Air bag fabric possessing improved packed volume and stable air permeability

Abstract

A fabric for use in an air bag is provided. The fabric of the invention is produced by mechanically compressing a preliminary fabric constructed substantially of synthetic yarn such that the packed volume per unit area of the compressed fabric is less than the packed volume per unit area of the preliminary fabric. Air permeability is not adversely affected.

1. A process to provide a plain weave air bag fabric comprising the steps of: providing an uncoated plain weave fabric having a permeability greater than one cubic foot of air per minute per square foot of fabric at a pressure dial of 124 Pascals (0.5 inches of water) across the fabric in its untensioned state , supplying said plain weave fabric into the nip of a continuous rubber belt and a heated drum to compact the woven fabric therebetween and allowing the compacted fabric to recoil as it exits the nip of the belt and the heated drum to provide a fabric having a permeability greater than one cubic foot of air per minute per square foot of fabric at a pressure drop of  124  Pascals (   0 . 5  inches of water )  across the fabric in its untensioned state and  having a permeability of less than five cubic feet of air per minute per square foot at a pressure drop of 124 Pascals (0.5 inches of water) across the fabric when the fabric is subjected to substantially equivalent biaxial tension in both the warp and fill direction equal to or less than 150 pounds per linear inch. 
     
     
       2. The process according to  claim 1 , wherein the permeability of the fabric never exceeds about four cubic feet of air per minute per square foot of fabric at a pressure drop of 124 Pascals (0.5 inches of water) across the fabric when the fabric is subjected to substantially equivalent biaxial tension forces in both the warp and the fill directions up to about 150 pounds force per linear inch. 
     
     
       3. The process according to  claim 1 , wherein the permeability of the fabric never exceeds about three cubic feet of air per minute per square foot of fabric at a pressure drop of 124 Pascals (0.5 inches of water) across the fabric when the fabric is subjected to substantially equivalent biaxial tension forces in both the warp and the fill directions up to about 150 pounds force per linear inch. 
     
     
       4. The process according to  claim 1 , wherein the permeability of the fabric never exceeds about two cubic feet of air per minute per square foot of fabric at a pressure drop of 124 Pascals (0.5 inches of water) across the fabric when the fabric is subjected to substantially equivalent biaxial tension forces in both the warp and the fill directions up to about 150 pounds force per linear inch. 
     
     
       5. The process of  claim 1  wherein the yarn in said fabric is substantially all nylon 6.6. 
     
     
       6. The process of  claim 5  wherein said heated drum operates at a temperature of between room temperature and 325° F. 
     
     
       7. The process of  claim 6  wherein said drum temperature is below 250° F.