Composite fiber, multifilament, and fiber product

Abstract

The present invention relates to a conjugated fiber including two kinds of polyesters having a molecular weight difference of 5,000 or more in a fiber cross section, in which a high-molecular weight component is completely covered with a low-molecular weight component, and the high-molecular weight component has an orientation parameter of 1.5 to 3.0 and a crystallinity of 0% to 40%.

1 . A conjugated fiber comprising two kinds of polyesters having a molecular weight difference of 5,000 or more in a fiber cross section, wherein a high-molecular weight component is completely covered with a low-molecular weight component, and the high-molecular weight component has an orientation parameter of 1.5 to 3.0 and a crystallinity of 0% to 40%. 
     
     
         2 . The conjugated fiber according to  claim 1 , wherein the high-molecular weight component is polyethylene terephthalate containing a third component having a copolymerization rate of less than 5 mol %. 
     
     
         3 . A multifilament comprising a conjugated fiber, wherein the conjugated fiber comprises two kinds of polyesters having a molecular weight difference of 5,000 or more in a fiber cross section, and in the conjugated fiber, a high-molecular weight component is completely covered with a low-molecular weight component, and the high-molecular weight component has an orientation parameter of 5.0 to 15.0 and a crystallinity of 20% to 50%. 
     
     
         4 . The multifilament according to  claim 3  comprising a conjugated fiber that has a ratio S min /D, which is a ratio of a minimum thickness S min  of a thin portion in the low-molecular weight component to a fiber diameter D, of 0.01 to 0.1, and has a ratio, which is a ratio of the thin portion in the low-molecular weight component to a perimeter of entire fiber, of 30% or more, in the fiber cross section. 
     
     
         5 . The multifilament according to  claim 3 , having a crimp expression rate of 10% or more. 
     
     
         6 . The multifilament according to  claim 3 , having an elastic modulus of 30 cN/dtex or more. 
     
     
         7 . A fiber product partially comprising the multifilament according to  claim 3 .