JP6946062B2 - Resin, curable composition, cured product, method for producing cured product, and method for producing microlens - Google Patents

Description

The present invention relates to a resin containing a structural unit having a specific structure, a curable composition containing the resin, a cured product obtained by curing the above-mentioned resin, a method for producing a cured product using the above-mentioned resin, and the above-mentioned method. The present invention relates to a method for manufacturing a microlens using the above resin.

Traditionally, curable resin materials have been used in a variety of applications. By selecting the partial structure of the curable resin and the type of additive used together with the curable resin, a cured product exhibiting various properties is formed using the curable resin.
For example, a cured product used for forming a flattening film or a microlens in an image display element or an optical element may be desired to have good transparency, solvent resistance, and a high refractive index. ..

As a curable resin used for forming a flattening film or a microlens, for example, a copolymer containing a structural unit containing an epoxy group and a structural unit containing a biphenylyl group is known (Patent Document 1). reference.).

International Publication No. 2015/122109

However, when a cured film is formed using a resin having an epoxy group as described in Patent Document 1, it may be difficult to form a sufficiently cured cured film depending on the type of substrate, or the cured film may be formed in a high temperature environment. When used, the size of the film thickness may fluctuate, or the light transmittance of the transmitting film may decrease.

The present invention has been made in view of the above problems, and when it is cured on a substrate, it is cured satisfactorily regardless of the type of the substrate, and when it is used in a high temperature environment, dimensional changes occur or light rays occur. A heat-curable resin capable of forming a cured product whose permeability does not easily decrease, a curable composition containing the resin, a cured product obtained by curing the above-mentioned resin, and a cured product using the above-mentioned resin. It is an object of the present invention to provide a method for producing a microlens using the above-mentioned resin and a method for producing a microlens using the above-mentioned resin.

The present inventors have a specific structural unit having a blocked isocyanate group, a specific structural unit having a hydroxyl group, and a specific structural unit having a hydrocarbon group containing two or more benzene rings. It has been found that the above-mentioned problems can be solved by using a resin containing a combination of the above-mentioned substances, and the present invention has been completed.

（式（ａ１）、（ａ２）、及び（ａ３）中、Ｒ^１は、それぞれ独立に水素原子、又はメチル基であり、Ｒ^２は、単結合、又は炭素原子数１以上５以下のアルキレン基であり、Ｒ^３は、ブロックイソシアネート基であり、Ｒ^４は、２価の炭化水素基であり、Ｒ^５は、単結合、又は２価の連結基であり、Ｒ^６は、２以上のベンゼン環を含む有機基である。） The first aspect of the present invention is a resin 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). be.

(In the formulas (a1), (a2), and (a3), R ¹ is an independently hydrogen atom or a methyl group, and R ² is a single bond or an alkylene group having 1 or more and 5 or less carbon atoms. R ³ is a blocked isocyanate group, R ⁴ is a divalent hydrocarbon group, R ⁵ is a single bond or a divalent linking group, and R ⁶ is two or more benzenes. It is an organic group containing a ring.)

A second aspect of the present invention is a curable composition containing the resin according to the first aspect and a solvent.

A third aspect of the present invention is a cured product obtained by curing the resin according to the first aspect.

A fourth aspect of the present invention is
A molding step of molding the resin according to the first aspect into a predetermined shape, and
A curing process in which the molded resin is cured by heating,
It is a method for producing a cured product containing.

A fifth aspect of the present invention is
A lens material layer forming step of forming a lens material layer by cross-linking a resin layer obtained by applying the composition containing the resin according to the first aspect on a substrate by heating.
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.
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.
It is a manufacturing method of a microlens including.

According to the present invention, a curable resin having good curability and capable of forming a cured product having a high refractive index, a curable composition containing the resin, and a cured product obtained by curing the above-mentioned resin. , A method for producing a cured product using the above-mentioned resin and a method for producing a microlens using the above-mentioned resin can be provided.

（式（ａ１）、（ａ２）、及び（ａ３）中、Ｒ^１は、それぞれ独立に水素原子、又はメチル基であり、Ｒ^２は、単結合、又は炭素原子数１以上５以下のアルキレン基であり、Ｒ^３は、ブロックイソシアネート基であり、Ｒ^４は、２価の炭化水素基であり、Ｒ^５は、単結合、又は２価の連結基であり、Ｒ^６は、２以上のベンゼン環を含む炭化水素基である。） ≪Resin≫
The resin includes 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).

(In the formulas (a1), (a2), and (a3), R ¹ is an independently hydrogen atom or a methyl group, and R ² is a single bond or an alkylene group having 1 or more and 5 or less carbon atoms. R ³ is a blocked isocyanate group, R ⁴ is a divalent hydrocarbon group, R ⁵ is a single bond or a divalent linking group, and R ⁶ is two or more benzenes. It is a hydrocarbon group containing a ring.)

Hereinafter, the structural unit represented by the formula (a1) is also referred to as "structural unit A1", and the structural unit represented by the formula (a2) is also referred to as "structural unit A2", and the structural unit represented by the formula (a3). Is also referred to as "structural unit A3".

Structural units A1 represented by the above formula (a1) has a blocked isocyanate group as ^{R 3.} The blocked isocyanate group means a group in which the isocyanate group is blocked by a thermally dissociable protecting group.
Therefore, when the above resin having the structural unit A1 is heated, the protecting groups in the blocked isocyanate groups are desorbed and active isocyanate groups are generated.

The isocyanate group produced by heating easily reacts with a functional group having active hydrogen. Here, the structural unit A2 represented by the above formula (a2) has a hydroxyl group which is a functional group having an active hydrogen group. Therefore, when the above resin is heated, an active isocyanate group is generated in the structural unit A1. When this isocyanate group (-NCO) reacts with the hydroxyl group in the structural unit A2, cross-linking by a urethane bond (-NH-CO-O-) proceeds, and a cured product is formed.

Furthermore, the structural unit represented by the above formula (a3) is, as R ^6, having a hydrocarbon group containing 2 or more benzene rings. Here, the hydrocarbon group containing two or more benzene rings contributes to increasing the refractive index of the cured product.
Therefore, when the above resin is heated, the curing of the resin proceeds satisfactorily, and as a result, a cured product having a high refractive index is formed.

Hereinafter, essential or arbitrary structural units contained in the resin, a method for producing the resin, and the like will be described.

<Structural unit A1>
As described above, the resin contains a structural unit A1 having a blocked isocyanate group. The resin may contain a combination of two or more types of structural units A1.

The structural unit A1 is a structural unit represented by the above formula (a1). In formula (a1), R ¹ is a hydrogen atom or a methyl group.

In the formula (a1), R ² is a single bond or an alkylene group having 1 or more and 5 or less carbon atoms. The alkylene group may be linear or branched, and is preferably linear. Specific examples of the alkylene group as R ² include a methylene group, an ethane-1,2-diyl group, an ethane-1,1-diyl group, a propane-1,3-diyl group, and a propane-1,2-diyl group. , Butane-1,4-diyl group, pentane-1,5-diyl group and the like.
Among these groups, a methylene group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group are preferable, and methylene is used. Groups, ethane-1,2-diyl groups, and propane-1,3-diyl groups are more preferred, with ethane-1,2-diyl groups being particularly preferred.

