Composition for optical material

The present invention relates to a composition for an optical material and the like, and more particularly to an optical material such as a plastic lens, a prism, an optical fiber, an information recording substrate and a filter, and particularly a composition for an optical material suitable for a plastic lens and the like.

Since plastic materials are lightweight, have high toughness, and are easy to dye, they have been widely used in various optical materials, especially spectacle lenses, in recent years. The performances particularly required for optical materials, especially spectacle lenses, are low specific gravity, high transparency, low yellowness, high heat resistance, high strength, etc. as physical properties, and high refractive index and high optical performance. Abbe number. A high refractive index makes it possible to make the lens thinner, and a high Abbe number reduces the chromatic aberration of the lens, but as the refractive index increases, the Abbe number decreases, so studies have been conducted to improve both at the same time. The most typical method among these studies is a method using an episulfide compound (see Patent Document 1).

In order to improve the oxidation resistance, a composition in which a thiol compound is added to an episulfide compound has been proposed (see Patent Document 2). Further studies have been conducted aiming at a high refractive index, and a composition composed of sulfur, episulfide and thiol has been proposed (see Patent Documents 3 and 4).

However, the composition containing these thiols may turn yellow when polymerized and cured. Since it is used as an optical material, if it is discolored after curing, it will be all defective and a huge loss will occur. Therefore, there has been a demand for a method that predicts the presence or absence of yellow discoloration after curing at the stage before curing and enables the judgment of quality.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 9-110979</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 10-298287</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2001-2783</text></patcit><patcit num="4"><text>Japanese Unexamined Patent Publication No. 2004-137481</text></patcit></p>

<p> An object to be solved by the present invention is to provide a composition for an optical material containing polythiol, which can predict and discriminate the presence or absence of yellow discoloration after curing at a stage before polymerization curing, and can judge the quality. Is.</p>

<p> As a result of intensive research in view of such a situation, the present inventors have solved this problem with a composition for an optical material containing polythiol having a total content of iron, chromium and nickel of 5.0 ppm or less and episulfide. The solution led to the present invention.</p><p> That is, the present invention is as follows. &lt;1&gt; A composition for an optical material, which comprises a polythiol compound having a total content of iron, chromium and nickel of 5.0 ppm or less and an episulfide compound. &lt;2&gt; The composition for an optical material according to &lt;1&gt; above, which further contains a polyisocyanate compound. &lt;3&gt; The composition for an optical material according to the above &lt;1&gt; or &lt;2&gt;, which further contains sulfur. &lt;4&gt; An optical material obtained by polymerizing the composition for an optical material according to any one of &lt;1&gt; to &lt;3&gt; above. &lt;5&gt; The optical material according to &lt;4&gt; above, which has been annealed after the polymerization of the composition for an optical material. &lt;6&gt; A method for producing a composition for an optical material, which comprises a step of mixing a polythiol compound having a total content of iron, chromium, and nickel of 5.0 ppm or less and an episulfide compound.</p>

<p> According to the present invention, a composition for an optical material containing a polythiol compound, which is difficult in the prior art, can predict and discriminate the presence or absence of yellow discoloration after curing at a stage before polymerization curing, and can judge the quality. Etc. can be provided.</p>

The polythiol compounds used in the present invention include all polythiol compounds, and specifically include methanedithiol, 1,2-dimercaptoethanol, 2,2-dimercaptopropane, and 1,3-dimercaptopropane. 1,2,3-Trimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis (2-mercaptoethyl) sulfide, 1,2-bis (2-mercaptoethylthio) ethane, 1 , 5-Dimercapto-3-oxapentane, 1,8-dimercapto-3,6-dioxaoctane, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-Mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl 1,4-dimercaptopropane, 2- (2-mercaptoethylthio) -1,3-dimercaptopropane, 1,2-bis (2) -Mercaptoethylthio) -3-mercaptopropane, 1,1,1-tris (mercaptomethyl) propane, tetrakis (mercaptomethyl) methane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9 -Trithiandecane, 4,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithiandecane, 5,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Tri Thiaundecane, 1,1,3,3-tetrakis (mercaptomethylthio) propane, ethylene glycol bis (2-mercaptoaceto), ethylene glycol bis (3-mercaptopropionate), 1,4-butanediol bis (2- Mercaptacetacetate), 1,4-butanediolbis (3-mercaptopropionate), trimethylolpropanetris (2-mercaptoacetacetase), trimethylolpropanetris (3-mercaptopropionate), pentaerythritoltetrakiss (2- Mercaptoacetate), pentaerythritoltetrakis (3-mercaptopropionate), 1,1-dimercaptocyclohexane, 1,2-Dimercaptocyclohexane, 1,3-dimercaptocyclohexane, 1,4-dimercaptocyclohexane, 1,3-bis (mercaptomethyl) cyclohexane, 1,4-bis (mercaptomethyl) cyclohexane, 2,5-bis ( Mercaptomethyl) -1,4-dithiane, 2,5-bis (mercaptoethyl) -1,4-dithiane, 1,2-bis (mercaptomethyl) benzene, 1,3-bis (mercaptomethyl) benzene, 1, 4-bis (mercaptomethyl) benzene, bis (4-mercaptophenyl) sulfide, bis (4-mercaptophenyl) ether, 2,2-bis (4-mercaptophenyl) propane, bis (4-mercaptomethylphenyl) sulfide, Examples thereof include bis (4-mercaptomethylphenyl) ether and 2,2-bis (4-mercaptomethylphenyl) propane.

