阅读说明：本技术 一种延长对苯二胺存储期的方法 (Method for prolonging storage period of p-phenylenediamine ) 是由 赵思远 金汉强 季峰崎 杨忠林 丁红霞 于 2018-06-25 设计创作，主要内容包括：本发明通过在对二胺精馏前加入一定量的抗氧化剂,一方面通过抗氧化剂进一步氧化邻位和间位的异构体,使这两种物质生成沸点更高的氧化物,另外阻止对苯二胺自由基的形成,从而从根本上解决对苯二胺易变色问题,大大延长对苯二胺的储存时间。(According to the invention, a certain amount of antioxidant is added before the diamine is rectified, so that ortho-position and meta-position isomers are further oxidized by the antioxidant, the two substances generate oxides with higher boiling points, and the formation of p-phenylenediamine free radicals is prevented, thereby fundamentally solving the problem of easy discoloration of the p-phenylenediamine and greatly prolonging the storage time of the p-phenylenediamine.)

1. A method for prolonging the storage life of p-phenylenediamine is characterized in that the p-phenylenediamine is obtained by adding an antioxidant into a p-nitroaniline hydrogenation solution or a p-phenylenediamine solution reduced by purchasing other processes and then rectifying, wherein the antioxidant is prepared by mixing inorganic sulfide, sulfate, metal oxide and organic phenols.

2. The method according to claim 1, characterized in that the weight percentage of inorganic sulfides, sulfates, metal oxides, organic phenols in the antioxidant is 10 ~ 20%, 60 ~ 70%, 5 ~ 20%, 5 ~ 10%.

3. The method according to claim 1, wherein the inorganic sulfide is sodium sulfide, the sulfate is one or two of sodium sulfate and zinc sulfate, the metal oxide is one or two of zinc oxide and titanium oxide, and the organic phenol is a mixture of tert-butyl phenol and 2, 6-di-tert-butyl phenol.

4. The process of claim 1 wherein the antioxidant is added in an amount of 0.1 ~ 0.8.8% of the crude p-phenylenediamine, the addition temperature is 60 ~ 90 ℃, and the stirring time after addition is 90 ~ 150 min.

5. The process of claim 4, wherein the antioxidant is added in an amount of 0.5 ~ 0.6.6% based on crude p-phenylenediamine, the addition temperature is 80 ~ 85 ℃, and the stirring time after addition is 120 min.

6. A process according to claim 3, characterized in that the sodium sulphide is added in an amount of 15 ~ 18% of the total antioxidants.

7. A method according to claim 3, characterized in that the amount of zinc sulphate added in the sulphate is 70 ~ 100% of the total sulphate amount.

8. The method of claim 3, wherein the amount of zinc oxide added to the metal oxide is 30% 30 ~ 100% and the amount of titanium oxide added is 10% ~ 70% of the total metal oxide.

9. The process of claim 3 wherein the amount of tertiary butyl phenol added to the organic phenol is 30 ~ 50% of the organic phenol, the amount of 2, 6-di-tertiary butyl phenol added is 50 ~ 70% of the organic phenol, and the amount of tertiary butyl phenol added is optimized to be 40 ~ 45% of the organic phenol.

10. The process according to claim 9, wherein the amount of tert-butylphenol added to the organic phenol is 40 ~ 45% of the organic phenol.

Technical Field

The invention relates to an antioxidant auxiliary agent in a p-phenylenediamine production process, and belongs to the field of fine chemical engineering.

Background

The production process of p-phenylenediamine at home and abroad is p-nitroaniline hydrogenation method and sodium sulfide reduction p-nitroaniline method, but the p-phenylenediamine produced by any method has short storage time and basically begins to change color after about three months. Particularly affecting the application of p-phenylenediamine in aramid 1414.

The main reason for the discoloration of p-phenylenediamine is that a small amount of ortho-and meta-isomers are also present in p-nitroaniline, and impurities such as o-phenylenediamine and m-phenylenediamine are produced during hydrogenation or during hydrogenation. further-NH in p-phenylenediamine₂Is a color-aiding group, is oxidized in the air to generate peroxide, is a free radical chain reaction, and generates free radical intermediates which can further react to generate various more complex macromolecular impurities.

P-phenylenediamine is gradually oxidized to form p-phenylenediamine when contacting with air or water, and then the p-phenylenediamine is further reacted to form a polymer, so that the color of the p-phenylenediamine is changed. In addition, the generation of free radicals from p-phenylenediamine can be initiated by light and heat, which is also one of the reasons for the discoloration of the p-phenylenediamine.

At present, the physical method of taking measures for the color change of the product by the p-phenylenediamine production enterprise is vacuum packaging, nitrogen gas packaging and desiccant adding in the packaging. However, the problem of short storage life caused by the easy discoloration of p-phenylenediamine cannot be fundamentally solved, and the physical method can only slightly prolong the storage time of p-phenylenediamine.

