阅读说明：本技术 一种聚硫醇化合物、其制备方法及应用 (Polythiol compound, preparation method and application thereof ) 是由 许倩倩 梁万根 张超 崔卫华 孙志利 费潇瑶 卞文 于 2020-11-27 设计创作，主要内容包括：本发明涉及光学树脂技术领域,尤其涉及一种聚硫醇化合物、其制备方法及应用。聚硫醇化合物的制备方法包括：A)将表氯醇溶液、巯基乙醇和第一碱性化合物溶液进行反应,得到多元醇混合液；B)将所述多元醇混合液、硫脲和第一酸液进行成盐反应,得到异硫脲盐；C)将所述异硫脲盐与第二碱性化合物溶液混合,进行水解反应得到聚硫醇粗品；D)将所述聚硫醇粗品采用第二酸液进行洗涤；E)将所述洗涤后的产物与有机溶剂混合,进行萃取；F)分液、除去溶剂,得到聚硫醇化合物。本发明提供的制备方法可以获得高品质的聚硫醇化合物,进一步得到了色调优异的聚硫氨脂系树脂,从而解决了树脂固化后的白浊现象。(The invention relates to the technical field of optical resin, in particular to a polythiol compound, and a preparation method and application thereof. The method for producing a polythiol compound comprises: A) reacting epichlorohydrin solution, mercaptoethanol and first alkaline compound solution to obtain polyol mixed solution; B) carrying out salt forming reaction on the polyol mixed solution, thiourea and first acid solution to obtain isothiourea salt; C) mixing the isothiourea salt with a second alkaline compound solution, and performing hydrolysis reaction to obtain a polythiol crude product; D) washing the polythiol crude product by using a second acid solution; E) mixing the washed product with an organic solvent, and extracting; F) separating and removing the solvent to obtain the polythiol compound. The preparation method provided by the invention can obtain high-quality polythiol compound, further obtain polythiourethane resin with excellent color tone, and solve the white turbidity phenomenon after the resin is cured.)

1. A method for producing a polythiol compound, comprising the steps of:

A) reacting epichlorohydrin solution, mercaptoethanol and first alkaline compound solution to obtain polyol mixed solution;

B) carrying out salt forming reaction on the polyol mixed solution, thiourea and first acid solution to obtain isothiourea salt;

C) mixing the isothiourea salt with a second alkaline compound solution, and performing hydrolysis reaction to obtain a polythiol crude product;

D) washing the polythiol crude product by using a second acid solution;

E) mixing the washed product with an organic solvent, and extracting;

F) separating and removing the solvent to obtain the polythiol compound.

2. The preparation method according to claim 1, wherein in step a), the first basic compound comprises one or more of potassium hydroxide, sodium carbonate and triethylamine;

the concentration of the first alkaline compound solution is 10 wt% -40 wt%;

the molar ratio of epichlorohydrin to mercaptoethanol to the first basic compound is 1: 1.95-2: 0.3 to 1.2.

3. The method according to claim 1, wherein in the step A), the reaction temperature is 35-60 ℃ and the reaction time is 10-40 min.

4. The preparation method according to claim 1, wherein in the step B), the first acid solution comprises one or more of a hydrobromic acid solution, a sulfuric acid solution and a hydroiodic acid solution;

the molar ratio of thiourea to epichlorohydrin in step A) is 3-6: 1;

the molar ratio of the acidic substance in the first acid solution to the epichlorohydrin in the step A) is 1-8: 1;

the temperature of the salt forming reaction is 90-120 ℃, and the time is 1.5-4 h.

5. The method according to claim 1, wherein in step C), the second basic compound solution comprises a potassium carbonate solution and/or a sodium hydroxide solution;

the concentration of the second alkaline compound solution is 15 wt% -30 wt%;

the molar ratio of the second alkaline compound to epichlorohydrin is 2.5-9: 1;

the temperature of the hydrolysis reaction is 45-65 ℃, and the time is 2-4 h.

