CN117209407A

CN117209407A - Preparation method and application of polythiol compound

Info

Publication number: CN117209407A
Application number: CN202311108775.6A
Authority: CN
Inventors: 邱晶晶; 崔卫华; 马雪菲; 孙志利; 刘红岐
Original assignee: Yifeng New Material Co ltd
Current assignee: Yifeng New Material Co ltd
Priority date: 2023-08-31
Filing date: 2023-08-31
Publication date: 2023-12-12

Abstract

The application belongs to the field of organic new materials, and relates to a preparation method of a polythiol compound and application thereof, wherein the content of iron element in ammonia water is controlled to be less than 100ppm, so that the chromaticity stability of the polythiol compound is improved, and the yellow index of an optical resin lens is further stabilized and qualified.

Description

Preparation method and application of polythiol compound

Technical Field

The application belongs to the field of novel organic materials, and particularly relates to a preparation method and application of a polythiol compound.

Background

Compared with the optical glass lens, the optical resin lens has the advantages of light weight, difficult crack, dyeing, strong antifogging property, dent prevention and the like. At present, various resin materials are applied to the field of optical resin lenses such as spectacles and lenses, and the related requirements for the optical resin lenses are also increasing.

The polythiourethane type optical resin lens has excellent performances of high transparency, low yellowness, high heat resistance, high strength, high refractive index and high Abbe number, and is particularly suitable for producing optical resin lenses with medium and high refractive indexes. The resin lens is mainly prepared from polythiol compounds serving as raw materials. The cured composition prepared by mixing the polythiol compound with the polyiso (thio) cyanate compound is further cured to obtain an optical resin lens. The yellowness index is an important index for the optical resin lens material, and the key to determine the yellowness index of the optical resin is the chromaticity of the polythiol compound.

CN101400648A discloses a polythiol compound represented by formula (1):

the preparation method is characterized in that the preparation method is obtained by reacting 2-mercaptoethanol with epihalohydrin compound and hydrolyzing the epihalohydrin compound by using an intermediate thiourea onium salt, wherein ammonia water is adopted for hydrolysis; however, during further studies, we found that the color of the polythiol compound represented by formula (1) is suddenly increased or decreased, and the stability is poor, which in turn results in poor stability of the yellow index of the optical resin lens obtained by further curing the cured composition prepared by mixing it with the polyiso (thio) cyanate compound. Both of the higher chromaticity of the polythiol compound and the higher yellowness index of the optical resin lens are judged as defective products, which results in lower overall quality and yield of the polythiol compound and the optical resin lens, and further results in higher production cost, and thus improvement is required.

Therefore, how to improve the ability to provide a polythiol compound having more excellent properties has become one of the problems to be solved in the art.

Disclosure of Invention

Aiming at a plurality of defects existing in the prior art, the application provides a preparation method for stabilizing and qualified yellow index of an optical resin lens by controlling the content of impurity iron in ammonia water, which is mainly characterized in that the content of iron element in the ammonia water is controlled to be less than 100ppm, so that the stability of chromaticity of a polythiol compound is improved, and the preparation method of a solidified product obtained by the method is included.

The inventive concept of the present application is as follows:

the inventors have intensively studied various factors that affect the chromaticity of polythiol compounds, and have obtained the following new findings not heretofore available:

although the prior art has a scheme of controlling the iron content in the alkali metal compound to reduce the chromaticity of the polythiol compound in the process of preparing the polyol compound, the effect is poor in practical application, and the inventor finds that the effect of using ammonia water in the process of hydrolyzing isothiourea salt and controlling the iron content in the ammonia water to reduce the chromaticity of the polythiol compound is more remarkable after experiments. Further studies have shown that the iron content of aqueous ammonia used in the synthesis of polythiol compounds can severely affect the chromaticity of the polythiol compounds. Because the impurity iron content in the purchased ammonia water of different batches is high and low, the chromaticity of the produced polythiol compounds of different batches is suddenly high and suddenly low, the product quality is unstable, the yellow index of the optical resin lens is further affected to be unstable, the number of unqualified products is increased, the product percent of pass is lower, and the production cost is increased. Based on this finding, the present application provides a process for producing a polythiol compound, which is capable of producing a polythiol compound of stable chromaticity.

