Preparation method of polythiol compound

Abstract

The invention belongs to the field of new materials, and provides a preparation method of a polythiol compound, the polythiol compound is prepared by reaction of 2-mercaptoethanol and an epichlorohydrin compound, the content of a compound shown in a formula (1) in the 2-mercaptoethanol is 0.001-0.2 wt% through a vacuum distillation method, and the content of the specific compound in the raw material 2-mercaptoethanol is strictly controlled, so that the content of the compound shown in the formula (1) is controlled to be 0.01-0.2 wt%. According to the present invention, a polythiol compound can be obtained, and even if the content of a compound represented by formula (2) contained in an epichlorohydrin compound is less than 200 ppm, the polythiol compound for a low-haze high-transmittance optical resin lens can be obtained; when the polythiol compound provided by the invention is used for the optical material, the qualification rate of the optical material can be improved, the local implosion phenomenon and the yield of unqualified products containing lines are reduced, the production cost is reduced, and the scratch resistance of the optical material is improved.

Description

Technical Field

[0001] The invention belongs to the field of new materials, and specifically provides a method for preparing a polythiol compound and a method for preparing a corresponding optical plastic lens. Background Art

[0002] Optical plastics have the advantages of high transparency, light weight, easy plastic processing, and excellent surface quality. They have been widely used in glasses, lighting equipment, auto parts, electronic products, optical instruments, etc. In the future, with the development and innovation of science and technology, optical plastics will become one of the indispensable materials in various industrial fields. Based on this, the demand for optical plastics in various fields will continue to grow, that is, higher requirements will be placed on the qualified rate of optical plastic products.

[0003] At present, the existing technology for preparing polythiol compounds mainly involves the reaction of 2-mercaptoethanol and epichlorohydrin compounds to synthesize polyols, the reaction of polyols with thiourea and hydrochloric acid to synthesize isothiouronium salts, and the alkaline hydrolysis reaction of isothiouronium salts with ammonia water (as shown in CN101400648A). The existing technology for preparing optical plastic lenses is to mix and dissolve polythiol compounds, isocyanate compounds and catalysts, and then heat and solidify them to prepare optical plastic lenses. During the research process, researchers found that the prepared optical plastic lenses have fine lines and a small amount of white bubbles in some parts, which not only affects the use and aesthetics of the optical plastic lenses, but also affects the scratch resistance of the optical plastic lenses. Such optical plastic lenses are regarded as unqualified products. The increase of unqualified products will increase production costs, reduce the output of qualified products entering the market, and affect the use of downstream users. In addition, the prior art still has the phenomenon that the lens is foggy, unclear or even opaque. To solve the above problems, CN117304082A discloses that limiting the impurity content of the epichlorohydrin compound represented by formula (I) to less than 30 ppm can improve the haze and transmittance of the optical resin lens, thereby obtaining a low haze and high transmittance optical resin lens. The inventor considers whether there are other solutions that can better solve the above problems. Summary of the invention

[0004] The present invention provides a method for preparing a polythiol compound, which is prepared by reacting 2-mercaptoethanol and an epichlorohydrin compound, wherein the content of the compound represented by formula (1) in the 2-mercaptoethanol is 0.001-0.2wt% by vacuum distillation, wherein the vacuum degree of the distillation tower during vacuum distillation is -0.005 to -0.2MPa, the temperature at the top of the distillation tower is 100 to 120°C, and the reflux ratio is 1:1 to 5:1. Compared with the prior art, the present invention can obtain a polythiol compound by strictly controlling the content of a specific compound in the raw material 2-mercaptoethanol, and even if the content of the compound represented by formula (2) contained in the epichlorohydrin compound is greater than 30ppm and is 30-200ppm, a polythiol compound for optical resin lenses with low haze and high light transmittance can be obtained; and the polythiol compound provided by the present invention is used for optical materials, which can improve the qualified rate of optical materials, reduce the local implosion phenomenon and the output of defective products containing lines, reduce production costs, and improve the scratch resistance of optical materials.