Specific examples of the preferred compounds among the above are bis (2-mercaptoethyl) sulfide, pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), and 2,5-bis (mercapto). Methyl) -1,4-dithian, 1,2-bis (2-mercaptoethylthio) -3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane , 4,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithiandecane, 5,7-Dimercaptomethyl-1,11-Dimercapto-3,6,9-Trithiandecane, 1 , 1, 3, 3-tetrakis (mercaptomethylthio) propane, 1,3-bis (mercaptomethyl) benzene, 1,4-bis (mercaptomethyl) benzene. Specific examples of more preferable compounds are bis (2-mercaptoethyl) sulfide and 1,3-bis (mercaptomethyl) benzene, and the most preferable compound is bis (2-mercaptoethyl) sulfide.

The total content of iron, chromium, and nickel in the polythiol may be measured by any measuring method as long as the total content of iron, chromium, and nickel can be measured, but it is preferably measured using an ICP emission spectrometer. To do. The measurement is carried out after pretreating polythiol with an acid such as sulfuric acid or nitric acid according to a conventional method. After performing these measurements, polythiol having a total content of iron, chromium, and nickel of 5.0 ppm or less is used. It is preferably 2.0 ppm or less, more preferably 1.0 ppm or less, still more preferably 0.5 ppm or less, and most preferably 0.3 ppm or less.

If the total content of iron, chromium and nickel exceeds 5.0 ppm, the composition containing these polythiols will turn yellow when polymerized and cured, making it unusable. Therefore, by measuring the total content of iron, chromium, and nickel, it is possible to predict and discriminate the presence or absence of yellow discoloration without polymerization curing, and to judge the quality of polythiol.

When the total content of iron, chromium and nickel exceeds 5.0 ppm, it is an effective method to reduce the total content to 5.0 ppm or less through the refining process. It is also an effective method to further purify the product into a preferable, more preferable, more preferable, and most preferable state. Examples of the purification method include water washing, distillation, column separation operation, adsorbent treatment, ion exchange resin treatment and the like, but water washing and distillation are preferable.

Washing with water may or may not use a solvent, but is usually used. As the solvent, any solvent may be used as long as it dissolves the polythiol, but ether, toluene, benzene, preferably toluene, which can be easily separated from water, is preferably used. Therefore, washing with water is usually carried out in a state of being dissolved in toluene, and toluene is removed after completion.

The conditions for distillation differ depending on the polythiol used, but any condition may be used as long as the polythiol can be distilled. It is preferably under reduced pressure, more preferably 0.01 to 100 Torr. The distillation temperature may be a temperature that does not decompose, but is preferably 20 to 200 ° C, more preferably 50 ° C to 150 ° C.

The episulfide compound used in the present invention includes all episulfide compounds, and specific examples thereof are listed separately for compounds having a chain aliphatic skeleton, an aliphatic cyclic skeleton, and an aromatic skeleton. Examples of the compound having a chain aliphatic skeleton include a compound represented by the following formula (1).

<chemistry num="1"><img file="JP2012167198A_D0001.tif" /></chemistry>(However, m is an integer from 0 to 4, and n is an integer from 0 to 2.)

Examples of the compound having an aliphatic cyclic skeleton include compounds represented by the following formula (2) or (3).

<chemistry num="2"><img file="JP2012167198A_D0002.tif" /></chemistry>(p and q each independently represent an integer from 0 to 4.)

<chemistry num="3"><img file="JP2012167198A_D0003.tif" /></chemistry>(p and q each independently represent an integer from 0 to 4.) Examples of the compound having an aromatic skeleton include a compound represented by the following formula (4).

