Polythiol composition, preparation method therefor and use thereof, and optical material

Abstract

A polythiol composition, comprising 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having a structure represented by general formula (II); wherein any one of R1 and R2 is -SH, and the other is -OH; and the mass content of the impurity having the structure represented by general formula (II) is less than or equal to 8.0%. By controlling the content of the impurity (II) in the polythiol composition mainly composed of 2,3-dithio(2-mercapto)-1-propanethiol, the refractive index of the composition is improved and stabilized, and the quality of the optical material prepared from the polythiol composition is further improved.

Description

A polythiol composition and its preparation method, application, and optical material

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 5, 2024, with application number 202410018603.8 and invention name “A polythiol composition, its preparation method, application, and an optical material”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention belongs to the technical field of preparation of 2,3-dithio(2-mercapto)-1-propanethiol, and relates to a polythiol composition, a preparation method thereof, an application thereof, and an optical material, and in particular to a polythiol composition, a preparation method thereof, an application of the polythiol composition in the preparation of an optical material, and an optical material. Background Art

[0003] Transparent plastic materials, with their advantages of light weight, strong toughness, and easy dyeing, have become increasingly popular in the preparation of various optical materials in recent years. For example, applications in eyewear and lenses require high transparency, low yellowing, high heat resistance, high strength, and a high refractive index and Abbe number. A high refractive index allows for thinner lens walls, while a high Abbe number reduces chromatic aberration. Polythiourethane optical resin materials, which exhibit these excellent properties, have been the subject of significant research in recent years. These resins are primarily produced using polythiol compounds and polyisocyanates as raw materials.

[0004] Currently, most polythiourethane optical resin materials are prepared from a polythiol compound having the following formula (chemical name: 2,3-dithio(2-mercapto)-1-propanethiol) and polyisocyanate. The resulting resin is a thermosetting resin.

[0005] The specific preparation method of this resin material includes: first, using tape to bond two glass molds together, leaving a certain distance between the two molds, typically about 2 mm between the centers. Then, polythiol, polyisocyanate, and additives are mixed and degassed to obtain a prepolymer. The tape is removed from the mold, and the prepolymer is poured into the mold. The tape is then affixed, cured, and demolded to obtain the resin material.

[0006] However, in actual production and preparation, the polythiourethane optical resin lens is prone to problems such as low refractive index and high lens material grain rate.

[0007] Therefore, how to find a more appropriate way to solve the above-mentioned problems existing in the current 2,3-dithio (2-mercapto)-1-propanethiol polythiourethane optical resin lenses has become one of the urgent issues to be solved by many front-line researchers in the industry. Summary of the Invention

[0008] In view of this, the technical problem to be solved by the present invention is to provide a polythiol composition, its preparation method, application, and an optical material. By controlling the refractive index and reactivity of the polythiol composition to be stable within a certain range, the present invention further ensures that the refractive index of lenses prepared using the polythiol composition of the present invention is qualified and stable, and the lenses are free of internal material cracks, thereby ensuring the application quality of the polythiol composition.

[0009] The present invention provides a polythiol composition comprising 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having a structure represented by formula (II);

[0010] wherein either one of R1 and R2 is -SH and the other is -OH;

[0011] The mass content of the impurity having the structure represented by formula (II) is ≤8.0%.

[0012] The present invention provides a method for preparing the polythiol composition as described in the above technical solution, comprising the following steps:

[0013] 1) After mercaptoethanol and alkali solution are mixed, epichlorohydrin is added to react, and then hydrochloric acid and thiourea are added to carry out a thiourea salt process, followed by hydrolysis to obtain a crude product of 2,3-dithio(2-mercapto)-1-propanethiol;

[0014] 2) post-treating the crude 2,3-dithio(2-mercapto)-1-propanethiol obtained in the above step to obtain 2,3-dithio(2-mercapto)-1-propanethiol;

[0015] The polythiol composition is a main product of 2,3-dithio (2-mercapto)-1-propanethiol and impurities generated during the preparation process.

[0016] Preferably, the alkali solution comprises sodium hydroxide solution;

[0017] The reaction temperature is 10-70°C;

[0018] The reaction time is 100 to 240 minutes;

[0019] The thiourea salting time is 90 to 360 minutes;

[0020] The post-treatment steps include one or more steps of acid washing, water washing, water removal and filtration.

[0021] The present invention provides an application of a polythiol composition in the preparation of an optical material;

[0022] The polythiol composition includes 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having a structure represented by formula (II);

[0023] wherein either one of R1 and R2 is -SH and the other is -OH;

[0024] The mass content of the impurity having the structure represented by formula (II) is ≤8.0%.

[0025] Preferably, in the polythiol composition, the purity of 2,3-dithio(2-mercapto)-1-propanethiol is 88% to 96%;

[0026] The polythiol composition is a composition containing a plurality of polythiol compounds;

[0027] The raw materials for preparing the optical material also include polyisocyanate;

[0028] The molar ratio of -SH in the polythiol composition to -NCO in the polyisocyanate is (0.8-1.2):1;

[0029] The mass content of the impurity having the structure represented by formula (II) is 0.1% to 8%.

[0030] Preferably, the raw materials for preparing the optical material further include another polythiol compound and a catalyst;

[0031] The raw materials for preparing the optical material also include auxiliary agents;

[0032] The optical material includes an optical lens;

[0033] The optical lens is specifically a polythiourethane optical resin optical lens;

[0034] The application is specifically to increase the refractive index of optical lenses and / or reduce the material grain defect rate of optical lenses.

[0035] The present invention also provides an optical material, which is prepared from a polythiol composition and polyisocyanate as raw materials;

[0036] The polythiol composition is the polythiol composition described in the above technical solution, the polythiol composition prepared by the preparation method described in any one of the above technical solutions, or the polythiol composition in the application described in any one of the above technical solutions.

