Composition, and optical material and lens using the same

Abstract

The present invention makes it possible to provide a composition comprising a compound (a) that is represented by formula (1) and a compound (b) that is represented by formula (2). (1) [In formula (1), Ar represents an aromatic ring, m represents an integer of 2-8, n represents an integer of 0-6, where m+n is not more than the number of carbon atoms constituting the aromatic ring, and each R1 independently represents an alkylthio group, a halogen group, a hydroxy group, a dialkylthiocarbamoyl group, or a dialkylcarbamoylthio group.] (2) [In formula (2), p represents an integer of 0-4, and q represents an integer of 0-2.]

Description

[Technical Field]

[0001] The present invention relates to a composition and an optical material and a lens using the same. [Background technology]

[0002] Optical materials, particularly those used for eyeglass lenses, are required to have optical properties such as heat resistance, low specific gravity, high transparency, low yellowness index, high refractive index, and high Abbe number. In recent years, there has been a demand for even higher performance, and optical materials with high refractive index and high Abbe number are particularly in demand.

[0003] Polymerizable compositions for optical materials using episulfide compounds have attracted attention as materials for achieving high refractive indexes and high Abbe numbers. For example, Patent Document 1 reports that in recent years, many organic compounds having sulfur atoms have been developed for the purpose of achieving high refractive indexes and high Abbe numbers. Among these, polyepisulfide compounds having sulfur atoms are known to have a good balance between refractive index and Abbe number (Patent Document 1). Although optical materials obtained from the polyepisulfide compounds of these inventions have achieved a high refractive index of 1.7 or more, materials with even higher refractive indexes are desired, and optical materials have been proposed that use compositions for optical materials containing organic compounds with cyclic skeletons containing sulfur, selenium, or tellurium atoms, and have achieved a refractive index of 1.73 or more (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 09-110979 [Patent Document 2] Patent No. 6773033 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the polymerizable composition described in Patent Document 2, an optical material with a high refractive index can be obtained. However, the high refractive index optical material does not have sufficient oxidation resistance and tends to be easily discolored during long-term storage and in processes requiring heat treatment. Therefore, an object of the present invention is to provide a composition from which an optical material with a high refractive index and excellent oxidation resistance can be obtained. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that the above-mentioned problems can be solved by combining a thiol compound having an aromatic skeleton with a polyepisulfide compound, and have thus completed the present invention. That is, the present invention is, for example, as follows.

[0007] [1] The following formula (1): [ka] [In the above formula, Ar represents an aromatic ring; m represents an integer of 2 to 8; n represents an integer of 0 to 6, provided that m+n is equal to or less than the number of carbon atoms constituting the aromatic ring; R 1 each independently represents an alkylthio group, a halogen group, a hydroxy group, a dialkylthiocarbamoyl group, or a dialkylcarbamoylthio group. and a compound (a) represented by the following formula (2): [ka] [In the above formula, p represents an integer of 0 to 4; q is an integer between 0 and 2. A composition comprising a compound (b) represented by the formula: [2] The composition according to [1] above, wherein m is 2 or 3. [3] The composition according to [1] or [2] above, wherein m+n is 2 to 6. [4] The composition according to any one of the above [1] to [3], wherein the content of the compound (a) is 1 to 30 mass % relative to the total mass of the composition. [5] The composition according to any one of the above [1] to [4], further comprising sulfur. [6] The composition according to any one of [1] to [5] above, further comprising 1,2,3,5,6-pentathiepane (c). [7] The composition according to any one of the above [1] to [6], further comprising a polythiol (d). [8] The polythiol (d) is selected from the group consisting of 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldisulfanyl)methanethiol, bis(2-mercaptoethyl)sulfide, 2,5-bis(mercaptomethyl)-1,4-dithiane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1 The composition described in [7] above, comprising at least one selected from the group consisting of 1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, tetramercaptopentaerythritol, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, and thiiranemethanethiol. [9] The composition according to any one of the above [1] to [8], further comprising a prepolymerization catalyst.

[10] The composition according to [9] above, wherein the prepolymerization catalyst comprises at least one selected from the group consisting of 2-mercapto-1-methylimidazole, 2-methyl-N-imidazole, and 1,2,2,6,6-pentamethylpiperidyl methacrylate.

[11] A pre-cured product obtained by pre-polymerizing the composition according to any one of the above [1] to

[10] .

[12] An optical material obtained by curing the composition according to any one of the above [1] to

[10] or the pre-cured product according to the above

[11] .

[13] An optical lens comprising the optical material described in

[12] above. [Effects of the Invention]

[0008] According to the present invention, there is provided a composition which can provide an optical material having a high refractive index and excellent oxidation resistance. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below with reference to embodiments and examples, but the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as desired within the scope of the present invention.

[0010] <Composition> The composition according to the present invention contains a compound (a) represented by formula (1) and a polyepisulfide compound (b) represented by formula (2). In addition, the composition may further contain sulfur, 1,2,3,5,6-pentathiepane (c), polythiol (d), a polymerizable compound, a prepolymerization catalyst, a polymerization catalyst, a polymerization regulator, an additive, and the like.

