HK1170753B - Method for producing resin for optical material - Google Patents

Abstract

Disclosed is a method for adequately producing a high-performance optical material (such as a lens) composed of a polyurethane resin, which optical material is clear and colorless, while having no strain. In this method, the optical material is produced without causing cord or white turbidity by polymerizing a polymerizable composition characterized by containing 10-300 ppm of moisture and composed of a polythiol compound and a polyiso(thio)cyanate compound.

Description

Method for producing resin for optical material

The present application is a divisional application of an application having an application date of 2007, 10 and 9, and an application number of 200780034569.8, entitled "method for producing resin for optical material".

Technical Field

The present invention relates to a method for producing an optical material (such as a lens) made of a polyurethane resin having excellent optical properties by polymerizing a polymerizable composition containing a polythiol compound and a polyiso (thio) cyanate compound.

Background

Resin optical materials are lighter and less likely to be damaged than optical materials made of inorganic materials, and can be dyed. Therefore, in recent years, the optical material has rapidly spread as an optical material such as a spectacle lens and a camera lens.

Resins for optical materials are increasingly required to have higher performance. Specifically, a high refractive index, a high abbe number, a low specific gravity, a high heat resistance, and the like are required. In light of the above requirements, various resins for optical materials have been developed and used so far.

Among them, proposals for polyurethane resins have been made. The present inventors have also proposed various proposals for optical materials such as plastic lenses made of polyurethane resins.

Among the polyurethane resins, the most representative resin is a resin obtained by reacting a polythiol compound with a polyiso (thio) cyanate compound. The resin is colorless and transparent, has a high refractive index and low dispersion, and is excellent in properties such as impact resistance, dyeability and processability. Therefore, it is one of the most suitable resins for optical materials such as plastic lenses. Among them, the transparency of the resin is an essential property as a lens.

Disclosure of Invention

When a resin for an optical material is produced, a cord (cord) or white turbidity may be generated in the resin or the optical material obtained by polymerization. Such striae or cloudiness may adversely affect the performance of the optical material. That is, an object of the present invention is to provide a method for producing a high-performance urethane resin optical material (such as a lens) which is free from striae and white turbidity, is colorless and transparent, and is free from deformation.

The present inventors have conducted intensive studies to achieve the above object and, as a result, have found that the polymerization rate of the polymerizable composition and the presence or absence of cloudiness or striae of the polyurethane resin lens are closely related to the amount of water contained in the polymerizable composition.

In general, when a lens is manufactured, a suitable amount of catalyst and a suitable temperature raising mode are determined for each lens shape, whereby a transparent lens free from striae or white turbidity can be obtained with high yield. In general, when the polymerization rate is significantly lower than the normal rate, the occurrence rate of striae and white turbidity is rapidly increased, and it is known that the occurrence rate often causes deterioration of the transparency of the resin. On the other hand, the present inventors have found that when the amount of water in a polymerizable composition containing a polythiol compound and a polyiso (thio) cyanate compound exceeds a certain specific value, the polymerization rate decreases to some extent, and as a result, striae and cloudiness occur, and the yield of products may decrease. That is, by setting the amount of water in the polymerizable composition within a certain specific range, it is possible to obtain a colorless and transparent high-performance polyurethane resin lens free from turbidity and striae while suppressing the decrease in polymerization rate, and the present invention has been completed.

It is known in the prior art that when the amount of water is large, water reacts with the iso (thio) cyanate compound, the resin foams, cloudiness, and transparency is completely lost, and industrial production of the optical material becomes difficult. However, the present invention is an invention based on the correlation between the moisture content in a specific range of a very small amount (ppm level) which is considered to be no problem in industrial production, the polymerization rate, and the striae and cloudiness caused by the polymerization, which are completely different from the above-described foaming and cloudiness phenomenon caused by a large amount of moisture. The above-described relationship has been found for the first time by the present inventors and is not known in the prior art.

That is, the present invention relates to a method for producing a resin for an optical material, which is obtained by polymerizing a polymerizable composition containing a polythiol compound and a polyiso (thio) cyanate compound, and which is characterized in that the content of water is 10 to 300 ppm.

The present invention also relates to a resin obtained by the above-described production method, and an optical material such as a lens formed from the resin.

According to the present invention, a high-performance urethane resin optical material (such as a lens) which is free from striae and white turbidity, is colorless and transparent, and is free from deformation can be produced with high yield and good quality.

Detailed Description

In the present invention, the polyurethane-based resin for optical materials is produced by polymerizing the polymerizable composition containing the polythiol compound and the polyiso (thio) cyanate compound. The water content of the polymerizable composition is in the range of 10 to 300 ppm. There is no problem even if the moisture content is less than 10ppm, but it is difficult to be less than 10ppm because of moisture in the raw material polythiol, moisture contamination by a mixing operation of the polythiol compound and the iso (thio) cyanate compound in the production process, and the like. Further, the water content of the polymerizable composition is preferably 10 to 200 ppm.

In order to make the water content 10 to 300ppm, it is necessary to reduce the water content as much as possible in the monomer production stage. For example, when a solvent is used in the production of a monomer, the amount of water can be reduced simultaneously with the removal of the solvent by azeotropy with water. Further, the amount of water remaining in the system can be reduced by introducing nitrogen gas under reduced pressure, at room temperature or under heating. In addition, when distillation purification or the like is used, the amount of water in the monomer can be reduced by adjusting the amount of fraction in the initial product. Further, the produced monomer is stored in a nitrogen atmosphere, and the moisture content can be maintained at a low level by preventing the moisture content from increasing due to moisture absorption or the like after the production of the monomer.

In the present invention, it is important not only to reduce the amount of water in the monomer or polymerizable composition by the above-mentioned methods, but also to determine whether the monomer or polymerizable composition can be used for polymerization by examining and measuring the water content of the monomer or polymerizable composition. That is, as a result of the examination measurement, when the water content is within the range defined in the present invention, the monomer or polymerizable composition can be used for polymerization, and when the water content is out of the range, the monomer or polymerizable composition is not used for polymerization, and further treated to reduce the water content, and then the examination measurement is performed again to determine whether the monomer or polymerizable composition can be used for polymerization.

