Patent ID: 7645839

Claim:
A biodegradable mixture obtained by melt mixing polyesters comprising: (A) An aliphatic polyester obtained from aliphatic diacids selected from the group consisting of azelaic acid, sebacic acid, brassylic acid, mixtures thereof and mixtures of said acids with aliphatic dicarboxylic acids and/or aliphatic hydroxyacids containing more than 50 mole % of azelaic acid, sebacic acid and brassylic acid, and from aliphatic diols said polyester having modulus of elasticity lying between 400 and 900 MPa and breaking elongation greater than 200% on blown film of about 25-30 μm, average ponderal molecular weight greater than 55,000 and a melting point from 40 to 95° C.; (B) A polymer of lactic acid chosen among L or D polylactic acid, L,D-polylactic, meso polylactic or lactic acid copolymer with hydroxyacids or lactones thereof containing at least 75% of L-lactic or D-lactic acid having average ponderal molecular weight greater than 70,000 and with modulus of elasticity greater than 1500 MPa; in which the mixture contains plasticizers in quantities less than 5% by weight with respect to the quantity of aliphatic polyester and polymer of the lactic acid the concentration by weight of A with respect to (A+B) is in the range of 30 to 60% and blown films of thickness between 25-30 μm have modulus of elasticity greater than 1400 MPa, permeability to water from 170 to 40 g30 μm/m 2 24 h a transmittance at the entrance port lying between 90 and 95% and in which the sum of the fusion enthalpy ΔH A and ΔH B of the two polyesters in the mixture is greater than the sum of the fusion enthalpies ΔH 1 and ΔH 2 of the polyesters prior to melt mixing.