Fabric for protection against electric arc hazards

Abstract

An improved knit fabric system for protecting against electrical arch hazards and promoting garment visibility is provided. The inventive knit fabric is either a solid fabric substrate or of a mesh construction that absorbs the thermal energy of an electric arc and, especially for the mesh construction, absorbs thermal energy or heat flux to prevent garment combustion. The solid or mesh version of the inventive knit fabric incorporates conductive fibers for draining away and thereby dissipating accumulated electrical charges. Such conductive fibers are incorporated into the fabric of the invention, by either being knitted into the fabric as it is formed or by the process of yarn spinning.

1 . A fabric comprising: 
 a knit construction made from high performance yarns that are resistant to melting, dripping and burning at a temperature of at least 700° F.; and    conductive yarns intermixed with said high performance yarns.    
   
   
       2 . The fabric of  claim 1 , wherein the high performance yarns are selected from the group consisting of modacrylic yarns, aramid yarns and polybenzimodazole yarns.  
   
   
       3 . The fabric of  claim 2 , wherein the high performance yarns have a yarn count of between about 12/2 c.c. and 32/2 c.c.  
   
   
       4 . The fabric of  claim 2 , wherein the high performance yarns comprise modacrylic yarns having an LOI value of between about 28 and 33.  
   
   
       5 . The fabric of  claim 2 , wherein the high performance yarns comprise aramid yarns having an LOI value of between about 28 and 30.  
   
   
       6 . The fabric of  claim 5 , wherein the aramid yarns comprise para-aramid fibers having a tenacity of between about 28 and 32 grams/denier.  
   
   
       7 . The fabric of  claim 2 , wherein the high performance yarns comprise polybenzimodazole having an LOI value of between about 35 and 40.  
   
   
       8 . The fabric of  claim 2 , wherein the knit construction comprises a knitted mesh.  
   
   
       9 . The fabric of  claim 8 , wherein the fabric has a mesh count of between about 3 and 5 meshes/inch in width and between about 4 and 5 meshes/inch in length.  
   
   
       10 . The fabric of  claim 2 , wherein the high performance yarns are present in an amount between about 85 and 95 weight percent and conductive yarns are present in the fabric in an amount between about 3 and 5 weight percent.  
   
   
       11 . The fabric of  claim 2 , wherein the conductive yarns are selected from the group consisting of conductive carbon fiber yarns, nylon fiber yarns coated with a metal, and metal fiber yarns.  
   
   
       12 . The fabric of  claim 2 , wherein the conductive yarns are knitted together with the high performance yarns.  
   
   
       13 . The fabric of  claim 2 , wherein the conductive yarns are arrayed in a diamond-like configuration.  
   
   
       14 . The fabric of  claim 2 , wherein the knit construction is produced by either a warp or weft knit system.  
   
   
       15 . The fabric of  claim 11 , wherein the carbon fiber yarns comprise a conductive carbon core surrounded by a non-conductive polymer cover.  
   
   
       16 . The fabric of  claim 11 , wherein the carbon fiber yarns comprise carbon particles embossed along a filament surface.  
   
   
       17 . The fabric of  claim 4 , wherein the modacrylic yarns have a tenacity of up to 2.8 grams/denier and fusing temperature of between about 371 and 410° F.  
   
   
       18 . The fabric of  claim 4 , wherein the modacrylic yarns have a moisture regain of between about 0.4 and 4.0%.  
   
   
       19 . The fabric of  claim 2 , wherein the high performance yarns comprise modacrylic yarns and the conductive yarns comprise nylon fibers coated with silver.  
   
   
       20 . A fabric comprising a knit construction made from spun modacrylic yarns in an amount between about 85 and 95 weight percent and conductive yarns in an amount between about 3 and 5 weight percent.  
   
   
       21 . The fabric of  claim 20 , wherein the conductive yarns are selected from the group consisting of conductive carbon fiber yarns, nylon fiber yarns coated with a metal, and metal fiber yarns.  
   
   
       22 . The fabric of  claim 20 , wherein the fabric has a mesh construction.  
   
   
       23 . A method for producing a fabric comprising knitting together high performance yarns selected from the group consisting of modacrylic yarns, aramid yarns and polybenzimodazole yarns with conductive yarns.