as structural unit A1, the structural unit represented by the following formula (2) may be referred to as structural unit A2, and the structural unit represented by the following formula (3) may be referred to as structural unit A3.

[0015] [ka]

[0016] In the above formula, R 0 R each independently represents a hydrogen atom or a methyl group. 0 is a hydrogen atom, the polymerizable group is an acrylic group, and R 0 When is a methyl group, the polymerizable group is a methacryl group.

[0017] <Structural unit A1> In the structural unit A1, L represents an optionally branched divalent linking group having 1 to 6 carbon atoms. From the viewpoint of a high refractive index, an alkylene group having 2 to 4 carbon atoms is preferred, and from the viewpoint of ease of synthesis, an ethylene group having 2 carbon atoms is more preferred. Furthermore, m represents an integer of 0 to 4, and from the viewpoint of a high refractive index, it is preferably 0 or 1. From the viewpoint of achieving both a high refractive index and solubility, m is preferably 1. n represents an integer of 1 to 3, and is preferably 2 or 3 from the viewpoint of a high refractive index.

[0018] A 1 represents a phenanthrene group or a naphthalene group. When n is 2 or 3, that is, A 1 When there are multiple A 1 may be the same or different. However, for ease of synthesis, it is preferable to use a plurality of A 1 are preferably the same. The formula (1) is preferably the following formula (4): That is, A is at the ortho-position or para-position relative to the site bonding to the oxygen atom of the benzene ring. 2 is preferably bonded to the 2 are each a hydrogen atom, a phenanthrene group, or a naphthalene group, and it is preferable that at least two of them are phenanthrene groups or naphthalene groups. 2 At least two of A are preferably phenanthrene groups or naphthalene groups, and an embodiment having two or three phenanthrene groups or naphthalene groups is more preferred. 2 It is preferable that three of them are phenanthrene groups or naphthalene groups. In an embodiment having two phenanthrene groups or two naphthalene groups, the other one is preferably a hydrogen atom.

[0019] [ka]

[0020] Examples of the monomer for forming the structural unit of the above formula (4) include compounds represented by the following formula (5).

[0021] [ka]

[0022] In formula (5), R 0 represents a hydrogen atom or a methyl group, L represents a divalent linking group having 1 to 6 carbon atoms which may be branched, m represents an integer of 0 to 4, and a plurality of A 2 Two of them are phenanthrene groups, and A is a group other than phenanthrene groups. 2 is a hydrogen atom. The phenanthrene group preferably has the following structure:

[0023] [ka]

[0024] Specifically, examples of compounds for forming the structural unit A1 include compounds represented by the following chemical formulas. [ka]

[0025] [ka]

[0026] Furthermore, it is particularly preferable that the compound has two phenanthrene groups or two naphthalene groups, and the remaining one is a hydrogen atom. From the viewpoint of ease of synthesis, the compound of the above formula (4) having two phenanthrene groups or two naphthalene groups has A at one ortho position and A at the para position. 2 is more preferably bonded. From the viewpoint of ease of synthesis, the phenanthrene group is preferably bonded to the benzene ring at the 9-position, and more specifically, the following groups are preferred.

[0027] [ka]

[0028] In addition, in view of a high refractive index, in the copolymer, the m is 1, and A 1 is a phenanthrene group or a naphthalene group, n is 3, and R 0 is preferably a hydrogen atom. In addition, from the viewpoint of heat resistance and ease of manufacturing, R 0 is preferably a methyl group. Furthermore, from the viewpoint of high refractive index and ease of synthesis, compounds represented by the following chemical formula are particularly preferred.

[0029] [ka]

[0030] Furthermore, from the viewpoint of achieving both a high refractive index and high solubility in the compound or after solution polymerization, a naphthalene group is preferred, and it is particularly preferred that the naphthalene group be bonded to the benzene ring at the 2-position. More specifically, the following groups are preferred:

[0031] [ka]

[0032] (Synthesis of structural unit A1) The structural unit A1 can be synthesized by the following steps. First, a Suzuki-Miyaura coupling reaction is carried out using a halogen-substituted phenol and a corresponding boronic acid to obtain a precursor aryl-substituted phenol. The resulting aryl-substituted phenol is acrylated, or subjected to a substitution reaction with ethylene carbonate or the like followed by acrylation to obtain structural unit A1. The synthesis method for structural unit A1 may also be other methods and is not limited to the above synthesis method.

[0033] <Structural unit A2> R in structural unit A2 2 represents a single bond or an alkylene group having 1 to 6 carbon atoms. 2 If is a single bond, R 3 is directly bonded to the oxygen atom. Among these, R is the 2 is preferably an alkylene group having 1 to 6 carbon atoms, more preferably an ethylene group. Also, R 3 represents a blocked isocyanate group. A blocked isocyanate group refers to a group in which an isocyanate group is blocked with a thermally dissociable protecting group. Therefore, when the copolymer having the structural unit A2 is heated, the protecting group in the blocked isocyanate group is eliminated, and an active isocyanate group is generated.

[0034] The isocyanate group generated by heating reacts easily with functional groups having active hydrogen. 5 is a hydrocarbon group having 1 to 20 carbon atoms having a hydroxy group as a substituent, or a phenyl group having a hydroxy group as a substituent, and the hydroxy group of the hydrocarbon group or phenyl group reacts with the isocyanate group. That is, when the copolymer of the present invention is heated, an active isocyanate group is generated in the structural unit A2, and this isocyanate group (-NCO) reacts with a hydroxy group in the structural unit A3, causing crosslinking via a urethane bond (-NH-CO-O-) to occur, resulting in the formation of a cured product.

[0035] (thermally dissociable protecting group) The thermally dissociable protecting group is formed by reacting an isocyanate group with a blocking agent that provides a protecting group. Examples of such blocking agents include alcohol compounds, phenol compounds, hydroxyl group-containing compounds other than alcohol compounds and phenol compounds, active methylene compounds, amine compounds, imine compounds, oxime compounds, carbamic acid compounds, urea compounds, acid amide (lactam) compounds, acid imide compounds, triazole compounds, pyrazole compounds, pyrrole compounds, mercaptan compounds, and bisulfites.

