초록 ▼

A sealant composition particularly suitable for vehicle tires comprising a cured butyl rubber present only in the form of a copolymer having a molecular weight in excess of 100,000 and one or more tackifiers, the tensile strength, elongation and cross-link density of the composition being adjusted t

A sealant composition particularly suitable for vehicle tires comprising a cured butyl rubber present only in the form of a copolymer having a molecular weight in excess of 100,000 and one or more tackifiers, the tensile strength, elongation and cross-link density of the composition being adjusted to produce the necessary properties for tire sealants.

대표청구항 ▼

1. A butyl rubber-based sealant composition, the butyl rubber constituent of which is present only in the form of a copolymer having a viscosity average molecular weight in excess of 100,000, comprising the reaction product of said butyl rubber, a quinoid cross-linking agent and a cross-linking acti

1. A butyl rubber-based sealant composition, the butyl rubber constituent of which is present only in the form of a copolymer having a viscosity average molecular weight in excess of 100,000, comprising the reaction product of said butyl rubber, a quinoid cross-linking agent and a cross-linking activator present in an amount sufficient to initiate a reaction between the butyl rubber and the cross-linking agent, and further including at least 1% by weight of zinc oxide, a sulfur constituent present in an amount equivalent to at least 0.5 parts of sulfur per hundred parts butyl rubber, and at least one tackifier compatible with butyl rubber, said butyl rubber comprising 13--30% by weight of the composition exclusive of the cross-linking system and sulfur constituent, such sealant composition being characterized in that, when applied to the interior surface of a tire in a layer at least 0.15 inches thick the tensile strength, elongation and cross-link density of the composition are such that the composition will bridge up to a 0.203 inch hole in a tire inflated to 32 psig at ambient temperature, adhere to a 0.18 inch diameter nail inserted through the tire and sealant layer with the nail being swung through a 90° arc, maintain an air seal about the hole caused by such nail both before and after the nail is withdrawn from the tire, and remain in a non-flow condition at temperatures up to 220° F., under forces encountered during normal tire usage. 2. The sealant composition of claim 1 wherein the sulfurous stabilizing constituent is sulfur present in an amount not less than 1 part per hundred parts butyl rubber. 3. The sealant composition of claim 1 further comprising a second sulfur constituent. 4. The sealant composition of claim 1 wherein the cross-linking activator comprises a first oxidizing agent of greater activity in initiating cross-linking of the butyl rubber and a second oxidizing agent of lesser activity, the relative concentrations of the first and second oxidizing agents being adjusted to control the curing of the sealant composition. 5. The sealant composition of claim 4 wherein the first oxidizing agent is benzoyl peroxide and the second oxidizing agent is t-butyl perbenzoate. 6. A butyl rubber-based sealant composition, the butyl rubber constituent of which is present only in the form of a copolymer having a viscosity average molecular weight in excess of 100,000 comprising the reaction product of said butyl rubber, a curing system for the butyl rubber selected from the group consisting of phenolic resin and quinoid curing systems, and further including at least 1% by weight of zinc oxide, a sulfur constituent present in an amount equivalent to at least 0.5 parts of sulfur by weight per 100 parts butyl rubber, and at least one tackifier compatible with butyl rubber, said butyl rubber comprising 13-40% by weight of the composition exclusive of the cross-linking system and sulfur constituent said sealant composition being compounded such that it has a tensile strength of at least 30 psi, an elongation of at least 600% and a cross-link density such that its swell ratio in toluene is between 12 and 40. 7. The sealant composition of claim 6 wherein the sulfurous stabilizing constituent is sulfur present in an amount not less than 1 part per hundred parts butyl rubber. 8. The sealant composition of claim 6 further comprising a second sulfur constituent. 