When the water content of the polymerizable composition is within the above-mentioned specific range, a transparent polyurethane resin optical material free from striae or cloudiness can be obtained without causing a significant decrease in polymerization rate. The polythiol compound used in the polymerizable composition preferably has a water content of 20 to 600ppm, and more preferably 20 to 400ppm from the viewpoint of suppressing striae and white turbidity. The moisture content can be measured using a karl fischer moisture meter.

The polymerizable composition is a composition mainly containing a polythiol compound and a polyiso (thio) cyanate compound. In addition, if necessary, any component such as a catalyst, an internal mold release agent, a UV absorber, a bluing agent, and the like may be contained.

For example, the polyurethane-based lens can be produced by injecting a polythiol compound, a polyiso (thio) cyanate compound, and optional components as required into a mold for a lens, and polymerizing the compounds.

The polyisocyanate (thio) cyanate compound used in the polymerizable composition is not particularly limited, and may be a compound having 2 or more isocyanate (thio) cyanate groups in one molecule. The "iso (thio) cyanate" means "isocyanate or isothiocyanate".

Specific examples of the polyisocyanate compound include aliphatic polyisocyanate compounds such as 1, 6-hexamethylene diisocyanate, 2-dimethylpentanedioic acid diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, butene diisocyanate, 1, 3-butadiene-1, 4-diisocyanate, 2, 4, 4-trimethyl-1, 6-hexamethylene diisocyanate, 1, 6, 11-undecane triisocyanate, 1, 3, 6-hexamethylene triisocyanate, 1, 8-diisocyanato-4-isocyanatomethyloctane, bis (isocyanatoethyl) carbonate, bis (isocyanatoethyl) ether, lysine methyl diisocyanate, and lysine triisocyanate;

alicyclic polyisocyanate compounds such as 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane diisocyanate and isophorone diisocyanate;

1, 2-diisocyanatobenzene, 1, 3-diisocyanatobenzene, 1, 4-diisocyanatobenzene, 2, 4-diisocyanatotoluene, ethylbenzene diisocyanate, isopropylbenzene diisocyanate, dimethylbenzene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, trimethylbenzene triisocyanate, benzene triisocyanate, biphenyl diisocyanate, toluidine diisocyanate, 4 ' -methylenebis (phenyl isocyanate), 4 ' -methylenebis (2-methylphenyl isocyanate), bibenzyl-4, 4 ' -diisocyanate, bis (isocyanatophenyl) ethylene, bis (isocyanatomethyl) benzene, bis (isocyanatoethyl) benzene, bis (isocyanatopropyl) benzene, α, α, α ', α ' -tetramethylxylylene diisocyanate, Polyisocyanate compounds having aromatic ring compounds such as bis (isocyanatobutyl) benzene, bis (isocyanatomethyl) naphthalene, bis (isocyanatomethyl phenyl) ether, bis (isocyanatoethyl) phthalate, and 2, 6-bis (isocyanatomethyl) furan;

bis (isocyanatomethyl) sulfide, bis (isocyanatoethyl) sulfide, bis (isocyanatopropyl) sulfide, bis (isocyanatohexyl) sulfide, bis (isocyanatomethyl) sulfone, bis (isocyanatomethyl) disulfide, bis (isocyanatoethyl) disulfide, bis (isocyanatopropyl) disulfide, bis (isocyanatomethylthio) methane, bis (isocyanatoethylthio) methane, bis (isocyanatomethylthio) ethane, bis (isocyanatoethylthio) ethane, 1, 5-diisocyanato-2-isocyanatomethyl-3-thiapentane, 1, 2, 3-tris (isocyanatomethylthio) propane, 1, 2, 3-tris (isocyanatoethylthio) propane, 3, 5-dithia-1, 2, 6, 7-heptane tetraisocyanate, Sulfur-containing aliphatic polyisocyanate compounds such as 2, 6-diisocyanatomethyl-3, 5-dithia-1, 7-heptane diisocyanate, 2, 5-diisocyanatomethylthiophene, diisocyanatoethylthio-2, 6-dithia-1, 8-octane diisocyanate;

aromatic thioether polyisocyanate compounds such as 2-isocyanatophenyl-4-isocyanatophenyl sulfide, bis (4-isocyanatophenyl) sulfide and bis (4-isocyanatomethylphenyl) sulfide;

aromatic disulfide polyisocyanate compounds such as bis (4-isocyanatophenyl) disulfide, bis (2-methyl-5-isocyanatophenyl) disulfide, bis (3-methyl-6-isocyanatophenyl) disulfide, bis (4-methyl-5-isocyanatophenyl) disulfide and bis (4-methoxy-3-isocyanatophenyl) disulfide;

sulfur-containing alicyclic polyisocyanate compounds such as 2, 5-diisocyanatotetrahydrothiophene, 2, 5-diisocyanatomethyltetrahydrothiophene, 3, 4-diisocyanatomethyltetrahydrothiophene, 2, 5-diisocyanato-1, 4-dithiane, 2, 5-diisocyanatomethyl-1, 4-dithiane, 4, 5-diisocyanato-1, 3-dithiolane, 4, 5-bis (isocyanatomethyl) -1, 3-dithiolane and 4, 5-diisocyanatomethyl-2-methyl-1, 3-dithiolane;

aliphatic polyisothiocyanate compounds such as 1, 2-diisothiocyanate ethane and 1, 6-diisothiocyanate hexane; alicyclic polyisothiocyanate compounds such as cyclohexane diisothiocyanate; aromatic polyisothiocyanate compounds such as 1, 2-diisothiocyanate-benzene, 1, 3-diisothiocyanate-benzene, 1, 4-diisothiocyanate-benzene, 2, 4-diisothiocyanate-toluene, 2, 5-diisothiocyanate-m-xylene, 4 '-methylenebis (phenyl isothiocyanate), 4' -methylenebis (2-methylphenyl isothiocyanate), 4 '-methylenebis (3-methylphenyl isothiocyanate), 4' -diisothiocyanate-benzophenone, 4 '-diisothiocyanate-3, 3' -dimethyl benzophenone, bis (4-isothiocyanatophenyl) ether and the like;

carbonyl polyisothiocyanate compounds such as 1, 3-benzenedicarbonyl diisothiocyanate, 1, 4-benzenedicarbonyl diisothiocyanate, and (2, 2-pyridine) -4, 4-dicarbonyl diisothiocyanate; sulfur-containing aliphatic polyisothiocyanate compounds such as thiobis (3-isothiocyanatopropane), thiobis (2-isothiocyanatoethane) and dithiobis (2-isothiocyanatoethane);

