Stretchable nonwoven materials with controlled retraction force and methods of making same

Abstract

A method of forming fibers into a web includes the steps of co-extruding a first elastomeric component and a second thermoplastic component; directing the first and second components through a fiber spin pack to form a plurality of continuous molten fiber spinlines, where the first elastomeric component is present in an amount greater than about 70 percent by weight of the molten fibers and the second thermoplastic component is present in an amount of between about 10 and 30 percent by weight of the molten fibers; attenuating the spinlines and routing the plurality of molten fibers through a quench chamber to form a plurality of cooled fibers; routing the plurality of cooled fibers through a fiber draw unit, whereby the fibers are pulled downward; allowing the pulled fibers to be deposited onto a forming surface thereby forming a web wherein the fibers are relaxed; stabilizing the web; and bonding the web to produce a web demonstrating greater than about 25 percent machine direction stretch recovery.

What is claimed is:  
     
         1 . A method of forming fibers into a web, comprising the steps of: 
 a) co-extruding a first elastomeric component and a second thermoplastic component;    b) directing said first and second components through a fiber spin pack to form a plurality of continuous molten multicomponent fibers, wherein said first elastomeric component is present in an amount greater than about 70 percent by weight of the molten fibers and said second thermoplastic component is present in an amount of between about 10 and 30 percent by weight of the molten fiber spinlines;    c) attenuating said spinlines and routing said plurality of molten fibers through a quench chamber to form a plurality of cooled fibers;    d) routing said plurality of cooled fibers through a fiber draw unit, whereby said fibers are pulled downward;    e) allowing said pulled fibers to be deposited onto a forming surface thereby forming a web wherein the fibers are relaxed;    f) stabilizing said web;    g) bonding said web to produce a web demonstrating greater than about 25 percent machine direction stretch recovery.    
     
     
         2 . The method of  claim 1  wherein said first and second components are formed in a sheath/core arrangement with the first component being the core and the second component being the sheath.  
     
     
         3 . The method  claim 1  wherein said first and second components are formed in a concentric configuration when they are directed through the spinpack.  
     
     
         4 . The method of  claim 1  wherein said first and second components are formed in eccentric configurations when they are directed through the spinpack.  
     
     
         5 . The method of  claim 1  wherein the stabilizing step is accomplished by either a hot air knife, compaction rolls, or a combination thereof.  
     
     
         6 . The method of  claim 1  further including the step of post formation stretching following bonding.  
     
     
         7 . The method of  claim 1  wherein said post-formation stretching is accomplished by either a series of stretch rolls, a series of grooved rolls, or tenter frames.  
     
     
         8 . The method of  claim 1  wherein said first elastomeric component is selected from styrenic block copolymers, polyurethane elastomers, copolyether esters, polyether block polyamide copolymers, ethylene vinyl acetate elastomers, ether amide block copolymers, and olefinic elastomers, including single-site catalyzed olefinic elastomers.  
     
     
         9 . The method of  claim 1  wherein said second thermoplastic component is selected from polyolefins, polyesters, polyethers, random copolymers, polymeric blends, and polyamides.  
     
     
         10 . The method of  claim 1  wherein said bonding is accomplished by thermal bonding.  
     
     
         11 . The method of  claim 10  wherein said bonding is accomplished by point bonding.  
     
     
         12 . The method of  claim 1  wherein said first component is present in a percentage between about 80 and 90 percent and said second component is present in an amount between about 10 and 20 percent.  
     
     
         13 . A material made in accordance with the method of  claim 1 .  
     
     
         14 . A material made in accordance with the method of  claim 6 .  
     
     
         15 . A material for use in personal care products, comprising: 
 a fibrous nonwoven web including bicomponent fibers, wherein said bicomponent fibers are of a sheath core configuration, wherein said core is comprised of an elastomeric component and said sheath is comprised of a thermoplastic component; wherein said core is present in an amount greater than about 70% by weight; and further wherein said web is bonded, such that said web demonstrates a fiber length per bond spacing of greater than about 23.    
     
     
         16 . The material of  claim 15  wherein said fiber length per bond spacing is between about 23 and 38.  
     
     
         17 . The material of  claim 16  wherein said fiber length per bond spacing is between about 27 and 36.  
     
     
         18 . A material for use in personal care products, comprising: 
 an elastic fibrous nonwoven web wherein said web is bonded, such that said web demonstrates a fiber length per bond spacing of greater than about 23, and further wherein said elastic fibrous nonwoven web demonstrates greater than about 25 percent machine direction stretch recovery.