Fiber material and method for manufacturing the same

Abstract

A fiber material contains an assembly of a plurality of nanofiber coated polymer fibers in which a polymer fiber serving as a core fiber is coated with polymer nanofibers, in which the polymer fibers and the polymer nanofibers are fusion-bonded and two or more of the polymer fibers are fusion-bonded to each other in at least one portion.

What is claimed is: 
     
         1 . A process for producing a fiber material, the fiber material, comprising:
 an assembly of a plurality of nanofiber coated polymer fibers in which a polymer fiber serving as a core fiber is coated with polymer nanofibers,   
       the polymer fiber and the polymer nanofibers being bonded such that an adhesion boundary portion between the polymer fiber and the polymer nanofibers has a sheet shape or is lost,
 two or more of the polymer fibers being bonded to each other in at least one portion such that an adhesion boundary portion between the two or more of the polymer fibers has a sheet shape or is lost, and 
 an average diameter of the polymer fiber being 10 μm to 50 μm, and an average diameter of the polymer nanofibers being 1 nm or more and less than 1 μm, 
 
       the process comprising the steps of:
 (i) extruding polymer solution or melted polymer from spinning orifices simultaneously towards a collector, 
 (ii) forming the electro-spun polymer fiber and electro-spun polymer nanofibers, 
 (iii) coating the electro-spun polymer fiber with the electro-spun polymer nanofibers to form an electro-spun polymer fiber coated with the electro-spun polymer nanofibers, and 
 (iv) heating the electro-spun polymer fiber coated with the electro-spun polymer nanofibers, and bonding the electro-spun polymer fiber and the electro-spun polymer nanofibers each other so that an adhesion boundary portion between the electro-spun polymer fiber and the electro-spun polymer nanofibers has a sheet shape or is lost. 
 
     
     
         2 . The process according to  claim 1 , wherein an amount of the electro-spun polymer nanofibers of the electro-spun polymer fiber coated with the electro-spun polymer nanofibers, is 5 parts by weight or more and 90 parts by weight or less. 
     
     
         3 . The process according to  claim 1 , wherein temperature of the heating in the step (iv) is equal to or higher than the melting point of the polymer material forming the electro-spun polymer fiber, and is equal to or less than the glass transition point of the polymer material forming the electro-spun polymer nanofibers.