[0037] Preferably, the polyisocyanate is selected from tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl-m-xylylene diisocyanate, dipropyl disulfide, diethyl disulfide, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5- One or more of diisocyanate-1,4-dithiane, dihexylthiodiisocyanate, dipropylthiodiisocyanate, bis(isocyanatomethyl)adamantane, bis(isocyanatomethyl)tetrahydrothiophene, 2,6-bis(isocyanatomethyl)naphthalene, 1,5-naphthalene diisocyanate, diethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenylether diisocyanate, and triphenylmethane triisocyanate;

[0038] The raw materials also include another polythiol compound;

[0039] The additional polythiol compound is selected from the group consisting of 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, methanedithiol, methanetrithiol, bis(2-mercaptoethyl)ether, tetrakis(mercaptomethyl)methane, 1,2-dimercaptopropane, 1,3-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, 2,2-dimercaptopropane, 1,2-bis(2-mercaptoethoxy)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 2,3-dimercapto-1 -Propanol, 1,2-dimercaptoethane, 1,3-dimercapto-2-propanol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptobutane, 1,2,3-trimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, bis(2-mercaptoethyl) sulfide, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(2-mercaptoacetate), 1,4-butanediol bis(2-mercaptoacetate), trimethylolpropane trimercaptopropionate, pentaerythritol tetramercaptoacetate, diethylene glycol bis(3-mercaptopropionate), pentaerythritol tetramercaptoacetate tetramercaptopropionate, 1,2-dimercaptocyclohexane, 1,1,1-tris(mercaptomethyl)propane, 1,4-butanediol bis(3-mercaptopropionate), 1,3-dimercaptocyclohexane, trimethylolpropane trimercaptoacetate, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, bis(4-mercaptophenyl)sulfone, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis(2-mercaptoethylthiomethyl)-1,4-dithiane, 2,5-dimercaptomethyl-1-thiane, 2,5-dimercaptoethyl-1-thiane, 2,5-dimercaptomethylthiophene, bis(4-mercaptophenyl)sulfide, 1,2-dimercaptobenzene, One or more of 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,3-bis(mercaptomethyl)benzene, 2,5-dimercaptomethyl-1,4-dithiane, 1,4-bis(mercaptomethyl)benzene, 2,2'-dimercaptobiphenyl, bis(4-mercaptophenyl)methane, 2,2-bis(4-mercaptophenyl)propane, 4,4'-dimercaptobiphenyl, bis(4-mercaptophenyl)ether, bis(4-mercaptomethylphenyl)methane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 2,2-bis(4-mercaptomethylphenyl)propane, bis(4-mercaptomethylphenyl)ether, bis(4-mercaptomethylphenyl)sulfide, 2,5-dimercapto-1,3,4-thiadiazole, and 3,4-thiophenedithiol;

[0040] The molar ratio of the total molar number of -SH in the polythiol composition and another polythiol compound to the molar ratio of -NCO in the polyisocyanate is (0.8-1.2):1.

[0041] Preferably, the molar ratio of -SH in the polythiol composition to -NCO in the polyisocyanate is (0.8-1.2):1;

[0042] The raw materials also include a catalyst;

[0043] The catalyst is one or more of dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide and stannous octoate;

[0044] The catalyst is 0.001% to 0.2% of the total mass of the raw materials, and the raw materials also include additives;

[0045] The raw materials also include auxiliary agents;

[0046] The auxiliary agent includes one or more of a release agent, an ultraviolet absorber, a toner and a release agent.

[0047] Preferably, the preparation method includes polymerization and curing;

[0048] The temperature rise program of the polymerization curing is:

[0049] Keep warm at 25-35°C for 175-185 min, increase the temperature to 43-47°C at a heating rate of 0.83-1.25°C / 10 min, increase the temperature to 48-52°C at a heating rate of 0.42-0.56°C / 10 min, increase the temperature to 58-62°C at 0.57-0.83°C / 10 min, increase the temperature to 115-125°C at 2.00-2.50°C / 10 min, and keep warm at 115-125°C for 180-240 min.

[0050] The present invention provides a polythiol composition comprising 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having a structure represented by formula (II); wherein either R1 or R2 is -SH and the other is -OH; and the mass content of the impurity having the structure represented by formula (II) is ≤8.0%. Compared with the prior art, the present invention addresses the aforementioned problems existing in the actual production of 2,3-dithio(2-mercapto)-1-propanethiol. Research indicates that a small amount of impurities are generated during the actual production of the polythiol compound. One important impurity has a structure represented by formula (II) and contains a hydroxyl functional group. Its sulfur content is 52.5%, which is lower than that of the polythiol compound having the main structure represented by formula (I) (sulfur content is 61.5%). When the impurity content is too high, the refractive index of the composition decreases, further resulting in a lower refractive index of the prepared lens. However, the curvature and degree of resin lens molds currently on the market are fixed. If the refractive index is reduced significantly, the degree of the prepared lenses will exceed the standard requirements and become unqualified products. At the same time, the reactivity of hydroxyl groups and isocyanates is higher than that of thiol groups. The increase in impurity content will cause the reaction rate of the polythiol composition and isocyanate to increase, further causing the viscosity of the prepolymer to increase. Material lines will appear when the material with high viscosity is poured into the mold. This is because the material has high viscosity and poor fluidity, which makes it easy to mix unevenly during the casting process.

[0051] Based on this, the present invention studies the relationship between impurity content and refractive index, viscosity, and lens grain defect rate, determines the control range of impurity content, and provides a polythiol composition containing 2,3-dithio(2-mercapto)-1-propanethiol and a specific amount of an impurity having the structure represented by formula (II). Through the present invention, the refractive index and reactivity of the polythiol combination can be controlled to be stable within a certain range. Furthermore, lenses prepared using the polythiol composition of the present invention have a qualified and stable refractive index and are free of grain inside the lenses, thus ensuring the application quality of the polythiol composition.

