Curable composition, cured product, molded product, optical material, and method for producing multifunctional (METH)acrylic acid thioester composition

Abstract

[1] A polyfunctional (meth)acrylate thioester composition comprising a polyfunctional (meth)acrylate thioester compound (A) represented by formula (1); [2] A curable composition comprising the polyfunctional (meth)acrylate thioester composition as described in [1]; [3] A curable material formed by curing the curable composition as described in [2]; [4] A molded body comprising the curable body as described in [3]; and [5] An optical material comprising the molded body as described in [4].

Description

Technical Field

[0001] The present invention relates to a multifunctional (meth)acrylic acid thioester composition, a curable composition, a cured product, a molded body, an optical material, and a method for producing the multifunctional (meth)acrylic acid thioester composition. Prior Art

[0002] Previously, glass was the preferred optical material due to its diverse refractive index and minimal fluctuations due to temperature and humidity. However, in recent years, demand for lighter weight and lower costs has led to the use of cured resins.

[0003] For example, camera lens modules for smartphones are increasingly using wafer-level lenses to achieve miniaturization and thinness. Wafer-level lenses require a cured resin with a high refractive index and excellent heat resistance. Furthermore, hybrid wafer-level lenses, where a resin lens is formed on a glass substrate, require a low curing shrinkage rate during curing to prevent delamination between the glass substrate and the resin lens caused by residual stress. As a method for obtaining a cured resin having a higher refractive index, Patent Document 1 or Patent Document 2 reports a method of using a transparent material obtained by photocuring a composition containing thio(meth)acrylate or the like. [Prior art literature] [Patent Document]

[0004] Patent Document 1: International Publication No. 98 / 24761 Patent Document 2: Japanese Patent Laid-Open No. 8-325337 Summary of the Invention

[0005] [Problems to be solved by the invention] However, the cured resin obtained by the methods described in Patent Documents 1 and 2 has a high refractive index, but has a large shrinkage rate during curing, and has problems with adhesion to glass.

[0006] The present invention has been made in view of the above circumstances and provides a multifunctional (meth)acrylate thioester composition and a curable composition capable of producing a cured product having an improved balance of properties including a high refractive index, low curing shrinkage, and glass adhesion; as well as a cured product, a molded article, and an optical material having an improved balance of properties including a high refractive index, low curing shrinkage, and glass adhesion. [Methods for solving the problem]

[0007] The present inventors have conducted intensive research to address the aforementioned issues. As a result, they discovered that the use of a specific polyfunctional (meth)acrylate thioester compound improves the performance balance of the resulting cured product, including high refractive index, low curing shrinkage, and glass adhesion. This led to the completion of the present invention. According to the present invention, there are provided the following multifunctional (meth)acrylate thioester composition, curable composition, cured product, molded article, optical material, and method for producing the multifunctional (meth)acrylate thioester composition.

[0008] [1] A multifunctional (meth)acrylic acid thioester composition comprises a multifunctional (meth)acrylic acid thioester compound (A) represented by the following formula (1). [Chemistry 1] (In the above formula (1), n ​​is an integer of 5 or greater, X represents an alkylene group having 1 or more and 4 or less carbon atoms, in which any methylene group may be substituted with a carbonyl group, any hydrogen atom in the alkylene group is substituted with a structure of the following formula (2), and R1 and R2 each independently represent a hydrogen atom or a methyl group) [Chemistry 2] (In the formula (2), R 3 represents a hydrogen atom or a methyl group, multiple R 3 groups may be the same or different, W represents an alkylene group having 1 or more and 4 or less carbon atoms, and o is an integer greater than 1) [2] The multifunctional (meth)acrylate thioester composition as described in [1], wherein the weight average molecular weight of the multifunctional (meth)acrylate thioester composition is greater than or equal to 1,000 and less than or equal to 100,000. [3] The polyfunctional (meth)acrylate thioester composition as described in [1] or [2], wherein the polyfunctional (meth)acrylate thioester compound (A) comprises at least one selected from the group consisting of a compound represented by the following formula (3) and a compound represented by the following formula (4). [Chemistry 3] [Chemistry 4] (In the formulae (3) and (4), m and n are each independently an integer greater than 2, X and Y each independently represent an alkylene group having 1 to 4 carbon atoms, in which any hydrogen atom may be substituted by the structure of the formula (2), multiple Xs and Ys may be the same or different, and R1 and R2 each independently represent a hydrogen atom or a methyl group) [4] A curable composition comprising the multifunctional (meth)acrylate thioester composition described in any one of [1] to [3]. [5] The curable composition described in [4] further comprises a compound (B) represented by the following formula (5). [Chemistry 5] (In the formula (5), Z1 and Z2 each independently represent an aromatic carbocyclic ring or an alkylene group, any hydrogen atom of which may be substituted by an alkyl group or an alkoxy group; Z3 and Z4 each independently represent an aromatic carbocyclic ring or an alkylene group, any hydrogen atom of which may be substituted by an alkyl group or an alkoxy group; R1 and R3 each independently represent an alkylene group having 1 to 10 carbon atoms; R2 and R4 each independently represent a hydrogen atom or a methyl group; R5 and R6 each independently represent an alkyl group; m and n each independently represent an integer greater than 0; o, p, q, and r each are an integer greater than 0 that satisfies the relationship o+q≦4 and p+r≦4.) [6] The curable composition as described in [4] or [5], wherein the viscosity of the curable composition at 25°C measured using an E-type viscometer at a rotation speed of 2.5 rpm is 100 mPa·s or more and 10,000 mPa·s or less. [7] The curable composition as described in any one of [4] to [6] further comprises a polymerization initiator. [8] The curable composition as described in any one of [4] to [7] further comprises at least one selected from the group consisting of a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer. [9] The curable composition according to any one of [4] to [8], wherein, when d1 is the specific gravity of the curable composition measured using a pycnometer in accordance with Japanese Industrial Standards (JIS) Z 8804:2012, and d2 is the specific gravity of a test piece having a thickness of 250 μm containing the cured product of the curable composition, the curing shrinkage of the curable composition, represented by (1-d1 / d2)×100, is 9.0% or less.

[10] The curable composition described in any one of [4] to [9] can be used for optical materials.

[11] A hardened material is obtained by hardening the hardening composition described in any one of [4] to

[10] .

[12] The cured product as described in

[11] , wherein when a test piece having a thickness of 250 μm including the cured product is prepared, the light transmittance (T 1) of the test piece at a wavelength of 400 nm is 81% or more.

[13] The cured product as described in

[12] , wherein the test piece is heated in an oven set at 125°C in an air environment for 168 hours, and when the light transmittance of the test piece at a wavelength of 400 nm after the heating treatment is set to T2, the change rate of the light transmittance after heating represented by (T1-T2) / T1×100 is 7.0% or less.

[14] The cured product as described in any one of

[11] to

[13] , wherein when a test piece having a thickness of 250 μm including the cured product is prepared, the refractive index (nD) of the test piece in D-ray (589.3 nm) is 1.600 or greater.

[15] The hardened material as described in any one of

[11] to

[14] , wherein when a test piece having a thickness of 250 μm including the hardened material is prepared, the Abbe's number (νD) of the test piece measured in accordance with American Society for Testing Materials (ASTM) D542 is 20 or more.

[16] A formed body comprising the hardened material described in any one of

[11] to

[15] .

[17] An optical material comprising the formed body as described in

[16] .

[18] The optical material as described in

[17] further comprises a glass substrate, and The optical material is a laminate of the molded body and the glass substrate.

[19] The optical material as described in

[17] or

[18] is an optical lens.

