Curable composition, cured product, optical material, microlens, and diffractive optical element

Abstract

Provided are: a curable composition comprising a thio(meth)acrylate monomer that contains an aromatic hydrocarbon ring, a compound that contains a piperidinyloxy radical structure, and a phenol compound; a cured product obtained from said curable composition; an optical material; a microlens; and a diffractive optical element.

Description

Curable compositions, cured products, optical materials, microlenses, and diffractive optical elements

[0001] The present invention relates to a curable composition, a cured product, an optical material, a microlens, and a diffractive optical element.

[0002] In recent years, there has been a growing demand for optical components requiring high refractive indices, such as microlenses in micro-OLED (Organic Light Emitting Diode) displays, microlenses for image sensors, and diffractive optical elements in augmented reality (AR) glasses. As a result, research is being conducted on applying resins that exhibit high refractive indices (high refractive index resins) as materials for such optical components. High refractive index resins can be obtained by polymerizing monomers that exhibit high refractive indices (high refractive index monomers).

[0003] As an example of a high refractive index monomer, naphthalene skeleton-containing monomers are known. However, naphthalene skeleton-containing monomers have high crystallinity derived from the naphthalene skeleton, which imposes limitations in terms of handling. As a technology to address this problem, for example, Patent Document 1 describes 1,6-naphthalenedithiol and its derivatives (e.g., (meth)acrylate dithioester) that achieve both high refractive index and high solubility (mismatch).

[0004] Furthermore, imprint technology is known to be used to fabricate optical components with nanometer to micrometer-order microstructures. Imprint technology is a microfabrication technique that transfers a fine pattern to the surface of a material by pressing a mold with a desired fine pattern structure onto a material such as resin. Imprint technology consists of the following steps: coating the substrate with the material, pressing the mold in the pressed state, fixing the transferred pattern by light or heat curing, and demolding. The material used for imprinting is required to have low viscosity, like ink used in inkjet, and to not undergo crystal precipitation or turbidity in the storage tank before use (hereinafter also referred to as "long-term stability").

[0005] For example, Patent Document 2 describes a curable composition containing a monofunctional (meth)acrylic acid thioester monomer having an arylene group and a group containing an S atom on a (meth)acryloylthiooxy(ethyl)phenyl ring, and a difunctional (meth)acrylic acid thioester monomer, as a monomer-containing composition that achieves high refractive index, low viscosity, and long-term stability.

[0006] International Publication No. 2023 / 058449, International Publication No. 2024 / 128266

[0007] Generally, in monomers having a (meth)acryloyloxy group or a (meth)acryloylthiooxy group, polymerization of the monomer tends to proceed when the solvent is removed from a solution containing the monomer and the solvent and the solution is concentrated during monomer synthesis, preparation of monomer-containing compositions, etc. Therefore, polymerization inhibitors are usually added to suppress monomer polymerization during concentration. Similarly, in the (meth)acrylic acid thioester monomers described in Patent Documents 1 and 2, polymerization inhibitors are added during the monomer synthesis process or the preparation of monomer-containing compositions. The present inventors investigated polymerization inhibitors applicable to (meth)acrylic acid thioester monomers and found that when compounds having a piperidinyl oxy radical structure, such as 2,2,6,6-tetramethylpiperidine-1-oxyl free radical (TEMPO) (TEMPO-based polymerization initiators), which are known to exhibit a high polymerization inhibition (polymerization suppression) effect, the polymerization suppression effect during the concentration of (meth)acrylic acid thioester monomer solutions is excellent. On the other hand, a new problem has emerged with curable compositions containing (meth)acrylic acid thioester monomers and TEMPO-based polymerization initiators: if they are stored for a certain period of time before being used to produce cured products, discoloration over time (discoloration over time) occurs.

[0008] The present invention aims to provide a curable composition that contains a thio(meth)acrylate monomer containing an aromatic hydrocarbon ring and a compound containing a piperidinyl oxy radical structure, while being less prone to discoloration over time. The present invention also aims to provide a cured product obtained from this curable composition, as well as an optical material, microlens, and diffractive optical element containing this cured product.

[0009] The above problems of the present invention have been solved by the following means: <1> A curable composition comprising a thio(meth)acrylate monomer containing an aromatic hydrocarbon ring, a compound containing a piperidinyl oxy radical structure, and a phenol compound. <2> The curable composition according to <1>, wherein, in 100% by mass of the solid content of the curable composition, the content of the compound containing the piperidinyl oxy radical structure is 0.0050 to 0.1000% by mass, the content of the phenol compound is 0.0500 to 0.3000% by mass, and the ratio of the content of the phenol compound to the content of the compound containing the piperidinyl oxy radical structure is 1.0 to 60. <3> The curable composition according to <1> or <2>, wherein the thio(meth)acrylate monomer containing the aromatic hydrocarbon ring is represented by the following general formula (A) or (B). In the above formula, R ａ ~R ｈ R represents a hydrogen atom, an alkylsulfanyl group having 1 to 10 carbon atoms, or a (meth)acryloylthiooxy group. However, R ａ ~R ｈ At least one of these is a (meth)acryloylthiooxy group. In the above formula, R ５ R represents a group containing an arylene group and an S atom, and L represents a single bond or a methylene group. ６ R represents a hydrogen atom or a methyl group. ５The (meth)acryloylthiooxy group may further be present. <4> A curable composition according to any one of <1> to <3> for imprinting. <5> A cured product obtained from any one of the curable composition according to <1> to <4>. <6> An optical material comprising the cured product according to <5>. <7> A microlens or diffractive optical element comprising the cured product according to <5>.

[0010] In the present invention, when there are a plurality of substituents or linking groups, etc. (hereinafter referred to as substituents, etc.) represented by specific symbols or formulas, or when a plurality of substituents, etc. are defined simultaneously, unless otherwise specified, each of the substituents, etc. may be the same as or different from each other (regardless of the presence or absence of the expression "each independently", each of the substituents, etc. may be the same as or different from each other). This also applies to the definition of the number of substituents, etc. Further, when a plurality of substituents, etc. are close to each other (particularly when adjacent), unless otherwise specified, they may be linked to each other to form a ring. Further, unless otherwise specified, a ring, for example, an alicyclic ring, an aromatic ring, or a heterocyclic ring may be further condensed to form a fused ring. In the present invention, unless otherwise specified, for a double bond, when both E-type and Z-type exist in the molecule, it may be either of them or a mixture thereof. Further, in the present invention, unless otherwise specified, when a compound has one or more asymmetric carbons, the stereochemistry of such asymmetric carbons can each independently take either the (R)-form or the (S)-form. As a result, the compound may be a mixture of stereoisomers such as optical isomers or diastereoisomers, or may be a racemate. However, when counting the types of compounds such as the thio(meth)acrylate monomer (T), the piperidinyl oxy radical compound (N), and the phenol compound (P) described later, the types of structural isomers are counted, and stereoisomers are not counted as different types. Further, in the present invention, the representation of the compound and the monomer includes those in which a part of the structure is changed as long as the effects of the present invention are not impaired. Furthermore, for compounds and monomers that are not specified as substituted or unsubstituted in words, it means that they may have any substituent as long as the effects of the present invention are not impaired. For example, in the monomer represented by the general formula (B), R ５ and -L-S-C(=O)C(R ６ )=CH ２The benzene ring having can be unsubstituted or have any substituent. Examples of optional substituents include saturated or unsaturated aliphatic hydrocarbon groups (which can be linear, branched, or cyclic), aromatic hydrocarbon groups, aromatic heterocyclic groups, alkoxy groups, alkylthio groups, aryloxy groups, arylthio groups, halogen atoms, etc. From the viewpoint of imprint applications, it is preferable that the ring is unsubstituted or, if substituted, that substituent is a halogen atom. In this invention, substituents (and the same applies to linking groups and rings) that are not explicitly stated as substituted or unsubstituted may have any substituent as long as the desired effect is not impaired. For example, "alkyl group" includes both unsubstituted alkyl groups and substituted alkyl groups. For example, R in general formula (A) ａ ~R ｈ and R in general formula (a) ｉ ~R ｐ The alkyl group in the alkylsulfanyl group having 1 to 10 carbon atoms that can be used as such may have substituents, as will be described later. In the present invention, when the number of carbon atoms of a group is specified, this number of carbon atoms refers to the total number of carbon atoms of the group unless otherwise specified in the present invention or this specification. That is, if the group has further substituents, it refers to the total number of carbon atoms including these substituents.

[0011] In the present invention, when describing physical properties, etc., by indicating numerical ranges, if the upper and lower limits of the numerical range are described separately, either upper or lower limit can be appropriately combined to form a specific numerical range. On the other hand, when multiple numerical ranges expressed using "~" are set and described, the upper and lower limits forming the numerical range are not limited to the specific combination of upper and lower limits described before and after "~" as a specific numerical range, but can be a numerical range formed by appropriately combining the upper and lower limits of each numerical range. In the present invention, a numerical range expressed using "~" means a range that includes the values ​​described before and after "~" as the lower and upper limits. In the curable composition of the present invention, unless otherwise specified, each component may be used individually or as a mixture of two or more. The same applies to cured products, optical materials, microlenses, and diffractive optical elements obtained from the curable composition of the present invention. In the present invention, a composition includes not only mixtures in which the component concentration is constant (each component is uniformly dispersed), but also mixtures in which the component concentration fluctuates within a range that does not impair the desired function. In particular, a mixture in which the component concentrations are constant (i.e., each component is uniformly dispersed) is preferred.

[0012] In the present invention, "(meth)acrylate" represents either acrylate or methacrylate, or both; "(meth)acrylic acid" represents either acrylic acid or methacrylic acid, or both; and "(meth)acryloyl" represents either acryloyl or methacryloyl, or both. In the present invention, "thio(meth)acrylate" represents either S-thioacrylate or S-thiomethacrylate, or both; "thio(meth)acrylic acid" represents either S-thioacrylic acid or S-thiomethacrylic acid, or both; and "(meth)acryloylthiooxy" represents either acryloylthiooxy or methacryloylthiooxy, or both.

[0013] The acryloylthiooxy group is the group represented by the following formula (Pol-1), and the methacryloylthiooxy group is the group represented by the following formula (Pol-2). In the following formulas, * indicates a bond.

[0014]

[0015] In the present invention, "(meth)acrylthioate ester" refers to either or both of acrylic acid S-ester and methacrylic acid S-ester, and means an ester of (meth)acrylic S-acid, which is an S-acid (-C(=O)SH). In the present invention, monomers are distinguished from oligomers and polymers by molecular weight, and compounds with a weight-average molecular weight of 1000 or less are called monomers.

[0016] In this invention, the term "alkyl group" refers to a linear or branched alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, even more preferably 1 to 7, and particularly preferably 1 to 5. Examples of alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, 1-methylbutyl group, 3-methylbutyl group, hexyl group, 1-methylpentyl group, 4-methylpentyl group, heptyl group, 1-methylhexyl group, 5-methylhexyl group, 2-ethylhexyl group, octyl group, 1-methylheptyl group, nonyl group, 1-methyloctyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc., of which methyl group or ethyl group is preferred. The same applies to alkyl groups in groups containing alkyl groups (alkoxy group, alkylsulfanyl group, alkoxycarbonyl group, acyl group, acyloxy group, etc.). Furthermore, alkyl groups may have substituents, and examples of alkyl groups having substituents include halogenated alkyl groups and hydroxyalkyl groups. In the present invention, the alkyl group having a cyclic structure, known as "cycloalkyl group," preferably has 3 to 20 carbon atoms, more preferably 3 to 12 carbon atoms, even more preferably 3 to 8 carbon atoms, even more preferably 3 to 6 carbon atoms, and particularly preferably 3 carbon atoms.

