Patent ID: 6637181
Filing Date: 2003-10-28
Classification: C08G,D01F,Y10T

Abstract:
Process for producing elastane yarn by reaction of:(A) macrodiol mixtures comprising at least a linear polyester-, polyether- and/or polycarbonate-diols having a molecular weight of 1000-8000 g/mol (number average), and at least one hydroxyalkyl-terminated polysiloxane compound with (B) isocyanate mixtures of diisocyanates and smaller fractions of aliphatically structured polyisocyanates having an average NCO functionality of greater than 2, and (C) hydroxyalkyl-substituted diols having a molecular weight (number average) of up to 400 g/mol as chain extenders, alone or mixed, and optionally combined with low molecular weight polysiloxanes mentioned under (A) and optionally in the presence of(D) catalysts, stabilizers and further auxiliary and operational substances, spinning the resulting polyurethanes from the melt, spin finishing, drawing, relaxing then thermally aftertreating the yarn obtained, wherein the polyurethane synthesis is carried out using in the macrodiol mixture (A) at least one hydroxyalkyl-terminated polysiloxane compound having an OH functionality &lE;2 and a molecular weight of 300-6000 g/mol (number average) and the components of the macrodiol mixture (A) in such a mixing ratio that the number of the OH equivalents of the polysiloxane compounds relates to the number of the OH equivalents of the other macrodiols as 0.2:99.8 to 30:70, and wherein the components of the isocyanate mixture (B) are used in such amounts that the ratio of the isocyanate equivalents of the difunctional components to the higher functional components is within the range from 99.5:0.5 to 80:20, the reaction of the components (A), (B) and (C) is carried out continuously according to a one-step process or in two steps by the prepolymerization process with continuous chain extension reaction, the proportion of the components (B)+(C) in the elastic yarn, based on the sum total of the components (A)+(B)+(C), being 5-30% by weight, and wherein the resulting reaction melt is spun directly, optionally in the presence of stabilizers and lubricants or other auxiliaries (D).