Curable composition, cured product, optical material, diffractive optical element, and monofunctional (meth) acrylic acid thioester monomer

Abstract

The present invention provides a curable composition, a cured product using the curable composition, an optical material, and a diffractive optical element, a monofunctional thioester (meth) acrylate monomer represented by general formula (1), and a curable composition containing the monofunctional thioester (meth) acrylate monomer, the curable composition contains a monofunctional (meth) acrylic acid thioester monomer represented by general formula (1) and a bifunctional (meth) acrylic acid thioester monomer. In the formula, R1 represents an arylene group and an S-atom-containing group, L represents a single bond or a methylene group, and R2 represents a hydrogen atom or a methyl group. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a curable composition, a cured product, an optical material, a diffractive optical element, and a monofunctional (meth)acrylic acid thioester monomer. Background Art

[0002] In recent years, in-depth studies have been conducted on optical resins expected to be applied to optical components such as diffractive optical elements that require a high refractive index, and monomers that exhibit a high refractive index as raw materials for optical resins have also been developed.

[0003] For example, Patent Document 1 describes a polymerizable compound having a specific structure, which has 1 to 3 arylthio groups and 1 polymerizable group on a benzene ring, and has a refractive index n at 25 °C D of 1.650 or more.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-37693 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] There is known a microfabrication technique called imprint technology in which a mold having various patterns with a size of nanometers to several hundreds of micrometers is imprinted on a material such as resin and the pattern is transferred to the surface of the material.

[0009] In order to transfer the fine pattern of nanometer to several hundreds of micrometers formed on the mold to the material such as resin to be imprinted with high precision, it is required that the above material does not contain inorganic particles and has a low viscosity.

[0010] Imprinting includes steps of coating a material on a substrate, pressing in a state of imprinting a mold, fixing the transferred pattern by light or heat curing, and demolding. In order to be temporarily stored in a tank until the above imprinting step is performed, like ink in inkjet, the material used in imprinting is required not to precipitate crystals or become cloudy in the storage tank (hereinafter, also referred to as "stability over time").

[0011] Moreover, although compounds having an aromatic ring in the molecular structure are expected to have a high refractive index, they often exhibit a high viscosity. From the viewpoint of application to imprinting, it is required to achieve both a high refractive index and a low viscosity at a high level.

[0012] In addition, from the viewpoint of accurately manufacturing an optical material having a desired fine structure pattern by imprint technology, it is also important that the resin does not break when demolding from the mold.

[0013] As a result of investigations by the present inventors, the following was found: In the polymerizable compounds described in Patent Document 1, when a curable composition containing a polymerizable compound, a polymerization initiator, a monomer for dilution, etc. is prepared, resin chipping easily occurs during demolding from a mold, crystal precipitation and / or turbidity easily occur in the composition, and it cannot be said that the balance between the high refractive index of the cured product and the low viscosity of the composition is sufficient.

[0014] An object of the present invention is to provide a curable composition capable of obtaining a cured product in which resin chipping during demolding from a mold hardly occurs, showing excellent stability over time in the state of the curable composition before the curing reaction, having a low viscosity, and further enabling high refractive index of the obtained cured product. And an object of the present invention is to provide a cured product obtained from the curable composition, an optical material and a diffractive optical element containing the cured product, and a monomer contained in the curable composition.

[0015] Means for Solving the Technical Problem

[0016] The above problems of the present invention are solved by the following method.

[0017] <1>

[0018] A curable composition containing:

[0019] A monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (1); and

[0020] A difunctional (meth)acrylic acid thioester monomer,

[0021] [Chemical formula 1]

[0022]

[0023] In the above formula, R 1 represents an arylene group and a group containing an S atom, L represents a single bond or a methylene group, and R 2 represents a hydrogen atom or a methyl group.

[0024] <2>

[0025] The curable composition according to <1>, wherein

[0026] the liquid refractive index nD at 25 °C is 1.650 or more.

[0027] <3>

[0028] The curable composition according to <1> or <2>, wherein

[0029] The monofunctional (meth)acrylic acid thioester monomer represented by the above general formula (1) includes the monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (2).

[0030] [Chemical formula 2]

[0031]

[0032] In the above formula, the meanings of L and R 2 are the same as those of the above L and R 2 .

[0033] <4>

[0034] The curable composition according to any one of <1> to <3>, wherein

[0035] the monofunctional (meth)acrylic acid thioester monomer represented by the above general formula (1) includes the monomer in which L in the above general formula (1) is a single bond.

[0036] <5>

[0037] The curable composition according to <3>, wherein

[0038] the monofunctional (meth)acrylic acid thioester monomer represented by the above general formula (1) includes the monomer in which at least one of the bonding position of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the above general formula (2) is the meta position and L is a single bond.

[0039] <6>

[0040] The curable composition according to <5>, wherein

[0041] the monofunctional (meth)acrylic acid thioester monomer represented by the above general formula (1) includes the monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (3).

[0042] [Chemical formula 3]

[0043]

[0044] In the above formula, the meaning of R 2 is the same as that of the above R 2 .

[0045] <7>

[0046] The curable composition according to any one of <1> to <6> is used for imprinting.

[0047] <8>

[0048] A cured product which is a cured product of the curable composition according to any one of <1> to <7>.

[0049] <9>

[0050] An optical material containing the cured product described in <8>.

[0051] <10>

[0052] A diffractive optical element containing a surface having a diffractive grating shape formed from the cured product described in <8>.

[0053] <11>

[0054] A monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (1),

[0055] [Chemical formula 4]

[0056]

[0057] In the above formula, R 1 represents an arylene group and a group containing an S atom, L represents a single bond or a methylene group, and R 2 represents a hydrogen atom or a methyl group.

[0058] <12>

[0059] A curable composition containing the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) described in <11>.

[0060] In the present invention, when there are a plurality of substituents or linking groups etc. represented by specific symbols or formulas (hereinafter referred to as substituents etc.), 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 expression "each independently", each of the substituents etc. may be the same as or different from each other). This is the same for the definition of the number of substituents etc. Also, when a plurality of substituents etc. are close (especially when adjacent), unless otherwise specified, they may be connected to each other to form a ring. And unless otherwise specified, a ring, such as an alicyclic ring, an aromatic ring, or a heterocyclic ring, may be further condensed to form a fused ring.

[0061] In the present invention, unless otherwise specified, regarding a double bond, when there are E-type and Z-type in the molecule, it may be either one, and it may also be a mixture of them.

[0062] And, in the present invention, unless otherwise specified, when a compound has one or two or more asymmetric carbons, regarding the stereochemistry of such asymmetric carbons, either the (R)-form or the (S)-form can be independently adopted for each. As a result, the compound may be a mixture of stereoisomers such as optical isomers or diastereomers, or it may be a racemate.

[0063] Also, in the present invention, the display of the compound and the monomer means the compound and the monomer that include a part of the structure changed within the range not impairing the effects of the present invention. In addition, regarding the compound and the monomer that are not explicitly described as substituted or unsubstituted in words, it means that they can have any substituent within the range not impairing the effects of the present invention. For example, in the monomer represented by the general formula (1), the benzene ring having R 1 and -L-S-C(=O)C(R 2 )=CH2 may be unsubstituted or may have any substituent. As the any substituent, there may be mentioned any one of linear, branched and cyclic saturated or unsaturated aliphatic hydrocarbon groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, alkoxy groups, alkylthio groups, aryloxy groups, arylthio groups, halogen atoms, etc. From the viewpoint of the imprinting use, it is preferably unsubstituted, or when having a substituent, the substituent is a halogen atom.

[0064] In the present invention, regarding the substituent that is not explicitly described as substituted or unsubstituted (the same applies to the linking group and the ring), it means that it can have any substituent on the group within the range not impairing the desired effects. For example, in the case of being called "alkyl", it means including both unsubstituted alkyl and substituted alkyl.

[0065] In the present invention, when specifying the number of carbon atoms of a certain group, unless otherwise specifically stated in the present invention or this specification, the number of carbon atoms refers to the total number of carbon atoms of the entire group. That is, in the case where the group is in a form further having a substituent, it refers to the total number of carbon atoms including the substituent.

[0066] In the present invention, the numerical range represented by "~" means the range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0067] In the curable composition of the present invention, each component can be used singly or two or more kinds can be used in combination. The same applies to the cured product, the optical material and the diffractive optical element obtained from the curable composition of the present invention.

[0068] In the present invention, "(meth)acrylate" means either or both of acrylate and methacrylate, "(meth)acrylic acid" means either or both of acrylic acid and methacrylic acid, and "(meth)acryloyl" means either or both of acryloyl and methacryloyl. The monomer in the present invention is distinguished by oligomer, polymer and molecular weight, and a compound having a weight average molecular weight of 1000 or less is called a monomer.

[0069] In the present invention, when called alkyl, it means a linear or branched alkyl.

