Curable composition, resin, and cured product

Abstract

The invention relates to a curable composition, a resin and a cured product. The present invention addresses the problem of providing: a curable composition which is capable of providing a cured product having high solvent resistance and a low refractive index and which has excellent stability over time; a resin which can be suitably incorporated into the curable composition; and a cured product of the curable composition. In 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), and the ratio of the mass of the colorant (C) to the total mass of the components of the curable composition other than the solvent (S) is less than 50 mass%. A resin containing an ester-containing unit (a1), a hydroxyl group-donating unit (a2), and a blocked isocyanate group-containing unit (a3) is used as the resin (A).

Description

Technical Field

[0001] The present invention relates to a curable composition containing a resin having a structural unit including a specific structure, a resin that can be suitably blended in the curable composition, and a cured product of the curable composition. Background Art

[0002] Conventionally, as resin materials, materials having an appropriately adjusted refractive index are known, and such materials are used in the optical field and the like. As a composition for forming a low-refractive-index material, for example, a curable resin composition has been proposed, which contains a (meth)acrylic resin, hollow resin particles having a specific particle size, and an organic solvent, and the (meth)acrylic resin contains a structural unit having an epoxy group and a structural unit having a hydrocarbon group substituted with a hydroxyl group (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.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-8550 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The curable composition described in Patent Document 1 is cured 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 prone to thickening over time.

[0008] The present invention has been made in view of such circumstances, and an object thereof is to provide a curable composition that can provide a cured product having high solvent resistance and a low refractive index and excellent stability over time, a resin that can be suitably blended in the curable composition, and a cured product of the curable composition.

[0009] Means for Solving the Problems

[0010] The inventors of the present application have found that by dissolving the resin (A) in the solvent (S) in a curable composition containing the resin (A) and the solvent (S) and containing or not containing the colorant (C), and making the ratio of the mass of the colorant (C) to the total mass of the components of the curable composition other than the solvent (S) less than 50% by mass, and using a resin containing an ester unit (a1), a hydroxyl group-providing unit (a2), and a unit containing a blocked isocyanate group as the resin (A), the above problems can be solved, and thus the present invention has been completed. Specifically, the present invention provides the following.

[0011] A first aspect of the present invention is a curable composition, which contains a resin (A) and a solvent (S), and may or may not contain a colorant (C).

[0012] The resin (A) is dissolved in the solvent (S).

[0013] The mass ratio of the colorant (C) is less than 50% by mass with respect to the total mass of the components other than the solvent (S) in the curable composition.

[0014] The resin (A) contains an ester-containing unit (a1), a hydroxyl group-providing unit (a2), and a blocked isocyanate group-containing unit (a3).

[0015] The ester-containing unit (a1) has an ester group represented by the following formula (A1).

[0016] -CO-O-R(A1)

[0017] (In the formula, R is an aliphatic hydrocarbon group which may have a substituent, or a trialkylsilyl group.)

[0018] The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-providing unit (a2) and the blocked isocyanate group-containing unit (a3).

[0019] A second aspect of the present invention is a resin, which contains an ester-containing unit (a1), a hydroxyl group-providing unit (a2), and a blocked isocyanate group-containing unit (a3), and does not contain an acidic group-containing unit (a4).

[0020] The ester-containing unit (a1) has an ester group represented by the following formula (A1).

[0021] -CO-O-R(A1)

[0022] (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.)

[0023] The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-providing unit (a2) and the blocked isocyanate group-containing unit (a3).

[0024] The molar ratio of the blocked isocyanate group-containing unit (a3) is 15 mol% or more with respect to the total number of moles of all the structural units of the resin (A).

[0025] A third aspect of the present invention is a cured product of the curable composition according to the first aspect.

[0026] Advantages of the Invention

[0027] According to the present invention, there can be provided a curable composition that can supply a cured product having high solvent resistance and a low refractive index and has excellent stability over time, a resin that can be suitably incorporated into the curable composition, and a cured product of the curable composition. Detailed Description of Embodiments

[0028] <<Curable Composition>>

[0029] The curable composition contains a resin (A) and a solvent (S), and may or may not contain a colorant (C).

[0030] The resin (A) is dissolved in the solvent (S).

[0031] The resin (A) contains an ester-containing unit (a1), a hydroxyl group-providing unit (a2), and a blocked isocyanate group-containing unit (a3).

[0032] The ester-containing unit (a1) has an ester group represented by the following formula (A1).

[0033] -CO-O-R(A1)

[0034] (In the formula, R is an aliphatic hydrocarbon group that may have a substituent.)

[0035] The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-providing unit (a2) and the blocked isocyanate group-containing unit (a3).

[0036] The curable composition can supply a cured product having a low refractive index. Therefore, the cured product of the curable composition can be suitably used as an optical material. Therefore, the curable composition does not contain a large amount of the colorant (C). Specifically, the mass ratio of the colorant (C) is less than 50% by mass relative to the total mass of the components other than the solvent (S) in the curable composition.

[0037] Specifically, 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 formed from the curable composition at 100°C for 60 seconds and then heating at 200°C for 5 minutes is preferably 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 below in the curable composition.

[0038] Hereinafter, the essential or optional components that can be contained in the curable composition will be described.

[0039] <<Resin (A)>>

[0040] The resin (A) contains an ester-containing unit (a1), a hydroxyl group-providing unit (a2), and a blocked isocyanate group-containing unit (a3).

[0041] Hereinafter, the "ester-containing unit (a1)" will also be referred to as "unit (a1)". The "hydroxyl group-providing unit (a2)" will also be referred to as "unit (a2)". The "unit (a3) containing a blocked isocyanate group" will also be referred to as "unit (a3)".

[0042] In addition, in the specification of the present application, a "unit" means a "structural unit".

