阅读说明：本技术 一种降低聚硫醇化合物色度的方法 (Method for reducing chroma of polythiol compound ) 是由 张超 梁万根 崔卫华 费潇瑶 宋吻吻 于 2019-10-25 设计创作，主要内容包括：本发明涉及聚硫醇固化剂生产领域,具体提供了一种降低聚硫醇化合物色度的方法,包括以下步骤：将聚硫醇化合物与超纯水混合,在加热搅拌的条件下再加入酸和还原剂进行酸化还原反应,加入酸为还原反应提供一种酸性环境,反应结束后,过滤,分层,水洗,精馏得到色度降低的聚硫醇。本发明针对已经生产出来的色度偏高的聚硫醇固化剂或者由于某些原因导致色度偏高的聚硫醇固化剂类产品,通过与特定的还原剂进行反应,即可降低此聚硫醇类化合物的色度,方法简单,成本低。(The invention relates to the field of polythiol curing agent production, and particularly provides a method for reducing chroma of a polythiol compound, which comprises the following steps: and (2) mixing the polythiol compound with ultrapure water, adding acid and a reducing agent under the condition of heating and stirring for carrying out acidification reduction reaction, adding the acid to provide an acid environment for the reduction reaction, and after the reaction is finished, filtering, layering, washing with water and rectifying to obtain the polythiol with reduced chromaticity. The invention can reduce the chroma of the polythiol compound by reacting the produced polythiol curing agent with high chroma or polythiol curing agent products with high chroma caused by some reasons with a specific reducing agent, and has the advantages of simple method and low cost.)

1. A method for reducing the color of a polythiol compound. Wherein the polythiol compound is selected from compounds having the following structure:

wherein R is not particularly limited and is a polyether polyol which is well known to those skilled in the art, and n is an integer between 1 and 20;

the method is characterized in that: the method comprises the following specific steps:

1) mixing the polythiol compound and ultrapure water, and starting heating and stirring; adding acid when the temperature is raised to a certain temperature to provide an acid environment for reduction reaction, wherein the pH value is 2-4, and then adding a reducing agent for reaction;

2) step 1), filtering after the reaction is finished, standing for layering, separating out washing water, adding ultrapure water for washing, and controlling the temperature and the washing time;

3) standing and layering after the step 2) to separate a polythiol material, and distilling to obtain a decolored polythiol compound;

wherein the mass ratio of the polythiol to the ultrapure water in the step 1) is 1: (0.5 to 10);

the mass ratio of the polythiol to the reducing agent is 10: (0.01-10).

2. The method of reducing the color of a polythiol compound according to claim 1, wherein:

the mass ratio of the polythiol to the ultrapure water in the step 1) is 1: (0.8-2.5); the mass ratio of the polythiol to the reducing agent is 1: (0.1-5);

the acid adopted in the step 1) is one of acetic acid, sulfuric acid, hydrochloric acid or nitric acid;

the reducing agent is one or more of sulfite, sodium borohydride, zinc powder, lithium aluminum hydride, sodium gluconate or sodium hydrosulfite.

3. The method of reducing the color of a polythiol compound according to claim 1, wherein:

the reaction temperature in the step 1) is 50-110 ℃, and the reaction time is 1-2 h;

the washing temperature in the step 2) is 50-110 ℃, and the washing time is 1-2 h; the amount of water used for washing is 1-1.5 times of the mass of the polythiol.

4. The method of claim 3 for reducing the color of a polythiol compound, wherein: the reaction temperature and the washing temperature are 60-90 ℃.

Technical Field

The invention relates to the field of polythiol curing agent production, and particularly provides a method for reducing chroma of polythiol compounds.

Background

A novel polythiol curing agent such as polythiol compound is a low-temperature fast curing epoxy curing agent used in recent years, and the terminal group of the novel polythiol curing agent has more than two sulfydryl groups, so that the novel polythiol curing agent can be fast cured with epoxy resin at low temperature. Compared with other epoxy curing agents, the epoxy curing agent has the remarkable characteristics of low curing temperature, quick curing, thin-layer curing and the like, is a product which cannot be replaced by other curing agents, and is mainly applied to devices with higher precision such as optical elements and the like.