[20] A method for producing a multifunctional (meth)acrylic acid thioester composition is the method for producing a multifunctional (meth)acrylic acid thioester composition as described in any one of [1] to [3], comprising the steps of converting 0.5 equivalents or more and 0.9 equivalents or less of all thiol groups in a polythiol compound into functional groups represented by the following structural formula, and then subjecting the obtained compound to a β-detachment reaction and an enethiol reaction, thereby synthesizing a multifunctional (meth)acrylic acid thioester compound. [Chemistry 6] (In the structural formula, X represents a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and R represents a hydrogen atom or a methyl group) [twenty one] A method for producing a multifunctional (meth)acrylate thioester composition is the method for producing a multifunctional (meth)acrylate thioester composition as described in any one of [1] to [3], comprising the following steps: reacting a polythiol compound with a polythio(meth)acrylate compound via an enethiol reaction. [Effects of the Invention]

[0009] The present invention provides a multifunctional (meth)acrylate thioester composition and a curable composition capable of producing a cured product having an improved balance of properties including a high refractive index, low curing shrinkage, and glass adhesion; as well as a cured product, a molded article, and an optical material having an improved balance of properties including a high refractive index, low curing shrinkage, and glass adhesion. Implementation Method

[0010] The present invention will be described below based on embodiments. In this specification, "A to B," which indicates a numerical range, represents A or greater and B or less, unless otherwise specified. Furthermore, the term "(meth)acrylic acid" in this specification refers to at least one selected from the group consisting of acrylic acid and methacrylic acid, and the same applies to similar terms such as "thio(meth)acrylate" and "(meth)acrylate." Furthermore, the term "(meth)acryloyl" in this specification refers to at least one selected from the group consisting of an acryl group represented by -C(=O)-CH=CH₂ and a methacryloyl group represented by -C(=O)-C(CH₃)=CH₂.

[0011] [Multifunctional (meth)acrylate thioester composition] The polyfunctional (meth)acrylate thioester composition of the present invention comprises a polyfunctional (meth)acrylate thioester compound (A) represented by the following formula (1) (hereinafter, also referred to as "compound (A)"). The polyfunctional (meth)acrylate thioester composition of the present invention may comprise only one polyfunctional (meth)acrylate thioester compound (A) or may comprise two or more polyfunctional (meth)acrylate thioester compounds (A). Furthermore, when the polyfunctional (meth)acrylate thioester composition of the present invention comprises only one polyfunctional (meth)acrylate thioester compound (A), it is also referred to as a polyfunctional (meth)acrylate thioester composition.

[0012] [Chemistry 7] In the formula (1), n ​​is an integer of 5 or greater, X represents an alkylene group having 1 or more and 4 or less carbon atoms in which any methylene group may be substituted by a carbonyl group, any hydrogen atom in the alkylene group is substituted by a structure of the following formula (2), and R1 and R2 each independently represent a hydrogen atom or a methyl group.

[0013] [Chemistry 8] In the formula (2), R 3 represents a hydrogen atom or a methyl group, and multiple R 3 groups may be the same or different. W represents an alkylene group having 1 to 4 carbon atoms, and o is an integer greater than 1.

[0014] In the formula (1), n ​​is an integer greater than or equal to 5, preferably an integer greater than or equal to 6, more preferably an integer greater than or equal to 7, and is preferably an integer less than or equal to 20, more preferably an integer less than or equal to 15, further preferably an integer less than or equal to 12, and further preferably an integer less than or equal to 10. In the formula (1), X represents an alkylene group having 1 to 4 carbon atoms, in which any methylene group may be substituted by a carbonyl group, more preferably an alkylene group having 2 to 4 carbon atoms, and even more preferably an alkylene group having 2 to 3 carbon atoms, and any hydrogen atom in the alkylene group may be substituted by a structure of the formula (2). In the formula (1), in X, the number of alkylene groups substituted with the structure of the formula (2) is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, further preferably 1 or 2, and further preferably 2. In the formula (1), in X, the number of the carbonyl groups is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and further preferably 1 or 2.

[0015] In the formula (2), W represents an alkylene group having 1 or more and 4 or less carbon atoms, preferably an alkylene group having 1 or more and 3 or less carbon atoms, more preferably an alkylene group having 1 or 2 carbon atoms, and further preferably an alkylene group having 1 carbon atoms; o is an integer of 1 or more, preferably an integer of 1 or more and 4 or less, more preferably an integer of 1 or more and 3 or less, further preferably 1 or 2, and further preferably 1.

[0016] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the compound (A) preferably comprises at least one selected from the group consisting of a compound represented by the following formula (3) and a compound represented by the following formula (4).

[0017] [Chemistry 9]

[0018] [Chemistry 10] In the formulae (3) and (4), m and n are each independently an integer greater than 2, X and Y each independently represent an alkylene group having 1 or more and 4 or less carbon atoms, in which any hydrogen atom may be substituted by the structure of the formula (2), multiple Xs and Ys may be the same or different, and R1 and R2 each independently represent a hydrogen atom or a methyl group.

[0019] In the formula (3) and the formula (4), m and n are each independently an integer greater than 2, preferably an integer greater than 2 and less than 6, more preferably an integer greater than 2 and less than 5, further preferably an integer greater than 2 and less than 3, and further preferably 3. In the formula (3) and the formula (4), X and Y are each independently an alkylene group having 2 or more and 4 or less carbon atoms, in which any hydrogen atom may be replaced by the structure of the formula (2), preferably an alkylene group having 2 or more and 3 or less carbon atoms, in which any hydrogen atom may be replaced by the structure of the formula (2), and more preferably an alkylene group having 2 carbon atoms, in which any hydrogen atom may be replaced by the structure of the formula (2). In the formulae (3) and (4), in X and Y, the number of alkylene groups substituted with the structure of the formula (2) is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, further preferably 1 or 2, and further preferably 2.

[0020] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the compound (A) preferably contains at least one selected from the group consisting of the following compounds.

[0021] [Chemistry 11]

[0022] From the perspective of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the weight average molecular weight of the multifunctional (meth)acrylate thioester composition of the present invention is preferably 1,000 or more, more preferably 1,500 or more, and preferably 100,000 or less, more preferably 50,000 or less, further preferably 20,000 or less, further preferably 10,000 or less, and further preferably 5,000 or less.

[0023] When the total amount of the polyfunctional (meth)acrylate thioester composition is taken as 100% by mass, from the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the content of the compound (A) in the polyfunctional (meth)acrylate thioester composition of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and is preferably 100% by mass or less.

[0024] (Method for producing a polyfunctional (meth)acrylic acid thioester composition) The polyfunctional (meth)acrylate thioester composition of the present invention can be produced, for example, by a production method comprising the following steps: converting 0.5 equivalents or more and 0.9 equivalents or less of all thiol groups in a polythiol compound into functional groups represented by the following structural formula; and then subjecting the obtained compound to a β-detachment reaction and an enethiol reaction to synthesize the polyfunctional (meth)acrylate thioester compound. More specifically, as described in Synthesis Example 3 below, by reacting a polythiol compound with a halogenated alkylcarbonyl halide such as 3-chloropropionyl chloride, the thiol group in the polythiol compound can be converted to a functional group represented by the following structural formula. The β-detachment reaction and enethiol reaction can be carried out by known methods.

[0025] [Chemistry 12] In the structural formula, X represents a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom, and R represents a hydrogen atom or a methyl group.

[0026] In addition, the multifunctional (meth)acrylate thioester composition of the present invention can also be produced by a production method comprising the steps of reacting a polythiol compound with a polythio(meth)acrylate compound via an ene-thiol reaction. More specifically, as described in Synthesis Example 2 below, a polyfunctional thio(meth)acrylate composition can be obtained by reacting a polythio(meth)acrylate compound with a polythiol compound via an ene-thiol reaction. The ene-thiol reaction can be performed by a known method.

[0027] [Curing composition] The curable composition of the present invention includes the multifunctional (meth)acrylate thioester composition of the present invention. The curable composition of the present invention can provide a cured product, a molded article, and an optical material having an improved performance balance of high refractive index, low curing shrinkage, and glass adhesion.

[0028] Hereinafter, each component constituting the curable composition of the present invention will be described.

[0029] <Multifunctional (meth)acrylate thioester composition> The polyfunctional (meth)acrylic acid thioester composition is the polyfunctional (meth)acrylic acid thioester composition of the present invention as described above. From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the content of the polyfunctional (meth)acrylate thioester composition in the curable composition of the present invention is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, further preferably 50 parts by mass or more, further preferably 70 parts by mass or more, further preferably 80 parts by mass or more, further preferably 90 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 99 parts by mass or less, based on 100 parts by mass of the curable composition of the present invention.