Wherein (a1), ^{R 3} is a block isocyanate group. As described above, the blocked isocyanate group means a group in which the isocyanate group is blocked by a thermally dissociable protecting group.
Such a 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-based compounds, phenol-based compounds, hydroxyl-containing compounds other than alcohol-based compounds and phenol-based compounds, active methylene-based compounds, amine-based compounds, imine-based compounds, oxime-based compounds, and carbamate-based compounds. , Urea-based compounds, acid-amide-based (lactam-based) compounds, acid-imide-based compounds, triazole-based compounds, pyrazole-based compounds, pyrrol-based compounds, mercaptan-based compounds, and heavy sulfites.

Examples of alcohol-based compounds include methanol, ethanol, isopropanol, n-butanol, sec-butanol, 2-ethylhexyl alcohol, 1-octanol, 2-octanol, cyclohexyl alcohol, ethylene glycol, benzyl alcohol, 2,2,2-. Trifluoroethanol, 2,2,2-trichloroethanol, 2- (hydroxymethyl) furan, 2-methoxyethanol, methoxypropanol, 2-2-ethoxyethanol, n-propoxyethanol, 2-butoxyethanol, 2- (2) -Ethoxyethoxy) ethanol, 2- (4-ethoxybutoxy) ethanol, 2- (2-butoxyethoxy) ethanol, N, N-dibutyl-2-hydroxyacetamide, N-morpholine ethanol, 2,2-dimethyl-1, Examples thereof include 3-dioxolan-4-methanol, 3-oxazolidine ethanol, 2-hydroxymethylpyridine, furfuryl alcohol, 12-hydroxystearic acid, 2-hydroxyethyl methacrylate and the like.

Examples of phenolic compounds include phenol, o-cresol, m-cresol, p-cresol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2-n-propylphenol, and 3-n-propylphenol. , 4-n-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-n-butylphenol, 3-n-butylphenol, 4-n-butylphenol, 2-sec-butylphenol, 3-sec -Butylphenol, 4-sec-butylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-n-hexylphenol, 3-n-hexylphenol, 4-n-hexylphenol, 2- (2-Ethylhexyl) phenol, 3- (2-ethylhexyl) phenol, 4- (2-ethylhexyl) phenol, 2-n-octylphenol, 3-n-octylphenol, 4-n-octylphenol, 2-n-nonylphenol, 3 -N-nonylphenol, 4-n-nonylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5- Dimethylphenol, 2,3-din-propylphenol, 2,4-din-propylphenol, 2,5-din-propylphenol, 2,6-din-propylphenol, 3,4-din- Propylphenol, 3,5-din-propylphenol, 2,3-diisopropylphenol, 2,4-diisopropylphenol, 2,5-diisopropylphenol, 2,6-diisopropylphenol, 3,4-diisopropylphenol, 3, 5-Diisopropylphenol, 3-isopropyl-2-methylphenol, 4-isopropyl-2-methylphenol, 5-isopropyl-2-methylphenol, 6-isopropyl-2-methylphenol, 2-isopropyl-3-methylphenol, 4-isopropyl-3-methylphenol, 5-isopropyl-3-methylphenol, 6-isopropyl-3-methylphenol, 2-isopropyl-4-methylphenol, 3-isopropyl-4-methylphenol, 5-isopropyl-4 -Methylphenol, 6-isopropyl-4-methylphenol Enol, 2,3-din-butylphenol, 2,4-din-butylphenol, 2,5-din-butylphenol, 2,6-din-butylphenol, 3,4-din-butylphenol, 3,5 − Di n-butylphenol, 2,3-disec-butylphenol, 2,4-disec-butylphenol, 2,5-disec-butylphenol, 2,6-disec-butylphenol, 3,4-disec-butylphenol , 3,5-disec-butylphenol, 2,3-ditert-butylphenol, 2,4-ditert-butylphenol, 2,5-ditert-butylphenol, 2,6-ditert-butylphenol, 3,4-di tert-butylphenol, 3,5-di tert-butylphenol, 2,3-din-octylphenol, 2,4-din-octylphenol, 2,5-din-octylphenol, 2,6-din-octylphenol, 3 , 4-Din-octylphenol, 3,5-din-octylphenol, 2,3-di2-ethylhexylphenol, 2,4-di2-ethylhexylphenol, 2,5-di2-ethylhexylphenol, 2,6 -Di2-ethylhexylphenol, 3,4-di2-ethylhexylphenol, 3,5-di2-ethylhexylphenol, 2,3-din-nonylphenol, 2,4-din-nonylphenol, 2,5-di n-nonylphenol, 2,6-din-nonylphenol, 3,4-din-nonylphenol, 3,5-din-nonylphenol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2-bromophenol , 3-Bromophenol, 4-Bromophenol 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-fluorophenol, 3-fluorophenol, 4-fluorophenol, styrenated phenol (by α-methylbenzyl group) Phenol mono, di, or tri-substituted), methyl salicylate, methyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 2-ethylhexyl 4-hydroxybenzoate, 4-[(dimethylamino) methyl] phenol, 4 -[(Dimethylamino) methyl] nonylphenol, bis (4-hydroxyphenyl) acetic acid, 2-hydroxypyridine, 2-hydroxyquinoline, 8-hydroxyquinoline, 2-chloro-3-pyridinol and the like. Be done.

Examples of the hydroxyl group-containing compound other than the alcohol-based compound and the phenol-based compound include N-hydroxysuccinimide and triphenylsilanol.

Examples of the active methylene compound include malonic acid and dialkyl malonic acid (for example, dimethyl malonic acid, diethyl malonate, din-butyl malonic acid, ditert-butyl malonic acid, di2-ethylhexyl malonic acid, and methyl malonate. n-butyl, ethyl malonate n-butyl, methyl sec-butyl malonate, ethyl sec-butyl malonate, methyl tert-butyl malate, ethyl tert-butyl malate, diethyl methyl malonate, dibenzyl malonate, malonic acid Diphenyl, benzylmethyl malonate, ethylphenyl malonate, tert-butylphenyl malonic acid, isopropyridene malonate, etc.), alkyl acetoacetate (eg, methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate) , N-butyl acetoacetate, tert-butyl acetoacetate, benzyl acetoacetate, phenyl acetoacetate, etc.), 2-acetoxyethyl methacrylate, acetylacetone, ethyl cyanoacetate and the like.

Examples of amine-based compounds include dibutylamine, diphenylamine, aniline, N-methylaniline, carbazole, bis (2,2,6,6-tetramethylpiperidinyl) amine, din-propylamine, diisopropylamine, and isopropyl. Ethylamine, 2,2,4-trimethylhexamethyleneamine, 2,2,5-trimethylhexamethyleneamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis (3,5,5-trimethylcyclohexyl) amine, piperidine, 2, 6-Dimethylpiperidin, tert-butylmethylamine, tert-butylethylamine, tert-butyl n-propylamine, tert-butyl n-butylamine, tert-butylbenzylamine, tert-butylphenylamine, 2,2,6-trimethyl Piperidine, 2,2,6,6-tetramethylpiperidin, (dimethylamino) -2,2,6,6-tetramethylpiperidin, 2,2,6,6-tetramethyl-4-piperidin, 6-methyl- 2-piperidin, 6-aminocaproic acid and the like can be mentioned.

