Polyester staple fiber and nonwoven fabric comprising same

Abstract

Polyester staple fibers containing a polymeric blend of 0.5 to 15 mass % of a polyolefinic polymer with a matrix polyester polymer, 50% or more of the surface area of each fiber being formed by the polymeric blend, are useful for forming a nonwoven fabric with soft hand and a uniform texture by using various web-forming methods, for example, an air laid, wet laid or carding method.

1 . A polyester staple fiber comprising; 
 a polymeric blend comprising 0.5 to 15% by mass of a polyolefinic polymer mixed and dispersed in a matrix polyester polymer,    50% or more of the surface area of the fiber being formed by the polymeric blend.    
     
     
         2 . The polyester staple fiber as claimed in  claim 1 , wherein the polyolefinic polymer comprises at least one member selected from polyethylene, polypropylene, ethylene-propylene copolymers and polyethylene copolymers and polypropylene copolymers in which at least one ethylenically unsaturated monomer different from ethylene and propylene is block-copolymerized or graft-copolymerized.  
     
     
         3 . The polyester staple fiber as claimed in  claim 1 , wherein the matirix polyester polymer is selected from polyalkylene terephthalates and polyalkylene terephthalate-isophthalate copolymers.  
     
     
         4 . The polyester staple fiber as claimed in any one of  claims 1  to  3 , having a degree of crystallization of 20% or less or a birefringence of 0.05 or less.  
     
     
         5 . The polyester staple fiber as claimed in any one of  claims 1  to  3 , having a concentric or eccentric core-in-sheath conjugate structure in which the sheath section is formed from the polymeric blend.  
     
     
         6 . The polyester staple fiber as claimed in any one of  claims 1  to  3 , having a fiber length of 2 to 30 mm, and a plane zigzag type or omega type crimps in a number of crimp of 3 to 13 crimps/25 mm and a percentage of crimp of 3 to 15%.  
     
     
         7 . The polyester staple fiber as claimed in any one of  claims 1  to  3 , having a fiber length of 30 to 200 mm, and crimps in a number of crimps of 5 to 30 crimps/25 mm and a percentage of crimps of 3 to 30%.  
     
     
         8 . A nonwoven fabric comprising a plurality of the polyester staple fibers as claimed in any one of claims  1  to 6, and formed by an air laid web-forming method.  
     
     
         9 . The nonwoven fabric as claimed in  claim 8 , having a percentage of non-opened fibers of 5% or less.  
     
     
         10 . A nonwoven fabric comprising a plurality of the polyester staple fibers as claimed in any one of  claims 1  to  5 , and formed by a wet web laid forming method.  
     
     
         11 . A nonwoven fabric comprising a plurality of the polyester staple fibers as claimed in any one of  claims 1  to  5  and  7 , and formed by a carding web-forming method.  
     
     
         12 . The nonwoven fabric as claimed in any one of  claims 8  to  11 , having a bending resistance of 70 mm or less, as determined by the cantilever method.