[0036] Specific preferred examples of the (meth)acrylic acid ester that provides the structural unit A2 include the following compounds.

[0037] [ka]

[0038] Among these, the following (meth)acrylic acid esters are preferred because they are easy to produce and can easily provide resins with good curability.

[0039] [ka]

[0040] (Synthesis of structural unit A2) The structural unit A2 can be obtained by adding pyrazole, oxime, or malonic acid ester to a (meth)acrylate containing isocyanate. The synthesis method of the structural unit A2 is not limited to the above synthesis method and other methods may also be used.

[0041] <Structural unit A3> R in structural unit A3 4 represents a single bond or an alkylene group having 1 to 6 carbon atoms. 4 If is a single bond, R 5 directly bonds to the oxygen atom. R 5is a hydrocarbon group having 1 to 20 carbon atoms and having a hydroxy group as a substituent, or a phenyl group having a hydroxy group as a substituent, and as described above, the hydroxy group reacts with the isocyanate group, causing crosslinking via a urethane bond (-NH-CO-O-) to form a cured product. The hydrocarbon group having 1 to 20 carbon atoms and a hydroxy group as a substituent may be linear, branched, or cyclic. Among these, from the viewpoint of a high refractive index and high heat resistance, a hydrocarbon group having 1 to 10 carbon atoms is preferred, and an ethylene group having 2 carbon atoms is more preferred.

[0042] Specific preferred examples of the (meth)acrylic acid ester that provides the structural unit A3 include the following compounds.

[0043] [ka]

[0044] Among these, the following (meth)acrylic acid esters are preferred from the viewpoints of ease of resin production, ease of obtaining a resin with good curability, and compatibility of a high refractive index and heat resistance.

[0045] [ka]

[0046] (Synthesis of structural unit A3) The structural unit A3 can be obtained by (meth)acrylating a diol. The method for synthesizing the structural unit A3 is not limited to the above synthesis method and other methods may also be used.

[0047] The content of the structural unit A1 in the copolymer of the present invention is not particularly limited as long as it does not impair the object of the present invention, but from the viewpoint of curability, it is preferably at least 20 mol% relative to all structural units of the copolymer. From the viewpoint of achieving both good curability and a high refractive index of the cured product, the content of the structural unit A1 in the copolymer is more preferably 25 mol% or more, even more preferably 35 mol% or more, particularly preferably 40 mol% or more, and most preferably 45 mol% or more relative to all structural units of the copolymer. On the other hand, taking into consideration the contents of the other structural units A2 and A3, from the viewpoint of increasing the degree of crosslinking of the cured product, maintaining the elastic modulus at high temperatures, and improving the solubility of the resin in solvents, the content is preferably 95 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less.

[0048] The content of the structural unit A2 in the copolymer of the present invention is not particularly limited as long as it does not impair the object of the present invention, but from the viewpoints of increasing the degree of crosslinking of the cured product, maintaining the elastic modulus at high temperatures, and improving the solubility of the resin in solvents, it is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, and particularly preferably 18 mol% or more. On the other hand, from the viewpoint of achieving both good curability and a high refractive index of the cured product, it is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. The content of the structural unit A3 in the copolymer of the present invention is not particularly limited as long as it does not impair the object of the present invention, but from the viewpoints of increasing the degree of crosslinking of the cured product, maintaining the elastic modulus at high temperatures, and improving the solubility of the resin in solvents, it is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, and particularly preferably 18 mol% or more. On the other hand, from the viewpoint of achieving both good curability and a high refractive index of the cured product, it is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less.

[0049] <Other structural units> The copolymer according to the present invention may contain other structural units in addition to the structural units A1, A2, and A3 described above, as long as the object of the present invention is not impaired. Examples of other structural units include structural units derived from (meth)acrylic acid esters. (Meth)acrylic acid refers to acrylic acid or methacrylic acid.

[0050] When the copolymer according to the present invention contains structural units other than the structural units A1, A2, and A3 described above, the total amount of the structural units A1, A2, and A3 in the copolymer is preferably 80 mol % or more, more preferably 90 mol % or more, and particularly preferably 95 mol % or more, based on the total structural units in the copolymer. In order to easily achieve both a high refractive index of the cured product and good curability, it is preferable that the copolymer does not contain any other structural units and is composed only of the structural units A1, A2, and A3.

[0051] The weight-average molecular weight of the copolymer according to the present invention is preferably in the range of 2,000 to 200,000. A weight-average molecular weight of 2,000 or more is advantageous in terms of film strength and heat resistance, while a weight-average molecular weight of 200,000 or less is advantageous in terms of viscosity and solubility. From the above perspectives, the weight-average molecular weight of the copolymer is more preferably in the range of 3,000 to 150,000, and even more preferably in the range of 4,000 to 120,000. By increasing the amount of initiator or chain transfer agent, a resin with a small weight-average molecular weight can be obtained, and conversely, by decreasing the amount of initiator or chain transfer agent, a resin with a large weight-average molecular weight can be obtained. The weight average molecular weight is a molecular weight measured by gel permeation chromatography (GPC) and converted into polystyrene.

[0052] <Method of producing copolymer> The method for producing the copolymer is not particularly limited. In general, the copolymer can be obtained by mixing predetermined amounts of monomers that provide the structural units A1, A2, and A3, and, if necessary, monomers that provide other structural units, and then polymerizing the mixture in a suitable solvent in the presence of a polymerization initiator at a temperature ranging from 50°C to 120°C. The copolymer is often obtained as a solution in an organic solvent. A chain transfer agent may be used during polymerization, if necessary. The solvent used in the thermosetting resin composition described below can be used as the solvent.