Examples of imine compounds include ethyleneimine, polyethyleneimine, 1,4,5,6-tetrahydropyrimidine, guanidine and the like.

Examples of oxime compounds include formaldehyde, acetoaldoxime, acetooxime, methylethylketooxime, cyclohexanone oxime, diacetylmonooxime, benzophenone oxime, 2,2,6,6-tetramethylcyclohexanone oxime, diisopropylketone oxime, and methyl. tert-butylketone oxime, diisobutylketone oxime, methylisobutylketone oxime, methylisopropylketone oxime, methyl2,4-dimethylpentylketone oxime, methyl3-ethylheptylketone oxime, methylisoamylketone oxime, n-amylketone oxime, Examples thereof include 2,2,4,4-tetramethyl-1,3-cyclobutanedione monooxime, 4,4'-dimethoxybenzophenone oxime, and 2-heptanone oxime.

Examples of the carbamic acid-based compound include phenyl N-phenylcarbamate and the like.

Examples of the urea compound include urea, thiourea, ethylene urea and the like.

Examples of acid amide-based (lactam-based) compounds include acetamide, N-methylacetamide, acetate amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, pyrrolidone, 2,5-piperazindione, and laurolactam. Can be mentioned.

Examples of the acidimide-based compound include succinimide, maleateimide, and phthalimide.

Examples of the triazole-based compound include 1,2,4-triazole, benzotriazole and the like.

Examples of the pyrazole-based compound include pyrazole, 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, 3,5-diphenylpyrazole, 3,5-ditert-butylpyrazole, 3-methylpyrazole, and 4-benzyl-. Examples thereof include 3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole.

Examples of the pyrrole compound include pyrrole, 2-methylpyrrole, 3-methylpyrrole, 2,4-dimethylpyrrole and the like.

Examples of the mercaptan-based compound include n-butyl mercaptan, n-dodecyl mercaptan, n-hexyl mercaptan, thiophenol, and pyridine-2-thiol.

Examples of the sodium bisulfite include sodium bisulfite and the like.

（式（ａ１−１）、式（ａ１−２）及び式（ａ１−３）中、Ｒ^１、及びＲ^２は、前記式（ａ１）と同様であり、Ｒ^７は、それぞれ独立に炭素原子数１以上１２以下の有機基であり、Ｒ^８は、それぞれ独立にハロゲン原子又は炭素原子数１以上６以下の有機基であり、Ｒ^９は、それぞれ独立に炭素原子数１以上６以下の有機基であり、ａは、０以上３以下の整数である。） Among the structural units A1 represented by the formula (a1) described above, the following formulas (a1-1) and (a1-) are available because the resin can be easily prepared and the curability is good. 2) or the structural unit represented by the formula (a1-3) is preferable.

(In the formula (a1-1), the formula (a1-2) and the formula (a1-3), R ¹ and R ² are the same as those in the formula (a 1), and R ⁷ is an independent carbon atom. ^{R 8} is an organic group having a number of 1 or more and 12 or less, R 8 is an organic group having a halogen atom or a carbon atom number of 1 or more and 6 or less, and R ⁹ is an organic group having a carbon atom number of 1 or more and 6 or less. It is a group, and a is an integer of 0 or more and 3 or less.)

In the formula (a1-1), ^{the organic group as R 7} includes an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and an alkoxyalkyl group having 2 to 12 carbon atoms. Examples thereof include a group, a phenyl group, a phenylalkyl group having 7 or more and 12 or less carbon atoms, and an acyl group having 2 or more and 12 or less carbon atoms. Among these groups, an alkyl group is preferable, an alkyl group having 1 or more and 6 or less carbon atoms is more preferable, an alkyl group having 1 or more and 3 or less carbon atoms is further preferable, and a methyl group or an ethyl group is particularly preferable.
The alkyl group may be linear or branched.
In the formula (a1-1), the two ^Ra7s may be the same or different.

In the formula (a1-2), R ^a8 is a substituent on the pyrazolyl group, which is independently a halogen atom or an organic group having 1 or more and 6 or less carbon atoms.
Preferable examples of R ^a8 are halogen atoms, alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, and 2 carbon atoms. Examples thereof include aliphatic acyl groups having a value of 6 or less.
As R ^a8 , a halogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are preferable, and an alkyl group having 1 to 6 carbon atoms is more preferable, and the number of carbon atoms is more preferable. Alkyl groups of 1 or more and 3 or less are more preferable, and methyl groups are particularly preferable.
In the formula (a1-2), a is an integer of 0 or more and 3 or less, and an integer of 0 or more and 2 or less is preferable.

In the formula (a1-3), ^{the organic group as R a9} is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and an alkoxyalkyl group having 2 to 12 carbon atoms. Examples thereof include a group, a phenyl group, and a phenylalkyl group having 7 or more and 12 or less carbon atoms.
In the formula (a1-3), the two ^Ra9s may be the same or different.

The structural unit A1 is incorporated into the resin by copolymerizing the (meth) acrylic acid ester represented by the following formula (a-I) with a monomer giving another structural unit.
Among the (meth) acrylic acid esters represented by the formula (a-I), the following formula (a-I-1), formula (a-I-2), or formula (a-I-3) is used. The (meth) acrylic acid ester to be used is preferable, and the (meth) acrylic acid ester represented by the following formula (a-I-1a), formula (a-I-2a), or formula (a-I-3a) is used. More preferred.
The structural unit A1 may be present in the resin in a block shape or may be randomly present in the resin. The structural unit A1 is preferably randomly present in the resin from the viewpoint that the isocyanate group generated in the structural unit A1 by heating and the hydroxyl group easily react with each other.

Preferable specific examples of the (meth) acrylic acid ester giving the structural unit A1 include the following compounds.

Among these, the following (meth) acrylic acid ester is preferable because it is easy to produce a resin and it is easy to obtain a resin having good curability.

The amount of the structural unit A1 in the resin is not particularly limited as long as the object of the present invention is not impaired. The content of the structural unit A1 in the resin is preferably 15 mol% or more, more preferably 15 mol% or more and 45 mol% or less, based on the total structural units of the resin, from the viewpoint of curability. From the viewpoint of achieving both good curability and high refractive index of the cured product, the content of the structural unit A1 in the resin is preferably 20 mol% or more and 40 mol% or less with respect to the total structural units of the resin. , 25 mol% or more and 35 mol% or less are more preferable.

<Structural unit A2>
The structural unit A2 is a structural unit represented by the above formula (a2). In formula (a2), R ¹ is a hydrogen atom or a methyl group.