<chemistry num="4"><img file="JP2012167198A_D0004.tif" /></chemistry>(p and q each independently represent an integer from 0 to 4.)

Among them, the preferable compound is a compound represented by the above formula (1) having a chain aliphatic skeleton, and specifically, bis (β-epithiopropyl) sulfide, bis (β-epithiopropyl) disulfide, and bis. (β-Epithiopropyl) Trisulfide, Bis (β-Epithiopropylthio) Methan, 1,2-Bis (β-Epithiopropylthio) Ethan, 1,3-Bis (β-Epithiopropylthio) Propyl , 1,4-Bis (β-Epithiopropylthio) butane, Bis (β-Epithiopropylthioethyl) sulfide. Particularly preferable compounds are bis (β-epithiopropyl) sulfide (n = 0 in the above formula (1)) and bis (β-epithiopropyl) disulfide (m = 0, n = 1 in the above formula (1)). The most preferable compound is bis (β-epithiopropyl) sulfide (n = 0 in the above equation (1)).

Examples of episulfide compounds having an aliphatic cyclic skeleton include 1,3 and 1,4-bis (β-epithiopropylthio) cyclohexane (p = 0, q = 0 in the above equation (2)), 1,3. And 1,4-bis (β-epithiopropylthiomethyl) cyclohexane (p = 1, q = 1 in equation (2) above), bis [4- (β-epithiopropylthio) cyclohexyl] methane, 2, 2-Bis [4- (β-Epithiopropylthio) Cyclohexyl] Propyl, Bis [4- (β-Epithiopropylthio) Cyclohexyl] Sulfide, 2,5-Bis (β-Epithiopropylthio) -1, Examples thereof include 4-dithiane (p = 0, q = 0 in the above equation (3)), 2,5-bis (β-epithiopropylthioethylthiomethyl) -1,4-dithiane and the like.

In addition, as episulfide compounds having an aromatic skeleton, 1,3 and 1,4-bis (β-epithiopropylthio) benzene (p = 0, q = 0 in (4) above), 1,3 and 1 , 4-Bis (β-Epithiopropylthiomethyl) benzene (p = 1, q = 1 in Eq. (4) above), Bis [4- (β-Epithiopropylthio) phenyl] methane, 2,2- Bis [4- (β-epithiopropylthio) phenyl] propane, bis [4- (β-epithiopropylthio) phenyl] sulfide, bis [4- (β-epithiopropylthio) phenyl] sulfin, 4, 4-Bis (β-epithiopropylthio) biphenyl and the like can be mentioned.

In the composition for optical materials of the present invention, when the total of polythiol and episulfide is 100 parts by weight, the polythiol is usually 1 to 30 parts by weight, preferably 2 to 20 parts by weight, and particularly preferably 3 to 15 parts by weight. It is a department.