[0017] In the present invention, the alkylene group can be any group obtained by removing one hydrogen atom bonded to a carbon atom in the alkyl group, and may be a linear alkylene group or a branched alkylene group. Examples include ethylene, propylene, and butylene groups.

[0018] In the present invention, a monovalent aromatic hydrocarbon group refers to a monovalent group obtained by removing one arbitrary hydrogen atom from an aromatic hydrocarbon ring, which may be a monocyclic or fused ring. Preferred monovalent aromatic hydrocarbon groups are those having 6 to 14 carbon atoms. Examples include phenyl, 1-naphthyl, 2-naphthyl, 1-anthracenyl, 2-anthracenyl, 9-anthracenyl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, and 9-phenanthryl groups. Of these, the phenyl group is preferred.

[0019] In the present invention, a divalent aromatic hydrocarbon group (arylene group) refers to a divalent group obtained by removing one arbitrary hydrogen atom from the above-mentioned monovalent aromatic hydrocarbon group. Examples of divalent aromatic hydrocarbon groups include phenylene group, naphthylene group, phenanthrylene group, etc., with phenylene group being preferred, and 1,3-phenylene group or 1,4-phenylene group being more preferred.

[0020] In the present invention, examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0021] The curable composition of the present invention contains a thio(meth)acrylate monomer containing an aromatic hydrocarbon ring and a compound containing a piperidinyl oxy radical structure, yet is less prone to discoloration over time. The cured products, optical materials, microlenses, and diffractive optical elements of the present invention exhibit suppressed discoloration due to the fact that the curable composition used in their formation is less prone to discoloration over time.

[0022] Figure 1 is a schematic cross-sectional view illustrating a method for producing a cured product of the present invention using the curable composition of the present invention and imprint technology.

[0023] [Curable Composition] The curable composition of the present invention comprises a thio(meth)acrylate monomer containing an aromatic hydrocarbon ring (hereinafter also referred to as "thio(meth)acrylate monomer (T)"), a compound containing a piperidinyl oxy radical structure (hereinafter also referred to as "piperidinyl oxy radical compound (N)"), and a phenol compound (hereinafter referred to as "phenol compound (P)").

[0024] In the present invention, a curable composition means a composition that is curable and from which a cured product (resin) can be obtained by a curing reaction. That is, the curable composition of the present invention includes not only compositions in which the solvent is substantially almost absent and the monomer is contained in a high concentration, but also compositions in which the solvent and monomer are contained in a low concentration. In the above-mentioned compositions containing a high concentration of monomer, the effect of inhibiting monomer polymerization during concentration by the polymerization inhibitor piperidinyl oxy radical compound (N) is already achieved. Furthermore, in the above-mentioned compositions containing a low concentration of monomer, the solvent is substantially removed by concentration, thereby obtaining a composition containing a high concentration of monomer, and the effect of inhibiting monomer polymerization during concentration by the piperidinyl oxy radical compound (N) is achieved during the above-mentioned concentration. In the curable composition of the present invention, the total content of all monomers contained in the composition (total content of thio(meth)acrylate monomer (T) and (meth)acrylic(thio) acid ester compounds that may be included as other components) is not particularly limited, but is usually 50% by mass or more and less than 100% by mass, preferably 70% by mass or more and less than 100% by mass, and more preferably 80% by mass or more and less than 100% by mass, based on 100% by mass of solids. If the curable composition of the present invention contains a compound represented by the general formula (a) described below, the above monomer content shall include the content of the compound represented by the general formula (a) described below. In the present invention, solids refer to components other than the solvent described below.

[0025] The curable composition of the present invention contains a thio(meth)acrylate monomer (T), a piperidinyl oxy radical compound (N), and a phenol compound (P), which provides excellent suppression of discoloration over time in the state of the curable composition before the curing reaction. This is presumably because the piperidinyl oxy radical compound (N) in the curable composition of the present invention functions as a polymerization inhibitor for the thio(meth)acrylate monomer (T), while also acting as an inhibitor of oxygen (O) in the atmosphere. ２ Because oxidized forms of the piperidinyl oxy radical compound (N) are generated over time by oxidizers such as , it is thought that discoloration occurs when these oxidized forms react with the thio(meth)acrylate monomer (T). The curable composition of the present invention further contains a phenol compound (P) as an antioxidant, which reduces the oxidized forms of the piperidinyl oxy radical compound (N) back to the piperidinyl oxy radical compound (N). As a result, while demonstrating the suppression of monomer polymerization during concentration by the piperidinyl oxy radical compound (N), it is also possible to achieve a high level of suppression of discoloration over time in the state of the curable composition before the curing reaction.

[0026] Furthermore, the oxidized product of the piperidinyl oxy radical compound (N) obtained by oxidation of the above piperidinyl oxy radical compound (N) is formed when the nitroxyl radical (>N-O•), which is the active group in the piperidinyl oxy radical compound (N), is replaced with N-oxoammonium (>N ＋ It is thought to be a compound converted to (=O). The oxidized form of this piperidinyl oxy radical compound (N) is reduced to a phenol compound (P), resulting in N-oxoammonium (>N). ＋ It is known that the (N) compound can revert to the chemical structure of a piperidinyl oxy radical compound (N) in which (=O) is converted to a nitroxyl radical (>N-O•).

[0027] The components contained in the curable composition of the present invention will be described in order below.

[0028] <Thiotic (meth)acrylate monomers (T)> Thiotic (meth)acrylate monomers containing an aromatic hydrocarbon ring (thio(meth)acrylate monomers (T)) are compounds that contain an aromatic hydrocarbon ring and a functional group called a (meth)acryloylthiooxy group.

[0029] The above aromatic hydrocarbon ring may be either a monoring or a fused ring, and the number of ring constituent atoms is preferably 6 to 14, more preferably 6 to 10. In other words, it is more preferably a benzene ring or a naphthalene ring.

[0030] The thio(meth)acrylate monomer (T) preferably has one to four benzene rings or one to two naphthalene rings as an aromatic hydrocarbon ring, more preferably has one to three benzene rings or one naphthalene ring, and even more preferably has one or two benzene rings or one naphthalene ring. Depending on the number of (meth)acryloylthiooxy groups which are functional groups, the thio(meth)acrylate monomer (T) can have, for example, 1 to 6 functionalities, and is preferably 1 to 4 functionalities.

[0031] The thio(meth)acrylate monomer (T) is preferably represented by the following general formula (A) or the general formula (B). The thio(meth)acrylate monomer represented by the following general formula (A) is abbreviated as "thio(meth)acrylate monomer (TA)", and the thio(meth)acrylate monomer represented by the following general formula (B) is abbreviated as "thio(meth)acrylate monomer (TB)".

[0032] (Thio(meth)acrylate monomer (TA)) Thio(meth)acrylate monomer (TA) is represented by the following general formula (A).

[0033]

[0034] In the above formula, R ａ ~R ｈ R represents a hydrogen atom, a C1-C10 alkylsulfanyl group (alkyl-S-), or a (meth)acryloylthiooxy group. However, R ａ ~R ｈAt least one of these is a (meth)acryloylthiooxy group.

[0035] R ａ ~R ｈ The alkyl group in the C1-C10 alkylsulfanyl group that can be taken as is either linear or branched, and the number of carbon atoms in the alkyl group can be 1 to 10, preferably 1 to 7, more preferably 1 to 5, and even more preferably 1 to 3. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, 1-methylbutyl group, 3-methylbutyl group, hexyl group, 1-methylpentyl group, 4-methylpentyl group, heptyl group, 1-methylhexyl group, 5-methylhexyl group, 2-ethylhexyl group, octyl group, 1-methylheptyl group, nonyl group, 1-methyloctyl group, nonyl group, decyl group, etc., with methyl group or ethyl group being preferred. ａ ~R ｈ The alkyl group in the C1-C10 alkylsulfanyl group that can be selected may have substituents, and examples of alkyl groups having such substituents include halogenated alkyl groups and hydroxyalkyl groups. Examples of halogen atoms constituting the halogenated alkyl group include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. ａ ~R ｈ As for the alkylsulfanyl group having 1 to 10 carbon atoms that can be selected, a methylsulfanyl group or an ethylsulfanyl group is preferred.

[0036] R ａ ~R ｈ Of the eight groups, the number of groups that are alkylsulfanyl groups or (meth)acryloylthiooxy groups having 1 to 10 carbon atoms is not particularly limited, and there should be one or more, preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 3. Also, R ａ ~R ｈOf the eight groups, the number of (meth)acryloylthiooxy groups should be one or more, and from the viewpoint of obtaining a good cured product, for example, 1 to 4 is preferred, 1 to 3 is more preferred, and 1 or 2 is even more preferred. Also, R ａ ~R ｈ Of the eight groups, there are no particular restrictions on the number of alkylsulfanil groups having 1 to 10 carbon atoms; for example, 0 to 3 are preferred, and 0 to 2 are more preferred.

[0037] In the thio(meth)acrylate monomer (TA), the position of the substituent selected from a (meth)acryloylthiooxy group and a C1-C10 alkylsulfanil group (hereinafter referred to as "substituent A") is not particularly limited, and for example, it is as follows: In the case of monosubstituted, the position of the (meth)acryloylthiooxy group is R ａ and R ｂ Any of the following may be used. In the case of disubstituted substitution, the position of substituent A is not particularly limited, for example, R ａ and R ｂ , R ａ and R ｃ , R ａ and R ｄ , R ａ and R ｆ , R ａ and R ｇ , R ａ and R ｈ , R ｂ and R ｃ , or R ｂ and R ｇ In the case of trisubstituted substitution, the position of substituent A is not particularly limited, for example, R ａ , R ｃ and R ｆ The combination, R ａ , R ｃ and R ｇ A combination of, or R ｂ , R ｃ and R ｇ The combination is preferred. In the case of tetrasubstituted substitution, the position of substituent A is not particularly limited, for example, R ａ , R ｃ , R ｆ and R ｇA combination of, or R ａ , R ｃ , R ｆ and R ｈ The combination is preferred. However, in the above disubstituted to tetrasubstituted groups, at least one of substituent A is a (meth)acryloylthiooxy group.

[0038] (Compound represented by general formula (a)) When the thio(meth)acrylate monomer (T) is thio(meth)acrylate monomer (TA), the curable composition of the present invention may further contain a compound represented by the following general formula (a). The compound represented by the following general formula (a) is an alkylsulfanyl-substituted naphthalene compound.

[0039]

[0040] In the above formula, R ｉ ~R ｐ R represents a hydrogen atom or an alkylsulfanyl group having 1 to 10 carbon atoms (alkyl group -S-). However, R ｉ ~R ｐ At least one of these is an alkylsulfanil group having 1 to 10 carbon atoms.