[0043] In addition, in the resin (A), within the range not impairing the desired purpose, it may contain a unit (a4) containing an acidic group and other units (a5) in addition to the unit (a1), the unit (a2), and the unit (a3).

[0044] These units may be present in the resin in a block form or randomly. From the aspect of the reactivity of the resin (A), each unit constituting the resin (A) is preferably randomly present in the resin (A).

[0045] [Ester-containing unit (a1)]

[0046] The ester-containing unit (a1) has an ester group represented by the following formula (A1).

[0047] -CO-O-R(A1)

[0048] (In the formula, R is an aliphatic hydrocarbon group which may have a substituent, or a trialkylsilyl group.)

[0049] The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-providing unit (a2), the unit (a3) containing a blocked isocyanate group, the unit (a4) containing an acidic group, and other units (a5).

[0050] 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.

[0051] In addition, from the aspect of the stability of the curable composition, when the aliphatic hydrocarbon group as R has a tertiary carbon atom, it is preferred 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.

[0052] 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. Typically, the number of substituents is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or 2.

[0053] 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 ), imido group (-N(-CO-R A2 ) 2 ), a cyano group, an alkylthio group, an aliphatic acylthio group, and a thiol group.

[0054] Regarding the amide group, R A1 is a hydrogen atom or an aliphatic hydrocarbon group. A1 The aliphatic hydrocarbon group is preferably an alkyl group having 1 to 6 carbon atoms. A2 is an aliphatic hydrocarbon group. A1 They may be the same or different. In the imide group, two R A2 The aliphatic hydrocarbon groups may be bonded to each other to form a ring. A2 The aliphatic hydrocarbon group is preferably an alkyl group having 1 to 6 carbon atoms. A 2 When the aliphatic hydrocarbon groups of are bonded to each other to form a ring, examples of the imide group include a succinimide group and a maleimide group. A2 They can be the same as each other or different.

[0055] The alkoxy group as a substituent is preferably an alkoxy group having a carbon number of 1 to 4. Specific examples of the alkoxy group include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, isobutyloxy, sec-butyloxy, and tert-butyloxy.

[0056] The aliphatic acyl group as a substituent is preferably an aliphatic acyl group having a carbon number of 2 or more and 4 or less. Specific examples of the aliphatic acyl group include an acetyl group, a propionyl group, and a butyryl group.

[0057] The aliphatic acyloxy group as a substituent is preferably an aliphatic acyloxy group having a carbon number of 2 or more and 4 or less. Specific examples of the aliphatic acyloxy group include an acetyloxy group, a propionyloxy group, and a butyryloxy group.

[0058] Examples of the halogen atom as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0059] Specific examples of the amide group include carbamoyl (—CO—NH 2 ), N-methylcarbamoyl, N-ethylcarbamoyl, N,N-dimethylcarbamoyl, and N,N-diethylcarbamoyl.

[0060] As specific examples of the imide group, N,N-diacetylamino, N,N-dipropionylamino, succinimido, and maleimido can be mentioned.

[0061] Regarding the alkylthio group as a substituent, an alkylthio group having 1 to 4 carbon atoms is preferred. As specific examples of the alkylthio group, methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, isobutylthio, sec-butylthio, and tert-butylthio can be mentioned.

[0062] Regarding the aliphatic acylthio group as a substituent, an aliphatic acylthio group having 2 to 4 carbon atoms is preferred. As specific examples of the aliphatic acylthio group, acetylthio, propionylthio, and butyrylthio can be mentioned.

[0063] 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 preferred, and an alkoxy group, an aliphatic acyl group, an aliphatic acyloxy group, a halogen atom, an amide group, and an imide group are more preferred.

[0064] The number of carbon atoms of the aliphatic hydrocarbon group as R in the 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. It should be noted that the number of carbon atoms described above does not include the carbon atoms of the substituent.

[0065] As preferred specific examples of the linear aliphatic hydrocarbon group as R, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, sec-pentyl, tert-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosyl can be mentioned.

[0066] As preferred specific examples of the cyclic aliphatic hydrocarbon group as R, cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; polycyclic alkyl groups such as adamantyl, norbornyl, isobornyl, tricyclodecyl, and tetracyclodecyl. The polycyclic alkyl group is a group obtained by removing one hydrogen atom from a polycyclic alkane.

[0067] Preferable specific examples of the group formed from 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, 1-ethylcyclopentan-1-yl, 1-n-propylcyclopentan-1-yl, 1-isopropylcyclopentan-1-yl, and 1-n-butylcyclopentan-1-yl; 1-alkylcyclohexan-1-yl groups such as 1-methylcyclohexan-1-yl, 1-ethylcyclohexan-1-yl, 1-n-propylcyclohexan-1-yl, 1-isopropylcyclohexan-1-yl, and 1-n-butylcyclohexan-1-yl; 1-alkylcycloheptan-1-yl groups such as 1-methylcycloheptan-1-yl, 1-ethylcycloheptan-1-yl, 1-n-propylcycloheptan-1-yl, 1-isopropylcycloheptan-1-yl, and 1-n-butylcycloheptan-1-yl; 1-alkylcyclooctan-1-yl groups such as 1-methylcyclooctan-1-yl, 1-ethylcyclooctan-1-yl, 1-n-propylcyclooctan-1-yl, 1-isopropylcyclooctan-1-yl, and 1-n-butylcyclooctan-1-yl; 2-alkyladamantan-2-yl groups such as 2-methyladamantan-2-yl, 2-ethyladamantan-2-yl, 2-n-propyladamantan-2-yl, 2-isopropyladamantan-2-yl, and 2-n-butyladamantan-2-yl; and 2-alkylnorbornan-2-yl groups such as 2-methylnorbornan-2-yl, 2-ethylnorbornan-2-yl, 2-n-propylnorbornan-2-yl, 2-isopropylnorbornan-2-yl, and 2-n-butylnorbornan-2-yl.