[0005] The inventors firstly provide a method for preparing a polythiol compound, which specifically comprises the following steps: synthesizing a polyol by reacting 2-mercaptoethanol and an epichlorohydrin compound, synthesizing an isothiourea salt by reacting the polyol with thiourea and hydrochloric acid, and performing an alkaline hydrolysis reaction between the isothiourea salt and aqueous ammonia.

[0006] Wherein, the content of the compound represented by formula (1) in the 2-mercaptoethanol is 0.001-0.2wt%; Formula (1); The CAS number of the thiol compound having the structure represented by the above formula (1) is 98026-19-8.

[0007] The method for controlling the content of the compound represented by formula (1) in the 2-mercaptoethanol to 0.001-0.2wt% can be various existing suitable removal means, among which the inventors preferably cite a vacuum distillation method; the conditions of the vacuum distillation in this method are that the vacuum degree of the distillation tower is -0.005 ~ -0.2MPa, the top temperature of the distillation tower is 100~120℃, and the reflux ratio is 1:1 ~ 5:1.

[0008] The inventors have found that in the synthesis process of the polythiol compound, the content of the compound represented by formula (1) in the 2-mercaptoethanol used will seriously affect the stability of the polythiol compound component. When the content of the compound represented by formula (1) in the 2-mercaptoethanol is too high, the side reactions occurring in the synthesis process increase, the content of the main component in the generated polythiol compound decreases, the types of impurities that can react with the isocyanate compound increase, and the components are too complex, resulting in different reaction rates in the reaction system when the polythiol compound reacts with the isocyanate compound, so that many fine lines appear in the prepared optical plastic lens, and local white bubbles are generated due to local explosion. Such optical plastic lenses are regarded as unqualified products, which greatly reduces the qualified rate of optical plastic lenses, increases production costs, and reduces the output of optical plastic lenses entering the market.

[0009] In addition, more importantly, the inventors unexpectedly discovered in the research that when the content of the compound represented by formula (1) in 2-mercaptoethanol is controlled to be 0.001-0.2wt%, even if the content of the compound represented by formula (2) in another raw material epichlorohydrin compound is greater than 30ppm, the stability and other properties of the finally obtained polythiol compound can be maintained at a high level; the prepared polythiol compound can also obtain an optical resin lens with low haze and high transmittance.

[0010] Formula (2).

[0011] The compound shown in the above formula (2) is the compound shown in formula (I) of the epichlorohydrin compound disclosed in CN117304082A in the background technology. That is to say, the technical scheme of the present application makes it possible to meet the product requirements as long as the compound shown in formula (2) of the epichlorohydrin compound is less than 200ppm, thereby reducing the requirements for the purity of the epichlorohydrin compound. The content of the compound shown in formula (2) contained in the conventional commercially available qualified epichlorohydrin compound with a content of 99.9%wt is within the above range. Therefore, the present application can directly select the commercially available qualified epichlorohydrin compound with a content of 99.9%wt as raw material, further reduce the production cost, and improve the yield rate. According to verification, the polythiol compound obtained by the above technical scheme is used for optical materials, which can improve the yield rate of optical materials, reduce the local implosion phenomenon and the output of defective products containing lines, reduce production costs, and improve the scratch resistance of optical materials.

[0012] In addition to the above-mentioned features, in the preparation method of the polythiol compound defined in the present application, the "synthesis of polyols by reacting 2-mercaptoethanol and epichlorohydrin compounds, the synthesis of isothiouronium salts by reacting polyols with thiourea and hydrochloric acid, and the alkaline hydrolysis reaction of isothiouronium salts with ammonia water" are all completed using existing conventional processes, which the inventors have illustrated in the embodiments and will not be repeated here.

[0013] Based on this discovery, the present invention provides a method for preparing a polythiol compound, which can prepare a polythiol compound with stable components, and then prepare a qualified optical plastic lens without fine lines and white bubbles.

[0014] In addition, the inventors also provide an optical material and a preparation method thereof, which is prepared using the polythiol compound, isocyanate compound and catalyst described in the above technical solution as raw materials.

[0015] The preferred isocyanate compound 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 - 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, diphenyl ether diisocyanate and triphenylmethane triisocyanate.

[0016] More preferably, the isocyanate compound is at least one selected from the group consisting of hexamethylene diisocyanate, 4,4′-diisocyanate dicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate.

