WO2008062903A1

WO2008062903A1 - Radically polymerizable compound having a dithiocarbonate structure and a sulfur-containing allylcarbonate

Info

Publication number: WO2008062903A1
Application number: PCT/JP2007/072999
Authority: WO
Inventors: Yasuyuki Oyama; Nobuyuki Kibino; Kazufumi Kai; Tsuneo Tajima
Original assignee: Showa Denko K.K.
Priority date: 2006-11-22
Filing date: 2007-11-21
Publication date: 2008-05-29
Also published as: JP4955518B2; KR20090061067A; TW200848396A; KR101060626B1; EP2094654A1; JP2008285644A

Abstract

The invention provides a radically polymerizable compound having a dithiocarbonate structure represented by formula (1) and a sulfur-containing allylcarbonate group which can give an optical material stable and little colored at the time of thermal curing reaction, having a high refractive index and an excellent transparency, production method thereof, (co) polymer of the compound, composition containing the compound and cured product thereof, andmolded product for optical material comprising the cured product. (In the formula, R1 and R2 each independently represents a hydrogen atom or methyl group, and X and Y each independently represents a divalent group selected from group consisting of an alkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group.)

Description

DESCRIPTION

RADICALLY POLYMERIZABLE COMPOUND HAVING A DITHIOCARBONATE STRUCTURE AND A SULFUR-CONTAINING ALLYLCARBONATE

TECHNICAL FIELD

The invention relates to a radically polymeri zable compound having a specific dithiocarbonate structure and a sulfur-containing allylcarbonate group, and optical material with a high refractive index using the compound.

BACKGROUND ART

Organic glass is light as compared with inorganic glass and for its good impact resistance and easiness in thermoplastic formation and coloring, organic glass has been used instead of inorganic glass as window material in buildings and vehicles or as materials in lighting equipments, trade signs, household goods and the like. Typical examples of such an organic glass include diethyleneglycol bis (allylcarbonate) polymer such as CR-39 (Product name, manufactured by PPG Industries) and methyl methacrylate polymer .

In a case where lens of eyeglasses is manufactured from glass, the higher the refractive index of the glass, the thinner-walled the lens can be . Refractive index of organic glass is in a range of 1.49 to 1.50, which is low as compared with that of inorganic glass (1.523 in case of white crown glass) . Therefore, in a case where lens is manufactured by using organic glass, edge thickness of the lens is large as compared with a case using inorganic glass, whereby advantage of lighter weight is offset. Moreover, in a case where vision-corrective lens is manufactured from organic glass, the higher the corrective power of the lens, the worse the appearance. Under these circumstances, there have been demands for resin for optical material which cangivea polymer having a high refractive index.

In order to increase refractive index of organic glass, various attempts have been made so far. For example, Japanese Patent Application Laid-Open No . S63-46213 describes as resin for an optical material having a high refractive index, thiourethane-based resin obtained by reaction between an isocyanate compound and a mercapto compound. However, toxicity of raw material isocyanate compound and extremely unpleasant odor inherent to raw material thiol compound are of concern.

In addition, Japanese Patent Application Laid-Open No .H03-217412 describes as resin for an optical material having a high refractive index, a sulfur-atom-containing (meth) acrylate compound. However, many of such a material tend to yield high viscosity and have high reactivity. Therefore, use of such a material requires a lot of know-how in storage and is not always easy.

Furthermore, Japanese Patent Application Laid-Open No . H02-261808, H10-175947 and Hll-49744 describe as resin for optical material having high refractive indices, radically polymerizable compounds having sulfur-containing allylcarbonate groups. Although these compounds having high refractive indices and having good photocurability, oxidation readily occurs in sulfide structure of molecules when a peroxide is used as a polymerization initiator in heat curing reaction, sometimes causing problems such as coloring. Also, polymerization control is difficult.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a radically polymerizable compound which can be stably subjected to heat curing reaction with little coloring, and an optical material having a high refractive index and excellent transparency using the compound.

As a result of intensive studies made with a view to solving the above problems, the present inventors have found out that a radically polymerizable compound having a specific dithiocarbonate structure and a sulfur-containing allylcarbonate group, stable and almost free of being colored at the time of thermal curing reaction, can give an optical material having a high refractive index and excellent transparency, and thus they have completed the invention. That is, the present invention relates to the following items 1 to 16.

1. A radically polymerizable compound represented by formula ( 1 ) .

(In the formula, R¹ and R² each independently represents a hydrogen atom or methyl group, and X and Y each independently represents a divalent group selected from group consisting of an alkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group.)

2. The radically polymerizable compound according to 1, whereinX and Y in formula (1) are amethylene group, anethylene group, 1 , 2-propylene group, or a 1 , 3-propylene group.

3. The radically polymerizable compound according to 1 or 2, wherein R¹ and R² in formula (1) are hydrogen atoms.

4. A method of producing the radically polymerizable compound represented by formula (1), comprising allowing a thiol compound represented by formula (2) with a dithiol compound represented by formula (3) in the presence of a base to thereby obtain a thiol compound represented by formula (4) and further allowing the thiol compound with N, N' -carbonyl diimidazole .

(In the formula^¹ and R² each independently represents a hydrogen atom or methyl group, and X and Y each independently represents a divalent group selected from group consisting of an alkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group.)

(In the formula, L represents a divalent group selected from a group consisting of an alkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group.)

(In the formula, R⁴ represents a hydrogen atom or a methyl group and Z represents a chlorine atom or a bromine atom. )

(Symbols in the formula have the same meanings as defined above . )

5. The method of producing the radically polymerizable compound according to 4, wherein X and Y in formula (1) are a methylene group, an ethylene group, 1 , 2-propylene group, or a 1 , 3-propylene group.

6. The method of producing the radically polymerizable compound according to 4 or 5, wherein R¹ and R² in formula (1) are hydrogen atoms. 7. A polymer or copolymer comprising the radically polymerizable compound according to any one of 1 to 3 as one of its raw material monomers.

8. The copolymer according to 7, which is a copolymer of the radically polymerizable compound according to any one of 1 to 3 and other radically polymerizable compounds.

9. The copolymer according to 8, which is a copolymer of the radically polymerizable compound according to any one of 1 to 3 and allyl methacrylate and/or diallyl maleate.

10. A polymerizable composition for an optical material, comprising the radically polymerizable compound according to any one of 1 to 3 .

11. The polymerizable composition for an optical material according to 10, further comprising other radically polymerizable compounds. 12. The polymerizable composition for an optical material according to 11, wherein the other radically polymerizable compounds include at least allyl methacrylate and/or diallyl maleate .

13. A cured product of the polymerizable composition for an optical material according to any one of 10 to 12.

14. A molded body for an optical material comprising the cured product according to 13.

15. A molded body for an optical material according to 14, selected from a group consisting of lens, optical waveguide, film, prism, plate and fiber.

16. Alensobtainedbycuringthe polymerizable composition for an optical material according to any one of 10 to 12.

The composition for optical material using the radically polymerizable compound according to the present invention has a high refractive index and excellent transparency when cured and involves little coloring at the time of thermal curing reaction. Therefore, the composition is especially useful for optical materials such as optical lens including eyeglass lens and camera lens, optical waveguide, optical sealant, optical film, prism, light guide plate for liquid crystal panel and optical fiber.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is the ¹H-NMR spectrum of S, S' -bis [2- ( allyloxycarbonylthio) ethyl ] dithiocarbonate obtained in Example 1.

Fig. 2 is the ¹³C-NMR spectrum of S, S' -bis [2- (allyloxycarbonylthio) ethyl] dithiocarbonate obtained in Example 1.

