JP4957629B2 - Manufacturing method of optical material - Google Patents

Description

  The present invention relates to a method of manufacturing a plastic lens for spectacles, particularly a semi-finished lens, which is an optical material such as a plastic lens, a prism, an optical fiber, an information recording substrate, and a filter.

  Plastic lenses are lightweight, tough and easy to dye, and the performance required especially for plastic lenses is low specific gravity, high transparency and low yellowness, high refractive index and high Abbe number as optical performance, and high Heat resistance, high strength, etc. A high refractive index enables the lens to be thinned, and a high Abbe number reduces the chromatic aberration of the lens. In recent years, many organic compounds having a sulfur atom and / or a selenium atom have been reported for the purpose of high refractive index and high Abbe number. Among them, polyepisulfide compounds have a good balance between the refractive index and the Abbe number. For example, linear polyepisulfide compounds and polyepisulfide compounds having a selenium atom have been proposed (for example, see Patent Document 1). .) Although the optical material obtained from the polyepisulfide compounds of these inventions has achieved a high refractive index of 1.7 or more, a material having a higher refractive index is required, and sulfur atoms and / or selenium are required. An optical material containing an inorganic compound having an atom has been proposed (see, for example, Patent Document 2).

  A lens mold used for molding a plastic lens is a finish lens that molds a desired plastic lens, a semi-finished lens that molds a desired plastic lens by making the optical and non-optical surfaces face each other, and cutting the non-optical surface. There is a method to make a finish lens. In recent years, with the diversification of plastic lens products, the ratio of cut products has increased. In particular, the polymerization of semi-finished lenses has a quality problem such as optical distortion or striae. It was.

Japanese Patent Laid-Open No. 9-110979 Japanese Patent Laid-Open No. 2004-137482

  An object of the present invention is to impart a high degree of transparency and uniformity to an optical material having a high refractive index without optical distortion or striae, particularly a semi-finished lens.

As a result of intensive studies to solve these problems, the present inventors,
(A) a compound represented by the following formula (1):
(M represents an integer of 0 to 4, n represents an integer of 0 to 2)
(B) sulfur,
(C) In a method for producing an optical material for polymerizing a composition for optical materials comprising a compound having at least one mercapto group and one sulfide bond per molecule,
(1) A mixture of (a) a compound and (b) sulfur is reacted at 0 to 100 ° C. under a reduced pressure of 0.001 to 50 Torr for 1 minute to 24 hours, and (b) 50% or more of sulfur ( A step of reacting 90% or less)
(2) Next, adding the compound (c) and vacuum degassing at 0 to 100 ° C. for 1 minute to 24 hours under a reduced pressure of 0.001 to 50 Torr,
(3) A step of holding the resin composition for an optical material after completion of the step (2) at 10 ° C to 30 ° C for 1 hour to 6 hours,
(4) A method for producing an optical material, wherein the resin composition for optical material is injected into a lens mold and polymerized and cured.

That is, the present invention is as follows.
1. (A) a compound represented by the formula (1), (b) sulfur,
(C) In a method for producing an optical material for polymerizing a resin composition for an optical material comprising a compound having at least one mercapto group and one sulfide bond per molecule,
(1) A mixture of (a) a compound and (b) sulfur is reacted at 0 to 100 ° C. under a reduced pressure of 0.001 to 50 Torr for 1 minute to 24 hours, and (b) 50% or more of sulfur ( A step of reacting 90% or less)
(2) Next, adding the compound (c) and vacuum degassing at 0 to 100 ° C. for 1 minute to 24 hours under a reduced pressure of 0.001 to 50 Torr,
(3) The refractive index of the resin composition for optical materials (nD) is maintained by maintaining the resin composition for optical materials after the completion of the step (2) at 10 ° C. to 30 ° C. for 1 to 6 hours without degassing. (20 ° C)) is increased 0.001 to 0.002 immediately after the end of the deaeration process,
(4) A method for producing an optical material, wherein the resin composition for an optical material is poured into a lens mold and polymerized and cured.
2. 2. The method for producing an optical material according to item 1, wherein the optical material is a semi-finished lens.