[0011] The composition contains the compound (a) represented by formula (1), i.e., a thiol compound having an aromatic skeleton, and the resulting cured product (optical material) can have a high refractive index and improved oxidation resistance. Therefore, the composition is preferably a composition for optical materials.

[0012] [Compound (a)] The compound (a) is represented by the following formula (1).

[0013] [ka]

[0014] m represents an integer of 2 to 8, and is preferably 2, 3, or 6, more preferably 2 or 3, and even more preferably 3, from the viewpoint of color tone and ease of synthesis.

[0015] n represents an integer of 0 to 6, preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0016] m+n is equal to or less than the number of carbon atoms constituting the aromatic ring represented by Ar, and is preferably equal to or less than 8 (m+n≦8), more preferably 2 to 6 or 3 to 6, even more preferably 2 to 3, and particularly preferably 3. m+n is preferably 3 because it provides higher heat resistance. Furthermore, "equal to or less than the number of carbon atoms constituting the aromatic ring" means that it does not exceed the number of carbon atoms contained in the aromatic ring. For example, in the case of a benzene ring, which is an aromatic ring composed of carbon and hydrogen, the number of carbon atoms constituting the ring is 6, so m+n is equal to or less than 6. Furthermore, in the case of a thiadiazole ring, which is a heteroaromatic ring, the number of carbon atoms constituting the ring is 2, so m+n is equal to or less than 2.

[0017] R 1 each independently represents an alkylthio group, a halogen group, a hydroxy group, a dialkylthiocarbamoyl group, or a dialkylcarbamoylthio group.

[0018] The alkylthio group is not particularly limited, but examples thereof include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, an isobutylthio group, a sec-butylthio group, a tert-butylthio group, a pentylthio group, and a hexylthio group.

[0019] The halogen group is not particularly limited, but examples thereof include a fluorine group (-F), a chlorine group (-Cl), a bromine group (-Br), and an iodine group (-I).

[0020] The dialkylthiocarbamoyl group is not particularly limited, but examples thereof include a dimethylthiocarbamoyl group, a diethylthiocarbamoyl group, and an ethylmethylthiocarbamoyl group.

[0021] The dialkylcarbamoylthio group is not particularly limited, but examples thereof include a dimethylcarbamoylthio group, a diethylcarbamoylthio group, and an ethylmethylcarbamoylthio group.

[0022] Ar represents an aromatic ring. Examples of the aromatic ring include aromatic rings composed of carbon and hydrogen, such as aromatic hydrocarbons, and heteroaromatic rings (aromatic rings containing heteroatoms). The aromatic ring represented by Ar has 2 or more carbon atoms, preferably 2 to 18, more preferably 2 to 12, and even more preferably 3 to 6. Ar is preferably a 5-membered or 6-membered ring, and more preferably a 6-membered ring. From the viewpoints of refractive index and ease of synthesis, preferred are benzene, naphthalene, fluorene, triazine, and thiadiazole, more preferably benzene and naphthalene, and even more preferably benzene.

[0023] Specific examples of the compound (a) include, but are not limited to, dimercaptobenzene compounds such as 1,3-dimercaptobenzene and 1,4-dimercaptobenzene; trimercaptobenzene compounds such as 1,3,5-trimercaptobenzene, 1,2,4-trimercaptobenzene and 1,2,5-trimercaptobenzene; 1-methylthio-3,5-dimercaptobenzene, 1-methylthio-2,4-dimercaptobenzene, 1-methylthio-2,5-dimercaptobenzene; alkylthio-substituted dimercaptobenzene compounds such as 1-t-butylthio-3,5-dimercaptobenzene, 1-ethylthio-3,5-dimercaptobenzene, and 1-t-butylthio-3,5-dimercaptobenzene; halogen-substituted dimercaptobenzenes such as 1-fluoro-3,5-dimercaptobenzene, 1-chloro-3,5-dimercaptobenzene, 1-bromo-3,5-dimercaptobenzene, 1-chloro-2,4-dimercaptobenzene, and 1-chloro-2,5-dimercaptobenzene; hydroxyl-substituted dimercaptobenzene compounds such as 1-hydroxy-3,5-dimercaptobenzene, 1-hydroxy-2,4-dimercaptobenzene, and 1-hydroxy-2,5-dimercaptobenzene; dialkylthiocarbamoyl-substituted dimercaptobenzene compounds such as 1-dimethylthiocarbamoyl-3,5-dimercaptobenzene, 1-methylthiocarbamoyl-3,5-dimercaptobenzene, 1-methylthiocarbamoyl-2,4-dimercaptobenzene, and 1-methylthiocarbamoyl-2,5-dimercaptobenzene; and dialkylcarbamoylthio-substituted dimercaptobenzene compounds such as 1-dimethylcarbamoylthio-3,5-dimercaptobenzene, 1-methylcarbamoylthio-3,5-dimercaptobenzene, 1-dimethylcarbamoylthio-2,4-dimercaptobenzene, and 1-dimethylcarbamoylthio-2,5-dimercaptobenzene.Among these, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,3,5-trimercaptobenzene, 1-alkylthio-3,5-dimercaptobenzene, 1-halo-3,5-dimercaptobenzene, 1-hydroxy-3,5-dimercaptobenzene, 1-dialkylthiocarbamoyl-3,5-dimercaptobenzene, 1-alkylcarbamoylthio-3,5-dimercaptobenzene, 1,5-naphthalenedithiol, 2,7-naphthalenedithiol, 9,9-bis(4-mercaptophenyl)fluorene, thiocyanuric acid, and bismuthiol are preferred, and 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,3,5-trimercaptobenzene, and 1,5-naphthalenedithiol are more preferred, and 1,3,5-trimercaptobenzene is even more preferred from the viewpoint of a higher refractive index. The above-mentioned compounds (a) may be used alone or in combination of two or more.

