Curable composition, resin, and cured product

Abstract

To provide a curable composition which gives a cured product having high solvent resistance and exhibiting a low refractive index and is excellent in stability over time, a resin which can be suitably blended in the curable composition, and a cured product of the curable composition.SOLUTION: In a curable composition which comprises resin (A) and solvent (S), with or without a colorant (C), the resin (A) is dissolved in the solvent (S) and the ratio of the mass of the colorant (C) to the total mass of the components other than the solvents (S) of the curable composition is less than 50 mass%. As the resin (A), a resin containing ester-containing units (a1), hydroxy group-donating units (a2), and block isocyanate group-containing units (a3) is used.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable composition containing a resin containing a structural unit of a specific structure, a resin suitably blended with the above curable composition, and a cured product of the above curable composition.

Background Art

[0002] Conventionally, a resin material having an appropriately adjusted refractive index has been known, and such a material is used in the optical field and the like. As a composition for forming a low refractive index material, for example, a (meth)acrylic resin containing a structural unit having an epoxy group and a structural unit having a hydrocarbon group substituted with a hydroxyl group, hollow resin particles having a specific particle diameter, and an organic solvent A curable resin composition containing has been proposed (see Patent Document 1). By using the curable resin composition described in Patent Document 1, a cured product having high solvent resistance and a low refractive index can be formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The curable composition described in Patent Document 1 cures by a curing reaction of an epoxy group. Since the epoxy group is highly reactive, the curable composition described in Patent Document 1 has a problem of being likely to thicken over time.

[0005] The present invention has been made in view of such circumstances, and provides a curable composition that gives a cured product having high solvent resistance and a low refractive index and excellent stability over time, a resin that can be suitably blended with the curable composition, and a cured product of the above curable composition. The purpose is to provide.

Means for Solving the Problems

[0006] The present inventors have found that the above problems can be solved by dissolving the resin (A) in the solvent (S) in a curable composition that contains a resin (A) and a solvent (S) and may or may not contain a colorant (C), making the mass ratio of the colorant (C) less than 50 mass% relative to the total mass of the components other than the solvent (S) in the curable composition, and using a resin containing an ester-containing unit (a1), a hydroxyl-donor unit (a2), and a blocked isocyanate group-containing unit (a3) ​​as the resin (A), and have arrived at the present invention. Specifically, the present invention provides the following.

[0007] A first aspect of the present invention is a curable composition comprising a resin (A) and a solvent (S), with or without a colorant (C), Resin (A) is dissolved in solvent (S), the ratio of the mass of the colorant (C) to the total mass of the components other than the solvent (S) of the curable composition is less than 50 mass%, The resin (A) contains an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3), The ester-containing unit (a1) is represented by the following formula (A1): -CO-OR (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent, or a trialkylsilyl group.) and having an ester group represented by The ester-containing unit (a1) is a unit that does not fall under the category of the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3) ​​in the curable composition.

[0008] A second aspect of the present invention is a resin comprising an ester-containing unit (a1), a hydroxyl-donor unit (a2), and a blocked isocyanate group-containing unit (a3), but not comprising an acidic group-containing unit (a4), The ester-containing unit (a1) is represented by the following formula (A1): -CO-OR (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.) having an ester group represented by The ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3). The resin is a resin in which the ratio of the number of moles of the blocked isocyanate group-containing unit (a3) to the number of moles of all the constituent units of the resin (A) is 15 mol% or more.

[0009] A third aspect of the present invention is a cured product of the curable composition according to the first aspect. [Effect of the Invention]

[0010] According to the present invention, it is possible to provide a curable composition that gives a cured product having high solvent resistance and a low refractive index and excellent stability over time, a resin that can be suitably blended with the curable composition, and a cured product of the aforementioned curable composition. [Embodiments for Carrying Out the Invention]

[0011] ≪Curable Composition≫ The curable composition contains a resin (A) and a solvent (S), and may or may not contain a colorant (C). The resin (A) is dissolved in the solvent (S). The resin (A) contains an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3). The ester-containing unit (a1) has the following formula (A1): -CO-O-R (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.) having an ester group represented by The ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3).

[0012] The curable composition provides a cured product with a low refractive index. Therefore, the cured product of the curable composition is suitably used as an optical material. Accordingly, the curable composition does not contain a large amount of the colorant (C). Specifically, the ratio of the mass of the colorant (C) to the total mass of the components other than the solvent (S) of the curable composition is less than 50% by mass.

[0013] Specifically, it is preferable that the refractive index at a wavelength of 550 nm of a cured film with a thickness of 1 μm formed by heating a coating film composed of the curable composition at 100 °C for 60 seconds and then heating at 200 °C for 5 minutes is 1.53 or less. The refractive index of the cured film can be adjusted by adjusting the content of the ester-containing unit (a1) in the resin (A) or by adjusting the content of the hollow particles (B) described later in the curable composition.

[0014] Hereinafter, the essential or optional components that can be contained in the curable composition will be described.

[0015] <Resin (A)> The resin (A) contains an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3). Hereinafter, the "ester-containing unit (a1)" will also be referred to as "unit (a1)". The "hydroxyl group-donating unit (a2)" will also be referred to as "unit (a2)". The "blocked isocyanate group-containing unit (a3)" will also be referred to as "unit (a3)". In addition, in the specification of the present application, "unit" means "structural unit". Furthermore, the resin (A) may contain an acidic group-containing unit (a4) and other units (a5) in addition to the unit (a1), the unit (a2), and the unit (a3) as long as the desired purpose is not impaired. These units may be present in the resin in a block form or randomly. From the viewpoint of the reactivity of the resin (A), each unit constituting the resin (A) is preferably randomly present in the resin (A).

[0016] 〔Ester-containing unit (a1)〕 The ester-containing unit (a1) is represented by the following formula (A1): -CO-O-R (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent, or a trialkylsilyl group.) It has an ester group represented by the formula. The ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2), the blocked isocyanate group-containing unit (a3), the acidic group-containing unit (a4), and the other unit (a5).

[0017] The structure of the aliphatic hydrocarbon group as R may be linear, cyclic, or a combination of a linear structure and a cyclic structure. The aliphatic hydrocarbon group may have one or more unsaturated bonds. As the aliphatic hydrocarbon group, a saturated hydrocarbon group is preferred. Also, from the viewpoint of the stability of the curable composition, when the aliphatic hydrocarbon group as R has a tertiary carbon atom, it is preferable that the non-carbonyl oxygen atom in the formula (A1) is not bonded to the tertiary carbon atom in the aliphatic hydrocarbon group as R.

[0018] The aliphatic hydrocarbon group may have a substituent. The number of substituents of the aliphatic hydrocarbon group is not particularly limited as long as the desired effect is not impaired. The number of substituents is typically preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and even more preferably 1 or 2.