Fig. 3 is the IR spectrum of S,S'-bis[2-

( allyloxycarbonylthio) ethyl ] dithiocarbonate obtained in Example 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention is described in more detail.

[Radically polymerizable compound having a dithiocarbonate structure and a sulfur-containing allylcarbonate group] The radically polymerizable compound having a dithiocarbonate structure and a sulfur-containing allylcarbonate group of the present invention is a compound represented by formula (1) .

Hereinafter, the compound is sometimes referred to as "the radically polymerizable compound of the invention".

In the present invention, when a formula does not conform to the described compound name, the formula supersedes.

In formula (1) , R¹ and R² each independently represents a hydrogen atom or methyl group. Of the two, in terms of enhancing refractive index, hydrogen atom is the more preferred. In formula (1), X and Y each independently represents a divalent group selected from a group consisting of an alkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group. Examples of alkylene group include methylene group, ethylene group, 1, 2-propylene group, 1 , 3-propylene group, butylene group, amylene group and hexylene group.

Examples of arylene group include 1, 2-phenylene group, 1 , 3-phenylene group, 1, 4-phenylene group, toluylene group, naphthalenylene group and biphenylene group. Examples of cycloalkylene group include 1, 3-cyclopentylene group, 1 , 2-cyclopentylene group, 1 , 1-cyclopentylene group, 1 , 4-cyclohexylene group, 1 , 3-cyclohexylene group, 1 , 2-cyclohexylene group and 1 , 1-cyclohexylene group.

Among them, more preferred as X and Y are alkylene group having 1 to 4 carbon atoms and cycloalkylene group having 1 to 6 carbon atoms . In consideration for goodbalance between the refractive index and the abbe number, methylene group, ethylene group, 1 , 2-propylene group and 1 , 3-propylene group are most preferred.

As radically polymerizable compound represented by formula (1), S , S' -bis [2- (allyloxycarbonylthio ) ethyl] dithiocarbonate is most preferred. The radically polymerizable compounds for optical materials described in paragraphs about background art contain a sulfide skeleton (-CH2-S-CH2-) containing a sulfur atom for enhancing refractive index. However, in such a structure, the sulfur atom is readily oxidized, causing coloring at the time of polymerization or curing reaction and there are disadvantages in stability at the time of curing such as a problem that due to deactivation of polymerization initiator, curing becomes incomplete. On the other hand, the radically polymerizable compound of the present invention contains as sulfur-containing groups, a dithiocarbonate structure (-S-(C=O)-S-) and sulfur-containing allylcarbonate structure (CH₂=CR³-CH₂-O- (C=O) -S- (R³ means R¹ or R² above)). This structure, in which a carbonyl group having electron-withdrawing property placed next to a sulfur atom prevents the sulfur atom from being oxidized to thereby avoid coloring during polymerization or curing reaction, is stable. [Production method] Next, production method of the radically polymerizable compound having a dithiocarbonate structure and a sulfur-containing allylcarbonate group represented by formula (1) according to the present invention is described.

The radically polymerizable compound having a dithiocarbonate structure and a sulfur-containing allylcarbonate group represented by formula (1) can be produced by (i) allowing dithiol to react with halogenated (meth) allyl formate in the presence of a base, and then (ii) react with N, N' -carbonyl diimidazole. In the present Specification, the term " (meth) allyl" means "methallyl and/or allyl" and the term " (meth) acrylate" means "methacrylate and/or acrylate".

(i) Reaction between dithiol and halogenated (meth) allyl formate in the presence of a base The dithiol used in the present invention is a compound represented by formula (2).

HS' ^{^}SH (2)

The halogenated (meth) allyl formate used in the present invention is a compound represented by formula (3).

°

Both of these compounds are allowed to react with each other in the presence of a base to thereby obtain a thiol compound represented by formula (4) (hereinbelow, the compound is sometimes referred to as thiol compound (4)) .

(Symbols in the formula have the same meanings as defined above . ) In formula (3), it is preferable in terms of good balance between reactivity and economic efficiency that Z be a chlorine atom. In formula (4), L is selected according to X and Y in the compound represented by formula (1) .

There is no particular limitation on the amounts of dithiol of formula (2) and halogenated (meth) allyl formate of formula (3) used here. Generally, it is preferable that the amount of the halogenated (meth) allyl formate be within a range of 0.1 to 1.5 mol based on 1 mol of the dithiol, particularly preferably from 0.5 to 1.1 mol. If the amount of the halogenated (meth) allyl formate is less than 0.1 mol, the yield of reaction with dithiol decreases while if it exceeds 1.5 mol, the amount of by-products increases.

This reaction can be carried out by using either a method where the reaction is allowed to proceed while removing from the reaction system hydrogen halides generated as by-product in the absence of catalyst or a method where the reaction is conducted with addition of a hydrogen halide scavenger".

Examples of hydrogen halide scavenger include organic bases such as pyridine, triethylamine, picoline, dimethyl aniline, diethyl aniline, 1 , 4-diazabicyclo [2.2.2 ] octane and 1 , 8-diazabicyclo [ 5.4.0] undeca-7-ene, and inorganic bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate and sodium hydrogen carbonate . There is no particular limitation on the used amount of the hydrogen halide scavenger. A preferred range of the amount is from 0.1 to 1.5 mol, particularly preferred is 0.5 to 1.1 mol, based on 1 mol of the dithiol. Moreover, the reaction may be conducted without a solvent or with a solvent not reactive with the substrate. Also, the reaction can proceed in the copresence of water without any problems. Examples of the solvent include hydrocarbon-based solvents such as n-hexane, toluene, xylene and benzene, ketone-based solvents such as acetone, methylethyl ketone and methyl isobutyl ketone, ester-based solvents such as ethyl acetate andbutyl acetate, ether-based solvents such as diethyl ether, diethylene glycol dimethyl ether and tetrahydrofuran, tetrahydropyran, halogen-based solvents such as dichloromethane, dichloroethane, chloroform and chlorobenzene, and polar solvents such as acetonitrile, N, N-dimethylformamide and dimethyl sulfoxide . One of these solvent may be used singly or two or more of them may be used in combination.

There is no particular limitation on the reaction temperature. Generally, a preferred range of the temperature is from -30 to 100 °C, particularly preferred is from 0 to 50 °C. If the temperature is less than -30 ⁰C, the reaction rate is extremely slow. If the temperature exceeds 100 °C, side-reaction such as polymerization of thiol compound as intermediate body through ene-thiol reaction tends to occur.

Also, in the reaction, a polymerization inhibitor may be added in order to suppress polymerization.

Examples of polymerization inhibitor include quinones such as p-benzoquinone, naphthoquinone and 2 , 5-diphenyl-p-benzoquinone, polyvalent phenols such as hydroquinone, p-t-butylcatechol and 2 , 5-di-t-butylhydroquinone, and phenols such as hydroquinone monomethyl ether, di-t-butyl paracresol and α-naphthol.

The thus obtained thiol compound (4) can be refined through distillation, separation, recrystallization, chromatography or treatments using activated carbon, activated earth or synthetic adsorbent.

(ii) Reaction between the thiol compound (4) produced in above (i) and N, N' -carbonyl diimidazole Next, a method of producing the radically polymerizable compound represented by formula (1) according to the present invention by allowing thiol compound (4) generated in (i) to react with N, N' -carbonyl diimidazole is described in detail . There is no limitation on the used amounts of thiol compound (4) and N, N' -carbonyl diimidazole. Generally, it ispreferablethat 0.1 to 0.7 mol of N, N' -carbonyl diimidazole be used based on 1 mol of the thiol compound, particularly preferred is 0.3 to 0.5 mol of N, N' -carbonyl diimidazole. If the amount of N, N' -carbonyl diimidazole is less than 0.1 mol, yield of reaction with thiol compound (4) decreases. If the amount exceeds 0.7 mol, the amount of side-products increases .

