Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkage

Claim 1

A heat curable silicone rubber composition comprising a polymer system, said polymer system containing: (A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C. and substantially no vinyl, or mixtures of such organopolysiloxanes; (B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free to vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C., or mixtures of such organopolysiloxanes; (C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5×10 -3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C., or mixtures of such organopolysiloxanes; (D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5×10 -3 to about 5 weight percent, or mixtures of such organopolysiloxanes; (F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising: 1) R 3 SiO 1/2 units (M units) and SiO 2 units (Q units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free to aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R 3 SiO 1/2 units (M units), SiO 2 units (Q units) and R Vi 2 SiO 2/2 units (D vinyl units) where each R is as defined above and each R Vi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.5:1 to about 1.5:1, and the D vinyl units are present in an amount of from about 1 to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixtures of 1 and 2; such that the total of Components (A)-(D) and (F) equals 100 parts by weight, said silicone rubber composition further comprising: (G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m 2 /g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.45 and 1.0 micrometers; (H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent.

Claim 30

A method of improving oil resistance in a heat curable silicone rubber composition, said silicone rubber composition comprising a polymer system, said polymer system containing: (A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C. and substantially no vinyl, or mixtures of such organopolysiloxanes; (B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C., or mixtures of such organopolysiloxanes; (C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5×10 -3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C., or mixtures of such organopolysiloxanes; (D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5×10 -3 to about 5 weight percent, or mixtures of such organopolysiloxanes; (F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising: 1) R 3 SiO 1/2 units (M units) and SiO 2 units (Q units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free to aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R 3 SiO 1/2 units (M units), SiO 2 units (Q units) and R Vi 2 SiO 2/2 units (D vinyl units) where each R is as defined above and each R Vi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.5:1 to about 1.5:1, and the D vinyl units are present in an amount of from about 1 to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixtures of 1 and 2; such that the total of Components (A)-(D) and (F) equals 100 parts by weight, said silicone rubber composition further comprising: (H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent, said method comprising mixing with said silicone rubber composition (G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m 2 /g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers.

Claim 31

A method of improving oil resistance in a heat curable silicone rubber composition, said silicone rubber composition comprising a polymer system, said polymer system containing: (A) up to 100 parts by weight of an organopolysiloxane having a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C. and substantially no vinyl, or mixtures of such organopolysiloxanes; (B) up to 100 parts by weight of a vinyl-stopped organopolysiloxane, substantially free of vinyl-on-chain, having a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C., or mixtures of such organopolysiloxanes; (C) up to 100 parts by weight of a vinyl-on-chain organopolysiloxane, free of vinyl end stops, having a vinyl content of about 5×10 -3 to about 5 weight percent and a viscosity of about 3,000,000 to about 100,000,000 cps at 25° C., or mixtures of such organopolysiloxanes; (D) up to 100 parts of a vinyl-stopped, vinyl-on-chain organopolysiloxane having a vinyl content of about 5×10 -3 to about 5 weight percent, or mixtures of such organopolysiloxanes; (F) up to about 30 parts by weight based upon 100 parts of the total of Components (A)-(D) of an organopolysiloxane resin copolymer comprising: 1) R 3 SiO 1/2 units (M units) and SiO 2 units (Q units) where each R is independently selected from the group consisting of vinyl radicals and monovalent hydrocarbon radicals free to aliphatic unsaturation with a ratio of M units to Q units ranging from 0.5:1 to about 1.5:1, where the copolymer contains from about 0.5 to 10 weight percent vinyl groups, or 2) R 3 SiO 1/2 units (M units), SiO 2 units (Q units) and R Vi 2 SiO 2/2 units (D vinyl units) where each R is as defined above and each R Vi is a vinyl containing radical having from 2 to about 10 carbon atoms, and where the ratio of M units to Q units is from 0.5:1 to about 1.5:1, and the D vinyl units are present in an amount of from about 1 to about 70 mol percent based upon the total number of mols of siloxy units in the copolymer, and where the resinous copolymer contains from about 0.5 to about 10.0 weight percent vinyl groups, or 3) mixtures of 1 and 2; such that the total of Components (A)-(D) and (F) equals 100 parts by weight, said silicone rubber composition further comprising: (H) up to about 200 parts by weight based upon the polymer system of a finely divided filler; and (J) from about 0.1 to about 10 parts by weight based upon the polymer system of a hydride cross-linking agent, said method comprising mixing with said silicone rubber composition (G) from about 1 to about 50 parts by weight potassium aluminosilicate filler having a surface area of between about 5.0 and about 6.50 m 2 /g, an average particle diameter of between about 1.0 and about 20.0 micrometers and an average particle thickness of between about 0.5 and 1.0 micrometers.