Multi-component fibers and non-woven webs made therefrom

Abstract

Bicomponent spunbond filaments and non-woven webs made from the filaments are disclosed. The spunbond filaments include a core polymer and a sheath polymer. Both the core polymer and the sheath polymer are made primarily from polypropylene polymers. For instance, the sheath polymer can be a randomized copolymer of polypropylene and ethylene. The ethylene can be present in the sheath polymer in an amount of less than about 2% by weight. The core polymer, on the other hand, can be a polypropylene polymer having a melting temperature than the sheath polymer.

What is claimed is:  
     
         1 . A non-woven web comprising continuous polymeric filaments, the polymeric filaments comprising multi-component filaments including a sheath polymer and a core polymer, the sheath polymer comprising a copolymer of a polypropylene polymer and a monomer, the core polymer comprising primarily a polypropylene homopolymer polymer, the core polymer having a melting temperature that is at least about 15° F. greater than the melting temperature of the sheath polymer, the continuous polymer filaments being fused together.  
     
     
         2 . A non-woven web as defined in  claim 1 , wherein the sheath polymer comprises a randomized copolymer.  
     
     
         3 . A non-woven web as defined in  claim 2 , wherein the monomer comprises ethylene.  
     
     
         4 . A non-woven web as defined in  claim 2 , wherein the monomer is present in the sheath polymer in an amount of less than about 2% by weight.  
     
     
         5 . A non-woven web as defined in  claim 3 , wherein the monomer is present in the sheath polymer in an amount of less than about 2% by weight.  
     
     
         6 . A non-woven web as defined in  claim 1 , wherein the continuous filaments comprise spunbond filaments.  
     
     
         7 . A non-woven web as defined in  claim 1 , wherein the sheath polymer and the core polymer have a melt flow rating of from about 30 g/10 minutes to about 35 g/10 minutes.  
     
     
         8 . A non-woven web as defined in  claim 1 , wherein the sheath polymer has a melting temperature of from about 110° C. to about 150° C.  
     
     
         9 . A non-woven web as defined in  claim 1 , wherein the core polymer comprises a metallocene catalyzed polypropylene.  
     
     
         10 . A non-woven web as defined in  claim 1 , wherein the core polymer comprises polypropylene in an amount of at least 98% by weight.  
     
     
         11 . A non-woven web as defined in  claim 1 , wherein the sheath polymer comprises a blend of the copolymer of a polypropylene polymer and a monomer and a polypropylene homopolymer, the copolymer of a polypropylene polymer and a monomer comprising a randomized copolymer of polypropylene and ethylene.  
     
     
         12 . A non-woven web comprising polymeric fibers, the polymeric fibers comprising multi-component fibers including a sheath polymer and a core polymer, the sheath polymer comprising a random copolymer of a polypropylene polymer and ethylene, the ethylene being present in the sheath polymer in an amount of less than about 2% by weight, the core polymer comprising a polypropylene polymer, the core polymer having a melting temperature that is at least about 15° F. greater than the melting temperature of the sheath polymer, the polymeric fibers being fused together.  
     
     
         13 . A non-woven web as defined in  claim 12 , wherein ethylene is present in the sheath polymer in an amount of less than about 1.8% by weight.  
     
     
         14 . A non-woven web as defined in  claim 12 , wherein the multi-component fibers are continuous filaments.  
     
     
         15 . A non-woven web as defined in  claim 12 , wherein the multi-component fibers are spunbond fibers.  
     
     
         16 . A non-woven web as defined in  claim 12 , wherein the sheath polymer and the core polymer have a melt flow rating of from about 30 g/10 minutes to about 35 g/10 minutes.  
     
     
         17 . A non-woven web as defined in  claim 12 , wherein the sheath polymer has a melting temperature of from about 110° C. to about 1500 C.  
     
     
         18 . A non-woven web as defined in  claim 12 , wherein the core polymer comprises a metallocene catalyzed polypropylene.  
     
     
         19 . A non-woven web as defined in  claim 12 , wherein the sheath polymer comprises a blend of the random copolymer and a polypropylene homopolymer.  
     
     
         20 . A non-woven web comprising continuous polymeric filaments, the polymeric filaments having been formed by being extruded through a spinnerette, the polymeric filaments comprising multi-component filaments including a sheath polymer and a core polymer, the sheath polymer comprising a random copolymer of a polypropylene polymer ethylene, the ethylene being present in the sheath polymer in an amount of less than about 2% by weight, the core polymer comprising a polypropylene polymer, the polypropylene being present in the core polymer in an amount of at least 95% by weight, the core polymer having a melting temperature that is at least about 15° F. greater than the melting temperature of the sheath polymer, the core polymer and the sheath polymer having a melt flow rating of at least 30 g/10 minutes, the continuous polymeric filaments being fused together to form the non-woven web.  
     
     
         21 . A non-woven web as defined in  claim 20 , wherein the sheath polymer has a melting temperature of from about 110° C. to about 150° C.  
     
     
         22 . A non-woven web as defined in  claim 20 , wherein the core polymer comprises a metallocene catalyzed polypropylene.  
     
     
         23 . A non-woven web as defined in  claim 20 , wherein the sheath polymer comprises from about 20% by weight to about 70% by weight of the continuous filaments.  
     
     
         24 . A non-woven web as defined in  claim 20 , wherein ethylene is present in the sheath polymer in an amount of less than about 1.8% by weight.  
     
     
         25 . A fiber comprising: 
 a bicomponent spunbond filament including a sheath polymer and a core polymer, the sheath polymer comprising a random copolymer of a polypropylene polymer and ethylene, the ethylene being present in the sheath polymer in an amount of less than about 2% by weight, the core polymer comprising a polypropylene polymer, the core polymer having a melting temperature that is at least about 15° F. greater than the melting temperature of the sheath polymer.    
     
     
         26 . A fiber as defined in  claim 25 , wherein ethylene is present in the sheath polymer in an amount of less than about 1.8% by weight.  
     
     
         27 . A fiber as defined in  claim 25 , wherein the sheath polymer and the core polymer have a melt flow rating of from about 30 g/10 minutes to about 35 g/10 minutes.  
     
     
         28 . A fiber as defined in  claim 25 , wherein the sheath polymer has a melting temperature of from about 110° C. to about 150° C.  
     
     
         29 . A fiber as defined in  claim 25 , wherein the core polymer comprises a metallocene catalyzed polypropylene.  
     
     
         30 . A fiber as defined in  claim 25 , wherein the sheath polymer comprises from about 20% by weight to about 70% by weight of the continuous filaments.  
     
     
         31 . A fiber as defined in  claim 25 , wherein the sheath polymer comprises a blend of the random copolymer and a polypropylene homopolymer.