Nonwoven fiber webs with poly(phenylene sulfide) binder

Abstract

The present invention relates to a nonwoven web comprised of metal or refractory fibers with poly(phenylene sulfide) as a binder. The nonwoven web is prepared by forming a foam furnish by agitating the fibers in a foamed medium, and passing the foam furnish onto a screen and defoaming the furnish. It is preferred that the poly(phenylene sulfide) binder is added to the foam furnish in the form of fibers. Once the furnish is defoamed to form a nonwoven web, the sheet is heated at a temperature sufficient to melt the poly(phenylene sulfide) binder.

What is claimed is:  
     
         1 . A nonwoven fibrous web comprised of metal or refractory fibers and poly(phenylene sulfide) as a binder for said fibers.  
     
     
         2 . The nonwoven web of  claim 1 , wherein the web is comprised of metal fibers.  
     
     
         3 . The nonwoven web of  claim 1 , wherein the web is comprised of refractory fibers.  
     
     
         4 . The web of  claim 3 , wherein the web is comprised of carbon fibers.  
     
     
         5 . The nonwoven web of  claim 4 , wherein the carbon fibers are comprised of activated carbon fibers.  
     
     
         6 . The nonwoven web of  claim 1 , wherein the web is comprised of zinc, nickel and/or stainless steel fibers.  
     
     
         7 . The nonwoven web of  claim 1 , wherein the poly(phenylene sulfide) binder comprises a poly(phenylene sulfide) having a para content greater than 75%.  
     
     
         8 . The nonwoven web of  claim 1 , wherein the web is comprised of ceramic fibers.  
     
     
         9 . The nonwoven web of  claim 1 , wherein the web is comprised of zinc fibers.  
     
     
         10 . A method for forming a nonwoven fibrous web comprised of metal or refractory fibers with poly(phenylene sulfide) as a binder, which comprises: 
 (i) forming a foam furnish by agitating metal and/or refractory fibers, and poly(phenylene sulfide) in a foamed medium with an apparatus comprising agitation means mounted for displacement within the foamed medium and including a leading surface facing in a direction of displacement, the leading surface including upper and lower portions converging in the direction of displacement to form a generally convex leading surface, with the agitating means including a non-convex trailing surface facing away from the direction of displacement; and driving means for displacing the agitating means in the direction of displacement for dispersing and separating the fibers within the foamed medium; and    (ii) passing the foam furnish onto a screen and defoaming the furnish to form a nonwoven web; and    (iii) heating the formed web at a temperature sufficient to melt the poly(phenylene sulfide) contained in the web.    
     
     
         11 . The method of  claim 10 , wherein the fibers are comprised of carbon fibers.  
     
     
         12 . The method of  claim 10 , wherein the fibers are comprised of metal fibers.  
     
     
         13 . The method of  claim 12 , wherein the fibers are comprised of zinc, nickel or stainless steel fibers.  
     
     
         14 . The method of  claim 10 , wherein the poly(phenylene sulfide) is present in the foam furnish in the form of poly(phenylene sulfide) fiber.  
     
     
         15 . A filter comprised of the nonwoven web of  claim 1 .  
     
     
         16 . A fuel cell comprised of a nonwoven web as defined in  claim 1 .  
     
     
         17 . An electrode comprised of a nonwoven web as defined in  claim 1.