[0070] The number of carbon atoms as the alkyl group is preferably 1 to 20, more preferably 1 to 10, still more preferably 1 to 7, and particularly preferably 1 to 5.

[0071] Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, 1-methylbutyl, 3-methylbutyl, hexyl, 1-methylpentyl, 4-methylpentyl, heptyl, 1-methylhexyl, 5-methylhexyl, 2-ethylhexyl, octyl, 1-methylheptyl, nonyl, 1-methyloctyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, etc. Among these, methyl or ethyl is preferred.

[0072] The same applies to the alkyl group in the group containing an alkyl group (alkoxy, alkylthio, alkoxycarbonyl, acyl, acyloxy, etc.).

[0073] Moreover, the alkyl group may have a substituent. Examples of such an alkyl group having a substituent include halogenated alkyl and hydroxyalkyl.

[0074] In the present invention, the alkylene group can be exemplified by a group obtained by removing one hydrogen atom bonded to a carbon atom in the above alkyl group, and can be a linear alkylene group or a branched alkylene group. Examples include ethylene, propylene, butylene, etc.

[0075] In the present invention, the monovalent aromatic hydrocarbon group represents a monovalent group obtained by removing an arbitrary hydrogen atom from an aromatic hydrocarbon ring which may be a monocyclic or a fused ring. As the monovalent aromatic hydrocarbon group, an aromatic hydrocarbon group having 6 to 14 carbon atoms is preferred. Examples include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, 9-phenanthryl, etc. Among these, phenyl is preferred.

[0076] In the present invention, the divalent aromatic hydrocarbon group (arylene group) represents a divalent group obtained by removing an arbitrary hydrogen atom from the above monovalent aromatic hydrocarbon group. Examples of the divalent aromatic hydrocarbon group include phenylene, naphthylene, phenanthrylmethylene, etc. Among them, phenylene is preferred, and 1,3-phenylene or 1,4-phenylene is more preferred.

[0077] In the present invention, examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom.

[0078] Advantages of the Invention

[0079] The curable composition of the present invention can obtain a cured product that exhibits excellent stability over time and is less likely to cause resin fragmentation when demolded from a mold, and can achieve both a low viscosity of the curable composition and a high refractive index of the obtained cured product at an excellent level. The cured product, optical material, and diffractive optical element of the present invention can exhibit a high refractive index. The monofunctional (meth)acrylic acid thioester monomer of the present invention can obtain the curable composition of the present invention that exhibits the above excellent characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 It is a schematic cross-sectional view showing a method for manufacturing a cured product of the present invention by an imprint technique using the curable composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0081] [Curable Composition]

[0082] The curable composition of the present invention contains a monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) and a difunctional (meth)acrylic acid thioester monomer.

[0083] The curable composition of the present invention refers to a composition having curability and capable of obtaining a cured product (resin) through a curing reaction.

[0084] The monofunctional (meth)acrylic acid thioester monomer contained in the curable composition of the present invention is such that the (meth)acryloylthio group is connected to the benzene ring by a single bond or a methylene group represented by L as shown in the following general formula (1), and has an arylene group represented by R 1 and a group containing an S atom as substituents on the benzene ring.

[0085] By having the above specific chemical structure, when the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) is made into a curable composition, a cured product can be obtained that exhibits excellent stability over time in the state of the curable composition before the curing reaction and realizes suppression of resin fragmentation when demolded from a mold, and can achieve both a low viscosity of the curable composition and a high refractive index of the obtained cured product at a high level. Further, the curable composition of the present invention containing the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) and the difunctional (meth)acrylic acid thioester monomer can obtain a cured product in which the generation of resin fragmentation when demolded from a mold can be suppressed to a sufficiently low level.

[0086] Hereinafter, the components contained in the curable composition of the present invention will be described in turn.

[0087] <Monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1)>

[0088] The curable composition of the present invention contains a monofunctional (meth)acrylic thioester monomer represented by the following general formula (1) (hereinafter, also simply referred to as "the monomer represented by general formula (1)").

[0089] [Chemical formula 5]

[0090]

[0091] In the above formula, R 1 represents an arylene group and a group containing an S atom, L represents a single bond or a methylene group, and R 2 represents a hydrogen atom or a methyl group.

[0092] R 1 represents an arylene group and a group containing an S atom.

[0093] In the present invention, "arylene group and group containing an S atom" means that R 1 is an arylene group and a group containing an S atom, and there are no particular restrictions on other structures as long as the effects of the present invention can be exerted.

[0094] The S atom contained in R 1 is contained in the form of a thioether bond represented by -S-. However, R 1 will not have a structure formed by connecting two or more S atoms (disulfide structure or polysulfide structure formed by connecting three or more S atoms).

[0095] R 1 only needs to contain one or more S atoms. For example, it is preferably 1 to 4, more preferably 2 to 4, still more preferably 2 to 3, and particularly preferably 2.

[0096] Examples of the arylene group contained in R 1 include a phenylene group composed of a monocyclic aromatic hydrocarbon ring and an arylene group composed of a fused aromatic hydrocarbon ring of two or more rings, and a phenylene group is preferred.

[0097] R 1 only needs to contain one or more arylene groups. For example, it is preferably 1 to 2, and more preferably 1.

[0098] R 1 The arylene group contained in may be unsubstituted or may have a substituent within the range that does not impair the effects of the present invention. Examples of the substituent that the arylene group contained in R 1 may have include a halogen atom, a thioalkyl group, an alkylthioalkyl group, and a halogen atom is preferred.

[0099] In addition, R 1The arylene contained in [compound name] having a substituent means that the substituent is present at a position other than the two bonding bonds in the arylene. For example, R 1 The 1,3-phenylene contained in [compound name] having a substituent means that the substituent is present at any one of the positions 2, 4 to 6 other than the two bonding bonds in the phenylene.

[0100] R 1 The number of carbon atoms of the alkylthio group that the arylene contained in [compound name] can have is preferably 1 to 6, more preferably 1 to 4, still more preferably 1 or 2, and particularly preferably 1.

[0101] In the case where the arylene contained in R 1 has a substituent, 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 still more preferably 1.

[0102] Among them, the arylene contained in R 1 is preferably unsubstituted or has a halogen atom as a substituent, and more preferably is unsubstituted.

[0103] R 1 may contain a structure other than the above arylene and S atom. For example, it preferably contains an alkylene structure.

[0104] R 1 The number of carbon atoms of the alkylene that can be contained is preferably 1 to 6, more preferably 1 to 4, still more preferably 1 or 2, and particularly preferably 1.

[0105] R 1 The alkylene structure that can be contained may be unsubstituted or may have a substituent within the range that does not impair the effects of the present invention. As the substituent that the alkylene structure that R 1 can contain, for example, a halogen atom, a thioalkyl group, and an alkylthio group can be mentioned, and a halogen atom is preferred.

[0106] In addition, the alkylene contained in R 1 having a substituent means that the substituent is present at a position other than the two bonding bonds in the alkylene.

[0107] As the alkylthio group that the alkylene structure that R 1 can contain, the description of the alkylthio group that the arylene contained in the above R 1 can have can be preferably applied.

[0108] Among them, the alkylene structure that R 1 can contain is preferably unsubstituted or has a halogen atom as a substituent, and more preferably is unsubstituted.

[0109] In addition, R1 is a monovalent group. Therefore, by containing an arylene group and an S atom, it has an H atom at the other end of the arylene group, -S-, or alkylene group that is the terminal part of R 1 For example, if monomer A-1 represented by the general formula (1) in the following examples is used for explanation, R 1 is a group having an H atom on the methylene group in -S-phenylene-S-methylen-.

[0110] The total number of atoms other than the hydrogen atoms constituting R 1 is preferably 7 to 20, more preferably 9 to 18, still more preferably 9 to 15, particularly preferably 9 to 11, and most preferably 9.

[0111] As R 1 , a group represented by -S-arylene-S-alkylene-H or a group represented by -S-arylene-S-arylene-S-alkylene-H is preferred, a group represented by -S-arylene-S-alkylene-H is more preferred, a group represented by -S-phenylene-S-alkylene-H is still more preferred, and a group represented by -S-phenylene-S-methylen-H is particularly preferred.

[0112] L represents a single bond or a methylene group. In addition, the methylene group refers to a group represented by >CH2.

[0113] From the viewpoint of further increasing the liquid refractive index nD of the curable composition of the present invention and the refractive index nD of the cured product obtained by curing the curable composition of the present invention, L is preferably a single bond.

[0114] Therefore, the monomer represented by the above general formula (1) preferably contains a monomer in which L in the above general formula (1) is a single bond.

[0115] The content of the monomer in which L in the monomer represented by the above general formula (1) is a single bond is preferably 35% by mass or more, more preferably 50% by mass or more, still more preferably 65% by mass or more, particularly preferably 80% by mass or more, and may be 100% by mass.