[0068] R in formula (A1) may also 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.

[0069] Preferable specific examples of the trialkylsilyl group include trimethylsilyl, triethylsilyl, tri-n-propylsilyl, triisopropylsilyl, and tri-n-butylsilyl.

[0070] The type of the resin (A) is not particularly limited, but an acrylic resin is preferred in view of easy availability, preparation of the monomer and the resin (A), and easy formation of a cured product having a low refractive index. The acrylic resin is a polymer of a monomer containing (meth)acrylic acid and / or a (meth)acrylic acid derivative.

[0071] 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 formula (A1-1), R is the same as R in formula (A1). R 11 is a hydrogen atom or a methyl group.

[0072] CH=CR 11 -CO-O-R(A1-1)

[0073] The (meth)acrylate as the supply unit (a1) is preferably a (meth)acrylate in which the hydrocarbon group as R is any one of the preferred specific examples of a linear aliphatic hydrocarbon group, the preferred specific examples of a cyclic aliphatic hydrocarbon group, or the preferred specific examples of a group formed from a linear aliphatic hydrocarbon group and a cyclic aliphatic hydrocarbon group.

[0074] As the (meth)acrylate, preferred are 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.

[0075] The ratio of the molar number of the unit (a1) to the molar number of all the structural units of the resin (A) is not particularly limited within the range that does not impair the desired effect. Relative to the molar number of all the structural units of the resin (A), the ratio of the molar number of the unit (a1) 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.

[0076] [Hydroxyl group-providing unit (a2)]

[0077] The hydroxyl group-providing unit (a2) has a hydroxyl group or can generate a hydroxyl group through a chemical reaction based on the action of light or heat. It should be noted that in the specification of the present application, the hydroxyl group possessed or generated by the hydroxyl group-providing unit (a2) is defined as a group that is an alcoholic hydroxyl group or a phenolic hydroxyl group and is bonded to a carbon atom. Therefore, a carboxyl group, a silanol group, etc. do not belong to the hydroxyl group possessed or generated by the hydroxyl group-providing unit (a2).

[0078] When the resin (A) is an acrylic resin, the hydroxyl group-providing unit (a2) is preferably a unit derived from an acrylate having a hydroxyl group.

[0079] For example, a lactone ring such as a γ-butyrolactone ring can be ring-opened through a chemical reaction based on the action of light or heat to generate a hydroxyl group.

[0080] When the resin (A) is an acrylic resin, as the unit (a2), preferred is the unit represented by the following formula (a2-1).

[0081] [Chemical Formula 1]

[0082]

[0083] (In formula (a2-1), R a21 is a hydrogen atom or a methyl group, and R a22 is an organic group having a hydroxyl group or a lactone ring group.)

[0084] When R a22 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. As for the number of hydroxyl groups in the organic group having a hydroxyl group of R a22 , there is no particular limitation as long as the desired effect is not impaired. Typically, the number of hydroxyl groups in the organic group having a hydroxyl group of R a22 is preferably 1 or more and 4 or less, more preferably 1 or 2, and still more preferably 1.

[0085] As R a22 , it is preferably a hydrocarbon group substituted by 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 preferred. 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 preferred.

[0086] When R a22 is a hydrocarbon group substituted by a hydroxyl group, the number of carbon atoms of the hydrocarbon group substituted by 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 by 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.

[0087] When the hydrocarbon group in the hydrocarbon group substituted by 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 of the hydrocarbon group substituted by a hydroxyl group is preferably 6 or more and 20 or less, more preferably 6 or more and 12 or less.

[0088] Specific examples of the aliphatic hydrocarbon group substituted with a hydroxyl group include hydroxymethyl, 2-hydroxyethyl, 1-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 1-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 7-hydroxyheptyl, 8-hydroxyoctyl, 9-hydroxynonyl, 10-hydroxydecyl, 11-hydroxyundecyl, 12-hydroxydodecyl, 13-hydroxytridecyl, 14-hydroxytetradecyl, 15-hydroxypentadecyl, 16-hydroxyhexadecyl, 17-hydroxyheptadecyl, 18-hydroxyoctadecyl, 19-hydroxynonadecyl, and 20-hydroxyeicosyl.

[0089] Among them, hydroxymethyl, 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 7-hydroxyheptyl, 8-hydroxyoctyl, 9-hydroxynonyl, 10-hydroxydecyl, 11-hydroxyundecyl, 12-hydroxydodecyl, 13-hydroxytridecyl, 14-hydroxytetradecyl, 15-hydroxypentadecyl, 16-hydroxyhexadecyl, 17-hydroxyheptadecyl, 18-hydroxyoctadecyl, 19-hydroxynonadecyl, and 20-hydroxyeicosyl are preferred.

[0090] Among them, hydroxymethyl, 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 7-hydroxyheptyl, 8-hydroxyoctyl, 9-hydroxynonyl, and 10-hydroxydecyl are more preferred.

[0091] Among them, 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, and 6-hydroxyhexyl are further preferred.

[0092] Specific examples of the aromatic hydrocarbon group substituted with a hydroxyl group include 4-hydroxyphenyl, 3-hydroxyphenyl, 2-hydroxyphenyl, 4-hydroxynaphthalen-1-yl, 6-hydroxynaphthalen-2-yl, and 7-hydroxynaphthalen-2-yl.

[0093] Among them, 4-hydroxyphenyl and 3-hydroxyphenyl are preferred, and 4-hydroxyphenyl is more preferred.

[0094] As the lactone ring group, as long as it is a group that can generate a hydroxyl group by hydrolysis, there is no particular limitation. The number of carbon atoms of the lactone ring group is preferably 3 or more and 8 or less, and more preferably 4 or more and 6 or less. The lactone ring group is preferably bonded to the non-carbonyl oxygen atom in the formula (a2-1) at a position adjacent to the carbonyl group in the lactone ring.

