Method for producing polythioether compound

Abstract

The purpose of the present disclosure is to provide a method for efficiently and economically obtaining a polythioether compound by polymerizing an alicyclic episulfide compound by a ring-opening reaction. The present disclosure provides a method for producing a polythioether compound, the method being characterized by polymerizing an alicyclic episulfide compound by a ring-opening reaction in the presence of a base. An amine compound is preferred as the above-mentioned base. Moreover, a strong base is preferred as the base.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a polythioether compound. More specifically, it relates to a method for producing a polythioether compound by ring-opening polymerization of an alicyclic episulfide compound. This application claims priority to Patent Application No. 202010101345.1, filed in the People's Republic of China on February 19, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] Compared to glass, plastics are lighter, less likely to break, and easier to dye, and therefore have been widely used in recent years as various optical materials such as eyeglass lenses, camera lenses, optical fiber cables, prisms, information recording substrates, filters, etc. When using plastics as optical materials, particularly eyeglass lenses, the optical properties required are high refractive index so that the lens thickness can be reduced, and a high Abbe number to reduce chromatic aberration. However, the optical properties of general resins tend to be such that the Abbe number decreases as the refractive index increases, and therefore, vigorous efforts are being made to develop plastic lens materials that achieve both high refractive index and high Abbe number.

[0003] In recent years, in order to improve the refractive index and Abbe number in a balanced manner, methods have been investigated in which a compound having a sulfur atom (sulfur-containing compound) with high atomic refraction and relatively small dispersion is introduced into a resin composition. For example, Patent Document 1 reports a thiourethane resin obtained by reacting a polythiol compound with a polyisocyanate compound as the sulfur-containing compound, and Patent Documents 2 and 3 report resin materials containing a sulfur-containing compound such as an episulfide resin obtained by curing and polymerizing a linear alkyl sulfide-type episulfide compound as the sulfur-containing compound.

[0004] The thiourethane resin described in Patent Document 1 exhibits a high refractive index of about 1.60 when xylylene diisocyanates are used as the polyisocyanate to be reacted with the polythiol compound, but the aromatic ring of the xylylene group causes a low Abbe number, resulting in the problem of rainbows due to chromatic aberration. Furthermore, the episulfide resins described in Patent Documents 2 and 3 contain a linear alkyl sulfide-type episulfide compound, which is a sulfur-containing compound, and therefore form a cured product with a very high refractive index of about 1.7, but the Abbe number is about 35, resulting in poor balance of optical properties and limited use to additives for adjusting the refractive index.

[0005] On the other hand, Patent Document 4 describes that a curable episulfide resin composition containing an episulfide compound having an alicyclic structure in the molecule as a sulfur-containing compound (hereinafter, may be referred to as an "alicyclic episulfide compound") has an optimized sulfur concentration and an alicyclic structure, and therefore has high refractive index, a high Abbe number, and excellent optical properties with a good balance between the two.

[0006] The alicyclic episulfide compound of Patent Document 4 has problems in that the reaction is difficult to control and side reactions such as oxidation and desulfurization easily proceed. According to studies by the present inventors, it has been found that when an acid generator that is widely used as a polymerization initiator for epoxy compounds is used as a catalyst, the reaction rate of the ring-opening polymerization reaction of the alicyclic episulfide compound is fast and difficult to control.

[0007] Non-Patent Document 1 discloses a method for producing a polythioether compound by ring-opening polymerization of a (9-carbazolylmethyl)thiirane compound, which is a linear alkyl sulfide-type episulfide compound, using a thiol compound as an initiator and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a catalyst. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 60-199016 [Patent Document 2] Japanese Patent Application Publication No. 9-110979 [Patent Document 3] Japanese Patent Application Publication No. 10-298287 [Patent Document 4] Japanese Patent Application Publication No. 2019-008289 [Non-patent literature]

[0009] [Non-Patent Document 1] European Polymer Journal,117(2019)179-187 Summary of the Invention [Problem to be solved by the invention]

[0010] Non-Patent Document 1 does not disclose a ring-opening polymerization reaction using an alicyclic episulfide compound. In addition, a considerable amount of tetrahydrofuran (THF) or dimethylformamide (DMF) is used as a solvent, and moreover, expensive TBD is used in a stoichiometric amount relative to the thiol compound, which poses problems for industrial application.

[0011] Therefore, an object of the present disclosure is to provide a method for efficiently and economically obtaining a polythioether compound by ring-opening polymerization of an alicyclic episulfide compound. Another object of the present disclosure is to provide a curable composition containing the polythioether compound obtained by the above method. [Means for solving the problem]

[0012]

[0006] As a result of intensive research to solve the above-mentioned problems, the inventors of the present disclosure have found that when an alicyclic episulfide compound is reacted in the presence of a base, the ring-opening polymerization reaction is easily controlled and a polythioether compound can be obtained efficiently and economically. They also found that the obtained polythioether compound is useful as a component of a curable composition exhibiting high refractive index and a high Abbe number. The invention of the present disclosure has been completed based on these findings.

[0013] That is, the present disclosure provides a method for producing a polythioether compound, which comprises ring-opening polymerization of an alicyclic episulfide compound in the presence of a base.

[0014] In the method for producing a polythioether compound, the ring-opening polymerization may be carried out in the absence of a solvent.

[0015] In the method for producing a polythioether compound, the ring-opening polymerization may be carried out at a reaction temperature of 30° C. or higher.

[0016] In the method for producing a polythioether compound, the base may be an amine compound.

[0017] In the method for producing a polythioether compound, the base is preferably a strong base.

[0018] In the method for producing a polythioether compound, the ring-opening polymerization may further proceed in the presence of a thiol compound.

[0019] In the method for producing the polythioether compound, the base may be used in an amount of 0.001 equivalent or more and less than 1 equivalent per equivalent of the thiol group contained in the thiol compound.

[0020] In the method for producing a polythioether compound, the thiol compound may be a compound having two or more thiol groups in the molecule.

[0021] In the method for producing a polythioether compound, the alicyclic episulfide compound may contain a compound represented by the following formula (I): [ka] [In the above formula (I), X represents a monovalent organic group. Ring A represents an alicyclic ring having 3 to 10 carbon atoms. r represents a natural number. However, the upper limit of r is the number of hydrogen atoms that can be present when ring A does not have X. When r is 2 or more, the two or more Xs may be the same or different.]

[0022] The present disclosure also provides a curable composition comprising the polythioether compound produced by the method.

[0023] In the curable composition, the polythioether compound may have a structure represented by the following formula (II): [ka] [In formula (II), X represents a monovalent organic group. Ring A represents an alicyclic ring having 3 to 10 carbon atoms. r represents a natural number. However, the upper limit of r is the number of hydrogen atoms that can be present when ring A does not have X. When r is 2 or more, two or more Xs may be the same or different. q represents a natural number of 1 or more. When q is 2 or more, X and r in the group in [ ] may be the same or different.]

[0024] The curable composition may be a resin composition for an optical lens. The curable composition may be a resin composition for eyeglass lenses.

[0025] The present disclosure also provides a cured product of the curable composition. The present disclosure also provides an optical lens molded from a cured product of the curable composition. The present disclosure also provides a spectacle lens formed from a cured product of the curable composition. [Effects of the Invention]

[0026] According to the method of the present disclosure, the ring-opening polymerization reaction of an alicyclic episulfide compound can be easily controlled, and a polythioether compound can be efficiently and economically obtained. The obtained polythioether compound is useful as a component of a curable composition for obtaining a cured product having excellent optical properties, such as high refractive index and high Abbe number, with a good balance between the two. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a chart of the 1H-NMR spectrum of the alicyclic episulfide compound obtained in Synthesis Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] [Method of producing polythioether compound] The method for producing a polythioether compound of the present disclosure is characterized by ring-opening polymerization of an alicyclic episulfide compound in the presence of a base. The method for producing a polythioether compound of the present disclosure may be carried out in the coexistence of a base and other components such as a thiol compound described below.

[0029] [Alicyclic episulfide compounds] The alicyclic episulfide compound used in the present disclosure is a compound having at least one alicyclic episulfide group (an episulfide group composed of two adjacent carbon atoms and a sulfur atom constituting an alicyclic ring) in the molecule. The number of alicyclic episulfide groups contained in the alicyclic episulfide compound is not particularly limited as long as it is one or more, but from the viewpoint of reactivity in ring-opening polymerization, one or two alicyclic episulfide groups are preferred, and one is more preferred.

[0030] The alicyclic ring (aliphatic hydrocarbon ring) of the alicyclic episulfide compound is not particularly limited, and examples thereof include 3- to 10-membered cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane, norbornane ring, adamantane ring, tricyclo[5.2.1.0] ring, and the like. 2,6] A bridged hydrocarbon ring such as a decane ring is exemplified, and from the viewpoint of reactivity in ring-opening polymerization, a 5- or 6-membered cycloalkane is preferred.

[0031] Specific examples of the alicyclic episulfide compound include compounds represented by the following formula (I): [ka]

[0032] In the above formula (I), X represents a monovalent organic group. Examples of the monovalent organic group include a hydrocarbon group (monovalent hydrocarbon group), an alkoxy group, an alkenyloxy group, an aryloxy group, an aralkyloxy group, an acyloxy group, an alkylthio group, an alkenylthio group, an arylthio group, an aralkylthio group, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aralkyloxycarbonyl group, a glycidyl group, an epoxy group, an episulfide group, a cyano group, an isocyanate group, a carbamoyl group, an isothiocyanate group, and groups formed by bonding these groups to a linking group (a divalent group having one or more atoms) described below. In addition, a substituent such as an alkyl group may be bonded to one or more carbon atoms constituting the alicyclic ring in formula (I).

[0033] Examples of the hydrocarbon group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and groups in which two or more of these groups are bonded together.

[0034] Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a C methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, an isooctyl group, a decyl group, and a dodecyl group. 1-20 Examples of the alkenyl group include C alkyl groups such as vinyl groups, allyl groups, methallyl groups, 1-propenyl groups, isopropenyl groups, 1-butenyl groups, 2-butenyl groups, 3-butenyl groups, 1-pentenyl groups, 2-pentenyl groups, 3-pentenyl groups, 4-pentenyl groups, and 5-hexenyl groups. 2-20Examples of the alkynyl group include C alkynyl groups such as ethynyl and propynyl groups. 2-20 Examples include an alkynyl group.

[0035] Examples of the alicyclic hydrocarbon group include C cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cyclododecyl groups. 3-12 Cycloalkyl groups; C such as cyclohexenyl groups 3-12 Cycloalkenyl groups; C such as bicycloheptanyl and bicycloheptenyl groups 4-15 Examples include a bridged cyclic hydrocarbon group.

[0036] Examples of the aromatic hydrocarbon group include C groups such as phenyl and naphthyl groups. 6-14 Aryl groups (e.g., C 6-10 aryl groups).