  After the step of reacting a mixture of (a) compound and (b) sulfur under a certain condition to a desired reaction rate or higher, (c) the compound is mixed and held until a desired refractive index is obtained, and then cast. By the method for producing a resin composition for optical materials characterized by polymerization, it has become possible to provide a semi-finished lens that imparts a higher degree of transparency and uniformity to an optical material having a high refractive index. .

The addition amount of the compound (a) used in the present invention is 30 to 95 parts by weight, preferably 40 to 40 parts by weight when the total amount of the (a) compound, (b) sulfur and (c) compound is 100 parts by weight. 95 parts by weight, particularly preferably 50 to 90 parts by weight.

  Specific examples of the compound (a) include bis (β-epithiopropyl) sulfide, bis (β-epithiopropyl) disulfide, bis (β-epithiopropyl) trisulfide, and bis (β-epithiopropylthio). Methane, 1,2-bis (β-epithiopropylthio) ethane, 1,3-bis (β-epithiopropylthio) propane, 1,2-bis (β-epithiopropylthio) propane, 1,4 -Episulfides such as bis (β-epithiopropylthio) butane and bis (β-epithiopropylthioethyl) sulfide. (A) The compounds may be used alone or in combination of two or more. Among them, preferred specific examples are bis (β-epithiopropyl) sulfide and / or bis (β-epithiopropyl) disulfide, and the most preferred specific example is bis (β-epithiopropyl) sulfide.

  The added amount of (b) sulfur used in the present invention is 0.1 to 50 parts by weight, preferably 100 parts by weight when the total amount of (a) compound, (b) sulfur and (c) compound is 100 parts by weight, preferably 0.5 to 45 parts by weight, particularly preferably 5 to 40 parts by weight.

(C) As a compound, a thiol compound having at least one sulfide bond in one molecule is selected in order to maintain a high refractive index, and in particular, two thiol groups in one molecule to exhibit high heat resistance. The compounds having the above are effective. That is, the effect of the present invention is remarkably exhibited in the specific compound (c) having one or more sulfide bonds in one molecule and two or more thiol groups in one molecule.

  Specific examples of the compound (c) include bis (2-mercaptoethyl) sulfide, bis (2,3-dimercaptopropyl) sulfide, 1,2-bis (2-mercaptoethylthio) ethane, 2- (2- Mercaptoethylthio) -1,3-dimercaptopropane, 1,2-bis (2-mercaptoethylthio) -3-mercaptopropane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 2, 4-bis (mercaptomethyl) -1,5-dimercapto-3-thiapentane, 4,8-bis (mercaptomethyl) -1,11-dimercapto-3,6,9-trithiaundecane, 4,7-bis ( Mercaptomethyl) -1,11-dimercapto-3,6,9-trithiaundecane, 5,7-bis (mercaptomethyl) -1,11-dimethyl Capto-3,6,9-trithiaundecane, 1,2,7-trimercapto-4,6-dithiaheptane, 1,2,9-trimercapto-4,6,8-trithianonane, 1,2,8, 9-tetramercapto-4,6-dithianonane, 1,2,10,11-tetramercapto-4,6,8-trithiaundecane, 1,2,12,13-tetramercapto-4,6,8,10 -Tetrathiatridecane, tetrakis (4-mercapto-2-thiabutyl) methane, tetrakis (7-mercapto-2,5-dithiaheptyl) methane, 1,5-dimercapto-3-mercaptomethylthio-2,4-dithiapentane, 3, , 7-bis (mercaptomethylthio) -1,9-dimercapto-2,4,6,8-tetrathianonane, 1,1,3,3-tetrakis (mercapto) Methylthio) propane, 2,5-bis (mercaptomethyl) -1,4-dithiane, 2,5-bis (2-mercaptoethyl) -1,4-dithiane, 2,5-bis (mercaptomethyl) -1- Polythiols such as thiane, 2,5-bis (2-mercaptoethyl) -1-thiane, bis (4-mercaptophenyl) sulfide, bis (4-mercaptomethylphenyl) sulfide, 3,4-thiophenedithiol, and the like And thiols such as oligomers such as dimers to 20-mers. (C) The compounds may be used alone or in combination of two or more. Among these, preferred specific examples are bis (2-mercaptoethyl) sulfide and / or 2,5-bis (mercaptomethyl) -1,4-dithiane, and the most preferred specific examples are easily available industrially. Bis (2-mercaptoethyl) sulfide.