6. The method according to claim 1, wherein in step D), the second acid solution comprises one or more of a sulfuric acid solution, an acetic acid solution, a formic acid solution, an pyruvic acid solution and a hydrofluoric acid solution;

the washing temperature is 20-60 ℃, and the washing time is 1-3 h.

7. The method according to claim 1, wherein in step E), the organic solvent comprises an alcohol solution.

8. The method according to claim 1, wherein in step F), the solvent is removed by freeze-drying;

the temperature of freeze drying is-10 ℃, and the time is 1-2 h;

the pressure of freeze drying is 100 Pa-180 Pa.

9. A polythiol compound obtained by the production method according to any one of claims 1 to 8.

10. An optical resin material produced by reacting raw materials including an isocyanate and the polythiol compound according to claim 9.

Technical Field

The invention relates to the technical field of optical resin, in particular to a polythiol compound, and a preparation method and application thereof.

Background

Plastic materials are lightweight, tough, and highly dyeable, and have been commonly used in the preparation of various optical materials in recent years. For the application to the field of spectacle lenses, low specific gravity, high transparency, low yellowness, high heat resistance, high strength, and high refractive index and Abbe number are required. As polythiourethane type optical resin materials having the above excellent properties, which are mainly prepared from polythiol compounds and isocyanates as raw materials, are important development directions in recent years.

When used for plastic lenses, the polythiourethane resin is required to have excellent color tone and good transparency. However, the quality of raw materials and reaction impurities during the reaction have a great influence on the index of the product, and further, the composition containing these polythiol compounds sometimes suffers from cloudiness during polymerization and curing, resulting in a great loss.

Disclosure of Invention

In view of the above, the present invention provides a polythiol compound, a preparation method and applications thereof, wherein the preparation method can obtain a high-quality polythiol compound, and further can obtain a high-quality optical resin material.

The invention provides a preparation method of a polythiol compound, which comprises the following steps:

A) reacting epichlorohydrin solution, mercaptoethanol and first alkaline compound solution to obtain polyol mixed solution;

B) carrying out salt forming reaction on the polyol mixed solution, thiourea and first acid solution to obtain isothiourea salt;

C) mixing the isothiourea salt with a second alkaline compound solution, and performing hydrolysis reaction to obtain a polythiol crude product;

D) washing the polythiol crude product by using a second acid solution;

E) mixing the washed product with an organic solvent, and extracting;

F) separating and removing the solvent to obtain the polythiol compound.

Preferably, in step a), the first basic compound comprises one or more of potassium hydroxide, sodium carbonate and triethylamine;

the concentration of the first alkaline compound solution is 10 wt% -40 wt%;

the molar ratio of epichlorohydrin to mercaptoethanol to the first basic compound is 1: 1.95-2: 0.3 to 1.2.

Preferably, in the step A), the reaction temperature is 35-60 ℃, and the reaction time is 10-40 min.

Preferably, in step B), the first acid solution includes one or more of a hydrobromic acid solution, a sulfuric acid solution and a hydroiodic acid solution;

the molar ratio of thiourea to epichlorohydrin in step A) is 3-6: 1;

the molar ratio of the acidic substance in the first acid solution to the epichlorohydrin in the step A) is 1-8: 1;

the temperature of the salt forming reaction is 90-120 ℃, and the time is 1.5-4 h.

Preferably, in step C), the second basic compound solution comprises a potassium carbonate solution and/or a sodium hydroxide solution;

the concentration of the second alkaline compound solution is 15 wt% -30 wt%;

the molar ratio of the second alkaline compound to epichlorohydrin is 2.5-9: 1;

the temperature of the hydrolysis reaction is 45-65 ℃, and the time is 2-4 h.

Preferably, in step D), the second acid solution includes one or more of a sulfuric acid solution, an acetic acid solution, a formic acid solution, an pyruvic acid solution and a hydrofluoric acid solution;

the washing temperature is 20-60 ℃, and the washing time is 1-3 h.