[0052] The present invention controls the content of impurities having a structure represented by formula (II) in a polythiol composition containing 2,3-dithio(2-mercapto)-1-propanethiol as a main component, thereby increasing and stabilizing the refractive index of the composition, significantly reducing the problem of internal graining in lenses, improving the yield rate, and further improving the quality of optical materials prepared from the polythiol composition. DETAILED DESCRIPTION

[0053] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0054] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0055] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with conventional purity in the field of optical resin lens raw material preparation.

[0056] All noun expressions and abbreviations in the present invention are conventional noun expressions and abbreviations in this field. Each noun expression and abbreviation is clear and unambiguous in its relevant application field. Those skilled in the art can clearly, accurately and uniquely understand them based on the noun expressions and abbreviations.

[0057] The present invention provides a polythiol composition (polythiol compound), comprising 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having a structure represented by formula (II);

[0058] wherein either one of R1 and R2 is -SH and the other is -OH;

[0059] The mass content of the impurity having the structure represented by formula (II) is ≤8.0%.

[0060] In the present invention, the polythiol composition can also be specifically defined as a polythiol compound, i.e., a polythiol compound having a structure of formula (I) containing an impurity having a structure represented by formula (II). More specifically, the impurity having a structure represented by formula (II) is generated during the preparation of the polythiol compound.

[0061] In the present invention, the polythiol composition may further include other impurities.

[0062] In the present invention, the mass content of the impurity having the structure represented by formula (II) is ≤8.0%, more preferably ≤7.0%, more preferably ≤6.0%, more preferably ≤5.0%, more preferably ≤4.0%.

[0063] The present invention provides a method for preparing the polythiol composition as described in the above technical solution, comprising the following steps:

[0064] 1) After mercaptoethanol and alkali solution are mixed, epichlorohydrin is added to react, and then hydrochloric acid and thiourea are added to carry out a thiourea salt process, followed by hydrolysis to obtain a crude product of 2,3-dithio(2-mercapto)-1-propanethiol;

[0065] 2) The crude 2,3-dithio(2-mercapto)-1-propanethiol obtained in the above step is post-treated to obtain 2,3-dithio(2-mercapto)-1-propanethiol.

[0066] In the present invention, the polythiol composition is the main product of 2,3-dithio(2-mercapto)-1-propanethiol and impurities generated during the preparation process.

[0067] The method comprises the following steps: firstly mixing mercaptoethanol and alkali solution, then adding epichlorohydrin to carry out reaction, then adding hydrochloric acid and thiourea to carry out thiourea salting process, and then hydrolyzing to obtain a crude product of 2,3-dithio(2-mercapto)-1-propanethiol.

[0068] In the present invention, the alkali solution preferably includes sodium hydroxide solution.

[0069] In the present invention, the reaction temperature is preferably 10 to 70°C, more preferably 20 to 60°C, and even more preferably 30 to 50°C.

[0070] In the present invention, the reaction time is preferably 100 to 240 min, more preferably 130 to 210 min, and even more preferably 160 to 190 min.

[0071] In the present invention, the thiourea salting time is preferably 90 to 360 min, more preferably 140 to 310 min, and even more preferably 190 to 260 min.

[0072] Finally, the crude 2,3-dithio(2-mercapto)-1-propanethiol obtained in the above steps is post-treated to obtain 2,3-dithio(2-mercapto)-1-propanethiol.

[0073] In the present invention, the post-treatment step preferably includes one or more steps of acid washing, water washing, water removal and filtration, more preferably multiple steps of acid washing, water washing, water removal and filtration.

[0074] The present invention also provides the use of the polythiol composition in the preparation of optical materials;

[0075] The polythiol composition includes 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having a structure represented by formula (II);

[0076] wherein either one of R1 and R2 is -SH and the other is -OH;

[0077] The mass content of the impurity having the structure represented by formula (II) is ≤8.0%.

[0078] In the present invention, the purity of 2,3-dithio(2-mercapto)-1-propanethiol in the polythiol composition is preferably 88% to 96%, more preferably 90% to 95%, and even more preferably 91% to 94%.

[0079] In the present invention, the polythiol composition is preferably a composition containing a plurality of polythiol compounds, more preferably a composition containing two polythiol compounds, namely a polythiol compound represented by formula (I) and a polythiol compound represented by formula (II).

[0080] In the present invention, the polythiol composition is preferably a composition containing a plurality of polythiol compounds for optical materials.

[0081] In the present invention, the raw materials for preparing the optical material preferably further include polyisocyanate.

[0082] In the present invention, the molar ratio of -SH in the polythiol composition to -NCO in the polyisocyanate is preferably (0.8-1.2):1, more preferably (0.85-1.15):1, more preferably (0.9-1.1):1, and more preferably (0.95-1.05):1.

[0083] In the present invention, the mass content of the impurity having the structure represented by formula (II) is preferably 0.1% to 8%, more preferably 0.2% to 7%, more preferably 0.3% to 6%, and more preferably 0.4% to 5%.

[0084] In the present invention, the raw materials for preparing the optical material preferably further include another polythiol compound and a catalyst.

[0085] In the present invention, the raw materials for preparing the optical material preferably further include an auxiliary agent.

[0086] In the present invention, the optical material preferably includes an optical lens.

[0087] In the present invention, the optical lens preferably includes an optical lens made of a polythiourethane optical resin material.

[0088] In the present invention, the application is preferably specifically an application in improving the refractive index of an optical lens and / or reducing the defective rate of material grain of an optical lens.

[0089] The present invention provides an optical material, which is prepared from a polythiol composition and polyisocyanate as raw materials;

[0090] The polythiol composition is the polythiol composition described in the above technical solution, the polythiol composition prepared by the preparation method described in any one of the above technical solutions, or the polythiol composition in the application described in any one of the above technical solutions.