[0037] Examples of the group in which the aliphatic hydrocarbon group and the alicyclic hydrocarbon group are bonded include a cyclohexylmethyl group, a methylcyclohexyl group, etc. Examples of the group in which the aliphatic hydrocarbon group and the aromatic hydrocarbon group are bonded include C groups such as a benzyl group and a phenethyl group. 7-18 C such as aralkyl group, cinnamyl group 6-10 Aryl-C 2-6 C such as alkenyl group, tolyl group 1-4 C such as alkyl-substituted aryl groups and styryl groups 2-4 Alkenyl-substituted aryl groups and the like are included.

[0038] The hydrocarbon group may have a substituent. The number of carbon atoms of the substituent in the hydrocarbon group is not particularly limited, but is preferably 0 to 20, more preferably 0 to 10. Examples of the substituent include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; hydroxyl groups; alkoxy groups such as methoxy groups, ethoxy groups, propoxy groups, isopropyloxy groups, butoxy groups, and isobutyloxy groups (for example, C 1-6 alkoxy groups; alkenyloxy groups such as allyloxy groups (e.g., C 2-6alkenyloxy group); phenoxy group, tolyloxy group, naphthyloxy group, etc., with C in the aromatic ring 1-4 Alkyl group, C 2-4 Alkenyl group, halogen atom, C 1-4 An aryloxy group (e.g., C 6-14 aryloxy group; aralkyloxy group such as benzyloxy group, phenethyloxy group (e.g., C 7-18 aralkyloxy groups; acyloxy groups such as acetyloxy groups, propionyloxy groups, (meth)acryloyloxy groups, and benzoyloxy groups (e.g., C 1-12 acyloxy group; mercapto group; alkylthio group such as methylthio group, ethylthio group (e.g., C 1-6 alkylthio groups; alkenylthio groups such as allylthio groups (e.g., C 2-6 alkenylthio group); phenylthio group, tolylthio group, naphthylthio group, etc., with C in the aromatic ring 1-4 Alkyl group, C 2-4 Alkenyl group, halogen atom, C 1-4 An arylthio group (e.g., C 6-14 arylthio group; aralkylthio group such as benzylthio group, phenethylthio group (e.g., C 7-18 aralkylthio groups; carboxyl groups; alkoxycarbonyl groups such as methoxycarbonyl groups, ethoxycarbonyl groups, propoxycarbonyl groups, and butoxycarbonyl groups (e.g., C 1-6 Alkoxy-carbonyl group; aryloxycarbonyl group such as phenoxycarbonyl group, tolyloxycarbonyl group, naphthyloxycarbonyl group (e.g., C 6-14 aryloxycarbonyl groups; aralkyloxycarbonyl groups such as benzyloxycarbonyl groups (e.g., C 7-18 aralkyloxy-carbonyl group; amino group; mono- or di-alkylamino group such as methylamino group, ethylamino group, dimethylamino group, diethylamino group (for example, mono- or di-C 1-6 alkylamino group; acylamino group such as acetylamino group, propionylamino group, benzoylamino group (e.g., C 1-11acylamino group); epoxy group-containing groups such as epoxy group, glycidyl group, glycidyloxy group, and cyclohexene oxide group; episulfide group-containing groups such as episulfide group, 2,3-episulfidepropyl group, 2,3-episulfidepropyloxy group, and episulfidecyclohexyl group; oxetanyl group-containing groups such as ethyloxetanyloxy group; acyl groups such as acetyl group, propionyl group, and benzoyl group; oxo group; and two or more of these may be optionally C 1-6 and groups bonded via an alkylene group.

[0039] In the above formula (I), ring A represents an alicyclic ring having 3 to 10 carbon atoms, and examples thereof include 3- to 10-membered cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane.

[0040] In the above formula (I), r represents a natural number (an integer of 0 or more). However, the upper limit of r is the number of hydrogen atoms that can be present when ring A does not have X. For example, when ring A is cyclopentane, r represents a natural number of 0 to 8, and when ring A is cyclohexane, r represents a natural number of 0 to 10. When r is 2 or more, the two or more Xs may be the same or different.

[0041] A preferred embodiment of X in the above formula (I) is an aliphatic hydrocarbon group, more preferably C 2-20 It is preferably an alkenyl group, more preferably a vinyl group. That is, the alicyclic episulfide compound is preferably a compound in which at least one of Xs contains a vinyl group, and specifically, a compound represented by the following formula (I-1) is preferred. [ka]

[0042] In the above formula (I-1), X and ring A have the same meanings as in formula (I). In the above formula (I-1), r1 represents a natural number (an integer of 0 or more), and r2 represents a natural number (an integer of 1 or more) of 1 or more, provided that the upper limit of the total of r1 and r2 is the number of hydrogen atoms that can be present when ring A does not have X.

[0043] The alicyclic episulfide compound is not particularly limited, but from the viewpoint of reactivity in ring-opening polymerization, a compound having an episulfide cyclohexyl group (an episulfide group composed of two adjacent carbon atoms and a sulfur atom constituting a cyclohexane ring) is preferred. That is, as the alicyclic episulfide compound, a compound having one or more episulfide cyclohexyl groups in the molecule is preferred. Specifically, a compound represented by the following formula (1) is preferred, a compound represented by the following formula (1-1) is more preferred, and a compound represented by the following formula (1-2) is even more preferred. [ka] [ka] [ka]

[0044] X in the formula (1) and formula (1-1) is a monovalent organic group, as in the formula (1). s represents a natural number from 0 to 10. s1 represents a natural number between 0 and 9, and s2 represents a natural number equal to or greater than 1. However, the upper limit of the sum of s1 and s2 is 10.

[0045] Furthermore, as a preferred embodiment of the compound represented by the above formula (1), from the viewpoint of reactivity in ring-opening polymerization, a compound represented by the following formula (2) is also preferred. [ka]

[0046] In the above formula (2), Y represents a single bond or a linking group (a divalent group having one or more atoms). Examples of the linking group include a divalent hydrocarbon group, an alkenylene group in which some or all of the carbon-carbon double bonds are episulfidized, a carbonyl group (-CO-), an ether bond (-O-), an ester bond (-COO-), an amide group (-CONH-), a carbonate group (-OCOO-), a sulfonyl group (-SO2-), and groups in which multiple of these are linked together. In addition, a substituent such as an alkyl group may be bonded to one or more of the carbon atoms constituting the alicyclic ring in formula (2).

[0047] In the above formula (2), X 1 and X 2 each independently represents an oxygen atom or a sulfur atom, and X 1 and X 2 At least one (preferably two) of the carbon atoms constituting the alicyclic ring in formula (2) may have a substituent such as an alkyl group bonded to it.

[0048] The compound represented by the above formula (2) is preferably a compound represented by the following formula (2-1). [ka]

[0049] Examples of the alicyclic episulfide compound in which Y in formula (2) is a single bond include a compound represented by the following formula (2a). [ka]

[0050] In the above formula (2a), X 3 and X 4 each independently represents an oxygen atom or a sulfur atom, and X 3 and X 4 At least one (preferably two) of the carbon atoms constituting the alicyclic ring in formula (2a) may have a substituent such as an alkyl group bonded to it.

[0051] Examples of the divalent hydrocarbon group include a linear or branched alkylene group having 1 to 18 carbon atoms and a divalent alicyclic hydrocarbon group. Examples of the linear or branched alkylene group having 1 to 18 carbon atoms include a methylene group, a methylmethylene group, a dimethylmethylene group, an ethylene group, a propylene group, and a trimethylene group. Examples of the divalent alicyclic hydrocarbon group include a divalent cycloalkylene group (including a cycloalkylidene group) such as a 1,2-cyclopentylene group, a 1,3-cyclopentylene group, a cyclopentylidene group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, and a cyclohexylidene group.

[0052] Examples of the alkenylene group in the alkenylene group in which some or all of the carbon-carbon double bonds have been episulfided or epoxidized (sometimes referred to as an "episulfided alkenylene group") include linear or branched alkenylene groups (including alkapolyenylene groups) having 2 to 8 carbon atoms, such as vinylene, propenylene, 1-butenylene, 2-butenylene, butadienylene, pentenylene, hexenylene, heptenylene, and octenylene. The episulfidated alkenylene group is preferably an alkenylene group in which all of the carbon-carbon double bonds have been episulfided or epoxidized, and more preferably an alkenylene group in which all of the carbon-carbon double bonds have been episulfided or epoxidized and have 2 to 4 carbon atoms.

[0053] The linking group Y is preferably a linking group containing an oxygen atom, and specific examples include -CO-, -O-CO-O-, -COO-, -O-, -CONH-, groups in which a plurality of these groups are linked together, and groups in which one or more of these groups are linked to one or more divalent hydrocarbon groups. Examples of the divalent hydrocarbon group include those exemplified above.

[0054] Representative examples of the alicyclic episulfide compound represented by the above formula (2) include 2,2-bis(3,4-episulfide cyclohexan-1-yl)propane, 2-(3,4-episolfidocyclohexan-1-yl)-2-(3,4-epoxycyclohexan-1-yl)propane, bis(3,4-episolfidocyclohexylmethyl)ether, (3,4-episolfidocyclohexylmethyl)(3,4-epoxycyclohexylmethyl)ether, 1,2-bis(3,4-episolfidocyclohexan-1-yl)ethane, 1-(3,4-episolfidocyclohexan-1-yl)-2-(3,4-epoxycyclohexan-1-yl)propane, bis(3,4-episolfidocyclohexylmethyl)ether, bis(3,4-episolfidocyclohexan-1-yl)ethane ... Examples of the bis(3,4-episulfidecyclohexane-1-yl)ethane include 1,2-episulfide-1,2-bis(3,4-episulfidecyclohexane-1-yl)ethane, 1,2-epoxy-1,2-bis(3,4-episulfidecyclohexane-1-yl)ethane, 1,2-episulfide-1-(3,4-episolfidocyclohexane-1-yl)-2-(3,4-epoxycyclohexane-1-yl)ethane, 1,2-episolfido-1-(3,4-episolfidocyclohexane-1-yl)-2-(3,4-epoxycyclohexane-1-yl)ethane, and compounds represented by the following formulas (2a) and (2-1) to (2-10). Note that l in the following formula (2-5) and m in the following formula (2-7) each represent an integer of 1 to 30. In the following formula (2-5), R is an alkylene group having 1 to 8 carbon atoms, and examples thereof include straight-chain or branched-chain alkylene groups such as methylene, ethylene, propylene, isopropylene, butylene, isobutylene, s-butylene, pentylene, hexylene, heptylene, and octylene. Among these, straight-chain or branched-chain alkylene groups having 1 to 3 carbon atoms such as methylene, ethylene, propylene, and isopropylene are preferred. In the following formulas (2-9) and (2-10), n1 to n6 each represent an integer of 1 to 30. In the following formula (2a), X 3 and X 4 each independently represents an oxygen atom or a sulfur atom, and X 3 and X 4 At least one (preferably two) of X is a sulfur atom. 5 and X 6each independently represents an oxygen atom or a sulfur atom, and X 5 and X 6 At least one (preferably two) of X is a sulfur atom. 7 and X 8 each independently represents an oxygen atom or a sulfur atom, and X 7 and X 8 At least one (preferably two) of X is a sulfur atom. 9 and X 10 each independently represents an oxygen atom or a sulfur atom, and X 9 and X 10 At least one (preferably two) of X is a sulfur atom. 11 and X 12 each independently represents an oxygen atom or a sulfur atom, and X 11 and X 12 At least one (preferably two) of X is a sulfur atom. 13 and X 14 each independently represents an oxygen atom or a sulfur atom, and X 13 and X 14 At least one (preferably two) of X is a sulfur atom. 15 and X 16 each independently represents an oxygen atom or a sulfur atom, and X 15 and X 16 At least one (preferably two) of X is a sulfur atom. 17 , X 18 and X 19 each independently represents an oxygen atom or a sulfur atom, and X 17 , X 18 and X 19 At least one (preferably two or more) of X is a sulfur atom. 20 , X 21 , X 22 and X 23 each independently represents an oxygen atom or a sulfur atom, and X 20 , X 21 , X 22 and X23 At least one (preferably two or more) of the groups is a sulfur atom. [ka]

[0055] [ka]

[0056] The alicyclic episulfide compounds represented by the above formulas (2a) and (2-1) to (2-10) can be produced using, as raw materials, corresponding commercially available alicyclic epoxy compounds such as those sold under the trade names "Celloxide 8000," "Celloxide 2021P," and "Celloxide 2081" (all manufactured by Daicel Corporation), according to the "method for producing an alicyclic episulfide compound" described below.