[0030] <Compound (B)> From the perspective of further reducing the Abbe number and further improving transparency, heat resistance and stability after heating, the curable composition of the present invention may further contain a compound (B) represented by the following formula (5) (hereinafter also referred to as "compound (B)").

[0031] [Chemistry 13] In the formula (5), Z1 and Z2 each independently represent an aromatic carbocyclic ring or an alkylene group, any hydrogen atom of which may be substituted by an alkyl group or an alkoxy group, Z3 and Z4 each independently represent an aromatic carbocyclic ring or an alkylene group, any hydrogen atom of which may be substituted by an alkyl group or an alkoxy group, R1 and R3 each independently represent an alkylene group having 1 or more and 10 or less carbon atoms, R2 and R4 each independently represent a hydrogen atom or a methyl group, R5 and R6 each independently represent an alkyl group, m and n each independently represent an integer greater than 0, and o, p, q and r each independently represent an integer greater than 0 that satisfies the relationship o+q≦4 and p+r≦4.

[0032] In formula (5), Z1 and Z2 each independently represent an aromatic carbocyclic ring or an alkylene group, and any hydrogen atom may be substituted with an alkyl group or an alkoxy group. Z1 and Z2 each independently represent preferably a benzene ring, a naphthalene ring, or an alkylene group having 1 to 4 carbon atoms, and more preferably a benzene ring or an alkylene group having 1 to 3 carbon atoms. In formula (5), Z3 and Z4 each independently represent an aromatic carbocyclic ring or an alkyl group, and any hydrogen atom may be substituted by an alkyl group or an alkoxy group. Z3 and Z4 each independently represent preferably an aromatic carbocyclic ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a naphthalene ring. In the formula (5), R1 and R3 each independently represent an alkylene group having 1 to 10 carbon atoms. R1 and R3 each independently represent preferably an alkylene group having 1 to 4 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, further preferably an alkylene group having 2 to 3 carbon atoms, and further preferably an alkylene group having 2 carbon atoms. In the formula (5), R 2 and R 4 each independently represent a hydrogen atom or a methyl group. R 2 and R 4 each independently represent preferably a hydrogen atom. In the formula (5), R 5 and R 6 each independently represent an alkyl group. R 5 and R 6 each independently represent an alkyl group preferably having 1 or more and 4 or less carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atoms. In the formula (5), m and n each independently represent an integer greater than 0. m and n each independently represent an integer greater than or equal to 0 and less than or equal to 4, more preferably an integer greater than or equal to 0 and less than or equal to 2, further preferably 0 or 1, further preferably 1. In formula (5), o, p, q, and r are each an integer greater than or equal to 0 that satisfies the relationship o+q≦4 and p+r≦4. q and r are each independently preferably an integer greater than or equal to 0 and less than or equal to 2, more preferably 0 or 1, and further preferably 0. o and p are each independently preferably an integer greater than or equal to 0 and less than or equal to 2, more preferably 0 or 1, and further preferably 0. From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the compound (B) is preferably a compound represented by the formula (5), wherein Z1 and Z2 are a benzene ring, a naphthalene ring, or an alkylene group having 1 to 4 carbon atoms, Z3 and Z4 are a benzene ring or a naphthalene ring, R1 and R3 are an alkylene group having 1 to 4 carbon atoms, R2 and R4 are a hydrogen atom or a methyl group, m and n are integers of 0 to 4, q and r are 0 or 1, and o and p are 0. More preferably, a compound represented by the formula (5), wherein Z1 and Z2 are a benzene ring or an alkylene group having 1 to 3 carbon atoms, Z3 and Z4 are a naphthalene ring, R1 and R3 are an alkylene group having 1 to 3 carbon atoms, R2 and R4 are a hydrogen atom or a methyl group, m and n are 0 or 1, q and r are 0 or 1, and o and p are 0.

[0033] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the compound (B) is selected from the group consisting of 9,9-bis(4-(meth)acryloyloxyphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)phenyl)fluorene, 9,9-bis(4-(3-(meth)acryloyloxypropoxy)phenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxypropoxy)phenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-3-methylphenyl)fluorene, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)-3-methylphenyl]fluorene, 9,9-bis[4-(3-(meth)acryloyloxypropoxy)phenyl]fluorene fluorene, 9,9-bis[4-(2-(meth)acryloyloxypropyloxy)-3-methylphenyl]fluorene, 9,9-bis[4-(2-(meth)acryloyloxypropyloxy)-3-methylphenyl]fluorene, 9,9-bis[4-(2-(meth)acryloyloxyethyl)-1,8-diphenylfluorene, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)-3-ethylphenyl]fluorene, 9,9-bis[4-(3-(meth)acryloyloxypropyloxy)-3-ethylphenyl]fluorene, 9,9-bis[4-(2-(meth)acryloyloxypropyloxy)-3-ethylphenyl]fluorene, 9,9-bis[4-(2-(meth)acryloyloxypropyloxy)-3-ethylphenyl]fluorene, 9,9-bis[2-(meth)acryloyloxyethyl)-1,8-diphenylfluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-1,8-diphenyl Fluorene, 9,9-bis(2-(meth)acryloyloxypropyl)-1,8-diphenylfluorene, 9,9-bis(2-(meth)acryloyloxyethyl)-2,7-diphenylfluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-2,7-diphenylfluorene, 9,9-bis(2-(meth)acryloyloxypropyl)-2,7-diphenyl Fluorene, 9,9-bis(2-(meth)acryloyloxyethyl)-3,6-diphenylfluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-3,6-diphenylfluorene, 9,9-bis(2-(meth)acryloyloxypropyl)-3,6-diphenylfluorene, 9,9-bis(2-(meth)acryloyloxyethyl)-4,5-diphenylfluorene Fluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-4,5-diphenylfluorene, 9,9-bis(2-(meth)acryloyloxypropyl)-4,5-diphenylfluorene, 9,9-bis(2-(meth)acryloyloxyethyl)-1,8-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(meth)acryloyloxypropyl)- 1,8-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-1,8-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-bis(naphthalene-1-yl)fluorene 9,9-bis(2-(methyl)acryloyloxyethyl)-4,5-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-4,5-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-4,5-bis(naphthalene-1-yl)fluorene Fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-1,8-bis(naphthalene-2-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-1,8-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-1,8-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-1,8-bis(naphthalene-2-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-bis(naphthalene- 2-yl) fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl) fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl) fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-4,5-bis(naphthalene-2-yl) fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl) fluorene At least one selected from the group consisting of 9,9-bis(4-(methyl)acryloyloxyphenyl)fluorene, 9,9-bis(4-(2-(methyl)acryloyloxypropyl)-4,5-bis(naphthalene-2-yl)fluorene, and 9,9-bis(2-(methyl)acryloyloxypropyl)-4,5-bis(naphthalene-2-yl)fluorene, more preferably 9,9-bis(4-(methyl)acryloyloxyphenyl)fluorene, 9,9-bis(4-(3-(methyl)acryloyloxypropyloxy)phenyl)fluorene, 9,9-bis(4-(2-(methyl)acryloyloxypropyloxy)phenyl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7-diphenylfluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-2,7-diphenylfluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-2,7-diphenylfluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-diphenylfluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-3,6-diphenylfluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-3,6-diphenylfluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-( 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7 at least one selected from the group consisting of 9,9-bis(naphthalene-2-yl)fluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-2,7-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(meth)acryloyloxypropyl)-2,7-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(meth)acryloyloxyethyl)-3,6-bis(naphthalene-2-yl)fluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl)fluorene, and 9,9-bis(2-(meth)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl)fluorene, and more preferably 9,9-bis(4-(2-(meth)acryloyloxyethoxy)phenyl)fluorene, 9,9-bis(4- (3-(methyl)acryloyloxypropyloxy)phenyl)fluorene, 9,9-bis(4-(2-(methyl)acryloyloxypropyloxy)phenyl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-3,6-bis(naphthalene-1-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxyethyl)-3,6-bis(naphthalene-1-yl)fluorene 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7-bis(naphthalene-2-yl)fluorene, 9,9-bis(3-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-2-yl)fluorene, 9,9-bis(2-(methyl)acryloyloxypropyl)-2,7-bis(naphthalene-2-yl)fluorene, At least one member selected from the group consisting of 9,9-bis(2-(meth)acryloyloxyethyl)-3,6-bis(naphthalene-2-yl)fluorene, 9,9-bis(3-(meth)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl)fluorene, and 9,9-bis(2-(meth)acryloyloxypropyl)-3,6-bis(naphthalene-2-yl)fluorene.