This reaction may be carried out either in the presence or absence of a base.

In a case where this reaction is conducted in the presence of a base, examples of base used here include organic bases such as methylamine, dimethylamine, triethylamine, pyridine, picoline, aniline, dimethylaniline, diethylaniline, toluidine, anisidine,

1, 4-diazabicyclo [2.2.2] octane (DABCO) and 1, 8-diazabicyclo [5.4.0] undeca-7-ene (DBU) , and inorganic bases such as sodium hydrogencarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium oxide .

There is no limitation on the used amounts of the base.

Generally, it is preferable that 0.1 to 5 mol of the base beusedbasedon 1 mol of the thiol compound ( 4 ) , more preferred is 0.5 to 3 mol of the base, particularly preferred is 0.8 to 1.2 mol of the base.

This reaction may be carried out either without any solvent or in an inert solvent. There is no particular limitation on the solvent as long as it is inactive in the reaction. Examples of the solvent include hydrocarbon-based solvents such as n-hexane, benzene, toluene and xylene, alcohol-based solvents such as methanol, ethanol, isopropanol, n-butanol, methoxy ethanol, ethoxyethanol, butoxy ethanol, diethyleneglycol monomethylether, diethyleneglycol monoethylether and diethyleneglycol monobutylether, ketone-based solvents such as acetone, methylethyl ketone and methyl isobutylketone, ester-based solvents such as ethyl acetate andbutyl acetate, ether-based solvents such as diethylether, diethyleneglycol dimethylether, tetrahydrofuran and dioxane, halogen-based solvents such as dichloromethane, chloroform, carbon tetrachloride, 1, 2-dichloroethane, tetrachloroethylene, chlorobenzene, o-dichlorobenzene, and polar solvents such as acetonitrile, N, N-dimethylformamide, N,N-dimethyl acetoamide, N, N-dimethylimidazolidinone, dimethyl sulfoxide and sulforan.

One of these solvent may be used singly or two or more of them may be used in combination.

There is no particular limitation on the reaction temperature. Generally, a preferred range of the temperature is from -78 to 150 ⁰C, more preferred is from

-20 to 120 °C, particularly preferred is from 0 to 100 °C.

The above-described reaction between thiol compound (4) and N, N' -carbonyl diimidazole may be conducted by a phased method where thiol compound (4) as an intermediate compound generated in reaction between dithiol of the initial stage and halogenated (meth) allyl formate is taken out to then be used in the carbonylation reaction of the second stage or a method where without taking out such an intermediate of thiol compound (4), carbonylation reaction is conducted in the same stage.

In a case where a phased method is employed, thiol compound (4) as an intermediate compound of the first stage reaction may be isolated as a high-purity compound by further conducting known separation or purification method (such as distillation, recrystallization, chromatography and treatment with activated carbon), if necessary.

In producing the radically polymerizable compound of the present invention, a polymerization inhibitor may be used for the purpose of preventing polymerization of the intermediate thiol compound (4) through ene-thiol reaction. Examples of polymerization inhibitor usable herein include various known compounds such as 4-methoxyphenol, 2, 6-di-tert-butylcresol, hydroquinone and phenothiazine . There is no limitation on the used amounts of the polymerization inhibitor . Generally, it is preferable that 0.001 to 5 parts by mass be used based on 100 parts by mass of the raw material mixture in the reaction system or the reaction product, more preferred is 0.05 to 3 parts by mass, particularly preferred is 0.01 to 1 parts by mass.

After completion of the reaction, the reaction product, the radically polymerizable compound of formula (1) according to the present invention is separated in post-treatment of a known operation or treatment method (such as neutralization, solvent extraction, washing with water, separation and distilling off solvent).

[Polymer of the radically polymerizable compound of formula (I)]

The radically polymerizable compound represented by formula (1) according to the present invention is easily radically polymerizedby heat, ultraviolet ray, electronbeam or the like. Further, copolymers can be produced in combination with other radically polymerizable compounds. The radically polymerizable compound of formula (1) is bifunctional in a sense that it has two polymerizable double bonds and therefore, it forms a cross-linking structure even through homopolymerization (curing reaction) . For the purpose of improving properties of homopolymer such as balance between the abbe number and the refractive index, it can be copolymerized with other radically polymerizable compounds . In a case where such a radically polymerizable compound to be copolymerized with has polyfunctional radically polymerizability, a cured product having an enhanced crosslinking density can be prepared.

Also, for the purpose of decreasing viscosity of the polymer and improving moldability, a monofunctional radically polymerizable monomer may be used. There is no limitation on the radically polymerizable compound to be copolymeri zedwith the radicallypolymerizable compound as long as it can copolymerize with the radically polymerizable compound of formula (1). Examples thereof include allyl esters such as di (meth) allyl phthalate, di (meth) allyl isophthalate, di (meth) allyl terephthalate, (meth) allyl benzoate, (meth) allyl α-naphthoate, (meth) allyl β-naphthoate, (meth) allyl 2-phenylbenzoate, (meth) allyl 3-phenylbenzoate, (meth) allyl 4-phenylbenzoate, (meth) allyl o-chlorobenzoate, (meth) allyl m-chlorobenzoate, (meth) allyl p-chlorobenzoate, (meth) allyl o-bromobenzoate, (meth) allyl m-bromobenzoate, (meth) allyl p-bromobenzoate, (meth) allyl 2, 6-dichlorobenzoate, (meth) allyl 2 , 4-dichlorobenzoate, (meth) allyl 2 , 4 , 6-tribromobenzoate, di (meth) allyl 1, 4-cyclohexane dicarboxylate, di (meth) allyl 1 , 3-cyclohexane dicarboxylate, di (meth) allyl 1 , 2-cyclohexane dicarboxylate, di (meth) allyl 1-cyclohexene-l , 2-dicarboxylate, di (meth) allyl 3-methyl-l, 2-cyclohexanedicarboxylate, di (meth) allyl 4-methyl-l, 2-cyclohexanedicarboxylate, di (meth) allyl endate, di (meth) allyl chlorendate, di (meth) allyl 3 , 6-methylene-l , 2-cyclohexane dicarboxylate, tri (meth) allyl trimellitate, tetra (meth) allyl pyromellitate, di (meth) allyl diphenate, di (meth) allyl succinate and di (meth) allyl adipate; diesters of maleic acid/fumaric acid such as dibenzyl maleate, dibenzyl fumarate, diphenyl maleate, diphenyl fumarate, dibutyl maleate, dibutyl fumarate, dimehtoxyethyl maleate and dimethoxyethyl fumarate; esters of (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl

(meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenyl (meth) acrylate, stearyl

(meth) acrylate, lauryl (meth) acrylate, benzyl

(meth) acrylate, isobornyl (meth) acrylate, trimethylol propane tri (meth) acrylate, ethyleneglycol di (meth) acrylate,

1 , 4-butanediol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, 1 , 9-nonanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylol propane tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl

(meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethoxylated cyclohexane dimethanol dimethacrylate and adamantyl (meth) acrylate; aromatic vinyl compounds such as styrene, α-methylstyrene, methoxystyrene and divinylbenzene; vinyl esters of aliphatic carboxylic acids such as vinyl acetate, vinyl propionate, vinyl lactate, vinyl pivalate, vinyl stearate and vinyl caproate; alicyclic vinyl esters such as vinyl ester of cyclohexanecarboxylic acid; aromatic vinyl esters such as vinyl ester of benzoic acid and vinyl ester of t-butylbenzoic acid; allylcarbonate compounds such as diallylcarbonate, diethyleneglycol bisallyl carbonate and polyethyleneglycol bis(allyl) carbonate such as the compound having a product name CR-39, manufactured by PPG Industries; oligomers comprising a (meth) allylester group at a terminal and an ester structure in its inside derived from polyvalent carboxylic acid and polyvalent alcohol; compounds such as (meth) allyl (meth) acryate, vinyl

(meth) acrylate and di (meth) allyl maleate, having polymerizable double bonds having different reactivities in molecules and nitrogen-containing polyfunctional allyl compounds such as triallyl isocyanurate and triallyl cyanurate .