  When the composition for optical material comprising the compound (a), (b) sulfur and the compound (c) is polymerized to obtain an optical material, a polymerization catalyst can be added as necessary. As the polymerization catalyst, imidazoles, phosphines, thioureas, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, and secondary iodonium salts are preferable, and particularly, compatibility with the composition is good. More preferred are imidazoles, quaternary ammonium salts and quaternary phosphonium salts, and more preferred are imidazoles and quaternary ammonium salts.

  Specific examples of more preferable polymerization catalysts include tetra-n-butylammonium bromide, triethylbenzylammonium chloride, cetyldimethylbenzylammonium chloride, quaternary ammonium salts such as 1-n-dodecylpyridinium chloride, tetra-n-butylphosphonium. Examples thereof include quaternary phosphonium salts such as bromide and tetraphenylphosphonium bromide, and imidazoles such as N-benzylimidazole, 4-methylimidazole, 1-phenylimidazole and 2-methyl-N-methylimidazole. Among these, more preferred specific examples are tetra-n-butylphosphonium bromide, triethylbenzylammonium chloride, 2-methyl-N-imidazole, and more preferably triethylbenzylammonium chloride or / and 2-methyl-N. -Imidazole. As mentioned above, although the polymerization catalyst at the time of carrying out the polymerization hardening of the resin composition for optical materials was illustrated, if the polymerization effect is expressed, it will not be limited to these listed compounds. These may be used alone or in combination of two or more.

    The addition amount of a polymerization catalyst is 0.0005-5.0 weight part with respect to 100 weight part of compositions for optical materials, Preferably, it is 0.0001-3.0 weight part.

  When the composition for an optical material comprising the compound (a), (b) sulfur and the compound (c) is polymerized and cured, a polymerization regulator is added as necessary for the purpose of extending the pot life or dispersing the polymerization heat. Can be added. Examples of the polymerization regulator include halides of Groups 13 to 16 in the long-term periodic table. Among these, preferred are halides of silicon, germanium, tin and antimony, and more preferred are chlorides of germanium, tin and antimony having an alkyl group. More preferred are specifically dibutyltin dichloride, butyltin trichloride, dioctyltin dichloride, octyltin trichloride, dibutyldichlorogermanium, butyltrichlorogermanium, diphenyldichlorogermanium, phenyltrichlorogermanium, triphenylantimony dichloride, most preferred A specific example is dibutyltin dichloride. The polymerization regulator may be used alone or in combination of two or more.

  The addition amount of the polymerization regulator is 0.0001 to 5.0 parts by weight, preferably 0.0005 to 100 parts by weight of the total amount of (a) compound, (b) sulfur and (c) compound. The amount is 3.0 parts by weight, more preferably 0.001 to 2.0 parts by weight.

