Method for dehydrating sodium sulfide polyhydrate in polyphenylene sulfide production

Abstract

The invention relates to the technical field of sodium sulfide dehydration, particularly to a method for dehydrating sodium sulfide polyhydrate in polyphenylene sulfide production. The specific schemeis that the method comprises: adding sodium sulfide polyhydrate, NMP, an auxiliary agent and sodium hydroxide into a reaction kettle, and heating and dehydrating the materials in the reaction kettle;making the mixed steam generated by the dehydrating enter a separator, separating, returning the separated liquid returns to the reaction kettle, and carrying out condensation recovery and waste gastreatment on the separated gas; and adding molten p-dichlorobenzene into the reaction kettle, and carrying out a step-by-step heating reaction on the mixed solution in the reaction kettle to finally obtain the polyphenylene sulfide product. In the prior art, the existing PPS production is high in dehydration temperature, performs two-section evaporation dehydration by requiring steam and other energy sources, is instable, and does not have the fixed dehydration time, and the process control is instable during dehydration to cause a large amount of liquid carrying so as to cause the high NMP content in the dehydrated water. According to the invention, the problem in the prior art is solved.

Description

technical field [0001] The invention relates to the technical field of sodium sulfide dehydration, in particular to a method for polyhydrate sodium sulfide dehydration in the production of polyphenylene sulfide. Background technique [0002] Polyphenylene sulfide (hereinafter referred to as PPS) resin has gradually become the most cost-effective special engineering material since its industrialization. There are many processes for producing PPS. At present, the industrialized mature method is the sodium sulfide method. This technology was first introduced by the Philippine Developed by Philips Petroleum Company in 1967, it was officially industrialized in 1973. In 1987, its products occupied the world. It was not until 1984 that the company's patent expired that countries such as Europe and Japan successively developed on the basis of their original technology and the same production principle. Out of their respective process routes, in 1986, Kureha Chemical Industry Co., Lt...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a method for the dehydration of polyhydrated sodium sulfide in the production of polyphenylene sulfide, to solve the problem that the dehydration temperature in the existing PPS production is high, steam and other energy sources are required to carry out two-stage evaporation dehydration, and it is unstable and often occurs during dehydration. , less time, unstable process control during dehydration, resulting in a large amount of liquid, resulting in about 50% to 80% of the NMP content in the extracted water, requiring secondary separation, and a large amount of new NMP needs to be added to the kettle, resulting in energy consumption High, high cost, the key is that the instability of the molar ratio of the sodium sulfide solution after dehydration to the molar ratio of p-dichlorobenzene directly leads to a wide range of molecular weight fluctuations and unstable quality.

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