Fluororubber Composition and Production Method of Cross-Linked Fluororubber Product

Abstract

A fluororubber composition which (1) is clean, (2) achieves a higher specific gravity, (3) achieves a better physical property in terms of breaking elongation, (4) is free of halogen substance (chlorine), and (5) provides a rubber surface which is non-tacky to metal(s); and a method for producing a crosslinked fluororubber product. The fluororubber composition includes a peroxide-crosslinkable fluororubber comprising a terfluoropolymer; barium sulfate; a peroxide crosslinking agent; and a salt having BF 4 − as a counter ion; wherein the barium sulfate is included in an amount of 50 to 180 parts by weight based on 100 parts by weight of the fluoropolymer; and wherein the salt having BF 4 − as a counter ion is included in an amount of 0.7 to 1.5 parts by weight based on 100 parts by weight of the fluoropolymer.

1 . A balance-adjusting weight formed by using a crosslinked fluororubber product obtained by a method comprising the steps of:providing a fluororubber composition comprising:
 a peroxide-crosslinkable fluororubber comprising a terfluoropolymer;   barium sulfate;   a peroxide crosslinking agent; and   a quaternary ammonium salt represented by the formula;   
       
         
           
           
               
               
           
         
         wherein the barium sulfate is included in an amount of 130 to 150 parts by weight based on 100 parts by weight of the fluoropolymer; and 
         wherein the salt having BF 4   −  as a counter ion is included in an amount of 0.7 to 1.5 parts by weight based on 100 parts by weight of the fluoropolymer; and 
         subsequently heat-treating the resulting crosslinked fluororubber composition at a temperature ranging from 200 to 300° C. for 0.1 to 48 hours, to obtain a crosslinked product having a specific gravity of 2.2 to 2.8 and a breaking elongation (%) of 250% or more as measured according to JIS K6251. 
       
     
     
         2 . A balance-adjusting weight formed by using a crosslinked fluororubber product obtained by a method comprising the steps of:
 providing a fluororubber composition comprising:   a peroxide-crosslinkable fluororubber comprising a terfluoropolymer;   barium sulfate;   a peroxide crosslinking agent; and   a quaternary ammonium salt represented by the formula;   
       
         
           
           
               
               
           
         
         wherein the barium sulfate is included in an amount of 130 to 150 parts by weight based on 100 parts by weight of the fluoropolymer; and 
         wherein the salt having BF 4   −  as a counter ion is included in an amount of 0.7 to 1.5 parts by weight based on 100 parts by weight of the fluoropolymer; and 
         subsequently heat-treating the resulting crosslinked fluororubber composition at a temperature ranging from 200 to 300° C. for 0.1 to 48 hours, to obtain a crosslinked product having a specific gravity of 2.2 to 2.8 and a breaking elongation (%) is at least 250% and not more than 350% as measured according to JIS K6251.