GB755447A - Process for the production of polyesters from six-membered cyclic esters - Google Patents

Abstract

A six-membered cyclic ester is polymerized in presence of a catalyst which is a metal of the 2nd main or sub-group or the 4th group of the periodic system or an alcoholate, oxide, hydroxide or a weak acid salt of such a metal (e.g. a phosphate, carbonate, acetate or lactate). Specified esters are lactide, glycolide, deltavalerolactone, trimethylene carbonate, ethylene oxalate and trimethyl-l-arabonic acid lactone. Polymerization is effected at 130 DEG -200 DEG C. by a batch or continuous process and may be effected in presence of a solvent, e.g. benzene or toluene, a chain-breaker, e.g. benzoic acid or water. Polymerization may be effected on surfaces to be coated. Pigments, plasticizers, solvents, &c., may be added to the polyesters. In examples (1) and (3) glycolide is polymerized by heating in presence of metallic mercury or lead acetate. Triphenyl phosphite may be added to the resultant polyester and further heating effected. (2), (4), (5), (6) Lactide is polymerized by heating in presence of zinc dust, zinc oxide, lead oxide or zinc carbonate and in Example (5) in presence of benzoic acid, (7) and (8). A mixture of glycolide and lactide is polymerized by heating in presence of lead oxide. (9) Lactide is polymerized by heating in presence of lead oxide and benzene.