[0019] Examples of the substituent that the aliphatic hydrocarbon group may have include an alkoxy group, an aliphatic acyl group, an aliphatic acyloxy group, a halogen atom, an amide group (-CONR A1 2), an imide group (-N(-CO-R A2 )2), a cyano group, an alkylthio group, an aliphatic acylthio group, and a thiol group. Regarding the amide group, R A1 is a hydrogen atom or an aliphatic hydrocarbon group. As the aliphatic hydrocarbon group as R A1 , an alkyl group having 1 or more and 6 or less carbon atoms is preferred. Regarding the imide group, R A2 is an aliphatic hydrocarbon group. The two R A1may be the same as or different from each other. In the imide group, two Rs A2 as aliphatic hydrocarbon groups may be bonded to each other to form a ring. As the aliphatic hydrocarbon group for R A2 an alkyl group having 1 to 6 carbon atoms is preferable. When two aliphatic hydrocarbon groups as Rs A2 are bonded to each other to form a ring, examples of the imide group include a succinimide group, a maleimide group, and the like. Two Rs A2 may be the same as or different from each other.

[0020] As the alkoxy group as a substituent, an alkoxy group having 1 to 4 carbon atoms is preferable. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, an isobutyloxy group, a sec-butyloxy group, and a tert-butyloxy group.

[0021] As the aliphatic acyl group as a substituent, an aliphatic acyl group having 2 to 4 carbon atoms is preferable. Specific examples of the aliphatic acyl group include an acetyl group, a propionyl group, and a butanoyl group.

[0022] As the aliphatic acyloxy group as a substituent, an aliphatic acyloxy group having 2 to 4 carbon atoms is preferable. Specific examples of the aliphatic acyloxy group include an acetyloxy group, a propionyloxy group, and a butanoyloxy group.

[0023] Examples of the halogen atom as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and a chlorine atom.

[0024] Specific examples of the amide group include a carbamoyl group (-CO-NH2), an N-methylcarbamoyl group, an N-ethylcarbamoyl group, an N,N-dimethylcarbamoyl group, and an N,N-diethylcarbamoyl group.

[0025] Specific examples of the imide group include an N,N-diacetylamino group, an N,N-dipropionylamino group, a succinimide group, and a maleimide group.

[0026] As the alkylthio group as a substituent, an alkylthio group having 1 to 4 carbon atoms is preferable. Specific examples of the alkylthio group include a methylthio group, an ethylthio group, an n-propylthio group, an isopropylthio group, an n-butylthio group, an isobutylthio group, a sec-butylthio group, and a tert-butylthio group.

[0027] As the aliphatic acylthio group as a substituent, an aliphatic acylthio group having 2 to 4 carbon atoms is preferable. Specific examples of the aliphatic acylthio group include an acetylthio group, a propionylthio group, and a butanoylthio group.

[0028] Among the substituents described above, an alkoxy group, an aliphatic acyl group, an aliphatic acyloxy group, a halogen atom, an amide group, an imide group, and a cyano group are preferable, and an alkoxy group, an aliphatic acyl group, an aliphatic acyloxy group, a halogen atom, an amide group, and an imide group are more preferable.

[0029] The number of carbon atoms of the aliphatic hydrocarbon group as R in formula (A1) is not particularly limited. The number of carbon atoms of the aliphatic hydrocarbon group is preferably 1 or more and 20 or less, more preferably 1 or more and 16 or less, further preferably 1 or more and 12 or less, still further preferably 1 or more and 6 or less, and particularly preferably 1 or more and 4 or less. Note that the above-mentioned number of carbon atoms does not include the number of carbon atoms of the substituent.

[0030] Preferable specific examples of the chain aliphatic hydrocarbon group as R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a sec-pentyl group, a tert-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group, etc.

[0031] Preferable specific examples of the cyclic aliphatic hydrocarbon group as R include cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group; polycycloalkyl groups such as an adamantyl group, a norbornyl group, an isobornyl group, a tricyclodecanyl group, and a tetracyclodecanyl group. The polycycloalkyl group is a group obtained by removing one hydrogen atom from a polycycloalkane.

[0032] Preferable specific examples of the group consisting of a chain aliphatic hydrocarbon group and a cyclic aliphatic hydrocarbon group as R include 1-alkylcyclopentan-1-yl groups such as 1-methylcyclopentan-1-yl group, 1-ethylcyclopentan-1-yl group, 1-n-propylcyclopentan-1-yl group, 1-isopropylcyclopentan-1-yl group, and 1-n-butylcyclopentan-1-yl group; 1-alkylcyclohexan-1-yl groups such as 1-methylcyclohexan-1-yl group, 1-ethylcyclohexan-1-yl group, 1-n-propylcyclohexan-1-yl group, 1-isopropylcyclohexan-1-yl group, and 1-n-butylcyclohexan-1-yl group; 1-alkylcycloheptan-1-yl groups such as 1-methylcycloheptan-1-yl group, 1-ethylcycloheptan-1-yl group, 1-n-propylcycloheptan-1-yl group, 1-isopropylcycloheptan-1-yl group, and 1-n-butylcycloheptan-1-yl group; 1-alkylcyclooctan-1-yl groups such as 1-methylcyclooctan-1-yl group, 1-ethylcyclooctan-1-yl group, 1-n-propylcyclooctan-1-yl group, 1-isopropylcyclooctan-1-yl group, and 1-n-butylcyclooctan-1-yl group; 2-alkyladamantan-2-yl groups such as 2-methyladamantan-2-yl group, 2-ethyladamantan-2-yl group, 2-n-propyladamantan-2-yl group, 2-isopropyladamantan-2-yl group, and 2-n-butyladamantan-2-yl group; and 2-alkylnorbornan-2-yl groups such as 2-methylnorbornan-2-yl group, 2-ethylnorbornan-2-yl group, 2-n-propylnorbornan-2-yl group, 2-isopropylnorbornan-2-yl group, and 2-n-butylnorbornan-2-yl group.

[0033] In formula (A1), R may be a trialkylsilyl group. In the trialkylsilyl group, the number of carbon atoms of the alkyl group bonded to the silicon atom is preferably 1 or more and 6 or less. Preferable specific examples of the trialkylsilyl group include a trimethylsilyl group, a triethylsilyl group, a tri-n-propylsilyl group, a triisopropylsilyl group, and a tri-n-butylsilyl group.

[0034] The type of the resin (A) is not particularly limited, but an acrylic resin is preferable because monomers and the resin (A) are easily available and easy to prepare, and it is easy to form a cured product with a low refractive index. The acrylic resin is a polymer of a monomer containing (meth)acrylic acid and / or a (meth)acrylic acid derivative.

[0035] When the resin (A) is an acrylic resin, the unit (a1) is preferably a unit derived from a (meth)acrylate represented by the following formula (A1-1). In the formula (A1-1), R is the same as R in the formula (A1). R 11 is a hydrogen atom or a methyl group. CH=CR 11 -CO-O-R (A1-1)

[0036] As the (meth)acrylate that gives the unit (a1), the (meth)acrylate in which the hydrocarbon group as R is any one of the preferable specific examples of the chain aliphatic hydrocarbon group, the preferable specific examples of the cyclic aliphatic hydrocarbon group, or the preferable specific examples of the group composed of a chain aliphatic hydrocarbon group and a cyclic aliphatic hydrocarbon group is preferable. Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 1-methylcyclopentyl (meth)acrylate, 1-ethylcyclopentyl (meth)acrylate, 1-methylcyclohexyl (meth)acrylate, 1-ethylcyclohexyl (meth)acrylate, 2-methyladamantan-2-yl (meth)acrylate, 2-ethyladamantan-2-yl (meth)acrylate, 2-n-propyladamantan-2-yl (meth)acrylate, and 2-isopropyladamantan-2-yl (meth)acrylate.