Wherein (a2), ^{R 4} is a divalent hydrocarbon group. The hydrocarbon group as R ⁴ may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a hydrocarbon group having an aliphatic portion and an aromatic portion. From the viewpoint of curability of resin, preferably R ⁴ is a divalent aliphatic hydrocarbon group. When R ⁴ is a divalent aliphatic hydrocarbon group, the structure of the aliphatic hydrocarbon group may be linear, branched chain, or cyclic, and these are combined. It may have a structure, and a linear structure is preferable.

The number of carbon atoms of the hydrocarbon group as ^{R 4 is not particularly limited.} When the hydrocarbon group is an aliphatic hydrocarbon group, the number of carbon atoms is preferably 1 or more and 20 or less, more preferably 2 or more and 10 or less, and particularly preferably 2 or more and 6 or less. When the hydrocarbon group is an aromatic group or a hydrocarbon group having an aliphatic portion and an aromatic portion, the number of carbon atoms is preferably 6 or more and 20 or less, and more preferably 6 or more and 12 or less.

Specific examples of the divalent aliphatic hydrocarbon group include a methylene group, an ethane-1,2-diyl group, an ethane-1.1-diyl group, a propane-1,3-diyl group, and a propane-1,2-diyl group. Diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonan- 1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group Group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, octadecane-1,18-diyl group, nonadecan-1,19-diyl group, and icosan- Examples include 1,20-diyl groups.
Among these, methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6- Diyl group, heptan-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane- 1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group Groups, octadecane-1,18-diyl groups, nonadecan-1,19-diyl groups, and icosan-1,20-diyl groups are preferred, methylene groups, ethane-1,2-diyl groups, propane-1,3-. Diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptan-1,7-diyl group, octane-1,8-diyl group, nonane- The 1,9-diyl group and the decane-1,10-diyl group are more preferable, and the ethane-1,2-diyl group, the propane-1,3-diyl group, the butane-1,4-diyl group, and the pentane-1 are preferable. , 5-Diyl group, and hexane-1,6-Diyl group are more preferred.

Specific examples of the divalent aromatic hydrocarbon group include p-phenylene group, m-phenylene group, o-phenylene group, naphthalene-1,4-diyl group, naphthalene-2,6-diyl group, and naphthalene-. Examples thereof include 2,7-diyl group, p-phenylene group and m-phenylene group are preferable, and p-phenylene group is more preferable.

（式（ａ−ＩＩ）中、Ｒ^１及びＲ^４は、式（ａ２）と同様である。） The structural unit A2 is incorporated into the resin by copolymerizing the (meth) acrylic acid ester represented by the following formula (a-II) with a monomer giving another structural unit.
The structural unit A2 may be present in the resin in a block shape or may be randomly present in the resin. The structural unit A2 is preferably randomly present in the resin from the viewpoint that the isocyanate group generated in the structural unit A1 by heating and the hydroxyl group easily react with each other.

(In the formula (a-II), R ¹ and R ⁴ are the same as those in the formula (a 2).)

Suitable specific examples of the (meth) acrylic acid ester giving the structural unit A2 include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4 -Hydroxybutyl methacrylate, 4-hydroxyphenyl acrylate, 4-hydroxyphenyl methacrylate, 3-hydroxyphenyl acrylate, 3-hydroxyphenyl methacrylate and the like can be mentioned.
Among these, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate are preferable.

The amount of the structural unit A2 in the resin is not particularly limited as long as it does not impair the object of the present invention.
The amount of the structural unit A2 in the resin is preferably 15 mol% or more, more preferably 15 mol% or more and 45 mol% or less, based on the total structural units of the resin. From the viewpoint of achieving both good curability and high refractive index of the cured product, the content of the structural unit A1 in the resin is preferably 20 mol% or more and 40 mol% or less with respect to the total structural units of the resin. , 25 mol% or more and 35 mol% or less are more preferable.
Further, in the resin, the number of moles of the structural unit A1 and the number of moles of the structural unit A2 are preferably 80/100 or more and 100/80 or less as the number of moles of the structural unit A1 / the number of moles of the structural unit A2, and 90 / 100 or more and 100/90 or less are more preferable, and 95/100 or more and 100/95 or less are particularly preferable. In the resin, the number of moles of the structural unit A1 and the number of moles of the structural unit A2 are most preferably equimolar.

<Structural unit A3>
The structural unit A3 is a structural unit represented by the above formula (a3). In formula (a3), R ¹ is a hydrogen atom or a methyl group.

In formula (a3), R ⁶ is an organic group containing two or more benzene rings. By including the structural unit A3 having an organic group containing two or more benzene rings as R ⁶ , a cured product having a high refractive index can be formed.
The ^{two or more benzene rings contained in R 6} may be condensed with each other, or may be bonded by a single bond or a linking group.
The ^{number of carbon atoms of R 6} is not particularly limited as long as the object of the present invention is not impaired. The number of carbon atoms of R6 is preferably 10 or more and 50 or less, and more preferably 10 or more and 30 or less.

As the organic group containing two or more benzene rings as R ⁶ , the following polycyclic compound or a group in which a substituent is introduced into the following polycyclic compound, excluding one hydrogen atom is used. Can be mentioned. In the following formula, X is -O-, -S-, -CO-, -SO _2- , -CO-NH-, -CO-NH-CO-, -NH-CO-NH-, -CO-O-. , -CO-O-CO- _{, -O-CO-O-, -SO 2} , -NH-, -S-S-, -CH _2- , -CH (CH ₃ )-, or -C (CH ₃₎ ) _2- .

Examples of the substituent that can be introduced into the above polycyclic compound include a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an alkoxy having 1 to 6 carbon atoms. Examples thereof include a group, an aliphatic acyl group having 2 or more and 6 or less carbon atoms, a nitro group, and a cyano group.
When a substituent is introduced into the above polycyclic compound, the number of substituents is not particularly limited, but 4 or less is preferable, and 1 or 2 is preferable.

The R ⁶ described above, preferably a group represented by the following formula.
In the following formula, R ¹⁰ , R ¹¹ , and R ¹³ are independently halogen atoms, alkyl groups having 1 or more and 6 or less carbon atoms, cycloalkyl groups having 3 or more and 6 or less carbon atoms, and 1 or more carbon atoms. A group selected from the group consisting of an alkoxy group of 6 or less, an aliphatic acyl group having 2 or more and 6 or less carbon atoms, a nitro group, and a cyano group, and R ¹² is a hydrogen atom or a carbon atom number of 1 or more and 6 or less. B and c are independently integers of 0 or more and 4 or less, and d is an integer of 0 or more and 7 or less.

Among these groups, the group represented by the following formula is preferable because the effect of increasing the refractive index is good and the introduction into the resin is easy. In the following formula, two bs are used. A biphenylyl group, both of which are 0, is more preferred.

