Thermal-adhesive bicomponent fiber and method for producing it

Abstract

An essential object of the invention is to provide a low-modulus, self-extensible thermal-adhesive bicomponent fiber including polyethylene terephthalate as the fiber-forming resin component thereof and capable of producing a nonwoven fabric or a fiber structure that has a high adhesive strength and is bulky and well drapable. The object of the invention is attained by a self-extensible thermal-adhesive bicomponent fiber that includes a fiber-forming resin component and a thermal-adhesive resin component and is characterized in that the fiber-forming resin component includes polyethylene terephthalate, that the thermal-adhesive resin component includes a crystalline thermoplastic resin having a melting point lower by at least 20° C. than that of the fiber-forming resin component, and that its breaking elongation is from 130 to 600%, its 100% elongation tensile strength is from 0.3 to 1.0 cN/dtex and its 120° C. dry heat shrinkage is smaller than −1.0%; and by a method for producing it.

1 . A self-extensible thermal-adhesive bicomponent fiber comprising a fiber-forming resin component and a thermal-adhesive resin component, which is characterized in that the fiber-forming resin component comprises polyethylene terephthalate, that the thermal-adhesive resin component comprises a crystalline thermoplastic resin having a melting point lower by at least 20° C. than that of the fiber-forming resin component, and that its breaking elongation is from 130 to 600%, its 100% elongation tensile strength is from 0.3 to 1.0 cN/dtex and its 120° C. dry heat shrinkage is smaller than −1.0%. 
   
   
       2 . The thermal-adhesive bicomponent fiber as claimed in  claim 1 , which is a core/sheath bicomponent fiber and in which the fiber-forming resin component constitutes the core component and the thermal-adhesive resin component constitutes the sheath component thereof. 
   
   
       3 . The thermal-adhesive bicomponent fiber as claimed in  claim 1 , wherein the thermal-adhesive resin component is a polyolefin resin. 
   
   
       4 . The thermal-adhesive bicomponent fiber as claimed in  claim 1 , wherein the thermal-adhesive resin component is a crystalline copolyester. 
   
   
       5 . A method for producing a thermal-adhesive bicomponent fiber of  claim 1 , which comprises cold-drawing an undrawn yarn taken out at a spinning speed of not higher than 1300 m/min, by from 1.05 to 1.30 times, and then relaxing and thermally shrinking it at a temperature higher by at least 10° C. than both the glass transition point of the thermal-adhesive resin component and the glass transition point of the fiber-forming resin component. 
   
   
       6 . The method for producing a thermal-adhesive bicomponent fiber as claimed in  claim 5 , wherein the relaxing and thermal shrinking treatment is effected in hot air. 
   
   
       7 . The method for producing a thermal-adhesive bicomponent fiber as claimed in  claim 5 , wherein the relaxing and thermal shrinking treatment is effected in hot water. 
   
   
       8 . A thermal-adhesive nonwoven fabric comprising only self-extensible thermal-adhesive bicomponent fibers of  claim 1  and having a cantilever value of at most 10 cm. 
   
   
       9 . A thermal-adhesive nonwoven fabric comprising only self-extensible thermal-adhesive bicomponent fibers of  claim 2  and having a cantilever value of at most 10 cm. 
   
   
       10 . A thermal-adhesive nonwoven fabric comprising only self-extensible thermal-adhesive bicomponent fibers of  claim 3  and having a cantilever value of at most 10 cm. 
   
   
       11 . A thermal-adhesive nonwoven fabric comprising only self-extensible thermal-adhesive bicomponent fibers of  claim 4  and having a cantilever value of at most 10 cm.