Process for the preparation of a masterbatch rubber having polymer bound functionality

The present invention relates to a process for preparing a masterbatch rubber containing polymer bound functionalized moieties. The process comprises the emulsion polymerization at a temperature from 40 degrees C. to 100 degrees C. of (a) at least one functionalized monomer that contains a polymerizable vinyl group; with (b) at least one copolymerizable conjugated diene monomer selected from the group consisting of butadiene-1,3,2 chlorobutadiene-1,3, isoprene, piperylene and conjugated hexadienes, wherein the polymerization is conducted in the presence of from (1) from 2 to 30 parts by weight of an ionic surfactant per 100 parts by weight of organic components and (2) about 10 to about 70 parts by weight of a plasticizer based on 100 parts by weight of total monomers. Other than the water, ionic surfactant, and the copolymerizable conjugated diene, the plasticizer functions as the sole solvent for the functionalized monomer during the emulsion polymerization and additionally functions as a plasticizer for the final polymer product.