Extensible nonwoven fabric

Abstract

Extensible nonwoven fabrics having improved elongation, extensibility, abrasion resistance and toughness. In particular, embodiments of the invention are directed to extensible spunbond fabrics comprising a polymeric blend of a metallocene catalyzed polypropylene, polyethylene, and a third polymer component.

That which is claimed: 
     
         1 . A nonwoven fabric comprising a plurality of fibers that are bonded together to form a coherent web, the fibers comprising a polymeric blend of a metallocene catalyzed polypropylene component, a polyethylene component, and a third polymer component that is at least partially miscible in the metallocene catalyzed polypropylene component and polyethylene component, wherein the nonwoven fabric exhibits a 15 to 45% increase in toughness in comparison to a similar nonwoven fabric comprising a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
         2 . The fabric of  claim 1 , wherein the third polymer component comprises a polypropylene copolymer or terpolymer. 
     
     
         3 . The fabric of  claim 1 , wherein the plurality of fibers are point bonded to each other with a bonding pattern having a cross-direction rod shape. 
     
     
         4 . The fabric of  claim 1 , wherein the bonds cover 8 to 25% of a surface are of the nonwoven fabric. 
     
     
         5 . The fabric of  claim 1 , wherein the nonwoven fabric has been subject to a solid state deformation such that the fibers have become permanently elongated. 
     
     
         6 . The fabric of  claim 1 , wherein the fibers are multicomponent fibers having a sheath/core arrangement in which the sheath comprises polyethyelene and the core comprises said polymeric blend. 
     
     
         7 . The fabric of  claim 1 , wherein the fibers are monocomponent fibers. 
     
     
         8 . The fabric of  claim 1 , wherein the blend comprises greater than 50 percent by weight of the polypropylene component, 1 to 10 percent of the polyethylene component and 10 to 40 percent of the third polymer component. 
     
     
         9 . An absorbent article comprising the fabric of  claim 1 . 
     
     
         10 . A nonwoven fabric comprising a plurality of fibers that are bonded together to form a coherent web, wherein the fibers comprise a polymeric blend of a metallocene catalyzed polypropylene component, a polyethylene component, and a third polymer component that is at least partially miscible in the metallocene catalyzed polypropylene component and polyethylene component, wherein the third polymer component comprises a polypropylene copolymer or terpolymer, the fibers comprise greater than 50 percent by weight of the polypropylene component, 1 to 10 percent of the polyethylene component and 10 to 40 percent of the third polymer component, and wherein the fabric exhibits an increase in toughness in comparison to a similar nonwoven fabric comprising a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
         11 . The nonwoven fabric of  claim 10 , wherein the fibers have been calendered bonded with rod shapes patterns that extend in the cross direction (CD) of the web, wherein the CD rod patterns have a length that is about 1.5 to 10× the width and the CD rod patterns are present in an amount ranging from about 8 to 15% based on the surface area of the nonwoven web. 
     
     
         12 . The fabric of  claim 10 , wherein the nonwoven fabric has been subject to a solid state deformation such that the fibers have become permanently elongated. 
     
     
         13 . The fabric of  claim 10 , wherein the fibers are multicomponent fibers having a sheath/core arrangement in which the sheath comprises the polymeric blend and the core comprises polyethylene. 
     
     
         14 . The fabric of  claim 10 , wherein the fibers are monocomponent fibers. 
     
     
         15 . The fabric of  claim 10 , wherein the fibers have a reverse bicomponent arrangement and in which the polymer blend is present in a sheath of the fiber, and a polymer having a lower melting temperature than said polymer blend defines a core of the fiber. 
     
     
         16 . A composite sheet material having an SMS or SMMS construction in which the spunbond layer comprises the nonwoven fabric of  claim 10 . 
     
     
         17 . An absorbent article comprising the fabric of  claim 10 . 
     
     
         18 . The absorbent article of  claim 17 , wherein the article comprises a diaper. 
     
     
         19 . A method of preparing a nonwoven fabric comprising the steps of:
 extruding a polymeric material through a plurality of orifices to form fibers, the polymeric material comprising a polymeric blend of a metallocene catalyzed polypropylene component, a polyethylene component, and a third polymer component that is at least partially miscible in the metallocene catalyzed polypropylene component and polyethylene component;   collecting the fibers on a collection surface to form a web of fibers;   passing the web of fibers through a calendering roll to thermally bond the fibers to each other, wherein the nonwoven fabric has wherein the nonwoven fabric exhibits a 15 to 45% increase in toughness in comparison to a similar nonwoven fabric comprising a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene.   
     
     
         20 . The method of  claim 19 , wherein the calendering roll comprises a roll having a plurality of 3-dimensional geometric rod or cylindrical shaped bond patterns extending in a cross-direction of said roll. 
     
     
         20 . The method of  claim 19 , wherein the bonds cover from 8 to 25% of the fabric. 
     
     
         21 . The method of  claim 20 , wherein the bond patterns cross-directional cylindrical or rod shaped bond patterns have a length that is from about 1.5 to 10 times the width. 
     
     
         22 . The method of  claim 19 , wherein the fabric comprises a spunbond fabric.