[0034] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low Abbe number, low curing shrinkage, and glass adhesion, and from the viewpoint of further improving transparency, heat resistance, and stability after heating, the content of compound (B) in the curable composition of the present invention is preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 10 parts by mass or more, further preferably 15 parts by mass or more, further preferably 20 parts by mass or more, and is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 50 parts by mass or less, based on 100 parts by mass of the curable composition of the present invention.

[0035] (Synthesis Method of Compound (B)) Examples of commercially available products of the compound (B) include difunctional acrylate "A-BPEF" manufactured by Shin-Nakamura Science & Technology Co., Ltd. and difunctional acrylate "OGSOL EA-0200" or "OGSOL EA-0300" manufactured by Osaka Gas Chemical Co., Ltd. Alternatively, compound (B) can be synthesized by (meth)acryloyl esterifying a commercially available fluorene derivative diol with (meth)acrylic anhydride or (meth)acryloyl chloride. Examples of commercially available fluorene derivative diols include bisphenoxyethanolfluorene (BPEF) and bisphenolfluorene (BPF) manufactured by Osaka Gas Chemical Co., Ltd. Alternatively, 9,9-bis(2-(methyl)acryloyloxyethyl)-2,7-bis(naphthalen-2-yl)fluorene (DNEOA) can be synthesized by the following synthesis scheme.

[0036] [Chemistry 14]

[0037] From the viewpoint of further improving the performance balance of the obtained cured product, namely, a high refractive index, low curing shrinkage, and glass adhesion, the viscosity of the curable composition of the present invention at 25°C, as measured using an E-type viscometer at a rotation speed of 2.5 rpm, is preferably 100 mPa·s or higher, more preferably 500 mPa·s or higher, further preferably 1000 mPa·s or higher, further preferably 1500 mPa·s or higher, and is preferably 10000 mPa·s or lower, more preferably 8000 mPa·s or lower, further preferably 6500 mPa·s or lower, further preferably 5000 mPa·s or lower, and further preferably 3500 mPa·s or lower.

[0038] <Other ingredients> The curable composition of the present invention may also contain other ingredients besides the multifunctional (meth)acrylate thioester composition and compound (B). Examples of these other ingredients include polymerization initiators, ultraviolet absorbers, resin modifiers, internal mold release agents, silane coupling agents, antioxidants, light stabilizers, processing stabilizers, bluing agents, polymeric metal deactivators, flame retardants, lubricants, antistatic agents, heat shielding agents, fluorescent dyes (including fluorescent brighteners), pigments, light scattering agents, reinforcing fillers, surfactants, antimicrobial agents, plasticizers, compatibilizers, and other resins or elastomers. Of these, the curable composition of the present invention preferably contains a polymerization initiator to further enhance curability. Furthermore, the curable composition of the present invention preferably further contains at least one selected from the group consisting of silane coupling agents, antioxidants, ultraviolet absorbers, and light stabilizers.

[0039] To further improve the performance balance of the resulting cured product, including a high refractive index, low curing shrinkage, and glass adhesion, the curable composition of the present invention preferably includes a polymerization initiator. Examples of the polymerization initiator include thermal radical polymerization initiators, photoradical polymerization initiators, and combinations thereof. Examples of the thermal radical polymerization initiator include dialkyl peroxides such as dicumyl peroxide, t-butyl cumyl peroxide, 2,5-bis(t-butyl peroxide) 2,5-dimethylhexane, 2,5-bis(t-butyl peroxide) 2,5-dimethylhexyne-3, di-t-butyl peroxide, isopropyl cumyl-t-butyl peroxide, and bis(α-t-butyl peroxide isopropyl)benzene; 1,1-bis(t-butyl peroxide) cyclohexane, 1,1-bis(t-butyl peroxide) 3,3,5-trimethylcyclohexane, 1,1-bis(t-butyl peroxide) cyclododecane, n-butyl-4,4-bis(t-butyl peroxide) valerate, and ethyl Peroxyketals such as 3,3-bis(tert-butyl peroxide) butyrate, 3,3,6,6,9,9-hexamethyl-1,2,4,5-tetraoxycyclononane; peroxyesters such as bis(tert-butyl peroxide) isophthalate, tert-butyl peroxybenzoate, and tert-butyl peroxyacetate; hydroperoxides such as tert-butyl hydroperoxide, tert-hexyl hydroperoxide, cumyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, diisopropylbenzene hydroperoxide, and p-menthane hydroperoxide; bibenzyl compounds such as 2,3-dimethyl-2,3-diphenylbutane; 3,3,5,7,7-pentamethyl-1,2,4-trioxepane, etc.

[0040] Examples of photoradical polymerization initiators include benzoin alkyl ether, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzophenone, methyl benzoylformate, isopropylthioxanthone, and mixtures of two or more thereof. These photoradical polymerization initiators may also be used together with a sensitizer. Examples of sensitizers include carbonyl compounds such as anthraquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, benzanthrone, p,p'-tetramethyldiaminobenzophenone, and tetrachlorobenzoquinone; nitro compounds such as nitrobenzene, p-dinitrobenzene, and 2-nitrofluorene; aromatic hydrocarbons such as anthracene and chrysene; sulfur compounds such as diphenyl disulfide; and nitrogen compounds such as nitroaniline, 2-chloro-4-nitroaniline, 5-nitro-2-aminotoluene, and tetracyanoethylene.

[0041] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the content of the polymerization initiator in the curable composition of the present invention is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, further preferably 1.0 parts by mass or more, further preferably 1.5 parts by mass or more, further preferably 2.0 parts by mass or more, further preferably 2.5 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8.0 parts by mass or less, further preferably 5.0 parts by mass or less, further preferably 4.0 parts by mass or less, based on the total amount of the polyfunctional (meth)acrylate thioester composition and compound (B) in the curable composition of the present invention being 100 parts by mass.

[0042] From the perspective of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the curable composition of the present invention preferably contains a silane coupling agent. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-phenylenediaminetrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, etc. These silane coupling agents are sold by, for example, Shin-Etsu Chemical Co., Ltd. and can be easily obtained from the market.

[0043] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the content of the silane coupling agent in the curable composition of the present invention is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, further preferably 0.1 parts by mass or more, further preferably 0.5 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, further preferably 3.0 parts by mass or less, and further preferably 1.5 parts by mass or less, based on the total amount of the polyfunctional (meth)acrylate thioester composition and compound (B) in the curable composition of the present invention being 100 parts by mass.

