Polyurethane elastomers, method of producing them and their use

Elastomeric fibers prepared by

• 1) melt spinning a polyurethane elastomer comprising structural units of:
• wherein the grouping —O —R1 —O— is a macrodiol group having a molecular weight of 500 to 10000, X is an olefinically unsaturated moiety, Y is NH and each Y is on each side of X, R2 is a member selected from the group consisting of bivalaent aliphatics, cycloalipbatics, aliphatic-cycloaliphatic groups and mixture thereof,
• n is an integer from 1 to 10,
• m is an integer of at least 4,
• said olefinically unsaturated moiety X being derived from a diaminoalkene, diaminoalkyne, diaminocycloalkene or a mixture thereof,
• wherein the diaminoalkene is cis- or trans-1,4-diaminobut-2-ene, cis- or trans-4,4′-diaminostilbene, a diamino maleic acid dinitrile or a mixture thereof, the diaminoalkyne is 1,4-diaminobut-2-yne and the diaminocycloalkene is 3,6-diaminocyclohexene-(1),
• whereby fibers are obtained;
• and
• 2) exposing said fibers to high-energy radiation in order to cross-link the polyurethane elastomer at least partially.