High strength fabrics consisiting of thin gauge constant compression elastic fibers

Abstract

Elastic fibers are disclosed which have a relatively flat modulus curve at between 100% and 200% elongation. The fibers can be made into garments having a very comfortable feel. The preferred elastic fibers are made from thermoplastic polyurethane polymers and are made by a unique melt spinning process where the fiber is wound into bobbins at a speed just slightly higher than the melt velocity of the polymer exiting the spinneret.

What is claimed is: 
     
         1 . A thin gauge, constant compression, high burst strength elastic fiber having an ultimate elongation of at least 400% and having a relativity flat modulus in the load and unload cycle between 100% and 200% elongation. 
     
     
         2 . The fiber of  claim 1  wherein a 40 denier monofilament fiber has a width of less than 100 microns. 
     
     
         3 . The fiber of  claim 1 , wherein when said fiber having a denier of 70 is made into a fabric and said fabric is tested for puncture strength according to ASTM D751 said fabric has a load at failure of greater than 6 pounds. 
     
     
         4 . The fiber of  claim 1 , wherein said fiber is a thermoplastic polyurethane fiber. 
     
     
         5 . The fiber of  claim 4 , wherein said fiber is a polyester thermoplastic polyurethane. 
     
     
         6 . The fiber of  claim 5 , wherein said fiber is crosslinked with a polyether crosslinking agent. 
     
     
         7 . The fiber of  claim 5 , wherein said polyester thermoplastic polyurethane has a weight average molecular weight of from 200,000 to 700,000 Daltons. 
     
     
         8 . The fiber of  claim 6 , wherein said crosslinking agent is from 5 to 20 weight percent of the combined weight of said polyester thermoplastic polyurethane and said crosslinking agent. 
     
     
         9 . The fiber of  claim 8 , wherein said crosslinking agent is from 8 to 12 weight percent of the combined weight of said polyester thermoplastic polyurethane and said crosslinking agent. 
     
     
         10 . A fabric comprising at least two different fibers wherein at least one of said fibers is a thermoplastic polyurethane fiber and at least one of said fibers is a hard fiber, and wherein said thermoplastic polyurethane fiber has a relatively flat stress-strain curve between 100 and 200 percent elongation. 
     
     
         11 . The fabric of  claim 10 , wherein said fabric is made up of two strands of thermoplastic polyurethane fiber for every one strand of hard fiber. 
     
     
         12 . The fabric of  claim 10 , wherein said thermoplastic polyurethane fiber has a denier of from 20 to 600. 
     
     
         13 . The fabric of  claim 12 , wherein said thermoplastic polyurethane fiber has a denier of from 70 to 360. 
     
     
         14 . The fabric of  claim 10 , wherein said hard fiber is selected from the group consisting of Nylon and polyester. 
     
     
         15 . The fabric of  claim 14 , wherein said hard fiber has a denier of about 70 and said thermoplastic polyurethane fiber has a denier of about 140. 
     
     
         16 . An article of clothing comprising the fabric of  claim 10 . 
     
     
         17 . The article of clothing of  claim 16 , wherein said article is an undergarment. 
     
     
         18 . The article of clothing of  claim 17 , wherein said article is a bra. 
     
     
         19 . A process for producing an elastic fiber having a relatively flat modulus in the load and unload cycle between 100% and 200% elongation, said process comprising:
 (a) melt spinning a thermoplastic elastomer polymer through a spinneret; and   (b) winding the elastic fiber into bobbins at a winding speed which is no greater than 50% of the polymer melt velocity exiting the spinneret.   
     
     
         20 . The process of  claim 19 , wherein said winding speed is no greater than 20% of the polymer melt velocity exiting the spinneret. 
     
     
         21 . The process of  claim 20 , wherein said winding speed is no greater than 10% of the polymer melt velocity exiting the spinneret. 
     
     
         22 . The process of  claim 19 , wherein said thermoplastic elastomer polymer is a thermoplastic polyurethane.