sulfur-containing aromatic polyisothiocyanate compounds such as 1-isothiocyanato-4- [ (2-isothiocyanato) sulfonyl ] benzene, thiobis (4-isothiocyanatobenzene), sulfonyl (4-isothiocyanatobenzene), dithiobis (4-isothiocyanatobenzene) and the like; sulfur-containing alicyclic polyisothiocyanate compounds such as 2, 5-diisothiocyanatothiophene and 2, 5-diisothiocyanato1, 4-dithiane;

polyisocyanate (thio) cyanate compounds having an isocyanate group and an isothiocyanate group, such as 1-isocyanato-6-isothiocyanatohexane, 1-isocyanato-4-isothiocyanatobenzene, 4-methyl-3-isocyanato-1-isothiocyanatobenzene, 2-isocyanato-4, 6-diisothiocyanato-1, 3, 5-triazine, 4-isocyanatophenyl-4-isothiocyanatophenylthioether, and 2-isocyanato-2-isothiocyanatoethyldisulfide.

Further, halogen-substituted compounds such as chlorine-substituted compounds and bromine-substituted compounds, alkyl-substituted compounds, alkoxy-substituted compounds, nitro-substituted compounds, prepolymer-type modified products with polyhydric alcohols, carbodiimide-modified products, urea-modified products, biuret-modified products, dimerization or trimerization reaction products, and the like can be used.

However, the polyiso (thio) cyanate compound is not limited to the above-mentioned compounds. The above-mentioned compounds may be used alone or in combination of 2 or more.

Among the above-mentioned compounds, at least 1 kind of alicyclic isocyanate compound is particularly preferably used. In addition, as the alicyclic isocyanate compound, it is preferable to use at least 1 compound selected from the group consisting of 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane diisocyanate and isophorone diisocyanate.

The polythiol compound used in the polymerizable composition is not particularly limited, and may be a compound having 2 or more thiol groups in one molecule.

Specific examples of the polythiol compound include methanedithiol, 1, 2-ethanedithiol, 1-propanedithiol, 1, 2-propanedithiol, 1, 3-propanedithiol, 2-propanedithiol, 1, 6-hexanedithiol, 1, 2, 3-propanetrithiol, 1-cyclohexanedithiol, 1, 2-cyclohexanedithiol, 2-dimethylpropane-1, 3-dithiol, 3, 4-dimethoxybutane-1, 2-dithiol, 2-methylcyclohexane-2, 3-dithiol, 1-bis (mercaptomethyl) cyclohexane, bis (2-mercaptoethyl) thiomalate, 2, 3-dimercapto-1-propanol (2-mercaptoacetate), 2, 3-dimercapto-1-propanol (3-mercaptopropionate), diethylene glycol bis (2-mercaptoacetate), diethylene glycol bis (3-mercaptopropionate), 1, 2-dimercaptopropyl methyl ether, 2, 3-dimercaptopropyl methyl ether, 2-bis (mercaptomethyl) -1, 3-propanedithiol, bis (2-mercaptoethyl) ether, aliphatic polythiol compounds such as ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), trimethylolpropane bis (2-mercaptoacetate), trimethylolpropane bis (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), and tetrakis (mercaptomethyl) methane;

1, 2-dimercaptobenzene, 1, 3-dimercaptobenzene, 1, 4-dimercaptobenzene, 1, 2-bis (mercaptomethyl) benzene, 1, 3-bis (mercaptomethyl) benzene, 1, 4-bis (mercaptomethyl) benzene, 1, 2-bis (mercaptoethyl) benzene, 1, 3-bis (mercaptoethyl) benzene, 1, 4-bis (mercaptoethyl) benzene, 1, 2, 3-trimercaptobenzene, 1, 2, 4-trimercaptobenzene, 1, 3, 5-trimercaptobenzene, 1, 2, 3-tris (mercaptomethyl) benzene, 1, 2, 4-tris (mercaptomethyl) benzene, 1, 3, 5-tris (mercaptomethyl) benzene, 1, 2, 3-tris (mercaptoethyl) benzene, 1, 2, 4-tris (mercaptoethyl) benzene, 1, 3, 5-tris (mercaptoethyl) benzene, Aromatic polythiol compounds such as 2, 5-methanedithiol, 3, 4-methanedithiol, 1, 3-di (p-methoxyphenyl) propane-2, 2-dithiol, 1, 3-diphenylpropane-2, 2-dithiol, phenylmethane-1, 1-dithiol, and 2, 4-di (p-mercaptophenyl) pentane;

aromatic polythiol compounds containing a sulfur atom in addition to a mercapto group, such as 1, 2-bis (mercaptoethylthio) benzene, 1, 3-bis (mercaptoethylthio) benzene, 1, 4-bis (mercaptoethylthio) benzene, 1, 2, 3-tris (mercaptomethylthio) benzene, 1, 2, 4-tris (mercaptomethylthio) benzene, 1, 3, 5-tris (mercaptomethylthio) benzene, 1, 2, 3-tris (mercaptoethylthio) benzene, 1, 2, 4-tris (mercaptoethylthio) benzene, 1, 3, 5-tris (mercaptoethylthio) benzene, and nuclear alkylated compounds thereof;

bis (mercaptomethyl) sulfide, bis (mercaptomethyl) disulfide, bis (mercaptoethyl) sulfide, bis (mercaptoethyl) disulfide, bis (mercaptopropyl) sulfide, bis (mercaptomethylthio) methane, bis (2-mercaptoethylthio) methane, bis (3-mercaptopropylthio) methane, 1, 2-bis (mercaptomethylthio) ethane, 1, 2-bis (2-mercaptoethylthio) ethane, 1, 2-bis (3-mercaptopropyl) ethane, 1, 3-bis (mercaptomethylthio) propane, 1, 3-bis (2-mercaptoethylthio) propane, 1, 3-bis (3-mercaptopropylthio) propane, 1, 2, 3-tris (mercaptomethylthio) propane, 1, 2, 3-tris (2-mercaptoethylthio) propane, 1, 2, 3-tris (3-mercaptopropylthio) propane, bis (mercaptopropyl) sulfide, bis (mercaptoethylthio) ethane, bis (mercaptoethylthio) propane, bis (mercapto, 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane, 4, 8-dimercaptomethyl-1, 11-dimercapto-3, 6, 9-trithioundecane, 4, 7-dimercaptomethyl-1, 11-dimercapto-3, 6, 9-trithioundecane, 5, 7-dimercaptomethyl-1, 11-dimercapto-3, 6, 9-trithioundecane, bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol, tetrakis (mercaptomethylthiomethyl) methane, tetrakis (2-mercaptoethylthiomethyl) methane, tetrakis (3-mercaptopropylthiomethyl) methane, bis (2, 3-dimercaptopropyl) sulfide, and mixtures thereof, Aliphatic polythiol compounds containing a sulfur atom other than a mercapto group, such as bis (1, 3-dimercaptopropyl) sulfide, 2, 5-dimercapto-1, 4-dithiane, 2, 5-dimercaptomethyl-2, 5-dimethyl-1, 4-dithiane, bis (mercaptomethyl) disulfide, bis (mercaptoethyl) disulfide, and bis (mercaptopropyl) disulfide, and esters of thioglycolic acid and mercaptopropionic acid thereof;

