Patent ID: 7662323

Claim:
A process to produce a bicomponent fiber comprising, a thermoplastic polymer sheath and an elastomeric compound core wherein the elastomeric compound core comprises a selectively hydrogenated block copolymer having an S block and an E or E 1 block and having the general formula: S-E-S, (S-E 1 ) n , (S-E 1 ) n S, (S-E 1 ) n X or mixtures thereof, wherein: a. prior to hydrogenation the S block is a polystyrene block; b. prior to hydrogenation the E block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight from 40,000 to 70,000; c. prior to hydrogenation the E 1 block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene, and mixtures thereof, having a molecular weight from 20,000 to 35,000; d. n has a value of 2 to 6 and X is the residue of a coupling agent; e. the styrene content of the block copolymer is from 13 to 25 weight percent; f. the vinyl content of the polydiene block prior to hydrogenation is from 70 to 85 mol percent; g. the block copolymer includes less than 15 weight percent of units having the general formula: S-E or S-E 1 wherein S, E and E 1 are as already defined; h. subsequent to hydrogenation about 0 to 10% of the styrene double bonds have been hydrogenated and at least 80% of the conjugated diene double bonds have been hydrogenated; i. the molecular weight of each of the S blocks is from 5,000 to 7,000; and j. the melt index of the block copolymer is greater than or equal to 12 grams/10 minutes according to ASTM D1238 at 230° C. and 2.16 kg weight, whereby the process comprises coextrusion of a thermoplastic polymer and an elastomeric compound wherein the thermoplastic polymer and the elastomeric compound are forced using separate melt pumps to extrude through a die to form one or more fibers having a sheath primarily consisting of the thermoplastic polymer and a core primarily consisting of the elastomeric compound at a rate of at least 500 meters per minute such that the bicomponent fiber has a denier per filament from 0.1 to 30 grams per 9000 meters.