JP2609474B2 - Manufacturing method of high refractive index resin - Google Patents

Description

The present invention relates to a method for producing a high refractive index resin particularly useful as an optical material.

(Prior art)

Heretofore, various studies have been made on synthetic resins in place of inorganic glass, but there are many drawbacks, and no satisfactory properties have yet been obtained. For example, methyl methacrylate or diethylene glycol bis (allyl carbonate)
A polymer obtained by polymerizing a monomer having as a main component is used as an optical resin or a lens, and has a refractive index of about 1.50.
And low.

For this reason, various crosslinkable monomers for high refractive index resins have been proposed. For example, Japanese Patent Application Laid-Open No. 61-28901 discloses a resin obtained by polymerizing a monomer containing a large number of halogen atoms, such as phenyl methacrylate in which a phenyl group is substituted with a halogen atom. JP-A-60-197711 proposes a composition for a high refractive index resin containing α-naphthyl methacrylate as a main component. However, these high-refractive-index resins have a problem that the refractive index is high but the dispersion is large. In order to obtain a resin having a high refractive index and a low dispersion, Japanese Patent Application Laid-Open Nos.
-26613 and the like, thiomethacrylic acid esters and thioacrylic acid esters (hereinafter referred to as thio (meth)
It is generically called an acrylic ester. ) Is being polymerized.

[Problems to be Solved by the Invention]

Thio (meth) acrylates are generally prepared by reacting the corresponding acid or acid chloride with a mercapto compound. For this reason, it is inevitable that unreacted mercapto compounds are mixed into the produced thio (meth) acrylate and further into the high refractive index resin obtained by polymerization thereof. The thio (meth) acrylate ester is partially decomposed during radical polymerization to produce a mercapto compound. For this reason, the high refractive index resin obtained by polymerizing thio (meth) acrylate often emits a strong mercaptan odor. For this reason, it was difficult to use the obtained high refractive index resin for applications such as eyeglass lenses.

In view of the above, the problem to be solved by the present invention is to provide a high refractive index resin which has a high refractive index and low dispersion, is excellent in transparency, weather resistance and light weight, and has no odor. .

[Means for Solving the Problems] The present inventors have conducted intensive studies in order to solve the above problems, and as a result, the presence of the isocyanate compound during the polymerization of the thiocarboxylic acid ester allows the presence of the isocyanate compound before the polymerization. The present inventors have found that it is possible to prevent the odor caused by the mercapto compound which has been produced or produced during the polymerization, thereby providing the present invention.

That is, the present invention polymerizes a thiocarboxylic acid ester monomer having one or more acryloylthio groups or methacryloylthio groups in one molecule in the presence of an isocyanate compound having one or more isocyanate groups in one molecule. This is a method for producing a high refractive index resin.

In the present invention, a compound having at least one acryloylthio group or methacryloylthio group in one molecule is used as the thiocarboxylic acid ester monomer to be subjected to polymerization without any limitation. In the present invention, for example, thiocarboxylic acid ester monomers represented by the following formulas [I] and [II] are suitably used for obtaining a resin having a high refractive index.

In the general formulas (I) and (II), R ² and R ³ may be the same or different hydrogen atoms or alkyl groups, respectively.
From the viewpoint of using a polymer obtained by polymerization for an optical material, a hydrogen atom or a methyl group is preferable.

In the general formula [I], R ⁴ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. The alkyl group is not particularly limited in the number of carbon atoms, but has 1 to 5 carbon atoms from the viewpoint of the viscosity of the thiocarboxylic acid ester monomer and the refractive index of the polymer obtained by polymerization. Is preferred. For example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, S-
Butyl group, t-butyl group, n-pentyl group and the like.
The aryl group is not particularly limited in the number of carbon atoms, but preferably has 6 to 10 carbon atoms for the same reason as described above. For example, a phenyl group,
Examples include a tolyl group, a xylyl group, and a naphthyl group.

The aralkyl group is not particularly limited in the number of carbon atoms, but is preferably 7 to 10 for the same reason as described above. For example, a benzyl group, a phenethyl group, a phenylpropyl group and the like can be mentioned.