[0057] [Method for producing alicyclic episulfide compounds] The alicyclic episulfide compound used in the present disclosure can be produced by reacting a corresponding alicyclic epoxy compound (a compound in which all of the sulfur atoms of an alicyclic episulfide compound have been substituted with oxygen atoms; hereinafter, in this specification, this may be referred to as an "alicyclic epoxy compound") with a thiatating agent.

[0058] The alicyclic epoxy compound, which is a raw material for producing the alicyclic episulfide compound of the present disclosure, can be produced by a known method, and commercially available products such as those under the trade names "Celloxide 2021P," "Celloxide 2081," "Celloxide 2000," and "Celloxide 8000" (all manufactured by Daicel Corporation) can also be used.

[0059] The thiating agent used in the production of the alicyclic episulfide compound is not particularly limited as long as it is a compound that reacts with an epoxy group of an alicyclic epoxy compound to promote a reaction to generate an episulfide group (hereinafter, in this specification, this reaction may be referred to as an "episulfidation reaction"). One type of thiating agent may be used alone, or two or more types of thiating agents may be used in combination.

[0060] Thiating agents used in the episulfidation reaction of the present disclosure include thiocyanates, thioureas, and the like. Examples of the thiocyanate salt include lithium thiocyanate, sodium thiocyanate, potassium thiocyanate, rubidium thiocyanate, cesium thiocyanate, silver thiocyanate, cobaltous thiocyanate, mercury thiocyanate, thallium (I) thiocyanate, cuprous thiocyanate, lead dithiocyanate, nickel dithiocyanate, barium dithiocyanate, ammonium thiocyanate, and guanidine thiocyanate. Of these, sodium thiocyanate, potassium thiocyanate, and ammonium thiocyanate are preferred in terms of availability and excellent reactivity.

[0061] Examples of the thioureas include thiourea, N,N'-dimethylthiourea, N,N,N',N'-tetramethylthiourea, N,N'-diethylthiourea, propylthiourea, N,N'-diisopropylthiourea, N,N'-dibutylthiourea, N-methyl-N'-(2-methyl-2-propenyl)thiourea, N-phenylthiourea, N,N'-diphenylthiourea, 1-methyl-2-imidazolidinthione, 1-benzyl-2-thiourea, N-(3,5-dimethylphenyl)thiourea, N-(2,6-dimethylphenyl)thiourea, and N-(2,3-dimethylphenyl)thiourea. N-(phenyl)thiourea, N-(2,4,6-trimethylphenyl)thiourea, N,N'-bis(2-methylphenyl)thiourea, N,N'-bis(3,5-dimethylphenyl)thiourea, N,N'-bis(2,6-dimethylphenyl)thiourea, N,N'-bis(2,4,6-trimethylphenyl)thiourea, N-(2-chlorophenyl)thiourea, N-(3-chlorophenyl)thiourea, N-(4-chlorophenyl)thiourea, N-(3,4-dichlorophenyl)thiourea, N-(3,5-dichlorophenyl)thiourea, N-(2,6-dichlorophenyl)thiourea N-(phenyl)thiourea, N-(2,4,6-trichlorophenyl)thiourea, N,N'-bis(2-chlorophenyl)thiourea, N,N'-bis(3,5-dichlorophenyl)thiourea, N,N'-bis(2,6-dichlorophenyl)thiourea, N-(2-fluorophenyl)thiourea, N-(3-fluorophenyl)thiourea, N-(4-fluorophenyl)thiourea, N-[2-(trifluoromethyl)phenyl]thiourea, N-[3-(trifluoromethyl)phenyl]thiourea, N-[4-(trifluoromethyl)phenyl]thiourea, N-( 2,6-difluorophenyl)thiourea, N-(2,4-difluorophenyl)thiourea, N-(2,3-difluorophenyl)thiourea, N-(2,4,6-trifluorophenyl)thiourea, N,N'-bis(2-fluorophenyl)thiourea, N,N'-bis(2,6-difluorophenyl)thiourea, N,N'-bis(2,4,6-trifluorophenyl)thiourea, N-(2-cyanophenyl)thiourea, N-(3-cyanophenyl)thiourea, N-(4-cyanophenyl)thiourea, N-(3,5-dicyanophenyl)thiourea, N,N'-bis(4-cyanophenyl)thiourea, N,N'-bis(3,5-dicyanophenyl)thiourea, N-(2-methoxyphenyl)thiourea, N-(3-methoxyphenyl)thiourea, N-(4-methoxyphenyl)thiourea, N-(2,6-dimethoxyphenyl)thiourea, N-(3,5-dimethoxyphenyl)thiourea, N-(2,4,6-tridimethoxyphenyl)thiourea, N,N'-bis(4-methoxyphenyl) )thiourea, N,N'-bis(2,6-dimethoxyphenyl)thiourea, N,N'-bis(2,4,6-tridimethoxyphenyl)thiourea, N-(2-nitrophenyl)thiourea, N-(3-nitrophenyl)thiourea, N-(4-nitrophenyl)thiourea, N-(3,5-dinitrophenyl)thiourea, N,N'-bis(3,5-dinitrophenyl)thiourea, etc., and thiourea is preferred from the viewpoints of economy and reactivity.

[0062] The amount of thiating agent used in the episulfidation reaction is not particularly limited as long as it allows the episulfidation reaction to proceed, but is preferably 100 to 2000 mol%, and more preferably 105 to 1000 mol%, relative to the total molar amount (100 mol%) of epoxy groups contained in the alicyclic epoxy compound used as a raw material. If the amount of thiating agent used is 100 mol% or more, the episulfidation reaction proceeds well. On the other hand, even if the amount of thiating agent used exceeds 2000 mol%, there is little effect on the progress of the episulfidation reaction and it is economically disadvantageous.

[0063] The episulfidation reaction can be carried out in the presence or absence of a solvent. It is particularly preferred to carry out the reaction in the presence of a solvent. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; nitriles such as acetonitrile, propionitrile, and benzonitrile; alcohols such as methanol, ethanol, isopropyl alcohol, and butanol; and water. Among these, alcohols are preferred as the solvent. One solvent may be used alone, or two or more solvents may be used in combination.

[0064] The amount of the solvent used is not particularly limited, and can be adjusted appropriately within the range of 0 to 2000 parts by weight relative to 100 parts by weight of the alicyclic epoxy compound depending on the desired reaction time and the like.

[0065] The reaction temperature for the episulfidation reaction is not particularly limited, but is preferably -100 to 150°C, and more preferably 10 to 80°C. The reaction time for the episulfidation reaction is not particularly limited, but is preferably 1 to 100 hours, and more preferably 3 to 50 hours. The episulfidation reaction can be carried out under normal pressure, or under increased or reduced pressure. The atmosphere in which the episulfidation reaction is carried out is not particularly limited, and may be, for example, an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere, or in the presence of oxygen such as air.

[0066] The episulfidation reaction gives an alicyclic episulfide compound. After completion of the episulfidation reaction, the alicyclic episulfide compound may be separated and purified by a separation means such as water washing, acid washing, alkali washing, filtration, concentration, distillation, extraction, crystallization, recrystallization, column chromatography, or a separation means comprising a combination of these.

[0067] [Method of producing polythioether compound] A polythioether compound can be obtained by ring-opening polymerization of an alicyclic episulfide compound in the presence of a base.

[0068] In the production method of a polythioether compound according to the present disclosure (hereinafter, sometimes simply referred to as the "production method of the present disclosure"), one type of alicyclic episulfide compound can be used alone, or two or more types can be used in combination.

[0069] In the production method of the present disclosure, a base is used as a catalyst. By using a base, the ring-opening polymerization reaction of the alicyclic episulfide group of the alicyclic episulfide compound can be efficiently promoted. The base can be used alone or in combination of two or more.

[0070] The base is not particularly limited, but an amine compound can be preferably used. The amine compound can be used alone or in combination of two or more.