hydroxymethyl sulfide bis (2-mercaptoacetate), hydroxymethyl sulfide bis (3-mercaptopropionate), hydroxyethyl sulfide bis (2-mercaptoacetate), hydroxyethyl sulfide bis (3-mercaptopropionate), hydroxypropyl sulfide bis (2-mercaptoacetate), hydroxypropyl sulfide bis (3-mercaptopropionate), hydroxymethyl disulfide bis (2-mercaptoacetate), hydroxymethyl disulfide bis (3-mercaptopropionate), hydroxyethyl disulfide bis (2-mercaptoacetate), hydroxyethyl disulfide bis (3-mercaptopropionate), hydroxypropyl disulfide bis (2-mercaptoacetate), hydroxypropyl disulfide bis (3-mercaptopropionate), 2-mercaptoethyl ether bis (2-mercaptoacetate), 2-mercaptoethyl ether bis (3-mercaptopropionate), 1, 4-dithiane-2, 5-diol bis (2-mercaptoacetate), 1, 4-dithiane-2, 5-diol bis (3-mercaptopropionate), dithiodiacetic acid bis (2-mercaptoethyl ester), thiodipropionic acid bis (2-mercaptoethyl ester), 4-thiodibutanoic acid bis (2-mercaptoethyl ester), dithiodiacetic acid bis (2-mercaptoethyl ester), dithiodipropionic acid bis (2-mercaptoethyl ester), 4-dithiodibutanoic acid bis (2-mercaptoethyl ester), thiodiacetic acid bis (2, 3-dimercaptopropyl ester), thiodipropionic acid bis (2, 3-dimercaptopropyl ester), dithiodiacetic acid bis (2, 3-dimercaptopropyl ester), Aliphatic polythiol compounds containing a sulfur atom and an ester bond in addition to a mercapto group, such as bis (2, 3-dimercaptopropyl) dithiodipropionate;

heterocyclic compounds containing a sulfur atom in addition to a mercapto group, such as 3, 4-thiophenedithiol, 2, 5-dimercapto-1, 3, 4-thiadiazol, and the like;

2-mercaptoethanol, 3-mercapto-1, 2-propanediol, glycerol di (mercaptoacetate), 1-hydroxy-4-mercaptocyclohexane, 2, 4-dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 3, 4-dimercapto-2-propanol, 1, 3-dimercapto-2-propanol, 2, 3-dimercapto-1-propanol, 1, 2-dimercapto-1, 3-butanediol, pentaerythritol tris (3-mercaptopropionate), pentaerythritol mono (3-mercaptopropionate), pentaerythritol bis (3-mercaptopropionate), pentaerythritol tris (mercaptoacetate), dipentaerythritol penta (3-mercaptopropionate), hydroxymethyl-tris (mercaptoethylthiomethyl) methane, glycerol di (mercaptoacetate), glycerol di (mercaptophenol, 2-dimercaptophenol, 2-mercaptohydroquinone, 4-dimercaptophenol, 3, 4-dimercapto, Compounds containing a hydroxyl group other than a mercapto group, such as 1-hydroxyethylthio-3-mercaptoethylthiobenzene;