Examples of the substituent of the alkyl group, aryl group and aralkyl group represented by the R ^4, is not particularly limited, a halogen atom, an alkoxy group, an alkylthio group, phenyl group, and a phenylthio group. Representative examples of these substituted alkyl groups, substituted aryl groups and substituted aralkyl groups are, for example, halogen aralkyl groups such as chlorophenylmethyl group, dibromophenylmethyl group and tribromophenylmethyl group; chloromethyl group Halogenoalkyl groups such as chloro, bromomethyl and trichloromethyl groups; halogenoaryl groups such as chlorophenyl, bromophenyl, dichlorophenyl, dibromophenyl and tribromophenyl groups; methylthiophenyl and di (methylthio) phenyl Group, phenylthiophenyl group,
Examples thereof include a biphenyl group, a methylthiophenylmethyl group, and a di (methylthio) phenylmethyl group.

In the above general formulas (I) and (II), m, n ₁ , n ₂ and n
3 may be an integer of 0 or more. In general, if these values are too large, the viscosity of the compounds represented by the general formulas (I) and (II) sharply increases, making it difficult to handle them, and the heat resistance of the resin obtained by polymerization becomes lower. There is a problem of being done. Therefore, considering the refractive index, impact resistance and heat resistance of the obtained resin, m, n ₁ , n ₂ ,
And n3 is in the range of each 0-5, especially m is in the range of 1 to 3, n _1, n ₂ and n3 is preferably selected in the range of 0-2.

In the above thiocarboxylic acid ester monomer, R ⁴ in the general formula (I) may be selected according to the use of the obtained resin, but in order to obtain a resin having a high refractive index and a low dispersion,
R ⁴ is preferably a substituted or unsubstituted aralkyl group.

These monomers can be used alone or in combination of two or more.

On the other hand, as the isocyanate compound having one or more isocyanate groups in one molecule, a known isocyanate compound can be used without any limitation. Examples thereof include aliphatic monoisocyanates such as methyl isocyanate, ethyl isocyanate, isopropyl isocyanate, n-butyl isocyanate, chloromethyl isocyanate, α-methylbenzyl isocyanate, benzyl isocyanate and cyclohexyl isocyanate. Aromatic monoisocyanates such as phenyl isocyanate, α-naphthyl isocyanate, tolyl isocyanate, chlorophenyl isocyanate, trifluoromethylphenyl isocyanate; hexamethylene diisocyanate, isophorone diisocyanate, m -Xylylene diisocyanate, bis (isocyanatomethyl) cyclohexane,
Aliphatic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate; aromatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and naphthalene diisocyanate; hexa Biuretization reaction product of methylene diisocyanate; trifunctional or higher functional isocyanate compound such as adduct product of hexamethylene diamine and trimethylolpropane; radical polymerizable group such as 2-isocyanate ethyl methacrylate and styryl isocyanate Isocyanates and the like. These isocyanate compounds can be used alone or in combination of two or more.

Among these isocyanate compounds, an aliphatic mono- or diisocyanate or an isocyanate compound having a radically polymerizable group is preferable from the weather resistance and optical properties of the obtained resin, and an isocyanate compound having a radically polymerizable group is particularly preferable. Is preferably used because even if it is used excessively, the obtained resin does not become turbid and a decrease in optical properties is not a problem. The amount of the isocyanate compound to be used cannot be unconditionally determined because there is an optimum amount depending on the type of the thiocarboxylic acid ester monomer and the isocyanate compound used. The sum of the amount of the compound and the amount of the mercapto compound generated when polymerizing the thiocarboxylic acid ester monomer is generally in the range of 0.0001 to 1 part by weight based on 100 parts by weight of the thiocarboxylic acid ester monomer before polymerization. Therefore, the isocyanate compound is usually 0.0001 parts by weight based on 100 parts by weight of the thiocarboxylic acid ester monomer.
It is sufficient to use up to 5 parts by weight, particularly preferably 0.001 to 1 part by weight.

