A thiol composition and its application in optical materials

Abstract

The present invention relates to organic sulfides, optical materials such as plastic lenses, prisms, filters, and more particularly to a thiol composition and its application in optical materials. Adding a thiol compound of formula (1) to 2,3-disulfide (2-mercapto)-1-propanethiol or a thiol composition mainly containing the thiol compound, and controlling the content of the thiol compound of formula (1) within a certain range, can effectively solve the problem of impurity points in optical materials prepared mainly using 2,3-disulfide (2-mercapto)-1-propanethiol, and significantly improve the qualified rate of optical materials.

Description

Technical Field

[0001] The invention relates to organic sulfide, optical materials such as plastic lenses, prisms, filters, etc., and in particular to a thiol composition and its application in optical materials. Background Art

[0002] Plastic transparent materials have the advantages of light weight, strong toughness, and easy dyeing. In recent years, they are often used in the preparation of various optical materials. For use in the field of glasses and lenses, they require high transparency, low yellowness, high heat resistance, high strength, and high refractive index and Abbe number. High refractive index can make the lens thinner, and high Abbe number can reduce the chromatic aberration of the lens.

[0003] Polythiourethane optical resin materials with the above excellent properties have been an important development direction in recent years. This type of resin material is mainly prepared using polythiol compounds and isocyanates as raw materials.

[0004] During the research process, we found that some optical resin materials prepared from 2,3-dithio (2-mercapto)-1-propanethiol (Formula (2)) and isocyanate have impurity points on the surface or inside. Through detection analysis and comparative experimental analysis, it was found that the impurity points were caused by the precipitation of ultraviolet absorbers during the curing process of the material. Ultraviolet absorbers are one of the auxiliary materials that must be added to prepare optical materials, especially lenses, to improve the ultraviolet blocking rate of lenses. The presence of impurities in the lenses affects the quality and will be judged as unqualified products, resulting in low overall quality and low pass rate of the lenses, which further increases production costs, so improvements are needed. Summary of the invention

[0005] The present invention aims at the problems of the prior art and proposes a thiol composition and its application in optical materials. First, the inventors have found through in-depth research that adding a thiol compound of formula (1) to 2,3-dithio (2-mercapto)-1-propanethiol or a thiol composition mainly containing 2,3-dithio (2-mercapto)-1-propanethiol and controlling the content of the thiol compound of formula (1) within a certain range can effectively solve the impurity point problem of the optical material prepared mainly using 2,3-dithio (2-mercapto)-1-propanethiol, and significantly improve the qualified rate of the optical material.

[0006] The technical solution of the present invention includes:

[0007] First, a thiol compound was discovered through research, and its structure is shown in formula (1):

[0008]

[0009] The present application further provides a method for preparing a thiol compound of formula (1):

[0010] Mercaptoethanol and epichlorohydrin react in the presence of an alkaline reagent, the reaction product is dehydrated, and solid salts are removed by filtration; Lucas reagent is added to the obtained liquid, and the liquid is separated after the reaction, and liquid alkali is added to the organic phase obtained by the separation for reaction, and hydrochloric acid and thiourea are added after the reaction. After the reaction is completed under reflux conditions, ammonia water is added after the temperature is lowered to room temperature for hydrolysis reaction to obtain a thiol compound of formula (1).

[0011] Wherein, the molar ratio of mercaptoethanol to epichlorohydrin is 1.0-3.0, preferably 1.5-2.5, and more preferably 1.8-2.2.

[0012] The alkaline agent can be selected from sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, ammonia water, etc. Sodium hydroxide and potassium hydroxide are preferred.

[0013] The molar ratio of the alkaline agent to epichlorohydrin is 0.5-2.0, preferably 1.0-1.5.

[0014] A thiol composition comprises a thiol compound of formula (1) and a polythiol compound of formula (2).

[0015]

[0016] Preferably, the mass content of the thiol compound of formula (1) in the thiol composition is 0.01-2.0%, more preferably, the mass content of the thiol compound of formula (1) is 0.05-1%, and most preferably, the mass content of the thiol compound of formula (1) is 0.1-0.5%.

[0017] The present invention further provides a composition for an optical material based on the above thiol composition, which comprises the above thiol composition and polyisocyanate.

[0018] The polyisocyanate may be a conventionally used type in the art, and may also be 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 diisocyanate, diethyl diisocyanate, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiophene The present invention further comprises one or more of 2,4-diisocyanate, 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, trimethyl hexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, triphenylmethane triisocyanate, etc. More preferably, one or more of hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, m-xylylene diisocyanate, and hydrogenated m-xylylene diisocyanate. The most preferred one is selected from hydrogenated meta-xylylene diisocyanate, norbornane diisocyanate and meta-xylylene diisocyanate.