Preferably, in step E), the organic solvent comprises an alcohol solution.

Preferably, in step F), the solvent is removed by freeze-drying;

the temperature of freeze drying is-10 ℃, and the time is 1-2 h;

the pressure of freeze drying is 100 Pa-180 Pa.

The invention also provides a polythiol compound prepared by the preparation method.

The invention also provides an optical resin material prepared by reacting the raw materials comprising isocyanate and the polythiol compound.

The invention provides a preparation method of a polythiol compound, which comprises the following steps: A) reacting epichlorohydrin solution, mercaptoethanol and first alkaline compound solution to obtain polyol mixed solution; B) carrying out salt forming reaction on the polyol mixed solution, thiourea and first acid solution to obtain isothiourea salt; C) mixing the isothiourea salt with a second alkaline compound solution, and performing hydrolysis reaction to obtain a polythiol crude product; D) washing the polythiol crude product by using a second acid solution; E) mixing the washed product with an organic solvent, and extracting; F) separating and removing the solvent to obtain the polythiol compound. The preparation method provided by the invention can obtain high-quality polythiol compound, further obtain polythiourethane resin with excellent color tone, and solve the white turbidity phenomenon after the resin is cured. The preparation method provided by the invention is simple to operate and easy to control, and can be used for preparing a polythiol product with high transparency, so that the product quality of downstream optical resin products is ensured, and good social and economic benefits are achieved.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a preparation method of a polythiol compound, which comprises the following steps:

A) reacting epichlorohydrin solution, mercaptoethanol and first alkaline compound solution to obtain polyol mixed solution;

B) carrying out salt forming reaction on the polyol mixed solution, thiourea and first acid solution to obtain isothiourea salt;

C) mixing the isothiourea salt with a second alkaline compound solution, and performing hydrolysis reaction to obtain a polythiol crude product;

D) washing the polythiol crude product by using a second acid solution;

E) mixing the washed product with an organic solvent, and extracting;

F) separating and removing the solvent to obtain the polythiol compound.

The method comprises the step of reacting epichlorohydrin solution, mercaptoethanol and first alkaline compound solution to obtain polyol mixed solution.

In certain embodiments of the invention, the epichlorohydrin solution has a concentration of 98 wt% to 99.9 wt%. In certain embodiments, the concentration of the epichlorohydrin solution is 99.85 wt%, 99.8 wt%, or 99.9 wt%. In certain embodiments, the solvent in the epichlorohydrin solution is water.

In certain embodiments of the invention, the first basic compound comprises one or more of potassium hydroxide, sodium carbonate, and triethylamine. In certain embodiments of the invention, the concentration of the first basic compound solution is 10 wt% to 40 wt%. In certain embodiments, the concentration of the first basic compound solution is 30 wt%. In certain embodiments, the solvent in the first basic compound solution is water.

In certain embodiments of the present invention, the mole ratio of epichlorohydrin, mercaptoethanol, and first basic compound is 1: 1.95-2: 0.3 to 1.2. In certain embodiments, the molar ratio of epichlorohydrin, mercaptoethanol, and first alkaline compound is 1: 1.96: 0.38, 1: 1.98: 0.74 or 1: 1.998: 0.38.

in some embodiments of the present invention, the reaction temperature of the epichlorohydrin solution, the mercaptoethanol, and the first alkaline compound solution is 35 to 60 ℃, and the reaction time is 10 to 40 min. In certain embodiments, the temperature of the reaction is 45 ℃, 40 ℃, or 38 ℃. In certain embodiments, the time of the reaction is 20 min.

After obtaining the polyol mixed solution, carrying out salt forming reaction on the polyol mixed solution, thiourea and the first acid solution to obtain isothiourea salt.

In certain embodiments of the invention, the first acid solution comprises one or more of a hydrobromic acid solution, a sulfuric acid solution, and a hydroiodic acid solution. In certain embodiments of the present invention, the concentration of the first acid solution is 20 wt% to 40 wt%. In certain embodiments, the concentration of the first acid solution is 36 wt%. In certain embodiments, the solvent in the first acid solution is water.