The above radically polymerizable compounds are only examples and the compounds usable here are by no means limited thereto. Moreover, in order to obtain target properties, two or more kinds of such a radically polymerizable compound may be used in combination.

Preferred among these radically polymerizable compounds from the viewpoint of balancing the refractive index and the abbe number are di (meth) allyl 1, 4-cyclohexane dicarboxylate, trimethylolpropane tri (meth) acrylate, di (meth) allyl isophthalate, di (meth) allyl terephthalate, tri (meth) allyl trimellitate, tetra (meth) allyl pyromellitate and oligomers comprising a (meth) allylester group at a terminal and an ester structure in its inside derived from polyvalent carboxylic acid and polyvalent alcohol .

Also preferred are compounds such as (meth) allyl (meth) acryate, vinyl (meth) acrylate and di (meth) allyl maleate, having radically polymerizable double bonds having different reactivities in the molecule. Thanks to difference in reactivity, these compounds are useful from the viewpoint of controlling the curing degree in curing and molding processes through radical polymerization.

In polymerizing the radically polymerizable compound of the present invention, the compound may be thermally polymerized without using an initiator. However, it is preferable that a radical polymerization initiator be used. Any radical polymerization initiator may be used as long as it can generate radicals by heat, ultraviolet ray, electron beam, radioactive ray or the like. A heat radical polymerization initiator and other initiators for radial polymerization or the like may be used in combination. Examples of heat radical polymerization initiator include azo compounds such as 2, 2' -azobisisobutyronitrile, 2 , 2 ' -azobisisovaleronitrile and dimethyl-2, 2' -azobisisobutyrate; ketone peroxides such as methylethyl ketone peroxide, methyl isobutyl ketone peroxide and cyclohexanone peroxide; diacyl peroxides such as benzoyl peroxide, decanoyl peroxide and lauroyl peroxide; dialkyl peroxides such as dicumyl peroxide, t-butylcumyl peroxide and di-t-butylperoxide; peroxy ketals such as

1, 1-di (t-hexylperoxy) -3, 3, 5-trimethyl cyclohexane, 1, 1-bis (t-hexylperoxy) cyclohexane, 1, 1-di-t-butylperoxycyclohexane and 2, 2-di (t-butylperoxy) butane; alkylperoxy esters such as t-butylperoxy pivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy isobutyrate, di-t-butylperoxy hexahydroterephthalate, di-t-butylperoxy azelate, t-butylperoxy-3 , 5, 5-trimethylhexanoate, t-hexylperoxy-2-ethylhexanoate,

1,1,3, 3-tetramethylbutylperoxy-2-ethylhexanoate, t-butylperoxy acetate, t-butylperoxybenzoate, di-t-butylperoxy trimethyl adipate, t-hexylperoxy isopropyl monocarbonate, t-butylperoxy laurate and t-hexylperoxybenzoate : and peroxycarbonates such as diisopropylperoxy dicarbonate, di-sec-butylperoxy dicarbonate and t-butylperoxy isopropyl carbonate. The initiator is not limited thereto. Also, two or more kinds of these heat radical polymerization initiators may be used in combination.

Examples of initiators for radical polymerization by UV-ray, electron beam or radioactive-ray include acetophenone derivatives such as acetophenone, 2, 2-dimethoxy-2-phenyl acetophenone, diethoxyacetophenone, l-hydroxy-cyclohexyl-phenylketone, and

2-methyl-1- [ 4- (methylthio) phenyl ] -2-morpholinopropanone- 1, 2-benzyl-2-dimethylamino-1- ( 4-morpholinophenyl ) -butano ne-1, 2-hydroxy-2-methyl-1-phenyl-propane-1-one; benzophenone derivatives such as benzophenone, 4, 4' -bis (dimethylamino) benzophenone, 4-trimethylsilyl benzophenone and 4-benzoyl-4' -methyl-diphenylsulfide, benzoin derivatives such as benzoin, benzoin ethylether, benzoin propylether, benzoin isobutylether and benzoin isopropylether, methylphenyl glyoxylate, benzoin dimethylketal and 2 , 4 , 6-trimethylbenzoyl diphenylphosphine oxide. The invention is not limited by these examples. Also, two or more kinds of these UV-ray, electron beam or radioactive-ray radical polymerization initiators may beusedin combination . The addition amount of the polymerization initiator differs according to curing temperature, composition ratios of radical polymerizable composition and kinds and amounts of additives and cannot be flatly defined. Apreferred amount is within a range of 0.01 to 15 parts by mass, particularly preferably 0.1- to 10 parts by mass, based on 100 parts by mass of the total amount of radically polymerizable compound of formula (1) of the present invention and other radically polymerizable compounds added for copolymerization when necessary. If the amount of the radical polymerization initiator is less than 0.01 parts by mass, polymerization and curing tend to be insufficient . Also, addition exceeding 15 parts by mass is economically disadvantageous.

Appropriate polymerization temperature (curing temperature) may be selected according to the type of the polymerization initiator. In case of UV-ray polymerization or the like, room temperature can be selected. In case of heat polymerization, it is preferable that the temperature be selected according to decomposition temperature of the initiator and it is generally within a range of 30 to 130 ⁰C. Also, the temperature may be gradually changed during the polymerization (curing) . In polymerization, inert solvent may be used.

The resin obtained by polymerizing the radically polymerizable compound of formula (1) of the present invention has high transparency and is useful as a resin for optical material having a high refractive index. [Composition for optical material] The composition for optical material and its cured product according to the present invention comprises the above-described radically polymerizable compound of formula

(1) . Cured product is prepared by homopolymerizing the compound of formula (1) or copolymerizing it with other radically polymerizable compounds and curing the obtained composition. It may include radical polymerization initiators when necessary.

In a case where a radically polymerizable compound used for copolymerization is polyfunctional, crosslinking density can be controlled.

Radically polymerizable compound used for copolymerization, radical polymerization initiators and polymerization (curing) methods are as described above. However, it is preferable that solvent not be used, since it requires removal from the cured product.

In a case where the radically polymerizable compound of the present invention and other radically polymerizable compounds are copolymerized, there is no particular limitation on blending amounts in the composition. It is preferable that the radically polymerizable compound of the present invention be contained at 60 mass % or more in the composition, more preferably 75 mass % or more.

In either case of homopolymerization and copolymerization, if cast curing is employed as curing method, a monofunctional radical polymerizable monomer is appropriately blended therein as a reactive diluent to thereby adjust viscosity, so that the composition with decreased viscosity can be easily infused in a mold. It is preferable that the viscosity be 600 mPa's or less at the temperature when the composition is infused into a mold, more preferably 300 mPa's or less, particularly preferably 200 mPa*s or less. The viscosity is measured according to JIS Z8803. Examples of monofunctional radical polymerizable monomer include monofunctional compounds among the compounds described above as examples for radically polymerizable compounds used in copolymerization with the radically polymerizable compound of the present invention.