The prior technology for preparing the polythiol curing agent mainly adopts a sodium hydrosulfide nucleophilic method, and adopts a sodium hydrosulfide raw material to synthesize polythiol, wherein the polythiol generates a disulfide and a polysulfide in a side reaction in the synthesis process, and the polysulfide has large chroma, such as the polythiol prepared by the preparation and activity research of the polythiol curing agent made by Liaoyinxing of Xiamen university has large chroma and is light yellow, so the obvious problem exists; therefore, how to reduce the chroma of the polythiol curing agent per se becomes one of the problems to be solved urgently by the technical personnel in the field.

Disclosure of Invention

Aiming at the defects of the technology, the invention provides a method for reducing the chroma of a polythiol compound, which comprises the following steps: and (2) mixing the polythiol compound with ultrapure water, adding acid and a reducing agent under the condition of heating and stirring for carrying out acidification reduction reaction, adding the acid to provide an acid environment for the reduction reaction, and after the reaction is finished, filtering, layering, washing with water and rectifying to obtain the polythiol with reduced chromaticity. The invention can reduce the chroma of the polythiol compound by reacting the produced polythiol curing agent with high chroma or polythiol curing agent products with high chroma caused by some reasons with a specific reducing agent, and has the advantages of simple method and low cost.

The principle of the invention is that reducing agent is added into produced polythiol curing agent with higher chroma or polythiol curing agent products with higher chroma caused by some reasons in acid environment to react with polysulfide contained in polythiol in later period, so as to reduce polysulfide into mercaptan.

The specific technical scheme of the invention is as follows:

a method for reducing the color of a polythiol compound selected from compounds having the structure:

wherein R is not particularly limited and is a polyether polyol which is well known to those skilled in the art, and n is an integer between 1 and 20;

the method comprises the following specific steps:

1) mixing the polythiol compound and ultrapure water, and starting heating and stirring; adding acid when the temperature is raised to a certain temperature to provide an acid environment for reduction reaction, wherein the pH is between 2 and 4, and then adding a reducing agent for reaction;

2) step 1), filtering after the reaction is finished, standing for layering, separating out washing water, adding ultrapure water for washing, and controlling the temperature and the washing time;

3) standing and layering after the step 2) to separate a polythiol material, and distilling to obtain a decolored polythiol compound;

wherein the mass ratio of the polythiol to the ultrapure water in the step 1) is 1: (0.5 to 10);

the mass ratio of the polythiol to the reducing agent is 10: (0.01-10);

further, the mass ratio of polythiol to ultrapure water is 1: (0.8-2.5); the mass ratio of the polythiol to the reducing agent is 1: (0.1-5);

the acid adopted in the step 1) is one of acetic acid, sulfuric acid, hydrochloric acid or nitric acid;

the reducing agent is one or more of sulfite, sodium borohydride, zinc powder, lithium aluminum hydride, sodium gluconate or sodium hydrosulfite;

the reaction temperature in the step 1) is 50-110 ℃, and the reaction time is 1-2 h;

the washing temperature in the step 2) is 50-110 ℃, and the washing time is 1-2 h; the amount of water used for washing is 1-1.5 times of the mass of the polythiol;

furthermore, the reaction temperature and the washing temperature are preferably 60-90 ℃;

the reaction temperature and the washing temperature are the optimum temperature ranges preferred by the inventor, the polythiol is better decolorized in the optimum temperature ranges, and the reaction and washing time is kept for 1-2 h to ensure the decolorization.

The distillation condition in the step 3) is that the distillation temperature is 70-90 ℃, and the negative pressure is kept at-0.095 MPa.

Detailed Description

The present invention will be described in further detail with reference to the following examples, but it should not be construed that the scope of the above subject matter is limited to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention, and the following embodiments are all completed by adopting the conventional prior art except for the specific description.