  Furthermore, addition of an epoxy compound to form a composition for optical materials is also an effective means for improving the uniformity of the optical material. Specific examples of epoxy compounds include phenolic epoxy compounds produced by condensation of aromatic hydroxy compounds such as phenol and bisphenol A and epihalohydrin, alcoholic epoxy compounds produced by condensation of alcohol compounds and epihalohydrin, carboxylic acid compounds, and the like. Glycidyl ester epoxy compound produced by condensation of epihalohydrin, amine epoxy compound produced by condensation of amine and epihalohydrin, epoxy compound produced by oxidative epoxidation of unsaturated compound, alcohol, phenol compound and diisocyanate and glycidol, etc. Urethane epoxy compounds produced from the above, and compounds in which part or all of the thiirane ring of the episulfide compound is substituted with an epoxy ring It can be. Among these, a phenolic epoxy compound is preferable, and diglycidyl ether of bisphenol A is most preferable. The addition amount is usually 0.0001 to 5 parts by weight with respect to 100 parts by weight of the total amount of (a) compound, (b) sulfur and (c) compound.

  Further, in order to improve the dyeability of an optical material obtained by polymerizing the composition for optical materials of the present invention, as a dyeability improving component, carboxylic acid, mercaptocarboxylic acid, hydroxycarboxylic acid, amide, 1,3-diketone, 1 , 3-dicarboxylic acid, 3-ketocarboxylic acid and esters thereof, mercapto alcohols, and compounds having an unsaturated group can be used in combination. The addition amount of these compounds is 0.0001-5 weight part with respect to 100 weight part of total amounts of (a) compound, (b) sulfur, and (c) compound.

  The cured product of the present invention has (a) a compound having two or more functional groups capable of reacting with the compound or (a) one functional group capable of reacting with the compound and one or more other functional groups capable of homopolymerization. It can also be produced by curing polymerization with a polymerizable compound such as a compound. Examples of these compounds include known compounds having a thiirane ring, polyvalent carboxylic acid anhydrides, compounds having an unsaturated group, etc., and these may be used alone or in combination of two or more.

  Further, the optical material composition according to the present invention is not limited to these, and includes (a) compound oligomers, solvents and acids used in the synthesis, unreacted raw materials, and by-products as long as they do not become a problem. Good.

  In addition, when the optical material composition of the present invention is polymerized and cured to obtain an optical material, it can be obtained by adding known additives such as an antioxidant, an ultraviolet absorber, a yellowing inhibitor, a bluing agent, and a pigment. Of course, it is possible to further improve the practicality of optical materials. When the resin composition for optical materials 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 improve the adhesion between the obtained optical material and the mold. It is also possible to improve control. Examples of the adhesion improver include known silane coupling agents and titanate compounds, and these may be used alone or in combination of two or more. The addition amount is 0.0001 to 5 parts by weight with respect to 100 parts by weight of the total amount of (a) compound, (b) sulfur and (c) compound. On the contrary, when the resin composition for optical materials of the present invention is difficult to peel off from the mold after polymerization, it is possible to use or add a known external and / or internal mold release agent to release the optical material from the mold. It is also possible to improve. Release agents include fluorine-based nonionic surfactants, silicon-based nonionic surfactants, alkyl quaternary ammonium salts, phosphate esters, acidic phosphate esters, oxyalkylene-type acidic phosphate esters, alkali metal salts of acidic phosphate esters, oxy Alkali metal salts of acidic phosphates, metal salts of higher fatty acids, higher fatty acid esters, paraffins, waxes, higher aliphatic amides, higher aliphatic alcohols, polysiloxanes, aliphatic amine ethylene oxide adducts, etc. May be used alone or in combination of two or more. The addition amount is 0.0001 to 5 parts by weight with respect to 100 parts by weight of the total amount of (a) compound, (b) sulfur and (c) compound.

  The method for producing the optical material of the present invention will be described in more detail as follows. The above-mentioned main raw materials, auxiliary raw materials and antioxidants, ultraviolet absorbers, polymerization catalysts, radical polymerization initiators, adhesion improvers, mold release agents, etc. can all be mixed in the same container with stirring at the same time. Each raw material may be added and mixed in stages, or several components may be separately mixed and then remixed in the same container. The main raw material, auxiliary raw material and various additives may be mixed in any order.

