GB817039A - New benzthiazolylsulphenimides and their use as vulcanisation accelerators - Google Patents

Abstract

Natural or synthetic rubbers are vulcanized after the incorporation of a N-tertiary-octyl-bis-(benzthiazolyl-2-sulphen)-imide, e.g. the 1,1,3,3-tetramethylbutyl compound, a delayed-action accelerator of vulcanization, useful particularly in preventing scorching of the vulcanizate. The sulphenimide may be incorporated in amounts of up to 10 per cent of the rubber, preferably 0.2-3.0 per cent. The vulcanization may be effected by known methods, e.g. by heating with sulphur at 140 DEG C. for 20-30 minutes. Specified synthetic rubbers are polymers of butadiene-1,3, iso-butene and 2-chlorobutadiene-1,3 and copolymers of these with acrylonitrile, styrene, and methyl methacrylate. The rubbers may also contain fillers, channel and furnace blacks, antioxidants and pigments. An example is of a natural rubber (smoked sheet) mix containing N-1,1,3,3-tetramethylbutyl-bis-(benzthiazolyl-2-sulphen)-imide, and the properties of the vulcanizate. According to the Provisional Specification, any N-tertiary-alkyl-bis-(benzthiazolyl-2-sulphen)-imide may be used, tertiary alkyl groups specified being the tertiary butyl, amyl and hexyl radicals, and tertiary cycloalkyl groups such as 1-methyl-cyclohexyl. The N-tertiary butyl compound is used in an additional example. This material does not appear in the accepted Complete Specification.ALSO:The invention comprises benzthiazolylsulphenimides of the formula <FORM:0817039/IV (b)/1> where R is a tertiary octyl radical, e.g. the 1,1,3,3-tetramethylbutyl group. The compounds may be prepared by reacting a benzthiazolyl-2-sulphenhalide, e.g. the chloride, with a tertiary octylamine in an inert substantially anhydrous organic solvent, e.g. carbon tetrachloride, chloroform, benzene, chlorobenzene, dichlorobenzene and dibutyl ether, preferably one boiling below about 100 DEG C. Suitable temperatures are from 0-75 DEG C., preferably 20-40 DEG C. An acid acceptor is preferably present e.g. pyridine, an alkyl pyridine, or triethylamine. The compounds of the invention may also be prepared by reading benzthiazolyl-2-sulphenchloride (which may be obtained by chlorination of the benzthiazolyl disulphide) with an N-tertiary-octyl-benzthiazolyl-2-sulphenamide in an inert substantially anhydrous solvent, preferably in the presence of an acid acceptor. In examples, the compound is prepared in which R is the 1,1,3,3-tetramethylbutyl group. The compounds are useful in vulcanizing rubber (see Group IV (a)). According to the Provisional Specification, the group R may be any tertiary alkyl group, including cycloalkyl radicals, such as the tertiary butyl, amyl and hexyl groups, and 1-methyl-cyclohexyl radicals. In an example the compound in which R is tertiary butyl is prepared. This material does not appear in the accepted Complete Specification.