Also, in the composition for optical material according to the present invention, various known additives such as ultraviolet absorber, antioxidant, mold-releasing agent, colorant (pigment, dye) , liquidity adjuster, leveling agent , inorganic filler and the like can be added.

Examples of UV absorber include triazoles such as 2- (2' -hydroxy-tert-butylphenyl ) benzotriazole, benzophenones such as 2 , 4-dihydroxybenzophenone, salicylates such as 4-tert-butylphenyl salicylate, and hindered amines such as bis- (2, 2, 6, 6-tetramethyl-4-piperidinyl) sebacate . The UV absorber is not limited to these examples.

The blending amount of the UV absorber differs depending on the kinds and amounts of the other additives . Generally, a preferred amount is within a range of 0.01 to 2 parts by mass, more preferably 0.03 to 1.7 parts by mass, most preferably 0.05 to 1.4 parts by mass based on 100 parts by mass of the total radically polymerizable compound contained in the composition for optical material. If the amount of the UV absorber is less than 0.01 parts by mass, sufficient effect cannot be expected . Also, addition exceeding 2 parts by mass is economically disadvantageous.

Examples of antioxidant include phenol-based ones such as 2, 6-di-tert-butyl-4-methylphenol, tetrakis- [methylene-3- ( 3' , 5' -di-tert-butyl-4-hydroxyphe nyl) propionate] methane, sulfur-based ones such as dilauryl-3, 3' -thiodipropionate, and phosphorus based ones such as trisnonylphenyl phosphite. The antioxidant is not limited to these examples.

The blending amount of the antioxidant differs depending on the kinds and amounts of the other additives. Generally, a preferred amount is within a range of 0.01 to 5 parts by mass, more preferably 0.05 to 4 parts by mass, most preferably 1 to 3 parts by mass based on 100 parts by mass of the total radically polymerizable compound contained in the composition for optical material. If the amount of the antioxidant is less than 0.01 parts by mass, sufficient effect cannot be expected. Also, addition exceeding 5 parts by mass is economically disadvantageous.

Examples of mold-releasing agent include stearic acid, butyl stearate, zinc stearate, stearic acid amide, fluorine-based compound and silicon compound. The mold-releasing agent is not limited to these examples.

The blending amount of the mold-releasing agent differs depending on the kinds and amounts of the other additives. Generally, a preferred amount is within a range of 0.01 to 2 parts by mass, more preferably 0.03 to 1.7 parts by mass, most preferably 0.05 to 1.4 parts by mass based on 100 parts by mass of the total radically polymerizable compound contained in the composition for optical material. If the amount of the mold-releasing agent is less than 0.01 parts by mass, sufficient effect cannot be expected. Also, addition exceeding 5 parts by mass is economically disadvantageous and may cause problems, e.g., making the surface of the cured product sticky. Examples of colorant include organic pigments such as anthraquinone series, azo series, carbonium series, quinoline series, quinone imine series, indigoid series and phthalocyanine series; organic dyes such as azoic dye and sulfide dye; inorganic pigments such as titanium yellow, yellow iron oxide, zinc yellow, chrome orange, molybdenum red, cobalt violet , cobalt blue, cobalt green, chromium oxide, titanium oxide, zinc sulfide and carbon black . The colorant is not limited to these examples. Also, the blending amount of the colorant is not limited specifically. In a case where the composition for optical material of the present invention is formed into an optical material like plastic lens, cast-molding is suitable. As a specific example of the method, a method where, after adding radical polymerization initiator to the composition, the composition is injected through a tube or pipe into a mold fixed with an elastomer gasket or a spacer and cured by heat in an oven can be cited.

It is preferred that the material used for the mold be metal or inorganic glass. Generally, after the cast-molding process, the molds used for forming plastic lens require washing with strong acid or strong alkali . Therefore, inorganic glass, which is not denatured by washing and can easily give a flat surface by polishing, is particularly preferred. The curing temperature in forming the composition for optical material of the present invention into plastic lens depends on the composition ratio of the radically polymerizable composition and the kinds and amounts of the additives and cannot be flatly determined, however, generally it is about 20 to 150 ⁰C, preferably 30 to 120 °C.

Moreover, in consideration for contraction and distortion caused by curing, it is preferable that the composition be gradually cured by raising the curing temperature. Generally, it is preferable that curing take 0.5 to 100 hours, preferably 3 to 50 hours, more preferably 10 to 30 hours.

Further, a molded body comprising cured product of the composition for optical material of the present invention maybe subj ected to various coating treatments when necessary. For example, a layer with high hardness can be formed on the molded body by using a coating solution containing organic silicon compound or fine particulate inorganic substance such as tin oxide, silicon oxide, zirconium oxide or titanium oxide, in order to enhance abrasion resistance. Also, in order to enhance impact resistance, a primer layer mainly comprising polyurethane or polyester can be provided. Furthermore, in order to imparting antireflective property, an antireflective layer can be provided by using silicon oxide, titanium oxide, zirconium oxide, tantalum oxide or the like . Still further, in order to improve water-repellent property, a water-repellent layer can be provided on the antireflective layer by using an organic silicon compound containing fluorine atoms . [Optical material]

The cured product of the composition for optical material of the present invention can be used for optical lenses such as eyeglass lens and camera lens and as optical materials such as light waveguide, optical sealant, optical adhesive, optical film, prism, light guide plate for liquid crystal panel, optical fiber, transparent panel, transparent film and transparent sheet.

EXAMPLES Hereinafter, the invention will be more specifically described with reference to examples and comparative examples, but the invention is not limited thereto.

Measuring methods of the physical properties of the products obtained in the Examples and Comparative Examples are described below.

1. Refractive index (n_D) and Abbe number (v_D) Apparatus used: Abbe refractometer lT-type (manufactured by ATAGO CO. , LTD. )

Measuring method: A sample piece of 9 mm x 16 mm x 4 mm was prepared, by using Abbe refractometer lT-type, the refractive index (n_D) and the abbe number (v_D) at 25 °C were measured. As contact solution, diiodomethane was used.

2. ¹H-NMR, ¹³C-NMR

Apparatus used: JEOL EX-400 ( 400MHz, manufactured by JEOL Ltd . )

Measuring method: The sample was dissolved in deuterated chloroform and measured using tetramethylsilane as an internal reference material. 3. FT-IR

Apparatus used: Spectrum GX, product of Perkin Elmer Co., Ltd.

Measuring method: The sample was measured by using a KBr plate according to liquid membrane technique. 4. Barcol hardness

Hardness was measured according to JIS K6911 by using an impressor, GYZJ934-1, manufactured by Barber-Coleman .

Example 1: Synthesis of S, S' -bis [2- (allyloxycarbonylthio ) ethyl] dithiocarbonate (abbreviated as BADTC)

(5) (6) (7)

O

^1/2 /Y Y\

O)

To a three-necked flask equipped with a thermometer, a dropping funnel and a stirrer, sodium hydroxide (8.07g,

0.20mol ) was added and completely dissolved in 80.7 g of pure water. Further to the solution, 24.0 ml of toluene was added.

This flask was immersed in ice bath, and the temperature inside the reaction system was adjusted to 10 °C or less. Ethane dithiol (formula ( 6) , manufactured by Tokyo Chemical Industry- Co., Ltd., 19.0Og, 0.20 mol) was slowly added thereto while stirring. After stirred for 20 minutes, a solution obtained by dissolving allyl chloroformate ( formula ( 5) , manufactured by Tokyo Chemical Industry Co., Ltd., 24.36g, 0.20 mol) diluted with 24.0 ml of toluene was placed in the dropping funnel and dropped into the above ethane dithiol solution over 1 hour. After completion of dropping, the temperature inside the reaction system was kept at 10 °C or less and the solution was stirred for 1 hour. This reaction solution was transferred to a separating funnel and separation operation was conducted. Further, the toluene layer was repeatedly washed until the pH value of the water layer became 7. The obtained toluene layer was driedwith anhydrous sodium sulfate and sodium sulfate was removed through filtration, to thereby obtain a dehydrated toluene solution of 0-allyl S- (2-mercaptoethyl) thiocarbonate (formula (7)).