[0037] The ratio of the number of moles of the unit (a1) to the total number of moles of all the constituent units of the resin (A) is not particularly limited as long as the desired effect is not impaired. The ratio of the number of moles of the unit (a1) to the total number of moles of all the constituent units of the resin (A) is preferably 15 mol% or more, more preferably 15 mol% or more and 90 mol% or less, and still more preferably 20 mol% or more and 70 mol% or less.

[0038] [Hydroxyl group-providing unit (a2)] The hydroxyl group-providing unit (a2) has a hydroxyl group or can generate a hydroxyl group by a chemical reaction due to the action of light or heat. In the specification of the present application, the hydroxyl group that the hydroxyl group-providing unit (a2) has or generates is defined as an alcoholic hydroxyl group or a phenolic hydroxyl group and is a group bonded to a carbon atom. Therefore, a carboxyl group, a silanol group, etc. do not correspond to the hydroxyl group that the hydroxyl group-providing unit (a2) has or generates. When the resin (A) is an acrylic resin, the hydroxyl group-providing unit (a2) is preferably a unit derived from an acrylic acid ester having a hydroxyl group. For example, a lactone ring such as a γ-butyrolactone ring can be opened by a chemical reaction due to the action of light or heat to generate a hydroxyl group.

[0039] When the resin (A) is an acrylic resin, as the unit (a2), the unit represented by the following formula (a2-1) is preferable.

Chemical formula

[0040] R a22 When the organic group having a hydroxyl group is an organic group having a hydroxyl group, the organic group may be an aliphatic group, an aromatic group, or a combination of an aliphatic group and an aromatic group. The number of hydroxyl groups of the organic group having a hydroxyl group as R a22 is not particularly limited as long as the desired effect is not impaired. The number of hydroxyl groups of the organic group having a hydroxyl group as R a22 is typically preferably 1 or more and 4 or less, more preferably 1 or 2, and even more preferably 1.

[0041] R a22 is preferably a hydrocarbon group substituted with a hydroxyl group. The hydrocarbon group may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. As the hydrocarbon group, an aliphatic hydrocarbon group is preferable. The aliphatic hydrocarbon group may be linear, branched, cyclic, or a combination of these structures. As the aliphatic hydrocarbon group, a linear aliphatic hydrocarbon group is preferable.

[0042] R a22 When the hydrocarbon group is a hydrocarbon group substituted with a hydroxyl group, the number of carbon atoms of the hydrocarbon group substituted with a hydroxyl group is not particularly limited. When the hydrocarbon group is an aliphatic hydrocarbon group, the number of carbon atoms of the hydrocarbon group substituted with a hydroxyl group 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 in the hydrocarbon group substituted with a hydroxyl group is an aromatic hydrocarbon group or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group, the number of carbon atoms in the hydrocarbon group substituted with a hydroxyl group is preferably 6 or more and 20 or less, more preferably 6 or more and 12 or less.

[0043] Specific examples of the aliphatic hydrocarbon group substituted with a hydroxyl group include hydroxymethyl group, 2-hydroxyethyl group, 1-hydroxyethyl group, 3-hydroxypropyl group, 2-hydroxypropyl group, 1-hydroxypropyl group, 4-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxyhexyl group, 7-hydroxyheptyl group, 8-hydroxyoctyl group, 9-hydroxynonyl group, 10-hydroxydecyl group, 11-hydroxyundecyl group, 12-hydroxydodecyl group, 13-hydroxytridecyl group, 14-hydroxytetradecyl group, 15-hydroxypentadecyl group, 16-hydroxyhexadecyl group, 17-hydroxyheptadecyl group, 18-hydroxyoctadecyl group, 19-hydroxynonadecyl group, and 20-hydroxyicosyl group. Among these, hydroxymethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxyhexyl group, 7-hydroxyheptyl group, 8-hydroxyoctyl group, 9-hydroxynonyl group, 10-hydroxydecyl group, 11-hydroxyundecyl group, 12-hydroxydodecyl group, 13-hydroxytridecyl group, 14-hydroxytetradecyl group, 15-hydroxypentadecyl group, 16-hydroxyhexadecyl group, 17-hydroxyheptadecyl group, 18-hydroxyoctadecyl group, 19-hydroxynonadecyl group, and 20-hydroxyicosyl group are preferred. Among these, hydroxymethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxyhexyl group, 7-hydroxyheptyl group, 8-hydroxyoctyl group, 9-hydroxynonyl group, and 10-hydroxydecyl group are more preferred. Among these, a 2-hydroxyethyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 5-hydroxypentyl group, and 6-hydroxyhexyl group are more preferable.

[0044] Specific examples of the aromatic hydrocarbon group substituted with a hydroxyl group include a 4-hydroxyphenyl group, 3-hydroxyphenyl group, 2-hydroxyphenyl group, 4-hydroxynaphthalen-1-yl group, 6-hydroxynaphthalen-2-yl group, and 7-hydroxynaphthalen-2-yl group. Among these, a 4-hydroxyphenyl group and 3-hydroxyphenyl group are preferable, and a 4-hydroxyphenyl group is more preferable.

[0045] The lactone cyclic group is not particularly limited as long as it can generate a hydroxyl group by hydrolysis. The number of carbon atoms in the lactone ring is preferably 3 or more and 8 or less, and more preferably 4 or more and 6 or less. The lactone cyclic group preferably binds to the non-carbonyl oxygen atom in formula (a2-1) at a position adjacent to the carbonyl group in the lactone ring. Preferable specific examples of the lactone cyclic group include a 4-oxooxetan-3-yl group (propionolactonyl group), 5-oxotetrahydrofuran-4-yl group (butyrolactonyl group), and 6-oxotetrahydropyran-5-yl group (valerolactonyl group).

[0046] Preferable specific examples of the (meth)acrylate that gives the unit represented by formula (a2-1) 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, 4-oxooxetan-3-yl acrylate, 4-oxooxetan-3-yl methacrylate, 5-oxotetrahydrofuran-4-yl acrylate, 5-oxotetrahydrofuran-4-yl methacrylate, 6-oxotetrahydropyran-5-yl acrylate, and 6-oxotetrahydropyran-5-yl methacrylate, and the like. Among these, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 5-oxotetrahydrofuran-4-yl acrylate, and 5-oxotetrahydrofuran-4-yl methacrylate are preferable.

[0047] The ratio of the number of moles of unit (a2) to the total number of moles of all the constituent units of resin (A) is not particularly limited as long as the desired effect is not impaired. The ratio of the number of moles of unit (a2) to the total number of moles of all the constituent units of resin (A) is preferably 5 mol% or more, more preferably 15 mol% or more and 50 mol% or less, and even more preferably 20 mol% or more and 40 mol% or less. Note that the number of moles M of unit (a2) in resin (A) H and the number of moles M of unit (a3) BI The ratio between them is preferably 30:70 to 70:30, more preferably 40:60 to 60:40, and even more preferably 45:55 to 55:45 as M H :M BI

[0048] [Block isocyanate group-containing unit (a3)] The blocked isocyanate group means a group in which the isocyanate group is blocked by a thermally dissociable protecting group. The blocked isocyanate group-containing unit (a3) is a unit having the above-described blocked isocyanate group.