[0019] The optical material composition may further comprise other polythiol compounds, and the other polythiol compounds may be conventionally used in the art. Preferably, the other polythiol compounds can be 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 1,2-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), quaternary 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, 3,4-thiophenedithiol.

[0020] A method for preparing an optical material comprises the following steps: adding a catalyst in an amount of 0.001% to 0.2% of the total mass of the optical material composition to the optical material composition, and performing polymerization and curing.

[0021] The catalyst is selected from dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide and stannous octoate, preferably dibutyltin dilaurate and dibutyltin dichloride.

[0022] The amount of polymerization catalyst added varies according to the components of the optical material composition. Based on the mass of the optical material composition as 100%, the amount of catalyst added is 0.005-0.2%, preferably 0.01-0.1%, and more preferably 0.01-0.05%. When the amount of catalyst added is less than 0.005%, incomplete polymerization may occur, resulting in poor mechanical formation of the optical material. When the amount of catalyst added is greater than 0.2%, the polymerization speed may be too fast, resulting in an increase in the color tone of the optical material.

[0023] In addition to adding a catalyst in the preparation method of the optical material, one or more of a release agent, an ultraviolet absorber, a toner, a mold release agent, etc. can be added as needed to further improve the performance of the optical material.

[0024] In summary, the present invention provides a thiol compound (Formula (1)), which is mixed with 2,3-dithio(2-mercapto)-1-propanethiol to prepare a thiol composition, and the composition is further used to prepare an optical material, which can effectively reduce the impurity point problem caused by the precipitation of ultraviolet absorbers during the curing process of the material, improve the performance of the prepared optical material, and especially improve the light transmittance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a mass spectrometry analysis diagram of the thiol compound synthesized in Example 1 of the present application;

[0026] Figure 2 This is the NMR spectrum of the thiol compound synthesized in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The invention will be further described below in conjunction with specific embodiments, so that those skilled in the art can further understand the invention, but it is not intended to limit the content of the invention. All technologies based on the principles described in the invention belong to the scope of the invention.

[0028] In the following examples and comparative examples:

[0029] 1. 1 H-NMR determination:

[0030] The measurement was carried out using a 500 MHz liquid nuclear magnetic resonance spectrometer (AVANCE 500) produced by Bruker.

[0031] 2. Mass spectrometry analysis:

[0032] The analysis was performed using Agilent 6520B-QTOF LC / MS / MS with EI ionization.

[0033] 3.Quality rate test:

[0034] A semi-automatic mold-clamping machine was used to mold two pieces of flat glass with a diameter of 80 mm and an adhesive tape to form a mold with a thickness of 2 mm. 100 molds were prepared, and the optical material composition with added catalyst, release agent, and ultraviolet absorber was injected into the mold, and programmed temperature was increased to cure it. After curing, the temperature was lowered, and the optical material was demoulded to obtain the optical material. After cleaning, it was visually observed under a high-pressure mercury lamp. If there were impurities inside the material, it was judged to be unqualified, and the qualified rate was calculated.

[0035] 4. Curing heating program: maintain 30℃ for 180min, heat to 45℃ after 120min, heat to 50℃ after 90min, heat to 60℃ after 120min, heat to 120℃ after 240min, maintain at this temperature for 240min, and heat to 70℃ after 120min.

[0036] Example 1

[0037] Preparation of thiol compounds of formula (1):

[0038] Preparation of Lucas reagent: Heat and melt 68g of anhydrous zinc chloride in an evaporating dish, cool it in a desiccator, crush it, and dissolve it in 46g of 36% hydrochloric acid. The dissolution process releases heat, and cool it with cold water.

[0039] Into a four-necked flask equipped with a thermometer and a stirring device, 78.2 g of mercaptoethanol was added, 65.8 g of a 32% aqueous sodium hydroxide solution was added dropwise, and then 46.3 g of epichlorohydrin was added dropwise. Hydrochloric acid was added to adjust the pH to about 6, the water was evaporated by heating under reduced pressure, and the liquid was obtained by filtration. The prepared Lucas reagent was added thereto, heated to 60°C for reaction for 3 hours, separated, 63.0 g of a 32% sodium hydroxide aqueous solution was added to the organic phase obtained by separation, heated to 40°C for reaction for 3 hours, allowed to stand for stratification, the lower organic phase was separated, and 99.0 g of 36% hydrochloric acid and 45.6 g of thiourea were added to the organic phase, reacted under heating reflux for 3 hours, cooled to room temperature, 141.7 g of 18% ammonia water was added, reacted at 55°C for 3 hours, allowed to stand for stratification, the lower organic phase was separated to obtain a crude thiol compound represented by formula (1), hydrochloric acid was added to adjust the pH to about 6, water was added for washing twice, and water was removed by heating under reduced pressure to obtain the thiol compound represented by formula (1).

