Patent ID: 8623950

Claim:
A method of preparing polyurethaneurea elastic fiber having heat-resistance and chlorine-resistance comprising the steps of: (a) preparing a first polyurethane polymer by mixing polyol and isocyanate compound in the absence of mono-alcohol; (b) preparing a second polymer by adding a chain extender, a chain terminator, and a cross-linking agent to the first polymer of step (a), and at this time, using ethylenediamine alone as a chain extender; (c) preparing a spinning dope by adding a surface modified basic magnesium carbonate as an anti-chlorine additive to the second polymer of step (b); and (d) preparing the elastic fiber by spinning the spinning dope of step (c), wherein the first polymer of step (a) is prepared by mixing the polyol and isocyanate compound continuously loaded in a count current static mixer, wherein the polyurethaneurea elastic fiber has fracture strength (g/d) of 1.0-1.5, elongation break of 450-700%, elasticity recovering rate at 180° C. dry heat of 40-50%, and color of yarn (b) of 1.0-3.2, and wherein a strength of the fiber after treatment with 180° C. hot air for 1 minute as 100% extended is 82-99% of a strength of a non-treated fiber and a strength of the fiber after 24 hours and 48 hours of soaking in a bath containing 20 ppm of chlorine and having a pH of 7 at an extension of 50% is, respectively, 85-98% and 82-95% of a strength of a non-treated fiber.