Patent ID: 7101622

Claim:
An extensible fiber comprising a propylene copolymer, the copolymer comprising at least about 50 weight percent of units derived from propylene and at least about 5 weight percent of units derived from a comonomer other than propylene, the fiber characterized as having a crystallinity index less than 30%, a modulus of less than or equal to about 22 g/den, wherein said extensible fiber can be characterized by having a retained load of more than or equal to about 2.5% and an immediate set of less than or equal to about 22% as determined in a 50% 1-cycle test, said 50% 1-cycle test being one in which a load on the fiber is measured while the fiber is extended at a rate of 10 inches per minute to an elongation of 50% then retracted to an elongation of 0% at a rate of 10 inches per minute, and then extended a second time to an elongation of 50% at a rate of 10 inches per minute, and wherein the retained load is the load measured at 30% elongation during retraction divided by the load measured at 30% elongation during the first extension, and wherein the immediate set is the elongation at which a positive load is first measured during the second extension.