[0091] In the present invention, the polyisocyanate is preferably selected from tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl-m-xylylene diisocyanate, dipropyl disulfide, diethyl disulfide, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-diisocyanate, Thiane, 2,5-diisocyanate-1,4-dithiane, dihexylthiodiisocyanate, dipropylthiodiisocyanate, bis(isocyanatomethyl)adamantane, bis(isocyanatomethyl)tetrahydrothiophene, 2,6-bis(isocyanatomethyl)naphthalene, 1,5-naphthalene diisocyanate, diethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, and triphenylmethane triisocyanate One or more of esters, more preferably tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl-m-xylylene diisocyanate, dipropyl disulfide, diethyl disulfide, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5-diisocyanate-1,4-dithiane, dihexylthiodiisocyanate, dipropylthiodiisocyanate, bis(isocyanatomethyl)adamantane, bis(isocyanatomethyl)tetrahydrothiophene, 2,6-bis(isocyanatomethyl)naphthalene, 1,5-naphthalene diisocyanate, diethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenylether diisocyanate, or triphenylmethane triisocyanate.

[0092] In the present invention, the raw material preferably further comprises another polythiol compound.

[0093] In the present invention, the additional polythiol compound is preferably selected from 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, methanedithiol, methanetrithiol, bis(2-mercaptoethyl)ether, tetrakis(mercaptomethyl)methane, 1,2-dimercaptopropane, 1,3-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, 2,2-dimercaptopropane, 1,2-bis(2-mercaptoethoxy)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 2,3-dimercapto-1-propanol, 1,2-dimercapto-2-propanol, 1,2-dimercapto-1-propanol, 1,2-dimercapto-3,6,9-trithiaundecane, 1,2-dimercapto-2-propanol, 1,2-dimercapto-3,6,9-trithiaundecane, 1,2-dimercapto-3,6,9-trithiaundecane, 1,2-dimercapto-3,6,9-trithiaundecane, 1,2-dimercapto- 2-dimercaptoethane, 1,3-dimercapto-2-propanol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptobutane, 1,2,3-trimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, bis(2-mercaptoethyl) sulfide, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(2-mercaptoacetate), 1,4-butanediol bis(2-mercaptoacetate), trimethylolpropane trimercaptopropionate, pentaerythritol tetramercaptoacetate, diethylene glycol bis(3-mercaptopropionate), pentaerythritol tetramercaptopropionate, 1,2-dimercaptocyclohexane, 1 ,1,1-Tris(mercaptomethyl)propane, 1,4-butanediol bis(3-mercaptopropionate), 1,3-dimercaptocyclohexane, trimethylolpropane trimercaptoacetate, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, bis(4-mercaptophenyl)sulfone, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis(2-mercaptoethylthiomethyl)-1,4-dithiane, 2,5-dimercaptomethyl-1-thiane, 2,5-dimercaptoethyl-1-thiane, 2,5-dimercaptomethylthiophene, bis(4-mercaptophenyl)sulfide, 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,3-bis(mercaptomethyl)benzene, 2,5 One or more of dimercaptomethyl-1,4-dithiadioic acid, 1,4-bis(mercaptomethyl)benzene, 2,2'-dimercaptobiphenyl, bis(4-mercaptophenyl)methane, 2,2-bis(4-mercaptophenyl)propane, 4,4'-dimercaptobiphenyl, bis(4-mercaptophenyl)ether, bis(4-mercaptomethylphenyl)methane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 2,2-bis(4-mercaptomethylphenyl)propane, bis(4-mercaptomethylphenyl)ether, bis(4-mercaptomethylphenyl)sulfide, 2,5-dimercapto-1,3,4-thiadiazole and 3,4-thiophenedithiol, more preferably 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, methanedithiol, methanetrithiol, bis(2-mercaptoethyl) ether, tetrakis(mercaptomethyl)methane, 1,2-dimercaptopropane, 1,3-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, 2,2-dimercaptopropane, 1,2-bis(2-mercaptoethoxy)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 2,3-dimercapto-1-propanol, 1,2-dimercaptoethane, 1,3-dimercapto-2-propanol, 2-mercaptomethyl-1,3-dimercapto Propane, 2-mercaptomethyl-1,4-dimercaptobutane, 1,2,3-trimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, bis(2-mercaptoethyl) sulfide, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(2-mercaptoacetate), 1,4-butanediol bis(2-mercaptoacetate), trimethylolpropane trimercaptopropionate, pentaerythritol tetramercaptoacetate, diethylene glycol bis(3-mercaptopropionate), pentaerythritol tetramercaptopropionate, 1,2-dimercaptocyclohexane, 1,1,1- Tris(mercaptomethyl)propane, 1,4-butanediol bis(3-mercaptopropionate), 1,3-dimercaptocyclohexane, trimethylolpropane trimercaptoacetate, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, bis(4-mercaptophenyl)sulfone, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis(2-mercaptoethylthiomethyl)-1,4-dithiane, 2,5-dimercaptomethyl-1-thiane, 2,5-dimercaptoethyl-1-thiane, 2,5-dimercaptomethylthiophene, bis(4-mercaptophenyl)sulfide, 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-Dimercaptobenzene, 1,3-bis(mercaptomethyl)benzene, 2,5-dimercaptomethyl-1,4-dithiane, 1,4-bis(mercaptomethyl)benzene, 2,2'-dimercaptobiphenyl, bis(4-mercaptophenyl)methane, 2,2-bis(4-mercaptophenyl)propane, 4,4'-dimercaptobiphenyl, bis(4-mercaptophenyl)ether, bis(4-mercaptomethylphenyl)methane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 2,2-bis(4-mercaptomethylphenyl)propane, bis(4-mercaptomethylphenyl)ether, bis(4-mercaptomethylphenyl)sulfide, 2,5-dimercapto-1,3,4-thiadiazole or 3,4-thiophenedithiol.