[0024] The content of compound (a) is preferably 0.1 to 30 mass %, more preferably 0.5 to 25 mass %, even more preferably 1 to 20 mass %, and particularly preferably 2 to 10 mass %, relative to the total mass of the composition. When the content of compound (a) is within the above range, a sufficiently high refractive index and an improved oxidation resistance can be obtained.

[0025] [Compound (b)] The compound (b) is represented by the following formula (2).

[0026] [ka]

[0027] p represents an integer of 0 to 4, preferably 0 to 2, and more preferably 0 or 1. q represents an integer of 0 to 2, and is preferably 0 or 1.

[0028] Specific examples of compound (b) include, but are not limited to, bis(β-epithiopropyl) sulfide and bis(β-epithiopropyl) disulfide. Of these, bis(β-epithiopropyl) sulfide is preferred. The above-mentioned compound (b) may be used alone or in combination of two or more. Note that bis(β-epithiopropyl) sulfide corresponds to the compound in the above formula (2) where p=q=0, and bis(β-epithiopropyl) disulfide corresponds to the compound in the above formula (2) where p=0 and q=1.

[0029] The content of compound (b) is preferably 40 to 90 mass %, more preferably 45 to 85 mass %, and particularly preferably 50 to 80 mass %, based on the total mass of the composition. When the content of compound (b) is within the above range, it is possible to improve the curing reactivity while ensuring heat resistance, which is preferable.

[0030] [sulfur] In one embodiment, the composition may further include sulfur, which can improve the refractive index of the resulting optical material.

[0031] The form of sulfur is not particularly limited and may be any form. Specific forms include finely divided sulfur, colloidal sulfur, precipitated sulfur, crystalline sulfur, and sublimed sulfur. Among these, finely divided sulfur is preferred from the viewpoint of dissolution rate.

[0032] The particle size (diameter) of sulfur is preferably smaller than 10 mesh (opening 1.70 mm), more preferably smaller than 30 mesh (opening 500 μm), and even more preferably smaller than 60 mesh (opening 250 μm). A particle size of sulfur smaller than 10 mesh is preferable because sulfur is easily dissolved.

[0033] The purity of sulfur is not particularly limited, but is preferably 98% or more, more preferably 99.0% or more, even more preferably 99.5% or more, and particularly preferably 99.9% or more. A sulfur purity of 98% or more is preferable because the color tone of the resulting optical material is further improved.

[0034] The sulfur content is preferably 0 to 30% by mass, more preferably 0.1 to 25% by mass, and even more preferably 1 to 25% by mass, relative to the total mass of the composition. A sulfur content within the above range is preferred because it provides an excellent balance between the refractive index improvement effect and solubility.

[0035] [1,2,3,5,6-pentathiepan(c)] 1,2,3,5,6-Pentathiepane (c) is a compound represented by the following formula (3), and has the effect of improving the refractive index of the resulting optical material.

[0036] [ka]

[0037] The method for obtaining 1,2,3,5,6-pentathiepane (c) is not particularly limited, and it may be a commercially available product, or it may be extracted from natural products such as crude oil, animals, and plants, or it may be synthesized by a known method. Examples of the synthesis method for synthesizing 1,2,3,5,6-pentathiepane (c) include those described in N. Takeda et al., Bull. Chem. Soc. Jpn., 68, 2757 (1995), F. Feher et al., Angew. Chem. Int. Ed., 7, 301 (1968), GW Kutney et al., Can. J. Chem, 58, 1233 (1980), etc.

[0038] The content of 1,2,3,5,6-pentathiepane (c) is preferably 0 to 40% by weight, more preferably 0.1 to 35% by weight, and even more preferably 1 to 30% by weight, relative to the total weight of the composition. When the content of 1,2,3,5,6-pentathiepane (c) is within the above range, the resulting optical material can have both a high refractive index and high transparency, which is preferable.

[0039] [Polythiol (d)] Polythiol (d) refers to a compound having two or more thiol groups (-SH) per molecule. In this case, compounds corresponding to compound (a) (thiol compounds having an aromatic skeleton) are not included in polythiol (d).