The group R ⁶ described above is bound to the main chain of the resin via R ^5. R ⁵ is a single bond or divalent linking group.
The divalent linking group is not particularly limited as long as it does not interfere with the object of the present invention. Preferable examples of the divalent linking group are an alkylene group having 1 or more and 6 or less carbon atoms, -O-, -S-, -CO-, -SO _2- , -CO-NH-, -CO-NH. Consists of -CO-, -NH-CO-NH-, -CO-O-, -CO-O- _{CO-, -O-CO-O-, -SO 2} , -NH-, and -S-S- Examples thereof include a divalent group selected from the group and a group combining two or more divalent groups selected from the above-mentioned group.
Among R ⁶ , single bonds, alkylene groups having 1 to 6 carbon atoms, and -CO-O- are preferable, single bonds and -CO-O- are more preferable, and -CO-O- * (* is , Represents the end of the bond that binds to ^{R 6} in formula (a3)) is particularly preferred. When R ⁶ is an alkylene group, the alkylene group may be linear or branched.

From the above, as the structural unit A3, the structural unit represented by the following formula (a3-1) is preferable. In formula (a3-1), R ¹ , R ¹⁰ , and b are as described above, respectively.

The structural unit A3 is incorporated into the resin by copolymerizing an unsaturated compound represented by the following formula (a-III) with a monomer that gives another structural unit.
The structural unit A3 may be present in the resin in a block shape or may be randomly present in the resin. Since the structural unit A1 and the structural unit A2 can be easily distributed uniformly in the resin, the structural unit A3 is preferably randomly present in the resin.

As the unsaturated compound represented by the formula (a-III), the (meth) acrylic acid ester represented by the following formula (a-III-1) is preferable, and it is represented by the following formula (a-III-1a). (Meta) acrylic acid esters are more preferred. In formula (a-III), formula (a-III-1), and formula (a-III-1a), R ¹ , R ⁵ , R ⁶ , R ¹⁰ , and b are as described above, respectively.

Suitable specific examples of the unsaturated compound giving the structural unit A3 include acrylic acid (1,1'-biphenyl-4-yl) ester, methacrylic acid (1,1'-biphenyl-4-yl) ester, and acrylic acid. (1,1'-biphenyl-3-yl) ester, methacrylic acid (1,1'-biphenyl-3-yl) ester, 4-vinyl-1,1'-biphenyl, and 3-vinyl-1,1'. -Biphenyl can be mentioned.
Among these, acrylic acid (1,1'-biphenyl-4-yl) ester and methacrylic acid (1,1'-biphenyl-4-yl) ester are preferable.

The amount of the structural unit A3 in the resin is not particularly limited as long as it does not impair the object of the present invention. The amount of the structural unit A3 in the resin is preferably 30 mol% or more and 50 mol% or less, preferably 35 mol% or less, from the viewpoint that it is easy to achieve both good curability and high refractive index of the cured product. More than 50 mol% is more preferable, and 40 mol% or more and 50 mol% or less is particularly preferable.

<Other structural units>
The resin may contain other structural units in addition to the above-mentioned structural unit A1, structural unit A2, and structural unit A3 as long as the object of the present invention is not impaired.

Other structural units include, for example, structural units derived from (meth) acrylic acid esters. Those containing a structural unit can be used. The (meth) acrylic acid is acrylic acid or methacrylic acid. The (meth) acrylic acid ester is represented by the following formula (a-4-1), and is not particularly limited as long as the object of the present invention is not impaired.

In the above formula (a-IV), ^Ra1 is a hydrogen atom or a methyl group. R ^a11 may react with the isocyanate group formed from the blocked isocyanate groups in the structural unit A1, an organic group having no group containing active hydrogen.
Examples of the group containing active hydrogen include a hydroxyl group, a mercapto group, an amino group, a carboxy group and the like. This organic group may contain a bond or a substituent other than the hydrocarbon group such as a hetero atom in the organic group. Further, the organic group may be linear, branched or cyclic.

The hydrocarbon substituent other than groups in the organic group R ^a11, not particularly limited as long as the effect is not impaired the present invention, a halogen atom, an alkylthio group, an arylthio group, a cyano group, a silyl group, an alkoxy group, an alkoxy Carbonyl group, nitro group, nitroso group, acyl group, acyloxy group, alkoxyalkyl group, alkylthioalkyl group, aryloxyalkyl group, arylthioalkyl group, N, N-di-substituted amino group (-NRR': R and R' Independently indicate a hydrocarbon group) and the like. The hydrogen atom contained in the above substituent may be substituted with a hydrocarbon group. The hydrocarbon group contained in the substituent may be linear, branched or cyclic.

R ^a11 is preferably an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group, and these groups may be substituted with a halogen atom, an alkyl group, or a heterocyclic group. When these groups contain an alkylene moiety, the alkylene moiety may be interrupted by an ether bond, a thioether bond, or an ester bond.

When the alkyl group is linear or branched, the number of carbon atoms thereof is preferably 1 or more and 20 or less, more preferably 1 or more and 15 or less, and particularly preferably 1 or more and 10 or less. Examples of suitable alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec. -Pentyl group, tert-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, isooctyl group, sec-octyl group, tert-octyl group, n-nonyl group, isononyl group, n-decyl group, And an isodecyl group and the like.

When R ^a11 is an alicyclic group or a group containing an alicyclic group, suitable alicyclic groups include a monocyclic alicyclic group such as a cyclopentyl group and a cyclohexyl group, an adamantyl group, and a norbornyl group. Examples thereof include a polycyclic alicyclic group such as a group, an isobornyl group, a tricyclononyl group, a tricyclodecyl group, and a tetracyclododecyl group.

Examples of the monomer other than the above-mentioned (meth) acrylic acid ester that gives other structural units include allyl compounds, vinyl ethers, vinyl esters, styrenes and the like. These monomers can be used alone or in combination of two or more.

Examples of the allyl compound include allyl esters such as allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, and allyl lactate; allyloxyethanol; and the like. Can be mentioned.

Examples of vinyl ethers include hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, and diethylene glycol vinyl ether. Alkyl vinyl ethers such as dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether; vinyl phenyl ether, vinyl trill ether, vinyl chlorophenyl ether, vinyl-2,4-dichlorophenyl ether, vinyl naphthyl ether. , Vinyl aryl ethers such as vinyl anthranil ethers; and the like.

Examples of vinyl esters include vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl ballerate, vinyl caproate, vinyl chloro acetate, vinyl dichloro acetate, vinyl methoxy acetate, vinyl butoxy acetate, and vinyl phenyl. Examples thereof include acetate, vinyl acetoacetate, vinyl lactate, vinyl-β-phenylbutyrate, vinyl benzoate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate and the like.

Examples of styrenes include styrene; methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxy. Alkylstyrene such as methylstyrene and acetoxymethylstyrene; alkoxystyrene such as methoxystyrene, 4-methoxy-3-methylstyrene and dimethoxystyrene; chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, Examples thereof include halostyrene such as dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, and 4-fluoro-3-trifluoromethylstyrene.

When the resin does not contain other structural units in addition to the above-mentioned structural unit A1, structural unit A2, and structural unit A3, the total amount of structural unit A1, structural unit A2, and structural unit A3 in the resin is the total amount in the resin. 80 mol% or more is preferable, 90 mol% or more is more preferable, and 95 mol% or more is particularly preferable with respect to the structural unit.
The resin does not contain other structural units and is composed of only the structural unit A1, the structural unit A2, and the structural unit A3 because the cured product has a high refractive index and is easy to achieve both good curability. preferable.