[0017] Preferably, in addition to the above-mentioned polythiol compounds defined in the present application, the raw materials of the optical material may also include other polythiol compounds; 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-mercaptoethyl)ether, 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 tetramercapto trimethylolpropane trithioacetate, 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)sulfone At least one of 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.

[0018] More preferably, the other polythiol compounds are selected from at least one 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, pentaerythritol tetramercaptoacetate and pentaerythritol tetramercaptopropionate.

[0019] The catalyst is selected from one or more of dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide and stannous octoate.

[0020] In addition, the raw materials for preparing the optical material may further include an auxiliary agent; the auxiliary agent is selected from at least one of a release agent, an ultraviolet absorber and a toner.

[0021] The above-mentioned auxiliary agent can be any conventional technology, and is not particularly limited. The release agent can be selected from one or more of phosphate ester, acid phosphate ester, oxyalkylene type acid phosphate ester, alkali metal salt of acid phosphate ester, alkali metal salt of oxyalkylene type acid phosphate ester, alkali metal salt of higher fatty acid, and higher fatty acid ester. Preferably, it is selected from phosphate ester, acid phosphate ester, and oxyalkylene type acid phosphate ester.

[0022] The ultraviolet absorber can be selected from 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, o-hydroxybenzoic acid phenyl ester, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-(2'-hydroxy-3', 5'-di-tert-phenyl)-5-chlorobenzotriazole, monobenzoic acid resorcinol ester or one or more.Preferably 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole or 2-(2'-hydroxy-3', 5'-di-tert-phenyl)-5-chlorobenzotriazole.

[0023] The toner is preferably a boron reagent.

[0024] Preferably, the molar ratio of the mercapto groups contained in all the polythiol compounds to the isocyanate groups contained in the isocyanate compounds may be 0.5-3.0, preferably 0.6-2.0, more preferably 0.7-1.3.

[0025] Preferably, based on 100 parts by weight of the total mass of all polythiol compounds and isocyanate compounds, the catalyst accounts for 0.001 parts by weight to 0.5 parts by weight, and the auxiliary agent accounts for 0.01 parts by weight to 1.5 parts by weight.

[0026] In addition, the preparation method of the above optical material also directly adopts the existing technology, which is illustrated by the inventor in the embodiments and will not be described in detail here.

[0027] In summary, the present application can prepare a polythiol compound with higher stability by controlling the content of the compound represented by formula (1) in 2-mercaptoethanol in the range of 0.001-0.2wt%. More importantly, the purity requirement for the epichlorohydrin compound is reduced, so that most of the commercially available epichlorohydrin compounds can be directly used for the preparation of the present application, which greatly reduces the production cost. The polythiol compound finally obtained is used for optical materials, which can improve the qualified rate of optical materials, reduce the local explosion phenomenon and the output of defective products containing lines, reduce the production cost, and improve the scratch resistance of optical materials. DETAILED DESCRIPTION

[0028] The following is a further detailed description of the above contents of the present invention through specific implementation examples, but this should not be understood as the scope of the above subject of the present invention being limited to the following examples. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Unless otherwise specified, the following embodiments are all completed using conventional existing technologies.

[0029] After testing, the conventional commercially available qualified epichlorohydrin compound with a content of 99.9%wt used in the examples of the present application contained the compound represented by formula (2) at a content of less than 200ppm. Therefore, the present application directly selected the commercially available qualified epichlorohydrin compound with a content of 99.9%wt as the raw material; the epichlorohydrin compound used in Comparative Example 4 was a commercially available product after long-term storage, in which the compound represented by formula (2) was enriched and the content reached 201.12ppm. The inventors hereby explain this.

[0030] The purity of commercially available 2-mercaptoethanol is above 99.5 wt%. In order to obtain 2-mercaptoethanol containing the specific compound represented by formula (1), the inventors adopted the following technical solution: 10 kg of 2-mercaptoethanol with a purity of more than 99.5 wt% purchased from the market was taken for vacuum distillation. During the vacuum distillation, the vacuum degree of the distillation tower was -0.1 MPa, the top temperature of the distillation tower was 110° C., and the reflux ratio was 3:1. Finally, 9.50 kg of purified 2-mercaptoethanol and 500 g of heavy components were obtained.