[0049] When the resin (A) is an acrylic resin, the blocked isocyanate group-containing unit (a3) is preferably a unit derived from an acrylate having a blocked isocyanate group. As the unit derived from an acrylate having a blocked isocyanate group, a unit represented by the following formula (a3-1) is preferable. [Chemical formula] (In formula (a3-1), R a31 is a hydrogen atom or a methyl group, R a32 is a single bond or an alkylene group having 1 to 5 carbon atoms, and R a33 is a blocked isocyanate group.)

[0050] In formula (a3-1), R a32 is a single bond or an alkylene group having 1 to 5 carbon atoms. The alkylene group may be linear or branched, and is preferably linear. Specific examples of the alkylene group as R a32 include a methylene group, an ethane-1,2-diyl group, an ethane-1,1-diyl group, a propane-1,3-diyl group, a propane-1,2-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group. 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, a methylene group, an ethane-1,2-diyl group, and a propane-1,3-diyl group are more preferable, and an ethane-1,2-diyl group is particularly preferable.

[0051] In formula (a3-1), R a33is a blocked isocyanate group. 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 the protecting group.

[0052] Examples of such blocking agents include alcohol-based compounds, phenol-based compounds, hydroxyl group-containing compounds other than alcohol-based compounds and phenol-based compounds, active methylene-based compounds, amine-based compounds, imine-based compounds, oxime-based compounds, carbamic acid-based compounds, urea-based compounds, acid amide-based (lactam-based) compounds, acid imide-based compounds, triazole-based compounds, pyrazole-based compounds, pyrrole-based compounds, mercaptan-based compounds, and bisulfites.

[0053] 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, 2-methoxypropanol, 2-ethoxyethanol, n-propoxyethanol, 2-butoxyethanol, 2-(2-ethoxyethoxy)ethanol, 2-(4-ethoxybutoxy)ethanol, 2-(2-butoxyethoxy)ethanol, N,N-dibutyl-2-hydroxyacetamide, N-morpholineethanol, 2,2-dimethyl-1,3-dioxolan-4-methanol, 3-oxazolidineethanol, 2-hydroxymethylpyridine, furfuryl alcohol, 12-hydroxystearic acid, and 2-hydroxyethyl methacrylate.

[0054] Examples of phenolic compounds include phenol, o-cresol, m-cresol, p-cresol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2-n-propylphenol, 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-di-n-propylphenol, 2,4-di-n-propylphenol, 2,5-di-n-propylphenol, 2,6-di-n-propylphenol, 3,4-di-n-propylphenol, 3,5-di-n-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, 2,3-Di-n-butylphenol, 2,4-Di-n-butylphenol, 2,5-Di-n-butylphenol, 2,6-Di-n-butylphenol, 3,4-Di-n-butylphenol, 3,5-Di-n-butylphenol, 2,3-Di-sec-butylphenol, 2,4-Di-sec-butylphenol, 2,5-Di-sec-butylphenol, 2,6-Di-sec-butylphenol, 3,4-Di-sec-butylphenol, 3,5-Di-sec-butylphenol, 2,3-Di-tert-butylphenol, 2,4-Di-tert-butylphenol, 2,5-Di-tert-butylphenol, 2,6-Di-tert-butylphenol, 3,4-Di-tert-butylphenol, 3,5-Di-tert-butylphenol, 2,3-Di-n-octylphenol, 2,4-Di-n-octylphenol, 2,5-Di-n-octylphenol, 2,6-Di-n-octylphenol, 3,4-Di-n-octylphenol, 3,5-Di-n-octylphenol, 2,3-Di-2-ethylhexylphenol, 2,4-Di-2-ethylhexylphenol, 2,5-Di-2-ethylhexylphenol, 2,6-Di-2-ethylhexylphenol, 3,4-Di-2-ethylhexylphenol, 3,5-Di-2-ethylhexylphenol, 2,3-Di-n-nonylphenol, 2,4-Di-n-nonylphenol, 2,5-Di-n-nonylphenol, 2,6-Di-n-nonylphenol, 3,4-Di-n-nonylphenol, 3,5-di-n-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 (mono-, di-, or tri-substituted phenol by α-methylbenzyl group), 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, and 2-chloro-3-pyridinol, etc. can be mentioned.,

[0055] Examples of hydroxyl group-containing compounds other than alcohol-based compounds and phenol-based compounds include N-hydroxysuccinimide and triphenylsilanol.,

[0056] Examples of active methylene compounds include Meldrum's acid, dialkyl malonates (e.g., dimethyl malonate, diethyl malonate, di-n-butyl malonate, di-tert-butyl malonate, di-2-ethylhexyl malonate, methyl n-butyl malonate, ethyl n-butyl malonate, methyl sec-butyl malonate, ethyl sec-butyl malonate, methyl tert-butyl malonate, ethyl tert-butyl malonate, diethyl methylmalonate, dibenzyl malonate, diphenyl malonate, benzyl methyl malonate, ethyl phenyl malonate, tert-butyl phenyl malonate, and isopropylidene malonate, etc.), alkyl acetoacetates (e.g., methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate, n-butyl acetoacetate, tert-butyl acetoacetate, benzyl acetoacetate, and phenyl acetoacetate, etc.), 2-acetoacetoxyethyl methacrylate, acetylacetone, and ethyl cyanoacetate, etc.,

[0057] Examples of amine compounds include dibutylamine, diphenylamine, aniline, N-methylaniline, carbazole, bis(2,2,6,6-tetramethylpiperidinyl)amine, di-n-propylamine, diisopropylamine, isopropylethylamine, 2,2,4-trimethylhexamethyleneamine, 2,2,5-trimethylhexamethyleneamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis(3,5,5-trimethylcyclohexyl)amine, piperidine, 2,6-dimethylpiperidine, tert-butylmethylamine, tert-butylethylamine, tert-butyl n-propylamine, tert-butyl n-butylamine, tert-butylbenzylamine, tert-butylphenylamine, 2,2,6-trimethylpiperidine, 2,2,6,6-tetramethylpiperidine, (dimethylamino)-2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethyl-4-piperidine, 6-methyl-2-piperidine, and 6-aminocaproic acid, etc.

[0058] Examples of imine compounds include ethyleneimine, polyethyleneimine, 1,4,5,6-tetrahydropyrimidine, and guanidine, etc.

[0059] Examples of oxime compounds include formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, diacetyl monoxime, benzophenone oxime, 2,2,6,6-tetramethylcyclohexanone oxime, diisopropyl ketone oxime, methyl tert-butyl ketone oxime, diisobutyl ketone oxime, methyl isobutyl ketone oxime, methyl isopropyl ketone oxime, methyl 2,4-dimethylpentyl ketone oxime, methyl 3-ethylheptyl ketone oxime, methyl isoamyl ketone oxime, n-amyl ketone oxime, 2,2,4,4-tetramethyl-1,3-cyclobutanedione monoxime, 4,4'-dimethoxybenzophenone oxime, and 2-heptanone oxime, etc.