9. The sealant composition of claim 6 wherein the curing system is a quinoid curing system comprising a quinoid cross-linking agent and a cross-linking activator and wherein the cross-linking activator comprises a first oxidizing agent of greater activity in initiating cross-linking of the butyl rubber and a second oxidizing agent of lesser activity, the relative concentrations of the first and second oxidizing agents being adjusted to control the curing of the sealant composition. 10. The sealant composition of claim 9 wherein the first oxidizing agent is benzoyl peroxide and the second oxidizing agent is t-butyl perbenzoate. 11. A butyl rubber based sealant composition, the butyl rubber constituent of which is present only in the form of a copolymer having a viscosity average molecular weight in excess of 100,000, comprising the reaction product of said butyl rubber, a quinoid cross-linking agent, a cross-linking activator present in an amount sufficient to initiate a reaction between the cross-linking agents and the butyl rubber, at least two parts by weight carbon black per hundred parts butyl rubber at least one tackifier compatible with butyl rubber, and further including at least 1% by weight of zinc oxide, a sulfur constituent present in an amount equivalent to at least 0.5 parts of sulfur per hundred parts butyl rubber, said butyl rubber comprising 13-40% by weight of the composition exclusive of the cross-linking agent, activator and sulfur constituent, said reaction product being formed such that the sulfur constituent is not appreciably consumed in the cross-linking of the butyl rubber. 12. The sealant composition of claim 11 wherein the sulfur constituent is sulfur present in an amount not less than 1 part per hundred parts butyl rubber. 13. The sealant composition of claim 11 further comprising a second sulfur constituent. 14. The sealant composition of claim 11 wherein the cross-linking activator comprises first and second oxidizing agent of greater activity in initiating cross-linking of the butyl rubber and a second oxidizing agent of lesser activity, the relative concentrations of the first and second oxidizing agents being adjusted to control the curing of the sealant composition. 15. The sealant composition of claim 14 wherein the first oxidizing agent is benzoyl peroxide and the second oxidizing agent is t-butyl perbenzoate. 16. A butyl rubber based sealant composition the butyl rubber constituent of which is present only in the form of copolymers having a viscosity average molecular weight in excess of 100,000, comprising the reaction product of said butyl rubber with a curing system, said curing system being selected from the group consisting of quinoid cross-linking systems and phenolic resin curing systems, a tackifier compatible with the butyl rubber, at least 1% by weight of zinc oxide, a first sulfur constituent present in an amount of at least 0.5 parts per hundred parts of butyl rubber and a second sulfur constituent present in an amount of at least 0.5 parts per hundred parts of butyl rubber, said first and second sulfur constituents being present in an amount less than that which results in migration of sulfur to the surface of the composition, said sealant composition being prepared and cured such that substantially all of the cross-linking of the butyl rubber is accomplished by said curing system said sealant composition being compounded such that it has a tensile strength of at least 30 psi, an elongation of at least 600% and a cross-link density such that its swell ratio in toluene is between 12 and 40. 17. The sealant composition of claim 16 wherein said first sulfur constituent comprises sulfur. 18. The sealant composition of claim 17 wherein said second sulfur constituent is selected from the group consisting of benzothiazyl disulfide, mercaptobenzothiazole and its derivatives and salts, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, zinc dibutyldithiocarbamate, tellurium diethyldithiocarbamate, dipentamethylene thiuram tetrasulfide, thioureas, aminodisulfides, tetramethylthiuram trisulfide and polysulfide, polymeric alkylphenol sulfides of a sulfur rank greater than 3, alkyl and aryl polysulfides of sulfur rank greater than or equal to 3, and other vulcanization accelerators and materials which provide sulfur either by themselves or through interaction with other materials. 19. The sealant composition of claim 16 wherein the curing system includes first and second cross-linking activators for activating said cross-linking agent to cross-link said butyl rubber, the first activator having an activity to promote cross-linking of the butyl rubber which is greater than the activity of the second activator whereby the gel time and curing time of the sealant may be controlled. 