[0095] Preferred specific examples of the lactone ring group include 4-oxooxetan-3-yl (propiolactone group), 5-oxotetrahydrofuran-4-yl (butyrolactone group), and 6-oxotetrahydropyran-5-yl (valerolactone group).

[0096] Preferred specific examples of the (meth)acrylate of the unit represented by the supply type (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.

[0097] Among them, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 5-oxotetrahydrofuran-4-yl acrylate, and 5-oxotetrahydrofuran-4-yl methacrylate are preferred.

[0098] The ratio of the molar number of the unit (a2) to the molar number of all the structural units of the resin (A) is not particularly limited as long as the desired effects are not impaired. Relative to the molar number of all the structural units of the resin (A), the ratio of the molar number of the unit (a2) is preferably 5 mol% or more, more preferably 15 mol% or more and 50 mol% or less, and still more preferably 20 mol% or more and 40 mol% or less.

[0099] It should be noted that the molar number M of the unit (a2) in the resin (A) H and the molar number M of the unit (a3) BI The ratio of is preferably 30:70 to 70:30, more preferably 40:60 to 60:40, and still more preferably 45:55 to 55:45 in terms of M H : M BI calculated.

[0100] [Unit (a3) containing a blocked isocyanate group]

[0101] The so-called blocked isocyanate group refers to a group formed by blocking an isocyanate group with a thermally dissociable protecting group. The unit (a3) containing a blocked isocyanate group is a unit having the aforementioned blocked isocyanate group.

[0102] When the resin (A) is an acrylic resin, the unit (a3) containing a blocked isocyanate group 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 preferred.

[0103] [Chemical formula 2]

[0104]

[0105] (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.)

[0106] 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 methylene, ethane-1,2-diyl, ethane-1,1-diyl, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl, and pentane-1,5-diyl, etc.

[0107] Among these groups, methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, and pentane-1,5-diyl are preferred, methylene, ethane-1,2-diyl, and propane-1,3-diyl are more preferred, and ethane-1,2-diyl is particularly preferred.

[0108] In formula (a3-1), R a33 is a blocked isocyanate group. The blocked isocyanate group refers to a group formed by blocking an isocyanate group with a thermally dissociable protecting group.

[0109] Regarding the thermally dissociable protecting group, it can be formed by reacting an isocyanate group with a blocking agent that provides the protecting group.

[0110] As the blocking agent, for example, alcohol compounds, phenolic compounds, compounds containing a hydroxyl group other than alcohol compounds and phenolic compounds, active methylene compounds, amine compounds, imine compounds, oxime compounds, carbamic acid compounds, urea compounds, amide (lactam) compounds, imide compounds, triazole compounds, pyrazole compounds, pyrrole compounds, thiol compounds, and bisulfites, etc. can be cited.

[0111] Examples of the alcohol-based compounds include methanol, ethanol, isopropyl alcohol, n-butanol, sec-butanol, 2-ethylhexanol, 1-octanol, 2-octanol, cyclohexanol, 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-morpholinoethanol, 2,2-dimethyl-1,3-dioxolane-4-methanol, 3-oxazolidineethanol, 2-hydroxymethylpyridine, furfuryl alcohol, 12-hydroxystearic acid, 2-hydroxyethyl methacrylate, and the like.

[0112] As phenolic compounds, for example, 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 product of phenol obtained using α - methylbenzyl), 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 - chloropyridin - 3 - ol, etc.,

[0113] As compounds containing a hydroxyl group other than alcohol - based compounds and phenol - based compounds, for example, N - hydroxysuccinimide and triphenylsilanol can be cited.

[0114] As active methylene - based compounds, for example, 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.

[0115] As amine - based compounds, for example, dibutylamine, diphenylamine, aniline, N - methylaniline, carbazole, bis(2,2,6,6 - tetramethylpiperidyl)amine, di - n - propylamine, diisopropylamine, isopropyl ethylamine, 2,2,4 - trimethylhexamethylenediamine, 2,2,5 - trimethylhexamethylenediamine, 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.

[0116] As imine compounds, for example, ethylenimine, polyethyleneimine, 1,4,5,6-tetrahydropyrimidine, guanidine, etc. can be cited.

[0117] As oxime compounds, for example, 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 isopentyl ketone oxime, n-pentyl ketone oxime, 2,2,4,4-tetramethyl-1,3-cyclobutanedione monoxime, 4,4'-dimethoxybenzophenone oxime, 2-heptanone oxime, etc. can be cited.

[0118] As carbamate compounds, for example, phenyl N-phenylcarbamate, etc. can be cited.

[0119] As urea compounds, for example, urea, thiourea, ethyleneurea, etc. can be cited.

[0120] As amide (lactam) compounds, for example, acetanilide, N-methylacetamide, acetamide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, pyrrolidone, 2,5-piperazinedione, laurolactam, etc. can be cited.

[0121] As imide compounds, for example, succinimide, maleimide, phthalimide, etc. can be cited.

[0122] As triazole compounds, for example, 1,2,4-triazole, benzotriazole, etc. can be cited.

[0123] As pyrazole compounds, for example, 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, etc. can be cited.

[0124] As pyrrole compounds, pyrrole, 2-methylpyrrole, 3-methylpyrrole, 2,4-dimethylpyrrole, etc. can be cited.

[0125] As thiol compounds, for example, n-butyl mercaptan, n-dodecyl mercaptan, n-hexyl mercaptan, benzenethiol, pyridine-2-thiol, etc. can be cited.

[0126] As bisulfite, for example, sodium bisulfite, etc. can be cited.

[0127] Among these capping agents, from the viewpoint of never deactivating the acid generated by the acid generator (B) and obtaining good patterning properties, an amide compound, an alcohol compound, or an oxime compound is preferred. As the amide compound, a lactam compound is preferred.