In certain embodiments of the invention, the molar ratio of the acidic material to epichlorohydrin in the first acid solution is 1 to 8: 1. in certain embodiments, the molar ratio of acidic species to epichlorohydrin in the first acid liquor is 1.78: 1 or 1.8: 1.

in certain embodiments of the invention, the molar ratio of thiourea to epichlorohydrin is from 3 to 6: 1. in certain embodiments, the molar ratio of thiourea to epichlorohydrin is 3.18: 1 or 3.2: 1.

in some embodiments of the invention, the temperature of the salt forming reaction is 90-120 ℃ and the time is 1.5-4 hours. In certain embodiments, the temperature of the salt formation reaction is 110 ℃ or 112 ℃. In certain embodiments, the time for the salt formation reaction is 3 hours or 2.5 hours.

After the isothiourea salt is obtained, mixing the isothiourea salt with a second alkaline compound solution, and carrying out hydrolysis reaction to obtain a polythiol crude product.

In certain embodiments of the present invention, the isothiourea salt, prior to mixing with the second basic compound solution, further comprises: cooling the isothiourea salt. In some embodiments, the temperature is reduced to 20-40 ℃. In certain embodiments, the temperature is reduced to room temperature or 35 ℃, 20 ℃ or 40 ℃.

In certain embodiments of the invention, the second basic compound solution comprises a potassium carbonate solution and/or a sodium hydroxide solution. In certain embodiments of the invention, the concentration of the second basic compound solution is between 15 wt% and 30 wt%. In certain embodiments, the concentration of the second basic compound solution is 25 wt% or 20 wt%. In certain embodiments, the solvent in the second basic compound solution is water.

In certain embodiments of the present invention, the molar ratio of the second basic compound to epichlorohydrin is from 2.5 to 9: 1. in certain embodiments, the molar ratio of the second basic compound to epichlorohydrin is 2.975: 1. 4.12: 1 or 3.3: 1.

in some embodiments of the present invention, the temperature of the hydrolysis reaction is 45-65 ℃ and the time is 2-4 hours. In certain embodiments, the temperature of the hydrolysis reaction is 50 ℃, 45 ℃, or 55 ℃. In certain embodiments, the hydrolysis reaction time is 3 hours.

And after a polythiol crude product is obtained, washing the polythiol crude product by adopting a second acid solution.

In certain embodiments of the present invention, the second acid solution comprises one or more of a sulfuric acid solution, an acetic acid solution, a formic acid solution, an pyruvic acid solution, and a hydrofluoric acid solution. In certain embodiments of the invention, the concentration of the second acid solution is 20 wt% to 40 wt%. In certain embodiments, the concentration of the second acid solution is 25 wt%, 35 wt%, or 30 wt%. In certain embodiments of the invention, the mass ratio of the second acid solution to the crude polythiol is 1: 1. in certain embodiments, the solvent of the second acid solution is water.

In some embodiments of the invention, the washing temperature is 20-60 ℃ and the washing time is 1-3 h. In certain embodiments, the temperature of the wash is 30 ℃, 40 ℃, or 50 ℃. In certain embodiments, the time for the wash is 2h, 3h, or 1 h.

In some embodiments of the invention, after washing is completed, liquid separation is performed to obtain a washed product.

After obtaining the washed product, mixing the washed product with an organic solvent, and extracting.

In certain embodiments of the present invention, the organic solvent comprises an alcohol solution. In certain embodiments of the present invention, the alcohol solution comprises one or more of an ethanol solution, a methanol solution, and an isopropanol solution. In certain embodiments of the invention, the concentration of the alcoholic solution is between 90 wt% and 99 wt%. In certain embodiments, the concentration of the alcohol solution is 99 wt% or 98 wt%. In certain embodiments of the present invention, the volume ratio of the organic solvent to the washed product is 1: 1. in certain embodiments, the solvent of the alcoholic solution is water.