[0031] In addition, the above parameters can also be set as the vacuum degree of the distillation tower is -0.15MPa, -0.2MPa, the top temperature of the distillation tower is 115°C, 120°C, and the reflux ratio is 2:1, 4:1.

[0032] The original 2-mercaptoethanol purchased, the purified 2-mercaptoethanol and the still residue after distillation were tested by gas chromatography. The results showed that the content of the compound represented by formula (1) in the original 2-mercaptoethanol purchased was 0.85wt%, the purified 2-mercaptoethanol did not contain the compound represented by formula (1), and the content of the compound represented by formula (1) in the still residue component after distillation was 17.93wt%. According to experiments, other impurities in the still residue after distillation have no effect on the purpose of this application, so the effects of other impurities in the still residue after distillation on the implosion phenomenon, lens texture, lens haze and transmittance can be ignored.

[0033] 1 g of the still residue after distillation was taken and added to 10 g, 12 g, 50 g, 85 g, 100 g, 150 g, 350 g and 850 g of purified 2-mercaptoethanol, respectively, to obtain 2-mercaptoethanol containing different contents of the specific compound represented by formula (1). After detection by gas chromatography, the contents of the compound represented by formula (1) in the above 2-mercaptoethanol containing different contents of the specific compound represented by formula (1) were 1.79 wt%, 1.49 wt%, 0.36 wt%, 0.21 wt%, 0.18 wt%, 0.12 wt%, 0.05 wt% and 0.02 wt%, respectively.

[0034] At the same time, 0.1 g of the still residue after distillation was added to 1000 g of purified 2-mercaptoethanol. After detection by gas chromatography, the content of the compound represented by formula (1) in the 2-mercaptoethanol was 0.001 wt%.

[0035] The inventors used the above-obtained 2-mercaptoethanol containing different contents of the specific compound represented by formula (1) as a raw material to carry out the preparation of the following examples.

[0036] The content of the compound represented by formula (1) in the above 2-mercaptoethanol was measured using an Agilent 7820A VL gas chromatograph.

[0037] In the following examples, the content of the compound represented by formula (2) in the epichlorohydrin compound was determined by ionization method using an Agilent 6530 Q-TOF LC / MS liquid spectrometer with an accuracy of 2 ppm.

[0038] Furthermore, in the process of preparing optical plastic lenses, the oven polymerization curing procedure is: Procedure 1 25℃-25℃ 5h; 25℃-45℃ 4h; 45℃-50℃ 3h; 50℃-60℃ 3h; 60℃-120℃ 5h; 120℃-120℃ 4h; 120℃-70℃ 1h.

[0039] Procedure 2 25℃-25℃ 7h; 25℃-45℃ 3h; 45℃-50℃ 3h; 50℃-60℃ 1h; 60℃-120℃ 6h; 120℃-120℃ 4h; 120℃-70℃ 2h.

[0040] Procedure 3 25℃-25℃ 20h; 25℃-45℃ 3h; 45℃-60℃ 2h; 60℃-90℃ 3h; 90℃-120℃ 1h; 120℃-120℃ 4h; 120℃-70℃ 2h.

[0041] The evaluation method for whether the obtained optical plastic lens is qualified is: 20 people observe with the naked eye whether the optical plastic products have fine lines and determine whether the optical plastic products are qualified.

[0042] The haze evaluation method for optical plastic lenses is: The haze of the optical plastic lenses obtained in the examples and comparative examples was measured using an UltraScan PRO spectrophotometer. The lower the haze, the better the transparency of the optical plastic lens.

[0043] The light transmittance evaluation method of optical plastic lenses is: The light transmittance of the optical plastic lenses obtained in the examples and comparative examples was measured using an UltraScan PRO spectrophotometer. The higher the light transmittance, the better the light transmittance of the optical plastic lens.