[0044] From the perspective of further improving UV resistance, the curable composition of the present invention preferably contains a UV absorber. Examples of UV absorbers include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, triazine-based UV absorbers, and benzoxazine-based UV absorbers. Examples of benzophenone-based UV absorbers include 4-methoxy-2-hydroxybenzophenone (molecular weight 228), 4-methoxy-2-hydroxybenzophenone-5-sulfonic acid (molecular weight 308), 2,4-dihydroxybenzophenone (molecular weight 214), 4,4'-dimethoxy-2,2'-dihydroxybenzophenone (molecular weight 274), 4,4'-dimethoxy-2,2'-dihydroxy-5,5'-disulfonic acid benzophenone. Disodium benzoate (molecular weight 478), 2,2'-4,4'-tetrahydroxybenzophenone (molecular weight 246), sodium hydroxymethoxybenzophenone sulfonate (molecular weight 376), octabenzophenone (molecular weight 326), 2-hydroxy-4-m-octyloxybenzophenone (molecular weight 345), 2-hydroxy-4-n-octyloxybenzophenone (molecular weight 326), bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane (molecular weight 468), etc. In addition, examples of benzotriazole-based ultraviolet absorbers include 2-(2H-benzotriazole-2-yl)-p-cresol (molecular weight 225), 2-(2H-benzotriazole-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (molecular weight 448), 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-(tert-butyl)phenol (molecular weight 316), 2,4-di-tert-butyl-6-(5-chloro-2H-1,2,3-benzotriazole-2-yl)phenol (molecular weight 358), 2-(2H-benzotriazole-2-yl)-4,6-tert-pentylphenol (molecular weight 352), 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (molecular weight 448), 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-(tert-butyl)phenol (molecular weight 316), 2,4-di-tert-butyl-6-(5-chloro-2H-1,2,3-benzotriazole-2-yl)phenol (molecular weight 358), -benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (molecular weight 323), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (molecular weight 659), 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'5-di-tert-butyl-phenyl)-5-chlorobenzotriazole (molecular weight 357), 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (molecular weight 225), 2-(2-hydroxy-5-octylphenyl)-benzotriazole (molecular weight 323), etc. Furthermore, as triazine-based ultraviolet absorbers, for example, there are 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (molecular weight 426), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol (molecular weight 509), 2,4,6-tris(2-hydroxy-4-hexyloxy-3- methylphenyl)-1,3,5-triazine (molecular weight 700), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol (molecular weight 512), poly[1,6-hexanediamine, N,N'-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-morpholine-2,4,6-trichloro-1,3,5-triazine], etc. Examples of benzoxazine-based UV absorbers include 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one) (molecular weight 368). Other examples include tetraethyl-2,2-(1,4-phenylene-dimethine)-bismalonic acid (molecular weight 418), which has a malonic acid ester structure, and 2-ethyl, 2'-ethoxy-oxalamide (molecular weight 312), which has an oxalic acid aniline structure. These components can also be used in combination.

[0045] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, glass adhesion, and UV resistance, the content of the ultraviolet absorber in the curable composition of the present invention is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, and even more preferably 0.01 parts by mass or more, and is preferably 1.0 parts by mass or less, more preferably 0.5 parts by mass or less, even more preferably 0.2 parts by mass or less, and even more preferably 0.1 parts by mass or less, based on the total amount of the polyfunctional (meth)acrylate thioester composition and compound (B) in the curable composition of the present invention being 100 parts by mass.

[0046] From the viewpoint of further improving oxidation resistance, the curable composition of the present invention preferably contains an antioxidant. Examples of antioxidants include triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenyl) propionate. tributyl-4-hydroxybenzyl)benzene, N,N-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester, tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, and 3,9-bis{1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro(5,5)undecane, etc.

[0047] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, glass adhesion, and oxidation resistance, the content of the antioxidant in the curable composition of the present invention is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, and is preferably 5.0 parts by mass or less, more preferably 2.0 parts by mass or less, and even more preferably 1.0 parts by mass or less, based on the total amount of the polyfunctional (meth)acrylate thioester composition and compound (B) in the curable composition of the present invention being 100 parts by mass.

[0048] From the perspective of further improving weather resistance, the curable composition of the present invention preferably contains a light stabilizer, more preferably a hindered amine light stabilizer. Examples of hindered amine light stabilizers include (1,2,2,6,6-pentamethyl-piperidin-4-yl) methacrylate, bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperidinyl) decanedioate, 70% by weight of a reaction product of 1,1-dimethylethyl hydroperoxide and octane and 30% by weight of polypropylene, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, and methyl-1,2,2,6,6-pentamethyl-4-piperidinyl mixtures of sebacic acid esters, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacic acid ester, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, a mixture of 2,2,6,6-tetramethyl-4-piperidyl-1,2,3,4-butanetetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate, a mixture of 1,2,2,6,6-pentamethyl-4-piperidyl-1,2,3,4-butanetetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate, and the like.

[0049] When the total amount of the polyfunctional (meth)acrylate thioester composition and the compound (B) in the curable composition of the present invention is 100 parts by mass, from the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, glass adhesion, and weather resistance, the content of the hindered amine-based light stabilizer in the curable composition of the present invention is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, and is preferably 5.0 parts by mass or less, more preferably 1.0 parts by mass or less, even more preferably 0.5 parts by mass or less, and even more preferably 0.2 parts by mass or less.

[0050] In the curable composition of the present invention, when the specific gravity of the curable composition, as measured using a pycnometer in accordance with JIS Z 8804:2012, is d1, and the specific gravity of a 250 μm thick test piece containing the cured product of the curable composition of the present invention is d2, the curing shrinkage of the curable composition, expressed as (1-d1 / d2)×100, is preferably 9.0% or less, more preferably 8.0% or less, further preferably 7.0% or less, and further preferably 6.5% or less. The lower limit of the curing shrinkage is not particularly limited, and may be, for example, 0.1% or more, 1.0% or more, 3.0% or more, 4.0% or more, or 5.0% or more. In this embodiment, a test piece having a thickness of 250 μm of a cured product comprising the curable composition of the present invention can be obtained, for example, by irradiating a curable film comprising the curable composition applied to a glass substrate with ultraviolet light at an exposure dose of 1000 mJ / cm 2 at 365 nm, and then heating the obtained cured product at 80°C for 30 minutes under a nitrogen atmosphere.

[0051] <Method for producing a curable composition> The curable composition of the present invention can be obtained by mixing the compound (B) and other components as needed with a polyfunctional (meth)acrylate thioester composition using a conventionally known method.

[0052] From the viewpoint of further improving the performance balance of the obtained cured product, namely, high refractive index, low curing shrinkage, and glass adhesion, the total content of the polyfunctional (meth)acrylate thioester composition and compound (B) in the curable composition of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and is preferably 100% by mass or less, when the entire curable composition is taken as 100% by mass.

[0053] [Hardened material] The cured product of the present invention is obtained by curing the curable composition of the present invention. The cured product of the present invention has an improved performance balance between high refractive index, low curing shrinkage, and glass adhesion, and is therefore preferably used in optical materials.

[0054] Regarding the cured product of this embodiment, from the perspective of further improving the transparency of the cured product, when a 250 μm thick test piece containing the cured product is prepared, the light transmittance (T1) of the test piece at a wavelength of 400 nm is preferably 81% or higher, more preferably 83% or higher, further preferably 84% or higher, and further preferably 85% or higher. The upper limit of the light transmittance (T1) is not particularly limited, and for example, it may be less than 100%, 99% or lower, 95% or lower, or 90% or lower. In this embodiment, a test piece having a thickness of 250 μm including the cured product of this embodiment can be obtained, for example, by irradiating a curable film including a curable composition applied to a glass substrate with ultraviolet light at an exposure dose of 1000 mJ / cm 2 at 365 nm, and then heating the obtained cured product at 80°C for 30 minutes under a nitrogen atmosphere.

[0055] Furthermore, regarding the cured product of this embodiment, a 250 μm thick test piece is prepared using the cured product. The obtained test piece is heated in an oven set at 125°C in an air environment for 168 hours. The transmittance of the heat-treated test piece at a wavelength of 400 nm is defined as T2. The rate of change in transmittance after heating, expressed as (T1-T2) / T1×100, is preferably 7.0% or less, more preferably 5.0% or less, further preferably 4.0% or less, and further preferably 3.0% or less. The lower limit of the rate of change in transmittance after heating is not particularly limited, and may be, for example, 0.1% or more, 0.5% or more, 0.8% or more, or 1.0% or more.

[0056] Regarding the cured product of this embodiment, from the perspective of further improving the optical properties of the cured product, when a 250 μm thick test piece containing the cured product is prepared, the refractive index (nD) of the test piece in D-ray (589.3 nm) is preferably 1.600 or greater, more preferably 1.610 or greater, further preferably 1.620 or greater, further preferably 1.630 or greater, further preferably 1.635 or greater, further preferably 1.640 or greater, and further preferably 1.645 or greater. The upper limit of the refractive index (nD) of the test piece in D-ray (589.3 nm) is not particularly limited, and may be, for example, 1.700 or less, 1.680 or less, 1.655 or less, or 1.650 or less.