In the present invention, it is possible to polymerize immediately after mixing the thiocarboxylic acid ester monomer and the isocyanate compound, but in order to more effectively remove the mercapto compound mixed in the thiocarboxylic acid ester monomer. Preferably, the thiocarboxylic acid ester monomer and the isocyanate compound are mixed in advance and reacted at a temperature of 0 to 100 ° C. for 10 minutes to 48 hours, and if necessary, the isocyanate compound is added, followed by polymerization. It is also possible to sequentially add an isocyanate compound during the polymerization of the thiocarboxylic acid ester monomer.

In addition, a known catalyst can be used as necessary to promote the reaction between the isocyanate compound and the mercapto compound. For example, dibutyltin dilaurate, dibutyltin di (2-ethylhexoate), stannous 2-ethylcaproate, stannous oleate, stannous chloride and the like can be mentioned.

In the method in which the mercapto compound and the isocyanate compound mixed in the thiocarboxylic acid ester monomer are reacted in advance, when an excess of the isocyanate compound is used, an unreacted isocyanate compound may remain. . Unreacted isocyanate compound may cause cloudiness of the obtained resin. For this,
It is preferable that the isocyanate compound is left only in an amount sufficient for the reaction with the mercapto compound generated during the polymerization of the thiocarboxylic acid ester monomer, and that the surplus isocyanate compound is converted into another compound. In order to convert the surplus isocyanate compound into another compound, a compound having one or more hydroxyl groups in one molecule (hereinafter, also referred to as an alcohol compound) is suitably used. When the reaction product of the isocyanate compound and the alcohol compound is present in the resin obtained by polymerizing the thiocarboxylic acid ester monomer, it causes elution and the like, and therefore, at least one of the isocyanate compound and the alcohol compound One is
It preferably has a polymerizable group. The amount of the alcohol compound to be added may be selected so that the amount of the isocyanate compound present at the time of polymerization falls within the above-mentioned range. Normal,
Even if the alcohol compound is added up to about 6 equivalents to the unreacted isocyanate compound, a part of the unreacted isocyanate compound reacts with the mercapto compound.
The mercapto compound can be removed well.

In the present invention, examples of preferably used alcohol compounds include 2-hydroxyethyl acrylate and 2-hydroxyethyl acrylate.
Hydroxypropyl acrylate, 1-methyl-2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 1-methyl-2-hydroxyethyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro- 2
Aliphatic monohydroxy methacrylates or acrylates such as hydroxypropyl methacrylate, hydroxymethyl acrylamide, hydroxymethyl methacrylamide, tetramethylol methane triacrylate, tetramethylol methane trimethacrylate, glycerin dimethacrylate, diethylene glycol monomethacrylate; 2,3-dihydroxy Propyl methacrylate, 2,3-dihydroxypropyl acrylate, ethylene glycol di (3-methacryloyloxy-2-hydroxypropyl ether), ethylene glycol di (3-
Fats such as acryloyloxy-2-hydroxypropyl ether), propylene glycol di (3-methacryloyloxy-2-hydroxypropyl ether), 2-hydroxypropylene glycol di (3-methacryloyloxy-2-hydroxypropyl ether) glycerin monomethacrylate Group polyhydroxy methacrylates or acrylates; 3-phenoxy-2-hydroxypropyl methacrylate, 3-phenoxy-2-hydroxypropyl acrylate, P-hydroxymethylbenzyl methacrylate, P-hydroxymethylphenyl methacrylate, P-hydroxymethylphenyl Acrylate,
(2-methacryloyloxyethyl)-(2-hydroxyethyl) -terephthalate, (2-methacryloyloxyethyl)-(2-hydroxyethyl) phthalate,
2,2-bis (4- (2-hydroxyethoxyphenyl)) propane) monomethacrylate, 2,2-bis (3,5
Monohydroxy methacrylates or acrylates having an aromatic nucleus such as -dibromo-4- (2-hydroxyethoxyphenyl)) propane monomethacrylate; 2,2-bis [4- (3-methacryloyloxy-2-
(Hydroxypropoxy) phenyl] propane, 2,2-bis [4- [3- (3-methacryloyloxy-2-hydroxypropoxy) -2-methylpropoxy] phenyl]
Propane, 2,2-bis [4- (3-acryloyloxy-
Dihydroxy methacrylates or acrylates having an aromatic ring such as 2-hydroxypropoxy] phenyl] propane; dially tartrate (diallyl tartrate), diallyl maleate (diallyl malate),
Allyl esters having an alcoholic hydroxyl group such as triallyl citrate (triallyl citrate), diethylene glycol monoallyl carbonate, and 3-butenoic acid glycerin ester; unsaturated polyester oligomers and unsaturated polyurethane oligomers having a hydroxyl group; These are mixtures and the like.

