High-modulus rubber composition for pneumatic tires

Abstract

A tire designed for operation both as a pneumatic tire under ordinary conditions, and also without inflation under emergency conditions, has thick sidewalls made of low-hysteresis high-modulus vulcanized natural rubber composition containing reinforcing carbon black and also containing an effective anti-oxidant, together with a cobalt soap to prevent reduction in modulus during service of the tire.

I claim: 
     
       1. A .Iadd. tire with a sidewall comparable in thickness to the tread, which sidewall in a major part of its thickness is made of a .Iaddend.high-modulus, low-hysteresis, stable, vulcanized, tire composition consisting essentially of vulcanized cis-polyisoprene rubber containing a high-modulus carbon black, about 4 to 8 parts, per hundred of rubber, of an active cobalt compound, and an effective quantity of an efficient antioxidant. 
     
     
       2. A tire .[.composition.]. as in claim 1, in which the cobalt compound is a cobalt soap of a fatty acid. 
     
     
       3. A tire .[.composition.]. as in claim 2, in which the cobalt compound is cobalt stearate. 
     
     
       4. A tire .[.composition.]. as in claim 1, in which the carbon black is superior processing furnace black. 
     
     
       5. A tire .[.composition.]. as in claim 1, in which the antioxidant includes an N-substituted p-phenylene diamine. 
     
     
       6. A tire .[.composition.]. as in claim 1, including a heat setting phenolic resin. 
     
     
       7. A tire .[.composition.]. as in claim 6, in which the phenolic resin is a resorcinol formaldehyde resin. 
     
     
       8. A tire .[.composition.]. as in claim 7, in which the cobalt compound is cobalt stearate and the antioxidant includes an N-substituted p-phenylene diamine. 
     
     
       9. A tire .[.composition.]. as in claim 8, in which the major part of the cis-polyisoprene is natural rubber. .[.10. A tire with a sidewall comparable in thickness to the tread, which sidewall consists of the composition defined in claim 1..]. .[.11. A tire with a sidewall comparable in thickness to the tread, which sidewall consists of the 
     
     
        composition defined in claim 9..]. 12. A tire as in claim .[.11.]. .Iadd.9 .Iaddend.containing a ply of reinforcing cords, in which the major part of the thickness of the middle zone of the sidewall is between the reinforcing cord ply and the inner surface of the tire.