Cold vulcanising repair patches or plasters

摘要

A multi-layer cold vulcanizing dry repair patch or plaster, for repairing rubber tyres, tubes, conveyer belts &c. without the prior application of rubber solution, comprises a main body of vulcanized rubber with or without reinforcing cord inserts, and a connecting layer which consists of a mixture of vulcanizable unvulanized natural and synthetic rubbers containing as accelerator a dry double salt of dithiocarbamates and organic alkali; and containing also as a preserving agent phenolformaldehyde condensation products. The synthetic rubber may be copolymers based on poly-, polychloro-, or polymethyl-butylene, or butyl rubber, used in the proportion 1 to 40% by weight of the natural rubber, the preferred synthetic rubber being capable of crystallizing. The preferred accelerator is a double salt of zinc ethylphenyldithiocarbamate and cyclohexylethylamine in the proportion 15 to 50% by weight of natural rubber. The preserving agent may comprise aromatic hydroxyl compounds such as phenol, cresols and diphenylolpropane of the resol or resitol classes, preferably phenol or cresol resin modified with a terpene having at least ten carbon atoms, used in the proportion of 2 to 10% by weight of natural rubber. The connecting layer may be strengthened by the addition of 0,5 to 4% silicic acid fillers by weight of natural rubber possibly together with 2 to 5% of zinc oxide. To ensure adhesion between the main body and the connecting layer, a securing layer may be interprsed comprising unvulcanized rubber containing 0,2 to 2% of tetramethythiuram disulphide by weight of natural rubber.