[0060] Examples of the carbamic acid compounds include phenyl N-phenylcarbamate and the like.

[0061] Examples of the urea compounds include urea, thiourea, ethylene urea, and the like.

[0062] Examples of the acid amide (lactam) compounds include acetanilide, N-methylacetamide, acetamide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, pyrrolidone, 2,5-piperazinedione, laurolactam, and the like.

[0063] Examples of the acid imide compounds include succinimide, maleimide, phthalimide, and the like.

[0064] Examples of the triazole compounds include 1,2,4-triazole, benzotriazole, and the like.

[0065] Examples of the pyrazole compounds include pyrazole, 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, 3,5-diphenylpyrazole, 3,5-di-tert-butylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, 3-methyl-5-phenylpyrazole, and the like.

[0066] Examples of the pyrrole compounds include pyrrole, 2-methylpyrrole, 3-methylpyrrole, 2,4-dimethylpyrrole, and the like.

[0067] Examples of the mercaptan compounds include n-butyl mercaptan, n-dodecyl mercaptan, n-hexyl mercaptan, thiophenol, pyridine-2-thiol, and the like.

[0068] Examples of the bisulfites include sodium bisulfite and the like.

[0069] Among these blocking agents, an acid amide compound, an alcohol compound, or an oxime compound is preferable because it does not deactivate the acid generated by the acid generator (B) and good patterning characteristics can be obtained. As the acid amide compound, a lactam compound is preferable.

[0070] As the lactam compound, a compound having a group represented by the following formula (a3-2) as R a33 is preferable. -NH-CO-R a34 ···(a3-2) (In formula (a3-2), R a34 is a lactam ring group. The lactam ring group is a group obtained by removing a hydrogen atom from the nitrogen atom in the lactam ring. The nitrogen atom in the lactam ring group is bonded to the carbon atom in the carbonyl group.)

[0071] As the alcohol compound, a compound having a group represented by the following formula (a3-3) as R a33 is preferable. -NH-CO-R a35 ···(a3-3) (In formula (a3-3), R a35 is an alkoxy group. The oxygen atom in the alkoxy group is bonded to the carbon atom in the carbonyl group. The alkoxy group may contain a hetero atom other than the oxygen atom of the alkoxy group. Examples of the hetero atom include an oxygen atom, a sulfur atom, and a nitrogen atom.)

[0072] As the oxime compound, a compound having a group represented by the following formula (a3-4) as R a33 is preferable. -NH-CO-R a36 ···(a3-4) (In formula (a3-4), R a36 is an oxime group. The oxime group is a group obtained by removing a hydrogen atom from the oxygen atom in the oxime structure. The oxygen atom in the oxime group is bonded to the carbon atom in the carbonyl group.)

[0073] The ratio of the number of moles of unit (a3) to the total number of moles of all the constituent units of resin (A) is not particularly limited as long as the desired effect is not impaired. The ratio of the number of moles of unit (a3) to the total number of moles of all the constituent units of resin (A) is preferably 5 mol% or more, more preferably 15 mol% or more and 50 mol% or less, and even more preferably 20 mol% or more and 40 mol% or less.

[0074] 〔Acidic group-containing unit (a4)〕 Resin (A) may contain an acidic group-containing unit (a4) as long as the desired effect is not impaired. Resin (A) preferably does not contain an acidic group-containing unit (a4). However, the acidic group-containing unit (a4) does not correspond to the hydroxyl group-donating unit (a2). The acidic group-containing unit (a4) is also referred to as unit (a4). The acidic group contained in the acidic group-containing unit (a4) is typically a protonic acidic group. Examples of the protonic acidic group include a carboxy group, a sulfonic acid group, a phosphonic acid group, and a phosphinic acid group.

[0075] When resin (A) is an acrylic resin, the acidic group-containing unit (a4) is a unit derived from an unsaturated compound having an acidic group. The acidic group-containing unit (a4) is preferably a unit derived from unsaturated carboxylic acids. Examples of the unsaturated carboxylic acids include monocarboxylic acids such as (meth)acrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itaconic acid; anhydrides of these dicarboxylic acids; and the like. Among these, (meth)acrylic acid is preferred.

[0076] 〔Other unit (a5)〕 Resin (A) may contain other units (a5) in addition to the aforementioned units (a1), (a2), (a3), and (a4) as long as the desired effect is not impaired.

[0077] When the resin (A) is an acrylic resin, examples of the other unit (a5) include units derived from (meth)acrylic acid esters. However, as the unit (meth)acrylic acid ester, a compound represented by the following formula (a5-1) is preferable. [Chemical formula]

[0078] In the above formula (a5-1), R a51 is a hydrogen atom or a methyl group. R a52 is an organic group having no group containing active hydrogen that can react with an isocyanate group. However, the unit derived from the (meth)acrylic acid ester represented by the formula (a5-1) is a unit that does not correspond to the aforementioned units (a1), (a2), and (a3). Examples of the group containing active hydrogen include a hydroxyl group, a mercapto group, an amino group, a carboxy group, etc. This organic group may contain a bond or a substituent other than a hydrocarbon group such as a hetero atom in the organic group. Further, the structure of this organic group may be linear, branched, cyclic, or any combination of these structures.

[0079] R a52 The substituent other than the hydrocarbon group in the organic group of is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include a halogen atom, an alkylthio group, an arylthio group, a cyano group, a silyl group, an alkoxy group, an alkoxycarbonyl group, a nitro group, a nitroso group, an acyl group, an acyloxy group, an alkoxyalkyl group, an alkylthioalkyl group, an aryloxyalkyl group, an arylthioalkyl group, an N,N-disubstituted amino group (-NRR’: R and R’ each independently represent a hydrocarbon group), etc. The hydrogen atom contained in the above substituent may be substituted by a hydrocarbon group. Further, the structure of the hydrocarbon group contained in the above substituent may be linear, branched, cyclic, or any combination of these structures.

[0080] R a52As the group, an aryl group, an aralkyl group, or a heterocyclic group is preferable. These groups may be substituted with a halogen atom, an alkyl group, or a heterocyclic group. Further, when these groups contain an alkylene moiety, the alkylene moiety may be interrupted by an ether bond, a thioether bond, or an ester bond.

[0081] R a52 When R is an aryl group, preferable examples of the aryl group include a phenyl group, a naphthalen-1-yl group, a naphthalen-2-yl group, a 4-phenylphenyl group, a 3-phenylphenyl group, and a 2-phenylphenyl group.

[0082] R a52 When R is an alicyclic group or a group containing an alicyclic group, preferable alicyclic groups include monocyclic alicyclic groups such as a cyclopentyl group and a cyclohexyl group, and polycyclic alicyclic groups such as an adamantyl group, a norbornyl group, an isobornyl group, a tricyclononyl group, a tricyclodecyl group, and a tetracyclododecyl group.

[0083] Examples of the monomer other than the above (meth)acrylic acid ester that gives unit (a5) include allyl compounds, vinyl ethers, vinyl esters, styrenes, and the like. These monomers can be used alone or in combination of two or more.

[0084] 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.

[0085] Examples of vinyl ethers include alkyl vinyl ethers such as 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, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, and tetrahydrofurfuryl vinyl ether; vinyl aryl ethers such as vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4-dichlorophenyl ether, vinyl naphthyl ether, and vinyl anthranil ether; and the like.

