GB839394A - Improvements in a tubeless pneumatic tyre or other laminated article comprising a natural rubber layer bonded to a synthetic rubber layer - Google Patents

Abstract

<PICT:0839394/IV (a)/1> In a composite rubber article, e.g. a tubeless pneumatic tyre, comprising laminated vulcanized rubber material, a layer 8 comprises vulcanized natural rubber and is vulcanized to a second layer, e.g. a liner member 7, comprising a chlorinated copolymer of a major portion of an iso-olefin having 4 to 8 carbon atoms and a minor portion of a diolefin having 4 to 7 carbon atoms, and at least one of the layers 7, 8, preferably the layer 8, contains silica. The liner 7 is adhered by the layer 8 to a fabric reinforced portion 2 which terminates in beads 3, 4. The layer 8 may contain 20 to 60 parts by weight of silica per 100 parts of natural rubber, and may be applied to the portion 2 either as a calendered sheet or as an adhesive solution prepared by dissolving 100 parts natural rubber, 33 parts hydrated silica, 25 parts carbon black, and vulcanizing and other compounding ingredients in gasolene, toluene, xylene, or other rubber solvent. Measurement tests are described of the adhesion between a calendered sheet of the natural rubber composition of layer 8, and a composition comprising 20 parts natural rubber, 80 parts chlorinated copolymer, 40 parts carbon black, and vulcanizing and other compounding ingredients. The chlorinated copolymer may be prepared by co-polymerizing 70 to 99 parts by weight of isobutylene and 30 to 1 parts butadiene or isoprene, and chlorinating the resulting copolymer by mixing with a chlorinating agent such as dichlorodimethyl hydantoin on a two roll mill.