[0116] R 2 represents a hydrogen atom or a methyl group.

[0117] From the viewpoint of further increasing the liquid refractive index nD of the curable composition of the present invention and the refractive index nD of the cured product obtained by curing the curable composition of the present invention, R 2 is preferably a hydrogen atom.

[0118] Therefore, the monomer represented by the above general formula (1) preferably contains a monomer in which R 2 in the above general formula (1) is a hydrogen atom.

[0119] In the monomer represented by the above general formula (1), R in the above general formula (1) 2 The content of the monomer that is a hydrogen atom is preferably 35% by mass or more, more preferably 50% by mass or more, still more preferably 65% by mass or more, particularly preferably 80% by mass or more, and may be 100% by mass.

[0120] In general formula (1), regarding the relationship between the bonding position of R 1 and the bonding position on the benzene ring of L, relative to the bonding position of R 1 L can be bonded to any of the ortho, meta, and para positions, and is preferably bonded to the meta position.

[0121] From the viewpoint of further increasing the liquid refractive index nD of the curable composition of the present invention and the refractive index nD of the cured product obtained by curing the curable composition of the present invention, the monomer represented by the above general formula (1) preferably contains a monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (2) (hereinafter, also simply referred to as "the monomer represented by general formula (2)").

[0122] [Chemical formula 6]

[0123]

[0124] In the above formula, the meanings of L and R 2 are the same as the meanings of L and R in the above general formula (1). 2 are the same.

[0125] That is, L is preferably a single bond, and R 2 is preferably a hydrogen atom.

[0126] The content of the monofunctional (meth)acrylic acid thioester monomer represented by the above general formula (2) in the monomer represented by the above general formula (1) is preferably 35% by mass or more, more preferably 50% by mass or more, still more preferably 65% by mass or more, particularly preferably 80% by mass or more, and may be 100% by mass.

[0127] The bonding position of L on the benzene ring relative to the bonding position of -S-phenylene-S-CH3 on the benzene ring on the right side in general formula (2) can be any of the ortho, meta, and para positions, and is preferably the meta position.

[0128] Moreover, the bonding position of -S-CH3 on the benzene ring relative to the bonding position of -S-phenylene-L-S-C(=O)C(R 2 )=CH2 on the benzene ring on the left side in general formula (2) can be any of the ortho, meta, and para positions, and is preferably the meta position.

[0129] From the perspective of further improving the stability of the composition over time and further reducing the viscosity of the composition, it is preferred that at least one of the bonding positions of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the general formula (2) is the meta-position and L is a single bond. From the perspective of further reducing the viscosity of the composition, it is more preferred that both of the above-mentioned bonding positions in the general formula (2) are the meta-position and L is a single bond.

[0130] In addition, in the present invention, the "bonding position of L on the benzene ring" refers to the bonding position of L on the benzene ring relative to the bonding position of -S-phenylene-S-CH3 on the right-side benzene ring in the general formula (2), and the "bonding position of -S-CH3 on the benzene ring" refers to the bonding position of -S-CH3 on the benzene ring relative to the bonding position of -S-phenylene-L-S-C(=O)C(R 2 )=CH2 on the left-side benzene ring in the general formula (2).

[0131] Therefore, from the perspective of further improving the stability of the composition over time and further reducing the viscosity of the composition, the monomer represented by the above general formula (1) preferably contains a monomer in which at least one of the bonding positions of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the general formula (2) is the meta-position and L is a single bond. From the perspective of further reducing the viscosity of the composition, it is more preferred to contain a monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (3) (hereinafter, also simply referred to as "the monomer represented by the general formula (3)").

[0132] [Chemical formula 7]

[0133]

[0134] In the above formula, the meaning of R 2 is the same as the meaning of R 2 in the above general formula (1).

[0135] That is, R 2 is preferably a hydrogen atom.

[0136] The content of the monomer in the monomer represented by the above general formula (1), in which at least one of the bonding positions of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the general formula (2) is the meta-position and L is a single bond, is preferably 35% by mass or more, more preferably 50% by mass or more, further preferably 65% by mass or more, particularly preferably 80% by mass or more, and may be 100% by mass.

[0137] Regarding the "content of the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (3)" in the monomer represented by the above general formula (1), the description of "the content of the monomer in which at least one of the bonding position of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the general formula (2) is the meta position and L is a single bond" can also be applied.

[0138] The following lists preferred specific examples of the monomer represented by the general formula (1), but the present invention is not limited to these compounds.

[0139] [Chemical formula 8]

[0140]

[0141] The molecular weight of the monomer represented by the general formula (1) is preferably 270 to 600, more preferably 300 to 600, and still more preferably 300 to 500.

[0142] The monomer represented by the general formula (1) can be synthesized by a conventional method. For example, it can be synthesized by referring to the synthesis methods described in Org. Lett., 2004, Vol. 6, No. 24, p. 4587 - 4590, the specification of US Patent Application Publication No. 2003 / 0195270, etc. And it can be synthesized by appropriately referring to the methods described in the examples, etc.

[0143] The content of the monomer represented by the general formula (1) in the curable composition of the present invention can be set, for example, to 60% by mass or more. From the viewpoint of further increasing (further enhancing) the liquid refractive index nD of the curable composition of the present invention and the refractive index nD of the cured product obtained by curing the curable composition of the present invention (both are refractive indices at a wavelength of 589 nm at 25°C), it is preferably 65% by mass or more, more preferably 70% by mass or more, and still more preferably 75% by mass or more. The upper limit value of the content of the monomer represented by the above general formula (1) is not particularly limited. For example, it can be set to 99% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass or less. That is, the content of the monomer represented by the above general formula (1) is preferably 65 - 99% by mass, more preferably 70 - 95% by mass, still more preferably 75 - 90% by mass, and particularly preferably 75 - 85% by mass.

[0144] In addition, when the monomer represented by the above general formula (1) is made into a curable composition as described above, a cured product that highly suppresses resin fragmentation when demolding from a mold can be obtained, a low viscosity of the above curable composition can be achieved, and a high refractive index of the obtained cured product can be achieved. Moreover, even when the concentration of the monomer represented by the general formula (1) in the curable composition is set to a high concentration, the composition can exhibit excellent stability over time.

[0145] In the present invention, a curable composition that does not contain a difunctional (meth)acrylic acid thioester monomer and contains the monomer represented by the general formula (1) can also be prepared. In this case, the content of the monomer represented by the general formula (1) can be, for example, 99.99% by mass or less, preferably 99.95% by mass or less, more preferably 99.90% by mass or less, and further preferably 99.7% by mass or less. In this case, the lower limit of the content of the monomer represented by the general formula (1) can be, for example, 97% by mass or more, preferably 98% by mass or more, and more preferably 99.0% by mass or more. That is, in this case, the content of the monomer represented by the general formula (1) is preferably 97 to 99.99% by mass, more preferably 98 to 99.95% by mass, further preferably 99.0 to 99.90% by mass, and particularly preferably 99.0 to 99.7% by mass.

[0146] Two or more kinds of monomers represented by the general formula (1) may be contained in the above curable composition. In the case of containing two or more kinds of monomers represented by the general formula (1), the total content is preferably within the above range.

[0147] <Difunctional (meth)acrylic acid thioester monomer>

[0148] The curable composition of the present invention contains a difunctional (meth)acrylic acid thioester monomer as a diluent monomer in addition to the monomer represented by the general formula (1).

[0149] The difunctional (meth)acrylic acid thioester monomer refers to a compound having two (meth)acryloylthio groups.

[0150] There is no particular limitation on the group connecting two (meth)acryloylthio groups (hereinafter, also referred to as "linking group LL"). A branched structure is preferably not present. For example, a linear alkylene group or a group in which one or two or more non-adjacent -CH2- groups in the linear alkylene group that are not adjacent to the S atom are replaced by -S- is more preferably used.

[0151] The number of carbon atoms of the linear alkylene group that can be used as the linking group LL is preferably 1 to 9, more preferably 3 to 7, and further preferably 3 to 5.

[0152] In the present invention, the "group in which one or two or more non-adjacent -CH2- groups in the linear alkylene group that are not adjacent to the S atom are replaced by -S-" means, in other words, a group having an -S- bond in the linear alkylene group and not having a structure formed by connecting two or more S atoms (for example, a disulfide structure or a polysulfide structure formed by connecting three or more S atoms), and a group in which the bonding bond to the (meth)acryloylthio group is -CH2-.

[0153] In a group in which one or two or more non-adjacent -CH2- in a linear alkylene group that is not adjacent to an S atom are replaced by -S-, as the linear alkylene group before replacing -CH2- with -S-, the description of the linear alkylene group that can be preferably used as the above-mentioned linking group LL can be preferably applied.

[0154] The molecular weight of the difunctional (meth)acrylic acid thioester monomer is preferably 150 to 400, more preferably 200 to 350.