[0040] The qualitative test results of the product are as follows:

[0041] like Figure 1 and Figure 2 As shown, mass spectrometry analysis value: 210, calculated value: 210; nuclear magnetic resonance: 1H-NMR spectrum (CDCl3): δ=1.4 (1H), δ=2.3-2.5 (2H), δ=2.5-2.8 (6H), δ=2.9 (2H), δ=3.8-4.0 (2H), δ=4.2 (1H).

[0042] Example 2

[0043] The thiol compound of formula (1) obtained in Example 1 and the polythiol compound of formula (2) were mixed in different proportions to obtain thiol compositions of different compositions.

[0044] The mass contents of the thiol compound of formula (1) in the thiol composition are 0.01%, 0.05%, 0.1%, 0.5%, 1.0%, 2.0%, 3.0% and 5.0% respectively.

[0045] Examples 3-9 and Comparative Examples 1-2

[0046] Comparative Example 1 The technical scheme is as follows: 52.0 parts by mass of xylene diisocyanate are added to the flask, 0.01 parts by mass of catalyst (dibutyltin dichloride), 0.08 parts by mass of release agent (polyphosphate), and 0.8 parts by mass of ultraviolet absorber (UV329) are added, and stirred and dissolved at 10-15°C; 48.0 parts by mass of 2,3-dithio (2-mercapto)-1-propanethiol are added and stirred evenly. A vacuum pump is used for degassing, the pressure is controlled below 350Pa, and the degassing time is 0.5-1.0 hours to prepare a mixed solution, the solution is poured into a mold with a diameter of 80mm and a center thickness of 2.0mm, and the solution is placed in an oven for programmed temperature curing. After curing, the optical material is demoulded and cleaned to obtain an optical material. Visual observation under a high-pressure mercury lamp shows that the material has impurities inside and is judged to be unqualified. The qualified rate is statistically calculated, and the results are listed in Table 1.

[0047] The thiol compositions with different contents of the thiol compound of formula (1) prepared in Example 2 were used to replace the 2,3-dithio(2-mercapto)-1-propanethiol in Comparative Example 1, and the other operations were the same as those in Comparative Example 1 to obtain Examples 3-9 and Comparative Example 2. The detailed differences and test results are shown in Table 1.

[0048] Table 1

[0049]

[0050] Examples 9-15 and Comparative Examples 3-4

[0051] Comparative Example 3 The technical scheme is as follows: 49.8 parts by mass of hydrogenated xylene diisocyanate is added to the flask, 0.10 parts by mass of catalyst (dibutyltin dichloride), 0.10 parts by mass of release agent (polyphosphate), and 0.8 parts by mass of ultraviolet absorber (UV329) are added, and stirred and dissolved at 10-20°C; 30.2 parts by mass of 2,3-dithio (2-mercapto)-1-propanethiol and 20.0 parts by mass of pentaerythritol tetramercaptopropionate are added, and stirred evenly. A vacuum pump is used for degassing, the pressure is controlled below 350Pa, and the degassing time is 0.5-1.0 hours to prepare a mixed solution, and then the solution is poured into a mold with a diameter of 80mm and a center thickness of 2.0mm, and placed in an oven for program temperature curing. After curing, demoulding and cleaning are performed to obtain an optical material, and visual observation under a high-pressure mercury lamp determines that there are impurities inside the material that are unqualified, and the qualified rate is statistically calculated, and the results are listed in Table 2.

[0052] The thiol compositions with different contents of the thiol compound of formula (1) prepared in Example 2 were used to replace the 2,3-dithio(2-mercapto)-1-propanethiol in Comparative Example 3, and the other operations were the same as those in Comparative Example 3 to obtain Examples 9-15 and Comparative Example 4. The detailed differences and test results are shown in Table 2.

