BIODEGRADABLE POLYMERS, PROCESS FOR PRODUCING THEM AND THEIR USE IN PREPARING BIODEGRADABLE MOULDINGS

摘要

PCT No. PCT/EP96/00457 Sec. 371 Date Aug. 14, 1997 Sec. 102(e) Date Aug. 14, 1997 PCT Filed Mar. 5, 1996 PCT Pub. No. WO96/25446 PCT Pub. Date Aug. 22, 1996Biodegradable polyesters having a molecular weight (Mn) of from 5000 to 50,000 g/mol (measured by gel permeation chromatography), a viscosity number of from 30 to 350 g/ml (measured in 50:50 by weight of o-dichlorobenzene/phenol at a concentration of 0.5% by weight of polyester at 25 DEG C.), and a melting point of from 50 to 170 DEG C., and having both hydroxyl and carboxyl end groups, the molar ratio of carboxyl end groups to hydroxyl end groups being greater than one, which is obtained by reacting a mixture consisting essentially of a1) a mixture consisting essentially of from 45 to 80 mol % of adipic acid or ester-forming derivatives thereof, or mixtures thereof, from 20 to 55 mol % of terephthalic acid or ester-forming derivatives thereof, or mixtures thereof, and from 0 to 5 mol % of a sulfonate compound, where the sum of the individual mole percentages is 100 mol %, and a2) a dihydroxy compound selected from the group consisting of C2-C6-alkanediols and C5-C10-cycloalkanediols, in the presence of from 0.01 to 5 mol %, per mol of component a1), of a compound D having at least three groups capable of ester formation, the molar ratio of a1) to a2) being from 0.4:1 to 1.5:1, polymers and biodegradable thermoplastic molding compositions, processes for their preparation and their use for producing biodegradable moldings, adhesives, foams and blends with starch obtained from the polymers or molding compositions.