[0053] The copolymer solution obtained as described above may be mixed with a poor solvent such as hexane, diethyl ether, methanol, ethyl acetate, or water to precipitate the copolymer, and the precipitated copolymer may be recovered and used. The precipitated copolymer is preferably filtered, washed, and then dried under normal pressure or reduced pressure at a temperature that does not decompose the blocked isocyanate group in the structural unit A2. In this way, a powdery solid copolymer can be recovered. The powdery copolymer may be used as is, or may be mixed with a solvent.

[0054] As the radical polymerization initiator serving as an initiator, known ones can be used, and examples thereof include azo compounds such as dimethylformamide (DMF), 2,2-azobisisobutyronitrile, 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-methylbutyronitrile), and 2,2-azobis(2-methylpropionate) dimethyl; and organic peroxides such as lauryl peroxide, benzoyl peroxide, cumene hydroperoxide, lauryl peroxide, di-t-butyl peroxide, and t-butylperoxy-2-ethylhexanoate. The content of the polymerization initiator is not particularly limited and can be set appropriately, and is typically about 0.1 to 20 parts by mass per 100 parts by mass of the polymerizable monomer.

[0055] As the chain transfer agent, known ones can be used, for example, mercaptans such as η-dodecyl mercaptan, thioglycolic acid esters such as octyl thioglycolate, α-methylstyrene dimer, terpinolene, and the like. The content of the chain transfer agent is not particularly limited and can be set appropriately, and is typically about 0.0001 to 10 parts by mass per 100 parts by mass of the polymerizable monomer.

[0056] [Thermosetting resin composition] The thermosetting resin composition of the present invention contains the copolymer described above. In addition to the copolymer, the thermosetting resin composition of the present invention preferably contains a solvent and may also contain a surfactant described below.

[0057] The type of solvent is not limited as long as it does not impair the object of the present invention, and examples thereof include monoalkyl ethers of glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, and propylene glycol monobutyl ether; Examples of suitable solvents include monoalkyl ether acetates of glycols such as glycol monobutyl ether acetate; aromatic solvents such as toluene and xylene; ketones such as acetone, methyl ethyl ketone, 2-heptanone, cyclopentanone, and cyclohexanone; and esters such as ethyl acetate, butyl acetate, ethyl ethoxyacetate, ethyl hydroxyacetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl lactate, butyl lactate, and γ-butyrolactone.

[0058] The amount of solvent used in the thermosetting resin composition is not particularly limited, and is determined appropriately depending on the application, taking into consideration the viscosity and the like. The amount of solvent used is preferably set so that the solids concentration in the thermosetting resin composition is 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. When the amount is equal to or greater than the above lower limit, a cured product can be obtained efficiently. Furthermore, the amount of solvent used is preferably set so that the solids concentration in the thermosetting resin composition is 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. When the amount is equal to or less than the above upper limit, the viscosity can be appropriately adjusted, making the composition easier to handle, such as for application.

[0059] The thermosetting resin composition of the present invention may further contain various additives within the scope of not impairing the object of the present invention. Examples of the additives include surfactants, crosslinking agents, ultraviolet absorbers, sensitizers, plasticizers, antioxidants, light stabilizers, adhesion aids, and fillers (for example, fillers for increasing the refractive index, such as zirconium oxide fine particles).

[0060] <Surfactant> The thermosetting resin composition of the present invention may contain a surfactant as a leveling agent. Conventionally known surfactants can be used as the surfactant, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants.

[0061] Examples of anionic surfactants include alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, polyoxyethylene alkyl ether sulfonates, alkyl sulfates, alkyl sulfate ester salts, higher alcohol sulfate ester salts, aliphatic alcohol sulfate ester salts, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, special polymer surfactants, etc. Also, commercially available products can be used, for example, alkyl sulfate ester salts include "EMAL 10" manufactured by Kao Corporation, alkyl naphthalene sulfonates include "PELEX NB-L" manufactured by Kao Corporation, and special polymer surfactants include "HOMOGENOL L-18" and "HOMOGENOL L-100" manufactured by Kao Corporation.

[0062] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, pentaerythritol fatty acid esters, polyoxyethylene pentaerythritol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, sorbitol fatty acid esters, polyoxyethylene sorbitol fatty acid esters, fluorine-containing surfactants, etc. Commercially available products of these surfactants include polyoxyethylene surfactants such as "Emulgen 104P" and "Emulgen A60" manufactured by Kao Corporation, and fluorine-containing surfactants such as "R-40" manufactured by DIC Corporation and "U-218" manufactured by Unichem Co., Ltd.

[0063] Examples of cationic surfactants include quaternary ammonium salts, imidazoline derivatives, and alkylamine salts. Examples of amphoteric surfactants include betaine compounds, imidazolium salts, imidazolines, and amino acids. Commercially available alkylamine salts include "Acetamine 24" manufactured by Kao Corporation, and quaternary ammonium salts include "Quatamine 24P" and "Quatamine 86W" manufactured by Kao Corporation.

[0064] <Cured product> The thermosetting resin composition of the present invention is molded into a desired shape and then heated to form a cured product, which has a high refractive index due to the inclusion of the structural unit A1 derived from the copolymer. The refractive index of the cured product, when measured using light of 550 nm, is preferably 1.60 or more, more preferably 1.63 or more, and even more preferably 1.65 or more. There is no particular upper limit to the refractive index, but it is usually 1.75 or less. Specific examples of the cured product include, but are not limited to, planarizing films as cured products to be formed into films, and microlenses as cured products to be processed into lens shapes. Factors such as the curvature and formed height of microlenses are determined taking into account the focus of concentrated light, but a high refractive index is preferred because it allows light to be concentrated without increasing the curvature.