[0057] Regarding the cured product of this embodiment, from the viewpoint of further improving the optical properties of the cured product, when a test piece having a thickness of 250 μm including the cured product is prepared, the Abbe number (νD) of the test piece measured in accordance with ASTM D542 is preferably 20 or greater, more preferably 25 or greater, further preferably 28 or greater, further preferably 30 or greater, further preferably 32 or greater, and further preferably 33 or greater. The upper limit of the Abbe number (νD) of the test piece is not particularly limited, and may be, for example, 45 or less, 42 or less, 40 or less, or 38 or less.

[0058] [molded body] The molded article of the present invention is a molded article comprising the cured product of the present invention, and can be obtained, for example, by molding the curable composition of the present invention into a predetermined shape while curing it. Since the molded article of the present invention includes the cured article of the present invention, the performance balance of high refractive index, low curing shrinkage, and glass adhesion is improved, and thus it can be preferably used in optical materials.

[0059] From the viewpoint of further improving the performance balance of high refractive index, low curing shrinkage, and glass adhesion, the content of the cured product of the present invention in the molded article of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 97% by mass or more, and is preferably 100% by mass or less, based on 100% by mass of the entire molded article.

[0060] [Optical Materials] The optical material of the present invention includes the molded article of the present invention, and can be obtained, for example, by molding the curable composition of the present invention into a predetermined shape while curing it. The optical material of the present invention includes the cured product or molded article of the present invention, and thus has an improved performance balance of high refractive index, low curing shrinkage, and glass adhesion. Therefore, examples of the optical material include various optical lenses such as sensor lenses, pickup lenses, projector lenses, prisms, fθ lenses, imaging lenses, camera lenses, light guide plates, head-mounted display lenses, plastic eyeglass lenses, goggles, vision correction eyeglass lenses, imaging equipment lenses, Fresnel lenses for liquid crystal projectors, lenticular lenses, contact lenses, sealants for light emitting diodes (LEDs), optical waveguides, wafer-level optics (WLOs), or optical adhesives used for bonding optical waveguides, antireflection films used in optical lenses, etc., transparent coatings used in liquid crystal display device components (substrates, light guide plates, films, sheets, etc.), sheets or films attached to car windshields or motorcycle helmets, and transparent substrates. The optical material of the present invention has an improved performance balance among high refractive index, low curing shrinkage and glass adhesion, and is therefore more preferably used as various optical lenses. Furthermore, the optical material of the present invention has an improved performance balance of high refractive index, low curing shrinkage and glass adhesion, and therefore further includes a glass substrate, and can be preferably used as a laminate of the molded body of the present invention and the glass substrate, and further, can be preferably used as a so-called hybrid optical lens in which a resin lens is formed on a glass substrate.

[0061] While the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above may be employed. The present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0062] Hereinafter, this embodiment will be described in detail with reference to Examples etc. However, this embodiment is not limited in any way by the description of these Examples.

[0063] <Example 1> (Preparation of Curable Composition) The composition obtained in Synthesis Example 2 (100 parts by weight) of the polyfunctional (meth)acrylate thioester composition and Irg184 (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF, 3.0 parts by weight) as a polymerization initiator were added to a sample bottle and mixed using a mixing rotor until the appearance became uniform, thereby obtaining a curable composition. The viscosity of the obtained curable composition at 25° C. was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) at a rotation speed of 2.5 rpm.

[0064] (Production of hardened film) 0.5 mL of the curable composition was applied to an Eagle-XG (an alkali-free glass substrate manufactured by Corning, 70 × 70 × 0.7 mm T) that had been mold-released using Novec 1720 (a fluorinated silane coating agent manufactured by 3M). The substrate was then sandwiched between another mold-released glass substrate via a 250 μm-thick spacer, and the ends were secured with a clamp. The obtained laminate was irradiated with ultraviolet light from one side using an electrodeless lamp (H-type lamp) at an exposure dose of 1000 mJ / cm2 at 365 nm. The cured product was then released from the glass substrate and heated at 80°C for 30 minutes under a nitrogen atmosphere to obtain a cured film with a thickness of 250 μm. The refractive index and shrinkage rate during curing of the obtained cured film were measured by the method shown below. The obtained results are shown in Table 1.

[0065] <Measurement of Refractive Index (nD) and Abbe Number (νD)> The refractive index (nD) and the Abbe number (νD) were measured according to ASTM D542 as follows. The refractive index (nD) of the cured film at D-ray (589.3 nm) was measured using an Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.). The measurement was performed using RE-3520 (D-ray, manufactured by Atago Co., Ltd.) as the interference filter and RE-1196 (monobrominated naphthalene, manufactured by Atago Co., Ltd.) as the intermediate solution. The sample temperature was set at 25°C. The refractive index (nC) of the cured film for C-rays (wavelength 656.3 nm) was measured using an Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.) with RE-3522 (C-ray, manufactured by Atago Co., Ltd.) as the interference filter and RE-1196 (monobrominated naphthalene, manufactured by Atago Co., Ltd.) as the intermediate solution, with the sample temperature set at 25°C. The refractive index (nF) of the cured film under F-ray (wavelength 486.1 nm) was measured using a refractometer (DR-M2, manufactured by Atago Co., Ltd.) with RE-3521 (F-ray, manufactured by Atago Co., Ltd.) as the interference filter and RE-1196 (monobrominated naphthalene, manufactured by Atago Co., Ltd.) as the intermediate solution, with the sample temperature set at 25°C. Then, the Abbe number of the cured film was calculated according to the following formula. Abbe number = (nD-1) / (nF-nC)

[0066] <Light transmittance> The light transmittance in the thickness direction of the obtained cured film was measured under the following conditions to obtain the light transmittance T1. The measurement was performed by attaching the cured film to an integrating sphere, with the light incident surface being an arbitrary surface. (Measurement conditions) Measuring device: UH4150 (UV-visible-near-infrared spectrophotometer manufactured by Hitachi High-Tech Scientific Co., Ltd.) Determination method: permeation method Measurement wavelength: 400 nm Reference: Atmosphere Detector: Integrating sphere / photomultiplier tube (200 nm~850 nm) Integrating sphere: PbS (850 nm~2600 nm)

[0067] <Change in Light Transmittance After Heating (125°C, 168 Hours)> First, the resulting cured film was heated in an oven set at 125°C in an air environment for 168 hours. The light transmittance in the thickness direction was then measured under the aforementioned conditions to obtain the post-heating light transmittance T2, which was calculated using the following formula. The results are shown in Table 1. Change in light transmittance after heating (125°C 168 hours) (%) =(T 1-T 2) / T 1×100

[0068] <Determination of Curing Shrinkage> The specific gravity d1 of the curable composition was measured using a pycnometer (JIS Z 8804:2012). The specific gravity d2 of the cured film was also measured using the Archimedean method (JIS Z 8807:2012). Using these specific gravity values, the curing shrinkage (%) was calculated using the following formula. Formula: Hardening shrinkage (%) = (1-d 1 / d 2) × 100

[0069] <Evaluation of Glass Adhesion> 0.5 mL of the curable composition was applied to an Eagle-XG substrate (an alkali-free glass substrate manufactured by Corning, 70 × 70 × 0.7 mm T) that had been release-treated using Novec 1720 (a fluorinated silane coating agent manufactured by 3M). The substrate was then sandwiched between two unreleased Eagle-XG substrates (an alkali-free glass substrate manufactured by Corning, 70 × 70 × 0.7 mm T) via a 250 μm-thick spacer, and the ends were secured with a clamp. The obtained laminate was irradiated with ultraviolet light from one side using an electrodeless lamp (H-type lamp) at an exposure dose of 1000 mJ / cm2 at 365 nm. The cured product was then released from the release-treated glass substrate and heated at 80°C for 30 minutes under a nitrogen atmosphere to obtain a cured resin / glass substrate laminate. The glass adhesion of the obtained laminate was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) PASS (good): No peeling at the resin / glass substrate interface or cracking of the resin was observed. FAIL (poor): Peeling at the resin / glass substrate interface or cracks in the resin were observed.