[0094] In the present invention, the molar ratio of the total molar number of -SH in the polythiol composition and the other polythiol compounds to the -NCO of the polyisocyanate is preferably (0.8 to 1.2):1, more preferably (0.85 to 1.15):1, more preferably (0.9 to 1.1):1, and more preferably (0.95 to 1.05):1.

[0095] In the present invention, the molar ratio of -SH in the polythiol composition to -NCO in the polyisocyanate is preferably (0.8-1.2):1, more preferably (0.85-1.15):1, more preferably (0.9-1.1):1, and more preferably (0.95-1.05):1.

[0096] In the present invention, the raw materials preferably further include a catalyst.

[0097] In the present invention, the catalyst is preferably one or more of dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide and stannous octoate, more preferably dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide or stannous octoate.

[0098] In the present invention, the catalyst accounts for 0.001% to 0.2% of the total mass of the raw materials. The raw materials preferably also include an auxiliary agent.

[0099] In the present invention, the raw materials preferably further include auxiliary agents.

[0100] In the present invention, the auxiliary agent preferably includes one or more of a release agent, an ultraviolet absorber, a toner and a release agent, and more preferably includes a release agent, an ultraviolet absorber, a toner or a release agent.

[0101] In the present invention, the preparation method preferably includes polymerization and curing.

[0102] In the present invention, the temperature rise program for polymerization and curing is preferably:

[0103] The temperature is kept at 25-35°C for 175-185 min, and the temperature is increased to 43-47°C at a heating rate of 0.83-1.25°C / 10 min, and then the temperature is increased to 48-52°C at a heating rate of 0.42-0.56°C / 10 min, and then the temperature is increased to 58-62°C at 0.57-0.83°C / 10 min, and then the temperature is increased to 115-125°C at 2.00-2.50°C / 10 min, and then the temperature is kept at 115-125°C for 180-240 min, more preferably, the temperature is kept at 27-33°C for 177-183 min, and the temperature is increased to 43.5-46.5°C at a heating rate of 0.93-1.15°C / 10 min, and then the temperature is increased to 48.5-51.5 at a heating rate of 0.45-0.53°C / 10 min, and then the temperature is increased to 58.5-51.5 ℃, then heat it to 58.5-61.5℃ at a rate of 0.62-0.78℃ / 10min, then heat it to 117-123℃ at a rate of 2.10-2.40℃ / 10min, and then keep it at 117-123℃ for 190-230min, more preferably keep it at 29-31℃ for 179-181min, heat it to 44-46℃ at a rate of 0.98-1.10℃ / 10min, then heat it to 49-51℃ at a rate of 0.48-0.50℃ / 10min, then heat it to 59-61℃ at a rate of 0.67-0.73℃ / 10min, then heat it to 119-121℃ at a rate of 2.20-2.30℃ / 10min, and then keep it at 119-121℃ for 200-220min.

[0104] The present invention is a complete and detailed overall technical solution that further reduces the lens material grain rate, improves the lens refractive index and the product quality of the lens. The above-mentioned polythiol composition and its preparation method, the use of the polythiol composition in the preparation of optical materials, and an optical material can specifically include the following contents:

[0105] The present invention provides a polythiol composition, the main component structure of which is shown in Formula I, characterized in that the impurity content in the polythiol composition is ≤8.0%;

[0106] The molecular structure of the impurity is shown in Formula II;

[0107] In formula II, one of the R1 and R2 functional groups is -SH and the other is -OH.

[0108] Specifically, the content of impurities of the structure of formula II in the polythiol composition is ≤6.0%.

[0109] The present invention provides a composition for an optical material, comprising the polythiol composition described in the above technical solution and polyisocyanate.

[0110] Specifically, the polyisocyanate is selected from tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl-m-xylylene diisocyanate, dipropyl disulfide, diethyl disulfide, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5 - diisocyanate-at least one of 1,4-dithiane, dihexylthiodiisocyanate, dipropylthiodiisocyanate, bis(isocyanatomethyl)adamantane, bis(isocyanatomethyl)tetrahydrothiophene, 2,6-bis(isocyanatomethyl)naphthalene, 1,5-naphthalene diisocyanate, diethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenylether diisocyanate and triphenylmethane triisocyanate.

[0111] Specifically, the optical material composition further includes other polythiol compounds.

[0112] Specifically, the other polythiol compounds are selected from 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, methanedithiol, methanetrithiol, bis(2-mercaptoethyl) ether, tetrakis(mercaptomethyl)methane, 1,2-dimercaptopropane, 1,3-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, 2,2-dimercaptopropane, 1,2-bis(2-mercaptoethoxy)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 2,3-dimercapto Mercapto-1-propanol, 1,2-dimercaptoethane, 1,3-dimercapto-2-propanol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptobutane, 1,2,3-trimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, bis(2-mercaptoethyl) sulfide, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(2-mercaptoacetate), 1,4-butanediol bis(2-mercaptoacetate), trimethylolpropane trimercaptopropionate, pentaerythritol tetramercaptoacetate, diethylene glycol bis(3-mercaptopropionate), Pentaerythritol tetramercaptopropionate, 1,2-dimercaptocyclohexane, 1,1,1-tris(mercaptomethyl)propane, 1,4-butanediol bis(3-mercaptopropionate), 1,3-dimercaptocyclohexane, trimethylolpropane trimercaptoacetate, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, bis(4-mercaptophenyl)sulfone, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis(2-mercaptoethylthiomethyl)-1,4-dithiane, 2,5-dimercaptomethyl-1-thiane, 2,5-dimercaptoethyl-1-thiane, 2,5-dimercaptomethylthiophene, bis(4-mercaptophenyl)sulfide, 1,2-dimercapto at least one of benzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,3-bis(mercaptomethyl)benzene, 2,5-dimercaptomethyl-1,4-dithiane, 1,4-bis(mercaptomethyl)benzene, 2,2'-dimercaptobiphenyl, bis(4-mercaptophenyl)methane, 2,2-bis(4-mercaptophenyl)propane, 4,4'-dimercaptobiphenyl, bis(4-mercaptophenyl)ether, bis(4-mercaptomethylphenyl)methane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 2,2-bis(4-mercaptomethylphenyl)propane, bis(4-mercaptomethylphenyl)ether, bis(4-mercaptomethylphenyl)sulfide, 2,5-dimercapto-1,3,4-thiadiazole, and 3,4-thiophenedithiol.

