Production of poly ethylene with a high molecular weight of forwarding the phthalates

摘要

1486409 Preparing polyethylene terephthalate using scrap material AGFA-GEVAERT 25 Oct 1974 [6 Nov 1973] 51381/73 Heading C3R A process for preparing polyethylene terephthalate comprises heating at 240‹ to 310‹ C. in an inert atmosphere a reaction mixture comprising terephthalic acid and bis(2-hydroxyethyl)terephthalate in a molar ratio of from 1 : 1 to 1À1 : 1, and ethylene glycol in a molar ratio of from 0À3 : 1 to 0À9 : 1 with respect to the terephthalic acid, the terephthalic acid and the ethylene glycol being in the free state and/or bound in the form of polyethylene terephthalate scrap, to produce a pre-condensate; a first part of the precondensate is polycondensed at elevated temperature and subatmospheric pressure to form polyethylene terephthalate, and a second part is mixed, as such or after glycolization with ethylene glycol to bis(2-hydroxyethyl)terephthalate, with polyethylene terephthalate scrap or with such scrap and with fresh terephthalic acid and/or ethylene glycol such that the above molar ratios are achieved and the process is repeated in a continuous or batch manner. The polyethylene terephthalate scrap is preferably film scrap in the form of particles having a mean dimension of about 10 mm.