[0040] The polythiol (d) is not particularly limited, but from the viewpoint of a high color tone improving effect, 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldisulfanyl)methanethiol, bis(2-mercaptoethyl)sulfide, 2,5-bis(mercaptomethyl)-1,4-dithiane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio) )propane, tetramercaptopentaerythritol, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, and thiiranemethanethiol are preferred, bis(2-mercaptoethyl)sulfide, 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldisulfanyl)methanethiol, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane are more preferred, and bis(2-mercaptoethyl)sulfide, 1,2,6,7-tetramercapto-4-thiaheptane, and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane are even more preferred. The above-mentioned polythiols (d) may be used alone or in combination of two or more.

[0041] The content of polythiol (d) is preferably 0.1 to 30 mass %, more preferably 0.1 to 20 mass %, further preferably 0.5 to 20 mass %, and particularly preferably 1 to 15 mass %, relative to the total mass of the composition. The content of polythiol (d) within the above range is preferred because it provides a good balance between color stabilization effect and heat resistance.

[0042] [Polymerizable compound] In one embodiment, the composition may further contain a polymerizable compound. By including the polymerizable compound, the physical properties of the optical material can be adjusted. Here, the "polymerizable compound" means a compound that can be copolymerized with compound (b).

[0043] The polymerizable compound is not particularly limited as long as it is a compound copolymerizable with compound (b), and examples thereof include episulfide compounds other than compound (b), vinyl compounds, methacrylic compounds, acrylic compounds, allyl compounds, etc. These compounds may be used alone or in combination of two or more.

[0044] The amount of the polymerizable compound added is not particularly limited as long as it is within a range that does not impair the effects of the present invention, and is, for example, preferably 0 to 30% by mass, more preferably 1 to 30% by mass, and even more preferably 1 to 20% by mass, relative to the total mass of the composition.

[0045] [Prepolymerization catalyst] In one embodiment, the composition may further include a prepolymerization catalyst. By including the prepolymerization catalyst, a precured product described below can be suitably produced.

[0046] The prepolymerization catalyst is not particularly limited, but examples thereof include imidazoles, phosphines, thioureas, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, secondary iodonium salts, hindered amines, etc. Among these, imidazoles and hindered amines are preferred from the viewpoint of good compatibility with the composition.

[0047] The imidazoles are not particularly limited, but include N-benzylimidazole, 4-methylimidazole, 4-ethylimidazole, 1-phenylimidazole, 2-methyl-N-methylimidazole, and the like.

[0048] The hindered amine is not particularly limited, but examples thereof include 1,2,2,6,6-pentamethylpiperidyl methacrylate, 1,2,2,6,6-pentamethylpiperidyl acrylate, and 1,2,2,6,6-pentamethylpiperidyl-4-vinylbenzoate.

[0049] Among these, the prepolymerization catalyst preferably contains at least one selected from the group consisting of 2-mercapto-1-methylimidazole, 2-methyl-N-imidazole, and 1,2,2,6,6-pentamethylpiperidyl methacrylate. The above prepolymerization catalysts may be used alone or in combination of two or more.

[0050] The amount of prepolymerization catalyst added cannot be determined in general because it varies depending on the components of the composition, the mixing ratio, and the polymerization and curing method. However, it is usually preferably 0.0001% by mass to 10% by mass, and more preferably 0.003% by mass to 3.0% by mass, relative to 100% by mass of the total of compound (a), polythiol (b), compound (c), and sulfur. Prepolymerization catalysts added in an amount of 0.0001% by mass or more are preferred because the prepolymerization reaction proceeds smoothly. On the other hand, prepolymerization catalysts added in an amount of 10% by mass or less are preferred because they provide high oxidation resistance.

[0051] [Polymerization catalyst] In one embodiment, the composition may further include a polymerization catalyst, which allows the composition to be suitably polymerized to produce an optical material.

[0052] The polymerization catalyst is not particularly limited, but includes amines, phosphines, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, secondary iodonium salts, mineral acids, Lewis acids, organic acids, silicic acids, tetrafluoroboric acids, peroxides, azo compounds, condensates of aldehydes and ammonia compounds, guanidines, thioureas, thiazoles, sulfenamides, thiurams, dithiocarbamates, xanthogenates, acidic phosphate esters, etc. Among these, amines, phosphines, quaternary ammonium salts, and quaternary phosphonium salts are preferred. These polymerization catalysts may be used alone or in combination of two or more.

[0053] The amount of the polymerization catalyst added is preferably 0.0001 to 10% by mass, more preferably 0.01 to 3% by mass, based on the total mass of the composition.

[0054] [Polymerization modifier] In one embodiment, the composition may further comprise a polymerization modifier. The polymerization modifier is not particularly limited, but examples thereof include halides of elements of Groups 13 to 16 of the long-term periodic table. Among these, halides of silicon, germanium, tin, and antimony are preferred, and chlorides of germanium, tin, and antimony having an alkyl group are more preferred. These polymerization modifiers may be used alone or in combination of two or more.