The specific technical scheme of the application is as follows:

a preparation method of a polythiol compound comprises the following specific steps:

performing hydrolysis reaction on isothiourea salt in ammonia water to prepare a polythiol compound represented by a formula (1);

wherein the content of iron element in the ammonia water is below 100 ppm.

The isothiourea salt is obtained by reacting a polyol compound represented by the formula (2) with thiourea in hydrochloric acid,

the polyol compound represented by the above formula (2) is obtained by reacting 2-mercaptoethanol with an epichlorohydrin compound in the presence of a sodium hydroxide solution which is commercially available, preferably, the content of iron element in the sodium hydroxide solution is 10ppm or less.

The preparation methods of the isothiouronium salt and the polyol compound represented by the formula (2) are all conventional technologies, and the applicant has the main characteristic that the content of the iron element is controlled, and other specific steps are the same as those of the prior art and are not repeated here.

The reason why the iron content of ammonia is controlled to 100ppm or less is that the inventors found that the iron contained in the ammonia in the form of impurities forms a complex with the impurities contained in thiourea during the course of the study, resulting in a polythiol compound having a high color. The impurity in the thiourea is thiocyanate radical in ammonium thiocyanate. The thiourea is used in the reaction with the above polyol compound, and ammonium thiocyanate is reacted therewith and is difficult to remove according to the prior art, so that the applicant finally decided that the formation of complex can be suppressed by controlling the content of iron element by the above technical scheme, contributing to the reduction of the chromaticity of the polythiol compound prepared and keeping the chromaticity of the polythiol compound stable.

The iron content in the aqueous ammonia is preferably controlled to be 90ppm or less, more preferably 80ppm or less, still more preferably 70ppm or less, still more preferably 60ppm or less, still more preferably 50ppm or less, still more preferably 40ppm or less, still more preferably 30ppm or less, still more preferably 20ppm or less. The iron content of the aqueous ammonia may be, for example, 1ppm or more or 5ppm or more, but from the viewpoint of reducing chromaticity, the lower the iron content is, the more preferable, and therefore, the lower limit exemplified above. The iron content of the aqueous ammonia may be measured by an atomic absorption spectrometer.

The reduction of the iron content of the aqueous ammonia can be achieved by various conventionally known purification methods, and preferred purification methods include a hydrogen-type strongly acidic cation exchange resin, a sodium-type strongly acidic cation exchange resin, an ammonium-type strongly acidic cation exchange resin purification method, a filter filtration method, a metal ion adsorbent method, and the like.

Other steps of the process for producing a polythiol compound of the present application are the same as those disclosed in CN101400648A, except for the above.

Based on the polythiol compound obtained by the above technique, the inventors further provide a cured composition comprising the polythiol compound obtained above and a polyisocyanate compound or a polyisothiocyanate.

The cured composition can be further used for preparing a cured product by adding a catalyst which is 0.001 to 0.3 percent of the total mass of the polythiol compound and the polyisocyanate compound or the polyisothiocyanate composition to the cured composition, and polymerizing and curing the obtained cured product, namely the polythiourethane type optical resin lens.

In addition, any one or more of a release agent, an ultraviolet absorber, and a toner may be optionally added in the preparation of the cured product.

In summary, compared with the prior art, the method for preparing the cured product obtained by controlling the content of the iron element in the ammonia water to be less than 100ppm improves the stability of the chromaticity of the polythiol compound and further stabilizes and qualifies the yellow index of the optical resin lens.

Detailed Description

The above-described aspects of the present application will be described in further detail by way of the following embodiments, but it should not be construed that the scope of the above-described subject matter of the present application is limited to the following examples. All techniques based on the above description of the present application are within the scope of the present application, and the raw materials used in the following examples are all commercially available products, except for the specific descriptions.

A process for producing a polythiol compound represented by formula (1):

step 1 preparing a polyol compound represented by formula (2):

as a method for obtaining the polyol compound represented by the formula (2) by reacting 2-mercaptoethanol with an epichlorohydrin compound in the presence of a sodium hydroxide solution, for example, the following can be carried out:

first, a sodium hydroxide solution having an iron content of 10ppm or less was added dropwise to 2-mercaptoethanol in a four-necked glass flask to form a mixed solution 1, and epichlorohydrin was added dropwise to the mixed solution 1 to obtain a mixed solution 2 containing a polyol compound represented by the formula (2).