[0041] R ｉ ~R ｐ The alkylsulfanyl groups having 1 to 10 carbon atoms that can be taken as R ａ ~R ｈ This is synonymous with an alkylsulfanil group having 1 to 10 carbon atoms that can be selected as R. ｉ ~R ｐ Of the eight groups, the number of alkylsulfanyl groups having 1 to 10 carbon atoms is not particularly limited; it should be one or more, preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0042] In the compound represented by general formula (a), the position of the alkylsulfanyl group having 1 to 10 carbon atoms is not particularly limited, and is as follows, for example: In the case of monosubstituted, the position of the alkylsulfanyl group having 1 to 10 carbon atoms is R ｉ and R ｊAny of them may be used. In the case of 2-substitution, the position having an alkylsulfanyl group having 1 to 10 carbon atoms is not particularly limited. For example, R ｉ and R ｊ , R ｉ and R ｋ , R ｉ and R ｌ , R ｉ and R ｎ , R ｉ and R ｏ , R ｉ and R ｐ , R ｊ and R ｋ , or, R ｊ and R ｏ are preferred. In the case of 3-substitution, the position having an alkylsulfanyl group having 1 to 10 carbon atoms is not particularly limited. For example, the combination of R ｉ , R ｋ and R ｎ , the combination of R ｉ , R ｋ and R ｏ , or the combination of R ｊ , R ｋ and R ｏ are preferred. In the case of 4-substitution, the position having an alkylsulfanyl group having 1 to 10 carbon atoms is not particularly limited. For example, the combination of R ｉ , R ｋ , R ｎ and R ｏ , or the combination of R ｉ , R ｃ , R ｎ and R ｐ are preferred. In addition, the position where the compound represented by the general formula (a) has an alkylsulfanyl group having 1 to 10 carbon atoms on the naphthalene ring is preferably the same as the position where the thio(meth)acrylate monomer (TA) contained in the curable composition of the present invention has the above-described substituent A on the naphthalene ring.

[0043] The following lists preferred specific examples of thio(meth)acrylate monomers (TA), compounds (A-1) to (A-26) and (A-35) to (A-58), and preferred specific examples of compounds represented by general formula (a), compounds (a-27) to (a-34), but are not limited to these. In the following, * indicates a bond.

[0044]

[0045] The molecular weight of the thio(meth)acrylate monomer (TA) is preferably 214 to 820, more preferably 214 to 670, and even more preferably 214 to 530. The molecular weight of the compound represented by general formula (a) is preferably 174 to 820, more preferably 174 to 670, and even more preferably 174 to 530.

[0046] Thio(meth)acrylate monomers (TA) and compounds represented by general formula (a) can be synthesized by conventional methods. For example, they can be synthesized by referring to the synthesis methods described in Japanese Patent Publication No. 2013-155118 (Sumitomo Seika) and Japanese Patent Publication No. Hei 3-170456 (Sumitomo Seika). They can also be synthesized by referring to the methods described in the examples as appropriate.

[0047] When the curable composition of the present invention contains thio(meth)acrylate monomer (TA) as thio(meth)acrylate monomer (T), it is preferable, and more preferable, to contain two or more compounds selected from thio(meth)acrylate monomer (TA) and compounds represented by general formula (a), from the viewpoint of suppressing crystal precipitation and exhibiting excellent long-term stability of the curable composition. However, it is always necessary to contain at least one thio(meth)acrylate monomer (TA). In this case, from the viewpoint of exhibiting excellent long-term stability of the curable composition, the content of each thio(meth)acrylate monomer (TA) and each compound represented by general formula (a) in the total 100% by mass of thio(meth)acrylate monomer (TA) and compounds represented by general formula (a) contained in the curable composition of the present invention can be, for example, 5% by mass or more for each, preferably 7% by mass or more for each, and more preferably 10% by mass or more for each. The upper limit is appropriately determined depending on how many types of thio(meth)acrylate monomers (TA) and compounds represented by general formula (a) are contained in the curable composition of the present invention, such that the lower limit of any compound is 5% by mass or more (preferably 7% by mass or more, more preferably 10% by mass or more). In the case of two or more of the above types being contained, it is sufficient that at least two types satisfy the above content requirement, and in the case of three or more types being contained, at least three types satisfy the above content requirement. For example, in addition to the at least two types or the at least three types mentioned above, thio(meth)acrylate monomers (TA) or compounds represented by general formula (a) may be contained in a content of less than 5% by mass.

[0048] When the curable composition of the present invention contains a compound represented by general formula (a), the content of the compound represented by general formula (a) relative to the total of the thio(meth)acrylate monomer (TA) and the compound represented by general formula (a) is not particularly limited as long as the desired cured product is obtained. For example, 0.01 to 50% by mass is preferred, 1 to 45% by mass is more preferred, 5 to 40% by mass is even more preferred, and 7 to 40% by mass is particularly preferred.

[0049] (Thio(meth)acrylate monomer (TB)) Thio(meth)acrylate monomer (TB) is represented by the following general formula (B).

[0050]

[0051] In the above formula, R ５ R represents a group containing an arylene group and an S atom, and L represents a single bond or a methylene group. ６ R represents a hydrogen atom or a methyl group. ５ It may further have a (meth)acryloylthiooxy group. Note that -R ５ and -L-SC(=O)C(R ６ ) = CH ２ It may be bonded to any carbon atom between positions 1 and 6 of the benzene ring.

[0052] R ５ This refers to a group containing an arylene group and an S atom. In the present invention, "a group containing an arylene group and an S atom" means R ５ The group is a group containing an arylene group and an S atom, and there are no particular restrictions on other structures as long as they do not impair the effects of the present invention.

[0053] R ５ The sulfur atoms contained in are included as thioether bonds represented by -S-. However, R ５ It does not have a structure in which two or more S atoms are linked together (disulfide structure or polysulfide structure in which three or more S atoms are linked together). ５ The number of S atoms contained in the material may be one or more, for example, 1 to 4 is preferred, 2 to 4 is more preferred, 2 to 3 is even more preferred, and 2 is particularly preferred.

[0054] R ５ Examples of arylene groups contained in include phenylene groups consisting of a monocyclic aromatic hydrocarbon ring and arylene groups consisting of aromatic hydrocarbon rings formed by the condensation of two or more rings, with phenylene groups being preferred. ５ The number of arylene groups contained in may be one or more, for example, one to two is preferred, and one is more preferred. ５The arylene group contained in may be unsubstituted, or it may have substituents as long as it does not impair the effects of the present invention. ５ Examples of substituents that the arylene group contained in may have include halogen atoms, sulfanyl groups, and alkylsulfanyl groups, with halogen atoms being preferred. ５ The statement that an arylene group contained in has substituents means that substituents are present at locations other than the two bond sites of the arylene group. For example, R ５ The 1,3-phenylene group contained in has substituents, meaning that the substituent is located at any of the positions 2, 4, to 6, other than the two bonds on the phenylene group. ５ The alkylsulfanyl group that may be present in the arylene group contained therein preferably has 1 to 6 carbon atoms, more preferably 1 to 4, even more preferably 1 or 2, and particularly preferably 1. ５ If the arylene group contained in has substituents, the number of substituents is not particularly limited, for example, it can be 1 to 4, preferably 1 to 3, more preferably 1 to 2, and even more preferably 1. Among them, R ５ The arylene group contained in is preferably unsubstituted or has a halogen atom as a substituent, and more preferably unsubstituted.

[0055] R ５ It may further have a (meth)acryloylthiooxy group. ５ The fact that it further has a (meth)acryloylthiooxy group means that R ５ This means that the bond at the terminal end of the substituent among the arylene groups constituting the compound is bonded to the (meth)acryloylthiooxy group.

[0056] R ５ It may also contain structures other than the aforementioned arylene group and S atom, and any (meth)acryloylthiooxy group, for example, it is preferable to include an alkylene structure. ５ The number of carbon atoms in the alkylene group that may be contained is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 or 2, and particularly preferably 1.５ The alkylene structure that may be included may be unsubstituted, or it may have substituents to the extent that it does not impair the effects of the present invention. ５ Examples of substituents that the alkylene structure may contain include halogen atoms, sulfanyl groups, and alkylsulfanyl groups, with halogen atoms being preferred. ５ The term "having substituents" refers to the presence of substituents at locations other than the two bond sites on the alkylene group. ５ The alkylsulfanil group that the alkylene structure may contain is the aforementioned R ５ The description of alkylsulfanil groups that may be present in the arylene group contained therein can be preferably applied. In particular, R ５ The alkylene structure that may be included is preferably unsubstituted or has halogen atoms as substituents, and more preferably unsubstituted.

[0057] Note R ５ Since it is a monovalent group, R is made to include an arylene group and an S atom. ５ The terminal portion, the arylene group, the -S- group, or the other alkylene group, has a hydrogen atom. For example, using the following example compound (B-6), R ５ This is a group in which a H atom is present on the methylene group in -S-phenylene-S-methylene-. ５ If it further has a (meth)acryloylthiooxy group, R ５ The other end of the terminal portion, -S-, has a (meth)acryloyl group. For example, using the following example compound (B-21), R ５ This is a group having an acryloyl group at the -S- position in -S-phenylene-S-.

[0058] R ５ The total number of atoms other than hydrogen atoms constituting the compound is preferably 7 to 20, more preferably 9 to 18, even more preferably 9 to 15, particularly preferably 9 to 11, and most preferably 9. ５In the absence of a (meth)acryloylthiooxy group, it is preferably a group represented by -S-arylene-S-alkylene-H or -S-arylene-S-arylene-S-alkylene-H, more preferably a group represented by -S-arylene-S-alkylene-H, even more preferably a group represented by -S-phenylene-S-alkylene-H, and particularly preferably a group represented by -S-phenylene-S-methylene-H. ５ For example, when it has a (meth)acryloylthiooxy group, R when it does not have the above-mentioned (meth)acryloylthiooxy group ５ In the specific example, "-alkylene-H" and "-methylene-H" are replaced with "-C(=O)C(R) ６ ) = CH ２ A good example is the one in which the base is replaced with ".

[0059] L represents a single bond or a methylene group. Note that a methylene group is >CH ２ This refers to the group represented by . From the viewpoint of further increasing the refractive index nD of the cured product obtained by curing the curable composition of the present invention, L is preferably a single bond.

[0060] R ６ R represents a hydrogen atom or a methyl group. ６ From the viewpoint of further increasing the refractive index nD of the cured product obtained by curing the curable composition of the present invention, it is preferable that the atom is a hydrogen atom.

[0061] In general formula (B), R ５ Regarding the relationship between the bond positions of L on the benzene ring, ５ L may be bonded to the ortho, meta, or para position relative to the bonding site of L, but it is preferable that it is bonded to the meta position.

[0062] From the viewpoint of further increasing the refractive index nD of the cured product obtained by curing the curable composition of the present invention, the above-mentioned thio(meth)acrylate monomer (TB) preferably includes a monofunctional thio(meth)acrylate monomer represented by the following general formula (B1).

[0063]

[0064] In the above formula, L and R ６ These are L and R in the above general formula (B), respectively. ６ This is equivalent to the above. In other words, L is preferably a single bond, and R ６ A hydrogen atom is preferred.