Separately, a three-necked flask equipped with a thermometer, a dropping funnel, a Dimroth condenser and a stirrer was purged with nitrogen and in this flask, the above obtained toluene solution was placed. Then, the flask was immersed in ice bath to thereby lower the temperature of the content to 10 °C or less. A solution obtained by dissolving N, N' -carbonyl diimidazole (formula (8), manufactured by

HODOGAYA CHEMICAL CO., LTD., 16.4g, 0.10 mol) in 115.0 ml of N,N-dimethylformamide (DMF) was added thereto by dropwise from the dropping funnel over 1 hour.

Then, the temperature inside the reaction system was kept at 10 °C or less and the solution was stirred for 3 hours. 50 mL of pure water was added thereto and the reaction solution was transferred to a separating funnel and separation operation was conducted. Further, the obtained organic layer was treated with 15 mL of 5% sodium hydroxide aqueous solution, 50 ml of pure water and 15 mL of 5% hydrochloric acid and finally was washed with pure water repeatedly until the water layer became neutral. The organic layer recovered here was dried with anhydrous sodium sulfate, sodium sulfate was removed through filtration and substances having low boiling points were removed under reducedpressure, to thereby obtain 37.6 g of a crude product . Further, by using a mixed solvent of hexane and ethyl acetate as developing solvent, the crude product was purified by column chromatography, to thereby obtain a colorless transparent liquid, (yield: 21. 4g, 56.0 %)

Through measurement of the ¹H-NMR, ¹³C-NMR and IR of this liquid, the liquid was confirmed to be the target compound, S, S '-bis [2- (allyloxycarbonylthio) ethyl ] dithiocarbonate

(formula (9) ). The results of the ¹H-NMR, ¹³C-NMR and IR analyses are shown in Figures 1 to 3.

Example 2: Curing reaction of BADTC To the BADTC (2.500 g) obtained in Example 1, 1, 1-di (t-hexylperoxy) -3, 3, 5-trimethylcyclohexane (manufactured by NOF Corporation, Product Name: Perhexa TMH, O.OlOg), which is a radical polymerization initiator, was added and the mixture was infused into a 4mm-thick molding die consisting of two glass plates and a silicone tube as a spacer. This molding die was placed in an oven to be heated in a curing temperature program where the temperature was first 70 °C for 7 hours, then increased to 90 °C over 10 hours, further to 120 °C over 3 hours and the temperature was kept at 120 °C for 2 hours, to thereby thermally cure the BADTC.

The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product (refractive index, abbe number and Barcol hardness) are shown in Table 2.

Example 3: Curing of copolymerized composition of BADTC and trimethylol propane trimethacrylate To a mixture of the BADTC (2.375 g) obtained in Example 1 and trimethylol propane trimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., 0.125 g) , t-hexylperoxy-2-ethyl hexanoate (manufactured by NOF Corporation, Product Name: Perhexyl 0 ,0.075 g) and Perhexa TMH ( 0.025g) , which are a radical polymerization initiators, were added. The mixture was cured by using the same type of molding die and curing temperature program as used in Example 1.

The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2.

Example 4: Curing of copolymerized composition of BADTC and diallyl isophthalate _#

To a mixture of the BADTC (1.803 g) obtained in Example 1 and diallyl isophthalate (0.203 g) , 1,1,3, 3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, Product Name: Perocta-O, 0.061 g) and Perhexa -TMH (0.02Og), which are radical polymerization initiators, were added. The mixture was infused into a 4mm-thick molding die consisting of two glass plates and a silicone tube as a spacer. This was placed in an oven to be cured by heat in a curing temperature program where the temperature was increased from 60 °C to 120 °C over 16 hours and kept for 2 hours.

Example 5: Curing of copolymerized composition of BADTC and diallyl 1, 4-cyclohexane dicarboxylate To a mixture of the BADTC (1.807 g) obtained in Example 1 and diallyl 1 , 4-cyclohexane dicarboxylate (0.202g), Perocta-0 (0.066g) and Perhexa-TMH (0.02Og) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4. The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2. Example 6: Curing of copolymerized composition of BADTC and isobornyl methacrylate

To a mixture of the BADTC (1.907 g) obtained in Example 1 and isobornyl methacrylate (KYOEISHA CHEMICAL Co., LTD., product name: Light-Ester IB-X, 0.105 g) , Perocta-0 (0.065 g) and Perhexa TMH (0.023g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 7: Curing of copolymerized composition of BADTC and dicyclopentanyl methacrylate

To a mixture of the BADTC (1.900 g) obtained in Example 1 and dicyclopentanyl methacrylate (manufactured by Hitachi Chemical Co . , Ltd. , product name : FA-513M, 0.10Ig), Perocta-0 (0.064 g) and Perhexa-TMH (0.023 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 8: Curing of copolymerized composition of BADTC and allyl ester oligomer-1

To a mixture of the BADTC (1.80Ig) obtained in Example 1 and allyl ester oligomer-1 {mixture of compounds of the following formula (10) , 40 mass% of the compound wherein n=0 (monomer) and 60 mass % of the compound wherein n=l or more} (0.206g) , Perocta-0 ( 0.064 g) and Perhexa-TMH (0.029 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

The allyl ester oligomer-1 used here was synthesized as follows. In a three-necked 3L-volume flask equipped with distillation equipment, 1500.0 g (6.09 mol) of diallyl isophthalate, 154.5 g (2.03mol) of propylene glycol and 1.50 g of dibutyl tin oxide were placed. The content was heated at 180 ⁰C under nitrogen atmosphere and allyl alcohol generatedwas distilled off . At the time point when the amount of the allyl alcohol distilled off became about 140 g, the inside of the reaction system was depressurized to 1.33 kPa, to thereby increase the distillation rate of allyl alcohol. After the theoretical amount (235.9 g) of allyl alcohol was distilled off, the reaction system was kept at 180 °C/0.13 kPa for another hour. Then, the reaction vessel was cooled down to thereby obtain 1420.1 g of allyl ester oligomer-1. Example 9: Curing of copolymerized composition of BADTC and allyl ester oligomer-2

To a mixture of the BADTC (1.802 g) obtained in Example 1 and allyl ester oligomer-2 {mixture of compounds of the following formula (11), 45 mass% of the compound wherein n=0 (monomer) and 55 mass % of the compound wherein n=l or more} (0.203 g) , Perocta-0 (0.064 g) and Perhexa-TMH (0.021 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

The allyl ester oligomer-2 used here was synthesized as follows.

In a three-necked 3L-volume flask equipped with a distillation equipment, 1500.0 g (5.95 mol) of diallyl 1 , 4-cyclohexane dicarboxylate, 177.3 g (1.32 mol) of trimethyIo1 propane and 1.50 gof dibutyl tin oxide were placed. The content was heated at 180 °C under nitrogen flow and allyl alcohol generated was distilled off. At the time point when the amount of the allyl alcohol distilled off became about 138 g, the inside of the reaction system was depressurized to 1.33 kPa, to thereby increase the distillation rate of allyl alcohol. After the theoretical amount (230.2 g) of allyl alcohol was distilled off, the reaction system was kept at 180 °C/0.13 kPa for another hour . Then, the reaction vessel was cooled down to thereby obtain 1448.5 g of allyl ester oligomer-2.