[0065] <Planarization film> The thermosetting resin composition of the present invention is useful as a planarizing film. Examples of methods for forming the planarizing film include a method of applying a thermosetting resin composition containing a solvent and a copolymer (the thermosetting resin composition of the present invention) onto a substrate and then removing the solvent from the coating, a method of pouring a liquid of the thermosetting resin composition of the present invention onto a substrate and then removing the solvent, and a method of filling a liquid of the thermosetting resin composition of the present invention into a mold having a recess of a predetermined shape and then removing the solvent from the composition in the mold. The method for applying the thermosetting resin composition of the present invention to a substrate is not particularly limited. For example, the thermosetting resin composition of the present invention can be applied to a substrate to a desired film thickness using a contact transfer type coating device such as a roll coater, a reverse coater, a bar coater, or a slit coater, or a non-contact type coating device such as a spinner (rotary coating device) or a curtain flow coater, to form a planarizing film.

[0066] After molding the thermosetting resin composition containing the solvent and the copolymer by the above method, the solvent is removed by a suitable heat treatment (pre-baking (post-applied bake (PAB)) treatment), thereby obtaining a resin molded into a desired shape. The pre-baking temperature is appropriately selected taking into consideration the boiling point of the solvent, etc. Pre-baking may be carried out at a low temperature under reduced pressure to prevent the copolymer from curing before the solvent is sufficiently removed. The pre-baking method is not particularly limited, and may be, for example, a method of drying using a hot plate at a temperature of 80°C to 120°C for a period of 60 to 120 seconds, a method of leaving the substrate at room temperature for a period of several hours to a period of several days, or a method of placing the substrate in a hot air heater or an infrared heater for a period of several tens of minutes to a period of several hours to remove the solvent.

[0067] By heating (post-baking) as described above, a cured product of the thermosetting resin is formed. The curing temperature is not particularly limited as long as the curing of the thermosetting resin proceeds well and thermal denaturation or thermal decomposition of the cured product does not occur. The upper limit of the curing temperature is, for example, preferably 250° C. or lower, more preferably 230° C. The lower limit of the curing temperature is preferably 120° C. or higher, more preferably 130° C. or higher.

[0068] A planarizing film is produced by the above method.

[0069] <Microlens manufacturing method> The thermosetting resin composition of the present invention is useful for microlenses. The method for manufacturing a microlens includes a lens material layer forming step of applying the thermosetting resin composition of the present invention onto a substrate to obtain a resin layer and crosslinking the resin layer by heating to form a lens material layer; a lens pattern forming step of forming a resist pattern on the lens material layer and then reflowing the resist pattern by heating to form a lens pattern; and a shape transfer step of dry-etching the lens material layer and the lens pattern using the lens pattern as a mask to transfer the shape of the lens pattern to the lens material layer.

[0070] Examples of the substrate include an image element including a photodiode (organic photodiode, inorganic photodiode, etc.), a silicon wafer provided with a color filter layer, etc., and a substrate such as a silicon wafer optionally further provided with an anti-reflection film. Specific examples of methods for applying the thermosetting resin composition of the present invention to a substrate include the methods described above for producing a planarizing film. The formed coating film can be appropriately subjected to a heat treatment (pre-baking (post-apply bake (PAB)) treatment) to remove the solvent in the coating film, thereby forming a lens material layer. The specific method of pre-baking is also the same as that described above in the method of manufacturing the flattening film.

[0071] The upper limit of the curing temperature in the lens material layer forming step is, for example, preferably 250° C. or lower, more preferably 230° C. or lower. The lower limit of the curing temperature is preferably 120° C. or higher, more preferably 130° C. or higher. From the viewpoint of process construction when an organic photodiode is used, the heating temperature in the lens material layer forming step can be set to a curing condition of, for example, 180° C. or less, or 150° C. or less.

[0072] The upper limit of the thickness of the formed lens material layer is 4.0 μm or less, preferably 3.0 μm or less, and particularly preferably 2.5 μm or less, and the lower limit is 100 nm or more, more preferably 200 nm or more, and particularly preferably 400 nm or more. The heating conditions for reflow in the lens pattern formation process vary depending on the types and blending ratios of each component in the composition used to form the resist pattern, the film thickness of the resist pattern, etc., but the heating temperature is, for example, 60°C or higher and 150°C or lower, and the heating time is, for example, approximately 0.5 minutes or higher and 60 minutes or lower. The film thickness of the resist pattern is preferably in the range of 100 nm or more and 4.0 μm or less, and more preferably in the range of 400 nm or more and 2.0 μm or less.

[0073] The dry etching in the shape transfer step is not particularly limited, and examples thereof include dry etching using plasma (oxygen, argon, CF4, etc.), corona discharge, etc.

[0074] By using the thermosetting resin composition of the present invention through the above steps, it is possible to form a microlens that has high visible light transmittance, a high refractive index, and is less susceptible to dimensional change and loss of transparency when used in a high-temperature environment. Therefore, the microlens formed by the above method is suitable for various applications. [Example]

[0075] The present invention will be described in more detail in the following examples and comparative examples, but the present invention is not limited thereto.

[0076] (Evaluation method) <Weight average molecular weight> The weight average molecular weight of the resin was measured using GPC "HLC-8320" (manufactured by Tosoh Corporation), and is shown as Mw in Table 1 in the examples. <Refractive index and film thickness> The refractive index at 550 nm and film thickness of the cured film coated on the supporting substrate of the glass substrate were calculated using a reflection spectroscopic film thickness meter "FE-3000" (manufactured by Otsuka Electronics Co., Ltd.). <Internal transmittance> The cured film coated on the support substrate of the glass substrate was measured using a UV-Vis-NIR spectrophotometer U-4100 (Hitachi, Ltd.). The sum of the transmittance and reflectance obtained by the measurement was calculated as the internal transmittance. The wavelength of the light used for the measurement was 300 to 850 nm.

[0077] <Heat resistance> The cured films of each Example and Comparative Example were heat-treated at 150°C for 1000 hours, and then the internal transmittance at 400 nm was measured, and the cured films were evaluated based on the degree of decrease in internal transmittance at 400 nm before and after the heat treatment.

