Abstract: A curable composition comprising (1) at least one rubber selected from the group consisting of natural rubber, a diene rubber and a diene copolymer rubber, (2) a sulfide resin as a curing agent having the following general formula: ##STR1## wherein X is methylene group, ethylene group, --S-- or --S--S--, R.sup.1 and R.sup.2 are independently a C.sub.1-10 alkyl or alkylene group, Y.sup.1 and Y.sup.2 are independently the residue of a phenol compound, p is an integer of 2 to 8, and n is an integer of 2 to 5, (3) a phenolic thermosetting resin and (4) a hardener for hardening said thermosetting resin. The composition shows a low viscosity upon milling and also does not take place scorching and blooming, and can provide a cured rubber having a high dynamic modulus of elasticity with improved workability and processability. The cured rubber is suitable for use in radial tires as bead filler rubber.

Abstract: A curable composition comprising (1) at least one rubber selected from the group consisting of natural rubber, a diene rubber and a diene copolymer rubber, (2) a sulfide resin as a curing agent having the following general formula: ##STR1## wherein X is methylene group, ethylene group, --S-- or --S--S--, R.sup.1 and R.sup.2 are independently a C.sub.1-10 alkyl or alkylene group, Y.sup.1 and Y.sup.2 are independently the residue of a phenol compound, p is an integer of 2 to 8, and n is an integer of 2 to 5, (3) a phenolic thermosetting resin and (4) a hardener for hardening said thermosetting resin. The composition shows a low viscosity upon milling and also does not take place scorching and blooming, and can provide a cured rubber having a high dynamic modulus of elasticity with improved workability and processability. The cured rubber is suitable for use in radial tires as bead filler rubber.