The composition for an optical material of the present invention may further contain a polyisocyanate compound. The polyisocyanate compound includes all compounds having a plurality of isocyanate groups, and specifically, diethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexanediisocyanate, 1,3-bis ( Isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, 2,6-bis (isocyanatomethyl) decahydronaphthalene, lysine triisocyanate, 2,4-tolylene diisocyanate, 2,6 -Torylene diisocyanate, o-trizine diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3- (2'-isocyanate cyclohexyl) propyl isocyanate, tris (phenylisocyanate) thiophosphate, isopropyridenebis ( Cyclohexylisocyanate), 2,2'-bis (4-isocyanatophenyl) propane, triphenylmethane triisocyanate, bis (diisocyanatotril) phenylmethane, 4,4', 4''-triisocyanate-2,5 -Dimethoxyphenylamine, 3,3'-dimethoxybenzidine-4,4'-diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediisocyanate, 4,4'-diisocyanatobiphenyl, 4,4'-diisocyanate Isocyanate-3,3'-dimethylbiphenyl, dicyclohexylmethane-4,4'-diisocyanate, 1,1'-methylenebis (4-isocyanatebenzene), 1,1'-methylenebis (3-methyl-4-isocyanate) Benzene), m-xylylene diisocyanate, p-xylylene diisocyanate, 1,3-bis (1-isocyanate-1-methylethyl) benzene, 1,4-bis (1-isocyanate-1-methylethyl) benzene , 1, 3-Bis (2-isocyanato-2-propyl) benzene, 2,6-bis (isocyanatomethyl) naphthalene, 1,5-naphthalenediocyanate, bis (isocyanatomethyl) tetrahydrodicyclopentadiene, bis (isocyanatomethyl) ) Dicyclopentadiene, bis (isocyanatomethyl) tetrahydrothiophene, bis (isocyanatomethyl) norbornene, bis (isocyanatomethyl) adamantan, diisocyanate dimerate, 1,3,5-tri (1-isocyanatehexyl) isocyanurate , Thiodiethyldiisocyanate, thiodipropyldiisocyanate, thiodihexyldiisocyanate, bis [(4-isocyanatomethyl) phenyl] sulfide, 2,5-diisocyanate-1,4-dithian, 2,5-diisocyanatomethyl-1, Polyisocyanates such as 4-dithian, 2,5-diisocyanatomethylthiophene, dithiodiethyldiisocyanate, dithiodipropyldiisocyanate, and compounds in which all or part of the isocyanate groups of the above isocyanates are changed to isocyanate groups. And so on. Among the above, examples of polyisocyanates include dimers, cyclized trimers and adducts of alcohols or thiols obtained by a burette-type reaction. Although specific examples have been shown above, the polyisocyanate compounds that can be used in the composition for optical materials of the present invention are not limited to these, and these polyisocyanate compounds may be mixed alone or in combination of two or more. You may use it. 5-Naphthalenediocyanate, bis (isocyanatomethyl) tetrahydrodicyclopentadiene, bis (isocyanatomethyl) dicyclopentadiene, bis (isocyanatomethyl) tetrahydrothiophene, bis (isocyanatomethyl) norbornene, bis (isocyanatomethyl) adamantan , Diisocyanate dimerate, 1,3,5-tri (1-isocyanatohexyl) isocyanurate, thiodiethyldiisocyanate, thiodipropyldiisocyanate, thiodihexyldiisocyanate, bis [(4-isocyanatomethyl) phenyl] sulfide, 2, Polyisocyanates such as 5-diisocyanate-1,4-dithianate, 2,5-diisocyanatemethyl-1,4-dithianate, 2,5-diisocyanatemethylthiophene, dithiodiethyldiisocyanate, dithiodipropyldiisocyanate, and more. Can be mentioned as a compound in which all or part of the isocyanate groups of the above-mentioned isocyanates are changed to isocyanate groups. In addition, among the above, examples of polyisocyanates include dimers by burette type reaction, cyclized trimers, and isocyanates such as alcohol or thiol adducts. Although specific examples have been shown above, the polyisocyanate compounds that can be used in the composition for optical materials of the present invention are not limited to these, and these polyisocyanate compounds may be mixed alone or in combination of two or more. You may use it. 5-Naphthalenediocyanate, bis (isocyanatomethyl) tetrahydrodicyclopentadiene, bis (isocyanatomethyl) dicyclopentadiene, bis (isocyanatomethyl) tetrahydrothiophene, bis (isocyanatomethyl) norbornene, bis (isocyanatomethyl) adamantan , Diisocyanate dimerate, 1,3,5-tri (1-isocyanatohexyl) isocyanurate, thiodiethyldiisocyanate, thiodipropyldiisocyanate, thiodihexyldiisocyanate, bis [(4-isocyanatomethyl) phenyl] sulfide, 2, Polyisocyanates such as 5-diisocyanate-1,4-dithianate, 2,5-diisocyanatemethyl-1,4-dithianate, 2,5-diisocyanatemethylthiophene, dithiodiethyldiisocyanate, dithiodipropyldiisocyanate, and more. Can be mentioned as a compound in which all or part of the isocyanate groups of the above-mentioned isocyanates are changed to isocyanate groups. In addition, among the above, examples of polyisocyanates include dimers by burette type reaction, cyclized trimers, and isocyanates such as alcohol or thiol adducts. Although specific examples have been shown above, the polyisocyanate compounds that can be used in the composition for optical materials of the present invention are not limited to these, and these polyisocyanate compounds may be mixed alone or in combination of two or more. You may use it. Polyisocyanates such as 5-diisocyanate methylthiophene, dithiodiethyldiisocyanate, and dithiodipropyldiisocyanate, and compounds in which all or part of the isocyanate groups of the above isocyanates are changed to isothiocyanate groups can be mentioned. .. In addition, among the above, examples of polyisocyanates include dimers by burette type reaction, cyclized trimers, and isocyanates such as alcohol or thiol adducts. Although specific examples have been shown above, the polyisocyanate compounds that can be used in the composition for optical materials of the present invention are not limited to these, and these polyisocyanate compounds may be mixed alone or in combination of two or more. You may use it. Polyisocyanates such as 5-diisocyanate methylthiophene, dithiodiethyldiisocyanate, and dithiodipropyldiisocyanate, and compounds in which all or part of the isocyanate groups of the above isocyanates are changed to isothiocyanate groups can be mentioned. .. In addition, among the above, examples of polyisocyanates include dimers by burette type reaction, cyclized trimers, and isocyanates such as alcohol or thiol adducts. Although specific examples have been shown above, the polyisocyanate compounds that can be used in the composition for optical materials of the present invention are not limited to these, and these polyisocyanate compounds may be mixed alone or in combination of two or more. You may use it.