[0065] -S-phenylene-S-CH₃ on the benzene ring located on the right side of general formula (B1) ３ The bond position of L on the benzene ring relative to the bond position of may be the ortho, meta, or para position, but the meta position is preferred. Also, the bond position of -S-phenylene-L-S-C(=O)C(R) on the benzene ring located on the left side in general formula (B1) ６ ) = CH ２ -S-CH on the benzene ring relative to the bonding position ３ The bond position may be the ortho, meta, or para position, with the meta position being preferred. From the viewpoint of further improving the long-term stability of the composition and lowering the viscosity of the composition, the -S-CH on the benzene ring in general formula (B1) ３ Preferably, at least one of the bonding position of -S-phenylene-S-CH on the benzene ring and the bonding position of L on the benzene ring is a meta position, and L is a single bond. From the viewpoint of further lowering the viscosity of the composition, it is more preferable that both of the above bonding positions in general formula (B1) are meta positions, and L is a single bond. In this invention, "bonding position of L on the benzene ring" refers to the -S-phenylene-S-CH on the benzene ring located on the right side in general formula (B1). ３ This refers to the bond position of L on the benzene ring relative to the bond position of -S-CH on the benzene ring, meaning "the bond position of -S-CH on the benzene ring". ３ The "bonding position" refers to the -S-phenylene-L-S-C(=O)C(R) on the benzene ring located on the left side in general formula (B1). ６ ) = CH ２ -S-CH on the benzene ring relative to the bonding position ３ This refers to the bond position. Therefore, from the viewpoint of further improving the temporal stability of the composition and further lowering the viscosity of the composition, the monomer represented by the above general formula (B) is the -S-CH on the benzene ring in general formula (B1). ３It is preferable to include a monomer in which at least one of the bonding position of L and the bonding position of L on the benzene ring is in the meta position, and L is a single bond. From the viewpoint of further lowering the viscosity of the composition, it is even more preferable to include a monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (B2) (hereinafter also simply referred to as "monomer represented by general formula (B2)").

[0066]

[0067] In the above formula, R ６ R in the above general formula (B) is ６ This is synonymous with R. ６ A hydrogen atom is preferred.

[0068] In the monomer represented by the above general formula (B), the monofunctional thio(meth)acrylate monomer represented by general formula (B1) (preferably the -S-CH on the benzene ring in general formula (B1)) ３ A monomer in which at least one of the bonding position of L and the bonding position of L on the benzene ring is at the meta position, and L is a single bond, more preferably a monofunctional (meth)acrylic acid thioester monomer represented by general formula (3). The content of ) is preferably 35% by mass or more, more preferably 50% by mass or more, even more preferably 65% ​​by mass or more, particularly preferably 80% by mass or more, and may be 100% by mass.

[0069] The following are some preferred examples of the thio(meth)acrylate monomers (TB) mentioned above, but the present invention is not limited to these compounds.

[0070]

[0071]

[0072] The molecular weight of the thio(meth)acrylate monomer (TB) is preferably 270 to 600, more preferably 300 to 600, and even more preferably 300 to 500.

[0073] Thio(meth)acrylate monomers (TB) can be synthesized by conventional methods. For example, they can be synthesized by referring to the synthesis method described in Org. Lett., 2004, Vol. 6, No. 24, pp. 4587-4590, or the synthesis method described in U.S. Patent Application Publication No. 2003 / 0195270. They can also be synthesized by referring to the methods described in the examples as appropriate.

[0074] When the curable composition of the present invention contains the above-mentioned thio(meth)acrylate monomer (T) in a high concentration, the total content of the above-mentioned thio(meth)acrylate monomer (T) in 100% by mass of the solid content of the curable composition of the present invention can be, for example, 97.00 to 99.99% by mass, preferably 98.00 to 99.95% by mass, more preferably 99.00 to 99.90% by mass, and even more preferably 99.00 to 99.70% by mass. If the curable composition of the present invention contains the compound represented by the above-mentioned general formula (a), the total content of the above-mentioned thio(meth)acrylate monomer (T) shall be the sum of the content of the above-mentioned thio(meth)acrylate monomer (T) and the content of the compound represented by the above-mentioned general formula (a).

[0075] When the curable composition of the present invention contains a diluted monomer such as a (meth)acrylic (thio) acid ester compound described below, the total content of the above thio(meth)acrylate monomer (T) in 100% by mass of the solid content of the curable composition of the present invention can be, for example, 60 to 99% by mass, preferably 65 to 99% by mass, more preferably 70 to 95% by mass, even more preferably 75 to 90% by mass, and particularly preferably 75 to 85% by mass.

[0076] <Piperidinyl oxy radical compound (N)> Compounds containing a piperidinyl oxy radical structure (piperidinyl oxy radical compound (N)) function as polymerization inhibitors. That is, as mentioned above, piperidinyl oxy radical compound (N) can effectively suppress the polymerization reaction of monomers that occurs when preparing a high-concentration composition containing thio(meth)acrylate monomer (T) (during concentration). As a result, the curable composition of the present invention contains a high concentration of monomers but substantially no monomer polymers, and therefore has good handling properties and excellent quality of the resulting cured product.

[0077] As the piperidinyl oxy radical compound (N), any compound containing a piperidinyl oxy radical structure that is commonly used as a polymerization inhibitor can be used without particular limitation. The number of piperidinyl oxy radical structures contained in the piperidinyl oxy radical compound (N) may be one or more, and one or two is preferred.

[0078] Preferred piperidinyl oxy radical compounds (N) include compounds represented by the following general formula (N1) or the following general formula (N2).

[0079] (Compounds represented by general formula (N1))

[0080] In the above formula, R １１ ~R １４ R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. １５ This represents a hydrogen atom, a hydroxyl group, a carboxyl group, an oxo group (=O), an alkoxy group having 1 to 10 carbon atoms, an acylamino group, an acyloxy group, or a group represented by the following general formula (n).

[0081]

[0082] In the above formula, R １１ ~R １４ The above R １１ ~R １４ These are synonymous. L represents an alkylene group having 1 to 10 carbon atoms, or a group formed by combining an alkylene group having 1 to 10 carbon atoms with at least one of -O-, >C=O, and >NH.

[0083] R １１ ~R １４ For alkyl groups having 1 to 10 carbon atoms, the description of alkyl groups described above applies to all aspects except the number of carbon atoms, and those with 1 to 4 carbon atoms are preferred. １１ ~R １４ The alkyl group is preferably a C1 to C10 alkyl group, and more preferably a C1 to C4 alkyl group.

[0084] R １５ For the alkoxy group having 1 to 10 carbon atoms (-O-alkyl group having 1 to 10 carbon atoms) that can be selected as such, the alkyl group can be described in the above-mentioned alkyl group description except for the number of carbon atoms, and the number of carbon atoms is preferably 1 to 4. １５ The acylamino group that can be taken is preferably an alkylcarbonylamino group. The alkyl group in the alkylcarbonylamino group (-NHC(=O)-alkyl group) can be defined according to the description of alkyl groups described above, and the number of carbon atoms is preferably 1 to 4. １５ The acyloxy group that can be taken as is preferably an arylcarbonyloxy group or a cycloalkylcarbonyloxy group. In the above arylcarbonyloxy group (-OC(=O)-aryl group), the aryl group can be described in the above description of aromatic hydrocarbon groups, and the number of carbon atoms of the arylcarbonyloxy group is preferably 7 to 14, and more preferably 7. In the above cycloalkylcarbonyloxy group (-OC(=O)-cycloalkyl group), the cycloalkyl group can be described in the above description of cycloalkyl groups, and the number of carbon atoms of the cycloalkylcarbonyloxy group is preferably 6 or 7. １５ The group is preferably a hydrogen atom, a hydroxyl group, a carboxyl group, an oxo group, an alkoxy group having 1 to 4 carbon atoms, an alkylcarbonylamino group having 2 to 5 carbon atoms, an arylcarbonyloxy group having 7 to 14 carbon atoms, a cycloalkylcarbonyloxy group having 6 or 7 carbon atoms, or a group represented by the above general formula (n), with a hydrogen atom, a hydroxyl group, or an oxo group being more preferred.

[0085] For alkylene groups having 1 to 10 carbon atoms that can constitute L, the above description of alkylene groups applies except for the number of carbon atoms, and the number of carbon atoms is preferably 1 to 8. Examples of groups that can be taken as L, which are formed by combining an alkylene group having 1 to 10 carbon atoms with at least one of -O-, >C=O, and >NH, include groups having at least one of -O-, >C=O, and >NH at both ends of the alkylene group having 1 to 10 carbon atoms, groups having -OC(=O)- or -NHC(=O)- at both ends of the alkylene group having 1 to 10 carbon atoms are preferred, and groups having -OC(=O)- at both ends of the alkylene group having 1 to 10 carbon atoms are more preferred. L is preferably a group formed by combining an alkylene group having 1 to 10 carbon atoms with at least one of -O-, >C=O, and >NH, more preferably a group having -OC(=O)- or -NHC(=O)- at both ends of the alkylene group having 1 to 10 carbon atoms, and even more preferably a group having -OC(=O)- at both ends of the alkylene group having 1 to 10 carbon atoms.

[0086] (Compounds represented by the general formula (N2))

[0087] In the above formula, R ２１ and R ２２ R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. ２３ and R ２４ R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, or ２３ and R ２４ and directly or methylene group (>CH ２ They are connected to each other via () to form a ring.

[0088] R ２１ ~R ２４ The alkyl groups having 1 to 10 carbon atoms that can be taken as are the above-mentioned R １１ ~R １４ This is synonymous with alkyl groups having 1 to 10 carbon atoms that can be selected as R. ２１ and R ２２ R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２３ and R ２４ Both are hydrogen atoms, or R ２３ and R ２４It is preferable that the two elements are bonded to each other directly or via a methylene group to form a ring.

[0089] The following lists preferred specific examples of the piperidinyl oxy radical compound (N) described above, but the present invention is not limited to these compounds. In the following, Me represents a methyl group. For some of the specific examples below, the general abbreviation of the compound is also indicated below the structural formula.

[0090]

[0091] The piperidinyl oxy radical compound (N) may contain one type or two or more types.

[0092] The content of piperidinyl oxy radical compound (N) in 100% by mass of the solid content of the curable composition of the present invention is not particularly limited as long as the color exhibited by the piperidinyl oxy radical compound (N) itself does not affect the curing reaction, and a desired cured product can be obtained by the curing reaction described later using the curable composition of the present invention. For example, 0.0050 to 0.1000% by mass (50 to 1000 ppm) is preferred, 0.0100 to 0.0700% by mass (100 to 700 ppm) is more preferred, and 0.0150 to 0.0500% by mass (150 to 500 ppm) is even more preferred. In particular, the content of phenol compound (P) needs to be adjusted according to the content of piperidinyl oxy radical compound (N) in order to suppress discoloration over time. Since phenol compound (P) also acts as a polymerization inhibitor, it is preferable to satisfy the above-mentioned content of piperidinyl oxy radical compound (N) from the viewpoint of the curing reaction proceeding well and obtaining a desired cured product. In the present invention, the content of the piperidinyl oxy radical compound (N) refers to the content of the piperidinyl oxy radical compound (N) contained in the curable composition of the present invention. Oxidized forms of the piperidinyl oxy radical compound (N) that have been oxidized by oxygen in the atmosphere, etc., are not included in the content of the piperidinyl oxy radical compound (N). The content of the piperidinyl oxy radical compound (N) in 100% by mass of the solid content of the curable composition of the present invention can be measured by gas chromatography or the like.

[0093] <Phenol compound (P)> The phenol compound (P) functions as an antioxidant. That is, as described above, the phenol compound (P) can suppress the discoloration caused by the chemical reaction between the oxidized form of the piperidinyl oxy radical compound (N) and the thio(meth)acrylate monomer (T) by reducing the oxidized form of the piperidinyl oxy radical compound (N).