[0155] The following are preferred specific examples of the difunctional (meth)acrylic acid thioester monomer, but the present invention is not limited to these compounds.

[0156] [Chemical formula 9]

[0157]

[0158] As the difunctional (meth)acrylic acid thioester monomer, among them, the above-mentioned exemplified compound M-1 or M-2 is preferred.

[0159] There is no particular limitation on the method for obtaining the above-mentioned difunctional (meth)acrylic acid thioester monomer, and it can be obtained commercially or synthesized by a conventional method.

[0160] The content of the difunctional (meth)acrylic acid thioester monomer in the curable composition of the present invention can be set, for example, to 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. There is no particular limitation on the lower limit value of the content of the difunctional (meth)acrylic acid thioester monomer, and it can be set, for example, to 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. That is, the content of the difunctional (meth)acrylic acid thioester monomer is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, further preferably 10 to 30% by mass, and particularly preferably 15 to 25% by mass.

[0161] The function of relieving the stress during the thermal change of the cured product can be adjusted by controlling the amount of the difunctional (meth)acrylic acid thioester monomer in the curable composition.

[0162] The curable composition of the present invention may contain two or more difunctional (meth)acrylic acid thioester monomers. When two or more difunctional (meth)acrylic acid thioester monomers are contained, the total content is preferably within the above range.

[0163] <Other components>

[0164] The curable composition of the present invention may further contain other components in addition to the monofunctional (meth)acrylic acid thioester monomer and the difunctional (meth)acrylic acid thioester monomer represented by the general formula (1). As the other components, for example, a photo radical polymerization initiator can be cited.

[0165] (Photo radical polymerization initiator)

[0166] The curable composition of the present invention preferably contains a photo radical polymerization initiator. The curable composition of the present invention can obtain a cured product exhibiting a high refractive index through photopolymerization based on the action of the photo radical polymerization initiator. As the photo radical polymerization initiator, compounds generally used as photo radical polymerization initiators can be appropriately used according to the conditions of the subsequent photopolymerization (photocuring) process. Specifically, the following compounds can be used.

[0167] For example, 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, 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1,2-diphenylethane-1,2-dione, methyl phenylglyoxylate, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-methyl-1-(4-methylphenylthio)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc. can be cited.

[0168] Among them, in the present invention, as the photoinitiator for free radical polymerization, 1-hydroxycyclohexyl phenyl ketone (which can be obtained from BASF as IRGACURE 184 (product name)), bis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (which can be obtained from BASF as IRGACURE 819 (product name)), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (which can be obtained from BASF as IRGACURE TPO (product name)), 2,2-dimethoxy-1,2-diphenylethane-1-one (which can be obtained from BASF as IRGACURE 651 (product name)), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one or 2-methyl-1-(4-methylphenylthio)-2-morpholinopropan-1-one can be preferably used.

[0169] In the case of containing a photoinitiator for free radical polymerization, the content of the photoinitiator for free radical polymerization in the above curable composition is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 1.0% by mass, and further preferably 0.05 to 0.5% by mass.

[0170] As long as it does not violate the gist of the present invention, the curable composition containing the monomer represented by the general formula (1) may contain polymers or monomers, dispersants, plasticizers, heat stabilizers, mold release agents, solvents, etc. other than the above components.

[0171] In addition, when used as an imprinting material, it is preferable to suppress the content of inorganic particles in the curable composition to 30% by mass or less, and more preferably not to contain inorganic particles.

[0172] From the viewpoint of improving the workability during the molding of the cured product, particularly improving the followability to the mold during imprinting and forming a cured product of higher quality, the viscosity of the curable composition containing the monomer represented by the general formula (1) is preferably less than 170 mPa·s, more preferably less than 135 mPa·s, further preferably less than 120 mPa·s, further preferably less than 100 mPa·s, particularly preferably less than 65 mPa·s, and most preferably less than 55 mPa·s. The lower limit is not particularly limited and is actually 1 mPa·s or more.

[0173] The viscosity of the above curable composition is the viscosity measured by the method described in the following examples. In addition, 1 mPa·s is 1 cP.

[0174] Regarding the liquid refractive index of the curable composition of the present invention, the refractive index nD at a wavelength of 589 nm at 25°C (in the present invention, it is also simply referred to as "the liquid refractive index nD of the curable composition" or "the liquid refractive index nD at 25°C") can be used for evaluation.

[0175] The liquid refractive index nD of the curable composition of the present invention can be 1.650 or more, preferably 1.660 or more. The upper limit value of the liquid refractive index nD of the curable composition of the present invention is not particularly limited, and is actually 1.750 or less.

[0176] The liquid refractive index nD of the above curable composition is a value measured using an Abbe refractometer (for example, manufactured by ATAGO CO., LTD., product name: multi-wavelength Abbe refractometer DR-M2 or DR-M4). Specifically, a measurement sample (curable composition) can be prepared and measured according to the description of the following examples. And JIS (Japanese Industrial Standards) B 7090:1999 Optics and optical instruments - Reference wavelengths (ISO (International Organization for Standardization) 7944:1998 Optics and optical instruments - Reference wavelengths) can be appropriately referred to.

[0177] The curable composition of the present invention can be used to manufacture a cured product that requires a high refractive index.

[0178] Among them, the curable composition of the present invention has low viscosity, excellent stability over time, and is suppressed from resin fragmentation when demolded from a mold. Therefore, it is used as an imprinting material such as nanoimprinting and can be preferably used to manufacture a cured product that exhibits a high refractive index.

[0179] 〔Cured product〕

[0180] The cured product of the present invention is a cured product obtained by curing a curable composition containing the monomer represented by the above general formula (1) and a bifunctional (meth)acrylic acid thioester monomer.

[0181] The cured product of the present invention is a cured product obtained by carrying out a polymerization reaction of a monomer containing the monomer represented by the general formula (1) and a bifunctional (meth)acrylic acid thioester monomer and curing. Unreacted monomers (for example, the monomer represented by the general formula (1), bifunctional (meth)acrylic acid thioester monomer) etc. may be contained in the cured product of the present invention.

[0182] The cured product of the present invention can exhibit a high refractive index as described above.

[0183] Regarding the refractive index of the cured product, it can be evaluated using the refractive index nD at a wavelength of 589 nm at 25 °C (in the present invention, it is also simply referred to as "the refractive index nD of the cured product" or "the refractive index nD of the cured product obtained by curing the curable composition").

[0184] The refractive index nD of the cured product of the present invention can be 1.670 or more, preferably 1.680 or more, more preferably 1.690 or more, further preferably 1.700 or more, and particularly preferably 1.710 or more. In the region where the refractive index nD of the above-mentioned cured product is 1.670 or more, due to the difference in the 10 -3 grade of the refractive index nD, there are differences in the performance of high refractive index when applied to optical components. For example, it can be said that the difference of 0.004 between the refractive index nD1.686 of the cured product of No. 101 and the refractive index nD1.690 of the cured products of No. 102 and 103 in the following examples is a significant difference.

[0185] In addition, the upper limit value of the refractive index nD of the cured product of the present invention is not particularly limited, and is actually 1.800 or less.

[0186] The refractive index nD of the above-mentioned cured product is a value measured using an Abbe refractometer (for example, manufactured by ATAGO CO., LTD., 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 following examples. In addition, when forming the cured product, a heating process can be used instead of the ultraviolet irradiation process described in the following examples, or both a heating process and an ultraviolet irradiation process can be used. And JIS B 7090:1999 Optics and optical instruments - Reference wavelengths (ISO 7944:1998 Optics and optical instruments - Reference wavelengths) can be appropriately referred to.

[0187] The transmittance of the cured product of the present invention is preferably 85% or more, more preferably 90% or more, and further preferably 95% or more as a whole in the visible light wavelength region of 360 to 830 nm. And the upper limit value of the transmittance of the cured product of the present invention is not particularly limited, but is actually 99% or less.

[0188] The transmittance of the above-mentioned cured product is a value of the external transmittance including surface reflection measured using a UV-visible spectrophotometer (for example, UV-2600 (product name), manufactured by Shimadzu Corporation) for a cured product with a thickness of 1 mm.

[0189] [Method for manufacturing cured product]

[0190] The cured product of the present invention can be manufactured by a method including a step of photocuring the above-mentioned curable composition. In the case of photocuring, it is preferred that the curable composition contains the above-mentioned photo radical polymerization initiator.

[0191] Regarding the conditions for photocuring, the description of light irradiation in the diffraction optical element described below can be preferably applied.

[0192] In the method for producing the cured product of the present invention, it is preferable to press the curable composition of the present invention onto a mold (die) and subject it to photocuring to obtain a cured product having a pattern of the mold (die) transferred thereon.

[0193] As the mold (die), from the viewpoint of peelability, a mold subjected to a surface treatment based on chromium nitride is preferable. As the surface treatment of the mold (die) based on chromium nitride, for example, except for reading "die" as "mold (die)", the description of the chromium nitride treatment in paragraph

[0108] of International Publication No. 2019 / 044863 can be directly applied.