[0071] The amine compound is not particularly limited, and examples thereof include ethylamine, n-propylamine, sec-propylamine, n-butylamine, sec-butylamine, isobutylamine, t-butylamine, pentylamine, hexylamine, heptylamine, octylamine, decylamine, laurylamine, myristyrylamine, 1,2-dimethylhexylamine, 3-pentylamine, 2-ethylhexylamine, allylamine, aminoethanol, 1-aminopropanol, 2-aminopropanol, aminobutanol, and aminopentanol. primary amines such as methyl methyl amine, ... Diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, dimethylaminopropylamine, diethylaminopropylamine, bis-(3-aminopropyl)ether, 1,2-bis-(3-aminopropoxy)ethane, 1,3-bis-(3-aminopropoxy)-2,2'-dimethylpropane, aminoethylethanolamine, 1,2-, 1,3- or 1,4-bisaminocyclohexane cyclohexane, 1,3- or 1,4-bisaminomethylcyclohexane, 1,3- or 1,4-bisaminoethylcyclohexane, 1,3- or 1,4-bisaminopropylcyclohexane, hydrogenated 4,4'-diaminodiphenylmethane, 2- or 4-aminopiperidine, 2- or 4-aminomethylpiperidine, 2- or 4-aminoethylpiperidine, N-aminoethylpiperidine, N-aminopropylpiperidine, N-aminoethylmorpholine, N-aminopropylmorpholine, isophoronediamine, menthanediamine, 1,4-bisaminopropylpiperazine, o-, m-, or p-phenylenediamine, 2,4- or 2,6-tolylenediamine, 2,4-toluenediamine, m-aminobenzylamine, 4-chloro-o-phenylenediamine, tetrachloro-p-xylylenediamine, 4-methoxy-6-methyl-m-phenylenediamine, m- or p-xylylenediamine, 1,5- or 2,6-naphthalenediamine, benzidine, 4,4'-bis(o-toluidine), dianisidine, 4,4'-diaminodiphenylmethane, 2,2-(4,4'-di (aminodiphenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-thiodianiline, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminoditolyl sulfone, methylenebis(o-chloroaniline), 3,9-bis(3-aminopropyl)2,4,8,10-tetraoxaspiro[5,5]undecane, diethylenetriamine, iminobispropylamine, methyliminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-aminoethyl primary polyamines such as 1,4-diaminopyridine, N-aminopropylpiperazine, 1,4-bis(aminoethylpiperazine), 1,4-bis(aminopropylpiperazine), 2,6-diaminopyridine, and bis(3,4-diaminophenyl)sulfone; diethylamine, dipropylamine, di-n-butylamine, di-sec-butylamine, diisobutylamine, di-n-pentylamine, di-3-pentylamine, dihexylamine, octylamine, di(2-ethylhexyl)amine, methylhexylamine, diallylamine, pyrrolidine, piperidine, 2-, 3- Secondary amines such as 4-picoline, 2,4-, 2,6-, and 3,5-lupetidine, diphenylamine, N-methylaniline, N-ethylaniline, dibenzylamine, methylbenzylamine, dinaphthylamine, pyrrole, indoline, indole, and morpholine; N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,2-diaminobutane, N,N'-dimethyl-1,3-diaminobutane, N,N'-dimethyl-1,4-diaminobutane, N,N'-dimethyl-1,5-diaminopentane, N,N'-dimethyl-1,6-diaminohexane, N,N'-dimethyl-1,7-diaminoheptane, N,N'-diethylethylenediamine, N,N'-diethyl-1,2-diaminopropane, N,N'-diethyl-1,3-diaminopropane, N,N'-diethyl-1,2-diaminobutane, N,N'-diethyl-1,3-diaminobutane, N,N'-diethyl-1,4-diaminobutane, N,N'-diethyl-1,6-diaminohexane, piperazine, 2-methylpiperazine, 2,5- or 2,6 -Dimethylpiperazine, homopiperazine, 1,1-di-(4-piperidyl)methane, 1,2-di-(4-piperidyl)ethane, 1,3-di-(4-piperidyl)propane, 1,4-di-(4-piperidyl)butane, tetramethylguanidine, and other secondary polyamines; trimethylamine, triethylamine, tri-n-propylamine, tri-isopropylamine, tri-1,2-dimethylpropylamine, tri-3-methoxypropylamine, tri-n-butylamine, tri-isobutylamine, tri-sec-butylamine, tripentylamine, tri -3-pentylamine, tri-n-hexylamine, tri-n-octylamine, tri-2-ethylhexylamine, tri-dodecylamine, tri-laurylamine, tri-cyclohexylamine, N,N-dimethylhexylamine, N-methyldihexylamine, N,N-dimethylcyclohexylamine, N,N-dicyclohexylmethylamine, N-methyldicyclohexylamine, triethanolamine, tribenzylamine, N,N-dimethylbenzylamine, diethylbenzylamine, triphenylamine, N,N-dimethylamino-p-chloramine Tertiary amines such as resol, N,N-dimethylaminomethylphenol, 2-(N,N-dimethylaminomethyl)phenol, N,N-dimethylaniline, N,N-diethylaniline, pyridine, quinoline, N-methylmorpholine, N-methylpiperidine, 2-(2-dimethylaminoethoxy)-4-methyl-1,3,2-dioxabornane; tetramethylethylenediamine, pyrazine, N,N'-dimethylpiperazine, N,N'-bis((2-hydroxy)propyl)piperazine, hexamethylenetetramine, N,N,N',N'-tetramethyl-1,Tertiary polyamines such as 3-butanamine, 2-dimethylamino-2-hydroxypropane, diethylaminoethanol, N,N,N-tris(3-dimethylaminopropyl)amine, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, and heptamethylisobiguanide; imidazole, N-methylimidazole, 2-methylimidazole, 4-methylimidazole, N-ethylimidazole, 2-ethylimidazole, 4-ethylimidazole, N-butylimidazole, 2-butylimidazole, N-undecylimidazole, 2-undecylimidazole, N-phenylimidazole, 2-phenylimidazole, N-benzylimidazole, 2-benzylimidazole, 1-benzyl-2-methylimidazole, N-(2' imidazoles such as N-(2'-cyanoethyl)-2-methylimidazole, N-(2'-cyanoethyl)-2-undecylimidazole, N-(2'-cyanoethyl)-2-phenylimidazole, 3,3-bis-(2-ethyl-4-methylimidazolyl)methane, adducts of alkylimidazoles and isocyanuric acid, and condensates of alkylimidazoles and formaldehyde; amidines such as 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, and 6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene-7, and guanidines such as 1,5,7-triazabicyclo[4.4.0]decene-5 and 7-methyl-1,5,7-triazabicyclo[4.4.0]decene-5. ,

[0072] As the base, from the viewpoint of reactivity of ring-opening polymerization, a strong base is preferable, and amidines such as 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, 6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene-7, etc., and guanidines such as 1,5,7-triazabicyclo[4.4.0]decene-5, 7-methyl-1,5,7-triazabicyclo[4.4.0]decene-5, etc. are preferable, and from the viewpoint of economy, 1,8-diazabicyclo[5.4.0]undecene-7 is more preferable. In addition, a "strong base" is defined as a base that has a high acid dissociation constant (pK a) refers to a group having 12 or more, preferably 13 or more bases.

[0073] The amount of the base used is not particularly limited, but is preferably 0.01 to 20 parts by weight, more preferably 0.01 to 15 parts by weight, even more preferably 0.05 to 12 parts by weight, and even more preferably 0.1 to 10 parts by weight, relative to 100 parts by weight of the alicyclic episulfide compound. More specifically, the base is preferably used in an amount of 0.0001 to 0.2 equivalents, preferably 0.0005 to 0.1 equivalents, more preferably 0.001 to 0.12 equivalents, and even more preferably 0.005 to 0.1 equivalents, per equivalent of the alicyclic episulfide group contained in the alicyclic episulfide compound. Using the base within the above range facilitates efficient ring-opening polymerization of the alicyclic episulfide compound. When two or more bases are used, it is preferable that the total amount of these bases satisfies the above range.

[0074] The production method of the present disclosure can be carried out in the presence or absence of a solvent. Among them, from the viewpoints of reactivity and economic efficiency, it is preferable to carry out the method in the absence of a solvent. By carrying out the method in the absence of a solvent, the reactivity is maintained while eliminating the need to remove the solvent, which is economical.

[0075] When the above solvent is used, examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; nitriles such as acetonitrile, propionitrile, and benzonitrile; alcohols such as methanol, ethanol, isopropyl alcohol, and butanol; and water. One solvent may be used alone, or two or more solvents may be used in combination.

[0076] When a solvent is used, the amount used is not particularly limited and can be adjusted appropriately within the range of 0 to 2000 parts by weight relative to 100 parts by weight of the alicyclic epoxy compound depending on the desired reaction time, etc.

[0077] [Thiol compounds] The manufacturing method of the present disclosure may further be carried out in the coexistence of a thiol compound. When a thiol compound is used in the manufacturing method of the present disclosure, it is believed that the thiol group reacts with the alicyclic episulfide group to cause a ring-opening polymerization reaction. In addition, since the sulfur concentration in the cured product described below can be adjusted, a cured product having a high refractive index, a high Abbe number, and a good balance between the refractive index and the Abbe number can be formed. However, since the ring-opening polymerization reaction proceeds sufficiently due to the catalytic action of the base even without the use of a thiol compound, the use of a thiol compound is not necessary. In other words, the manufacturing method of the present disclosure may be carried out in the absence of a thiol compound.

[0078] When the production method of the present disclosure is carried out in the presence of a thiol compound, the thiol compound is not particularly limited, but examples thereof include thiophenols, thiols, mercaptoalcohols, hydroxythiophenols, mercaptoorganic acids, and mercaptoamines.

[0079] The thiophenols are not particularly limited, but examples thereof include thiophenol, 4-tert-butylthiophenol, 2-methylthiophenol, 3-methylthiophenol, 4-methylthiophenol, o-dimercaptobenzene, m-dimercaptobenzene, p-dimercaptobenzene, and 1,3,5-trimercaptobenzene.

[0080] The thiols are not particularly limited, but examples thereof include methyl mercaptan, ethyl mercaptan, n-propyl mercaptan, n-butyl mercaptan, allyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, n-hexadecyl mercaptan, n-octadecyl mercaptan, cyclohexyl mercaptan, isopropyl mercaptan, tert-butyl mercaptan, tert-nonyl mercaptan, tert-dodecyl mercaptan, benzo ... Monothiols such as dimercaptan, 4-chlorobenzyl mercaptan, methyl thioglycolate, ethyl thioglycolate, n-butyl thioglycolate, n-octyl thioglycolate, methyl 3-mercaptopropionate, ethyl 3-mercaptopropionate, 3-methoxybutyl 3-mercaptopropionate, n-butyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, and n-octyl 3-mercaptopropionate, methanedithiol, 1,2-dimercaptoethane, 2,2 -Dimercaptopropane, 1,3-dimercaptopropane, 1,2,3-trimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis(2-mercaptoethyl) sulfide, 1,2-bis(2-mercaptoethylthio)ethane, 1,5-dimercapto-3-oxapentane, 1,8-dimercapto-3,6-dioxaoctane, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-di Mercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 1,1,1-tris(mercaptomethyl)propane, tetrakis(mercaptomethyl)methane, 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, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), 1,4-butanediol bis(2-mercaptoacetate), 1,4-butanediol bis(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), 1,1-dimercaptocyclohexane, 1,2-dimercaptocyclohexane, 1,3-dimercaptocyclohexane, 1,4-dimercaptocyclohexane Examples of suitable thiols include polyvalent thiols such as cyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, 2,5-bis(mercaptomethyl)-1,4-dithiane, 2,5-bis(mercaptoethyl)-1,4-dithiane, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, bis(4-mercaptophenyl)sulfide, bis(4-mercaptophenyl)ether, 2,2-bis(4-mercaptophenyl)propane, bis(4-mercaptomethylphenyl)sulfide, bis(4-mercaptomethylphenyl)ether, and 2,2-bis(4-mercaptomethylphenyl)propane.

[0081] The mercaptoalcohols are not particularly limited, but examples thereof include 2-mercaptoethanol, 2-mercaptopropanol, 3-mercaptopropanol, 2-hydroxypropyl mercaptan, 2-phenyl-2-mercaptoethanol, 2-phenyl-2-hydroxyethyl mercaptan, 3-mercapto-1,2-propanediol, 2-mercapto-1,3-propanediol, 2,3-dimercaptopropanol, 1,3-dimercapto-2-propanol, 2,2-dimethylpropane-1,3-dithiol, and glyceryl dithioglycolate.