1, 1, 3, 3-tetrakis (mercaptomethylthio) propane, 1, 2, 2-tetrakis (mercaptomethylthio) ethane, 4, 6-bis (mercaptomethylthio) -1, 3-dithiacyclohexane, 1, 5, 5-tetrakis (mercaptomethylthio) -3-thiapentane, 1, 6, 6-tetrakis (mercaptomethylthio) -3, 4-dithiahexane, 2, 2-bis (mercaptomethylthio) ethanethiol, 2- (4, 5-dimercapto-2-thiapentyl) -1, 3-dithiacyclopentane, 2, 2-bis (mercaptomethyl) -1, 3-dithiacyclopentane, 2, 5-bis (4, 4-bis (mercaptomethylthio) -2-thiabutyl) -1, 4-dithiane, 2-bis (mercaptomethylthio) -1, 3-propanedithiol, 3-mercaptomethylthio-1, 7-dimercapto-2, 6-dithiaheptane, 3, 6-bis (mercaptomethylthio) -1, 9-dimercapto-2, 5, 8-trithianonane, 4, 6-bis (mercaptomethylthio) -1, 9-dimercapto-2, 5, 8-trithianonane, 3-mercaptomethylthio-1, 6-dimercapto-2, 5-dithiahexane, 2- (2, 2-bis (mercaptomethylthio) ethyl) -1, 3-dithiacyclobutane, 1, 9, 9-tetrakis (mercaptomethylthio) -5- (3, 3-bis (mercaptomethylthio) -1-thioisopropyl) 3, 7-dithianonane, tris (2, 2-bis (mercaptomethylthio) ethyl) methane, tris (4, 4-bis (mercaptomethylthio) -2-thiobutyl) methane, tetrakis (2, 2-bis (mercaptomethylthio) ethyl) methane, tetrakis (4, 4-bis (mercaptomethylthio) -2-thiobutyl) methane, 3, 5, 9, 11-tetrakis (mercaptomethylthio) -1, 13-dimercapto-2, 6, 8, 12-tetrathiatridecane, 3, 5, 9, 11, 15, 17-hexa (mercaptomethylthio) -1, 19-dimercapto-2, 6, 8, 12, 14, 18-hexathianonadecane, 9- (2, 2-bis (mercaptomethylthio) ethyl) -3, 5, 13, 15-tetrakis (mercaptomethylthio) -1, 17-dimercapto-2, 6, 8, 10, 12, 16-hexakis (mercaptomethylthio) -1, 11-dimercapto-2, 5, 7, 10-tetrathiaundecane, 3, 4, 8, 9, 13, 14-hexakis (mercaptomethylthio) -1, 16-dimercapto-2, 5, 7, 10, 12, 15-hexathiahexadecane, 8- { bis (mercaptomethylthio) methyl } -3, 4, 12, 13-tetrakis (mercaptomethylthio) -1, 15-dimercapto-2, 5, 7, 9, 11, 14-hexathiapentadecane, 4, 6-bis {3, 5-bis (mercaptomethylthio) -7-mercapto-2, 6-dithiaheptylthio } -1, 3-dithiane, 4- {3, 5-bis (mercaptomethylthio) -7-mercapto-2, 6-dithiaheptylthio } -6-mercaptomethylthio-1, 3-dithiane, 1-bis {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -3, 3-bis (mercaptomethylthio) propane, 1, 3-bis {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -1, 3-bis (mercaptomethylthio) propane, 1- {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -3- {2, 2-bis (mercaptomethylthio) ethyl } -7, 9-bis (mercaptomethylthio) -2, 4, 6, 10-tetrathiaundecane, 1- {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -3- {2- (1, 3-dithiocyclobutyl) } methyl-7, 9-bis (mercaptomethylthio) -2, 4, 6, 10-tetrathiaundecane, 1, 5-bis {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -3- {2- (1, 3-dithiocyclobutyl) } methyl-2, 4-dithiane, a, 4, 6-bis [3- {2- (1, 3-dithiocyclobutyl) } methyl-5-mercapto-2, 4-dithiopentylthio ] -1, 3-dithiane, 4, 6-bis {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -1, 3-dithiane, 4- {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -6- {4- (6-mercaptomethylthio) -1, 3-dithianylthio } -1, 3-dithiane, 3- {2- (1, 3-dithiocyclobutyl) } methyl-7, 9-bis (mercaptomethylthio) -1, 11-dimercapto-2, 4, 6, 10-tetrathiaundecane, 9- {2- (1, 3-dithiocyclobutyl) } methyl-3, 5, 13, 15-tetrakis (mercaptomethylthio) -1, 17-dimercapto-2, 6, 8, 10, 12, 16-hexathiaheptadecane, 3- {2- (1, 3-dithiocyclobutyl) } methyl-7, 9, 13, 15-tetrakis (mercaptomethylthio) -1, 17-dimercapto-2, 4, 6, 10, 12, 16-hexathiaheptadecane, 3, 7-bis {2- (1, 3-dithiocyclobutyl) } methyl-1, 9-dimercapto-2, 4, 6, 8-tetrathianonane, 4- {3, 4, 8, 9-tetrakis (mercaptomethylthio) -11-mercapto-2, 5, 7, 10-tetrathiaundecyl } -5-mercaptomethylthio-1, 3-dithiolane, 4, 5-bis {3, 4-bis (mercaptomethylthio) -6-mercapto-2, 5-dithiahexylthio } -1, 3-dithiolane, 4- {3, 4-bis (mercaptomethylthio) -6-mercapto-2, 5-dithiahexylthio } -5-mercaptomethylthio-1, 3-dithiolane, 4- { 3-bis (mercaptomethylthio) methyl-5, 6-bis (mercaptomethylthio) -8-mercapto-2, 4, 7-trithio-octyl } -5-mercapto-methylthio-1, 3-dithiolane, 2- [ bis {3, 4-bis (mercaptomethylthio) -6-mercapto-2, 5-dithiahexylthio } methyl ] -1, 3-dithiolane, 2- {3, 4-bis (mercaptomethylthio) -6-mercapto-2, 5-dithiahexylthio } mercaptomethylthiomethyl-1, 3-dithiolane, 2- {3, 4, 8, 9-tetrakis (mercaptomethylthio) -11-mercapto-2, 5, 7, 10-tetrathiaundecylthio } mercaptomethylthiomethyl-1, 3-dithiolane, 2- { 3-bis (methylthio) methyl-5, 6-bis (mercaptomethylthio) -8-mercapto-2, 4, 7-trithio-heteroctyl } mercaptomethylthiomethyl-1, 3-dithiolane, 4, 5-bis [1- {2- (1, 3-dithiolane-butyl) } -3-mercapto-2-thiolpropylthio ] -1, 3-dithiolane, 4- [1- {2- (1, 3-dithiolane-butyl) } -3-mercapto-2-thiolpropylthio ] -5- {1, 2-bis (mercaptomethylthio) -4-mercapto-3-thiolbutylthio } -1, 3-dithiolane, 2- [ bis {4- (5-mercaptomethylthio-1, 3-dithiolanyl) thio } ] methyl-1, 3-dithiolane, 4- {4- (5-mercaptomethylthio-1, 3-dithiolanyl) thio } -5- [1- {2- (1, 3-dithiocyclobutyl) } -3-mercapto-2-thiolpropylthio ] -1, 3-dithiolane, and compounds having a dithioacetal (dithioacetal) or dithioketal (dithioketal) skeleton such as oligomers thereof;

tris (mercaptomethylthio) methane, tris (mercaptoethylthio) methane, 1, 5, 5-tetrakis (mercaptomethylthio) -2, 4-dithiapentane, bis (4, 4-bis (mercaptomethylthio) -1, 3-dithiabutyl) (mercaptomethylthio) methane, tris (4, 4-bis (mercaptomethylthio) -1, 3-dithiabutyl) methane, 2, 4, 6-tris (mercaptomethylthio) -1, 3, 5-trithiacyclohexane, 2, 4-bis (mercaptomethylthio) -1, 3, 5-trithiacyclohexane, 1, 3, 3-tetrakis (mercaptomethylthio) -2-thiapropane, bis (mercaptomethyl) methylthio-1, 3, 5-trithiacyclohexane, tris ((4-mercaptomethyl-2, 5-dithiacyclohexyl-1-yl) methylthio) methane, 2, 4-bis (mercaptomethylthio) -1, 3-dithiolane, 2-mercaptoethylthio-4-mercaptomethyl-1, 3-dithiolane, 2- (2, 3-dimercaptopropylthio) -1, 3-dithiolane, 4-mercaptomethyl-2- (1, 3-dimercapto-2-propylthio) -1, 3-dithiolane, tris (2, 2-bis (mercaptomethylthio) -1-thioethyl) methane, tris (3), compounds having a trithioorthoformate (ortho trithioform) skeleton such as 3-bis (mercaptomethylthio) -2-thioisopropyl) methane, tris (4, 4-bis (mercaptomethylthio) -3-thiobutyl) methane, 2, 4, 6-tris (3, 3-bis (mercaptomethylthio) -2-thioisopropyl) -1, 3, 5-trithio-cyclohexane, tetrakis (3, 3-bis (mercaptomethylthio) -2-thioisopropyl) methane, and oligomers thereof;

