Article of manufacture and rubber composition containing bismaleimide

A method of reducing copper-sulfide formation in an article of manufacture comprising:

• providing a brass-plated reinforcement cord;
• providing a rubber composition comprising
• (1) from 70 to 100 phr of at least one polyisoprene rubber selected from the group consisting of natural rubber or synthetic polyisoprene;
• (2) from 0 to 30 phr of at least one additional rubber selected from the group consisting of polybutadiene and styrene-butadiene rubber;
• (3) from 20 to 80 phr of carbon black;
• (4) from 2 to 10 phr of silica;
• (5) from 1 to 8 phr of sulfur;
• and
• (6) from 0.5 to 5 phr of N, N′-m-phenylene bismaleimide,
• wherein the rubber composition is essentially free of cobalt;
• applying the rubber composition to the brass-plated reinforcement cord;
• curing the rubber composition on the brass-plated reinforcement cord;
• wherein an atomic ratio of sulfur to copper on at an interface of the rubber and the brass-plated reinforcement cord is less than about 0.1.

A rubber composition embedding a brass-coated steel cord-reinforced component of a pneumatic tire, the rubber composition comprising:

• a vulcanizable rubber matrix;
• and
• N,N′-m-phenylene bismaleimide in an amount effective to inhibit copper sulfide overgrowth at a brass/rubber interface under tire aging conditions by limiting sulfur availability for sulfidation;
• wherein the composition is free of cobalt salts.