Patent ID: 7087338

Claim:
A polymer electrolyte fuel-cell separator comprising: a metal thin plate or a substrate comprising an electrically conductive powder and a binder; and a seal member formed along a periphery on at least one side of the plate or substrate by applying along said periphery on at least one side of said plate or substrate a rubber composition comprising, in parts by weight, (A) 70 to 95 parts of an organopolysiloxane which is blocked at either end of the molecular chain with a radical independently selected from the group consisting of alkenyldialkylsiloxy, dialkenylalkylsiloxy and trialkenylsiloxy radicals, and which does not contain an aliphatic unsaturated monovalent hydrocarbon radical attached to a silicon atom on any molecular side chain, (B) 5 to 30 parts of an organopolysiloxane containing at least three alkenyl radicals each attached to a silicon atom on molecular side chains per molecule, (C) 0.5 to 20 parts, per 100 parts of components (A) and (B) combined, of an organohydrogenpolysiloxane having at least three hydrogen atoms each attached to a silicon atom per molecule, (D) 10 to 40 parts, per 100 parts of components (A) and (B) combined, of fumed silica having a specific surface area of 50 to 400 m 2 / g, and (E) a catalytic amount of an addition reaction catalyst, by a compression molding, casting, injection molding, transfer molding, dipping, coating or screen printing technique, and curing said composition on said periphery on at least one side of said plate or substrate.