[0082] The hydroxythiophenols are not particularly limited, but examples thereof include 2-hydroxythiophenol, 3-hydroxythiophenol, and 4-hydroxythiophenol.

[0083] The organic mercapto acids are not particularly limited, but examples thereof include mercaptocarboxylic acids such as 2-mercaptoacetic acid (thioglycolic acid) and 3-mercaptopropionic acid.

[0084] The mercaptoamines are not particularly limited, but examples thereof include mercaptoalkylamines such as 2-mercaptoethylamine, 3-mercaptopropylamine, and 3-mercaptobutylamine; and aminothiophenols such as 4-aminothiophenol.

[0085] As the thiol compound, a compound having two or more thiol groups in the molecule is preferred from the viewpoint that the molecular weight of the obtained polythioether compound is likely to be high. The number of thiol groups in the thiol compound molecule is preferably two or more, more preferably three or more, and even more preferably four or more.

[0086] Examples of compounds having two or more thiol groups in the molecule include o-dimercaptobenzene, m-dimercaptobenzene, p-dimercaptobenzene, 1,3,5-trimercaptobenzene, methanedithiol, 1,2-dimercaptoethane, 2,2-dimercaptopropane, 1,3-dimercaptopropane, 1,2,3-trimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis(2-mercaptoethyl)sulfide, 1,2-bis(2-mercaptoethylthio)ethane, 1,5-dimercapto-3-oxapentane, 1,8-Dimercapto-3,6-dioxaoctane, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 1,1,1-tris(mercaptomethyl)propane, tetrakis(mercaptomethyl)methane, 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, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), 1,4-butanediol bis(2-mercaptoacetate), 1,4-butanediol bis(3-mercaptopropionate) trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(3-mercaptopropionate), 1,1-dimercaptocyclohexane, 1,2-dimercaptocyclohexane, 1,3-dimercaptocyclohexane, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, 2,Examples of polyvalent thiols include 5-bis(mercaptomethyl)-1,4-dithiane, 2,5-bis(mercaptoethyl)-1,4-dithiane, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, bis(4-mercaptophenyl)sulfide, bis(4-mercaptophenyl)ether, 2,2-bis(4-mercaptophenyl)propane, bis(4-mercaptomethylphenyl)sulfide, bis(4-mercaptomethylphenyl)ether, 2,2-bis(4-mercaptomethylphenyl)propane, 2,3-dimercaptopropanol, 1,3-dimercapto-2-propanol, 2,2-dimethylpropane-1,3-dithiol, and glyceryl dithioglycolate.

[0087] When the production method of the present disclosure is carried out in the presence of a thiol compound, the amount of the thiol compound used is not particularly limited, but is preferably 0.1 to 200 parts by weight, more preferably 0.5 to 150 parts by weight, and even more preferably 0.6 to 120 parts by weight, relative to 100 parts by weight of the alicyclic episulfide compound. More specifically, the thiol compound is preferably used in a proportion such that 0.005 to 1.5 equivalents, preferably 0.005 to 1.2 equivalents, of thiol groups per equivalent of alicyclic episulfide groups contained in the alicyclic episulfide compound. Using an amount of the thiol compound of 0.1 part by weight or 0.005 equivalents or more makes it easier to adjust the molecular weight of the resulting polythioether compound within an appropriate range. On the other hand, using an amount of the thiol compound exceeding 200 parts by weight or 1.5 equivalents may result in a poor balance between the refractive index and Abbe number of the cured product, as described below. When two or more thiol compounds are used, it is preferable that the total amount of these thiol compounds satisfy the above range.

[0088] When the production method of the present disclosure is carried out in the presence of a thiol compound, the amount of base used relative to the thiol compound is not particularly limited. However, it is preferable to use the base in a proportion of 0.001 equivalents or more, preferably 0.005 equivalents or more, more preferably 0.01 equivalents or more, even more preferably 0.05 equivalents or more, and even more preferably 0.1 equivalents or more per equivalent of thiol groups contained in the thiol compound. Using the base in an amount greater than this range facilitates the ring-opening polymerization reaction of the alicyclic episulfide compound. On the other hand, it is preferable to use the base in an amount less than 1.0 equivalent, more preferably 0.5 equivalents or less, even more preferably 0.25 equivalents or less, and even more preferably 0.2 equivalents or less per equivalent of thiol groups contained in the thiol compound. Even if the base is used in an amount exceeding this range, the effect on reactivity is minimal, and from an economical perspective, it is preferable to use the base within this range. Note that when two or more thiol compounds and / or bases are used, it is preferable that the total amount of these thiol compounds and / or bases satisfies the above range.

[0089] The reaction temperature in the production method of the present disclosure is not particularly limited, but can be selected from the range of 0 to 150°C. Specifically, the reaction temperature is preferably 10°C or higher, more preferably 20°C or higher, even more preferably 30°C or higher, and even more preferably 40°C or higher. By carrying out the production method of the present disclosure at a certain reaction temperature or higher, the ring-opening polymerization reaction of the alicyclic episulfide compound is promoted, the reaction time is shortened, and productivity tends to be improved. Furthermore, the reaction temperature is preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and even more preferably 80°C or lower. Even if the reaction temperature exceeds this range, the effect on reactivity is small, and from an economical viewpoint, it is preferable to carry out the reaction at a temperature below this range.

[0090] The reaction time of the production method of the present disclosure is not particularly limited, but is preferably 1 minute to 500 hours, and more preferably 0.5 to 100 hours. The production method of the present disclosure can be carried out under normal pressure, or under increased or reduced pressure. The atmosphere in which the production method of the present disclosure is carried out is not particularly limited, and may be, for example, an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere, or in the presence of oxygen such as air.

[0091] A polythioether compound can be obtained by the production method of the present disclosure. After completion of the production method of the present disclosure, the polythioether compound may be separated and purified by a separation means such as water washing, acid washing, alkali washing, filtration, concentration, distillation, extraction, crystallization, recrystallization, column chromatography, or a combination thereof.

[0092] The number average molecular weight of the polythioether compound obtained by the production method of the present disclosure is not particularly limited, but is, for example, 500 to 50,000, preferably 600 to 30,000, and more preferably 800 to 20,000. When the number average molecular weight of the polythioether compound is within this range, the handleability of the curable composition described below tends to be improved. The number average molecular weight of the polythioether compound is the number average molecular weight converted into the molecular weight of polystyrene used as a molecular weight standard measured by gel permeation chromatography (GPC).

[0093] Although the reaction mechanism of the production method of the present disclosure is not clear, it is presumed that, for example, when an amine compound is used as a base, an unshared electron pair (lone pair) present on a nitrogen atom of the amine compound undergoes addition to an alicyclic episulfide group of an alicyclic episulfide compound, thereby causing ring-opening, and the generated thiol anion attacks an alicyclic episulfide group of another alicyclic episulfide compound, thereby causing ring-opening polymerization to proceed in a chain reaction (see the reaction scheme below). [ka]

[0094] In the above reaction scheme, t is a natural number of 1 or more, and other symbols have the same meanings as above. Therefore, it is presumed that the polythioether compound obtained by the production method of the present disclosure has, in the molecule, a structure represented by the following formula (II), preferably a structure represented by formula (IIa). [ka] [ka]

[0095] In formula (II) and formula (IIa), X, ring A, r, and s have the same meanings as above. q represents a natural number of 1 or more. When q is 2 or more, X, r, and s in the groups in [ ] may be the same or different. The reaction mechanism of the production method of the present disclosure and the structure of the polythioether compound described above are speculations, and the present disclosure is not limited thereto.

[0096] [Curable composition] The curable composition of the present disclosure includes a polythioether compound produced by the production method of the present disclosure. Therefore, the curable composition of the present disclosure is considered to preferably include a polythioether compound having a structure represented by the above formula (II), formula (IIa).

[0097] In the curable composition of the present disclosure, one type of polythioether compound may be used alone, or two or more types may be used in combination.

[0098] The content (blending amount) of the polythioether compound in the curable composition (100 wt%) of the present disclosure is not particularly limited, but is preferably 3 wt% or more and less than 100 wt%, more preferably 4 to 90 wt%, and even more preferably 5 to 80 wt%. If the content of the polythioether compound is less than 3 wt%, the refractive index, Abbe number, heat resistance, and light resistance of the cured product may decrease. When two or more polythioether compounds are used, it is preferable that the total amount of these polythioether compounds satisfy the above range.

[0099] In addition to the polythioether compound, the curable composition of the present disclosure preferably contains a component (hereinafter sometimes referred to as a “curable component”) that can react or polymerize with the polythioether compound to produce a cured product.

[0100] The curable component is preferably a compound having an ethylenically unsaturated bond group capable of reacting with the thiol group present at the terminal of the polythioether compound. Note that, when the polythioether compound itself has an ethylenically unsaturated bond group (for example, a vinyl group), the curable composition of the present disclosure does not need to contain a compound having an ethylenically unsaturated bond group as a curable component.

[0101] The compound having an ethylenically unsaturated bond group is preferably a compound having two or more ethylenically unsaturated bond groups.

[0102] Examples of the compound (B) having two or more ethylenically unsaturated bond groups include aliphatic, alicyclic, or aromatic (meth)acrylate monomers, allyl monomers, urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, and polyester (meth)acrylate oligomers.

[0103] Examples of aliphatic (meth)acrylate monomers include alkylene glycol di(meth)acrylates such as neopentyl glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate, alkylene diol di(meth)acrylates such as 1,6-hexanediol di(meth)acrylate and 1,9-nonanediol di(meth)acrylate, tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate; ethylene oxide- or propylene oxide-modified trimethylolpropane triacrylate, tetra(meth)acrylates such as pentaerythritol, tetra(meth)acrylates such as ditrimethylolpropane, penta(meth)acrylates such as dipentaerythritol and ethoxylated pentaerythritol, and hexa(meth)acrylates such as dipentaerythritol. Specific examples include 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexaacrylate.

[0104] An example of the alicyclic (meth)acrylate monomer is dicyclopentadienyl di(meth)acrylate, and specifically, dicyclopentadienyl diacrylate.

[0105] Examples of aromatic (meth)acrylate monomers include ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, and the like, and specifically, ethoxylated bisphenol A diacrylate.

[0106] Examples of the allyl type monomer include tri(meth)allyl isocyanurate, and more specifically, trimethallyl isocyanurate and triallyl isocyanurate.

[0107] Examples of urethane (meth)acrylate oligomers include polyetherurethane (meth)acrylates in which ether glycols such as ethylene glycol are chain-extended with diisocyanate and both ends are (meth)acrylated; polyesterurethane (meth)acrylates in which polyester glycol is used instead of ether glycol; and others in which caprolactone diol, polycarbonate diol, etc. are used.

[0108] Examples of epoxy (meth)acrylate oligomers include those obtained by reacting (meth)acrylic acid with an epoxy group of a bisphenol A type epoxy resin, a novolac type epoxy resin, or an epoxidized oil type.