and compounds having a tetrathioorthocarbonate skeleton such as 3, 3 '-bis (mercaptomethylthio) -1, 5-dimercapto-2, 4-dithiolane, 2' -bis (mercaptomethylthio) -1, 3-dithiolane, 2, 7-bis (mercaptomethyl) -1, 4, 5, 9-tetrathiospiro [4, 4] nonane, 3, 9-dimercapto-1, 5, 7, 11-tetrathiospiro [5, 5] undecane, and oligomers thereof.

However, the polythiol compound is not limited to the above-mentioned compounds. The above-mentioned compounds may be used alone or in combination of 2 or more.

Among the above-mentioned compounds, it is particularly preferable to use at least 1 polythiol compound selected from the group consisting of 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane, bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol, pentaerythritol tetrakis (3-mercaptopropionate), 1, 3, 3-tetrakis (mercaptomethylthio) propane and 2-mercaptoethanol.

The ratio of the polythiol compound to the polyiso (thio) cyanate compound is usually in the range of 0.5 to 3.0, preferably 0.6 to 2.0, and more preferably 0.8 to 1.3 for SH group/NCO group.

In order to improve the physical properties, workability, polymerization reactivity, and the like of the polyurethane resin, in addition to the polythiol compound and the iso (thio) cyanate compound forming the polyurethane resin, 1 or more compounds other than the polyurethane-forming raw material, such as an active hydrogen compound represented by amine or the like, an epoxy compound, an olefin compound, a carbonate compound, an ester compound, a metal oxide, an organic metal compound, an inorganic substance, and the like, may be added.

In addition, various substances such as a chain extender, a crosslinking agent, a light stabilizer, an ultraviolet absorber, an antioxidant, an oil-soluble dye, a filler, a mold release agent, and a bluing agent may be added in the same manner as in a known molding method depending on the purpose. In order to adjust the reaction rate to a desired level, S-alkyl thiocarbamates and known reaction catalysts used in the production of polyurethanes may be added as appropriate.

Optical materials formed from polyurethane-based resins are generally produced by injection polymerization. Specifically, a polythiol compound and a polyiso (thio) cyanate compound are mixed. This mixed solution (polymerizable composition) is deaerated by an appropriate method if necessary, and then injected into an injection mold for an optical material, and usually heated from a low temperature to a high temperature gradually to polymerize the same. Then, the optical material was obtained by demolding.

The polyurethane resin produced by the method of the present invention has the characteristics of high refractive index, low dispersion, excellent heat resistance and durability, light weight, excellent impact resistance, and excellent color tone. Therefore, the resin is suitable for use in optical materials such as lenses and prisms. Particularly well suited for lens applications such as spectacle lenses, camera lenses, etc.

In addition, in order to improve the antireflection, the high hardness, the abrasion resistance, the chemical resistance, the antifogging property, the fashionability, and the like, the optical material may be subjected to physical and chemical treatments such as surface polishing, antistatic treatment, hard coating treatment, non-reflective coating treatment, dyeing treatment, light control treatment, and the like, as necessary.

The optical material of the present invention made of a polyurethane resin is characterized by having very little striae or white turbidity. That is, the optical material of the present invention is characterized by excellent properties and being capable of being produced with high yield. Specifically, 100 sheets of optical materials were visually observed under a high-pressure mercury lamp, and when a streak was observed, it was judged that there was a streak, and when turbidity was observed, it was judged that there was white turbidity.

Examples

The present invention will be described in detail with reference to examples. The water content and polymerization rate in the polymerizable composition and the striae/white turbidity formation rate of the resin were evaluated by the following methods. In the following description, "part" means "part by mass".

Moisture content: measured using a Karl Fischer moisture tester. Specifically, KF-100 manufactured by Mitsubishi chemical was used as an automatic moisture measuring device, and VA-100 (with a switchboard (board)) manufactured by Mitsubishi chemical was used as a moisture vaporizing device.

Polymerization rate: the evaluation was carried out using the viscosity after 7 hours as an index, 0 hour at the time of preparing the polymerizable composition.

Incidence of cord: the term "rib" refers to a phenomenon in which the refractive index is locally different from the normal refractive index of the surroundings due to a difference in composition or the like. In this example, 100 lenses were visually observed under a high-pressure mercury lamp, and the streak-like lens was confirmed to be a lens having striae, and the striae occurrence rate was calculated.

White turbidity incidence: the 100 lenses were visually observed under a high-pressure mercury lamp, and the lens for which clouding was confirmed was determined to be a lens having cloudiness, and the cloudiness occurrence rate was calculated.

[ example 1]

(measurement of viscosity of polymerizable composition)

60 parts of dicyclohexylmethane diisocyanate, 0.05 part of dimethyltin dichloride as a curing catalyst, 0.10 part of an acid phosphate (product name: Zelec UN, manufactured by Stepan Co., Ltd.), and 0.05 part of an ultraviolet absorber (product name: BioSorb583, manufactured by Kyowa Co., Ltd.) were mixed and dissolved at 10 to 15 ℃. Further, 40 parts of a polythiol containing 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane as a main component was added and mixed to form a homogeneous mixed liquid (polymerizable composition). The polythiol used had a moisture content of 50ppm and the polymerizable composition had a moisture content of 20 ppm. The viscosity after 7 hours was measured for 0 hour when the homogeneous mixed solution was prepared. The results are shown in Table 1.

