Flexible graphite article and method of manufacture

Abstract

A flexible graphite sheet exhibiting enhanced isotropy is provided. In addition, an apparatus, system and method for continuously producing a resin-impregnated flexible graphite sheet is also provided.

1 . A method for forming a graphite plate sealed with a resin sealant, said method comprising:
 (i) providing a graphite sheet having opposed planar surfaces defining an interior portion therebetween, said sheet being formed from exfoliated graphite particles to provide said interior with pores and defining a graphite density of said sheet;   (ii) providing a curable resin sealant selecting from the group consisting of a phenolic resin, a vinyl resin, a silicone resin, an acrylic resin, an epoxy resin, and combinations thereof;   (iii) contacting said resin sealant with at least one of said planar surfaces, allowing said resin sealant to communicate through said pores;   (iv) compressing said sheet to form a graphite plate having graphite density after compression, wherein said graphite density is greater after compression than before compression; and   (v) curing said resin sealant contained within said pores to seal said plate.   
     
     
         2 . The method of  claim 1  wherein said graphite density before compression is from about 0.08 to about 0.8 g/cc. 
     
     
         3 . The method of  claim 2  wherein said graphite density before compression is from about 0.08 to 0.5 g/cc. 
     
     
         4 . The method of  claim 2  wherein said graphite density after compression is from about 1.0 to 2.2 g/cc. 
     
     
         5 . The method of  claim 1  wherein compressing further includes forming a pattern in at least one of said planar surfaces. 
     
     
         6 . The method of  claim 5  wherein said plate is a fluid-flow plate of a fuel cell and further wherein said pattern is a continuous fluid-flow channel. 
     
     
         7 . The method of  claim 1  further comprising the step of filling from about 70% to about 95% of said pores on a volume basis with said resin sealant. 
     
     
         8 . The method of  claim 1  further including the step of providing a free radical initiator to initiate cure of said resin sealant. 
     
     
         9 . The method of  claim 8  wherein said free radical initiator includes a heat-curing initiator to produce free radicals by thermal decomposition to cure said resin sealant. 
     
     
         10 . The method of  claim 8  wherein said free radical initiator includes an anaerobic-curing initiator to produce free radicals upon the exclusion of oxygen to cure said resin sealant. 
     
     
         11 . A graphite plate comprising:
 (i) a graphite sheet formed from exfoliated graphite particles and having an internal portion with pores between opposed planar surfaces; and   (ii) a curable resin sealant contained within greater than 70% of said pores on a volume basis, wherein upon curing said resin sealant said graphite sheet is sealed with said resin sealant to form said plate.   
     
     
         12 . The graphite plate of  claim 11  wherein said resin sealant includes a resin sealant selected from the group consisting of a phenolic resin, a vinyl resin, a silicone resin, an acrylic resin, an epoxy resin, and combinations thereof. 
     
     
         13 . The graphite plate of  claim 11  further including a free radical initiator to initiate cure of said resin sealant. 
     
     
         14 . The graphite plate of  claim 13  wherein said free radical initiator includes a heat-curing initiator to produce free radicals by thermal decomposition to cure said resin sealant. 
     
     
         15 . The graphite plate of  claim 13  wherein said free radical initiator includes an anaerobic-curing initiator to produce free radicals upon the exclusion of oxygen to cure said resin sealant. 
     
     
         16 . The graphite plate of  claim 11  wherein said graphite plate is compressed to form a fluid-flow plate of a fuel cell. 
     
     
         17 . The graphite plate of  claim 16  wherein said fluid-flow plate includes a continuous fluid-flow channel extending through at least one of said planar surfaces. 
     
     
         18 . A method for forming a graphite article comprising compressing exfoliated graphite particles into a coherent self-supporting sheet; impregnating the sheet with resin; compressing the sheet to increase the density thereof; and curing the resin. 
     
     
         19 . The method of  claim 18  which further comprises mechanically deforming a surface of the sheet to provide a series of repeating patterns on a surface of the sheet. 
     
     
         20 . The method of  claim 19  wherein the graphite article comprises a fuel cell flow field plate. 
     
     
         21 . A graphite article comprising a sheet of compressed particles of exfoliated graphite having a density of about 0.08 g/cc to about 2.00 g/cc and impregnated with a cured resin. 
     
     
         22 . The graphite article of  claim 21  which comprises a fuel cell flow field plate.