Emulsion polymerization in the presence of lignosulfonate salt

An emulsion polymerization process for preparing a rubber latex comprising agitating, at a temperature of from 5.degree. to 80.degree. C, a mixture of water and monomeric material selected from conjugated dienes with or without at least one copolymerizable monoethylenically unsaturated monomer, in the presence of an emulsion polymerization catalyst for said monomeric material in an amount effective to catalyze the polymerization of said monomeric material, and in the presence of from 0.1 to 6 parts, per 100 parts by weight of said monomeric material, of a water-soluble lignosulfonate salt as an emulsion modifier, and from 0.1 to 3 parts, per 100 parts by weight of said monomeric material, of a different anionic principal emulsifying agent, resulting in a stable rubber latex having a particle size of from 500 to 5,000 Angstroms average diameter as determined by turbidity measurement.

An emulsion polymerization process for preparing a rubber latex comprising agitating, at a temperature of from 5.degree. to 80.degree. C, a mixture of water and monomeric material comprising a conjugated diene, a copolymerizable vinyl aryl monomer and a copolymerizable monoethylenically unsaturated carboxylic acid, at a pH of 2 to 3.5, in the presence of an emulsion polymerization catalyst for said monomeric material in an amount effective to catalyze the polymerization of said monomeric material, and in the presence of from 0.2 to 5 parts, per 100 parts by weight of said monomeric material, of a water-soluble lignosulfonate alkali metal or alkaline earth metal salt as an emulsion polymerization modifier and from 0.5 to 1.5 parts, per 100 parts by weight of said monomers, of a different anionic principal emulsifying agent, resulting in a stable rubber latex having a particle size of from 1,000 to 3,000 Angstroms average diameter as determined by turbidity measurement.