Polyphenylene Sulfide Production Technology Development

As polyphenylene sulfide (PPS) is a kind of special engineering plastics possessing excellent comprehensive perfonnance, the demands of global market for PPS grows with each passing day, and the domestic markets nearly all rely on import. At present, PPS production of our country is at industrialization stage. However, a series of problem such as recovering auxiliary and engineering technology still are expected to be resolved, and thus restrict the process of industrialization seriously. In addition, the lower toughness of domestic PPS also hinders its application and development. It will be great important to overcome the difficulties.A new production rout for PPS was investigated. Adopting raw materials such as hydrous sodium sulfide, p-dichlorobenzene and solvent N-methylpyrrolidinone (NMP), PPS resin was synthesized by using high temperature and pressure. And it was purified by water-washing. NMP and auxiliary were also recovered by vacuum rectifications and carbonate precipitation, respectively.Optimal PPS synthesizing conditions were found through adopting orthogonal test method, which involved the reaction temperature 220℃ at earlier stage and 260 ℃ in later stage, solvent consumption 500 ml/(mol p-DCB), consumption of sodium sulfide 1.00 mol/(mol p-DCB) and polymerization aids 40 g/(mol p-DCB). Through the pilot scale experiment, resin-melting viscidity reached 500 Pa.s and the yields of the products was more than 93%.According to comparing results of different washing methods, the washing method may influences melting viscosity and melting index etc, in certain some degree. However, the mechanical, electrical and heat performances of the resin are almost same. It is feasible economically to purify PPS resin by water-washing. When high quality is required, the resin can be purified by an acid-washing.The experiment system is designed which contains vacuum evaporator, vacuum rake drier and vacuum dephlegmator. Through the pilot scale experiment, the yield of solvent recovery reaches more than 95%, and the purity is up to 99. 94%. It can be used satisfactorily.The auxiliary was recovered by carbonate precipitation. It turns to be proved that the yield of recovery of the chlorine lithium is about 93. 6%, the purity is up to99.3%. It has nothing to do with the product quality for reuse.As an instance of PPS application, the research on alloy the nylon 66 and polyphenylene sulfide (PPS/PA66) was investigated. The favorable prescription of enhancing toughness was confirmed. When the component of PA66 is 15%, strike intensity with no gap can reach 58 kJ/m2.The results of the laboratory and pilot scale experiment can be used to provide a base of design considerations for industrialization of PPS. A new industry system of PPS will be able to be developed in the future.