The patent CN200410041334.X p-phenylenediamine crystallization method relates to a new p-phenylenediamine crystallization method, which is characterized in that distilled p-phenylenediamine is received in solvent water, and is dissolved, cooled and crystallized to form granular crystals, and then the granular crystals are separated and dried in vacuum to obtain the finished product. The invention prevents the oxidation reaction by cutting off the source (air, etc.) of the oxidation reaction with the p-phenylenediamine. The p-phenylenediamine is crystallized into a high-purity and high-quality product according to strict lattice arrangement through natural crystallization, the white yield can reach 100 percent, the p-phenylenediamine production of domestic manufacturers is mainly vacuum rectification, but the rectified product still has short storage time, and particularly has shorter storage time in plum rain seasons and high temperature in summer.

The patent CN200810035408.7 discloses a refining method of p-phenylenediamine, which combines rectification and melt crystallization, utilizes the condensate of the rectification product to directly carry out melt crystallization purification, and obtains a high-purity product through at least one crystallization and fractional crystallization for sweating. According to the invention, the p-phenylenediamine is refined by adopting a process of combining rectification and melt crystallization, and the high-purity and high-quality p-phenylenediamine product can be obtained by controlling the operation parameters, wherein the product quality meets the quality requirement of a polymer-grade product, and the high-quality p-phenylenediamine which cannot be realized by adopting the rectification process is obtained. However, the p-phenylenediamine produced by the method has the defects of short storage time (about three months), and easy color change caused by moisture or exposure to air.

The above patent uses a physical method to realize high purity of p-phenylenediamine, thereby achieving the purpose of prolonging the storage period, and the physical method cannot fundamentally solve the problem that p-phenylenediamine is easy to discolor.

Disclosure of Invention

The purpose of the invention is as follows: by using a chemical method and adding a certain amount of antioxidant, the factor of discoloration of p-phenylenediamine in the storage process is inhibited, so that the discoloration of p-phenylenediamine is fundamentally avoided, and the storage period of p-phenylenediamine is greatly prolonged.

The main technical scheme of the invention is as follows: the method for prolonging the storage life of p-phenylenediamine is characterized in that the p-phenylenediamine is obtained by adding an antioxidant into a p-nitroaniline hydrogenation solution or a p-phenylenediamine solution reduced by purchasing other processes and then rectifying, wherein the antioxidant is prepared by mixing inorganic sulfide, sulfate, metal oxide and organic phenols.

The weight percentages of inorganic sulfide, sulfate, metal oxide and organic phenol in the antioxidant are 10 ~ 20%, 60 ~ 70%, 5 ~ 20% and 5 ~ 10%.

The inorganic sulfide is sodium sulfide, the sulfate is one or a mixture of two of sodium sulfate and zinc sulfate, the metal oxide is one or a mixture of two of zinc oxide and titanium oxide, and the organic phenol is a mixture of tert-butyl phenol and 2, 6-di-tert-butyl phenol.

The adding amount of the antioxidant is 0.1 ~ 0.8.8% of the crude p-phenylenediamine, the adding temperature is 60 ~ 90 ℃, the optimized temperature is 80 ~ 85 ℃, the optimized adding amount is 0.5 ~ 0.6.6%, the stirring time after adding is 90 ~ 150min, and the optimized stirring time is 120 min.

The optimum addition of sodium sulfide was 15 ~ 18% of the total antioxidant.

The adding amount of the zinc sulfate in the sulfate is 70 ~ 100% of the total amount of the sulfate, and the adding amount of the zinc sulfate in the optimized sulfate is 80 ~ 90%.

The addition amount of zinc oxide in the metal oxide is 30 ~ 100% of the total metal oxide, the addition amount of titanium oxide is 10% ~ 70% of the total metal oxide, and the addition amount of optimized zinc oxide is 60 ~ 80%.

The addition amount of the tert-butyl phenol in the organic phenols is 30 ~ 50% of the organic phenols, the addition amount of the 2, 6-di-tert-butyl phenol is 50 ~ 70% of the organic phenols, and the addition amount of the optimized tert-butyl phenol is 40 ~ 45% of the organic phenols.

According to the invention, a certain amount of antioxidant is added before the diamine is rectified, so that ortho-position and meta-position isomers are further oxidized by the antioxidant, the two substances generate oxides with higher boiling points, and the formation of p-phenylenediamine free radicals is prevented, thereby fundamentally solving the problem of easy discoloration of the p-phenylenediamine and greatly prolonging the storage time of the p-phenylenediamine.

Detailed Description

The technical solution of the present invention is further illustrated by the following examples.