GB923080A - Improvements in or relating to rubber threads - Google Patents

Abstract

Textile threads of a rubber cured with a peroxide curing agent and in the absence of sulphur-containing curing agents in amount corresponding to more than 0,02% of available sulphur, based on the weight of the rubber, do not give rise to discolouration in associated threads of, for example, nylon or regenerated cellulose threads, particularly when articles containing both types of threads are treated with water containing copper. Natural rubber, synthetic rubbers such as butadiene/styrene, butadiene/methyl methacrylate, butadiene/acrylonitrile and chloroprene-based rubbers, rubbery olefine copolymers, e.g. ethylene/propylene copolymers, blends of natural and a synthetic rubber or of two synthetic rubbers, and polymers of partly natural and partly synthetic rubber obtained from natural rubber by graft polymerization are specified. Peroxide curing agents mentioned are dicumyl peroxide in amount 2,5-6,25% of the weight of the rubber (preferred), di-isopropyl, di-t-butyl and di-benzoyl peroxides, cumyl and t-butyl hydroperoxides and peresters such as t-butyl perbenzoate. The rubber composition from which the threads are made may contain lime as a mild accelerator, whiting to increase the modulus or massaged modulus, zinc oxide to increase tenacity, pigments, e.g. titanium dioxide, and antioxidants such as 2,21-methylene-bis(4-ethyl-6-tertiary butyl phenol) and sym-dibeta-naphthylparaphenylene diamine. The peroxide curing agent may be compounded in association with a carrier such as precipitated calcium carbonate, or absorbant, e.g. a suitable Zeolite. According to an example, threads formed from a composition consisting of 100 parts crepe rubber, 2,5 parts dicumyl peroxide deposited on precipitated calcium carbonate, 10 parts whiting, 2 parts lime, 6 parts titanium dioxide, 1 part sym-dibetanaphthylparaphenylene diamine and 0,125 part of Ultramarine Blue were cured at 287 DEG F. for about 2 hours.