GB1430012A - Process for preparing polyesters - Google Patents

Abstract

1430012 Enhancing the polymerization rate of polyesters KURARAY CO Ltd 5 April 1973 [14 April 1972] 16359/73 Heading C3R A process for the preparation of a polyester containing at least 80 mole per cent of ethylene terephthalate units comprises polycondensing ethylene glycol with terephthalic acid or an ester thereof, or polycondensing an intermediate reaction product thereof by ester interchange, the polycondensation being carried out in the presence of from 0À1 to 30% by weight, based on the resulting polyesters, of at least one organic compound which (a) is non-reactive with ester groups or ester-forming groups under the conditions of the polycondensation, (b) contains neither nitrogen nor phosphorus, (c) contains at least one aromatic nucleus, carbonyl group, ether group or halogen atom, (d) has a total number of carbon atoms or carbon atoms plus halogen atoms of from 5 to 25, and (c) has a boiling point in the range of from 80‹ C. at 760 mm. Hg to 230‹ C. at 10 mm. Hg; in which the organic compound is added to the reaction medium before the intrinsic viscosity reaches 0À30 and, in the case when the starting materials are ethylene glycol and terephthalic acid, not until the degree of esterification has reached at least 90%, and in which at least 90% by weight of the organic compound is removed from the reaction medium before the intrinsic viscosity reaches 0À35 and substantially all of of the organic compound is removed before the intrinsic viscosity reaches 0À45, and the polycondensation is then completed. Examples of the organic compounds are (a) aromatic hydrocarbons, e.g. benzene, (b) aromatic halogen compounds, e.g. chlorobenzene, (c) aromatic ether compounds, e.g. diphenyl ether, (d) aromatic ketones, e.g. acetophenone, (e) other aromatic compounds, e.g. diphenylsulphone (f) aliphatic halogen compounds, e.g. tetrachloroethane (g) aliphatic ethers, e.g. di-n-butyl ether and (h) aliphatic ketones, e.g. diethylketone. The examples describe the preparation of polyethylene terephthalate using the above organic compounds.