[0070] <Examples 2 to 5 and Comparative Examples 1 to 2> The evaluations were performed in the same manner as in Example 1, except that the composition of the curable composition was changed to the composition shown in Table 1. Table 1 shows the curable composition composition and the various evaluation results.

[0071] [Table 1] Table 1 Ingredient name Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Composition of the curing composition (parts by mass) The composition obtained in Synthesis Example 2 100 100 The composition obtained in Synthesis Example 3 100 80 60 Compound (B) A-BPEF 20 40 GSTA 100 The composition obtained in Synthesis Example 4 100 Irg184 3 3 3 3 3 3 3 KBM-5103 1 AO-60 0.5 LA-82 0.1 LA-46 0.05 Viscosity of curable composition (mPa･s, 25℃) 6200 1600 2800 6000 6000 370 2100 Physical properties of hardened material Refractive index (nD, 25°C) 1.649 1.649 1.642 1.637 1.640 1.642 1.651 Abbe number 36 34 32 30 36 35 31 Hardening shrinkage (%) 6.8 6.1 6.3 6.2 6.2 9.6 11.2 Glass adhesion Pass Pass Pass Pass Pass Fail Fail Light transmittance (%) 84.3 84.1 86.5 86.7 88.7 80.1 79.1 Change in light transmittance after heating (125°C 168 hours) (%) 3.5 3.6 2.1 1.2 1.1 8 9

[0072] The details of each component shown in Table 1 are as follows. GSTA: 1,8-bisacrylthio-(4-acrylthiomethyl-3,6-dithiaoctane) (produced according to Synthesis Example 1 below)

[0073] A-BPEF (fluorene acrylate monomer (9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene), manufactured by Shin-Nakamura Scientific Co., Ltd., compound with the following structure)

[0074] [Chemistry 15]

[0075] (Other ingredients) Irg184: Polymerization initiator (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF, compound with the following structure)

[0076] [Chemistry 16] KBM-5103: Silane coupling agent (3-acryloxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., compound with the following structure)

[0077] [Chemistry 17]

[0078] AO-60: Antioxidant (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, manufactured by ADEKA Co., Ltd., a compound with the following structure)

[0079] [Chemistry 18] LA-82: Hindered amine light stabilizer (methacrylic acid (1,2,2,6,6-pentamethyl-piperidin-4-yl), manufactured by ADEKA Co., Ltd., compound with the following structure)

[0080] [Chemistry 19] LA-46: UV absorber (2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol, a compound with the following structure, manufactured by ADEKA Co., Ltd.)

[0081] [Chemistry 20]

[0082] (Synthesis Example 1: Synthesis of GSTA) In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet, and dropping funnel, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (GST, 100.0 g, 383.9 mmol) was placed, diluted with dichloromethane (100 mL), and stirring was initiated. Next, while the reaction mixture was cooled in an ice bath to an internal temperature below 40°C, 3-chloropropionyl chloride (121.84 g, 959.7 mmol) was added dropwise. After stirring the reaction mixture at room temperature for 48 hours, pure water (100 mL) was added and the organic phase was separated by separation. The resulting organic phase was washed twice with saturated aqueous sodium bicarbonate (100 mL), and the solvent was distilled off using an evaporator to obtain the compound with the following structure (201.0 g).

[0083] [Chemistry 21]

[0084] The obtained compound was placed in a four-necked flask equipped with a thermometer and a dropping funnel. 4-Methoxyphenol (150 mg) was added as a polymerization inhibitor and dissolved while stirring at room temperature. Triethylamine (116.5 g, 1152 mmol) was then added dropwise while cooling the reaction mixture in an ice bath to an internal temperature below 40°C. After stirring the reaction mixture at room temperature for 1 hour, 1 M hydrochloric acid (300 mL) was added and the organic phase was separated by separation. The resulting organic phase was passed through silica gel (100 mL), 4-methoxyphenol (150 mg) was added as a polymerization inhibitor, and the mixture was concentrated under reduced pressure to obtain a colorless, transparent compound (GSTA) with the following structure (110.0 g). Molecular weight was determined by gel permeation chromatography (GPC), revealing a number average molecular weight (Mn) of 400 and a weight average molecular weight (Mw) of 440.

[0085] [Chemistry 22]

[0086] (Synthesis example 2) A four-necked flask equipped with a stirrer, thermometer, nitrogen inlet, and dropping funnel was charged with GSTA (9.0 g) obtained in Synthesis Example 1 and bis(2-mercaptoethyl)sulfide (1.0 g). Triethylamine (10 mg) was then added while the reaction mixture was cooled in an ice bath to an internal temperature below 30°C. The reaction mixture was stirred at room temperature for 24 hours, followed by the addition of 1 M hydrochloric acid (100 mL) and dichloromethane (100 mL). The organic phase was separated by separation. The resulting organic phase was passed through silica gel (10 mL), and 4-methoxyphenol (10 mg) was added as a polymerization inhibitor. The mixture was then concentrated under reduced pressure to obtain a colorless, transparent polyfunctional (meth)acrylate thioester composition (9.9 g) containing the following compound. Molecular weight measurement by GPC revealed a number average molecular weight (Mn) of 600 and a weight average molecular weight (Mw) of 3500.

[0087] [Chemistry 23]

[0088] (Synthesis example 3) In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet, and dropping funnel, GST (trithiol, 100.0 g, 383.9 mmol) was placed, diluted with dichloromethane (100 mL), and stirring was initiated. Next, while the reaction mixture was cooled in an ice bath to an internal temperature below 40°C, 3-chloropropionyl chloride (121.84 g, 959.7 mmol) was added dropwise. After stirring the reaction mixture at room temperature for 48 hours, pure water (100 mL) was added and the organic phase was separated by liquid separation. The resulting organic phase was washed twice with saturated aqueous sodium bicarbonate (100 mL) to obtain a dichloromethane solution of a composition containing GST (the following compound group) in which a portion of the thiol groups of GST were esterified with 3-chloropropionate. High-performance liquid chromatography (HPLC) analysis revealed a peak area ratio of 3-substituted: 2-substituted: 1-substituted: 56:38:6.

[0089] [Chemistry 24]

[0090] [Chemistry 25]

[0091] [Chemistry 26]

[0092] The resulting solution was placed in a four-necked flask equipped with a stirrer, thermometer, and dropping funnel. 150 mg of 4-methoxyphenol (a polymerization inhibitor) was added and dissolved while stirring at room temperature. Triethylamine (116.5 g, 1152 mmol) was then added dropwise while cooling the reaction mixture in an ice bath to an internal temperature below 40°C. After stirring the reaction mixture at room temperature for 1 hour, 1 M hydrochloric acid (300 mL) was added and the organic phase was separated by separation. The resulting organic phase was passed through silica gel (100 mL), 4-methoxyphenol (150 mg) was added as a polymerization inhibitor, and the mixture was concentrated under reduced pressure to obtain a colorless, transparent polyfunctional (meth)acrylate thioester composition (132.5 g) containing the following compound. Molecular weight measurement by GPC revealed a number average molecular weight (Mn) of 500 and a weight average molecular weight (Mw) of 1600.

[0093] [Chemistry 27]

[0094] (Synthesis Example 4) In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet, and dropping funnel, place MES (bis(2-mercaptoethyl)sulfide, 100.0 g, 648.1 mmol), dilute with dichloromethane (100 mL), and begin stirring. Next, while cooling the reaction mixture in an ice bath to an internal temperature below 40°C, add 3-chloropropionyl chloride (123.42 g, 972.1 mmol) dropwise. After stirring the reaction mixture at room temperature for 48 hours, pure water (100 mL) was added and the organic phase was separated by liquid separation. The resulting organic phase was washed twice with saturated aqueous sodium bicarbonate (100 mL) to obtain a dichloromethane solution of a composition containing MES (the following compound group) in which a portion of the thiol groups of MES were esterified with 3-chloropropionate.