The time for the dropping is not particularly limited, and may be about 0 to 6 hours. In the dropwise addition, the mixed solution 1 may be stirred as needed. In this case, the reaction temperature is preferably not less than 0℃and not more than 100 ℃. The epichlorohydrin may be reacted with 2-mercaptoethanol in a proportion ranging, for example, from 0.1 to 1.0 mol, preferably from 0.3 to 0.7 mol, more preferably from 0.4 to 0.6 mol, relative to 1.0 mol of 2-mercaptoethanol. The sodium hydroxide in the sodium hydroxide solution may be used in an amount of about 0.1 to 1.0 mol, for example, based on 1.0 mol of 2-mercaptoethanol. The mixed solution 2 may be reacted for about 0.5 to 10 hours with heat preservation as needed after the addition of epichlorohydrin. During the heat preservation, the mixed solution 2 may be stirred as needed.

Step 2 is to react a polyol compound represented by the formula (2) with thiourea in hydrochloric acid to obtain isothiourea salt:

hydrochloric acid is added to the mixed solution 2 containing the polyol compound represented by the formula (2), followed by adding thiourea to the mixed solution to perform a reaction. The form of addition of hydrochloric acid is not particularly limited, and hydrochloric acid may be added as an aqueous solution, for example. The concentration of the hydrochloric acid is not particularly limited, and may be, for example, about 10 to 80 mass%.

Hydrochloric acid may be used in a proportion of, for example, 1.0 to 6.0 mol, preferably 2.0 to 5.0 mol, and thiourea may be used in a proportion of, for example, 1.0 to 6.0 mol, preferably 2.0 to 4.0 mol, relative to 1.0 mol of the polyol compound represented by the formula (2). The reaction temperature may be, for example, 70℃to the reflux temperature, preferably about 80 to 120℃and the reaction time may be, for example, about 1 to 24 hours.

Step 3, performing hydrolysis reaction on isothiourea salt in ammonia water to prepare a polythiol compound represented by the formula (1):

the concentration of ammonia water to be added to isothiouronium salt is not particularly limited and may be, for example, 10 to 30%. The aqueous ammonia may be used in a proportion of, for example, 1.0 to 10.0 mol, preferably 4.0 to 7.0 mol, more preferably 3.0 to 6.0 mol, based on 1.0 mol of the polyol compound represented by the formula (2), the reaction temperature may be, for example, about 10 to 80℃and the reaction time may be, for example, about 1 to 10 hours.

In the above production method, the iron content of the aqueous ammonia reacted with the isothiouronium salt is 100ppm or less. This inhibits its formation of a complex with the thiocyanate group in ammonium thiocyanate. The iron content of the aqueous ammonia is preferably 90ppm or less, more preferably 80ppm or less, still more preferably 70ppm or less, still more preferably 60ppm or less, still more preferably 50ppm or less, still more preferably 40ppm or less, still more preferably 30ppm or less, still more preferably 20ppm or less, from the viewpoint of further stabilizing the color of the polythiol compound. The iron content of the aqueous ammonia may be, for example, 1ppm or more or 5ppm or more, but from the viewpoint of reducing chromaticity, the lower the iron content is, the more preferable, and therefore, the lower limit exemplified above. The iron content of the aqueous ammonia may be measured by an atomic absorption spectrometer.

The iron content of the aqueous ammonia may be reduced by various known purification methods. Preferred purification methods for reducing the iron content include a purification method using a hydrogen-type strongly acidic cation exchange resin, a sodium-type strongly acidic cation exchange resin, an ammonium-type strongly acidic cation exchange resin, a filter filtration method, a metal ion adsorbent method, and the like.

