Silica-reinforced rubber compounded with an organosilane tetrasulfide silica coupling agent at high mixing temperature
AssigneeBridgestone Corporation
InventorsChenchy Jeffrey Lin, William L. Hergenrother, Ashley S. Hilton
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Abstract
Sulfur-vulcanizable elastomeric compounds and pneumatic tire components having improved tensile mechanical and dynamic viscoelastic properties are produced by compounding polymers with silica at a temperature of 165° C. to about 200° C., in the presence of a silica dispersing agent, and a very small amount (e.g., about 0.01% to about 1% by weight, based on the weight of the silica) of a bis(trialkoxysilylorgano) tetrasulfide silica coupling agent.
Claims20
A sulfur-vulcanized elastomeric compound produced by a process comprising the steps of:
- (a) mixing together at a temperature of 165° C. to about 200° C. in the absence of cure agents, an elastomer optionally having an alkoxysilane terminal group, a reinforcing filler comprising silica or a mixture thereof with carbon black, about 0.01% to about 1% by weight, based on the weight of the silica, of a bis(trikoxysilylorgano) tetrasulfide silica coupling agent, and a silica dispersing aid;
- (b) allowing the mixture to cool below the mixing temperature;
- (c) mixing the mixture obtained in step (b), at a temperature lower than a vulcanization temperature, with a cure agent comprising an effective amount of sulfur to achieve a satisfactory cure;
- and
- (d) curing the mixture obtained in step (c).
A pneumatic tire comprising a component produced from a sulfur-vulcanized elastomeric compound, wherein the compound comprises an elastomer optionally having an alkoxysilane terminal group, a reinforcing filler comprising silica or a mixture thereof with carbon black, about 0.01% to about 1% by weight of a bis(trialkoxysilylorgano) tetrasulfide silica coupling agent based on the weight of the silica, a silica dispersing aid, and a cure agent comprising an effective amount of sulfur to achieve a satisfactory cure,
- wherein the compound is formed by mixing together the elastomer, the silica, the silica coupling agent and the silica dispersing aid, in the absence of the cure agent, at a temperature of 165° C. to about 200° C., wherein the compound exhibits about a 10% to about a 50% decrease in filler flocculation after compounding, as measured by ΔG′, or reduced hysteresis as measured by about a 5% to about a 20% decrease in tangent δ at 65° C., compared to a similar compound in which a conventional amount of the bis(trialkoxysilylorgano) tetrasulfide silica coupling agent is mixed with the silica, in the absence of the cure agent, at a temperature of 160° C. or less.
A method for preparing a sulfur-vulcanized elastomeric compound, comprising the steps of:
- (a) mixing together at a temperature of 165° C. to about 200° C. in the absence of added sulfur and cure agents, an elastomer optionally having an alkoxysilane terminal group, a reinforcing filler comprising silica or a mixture thereof with carbon black, about 0.01% to about 1% by weight of a bis(trialkoxysilylorgano) tetrasulfide silica coupling agent, based on the weight of the silica, and a silica dispersing aid;
- (b) allowing the mixture to cool below the mixing temperature;
- (c) mixing the mixture obtained in step (b), at a temperature lower than a vulcanization temperature, with a cure agent and an effective amount of sulfur to achieve a satisfactory cure;
- and
- (d) curing the mixture obtained in step (c).
Dependencies are inferred from the claim text.