[0095] [Chemistry 28]

[0096] The resulting solution was placed in a four-necked flask equipped with a stirrer, thermometer, and dropping funnel. 4-Methoxyphenol (150 mg) was added as a polymerization inhibitor and dissolved while stirring at room temperature. Triethylamine (144.28 g, 1430 mmol) was then added dropwise while cooling the reaction mixture in an ice bath to an internal temperature below 40°C. After stirring the reaction mixture at room temperature for 1 hour, 1 M hydrochloric acid (300 mL) was added and the organic phase was separated by separation. The resulting organic phase was passed through silica gel (100 mL), 4-methoxyphenol (150 mg) was added as a polymerization inhibitor, and the mixture was concentrated under reduced pressure to obtain a colorless, transparent polyfunctional (meth)acrylate thioester composition (121.5 g) containing the following compound. Molecular weight measurement by GPC revealed a number average molecular weight (Mn) of 700 and a weight average molecular weight (Mw) of 2000.

[0097] [Chemistry 29]

[0098] (Molecular weight determination) The number average molecular weight (Mn) and weight average molecular weight (Mw) of the multifunctional (meth)acrylic acid thioester compositions in Synthesis Examples 1 to 4 were measured by gel permeation chromatography (GPC) according to the following procedure. (1) Preparation of sample solution A polyfunctional (meth)acrylic acid thioester composition was dissolved in tetrahydrofuran to a concentration of 1 g / 100 mL. The solution was then filtered through a 1 μm pore size filter (Membrane Solutions, trade name: Syringe Filter PTFE013100) to remove insoluble components, thereby preparing a sample solution. (2) Molecular weight determination Using a GPC measuring apparatus (Alliance, manufactured by Waters), tetrahydrofuran (Fujifilm Wako Pure Chemical Industries, Ltd., for high-performance liquid chromatography) was flowed at a flow rate of 1.0 mL / min as a washing solution. Three analytical columns (gel permeation columns, manufactured by Agilent, PLgel 5 μm Mixed-C) were connected in series and stabilized in a 40°C thermostat. 10 μL of the sample solution was injected into the column and the measurement was performed. A differential refractive index (RI) detector was used. The molecular weight of the sample was calculated based on a pre-prepared calibration curve. This calibration curve was created using several monodisperse polystyrenes (manufactured by Agilent) of known molecular weight as standard samples.

[0099] This application claims priority based on Japanese patent application No. 2022-052197 filed on March 28, 2022, and all contents disclosed therein are incorporated into this application.

[0100] none

Claims

1. A curable composition comprising a polyfunctional (meth)acrylate thioester composition, said polyfunctional (meth)acrylate thioester composition comprising a polyfunctional (meth)acrylate thioester compound (A) represented by the following formula (1), wherein when the total of said polyfunctional (meth)acrylate thioester composition is set to 100% by mass, the content of said compound (A) in said polyfunctional (meth)acrylate thioester composition is 70% by mass or more, and the content of said polyfunctional (meth)acrylate thioester composition in the curable composition is 50 parts by mass or more relative to 100 parts by mass of said curable composition, wherein in the following formula (1), in X, the number of alkyl groups substituted by the following formula (2) is 2, (in said formula (1), n ​​is an integer of 5 or more, X represents any alkyl group in which a methylene group can be substituted by a carbonyl group with a carbonyl group having a carbonyl group number of 1 or more and 4 or less, any hydrogen atom in the alkyl group needs to be substituted by the following formula (2), and R1 and R2 independently represent a hydrogen atom or a methyl group respectively) (In the formula (2), R3 represents a hydrogen atom or a methyl group. Multiple R3s may be the same or different. W represents an alkyl group with 1 or more carbon atoms and less than 4 carbon atoms. o is an integer greater than 1.) 2. The hardening composition as described in claim 1, wherein, The weight average molecular weight of the polyfunctional (meth)acrylate thioester composition is above 1000 and below 100000.

3. The hardening composition as described in claim 1 or 2, wherein, The polyfunctional (meth)acrylate thioester compound (A) comprises at least one selected from the group consisting of compounds represented by formula (3) and formula (4) below, wherein in formulas (3) and (4) below, the number of alkyl groups substituted by the structure of formula (2) in X and Y is 2, (in formulas (3) and (4), m and n are each independently an integer greater than 2, X and Y each independently represent alkyl groups with 1 or more and 4 carbon atoms that need to be substituted by the structure of formula (2), multiple X and Y may be the same or different, R1 and R2 each independently represent a hydrogen atom or a methyl group).

4. The curing composition as claimed in claim 1 or 2 further comprises compound (B) represented by the following formula (5); (in the formula (5), Z1 and Z2 each independently represent an aromatic carbide ring or an alkyl group, any hydrogen atom may be substituted by an alkyl or alkoxy group, Z3 and Z4 each independently represent an aromatic carbide ring, any hydrogen atom may be substituted by an alkyl or alkoxy group, R1 and R3 each independently represent an alkyl group having 1 or more carbon atoms and less than 10 carbon atoms, R2 and R4 each independently represent a hydrogen atom or a methyl group, R5 and R6 each independently represent an alkyl group, m and n each independently represent an integer greater than or equal to 0, and o, p, q and r are integers greater than or equal to 0 that satisfy the relationship o+q≦4 and p+r≦4).

5. The hardening composition as described in claim 1 or 2, wherein, The viscosity of the hardening component at 25°C, measured using an E-type viscometer at a rotation speed of 2.5 rpm, is ≥100 mPa·s and ≤10000 mPa·s.

6. The curing composition as described in claim 1 or 2 further comprises a polymerization initiator.

7. The curing composition as claimed in claim 1 or 2 further comprises at least one selected from the group consisting of silane coupling agents, antioxidants, ultraviolet absorbers and light stabilizers.

8. The hardening composition as described in claim 1 or 2, wherein, When the specific gravity of the curing component, measured according to Japanese Industrial Standard Z 8804:2012 using a specific gravity bottle, is set as d1, and the specific gravity of a test piece containing the curing component with a thickness of 250 μm is set as d2, the curing shrinkage rate of the curing component, expressed as (1-d1 / d2)×100, is 9.0% or less.

9. The hardening composition as described in claim 1 or 2, which can be used in optical materials.

10. A hardener formed by hardening a hardening composition as described in any one of claims 1 to 9.

11. The hardened material as claimed in claim 10, wherein, When fabricating a test piece containing the hardened material with a thickness of 250 μm, the light transmittance (T1) of the test piece at a wavelength of 400 nm is 81% or more.

12. The hardened material as claimed in claim 11, wherein, The test piece was heated in an oven set at 125°C for 168 hours in air. When the light transmittance of the test piece at a wavelength of 400 nm after heat treatment was set as T2, the change rate of light transmittance after heating, expressed as (T1-T2) / T1×100, was less than 7.0%.

13. The hardened material as described in any one of claims 10 to 12, wherein, When preparing a test piece with a thickness of 250 μm containing the hardened material, the refractive index (nD) of the test piece for D-rays (589.3 nm) is 1.600 or higher.

14. The hardened material as claimed in any one of claims 10 to 12, wherein, When preparing a test piece with a thickness of 250 μm containing the hardened material, the Abbe number (νD) of the test piece, as determined by the American Society for Testing and Materials (ASTM) D542, is 20 or greater.

15. A molded article comprising a hardened material as described in any one of claims 10 to 14.

16. An optical material comprising a shaped body as described in claim 15.

17. The optical material as claimed in claim 16, further comprising a glass substrate, wherein the optical material is a laminate of the shaped body and the glass substrate.

18. The optical material as described in claim 16 or 17, which is an optical lens.

19. A method for manufacturing a polyfunctional (meth)acrylate thioester composition, comprising the method of manufacturing a polyfunctional (meth)acrylate thioester composition contained in a curable composition as described in any one of claims 1 to 3, the method comprising the steps of: converting 0.5 equivalents or more and 0.9 equivalents or less of all thiol groups in a polythiol compound to functional groups represented by the following structural formula; and then subjecting the obtained compound to a β-desorption reaction and an enthiol reaction, thereby synthesizing a polyfunctional (meth)acrylate thioester compound; (in the structural formula, X represents a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and R represents a hydrogen atom or a methyl group).

20. A method for manufacturing a polyfunctional (meth)acrylate thioester composition, comprising the steps of reacting a polythiol compound with a polythioacrylate compound via an enylthiol reaction.