Patent ID: 7312295

Claim:
A copolymer comprising units derived from ethylene and 1-heptene wherein the peak force at break per millimeter of film thickness P of a blown film made of the copolymer satisfies the following relationship: P> 1.9 C− 127 (1) wherein P is expressed in N/mm and determined on a 50 micrometer thick blown film according to ASTM-D5748-95; and C is given by the relationship C=D(1−CFW), wherein D is the density of the copolymer measured in kg/m 3 according to ASTM-D-792 and CFW is the weight fraction of the copolymer having a crystallization point of 75° C. or higher as determined using crystallization analysis fractionation, and C is greater than or equal to 550.