(production of Plastic lens)

60 parts of dicyclohexylmethane diisocyanate, 0.05 part of dimethyltin dichloride as a curing catalyst, 0.10 part of acidic phosphate ester (Zelec UN) and 0.05 part of ultraviolet absorber (BioSorb583) were mixed and dissolved at 10 to 15 ℃. Further, 40 parts of a polythiol containing 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane as a main component was added and mixed to form a homogeneous mixed liquid (polymerizable composition). The polythiol used had a moisture content of 50ppm and the polymerizable composition had a moisture content of 20 ppm. The homogeneous mixture was degassed at 600Pa for 1 hour, and then filtered through a 1 μm PTFE (polytetrafluoroethylene) filter. Then, the mixture was injected into an injection mold for a lens, which was composed of a glass mold having a diameter of 75mm, 4D and an adhesive tape. The injection mould was placed in an oven and held at 40 ℃ for 2 hours, heated to 50 ℃ for 2 hours over 4 hours and heated to 60 ℃ for 2 hours over 3 hours. The temperature was raised to 70 ℃ for another 3 hours and held for 2 hours, to 100 ℃ for another 3 hours, and to 130 ℃ for another 1 hour and held for 2 hours. As described above, the polymerization was carried out at a temperature ranging from 40 ℃ to 130 ℃ for a total of 24 hours. And after the polymerization is finished, taking the injection mold out of the oven, and demolding to obtain the lens. The resulting lens was then annealed at 120 ℃ for 3 hours. As described above, 100 lenses were produced, and the striae incidence and the white turbidity incidence were calculated. The results are shown in Table 1.

[ example 2]

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 1 except that the polymerizable composition having a moisture content of 100ppm was used instead of the polymerizable composition used in example 1. The results are shown in Table 1.

[ example 3]

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 1 except that the polymerizable composition having a moisture content of 200ppm was used instead of the polymerizable composition used in example 1. The results are shown in Table 1.

[ example 4]

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 1 except that the polymerizable composition having a moisture content of 300ppm was used instead of the polymerizable composition used in example 1. The results are shown in Table 1.

[ example 5]

(measurement of viscosity of polymerizable composition)

50.6 parts of a mixture of 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane and 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 0.06 part of dibutyltin dichloride as a curing catalyst, 0.12 part of acidic phosphate ester (Zelec UN), and 0.05 part of an ultraviolet absorber (BioSorb583) were mixed and dissolved at 10 to 15 ℃. Further, 25.5 parts of polythiol containing 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane as a main component and 23.9 parts of pentaerythritol tetrakis (mercaptopropionate) were added and mixed to form a homogeneous mixture (polymerizable composition). The polythiol mainly composed of 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane used had a moisture content of 40ppm, the pentaerythritol tetrakis (mercaptopropionate) had a moisture content of 20ppm, and the polymerizable composition had a moisture content of 15 ppm. The viscosity after 7 hours was measured for 0 hour when the homogeneous mixed solution was prepared. The results are shown in Table 1.

(production of Plastic lens)

50.6 parts of a mixture of 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane and 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 0.06 part of dibutyltin dichloride as a curing catalyst, 0.12 part of acidic phosphate ester (Zelec UN), and 0.05 part of an ultraviolet absorber (BioSorb583) were mixed and dissolved at 10 to 15 ℃. Further, 25.5 parts of polythiol containing 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane as a main component and 23.9 parts of pentaerythritol tetrakis (mercaptopropionate) were added and mixed to form a homogeneous mixture (polymerizable composition). The polythiol mainly composed of 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane used had a moisture content of 40ppm, the pentaerythritol tetrakis (mercaptopropionate) had a moisture content of 20ppm, and the polymerizable composition had a moisture content of 15 ppm. This homogeneous mixture was degassed under 600Pa for 1 hour, and then filtered through a 1. mu. mTFE filter. Then, the mixture was injected into an injection mold for a lens comprising a glass mold having a diameter of 75mm and 4D and an adhesive tape. The injection mould was placed in an oven and held at 40 ℃ for 2 hours, heated to 50 ℃ for 2 hours over 4 hours and heated to 60 ℃ for 2 hours over 3 hours. The temperature was raised to 70 ℃ for another 3 hours and held for 2 hours, to 100 ℃ for another 3 hours, and to 130 ℃ for another 1 hour and held for 2 hours. As mentioned above, polymerization was carried out at a temperature ranging from 40 ℃ to 130 ℃ for a total of 24 hours. And after the polymerization is finished, taking the injection mold out of the oven, and demolding to obtain the lens. The resulting lens was then annealed at 120 ℃ for 3 hours. The 100 lenses were produced as described above, and the striae incidence and the white turbidity incidence were calculated. The results are shown in Table 1.

[ example 6]

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 5 except that the polymerizable composition having a moisture content of 150ppm was used instead of the polymerizable composition used in example 5. The results are shown in Table 1.

[ example 7]

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 5 except that the polymerizable composition having a moisture content of 300ppm was used instead of the polymerizable composition used in example 5. The results are shown in Table 1.

[ example 8]

(measurement of viscosity of polymerizable composition)

A mixture of 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane and 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane (49.7 parts), dibutyltin dichloride (0.03 part) as a curing catalyst, acidic phosphate (Zelec UN) (0.12 part), and an ultraviolet absorber (BioSorb583) (0.05 part) were mixed and dissolved at 10 to 15 ℃. Further, 25.9 parts of polythiol containing bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol as a main component and 24.4 parts of pentaerythritol tetrakis (mercaptopropionate) were added and mixed to form a homogeneous mixed liquid (polymerizable composition). The polythiol mainly composed of bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol was used at a moisture content of 70ppm, pentaerythritol tetrakis (mercaptopropionate) at a moisture content of 20ppm, and the polymerizable composition at a moisture content of 21 ppm. The viscosity after 7 hours was measured for 0 hour when the homogeneous mixed solution was prepared. The results are shown in Table 1.