20. The sealant composition of claim 19 wherein the first activator comprises benzoyl peroxide and the second activator comprises t-butyl perbenzoate. 21. The sealant composition of claim 17 wherein the curing system is a quinoid curing system and wherein said sealant composition includes at least two parts of carbon black per hundred parts butyl rubber. 22. The sealant composition of claim 16 wherein said first and second sulfur constituents are selected from the group consisting of sulfur, benzothiazyl disulfide, mercaptobenzothiazole and its derivatives and salts, tetraethylthiuram disulfide, tetraethylthiuram monosulfide, zinc dibutyldithiocarbamate, tellurium diethyldithiocarbamate, dipentamethylene thiuram tetrasulfide, thioureas, aminodisulfides, tetramethylthiuram trisulfide and polysulfide, polymeric alkylphenol sulfides of a sulfur rank greater than 3, alkyl and aryl polysulfides of sulfur rank greater than or equal to 3, and other vulcanization accelerators and materials which provide sulfur either by themselves or through interaction with other materials. 23. The sealant composition of claim 22 wherein said zinc oxide is present in an amount equivalent to 0.5 parts of sulfur per hundred parts butyl rubber, the quantity of said first sulfur constituent being adjusted to account for differences in molecular weight between such constituent and sulfur, and for the number of sulfur bearing functional groups per molecule. 24. The sealant composition of claim 17 wherein the sulfur is present in an amount between 1. 5 and 3.0 parts per hundred parts butyl rubber. 25. A butyl rubber based sealant composition the butyl rubber constituent of which is present only in the form of copolymers having a viscosity average molecular weight in excess of 100,000, comprising the reaction product of said butyl rubber with a curing system, said curing system being selected from the group consisting of quinoid curing systems and phenolic resin curing systems, a tackifier compatible with the butyl rubber, at least 1% by weight zinc oxide, and a sulfur constituent present in an amount equivalent to between about 1.5-3.0 parts of sulfur per hundred parts butyl rubber, said sealant composition being prepared and cured such that substantially all of the cross-linking of the butyl rubber is accomplished by the curing system selected from said group, said sealant composition being compounded such that it has a tensile strength of at least 30 psi, an elongation of at least 600% and a cross-link density such that its swell ratio in toluene is between 12 and 40. 26. The sealant composition of claim 25 wherein said zinc oxide is present in an amount not less than 1% by weight of said sealant composition. 27. The sealant composition of claim 26 wherein said sulfur constituent is chosen from the group consisting of sulfur, benzothiazyl disulfide, mercaptobenzothiazole and its derivatives and salts, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, zinc dibutyldithiocarbamate, tellurium diethyldithiocarbamate, dipentamethylene thiuram tetrasulfide, thioureas, aminodisulfides, tetramethylthiuram trisulfide and polysulfide, polymeric alkylphenol sulfides of a sulfur rank greater than 3, alkyl and aryl polysulfides of sulfur rank greater than or equal to 3, and other vulcanization accelerators and materials which provide sulfur either by themselves or through interaction with other materials. 28. The sealant composition of claim 27 further comprising a second sulfur constituent. 29. The sealant composition of claim 28 wherein said second sulfur constituent is selected from the group consisting of sulfur, benzothiazyl disulfide, mercaptobenzothiazole and its derivatives and salts, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, zinc dibutyldithiocarbamate, tellurium diethyldithiocarbamate, dipentamethylene thiuram tetrasulfide, thioureas, aminodisulfides, tetramethylthiuram trisulfide and polysulfide, polymeric alkylphenol sulfides of a sulfur rank greater than 3, alkyl and aryl polysulfides of sulfur rank greater than or equal to 3, and other vulcanization accelerators and materials which provide sulfur either by themselves or through interaction with other materials. 30. The sealant composition of claim 25 wherein said curing system is a quinoid curing system and wherein said sealant composition includes at least two parts carbon black per hundred parts butyl rubber.