Polyester manufacturing method
Polyester is an important variety of synthetic fibers, is the trade name of polyester fiber in China. It is a fiber-forming polymer, polyethylene terephthalate (PET), produced by esterification or ester-exchange and polycondensation reaction of purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG), which is made into a fiber by spinning and post-treatment. Polyester is also known as Terylene, or "Dacron" in the United States. When it appeared on the market in Hong Kong, it was translated into Cantonese as "确实凉" or "的确良", meaning "really cool", a household name. The production process of polyester includes the main processes of polymerization, spinning and post-processing. Polymerization
Polyester polymerization usually adopts two methods: esterification and ester exchange. Esterification method is to esterify terephthalic acid and ethylene glycol under the action of catalyst to produce bis(hydroxy)ethyl terephthalate, and then carry out polycondensation reaction to produce polyethylene glycol terephthalate. Ester exchange method is to carry out ester exchange reaction between dimethyl terephthalate and ethylene glycol under the action of catalyst to generate bis(hydroxy)ethyl terephthalate, and then carry out polycondensation reaction. Both methods yield polymers of polyester.
2. Spinning
The spinning process of polyester is mainly two kinds of melt spinning and solution spinning. Melt spinning is the polyester polymer heated and melted, through the spinneret spray to form the silk strip, and then after cooling, stretching, winding and other processes made of polyester silk. Solution spinning is the polyester polymer dissolved in organic solvents, sprayed through the nozzle to form silk, and then after solidification, stretching, winding and other processes made of polyester yarn. Both methods can get polyester fiber with good quality.
3. Post-processing
The post-processing of polyester mainly includes drafting, heat setting, winding and other processes. Drawing is to improve the strength and elasticity of the fiber by stretching it, and heat shaping is to fix the molecular structure inside the fiber by heating to improve the dimensional stability of the fiber. Winding is to wind the fibers into certain shapes and specifications for subsequent weaving and processing.
In short, the manufacturing method of polyester is a complex process that requires close cooperation and strict control of multiple processes to ensure the quality of the final product. Meanwhile, with the continuous development of science and technology, the manufacturing method of polyester is also being improved and optimized, which improves the production efficiency and quality.
