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Technical Manual: Polyester (PET) production technology development 0 replies,1514 views

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Polyester (PET) either by dimethyl terephthalate (DMT) and ethylene glycol (EG) prepared by the reaction, but also by terephthalic acid (PTA) with ethylene glycol reaction. Currently, the world line of PET production technology used is mainly the two, known as DMT method (also known as transesterification) and the PTA method (direct esterification). DMT method is the use of dimethyl terephthalate (DMT) and ethylene glycol (EG) for transesterification, and polycondensation as PET. PTA method using high purity terephthalic acid (PTA), or the purity of terephthalic acid (MTA) and ethylene glycol (EG) direct esterification, condensation into the polyester. The direct esterification is from 1965 Amoco refining of crude terephthalic acid developed after the success since then has developed rapidly, PET production also will be improved very rapidly. Law of the PTA merits more than the DMT method (low consumption of raw materials, EG recovery system less, not by-product of methanol, the production of safer, short process, low investment projects, utility consumption and lower production costs, speed of flat production stable control), etc., the world's total production capacity of PET used in most of the PTA method. In the early 20th century, 60, PET-based production of the batch process. 60 years later, Western Europe, Japan after the United States, but also successfully developed a continuous production technology, the process is relatively continuous batch process technology is superior, production, quality, and can direct spinning, product cost low, so get rapidly. PET production has become mainstream. Built 70 years after the PET devices have adopted large-scale continuous process. 80 years after entry, the new PET device that is mainly continuous PTA method. In addition, with silk and PET bottles for industrial development, there was thickening PET SSP technology, and its technology is also intermittent and continuous methods of the points. There are many PET resin production technology patents, both the esterification and polycondensation process (melt phase) or the production of high viscosity bottle together with the solid resin are many different processes. Melt polymerization method in which the main technical holding company Zimmer company, Teijin, Kanebo Corporation, Ems-Inventa Corporation, JohnBrownDeutsche, DuPont, and Sunkyong companies; solid-phase polycondensation of the main technical holding company Zimmer Company, Bepex company, Hosokawa company, Karl Fischer Company, Sinco company, Buehler companies and Sunkyong companies. (L) PTA direct esterification process. If the use of PTA as raw material, PET polyester polymer production mainly in the following two reactions: The first step is esterification of PTA and EG to produce ethylene terephthalate (BHET); second step is the catalyst BHET condensation reaction under the action of PET. Esterification reaction stage, in order to shorten the reaction time, the esterification reaction pressure is higher than atmospheric pressure, reaction temperature is higher than the boiling point of alcohol. Specific reactions with alcohol used in the molar ratio of 1.1:1-2:1 TPA, the reaction temperature used in 258-263 ? Polycondensation reaction temperature to be higher than the melting temperature of the polymer (260-265 ?, lower than 300 ?(when the temperature reaches this value, the polymer began to degrade), the condensation reaction is the most suitable temperature range 275 - 290 ? Polycondensation reaction time of at least 2 hours, depending on the reactor vary. The smaller reaction constant, so the reaction process must be removed as soon as possible reaction of ethylene glycol generated to break the equilibrium, to promote reaction to the right, otherwise it will not only affect the reaction rate, and the degree of polymerization is not mentioned high. Therefore, polycondensation requires under vacuum, in particular, the late request polycondensation under high vacuum, but should try to increase the evaporation surface. Some for the esterification reaction or transesterification catalyst can also be used for condensation reactions. Among the many catalysts, antimony trioxide and antimony acetate is the most common species, which are high temperature in the condensation reaction effectively (275-290 ?, is not subject to phosphite stabilizer of class. These catalysts can be together with the esterification catalyst are added in the initial reaction can also be added after the esterification reactor. (2) Evans of - Fischer Polyester reactor technology. Evans of EMS - Fischer (Inventa-Fisher) has developed an innovative polyester reactor technology can reduce the production of polyester raw material consumption and improve yield. ESPRE tower, called into the reactor can reduce the cost of 26%, 22% sales revenue increase and improve the quality of polyester. The reactor can be flexibly used for PET, PTT, PEN and PBT and its copolyester. In the new process, the esterification and condensation at the same time reducing the pressure and temperature conditions conducive to reaction. With completion of the reaction gas or inert gas mixed with each other to avoid mechanical mixing, the reaction system automatically. Use of the new response of the reactor system, which can avoid dead-products and reaction, and can optimize the molecular weight distribution of the target. Currently, this new technology in addition has a set of 1 ton / day of medium-sized installations, there are three sets of a new polyester plant reactor technology, Germany, 240 tons / day plant is under construction, the Netherlands 180 tons / day plant at the base engineering phase, China Taiwan 120 tons / day unit has decided to use this reactor. (3) polyester polymerization catalyst. Currently most of the world still using PET polyester production plant type antimony catalyst, about 90% antimony catalyst, there are other germanium and titanium catalysts, although the catalytic effect of antimony catalysts well, but with the awareness the improvement of the toxicity of antimony become more and more attention problems. Therefore, PET non-antimony catalysts in recent years is very active. DuPont, Toyobo, Teijin, Zimmer, Acordis, Synetix and other companies have introduced environmentally friendly heavy metal antimony-free catalyst. PET non-antimony catalyst development have the following profile: ACORDIS the company's C-94 catalyst, Zimmer Company Ecoca
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