[0094] The phenol compound (P) is not particularly limited as long as it is a phenol compound that has the function of reducing the oxidized form of the piperidinyl oxy radical compound (N), and commonly used phenolic antioxidants can be used.

[0095] As the phenol compound (P), compounds represented by the following general formula (P) are preferred.

[0096] (Compounds represented by general formula (P))

[0097] In the above formula, R ３１ ~R ３５ R represents a hydrogen atom, a hydroxyl group, an alkyl group, or an alkoxy group. However, R ３１ ~R ３５ At least one of these is a hydroxyl group, an alkyl group, or an alkoxy group.

[0098] R ３１ ~R ３５ The alkyl groups that can be selected are those to which the above description of alkyl groups applies, preferably having 1 to 4 carbon atoms, and more preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, or tert-butyl. ３１ ~R ３５ The alkyl group in the alkoxy group (-O-alkyl group) that can be taken as follows can be described in the above description of alkyl groups, and the number of carbon atoms is preferably 1 to 4. ３１ ~R ３５ Of these, the number of hydroxyl groups is preferably 0 to 2. ３１ ~R ３５ The number of hydrogen atoms in the group is preferably 1 to 4.

[0099] Furthermore, two of the compounds represented by the above general formula (P) are R ３１ ~R ３５ Compounds in which the members are linked to each other via a linking group at any one of the positions are also preferred. Examples of the linking group include -S- and alkylene groups. The description of alkylene groups above can be applied to the alkylene group, and methylene is preferred.

[0100] The following lists preferred specific examples of phenol compounds (P), but the present invention is not limited to these compounds. In the following, Me represents a methyl group, Et represents an ethyl group, and t-Bu represents a tert-butyl group.

[0101]

[0102] The molecular weight of the phenol compound (P) is preferably 110 to 550, more preferably 110 to 450, and even more preferably 110 to 400.

[0103] Furthermore, polymers known as phenolic resins, cresol resins, etc., can also be preferably used as the phenolic compound (P).

[0104] The phenol compound (P) may contain one type or two or more types.

[0105] The content of phenol compound (P) in 100% by mass of solids of the curable composition of the present invention is preferably 0.0500 to 0.3000% by mass (500 to 3000 ppm), more preferably 0.0500 to 0.2000% by mass (500 to 2000 ppm), and even more preferably 0.0750 to 0.1500% by mass (750 to 1500 ppm). Since phenol compound (P) also acts as a polymerization inhibitor, it is preferable to satisfy the above-mentioned content of phenol compound (P) from the viewpoint of ensuring that the curing reaction proceeds well and that a desired cured product can be obtained. In the present invention, the above-mentioned content of phenol compound (P) means the total content of phenol compound (P) and the oxidized form of phenol compound (P) obtained as a result of reducing piperidinyl oxy radical compound (N) contained in the curable composition of the present invention. The content of phenol compound (P) in 100% by mass of solids of the curable composition of the present invention can be measured by gas chromatography or the like.

[0106] In the curable composition of the present invention, the ratio of the content of the phenol compound (P) to the content of the piperidinyl oxy radical compound (N) (i.e., [content of phenol compound (P)] / [content of piperidinyl oxy radical compound (N)]) is preferably 1.0 to 60, more preferably 2.0 to 30, even more preferably 2.5 to 20, and particularly preferably 3.0 to 15.

[0107] In particular, from the viewpoint of achieving a higher level of suppression of monomer polymerization during concentration and suppression of discoloration of the composition over time, the curable composition of the present invention preferably has a content of piperidinyl oxy radical compound (N) of 0.0050 to 0.1000% by mass and a content of phenol compound (P) of 0.0500 to 0.3000% by mass in 100% by mass of solid content, and the ratio of the content of phenol compound (P) to the content of piperidinyl oxy radical compound (N) (i.e., [content of phenol compound (P)] / [content of piperidinyl oxy radical compound (N)]) is preferably 1.0 to 60.

[0108] Furthermore, the curable composition of the present invention yields a cured product through radical polymerization of the (meth)acryloylthiooxy group of the thio(meth)acrylate monomer (T). The curable composition of the present invention does not yield a cured product through an enthiol reaction, and it is preferable that it does not contain a polythiol compound having two or more sulfanil groups.

[0109] <Other Components> In addition to the thio(meth)acrylate monomer (T) (which may include the compound represented by the general formula (a) above), piperidinyl oxy radical compound (N), and phenol compound (P) described above, the curable composition of the present invention may further contain other components. Examples of other components include (meth)acrylic(thio) acid ester compounds (excluding the thio(meth)acrylate monomer (T) described above) and photoradical polymerization initiators.

[0110] ((meth)acrylic(thio) acid ester compounds) The curable composition of the present invention preferably contains, in addition to the thio(meth)acrylate monomer (T) described above, a (meth)acrylic(thio) acid ester compound (excluding the thio(meth)acrylate monomer (T) described above) as a diluent monomer. (Meth)acrylic(thio) acid ester compound means both (meth)acrylic acid ester compounds and (meth)acrylicthio acid S-ester compounds. Examples of (meth)acrylic(thio) acid ester compounds include monofunctional mono(meth)acrylic(thio) acid ester compounds, difunctional di(meth)acrylic(thio) acid ester compounds, and polyfunctional (meth)acrylic(thio) acid ester compounds with three or more functions, depending on the number of (meth)acryloyl groups which are functional groups.

[0111] Specific examples of mono(meth)acrylic(thio) ester compounds include isobornyl(meth)acrylate, dicyclopentanyl(meth)acrylate, 3,3,5-trimethylcyclohexyl(meth)acrylate, 4-tert-butylcyclohexyl(meth)acrylate, dicyclopentenyloxyethyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, isobutyl(meth)acrylate, and t-butyl(meth)acrylate. Isooctyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 1-ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, ethyl diglycol (meth)acrylate, cyclic trimethylolpropane formal mono(meth)acrylate, imide (meth)acrylate, isoamyl (meth)acrylate Ethoxylated succinic acid (meth)acrylate, trifluoroethyl (meth)acrylate, ω-carboxypolycaprolactone mono(meth)acrylate, cyclohexyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, stearyl (meth)acrylate, diethylene glycol monobutyl ether (meth)acrylate, lauryl (meth)acrylate, isodecyl (meth)acrylate, octyl / decyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone (meth)acrylate , ethoxylated (4) nonylphenol (meth)acrylate, methoxypolyethylene glycol (350) mono(meth)acrylate, methoxypolyethylene glycol (550) mono(meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, tribromophenyl (meth)acrylate, ethoxylated tribromophenyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate,Examples include ethylene oxide adducts of 2-phenoxyethyl (meth)acrylate, propylene oxide adducts of 2-phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 3-(meth)acryloyloxymethylcyclohexene oxide. Specific product names and sources of mono(meth)acrylic (thio) acid ester compounds include ethoxylated orthophenylphenol acrylate (NK Ester A-LEN-10, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) and m-phenoxybenzyl acrylate (Light Acrylate POB-A, manufactured by Kyoeisha Chemical Co., Ltd.).

[0112] Specific examples of di(meth)acrylic(thio) acid ester compounds include di(meth)acrylates of diols and di(meth)acrylates of (poly)alkylene glycols. Specific product names and sources for di(meth)acrylic(thio) acid ester compounds include 1,6-hexanediol diacrylate (NK Ester A-HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light Acrylate 1,6HX-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,9-nonanediol diacrylate (NK Ester A-NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light Acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.), and 1,10-decanediol diacrylate. (NK Ester A-DOD-N, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), neopentyl glycol diacrylate (NK Ester A-NPG, manufactured by Shin Nakamura Chemical Industry Co., Ltd.; light acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd.), ethylene glycol diacrylate (SR206NS, manufactured by Arkema), polyethylene glycol diacrylate (NK Ester A-400, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), polypropylene glycol diacrylate (NK Ester APG-400, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) (Manufactured by Nakamura Chemical Industry Co., Ltd.), Tricyclodecanedimethanol diacrylate (also known as dimethylol-tricyclodecanediacrylate) (NK Ester A-DCP, manufactured by Shin Nakamura Chemical Industry Co., Ltd.; Light Acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,3-Butanediol dimethacrylate (NK Ester BG, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 1,4-Butanediol dimethacrylate (NK Ester BD, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 1,6-Hexanediol dimethacrylate Examples include acrylate (NK Ester HD-N, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 1,9-nonanediol dimethacrylate (NK Ester NOD-N, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 1,10-decanediol dimethacrylate (NK Ester DOD-N, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), 1,12-dodecanediol dimethacrylate (SR262, manufactured by Sartomer Co., Ltd.), neopentyl glycol dimethacrylate (NK Ester NPG, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), etc.

[0113] Specific product names and sources for polyfunctional (meth)acrylic (thio) acid ester compounds include trimethylolpropane triacrylate (NK Ester A-TMPT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light Acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.), ethoxylated trimethylolpropane triacrylate (NK Ester A-TMPT-EO, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), ethoxylated glycerin triacrylate (NK Ester A-GLY-6E, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), propoxylated glycerin triacrylate (NK Ester A-GLY-3P, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), and other trifunctional (meth)acrylic (thio) acid ester compounds; Examples include tetrafunctional (meth)acrylic (thio) acid ester compounds such as pentaerythritol tetraacrylate (NK Ester A-TMMT, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), ethoxylated pentaerythritol tetraacrylate (NK Ester ATM-4E, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), and ditrimethylolpropane tetraacrylate (NK Ester AD-TMP-L, manufactured by Shin Nakamura Chemical Industry Co., Ltd.); pentafunctional (meth)acrylic (thio) acid ester compounds such as dipentaerythritol pentaacrylate (M-402, manufactured by Toagosei Co., Ltd.); and hexafunctional (meth)acrylic (thio) acid ester compounds such as dipentaerythritol hexaacrylate (GM66G0H, manufactured by Kokusei Chemical Co., Ltd.).

[0114] The following are some preferred examples of (meth)acrylic (thio) acid ester compounds, but the present invention is not limited to these compounds.

[0115]

[0116] There are no particular restrictions on how the above (meth)acrylic (thio) acid ester compounds can be obtained; they may be obtained commercially or synthesized by conventional methods.

[0117] When the curable composition of the present invention contains a (meth)acrylic (thio) acid ester compound, the content of the (meth)acrylic (thio) acid ester compound in 100% by mass of the solid content of the curable composition of the present invention can be, for example, 1 to 40% by mass, preferably 1 to 35% by mass, more preferably 5 to 30% by mass, even more preferably 10 to 25% by mass, and particularly preferably 15 to 25% by mass. By controlling the amount of the (meth)acrylic (thio) acid ester compound in the curable composition, the function of relieving stress when the cured product undergoes thermal changes can be adjusted.

[0118] If the curable composition of the present invention contains a (meth)acrylic (thio) acid ester compound, the curable composition of the present invention may contain two or more (meth)acrylic (thio) acid ester compounds. If two or more (meth)acrylic (thio) acid ester compounds are contained, it is preferable that the total content is within the above range.