[0086] Examples of vinyl esters include vinyl butyrate, vinyl isobutyrate, vinyl trimethylacetate, vinyl diethylacetate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxyacetate, vinyl phenylacetate, vinyl acetoacetate, vinyl lactate, vinyl-β-phenylbutyrate, vinyl benzoate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate, and the like.

[0087] Examples of styrenes include styrene; alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, and acetoxymethylstyrene; alkoxystyrenes such as methoxystyrene, 4-methoxy-3-methylstyrene, and dimethoxystyrene; halostyrenes such as chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, and 4-fluoro-3-trifluoromethylstyrene; and the like.

[0088] In the resin (A), the content of the other unit (a5) is not particularly limited as long as the desired effect is not impaired. The total of the molar ratio of the unit (a1), the molar ratio of the unit (a2), and the molar ratio of the unit (a3) to all the constituent units of the resin (A) is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Therefore, the molar ratio of the unit (a5) to all the constituent units of the resin (A) is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 30 mol% or less, even more preferably 20 mol% or less, and particularly preferably 10 mol% or less.

[0089] In the resin (A) described above, the ratio of the number of moles of the ester-containing unit (a1) to the total number of moles of all the constituent units of the resin (A) is 15 mol% or more, the ratio of the number of moles of the hydroxyl group-donating unit (a2) to the total number of moles of all the constituent units of the resin (A) is 5 mol% or more, the ratio of the number of moles of the block isocyanate group-containing unit (a3) to the total number of moles of all the constituent units of the resin (A) is 5 mol% or more, It is particularly preferable that the total ratio of the number of moles of the ester-containing unit (a1), the number of moles of the hydroxyl group-donating unit (a2), and the number of moles of the block isocyanate group-containing unit (a3) to the number of moles of all the constituent units of the resin (A) is 70 mol% or more.

[0090] The weight average molecular weight of the resin (A) is preferably 3000 or more and 100000 or less, more preferably 5000 or more and 80000 or less, and particularly preferably 7000 or more and 60000 or less. The weight average molecular weight is the molecular weight in terms of polystyrene measured by GPC. When the weight average molecular weight of the resin (A) is somewhat large, it is easy to form a cured product excellent in solvent resistance and thermal decomposition resistance. The dispersity of the resin (A) is preferably 1.5 or more and 6.0 or less, more preferably 2.0 or more and 5.0 or less. The dispersity is the value of the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn.

[0091] <Hollow particles (B)> In terms of easily forming a cured product having a low refractive index, the curable composition may contain hollow particles (B). The hollow particles (B) are composed of a shell and a pore surrounded by the shell. The material of the shell is not particularly limited and may be an organic material such as a resin or an inorganic material such as magnesium fluoride or silica. From the viewpoints of easy availability and easy formation of a cured product having a low refractive index, hollow silica particles (B1) and hollow resin particles (B2) are preferable as the hollow particles (B), and hollow silica particles (B1) are more preferable.

[0092] 〔Hollow silica particles (B1)〕 As the hollow silica particles (B1), conventionally known hollow silica particles can be used without particular limitation. The hollow silica particles (B1) may be commercially available products or synthetic products. The hollow silica particles (B1) can be selected and used from known hollow silica in consideration of the particle diameter and refractive index.

[0093] 〔Hollow resin particles (B2)〕 The hollow resin particles (B2) are particles composed of a resin shell and voids surrounded by the shell. The shell may be a single layer or multiple layers. When the shell is multiple layers, each layer may be composed of a different resin.

[0094] Examples of the hollow resin particles (B2) include polyester particles obtained by suspension polymerization of a water-in-oil-in-water emulsion; acrylic particles; styrene-acrylic hollow latex obtained by a seed polymerization method; vinylidene chloride-acrylonitrile-based or acrylonitrile-based thermally expandable microcapsules, etc. Note that the hollow particles preferably have a crosslinked structure. Commercially available hollow resin particles (B2) can also be used. As commercially available products of the hollow resin particles (B2), Tech Polymer (registered trademark) NH (Sekisui Chemical Co., Ltd.) etc. can be used.

[0095] The refractive index of the hollow particles (B) is significantly lower than that of ordinary silica with a refractive index of 1.46. This is because the hollow particles (B) contain air with a low refractive index of 1.0 inside. Therefore, by using a curable composition containing the hollow particles (B), a cured film with a low refractive index can be formed. As the refractive index of the hollow particles (B), typically 1.1 or more and 1.4 or less is preferable, and 1.1 or more and 1.35 or less is more preferable. Also, the hollowness ratio of the hollow particles (B) is preferably 10 to 95%, and more preferably 20 to 50%.

[0096] The volume average particle diameter of the hollow particles (B) is preferably 20 or more and 300 nm or less, more preferably 30 nm or more and 120 nm or less, and even more preferably 50 nm or more and 150 nm or less.

[0097] The content of the hollow particles (B) in the curable composition is not particularly limited as long as the desired effect is not impaired. From the viewpoint of easily forming a cured product with a low refractive index, the content of the hollow particles (B) in the curable composition is preferably 5 parts by mass or more and 2000 parts by mass or less, more preferably 10 parts by mass or more and 1500 parts by mass or less, based on 100 parts by mass of the resin (A).

[0098] <Colorant (C)> As described above, the curable composition may contain a colorant (C). The content of the colorant in the curable composition is less than 50% by mass, preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 0% by mass, based on the total mass of the components other than the solvent (S) of the curable composition. That is, it is most preferable that the curable composition does not contain the colorant (C).

[0099] The colorant (C) may be an organic colorant or an inorganic colorant. As the colorant (C), either a dye or a pigment can be used. As the colorant (C), a pigment is preferred. The hue of the colorant (C) is not particularly limited and is appropriately selected in consideration of the use of the cured product.

[0100] <Solvent (S)> The curable composition contains a solvent (S) for the purpose of adjusting coatability, viscosity, etc. Typically, an organic solvent is used as the solvent (S). The type of the organic solvent is not particularly limited as long as the components contained in the curable composition can be uniformly dissolved or dispersed.

[0101] Specific examples of the solvent (S) include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; (poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; other ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and tetrahydrofuran; ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone; and alkyl lactates such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate.Other esters such as ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl formate, isopentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl 2-oxobutanoate; aromatic hydrocarbons such as toluene and xylene; nitrogen-containing polar organic solvents such as N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N,N’,N’-tetramethylurea, etc.

[0102] Among these, (poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate; other ethers such as propylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, tetrahydrofuran; ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, 3-heptanone; other esters such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl formate, isopentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl 2-oxobutanoate; aromatic hydrocarbons such as toluene, xylene; nitrogen-containing polar organic solvents such as N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N,N',N'-tetramethylurea are preferred.

[0103] The solvent (S) can be used alone or in combination of two or more.

[0104] The amount of the solvent (S) used is not particularly limited as long as the desired effect is not impaired. From the viewpoint of film-forming properties, the solvent (S) is used such that the solid content concentration of the curable composition is preferably 1% by mass or more and 99% by mass or less, more preferably 1% by mass or more and 50% by mass or less, and still more preferably 5% by mass or more and 30% by mass or less.

