Patent ID: 7153569

Claim:
An aliphatic-aromatic copolyester film comprising a biodegradable stretched film comprising nonporous filler particles and a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of less than about 0° C. a weight average molecular weight of from about 90,000 to about 160,000 Daltons, wherein the nonporous filler particles comprise from about 30% (by weight of film and filler) to about 80% (by weight film and filler) of the copolyester film, and wherein the film has a water vapor transmission rate of greater than about 2500 g/m 2 /day, a modulus of elasticity in the machine direction of less than about 300 MPa, and an elongation at break in the machine direction of greater than about 70%.