Polyolefin-based synthetic fibers and method therefor

Abstract

The invention provides a method for making fibers and yarns having improved dyeability with reactive and disperse dyes, resistance to staining and improved mechanical properties and characteristics. The method includes blending a polyolefin polymer and a fibril forming polymer to provide a mixture of polyolefin and fibril forming polymers. The mixture is conducted to a hot melt extruder to provide a substantially homogenous molten mixture of polyolefin and fibril forming polymers. The molten mixture is forced through a spinneret having a length to diameter (L/D) ratio ranging from about 3 to about 30 to provide a fiber having a polyolefin matrix and elongate, substantially discontinuous fibrils of the fibril forming polymer dispersed into the polyolefin matrix, whereby the exterior surface of the fibers is substantially devoid of fibrils. Fibers made by the process of the invention are useful as carpet face yarn, in textiles, upholstery and other industrial applications, like chemical industry and others.

What is claimed is:  
     
         1 . A method for making fibers and yarns having denier per filament (dpf) size ranging from about 1 to about 30 dpf and improved mechanical properties comprising: 
 blending from about 55 to about 95 wt. % polyolefin polymer and from about 5 to about 45 wt. % fibril forming polymer to provide a mixture of polyolefin and fibril forming polymers;    conducting the mixture to a hot melt extruder to provide a substantially homogenous molten mixture of polyolefin and fibril forming polymers;    forcing the molten mixture through a spinneret having an length to diameter (L/D) ratio ranging from about 3 to about 30 at a shear rate ranging from about 1000 to about 5000 reciprocal seconds to provide a fiber having a polyolefin matrix and elongate, substantially discontinuous fibrils of the fibril forming polymer dispersed in the polyolefin matrix, whereby an exterior surface of the fibers is substantially devoid of fibrils.    
     
     
         2 . The method of  claim 1  wherein the fibril forming polymer is selected from the group consisting of polyamide polymers and polyester polymers.  
     
     
         3 . The method of  claim 1  wherein the polyolefin polymer comprises polypropylene.  
     
     
         4 . The method of  claim 1  wherein the blend comprises from about 15 to about 30 wt. % of fibril forming polymer.  
     
     
         5 . The method of  claim 1  wherein the L/D ratio of the spinneret ranges from about 6 to about 10.  
     
     
         6 . The method of  claim 1  wherein the mixture of polyolefin and fibril forming polymers comprises from about 0 to about 20 wt. % polyolefin compatibilizer selected from group consisting of maleated polypropylene, maleated ethylene/propylene copolymer, maleated styrene/butadiene/styrene copolymer, maleated styrene/ethylene/butadiene/styrene copolymer, maleated ethylene/propylene/diene monomer (EPDM) copolymer and maleated ethylene/propylene-rubber (EPR).  
     
     
         7 . The method of  claim 6  further comprising drying the polyolefin polymer, fibril forming polymer and compatibilizer to provide a mixture containing less than about 500 ppm moisture.  
     
     
         8 . The method of  claim 1  further comprising drying the polyolefin polymer and fibril forming polymer to provide a mixture containing less than about 500 ppm moisture.  
     
     
         9 . The method of  claim 1  further comprising dyeing the fibers with a dispersed dye, a reactive dye or a mixture of both to provide dyed fibers.  
     
     
         10 . The method of  claim 9  wherein the dyeing is conducted at a pressure ranging from about 1 to about 4 bar.  
     
     
         11 . The method of  claim 9  wherein the dyeing is conducted at a pressure ranging from about 1.5 to about 2 bar.  
     
     
         12 . A polyolefin-based yarn made by the method of  claim 1   
     
     
         13 . A BCF yarn made by the method of  claim 1  for use as a carpet face yarn.  
     
     
         14 . A yarn made by the method of  claim 1  wherein the yarn is manufactured as a POY, FDY or LDY yarn for use as a textile yarn.  
     
     
         15 . An upholstery yarn made by the method of  claim 1 .  
     
     
         16 . A staple yarn made by the method of  claim 1 .  
     
