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Polyester chips bai Scientific name: polyethylene te […]
Polyester chips bai
Scientific name: polyethylene terephthalate du, English abbreviation: PET
is made by polymerizing Zhi terephthalic acid (PTA) and ethylene glycol (EG).
At present, it is mainly used for bottle-grade polyester (widely used for packaging of various beverages, especially carbonated drinks), polyester film (mainly used for packaging materials, films and tapes, etc.) and polyester for chemical fiber.China polyester DTY yarns Company
The earliest history of polyester series products, it can be said that in 1928, Carothers of DuPont Company of the United States studied the polycondensation of aliphatic dibasic acid and ethylene glycol, and the earliest made fiber from polyester. In the autumn of 1931, Carothers (Carothers) officially published its research results in the American Chemical Society. The fiber has silk luster, strength and elasticity are comparable to silk, but because of its low melting point, easy hydrolysis and alkali resistance, it has no practical value. But this study first confirmed that polyester can be made into fibers. In 1941, Winfield and Dickson of the British Calico Printing and Dyeing Workers Association (hereinafter referred to as CPA), inspired by the work of Carothers, continued to study polyester, and CPA obtained a patent in 1942. It can be said that polyester (PET) was the first to achieve industrial production in the UK in 1949. Because of its excellent consumption and high strength, it has become the largest variety of synthetic fibers.
Polyester route includes direct esterification method (PTA method) and transesterification method (DMT method). The PTA method has the advantages of low raw material consumption and short reaction time. Since the 1980s, it has become the main process of polyester and the preferred technical route. The large-scale production line is a continuous production process, and the semi-continuous and intermittent production processes are suitable for small and medium-sized production devices. The continuous process of the PTA method mainly includes several technologies such as the German Zimmer company, the American DuPont company, the Swiss Inventa company, and the Japanese Konebo company. Among them, the technology of Jima, Yvonda, and Zhongfang is a 5-kettle process, and DuPont has developed a 3-kettle process (currently developing a 2-kettle process). The polycondensation process is basically similar, the difference is the esterification process. For example, the 5 kettle process uses lower temperature and pressure esterification, while the 3 kettle process uses a high ethylene glycol (EG)/PTA molar ratio and a higher esterification temperature to strengthen the reaction conditions, speed up the reaction speed, and shorten the reaction time. . The total reaction time is 10 hours for 5 kettles and 3.5 hours for 3 kettles. At present, large-scale polyester companies in the world all adopt the distributed control system (DCS) for production control and management, and simulate the whole process or single-pot process.
In early 2003, Inventa-Fisher (I-F) announced its polyester production process and energy consumption. This process produces resin grade or textile grade polyester from the reaction of PTA or DMT with ethylene glycol (EG). Using the 4 kettle (4R) process, a slurry composed of PTA and EG or molten DMT and EG enters the first esterification/transesterification reactor, and the reaction proceeds at a higher pressure and temperature (200 to 270°C). The oligomer enters the second cascade agitated reactor and reacts at a lower pressure and a higher temperature. The reaction conversion rate is greater than 97%. Then under the normal pressure and higher temperature, the third cascade reactor is used for prepolymerization, the degree of polycondensation is greater than 20. After the fourth DISCAGE refiner, the intrinsic viscosity (iV) of the final polycondensate is increased to 0.9 . Energy consumption: electricity 55.0 kwh/t, fuel oil 61.0kg/t, nitrogen 0.8m3/t, air 9.0m3/t. More than 50 sets of equipment have been built using this process, of which 13 production lines have a capacity of 100-700 tons/day. Now there is a single series of 700 tons/day production line put into operation.
In the future, the use of polyester PET will no longer be mainly limited to fibers, but will be further expanded to various types of containers, packaging materials, films, films, engineering plastics, etc. At present, polyester PET is increasingly replacing aluminum and glass , Ceramics, paper, wood, steel and other synthetic materials, the polyester family continues to expand. Therefore, the future prospects of polyester PET products are still optimistic.