Composite fiber, method for producing polyurethane elastomer fabric, and polyurethane elastomer fabric

Abstract

Provided is a composite fiber capable of forming a fabric giving a good wearing feeling to a human body. This composite fiber is composed of a polyurethane elastomer having a glass transition temperature of 15 to 50° C. as a component A, and a readily soluble thermoplastic polymer as a component B. In a cross section of the fiber, the component A constitutes a core, and the component B covers 70% or longer of the circumference of the component A. The component B may be, for example, a readily soluble polyester or thermoplastic polyvinyl alcohol-based polymer. The composite ratio (mass ratio) of the component A to the component B may be 90:10 to 40:60.

What is claimed is: 
     
         1 . A composite fiber comprising:
 a polyurethane elastomer having a glass transition temperature of 15 to 50° C. as a component A, the component A constituting a core in a cross section of the fiber, and   a readily soluble thermoplastic polymer as a component B, the component B covering 70% or longer of the circumference of the component A in the cross section.   
     
     
         2 . The composite fiber according to  claim 1 , wherein the component B comprises at least one selected from the group consisting of a readily soluble polyester and a thermoplastic polyvinyl alcohol-based polymer. 
     
     
         3 . The composite fiber according to  claim 1 , which has a single fiber fineness of 0.3 to 50 dtex. 
     
     
         4 . The composite fiber according to  claim 1 , wherein the composite ratio (mass ratio) of the component A to the component B is 90:10 to 40:60. 
     
     
         5 . The composite fiber according to  claim 1 , which has a core-sheath structure in which the component A is a core component and the component B is a sheath component. 
     
     
         6 . A method for producing a polyurethane elastomer fabric, comprising:
 preparing a composite fiber as claimed in  claim 1 ;   producing a fabric comprising the composite fiber by using the composite fiber; and   removing the component B from the fabric to produce a polyurethane elastomer fabric comprising a polyurethane elastomer monocomponent fiber.   
     
     
         7 . A polyurethane elastomer fabric produced by a method as claimed in  claim 6  comprising a polyurethane elastomer monocomponent fiber. 
     
     
         8 . The polyurethane elastomer fabric according to  claim 7 , wherein the fabric comprises a polyurethane elastomer monocomponent fiber having a single fiber fineness of 0.3 to 50 dtex. 
     
     
         9 . The polyurethane elastomer fabric according to  claim 7 , wherein the fabric has a peak value of mechanical dynamic loss tangent (tan θ) of 0.2 to 1.0. 
     
     
         10 . The polyurethane elastomer fabric according to  claim 7 , wherein the fabric comprises a polyurethane elastomer monocomponent fiber in a continuous fiber form. 
     
     
         11 . The polyurethane elastomer fabric according to  claim 7 , wherein the fabric is a woven or knitted fabric.