[0128] As the lactam compound, a compound that provides a group represented by the following formula (a3-2) as R a33 is preferred.

[0129] -NH-CO-R a34 ···(a3-2)

[0130] (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.)

[0131] As the alcohol compound, a compound that provides a group represented by the following formula (a3-3) as R a33 is preferred.

[0132] -NH-CO-R a35 ···(a3-3)

[0133] (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 heteroatom in addition to the oxygen atom of the alkoxy group. Examples of the heteroatom include an oxygen atom, a sulfur atom, and a nitrogen atom.)

[0134] As the oxime compound, a compound that provides a group represented by the following formula (a3-4) as R a33 is preferred.

[0135] -NH-CO-R a36 ···(a3-4)

[0136] (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.)

[0137] The ratio of the number of moles of unit (a3) to the total number of moles of all structural units of resin (A) is not particularly limited as long as the desired effects are not impaired. With respect to the total number of moles of all structural units of resin (A), the ratio of the number of moles of unit (a3) is preferably 5 mol% or more, more preferably 15 mol% or more and 50 mol% or less, and still more preferably 20 mol% or more and 40 mol% or less.

[0138] [Unit (a4) containing an acidic group]

[0139] Resin (A) may contain unit (a4) containing an acidic group, as long as the desired effect is not impaired. Resin (A) preferably does not contain unit (a4) containing an acidic group. However, unit (a4) containing an acidic group does not belong to the hydroxyl group-providing unit (a2). Unit (a4) containing an acidic group is also referred to as unit (a4).

[0140] Typically, the acidic group possessed by unit (a4) containing an acidic group is a protonic acidic group. Examples of the protonic acidic group include a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a phosphinic acid group.

[0141] When resin (A) is an acrylic resin, unit (a4) containing an acidic group is a unit derived from an unsaturated compound having an acidic group. Unit (a4) containing an acidic group is preferably a unit derived from unsaturated carboxylic acids.

[0142] 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 them, (meth)acrylic acid is preferred.

[0143] [Other unit (a5)]

[0144] In resin (A), within the range not impairing the desired effect, other units (a5) may be contained in addition to the aforementioned units (a1), unit (a2), unit (a3), and unit (a4).

[0145] When resin (A) is an acrylic resin, examples of other unit (a5) include units derived from (meth)acrylate. Among them, as the unit (meth)acrylate, a compound represented by the following formula (a5-1) is preferred.

[0146] [Chemical formula 3]

[0147]

[0148] In the above formula (a5-1), R a51 is a hydrogen atom or a methyl group. R a52 is an organic group that does not have a group containing an active hydrogen capable of reacting with an isocyanate group.

[0149] Among them, the unit derived from the (meth)acrylate represented by formula (a5-1) is a unit that does not belong to the aforementioned units (a1), unit (a2), and unit (a3).

[0150] Examples of the group containing active hydrogen include a hydroxyl group, a mercapto group, an amino group, a carboxyl group, etc. For such an organic group, a bond other than a hydrocarbon group such as a heteroatom and a substituent may be included in the organic group. Further, the structure of the organic group may be any of a linear structure, a branched structure, a cyclic structure, or a combination of these structures.

[0151] As the substituent other than the hydrocarbon group in the organic group of R a52 , as long as the effects of the present invention are not impaired, there is no particular limitation, 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 with a hydrocarbon group. Further, the structure of the hydrocarbon group contained in the above substituent may be any of a linear structure, a branched structure, a cyclic structure, and a combination of these structures.

[0152] As R a52 , it is preferably an aryl group, an aralkyl group, or a heterocyclic group. 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.

[0153] When R a52 is an aryl group, preferred 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, etc.

[0154] When R a52 is an alicyclic group or a group containing an alicyclic group, preferred examples of the alicyclic group 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.

[0155] As the monomer other than the above (meth)acrylate for the supply unit (a5), allyl compounds, vinyl ethers, vinyl esters, styrenes, etc. may be mentioned. These monomers may be used alone or in combination of two or more.

[0156] Examples of the allyl compound include allyl esters such as allyl acetate, allyl hexanoate, allyl octanoate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, etc.; allyloxyethanol; and the like.

[0157] 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 anthryl ether; and the like.

[0158] Examples of vinyl esters include vinyl butyrate, vinyl isobutyrate, vinyl pivalate, 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, and vinyl naphthoate.

[0159] 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; halogenated styrenes such as chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, and 4-fluoro-3-trifluoromethylstyrene; and the like.

[0160] The content of the other unit (a5) in the resin (A) is not particularly limited as long as the desired effects are not impaired. With respect to all the structural units of the resin (A), the total molar ratio of the unit (a1), the unit (a2), and the unit (a3) is preferably 50 mol% or more, more preferably 60 mol% or more, further preferably 70 mol% or more, further more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0161] Therefore, with respect to all the structural units of the resin (A), the molar ratio of the unit (a5) is preferably 50 mol% or less, more preferably 40 mol% or less, further preferably 30 mol% or less, further more preferably 20 mol% or less, and particularly preferably 10 mol% or less.

[0162] Particularly preferably, in the resin (A) described above,

[0163] the ratio of the number of moles of the ester-containing unit (a1) is 15 mol% or more with respect to the total number of moles of all the structural units of the resin (A),

[0164] the ratio of the number of moles of the hydroxyl group-donating unit (a2) is 5 mol% or more with respect to the total number of moles of all the structural units of the resin (A),

[0165] the ratio of the number of moles of the unit (a3) containing a blocked isocyanate group is 5 mol% or more with respect to the total number of moles of all the structural units of the resin (A),

[0166] 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 unit (a3) containing a blocked isocyanate group is 70 mol% or more with respect to the total number of moles of all the structural units of the resin (A).