The high refractive index resin provided in the present invention may be a homopolymer of a thiocarboxylic acid ester monomer,
If necessary, a high refractive index resin may be produced using a monomer copolymerizable with the thiocarboxylic acid ester monomer (hereinafter, also referred to as a second monomer) as a copolymerization component. As the second monomer, a known monomer can be used without any limitation as long as it is a monomer copolymerizable with the thiocarboxylic acid ester monomer. Examples of compounds preferably used as the second monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, and fumaric acid; methyl acrylate, methyl methacrylate, benzyl methacrylate, and phenyl methacrylate. , 2-Hydroxyethyl methacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, ethylene glycol bisglycidyl methacrylate, bisphenol A dimethacrylate, 2,2-bis (4-methacryloyloxyethoxyphenyl) propane, 2,2-bis ( 3,5-dibromo-4-
Acrylic acid and methacrylic acid ester compounds such as methacryloyloxyethoxyphenyl) propane and trifluoromethyl methacrylate; fumaric acid ester compounds such as monomethyl fumarate, diethyl fumarate, and diphenyl fumarate; diallyl phthalate, diallyl terephthalate, diallyl isophthalate, and tartaric acid Diallyl, diallyl epoxysuccinate, diallyl malate, allyl cinnamate, allyl isocyanate, diallyl chlorendate, diallyl hexaphthalate, diallyl carbonate,
Allyl compounds such as allyl diglycol carbonate; styrene, chlorostyrene, methylstyrene, vinylnaphthalene, isopropenylnaphthalene, bromostyrene,
And aromatic vinyl compounds such as dibromostyrene and divinylbenzene. These monomers can be used alone or in combination of two or more.

If all of the monomers used for the polymerization have one assembling group, the high refractive index resin obtained by the present invention is a thermoplastic resin. For this reason, especially when the resin is used for applications requiring lapping or the like, it is preferable to copolymerize using a monomer having two or more polymerizable groups as at least one kind of monomer.

The method for polymerizing the thiocarboxylic acid ester monomer in the presence of the isocyanate compound is not particularly limited, and a known radical polymerization method can be employed. Polymerization initiation means, use of radical polymerization initiators such as various peroxides and azo compounds,
Alternatively, irradiation can be performed by irradiation of ultraviolet rays, α rays, β rays, γ rays, or the like, or a combination of both. To illustrate a typical polymerization method, a mixture of a thiocarboxylic acid ester monomer containing a radical polymerization initiator and an isocyanate compound is injected between a mold held by an elastomer gasket or a spacer, and the mixture is placed in an air furnace. After curing, cast polymerization is removed.

The radical polymerization initiator is not particularly limited and known ones can be used. Typical examples thereof include benzoyl peroxide, P-chlorobenzoyl peroxide, decanoyl peroxide, lauroyl peroxide, and acetyl peroxide. Diacyl peroxides such as oxide; peroxyesters such as t-butylperoxy-2-ethylhexanate, t-butylperoxyneodecanate, cumylperoxyneodecanate, t-butylperoxybenzoate; diisopropylperoxy Percarbonates such as dicarbonate, di-2-ethylhexylperoxydicarbonate and di-sec-butylperoxydicarbonate; and azo compounds such as azobisisobutyronitrile. The amount of the radical polymerization initiator used depends on the polymerization conditions, the type of the initiator, and the composition of the monomer, and cannot be unconditionally limited, but is generally 0.001 to 10 based on 100 parts by weight of all the monomers. Parts by weight, preferably 0.00
It is preferable to use in the range of 1 to 5 parts by weight.

