Elastic nonwoven made from thermoset fibers

Abstract

The present invention is directed toward a nonwoven fiber web material comprised of thermoset fibers that has a machine direction and a cross direction with elastic stretch and recovery properties in the cross direction.

What is claimed is: 
     
         1 . A nonwoven material comprising thermoset polymer fibers that has a machine direction and a cross direction with elastic stretch and recovery properties in the cross direction. 
     
     
         2 . The nonwoven material of  claim 1 , wherein the thermoset polymer is polyimide. 
     
     
         3 . The nonwoven material of  claim 2 , wherein the polyimide is fully aromatic. 
     
     
         4 . The nonwoven material of  claim 3 , wherein the thermoset polymer fibers have a mean fiber diameter less than about 1 micron. 
     
     
         5 . The nonwoven material of  claim 1 , wherein the nonwoven material recovers at least about 95% of the elongation when stretched in the cross direction to at most about 50%. 
     
     
         6 . The nonwoven material of  claim 1 , wherein the nonwoven material recovers at least about 85% of the elongation when stretched in the cross direction to at most about 75%. 
     
     
         7 . The nonwoven material of  claim 1 , wherein the nonwoven material has an elongation to break of greater than about 100% in the cross direction. 
     
     
         8 . The nonwoven material of  claim 1 , wherein the elongation to break in the cross direction is greater than about 10 times the elongation to break in the machine direction. 
     
     
         9 . The nonwoven material of  claim 1 , wherein the load to break in the machine direction is greater than about 5 times the load to break in the cross direction. 
     
     
         10 . A process for making the nonwoven material of  claim 1 , comprising spinning fibers from a thermoset polymer into an unstretched nonwoven material and then stretching the unstretched nonwoven material while simultaneously elevating the temperature above the setting temperature of the polymer to create a nonwoven material. 
     
     
         11 . The process for making the nonwoven material of  claim 10 , wherein the fibers are spun from polyamic acid and the unstretched nonwoven material is stretched while simultaneously imidizing the polyamic acid to create a polyimide nonwoven material. 
     
     
         12 . A filter media comprising at least one layer of the nonwoven material of  claim 1 . 
     
     
         13 . The filter media of  claim 12  wherein the thermoset polymer is polyimide. 
     
     
         14 . A garment comprising at least one layer of the nonwoven material of  claim 1 . 
     
     
         15 . The garment of  claim 14  wherein the thermoset polymer is polyimide.