Process for curing tire employing a bladder lubricant

Claim 1

A method of molding and vulcanizing an unvulcanized rubber product by using a curing bladder, wherein said curing bladder is treated at the surface thereof with a silicone composition, said method comprising the steps of: applying said silicone composition to the surface of said curing bladder; placing an unvulcanized rubber product into a mold; conforming said unvulcanized rubber product to an internal surface of said mold by internally pressurizing said curing bladder into contact with a surface of said vulcanized rubber product; applying heat and curing said unvulcanized rubber product to form a vulcanized rubber product having a predetermined shape dictated by said mold; the improvement comprising applying said silicone composition comprising: (a) 100 parts by weight of a polyorganosiloxane having a viscosity at 25° C. of from 3,000 to 5,000,000 cst, said polyorganosiloxane having organic groups bonded to the silicon atoms of said polyorganosiloxane, said organic groups being selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, vinylphenyl, β-phenylethyl, β-phenylpropyl, chloromethyl, chlorophenyl and 3,3,3-trifluoropropyl, and wherein more than 90 mol % of said organic groups are methyl; (b) from 30 to 300 parts by weight of a polymethylhydrogensiloxane having a viscosity at 25° C. of from 10 to 70 cst; (c) from 2 to 25 parts by weight of finely powderous silica, and (d) from 0 to 30 parts by weight of an organic acid salt of one or more metals selected from the group consisting of zinc, magnesium, manganese and cobalt, and wherein said polyorganosiloxane (a) and said polymethylhydrogensiloxane (b) make up the silicone component of said silicone composition; and, the improvement further comprising the steps of said method being executed successively for more than 40 of said vulcanized rubber products without reapplication of said silicone composition to said surface of said curing bladder.

Claim 2

A method of molding and vulcanizing an unvulcanized rubber product by using a curing bladder, wherein said curing bladder is treated at the surface thereof with a silicone composition, said method comprising the steps of: applying said silicone composition to the surface of said curing bladder; placing an unvulcanized rubber product into a mold; conforming said unvulcanized rubber product to an internal surface of said mold by internally pressurizing said curing bladder into contact with a surface of said vulcanized rubber product; applying heat and curing said unvulcanized rubber product to form a vulcanized rubber product having a predetermined shape dictated by said mold; the improvement comprising applying said silicone composition comprising: (a) 100 parts by weight of a polyorganosiloxane having a viscosity at 25° C. of from 3,000 to 5,000,000 cst, said polyorganosiloxane having organic groups bonded to the silicon atoms of said polyorganosiloxane, said organic groups being selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, vinylphenyl, β-phenylethyl, β-phenylpropyl, chloromethyl, chlorophenyl and 3,3,3-trifluoropropyl, and wherein more than 90 mol % of said organic groups are methyl; (b) from 30 to 300 parts by weight of a polymethylhydrogensiloxane having a viscosity at 25° C. of from 10 to 70 cst; (c) from 2 to 25 parts by weight of finely powderous silica, and (d) from 0 to 30 parts by weight of an organic acid salt of one or more metals selected from the group consisting of zinc, magnesium, manganese and cobalt, and wherein said polyorganosiloxane (a) and said polymethylhydrogensiloxane (b) make up the silicone component of said silicone composition; and, the improvement further comprising the steps of said method being executed successively for more than 40 of said vulcanized rubber products without reapplication of said silicone composition to said surface of said curing bladder.