<Resin manufacturing method>
The method for producing the resin described above is not particularly limited. Generally, a predetermined amount of each of the above-mentioned monomers giving the structural unit A1, the structural unit A2, and the structural unit A3 and the monomer giving the other structural unit, if necessary, are mixed, and then appropriate. A resin can be obtained by carrying out polymerization in a suitable solvent in the presence of a polymerization initiator, for example, in a temperature range of 50 ° C. or higher and 120 ° C. or lower. The resin is often obtained as a solution in an organic solvent, but the resin obtained as a solution can be blended as it is in a curable composition described later, or can be used as it is as a curable composition.

The weight average molecular weight of the resin obtained by the above method is preferably 30,000 or more, more preferably 35,000 or more and 100,000 or less, and particularly preferably 40,000 or more and 80,000 or less. The weight average molecular weight is a polystyrene-equivalent molecular weight measured by GPC. Since the weight average molecular weight of the resin is large to some extent, it is easy to form a cured product having excellent solvent resistance and thermostable decomposition resistance.

The solution of the resin obtained as described above may be mixed with a poor solvent such as hexane, diethyl ether, methanol, or water to precipitate the resin, and the precipitated resin may be recovered and used. The precipitated resin is preferably washed after filtration and then dried under normal pressure or reduced pressure at a temperature at which the blocked isocyanate groups in the structural unit A1 are not decomposed. In this way, the powdery solid resin can be recovered. The powdery resin may be used as it is, or may be blended and used in a curable composition described later.

<< Curable composition >>
The curable composition contains the above-mentioned resin and a solvent. The type of solvent is not particularly limited as long as it does not interfere with the object of the present invention. The curable composition may contain a combination of two or more kinds of solvents.

Even if the solvent remains when the resin is cured, the isocyanate group generated from the blocked isocyanate group in the structural unit A1 does not react with the solvent, so that the solvent produces active hydrogen that can react with the isocyanate group. It is preferable that it does not have a containing group.
Examples of the group containing active hydrogen include a hydroxyl group, a mercapto group, an amino group, a carboxy group and the like.
Since the solvent can be removed at a temperature at which the curing of the resin does not proceed, for example, under reduced pressure, it is not necessarily impossible to use a solvent having a group containing active hydrogen.

Preferable examples of the solvent are 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. Monoalkyl ethers of glycols such as 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, propylene glycol monobutyl ether acetate and the like. Monoalkyl ether acetates of glycols; aromatic solvents such as toluene and xylene; ketones such as acetone, methyl ethyl ketone, 2-heptanone, cyclopentanone, and cyclohexanone; 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, 3-methoxypropionic acid Examples thereof include esters such as methyl, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl lactate, butyl lactate, and γ-butyrolactone.

Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, 2-heptanone, cyclopentanone, cyclohexanone, ethyl lactate, etc., from the viewpoint of the leveling property of the coating film when the curable composition is applied, etc. And butyl lactate are preferred, and propylene glycol monomethyl ether acetate, 2-heptanone, cyclopentanone, and cyclohexanone are more preferred.

The amount of the solvent used in the curable composition is not particularly limited, and is appropriately determined in consideration of the viscosity and the like according to the use of the curable composition.
The amount of the solvent used is preferably set so that the solid content concentration in the curable composition is 5% by mass or more, more preferably 8% by mass or more, and 10% by mass or more. It is more preferable to set as such. The amount of the solvent used is preferably set so that the solid content concentration in the curable composition is 50% by mass or less, more preferably 45% by mass or less, and 40% by mass or less. It is more preferable to set so as to be.

The resin composition may further contain various additives as long as the object of the present invention is not impaired. Examples of additives include cross-linking agents, UV absorbers, sensitizers, plasticizers, antioxidants, light stabilizers, adhesion aids, and fillers (eg, for high refractive index such as zirconium oxide fine particles). Filler) and the like.

≪Cured product≫
A cured product is formed by heating the above resin after forming it into a desired shape. Since such a cured product contains the structural unit A3 derived from the above resin, it has a high refractive index.
The refractive index of the cured product is preferably 1.55 or more, more preferably 1.56 or more, and even more preferably 1.58 or more. The upper limit of the refractive index is not particularly limited, but is, for example, 1.70 or less.

≪Manufacturing method of cured product≫
Hereinafter, a method for producing a cured product of the above resin will be described.
The method for manufacturing the cured product is
A molding process for molding the above resin into a predetermined shape,
A curing process that cures the molded resin by heating,
including.

In the molding process, the shape of the resin after molding and the method of molding the resin are not particularly limited.
Examples of the method for molding the resin include a method of applying a composition containing a solvent and a resin on a base material and then removing the solvent from the coating film, and a method of removing the solvent from the coating film, and a composition containing the solvent and the resin on the base material. A method of removing the solvent after filling the liquid of the above, and a method of removing the solvent from the composition in the mold after filling the mold having a recess having a predetermined shape with the liquid of the composition containing the solvent and the resin. And so on.

The method of applying the composition onto the substrate is not particularly limited. For example, a composition containing the above resin is used by using a contact transfer type coating device such as a roll coater, a reverse coater, a bar coater, a slit coater, or a non-contact type coating device such as a spinner (rotary coating device) or a curtain flow coater. A coating film can be formed by coating an object on a substrate so as to have a desired film thickness.

A resin molded into a desired shape by molding a composition containing a solvent and a resin by the above method and then appropriately heat-treating (pre-baking (post-apply bake (PAB)) treatment) to remove the solvent. Is obtained.
The prebake temperature is appropriately selected in consideration of the boiling point of the solvent and the like. Pre-baking may be performed at low temperature under reduced pressure to prevent the resin from curing before the solvent is sufficiently removed.

The prebaking method is not particularly limited, and for example, (i) using a hot plate at a temperature of 80 ° C. or higher and 120 ° C. or lower (preferably 85 ° C. or higher and 100 ° C. or lower, more preferably 85 ° C. or higher and 95 ° C. or lower) 60. A method of drying for a time of seconds or more and 120 seconds or less, (ii) a method of leaving the product at room temperature for several hours or more and several days or less, (iii) a method of tens of minutes or more and several hours or less in a warm air heater or an infrared heater. Any of the methods of adding a base material and removing the solvent during the above time may be used.

By heating (post-baking) the resin formed as described above, a cured product of the resin is formed. The curing temperature is not particularly limited as long as the curing of the resin proceeds satisfactorily and the cured product does not undergo thermal denaturation or thermal decomposition.
The upper limit of the curing temperature is, for example, preferably 250 ° C. or lower, and preferably 230 ° C. or lower. The lower limit of the curing temperature is preferably 120 ° C. or higher, more preferably 130 ° C. or higher.
Further, the resin of the present embodiment can be cured at a low temperature, for example, the curing conditions can be 180 ° C. or lower, and the curing conditions can be 150 ° C. or lower.

By the above method, a cured product of the above-mentioned resin is produced.