  (A) Compound and (b) Sulfur may be partially or wholly at −100 to 160 ° C. with or without stirring in the presence or absence of a polymerization catalyst and / or polymerization regulator. It is also possible to prepare the optical material composition after the preliminary reaction for 0.1 to 480 hours. In particular, when the compound in the composition for optical materials contains a solid component and handling is not easy, this preliminary reaction is effective. This preliminary reaction condition is preferably 0.1 to 240 hours at −10 to 120 ° C., more preferably 0.1 to 120 hours at 0 to 100 ° C., and particularly preferably 0.1 to 120 hours at 20 to 80 ° C. 60 hours. By this preliminary reaction, (b) sulfur is preferably reacted at 10% or more (previously 0%) 90% or less, more preferably 30% or more and 80% or less. It is particularly preferable that the reaction be performed at 50% or more and 70% or less. Such a preliminary reaction may be carried out under any atmosphere such as air, presence of a gas such as nitrogen or oxygen, normal pressure or increased pressure, or reduced pressure. When the reaction is performed under reduced pressure, hydrogen sulfide that promotes the reaction is removed as compared to normal pressure, and thus the reaction usually proceeds moderately. In this preliminary reaction, various additives such as (c) a compound, a compound capable of reacting with some or all of the auxiliary raw materials used as a performance improver, and an ultraviolet absorber may be added. . In addition, liquid chromatography and / or a method for measuring viscosity and / or specific gravity and / or refractive index is preferred for this preliminary resin composition for optical materials because of its high sensitivity, and further a method for measuring refractive index. Is most preferable because of its simplicity. These measurements are convenient because the use of an in-line type apparatus can monitor the reaction without time difference. In particular, it is effective because sample removal can be omitted in the case of pressure reduction and pressure sealing. For example, when measuring the refractive index, it is a conventional general technique to sample the resin composition for an optical material and use an Abbe refractometer or a Pullrich refractometer. Can track the response without any time difference. Specifically, the refractive index of the reaction solution can be continuously measured by immersing the detection unit of the refractometer in advance in a resin composition for optical materials that has undergone preliminary reaction or deaeration treatment. . Since the refractive index increases with the progress of the reaction, if the reaction is controlled at a desired refractive index, a constant reaction rate can be obtained with high accuracy, and a homogeneous resin composition for optical materials can be produced.

  Since the refractive index changes depending on the temperature, it is important to control the sample and the detection portion to a constant reference temperature when measuring by sampling. In the case of the in-line method, since the temperature of the detection portion varies, it is necessary to obtain the relationship between the temperature of the detection portion and the refractive index. The relationship between the measurement temperature, the refractive index, and the refractive index at the reference temperature can be easily obtained by multiple regression. Therefore, it is preferable to use a refractometer provided with a temperature correction function that can be automatically converted to the refractive index of the reference temperature.

  Examples of the inline refractometer include, but are not limited to, a method in which a light emitting diode is used as a light source and the angle of prism reflected light is identified by a CCD cell.

  In the method for producing an optical material of the present invention, it is of course possible to further improve the practicality of the resulting optical material by adding additives such as known antioxidants, bluing agents, ultraviolet absorbers, deodorants and the like. Is possible.

  In the present invention, the composition for optical material is degassed in advance, thereby achieving high transparency of the optical material, which is the subject of the present invention. Deaeration treatment is performed before, during or after mixing (a) compound, (b) sulfur, (c) compound, compound capable of reacting with some or all of the composition components, polymerization catalyst, polymerization regulator, and additive. , Under reduced pressure. Preferably, it is performed under reduced pressure during or after mixing. The treatment conditions are 0 to 100 ° C. under a reduced pressure of 0.001 to 50 Torr for 1 minute to 24 hours. The degree of vacuum is preferably 0.005 to 25 Torr, more preferably 0.01 to 10 Torr, and the degree of vacuum may be varied within these ranges. The deaeration time is preferably 5 minutes to 18 hours, more preferably 10 minutes to 12 hours. The temperature at the time of deaeration is preferably 5 ° C to 80 ° C, more preferably 10 ° C to 60 ° C, and the temperature may be varied within these ranges. In the deaeration treatment, renewing the interface of the composition for optical material by stirring, blowing of gas, vibration by ultrasonic waves, etc. is a preferable operation for enhancing the deaeration effect.