[0194] Moreover, the cured product of the present invention can be produced by an imprint technique using the curable composition of the present invention while sufficiently suppressing resin fragmentation during demolding from the mold.

[0195] Figure 1 It is a schematic cross-sectional view showing a schematic method for producing the cured product of the present invention by an imprint technique using the curable composition of the present invention. In addition, the size, shape, thickness, etc. of the substrate 3, the size, shape, transfer pattern, thickness, etc. of the mold (die) 5, and the amount of use of the curable composition 1 can be appropriately adjusted to obtain a cured product 7 having a desired size, shape, transferred pattern, thickness, etc.

[0196] As Figure 1 shown, it can be produced by the following steps: (a) First, the curable composition 1 is sandwiched between the mold (die) 5 and the substrate 3; (b) While pressing the curable composition 1 into the mold (die) 5, pressing is performed, and the curable composition 1 is photocured by ultraviolet irradiation (UV irradiation) to thereby produce a cured product 7 having a pattern of the mold (die) 5 transferred thereon; and (c) The obtained cured product 7 and the substrate 3 are demolded (peeled) from the mold (die) 5.

[0197] In addition, there is no particular limitation on the ultraviolet irradiation as long as the curable composition 1 is cured, and it can be irradiated from either side of the mold (die) 5 and the substrate 3. It is preferable that the substrate 3 is transparent and irradiated from the substrate 3 side.

[0198] Moreover, regarding the obtained cured product 7, it can be used in a form integrated with the substrate 3, or can be used in a form in which the substrate 3 is peeled off and composed of the cured product 7.

[0199] Regarding the substrate 3, the description of the transparent substrate in the diffraction optical element described below can be preferably applied.

[0200] [Use of the cured product]

[0201] The cured product of the present invention can be used for various applications. Since it exhibits a high refractive index, it can be preferably used for optical materials, and among them, it can be preferably used for diffractive optical elements. For example, the diffractive optical element of the present invention can be used as a diffractive optical element for waveguide in augmented reality glasses (AR glasses).

[0202] 〔Diffractive optical element〕

[0203] The diffractive optical element of the present invention is a diffractive optical element containing a surface having a diffractive grating shape formed by the cured product of the present invention, and is formed by curing the curable composition of the present invention.

[0204] The maximum thickness of the diffractive optical element of the present invention is preferably 0.05 μm to 100 μm. The maximum thickness is more preferably 0.1 μm to 50 μm, and further preferably 0.2 μm to 30 μm. Moreover, the step difference (grating thickness) of the diffractive grating shape (periodic structure) possessed by the diffractive optical element is preferably 0.05 μm to 100 μm, more preferably 0.05 μm to 50 μm, and further preferably 0.1 μm to 30 μm. In addition, the pitch of the diffractive grating shape possessed by the diffractive optical element may be between 0.05 μm and 1 mm, and is preferably set to 0.05 μm to 100 μm, and preferably varies within the same diffractive optical element according to the required optical aberration.

[0205] The diffractive optical element can be manufactured, for example, in the following order.

[0206] The curable composition is sandwiched between the above-mentioned surface of a mold such as a mold having a surface processed into a diffractive grating shape and a transparent substrate. Then, the curable composition can be pressurized and stretched to a desired range. In the sandwiched state, light is irradiated from the transparent substrate side to cure the curable composition. Then, the cured product is demolded from the mold such as a mold. After demolding, ultraviolet irradiation can be further performed from the side opposite to the transparent substrate side.

[0207] Examples of the above-mentioned transparent substrate include flat glass such as BK glass, and flat transparent resins ((meth)acrylic resin, polycarbonate resin, polyethylene terephthalate, etc.). Surface treatments such as ozone treatment can be performed on the surface of the transparent substrate.

[0208] The transparent substrate used in the above-mentioned manufacturing can be directly included in the diffractive optical element or can be peeled off.

[0209] The light used for light irradiation in the curing of the curable composition is preferably ultraviolet light or visible light, more preferably ultraviolet light. For example, a metal halide lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a germicidal lamp, a xenon lamp, an LED (Light Emitting Diode) light source lamp, etc. can be preferably used. The illuminance of the ultraviolet light used for light irradiation in the curing of the curable composition is preferably 1 to 100 mW / cm 2 , more preferably 1 to 75 mW / cm 2 , further preferably 5 to 50 mW / cm 2 . Ultraviolet light with different illuminances can be irradiated multiple times. The exposure amount of the ultraviolet light is preferably 0.4 to 10 J / cm 2 , more preferably 0.5 to 5 J / cm 2 , further preferably 1 to 3 J / cm 2 . The atmosphere during light irradiation is preferably air or an inert gas replacement atmosphere, more preferably an atmosphere in which air is replaced with nitrogen until the oxygen concentration becomes 1% or less.

[0210] Using the curable composition of the present invention as an imprinting material, pressing is performed in a state where a mold having a pattern with a desired size of nanometers to several hundred micrometers is engraved on the material, and a cured product of the present invention with the pattern of the mold transferred is produced by photocuring, and a diffraction grating shape can be produced by demolding.

[0211] Regarding the photocuring conditions, the descriptions in the manufacturing method of the above-mentioned cured product and the manufacturing of diffractive optical elements can be applied.

[0212] Regarding aspects other than the above, the descriptions of common imprinting can be adopted without particular limitation. For example, the Nanoimprint Technology Handbook (edited by the Applied Physics Society and the Nanoimprint Technology Research Group, published by Ohmsha, Ltd., December 1, 2019) can be referred to.

[0213] Examples

[0214] The present invention will be further described in detail below based on examples. The materials, usage amounts, ratios, treatment contents, treatment sequences, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Thus, the scope of the present invention is not construed as being limited by the specific examples shown below. In addition, hereinafter, unless otherwise specified, room temperature means 25°C.

[0215] In addition, in all processes from the preparation of the curable composition to the production or evaluation test of the cured product, it is carried out in an environment using a yellow lamp as illumination.

[0216] [Synthesis Example]

[0217] The monomer represented by the general formula (1) was synthesized as follows.

[0218] [Synthesis Example 1: Synthesis of Compound (A-1)]

[0219] [Chemical Formula 10]

[0220]

[0221] ["Synthesis of Compound (A-1A)"]

[0222] After mixing 9.23 g (243.2 mmol) of lithium aluminum hydride (LAH), 450 mL of tetrahydrofuran (hereinafter abbreviated as "THF") and purging with nitrogen, it was cooled to an internal temperature (liquid temperature) of 0 °C. A mixed solution of 25.0 g (162.1 mmol) of thiosalicylic acid and 283 mL of THF was added dropwise so that the liquid temperature did not exceed 7 °C, and then it was heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, it was cooled to 0 °C, 500 mL of ethyl acetate, 50 mL of concentrated hydrochloric acid, and 500 mL of water were added dropwise in sequence and stirred, followed by washing and liquid separation. Then, 500 mL of water was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out to obtain 22.3 g of an oily compound (A-1A). (Yield 98%)

[0223] ["Synthesis of Compound (A-1B)"]

[0224] After mixing 20.0 g (142.7 mmol) of compound (A-1A), 27.6 g (135.9 mmol) of 4-bromothioanisole, 204 mL of N,N-dimethylacetamide (DMAc), and 36.1 g (278.6 mmol) of N,N-diisopropylethylamine (DIPEA) and purging with nitrogen, 3.11 g (3.40 mmol) of tris(dibenzylideneacetone)dipalladium (Pd2(dba)3) and 3.93 g (6.80 mmol) of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) were added, and it was heated to an internal temperature (liquid temperature) of 120 °C. After stirring for 5 hours, 800 mL of ethyl acetate and 800 mL of 1N hydrochloric acid were added, the insoluble matter was filtered, and then washing and liquid separation were carried out. Then, 800 mL of 5% aqueous sodium bicarbonate solution was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out to obtain an oily composition, and then it was purified by column chromatography to obtain 27.6 g of compound (A-1B). Yield 74%.

[0225] ["Synthesis of Compound (A-1C)"]

[0226] 20.3 g (77.6 mmol) of triphenylphosphine (PPh3) and 370 mL of THF were mixed. After purging with nitrogen, the mixture was cooled to an internal temperature (liquid temperature) of 0 °C. 15.7 g (77.6 mmol) of diisopropyl azodicarboxylate (DIAD) was added dropwise. After stirring at 0 °C for 30 minutes, a mixture solution of 18.5 g (70.5 mmol) of compound (A-1B), 5.90 g (77.6 mmol) of thioacetic acid (AcSH), and 370 mL of THF was added dropwise so that the liquid temperature did not exceed 7 °C, and the mixture was stirred for 1 hour. After heating to 25 °C, 760 mL of ethyl acetate and 500 mL of 5% aqueous sodium bicarbonate solution were added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out, whereby an oily composition was obtained. Subsequently, purification was performed by column chromatography to obtain 19.7 g of compound (A-1C). The yield was 87%.