Example 10: Curing of copolymerized composition of BADTC and allyl ester oligomer-3

To a mixture of the BADTC (1.808 g) obtained in Example

1 and allyl ester oligomer-3 {mixture of compounds of the following formula (12) , 40 mass% of the compound wherein n=0

(monomer) and 60 mass % of the compound wherein n=l or more} (0.212 g) , Perocta-0 (0.061 g) and Perhexa-TMH (0.022 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

The allyl ester oligomer-3 used here was synthesized as follows.

In a three-necked 3L-volume flask equipped with a distillation equipment, 1500 g (6.09 mol) of diallyl isophthalate, 554.7 g (0.88 mol) of

2,2-bis[4-( 2-hydroxyethoxy) -3, 5-dibromophenyl ] propane and 1.50 g of dibutyl tin oxide were placed. The content was heated at 180 °C and allyl alcohol generated was distilled off. At the time point when the amount of the allyl alcohol distilled off became about 61 g, the inside of the reaction system was depressurized to 1.33 kPa, to thereby increase the distillation rate of allyl alcohol . After the theoretical amount (102.0 g) of allyl alcohol was distilled off, the reaction system was kept at 180 °C/0.13 kPa for another hour . Then, the reaction vessel was cooled down to thereby obtain 1954.2 g of allyl ester oligomer-3.

Example 11 : Curing of copolymerized composition of BADTC and triallyl trimellitate

To a mixture of the BADTC (1.907 g) obtained in Example 1 and triallyl trimellitate (manufactured by Wako Pure Chemical Industries, Ltd. ,0.103 g) , Perocta-0 (0.061 g) and Perhexa-TMH (0.022 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 12 : Curing of copolymerized composition of BADTC and triallyl isocyanurate

To a mixture of the BADTC (1.803 g) obtained in Example 1 and triallyl isocyanurate (manufactured by Wako

Pure Chemical Industries, Ltd., 0.201 g) , Perocta-0 (0.061 g) and Perhexa-TMH (0.025 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 13: Curing of copolymerized composition of BADTC and diallyl maleate

To a mixture of the BADTC (1.806 g) obtained in

Example 1 and diallyl maleate (0.202g), Perocta-0 (0.062 g) and Perhexa-TMH (0.023 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 14: Curing of copolymerized composition of BADTC and allyl methacrylate To a mixture of the BADTC (4.759 g) obtained in

Example 1 and allyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd., 0.256 g), Perocta-0 (0.150 g) and Perhexa-TMH (0.053 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 15: Curing of copolymerized composition of BADTC, allyl ester oligomer-2 and allyl methacrylate

To a mixture of the BADTC (4.25I g) obtained in Example 1, allyl ester oligomer-2 ( 0.509 g) and allyl methacrylate

(0.251 g) , Perocta-0 (0.151 g) and Perhexa-TMH (0.060 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4. The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2.

Example 16: Curing of copolymerized composition of BADTC, allyl ester oligomer-1 and allyl methacrylate

To a mixture of the BADTC (4.251 g) obtained in Example 1, allyl ester oligomer-1 ( 0.501 g) and allyl methacrylate (0.257 g) , Perocta-0 (0.154 g) and Perhexa-TMH (0.053 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 17 : Curing of copolymerized composition of BADTC and diallyl 1 , 4-cyclohexane dicarboxylate and allyl methacrylate

To a mixture of the BADTC (4.259 g) obtained in Example 1, diallyl 1 , 4-cyclohexane dicarboxylate (0.252 g) and allyl methacrylate (0.264 g) , Perocta-0 (0.155g) and Perhexa-TMH (0.057g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 18: Curing of copolymerized composition of BADTC, allyl ester oligomer-2 and diallyl maleate To a mixture of the BADTC (4.504 g) obtained in Example 1, allyl ester oligomer-2 (0.256 g) and diallyl maleate (0.251 g), Perocta-0 (0.15Ig) and Perhexa-TMH (0.053 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2. Example 19: Curing of copolymerized composition of BADTC and CR-39

To a mixture of the BADTC (1.810 g) obtained in Example 1 Example 1 and CR-39 (manufactured by PPG Industries, Ltd. ,0.201 g), Perocta-0 (0.065 g) and Perhexa-TMH (0.022 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4. The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2.

Example 20: Curing of copolymerized composition of BADTC, diallyl isophthalate and benzyl methacrylate

To a mixture of the BADTC (1.802 g) obtained in Example 1, diallyl isophthalate (0.104 g) and benzyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd., 0.102 g) , Perocta-0 (0.062 g) and Perhexa-TMH (0.020 g) were added. The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 21: Curing of copolymerized composition of BADTC, allyl ester oligomer-2 and benzyl methacrylate

To a mixture of the BADTC (1.906 g) obtained in Example 1, allyl ester oligomer-2 (0.093 g) and benzyl methacrylate (0.018 g) , Perocta-0 (0.062 g) and Perhexa-TMH ( 0.026 g) were added . The mixture was cured by heat by using the same type of the molding die and curing temperature program as used in Example 4.

Example 22: Curing of copolymerized composition of BADTC, allyl ester oligomer-4 and allyl methacrylate To a mixture of the BADTC (2.250 g) obtained in Example

1, allyl ester oligomer-4 (represented by the following formula (13), with 40 mass% of the oligomer being n=0

(monomer) and 60 mass % being n=l or more }(0.600g) and allyl methacrylate (0.15Og), Perocta-0 (0.09Og) and Perhexa-TMH (0.030 g) were added. The mixture was infused into the same type of the molding die as used in Example 4, and cured by heat in a curing temperature program where the temperature was increased from 45 to 120 °C over 16 hours and kept at 120 °C for 2 hours. The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2.

The allyl ester oligomer-4 used here was prepared as follows .

In a three-necked lL-volume flask equipped with a distillation equipment, 400.04 g (1.624 mol) of diallyl . terephthalate, 146.68 g (0.23 mol) of

2 , 2-bis [4- ( 2-hydroxyethoxy) -3, 5-dibromophenyl ] propane and 0.127 g of dibutyl tin oxide were placed. The content was heated at 180 °C under nitrogen flow and allyl alcohol generatedwas distilled off . At the time point when the amount of the allyl alcohol distilled off became about 13.7 g, the inside of the reaction system was depressurized to 1.33 kPa, to thereby increase the distillation rate of allyl alcohol. After the theoretical amount (27.0 g) of allyl alcohol was distilled off, the reaction system was kept at 180 °C/0.13 kPa for another hour. Then, the reaction vessel was cooled down to thereby obtain 519.0 g of allyl ester oligomer-4.

Example 23 : Curing of copolymerized composition of BADTC and triallyl cyanurate

To a mixture of the BADTC (2.550 g) obtained in Example 1 and triallyl cyanurate (manufacturedby Wako Pure Chemical Industries, Ltd., 0.450 g) , Perocta-0 (0.090 g) and Perhexa-TMH (0.030 g) were added. The mixture was cured by heat in the same manner as in Example 22.

Example 24: Curing of copolymerized composition of BADTC, triallyl cyanurate and allyl methacrylate

To a mixture of the BADTC (2.550 g) obtained in Example

1, triallyl cyanurate (0.300 g) and allyl methacrylate

(0.150 g) , Perocta-0 (0.091 g) and Perhexa-TMH (0.030 g) were added. The mixture was cured in the same manner as in Example 22.