[0044] Example 1 A method for preparing a polythiol compound and an optical plastic lens (1) Synthesis of 2,3-dithio(2-mercapto)-1-propanethiol: Into a 1-liter four-necked flask equipped with a stirrer, a nitrogen purge tube and a thermometer, 86.8 g of 2-mercaptoethanol (the content of the specific compound represented by formula (1) is 0.02 wt%) is placed, 77.5 g of a 36 wt% sodium hydroxide aqueous solution is added dropwise at 50° C. over 40 minutes, and then 56.3 g of epichlorohydrin (purity is 99.96 wt%, and the content of the specific compound represented by formula (2) contained therein is 178.73 ppm) is added dropwise over 1.5 hours, and the temperature is kept for 1 hour; then 260 g of 37 wt% hydrochloric acid and 165 g of 99.30 wt% thiourea are added, and the mixture is refluxed at 130° C. for 4 hours to obtain isothiouronium salt.

[0045] After cooling to room temperature, 300 g of 18 wt % ammonia water was added and the reaction was carried out at 75 ° C for 4 hours. The mixture was allowed to stand for stratification, and the lower organic phase was separated to obtain a crude polythiol compound with 2,3-dithio (2-mercapto) -1-propanethiol as the main component. Hydrochloric acid was added to adjust the pH to about 6, and water was added for washing twice. The mixture was heated and dehydrated under reduced pressure to obtain 2,3-dithio (2-mercapto) -1-propanethiol.

[0046] (2) Preparation of optical plastic lenses: Take 52 g of xylylene diisocyanate, 0.01 g of dibutyltin dichloride as a catalyst, 0.08 g of acidic phosphate as a release agent, 0.50 g of an ultraviolet absorber (2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole), and 0.08 g of a toner boron reagent, mix and dissolve; then add and mix 48 g of 2,3-dithio(2-mercapto)-1-propanethiol obtained in the above step (1) to obtain a mixture.

[0047] The mixture was degassed at 200 Pa for 1 hour, and then filtered with a PTFE (polytetrafluoroethylene) filter with a pore size of 5.0 μm; the filtered mixture was injected into a glass mold with a diameter of 75 mm and 0.00D sealed with tape; the mold was placed in an oven and heated through polymerization curing procedure 1 to perform polymerization curing reaction; after the polymerization curing was completed, the mold was taken out of the oven, and after the mold was cooled to room temperature, the sealing tape was torn off to demold the optical plastic lens inside the mold cavity of the mold from the mold, and an optical plastic lens with the internal shape of the mold cavity of the mold was obtained. A total of 100 optical plastic lenses were obtained.

[0048] The optical plastic lens obtained in Example 1 was evaluated for its compliance; the evaluation results are shown in Table 1.

[0049] Example 2 A method for preparing a polythiol compound and an optical plastic lens (1) Synthesis of bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol: Into a 1-liter four-necked flask equipped with a stirrer, a nitrogen purge tube and a thermometer, 80.0 g of 2-mercaptoethanol (in which the content of the specific compound represented by formula (1) is 0.05 wt %), 41.5 g of ultrapure water and 0.25 g of a 49 wt % sodium hydroxide aqueous solution were added; 97.1 g of epichlorohydrin (purity of 99.96 wt %, the content of the specific compound represented by formula (2) contained therein is 154.67 ppm) was added dropwise at 10° C. over 6.5 hours, and the mixture was stirred for 60 minutes; then 234.8 g of a 17.3 wt % sodium sulfide aqueous solution was added dropwise at 22° C. over 5.5 hours, and the mixture was stirred for 120 minutes; then 35 436.8 g of hydrochloric acid with a purity of 99.30 wt% and 198.1 g of thiourea with a purity of 99.30 wt% were stirred at reflux at 110°C for 3 hours to carry out thiourea salt reaction; after cooling to 45°C, 335.0 g of toluene was added, and the mixture was cooled to 26°C. 322.8 g of 25 wt% aqueous ammonia solution was added at 38°C over 30 minutes, and stirred at 58°C for 1 hour to carry out hydrolysis reaction, thereby obtaining a toluene solution of a polythiol with bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol as the main component.

[0050] Then add 93.0 g of 36 wt % hydrochloric acid, and acid-wash the toluene solution at 36° C. for 30 minutes, twice; add 185.8 g of ultrapure water, wash at 40° C. for 30 minutes, five times; remove toluene and trace amounts of water under heating and reduced pressure, and then filter under reduced pressure with a 1.2 μm PTFE membrane filter to obtain bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol.

