PURPOSE: To obtain a resin little in mold staining during molding by liq. phase polycondensation of polycondensate obtd. in the step of esterification in the presence of a catalyst solubilized with a specific amt. of an alkali and treatment of the final polycondensate with water in production of polyethylene terephthalate.
CONSTITUTION: A process for producing polyethylene terephthalate(PET) comprises step I of esterification of terephthalic acid (deriv.) with ethylene glycol (deriv.), step II of liq. phase polycondensation of the resulting ester by heating and melting it in the presence of a polycondensation catalyst comprising 1mol catalyst solubilized with at most 0.4mol alkaline solubilizer, step III of solid phase polycondensation of the resulting polycondensate, and step IV of contact of the final polycondensate with water to deactivate the catalyst. The solubilizer to be used in step II is tetraethylammonium hydroxide or the like, the amt. of which is pref. at most 0.2mol per mol of the polycondensation catalyst for solubilization. According to the process, oligomer formation can be reduced to such an extent as to satisfy the relationship: W1-W0≤0.1 (wherein W0 is the oligomer content (wt.%) of PET, and W1 is an oligomer content (wt.%) after molding of it into a stepped square plate through heating and melting at 290°C.
| WO/2018/074869 | METHOD FOR PRODUCING POLYBUTYLENE TEREPHTHALATE |
| JPH03200832 | POLYESTER PACKAGING MATERIAL |
| JP2000053802 | PROCESS FOR RECYCLING PET BOTTLE |
TANAKA YASUHIRO
MIURA KIMIYOSHI
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