[0105] <Other component (E)> The curable composition may contain various additives as other components (E) other than the components described above, if necessary. Examples of such additives include stabilizers, adhesion enhancers, crosslinking agents, curing accelerators, surfactants, antioxidants, adhesion aids, defoaming agents, polymerization inhibitors such as thermal polymerization inhibitors, and the like. These additives may be used alone or in combination of two or more.

[0106] The amount of these additives used is not particularly limited as long as the desired effect is not impaired. The amount of these additives used is appropriately determined in consideration of the amount of these additives used in conventionally known curable compositions.

[0107] 〔Manufacturing method of curable composition〕 The curable composition is obtained by mixing the components described above in predetermined amounts and then stirring the mixture uniformly.

[0108] <Resin> The resin is a resin that contains an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3), and does not contain an acidic group-containing unit (a4). The ester-containing unit (a1) has an ester group represented by the following formula (A1). -CO-O-R (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.) The ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3). The ratio of the number of moles of the blocked isocyanate group-containing unit (a3) to the total number of moles of all the constituent units of the resin (A) is 15 mol% or more.

[0109] Regarding the above resin, the ester-containing unit (a1), the hydroxyl group-donating unit (a2), the blocked isocyanate group-containing unit (a3), and the acidic group-containing unit (a4) are the same as those of the resin (A) contained in the curable composition. The above resin may contain other units (a5). The other units (a5) are the same as the other units (a5) that the resin (A) contained in the curable composition has.

[0110] The above resin can be suitably blended as the resin (A) in the aforementioned curable composition.

[0111] ≪Cured product≫ By heating the curable composition described above, a cured product is formed. Such a cured product has high solvent resistance and exhibits a low refractive index. The curing conditions are not particularly limited as long as the curable composition is sufficiently cured. As the curing temperature, for example, 90°C or higher and 250°C or lower is preferable, and 150°C or higher and 250°C or lower is more preferable. As the curing time, for example, 30 seconds or longer and 1 hour or shorter is preferable, and 1 minute or longer and 30 minutes or shorter is more preferable.

[0112] As described above, the present inventors provide the following (1) to (9). (1) A curable composition containing a resin (A) and a solvent (S), and containing or not containing a colorant (C), The resin (A) is dissolved in the solvent (S), The ratio of the mass of the colorant (C) to the total mass of the components other than the solvent (S) of the curable composition is less than 50% by mass, The resin (A) contains an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3), The ester-containing unit (a1) is represented by the following formula (A1): -CO-O-R (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.) has an ester group represented by, The ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3), a curable composition. (2) The curable composition according to (1), further containing hollow particles (B). (3) The curable composition according to (1) or (2), wherein the resin (A) does not contain an acidic group-containing unit (a4). (4) The curable composition according to any one of (1) to (3), wherein in the ester-containing unit (a1), the number of carbon atoms of the aliphatic hydrocarbon group is 1 or more and 6 or less. (5) The block isocyanate group-containing unit (a3) is represented by the following formula (a3-2): -NH-CO-R a34 ···(a3-2) (In the formula (a3-2), R a34 is a lactam ring group. The lactam ring group is a group obtained by removing a hydrogen atom from the nitrogen atom in the lactam ring. The nitrogen atom in the lactam ring is bonded to the carbon atom in the carbonyl group.) The curable composition according to any one of (1) to (4), which has a group represented by the formula. (6) The curable composition according to any one of (1) to (5), wherein the refractive index at a wavelength of 550 nm of a cured film having a thickness of 1 μm formed by heating a coating film composed of the curable composition at 100 °C for 60 seconds and then at 200 °C for 5 minutes is 1.53 or less. (7) The ratio of the number of moles of the ester-containing unit (a1) to the total number of moles of all the constituent units of the resin (A) is 15 mol% or more, the ratio of the number of moles of the hydroxyl group-donating unit (a2) to the total number of moles of all the constituent units of the resin (A) is 5 mol% or more, the ratio of the number of moles of the block isocyanate group-containing unit (a3) to the total number of moles of all the constituent units of the resin (A) is 5 mol% or more, The curable composition according to any one of (1) to (6), wherein the total ratio of the number of moles of the ester-containing unit (a1), the number of moles of the hydroxyl group-donating unit (a2), and the number of moles of the block isocyanate group-containing unit (a3) to the total number of moles of all the constituent units of the resin (A) is 70 mol% or more. (8) A resin containing an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a block isocyanate group-containing unit (a3), and not containing an acidic group-containing unit (a4), wherein the ester-containing unit (a1) is represented by the following formula (A1): -CO-O-R (A1) (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.) having an ester group represented by The ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3). A resin in which the ratio of the number of moles of the blocked isocyanate group-containing unit (a3) to the number of moles of all the constituent units of the resin (A) is 15 mol% or more. (9) A cured product of the curable composition according to any one of (1) to (7).

Examples

[0113] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to these Examples.

[0114] Hereinafter, in Examples and Comparative Examples, resins composed of the units described in Tables 1 to 3 were used. The weight average molecular weight (Mw) and the dispersity (weight average molecular weight Mw / number average molecular weight Mn) of the resins used in Examples and Comparative Examples are shown in Tables 1 to 3. The units described in Tables 1 to 3 are as follows.

[0115] <Ester-containing unit (a1)>

Chemical formula

[0116] <Hydroxyl group-donating unit (a2)>

Chemical formula

[0117] <Blocked isocyanate group-containing unit (a3)>

Chemical formula

[0118] <Acidic group-containing unit (a4)>

Chem.

[0119] <Other units (a5)>

Chem.

[0120] <Hollow particles (B)> In Examples and Comparative Examples, the following hollow particles b-1 and b-2 were used. b-1: Hollow silica particles with a volume-average particle diameter of 60 nm. b-2: Hollow particles with a resin shell and a volume-average particle diameter of 65 nm.

[0121] 〔Examples 1 to 22 and Comparative Examples 1 to 4〕 100 parts by mass of the resin described in Table 1 and 0.1 part by mass of a surfactant were dissolved in a solvent so that the solid content concentration was 20% by mass to obtain the curable compositions of Examples 1 to 21 and Comparative Examples 1 to 4. As the solvent, a mixed solvent composed of 70% by mass of propylene glycol monomethyl ether and 30% by mass of propylene glycol monomethyl ether acetate was used. As the surfactant, a siloxane-based surfactant (polyester-modified polydimethylsiloxane, BYK-310, manufactured by BYK-Chemie) was used.

[0122] Using the obtained curable compositions of Examples 1 to 22 and Comparative Examples 1 to 4, evaluations of the chemical resistance of the cured product, the refractive index of the cured product, and the temporal stability of the curable composition were carried out according to the following methods. These evaluation results are shown in Table 1.

