PET synthesis process and raw materials used-film supplier

PET often uses the following two synthesis methods: direct esterification of terephthalic acid (PTA) and ethylene glycol (EG) (PTA method) and transesterification of dimethyl terephthalate (DMT) and ethylene glycol Method (DMT method). The direct esterification method is to use PTA and EG to directly esterify the oligomer of terephthalic acid and ethylene glycol (BHET), and then carry out the polycondensation reaction. The transesterification method is to first convert terephthalate into dimethyl terephthalate, and then synthesize polyester through transesterification reaction after refining. Compared with the transesterification method, the direct esterification method has the advantages of short process, low consumption and safer production. The direct esterification method has become the main production process and preferred technical route for polyester since the 1980s. The main raw materials for the synthesis of PET are: terephthalic acid (TPA), dimethyl terephthalate (DMT), and ethylene glycol (EG). The catalysts are mainly metal compounds, such as antimony-based catalysts, germanium-based catalysts, and titanium-based catalysts. Among them, antimony-based catalysts are most widely used due to their high activity, few side reactions, low degree of promotion of the thermal degradation reaction of polyester, low price, and high-quality products. Commonly used antimony catalysts are ethylene glycol antimony, antimony acetate and antimony trioxide. However, the toxicity of antimony compounds will have adverse effects on human health and the environment. In recent years, countries around the world have put forward some new requirements for the use of antimony. . There are three main processing methods for PET film: casting method (APET), blow molding method and plane biaxial stretching method (BOPET). The three methods have their own advantages and disadvantages, and the properties of the films produced are also different. Among them, the planar biaxially oriented polyester film (BOPET) is the most excellent in quality and the most widely used. BOPET production equipment includes DMT in France, Bruckner in Germany, Dornier in Germany, and Mitsubishi Heavy Industries in Japan.