Among the above, preferable polyisocyanate compounds are 1,3-bis (isocyanatomethyl) cyclohexane, m-xylylene diisocyanate, bis (isocyanatomethyl) norbornene, and 2,5-diisocyanatomethyl-1,4-dithiane. , 1,3-Bis (1-isocyanato-1-methylethyl) benzene, and the most preferred polyisocyanate compound is m-xylylene diisocyanate.

The amount of the polyisocyanate compound added is usually 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass, and more preferably 1 to 15 parts by mass with respect to the total amount of the composition for optical materials.

Sulfur may be added to the composition for optical materials of the present invention. When sulfur is used, it is preferable to preliminarily react the episulfide compound with sulfur. The conditions for this preliminary polymerization reaction are preferably 0.1 to 240 hours at -10 ° C to 120 ° C, more preferably 0.1 to 120 hours at 0 to 100 ° C, and particularly preferably 0.1 at 20 to 80 ° C. ~ 60 hours. The use of catalysts to facilitate the preliminary reaction is effective and preferred examples are 2-mercapto-1-methylimidazole, triphenylphosphine, 3,5-dimethylpyrazole, N-cyclohexyl-2-benzothia. Zoryl sulfine amide, dipentamethylene thiuram tetrasulfide, tetrabutyl thiuram disulfide, tetraethyl thiuram disulfide, 1,2,3-triphenylguanidine, 1,3-diphenylguadinin, 1,1,3,3-tetramethyleneguanidine , Aminoguanidine urea, trimethylthiourea, tetraethylthiourea, dimethylethylthiourea, zinc dibutyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate, pipecorium pipecoryldithiocarbamate and the like. Furthermore, it is preferable to consume 10% or more of sulfur (100% before the reaction) by this preliminary polymerization reaction, and more preferably 20% or more. The preliminary reaction may be carried out in any atmosphere, such as in the atmosphere, under an inert gas such as nitrogen, or under normal pressure or hermetically sealed by pressurization or depressurization. It is also possible to use liquid chromatography or a refractive index meter to detect the progress of the preliminary reaction.

The amount of sulfur added is usually 0.01 to 40 parts by weight, preferably 0.1 to 30 parts by weight, and more preferably 0.5 to 25 parts by weight, based on the total amount of the composition for optical materials.

In the present invention, it is preferable that the composition for an optical material is degassed in advance. The degassing treatment is carried out under reduced pressure before, during or after mixing the compound, the polymerization catalyst and the additive capable of reacting with a part or all of the composition components. Preferably, it is carried out under reduced pressure during or after mixing. The treatment conditions are 0 ° C to 100 ° C for 1 minute to 24 hours under a reduced pressure of 0.001 to 50 torr. The degree of decompression is preferably 0.005 to 25 torr, more preferably 0.01 to 10 torr, and the degree of decompression may be varied within these ranges. The degassing time is preferably 5 minutes to 18 hours, more preferably 10 minutes to 12 hours. The temperature at the time of degassing is preferably 5 ° C to 80 ° C, more preferably 10 ° C to 60 ° C, and the temperature may be varied within these ranges. During the degassing treatment, updating the interface of the resin composition by stirring, blowing gas, vibrating by ultrasonic waves, or the like is a preferable operation for enhancing the degassing effect. The components removed by the degassing treatment are mainly dissolved gas such as hydrogen sulfide and low boiling point substances such as low molecular weight thiol, but if the effect of the present invention is exhibited, the target of removal is particularly high. The type of ingredient is not limited.

Furthermore, purifying these compositions for optical materials and / or each raw material before mixing by filtering impurities and the like with a filter having a pore size of about 0.05 to 10 μm further enhances the quality of the optical material of the present invention. It is also preferable from.