The preparation method of the ammonia water with different iron contents is exemplified as follows:

the content of impurity iron in ammonia water is reduced by adopting SMHG-CPN ammonium type cation exchange powder resin purchased from the chemical industry of gallery cis vast, wherein the skeleton of the SMHG-CPN ammonium type cation exchange powder resin is styrene-divinylbenzene copolymer, and the functional group is R-SO ₃ Ionic form is NH ⁴⁺ The particle diameter is 30-150 mu m, the mass total exchange capacity is more than or equal to 4.80mmol/g, NH ⁴⁺ The rate is not less than96.0％。

In the commercial products of ion exchange resins, the resins often contain solvents, materials that do not participate in the polymerization reaction, and small amounts of oligomers, and may also adsorb heavy metal ions such as iron, aluminum, copper, and the like. When the resin is contacted with water, acid, base or other solution, the soluble impurities are transferred into the solution, and pollute the ammonia water quality at the initial stage of use. Therefore, the SMHG-CPN ammonium cation exchange powder resin used in the present application is subjected to pretreatment prior to use. The specific method comprises the following steps: firstly, using saturated saline water, taking the resin with the volume twice that of the resin to be treated, soaking the resin in the saline solution for 18-20 hours, then placing the saline water completely, and rinsing and cleaning the resin with deionized water to ensure that the discharged water is not yellow; then 2% -4% NaOH solution is used, the amount of which is the same as that of the above solution, the resin is washed until the discharged water is nearly neutral after the alkali solution is completely discharged after the solution is soaked for 2-4 hours (or washed with small flow); then 5% hydrochloric acid solution is used, the amount of which is the same as that of the above, the acid solution is discharged after soaking for 4 to 8 hours, and the resin is washed by clear water until the water is discharged to be neutral for standby.

Taking a proper amount of resin to be used in a 1L beaker for later use, mixing the resin with ammonia water containing 500ppm of impurity iron in the beaker, slowly flushing the taken resin into a graduated flask by using the ammonia water, keeping the liquid level 3-4cm higher than a resin layer after the resin is settled, holding the upper part of the graduated flask, vertically and slightly knocking the bottom and the tabletop of the graduated flask vertically, observing that the volume of the resin is kept unchanged, selecting a resin column with proper size according to the volume of the resin, filling the resin column to be 1/2 of the height, fixing the resin column, clamping the resin column at the position of 1/3-2/3 of the column by using a universal clamp, keeping a lower switch in a small flow opening state, slowly flushing the resin in the graduated flask into a resin exchange column by using the ammonia water, and standing for later use after the resin column filling is finished. The ammonia water amount on the layer is regulated according to the actual condition, and the liquid level is kept to be 1-2cm higher than the resin layer. And pressing the resin with a piece of absorbent cotton.

300g of ammonia water containing 500ppm of impurity iron in the same batch is put in a plastic measuring cylinder, placed on a platform slightly higher than an iron frame table, opened a cock under an exchange column, dripped into a resin exchange column by a peristaltic metering pump, the flow rate is controlled to be 3BV/h, and after the ammonia water in the system is exhausted, the iron ion content in the collected ammonia water is detected to be 10ppm.

The peristaltic metering pump is used for controlling the flow rates to be 6BV/h, 10BV/h, 11BV/h, 12BV/h, 13BV/h and 14BV/h respectively, and other operations are the same as the steps of the preparation method of the ammonia water with different iron contents, and the iron ion contents in the ammonia water collected under the flow rates are detected to be 40ppm, 80ppm, 90ppm, 100ppm, 110ppm and 120ppm respectively.

The above steps may be performed in the atmosphere or in an atmosphere other than the atmosphere, for example, in a nitrogen atmosphere.

According to the above-described steps, a polythiol compound represented by formula (1) can be obtained. The colour of the polythiol compound can be evaluated by the value of b. The smaller the value of b represents the lower the chromaticity. According to the method for producing a polythiol compound provided by the present application, a polythiol compound having, for example, a b value of 1.48 or less (for example, 0.59 to 1.48) can be stably obtained. The cured product (polythiourethane type optical resin lens) obtained by curing the polythiol compound and the polyiso (thio) cyanate compound can have various characteristics suitable for spectacle lens base materials, such as high refractive index and high heat resistance.

The preparation method of the condensate comprises the following steps:

curing composition

By mixing the polythiol compound represented by the formula (1) prepared above with a polyiso (thio) cyanate compound, a cured composition can be obtained.