[0113] Specifically, the molar ratio of -SH in the polythiol composition and other polythiol compounds to -NCO in the polyisocyanate is 0.8:1 to 1.2:1.

[0114] The present invention provides a method for preparing an optical material, which comprises: adding a catalyst in an amount of 0.001% to 0.2% by weight of the total mass of the optical material composition to the optical material composition described in any of the above technical solutions, and performing polymerization and curing.

[0115] Specifically, the catalyst is at least one selected from dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide and stannous octoate.

[0116] Specifically, the amount of the catalyst added is 0.005% to 0.2% based on 100% by mass of the optical material composition.

[0117] Specifically, the mass ratio of the catalyst to the optical material composition is 0.005 to 0.2:100.

[0118] Specifically, the raw materials for preparing the optical material also include auxiliary agents;

[0119] Specifically, other auxiliary agents are added as needed, including at least one of a release agent, an ultraviolet absorber, a toner, and a release agent.

[0120] Specifically, the release agent is polyphosphate.

[0121] The present invention provides a polythiol composition and a preparation method thereof, use of the polythiol composition in the preparation of an optical material, and an optical material.

[0122] In order to further illustrate the present invention, a polythiol composition provided by the present invention, its preparation method, application, and an optical material are described in detail below in conjunction with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are provided only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The scope of protection of the present invention is not limited to the following examples.

[0123] In the following examples and comparative examples

[0124] 1. Refractive index detection: use Abbe refractometer for detection.

[0125] 2. Polymerization heating program

[0126] Keep warm at 30℃ for 180min, increase the temperature to 45℃ at a heating rate of 0.83℃ / 10min, increase the temperature to 50℃ at a heating rate of 0.55℃ / 10min, increase the temperature to 60℃ at 0.83℃ / 10min, increase the temperature to 120℃ at 2.50℃ / 10min, and keep warm at 120℃ for 180min.

[0127] Example 1

[0128] Preparation of polythiol compositions with different impurity contents:

[0129] To a four-necked flask equipped with a thermometer, a stirrer, and a constant-pressure dropping funnel, 156.6 g (2.0 mol) of mercaptoethanol was added. 133.3 g (1.0 mol) of a 30% aqueous sodium hydroxide solution was then added dropwise through the constant-pressure dropping funnel. Similarly, 92.6 g (1.0 mol) of epichlorohydrin was added dropwise through the constant-pressure dropping funnel. After the addition was complete, the mixture was reacted for 30 minutes. Then, 405.6 g (4.0 mol) of 36% hydrochloric acid and 229.8 g (3.0 mol) of thiourea were added and reacted at 110°C for 100-240 minutes to form a thiourea salt. The temperature was lowered to 60°C, and 425.0 g (4.5 mol) of 18% aqueous ammonia was added. Hydrolysis was carried out for 3 hours, and the lower layer was separated to obtain a crude product. The crude product was acid-washed and washed with water, and the water was removed by vacuum evaporation. After precise filtration, a polythiol composition having Formula I as the main component was obtained. Polythiol compositions with different impurity contents were obtained by controlling the thiourea salting time, and the refractive index was measured by Abbe refractometer, as shown in Table 1 below.

[0130] Table 1 Impurity content of polythiol compositions obtained with different thiourea salting times

[0131] Examples 2 to 7

[0132] Optical material preparation

[0133] Add 52.0 parts by mass of xylene diisocyanate into the batching kettle, add 0.01 parts by mass of catalyst (dibutyltin dichloride) and 0.08 parts by mass of release agent (polyphosphate), and stir and dissolve at 15°C; add 48.0 parts by mass of a polythiol composition with impurity contents of 7.6%, 5.7%, 4.5%, 3.1%, 1.7% and 0.4% respectively, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and degassing time for 0.5h to prepare a mixed solution, pour the solution into a glass mold, and place it flat on a tray after pouring. Put it in an oven for programmed temperature curing. After completion, take out the mold and open the mold to obtain an optical lens, and test the refractive index, lens degree, and material grain defect rate.

[0134] Comparative Examples 1 to 3

[0135] Optical material preparation

[0136] Add 52.0 parts by mass of xylylene diisocyanate, 0.01 parts by mass of catalyst (dibutyltin dichloride) and 0.08 parts by mass of release agent (polyphosphate) into the batching kettle, and stir and dissolve at 15°C; add 48.0 parts by mass of a polythiol composition with impurity contents of 15.3%, 10.9% and 8.5% respectively, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and degassing time for 0.5h to prepare a mixed solution, pour the solution into a glass mold, and place it flat on a tray after pouring. Put it into an oven for programmed temperature curing. After completion, take out the mold and open the mold to obtain an optical lens, and test the refractive index, lens power, and material grain defect rate.

[0137] See Table 2, which shows the specific data of the optical lenses prepared in Examples 2 to 7 and Comparative Examples 1 to 3 of the present invention.

[0138] Table 2

[0139] Examples 8 to 13

[0140] Preparation of optical materials:

[0141] Add 49.8 parts by mass of hydrogenated xylylene diisocyanate into the batching kettle, add 0.10 parts by mass of catalyst (dibutyltin dichloride) and 0.10 parts by mass of release agent (polyphosphate), and stir and dissolve at 15°C; add 30.2 parts by mass of polythiol composition with impurity contents of 7.6%, 5.7%, 4.5%, 3.1%, 1.7% and 0.4% respectively, and 20.0 parts by mass of pentaerythritol tetramercaptopropionate, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and degassing time for 0.5h to prepare a mixed solution, which is then poured into a mold. Place in an oven for programmed temperature curing, remove the mold and open the mold. After completion, remove the mold and open the mold to obtain an optical lens, and test the refractive index, lens power, and material grain defect rate.