Hereinafter, a method for producing an optical material by polymerizing the composition for an optical material of the present invention will be described. As a catalyst for polymerizing and curing the composition for an optical material of the present invention, an amine, an onium salt or a phosphine compound is used. Specific examples include amines, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, secondary iodonium salts, and phosphine compounds. Of these, a quaternary ammonium salt, a quaternary phosphonium salt, and a phosphine compound having good compatibility with the composition are more preferable, and a quaternary phosphonium salt is more preferable. Specific examples of more preferable compounds include quaternary ammonium salts such as tetra-n-butylammonium bromide, tetraphenylammonium bromide, triethylbenzylammonium chloride, cetyldimethylbenzylammonium chloride, 1-n-dodecylpyridinium chloride, and tetra-. Examples thereof include quaternary phosphonium salts such as n-butylphosphonium bromide and tetraphenylphosphonium bromide, and phosphine compounds such as triphenylphosphine. Of these, more preferred compounds are triethylbenzylammonium chloride and tetra-n-butylphosphonium bromide, and the most preferred compound is tetra-n-butylphosphonium bromide. The polymerization catalyst may be used alone or in combination of two or more.

The amount of the polymerization catalyst added varies depending on the composition, the mixing ratio, and the polymerization curing method, and therefore cannot be unconditionally determined, but is usually 0.001 wt% or more and 5 wt% or less, preferably 0.001 wt% or more and 5 wt% or less, based on the total amount of the composition for optical materials. Is 0.01 wt% or more and 1 wt% or less, most preferably 0.01 wt% or more and 0.5 wt% or less. If the amount of the polymerization catalyst added is more than 5 wt%, the refractive index and heat resistance of the cured product will decrease, and coloring may occur. If it is less than 0.001 wt%, it may not be sufficiently cured and the heat resistance may be insufficient.

When the composition for an optical material is polymerized and cured, a polymerization modifier can be added as necessary for the purpose of extending the pot life and dispersing the heat generated by the polymerization. Preferred compounds as polymerization modifiers are halides of silicon, germanium, tin and antimony, and more preferred compounds are chlorides of germanium, tin and antimony having an alkyl group. More preferred compounds are, specifically, dibutyltin dichloride, butyltin trichloride, dioctyltin dichloride, octyltin trichloride, dibutyldichlorogermanium, butyltrichlorogermanium, diphenyldichlorogermanium, phenyltrichlorogermanium, triphenylantimonydichloride, and most preferred A specific example of the compound is dibutyltin dichloride. The polymerization modifier may be used alone or in combination of two or more.

The amount of the polymerization modifier added is usually 0.0001 to 5.0 wt%, preferably 0.0005 to 3.0 wt%, and more preferably 0.001 to 2.0 wt% with respect to the total amount of the composition for optical materials.

Further, when the composition for an optical material of the present invention is polymerized and cured to obtain an optical material, additives such as a known antioxidant, an ultraviolet absorber, and a bluing agent are added to further improve the practicality of the obtained material. Of course, it is possible to improve it.

Phenolic derivatives are preferred examples of antioxidants. Among them, preferable compounds are polyhydric phenols and halogen-substituted phenols, more preferable compounds are catechols, pyrogallols and alkyl-substituted catechols, and the most preferable compounds are catechols and pyrogallols. Preferred examples of the UV protection agent include benzotriazole compounds. Specific examples of the most preferable compounds are 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole and 5-chloro-2- (3,5-di-tert-butyl-2-hydroxyphenyl) -2H. -Benzotriazole, 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-pentyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (2-hydroxy-4-octyloxyphenyl) -2H-benzotriazole, 2 -(2-Hydroxy-5-tert-octylphenyl) -2H-benzotriazole. Preferred examples of the bluing agent include anthraquinone compounds.

When the composition for an optical material of the present invention is easily peeled off from the mold during polymerization, a known external and / or internal adhesion improver is used or added to control the adhesion between the obtained cured product and the mold. , It is also possible to improve. Examples of the adhesion improving agent include known silane coupling agents and titanate compounds, and these may be used alone or in combination of two or more. The amount added is usually 0.0001 to 5 wt% with respect to the total amount of the composition for optical materials. On the contrary, when the composition of the present invention is difficult to be peeled off from the mold after polymerization, a known external and / or internal mold release agent is used or added to improve the mold release property of the obtained cured product. Is also possible. The release agent is a fluorine-based nonionic surfactant, a silicon-based nonionic surfactant, a phosphoric acid ester, an acidic phosphoric acid ester, an oxyalkylene type acidic phosphoric acid ester, an alkali metal salt of an acidic phosphoric acid ester, and an alkali of an oxyalkylene type acidic phosphoric acid ester. Metal salts, alkali metal salts of higher fatty acids, higher fatty acid esters, paraffins, waxes, higher aliphatic amides, higher fatty alcohols, polysiloxanes, aliphatic amine ethylene oxide adducts, etc. The above may be mixed and used. The amount added is usually 0.0001 to 5 wt% with respect to the total amount of the composition for optical materials.