Among the polymerization conditions, particularly the temperature affects the properties of the obtained high refractive index resin. This temperature condition is affected by the type and amount of the initiator and the type of the monomer, and thus cannot be limited unconditionally. Generally, the polymerization is started at a relatively low temperature, and the temperature is gradually increased. It is preferable to perform a so-called taper type two-stage polymerization in which the polymerization is cured at a high temperature at the end of the polymerization. Since the polymerization time also varies depending on various factors like the temperature, it is preferable to determine an optimum time in advance according to these conditions, but in general, the conditions are selected so that the polymerization is completed in 2 to 40 hours. Is preferred.

Of course, upon the polymerization, a release agent, an ultraviolet absorber, an antioxidant, a coloring inhibitor, an antistatic agent, a fluorescent dye, a dye,
Various stabilizers and additives such as pigments can be selected and used as needed.

In addition, since the thiocarboxylic acid ester compound of the present invention has one polymerizable group in the molecule, it is preliminarily polymerized to obtain a prepolymer and then polymerized or molded into a pellet. It is also possible to form a desired optical material using a method such as extrusion or extrusion.

As a method for obtaining the prepolymer or pellet, a known polymerization method can be employed. That is, methods such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and precipitation polymerization can be applied.

Further, the high-refractive-index resin obtained by the above method can be subjected to the following treatment depending on its use. That is, dyeing using a dye such as a disperse dye, a hard coat agent containing a silane coupling agent or a sol of an oxide such as silicon, zirconium, antimony, or aluminum as a main component, or a hard coat agent containing an organic polymer as a main component. hard Cote Ing treatment or by agent, SiO _2, TiO _2, ZrO ₂ anti-reflection treatment by coating or the like of a thin film deposition and organic polymer material of the thin film of a metal oxide such as, machining and secondary processing of antistatic treatment, etc. It is also possible to apply.

(Effect)

The resin obtained by the present invention has a high refractive index and low dispersion, has excellent transparency, weather resistance and light weight, and has extremely excellent properties such as no odor. Therefore, the high refractive index resin obtained in the present invention is useful as an organic glass, and is most suitable as an optical lens such as an eyeglass lens and an optical device lens.
It can be used for applications such as optical disk substrates and optical fibers.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

The properties of the high refractive index resin obtained in the examples were measured by the following test methods.

(1) Refractive index (no ²⁰ ), Atsube number (ν) 20 ° C using Atago Co., Ltd. Atsube refractometer (3T type)
Was measured for refractive index and Abbe number. In the contact liquid,
Bromophthalene was used.

(2) Appearance It was visually determined.

(3) Weather resistance The sample was placed in a long life xenon fade meter (FAC-25AX-HC type) manufactured by Suga Test Instruments Co., Ltd., and after exposure to xenon light for 100 hours, the degree of coloring of the sample was visually observed. Observations were made, and those with less coloring compared to polystyrene were evaluated as ○, equivalents as Δ, and those with higher coloring as X.

(4) Odor Sample pieces were judged by odor.

Those with no odor were rated as ○, those with a slight odor were rated as △, and those with a slight odor were rated as ×.

(5) Turbidity of resin Visually, no turbidity was evaluated as ○, slight turbidity, but practically no problem was evaluated as Δ, and turbidity was evaluated as ×. The compounds used in the following Examples were partially represented by the following symbols.