[0078] (material) The materials used in the examples and comparative examples are the following compounds.

[0079] compound 1 [ka]

[0080] compound 2 [ka]

[0081] compound 3 [ka]

[0082] compound 4 [ka]

[0083] compound 5 [ka]

[0084] Compound 5 was synthesized with reference to Molecular Crystals and Liquid Crystals (2011), 542, 132-140.

[0085] Compound H (HEMA; hydroxyethyl methacrylate) [ka]

[0086] Compound P 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate [ka]

[0087] Synthesis Example 1 (Synthesis of Compound 1) [ka]

[0088] 2,4,6-Tribromophenol (2.3 g), phenanthrene-9-boronic acid (5.8 g), and sodium carbonate (3.5 g) were dissolved in 100 mL of dioxane and 25 mL of water and degassed by passing nitrogen gas through the solution. 10 mg of dichlorobis[di-t-butyl(p-dimethylaminophenyl)phosphino]palladium(II) was added to the reaction solution, and nitrogen gas was passed through the solution for an additional 5 minutes. The reaction solution was heated under a nitrogen atmosphere and stirred under reflux for 5 hours. After cooling to room temperature, 100 mL of ethyl acetate and 50 mL of water were added, and the mixture was separated. The resulting organic layer was washed with aqueous sodium bicarbonate. After drying the organic layer, the resulting solid was washed with hexane. The solid was dried in a vacuum dryer, yielding 4.4 g of crude compound C-1.

[0089] The NMR measurement data of compound C-1 was as follows: 1H-NMR (400MHz, CDCl3, δ, ppm) 8.84-8.66 (Ar, 6H), 8.32 (dd, Ar, 1H), 8.11 (dd, Ar, 1 H), 8.07(dd, Ar, 1H), 8.04-7.86(Ar, 8H), 7.75-7.57(Ar, 12H), 5.18-5.13(OH, 1H)

[0090] Crude compound C-1 (4.0 g) and potassium carbonate (2.0 g) were added to DMF (dimethylformamide) (40 mL) and heated to 60 °C, followed by dropwise addition of 2-bromoethanol (1.8 g). The reaction mixture was stirred for 8 hours, then returned to room temperature, ice-cold water was added, and the solid was filtered. The resulting solid was purified by column chromatography to obtain 1.95 g of compound L-1.

[0091] The NMR measurement data of compound L-1 was as follows. 1 H NMR (400MHz, CDCl3, δ, ppm) 8.83-8.69(Ar, 6H), 8.33-8.26(Ar, 1H), 8.18-8.08(Ar, 2H), 8.03-7.86(Ar, 6H), 7 .82-7.76(d, Ar, 2H), 7.76-7.56(Ar, 12H), 3.38-3.27(CH2, 2H), 2.89-2.70(CH2, 2H), 0.60, 0.51(t, OH, total 1H)

[0092] Under a nitrogen atmosphere, compound L-1 (1.92 g) and triethylamine (0.95 g) were added to THF (20 mL), and acryloyl chloride (0.78 g) was slowly added dropwise in an ice bath. After completion of the reaction, the reaction solution was poured into 20 mL of 1N aqueous sodium hydroxide solution, extracted with 50 mL of ethyl acetate, washed with 50 mL of saturated brine, dried over sodium sulfate, filtered, and concentrated. The resulting crude product was purified by column chromatography to obtain 580 mg of compound 1.

[0093] The NMR measurement data of Compound 1 was as follows: 1H NMR (400MHz, CDCl3, δ, ppm) 8.81-8.68(Ar, 6H), 8.32-8.26(Ar, 1H), 8.17-8.07(Ar, 2H), 8.03-7.85(Ar, 6H), 7.79-7.57(Ar, 14H), 5.58, 5.54(dd, CH=CH2, total 1H), 5.21, 5.19(dd, CH=CH2, total 1H), 5.06-4.94(CH=CH2, 1H), 3.56-3.37(CH2-CH2, 4H)

[0094] Synthesis Example 2 (Synthesis of Compound 2) [ka]

[0095] A 1 L four-neck flask equipped with a reflux condenser, thermometer, and stirrer was charged with 2,4,6-tribromophenol (11.0 g, 33 mmol), 2-naphthylboronic acid (18.9 g, 0.11 mol, 3.3 equiv.), sodium carbonate (14.1 g, 0.13 mol, 4.0 equiv.), toluene (200 mL), ethanol (200 mL), and water (100 mL). Nitrogen was bubbled through the flask for 2 hours. Bis[di-tert-butyl(4-dimethylaminophenyl)phosphine]dichloropalladium(II) (4.71 mg, 6.7 μmol, 0.02 mol%) was then added and the mixture was heated to reflux in a 100°C oil bath for 2 hours. After cooling, the contents of the flask were transferred to a separatory funnel and separated with toluene and water. The collected toluene layer was washed with 1 M dilute hydrochloric acid, saturated aqueous sodium bicarbonate, and saturated brine (approximately 200 mL each) and dried over sodium sulfate. After removing sodium sulfate, the mixture was concentrated, and the resulting solid was washed with cold hexane (approximately 30 mL) to obtain 10.6 g of the desired white solid, 2,4,6-tri(2-naphthyl)phenol (compound C-2), in a yield of 67%.

[0096] A 200 mL three-neck flask equipped with a reflux condenser, thermometer, and stirrer was charged with 2,4,6-tri(2-naphthyl)phenol (8.00 g, 17 mmol), ethylene carbonate (4.47 g, 51 mmol, 3.0 equiv.), sodium carbonate (0.897 g, 8.5 mmol, 0.50 equiv.), and DMF (dimethylformamide) (80 mL) and heated in a 120 °C oil bath for 2 h. After cooling, the contents of the flask were transferred to a separatory funnel and washed with 1 M dilute sulfuric acid and ethyl acetate. The collected ethyl acetate layer was washed with 1 M dilute sulfuric acid, saturated aqueous sodium bicarbonate, 5% aqueous lithium chloride, and saturated brine (approximately 100 mL each) and dried over sodium sulfate. After removing sodium sulfate and concentrating the mixture, 8.22 g of the target white solid 2-[2,4,6-tri(2-naphthyl)phenoxy]ethanol (Compound L-2) was obtained in a yield of 94%.