The method for producing an optical material by polymerizing and curing the composition for an optical material of the present invention is as follows, to be described in more detail. Even if the above-mentioned composition components, antioxidants, UV absorbers, polymerization catalysts, radical polymerization initiators, adhesion improvers, mold release agents and other additives are all mixed in the same container at the same time with stirring. Each raw material may be added and mixed stepwise, or several components may be mixed separately and then remixed in the same container. The raw materials and auxiliary materials may be mixed in any order. For mixing, the set temperature, the time required for this, and the like are basically sufficient as long as each component is sufficiently mixed.

The composition for optical materials that has been subjected to the above-mentioned reaction and treatment is injected into a glass or metal mold, and is removed from the mold after the polymerization curing reaction is promoted by heating or irradiation with active energy rays such as ultraviolet rays. .. In this way, the optical material is manufactured. The composition for an optical material is preferably polymerized and cured by heating to produce an optical material. In this case, the curing time is 0.1 to 200 hours, usually 1 to 100 hours, and the curing temperature is -10 to 160 ° C, usually -10 to 140 ° C. The polymerization can be carried out by holding at a predetermined polymerization temperature for a predetermined time, raising the temperature by 0.1 ° C to 100 ° C / hour, lowering the temperature by 0.1 ° C to 100 ° C / hour, and a combination thereof. Further, in the method for producing an optical material of the present invention, after the polymerization is completed, the cured product is annealed at a temperature of 50 to 150 ° C. for about 10 minutes to 5 hours in order to eliminate distortion of the optical material. This is a preferred process. Further, if necessary, surface treatment such as dyeing, hard coating, impact resistance coating, antireflection, and antifogging can be performed.