MSA: methyl thioacrylate MSM: methyl thiomethacrylate PSM: phenyl thiomethacrylate BSM: benzyl thiomethacrylate MSSM: 2-methylthioethyl thiomethacrylate PSSM: 2-phenylthioethyl thiomethacrylate BSSM: 2 thiomethacrylic acid -Benzylthioethyl MS ₂ SM: 2- (2-methylthioethyl) thiomethacrylate
Thioethyl BS ₂ SM: 2- (2-benzylthioethyl) thioethyl thiomethacrylate IEM: 2-isocyanatoethyl methacrylate BI: n-butyl isocyanate HMDI: hexamethylene diisocyanate TDI: tolylene diisocyanate XDI: P -Xylylene diisocyanate BiMSE: bis- (2-methacryloylthioethyl) ether BiMSS: bis- (2-methacryloylthioethyl) sulfide BiMSB: 1,3-bismethacryloylthiobenzene BiMSMB: 1,4-bis (2-methacryloyl) Thiomethyl) benzene BiMSSMB: 1,4-bis (2-methacryloylthioethylthiomethyl) benzene BBSA: 2- (2,4-dibromophenylmethylthio) ethyl thioacrylate BBMEPP: 2,2-bis (3, 5-dibromo-4-methacryloyloxyethoxyphenyl) propane St: styrene BzMA: benzyl methacrylate G BMEPP: 2,2-bis (4-methacryloyloxyethoxyphenyl) propane DEG-DMA: diethylene glycol dimethacrylate ClSt: chlorostyrene DVB: divinylbenzene PrOH: n-propanol HEMA: 2-hydroxyethyl methacrylate EGBMHPE: ethylene glycol bis [3-methacryloyloxy (2-hydroxy) propyl ether] DAT: diallyl tartrate BMHPP: 2,2-bis [4-methacryloyloxy (2-hydroxy) propoxyphenyl] propane Examples 1 to 12 Shown in Table 1 A predetermined amount of the isocyanate compound shown in Table 1 was added to 100 parts by weight of the thiocarboxylic acid ester monomer, and mixed well under a nitrogen stream. To 100 parts by weight of the thiocarboxylic acid ester monomer, 1 part by weight of t-butylperoxy-2-ethylhexanate as a radical polymerization initiator was added and mixed well. This mixture was poured into a mold composed of a glass plate and a gasket composed of an ethylene-vinyl acetate copolymer, and cast polymerization was performed. The polymerization was carried out using an air furnace at 30 ° C. to 90 ° C. for 18 hours, gradually increasing the temperature, and maintaining the temperature at 90 ° C. for 2 hours. After the polymerization was completed, the mold was taken out of the air furnace, and after standing to cool, the polymer was removed from the glass of the mold. Various physical properties of the obtained polymer were measured and are shown in Table 1.

Comparative Examples 1 to 3 The same operation was performed in Examples 2, 9, and 10 except that the isocyanate compound was not used. The results are shown in Table 1.

Examples 13 to 17 50 parts by weight of the thiocarboxylic acid ester monomer shown in Table 2 and 50 parts by weight of styrene and 0.1 part by weight of IEM were added and stirred for 1 day under a nitrogen stream. By gas chromatography analysis
The residual rate of IEM was quantified. The results are shown in Table 2.
Thereafter, 1 part by weight of t-butylperoxy-2-ethylhexanate was added as a radical polymerization initiator and mixed well. Thereafter, polymerization was carried out in the same manner as in Example 1. The physical properties of the obtained polymer were measured and are shown in Table 2.

Examples 18 to 28 100 parts by weight of a mixture of a thiocarboxylic acid ester monomer and a second monomer in the proportions shown in Table 3 were added to methacrylic acid 2-
0.1 part by weight of isocyanatoethyl (IEM) was added, and the mixture was stirred for 1 day under a nitrogen atmosphere. The residual ratio of IEM was quantified by gas chromatography analysis. The results are shown in Table 3. Thereafter, t-butyl peroxy-2-ethylhexanate 1 was added to the monomer composition as a radical polymerization initiator.
Parts by weight were added and mixed well. Thereafter, polymerization was carried out in the same manner as in Example 1. Various physical properties of the obtained polymer were measured and are shown in Table 3.

Examples 29 to 34 The thiocarboxylic acid ester monomers and isocyanate compounds shown in Table 4 were added in predetermined amounts and stirred for 5 hours under a nitrogen atmosphere. The residual ratio of the isocyanate compound was quantified by gas chromatography analysis and is shown in Table 4. Further, predetermined amounts of the alcohol compound and the second monomer shown in Table 4 were added to obtain a polymerizable composition. To 100 parts by weight of this polymerizable composition, 1 part by weight of t-butyl peroxy-2-hexanate as a radical polymerization initiator was added and mixed well. Hereinafter, it carried out exactly like Example 1. Table 4 shows the physical properties of the obtained polymer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G02B 1/04 G02B 1/04

Claims (1)

(57) [Claims] 1. A thiocarboxylic acid ester monomer having one or more acryloylthio groups or methacryloylthio groups in one molecule is polymerized in the presence of an isocyanate compound having one or more isocyanate groups in one molecule. A process for producing a high refractive index resin.