[0167] The weight average molecular weight of the resin (A) is preferably 3,000 or more and 100,000 or less, more preferably 5,000 or more and 80,000 or less, and particularly preferably 7,000 or more and 60,000 or less. The weight average molecular weight is the molecular weight in terms of polystyrene measured by GPC. By making the weight average molecular weight of the resin (A) relatively large to some extent, it is easy to form a cured product excellent in solvent resistance and heat decomposition resistance.

[0168] 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.

[0169] <Hollow particles (B)>

[0170] From the aspect of easily forming a cured product with a low refractive index, the curable composition may contain hollow particles (B). The hollow particles (B) are formed 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.

[0171] From the aspects of ease of acquisition and ease of forming a cured product with a low refractive index, as the hollow particles (B), hollow silica particles (B1) and hollow resin particles (B2) are preferred, and hollow silica particles (B1) are more preferred.

[0172] 〔Hollow silica particles (B1)〕

[0173] As the hollow silica particles (B1), conventionally known hollow silica particles can be used without particular limitation. The hollow silica particles (B1) can be commercially available products or synthetic products.

[0174] The hollow silica particles (B1) can be selected and used from known hollow silica considering the particle size and refractive index.

[0175] 〔Hollow resin particles (B2)〕

[0176] The hollow resin particles (B2) are particles composed of a shell formed of a resin and a void surrounded by the shell. The shell can be a single layer or multiple layers. In the case where the shell is multiple layers, each layer can be composed of a different resin.

[0177] 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; thermally expandable microcapsules of vinylidene chloride-acrylonitrile or acrylonitrile. It should be noted that the hollow particles preferably have a crosslinked structure.

[0178] Commercially available hollow resin particles (B2) can also be used. As commercially available products of the hollow resin particles (B2), Techpolymer (registered trademark) NH (Sekisui Chemical Co., Ltd.) etc. can be used.

[0179] The refractive index of the hollow particles (B) is significantly lower than the refractive index of ordinary silica, which is 1.46. This is because the hollow particles (B) contain air inside, which exhibits a low refractive index of 1.0.

[0180] 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, it is preferably 1.1 or more and 1.4 or less, more preferably 1.1 or more and 1.35 or less.

[0181] In addition, as the hollowness ratio of the hollow particles (B), it is preferably 10 to 95%, more preferably 20 to 50%.

[0182] The volume average particle size 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, still more preferably 50 nm or more and 150 nm or less.

[0183] The content of the hollow particles (B) in the curable composition is not particularly limited as long as the desired effects are not impaired. Regarding the content of the hollow particles (B) in the curable composition, from the aspect of easily forming a cured product with a low refractive index, it 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, relative to 100 parts by mass of the resin (A).

[0184] <Colorant (C)>

[0185] 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, further preferably 20% by mass or less, further more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 0% by mass, relative to the total mass of the components other than the solvent (S) in the curable composition. That is, it is most preferred that the curable composition does not contain a colorant (C).

[0186] The colorant (C) can be an organic colorant or an inorganic colorant. As the colorant (C), any colorant among dyes and pigments can be used. As the colorant (C), a pigment is preferred. The hue of the colorant (C) is not particularly limited. The hue of the colorant (C) can be appropriately selected in consideration of the use of the cured product.

[0187] <Solvent (S)>

[0188] The curable composition contains a solvent (S) for purposes such as adjusting coating properties and viscosity. As the solvent (S), typically, an organic solvent can be used. The type of the organic solvent is not particularly limited as long as it can uniformly dissolve or disperse the components contained in the curable composition.

[0189] As specific examples of the solvent (S), mention may be made of (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monon-propyl ether, ethylene glycol monon-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monon-propyl ether, diethylene glycol monon-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monon-propyl ether, propylene glycol monon-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monon-propyl ether, dipropylene glycol monon-butyl ether, tripropylene glycol monomethyl ether, 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, propylene glycol monoethyl ether acetate; other ethers such as 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; alkyl lactates such as methyl 2-hydroxypropionate, 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 glycolate, 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, isoamyl 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-oxobutyrate; 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, etc.

[0190] Among them, preferred are (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-amyl formate, isoamyl 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-oxobutyrate; 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, etc.

[0191] The solvent (S) can be used alone or in combination of two or more.

[0192] 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 property, the solvent (S) is used in such a manner 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 further preferably 5% by mass or more and 30% by mass or less.

[0193] <Other components (E)>

[0194] The curable composition may contain various additives as other components (E) in addition to the aforementioned components as needed. Examples of such additives include stabilizers, adhesion enhancers, crosslinking agents, curing accelerators, surfactants, antioxidants, adhesion aids, defoamers, polymerization inhibitors such as thermal polymerization inhibitors, etc. These additives can be used alone or in combination of two or more.

[0195] The amounts of these additives used are not particularly limited as long as the desired effect is not impaired. The amounts of these additives used can be appropriately determined in consideration of the amounts of these additives used in conventionally known curable compositions.

[0196] 〔Manufacturing method of curable composition〕

[0197] After mixing the components described above in specified amounts and stirring the mixture evenly, a curable composition can be obtained.

[0198] <Resin>

[0199] The resin is a resin that contains an ester-containing unit (a1), a hydroxyl group-providing unit (a2), and a blocked isocyanate group-containing unit (a3), and does not contain an acidic group-containing unit (a4).

[0200] The ester-containing unit (a1) has an ester group represented by the following formula (A1).

[0201] -CO-O-R(A1)

[0202] (In the formula, R is an aliphatic hydrocarbon group that may have a substituent.)

[0203] The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-providing unit (a2) and the blocked isocyanate group-containing unit (a3).

[0204] With respect to the number of moles of all the structural units of the resin (A), the ratio of the number of moles of the blocked isocyanate group-containing unit (a3) is 15 mol% or more.

[0205] Regarding the above resin, the ester-containing unit (a1), the hydroxyl group-providing 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.