[0097] 2-[2,4,6-tri(2-naphthyl)phenoxy]ethanol (4.00 g, 7.7 mmol) was weighed into a 100 mL three-neck flask equipped with a calcium chloride tube, thermometer, and stir bar, and dissolved in 30 mL of dichloromethane. Triethylamine (1.6 mL, 12 mmol, 1.5 equiv.) was added and the mixture was cooled to 0.5 °C on ice. Acryloyl chloride (0.78 mL, 9.3 mmol, 1.2 equiv.) was then slowly added dropwise over 28 minutes. After the reaction mixture cooled to 0.4 °C, the ice cooling was discontinued and the mixture was stirred for 2 hours while slowly warming to room temperature. The reaction was quenched by adding water (approximately 20 mL). The contents of the flask were transferred to a separatory funnel and washed with dichloromethane and water. The recovered dichloromethane layer was washed with 1 M dilute hydrochloric acid, saturated aqueous sodium bicarbonate, and saturated brine (approximately 50 mL each) and dried over sodium sulfate. The sodium sulfate was removed, and the crude product obtained after concentration was purified by silica gel flash column chromatography using hexane and ethyl acetate to obtain the desired white solid, 2-[2,4,6-tri(2-naphthyl)phenoxy]ethyl acrylate (Compound 2), 3.42 g, 6.0 mmol, 77% yield.

[0098] The NMR measurement data of Compound 2 was as follows: 1H-NMR chart (400MHz, CDCl3, 22℃) 8.20(s,2H),8.14(s,1H),7.95-7.86(m,14H)7.55-7.47(m,6H),5.88(dd,J=15 .1,3.7Hz,2H),5.47-5.37(m,2H),3.82(t,J=4.2Hz,2H),3.54(t,J=4.2Hz,2H).

[0099] Synthesis Example 3 (Synthesis of Compound 3) [ka]

[0100] A 1 L four-neck flask equipped with a reflux condenser, thermometer, and stirrer was charged with 2,4,6-tribromophenol (10.0 g, 30 mmol), 1-naphthylboronic acid (17.2 g, 0.10 mol, 3.3 equiv.), sodium carbonate (12.8 g, 0.12 mol, 4.0 equiv.), toluene (200 mL), ethanol (200 mL), and water (100 mL). Nitrogen was bubbled through the flask for 2 hours. Bis[di-tert-butyl(4-dimethylaminophenyl)phosphine]dichloropalladium(II) (2.14 mg, 2.0 μmol, 0.01 mol%) was then added and the mixture was heated to reflux in a 100°C oil bath for 2 hours. After cooling, the contents of the flask were transferred to a separatory funnel and separated with toluene and water. The collected toluene layer was washed with 1 M dilute hydrochloric acid, saturated aqueous sodium bicarbonate, and saturated brine (approximately 200 mL each) and dried over sodium sulfate. After removing sodium sulfate, the mixture was concentrated, and the resulting solid was washed with cold hexane (approximately 30 mL) to obtain 11.5 g of the desired white solid, 2,4,6-tri(1-naphthyl)phenol (compound C-3), in 80% yield.

[0101] A 100 mL three-neck flask equipped with a reflux condenser, thermometer, and stirrer was charged with 2,4,6-tri(1-naphthyl)phenol (5.00 g, 11 mmol), ethylene carbonate (2.80 g, 32 mmol, 3.0 equiv.), sodium carbonate (0.561 g, 5.3 mmol, 0.50 equiv.), and DMF (dimethylformamide) (25 mL) and heated in an oil bath at 120 °C for 7 hours. After cooling, the contents of the flask were transferred to a separatory funnel and washed with 1 M dilute sulfuric acid and ethyl acetate. The collected ethyl acetate layer was washed with 1 M dilute sulfuric acid, saturated aqueous sodium bicarbonate, 5% aqueous lithium chloride, and saturated brine (approximately 100 mL each) and dried over sodium sulfate. After removing sodium sulfate and concentrating the mixture, 5.35 g of the target white solid, 2-[2,4,6-tri(1-naphthyl)phenoxy]ethanol (Compound L-3), was obtained in a yield of 98%.

[0102] 2-[2,4,6-tri(1-naphthyl)phenoxy]ethanol (3.00 g, 5.8 mmol) was weighed into a 100 mL three-neck flask equipped with a calcium chloride tube, thermometer, and stir bar, and dissolved in 30 mL of dichloromethane. Triethylamine (1.2 mL, 8.7 mmol, 1.5 equiv.) was added and the mixture was cooled to 1.1 °C on ice. Acryloyl chloride (0.56 mL, 7.0 mmol, 1.2 equiv.) was then slowly added dropwise over 6 minutes. After the reaction mixture cooled to 0.7 °C, the ice cooling was discontinued and the mixture was stirred for 1 hour while slowly warming to room temperature. The reaction was quenched by adding water (approximately 20 mL). The contents of the flask were transferred to a separatory funnel and washed with dichloromethane and water. The recovered dichloromethane layer was washed with 1 M dilute hydrochloric acid, saturated aqueous sodium bicarbonate, and saturated brine (approximately 50 mL each) and dried over sodium sulfate. The sodium sulfate was removed, and the crude product obtained after concentration was purified by silica gel flash column chromatography using hexane and ethyl acetate to obtain the desired white solid, 2-[2,4,6-tri(1-naphthyl)phenoxy]ethyl acrylate (Compound 3), in 2.45 g, 4.3 mmol, 74% yield.