[0227] <Synthesis of Compound (A-1D)>

[0228] 3.51 g (92.4 mmol) of lithium aluminum hydride (LAH) and 333 mL of THF were mixed. After purging with nitrogen, the mixture was cooled to an internal temperature (liquid temperature) of 0 °C. A mixture solution of 18.5 g (57.7 mmol) of compound (A-1C) and 210 mL of THF was added dropwise so that the liquid temperature did not exceed 7 °C, and then the internal temperature (liquid temperature) was heated to 25 °C. After stirring for 1 hour, the mixture was cooled to 0 °C, and 370 mL of ethyl acetate, 18.5 mL of concentrated hydrochloric acid, and 370 mL of water were added dropwise in sequence and stirred, followed by washing and liquid separation. Then, 370 mL of water was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out, whereby an oily composition was obtained. Subsequently, purification was performed by column chromatography to obtain 15.6 g of compound (A-1D). The yield was 97%.

[0229] <Synthesis of Compound (A-1)>

[0230] 8.00 g (28.7 mmol) of the mixed compound (A-1D), 204 mL of N,N-dimethylacetamide (DMAc), and it was cooled to an internal temperature (liquid temperature) of 0 °C. 4.01 g (31.6 mmol) of 3-chloropropionyl chloride (3CPC) was added dropwise so that the liquid temperature did not exceed 7 °C, and then it was heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, it was cooled to 0 °C, and 6.98 g (68.9 mmol) of triethylamine (TEA) was added dropwise so that the liquid temperature did not exceed 7 °C, and then it was heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, 240 mL of ethyl acetate and 800 mL of 1N hydrochloric acid were added. After filtering off the insoluble matter, washing and liquid separation were carried out. Then, 500 mL of 5% aqueous sodium bicarbonate solution was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out, whereby an oily composition was obtained, and then it was purified by column chromatography to obtain 6.57 g of compound (A-1). The yield was 69%.

[0231] 1 1H-NMR (300 MHz, CDCl3): δ (ppm) 2.48 (s, 3H), 4.37 (s, 2H), 5.60 - 5.70 (m, 1H), 6.2 - 6.5 (m, 2H), 7.1 - 7.3 (m, 7H), 7.4 - 7.5 (m, 1H)

[0232] [Synthesis Example 2: Synthesis of Compound (A-18)]

[0233] [Chemical Formula 11]

[0234]

[0235] <Synthesis of Compound (A-18B)>

[0236] 4-Bromothioanisole was changed to 1-bromo-4-(ethylthio)benzene, and otherwise, in the same manner as the synthesis of compound (A-1B), compound (A-18B) was synthesized (yield 70%).

[0237] <Synthesis of Compound (A-18C)>

[0238] Compound (A-1B) was changed to compound (A-18B), and otherwise, in the same manner as the synthesis of compound (A-1C), compound (A-18C) was synthesized (yield 85%).

[0239] <Synthesis of Compound (A-18D)>

[0240] Compound (A-1C) was changed to compound (A-18C), and except for this, compound (A-18D) was synthesized in the same manner as the synthesis of compound (A-1D) (yield 97%).

[0241] <Synthesis of Compound (A-18)>

[0242] Compound (A-1D) was changed to compound (A-18D), and except for this, compound (A-18) was synthesized in the same manner as the synthesis of compound (A-1) (yield 65%).

[0243] 1 H-NMR (300 MHz, CDCl3): δ (ppm) 1.25 (t, 3H), 2.66 (d, 2H), 4.37 (s, 2H), 5.6 - 5.7 (m, 1H), 6.2 - 6.5 (m, 2H), 7.1 - 7.3 (m, 7H), 7.4 - 7.5 (m, 1H)

[0244] [Synthesis Example 3: Synthesis of Compound (A-3)]

[0245] [Chemical Formula 12]

[0246]

[0247] <Synthesis of Compound (A-3B)>

[0248] 4-Bromothioanisole was changed to 3-bromothioanisole, and except for this, compound (A-3B) was synthesized in the same manner as the synthesis of compound (A-1B) (yield 74%).

[0249] <Synthesis of Compound (A-3C)>

[0250] Compound (A-1B) was changed to compound (A-3B), and except for this, compound (A-3C) was synthesized in the same manner as the synthesis of compound (A-1C) (yield 87%).

[0251] <Synthesis of Compound (A-3D)>

[0252] Compound (A-1C) was changed to compound (A-3C), and except for this, compound (A-3D) was synthesized in the same manner as the synthesis of compound (A-1D) (yield 95%).

[0253] <Synthesis of Compound (A-3)>

[0254] Compound (A-1D) was changed to compound (A-3D), and compound (A-3) (yield 62%) was synthesized in the same manner as the synthesis of compound (A-1) except for this.

[0255] 1 H-NMR (300 MHz, CDCl3): δ (ppm) 2.41 (s, 3H), 4.37 (s, 2H), 5.6 - 5.7 (m, 1H), 6.2 - 6.5 (m, 2H), 6.90 (s, 1H), 7.0 - 7.2 (m, 3H), 7.3 - 7.6 (m, 4H)

[0256] [Synthesis Example 4: Synthesis of Compound (A-8)]

[0257] [Chemical Formula 13]

[0258]

[0259] <Synthesis of Compound (A-8A)>

[0260] 16.3 g (129.2 mmol) of 4-hydroxybenzenethiol, 25.0 g (123.1 mmol) of 4-bromothioanisole, 185 mL of N,N-dimethylacetamide (DMAc), and 32.6 g (252.3 mmol) of N,N-diisopropylethylamine (DIPEA) were mixed and purged with nitrogen, and then 2.82 g (3.08 mmol) of tris(dibenzylideneacetone)dipalladium (Pd2(dba)3) and 3.56 g (6.16 mmol) of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) were added, and the mixture was heated to an internal temperature (liquid temperature) of 120 °C. After stirring for 5 hours, 800 mL of ethyl acetate and 800 mL of 1N hydrochloric acid were added, the insoluble matter was filtered, and then washing and liquid separation were carried out. Then, 800 mL of 5% aqueous sodium bicarbonate solution was added, stirred, and then washing and liquid separation were carried out. Dehydration based on magnesium sulfate, filtration, and concentration were carried out to obtain an oily composition, and then purification was carried out by column chromatography to obtain 23.5 g of compound (A-8A). Yield 77%.

[0261] <Synthesis of Compound (A-8B)>

[0262] 22.0 g (88.6 mmol) of the mixed compound (A-8A), 185 mL of N,N-dimethylacetamide (DMAc), 14.9 g (132.9 mmol) of 1,4-diazabicyclo[2.2.2]octane (DABCO), and 12.1 g of N,N-dimethylthiocarbamyl chloride were heated to an internal temperature (liquid temperature) of 50 °C. 240 mL of ethyl acetate and 500 mL of 1 N hydrochloric acid were added, and washing and liquid separation were performed. Then, 500 mL of 5% aqueous sodium bicarbonate solution was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out to obtain an oily composition, which was then purified by column chromatography to obtain 23.8 g of compound (A-8B). The yield was 80%.

[0263] <Synthesis of Compound (A-8C)>

[0264] After heating 23.0 g (68.5 mmol) of compound (A-8B) at 240 °C for 24 hours, it was cooled to room temperature. Ethyl acetate was added, and the dissolved portion was taken out and then concentrated to obtain 19.6 g of compound (A-8C). The yield was 85%.

[0265] <Synthesis of Compound (A-8D)>

[0266] 3.39 g (89.4 mmol) of lithium aluminum hydride (LAH) and 360 mL of THF were mixed and purged with nitrogen, and then cooled to an internal temperature (liquid temperature) of 0 °C. A mixture of 20.0 g (59.6 mmol) of compound (A-8C) and 227 mL of THF was added dropwise so that the liquid temperature did not exceed 7 °C, and then heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, it was cooled to 0 °C, and 300 mL of ethyl acetate, 17.9 mL of concentrated hydrochloric acid, and 370 mL of water were added dropwise in sequence and stirred, followed by washing and liquid separation. Then, 370 mL of water was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out to obtain an oily composition, which was then purified by column chromatography to obtain 15.1 g of compound (A-8D). The yield was 96%.

