GB1191499A - Production of Aromatic Polyesters - Google Patents

Abstract

1,191,499. Aromatic polyesters. IMPERIAL CHEMICAL INDUSTRIES Ltd. 9 Sept., 1968 [29 Sept., 1967 (2)], Nos. 44478/67 and 44479/67. Heading C3R. Normally grey polyesters made by the polycondensation of a bis-ethylene glycol ester of an aromatic dicarboxylic acid, with a trivalent antimony catalyst (e.g. antimony oxide), are made white by carrying out the polycondensation in the presence of a diol of formula where R 1 , R 2 and R 3 are H or monovalent hydrocarbon groups, or R 1 and R 2 together form a divalent hydrocarbon group containing up to 3 carbon atoms, of formula -(CH 2 ) n - joining the carbon atoms carrying the -OH groups, and n = 1 or 2. The diol may be added at the commencement or during the reaction leading to the formation of the bis-ester, or at the beginning of or during the polycondensation reaction, and is used in an amount which is 0À01 to 15 mole per cent (based on the bis-ethylene glycol ester. Diols specified are: propane-1,2- diol, butane-2,3-diol, propane-1,3-diol, butane- 1,3-diol, cyclohexane-1,3-diol, octane-1,2-diol, pentane-2,3-diol, 2-n-hexylpropane-1,3-diol, 1- benzylethylene glycol, 4-methyl pentane-1,2- diol, 3-methylbutane-1,2-diol and hexane-1,2- diol. The colour is further improved if phosphorus-containing stabilizers are present during the polycondensation. Examples describe the manufacture of polyethyleneterephthalate from dimethylterephthalate, ethylene glycol and one of the above diols.