  In the present invention, the main component removed by the degassing treatment is hydrogen sulfide, unlike water and carbon dioxide gas, which are the purpose of removal in the prior art. A high degree of transparency of the obtained optical material is ensured by the deaeration treatment under the conditions found in the present invention that can remove hydrogen sulfide at a certain level. In addition, other dissolved gases and low-boiling substances such as low-molecular mercaptans may be removed, but the effect of the present invention is not greatly affected. When the deaeration treatment is insufficient outside the scope of the present invention, that is, when the degree of vacuum and / or time and / or temperature is insufficient, a high degree of transparency cannot be obtained. On the other hand, when the degassing treatment is excessive outside the scope of the present invention, when the degree of vacuum and / or the time and / or temperature is excessive, the resin composition for optical material is thickened, gelled, rapidly polymerized, Causes color deterioration.

Further, the refractive index (n _D (20 ° C.)) of the resin composition for an optical material after completion of the deaeration treatment is increased by 0.001 to 0.002 immediately after the completion of the deaeration treatment, and then injected into the lens mold and cured. By doing so, an optical material having a high refractive index without optical distortion and striae can be obtained (third step).

  Liquid chromatography and / or measuring viscosity and / or specific gravity and / or refractive index of the composition for optical material to be degassed are preferable for confirming the degassing effect and producing a certain optical material. . Among them, the method for measuring the viscosity and / or the refractive index is preferable because of high sensitivity, and the method for measuring the refractive index is most preferable because the method is simple. In this case as well, the use of an inline refractometer is effective because it can track the degree of deaeration without time difference. Specifically, since the refractive index increases due to deaeration, if the deaeration is controlled with a desired refractive index, the deaeration process can be managed with high accuracy, and a homogeneous optical material can be manufactured.

  In this case as well, as in the case of the preliminary reaction, the refractive index changes depending on the temperature. Therefore, when sampling and measuring, it is important to control the sample and the detection portion to a constant reference temperature. An in-line refractometer can be suitably used in the operation method.

  The holding temperature in the third step of the reaction composition after completion of the degassing treatment (second step) is not particularly limited as long as it is in a temperature range that does not hinder the casting operation, and preferably 10 ° C to At 30 ° C, 15 ° C to 25 ° C is particularly preferable. The holding time in the third step is preferably 1 hour to 6 hours, more preferably 2 hours to 5 hours, and particularly preferably 3 hours to 5 hours.

  In the third step, a cured product having no striae is obtained by cast polymerization after raising the refractive index by 0.001 to 0.002 from the refractive index after completion of the deaeration treatment (second step). When the refractive index is increased beyond 0.002, casting unevenness occurs. Accordingly, the refractive index increase in the third step is preferably 0.001 to 0.002, more preferably 0.001 to 0.0015, and then cast polymerization is performed, and then a cured product having no striae. Is obtained.