[0142] Comparative Examples 4 to 6

[0143] Preparation of optical materials:

[0144] Add 49.8 parts by mass of hydrogenated xylylene diisocyanate, 0.10 parts by mass of catalyst (dibutyltin dichloride) and 0.10 parts by mass of release agent (polyphosphate) into the batching kettle, and stir and dissolve at 15°C; add 30.2 parts by mass of polythiol composition with impurity contents of 15.3%, 10.9% and 8.5% respectively, and 20.0 parts by mass of pentaerythritol tetramercaptopropionate, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and degassing time for 0.5h to prepare a mixed solution, which is then poured into a mold. Place in an oven for programmed temperature curing, remove the mold and open the mold. After completion, remove the mold and open the mold to obtain an optical lens, and test the refractive index, lens power, and material grain defect rate.

[0145] See Table 3, which shows the specific data of the optical lenses prepared in Examples 8 to 13 of the present invention and Comparative Examples 4 to 6.

[0146] Table 3

[0147] Application Example 14

[0148] Preparation of optical materials:

[0149] Add 22.8 parts by mass of hexamethylene diisocyanate, 10.0 parts by mass of isophorone diisocyanate, 16.0 parts by mass of hydrogenated xylylene diisocyanate, 0.15 parts by mass of a catalyst (dibutyltin dichloride), and 0.10 parts by mass of a release agent (polyphosphate) to a batching kettle and stir to dissolve at 15°C. Then add 33.0 parts by mass of a polythiol composition with an impurity content of 3.1% and 18.2 parts by mass of pentaerythritol tetramercaptopropionate and stir evenly. Degas the mixture using a vacuum pump at a pressure of 350 Pa for 0.5 hours to prepare a mixed solution. Pour the solution into a glass mold and place it flat on a tray. Place the solution in an oven for programmed temperature curing, remove the mold, and open it to produce an optical lens. The results show a refractive index of 1.5933, a lens power of 300°, and a grain defect rate of 1.1%.

[0150] Application Example 15

[0151] Add 49.6 parts by mass of norbornane diisocyanate, 0.03 parts by mass of catalyst (dibutyltin dichloride), and 0.07 parts by mass of release agent (polyphosphate) into the batching kettle, and stir to dissolve at 15°C; add 25.5 parts by mass of a polythiol composition with an impurity content of 3.1% and 23.9 parts by mass of pentaerythritol tetramercaptopropionate, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and the degassing time is 0.5h to prepare a mixed solution, pour the solution into a glass mold, and place it flat on a tray after pouring. Put it in an oven for programmed temperature curing, take out the mold and open it to obtain an optical lens. The refractive index is detected to be 1.5930, the lens power is 298°, and the material grain defect rate is 1.2%.

[0152] Application Example 16

[0153] Add 56.3 parts by mass of norbornane diisocyanate, 0.03 parts by mass of catalyst (dibutyltin dichloride), and 0.07 parts by mass of release agent (polyphosphate) into the batching kettle, and stir to dissolve at 15°C; add 22.6 parts by mass of a polythiol composition with an impurity content of 3.1% and 21.1 parts by mass of pentaerythritol tetramercaptopropionate, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and the degassing time is 0.5h to prepare a mixed solution, pour the solution into a glass mold, and place it flat on a tray after pouring. Put it in an oven for programmed temperature curing, take out the mold and open it to obtain an optical lens. The refractive index is 1.5910, the lens power is 283°, and the material grain defect rate is 1.3%.

[0154] Application Example 17

[0155] Add 46.2 parts by mass of norbornane diisocyanate, 0.03 parts by mass of catalyst (dibutyltin dichloride), and 0.07 parts by mass of release agent (polyphosphate) into the batching kettle, and stir to dissolve at 15°C; add 27.8 parts by mass of a polythiol composition with an impurity content of 3.1% and 260 parts by mass of pentaerythritol tetramercaptopropionate, and stir evenly. Use a vacuum pump for degassing, control the pressure at 350Pa, and the degassing time is 0.5h to prepare a mixed solution, pour the solution into a glass mold, and place it flat on a tray after pouring. Put it in an oven for programmed temperature curing, take out the mold and open it to obtain an optical lens. The refractive index is 1.5940, the lens power is 312°, and the material grain defect rate is 1.3%.

[0156] The above describes in detail a polythiol composition and its preparation method, the use of the polythiol composition in the preparation of an optical material, and an optical material provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above examples is only intended to help understand the methods and core concepts of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including making and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, without departing from the principles of the present invention, various improvements and modifications may be made to the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be imagined by those skilled in the art. If these other embodiments have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A polythiol composition, characterized in that, It includes 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having the structure shown in formula (II); Wherein, any one of R1 and R2 is -SH, and the other is -OH; The mass content of the impurity having the structure shown in formula (II) ≤ 8.0%; 2. A method for preparing a polythiol composition as described in claim 1, characterized in that, It includes the following steps: 1) After mixing mercaptoethanol and an alkali solution, epichlorohydrin is added for reaction, then hydrochloric acid and thiourea are added for the thiourea-ammonium saltification process, and then after hydrolysis, a crude product of 2,3-dithio(2-mercapto)-1-propanethiol is obtained; 2) The crude product of 2,3-dithio(2-mercapto)-1-propanethiol obtained in the above step is post-treated to obtain 2,3-dithio(2-mercapto)-1-propanethiol; The polythiol composition is the main product of 2,3-dithio(2-mercapto)-1-propanethiol and the impurities generated during the preparation process.