[0109] Examples of polyester (meth)acrylate oligomers include those obtained by polycondensing a polybasic acid with a polyhydric alcohol to obtain a polyester having a hydroxyl group or a carboxyl group, and then esterifying the hydroxyl group in the polyester with (meth)acrylic acid, or esterifying the carboxyl group in the polyester with a hydroxyl group-containing (meth)acrylate. The basic structural component of the oligomer, e.g., the diol component in the case of polyurethane (meth)acrylate, is not limited to one type, and different types may be mixed.

[0110] From the viewpoint of excellent heat resistance, those having three (trifunctional) or more ethylenically unsaturated bond groups are also preferred, and poly(meth)acrylates of trihydric or higher polyhydric alcohols are preferred. Specifically, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. are preferred, and dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate are more preferred.

[0111] When the curable composition of the present disclosure contains a compound having an ethylenically unsaturated bond group, the amount used is not particularly limited, but is preferably an amount such that the amount of ethylenically unsaturated groups is 0.1 to 10 equivalents, more preferably 0.2 to 8 equivalents, and even more preferably 0.3 to 5 equivalents, relative to the thiol groups contained in the polythioether compound. The amount of thiol groups contained in the polythioether compound can be calculated from the number average molecular weight of the polythioether compound.

[0112] When the curable composition of the present disclosure contains a compound having an ethylenically unsaturated bond group as a curable component and / or when the polythioether compound itself has an ethylenically unsaturated bond group, it preferably contains a radical polymerization initiator to promote the reaction between the thiol group of the polythioether compound and the ethylenically unsaturated bond group (thiol-ene reaction).

[0113] Examples of the radical polymerization initiator include organic peroxides, azo compounds, redox initiators, photopolymerization initiators, and thermal polymerization initiators. Examples of organic peroxides include benzoyl peroxide, cumene hydroperoxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, and dicumyl peroxide.

[0114] Specific examples of azo compounds include 2,2'-azobispropane, 2,2'-dichloro-2,2'-azobispropane, 1,1'-azo(methylethyl) diacetate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobisisobutyronitrile (AIBN), methyl 2,2'-azobis-2-methylpropionate, 2,2'-dichloro-2,2'-azobisbutane, 2,2'-azobis-2-methylbutyronitrile, dimethyl 2,2'-azobisisobutyrate, 3,5-dihydroxymethylphenylazo-2-methylmalonodinitrile, 2,2'-azobis-2-methylvaleronitrile, dimethyl 4,4'-azobis-4-cyanovalerate, and 2,2'-azobis-2,4-dimethylvaleronitrile.

[0115] Examples of the redox initiator include a combination of hydrogen peroxide and an iron (II) salt, an organic peroxide and dimethylaniline, and a cerium (IV) salt and an alcohol.

[0116] Examples of the photopolymerization initiator include known photopolymerization initiators such as alkylphenone-based photopolymerization initiators, α-amino alkyl ketone-based photopolymerization initiators, and phosphine oxide-based photopolymerization initiators.

[0117] More specifically, examples of the alkylphenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one.

[0118] Examples of the α-amino alkyl ketone photopolymerization initiator include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)butan-1-one.

[0119] Examples of the phosphine oxide photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, etc. Two or more of these photopolymerization initiators may be mixed and added.

[0120] As other initiators, dialkyl disulfides such as tetraalkylthiuram disulfides, in which the S—S bond is easily decomposed by heat, can also be used.

[0121] The amount of radical polymerization initiator used is preferably 0.001 to 10 parts by weight, more preferably 0.005 to 5 parts by weight, and even more preferably 0.01 to 3 parts by weight, per 100 parts by weight of the polythioether compound (when a compound having an ethylenically unsaturated bond group is used, the total amount of the polythioether compound and the compound having an ethylenically unsaturated bond group). If the amount of radical polymerization initiator used is less than 0.001 part by weight, sufficient curability may not be obtained.

[0122] The curable composition of the present disclosure may contain, as a curable component, a component (sometimes referred to as "another curable component") that can react with the thiol group present at the terminal end of the polythioether compound. Examples of other curable components include isocyanate compounds, thioisocyanate compounds, epoxy compounds, acid anhydrides, and episulfide compounds other than the above-mentioned alicyclic episulfide compounds.

[0123] The isocyanate compound is not particularly limited, but examples thereof include diethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, 2,6-bis(isocyanatomethyl)decahydronaphthalene, lysine Reisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, o-tolidine diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 3-(2'-isocyanatocyclohexyl)propyl isocyanate, tris(phenylisocyanato)thiophosphate, isopropylidenebis(cyclohexyl isocyanate), 2,2'-bis(4-isocyanatophenyl)propane , triphenylmethane triisocyanate, bis(diisocyanatolyl)phenylmethane, 4,4',4"-triisocyanato-2,5-dimethoxyphenylamine, 3,3'-dimethoxybenzidine-4,4'-diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diisocyanatobiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, dicyclohexylmethane-4,4'-diisocyanate Anate, 1,1'-methylenebis(4-isocyanatobenzene), 1,1'-methylenebis(3-methyl-4-isocyanatobenzene), m-xylylene diisocyanate, p-xylylene diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, 1,3-bis(2-isocyanato-2-propyl)benzene, 2,6-bis(isocyanatomethyl)naphthalene, 1,Examples of the isocyanate include 5-naphthalene diisocyanate, bis(isocyanatomethyl)tetrahydrodicyclopentadiene, bis(isocyanatomethyl)dicyclopentadiene, bis(isocyanatomethyl)tetrahydrothiophene, bis(isocyanatomethyl)norbornene, bis(isocyanatomethyl)adamantane, dimer acid diisocyanate, 1,3,5-tri(1-isocyanatohexyl)isocyanuric acid, thiodiethyl diisocyanate, thiodipropyl diisocyanate, thiodihexyl diisocyanate, bis[(4-isocyanatomethyl)phenyl]sulfide, 2,5-diisocyanato-1,4-dithiane, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5-diisocyanatomethylthiophene, dithiodiethyl diisocyanate, and dithiodipropyl diisocyanate. Among the above, examples of polyisocyanates include isocyanates such as dimers, cyclized trimers, and adducts of alcohols or thiols obtained by a Buret reaction.

[0124] The thioisocyanate compound is not particularly limited, but examples thereof include compounds in which all or part of the isocyanate groups of the above isocyanate compounds have been replaced with isothiocyanate groups.

[0125] The epoxy compound is not particularly limited, but examples thereof include phenolic epoxy compounds produced by condensation of an aromatic hydroxy compound such as phenol, cresol, xylenol, naphthol, hydroquinone, catechol, resorcinol, bisphenol A, bisphenol F, bisphenol sulfone, bisphenol ether, bisphenol sulfide, halogenated bisphenol A, novolac resin, and an epihalohydrin; methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol. , nonanol, isopropyl alcohol, isobutyl alcohol, tert-butanol, neopentyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, 1,3- and 1,4-cyclohexanediol, 1,3- and 1,4-cyclohexanediol Alcohol-based epoxy compounds produced by condensation of alcohol compounds such as hexanedimethanol, bisphenol A, bisphenol A-ethylene oxide adduct, and bisphenol A-propylene oxide adduct with epihalohydrin, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, isobutyric acid, isovaleric acid, benzoic acid, benzoylacetic acid, naphthalenecarboxylic acid, adipic acid, sebacic acid, dodecylcarboxylic acid, dimer acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methyl ... Glycidyl ester epoxy compounds produced by condensation of carboxylic acid compounds such as phthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, HET acid, nadic acid, maleic acid, succinic acid, fumaric acid, trimellitic acid, benzenetetracarboxylic acid, benzophenonetetracarboxylic acid, naphthalenedicarboxylic acid, and diphenyldicarboxylic acid with epihalohydrin, methylamine, ethylamine, propylamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 1,4-Diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, bis(3-aminopropyl)ether, 1,2-bis(3-aminopropoxy)ethane, 1,3-bis(3-aminopropoxy)-2,2'-dimethylpropane, 1,2-, 1,3-, or 1,4-bisaminocyclohexane, 1,3- or 1,4-bisaminomethylcyclohexane, 1,3- or 1,4-bisaminoethylcyclohexane, 1,3- or 1,4-bisaminopropylcyclohexane primary amines such as ammonium hydroxide, hydrogenated 4,4'-diaminodiphenylmethane, isophoronediamine, 1,4-bisaminopropylpiperazine, m- or p-phenylenediamine, 2,4- or 2,6-tolylenediamine, m- or p-xylylenediamine, 1,5- or 2,6-naphthalenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,2-(4,4'-diaminodiphenyl)propane, dimethylamine, diethylamine, dibutylamine, methylethylamine, methylpropylamine, methylamine N,N'-dimethyl-1,4-diaminobutane, N,N'-dimethyl-1,5-diaminopentane, N,N'-dimethyl-1,6-diaminohexane, N,N'-dimethyl-1,7-diaminoheptane, N,N'-diethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, ...dimethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,4-diaminobutane, N,N'-dimethyl-1,5-diaminopentane, N,N'-dimethyl-1,6-diaminohexane, N,N'-dimethyl-1,7-diaminoheptane, N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2 amine, N,N'-diethyl-1,2-diaminopropane, N,N'-diethyl-1,3-diaminopropane, N,N'-diethyl-1,4-diaminobutane, N,N'-diethyl-1,5-diaminopentane, N,N'-diethyl-1,6-diaminohexane, N,N'-diethyl-1,7-diaminoheptane, piperazine, 2-methylpiperazine, 2,5- or 2,6-dimethylpiperazine, homopiperazine, 1,1-di(4-piperidyl)methane, 1,2-di(4-piperidyl)ethane, 1,3-di(4-piperidyl)propane, 1,Examples of epoxy compounds include amine-based epoxy compounds produced by condensing a secondary amine such as 4-di(4-piperidyl)butane with an epihalohydrin, alicyclic epoxy compounds (compounds in which the sulfur atoms of the above-mentioned alicyclic episulfide compounds are substituted with oxygen atoms), epoxy compounds produced by epoxidizing unsaturated compounds such as styrene oxide, dicyclopentadiene diepoxide, epoxidized soybean oil, epoxidized polybutadiene, and vinylcyclohexene epoxide, and urethane-based epoxy compounds produced from the above-mentioned polyhydric alcohols, phenol compounds, diisocyanates, glycidol, etc.

[0126] The acid anhydride may be any known or conventional acid anhydride curing agent, and is not particularly limited. Examples include acid anhydrides that are liquid at 25°C, such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride, and methylendomethylenetetrahydrophthalic anhydride; and acid anhydrides that are solid (solid-state) at 25°C, such as succinic anhydride, hydrogenated pyromellitic anhydride, hydrogenated biphenyl dianhydride, phthalic anhydride, tetrahydrophthalic anhydride (e.g., 1,2,3,6-tetrahydrophthalic anhydride), hexahydrophthalic anhydride, and methylcyclohexene dicarboxylic anhydride. Furthermore, examples of the acid anhydride curing agent that can be used include polyvalent carboxylic acid condensates described in JP 2011-219534 A.