<p> Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. The evaluation was performed by the following method. Total iron, chromium and nickel content: The total iron, chromium and nickel content of polythiol was measured using an ICP emission spectrometer SPS5520 manufactured by SII Nanotechnology. Measurement of yellow: Flat plates with a thickness of 5 mm were prepared by the following polymerization methods A to D, and the YI value was measured using a colorimeter JS555 manufactured by Color Techno. Comparing the YI values with a flat plate prepared using polythiol having a total content of iron, chromium, and nickel below the detection limit (0.1 ppm), a difference (ΔYI) of 0.1 or less is , 0.1 to 0.3 is , and 0.3. ~ 0.5 was defined as Δ, and 0.5 or more was defined as ×. Of the above, was accepted.</p><p>(Polymerization method A) To a composition consisting of 5 parts by weight of bis (2-mercaptoethyl) sulfide and 95 parts by weight of bis (β-epithiopropyl) sulfide, 0.1 part by weight of tetrabutylphosphonium bromide was added as a polymerization catalyst and mixed uniformly at room temperature. After that, deaeration treatment was performed. After that, it was filtered through a 1 μm PTFE filter, injected into a mold, and heated from 20 ° C to 100 ° C for 20 hours to polymerize and cure. After that, it was demolded to obtain an optical material.</p><p>(Polymerization method B) 14 parts by weight of 1,3-bis (mercaptomethyl) benzene, 77 parts by weight of bis (β-epithiopropyl) sulfide, 9 parts by weight of tetramethylxylylene diisocyanate, 0.2 parts by weight of tetrabutylphosphonium bromide as a polymerization catalyst, dibutyltin dichloride 0.05 parts by weight was added, and the mixture was uniformly mixed at room temperature and then degassed. After that, it was filtered through a 1 μm PTFE filter, injected into a mold, and heated from 20 ° C to 100 ° C for 20 hours to polymerize and cure. After that, it was demolded to obtain an optical material.</p><p>(Polymerization method C) To 79 parts by weight of bis (β-epithiopropyl) sulfide and 14 parts by weight of sulfur, 0.5 part by weight of mercaptomethylimidazole was added, and the reaction was preliminarily reacted at 60 ° C. After cooling to 20 ° C, 7 parts by weight of bis (2-mercaptoethyl) sulfide, 0.2 parts by weight of dibutyltin dichloride, and 0.03 part by weight of triethylbenzylammonium chloride as a polymerization catalyst were added, and the mixture was uniformly mixed and then degassed. Was done. After that, it was filtered through a 1 μm PTFE filter, injected into a mold, and heated from 20 ° C to 100 ° C for 20 hours to polymerize and cure. After that, it was demolded to obtain an optical material.</p><p>(Polymerization method D) In 6 parts by weight of bis (2-mercaptoethyl) sulfide, 6 parts by weight of pentaerythritol tetraxthiopropionate, 80 parts by weight of bis (β-epithiopropyl) sulfide, 1 part by weight of sulfur, 7 parts by weight of m-xylylene diisocyanate 0.1 part by weight of tetrabutylphosphonium bromide and 0.05 part by weight of dibutyltin dichloride were added, mixed uniformly at room temperature, and then degassed. After that, it was filtered through a 1 μm PTFE filter, injected into a mold, and heated from 20 ° C to 100 ° C for 20 hours to polymerize and cure. After that, it was demolded to obtain an optical material.</p><p>(Create blank) Polymerization method A ~ using bis (2-mercaptoethyl) sulfide, m-xylylene thiol, and pentaerythritol tetrakisthiopropionate whose total content of iron, chromium, and nickel was below the detection limit (0.1 ppm). A flat plate with a thickness of 5 mm was prepared using the method of D.</p><p>Examples 1 to 3 Using the bis (2-mercaptoethyl) sulfide having the total content of iron, chromium, and nickel shown in Table 1, a flat plate with a thickness of 5 mm was prepared using the method of polymerization method A, and ΔYI was obtained by comparing with a blank. It was. The results are summarized in Table 1.</p><p>Examples 4 to 6 Using m-xylylene thiol having a total content of iron, chromium, and nickel shown in Table 1, a flat plate having a thickness of 5 mm was prepared by using the method of polymerization method B. Compared with the blank, ΔYI was calculated by comparing with the blank. The results are summarized in Table 1.</p><p>Examples 7-9 Using the bis (2-mercaptoethyl) sulfide having the total content of iron, chromium, and nickel shown in Table 1, a flat plate with a thickness of 5 mm was prepared using the method of polymerization method C, and ΔYI was obtained by comparing with a blank. It was. The results are summarized in Table 1.</p><p>Examples 10-12 Using the total content of iron, chromium, and nickel shown in Table 2, bis (2-mercaptoethyl) sulfide, and pentaerythritol tetrakisthiopropionate, a flat plate with a thickness of 5 mm was prepared using the method of polymerization method D. .. Compared with the blank, ΔYI was calculated by comparing with the blank. The results are summarized in Table 2.</p><p>Comparative example 1 Using bis (2-mercaptoethyl) sulfide having a total content of iron, chromium, and nickel shown in Table 2, a flat plate having a thickness of 5 mm was prepared using the method of polymerization method A. Compared with the blank, ΔYI was calculated by comparing with the blank. The results are summarized in Table 2.</p><p>Comparative example 2 Using m-xylylene thiol having a total content of iron, chromium, and nickel shown in Table 2, a flat plate having a thickness of 5 mm was prepared by using the method of polymerization method B. Compared with the blank, ΔYI was calculated by comparing with the blank. The results are summarized in Table 2.</p><p>Comparative example 3 Using bis (2-mercaptoethyl) sulfide having a total content of iron, chromium, and nickel shown in Table 2, a flat plate having a thickness of 5 mm was prepared by using the method of polymerization method C. Compared with the blank, ΔYI was calculated by comparing with the blank. The results are summarized in Table 2.</p><p>Comparative example 4 Using the total content of iron, chromium, and nickel shown in Table 2, bis (2-mercaptoethyl) sulfide, and pentaerythritol tetrakisthiopropionate, a flat plate with a thickness of 5 mm was prepared using the method of polymerization method D. .. Compared with the blank, ΔYI was calculated by comparing with the blank. The results are summarized in Table 2.</p><p><tables num="1"><img file="JP2012167198A_D0005.tif" /></tables></p><p><tables num="2"><img file="JP2012167198A_D0006.tif" /></tables></p><p> In the above-described embodiment, it is possible to prevent yellowing after curing by polymerizing a composition for an optical material using a polythiol that satisfies the condition that the total content of iron, chromium, and nickel is 0.5 ppm or less. did it. Therefore, according to the present invention, it is possible to selectively produce only optical materials having good properties by predicting the presence or absence of yellowing after polymerization and curing and determining the quality before the polymerization reaction. Therefore, both effective utilization of the composition for optical materials and production of excellent optical materials are possible.</p>