The polyisocyanate compound that can be used in the present application may be any conventional one, and is not particularly limited, but specific examples thereof include:

tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, 4' -diisocyanate dicyclohexylmethane, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl m-xylylene diisocyanate, dithiodipropyl diisocyanate, dithiodiethyl diisocyanate, 2, 5-diisocyanatothiophene, 2, 5-diisocyanatothiomethyl-1, 4-dithiane, 2, 5-diisocyanate-1, 4-dithiane, thiodihexyl diisocyanate, thiodipropyl diisocyanate, bis (isocyanatomethyl) adamantane, bis (isocyanatomethyl) tetrahydrothiophene, 2, 6-bis (isocyanatomethyl) naphthalene, 1, 5-naphthalene diisocyanate, diethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, toluene diisocyanate, o-tolidine diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, triphenylmethane triisocyanate and the like.

Preferably, the catalyst is selected from hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate, m-xylylene diisocyanate and hydrogenated m-xylylene diisocyanate. Most preferably, the catalyst is selected from hydrogenated m-xylylene diisocyanate, norbornane diisocyanate and m-xylylene diisocyanate. These compounds may be used alone or in combination of two or more.

The above-mentioned cured composition can be prepared by mixing the above-mentioned polythiol compound with a polyiso (thio) cyanate compound. The mixing ratio of the polythiol compound and the polyiso (thio) cyanate compound in the above-mentioned cured composition is not particularly limited, and for example, the ratio is calculated by mole:

the thiol group contained in the polythiol compound and the iso (thio) cyanate group contained in the poly (iso (thio) cyanate compound may be in the range of 0.5 to 3.0, preferably in the range of 0.6 to 2.0, more preferably in the range of 0.8 to 1.6. When the mixing ratio is within the above range, it is preferable to obtain a cured composition which can provide a cured product having various excellent physical properties such as a high refractive index and high heat resistance.

In one embodiment, the polythiol compound may be contained in an amount of, for example, 40% by mass or more (for example, 40 to 70% by mass) relative to 100% by mass of the total amount of the cured composition.

In order to provide the cured product of the present application with better physical properties, handleability, polymerization reactivity, etc., any one or more of a catalyst, a mold release agent, an ultraviolet absorber, and a toner is added as necessary.

The catalyst is selected from dibutyl tin dilaurate, dibutyl tin dichloride, dibutyl tin oxide and stannous octoate. Preferably, the catalyst is selected from dibutyl tin dilaurate and dibutyl tin dichloride.

The amount of the catalyst to be added varies depending on the components of the cured composition, and is 0.001 to 0.3%, preferably 0.01 to 0.1%, more preferably 0.01 to 0.05% based on 100% by mass of the cured composition.

An amount of the catalyst added less than 0.001% may cause incomplete polymerization, resulting in poor mechanical formation of the optical resin lens. When the catalyst addition amount is more than 0.3%, the polymerization rate may be too high, resulting in an increase in the color tone of the optical resin lens.

In addition to the catalyst, the composition of the cured composition may be added with a conventional release agent, an ultraviolet absorber, a toner, and the like as required, thereby further improving the usability of the optical resin lens.

Process for producing cured product

The cured product obtained by curing the above-mentioned cured composition can be used as a material for optical members such as spectacle lenses, in particular, polythiourethane type optical resin lenses. The chromaticity of the polythiourethane type optical resin lens can be evaluated by YI value. The smaller YI value means that the lower the chromaticity of the polythiourethane type optical resin lens. By using the polythiol compound obtained by the method for producing a polythiol compound provided by the present application as a synthetic raw material, a polythiourethane type optical resin lens (cured product) having a YI value of 1.51 or less (for example, 1.01 to 1.51) can be obtained.

The curing reaction of the polythiol compound with the polyiso (thio) cyanate compound described above can be carried out by various conventional curing treatments capable of curing the curing composition.

For example, a cured product (polythiourethane type optical resin lens) is obtained by casting a curable composition into a mold for a spectacle lens base material sealed with an adhesive tape, and polymerizing the curable composition by heating.

After the completion of curing, the temperature is lowered to release the cured product from the mold, thereby obtaining a cured product having a spectacle lens shape. The cured product of the mold release is preferably used as a lens substrate for an eyeglass lens. The cured product after demolding may be subjected to polishing, etching, cutting, polishing, etc. by a precise automated numerical control machine to obtain progressive addition lenses, antifatigue lenses, special-strength lenses, etc. having various functions. And then the lenses with various functions are cleaned, hardened, coated and inspected to form qualified lenses which are radiation-proof, static-resistant, scratch-resistant, pollution-proof and easier to clean. The known techniques can be applied to these steps without any limitation. In this way, an eyeglass lens in which the lens base material is the cured product can be obtained. Further, the eyeglass lens can be attached to the frame to obtain eyeglasses.