[0267] <Synthesis of Compound (A-8)>

[0268] 15.0 g (56.7 mmol) of the mixed compound (A-8D), 29.6 mL of N,N-dimethylacetamide (DMAc), and it was cooled to an internal temperature (liquid temperature) of 0 °C. 7.92 g (62.4 mmol) of 3-chloropropionyl chloride (3CPC) was added dropwise so that the liquid temperature did not exceed 7 °C, and then it was heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, it was cooled to 0 °C, and 13.8 g (136.1 mmol) of triethylamine (TEA) was added dropwise so that the liquid temperature did not exceed 7 °C, and then it was heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, 150 mL of ethyl acetate and 200 mL of 1N hydrochloric acid were added, and washing and liquid separation were carried out. Then, 500 mL of 5% aqueous sodium bicarbonate solution was added and stirred, and then washing and liquid separation were carried out. Dehydration based on magnesium sulfate, filtration, and concentration were carried out, whereby an oily composition was obtained, and then it was purified by column chromatography to obtain 11.7 g of compound (A-8). Yield 65%.

[0269] 1 1H-NMR (300 MHz, CDCl3): δ (ppm) 2.50 (s, 3H), 5.7 - 5.8 (m, 1H), 6.3 - 6.5 (m, 2H), 7.1 - 7.3 (m, 6H), 7.3 - 7.4 (m, 2H)

[0270] [Synthesis Example 5: Synthesis of Compound (A-6)]

[0271] [Chemical Formula 14]

[0272]

[0273] <Synthesis of Compound (A-6A)>

[0274] 4-Bromothioanisole was changed to 3-bromothioanisole, and 4-hydroxythiophenol was changed to 3-hydroxythiophenol. Otherwise, in the same manner as the synthesis of compound (A-8A), compound (A-6A) was synthesized (yield 72%).

[0275] <Synthesis of Compound (A-6B)>

[0276] Compound (A-8A) was changed to compound (A-6A). Otherwise, in the same manner as the synthesis of compound (A-8B), compound (A-6B) was synthesized (yield 82%).

[0277] <Synthesis of Compound (A-6C)>

[0278] Compound (A-8B) was changed to compound (A-6B), and in other respects, compound (A-6C) was synthesized in the same manner as the synthesis of compound (A-8C) (yield 85%).

[0279] <Synthesis of Compound (A-6D)>

[0280] Compound (A-8C) was changed to compound (A-6C), and in other respects, compound (A-6D) was synthesized in the same manner as the synthesis of compound (A-8D) (yield 85%).

[0281] <Synthesis of Compound (A-6)>

[0282] Compound (A-8D) was changed to compound (A-6D), and in other respects, compound (A-6) was synthesized in the same manner as the synthesis of compound (A-8) (yield 66%).

[0283] 1 1H-NMR (300 MHz, CDCl3): δ (ppm) 2.48 (s, 3H), 5.7 - 5.8 (m, 1H), 6.3 - 6.5 (m, 2H), 7.0 - 7.4 (m, 8H)

[0284] [Synthesis Example 6: Synthesis of Compound (A-9)]

[0285] [Chemical Formula 15]

[0286]

[0287] <Synthesis of Compound (A-9A)>

[0288] 4-Bromothioanisole was changed to 3-bromothioanisole, and in other respects, compound (A-9A) was synthesized in the same manner as the synthesis of compound (A-8A) (yield 70%).

[0289] <Synthesis of Compound (A-9B)>

[0290] Compound (A-8A) was changed to compound (A-9A), and in other respects, compound (A-9B) was synthesized in the same manner as the synthesis of compound (A-8B) (yield 83%).

[0291] <Synthesis of Compound (A-9C)>

[0292] Compound (A-8B) was changed to compound (A-9B), and in other respects, compound (A-9C) was synthesized in the same manner as the synthesis of compound (A-8C) (yield 85%).

[0293] <Synthesis of Compound (A-9D)>

[0294] Compound (A-8C) was changed to compound (A-9C), and compound (A-9D) was synthesized in the same manner as the synthesis of compound (A-8D) (yield: 83%).

[0295] <Synthesis of Compound (A-9)>

[0296] Compound (A-8D) was changed to compound (A-9D), and compound (A-9) was synthesized in the same manner as the synthesis of compound (A-8) (yield: 63%).

[0297] 1 1H-NMR (300 MHz, CDCl3): δ (ppm) 2.48 (s, 3H), 5.7 - 5.8 (m, 1H), 6.3 - 6.5 (m, 2H), 7.0 - 7.4 (m, 8H)

[0298] [Synthesis Example 7: Synthesis of Compound (A-16)]

[0299] [Chemical Formula 16]

[0300]

[0301] 15.0 g (56.7 mmol) of compound (A-8D), 29.6 mL of N,N-dimethylacetamide (DMAc), and 6.88 g (68.1 mmol) of triethylamine (TEA) were mixed and cooled to an internal temperature (liquid temperature) of 0 °C. 6.52 g (62.4 mmol) of methacryloyl chloride was added dropwise so that the liquid temperature did not exceed 7 °C, and then the mixture was heated to an internal temperature (liquid temperature) of 25 °C. After stirring for 1 hour, 150 mL of ethyl acetate and 200 mL of 1N hydrochloric acid were added, and washing and liquid separation were performed. Then, 500 mL of 5% aqueous sodium bicarbonate solution was added and stirred, followed by washing and liquid separation. Dehydration with magnesium sulfate, filtration, and concentration were carried out to obtain an oily composition, which was then purified by column chromatography to obtain 8.5 g of compound (A-16). The yield was 45%.

[0302] 1 1H-NMR (300 MHz, CDCl3): δ (ppm) 2.03 (s, 3H), 2.47 (s, 3H), 5.72 (s, 1H), 6.20 (s, 1H), 7.1 - 7.3 (m, 6H), 7.3 - 7.4 (m, 2H)

[0303] [Example 1: Preparation of Curable Composition]

[0304] The monomer represented by the general formula (1) or the comparative monomer, the bifunctional (meth)acrylic acid thioester monomer, and the photopolymerization initiator were mixed in such a manner as to form the composition described in Table 1 below, heated to 50 °C, and stirred to make them uniform, whereby a curable composition was prepared.

[0305] The curable compositions No. 101 to 112 are compositions containing the monomer represented by the general formula (1) of the present invention, and the curable compositions No. c11 to c14 are comparative compositions not containing the monomer represented by the general formula (1) of the present invention.

[0306] [Example 2: Production of cured product]

[0307] The curable composition prepared above was sandwiched between hydrophobized glass plates so that the film thickness of the cured product became 150 μm, and using a UV irradiation device (EXECURE 3000 (product name), manufactured by HOYA CANDEO OPTRONICS), in an atmosphere replaced with nitrogen (N2) with an oxygen concentration of 1% or less, at an integrated light quantity of 1.2 J / cm 2 and an illuminance of 5 mW / cm 2 , after UV (ultraviolet) irradiation under these conditions, it was peeled off from the glass plate to produce a cured product.

[0308] [Evaluation 1] Refractive index

[0309] At 25 °C, the refractive index nD at a wavelength of 589 nm of the measurement sample was measured using a multi-wavelength Abbe refractometer DR-M2 or DR-M4 (product name, manufactured by ATAGO CO., LTD.). As the measurement sample, for the liquid refractive index nD of the composition, the curable composition prepared above was used, and for the refractive index nD of the cured product, the cured product prepared above was used. For the refractive index nD of the cured product, evaluation was carried out according to the following criteria.

[0310] The results are summarized in Table 1.

[0311] - Evaluation criteria for the refractive index nD of the cured product -

[0312] A2: nD ≥ 1.710

[0313] A1: 1.700 ≤ nD < 1.710

[0314] B: 1.690 ≤ nD < 1.700

[0315] C: 1.680 ≤ nD < 1.690

[0316] D: 1.670 ≤ nD < 1.680

[0317] E: nD < 1.670

[0318] [Evaluation 2: Viscosity Measurement]

[0319] Using a rheometer (product name: Rheostress6000, manufactured by Thermo Scientific), the viscosity η at a shear rate of 10 s -1 and at 25 °C of the curable composition prepared above was evaluated according to the following criteria. 1 cP is 1 mPa·s.

[0320] The results are summarized in Table 1. In addition, for the viscosity values in the table, the unit "cP" is omitted in the description.

[0321] - Evaluation Criteria for Viscosity -

[0322] A3: η < 55 cP

[0323] A2: 55 cP ≤ η < 65 cP

[0324] A1: 65 cP ≤ η < 100 cP

[0325] B2: 100 cP ≤ η < 120 cP

[0326] B1: 120 cP ≤ η < 135 cP

[0327] C: 135 cP ≤ η < 170 cP

[0328] D: 170 cP ≤ η

[0329] [Evaluation 3: Temporal Stability of Liquid]

[0330] The curable composition prepared above was stored at 25 °C for 2 months, and visually observed for any changes in crystallization precipitation and / or turbidity over time. The temporal stability of the liquid was evaluated according to the following criteria. In addition, for storage, it was carried out in an environment with a yellow light used for lighting.

[0331] - Evaluation Criteria for Temporal Stability of Liquid -

[0332] A2: During the 2-month storage period, neither crystallization precipitation nor turbidity change occurred and it remained transparent.

