Stretchable nonwovens

Abstract

A nonwoven material which can be elongated and which will partially recover. The material comprises a web of fibers comprising polymeric chains which fibers are entangled with one another. The fibers are stretched in a first direction at a temperature wherein the fibers are aligned in a first direction and the polymeric chains within the fiber are also orientated in such first direction. The fibers are then cooled and demonstrate an ability to elongate and partially recover in a second direction that is different from the first direction.

1 . A nonwoven material which can be elongated in a selected direction, comprising 
 (a) a web of fibers comprising polymeric chains which fibers are entangled with one another characterized in that: 
 (i) said fibers have been stretched in a first direction at a temperature wherein said fibers are aligned in said first direction and said polymeric chains in said fiber are orientated in said first direction; and  
 (ii) said fibers have been cooled below said temperature;  
   wherein said web of fibers demonstrate an ability to elongate in a second direction that is different from said first direction and wherein said fibers can also partially recover from said elongation in said second direction.    
   
   
       2 . The nonwoven fabric of  claim 1  wherein said polymeric chains have a melting point Tm, and said temperature is below Tm.  
   
   
       3 . The nonwoven fabric of  claim 2  wherein temperature below Tm is about 0.1-20° C. below Tm.  
   
   
       4 . The nonwoven fabric of  claim 1  wherein said polymer chains have a Tg and Tm, and said temperature is at or above Tg and below Tm.  
   
   
       5 . The nonwoven fabric of  claim 1  wherein said fibers elongate in said second direction up to about 70% and partially recover.  
   
   
       6 . The nonwoven fabric of  claim 1  wherein said second direction is substantially perpendicular to said first direction.  
   
   
       7 . The nonwoven fabric of  claim 1  wherein said web of fibers comprises a microfilament nonwoven fabric having a weight of 30 to 150 g/m 2  and a tear strength of >40 N/5 cm, the nonwoven fabric being made of continuous multicomponent filaments having a titer of 1.5 to 5 dtex which are melt-spun, stretched, and directly laid down to form a nonwoven fabric, wherein the continuous multicomponent filaments are split, at least to the extent of 80%, to form continuous microfilaments having a titer of 0.01 to 1.0 dtex and bonded.  
   
   
       8 . The nonwoven fabric of  claim 7  wherein said continuous multicomponent filaments comprise a continuous bicomponent filament comprising two polymers.  
   
   
       9 . The nonwoven fabric of  claim 8  wherein one of said polymers comprises a polyester polymers, and one of said polymers comprise a polymer selected from the group consisting of polyamides, polyolefins, and mixtures thereof.  
   
   
       10 . A process for providing a nonwoven material with stretchable characteristics, comprising the steps of: 
 (a) forming a web of polymeric filaments that are entangled with one another, wherein said polymeric filaments have a Tm;    (b) stretching said web in a first direction at a temperature wherein said temperature is below Tm to align said fibers in said first direction and to orient said polymeric chains in said fiber in said first direction;    (c) cooling said fibers below said temperature wherein said nonwoven material can elongate in a second direction that is different from said first direction and partially recover from said elongation in said second direction.    
   
   
       11 . The process of  claim 10  wherein said temperature below Tm is about 0.1-20° C. below Tm.  
   
   
       12 . The process of  claim 10  wherein said fibers elongate in said second direction up to about 70% and partially recover.  
   
   
       13 . A process for providing a nonwoven material with stretchable characteristics, comprising the steps of: 
 (a) forming a web of polymeric filaments that are entangled with one another, wherein said polymeric filaments have a Tm and said web has a length and a width;    (b) stretching said web in a first direction coinciding with said web length at a temperature wherein said temperature is below Tm to align said fibers in said first direction and to orient said polymeric chains in said fiber in said first direction and wherein said width of said web is reduced;    (c) cooling said fibers below said temperature wherein said nonwoven material can elongate in a second direction across said width of said web and partially recover from said elongation.    
   
   
       14 . The process of  claim 13  wherein including the additional step wherein said web is further stretched across said width of said web, and wherein said nonwoven material can still elongate in a second direction across said width of said web and partially recover from said elongation.  
   
   
       15 . The process of  claim 13  wherein said step of stretching across said width of said web comprises placing said web on a tenter frame.