After the extraction is completed, the solution is separated and the solvent is removed to obtain the polythiol compound.

In certain embodiments of the invention, the method of removing the solvent is freeze drying. In some embodiments of the invention, the temperature of freeze-drying is-10 to 10 ℃. In certain embodiments, the temperature of freeze-drying is 5 ℃, 3 ℃, or 0 ℃. In certain embodiments of the invention, the pressure of freeze-drying is negative pressure. In certain embodiments, the pressure of freeze-drying is from 100Pa to 180 Pa. In certain embodiments, the pressure of freeze-drying is 100Pa, 150Pa, or 180 Pa. In some embodiments, the freeze-drying time is 1-2 hours. In certain embodiments, the time for lyophilization is 1h, 1.5h, or 2 h. In certain embodiments, the freeze-drying is performed in a freeze-dryer.

The invention also provides a polythiol compound prepared by the preparation method.

The invention also provides an optical resin material prepared by reacting the raw materials comprising isocyanate and the polythiol compound.

In certain embodiments of the present invention, the method for preparing the optical resin material comprises the steps of:

a) mixing polythiol compound, isocyanate and catalyst, and degassing under the condition of negative pressure; the polythiol compound is a polythiol compound described above;

b) and heating the degassed mixture, and carrying out polymerization reaction at 115-125 ℃ to obtain the optical resin material.

In certain embodiments of the present invention, the catalyst is dibutyltin dichloride.

In certain embodiments of the present invention, the mass ratio of the polythiol compound to the isocyanate is 45 to 55: 45-55. In certain embodiments, the mass ratio of polythiol compound to isocyanate is 50: 50.

in certain embodiments of the present invention, the mass ratio of the polythiol compound to the catalyst is 45 to 55: 0.005-0.015. In certain embodiments, the mass ratio of the polythiol compound to the catalyst is 50: 0.01.

in certain embodiments of the invention, in step a), the pressure of the sub-atmospheric condition is lower than 500 Pa. In certain embodiments, the pressure of the negative pressure condition in step a) is 200Pa, 300Pa or 250 Pa.

In some embodiments of the invention, the degassing temperature is 18-22 ℃ and the time is 0.8-1.2 h. In certain embodiments, the temperature of the degassing is 20 ℃. In certain embodiments, the time for degassing is 1 h.

In certain embodiments of the invention, step b) comprises:

and placing the degassed mixture into a casting mold, placing the casting mold into an oven, heating to 115-125 ℃, and carrying out polymerization reaction at 115-125 ℃ to obtain the optical resin material.

In certain embodiments of the invention, the casting mold is a glass mold.

In certain embodiments of the invention, the rate of heating is 1 deg.C/min.

In certain embodiments of the invention, the temperature of the polymerization reaction is 120 ℃. In certain embodiments of the present invention, the polymerization reaction time is 22 to 26 hours. In certain embodiments, the polymerization reaction time is 24 hours.

In certain embodiments of the present invention, after the polymerization reaction, further comprising: and (6) demolding.

In some embodiments of the present invention, the optical resin material may be an optical resin lens.

The source of the above-mentioned raw materials is not particularly limited in the present invention, and may be generally commercially available.

In order to further illustrate the present invention, the following will describe in detail a polythiol compound, its preparation method and application provided by the present invention with reference to examples, but they should not be construed as limiting the scope of the present invention.

The starting materials used in the following examples are all generally commercially available.

Example 1

The preparation of the (primary) polythiol comprises the following specific steps:

(1) polyol synthesis:

76.98g (0.98mol) of mercaptoethanol were poured into a four-necked flask, 62.5g of a 30% by weight triethylamine solution (the amount of triethylamine as a substance was 0.19mol) was added dropwise, and then an epichlorohydrin solution (the concentration was 99.85% by weight) was added in an amount of 46.30g (0.5mol) based on the amount of epichlorohydrin added and reacted at 45 ℃ for 20 minutes to obtain a polyol mixture.