Example 25: Curing of copolymerized composition of BADTC, divinyl benzene and diallyl maleate

To a mixture of the BADTC (1.50Og) obtained in Example 1, divinyl benzene (manufactured by Wako Pure Chemical Industries, Ltd., 0.100 g) and diallyl maleate (0.399 g) , Perocta-0 (0.060 g) and Perhexa-TMH (0.020 g) were added. The mixture was cured by heat in the same manner as in Example 22.

Example 26: Curing of copolymerized composition of BADTC, divinyl benzene and allyl methacrylate

To a mixture of the BADTC (1.700 g) obtained in Example

1, divinyl benzene (0.100 g) and allyl methacrylate (0.201 g) , Perocta-0 (0.06Og) and Perhexa-TMH (0.019 g) were added. The mixture was cured in the same manner as in Example 22.

Example 27: Curing of copolymerized composition of BADTC, allyl methacrylate and diallyl maleate

To a mixture of the BADTC (2.549 g) obtained in Example

1, allyl methacrylate (0.015 g) and diallyl maleate ( 0.301 g) , Perocta-0 (0.09Og) and Perhexa-TMH (0.03Og) were added.

The mixture was cured by heat in the same manner as in Example

22.

Example 28: Curing of BADTC

To the BADTC (2.00Og) obtained in Example 1, Perocta-0 (0.06Og) and Perhexa-TMH (0.02Og) were added. The mixture was cured by using the same molding dye and temperature program as in Example 4.

Example 29: Forming a lens of copolymerized composition of BADTC, allyl ester oligomer-2 and allyl methacrylate

To a mixture of the BADTC (21.20 g) obtained in Example

1, allyl ester oligomer-2 (2.550 g) and allyl methacrylate

(1.250 g) , Perocta-0 (0.750 g) and Perhexa-TMH (0.250 g) were added. The mixture was stirred until it became uniform. The obtained composition was infused into a casting die for lens of -2.00 diopter consisting of a glass mold and a resin gasket and was cured by heat in the same curing temperature program as in Example 15. After curing, the cured product was removed from the die to thereby obtain a lens-shaped formed body.

Comparative Example 1: Curing of bis (allyloxycarbonyl thioethyl) sulfide

A compound represented by formula (14), bis (allyloxycarbonyl thioethyl) sulfide was synthesized according to Example 1 in paragraph [0025] of Japanese Patent Application Laid-Open No. 10-175947.

To this bis (allyloxycarbonyl thioethyl) sulfide (2.500 g) , Perhexa-TMH (0.10Og) was added and the mixture was infused into a 4mm-thick molding die consisting of two glass plates and a silicone tube as a spacer while heating. This was placed in an oven and cured by heat in a curing temperature program where the die was heated at 70 °C for 7 hours, the temperature was increased to 90 °C over 10 hours and further increased to 120 ⁰C for 3 hours and was kept for 2 hours.

The physical properties of the resultant yellow transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2.

Comparative Example 2: Curing of bis ( allyloxycarbonylthioethyl ) sulfide

To bis (allyloxycarbonylthioethyl) sulfide (2.000 g) obtained in Comparative Example 1, Perocta-0 (0.060 g) and Perhexa-TMH (0.020 g) were added. The mixture was cured by using the same molding dye and temperature program as in Example 4. The resultant cured product was rubber-like. The physical properties of the resultant colorless transparent cured product were measured. The resin composition is shown in Table 1 and the properties of the cured product are shown in Table 2.

Table 1

T ab l e 2

Abbreviations used in Tables 1 and 2 are as follows Ex . : Example

C. Ex. or Comp. EX. : Comparative Example BADTC: S, S' -bis [2- ( allyloxycarbonylthio) ethyl ]dithiocarbonate

TMPTMA: trimethylolpropane trimethacrylate

DAIP: diallyl isophthalate

H-DATP: diallyl 1 , 4-cyclohexane dicarboxylate IBMA: isobornyl methacrylate

DCPMA: dicyclopentanyl methacrylate

AEO-I, 2, 3 AND 4: allyl ester oligomers-1 to 4

TAT: triallyl trimellitate

TAIC: triallyl isocyanurate DAM: diallyl maleate

AMA: allyl methacrylate

BzMA: benzyl methacrylate

CR-39: diethylene glycol bisallyl carbonate

DVB: divinyl benzene TAC: triallyl cyanurate

ACS : bis ( allyloxycarbonylthioethyl ) sulfide

HO: Perhexyl-0

00: Perocta-0

TMH: Perhexa-TMH

As seen in the results, all the cured products obtained from the radically polymerizable compound and the composition for optical material of the present invention were colorless and transparent, having high refractive indices and are useful for optical material . On the other hand, in the cured product of Comparative Example 1, the balance between the refractive index and the abbe number was bad and moreover, it was colored. The cured product of Comparative Example

2 was like a hard rubber. INDUSTRIAL APPLICABILITY

The radically polymerizable compound having a dithiocarbonate structure and a sulfur-containing allylcarbonate group of the present invention, which is stable and little colored at the time of heat curing reaction, can give an optical material having a high refractive index and an excellent transparency.

The cured product of the composition for optical material of the present invention can be used as optical materials such as optical lenses for eyeglasses and cameras, light waveguide, optical sealant, optical adhesive, optical film, prism, light guide plate for liquid crystal panel, optical fiber, transparent panel, transparent film and transparent sheet.

Claims

1. A radically polymerizable compound represented by formula ( 1) ,

wherein R¹ and R² each independently represents a hydrogen atom or methyl group, and X and Y each independently represents a divalent group selected from group consisting of analkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group.

2. The radically polymerizable compound according to claim 1, wherein X and Y in formula (1) are a methylene group, an ethylene group, 1 , 2-propylene group, or a 1 , 3-propylene group.

3. The radically polymerizable compound according to claim 1 or 2, wherein R¹ and R² in formula (1) are hydrogen atoms .

4. A method of producing the radically polymerizable compound represented by formula (1), comprising allowing a thiol compound represented by formula (2) with a dithiol compound represented by formula (3) in the presence of a base to thereby obtain a thiol compound representedby formula (4) and further allowing the thiol compound with N, N' -carbonyl diimidazole.

HS^/L^SH <²> wherein L represents a divalent group selected from a group consisting of an alkylene group having 1 to 10 carbon atoms which may be branched, an arylene group and a cycloalkylene group,

O wherein R⁴ represents a hydrogen atom or a methyl group and

Z represents a chlorine atom or a bromine atom,

wherein symbols in the formula have the same meanings as defined above.

5. The method of producing the radically polymerizable compound according to claim 4, wherein X and Y in formula (1) are a methylene group, an ethylene group, 1 , 2-propylene group, or a 1 , 3-propylene group.

6. The method of producing the radically polymerizable compound according to claim 4 or 5, wherein R¹ and R² in formula (1) are hydrogen atoms.

7. A polymer or copolymer comprising the radically polymerizable compound according to claim 1 as one of its raw material monomers.

8. The copolymer according to claim 7, which is a copolymer of the radically polymerizable compound according to claim 1 and other radically polymerizable compounds.

9. The copolymer according to claim 8 , which is a copolymer of the radically polymerizable compound according to claim

1 and allyl methacrylate and/or diallyl maleate.

10. A polymerizable composition for an optical material, comprising the radically polymerizable compound according to claim 1.

11. The polymerizable composition for an optical material according to claim 10, further comprising other radically polymerizable compounds.

12. The polymerizable composition for an optical material according to claim 11, wherein the other radically polymerizable compounds include at least allyl methacrylate and/or diallyl maleate.

3. Alensobtainedbycuringthe polymerizable compositionor an optical material according to any one of claims 10o 12.