Patent ID: 6916875

Claim:
A method for preparing a crosslinkable fluororubber composition comprising (A) 100 parts by weight of a liquid perfluoro compound having at least two alkenyl groups in the molecule and a divalent perfluoroalkylene or perfluoropolyether structure in the backbone, (B) 1 to 100 parts by weight of a reinforcing filler, (C) 0.01 to 30 parts by weight of a surface treating agent having at least one fluoroalkyl or fluoropolyalkyl ether group and at least one silanol group in the molecule, (D) a compound having at least two hydrosilyl groups in the molecule and capable of addition reaction, in such an amount as to give a molar ratio of hydrosilyl groups in component (D) to alkenyl groups in component (A) in the range of from 0.1 to 0.99, and (E) a sufficient amount to induce reaction of alkenyl groups in component (A) of a crosslinker having at least one hydrosilyl group in the molecule and capable of addition reaction or a peroxide crosslinker, said method comprising the steps of: (1) combining and mixing components (A) to (C) to form a liquid or paste composition, (2) adding component (D) to the liquid or paste composition for causing crosslinking to some alkenyl groups in the composition to form a millable composition, and (3) combining and mixing component (E) with the millable composition.