[0119] (Photoradical polymerization initiator) The curable composition of the present invention preferably contains a photoradical polymerization initiator. The curable composition of the present invention can produce a cured product exhibiting a high refractive index by photopolymerization induced by the action of the photoradical polymerization initiator. As the photoradical polymerization initiator, compounds commonly used as photoradical polymerization initiators can be used as appropriate according to the conditions of the photopolymerization (photocuring) process described later, and specifically the following compounds can be used. For example, 1,2-diphenylethanedione, methylphenylglyoxylate; bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,4,4-trimethylpentylphosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, ethylphenyl(2,4,6-trimethylbenzoyl)phosphinate (also known as (2,4,6-trimethylbenzoyl)ethoxylphenylphosphine oxide), etc., α-acylphosphine α-hydroxyketone compounds such as 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methylpropan-1-one; benzyl ketal compounds such as 2,2-dimethoxy-1,2-diphenylethane-1-one; α-aminoketone compounds such as 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone;Examples of oxime ester compounds include 1-[4-(phenylthio)phenyl]octane-1,2-dione=2-(O-benzoyl oxime) (available from BASF Japan as Irgacure OXE01 (trade name)), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone=O-acetyloxime (available from BASF Japan as Irgacure OXE02 (trade name)), Irgacure OXE03 and Irgacure OXE04 (all trade names, available from BASF Japan), and ADEKA Arculus N-1919T, ADEKA Arculus NCI-831E, ADEKA Arculus NCI-930 and ADEKA Arculus NCI-730 (all trade names, available from ADEKA).

[0120] In particular, the present invention uses the following as photoradical polymerization initiators: 1-hydroxycyclohexyl phenyl ketone (available from BASF Japan as Irgacure 184 (trade name)), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (available from BASF Japan as Irgacure 819 (trade name)), (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (available from BASF Japan as Irgacure TPO (trade name)), and 2,2-dimethoxy-1,2-diphenylethane-1-one. Preferably, one photoradical polymerization initiator may be used (available from BASF Japan as Irgacure 651 (trade name)), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, ethylphenyl (2,4,6-trimethylbenzoyl) phosphinate (available from BASF Japan as Irgacure TPO-L (trade name)), or Adeka Arclus NCI-831E (trade name, available from ADEKA). The photoradical polymerization initiator may contain one or more types.

[0121] When a photoradical polymerization initiator is included, the content of the photoradical polymerization initiator in 100% by mass of the solid content of the curable composition of the present invention is preferably 0.01 to 5.00% by mass, more preferably 0.05 to 1.00% by mass, and even more preferably 0.05 to 0.50% by mass.

[0122] To the extent that it does not contradict the spirit of the present invention, the curable composition of the present invention may contain polymers or monomers other than the components described above, inorganic particles, dispersants, plasticizers, heat stabilizers, mold release agents, solvents, etc. As the solvent, the description of organic solvents in the [Method for Preparing the Curable Composition] below can be applied. The content of the solvent in the curable composition of the present invention is not particularly limited and can be, for example, 20% by mass or more, and can be appropriately set within a range that satisfies the content of each component described above. It is preferable to keep the content of inorganic particles in the curable composition to 30% by mass or less.

[0123] The viscosity of the curable composition of the present invention at 60°C is preferably less than 50 mPa·s, more preferably less than 35 mPa·s, even more preferably less than 30 mPa·s, and particularly preferably less than 25 mPa·s, from the viewpoint of improving handling when forming the cured product, particularly improving conformability to the mold when imprinting, and forming a higher quality cured product. There is no particular limit on the lower limit, but it is practical to have a value of 1 mPa·s or more. The viscosity of the above curable composition is measured using a rheometer (e.g., trade name: HAAKE RheoStress 6000, manufactured by Thermo Fisher Scientific) at a shear rate of 10s. －１ This is the viscosity measured under conditions of 60°C.

[0124] The curable composition of the present invention can be used in the production of cured products that require a high refractive index. In particular, the curable composition of the present invention is excellent in suppressing polymerization during storage and excellent in suppressing discoloration over time, so it can be preferably used as an imprinting material such as nanoimprint to produce cured products that exhibit a high refractive index.

[0125] [Method for preparing the curable composition] The method for preparing the curable composition of the present invention is not particularly limited, and it is sufficient to prepare it so that the curable composition of the present invention contains the above-mentioned thio(meth)acrylate monomer (T), piperidinyl oxy radical compound (N), and phenol compound (P). In preparing the curable composition of the present invention, the mixing of the thio(meth)acrylate monomer (T), piperidinyl oxy radical compound (N), and phenol compound (P) may be carried out in the presence of an organic solvent, and is preferably carried out in the presence of an organic solvent. For example, the curable composition of the present invention can be prepared by stirring and mixing the thio(meth)acrylate monomer (T), piperidinyl oxy radical compound (N), and phenol compound (P) in the presence of an organic solvent. When preparing a composition containing the above-mentioned monomers in high concentrations, the curable composition of the present invention can be prepared by removing the organic solvent from the mixed solution obtained after the above-mentioned stirring and mixing. The thio(meth)acrylate monomer (T) may be formulated as a solution containing the thio(meth)acrylate monomer (T). Furthermore, in the step of removing the organic solvent from the solution containing the thio(meth)acrylate monomer (T), the mixing stage of the phenol compound (P) and other components is not particularly limited, as long as the piperidinyl oxy radical compound (N) is contained in the solution together with the thio(meth)acrylate monomer (T). The phenol compound (P) and other components may be added simultaneously, for example, when mixing the thio(meth)acrylate monomer (T) and the piperidinyl oxy radical compound (N), or the mixture of the thio(meth)acrylate monomer (T) and the piperidinyl oxy radical compound (N) may be prepared first, and then the phenol compound (P) may be added to this mixture and mixed. For example, with respect to the photoradical polymerization initiator, it is preferable to prepare a mixture of the piperidinyl oxy radical compound (N) with the thio(meth)acrylate monomer (T), and then add it to this mixture and mix.Regarding organic solvents, those that dissolve monomers such as thio(meth)acrylate monomers (T) are preferred. Examples include hydrocarbon solvents such as aromatic hydrocarbon solvents such as toluene, halogenated hydrocarbon solvents such as chlorinated hydrocarbon solvents such as methylene chloride and chloroform, alcohol solvents such as methanol, ether solvents such as cyclic ether solvents such as tetrahydrofuran, epihalohydrin solvents such as epichlorohydrin, glycol ether acetate solvents such as (poly)alkylene glycol monoalkyl ether acetate, ester solvents such as ethyl acetate, amide solvents such as N,N-dimethylformamide, urea solvents, and the like. Furthermore, when the above-mentioned thio(meth)acrylate monomers (T) are incorporated as a solution during the preparation of the curable composition of the present invention, in addition to the above-mentioned organic solvents, solvents used in the purification of the above-mentioned thio(meth)acrylate monomers (T) and that can be contained in the solution of thio(meth)acrylate monomers (T), such as aliphatic hydrocarbon solvents such as hexane, may also be contained in the curable composition of the present invention. The removal of organic solvents can be carried out by conventional methods, for example, by distillation under heating and / or reduced pressure.

[0126] [Cured Product] The cured product of the present invention is a cured product obtained from the curable composition of the present invention, and is a cured product obtained by curing a curable composition containing the above-mentioned thio(meth)acrylate monomer (T), piperidinyl oxy radical compound (N), and phenol compound (P). The cured product of the present invention is obtained by the polymerization reaction of monomers containing the above-mentioned thio(meth)acrylate monomer (T) proceeding and curing. The cured product of the present invention may contain unreacted monomers (for example, the above-mentioned thio(meth)acrylate monomer (T), (meth)acrylic(thio) acid ester compound), etc. As described above, the cured product of the present invention can exhibit a high refractive index.

[0127] The refractive index of the cured product of the present invention can be evaluated using the refractive index (nD) at 25°C and a wavelength of 589 nm (in the present invention, also simply referred to as "refractive index nD of the cured product"). The refractive index nD of the cured product of the present invention can be 1.670 or higher, preferably 1.680 or higher, more preferably 1.690 or higher, and even more preferably 1.700 or higher. In the region where the refractive index nD of the cured product is 1.670 or higher, 10 times the refractive index nD of the cured product －３ Differences in order of magnitude result in differences in high refractive index performance when applied to optical components. There is no particular upper limit to the refractive index nD of the cured product of the present invention, but it is practical to have a value of 1.800 or less. The refractive index nD of the cured product is measured using an Abbe refractometer (for example, Atago Corporation, product name: Multi-wavelength Abbe Refractometer DR-M2 or DR-M4). Specifically, a measurement sample (cured product) can be prepared and measured according to the description in the examples below. When forming the cured product, a heating step may be used instead of the ultraviolet irradiation step described in the examples below, or both the heating step and the ultraviolet irradiation step may be used. Furthermore, JIS B 7090:1999 Optics and optical instruments - Reference wavelengths (ISO 7944:1998 Optics and optical instruments - Reference wavelengths) can be referenced as appropriate.

[0128] The transmittance of the cured product of the present invention is preferably 60% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more, across the entire visible light wavelength range of 410 to 830 nm. Furthermore, while there is no particular upper limit to the transmittance of the cured product of the present invention, it is practical to be 99% or less. In the present invention, the transmittance of the cured product is the external transmittance value including surface reflection, measured using an ultraviolet-visible spectrophotometer (for example, UV-2600 (product name), manufactured by Shimadzu Corporation) for a cured product with a thickness of 150 μm.

[0129] The shape and thickness of the cured product of the present invention can be appropriately adjusted according to the shape to which the cured product of the present invention is applied.

[0130] [Method for Manufacturing Cured Products] The cured products of the present invention can be manufactured by a method that includes a step of photocuring the curable composition described above. When photocuring is performed, it is preferable to include the above-mentioned photoradical polymerization initiator in the curable composition. The conditions for photocuring can preferably be those described below regarding the conditions for photopolymerization (photocuring). If the curable composition of the present invention contains a solvent, the cured products of the present invention can be obtained by removing the solvent from the curable composition of the present invention and then curing it. The solvent removal step may be performed simultaneously with the manufacture of the cured product, or beforehand, as long as it is possible to manufacture the cured product. For example, when the curable composition of the present invention is used as a spin-coating liquid and a cured product is manufactured by spin-coating and drying, the curable composition is used for spin-coating while containing the solvent, and the solvent is removed simultaneously with the manufacture of the cured product. Furthermore, in the imprint technology described below, the cured products of the present invention are manufactured using the curable composition of the present invention from which the solvent has been removed in advance.

[0131] In the method for producing a cured product of the present invention, it is preferable to obtain a cured product with the pattern of the mold transferred to it by light curing the curable composition of the present invention while pressing it onto a mold. From the viewpoint of release properties, it is preferable that the mold is surface-treated with chromium nitride. As for the surface treatment of the mold with chromium nitride, for example, the description of chromium nitride treatment in paragraph

[0108] of International Publication No. 2019 / 044863 can be applied as is, except that "metal mold" is read as "mold".

[0132] Figure 1 is a schematic cross-sectional view illustrating a method for manufacturing a cured product of the present invention using the curable composition of the present invention and imprint technology. The size, shape, and thickness of the substrate 3, the size, shape, transfer pattern, and thickness of the mold 5, and the amount of curable composition 1 used can be appropriately adjusted to obtain a cured product 7 having the desired size, shape, transferred pattern, and thickness. As shown in Figure 1, (a) first, the curable composition 1 is sandwiched between the mold 5 and the substrate 3; (b) the curable composition 1 is pressed into the mold 5 and photocured by ultraviolet irradiation (UV irradiation) to produce a cured product 7 with the pattern of the mold 5 transferred to it; and (c) the obtained cured product 7 and substrate 3 are released (peeled) from the mold 5 to produce the cured product 7. The ultraviolet irradiation is not particularly limited as long as the curable composition 1 is cured, and the irradiation may be applied from either side of the mold 5 or the substrate 3. It is preferable that the substrate 3 is transparent and that the irradiation is performed from the substrate 3 side. Furthermore, the resulting cured product 7 may be used in a form integrated with the substrate 3, or the substrate 3 may be peeled off and the cured product 7 may be used separately. The description of the transparent substrate in the diffractive optical element described later can preferably be applied to the substrate 3.