[0206] The above resin may also contain other units (a5). The other units (a5) are the same as the other units (a5) of the resin (A) contained in the curable composition.

[0207] The above resin can be suitably incorporated as the resin (A) into the aforementioned curable composition.

[0208] 《Cured Product》

[0209] By heating the curable composition described above, a cured product can be formed. Such a cured product has high solvent resistance and exhibits a low refractive index.

[0210] The curing conditions are not particularly limited as long as the curable composition is sufficiently cured. As the curing temperature, for example, it is preferably 90°C or higher and 250°C or lower, more preferably 150°C or higher and 250°C or lower. As the curing time, for example, it is preferably 30 seconds or longer and 1 hour or shorter, more preferably 1 minute or longer and 30 minutes or shorter.

[0211] As described above, the inventors of the present application provide the following (1) to (9).

[0212] (1) A curable composition comprising a resin (A) and a solvent (S), and containing or not containing a colorant (C),

[0213] The resin (A) is dissolved in the solvent (S),

[0214] With respect to the total mass of the components other than the solvent (S) in the curable composition, the mass ratio of the colorant (C) is less than 50% by mass,

[0215] The resin (A) contains an ester-containing unit (a1), a hydroxyl group-providing unit (a2), and a blocked isocyanate group-containing unit (a3),

[0216] The ester-containing unit (a1) has an ester group represented by the following formula (A1),

[0217] -CO-O-R(A1)

[0218] (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.)

[0219] The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-providing unit (a2) and the blocked isocyanate group-containing unit (a3).

[0220] (2) The curable composition according to (1), further comprising hollow particles (B).

[0221] (3) The curable composition according to (1) or (2), wherein the resin (A) does not contain an acidic group-containing unit (a4).

[0222] (4) The curable composition according to any one of (1) to (3), wherein in the ester-containing unit (a1), the aliphatic hydrocarbon group has 1 to 6 carbon atoms.

[0223] (5) The curable composition according to any one of (1) to (4), wherein the blocked isocyanate group-containing unit (a3) has a group represented by the following formula (a3-2).

[0224] -NH-CO-R a34 ···(a3-2)

[0225] (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.)

[0226] (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 formed from the curable composition under the conditions of 100 °C for 60 seconds and then heating at 200 °C for 5 minutes is 1.53 or less.

[0227] (7) The curable composition according to any one of (1) to (6), wherein the ratio of the number of moles of the unit (a1) containing an ester to the total number of moles of all structural units of the resin (A) is 15 mol% or more.

[0228] The ratio of the number of moles of the hydroxyl group-providing unit (a2) to the total number of moles of all structural units of the resin (A) is 5 mol% or more.

[0229] The ratio of the number of moles of the unit (a3) containing a blocked isocyanate group to the total number of moles of all structural units of the resin (A) is 5 mol% or more.

[0230] The total ratio of the number of moles of the unit (a1) containing an ester, the number of moles of the hydroxyl group-providing unit (a2), and the number of moles of the unit (a3) containing a blocked isocyanate group to the total number of moles of all structural units of the resin (A) is 70 mol% or more.

[0231] (8) A resin comprising a unit (a1) containing an ester, a hydroxyl group-providing unit (a2), and a unit (a3) containing a blocked isocyanate group, and not containing a unit (a4) containing an acidic group.

[0232] The unit (a1) containing an ester has an ester group represented by the following formula (A1).

[0233] -CO-O-R(A1)

[0234] (In the formula, R is an aliphatic hydrocarbon group which may have a substituent.)

[0235] The unit (a1) containing an ester is a unit that does not belong to the hydroxyl group-providing unit (a2) and the unit (a3) containing a blocked isocyanate group.

[0236] The ratio of the number of moles of the unit (a3) containing a blocked isocyanate group to the total number of moles of all structural units of the resin (A) is 15 mol% or more.

[0237] (9) A cured product of the curable composition according to any one of (1) to (7).

[0238] Examples

[0239] Hereinafter, the present invention will be described in more detail using examples and comparative examples. The present invention is not limited to these examples.

[0240] Hereinafter, in Examples and Comparative Examples, a resin formed of the units described in Tables 1 to 3 was 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 the Examples and Comparative Examples are described in Tables 1 to 3.

[0241] The units described in Tables 1 to 3 are as follows.

[0242] <Unit (a1) containing an ester>

[0243] [Chemical formula 4]

[0244]

[0245] <Hydroxyl group-providing unit (a2)>

[0246] [Chemical formula 5]

[0247]

[0248] <Unit (a3) containing a blocked isocyanate group>[Chemical formula 6]

[0249]

[0250] <Unit (a4) containing an acidic group>

[0251] [Chemical formula 7]

[0252]

[0253] <Other unit (a5)>

[0254] [Chemical formula 8]

[0255]

[0256] <Hollow particles (B)>

[0257] In Examples and Comparative Examples, the following hollow particles b-1 and b-2 were used.

[0258] b-1: Hollow silica particles having a volume average particle diameter of 60 nm.

[0259] b-2: Hollow particles having a volume average particle diameter of 65 nm and a shell made of resin.

[0260] [Examples 1 to 22 and Comparative Examples 1 to 4]

[0261] Dissolve 100 parts by mass of the resin described in Table 1 and 0.1 part by mass of the surfactant in a solvent so that the solid content concentration is 20% by mass to obtain the curable compositions of Examples 1 to 21 and Comparative Examples 1 to 4.

[0262] 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.

[0263] As the surfactant, a silicone-based surfactant (polyester-modified polydimethylsiloxane, BYK-310, manufactured by BYK-Chemie) was used.

[0264] Using the obtained curable compositions of Examples 1 to 22 and Comparative Examples 1 to 4, the chemical resistance of the cured product, the refractive index of the cured product, and the temporal stability of the curable composition were evaluated according to the following methods. The evaluation results are shown in Table 1.