[0051] (2) Production of optical plastic lenses: Take 51.2 g of m-xylylene diisocyanate, 0.01 g of dibutyltin dichloride as a catalyst, 0.08 g of acidic phosphate as a release agent, 0.60 g of a UV absorber (2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole), and 0.08 g of a toner boron reagent, mix and dissolve; then, add and mix 48.8 g of bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol obtained in the above step (1) to obtain a mixture.

[0052] The mixture was degassed at 200 Pa for 1 hour, and then filtered with a PTFE (polytetrafluoroethylene) filter with a pore size of 5.0 μm; the filtered mixture was injected into a glass mold with a diameter of 75 mm and 0.00D sealed with tape; the mold was placed in an oven and heated through polymerization curing procedure 2 to perform a polymerization curing reaction; after the polymerization curing was completed, the mold was taken out of the oven, and after the mold was cooled to room temperature, the sealing tape was torn off to demold the optical plastic lens inside the mold cavity of the mold from the mold, and an optical plastic lens with the internal shape of the mold cavity of the mold was obtained. A total of 100 optical plastic lenses were obtained.

[0053] The optical plastic lens obtained in Example 2 was evaluated for its compliance; the evaluation results are shown in Table 1.

[0054] Example 3 The same method as in Example 1 was used except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 0.12 wt % and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 149.33 ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Example 3 were evaluated for their compliance; the evaluation results are shown in Table 1.

[0055] Example 4 The same method as in Example 1 was used except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 0.18 wt % and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 100.35 ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Example 4 were evaluated for their compliance; the evaluation results are shown in Table 1.

[0056] Example 5 The same method as in Example 1 was used except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 0.001wt%, and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 163.50ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 4 were evaluated for compliance; the evaluation results are shown in Table 1.

[0057] Example 6 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; 56.0 g of m-isophorone diisocyanate, 0.05 g of dibutyltin dichloride as a catalyst, 0.10 g of acidic phosphate as a release agent, 0.80 g of an ultraviolet absorber (2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole), and 0.07 g of a toner were mixed and dissolved; further, 44.0 g of 2,3-dithio(2-mercapto)-1-propanethiol prepared in the same manner as in Example 1 was added and mixed to obtain a mixture.

[0058] The mixture was degassed at 200 Pa for 1 hour, and then filtered with a PTFE (polytetrafluoroethylene) filter with a pore size of 5.0 μm; the filtered mixture was injected into a glass mold with a diameter of 75 mm and 0.00D sealed with tape; the mold was placed in an oven and heated through polymerization curing procedure 1 to perform a polymerization curing reaction; after the polymerization curing was completed, the mold was taken out of the oven, and after the mold was cooled to room temperature, the sealing tape was torn off to demold the optical plastic lens inside the mold cavity of the mold from the mold, and an optical plastic lens with the internal shape of the mold cavity of the mold was obtained. A total of 100 optical plastic lenses were obtained.

[0059] Example 7 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; Take 47.56 g of hydrogenated xylylene diisocyanate, 0.05 g of dibutyltin dichloride as a catalyst, 0.10 g of acidic phosphate as a release agent, 1.00 g of an ultraviolet absorber (2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole), and 0.08 g of a colorant, mix and dissolve; then, add and mix 29.97 g of 2,3-dithio(2-mercapto)-1-propanethiol and 22.47 g of pentaerythritol tetramercaptopropionate prepared in the same manner as in Example 1 to obtain a mixture.

[0060] The mixture was degassed at 200 Pa for 1 hour, and then filtered with a PTFE (polytetrafluoroethylene) filter with a pore size of 5.0 μm; the filtered mixture was injected into a glass mold with a diameter of 75 mm and 0.00D sealed with tape; the mold was placed in an oven and heated through polymerization curing procedure 3 to perform polymerization curing reaction; after the polymerization curing was completed, the mold was taken out of the oven, and after the mold was cooled to room temperature, the sealing tape was torn off to demold the optical plastic lens inside the mold cavity of the mold from the mold, and an optical plastic lens with the internal shape of the mold cavity of the mold was obtained. A total of 100 optical plastic lenses were obtained.