[0133] [Applications of the Cured Product] The cured product of the present invention can be used in a variety of applications and exhibits a high refractive index, making it particularly suitable for use in optical materials. In particular, the curable composition of the present invention used to obtain the cured product is less prone to discoloration over time, allowing for the fabrication of cured products with diverse microstructures ranging from nanometers to several hundred micrometers in size using imprint technology, etc., and is therefore particularly suitable for use in microlenses in micro-OLED (Organic Light Emitting Diode) displays, microlenses for image sensors, diffractive optical elements in augmented reality glasses (AR glasses) (preferably diffractive optical elements for waveguides), and the like.

[0134] [Diffractive Optical Element] The diffractive optical element of the present invention includes a cured product of the present invention, and preferably includes a surface having a diffraction grating shape formed with the cured product of the present invention, and is formed by curing the curable composition of the present invention. The diffractive optical element of the present invention preferably has a maximum thickness of 0.05 μm to 100 μm. The maximum thickness is more preferably 0.1 μm to 50 μm, and even more preferably 0.2 μm to 30 μm. The step difference (griddle thickness) of the diffraction grating shape (periodic structure) of the diffractive optical element is preferably 0.05 μm to 100 μm, more preferably 0.05 μm to 50 μm, and even more preferably 0.1 μm to 30 μm. Furthermore, the pitch of the diffraction grating shape of the diffractive optical element may be between 0.05 μm and 1 mm, and is also preferably 0.05 μm to 100 μm, and preferably varies within the same diffractive optical element according to the required optical aberration.

[0135] A diffractive optical element can be manufactured, for example, by the following procedure: A curable composition is sandwiched between the surface of a mold, such as a die, which has a surface processed into a diffraction grating shape, and a transparent substrate. After this, the curable composition may be pressed and stretched to a desired extent. While sandwiched, the curable composition is cured by irradiating it with light from the transparent substrate side. After that, the cured product is released from the mold, such as a die. After release, ultraviolet light may be irradiated from the side opposite to the transparent substrate.

[0136] Examples of the transparent substrates mentioned above include flat glass such as BK glass, and flat transparent resins (such as (meth)acrylic resin, polycarbonate resin, and polyethylene terephthalate resin). The surface of the transparent substrate may be subjected to surface treatment such as ozone treatment. The transparent substrate used in the above manufacturing may be included in the diffractive optical element as is, or it may be peeled off.

[0137] The following conditions are preferable for photopolymerization (photocuring). The light used for irradiating the curable composition is preferably ultraviolet light or visible light, and more preferably ultraviolet light. For example, metal halide lamps, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, germicidal lamps, xenon lamps, and LED (Light Emitting Diode) light source lamps are suitably used. The irradiance of the ultraviolet light used for irradiating the curable composition is 1 to 100 mW / cm². ２ Preferably, 1 to 75 mW / cm² ２ More preferably, 5 to 50 mW / cm² ２ This is even more preferable. Multiple exposures with ultraviolet light of different illuminances may be performed. The amount of ultraviolet light exposure should be 0.4 to 10 J / cm². ２ Preferably, 0.5 to 5 J / cm ２ More preferably, 1 to 3 J / cm ２ This is even more preferable. The atmosphere during light irradiation is preferably an air or inert gas purged atmosphere, and more preferably an atmosphere in which the air has been purged with nitrogen until the oxygen concentration is 1% or less.

[0138] By using the curable composition of the present invention as the imprinting material, pressing a mold having a desired nanometer to several hundred micrometer size pattern onto the material, and then photocuring it, a cured product of the present invention with the mold pattern transferred onto it can be produced, and then demolded to create a diffraction grating shape. Regarding the photocuring conditions, the descriptions in the above-mentioned method for producing the cured product and the descriptions regarding photopolymerization (photocuring) conditions can be applied. Aside from the above points, the commonly used descriptions of imprinting can be adopted without particular restriction, and for example, the Nanoimprint Technology Handbook (edited by the Nanoimprint Technology Research Group of the Japan Society of Applied Physics, published by Ohmsha, December 1, 2019) can be consulted.

[0139] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. In the following, room temperature means 25°C unless otherwise specified. "Hexane / ethyl acetate" means a mixed solvent of hexane and ethyl acetate. All processes from the preparation of the curable composition to the production of cured products or evaluation tests were carried out in an environment using yellow light as illumination. Furthermore, all processes from the synthesis of thio(meth)acrylate monomer (T) and the compound represented by general formula (a), to the preparation of the curable composition to the production of cured products or evaluation tests were carried out in air unless otherwise specified.

[0140] [Synthesis Example] The thio(meth)acrylate monomer (T) and the compound represented by general formula (a) were synthesized as follows.

[0141] [Synthesis Example 1: Synthesis of Compound (A-4)]

[0142] 5.00 g (26.0 mmol) of 1,6-naphthalenedithiol and 60 mL of N,N-dimethylacetamide (DMAc) were mixed while cooling until the internal temperature (liquid temperature) reached 0°C. 6.93 g (54.6 mmol) of 3-chloropropionyl chloride (3CPC) was added dropwise, ensuring the liquid temperature did not exceed 7°C, and then the mixture was heated until the internal temperature (liquid temperature) reached 25°C. After stirring for 1 hour, the mixture was cooled to 0°C, and triethylamine (Et) was added. ３N) 11.05 g (109.2 mmol) was added dropwise, ensuring the liquid temperature did not exceed 7°C, and then heated until the internal temperature (liquid temperature) reached 25°C. After stirring for 1 hour, 150 mL of ethyl acetate and 150 mL of 1N hydrochloric acid were added for washing and separation. Next, 80 mL of 5% sodium bicarbonate aqueous solution was added and stirred, followed by washing and separation. Dehydration with magnesium sulfate, filtration, and partial removal of the solvent were performed to concentrate the mixture and obtain an oily composition. This was then purified by hexane / ethyl acetate column chromatography to obtain a hexane / ethyl acetate solution of compound (A-4). The solid content concentration of the obtained solution was measured, confirming that 6.3 g of compound (A-4) was obtained. Yield: 81%. Compound (A-4) １ H-NMR (300MHz, CDCl ３ ): δ (ppm) 5.8-5.9 (m, 2H), 6.3-6.6 (m, 4H), 7.6-7.7 (m, 2H), 7.78 (d, 1H), 7.96 (d, 1H), 8.05 (s, 1H), 8.21 (d, 1H)

[0143] [Synthesis Example 2: Synthesis of Compound (A-8)] Compound (A-8), described below, was synthesized in the same manner as in Synthesis Example 1, except that 1,6-naphthalenedithiol was replaced with 2,7-naphthalenedithiol. Yield: 80%. Compound (A-8) １ H-NMR (300MHz, CDCl ３ ): δ (ppm) 5.8-5.9 (m, 2H), 6.3-6.6 (m, 4H), 7.5-7.6 (m, 2H), 7.92 (d, 2H), 7.98 (s, 2H)

[0144] [Synthesis Example 3: Synthesis of compounds (A-38), (A-46), (A-4), and (a-30)]

[0145] <Synthesis of compounds (A-38A), (A-46A), (A-4A), and (a-30)> Under a nitrogen atmosphere, 10 g (52.0 mmol) of 1,6-naphthalenedithiol, 4.68 g (52.0 mmol) of dimethyl carbonate (DMC), and 30 mL of N,N-dimethylacetamide (DMAc) were mixed. Then, 8.62 g (52.0 mmol) of potassium carbonate was added, and the mixture was heated to an internal temperature (liquid temperature) of 50°C. After stirring for 3 hours, 100 mL of ethyl acetate and 100 mL of 2N hydrochloric acid were added for washing and separation. Next, 100 mL of 2N hydrochloric acid was added again for washing and separation. 100 mL of 15% sodium chloride aqueous solution was added and stirred, then washed and separated. By dehydration with magnesium sulfate and filtration, an ethyl acetate solution containing compounds (A-38A), (A-46A), (A-4A), and (a-30) was obtained. The solid content concentration of the obtained solution was measured, and it was confirmed that the original ethyl acetate solution contained 14.0 g each of compounds (A-38A), (A-46A), (A-4A), and (a-30). Yield: 90%.

[0146] <Synthesis of compounds (A-38), (A-46), and (A-4)> A solution of 14.0 g (67.8 mmol) of a mixture containing the above compounds (A-38A), (A-46A), (A-4A), and (a-30) was mixed with 3 mL of N,N-dimethylacetamide (DMAc) and cooled to 0°C. 9.91 g (78.0 mmol) of 3-chloropropionyl chloride (3CPC) was added dropwise so that the liquid temperature did not exceed 7°C, and then the mixture was heated to 25°C. After stirring for 1 hour, it was cooled to 0°C and triethylamine (Et) was added. ３N) 16.5 g (163 mmol) was added dropwise so that the liquid temperature did not exceed 7°C, and then heated until the internal temperature (liquid temperature) reached 25°C. After stirring for 1 hour, 56 mL of ethyl acetate and 98 mL of 1N hydrochloric acid were added for washing and separation. Next, 56 mL of 1N hydrochloric acid was added again for washing and separation. Then, 56 mL of 5% sodium bicarbonate aqueous solution was added and stirred, followed by washing and separation. After dehydration with magnesium sulfate and filtration, and partial removal of the solvent for concentration, the solution was purified by column chromatography using hexane / ethyl acetate, and compounds (A-38), (A-46), (A-4), and (a-30) were isolated as hexane / ethyl acetate solutions. The solid content concentration of the obtained solutions was measured, and the yield of each compound was calculated. Compound (A-38): yield 20%, Compound (A-46): yield 25%, Compound (A-4): yield 20%, Compound (a-30): yield 20%. Compound (A-38) １ H-NMR (300MHz, CDCl ３ ): δ (ppm) 2.58 (s, 3H), 5.8-5.9 (m, 1H), 6.3-6.6 (m, 2H), 7.4-7.6 (m, 2H), 7.6-7.7 (m, 2H), 7.85 (d, 1H), 8.03 (d, 1H) Compound (A-46) １ H-NMR (300MHz, CDCl ３ ): δ (ppm) 2.58 (s, 3H), 5.8-5.9 (m, 1H), 6.3-6.6 (m, 2H), 7.4-7.6 (m, 3H), 7.6-7.7 (m, 1H), 7.98 (s, 1H), 8.33 (d, 1H) Compound (A-4) １ H-NMR (300MHz, CDCl ３ ): δ (ppm) 5.8-5.9 (m, 2H), 6.3-6.6 (m, 4H), 7.6-7.7 (m, 2H), 7.78 (d, 1H), 7.96 (d, 1H), 8.05 (s, 1H), 8.21 (d, 1H)

[0147] [Synthesis Example 4: Synthesis of Compound (B-6)] Compound (B-6), described below, was synthesized based on the description in Synthesis Example 5: Synthesis of Compound (A-6) of International Publication No. 2024 / 128266, and was obtained as a hexane / ethyl acetate solution of Compound (B-6) by purification in the same manner as in Synthesis Example 1 above.