[0103] The NMR measurement data of Compound 3 was as follows: 1H-NMR chart (400MHz, CDCl3, 22℃) 8.21(d,J=5.0Hz,2H),8.04-8.00(m,2H),7.91-7.84(m,6H)7.70-7.61(m,4H), 7.56-7.49(m,10H),5.91-5.84(m,1H),5.58-5.44(m,2H),3.44-73.32(m,4H).

[0104] Synthesis Example 4 (Synthesis of Compound 4) [ka] A 1 L four-neck flask equipped with a reflux condenser, thermometer, and stirrer was charged with 2,4-dibromophenol (4.99 g, 20 mmol), phenanthrene-9-boronic acid (9.66 g, 44 mmol, 2.2 equiv.), potassium phosphate (12.7 g, 60 mmol, 3.0 equiv.), toluene (20 mL), ethanol (20 mL), and water (10 mL). Nitrogen was bubbled through the flask for 30 minutes. Bis[di-tert-butyl(4-dimethylaminophenyl)phosphine]dichloropalladium(II) (1.26 mg, 0.18 μmol, 0.01 mol%) was then added and the mixture was heated to reflux in a 100°C oil bath for 3 hours. After cooling, the contents of the flask were transferred to a separatory funnel and separated with toluene and water. The collected toluene layer was washed with 1 M dilute hydrochloric acid, saturated sodium bicarbonate solution, and saturated brine (approximately 50 mL each) and dried over sodium sulfate. After removing the sodium sulfate, the mixture was concentrated to obtain 9.29 g of the target white amorphous crude product of 2,4-di(phenanthrene-9-yl)phenol (compound C-4).

[0105] The NMR measurement data of compound C-4 was as follows: 1 H-NMR chart (400MHz, CDCl3, 22℃) 8.83-8.68(m,4H),8.14(dd,J=8.3,1.2Hz,1H),7.96-7.87(m,4H),7.79-7.55(m,12H),5.01(s,1H).

[0106] 2,4-Di(phenanthren-9-yl)phenol (6.03 g, 14 mmol) and DMAP (4-dimethylaminopyridine, 43.0 mg, 0.35 mmol) were weighed and dissolved in 60 mL of dichloromethane in a 100 mL three-neck flask equipped with a calcium chloride tube, thermometer, and stirrer. Diisopropylethylamine (3.4 mL, 20 mmol, 1.45 equiv.) was then added and the mixture was cooled on ice. Acryloyl chloride (1.38 mL, 17 mmol, 1.25 equiv.) was then slowly added dropwise over 15 minutes to maintain the internal temperature of the reaction mixture below 8°C. The mixture was stirred at 0°C for 15 minutes. The reaction was quenched by adding 60 mL of aqueous sodium bicarbonate to the reaction mixture. The reaction mixture was concentrated, and the resulting crude product was purified by silica gel flash column chromatography using hexane and ethyl acetate. 3.55 g (0.7 mmol) of the target white solid, 2,4-di(phenanthrene-9-yl)phenyl acrylate (Compound 4), was obtained.

[0107] The NMR measurement data of Compound 4 was as follows: 1 H-NMR chart (400MHz, CDCl3, 22℃) 8.81-8.69(m,4H),8.12(dd,J=8.3,1.2Hz,1H),7.93-7.85(m,3H),7.81-7.76(m,2H),7.74-7.56(m,10H),7.5 0(d,J=8.8Hz,1H),6.01(dd,J=17.4,1.3Hz,1H),5.82(dd,J=17.4,10.3Hz,1H),5.58(dd,J=10.3,1.3Hz,1H).

[0108] Comparative Synthesis Example 1 (Synthesis of Compound 5) Compound 5 was synthesized with reference to Molecular Crystals and Liquid Crystals (2011), 542, 132-140, as described in the present specification.

[0109] [Example 1] Compound 1, HEMA, and Compound P were mixed in a molar ratio of 48 / 26 / 26 and polymerized. The polymerization conditions were as follows: Compound 1 (409 mg), HEMA (40 mg), Compound P (76 mg), cyclohexanone (526 mg), and 2,2-azobis(2-methylpropionate)dimethyl (10 mg) were charged into a flask, and the mixture was stirred under nitrogen at 75°C for 11 hours. The mass ratio of Compound 1 to the total amount of Compound 1, HEMA, and Compound P was 77% by mass. The resulting polymerization solution was diluted with cyclohexanone to a solids concentration of 15% by mass to obtain a thermosetting resin composition. The thermosetting resin composition was applied to a glass substrate by spin coating and cured at 90°C for 90 seconds and then at 150°C for 30 minutes. The results of evaluation of the resulting cured product using the above evaluation methods are shown in Table 1.

[0110] [Examples 2 and 3] Compound 1, HEMA, and Compound P were mixed in a molar ratio of 43 / 33 / 24 and polymerized. The polymerization conditions were as follows: Compound 1 (395 mg), HEMA (55 mg), Compound P (78 mg), PGMEA (propylene glycol monomethyl ether acetate) (1584 mg), and 2,2-azobis(2-methylpropionate)dimethyl (26 mg) were charged into a flask, and the mixture was stirred under nitrogen at 75°C for 11 hours. The mass ratio of Compound 1 to the total amount of Compound 1, HEMA, and Compound P was 75% by mass. After the polymerization, the flask contained a heterogeneous mixture of white solid and solvent. The solvent was decanted, and the solid was then washed twice with PGMEA. The white solid was then dissolved in cyclohexanone and diluted to a solids concentration of 15% by mass, yielding a thermosetting resin composition. The thermosetting resin composition was applied to a glass substrate using spin coating and cured at 90°C for 90 seconds and 230°C for 5 minutes. The results of evaluation of the obtained cured product using the above evaluation methods are shown in Table 1. The internal transmittance spectrum from 300 nm to 400 nm of the cured product obtained in Example 2 is also shown in Figure 1. In Example 3, surfactant U-218 (a fluorine-containing surfactant manufactured by Unichem Co., Ltd.) was contained in an amount of 0.16 mass % relative to the total amount of Compound 1, HEMA, and Compound P.