[0055] The amount of the polymerization modifier added is preferably 0.0001 to 5.0% by mass, and more preferably 0.01 to 2% by mass, relative to the total mass of the composition.

[0056] [Additives] In one embodiment, the composition may further contain an additive. Examples of the additive include, but are not limited to, an antioxidant, a bluing agent, an ultraviolet absorber, a deodorizer, an adhesion improver, a release improver, and a radical polymerization initiator. These additives may be used alone or in combination of two or more.

[0057] The content of the additives is preferably 0 to 10% by mass, more preferably 0.5 to 10% by mass, relative to the total mass of the composition.

[0058] [Composition of the composition] In one embodiment, the composition preferably has the following composition: Compound (a): 0.1 to 25% by mass, preferably 0.5 to 20% by mass; Compound (b): 45 to 85% by mass, preferably 50 to 80% by mass; Sulfur: 0 to 30% by mass, preferably 1 to 25% by mass; Pentathiepane (c): 0 to 40% by mass, preferably 1 to 30% by mass Polythiol (d): 0 to 30% by mass, preferably 1 to 20% by mass; Prepolymerization catalyst: 0 to 5% by mass, preferably 0 to 3% by mass; Polymerization catalyst: 0 to 5% by mass, preferably 0.0001 to 3% by mass; and Polymerization modifier: 0 to 5% by mass, preferably 0.0001 to 3% by mass; Includes:

[0059] <Method of producing the composition> The composition described above is not particularly limited and can be produced by a known method. Specifically, it can be produced by mixing the compound (a) and the compound (b), and, if necessary, sulfur, 1,2,3,5,6-pentathiepane (c), polythiol (d), etc.

[0060] <Preliminary cured product> According to one aspect of the present invention, a pre-cured product is provided. The pre-cured product is obtained by pre-polymerizing the above-described composition. Forming a pre-cured product is preferable from the viewpoints of slowing the rate of viscosity increase, improving the transparency of the optical material, and facilitating handling. In this specification, the term "pre-cured product" refers to a liquid having a viscosity of 5,000 mps or less, and includes polymers, partial polymers, oligomers, etc. formed by a polymerization reaction of at least one of compound (a), episulfide compound (b), compound (c), sulfur, and polymerizable compounds. In this specification, the "viscosity" refers to a value measured by the following method.

[0061] [Viscosity measurement method] The viscosity of the pre-cured product at 30°C is measured using a cone-plate viscometer DV2THA CP (manufactured by Brookfield AMETEK).

[0062] <Method of manufacturing pre-cured product> According to one aspect of the present invention, there is provided a method for producing a pre-cured product, the method including a pre-polymerization step of pre-polymerizing a composition.

[0063] [Prepolymerization process] The prepolymerization step is a step of prepolymerizing the composition. The composition used is the one described above. The composition preferably contains a prepolymerization catalyst.

[0064] The prepolymerization step is preferably carried out by casting into a mold or the like, from the viewpoint of carrying out the polymerization step described below following the prepolymerization. In this case, it is preferable to remove impurities by filtration using a filter or the like having a pore size of about 0.1 to 5 μm before casting, from the viewpoint of improving the quality of the optical material.

[0065] The temperature of the prepolymerization is preferably from -10 to 160°C, more preferably from 0 to 100°C, and even more preferably from 20 to 80°C.

[0066] The prepolymerization time is preferably 0.1 to 480 minutes, more preferably 0.1 to 420 minutes, and even more preferably 0.1 to 360 minutes.

[0067] In one embodiment, the prepolymerization is preferably carried out at −10 to 160° C. for 0.1 to 480 minutes, more preferably at 0 to 100° C. for 0.1 to 420 minutes, and even more preferably at 20 to 80° C. for 0.1 to 360 minutes.

[0068] The prepolymerization may be carried out at normal pressure, under increased pressure, or under reduced pressure. When the prepolymerization is carried out under reduced pressure, hydrogen sulfide, which promotes the reaction, is removed, and therefore the reaction usually proceeds more gently than when carried out under normal pressure. When the prepolymerization is carried out under normal pressure, the prepolymerization may be carried out in the air or in an inert gas.

[0069] In the prepolymerization step, it is preferable to detect the progress of the prepolymerization reaction. Examples of the detection method include, but are not limited to, liquid chromatography, viscosity measurement, specific gravity measurement, and refractive index measurement. Among these, refractive index measurement is preferable because it is simple. These detection methods may be used alone or in combination of two or more.