(2) Salt forming reaction:

122g (1.59mol) of thiourea and 198g of hydrobromic acid (the amount of hydrogen bromide was 0.89mol) having a concentration of 36 wt% were added to the polyol mixture in the step (2), and a reflux reaction was carried out at 110 ℃ for 3 hours to produce an isothiourea salt.

(3) Hydrolysis reaction and post-treatment:

and (3) cooling the isothiourea salt in the step (3) to 35 ℃, adding 238g of 25 wt% sodium hydroxide solution (the amount of sodium hydroxide is 1.4875mol), and carrying out hydrolysis reaction at 50 ℃ for 3h to obtain a polythiol crude product.

(4) Adding an acetic acid solution (with the concentration of 25 wt%) into the crude polythiol, wherein the mass ratio of the acetic acid solution to the crude polythiol is 1: washing at 1 and 30 ℃ for 2h, separating liquid, adding an ethanol solution (with the concentration of 99 wt%) into the washed product, and extracting, wherein the volume ratio of the washed product to the ethanol solution is 1: and 1, after extraction is finished, separating liquid, putting the liquid into a freeze dryer, and drying the liquid for 1 hour at the temperature of 5 ℃ under the negative pressure of 100Pa to obtain the polythiol.

The polythiol prepared in the example was subjected to colorimetric detection using a spectrocolorimeter (manufacturer Hunter, model Pro lab), and the experimental results were: 8.

(II) preparing the optical resin lens, which comprises the following steps:

at the temperature of 20 ℃, 50g of polythiol prepared in the step, 50g of isocyanate and 0.01g of catalyst dibutyltin dichloride are uniformly mixed, and degassing is carried out for 1h under the negative pressure of 200 Pa; then injecting the mixture into a casting mold consisting of a glass mold and an adhesive tape, putting the casting mold into an oven, heating the temperature from room temperature to 120 ℃ according to the heating rate of 1 ℃/min, and carrying out polymerization reaction for 24 hours at the temperature; after the polymerization, the mold was taken out from the oven and released to obtain an optical resin lens.

The optical resin lens prepared in the embodiment is detected, the texture and the white turbidity of the optical material are detected by a D65 light source of a color lamp box by adopting a standard light source, and the result shows that the lens has no white turbidity phenomenon.

Example 2

The preparation of the (primary) polythiol comprises the following specific steps:

(1) polyol synthesis:

77.37g (0.99mol) of mercaptoethanol were poured into a four-necked flask, 68.75g of a 30% by weight potassium hydroxide solution (the amount of potassium hydroxide substance was 0.37mol) was added dropwise, and then an epichlorohydrin solution (the concentration was 99.8% by weight) was added in an amount of 46.29g (0.5mol) based on the amount of epichlorohydrin added, and reacted at 40 ℃ for 20 minutes to obtain a polyol mixture.

(2) Salt forming reaction:

122.5g (1.6mol) of thiourea and 197g of hydrobromic acid having a concentration of 36 wt% (the amount of hydrogen bromide was 0.89mol) were put into the polyol mixture in the step (2), and a reflux reaction was carried out at 110 ℃ for 2.5 hours to produce an isothiourea salt.

(3) Hydrolysis reaction and post-treatment:

and (3) cooling the isothiourea salt in the step (3) to 20 ℃, adding 330g of 25 wt% sodium hydroxide solution (the amount of sodium hydroxide is 2.06mol), and carrying out hydrolysis reaction at 45 ℃ for 3h to obtain a polythiol crude product.

(4) Adding a sulfuric acid solution (with the concentration of 35 wt%) into the crude polythiol, wherein the mass ratio of the sulfuric acid solution to the crude polythiol is 1: washing at 1 and 40 ℃ for 3 hours, separating liquid, adding a methanol solution (with the concentration of 99 wt%) into the washed product, and extracting, wherein the volume ratio of the washed product to the methanol solution is 1: and 1, after extraction is finished, separating liquid, putting the liquid into a freeze dryer, and drying the liquid for 1.5 hours at the temperature of 3 ℃ under the negative pressure of 150Pa to obtain the polythiol.

