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US5057260A Spinning of segmented polyurethane-urea elastomers in a steam atmosphere 失效
在蒸汽大气中纺丝分离的聚氨酯 - 尿素弹性体

Spinning of segmented polyurethane-urea elastomers in a steam atmosphere
摘要:
An improved dry spinning process for the production of polyurethane elastomer threads using superheated steam as the spinning medium, comprising(1) spinning polyurethane-urea elastomers prepared by chain lengthening of NCO prepolymers with diamine from a solution containing dimethylformamide or dimethylacetamide via a hot spinneret having a nozzle at not less than 100.degree. C. and at a spinning solution temperature in the nozzle of not less than 100.degree. C. into a heated spinning chimney at a chimney wall temperature of not less than 160.degree. C., while(2) introducing superheated steam into the spinning chimney at a temperature above 250.degree. C. as the spinning medium in an amount of at least 20 kg/h, if the chimney diameter is less than or equal to 28 cm, or if the chimney diameter is greater than 28 cm, in an amount of at least 20 kg/h increased by up to a factor H, wherein factor H is equal to the chimney cross-section/615 cm.sup.2,(3) feeding the spinning medium and spinning solvent to a recovery step at the end of the spinning chimney, and(4) maintaining a take-off speed of the threads from the chimney of at least 250 m/min. The improved process yields improved thread properties in the resulting filament yarns.
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