[0070] The progress of the prepolymerization reaction is preferably detected inline. In particular, when the prepolymerization is performed under pressure or reduced pressure, inline detection is more preferable because it eliminates the need to release the pressure or reduced pressure to obtain a measurement sample. When performing inline detection, for example, when measuring the refractive index, the detection unit of the refractometer can be immersed in the composition before prepolymerization and the prepolymerization reaction solution to detect the increase in refractive index that accompanies the progress of the reaction, thereby enabling the progress of the reaction to be controlled. In addition, when using a detection method in which the measured value of the refractive index or the like changes with temperature, it is preferable to perform multiple regression analysis of the measurement temperature, refractive index, refractive index at a reference temperature, etc., to determine in advance the relationship between the temperature of the detection unit and the refractive index. Specifically, it is preferable to use a refractometer equipped with a temperature correction function that can automatically convert the measured value to the refractive index at the reference temperature. Examples of inline refractometers include a system in which a light-emitting diode is used as a light source and the angle of light reflected by a prism is identified by a CCD cell.

[0071] <Optical materials> According to one aspect of the present invention, there is provided an optical material. The optical material is obtained by curing the above-described composition or the above-described pre-cured product. That is, the optical material is a cured product of the above-described composition or the pre-cured product.

[0072] The optical material according to this embodiment has a high refractive index and excellent oxidation resistance. Specifically, the refractive index of the optical material is preferably 1.71 or more, more preferably 1.72 or more, even more preferably 1.73 or more, and particularly preferably 1.75 or more. That is, the refractive index of the optical material obtained from the above-mentioned composition is preferably 1.71 or more, more preferably 1.72 or more, even more preferably 1.73 or more, and particularly preferably 1.75 or more. The "refractive index" value is measured by the method described in the Examples.

[0073] Furthermore, the oxidation resistance of the optical material is preferably such that the ΔYI value is 2 or less, more preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less. That is, the ΔYI value of the optical material obtained from the above-mentioned composition is preferably 2 or less, more preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less. In this specification, the "ΔYI value" is measured by the method described in the Examples.

[0074] The optical material according to this embodiment has a high refractive index and excellent oxidation resistance, and therefore it is possible to incorporate various comonomers into the composition and increase the amount of comonomer incorporated, thereby enabling the design of optical materials with a wide range of physical properties.

[0075] <Method of manufacturing optical materials> According to one aspect of the present invention, there is provided a method for producing an optical material, the method including a polymerization step of polymerizing the above-described composition or the above-described pre-cured product.

[0076] [Polymerization process] The polymerization step is a step of polymerizing the above-mentioned composition or the above-mentioned pre-cured product. The polymerization step is usually carried out by casting the composition or a pre-cured product into a mold or the like and polymerizing it. When using a composition, it is preferable to remove impurities by filtration using a filter with a pore size of about 0.1 to 5 μm before casting, from the viewpoint of improving the quality of the optical material.

[0077] In one embodiment, the polymerization step includes a step of increasing the temperature to a polymerization temperature, a step of maintaining the temperature at the polymerization temperature, and a step of decreasing the temperature.

[0078] The polymerization may be carried out in multiple stages. That is, the polymerization temperature may be maintained at two or more steps. In one embodiment, the polymerization step includes a step of increasing the temperature to a first polymerization temperature, a step of maintaining the temperature at the first polymerization temperature, a step of increasing the temperature to a second polymerization temperature, a step of maintaining the temperature at the second polymerization temperature, and a step of decreasing the temperature. In this case, the first polymerization temperature is lower than the second polymerization temperature. In another embodiment, the polymerization step includes a step of increasing the temperature to the first polymerization temperature, a step of maintaining the temperature at the first polymerization temperature, a step of decreasing the temperature to a second polymerization temperature, a step of maintaining the temperature at the second polymerization temperature, and a step of decreasing the temperature. In this case, the first polymerization temperature is higher than the second polymerization temperature.

[0079] The temperature increase rate in the temperature increase step is preferably 0.1°C to 100°C / h, and the temperature decrease rate in the temperature decrease step is preferably 0.1°C to 100°C / h.

[0080] The polymerization temperature is usually from -10 to 140°C, and preferably from 0 to 140°C.

[0081] The polymerization time is usually 1 to 100 hours, and preferably 1 to 72 hours. In this specification, the term "polymerization time" refers to the time including the time for the temperature increasing step and the temperature decreasing step.

[0082] After polymerization, the resulting optical material is preferably annealed. By performing the annealing treatment, distortion of the optical material can be prevented or suppressed. The annealing temperature is preferably 50 to 150°C. The annealing time is preferably 10 minutes to 5 hours.

[0083] The obtained optical material may be subjected to surface treatment such as dyeing, hard coating, impact-resistant coating, anti-reflection coating, anti-fogging coating, etc., as required.

[0084] <Applications of optical materials> The optical materials described above are useful for a variety of applications, including optical members, mechanical component materials, electrical and electronic component materials, automotive component materials, civil engineering and construction materials, and molding materials, as well as paints and adhesives. Among these, the optical materials are suitable for optical applications such as eyeglass lenses, (digital) camera imaging lenses, light beam focusing lenses, light diffusing lenses, and other lenses; LED encapsulants, optical adhesives, optical transmission bonding materials, optical fibers, prisms, filters, diffraction gratings, watch glasses, and transparent glass and cover glass for display devices; and display device applications such as substrates for display elements such as LCDs, organic EL displays, and PDPs, substrates for color filters, touch panel substrates, information recording substrates, display backlights, light guide plates, display protective films, anti-reflection films, anti-fogging films, and other coating agents (coating films). The optical materials are particularly preferably used for applications such as optical lenses, prisms, optical fibers, information recording substrates, and filters, and more preferably for optical lenses. That is, in one embodiment, an optical lens comprising the optical material described above is provided.

