Method for making improved sealability polyolefin fibers, the fibers made thereby and non-woven textile materials including the fibers

Abstract

A method for making improved sealability polyolefin fibers comprising extruding a polyolefin ( 2 ) and at least one polyolefin copolymer ( 4 ) having a melting temperature less than that of the melting temperature of the polyolefin to form fibers ( 9 ) having outer surfaces wherein at least part of the outer surfaces is comprised of the low-melting polymer and which have high sealability properties.

I claim:  
     
         1 . A method for making an improved sealability polyolefin fiber comprising extruding a polyolefin and at least one low-melting polyolefin copolymer having a melting temperature of about 140-150° C., to form a polyolefin fiber wherein the polyolefin fiber has one or more outer surfaces comprising the low-melting polyolefin copolymer, and wherein the polyolefin fiber is in a form of a filament or a cut fiber having a cut length of at least 38 mm, and wherein the polyolefin fiber has a count of 1 to 70 dtex.  
     
     
         2 . The method according to    claim 1   , wherein the method comprises extruding a mixture of molten masses of polyolefin and low-melting polyolefin copolymer to provide a heterogeneous structure fiber comprising the polyolefin and the low-melting polyolefin copolymer.  
     
     
         3 . The method according to    claim 1   , wherein the low-melting polyolefin copolymer has a melting temperature of 148° C.  
     
     
         4 . The method according to    claim 1   , wherein the method comprises extruding the polyolefin and the low-melting polyolefin copolymer in a sheath-core extrusion process.  
     
     
         5 . The method according to    claim 1   , wherein the method comprises extruding the polyolefin and the low-melting polyolefin copolymer in a side-by-side extrusion process.  
     
     
         6 . The method according to    claim 1   , comprising extruding the polyolefin and the low-melting polyolefin copolymer to form a fiber having a composite construction and geometry.  
     
     
         7 . The method according to    claim 1   , wherein the polyolefin is polyethylene, polypropylene, polybutene, or polyisoprene.  
     
     
         8 . An improved sealability polyolefin fiber having an outer surface, wherein the polyolefin fiber is in the form of a filament or a cut fiber having a cut length of at least 38 mm and wherein the polyolefin fiber has a count of 1 to 70 dtex and wherein the polyolefin fiber has a heterogeneous structure comprising polyolefin and at least one low-melting polyolefin copolymer wherein the low-melting polyolefin copolymer has a melting temperature of about 140-150° C. and wherein the low-melting polyolefin copolymer comprises at least a portion of the outer surface of the polyolefin fiber.  
     
     
         9 . The polyolefin fiber according to    claim 8   , wherein the polyolefin fiber is a bicomponent sheath-core fiber having an outer sheath comprising the low-melting polyolefin copolymer and a core comprising the polyolefin.  
     
     
         10 . The polyolefin fiber according to    claim 8   , wherein the low-melting polyolefin copolymer has a melting temperature of 148° C.  
     
     
         11 . The polyolefin fiber according to    claim 8   , wherein the polyolefin fiber is a side-by-side fiber comprising both the polyolefin and low-melting polyolefin copolymer.  
     
     
         12 . The polyolefin fiber according to    claim 8   , wherein the fiber has a sealability of 10 to 12 N for 2.2 dtex fibers.  
     
     
         13 . The polyolefin fiber according to    claim 8   , wherein the polyolefin is polyethylene, polypropylene, polybutene, or polyisoprene.  
     
     
         14 . A non-woven textile material comprising a web wherein the web is comprised of polyolefin fiber in a form of a filament or a cut fiber having a cut length of at least 38 mm and wherein the polyolefin fiber has a count of 1 to 70 dtex and wherein the polyolefin fiber has an outer surface and a heterogeneous structure comprising polyolefin and at least one polyolefin copolymer having a melting temperature of about 140 -150° C. and wherein the low-melting polyolefin copolymer comprises at least a portion of the outer surface of the polyolefin fiber.  
     
     
         15 . The material according to    claim 14   , wherein the low-melting polyolefin copolymer has a melting temperature of 148° C.  
     
     
         16 . The material according to    claim 14   , wherein the web comprises a bicomponent sheath-core fiber having an outer sheath comprising the low-melting polyolefin copolymer and a core comprising the polyolefin.  
     
     
         17 . The material according to    claim 14   , wherein the web comprises a side-by-side fiber comprising both the polyolefin and low-melting polyolefin copolymer.  
     
     
         18 . The material according to    claim 14   , wherein filaments are sealed to one another at that portion of the outer surface of the fibers formed by the low-melting polyolefin copolymer.  
     
     
         19 . The material according to    claim 14   , wherein the polyolefin fiber has a sealability of 10 to 12 N for a fiber of 2.2 dtex.  
     
     
         20 . The material according to    claim 14   , wherein the material is a non-woven fabric having a weight of 19.5 g/m 2  and comprising fibers of 2.2 dtex and 40 mm in cut length.  
     
     
         21 . The material according to    claim 14   , wherein upon calendaring at a speed of 200 m/min and at a calendaring temperature of about 147 to 149° C., the fabric has a machine direction maximum load at breaking of about 39 N/5 cm. with an elongation of about 44% and a cross direction maximum load at breaking of about 9 N/5 cm. with an elongation of about 86%.  
     
     
         22 . The material according to    claim 14   , wherein the polyolefin is polyethylene, polypropylene, polybutene, or polyisoprene.  
     
     
         23 . A method of using an improved sealability polyolefin fiber having an outer surface wherein the polyolefin fiber is in the form of a filament or a cut fiber having a cut length of at least 38 mm and wherein the polyolefin fiber has a count of 1 to 70 dtex and wherein the polyolefin fiber has a heterogeneous structure comprising polyolefin and at least one low-melting polyolefin copolymer wherein the low-melting polyolefin copolymer has a melting temperature of about 140-150° C. and wherein the low-melting polyolefin copolymer comprises at least a portion of the outer surface of the polyolefin fiber, the method comprises incorporating the polyolefin fiber into a non-woven textile material.  
     
     
         24 . The method of using according to    claim 23   , wherein the low-melting polyolefin copolymer has a melting temperature of 148° C.  
     
     
         25 . A fiber obtained according to the method of    claim 1   , wherein the fiber is used to make a non-woven textile material sealed through a hot calendar, hot air or another system to obtain a non-woven textile material for hygienic and sanitary purposes.