[0061] Example 8 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; Take 49.09 g of norbornane diisocyanate, 0.05 g of dibutyltin dichloride as a catalyst, 0.15 g of acidic phosphate as a release agent, 1.10 g of an ultraviolet absorber (2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole), and 0.07 g of a colorant, mix and dissolve; then, add and mix 25.5 g of 2,3-dithio(2-mercapto)-1-propanethiol and 25.41 g of pentaerythritol tetramercaptopropionate prepared in the same manner as in Example 1 to obtain a mixture.

[0062] The mixture was degassed at 200 Pa for 1 hour, and then filtered with a PTFE (polytetrafluoroethylene) filter with a pore size of 5.0 μm; the filtered mixture was injected into a glass mold with a diameter of 75 mm and 0.00D sealed with tape; the mold was placed in an oven and heated through polymerization curing procedure 3 to perform polymerization curing reaction; after the polymerization curing was completed, the mold was taken out of the oven, and after the mold was cooled to room temperature, the sealing tape was torn off to demold the optical plastic lens inside the mold cavity of the mold from the mold, and an optical plastic lens with the internal shape of the mold cavity of the mold was obtained. A total of 100 optical plastic lenses were obtained.

[0063] Comparative Example 1 The same method as in Example 1 was used except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 0.21wt%, and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 130.77ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 1 were evaluated for their compliance; the evaluation results are shown in Table 1.

[0064] Comparative Example 2 The same method as in Example 1 was used except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 0.36 wt % and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 124.91 ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 2 were evaluated for compliance; the evaluation results are shown in Table 1.

[0065] Comparative Example 3 The same method as in Example 1 was used except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 1.49 wt % and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 150.07 ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 3 were evaluated for compliance; the evaluation results are shown in Table 1.

[0066] Comparative Example 4 Except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 1.79wt%, and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 201.12ppm, the other aspects were the same as in Example 1, and 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 4 were evaluated for compliance; the evaluation results are shown in Table 1.

[0067] Comparative Example 5 The same method as in Example 1 was used except that the 2-mercaptoethanol used was the original sample of 2-mercaptoethanol purchased from the market and the content of the specific compound represented by formula (2) contained in the epichlorohydrin was 141.66 ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared in the same manner as in Example 1; and an optical plastic lens was further prepared in the same manner as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 5 were evaluated for their compliance; the evaluation results are shown in Table 1.

[0068] Comparative Example 6 The same method as in Example 1 was used except that the 2-mercaptoethanol used was 2-mercaptoethanol purified by distillation and the content of the specific compound represented by formula (2) in epichlorohydrin was 163.50 ppm. 2,3-dithio(2-mercapto)-1-propanethiol was prepared by the same method as in Example 1. An optical plastic lens was further prepared by the same method as in Example 1. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 6 were evaluated for their compliance; the evaluation results are shown in Table 1.

[0069] Comparative Example 7 Except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 0.36wt%, and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 124.91ppm, the other aspects were the same as in Example 2, and bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol was prepared in the same manner as in Example 2; and an optical plastic lens was further prepared in the same manner as in Example 2. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 7 were evaluated for compliance; the evaluation results are shown in Table 1.

[0070] Comparative Example 8 Except that the content of the specific compound represented by formula (1) in the 2-mercaptoethanol used was 1.49wt%, and the content of the specific compound represented by formula (2) in the epichlorohydrin used was 150.07ppm, the other aspects were the same as in Example 2, and bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol was prepared in the same manner as in Example 2; and an optical plastic lens was further prepared in the same manner as in Example 2. A total of 100 optical plastic lenses were obtained. The optical plastic lenses obtained in Comparative Example 8 were evaluated for compliance; the evaluation results are shown in Table 1.

[0071] Table 1: Results of the evaluation of whether optical plastic lenses are qualified By comparing the optical plastic lenses obtained in Examples 1-5 and Comparative Example 6 with those obtained in Comparative Examples 1-5 and 7-8, it can be seen that the optical plastic lenses in the Comparative Examples all have implosion phenomenon, resulting in white bubbles and lines, and the lens qualification rate is less than 60%, while the lenses in Examples 1-5 have no implosion phenomenon, so there are no white bubbles and no lines.