≪Manufacturing method of microlens≫
Hereinafter, a method for manufacturing a microlens using the above resin will be described.
The manufacturing method of the micro lens is
A lens material layer forming step of forming a lens material layer by cross-linking a resin layer obtained by applying the above resin-containing composition onto a base material by heating.
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.
A shape transfer step in which the lens material layer and the lens pattern are dry-etched using the lens pattern as a mask and the shape of the lens pattern is transferred to the lens material layer.
including.

As the base material, an image element including a photodiode (organic photodiode, inorganic photodiode, etc.), a silicon wafer provided with a color filter layer, etc., a substrate such as a silicon wafer on which an antireflection film is further formed, etc. Can be mentioned.

The composition containing the above resin is typically a curable composition containing the above resin and a solvent. The method of applying the composition onto the substrate is not particularly limited. Specific examples of the method of applying the composition onto the substrate include the methods described above for the method of producing a cured product.
The resin layer can be formed by appropriately heat-treating the formed coating film (pre-baking (post-apply baking (PAB)) treatment) to remove the solvent in the coating film.
The specific method of pre-baking is also the same as described above for the method for producing the cured product.

The upper limit of the curing temperature in the lens material layer forming step is, for example, preferably 250 ° C. or lower, and 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, for example, a curing condition of 180 ° C. or lower, or a curing condition of 150 ° C. or lower.

The film thickness of the lens material layer to be formed is preferably in the range of 100 nm or more and 4.0 μm or less, and more preferably 400 nm or more and 2.0 μm or less.

The heating conditions for reflow in the lens pattern forming step differ depending on the type of each component in the composition used for forming the resist pattern, the blending ratio, the film thickness of the resist pattern, etc., but the heating temperature is, for example, 60 ° C. or higher and 150 ° C. Below (preferably 70 ° C. or higher and 140 ° C. or lower), the heating time is, for example, about 0.5 minutes or more and 60 minutes or less (preferably 1 minute or more and 50 minutes or less).
The film thickness of the resist pattern is preferably in the range of 100 nm or more and 4.0 μm or less, more preferably 400 nm or more and 2.0 μm or less.

The dry etching in the shape transfer step is not particularly limited, and examples _{thereof include dry etching by plasma (oxygen, argon, CF 4,} etc.), corona discharge, and the like.

Through the above steps, by using the above resin, it is possible to form a microlens having a high refractive index and little dimensional change and decrease in transparency when used in a high temperature environment. Therefore, the microlens formed by the above method is suitably used in various applications.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
100 parts by mass of a monomer mixture composed of 35 mol% of methacrylic acid ester (M1) of the following formula, 35 mol% of methacrylic acid ester (M2) of the following formula, and 30 mol% of methacrylic acid ester (M3) of the following formula. It was mixed and dissolved in 100 parts by mass of propylene glycol monomethyl ether in a flask. The flask was heated in an oil bath to an internal temperature of 75 ° C., and then 5 parts by mass of 2,2'-azobisisobutyronitrile propylene glycol monomethyl ether solution was gradually added dropwise into the flask. After completion of the dropping, the reaction was carried out for 20 hours while maintaining the temperature.

As a result of the polymerization, a resin 1 composed of the structural units of the following formula was obtained. In the following formula, the numerical value at the lower right of the parentheses means the content of each structural unit in the resin. The polystyrene-equivalent weight average molecular weight of the obtained resin 1 measured by GPC was 50,000.

[Examples 2 to 5]
A resin was obtained in the same manner as in Example 1 except that the monomer composition was changed to the composition shown in Table 1 below. The resins obtained in Examples 2 to 5 are designated as resins 2 to 5, respectively.
The weight average molecular weights of the resins 2 to 5 were 50,000, which was the same as that of the resin 1 obtained in Example 1.

[Examples 6 to 10 and Comparative Example 1]
In Examples 6 to 10, 99.94 parts by mass of the resin of the type shown in Table 2 and 0.06 parts by mass of a surfactant (PolyFox PF-656 (manufactured by Omniova)) were added to propylene glycol monomethyl ether acetate. To obtain a curable composition, the mixture was dissolved so as to have a solid content concentration of 15% by mass.
In Comparative Example 1, a comparative resin 1 (weight average molecular weight 50,000) having the following structure was used. In the following formula, the numerical value at the lower right of the parentheses means the content of each structural unit in the resin.

The obtained curable composition was applied onto a silicon substrate at a film thickness of 1 μm to form a coating film. The formed coating film was prebaked at 90 ° C. for 90 seconds and post-baked at 150 ° C. for 5 minutes to obtain a cured film. The film thickness of the obtained cured film is T1.
Next, the obtained cured film was immersed in acetone for 10 minutes at room temperature, and then the film thickness of the cured film after immersion was measured. The film thickness of the cured film after immersion is T2.
Based on the measurement results of T1 and T2, the following formula:
Residual film ratio (%) = T2 / T1 × 100
The residual film ratio was calculated by The curability was evaluated according to the following criteria based on the calculated residual film ratio. The results are shown in Table 2.
(Curing evaluation criteria)
⊚: Residual film ratio is 95% or more ○: Residual film ratio is 90% or more and less than 95% ×: Residual film ratio is less than 90%

According to Table 2, in Examples 6 to 10 using the resins 1 to 5 containing the structural unit A1, the structural unit A2, and the structural unit A3 described above, the coating film was applied to such an extent that a residual film ratio of 90% or more was exhibited. It can be seen that it can be cured well.
On the other hand, in Comparative Example 1 in which the comparative resin 1 containing the structural unit derived from glycidyl methacrylate was used instead of the structural unit A1, the residual film ratio of the formed cured film was less than 90%, as in the examples. Did not cure.

[Example 11, Comparative Example 2, and Comparative Example 3]
In Example 11, a curable composition containing the resin 1 used in Example 9 was used. In Comparative Example 2, the curable composition used in Comparative Example 1 was used. In Comparative Example 3, 100 parts by mass of the comparative resin 2 (weight average molecular weight 50,000) having the following structure and 1 part by mass of the thermoacid generator were dissolved in propylene glycol monomethyl ether acetate so as to have a solid content concentration of 15% by mass. The curable composition thus obtained was used. As the thermoacid generator here, K-PURE (registered trademark) CXC-1821 manufactured by King Industries was used.

The curable composition was applied on a silicon substrate or a color filter (CF) containing a basic amine component at a film thickness of 1 μm to form a coating film. The formed coating film was prebaked at 90 ° C. for 90 seconds and post-baked at 150 ° C. for 5 minutes to obtain a cured film. The film thickness of the obtained cured film is T1.
Next, the obtained cured film was immersed in acetone for 10 minutes at room temperature, and then the film thickness of the cured film after immersion was measured. The film thickness of the cured film after immersion is T2.
Based on the measurement results of T1 and T2, the following formula:
Residual film ratio (%) = T2 / T1 × 100
The residual film ratio was calculated by The calculated residual film ratio values are shown in Table 3.