[0123] 〔Chemical resistance evaluation〕 The curable composition was applied on a silicon substrate with a spin coater to form a coating film. After heating the coating film at 100 °C for 60 seconds, it was heated at 200 °C for 5 minutes to obtain a cured film. Next, the formed cured film was immersed in acetone, propylene glycol monomethyl ether acetate (PGMEA), and an aqueous solution of tetramethylammonium hydroxide (TMAH) with a concentration of 2.38% by mass for 10 minutes each at room temperature. After immersion, the surface of the cured film was rinsed with pure water for 30 seconds. After rinsing, the cured film was dried. The film thickness T1 of the cured film before immersion and the film thickness T2 of the cured film after immersion were measured respectively, and the residual film ratio was calculated by the following formula. Based on the calculated value of the residual film ratio, the chemical resistance was evaluated according to the following criteria. When the evaluation is A, B, or C, the chemical resistance is good. Residual film ratio (%) = T2 / T1 × 100 (Evaluation criteria) A: The residual film ratio is 99% or more and 103% or less. B: The residual film ratio is 95% or more and less than 99%, or more than 103% and 105% or less. C: The residual film ratio is 90% or more and less than 95%, or more than 105% and 110% or less D: The residual film ratio is less than 90%, or more than 110%

[0124] [Refractive index evaluation] The curable composition was applied on a silicon substrate with a spin coater to form a coating film. After heating the coating film at 100 °C for 60 seconds, it was heated at 200 °C for 5 minutes to obtain a cured film. The refractive index of the obtained cured film at a light wavelength of 550 nm was measured using a rotating compensator type high-speed spectroscopic ellipsometer (M-2000, manufactured by J. A. Woolam Japan Co., Ltd.). Based on the measured value of the refractive index, the refractive index was evaluated according to the following criteria. When the evaluation is A, B, or C, the refractive index is sufficiently low. A: The refractive index is 1.51 or less. B: The refractive index is more than 1.51 and 1.52 or less. C: The refractive index is more than 1.52 and 1.53 or less. D: The refractive index is more than 1.53.

[0125] [Evaluation of stability over time] The viscosity V1 of the obtained curable composition was measured using a Canon Fenske viscometer. After storing the obtained cured composition at 40 °C for 2 weeks, the viscosity V2 of the curable composition was measured using a Canon Fenske viscometer. Based on the values of V1 and V2, the viscosity increase rate (%) was calculated according to the following formula. Viscosity increase rate (%) = V2 / V1 × 100 - 100 Based on the calculated value of the viscosity increase rate, the stability over time of the curable composition was evaluated according to the following criteria. When the evaluation is A or B, the stability over time is good. A: Viscosity increase rate less than 5% B: Viscosity increase rate of 5% or more and less than 10% C: Viscosity increase rate of 10% or more and less than 15% D: Viscosity increase rate of 15% or more

[0126]

Table 1

[0127] 〔Examples 23 to 72, and Comparative Examples 5 to 12〕 100 parts by mass of the resin described in Table 2 or Table 3, the hollow particles of the type and amount described in Table 2 or Table 3, and 0.1 part by mass of a surfactant were dissolved and dispersed in a solvent so that the solid content concentration was 20% by mass to obtain the curable compositions of Examples 23 to 72 and Comparative Examples 5 to 10. As the solvent, a mixed solvent composed of 70% by mass of propylene glycol monomethyl ether and 30% by mass of propylene glycol monomethyl ether acetate was used. As the surfactant, a siloxane-based surfactant (polyester-modified polydimethylsiloxane, BYK-310, manufactured by BYK-Chemie) was used.

[0128] Using the obtained curable compositions of Examples 23 to 72 and Comparative Examples 5 to 12, in the same manner as in Example 1, the evaluation of the chemical resistance of the cured product, the evaluation of the refractive index of the cured product, and the evaluation of the stability over time of the curable composition were carried out. However, the refractive index was evaluated based on the following criteria. When the evaluation is A, B, or C, the refractive index is sufficiently low. These evaluation results are shown in Table 2 and Table 3. (Refractive Index Evaluation Criteria) A: The refractive index is 1.39 or less. B: The refractive index is more than 1.39 and 1.41 or less. C: The refractive index is more than 1.41 and 1.43 or less. D: The refractive index is more than 1.43.

Table 2

[0129]

Table 3

[0130] According to Tables 1 to 3, it can be seen that the curable composition containing the resin (A) including the aforementioned units (a1), (a2), and (a3) and the solvent (S) is excellent in chemical resistance, gives a cured product with a low refractive index, and is excellent in stability over time. On the other hand, the curable composition of the comparative example containing a resin not including the aforementioned units (a1), (a2), and (a3) was inferior in any one or more of chemical resistance, low refractive property of the cured product, and stability over time.

Claims

1. A curable composition comprising a resin (A) and a solvent (S), and containing or not containing a colorant (C), wherein the resin (A) is dissolved in the solvent (S), the ratio of the mass of the colorant (C) to the total mass of the components other than the solvent (S) of the curable composition is less than 50% by mass, the resin (A) contains an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3), the ester-containing unit (a1) is represented by the following formula (A1): -CO-O-R (A1) (wherein R is an aliphatic hydrocarbon group which may have a substituent). having an ester group represented by, the ester-containing unit (a1) is a unit that does not correspond to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3), a curable composition.

2. The curable composition according to claim 1, further comprising hollow particles (B).

3. The curable composition according to claim 1 or 2, wherein the resin (A) does not contain an acidic group-containing unit (a4).

4. The curable composition according to claim 1 or 2, wherein in the ester-containing unit (a1), the number of carbon atoms of the aliphatic hydrocarbon group is 1 or more and 6 or less.

5. The blocked isocyanate group-containing unit (a3) is represented by the following formula (a3-2): -NH-CO-R ａ３４ ...(a3-2) (in formula (a3-2), R ａ３４ is a lactam ring group. The lactam ring group is a group obtained by removing a hydrogen atom from the nitrogen atom in the lactam ring. The nitrogen atom in the lactam ring is bonded to the carbon atom in the carbonyl group.). The curable composition according to claim 1 or 2, having a group represented by.

6. The curable composition according to claim 1 or 2, wherein a refractive index of a cured film having a thickness of 1 μm formed by heating a coating film made of the curable composition at 100° C. for 60 seconds and then at 200° C. for 5 minutes is 1.53 or less at a wavelength of 550 nm.

7. A ratio of the number of moles of the ester-containing unit (a1) to the number of moles of all constitutional units of the resin (A) is 15 mol % or more, a ratio of the number of moles of the hydroxyl group-donating unit (a2) to the number of moles of all constitutional units of the resin (A) is 5 mol % or more, a ratio of the number of moles of the blocked isocyanate group-containing unit (a3) to the number of moles of all constitutional units of the resin (A) is 5 mol % or more, The curable composition according to claim 1 or 2, wherein a ratio of the total number of moles of the ester-containing unit (a1), the number of moles of the hydroxyl group-donating unit (a2), and the number of moles of the blocked isocyanate group-containing unit (a3) to the number of moles of all constitutional units of the resin (A) is 70 mol % or more.

8. A resin containing an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3), and not containing an acidic group-containing unit (a4), wherein the ester-containing unit (a1) has an ester group represented by the following formula (A1): —CO—O—R (A1) (wherein R is an aliphatic hydrocarbon group which may have a substituent), and the ester-containing unit (a1) is a unit not corresponding to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3), and a ratio of the number of moles of the blocked isocyanate group-containing unit (a3) to the number of moles of all constitutional units of the resin (A) is 15 mol % or more. The resin.

9. A cured product of the curable composition according to claim 1 or 2.

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