     
         17 . A method for improving the mechanical properties of yarns made of synthetic fibers at temperature of higher than room temperature comprising: 
 feeding a mixture containing from about 55 to about 95 wt. % polyolefin polymer, from about 5 to about 45 wt. % fibril forming polymer and from about 0 to about 20 wt. % polyolefin compatibilizer selected from the group consisting of maleated polypropylene, maleated ethylene/propylene copolymer, maleated styrene/butadiene/styrene copolymer, maleated styrene/ethylene/butadiene/styrene copolymer, maleated ethylene/propylene/diene monomer (EPDM) copolymer and maleated ethylene/propylene-rubber (EPR) to a hot melt extruder to provide a substantially homogeneous molten mixture of polyolefin, fibril forming polymer and compatibilizer;    forcing the molten mixture through a spinneret at a shear rate ranging from about 1000 to about 5000 reciprocal seconds, the spinneret having an length to diameter (L/D) ratio selected between 1 and 3 for increased fiber dyeability with cationic dyes and an L/D ratio selected between 3 and 30 for increased fiber dyeability with solution dyes, to provide a fiber having a polyolefin matrix and elongate, substantially discontinuous fibrils of the fibril forming polymer dispersed in the polyolefin matrix.    
     
     
         18 . The method of  claim 17  wherein the fibril forming polymer is selected from the group consisting of polyamide polymers and polyester polymers.  
     
     
         19 . The method of  claim 17  wherein the polyolefin matrix comprises polypropylene.  
     
     
         20 . The method of  claim 17  wherein the molten mixture comprises from about 15 to about 30 wt. % of fibril forming polymer.  
     
     
         21 . The method of  claim 17  wherein the L/D ratio of the spinneret ranges from about 6 to about 10.  
     
     
         22 . The method of  claim 17  further comprising drying the polyolefin polymer, fibril forming polymer and compatibilizer to provide a mixture containing less than about 500 ppm moisture.  
     
     
         23 . The method of  claim 17  further comprising dyeing the fibers with an acid dye to provide dyed fibers.  
     
     
         24 . The method of  claim 17  where the fibril forming polymer has cationic dyeability.  
     
     
         25 . The method of  claim 24  further comprising dying the fiber using a mixture of cationic dye and disperse dye.  
     
     
         26 . The method of  claim 23  wherein the dyeing is conducted at a pressure ranging from about 1 to about 4 bar.  
     
     
         27 . The method of  claim 25  wherein the dyeing is conducted at a pressure ranging from about 1 to about 4 bar.  
     
     
         28 . A BCF yarn made by the method of  claim 17  for use as a carpet face yarn.  
     
     
         29 . A yarn made by the method of  claim 17  wherein the yarn is manufactured as a POY, FDY or LDY yarn for use as a textile yarn.  
     
     
         30 . An upholstery yarn made by the method of  claim 17 .  
     
     
         31 . A staple yarn made by the method of  claim 17 .  
     
     
         32 . A yarn having improved mechanical properties comprising from about 55 to about 95 wt. % polyolefin continuous phase and from about 5 to about 45 wt. % discontinuous phase of fibrils dispersed in the polyolefin continuous phase, the fibrils being derived from a fibril forming polymer selected from the group consisting of polyamide polymers and polyester polymers, wherein the polyolefin continuous phase is substantially devoid of fibrils on an exposed surface thereof and wherein the yarn is dyeable and has an irreversible deformation at about 25° C. of less than about 3%.  
     
     
         33 . The yarn of  claim 32  wherein the polyolefin continuous phase comprises polypropylene.  
     
     
         34 . The yarn of  claim 33  wherein the fibrils comprise polyester.  
     
     
         35 . The yarn of  claim 33  wherein the fibrils comprise polyamide.  
     
     
         36 . The yarn of  claim 32  wherein the fibrils comprise cationic dyeable polyamide.  
     
     
         37 . The yarn of  claim 32  having improved acid dyeability, color-fastness and stain resistance.  
     
     
         38 . The yarn of  claim 36  having improved cationic dyeability, color-fastness and stain resistance.  
     
     
         39 . The yarn of  claim 32  comprising a BCF yarn for use as a carpet face yarn.  
     
     
         40 . The yarn of  claim 32  comprising a POY, FDY or LDY yarn for use as a textile yarn.  
     
     
         41 . The yarn of  claim 32  comprising an upholstery yarn.  
     
     
         42 . A staple yarn made by the method of  claim 32.