[0085] The optical lenses obtained from the composition according to the present invention are excellent in stability, hue, transparency, etc., and are therefore extremely useful in fields where expensive high refractive index glass lenses have traditionally been used, such as telescopes, binoculars, television projectors, etc. If necessary, they are preferably used in the form of aspherical lenses. [Example]

[0086] The present invention will be specifically explained below with reference to examples, but the embodiments can be modified as appropriate as long as the effects of the present invention are achieved. The optical materials were analyzed and evaluated by the following methods.

[0087] [Refractive index of optical materials] The refractive index of the optical material at 25° C. for e-line (546.1 nm) was measured using a digital precision refractometer KPR-2000 (manufactured by Shimadzu Corporation).

[0088] [Evaluation of oxidation resistance of optical materials] The increase in ΔYI value was measured after heating a 2.0 mm thick optical material in air at 110°C for 5 hours. The YI value was measured using a spectrophotometer CM-5 (manufactured by Konica Minolta Japan, Inc.) at 25°C.

[0089] [Synthesis Example 1: Synthesis of 1,3,5-trimercaptobenzene (hereinafter referred to as TMB)] [ka]

[0090] It was synthesized with reference to Beilstein Journal of Organic Chemistry, 8, 461-471, No. 53; 2012. Specifically, the synthesis is as follows. Specifically, a four-neck flask equipped with a thermometer and a dropping funnel was purged with nitrogen. Then, 400 g of N-methylpyrrolidone and 82.7 g (2067 mmol) of sodium hydroxide were added and stirred at 5°C. Subsequently, 186.4 g (2067 mmol) of t-butylthiol was added dropwise and stirred at 5°C for 3 hours. Furthermore, 50.0 g (275.56 mmol) of 1,3,5-trichlorobenzene was added, and the temperature was raised to 120°C and stirred for 24 hours. Next, the reaction solution was cooled to 25°C, 400 g of toluene was added, and the mixture was washed three times with 400 g of water. The solvent was then distilled off to obtain 45.3 g (132.3 mmol) of crude 1,3,5-tris(t-butylthio)benzene (TTBB).

[0091] The resulting crude TTBB (45.3 g, 132.3 mmol) was placed in a three-necked flask equipped with a thermometer, and the reaction vessel was purged with nitrogen. Then, 436 g of toluene was added and stirred at 20°C. Subsequently, 19.4 g (145.4 mmol) of aluminum chloride was added and stirred for 3 hours. 225 g of 20% sulfuric acid was added, and the toluene layer was washed with water three times. The solvent was then distilled off to obtain 16.1 g (92.4 mmol) of crude TMB.

[0092] The resulting crude TMB product was purified using a silica gel column to obtain a fraction (a-1) containing TMB1 (TMB purity 100%) and two fractions (a-2 and a-3) containing TMB1 and either TMB2 or TMB3. The results are shown in Table 1 below.

[0093] [Synthesis Example 2: Synthesis of TMB] [ka] The synthesis was carried out with reference to Bulletin de la Societe Chimique de France, (2), 302-8; 1987. Specifically, the synthesis is as follows.

[0094] Specifically, 30.0 g (238 mmol) of phloroglucinol and 375 g of N,N-dimethylformamide were added to a three-necked flask equipped with a thermometer. The reaction mixture was then cooled to 5°C, and 133.4 g (1189 mmol) of 1,4-diazabicyclo[2.2.2]octane and 147.0 g (1189 mmol) of dimethylthiocarbamoyl chloride were added and stirred for 24 hours. Next, 300 g of chloroform was added, followed by washing three times with 300 g of 10% aqueous NaOH solution. The solvent was then distilled off to obtain 73.8 g (190 mmol) of crude 1,3,5-tris(dimethylthiocarbamoyl)benzene.

[0095] 73.8 g of the obtained crude product of 1,3,5-tris(dimethylthiocarbamoyl)benzene was placed in a three-necked flask equipped with a thermometer and stirred at 240°C for 7 hours. After that, by cooling to 25°C, 73.8 g (190 mmol) of crude product of 1,3,5-tris(dimethylcarbamoylthio)benzene was obtained.

[0096] 73.8 g of the resulting crude 1,3,5-tris(dimethylcarbamoylthio)benzene was placed in a three-necked flask equipped with a thermometer. 826 g of diethylene glycol, 89.1 g of water, and 53.4 g (952 mmol) of potassium hydroxide were then added and stirred at 95°C for 10 hours. The mixture was then cooled to 25°C, and 370 g of 20% sulfuric acid and 740 g of chloroform were added. The organic layer was washed three times with water, and the solvent was distilled off to yield 15.9 g (91 mmol) of crude TMB.