The specific evaluation methods employed in the following examples were as follows:

(1) Iron content of aqueous ammonia

The measurement was performed using an atomic absorption spectrometer of Agilent 240FS AA.

(2) Evaluation of coloring of polythiol Compound (chroma)

The b-value of the polythiol compound obtained in examples and comparative examples was measured using a spectrophotometer U-3500 manufactured by Hitachi, inc. at an optical path length of 10 mm.

(3) Evaluation of coloration of cured product (YI value)

YI values of the cured products (0.00D, center wall thickness: 1.8 mm) obtained in examples and comparative examples were measured using a spectral transmittance measuring device DOT-3 manufactured by color technology research, inc.

The polythiol compound represented by formula (1) was obtained in the following examples and comparative examples by GPC (gel permeation chromatography), HPLC (high performance liquid chromatography) and MS (mass spectrometry).

Pretreatment of ammonia water

The iron content of the purchased aqueous ammonia was measured by the evaluation method of (1) above and found to be 500ppm. And the iron content of the ammonia water obtained by carrying out cation exchange resin treatment on the ammonia water by the preparation method of the ammonia water with different iron contents is 10-120ppm. In the following examples, the ammonia water obtained as described above was used.

Example 1

Synthesis of polythiol Compound represented by the formula (1)

2-mercaptoethanol having a purity of 99.80% by weight was stored in a glass vessel under a nitrogen stream, 79.8g of mercaptoethanol was charged into a 1L four-necked flask equipped with a stirrer, a nitrogen purge tube and a thermometer, 72.8g of an aqueous solution of 32% by weight sodium hydroxide was dropwise added at 30℃over 30 minutes, 53.5g of epichlorohydrin was then dropwise added over 1 hour, and the temperature was maintained for 30 minutes.

200g of 36% strength by weight hydrochloric acid and 130g of thiourea of 99.90% purity were then added and refluxed at 110℃for 3 hours to give isothiouronium salt.

Cooling to room temperature, adding 250g of ammonia water with concentration of 18 wt% and iron content of 10ppm, reacting for 3 hours at 55 ℃, standing for layering, separating a lower organic phase to obtain a polythiol compound crude product shown in a formula (1), adding hydrochloric acid to adjust pH to about 6, adding water for washing twice, heating and decompressing for dehydration to obtain the polythiol compound shown in the formula (1), wherein b-value of the obtained polythiol compound is 0.59.

Preparation of polythiourethane type optical resin lens

52 parts by mass of xylylene diisocyanate, 0.01 part by mass of dibutyltin dichloride as a curing catalyst, 0.08 part by mass of acid phosphate as a mold release agent, and 0.60 part by mass of an ultraviolet absorber (UV 329) were mixed and dissolved. Further, 48 parts by mass of the polythiol compound obtained in example 1 was added thereto and mixed to obtain a mixed solution. The mixture was defoamed at 200Pa for 1 hour, and then filtered through a PTFE (polytetrafluoroethylene) filter having a pore size of 5.0. Mu.m.

The filtered mixture (cured composition) was poured into a mold for lens comprising a glass mold having a diameter of 75mm and 0.00D and an adhesive tape. The molded die was put into an oven, slowly heated from 20℃to 120℃over 24 hours, and kept at 120℃for 4 hours to carry out polymerization (curing reaction). After the polymerization, the molded article was taken out of the oven after the temperature was lowered to 60℃and released from the oven to obtain a cured article (polythiourethane type optical resin lens). The obtained polythiourethane type optical resin lens was further annealed in an oven at a temperature of 120℃for 3 hours, and the YI value of the finally obtained optical resin lens was 1.01.

Examples 2 to 5 and comparative examples 1 and 2

The synthesis of the polythiol compound and the production of the cured product were performed in the same manner as in example 1, except that aqueous ammonia having an iron ion content shown in table 1 below was used.

Comparative example 3

The synthesis of a polythiol compound and the production of a cured product were performed in the same manner as in example 1, except that commercially available aqueous ammonia having an iron ion content of 500ppm was used.