  Details of the manufacturing method of the optical material are as follows. (A) compound, (b) sulfur, (c) compound, compound capable of reacting with some or all of the composition components, polymerization catalyst, polymerization regulator, adhesion improver or mold release improver, antioxidant, Additives such as bluing agents, ultraviolet absorbers, deodorants, and various performance improving additives can all be mixed in the same container at the same time under stirring or by adding each raw material in stages. The components may be mixed separately and then remixed in the same container. Each raw material and additive may be mixed in any order. Furthermore, two or more types of each component may be mixed after the preliminary reaction is performed by the above-described method in advance. In mixing, the set temperature, the time required for this, etc. may basically be any conditions that allow the components to be sufficiently mixed. However, excessive temperature and time may cause undesirable reactions between the raw materials and additives. This is not suitable because it causes a viscosity increase and makes the casting operation difficult. The mixing temperature should be about −50 ° C. to 100 ° C., preferably −30 ° C. to 70 ° C., more preferably −5 ° C. to 50 ° C. The mixing time is 1 minute to 12 hours, preferably 5 minutes to 10 hours, and most preferably about 5 minutes to 6 hours. If necessary, the active energy rays may be blocked and mixed. Thereafter, the deaeration process is performed by the above-described method. Furthermore, filtering and purifying these optical material compositions and / or raw materials before mixing with a filter having a pore size of about 0.05 to 10 μm further improves the quality of the optical material of the present invention. Is also preferable. After injection into a glass or metal mold, polymerization and curing are performed with an electric furnace or an active energy ray generator. The polymerization time is 0.1 to 100 hours, usually 1 to 48 hours, and the polymerization temperature is −10. ˜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 to 100 ° C./h, lowering the temperature by 0.1 to 100 ° C./h, and combinations thereof. Further, after the polymerization is completed, annealing the optical material at a temperature of 50 to 150 ° C. for about 5 minutes to 5 hours is a preferable process for removing distortion of the optical material. Further, if necessary, surface treatment such as dyeing, hard coating, antireflection, antifogging and impact resistance can be performed.

  Among the above reaction compositions, it is considered that a part of the oligomer having an increased molecular weight precipitates in the liquid depth portion (lower surface side) of the lens mold to form striae. In order to avoid this, for the semi-finished lens, the lens mold in which the resin composition for optical material is injected has a surface having desired optical characteristics on the upper side, and a curing reaction is performed to cause striae on the lower surface side. It can be removed by grinding, polishing, and producing an optical material having a high degree of transparency (fourth step).

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The striae of the obtained optical material was evaluated by the following method.

  The striae was visually evaluated by applying light from a high-pressure mercury lamp to the cured product in a dark room. The case where there was no striae or the striae occurred on the side of the surface having no optical characteristics was marked with ◯, and the ones where striae occurred and remained after grinding and polishing were marked with x.

Example 1
(1) Step: In a reaction flask equipped with an inline refractometer, 85 parts by weight of bis (β-epithiopropyl) sulfide (hereinafter referred to as a-1 compound) and 15 parts by weight of sulfur are mixed at 60 ° C. for 30 minutes. And uniform. Subsequently, 0.5 part by weight of 2-methyl-N-methylimidazole was added to make a homogeneous solution under a reduced pressure of 1 Torr, and the reaction at 60 ° C. was followed by a refractometer. The value of the refractometer (n _D , 20 (C conversion value) was confirmed to be 1.6570 (sulfur reaction rate: 50%), and then cooled to 20 ° C., and the refractive index value was 1.6580 ± 0.0001. The reaction solution obtained here is called a preliminary reaction solution.
(2) Step: Subsequently, 93 parts by weight of the preliminary reaction solution, 5 parts by weight of bis (2-mercaptoethyl) sulfide (hereinafter referred to as c-1 compound), 0.02 part by weight of triethylbenzylammonium chloride, 0. 3 parts by weight were mixed well at 20 ° C. to obtain a uniform solution. The obtained composition for an optical material was degassed for 1 Torr and 1 hour, and it was confirmed that the refractive index was the same as 1.6580 ± 0.0001.
(3) Step: Step (2) In order to increase the refractive index of the resin composition for an optical material by 0.001 after degassing, it was held at 20 ° C. for 3 hours. The refractive index of 1.6590 was confirmed and the process was terminated.
(4) Step; Step (3) Step The resin composition for optical material is injected into a mold (mold 1) composed of two glass plates and a tape and having a edge thickness of 10 mm, a center thickness of 15 mm, and a mold diameter of 75 mm. The mixture was heated at 15 ° C. for 20 hours, heated to 100 ° C. at a constant rate over 17 hours, and finally heated at 100 ° C. for 2 hours to be polymerized and cured. After standing to cool, it was released from the mold to obtain a cured optical material. The obtained optical material was annealed at 120 ° C. for 30 minutes to remove the strain caused by mold release. Table 1 shows the results of striae of the obtained optical material.