[0097] The resulting crude TMB product was purified using a silica gel column to obtain a fraction (a-4) containing TMB1 (TMB purity 100%) and three fractions (a-5 to a-7) containing TMB1 and TMB4, TMB5, or TMB6. The results are shown in Table 1 below.

[0098] [ka]

[0099] [Table 1]

[0100] The following compounds (a) were purchased commercially. a-8: 1,3-Dimercaptobenzene (Tokyo Chemical Industry Co., Ltd.) a-9: 1,5-Naphthalenedithiol (Tokyo Chemical Industry Co., Ltd.) a-10: Bismuthiol (Tokyo Chemical Industry Co., Ltd.) [ka]

[0101] [Raw materials] As compound (b), the following compounds b-1 and b-2 were prepared. b-1: Bis(β-epithiopropyl) sulfide b-2: Bis(β-epithiopropyl) disulfide

[0102] [ka]

[0103] In addition, 1,2,3,5,6-pentathiepane (c) represented by the following structural formula was prepared.

[0104] [ka]

[0105] Furthermore, the following compounds d-1 to d-3 were prepared as polythiols (d). d-1: Bis(2-mercaptoethyl) sulfide d-2: 1,2,6,7-tetramercapto-4-thiaheptane d-3: 4,8-Dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane

[0106] [ka]

[0107] [Example 1] A composition was produced by mixing 10 parts by mass of compound a-1, 90 parts by mass of compound b-1, 0.02 parts by mass of tetra-n-butylphosphonium bromide as a polymerization catalyst, and 0.05 parts by mass of di-n-butyltin dichloride as a polymerization regulator, while performing vacuum degassing.

[0108] [Examples 2 to 21, Comparative Examples 1 to 5] A composition was produced in the same manner as in Example 1, except that the composition was changed as shown in Table 2 below.

[0109] [evaluation] The compositions produced in Examples 1 to 21 and Comparative Examples 1 to 5 were heated at 30°C for 10 hours, then heated to 100°C over 10 hours, and finally heated at 100°C for 5 hours to polymerize and harden. After allowing to cool, the compositions were annealed at 120°C for 30 minutes to produce optical materials. The refractive index and oxidation resistance of the produced optical materials are shown in Table 2 below.

[0110] [Table 2]

[0111] As is clear from the results in Table 2, the cured products (optical materials) obtained by curing the compositions of Examples 1 to 21 have a high refractive index and excellent oxidation resistance. On the other hand, in Comparative Examples 1 to 3, the aromatic polythiol (a) was not contained, and as a result, the oxidation resistance was insufficient. Furthermore, in Comparative Example 4, an aliphatic polythiol was used, but it was found that the refractive index was insufficient.

Claims

1. The following formula (1): 【Chemistry 1】 [In the above formula, Ar represents an aromatic ring selected from the group consisting of benzene and naphthalene; m represents an integer of 2 to 8; n represents an integer of 0 to 6; provided that m+n is equal to or less than the number of carbon atoms constituting the aromatic ring; R １ each independently represents an alkylthio group, a halogen group, a hydroxy group, a dialkylthiocarbamoyl group, or a dialkylcarbamoylthio group. and a compound (a) represented by the following formula (2): 【Chemistry 2】 [In the above formula, p represents an integer of 0 to 4; and q represents an integer of 0 to 2. A composition comprising a compound (b) represented by The composition, wherein the content of the compound (a) is 1 to 30% by mass relative to the total mass of the composition.

2. The composition of claim 1 , wherein m is 2 or 3.

3. 3. The composition according to claim 1, wherein m+n is 2 to 6.

4. The composition of any one of claims 1 to 3, further comprising sulfur.

5. The composition according to any one of claims 1 to 4, further comprising 1,2,3,5,6-pentathiepane (c).

6. 1,2,6,7-tetramercapto-4-thiaheptane, methanedithiol, (sulfanylmethyldisulfanyl)methanethiol, bis(2-mercaptoethyl)sulfide, 2,5-bis(mercaptomethyl)-1,4-dithiane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane The composition according to any one of claims 1 to 5, further comprising a polythiol (d) comprising at least one selected from the group consisting of lithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, tetramercaptopentaerythritol, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, and thiiranemethanethiol.

7. The composition of any one of claims 1 to 6, further comprising a prepolymerization catalyst.

8. 8. The composition of claim 7, wherein the prepolymerization catalyst comprises at least one selected from the group consisting of 2-mercapto-1-methylimidazole, 2-methyl-N-imidazole, and 1,2,2,6,6-pentamethylpiperidyl methacrylate.

9. A pre-cured product obtained by pre-polymerizing the composition according to any one of claims 1 to 8.

10. An optical material obtained by curing the composition according to any one of claims 1 to 8 or the pre-cured product according to claim 9.

11. An optical lens comprising the optical material of claim 10.

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