According to Table 3, in Example 11 using the resin 1 to contain the structural unit A1, the structural unit A2, and the structural unit A3 described above, it may be on a Si substrate or on a CF in a basic atmosphere. It can be seen that the coating film can be satisfactorily cured to the extent that the residual film ratio is about the same.
On the other hand, in Comparative Example 2 in which the comparative resin 1 containing the structural unit derived from glycidyl methacrylate was used instead of the structural unit A1, the residual film ratio of the cured film formed on both the Si substrate and the CF was 90%. It was less than, and the curing did not proceed as much as in the examples.
Further, in Comparative Example 3 using the comparative resin 2 containing the structural unit derived from glycidyl methacrylate, the curing proceeded satisfactorily on the Si substrate by the use of the thermal acid generator. However, there was a large difference in the residual film ratio of the cured film between the curing on the Si substrate and the curing on the CF in the basic atmosphere.

[Example 12 and Comparative Examples 4 to 6]
In Example 12 and Comparative Examples 4 to 6, the thermal stability with respect to the film thickness of the cured film and the light transmittance was evaluated.
In Example 12, a cured film formed on the Si substrate was used as in Example 11. In Comparative Example 4, a cured film formed on the Si substrate was used as in Comparative Example 2. In Comparative Example 5, a cured film formed on the Si substrate was used as in Comparative Example 3.
In Comparative Example 6, a curable composition obtained by dissolving 100 parts by mass of Comparative Resin 3 (weight average molecular weight 10000) having the following structure in propylene glycol monomethyl ether acetate so as to have a solid content concentration of 18% by mass was used. , A cured film was formed on the Si substrate by the same method as in Example 11. The film thickness T1 of the cured film immediately after formation was measured.
In addition, the transmittance LT1 of light rays having a wavelength of 400 nm was measured for the cured film immediately after formation.

After the formed cured film was placed in a constant temperature bath at 150 ° C., the cured film was taken out at the time of 200 hours, 500 hours, 1000 hours, and 2000 hours, respectively, and had a film thickness of T3 and a wavelength of 400 nm, respectively. The light transmittance LT2 was measured. Based on the measurement result of each time, the following formula:
Film thickness reduction rate (%) = T3 / T1 × 100
Light transmittance reduction rate (%) = LT2 / LT1 × 100
The film thickness reduction rate and the light transmittance reduction rate at each time were determined. Table 4 shows the film thickness reduction rate and the light transmittance reduction rate at each time.

According to Table 4, in Example 12 using the resin 1 containing the structural unit A1, the structural unit A2, and the structural unit A3 described above, the film thickness and light transmittance were transmitted even when the cured film was held at 150 ° C. for 2000 hours. It can be seen that the rate does not decrease.
On the other hand, in Comparative Examples 4 to 6, in which the comparative resin 1, the comparative resin 2, and the comparative resin 3 containing the structural unit derived from glycidyl methacrylate were used instead of the structural unit A1, the formed cured film had a temperature of 150 ° C. It was found that the film thickness and the light transmittance decreased remarkably with the passage of time in the retention of the resin.

[Examples 13 to 15 and Comparative Example 7]
Resin 6 and comparative resin 4 were obtained in the same manner as in Example 1 except that the monomer composition was changed to the composition shown in Table 5 below. In addition, M4 shown in Table 5 is styrene.
In Examples 13 to 15 and Comparative Example 7, 99.94 parts by mass of the resin of the type shown in Table 5 and 0.06 parts by mass of a surfactant (PolyFox PF-656 (manufactured by Omniova)) were used as propylene. It was dissolved in glycol monomethyl ether acetate so as to have a solid content concentration of 15% by mass to obtain a curable composition.
Using each curable composition, a cured film having a film thickness of 1 μm was formed in the same manner as in Example 6, and the refractive index of the formed cured film was measured. The measurement results of the refractive index are shown in Table 5.

According to Table 5, it can be seen that in Examples 13 to 15 using the resin 1 containing the structural unit A1, the structural unit A2, and the structural unit A3 described above, a cured film exhibiting a refractive index of 1.56 or more can be formed. ..
On the other hand, in Comparative Example 7 using the comparative resin 4 containing the structural unit derived from styrene containing only one benzene ring instead of the structural unit A3, only a cured film having a refractive index of about 1.54 could be formed. ..

Claims (5)

A resin consisting only of 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) , or a table represented by the following formula (a1). It is derived from the structural unit represented by the following formula (a2), the structural unit represented by the following formula (a3), and the (meth) acrylic acid ester represented by the following formula (a-IV). A resin consisting of only structural units
The total amount of the structural unit represented by the following formula (a1), the structural unit represented by the following formula (a2), and the structural unit represented by the following formula (a3) is based on all the structural units in the resin. , 80 mol% or more,
The amount of the structural unit represented by the following formula (a1) in the resin is 15 mol% or more and 45 mol% or less with respect to all the structural units of the resin.
The amount of the structural unit represented by the following formula (a2) in the resin is 15 mol% or more and 45 mol% or less with respect to all the structural units of the resin.
The amount of the structural unit represented by the following formula (a3) in the resin is 20 mol% or more and 60 mol% or less with respect to all the structural units of the resin.
A resin in which the structural unit represented by the following formula (a3) is the structural unit represented by the following formula (a3-1).

(In the formulas (a1), (a2), and (a3), R ¹ is an independently hydrogen atom or a methyl group, and R ² is a single bond or an alkylene group having 1 to 5 carbon atoms. Yes, R ³ is a blocked isocyanate group, R ⁴ is a divalent hydrocarbon group, R ⁵ is a single bond or a divalent linking group, and R ⁶ is two or more benzene rings. It is an organic group containing.)

(In the formula (a3-1), R ¹ is the same as the above formula (a 3), R ¹⁰ is an independent halogen atom or an organic group having 1 to 6 carbon atoms, and b is an organic group, respectively. It is an integer from 0 to 4.

(In the formula a-IV, ^Ra1 is a hydrogen atom or a methyl group, and ^Raa11 is a group containing active hydrogen capable of reacting with an isocyanate group generated from the blocked isocyanate group in the structural unit (a1). It is an organic group that does not exist.) As the structural unit represented by the formula (a1), the structural unit represented by the following formula (a1-1), the structural unit represented by the following formula (a1-2), and the following formula (1-3). The resin according to claim 1, which comprises at least one of the structural units selected from the group consisting of the indicated structural units.

(In the formula (a1-1), the formula (a1-2) and the formula (a1-3), R ¹ and R ² are the same as those in the formula (a 1), and R ⁷ is an independent carbon atom. ^{R 8} is an organic group having 1 to 12 carbon atoms, R 8 is an organic group ^{having 1 to 6 carbon atoms independently, and R 9} is an organic group having 1 to 6 carbon atoms independently. Yes, a is an integer from 0 to 3.) Wherein R ⁴ is a divalent chain aliphatic hydrocarbon group, resin according to claim 1 or 2. Claims 1 to 100, wherein the ratio of the number of moles of the structural unit represented by the formula (a1) to the number of moles of the structural unit represented by the formula (a2) is 80/100 or more and 100/80 or less. The resin according to any one of 3. The resin according to any one of claims 1 to 4 , which has a weight average molecular weight of 30,000 or more.