[0148] [Preparation of Curable Compositions] The main monomer and polymerization inhibitor were dissolved in ethyl acetate to obtain the compositions shown in Tables 1-1 to 1-3 below (hereinafter collectively referred to as "Table 1"). The mixture was then concentrated at 70°C under reduced pressure of 40 hPa until the solvents (ethyl acetate and hexane) were gone. An antioxidant and a photopolymerization initiator were added to the resulting concentrate, and the mixture was heated and stirred at 70°C for 15 minutes until homogenized to prepare the curable compositions. In the above preparation, the main monomer synthesized in the [Synthesis Example] was incorporated as the ethyl acetate / hexane solution obtained in the [Synthesis Example]. Curable compositions No. 101 to 118 are the curable compositions of the present invention, and curable compositions No. c11 to c17 are curable compositions for comparison.

[0149] The transmittance and refractive index of the cured product were measured for the curable composition as follows. Furthermore, the polymerization inhibition effect and the effect of inhibiting discoloration over time were evaluated as follows, and the results are summarized in Table 1.

[0150] [Measurement of transmittance and refractive index] (1) Preparation of cured material The curable composition prepared above is sandwiched between hydrophobic treated glass plates so that the film thickness of the cured material is 150 μm, and UV irradiation is performed using an EXECURE 3000 (product name), manufactured by HOYA CANDEO OPTRONICS, so that the oxygen concentration is 1% or less, and nitrogen (N ２ Under the substituted atmosphere, the integrated light intensity was 1.2 J / cm². ２ , illuminance 5mW / cm ２After UV (ultraviolet) irradiation under the above conditions, the material was peeled off the glass plate and a cured product was prepared. The transmittance (external transmittance including surface reflection) of the cured products of curable compositions No. 101 to 118 with a film thickness of 150 μm, measured using a UV-Vis spectrophotometer (e.g., UV-2600 (product name), manufactured by Shimadzu Corporation), showed a high transmittance that was acceptable for use as a lens. (2) Measurement of refractive index Using the cured products prepared under the above conditions, the refractive index (refractive index nD of the cured product) at a wavelength of 589 nm was measured at 25°C using a multi-wavelength Abbe refractometer DR-M2 or DR-M4 (product name, manufactured by Atago Corporation). The refractive index nD of the cured products obtained from curable compositions No. 101 to 118 was all 1.690 or higher.

[0151] [Evaluation 1: Polymerization Inhibition Effect] 30 mg of the curable composition prepared above was weighed into a 1 cm diameter test tube, dissolved in 1 mL of ethyl acetate or methanol, and the turbidity of the solution was visually observed to evaluate the polymerization inhibition effect according to the following criteria. Note that the more insoluble components (high molecular weight components) there are in ethyl acetate or methanol, the stronger the turbidity of the solution. - Evaluation Criteria for Polymerization Inhibition Effect - A: No turbidity occurred in either dilution with ethyl acetate or methanol, and the solution was transparent. B: No turbidity occurred in dilution with ethyl acetate, and the solution was transparent, but slight turbidity occurred in dilution with methanol. C: Slight turbidity occurred in either dilution with ethyl acetate or methanol. D: Slight turbidity occurred in dilution with ethyl acetate, and strong turbidity occurred in dilution with methanol. E: Strong turbidity occurred in either dilution with ethyl acetate or methanol.

[0152] [Evaluation 2: Effect of suppressing discoloration over time] The curable composition prepared above was sandwiched between glass slides to a thickness of 150 μm, and the transmittance T at 420 nm was measured. １ The following was measured. Subsequently, the curable composition was stored at 50°C in air for 7 days, then sandwiched between glass slides to a thickness of 150 μm, and the transmittance T at 420 nm was measured. ２ The following was measured: Change in transmittance before and after time: ΔT% = T １ -T ２Based on the above, the effect of suppressing discoloration over time was evaluated according to the following criteria. Transmittance is the external transmittance value including surface reflection, measured using a UV-Vis spectrophotometer (UV-2600 (product name), manufactured by Shimadzu Corporation). - Evaluation criteria for the effect of suppressing discoloration over time - A: 0% ≤ ΔT% < 1% B: 1% ≤ ΔT% < 2% C: 2% ≤ ΔT% < 3% D: 3% ≤ ΔT% < 4% E: 4% ≤ ΔT% < 5% F: 5% ≤ ΔT%

[0153]

[0154]

[0155]

[0156] The wt% listed in the column for each component means mass%. A "-" in the column for each component indicates that the component is not contained. The ratio of each component listed in the column for the main monomer means the content ratio of each compound that makes up the main monomer, and wt% means mass%. If the main monomer is a mixture of two or more compounds, the content ratio of each compound is listed in the order of the compounds listed in the column for each type. For example, in No. 105, it is indicated that the main monomer is composed of A-38 at 33.4 wt%, A-46 at 33.3 wt%, and A-4 at 33.3 wt%. The "value of antioxidant / polymerization inhibitor ratio" means the value of the ratio of the content of the component listed in the antioxidant column to the content of the component listed in the polymerization inhibitor column. In Nos. 101 to 118, this corresponds to the value of the ratio of the content of phenol compound (P) to the content of piperidinyl oxy radical compound (N). If the product contains only one of the antioxidant or polymerization inhibitor components, enter "-" in the "Ratio of antioxidant / polymerization inhibitor" column. In the case of curable composition No. c15, as described in the above [Preparation of curable composition], discoloration and gelation due to polymerization occurred immediately after adding the antioxidant to the concentrate of the solution containing the main monomer and polymerization inhibitor. Therefore, for curable composition No. c15, the polymerization inhibition effect is rated "E", and the effect of inhibiting discoloration over time could not be evaluated, so it is marked "Not rated".

[0157] The components in the table are as follows: Main monomer: This refers to the following thio(meth)acrylate monomer (T) or compound represented by general formula (a). Note that although the compound represented by general formula (a) is not a monomer, the ratio of each component of the main monomer and the content of the main monomer are calculated including the compound represented by general formula (a) as a component of the main monomer.

[0158] (A compound represented by thio(meth)acrylate monomer (T) or general formula (a))

[0159] Compound (a-30) used was 16DMNDSH (trade name) manufactured by Sugai Chemical Industry Co., Ltd.

[0160] Polymerization inhibitor: Indicates the following piperidinyl oxy radical compound (N) or comparative compound.

[0161] (Piperidinyl oxy radical compound (N)) Note that OH-TEMPO shown below will be written as OHTEMPO in the table.

[0162] (Comparative compound) Q-1301: Trade name, structure shown below, a nitrosamine-based polymerization inhibitor manufactured by Fujifilm Wako Pure Chemical Industries.

[0163] Antioxidant: Indicates the following phenolic compound (P) or comparative compound.

[0164] (Phenol compound (P))

[0165] (Comparative compounds) Trihexyl phosphite: Phosphorus-based antioxidant PEMP: Sulfur-based antioxidant (structure shown below) Camphor sulfonic acid: Acid compound (structure shown below). Although it is not an antioxidant, it is listed in the antioxidant section for convenience.

[0166] (Photopolymerization initiator) IrgTPO: Irgacure TPO (trade name, manufactured by BASF Japan, available as Omnirad TPO H (trade name, manufactured by IGM Resins B.V.)), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide

[0167] From the results in Table 1, the following can be seen. As shown in comparative curable compositions No. c12 and c14, in compositions that do not contain the polymerization inhibitor piperidinyl oxy radical compound (N), monomer polymerization during concentration is not suppressed. Also, as shown in comparative curable compositions No. c11 and c13, in compositions that contain piperidinyl oxy radical compound (N) but do not contain the antioxidant phenol compound (P), discoloration of the composition over time occurred due to the oxidized form of piperidinyl oxy radical compound (N). Comparative curable composition No. c15 is not a curable composition of the present invention because it contains a phosphorus-based antioxidant instead of a phenol compound (P) as the antioxidant. In comparative curable composition No. c15, in the above-described [Preparation of Curable Composition], a reaction occurred immediately after adding the phosphorus-based antioxidant to the concentrate of the solution containing the main monomer and the polymerization inhibitor piperidinyl oxy radical compound (N), resulting in discoloration and gelation due to polymerization, and monomer polymerization was not suppressed. Furthermore, comparative curable composition No. c16 is not a curable composition of the present invention because it contains a sulfur-based antioxidant instead of a phenol compound (P) as an antioxidant. This comparative curable composition No. c16 underwent discoloration over time. For reference, a comparative example containing a sulfonic acid compound and a nitroso polymerization inhibitor, as described in International Publication No. 2014 / 061687 as a means to improve the storage stability of compositions for the enthiol reaction, is shown as curable composition No. c17. Curable composition No. c17 of this comparative example did not suppress monomer polymerization during concentration, and also underwent discoloration over time. In contrast, curable compositions No. 101 to 118 of the present invention are compositions in which monomer polymerization during concentration is suppressed, and furthermore, despite containing a piperidinyl oxy radical compound (N), the compositions hardly underwent discoloration over time.Furthermore, curable compositions in which the content of piperidinyl oxy radical compound (N) is 0.0050 to 0.1000% by mass and the content of phenol compound (P) is 0.0500 to 0.3000% by mass in 100% by mass of solid content of the curable composition, and the ratio of the content of phenol compound (P) to the content of piperidinyl oxy radical compound (N) is 1.0 to 60, achieved a higher level of suppression of monomer polymerization during concentration and suppression of coloration of the composition over time (curable compositions No. 103 to 109, 111 to 113, 116 and 117 compared to curable compositions No. 101, 102, 110, 114, 115 and 118).

[0168] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0169] This application claims priority based on Japanese Patent Application No. 2024-169651, filed in Japan on 27 September 2024, the contents of which are incorporated herein by reference as part of this specification.

[0170] 1. Curable composition 3. Substrate 5. Mold 7. Cured product

Claims

A curable composition comprising a thio(meth)acrylate monomer containing an aromatic hydrocarbon ring, a compound containing a piperidinyl oxy radical structure, and a phenol compound. 　 The curable composition according to claim 1, wherein, in 100% by mass of the solid content of the curable composition, the content of the compound containing the piperidinyl oxy radical structure is 0.0050 to 0.1000% by mass, the content of the phenol compound is 0.0500 to 0.3000% by mass, and the ratio of the content of the phenol compound to the content of the compound containing the piperidinyl oxy radical structure is 1.0 to 60. 　 The curable composition according to claim 1, wherein the thio(meth)acrylate monomer containing the aromatic hydrocarbon ring is represented by the following general formula (A) or (B). In the above formula, R ａ ~R ｈ R represents a hydrogen atom, an alkylsulfanyl group having 1 to 10 carbon atoms, or a (meth)acryloylthiooxy group. However, R ａ ~R ｈ At least one of them is a (meth)acryloylthiooxy group. In the above formula, R ５ R represents a group containing an arylene group and an S atom, and L represents a single bond or a methylene group. ６ R represents a hydrogen atom or a methyl group. ５ It may further have a (meth)acryloylthiooxy group. 　 The curable composition according to claim 1, for use in imprinting. 　 A cured product obtained from the curable composition according to any one of claims 1 to 4. 　 An optical material comprising the cured product described in claim 5. 　 A microlens or diffractive optical element comprising the cured product described in claim 5.

Images