The polythiol prepared in the example was subjected to colorimetric detection using a spectrocolorimeter (manufacturer Hunter, model Pro lab), and the experimental results were: 7.2.

(II) preparing the optical resin lens, which comprises the following steps:

at the temperature of 20 ℃, 50g of polythiol prepared in the step, 50g of isocyanate and 0.01g of catalyst dibutyltin dichloride are uniformly mixed, and degassing is carried out for 1h under the negative pressure of 300 Pa; then injecting the mixture into a casting mold consisting of a glass mold and an adhesive tape, putting the casting mold into an oven, heating the temperature from room temperature to 120 ℃ according to the heating rate of 1 ℃/min, and carrying out polymerization reaction for 24 hours at the temperature; after the polymerization, the mold was taken out from the oven and released to obtain an optical resin lens.

The optical resin lens prepared in the embodiment is detected, the texture and the white turbidity of the optical material are detected by a D65 light source of a color lamp box by adopting a standard light source, and the result shows that the lens has no white turbidity phenomenon.

Example 3

The preparation of the (primary) polythiol comprises the following specific steps:

(1) polyol synthesis:

76.59g (0.99mol) of mercaptoethanol was poured into a four-necked flask, 65.62g of a 30 wt% sodium carbonate solution (the amount of the substance of sodium carbonate was 0.19mol) was added dropwise, and then an epichlorohydrin solution (the concentration was 99.9 wt%) was added in an amount of 46.28g (0.5mol) in terms of the amount of epichlorohydrin added, and reacted at 38 ℃ for 20 minutes to obtain a polyol mixture.

(2) Salt forming reaction:

122.9g (1.6mol) of thiourea and 199g of hydrobromic acid having a concentration of 36 wt% (the amount of the hydrogen bromide substance was 0.9mol) were put into the polyol mixture in the step (2), and a reflux reaction was carried out at 112 ℃ for 2.5 hours to produce an isothiourea salt.

(3) Hydrolysis reaction and post-treatment:

and (3) cooling the isothiourea salt in the step (3) to 40 ℃, adding 330g of 20 wt% sodium hydroxide solution (the amount of sodium hydroxide is 1.65mol), and carrying out hydrolysis reaction at 55 ℃ for 3h to obtain a polythiol crude product.

(4) Adding an pyruvic acid solution (with the concentration of 30 wt%) into the crude polythiol, wherein the mass ratio of the pyruvic acid solution to the crude polythiol is 1: 1, washing for 1h at 50 ℃, adding an isopropanol solution (with the concentration of 98 wt%) into the washed product after liquid separation, and extracting, wherein the volume ratio of the washed product to the isopropanol solution is 1: and 1, after extraction is finished, separating liquid, putting the liquid into a freeze dryer, and drying the liquid for 2 hours at 0 ℃ under the negative pressure of 180Pa to obtain the polythiol.

The polythiol prepared in the example was subjected to colorimetric detection using a spectrocolorimeter (manufacturer Hunter, model Pro lab), and the experimental results were: 7.8.

(II) preparing the optical resin lens, which comprises the following steps:

at 20 ℃, 50g of polythiol prepared in the step, 50g of isocyanate and 0.01g of catalyst dibutyltin dichloride are uniformly mixed, and degassing is carried out for 1h under the negative pressure of 250 Pa; then injecting the mixture into a casting mold consisting of a glass mold and an adhesive tape, putting the casting mold into an oven, heating the temperature from room temperature to 120 ℃ according to the heating rate of 1 ℃/min, and carrying out polymerization reaction for 24 hours at the temperature; after the polymerization, the mold was taken out from the oven and released to obtain an optical resin lens.

The optical resin lens prepared in the embodiment is detected, the texture and the white turbidity of the optical material are detected by a D65 light source of a color lamp box by adopting a standard light source, and the result shows that the lens has no white turbidity phenomenon.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.