Mineral-filled elastomer compositions

A process for the preparation of a rubber composition consisting essentially of the steps of:

• A) thermomechanically mixing in a first pass:
• 1) at least one sulfur vulcanizable rubber;
• 2) at least one latent mercaptosilane coupling agent;
• 3) at least one filler;
• and
• 4) at least one additional mercaptan, said additional mercaptan being a mercaptosilane selected from the group consisting of compounds of the structure
• (HS—)rG(—SiX3)t;
• B) bringing the temperature of the first pass mix from about 140° C. to about 200° C. over a period of 1 to 20 minutes;
• thereby forming a nonproductive first mixture;
• C) thermomechanically mixing the nonproductive first mixture in a second pass, optionally in the presence of at least one curing agent, at a temperature of from about 25 to about 100° C. for a period of from about 1 to about 30 minutes;
• thereby forming a productive second mixture;
• D) adding at least one latent-mercaptosilane activator in step A), step C), or both step A) and step C);
• E) shaping the second mixture;
• and then
• F) curing the second mixture at a temperature between about 130° C. to about 200° C. for a period of from about 5 to about 60 minutes.