Examples 2-4
Example 1 was repeated except that the holding temperature and holding time are shown in Table 1. Table 1 shows the results of striae of the obtained optical material.

Example 5
Example 1 was repeated except that the edge thickness of the mold used was 14 mm, the center thickness was 10 mm, and the mold diameter was 80 mm (mold 2). Table 1 shows the results of striae of the obtained optical material.

Example 6
Example 1 was repeated except that the refractive index and sulfur reaction rate of the preliminary reaction liquid are shown in Table 1. Table 1 shows the results of striae of the obtained optical material.

Example 7
bis (β-epithiopropyl) disulfide (hereinafter referred to as a-2 compound) was used in place of the a-1 compound, and the refractive index of the preliminary reaction liquid and the refractive index after degassing were shown in Table 1 Example 1 was repeated.

Example 8
Instead of c-1 compound, bis (2,3-dimercaptopropyl) sulfide (hereinafter referred to as c-2 compound) was used, and the refractive index of the pre-reaction solution and the refractive index after deaeration are shown in Table 1. Example 1 was repeated except that.

Comparative Example 1
Example 1 was repeated except that the refractive index after holding at 20 ° C. for 30 minutes after degassing was increased by 0.0005 from that after degassing. The obtained optical material was striae throughout.

Comparative Example 2
Example 1 was repeated except that the refractive index after holding at 20 ° C. for 8 hours after degassing was increased by 0.003 from that after degassing. The obtained optical material was striae throughout.

Comparative Example 3
Comparative Example 1 was repeated except that the refractive index of the preliminary reaction solution, the sulfur reaction rate, and the mold are shown in Table 1.

Comparative Example 4
Instead of the a-1 compound, bis (β-epithiopropyl) disulfide (hereinafter referred to as a-2 compound) is used, the refractive index of the pre-reaction solution, after degassing and after holding at 20 ° C. for 30 minutes Example 1 was repeated except that the rates are shown in Table 1.

Comparative Example 5
Instead of c-1 compound, bis (2,3-dimercaptopropyl) sulfide (hereinafter referred to as c-2 compound) is used, and the refractive index of the pre-reaction solution, after degassing and after holding at 20 ° C. for 30 minutes Example 1 was repeated, except that the refractive index of is shown in Table 1.

Claims (2)

(A) a compound represented by the following formula (1):

(M represents an integer of 0 to 4, n represents an integer of 0 to 2)
(B) sulfur,
(C) In a method for producing an optical material for polymerizing a resin composition for an optical material comprising a compound having at least one mercapto group and one sulfide bond per molecule,
(1) A mixture of (a) a compound and (b) sulfur is reacted at 0 to 100 ° C. under a reduced pressure of 0.001 to 50 Torr for 1 minute to 24 hours, and (b) 50% or more of sulfur ( A step of reacting 90% or less)
(2) Next, adding the compound (c) and vacuum degassing at 0 to 100 ° C. for 1 minute to 24 hours under a reduced pressure of 0.001 to 50 Torr,
(3) The refractive index of the resin composition for optical materials (nD) is maintained by maintaining the resin composition for optical materials after the completion of the step (2) at 10 ° C. to 30 ° C. for 1 to 6 hours without degassing. (20 ° C)) is increased 0.001 to 0.002 immediately after the end of the deaeration process,
(4) A method for producing an optical material, wherein the resin composition for an optical material is poured into a lens mold and polymerized and cured. The method for producing an optical material according to claim 1, wherein the optical material is a semi-finished lens.