[0053] Table 2

[0054]

[0055] Embodiment 17

[0056] 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 catalyst (dibutyltin dichloride), 0.10 parts by mass of release agent (polyphosphate), and 0.8 parts by mass of ultraviolet absorber (UV329) were added into a flask, and stirred to dissolve at 10-20° C. 33.0 parts by mass of the thiol composition having a mass fraction of 0.1% of the thiol compound of formula (1) prepared in Example 2 and 18.2 parts by mass of pentaerythritol tetramercaptopropionate were added, and stirred evenly. A vacuum pump was used for degassing, the pressure was controlled below 350 Pa, the degassing time was 0.5-1.0 hour, a mixed solution was prepared, and then the solution was poured into a mold with a diameter of 80 mm and a center thickness of 2.0 mm, and placed in an oven for programmed temperature curing. After curing, the optical material was demoulded and cleaned to obtain the optical material. Visual observation under a high-pressure mercury lamp showed that the material had impurities inside and was judged to be unqualified. The statistical pass rate was 98%.

[0057] Embodiment 18

[0058] 49.6 parts by weight of norbornane diisocyanate, 0.03 parts by weight of catalyst (dibutyltin dichloride), 0.75 parts by weight of release agent (polyphosphate), and 0.8 parts by weight of ultraviolet absorber (UV329) were added into a flask, and the mixture was stirred and dissolved at 10-20° C. 25.5 parts by weight of a thiol composition having a mass fraction of 0.1% of the thiol compound shown in formula (1) and 23.9 parts by weight of pentaerythritol tetramercaptopropionate were added, and the mixture was stirred evenly. A vacuum pump was used for degassing, the pressure was controlled below 350 Pa, and the degassing time was 0.5-1.0 hours to prepare a mixed solution, and then the solution was poured into a mold having a diameter of 80 mm and a center thickness of 2.0 mm, and the mixture was placed in an oven for programmed temperature curing. After curing, the material was demoulded and cleaned to obtain an optical material, and the material was visually observed under a high-pressure mercury lamp. The material was judged unqualified if there were impurities inside, and the statistical qualified rate was 97%.

[0059] The above examples and corresponding proportional data further verify that the polythiol composition of the present invention can significantly improve the performance of the prepared optical material, especially can improve the light transmittance of the optical material, and has significant technical progress in application compared with the prior art.

Claims

1. A thiol compound, the structure of which is shown in formula (1): （1）。 2. A thiol composition, characterized in that: The composition comprises a thiol compound of formula (1) and a polythiol compound of formula (2), wherein the mass content of the thiol compound of formula (1) in the thiol composition is 0.01-2.0%; （1）； （2）。 3. The thiol composition according to claim 2, characterized in that The mass content of the thiol compound of formula (1) is 0.05-1%.

4. The thiol composition according to claim 2, characterized in that The mass content of the thiol compound of formula (1) is 0.1-0.5%.

5. A composition for an optical material, characterized in that: The composition comprises the thiol composition according to claim 2 and polyisocyanate.

6. The optical material composition according to claim 5, characterized in that 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 meta-xylylene diisocyanate, dipropyl diisocyanate, diethyl diisocyanate, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5-diisocyanatomethyl One or more of cyanate-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.

7. The composition for optical material according to claim 5, characterized in that The optical material composition further comprises other polythiol compounds, and 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-mercaptoethyl)ether 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- 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- One or more of 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.

8. A method for preparing an optical material, characterized in that: The process comprises: adding 0.001%-0.2% of the total mass of the optical material composition to the optical material composition according to any one of claims 5 to 7, and performing polymerization curing; the catalyst is selected from one of dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide, and stannous octoate.

9. The method for preparing an optical material according to claim 8, characterized in that: The process also includes: adding any one or more of a release agent, an ultraviolet absorber, a toner, and a mold release agent as needed.

10. The method for preparing a thiol compound according to claim 1, characterized in that: The specific steps are: Mercaptoethanol and epichlorohydrin react in the presence of an alkaline reagent, the reaction product is dehydrated, and solid salts are removed by filtration; Lucas reagent is added to the obtained liquid, and the liquid is separated after the reaction, and liquid alkali is added to the organic phase obtained by the separation for reaction, and hydrochloric acid and thiourea are added after the reaction. After the reaction is completed under reflux conditions, ammonia water is added after the temperature is lowered to room temperature for hydrolysis reaction to obtain a thiol compound of formula (1); Wherein, the molar ratio of mercaptoethanol to epichlorohydrin is 1.0-3.0; The alkaline reagent is selected from sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and ammonia water; The molar ratio of the alkaline reagent to epichlorohydrin is 0.5-2.0.

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