[0265] [Chemical resistance evaluation]

[0266] On a silicon substrate, the curable composition was coated using 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.

[0267] Next, the formed cured film was immersed in acetone, propylene glycol monomethyl ether acetate (PGMEA), and an aqueous solution of 2.38% by mass of tetramethylammonium hydroxide (TMAH) at room temperature for 10 minutes, respectively. After immersion, the surface of the cured film was rinsed with pure water for 30 seconds. After rinsing, the cured film was dried.

[0268] 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. In the case of A evaluation, B evaluation, and C evaluation, the chemical resistance is good.

[0269] Residual film ratio (%) = T2 / T1 × 100

[0270] (Evaluation criteria)

[0271] A: The residual film ratio is 99% or more and 103% or less.

[0272] B: The residual film ratio is 95% or more and less than 99%, or more than 103% and 105% or less.

[0273] C: The residual film ratio is 90% or more and less than 95%, or more than 105% and 110% or less

[0274] D: The residual film rate is less than 90% or greater than 110%.

[0275] [Refractive Index Evaluation]

[0276] On a silicon substrate, a curable composition was applied using 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.

[0277] Using a rotating compensator type high-speed spectroscopic ellipsometer (M-2000, manufactured by J.A. Woollam Japan Corporation), the refractive index of the obtained cured film at a light wavelength of 550 nm was measured. Based on the measured refractive index value, the refractive index was evaluated according to the following criteria. In the case of A evaluation, B evaluation, and C evaluation, the refractive index is sufficiently low.

[0278] A: The refractive index is 1.51 or less.

[0279] B: The refractive index is greater than 1.51 and 1.52 or less.

[0280] C: The refractive index is greater than 1.52 and 1.53 or less.

[0281] D: The refractive index is greater than 1.53.

[0282] [Evaluation of Stability over Time]

[0283] The viscosity V1 of the obtained curable composition was measured using a Cannon-Fenske viscometer. After storing the obtained curable composition at 40 °C for 2 weeks, the viscosity V2 of the curable composition was measured using a Cannon-Fenske viscometer. Based on the values of V1 and V2, the viscosity increase rate (%) was calculated according to the following formula.

[0284] Viscosity increase rate (%) = V2 / V1 × 100 - 100

[0285] Based on the calculated viscosity increase rate value, the stability over time of the curable composition was evaluated according to the following criteria. In the case of A evaluation and B evaluation, the stability over time is good.

[0286] A: The viscosity increase rate is less than 5%

[0287] B: The viscosity increase rate is 5% or more and less than 10%

[0288] C: The viscosity increase rate is 10% or more and less than 15%

[0289] D: The viscosity increase rate is 15% or more

[0290] [Table 1]

[0291]

[0292] [Examples 23 to 72 and Comparative Examples 5 to 12]

[0293] 100 parts by mass of the resin described in Table 2 or Table 3, hollow particles of the types and amounts 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.

[0294] 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.

[0295] As the surfactant, a silicone surfactant (polyester-modified polydimethylsiloxane, BYK-310, manufactured by BYK-Chemie) was used.

[0296] Using the obtained curable compositions of Examples 23 to 72 and Comparative Examples 5 to 12, the chemical resistance of the cured product, the refractive index of the cured product, and the temporal stability of the curable composition were evaluated in the same manner as in Example 1. Among them, the refractive index was evaluated based on the following criteria. In the case of A evaluation, B evaluation, and C evaluation, the refractive index was sufficiently low.

[0297] Their evaluation results are shown in Tables 2 and 3.

[0298] (Refractive Index Evaluation Criteria)

[0299] A: The refractive index is 1.39 or less.

[0300] B: The refractive index is greater than 1.39 and 1.41 or less.

[0301] C: The refractive index is greater than 1.41 and 1.43 or less.

[0302] D: The refractive index is greater than 1.43.

[0303] [Table 2]

[0304]

[0305] [Table 3]

[0306]

[0307] From Tables 1 to 3, it can be seen that the curable composition containing the resin (A) and the solvent (S) containing the aforementioned units (a1), (a2), and (a3) can provide a cured product having excellent chemical resistance and a low refractive index, and excellent temporal stability.

[0308] On the other hand, in the curable composition of the comparative example containing a resin that does not contain the aforementioned unit (a1), unit (a2), and unit (a3), any one or more of the chemical resistance, low refractive index of the cured product, and stability over time deteriorates.

Claims

1. A curable composition comprising a resin (A) and a solvent (S), and optionally a colorant (C), The resin (A) is dissolved in a 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) comprises an ester-containing unit (a1), a hydroxyl-donating unit (a2), and a blocked isocyanate group-containing unit (a3), The ester-containing unit (a1) has an ester group represented by the following formula (A1): -CO-OR(A1) In formula (A1), R is an aliphatic hydrocarbon group which may have a substituent; The ester-containing unit (a1) is a unit that does not belong to the hydroxyl group-donating unit (a2) and the blocked isocyanate group-containing unit (a3). 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 the unit (a4) containing an acidic group.

4. The curable composition according to claim 1 or 2, wherein In the ester-containing unit (a1), the aliphatic hydrocarbon group has 1 to 6 carbon atoms.

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

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

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

8. A resin comprising an ester-containing unit (a1), a hydroxyl-donating unit (a2) and a blocked isocyanate group-containing unit (a3), and no acidic group-containing unit (a4), The ester-containing unit (a1) has an ester group represented by the following formula (A1): -CO-OR(A1) In formula (A1), R is an aliphatic hydrocarbon group which may have a substituent; The ester-containing unit (a1) is a unit that does not belong to the hydroxyl-donating unit (a2) and the blocked isocyanate group-containing unit (a3). The ratio of the molar number of the units (a3) ​​containing a blocked isocyanate group to the molar number of all structural units of the resin (A) is 15 mol% or more.

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

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