| abstract |
A process for emulsion polymerization to form a latex having a particle size greater than about 0.5 micrometers by charging to a reaction vessel under agitation a reaction mixture including water, emulsifiers at an initial concentration slightly greater than or equal to the critical micelle concentration, a protective colloid, ethylenically unsaturated monomers, and an ionically balanced combination of an anionic and a cationic water soluble free radical initiator or a nonionic initiator; reacting the mixture to form an emulsion of polymerized monomer; and adding additional monomer, emulsifier, and protective colloid and a water soluble chain transfer agent to the reactor while continuing to agitate the mixture under conditions such that the emulsifier concentration does not exceed that at which new polymeric nuclei are formed. |