Foamed synthetic fiber and its manufacturing method.

摘要

57 Disclosed is a foamed synthetic fiber characterized in that an organic solvent solution of a thermoplastic polymer admixed with 3-100 weight percent of a compound scarcely soluble or insoluble in the aqueous coagulating bath for wet spinning, which is liquid under normal pressure and has a boiling point of 120°C or less, as foaming agent is injected as spinning dope into said aqueous coagulating bath and it is foamed in a drying atmosphere at the boiling point or more of the foaming agent and 100°C or more and has an expansion ratio of 3 percent or more, and the manufacturing method thereof. The foamed synthetic fiber of the present invention is light and bulky, being excellent in warmth-keeping and heat-insulating performance with its appearance, touch and development of color similar to those of an animal hair.