[0072] The qualified rate of the lenses of Examples 1-5 is 100%, indicating that when the content of the compound represented by formula (1) in 2-mercaptoethanol is less than 0.20wt%, the optical plastic lenses have no white bubbles or lines due to implosion, and the qualified rate of the lenses is 100%. In addition, in Comparative Example 6, 2-mercaptoethanol purified by distillation is used, in which the content of the compound represented by formula (1) is 0. Although no implosion phenomenon occurs, the qualified rate of the lenses is 0%. This is because when the content of the compound represented by formula (1) is 0, the content of the compound represented by formula (2) in epichlorohydrin is greater than 30ppm, which makes the lenses opaque. It can be seen that when the content of the compound represented by formula (1) in 2-mercaptoethanol is 0.001-0.2wt%, the technical effect described in the present application can be achieved.

[0073] Comparing the optical plastic lenses obtained in Examples 1-5, Comparative Examples 1-3, 5, 7-8 with Comparative Examples 4 and 6, it can be seen that although the lens of Comparative Example 6 has no implosion phenomenon and lines, it is not transparent; the lens of Comparative Example 4 has both white bubbles generated by implosion and lines, and is not transparent. This shows that when the content of the compound represented by formula (1) in 2-mercaptoethanol is 0.001-0.20wt% and the content of the compound represented by formula (2) in epichlorohydrin is less than 200ppm, the optical plastic lens has no white bubbles generated by implosion and no lines, the qualified rate of the lens is 100%, and it also has transparency, solving the problem of fogging and opacity of the lens.

[0074] Since the content of the compound represented by formula (2) contained in the qualified epichlorohydrin compound with a content of 99.9%wt on the market is less than 200ppm, the present invention does not limit the content of the compound represented by formula (2) contained in the epichlorohydrin compound. If necessary, the content of the compound represented by formula (2) contained in the qualified epichlorohydrin compound can be tested before use. As long as it is within the above range, it can be directly used as a raw material.

[0075] The above embodiments enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a polythiol compound, comprising a reaction stage of synthesizing a polyol by reacting 2-mercaptoethanol and an epichlorohydrin compound; characterized in that: The content of the compound represented by formula (1) in the 2-mercaptoethanol is 0.001-0.2wt%; Formula (1).

2. The method for preparing the polythiol compound according to claim 1, characterized in that: The content of the compound represented by formula (2) in the epichlorohydrin compound is less than 200 ppm; Formula (2).

3. An optical material, characterized in that: The polythiol compound, isocyanate compound and catalyst described in claim 1 are used as raw materials to prepare the product.

4. The optical material according to claim 3, characterized in that: The isocyanate compound 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 disulfide, diethyl disulfide, 2,5-diisocyanatomethylthiophene, 2,5-diisocyanatomethyl-1,4-dithiane, 2,5-diisocyanatomethyl-1,4-dithiane, At least one of isocyanate-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.

5. The optical material according to claim 3, characterized in that: The raw materials of the optical material may also include other polythiol compounds; 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, 1,2-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, At least one of 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.

6. The optical material according to claim 3, characterized in that: The catalyst is selected from one or more of dibutyltin dilaurate, dibutyltin dichloride, dibutyltin oxide and stannous octoate.

7. The optical material according to claim 3, characterized in that: The raw materials for preparing the optical material further include an auxiliary agent; the auxiliary agent is selected from at least one of a release agent, an ultraviolet absorber and a toner.

8. The optical material according to claim 6 or 7, characterized in that: Based on 100 parts by weight of the total mass of all the polythiol compounds and the isocyanate compounds, the catalyst accounts for 0.001-0.5 parts by weight, and the auxiliary agent accounts for 0.01-1.5 parts by weight.

9. The optical material according to claim 3 or 5, characterized in that: The molar ratio of the mercapto groups contained in all the polythiol compounds to the isocyanate groups contained in the isocyanate compounds is 0.5-3.

0.

10. The optical material according to claim 9, characterized in that: The molar ratio of the mercapto groups contained in all the polythiol compounds to the isocyanate groups contained in the isocyanate compounds is 0.6-2.0.

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