Curable polymer latex compositions for the manufacture of rubber articles

A method for making a curable polymer latex composition, the method comprising:

• (a) subjecting a monomer mixture comprising:
• i. at least one conjugated diene;
• ii. at least one ethylenically unsaturated nitrile;
• iii. optionally at least one ethylenically unsaturated acid;
• iv. optionally at least one further ethylenically unsaturated compound different from any of the compounds (i)-(iii);
• to free-radical emulsion polymerization in an aqueous reaction medium to form a raw polymer latex,
• (b) adding at least one thiocarbonyl-functional compound to the raw polymer latex after termination of the polymerization reaction, and allowing the raw polymer latex to mature in the presence of the at least one thiocarbonyl-functional compound at a temperature of at least 35° C., wherein the at least one thiocarbonyl-functional compound is present in an amount of at least 0.05 wt.-%, based on total amount of monomers subjected to the free-radical emulsion polymerization in step (a), and
• (c) optionally compounding the matured polymer latex with one or more cross-linking agent.