Comparative example 4

92.5g (1.0 mol) of epichlorohydrin was added dropwise to a mixture of 78.1g (1.0 mol) of 2-mercaptoethanol and 2.0g of triethylamine at an internal temperature of 35 to 40℃for 1 hour, and the mixture was aged at an internal temperature of 40℃for 1 hour to give a reaction solution 1.

125.0g (0.5 mol) of an aqueous solution of sodium sulfide nonahydrate (iron ion content: 80 ppm) dissolved in 100g of pure water was added dropwise to the reaction solution 1 after the aging at an internal temperature of 40 to 45℃for 1 hour, and the mixture was further aged at an internal temperature of 45℃for 1 hour to obtain a reaction solution 2.

303.8g (3.0 mol) of 36% hydrochloric acid and 190.3g (2.5 mol) of thiourea were added to the above-mentioned reaction solution 2, and they were heated and stirred at an internal temperature of 110℃for 9 hours to obtain a reaction solution 3.

After cooling the reaction solution 3 to room temperature, 400m1 of toluene was added, 600g (4.5 mol) of a 30% aqueous sodium hydroxide solution was slowly added, and hydrolysis was performed at an internal temperature of 60℃for 4 hours to obtain a reaction solution 4.

The reaction solution 4 was allowed to stand to separate into an aqueous layer and an organic layer, and then the organic layer was taken out, and the organic layer was washed with 36% hydrochloric acid 100m1, water 100m1, and then 2 times. Toluene in the washed organic layer was distilled off by a rotary evaporator to obtain a polythiol compound. The b-value of the obtained polythiol compound was 1.72. The obtained polythiol compound was produced in the same manner as in example 1 to give a cured product, and the YI value of the finally obtained optical resin lens was 1.98.

TABLE 1

From the results shown in table 1, it can be confirmed that: by using ammonia water having an iron content of 100ppm or less in the above-mentioned process for producing a polythiol compound, a polythiol compound having a significantly reduced chromaticity is unexpectedly obtained, and the b-value is stabilized at 1.48 or less; and it was found from comparison of the data of comparative example 4 and examples 1 to 5 that the b-value, i.e., the chromaticity, was further reduced in the present application by controlling the use of aqueous ammonia during the hydrolysis of isothiourea salt and controlling the iron content in aqueous ammonia, as compared with the polythiol compound obtained by controlling the iron content in the alkali metal compound during the preparation of the polyol compound in the prior art. Further, by using the polythiol compound, a polythiourethane type optical resin lens having a further reduced yellow index can be obtained, and it can be seen that the present application achieves unexpected technical effects as compared with the prior art.

The above examples and the corresponding ratio data further confirm that the polythiol compound and the cured product containing the compound of the present application can provide a polythiol compound for stabilizing an optical resin lens having a low chromaticity and a polythiourethane optical resin lens having a low yellow index. The method has great application value in the field of preparation of various optical components such as spectacle lenses.

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 application. Thus, the present application 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.

Claims

1. A preparation method of a polythiol compound comprises the following specific steps:

the method is characterized in that: wherein the content of iron element in the ammonia water is below 100 ppm.

2. The process for producing a polythiol compound according to claim 1, wherein: the isothiourea salt is obtained by reacting a polyol compound represented by the formula (2) with thiourea in hydrochloric acid,

3. the process for producing a polythiol compound according to claim 3, wherein: the polyol compound represented by the formula (2) is obtained by reacting 2-mercaptoethanol with an epichlorohydrin compound in the presence of a sodium hydroxide solution in which the content of iron element is 10ppm or less.

4. A cured composition characterized by: a composition comprising the polythiol compound obtained by the process of any one of claims 1 to 4, and a polyisocyanate compound or a polyisothiocyanate.

5. A process for preparing a cured product using the cured composition of claim 4, comprising the steps of: the polythiol compound and the polyisocyanate compound or the polyisothiocyanate are added with a catalyst accounting for 0.001 to 0.3 percent of the total mass of the polythiol compound and the polyisocyanate compound or the polyisothiocyanate composition for reaction, and the raw materials are polymerized and cured to obtain a cured product, namely the polythiourethane type optical resin lens.

6. Use of the cured composition of claim 4, wherein: as a lens substrate for spectacle lenses.