[0127] Examples of episulfide compounds other than alicyclic episulfide compounds include 2-[4-(2,3-episolfidopropoxy)cyclohexyl]-2-[4-(2,3-epoxypropoxy)cyclohexyl]propane, bis[2-(2,3-episolfidopropoxy)cyclohexyl]methane, [2-(2,3-episolfidopropoxy)cyclohexyl][2-(2,3-epoxypropoxy)cyclohexyl]methane, [2-(2,3-episolfidopropoxy)cyclohexyl] bis[4-(2,3-episulfidopropoxy)cyclohexyl]methane, [2-(2,3-episulfidopropoxy)cyclohexyl][4-(2,3-epoxypropoxy)cyclohexyl]methane, [2-(2,3-episolfidopropoxy)cyclohexyl][4-(2,3-epoxypropoxy)cyclohexyl]methane, bis[4-(2,3-episolfidopropoxy)cyclohexyl]methane, [4- (2,3-episulfidepropoxy)cyclohexyl][4-(2,3-epoxypropoxy)cyclohexyl]methane, bis[3,5-dimethyl-4-(2,3-episulfidepropoxy)cyclohexyl]methane, [3,5-dimethyl-4-(2,3-episulfidepropoxy)cyclohexyl][3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]methane, hydrogenated bisphenol F type episulfide resin ( hydrogenated bisphenol F episulfide resins); hydrogenated biphenol episulfide resins; hydrogenated novolac episulfide resins (for example, hydrogenated phenol novolac episulfide resins, hydrogenated cresol novolac episulfide resins, and hydrogenated cresol novolac episulfide resins of bisphenol A); hydrogenated naphthalene episulfide resins; and hydrogenated epoxy resins of episulfide resins obtained from trisphenolmethane. Here, the episulfide resin is a compound in which at least one epoxy group contained in the corresponding epoxy resin has been substituted with an episulfide group.

[0128] Furthermore, examples of episulfide compounds other than alicyclic episulfide compounds include 1,2,8,9-diepisulfide limonene, 1,2-episulfide-8,9-epoxy limonene, and 8,9-episolfide-1,2-epoxy limonene.

[0129] Furthermore, examples of episulfide compounds other than alicyclic episulfide compounds include aromatic thioglycidyl ether episulfide compounds [for example, bisphenol A episulfide compounds, bisphenol F episulfide compounds, biphenol episulfide compounds, phenol novolac episulfide compounds, cresol novolac episulfide compounds, cresol novolac episulfide compounds of bisphenol A, naphthalene episulfide compounds, episulfide compounds obtained from trisphenolmethane, etc.] etc.], aliphatic thioglycidyl ether-based episulfide compounds [for example, aliphatic 2,3-episulfidepropyl ether, etc.], thioglycidyl ester-based episulfide compounds, thioglycidylamine-based episulfide compounds, isocyanurate compounds having an episulfide group [for example, diallyl mono(2,3-episulfidepropyl) isocyanurate compound, monoallyl di(2,3-episulfidepropyl) isocyanurate compound, tri(2,3-episulfidepropyl) isocyanurate compound, etc.], and the like are also included.

[0130] The other curable components may be used alone or in combination of two or more. As the other curable component, from the viewpoints of a high refractive index, a high Abbe number, a balance between the refractive index and the Abbe number, heat resistance, and light resistance of the cured product, those containing a sulfur atom are preferred, i.e., thioisocyanate compounds, episulfide compounds other than alicyclic episulfide compounds, and the like are preferred.

[0131] When the curable composition of the present disclosure contains other curable components, their content (amount blended) is not particularly limited, but is preferably 10 to 1,000 parts by weight, more preferably 30 to 500 parts by weight, per 100 parts by weight of the polythioether compound. More specifically, the other curable components are preferably used in a ratio such that 0.1 to 1.5 equivalents of functional groups are contained in the other curable components per equivalent of thiol groups in the polythioether compound contained in the curable composition of the present disclosure. When two or more types of other curable components are used, it is preferable that the total amount of these curable components satisfy the above range.

[0132] In addition to the above, the curable composition of the present disclosure may contain various additives within a range that does not impair the effects of the present disclosure. For example, using a compound having a hydroxyl group, such as ethylene glycol, diethylene glycol, propylene glycol, or glycerin, as the additive allows the reaction to proceed slowly. Other commonly used additives that do not impair viscosity or transparency include amino acids, olefins such as (meth)acrylates, inorganic substances such as sulfur, silicone-based or fluorine-based antifoaming agents, leveling agents, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane or 3-mercaptopropyltrimethoxysilane, surfactants, inorganic fillers such as alumina, flame retardants, colorants, antioxidants, UV absorbers, ion adsorbents, pigments, and mold release agents.

[0133] The curable composition of the present disclosure is not particularly limited, and can be prepared by stirring and mixing the above-mentioned components, optionally while heating them. The curable composition of the present disclosure can be used as a one-component composition in which the components are premixed and used as is, or as a multi-component (e.g., two-component) composition in which, for example, two or more components stored separately are mixed in a predetermined ratio before use. The stirring and mixing method is not particularly limited, and known or conventional stirring and mixing means can be used, such as various mixers such as dissolvers and homogenizers, kneaders, rolls, bead mills, and planetary stirring devices. After stirring and mixing, the mixture may be degassed under vacuum.

[0134] The viscosity of the curable composition of the present disclosure at 25°C is not particularly limited, but is preferably 100 to 10,000 mPa·s, more preferably 200 to 9,000 mPa·s, and even more preferably 300 to 8,000 mPa·s. If the viscosity at 25°C is less than 100 mPa·s, the heat resistance of the cured product tends to decrease. On the other hand, if the viscosity at 25°C exceeds 10,000 mPa·s, workability during casting tends to decrease, and the cured product tends to be prone to defects due to poor casting. The viscosity of the curable episulfide resin composition at 25°C can be measured, for example, using a digital viscometer (model number "DVU-EII" manufactured by Tokimec Inc.) under the following conditions: rotor: standard 1°34' x R24, temperature: 25°C, and rotation speed: 0.5 to 10 rpm.

[0135] <Cured product> By curing the curable composition of the present disclosure, a cured product having a high refractive index, a high Abbe number, and a well-balanced refractive index and Abbe number can be obtained with high productivity. When the curable composition of the present disclosure contains the above-mentioned radical polymerization initiator, the cured product exhibits an even higher refractive index and Abbe number. The heating temperature during curing (curing temperature) is not particularly limited, but is preferably 10 to 200°C, more preferably 20 to 190°C, and even more preferably 30 to 180°C. The heating time during curing (curing time) is also not particularly limited, but is preferably 30 to 600 minutes, more preferably 45 to 540 minutes, and even more preferably 60 to 480 minutes. Curing temperatures and curing times lower than the lower limits of the above ranges result in insufficient curing, while temperatures higher than the upper limits of the above ranges may cause decomposition of the resin components, which is undesirable. Curing conditions vary depending on various factors, but can be appropriately adjusted, for example, by shortening the curing time when the curing temperature is high and lengthening the curing time when the curing temperature is low.

[0136] <Optical materials> The cured product obtained by curing the curable composition of the present disclosure (hereinafter, sometimes referred to as the "cured product of the present disclosure") exhibits a high refractive index and a high Abbe number. Furthermore, the balance between the refractive index and Abbe number is excellent. Therefore, the product can be suitably used as various optical materials, such as optical lenses for eyeglasses and cameras, optical fiber cables, prisms, information recording substrates, and plastic filters. Here, "excellent balance between the refractive index and Abbe number" means that the refractive index and Abbe number are high while being adjusted to within a satisfactory range for optical materials. From the viewpoints of achieving thin optical materials and eyeglass lenses and effectively preventing rainbows due to chromatic aberration, the refractive index (n e ) of the cured product at e-line (546.1 nm) is preferably 1.50 to 1.80, more preferably 1.55 to 1.75. Furthermore, from the viewpoint of effectively preventing rainbows due to chromatic aberration, the Abbe number (v e ) at e-line (546.1 nm) is preferably 30 to 60, more preferably 40 to 55. As described above, the cured product of the present disclosure has favorable optical properties, achieving both a high refractive index and a high Abbe number, and is therefore useful as an optical film, a plastic for eyeglass lenses, a transparent sealing material, and the like. The refractive index and Abbe number of the cured product are values ​​measured using a prism coupler. Specifically, the refractive index (ne) at wavelengths of 546.1 nm, the refractive index (nF') at 488 nm, and the refractive index (nC') at 643.9 nm of the cured product are determined, and the Abbe number (νe) is calculated by substituting these values ​​into the formula Abbe number = (ne-1) / (nF'-nC'). [Example]

[0137] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0138] ( 1 H-NMR measurement) Alicyclic episulfide compounds obtained in the synthesis examples 1 The H-NMR spectrum was measured under the following conditions. Equipment: JEOL 400MHz Solvent: deuterated chloroform (containing tetramethylsilane)

[0139] (Measurement of number average molecular weight) The number average molecular weight of the polythioether compounds obtained in the examples was measured by GPC under the following conditions. (Device) Degasser Shimadzu DGU-20As Shimadzu LC-20AD Pump Shimadzu SIL-20A Autosampler Oven: Tosoh CO-8020 RI detector: RID-20A conditions Mobile phase: CHCl3 Mobile phase flow rate: 1ml / min Column: Shodex Guard Column-KF803-KF802-KF801-KF801 Column temperature: 40℃ Detector temperature: 40℃ Sample concentration: 0.2% (C%) Injection volume: 100 μL

[0140] Synthesis Example 1 4-Vinylcyclohexene-1,2-epoxide (239 g) and ammonium thiocyanate (293 g) were reacted in methanol solvent (2.9 L) at 43°C for 4 hours. The reaction mixture was extracted with dichloromethane, washed with water, and concentrated. The resulting extract was purified using a silica gel column (elution solvent: dichloromethane) to obtain 170 g of product. NMR measurement identified the product as 4-vinylcyclohexene-1,2-episulfide (the compound represented by formula (1-2) above). The alicyclic episulfide compound obtained in Synthesis Example 1 1 The H-NMR spectrum chart is shown in Figure 1.

[0141] In the following examples, 4-vinylcyclohexene-1,2-episulfide synthesized in Synthesis Example 1 was used as the alicyclic episulfide compound, and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) was used as the base.

[0142] Example 1 4-Vinylcyclohexene-1,2-episulfide (500 mg) and DBU (50 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was heated to 60°C and stirred for 5 minutes, becoming a viscous liquid. When cooled to room temperature, it gelled and solidified. The number average molecular weight (Mn) measured by GPC was 11,700.

[0143] Example 2 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (8.8 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 44 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 1710.

[0144] Example 3 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (96 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 30 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 2348.

[0145] Example 4 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (19 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 30 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 2211.