[0333] A1: During the 1-month storage period, neither crystallization precipitation nor turbidity change occurred and it remained transparent, but during the storage period from over 1 month to 2 months, a trace amount of crystallization precipitation was observed.

[0334] N: During the 1-month storage period, at least one of crystallization precipitation and turbidity change occurred.

[0335] [Evaluation 4: Defective rate of the molded product released from the mold]

[0336] The following mold was prepared: a disk-shaped SUS mold with a diameter of 30 mm. On one of its surfaces, as a transfer pattern, there are 27 concentric grooves with a depth of 20 μm and a width of 50 μm at intervals of 0.5 mm from the center of the circle, and chromium nitride electroplating was performed on the surface. 10 μL of the curable composition prepared above was placed at the center of an ozone-treated BK-7 glass substrate (diameter 35 mm). After expanding the curable composition to a diameter of 30 mm, while pressing the mold against the curable composition, a UV irradiation device (EXECURE 3000 (product name), manufactured by HOYA CANDEO OPTRONICS) was used. In an atmosphere replaced with nitrogen (N2) with an oxygen concentration of 1% or less, under the conditions of an integrated light quantity of 1.2 J / cm 2 and an illuminance of 5 mW / cm 2 , after UV curing, the composite composed of the glass and the cured product of the curable composition was disassembled from the mold to obtain a sample. A total of 20 samples were prepared by the same method. The surface of the cured product of each sample (the side in contact with the mold) was observed with an optical microscope (manufactured by KEYENCE CORPORATION), and the sample in which the cured product was cracked within a range of a radius of 5 mm from the center was regarded as a defective product. The proportion of defective products among the 20 samples produced was calculated as the defective rate, and the evaluation was carried out according to the following criteria.

[0337] -Evaluation criteria for the defective rate of the molded product released from the mold-

[0338] A: The defective rate is 10% or less (the number of defective products is 0 - 2)

[0339] B: The defective rate exceeds 10% and is 20% or less (the number of defective products is 3 or 4)

[0340] C: The defective rate exceeds 20% and is 30% or less (the number of defective products is 5 or 6)

[0341] D: The defective rate exceeds 30% (the number of defective products is 7 - 20)

[0342]

[0343]

[0344] Each component in the table is as follows. In addition, the blending amount wt% of each component recorded in the column of each component refers to mass%, and "-" means that the component is not contained.

[0345] Further, the curable composition No. 109 contains A-1 and A-8, which are monomers represented by the general formula (1), at a ratio of 39.9 wt% each.

[0346] (Monomer represented by general formula (1))

[0347] [Chemical formula 17]

[0348]

[0349] (Comparative monomer)

[0350] [Chemical formula 18]

[0351]

[0352] The comparative monomers Z-1 to Z-3 are the compounds described in Examples 3, 8, and 10 of JP-A-2020-37693, respectively.

[0353] (Bifunctional (meth)acrylic thioester monomer)

[0354] [Chemical formula 19]

[0355]

[0356] (Photoinitiator)

[0357] IrgTPO: Irgacure TPO (product name, manufactured by BASF Japan Ltd., available as Omnirad TPO H (product name, manufactured by IGM Resins B.V.)), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide

[0358] From the results in Table 1, the following can be known.

[0359] In terms of having an acryloyloxy group as a functional group and the acryloyloxy group being connected to the benzene ring by >CH(CH3), the comparative monomer Z-1 is not a monomer represented by the general formula (1) of the present invention. In terms of having an acryloyloxy group as a functional group and the acryloyloxy group being connected to the benzene ring by >CH(C6H4-S-C6H5), the comparative monomer Z-2 is also not a monomer represented by the general formula (1) of the present invention. Regarding the curable compositions No. c11 and c12 containing these comparative monomers Z-1 or Z-2, the viscosity of the composition is high, the stability over time of the composition is low, the refractive index nD of the obtained cured product is low, and the defective rate of the mold-released product is high, and these are all poor.

[0360] In terms of having vinyl instead of (meth)acryloylthio group as a functional group, the comparative monomer Z-3 is not the monomer represented by the general formula (1) of the present invention. Regarding the curable composition No.c13 containing this comparative monomer Z-3, the viscosity of the composition is high, the stability over time of the composition is low, and the defective rate of the mold-released finished product is high, and it is poor in all these aspects.

[0361] In terms of having acryloyloxy instead of (meth)acryloylthio group as a functional group, the comparative monomer Z-4 is not the monomer represented by the general formula (1) of the present invention. Regarding the curable composition No.c14 containing this comparative monomer Z-4, the stability over time of the composition is low, the refractive index nD of the obtained cured product is low, and the defective rate of the mold-released finished product is high, and it is poor in all these aspects.

[0362] In contrast, regarding the curable compositions No.101 to 109 containing the monomer represented by the general formula (1) of the present invention and the bifunctional (meth)acrylic acid thioester monomer, the viscosity of the composition is as low as 77 cP or less, the stability over time of the composition is also excellent, and the refractive index nD of the obtained cured product is 1.686 or more and is high, and the defective rate of the mold-released finished product is also suppressed to 10% or less and is excellent. Among them, regarding the curable compositions No.102 to 109 containing the monomer represented by the general formula (2) of the present invention, the low viscosity, the stability over time, and the suppression of the defective rate of the mold-released finished product are excellent, and the refractive index nD of the cured product can be further increased and is more excellent. In addition, regarding the curable compositions No.104 to 109 containing the monomer of the present invention in which L in the general formula (1) is a single bond, the low viscosity, the stability over time, and the suppression of the defective rate of the mold-released finished product are excellent, and the refractive index nD of the cured product can be further increased and is more excellent. In particular, regarding the curable composition containing the monomer in which at least one of the bonding position of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the general formula (2) is the meta position and L is a single bond, the viscosity of the composition can be further reduced and the stability over time can be increased and is excellent (No.104 and 106 relative to No.105). Among them, regarding the curable composition containing the monomer represented by the general formula (3), the viscosity of the composition can be further reduced and is excellent (No.104 relative to No.106).

[0363] Further, regarding the monomer represented by the general formula (1) of the present invention, as can be seen from the comparison between curable composition No. 102 and 110, the comparison between curable composition No. 105 and 111, and the comparison between curable composition No. 104 and 112, the refractive index nD of the cured product is increased to 1.697 or more. Therefore, when the content ratio of the monomer (compound) represented by the general formula (1) of the present invention is designed at a high concentration of 99.7% by mass, the viscosity of the composition is as low as 132 cP or less, the stability of the composition over time is also excellent, and the defective rate of the mold-released product is also suppressed to 20% or less, which is excellent.

[0364] The present invention and its embodiments have been described together, but we believe that the present invention should not be limited to any details of the description unless otherwise specified, and should be broadly interpreted without departing from the spirit and scope of the invention shown in the appended claims.

[0365] This application claims the priority of Japanese Patent Application No. 2022-201313 filed in the Japanese Patent Office on December 16, 2022, and its content is incorporated herein by reference as a part of the description of this specification.

[0366] Symbol Explanation

[0367] 1 - curable composition, 3 - substrate, 5 - mold, 7 - cured product.

Claims

1. A curable composition comprising: a monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (1); and a difunctional (meth)acrylic acid thioester monomer, [Chemical formula 1] In the above formula, R 1 represents an arylene group and a group containing an S atom, L represents a single bond or a methylene group, and R 2 represents a hydrogen atom or a methyl group.

2. The curable composition according to claim 1, wherein the liquid refractive index nD at 25°C is 1.650 or more.

3. The curable composition according to claim 1, wherein the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) includes a monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (2), [Chemical formula 2] In the above formula, L and R 2 have the same meanings as L and R 2 respectively.

4. The curable composition according to claim 1, wherein the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) includes a monomer in which L in the general formula (1) is a single bond.

5. The curable composition according to claim 3, wherein the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) includes a monomer in which at least one of the bonding position of -S-CH3 on the benzene ring and the bonding position of L on the benzene ring in the general formula (2) is the meta position and L is a single bond.

6. The curable composition according to claim 5, wherein the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) includes a monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (3), [Chemical formula 3] In the above formula, R 2 has the same meaning as the R 2 .

7. The curable composition according to claim 1, which is used for imprinting.

8. A cured product which is a cured product of the curable composition according to any one of claims 1 to 7.

9. An optical material comprising the cured product according to claim 8.

10. A diffractive optical element comprising: a surface having a diffractive grating shape formed of the cured product according to claim 8.

11. A monofunctional (meth)acrylic acid thioester monomer represented by the following general formula (1), [Chemical formula 4] In the above formula, R 1 represents an arylene group and a group containing an S atom, L represents a single bond or a methylene group, and R 2 represents a hydrogen atom or a methyl group.

12. A curable composition comprising: the monofunctional (meth)acrylic acid thioester monomer represented by the general formula (1) according to claim 11.

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