Mixed fibers and nonwoven fabrics made from the same

Abstract

The subject matter disclosed herein relates generally to the production of a predetermined ratio of multicomponent fibers in combination with monocomponent fibers or other multicomponent fibers, preferably through a spunbonding process. After extrusion, these fibers can produce a fiber network that is subsequently bonded to produce a nonwoven fabric comprising multiple types of fibers. The multicomponent fibers within the network may be processed to remove one component by dissolution or to split the individual components into separate fibers. As a result, the fabric will be comprised of fibers with a range of diameters (micro- or nano-denier fibers as well as higher denier fibers) such that the fibers will not pack as tightly as in a homogeneous nonwoven fabric produced from one type of monocomponent or multicomponent fiber. The present invention additionally relates to methods for producing nonwoven fabrics with increased loft, breathability, strength, compressive properties, and filtration efficiency.

1 . A mixed filament spunbond fabric comprising a first fiber type and a second fiber type, the first fiber type comprising a segmented, bicomponent fiber having a cross-section such that each individual segment has a size of less than about 2 μm or comprising an islands in the sea bicomponent fiber having a cross-section such that each individual island has a size of less than about 1 μm, the second fiber type comprising a monocomponent fiber having a size greater than about 2 μm, the monocomponent fiber comprising at least about 20% by weight of the fibers in the fabric. 
     
     
         2 . The method of  claim 1 , wherein the fabric is hydroentangled, thermally bonded, or both hydroentangled and thermally bonded. 
     
     
         3 . The nonwoven fabric of  claim 1 , wherein the fabric exhibits an aerosol filtration quality factor (QF) of greater than about 0.10 mmH 2 O −1  when measured at a face velocity of 3.3 cm/s. 
     
     
         4 . The nonwoven fabric of  claim 1 , wherein the fabric exhibits a liquid filtration efficiency of at least about 65% while also exhibiting a flow resistance of less than about 0.10 psi when measured at a face velocity of 0.13 cm/s. 
     
     
         5 . The nonwoven fabric of  claim 1 , wherein the fabric exhibits an air permeability of at least about 10 ft 3 /ft 2  min when tested according to ASTM D 737-04. 
     
     
         6 . The nonwoven fabric of  claim 1 , wherein the plurality of filaments of the first fiber type are derived from a bicomponent fiber. 
     
     
         7 . A mixed filament spunbond fabric comprising a first fiber type and a second fiber type, the first fiber type comprising a plurality of individual filaments each having a size of less than about 2 μm, the second fiber type comprising a monocomponent fiber having a size greater than about 2 μm, wherein the monocomponent fiber comprises at least about 20% by weight of the fibers in the fabric. 
     
     
         8 . A nonwoven fabric prepared according to a method comprising:
 simultaneously melt spinning a set of fibers comprising a first fiber type and a second fiber type, the first fiber type comprising an islands in the sea fiber formed with a soluble sea component that dissolves to release a plurality of island filaments each less than about 1 denier in size, the second fiber type comprising at least one fiber that is greater than about 1 denier in size; and   collecting the melt-spun set of fibers.   
     
     
         9 . The nonwoven fabric of  claim 8 , wherein the fabric exhibits an aerosol filtration quality factor (QF) of greater than about 0.10 mmH 2 O −1  when measured at a face velocity of 3.3 cm/s. 
     
     
         10 . The nonwoven fabric of  claim 8 , wherein the fabric exhibits a liquid filtration efficiency of at least about 65% while also exhibiting a flow resistance of less than about 0.10 psi when measured at a face velocity of 0.13 cm/s. 
     
     
         11 . The nonwoven fabric of  claim 8 , wherein the fabric exhibits an air permeability of at least about 10 ft 3 /ft 2  min when tested according to ASTM D 737-04. 
     
     
         12 . The nonwoven fabric of  claim 8 , wherein the second fiber type comprises a bicomponent fiber. 
     
     
         13 . The nonwoven fabric of  claim 12 , wherein the bicomponent fiber is a segmented fiber that disassociates into a plurality of individual segments. 
     
     
         14 . The nonwoven fabric of  claim 13 , wherein each individual segment of the segmented fiber is greater than about 1 denier in size. 
     
     
         15 . The nonwoven fabric of  claim 13 , wherein each individual segment of the segmented fiber has a filament diameter of at least about 2 μm. 
     
     
         16 . The nonwoven fabric of  claim 8 , wherein the second fiber type comprises a monocomponent fiber. 
     
     
         17 . The nonwoven fabric of  claim 16 , wherein the monocomponent fiber has a diameter of at least about 5 μm. 
     
     
         18 . The nonwoven fabric of  claim 16 , wherein the fabric comprises at least about 20% by weight of the monocomponent fiber based on the overall weight of the fabric. 
     
     
         19 . The nonwoven fabric of  claim 8 , wherein each of the plurality of island filaments has a diameter of less than about 1 μm. 
     
     
         20 . The nonwoven fabric of  claim 19 , wherein each of the plurality of island filaments has a diameter of about 0.2 μm to about 0.8 μm. 
     
     
         21 . The nonwoven fabric of  claim 8 , wherein the second fiber type comprises an islands in the sea fiber formed with a soluble sea component that dissolves to release a plurality of island filaments each having a size that is greater than the size of the filaments from the first fiber type. 
     
     
         22 . The nonwoven fabric of  claim 21 , wherein the islands in the sea fiber of the first fiber type comprises a greater number of islands than the islands in the sea fiber of the second fiber type. 
     
     
         23 . The nonwoven fabric of  claim 22 , wherein the number of islands in the first and second fiber types are present at a ratio of at least 2:1. 
     
     
         24 . The nonwoven fabric of  claim 22 , wherein the number of islands in the first and second fiber types are present at a ratio of at least 10:1. 
     
     
         25 . The nonwoven fabric of  claim 8 , wherein the second fiber type comprises at least about 20% by weight of the total weight of the melt-spun fibers.