3. The preparation method according to claim 2, characterized in that, The alkali solution includes a sodium hydroxide solution; The temperature of the reaction is 10 - 70 °C; The time of the reaction is 100 - 240 min; The time of the thiourea-ammonium saltification is 90 - 360 min; The steps of the post-treatment include one or more of pickling, water washing, water removal, and filtration.

4. Application of the polythiol composition in the preparation of optical materials; The polythiol composition includes 2,3-dithio(2-mercapto)-1-propanethiol and an impurity having the structure shown in formula (II); Among them, Any one of R1 and R2 is -SH, and the other is -OH; The mass content of the impurity having the structure shown in formula (II) ≤ 8.0%; 5. The application according to claim 4, wherein In the polythiol composition, the purity of 2,3-dithio(2-mercapto)-1-propanethiol is 88% - 96%; The polythiol composition is a composition containing multiple polythiol compounds; The raw material for preparing the optical material further includes polyisocyanate; The molar ratio of -SH in the polythiol composition to -NCO in the polyisocyanate is (0.8 - 1.2):1; The mass content of the impurity having the structure shown in formula (II) is 0.1% - 8%; 6. The application according to claim 4, wherein The raw material for preparing the optical material further includes another polythiol compound and a catalyst; The raw material for preparing the optical material further includes an auxiliary; The optical material includes optical lenses; The optical lens is specifically an optical lens made of a polythiourethane-type optical resin material; The application is specifically an application in improving the refractive index of the optical lens and / or reducing the defective rate of streaks in the optical lens material.

7. An optical material, characterized in that, The optical material is obtained by preparing from the polythiol composition and polyisocyanate as raw materials; The polythiol composition is the polythiol composition described in claim 1, the polythiol composition prepared by the preparation method described in any one of claims 2 - 3, or the polythiol composition in the application described in any one of claims 4 - 6.

8. The optical material according to claim 7, characterized in that The polyisocyanate is selected from one or more of tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl-m-xylylene diisocyanate, dithiodipropyl diisocyanate, dithiodiethyl diisocyanate, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5-diisocyanate-1,4-dithiane, thiodihexyl diisocyanate, thiodipropyl diisocyanate, bis(isocyanatomethyl)adamantane, bis(isocyanatomethyl)tetrahydrothiophene, 2,6-bis(isocyanatomethyl)naphthalene, 1,5-naphthalene diisocyanate, diethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, and triphenylmethane triisocyanate; The raw materials further include an additional polythiol compound; The additional polythiol compound is selected from one or more of 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, methanedithiol, methanetrithiol, bis(2-mercaptoethyl) ether, tetrakis(mercaptomethyl)methane, 1,2-dimercaptopropane, 1,3-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, 2,2-dimercaptopropane, 1,2-bis(2-mercaptoethoxy)ethane, 1,2-bis(2-mercaptoethylthio)ethane, 2,3-dimercapto-1-propanol, 1,2-dimercaptoethane, 1,3-dimercapto-2-propanol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptobutane, 1,2,3-trimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, bis(2-mercaptoethyl) sulfide, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(2-mercaptoacetate), 1,4-butanediol bis(2-mercaptoacetate), trimethylolpropane trimercaptopropionate, pentaerythritol tetrakis(mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), pentaerythritol tetrakis(mercaptopropionate), 1,2-dimercaptohexane, 1,1,1-tris(mercaptomethyl)propane, 1,4-butanediol bis(3-mercaptopropionate), 1,3-dimercaptohexane, trimethylolpropane trismercaptoacetate, 1,4-dimercaptohexane, 1,3-bis(mercaptomethyl)hexane, 1,4-bis(mercaptomethyl)hexane, bis(4-mercaptophenyl) sulfone, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-bis(2-mercaptoethylthiomethyl)-1,4-dithiane, 2,5-dimercaptomethyl-1-thiane, 2,5-dimercaptoethyl-1-thiane, 2,5-dimercaptomethylthiophene, bis(4-mercaptophenyl) sulfide, 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,3-bis(mercaptomethyl)benzene, 2,5-dimercaptomethyl-1,4-dithiane, 1,4-bis(mercaptomethyl)benzene, 2,2'-dimercaptobiphenyl, bis(4-mercaptophenyl)methane, 2,2-bis(4-mercaptophenyl)propane, 4,4'-dimercaptobiphenyl, bis(4-mercaptophenyl) ether, bis(4-mercaptomethylphenyl)methane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 2,2-bis(4-mercaptomethylphenyl)propane, bis(4-mercaptomethylphenyl) ether, bis(4-mercaptomethylphenyl) sulfide, 2,5-dimercapto-1,3,4-thiadiazole, and 3,4-thiophenedithiol; The molar ratio of the total number of moles of -SH in the polythiol composition and the additional polythiol compound to the -NCO of the polyisocyanate is (0.8 to 1.2):

1.

9. The optical material according to claim 7, characterized in that, The molar ratio of -SH in the polythiol composition to -NCO in the polyisocyanate is (0.8 to 1.2):1; The raw materials further include a catalyst; The catalyst is one or more of dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide, and stannous octoate; The catalyst accounts for 0.001% to 0.2% of the total mass of the raw materials. The raw materials further include an auxiliary agent; The raw materials further include an auxiliary agent; The auxiliary agent includes one or more of a release agent, an ultraviolet absorber, a toner, and a demolding agent.

10. The optical material according to claim 7, characterized in that, The preparation method includes polymerization curing; The temperature increase procedure for the polymerization curing is as follows: Keep warm at 25 to 35 °C for 175 to 185 min, increase the temperature to 43 to 47 °C at a heating rate of 0.83 to 1.25 °C / 10 min, then increase the temperature to 48 to 52 °C at a heating rate of 0.42 to 0.56 °C / 10 min, then increase the temperature to 58 to 62 °C at a heating rate of 0.57 to 0.83 °C / 10 min, then increase the temperature to 115 to 125 °C at a heating rate of 2.00 to 2.50 °C / 10 min, and then keep warm at 115 to 125 °C for 180 to 240 min.

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