[0111] [Example 4] Polymerization was carried out in the same manner as in Example 1, except that the raw material composition was changed as shown in Table 1, PGME (propylene glycol monomethyl ether) (1691 mg) was used instead of cyclohexanone, and the curing conditions when applied to the glass substrate were 90°C for 90 seconds and 230°C for 5 minutes. The results of evaluation of the obtained cured product using the above evaluation methods are shown in Table 1. The internal transmittance spectrum from 300 nm to 400 nm of the cured product obtained in Example 4 is shown in Figure 1.

[0112] [Example 5] Polymerization was carried out in the same manner as in Example 1, except that the raw material composition was changed as shown in Table 1. The obtained cured product was evaluated using the evaluation methods described above, and the results are shown in Table 1. The internal transmittance spectrum of the obtained cured product from 300 nm to 400 nm is shown in Figure 1.

[0113] [Example 6] Polymerization was carried out in the same manner as in Example 2, except that the raw material composition was changed as shown in Table 1 and the curing conditions when applied to the glass substrate were 90°C for 90 seconds and 150°C for 30 minutes. The obtained cured product was evaluated using the above-mentioned evaluation methods, and the results are shown in Table 1. The internal transmittance spectrum of the obtained cured film from 300 nm to 400 nm is also shown in Figure 1.

[0114] [Comparative Example 1] Polymerization was carried out in the same manner as in Example 1, except that the raw material composition was changed as shown in Table 1. The obtained cured product was evaluated using the evaluation methods described above, and the results are shown in Table 1. The internal transmittance spectrum of the obtained cured product from 300 nm to 400 nm is shown in Figure 1.

[0115] [Table 1]

[0116] As can be seen from the results in Table 1, the cured product produced from the thermosetting resin composition of the present invention had an extremely high refractive index and maintained various physical properties at a high level. On the other hand, Comparative Example 1 corresponds to the cured product of the resin composition disclosed in Patent Document 1, and had an inferior refractive index compared to the present invention. 1, in spite of having a high refractive index, Examples 1 to 6 exhibit an internal transmittance of 99% or more at 400 nm, which is a practical wavelength in visible light, which is the same value as Comparative Example 1. Furthermore, in spite of having an absorption edge on the longer wavelength side compared to Comparative Example 1, Examples 1 to 6 also exhibit a decrease in internal transmittance at 400 nm after the heat resistance test which is the same as that of the Comparative Example, demonstrating sufficient heat resistance. [Industrial Applicability]

[0117] It has been confirmed that the thermosetting resin composition of the present invention has a very high refractive index and does not exhibit a decrease in transmittance due to a longer absorption wavelength, while maintaining high heat resistance in the cured product. Therefore, it is easy to predict that extremely high performance will be achieved when used in microlenses, planarization films, etc., and it is clear that this technology is of great industrial value.

Claims

1. A copolymer having a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3). 【Chemistry 1】 (In the formula, R ０ each independently represents a hydrogen atom or a methyl group, R ２ represents a single bond or an alkylene group having 1 to 6 carbon atoms, R ３ represents a blocked isocyanate group, and R ４ represents a single bond or an alkylene group having 1 to 6 carbon atoms, R ５ represents a hydrocarbon group having 1 to 20 carbon atoms and having a hydroxy group as a substituent, or a phenyl group having a hydroxy group as a substituent, and the hydrocarbon group having 1 to 20 carbon atoms may be linear, branched, or cyclic. L represents a divalent linking group having 1 to 6 carbon atoms, which may be branched. m represents an integer of 0 to 4, and n represents an integer of 1 to 3. A １ represents a phenanthrene group or a naphthalene group.

2. 2. The copolymer according to claim 1, wherein m is 0 or 1 and n is 2 or 3.

3. The formula (1) in the copolymer is the following formula (4), and A ２ and each represent a hydrogen atom, a phenanthrene group, or a naphthalene group, and at least two of them are phenanthrene groups or naphthalene groups. 【Chemistry 2】 (In the formula, R ０ represents a hydrogen atom or a methyl group; L represents a divalent linking group having 1 to 6 carbon atoms which may be branched; m represents an integer of 0 to 4; A ２ each represents a hydrogen atom, a phenanthrene group, or a naphthalene group, and at least two of them are phenanthrene groups or naphthalene groups.

4. The above A ２ 4. The copolymer according to claim 3, wherein three of the groups are phenanthrene groups or naphthalene groups.

5. In the structural unit represented by the formula (1), the m is 1, and A １ 2. The copolymer of claim 1, wherein is a phenanthrene group or a naphthalene group, and n is 3.

6. The copolymer according to claim 1, comprising at least 20 mol% of the structural unit represented by formula (1) relative to all structural units of the copolymer.

7. The copolymer of claim 1, wherein the copolymer has a weight average molecular weight of 2,000 to 200,000.

8. A thermosetting resin composition comprising the copolymer according to any one of claims 1 to 7.

9. The thermosetting resin composition of claim 8 further comprising a surfactant.

10. The thermosetting resin composition according to claim 8, which is used for a planarizing film.

11. The thermosetting resin composition according to claim 8, which is for use in a microlens.

12. A cured product obtained by heating the thermosetting resin composition according to claim 8.

13. A planarization film made from the thermosetting resin composition according to claim 10.

14. A microlens made from the thermosetting resin composition of claim 11.

15. A compound represented by the following formula (5): 【Transformation 3】 (In the formula, R ０ represents a hydrogen atom or a methyl group, L represents a divalent linking group having 1 to 6 carbon atoms which may be branched, m represents an integer of 0 to 4, and ２ Two of them are phenanthrene groups, and A is a group other than the phenanthrene group. ２ is a hydrogen atom.)

16. 16. The compound of claim 15, wherein the phenanthrene group has the structure: 【Chemistry 4】

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