(production of Plastic lens)

50.6 parts of a mixture of 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane and 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 0.06 part of dibutyltin dichloride as a curing catalyst, 0.12 part of acidic phosphate ester (Zelec UN), and 0.05 part of an ultraviolet absorber (BioSorb583) were mixed and dissolved at 10 to 15 ℃. Further, 25.5 parts of polythiol containing bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol as a main component and 23.9 parts of pentaerythritol tetrakis (mercaptopropionate) were added and mixed to form a homogeneous mixed liquid (polymerizable composition). The polythiol mainly composed of bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol was used at a moisture content of 70ppm, pentaerythritol tetrakis (mercaptopropionate) at a moisture content of 20ppm, and the polymerizable composition at a moisture content of 21 ppm. The homogeneous mixture was degassed under 600Pa for 1 hour, and then filtered through a 1 μm PTFE filter. Then, the mixture was injected into an injection mold for a lens comprising a glass mold having a diameter of 75mm and 4D and an adhesive tape. The injection mould was placed in an oven and held at 40 ℃ for 2 hours, heated to 50 ℃ for 2 hours over 4 hours and heated to 60 ℃ for 2 hours over 3 hours. The temperature was raised to 70 ℃ for another 3 hours and held for 2 hours, to 100 ℃ for another 3 hours, and to 130 ℃ for another 1 hour and held for 2 hours. As described above, the polymerization was carried out at a temperature ranging from 40 ℃ to 130 ℃ for a total of 24 hours. After the polymerization is finished, the injection mold is taken out of the oven, and the lens is obtained after demolding. The resulting lens was then annealed at 120 ℃ for 3 hours. The 100 lenses were produced as described above, and the striae incidence and the white turbidity incidence were calculated. The results are shown in Table 1.

[ example 9]

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 8 except that the polymerizable composition having a moisture content of 150ppm was used instead of the polymerizable composition used in example 8. The results are shown in Table 1.

[ example 10]

The measurement of the viscosity of the polymerizable composition and the production of a plastic lens were carried out in the same manner as in example 8 except that the polymerizable composition having a moisture content of 300ppm was used instead of the polymerizable composition used in example 8. The results are shown in Table 1.

Comparative example 1

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 1 except that the polymerizable composition having a moisture content of 500ppm was used instead of the polymerizable composition used in example 1. The results are shown in Table 1.

Comparative example 2

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 1 except that the polymerizable composition having a moisture content of 1000ppm was used instead of the polymerizable composition used in example 1. The results are shown in Table 1.

Comparative example 3

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 5 except that the polymerizable composition having a moisture content of 500ppm was used instead of the polymerizable composition used in example 5. The results are shown in Table 1.

Comparative example 4

The measurement of the viscosity of the polymerizable composition and the production of the plastic lens were carried out in the same manner as in example 8 except that the polymerizable composition having a moisture content of 500ppm was used instead of the polymerizable composition used in example 8. The results are shown in Table 1.

[ Table 1]

The resin obtained from the polymerizable composition having a small water content by using an appropriate amount of catalyst and polymerization mode has a striae and cloudiness occurrence rate of about 0 to 15%. From the results of examples and comparative examples, it was confirmed that the polymerization rate decreased and the viscosity decreased after 7 hours as the moisture content of the polymerizable composition increased. As a result, the striae incidence and the white turbidity incidence increased, and significantly varied within the range of 300ppm of water content. It is considered that when the water content exceeds a certain amount, the polymerization formulation and the polymerization rate are not matched with each other, and as a result, the striae occurrence rate and the cloudiness occurrence rate increase. When the water content of the polymerizable composition exceeds 300ppm, the viscosity after 7 hours becomes about 60% as compared with the case of low water content, and it is indicated that the decrease in the polymerization rate must be limited to such a degree to suppress striae and cloudiness. From the above, it is found that a polyurethane resin having high transparency can be provided by using a polymerizable composition having a water content of 10 to 300 ppm.

Industrial applicability

Polyurethane resins obtained by reacting a polythiol compound with a polyiso (thio) cyanate compound are colorless and transparent, have a high refractive index and are dispersed in a low amount, and are one of the most suitable resins for plastic lenses having excellent impact resistance, dyeability, processability and the like. Among them, the resin is essential for its transparency and good color tone. The present invention provides a transparent and high-performance optical element having properties essential as an optical material such as a lens with good yield and stably, and contributes to the development of this field.

Claims (12)

1. A method for producing a resin for optical materials, comprising the steps of,

step (1): reducing the moisture content in the polythiol compound by circulating nitrogen in the polythiol compound under reduced pressure, or by distillation of the polythiol compound;

step (2): mixing the polythiol compound obtained in the step (1) with a polyisocyanate compound and/or a polyisothiocyanate compound to obtain a polymerizable composition having a water content of 10 to 300 ppm;

step (3): and (3) polymerizing the polymerizable composition having a water content of 10 to 300ppm obtained in the step (2) to obtain a resin for an optical material.

2. The method for producing a resin for optical materials according to claim 1, wherein the water content in the polymerizable composition is 10 to 200 ppm.

3. The method for producing a resin for optical materials according to claim 1, wherein the polythiol compound has a moisture content of 20 to 600 ppm.

4. The method for producing a resin for optical materials according to claim 3, wherein the polythiol compound has a moisture content of 20 to 400 ppm.

5. The method for producing a resin for optical materials according to claim 1, wherein the polythiol compound comprises at least 1 compound selected from the group consisting of 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane, bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol, pentaerythritol tetrakis (3-mercaptopropionate), 1, 3, 3-tetrakis (mercaptomethylthio) propane, and 2-mercaptoethanol.

6. The method for producing a resin for optical materials according to claim 1, wherein the polyisocyanate compound and/or the polyisothiocyanate compound comprises at least 1 of alicyclic isocyanate compounds.

7. The method for producing a resin for optical materials according to claim 1, wherein the polythiol compound comprises at least 1 compound selected from the group consisting of 1, 2-bis [ (2-mercaptoethyl) thio ] -3-mercaptopropane, bis (mercaptomethyl) -3, 6, 9-trithio-1, 11-undecanedithiol, pentaerythritol tetrakis (3-mercaptopropionate), 1, 3, 3-tetrakis (mercaptomethylthio) propane and 2-mercaptoethanol, and the polyisocyanate compound and/or polyisothiocyanate compound comprises at least 1 of alicyclic isocyanate compounds.

8. The method for producing a resin for optical materials according to claim 6, wherein the alicyclic isocyanate compound comprises at least 1 compound selected from the group consisting of 2, 5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 2, 6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane diisocyanate and isophorone diisocyanate.

9. The method of producing a resin for optical materials according to claim 1, wherein the optical material is a lens.

10. A resin for optical materials obtained by the production method according to claim 1.

11. An optical material comprising the resin according to claim 10.

12. A lens comprised of the resin of claim 10.