Abstract: A rubber composition for coating steel cords, comprising a raw material rubber and, compounded therein, a methylolmelamine derivative and a product of a reaction of a cobalt salt of an organic acid with a metaboric acid ester, and a rubber product reinforced with rubber-coated steel cords comprising steel cords coated with the rubber composition.

Abstract: A promoter for bonding between a rubber and a steel cord, which is represented by the following general formula (I): ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 may be the same or different from one another and each represents a monocarboxylic radical bonded to the adjacent Co atom through the oxygen atom which is adjacent to the carbonyl group in said monocarboxylic radical; a rubber composition containing the bonding promoter, and rubber products made from the rubber composition.

Abstract: A rubber-steel cord adhesion promoter represented by the general formula ##STR1## wherein Y.sub.1, Y.sub.2 and Y.sub.3 are identical or different and each represents a resin acid radical, a naphthenic acid radical or an aliphatic monocarboxylic acid radical having 7 to 24 carbon atoms provided that Y.sub.1, Y.sub.2 and Y.sub.3 are not simultaneously aliphatic monocarboxylic acid radicals having 7 to 15, particularly 7 to 11, carbon atoms. The promoter aids in imparting a high rubber-to-steel cord adhesive strength which is retained for an extended period of time even at high temperature and humidity.