GB177493A - Improvements in processes for vulcanizing rubber and products obtained thereby - Google Patents

Abstract

177,493. Cadwell, S. M. March 25, 1921, [Convention date]. Vulcanizating-compositions.-The vulcanization of rubber &c. is accelerated bv the addition of a substance containing the radical R-#C-S-M where M represents a salt-forming element or group or hydrogen, or a radical S-#C-R, or a radical #C-R, X represents a bivalent element or radical, and R represents any element except nitrogen, this exception however being absent when M represents #C-R. Numerous substances falling within this category are specified. For vulcanizing at ordinary temperatures with substances in which M represents a metal the preferred metals are zinc and mercury; at higher temperatures, the preferred metals are zinc, mercury, lead, cadmium, copper, arsenic, manganese. If other metals be employed one of these metals should be present in the mixing in some form. Bases, as sodium hydroxide accelerate the action of these substances. Amines may also be added, the greatest effect in the case of aliphatic amines being produced when a half molecular weight of amine on the basis of the carbon bisulphide content of the thiol salt is used. An excess of aliphatic amine tends to retard vulcanization. The greater the amount of primary aromatic amine, the greater the acceleration. In an example, 100 parts of rubber, 10 parts of zinc oxide, 4 parts of zinc butyl xanthogenate, 1 part of sulphur, and 2 parts of toluidine is mixed as usual and allowed to stand for several days. For a cement, 100 parts of rubber, 10 parts of zinc oxide, and 6 parts of zinc butyl xanthogenate are mixed with 800 parts of benzol: and 100 parts of rubber, 10 parts of zinc oxide, 6 parts of sulphur and 6 parts of paratoluidine are mixed with 800 parts of benzol. On mixing these solutions in equal proportions, rubber is obtained which vulcanizes in 24-48 hours at room temperature, or more quickly at higher temperature- With substances in which M represents S-#C-R, the time of vulcanization is generally longer, and there is less danger of prevulcanization in the mill. As an example, 100 parts of rubber, 10 parts of zinc oxide, 3 parts of sulphur, and 2 parts of o normal butyl thiocarbonic acid disulphide are mixed and vulcanized in 10 minutes at steam pressure of 401b. per sq. in. Substances in which M represents #C-R are specially adapted for hot vulcanization, and there is no tendency to prevulcanization. In an example, 100 parts of rubber, 10 parts of zinc oxide, 3 parts of sulphur and 1-10th part of diphenyldimethylthiuram sulphide are mixed as usual and vulcanized in 10 minutes at 40lb. steam pressure.