[0146] Example 5 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (96 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was heated to 50°C, and after 0.5 hours, a viscous liquid was obtained. The number average molecular weight (Mn) measured by GPC was 1762.

[0147] Example 6 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (96 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was heated to 75°C, and after 0.5 hours, a viscous liquid was obtained. The number average molecular weight (Mn) measured by GPC was 1783.

[0148] Example 6 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (96 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was heated to 100°C, and after 0.5 hours, a viscous liquid was obtained. The number average molecular weight (Mn) measured by GPC was 2069.

[0149] Example 7 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (957 mg), and DBU (20 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 336 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 741.

[0150] Example 8 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (96 mg), and DBU (20 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 120 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 12,478.

[0151] Example 9 4-Vinylcyclohexene-1,2-episulfide (1000 mg), 3-mercaptopropionic acid ethyl ester (96 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 2 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 803.

[0152] Example 10 A viscous liquid was obtained by the same procedure as in Example 9, except that the standing time was changed to 4 hours. The number average molecular weight (Mn) measured by GPC was 1,248.

[0153] Example 11 A viscous liquid was obtained by the same procedure as in Example 9, except that the standing time was changed to 6 hours. The number average molecular weight (Mn) measured by GPC was 1,220.

[0154] Example 12 A viscous liquid was obtained by the same procedure as in Example 9, except that the standing time was changed to 24 hours. The number average molecular weight (Mn) measured by GPC was 1,389.

[0155] Example 13 4-Vinylcyclohexene-1,2-episulfide (1000 mg), pentaerythritol tetrakis(3-mercaptopropionate) (87 mg), and DBU (10 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. The mixture was allowed to stand at 22°C for 2 hours, resulting in a viscous liquid. The number average molecular weight (Mn) measured by GPC was 1878.

[0156] Example 14 A viscous liquid was obtained by the same procedure as in Example 13, except that the standing time was changed to 4 hours. The number average molecular weight (Mn) measured by GPC was 2,221.

[0157] Example 15 A viscous liquid was obtained by the same procedure as in Example 13, except that the standing time was changed to 6 hours. The number average molecular weight (Mn) measured by GPC was 2,280.

[0158] Example 16 A viscous liquid was obtained by the same procedure as in Example 13, except that the standing time was changed to 24 hours. The number average molecular weight (Mn) measured by GPC was 3,736.

[0159] Comparative Example 1 4-Vinylcyclohexene-1,2-episulfide (900 mg) and San-Aid SI-100L (20 mg, manufactured by Sanshin Chemical Industry Co., Ltd., thermal acid generator) were weighed into a mixing cup and stirred with a spatula for 1 minute. When the mixture was heated to 50°C, the reaction proceeded rapidly and solidified into a rubber-like substance after 1 minute.

[0160] Comparative Example 2 4-Vinylcyclohexene-1,2-episulfide (1 g) and BF3·Et2O (172 mg) were weighed into a mixing cup and stirred with a spatula for 1 minute. When the mixture was heated to 55°C, the reaction proceeded rapidly and solidified after 1 minute.

[0161] Each feature disclosed herein may be combined with any other feature disclosed herein. The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the gist of the present disclosure. The present disclosure is not limited by the embodiments, but is limited only by the scope of the claims.

[0162] Variations of the present disclosure described above are noted below. [1] A method for producing a polythioether compound, comprising ring-opening polymerization of an alicyclic episulfide compound in the presence of a base. [2] The method for producing a polythioether compound according to [1], wherein the ring-opening polymerization is carried out in the absence of a solvent. [3] The method for producing a polythioether compound according to [1] or [2], wherein the ring-opening polymerization is carried out at a reaction temperature of 30°C or higher (for example, 40°C or higher). [4] The method for producing a polythioether compound according to any one of [1] to [3], wherein the base is an amine compound. [5] The method for producing a polythioether compound according to any one of [1] to [4], wherein the base is a strong base. [6] The method for producing a polythioether compound according to any one of [1] to [5], wherein the base is at least one amidine selected from the group consisting of 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, and 6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene-7, or at least one guanidine selected from the group consisting of 1,5,7-triazabicyclo[4.4.0]decene-5 and 7-methyl-1,5,7-triazabicyclo[4.4.0]decene-5 (preferably 1,8-diazabicyclo[5.4.0]undecene-7). [7] The method for producing a polythioether compound according to any one of [1] to [6], wherein the amount of the base used is 0.01 to 20 parts by weight (e.g., 0.01 to 15 parts by weight, 0.05 to 12 parts by weight, or 0.1 to 10 parts by weight) relative to the alicyclic episulfide compound (100 parts by weight). [8] The method for producing a polythioether compound according to any one of [1] to [7], wherein the amount of the base used is 0.0001 to 0.2 equivalents (e.g., 0.0005 to 0.1 equivalents, 0.001 to 0.12 equivalents, or 0.005 to 0.1 equivalents) per equivalent of an alicyclic episulfide group contained in the alicyclic episulfide compound. [9] The method for producing a polythioether compound according to any one of [1] to [8], wherein the ring-opening polymerization further proceeds in the presence of a thiol compound.

[10] The method for producing a polythioether compound according to [9], wherein the thiol compound is at least one selected from the group consisting of thiophenols, thiols, mercaptoalcohols, hydroxythiophenols, mercaptoorganic acids, and mercaptoamines (preferably, thiols).

[11] The method for producing a polythioether compound according to [9] or

[10] , wherein the thiol compound is a compound having two or more (e.g., three or more, or four or more) thiol groups in the molecule.

[12] The method for producing a polythioether compound according to any one of [9] to

[11] , wherein the amount of the thiol compound used is 0.1 to 200 parts by weight (e.g., 0.5 to 150 parts by weight, or 0.6 to 120 parts by weight) relative to 100 parts by weight of the alicyclic episulfide compound.

[13] The method for producing a polythioether compound according to any one of [9] to

[12] , wherein the amount of the thiol compound used is such that the amount of thiol groups is 0.005 to 1.5 equivalents (e.g., 0.005 to 1.2 equivalents) per equivalent of alicyclic episulfide groups contained in the alicyclic episulfide compound.

[14] The method for producing a polythioether compound according to any one of [9] to

[13] , wherein the base is used in an amount of 0.001 equivalents or more (e.g., 0.005 equivalents or more, 0.01 equivalents or more, 0.05 equivalents or more, or 0.1 equivalents or more) per equivalent of a thiol group contained in the thiol compound.

[15] The method for producing a polythioether compound according to any one of [9] to

[14] , wherein the base is used in an amount of less than 1 equivalent (e.g., 0.5 equivalents or less, 0.25 equivalents or less, or 0.2 equivalents or less) per equivalent of a thiol group contained in the thiol compound.

[16] The method for producing a polythioether compound according to any one of [1] to

[15] , wherein the alicyclic episulfide compound contains a compound represented by the following formula (I): [ka] [In the above formula (I), X represents a monovalent organic group. Ring A represents an alicyclic ring having 3 to 10 carbon atoms. r represents a natural number. However, the upper limit of r is the number of hydrogen atoms that can be present when ring A does not have X. When r is 2 or more, the two or more Xs may be the same or different.]

[0163]

[17] A curable composition comprising a polythioether compound produced by the method according to any one of [1] to

[16] .

[18] The curable composition according to

[17] , wherein the polythioether compound has a structure represented by the following formula (II): [ka] [In formula (II), X represents a monovalent organic group. Ring A represents an alicyclic ring having 3 to 10 carbon atoms. r represents a natural number. However, the upper limit of r is the number of hydrogen atoms that can be present when ring A does not have X. When r is 2 or more, two or more Xs may be the same or different. q represents a natural number of 1 or more. When q is 2 or more, X and r in the group in [ ] may be the same or different.]

[19] The curable composition according to

[17] or

[18] , wherein the content (blending amount) of the polythioether compound in the curable composition (100 wt%) is 3 wt% or more but less than 100 wt% (e.g., 4 to 90 wt%, or 5 to 80 wt%).

[20] The curable composition according to any one of

[17] to

[19] , further comprising a compound having an ethylenically unsaturated bond group.

[21] The curable composition according to any one of

[17] to

[20] , further comprising the radical polymerization initiator (e.g., organic peroxide, azo compound and redox initiator, photopolymerization initiator, thermal polymerization initiator, etc.).

[22] The curable composition according to any one of

[17] to

[21] , which is a resin composition for an optical lens.

[23] The curable composition according to any one of

[17] to

[21] , which is a resin composition for eyeglass lenses.

[24] A cured product of the curable composition according to any one of

[17] to

[23] .

[25] An optical lens molded from a cured product of the curable composition according to

[22] .

[26] A spectacle lens formed from a cured product of the curable composition according to

[23] . [Industrial Applicability]

[0164] According to the method of the present disclosure, the ring-opening polymerization reaction of an alicyclic episulfide compound can be easily controlled, and a polythioether compound can be efficiently and economically obtained. The obtained polythioether compound is useful as a component of a curable composition for obtaining a cured product having excellent optical properties, such as high refractive index and high Abbe number, with a good balance between the two.

Claims

1. A method for producing a polythioether compound having a number average molecular weight of 500 to 50,000, comprising ring-opening polymerization of an alicyclic episulfide compound in the presence of a base whose conjugate acid has an acid dissociation constant (pKa) of 12 or more, in the absence of a solvent.

2. A method for producing a polythioether compound having a number average molecular weight of 500 to 50,000, comprising ring-opening polymerization of an alicyclic episulfide compound in the presence of a base whose conjugate acid has an acid dissociation constant (pKa) of 12 or more, and carrying out the ring-opening polymerization at a reaction temperature of 30°C or more.

3. A method for producing a polythioether compound having a number average molecular weight of 500 to 50,000, comprising ring-opening polymerization of an alicyclic episulfide compound in the presence of a base whose conjugate acid has an acid dissociation constant (pKa) of 12 or more, wherein the alicyclic episulfide compound contains a compound represented by the following formula (I): 【Chemistry 1】 [In the above formula (I), X represents a monovalent organic group. Ring A represents an alicyclic ring having 3 to 10 carbon atoms. r represents a natural number. However, the upper limit of r is the number of hydrogen atoms that can be present when ring A does not have X.] When r is 2 or more, the two or more Xs may be the same or different.

4. A method for producing a polythioether compound having a number average molecular weight of 500 to 50,000, comprising ring-opening polymerization of an alicyclic episulfide compound in the presence of a base whose conjugate acid has an acid dissociation constant (pKa) of 12 or more, the ring-opening polymerization further proceeding in the presence of a thiol compound, and using the base in a proportion of 0.001 equivalent or more and less than 1 equivalent per equivalent of a thiol group contained in the thiol compound.

5. The method for producing a polythioether compound according to any one of claims 1 to 4, wherein the base is an amine compound.

6. The method for producing a polythioether compound according to any one of claims 1 to 3 and 5, wherein the ring-opening polymerization further proceeds in the presence of a thiol compound.

7. The method for producing a polythioether compound according to claim 4 or 6, wherein the thiol compound is a compound having two or more thiol groups in the molecule.

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