Microsuspension polymerization process to yield vinyl halide polymer latex involving delayed addition of bulk monomer mix

The batch process for the production of a vinyl halide polymer latex which comprises subjecting a polymerization mixture of a vinyl halide-containing monomeric material to homogenization, polymerizing said mixture in aqueous microsuspension in the presence of a monomer-soluble free radical initiator, and, after at least 40% and before 80% of the original monomeric material has been converted to polymer, adding not more than 40% by weight based on the weight of the original monomeric material of bulk vinyl halide-containing monomeric material at a rate and in a quantity such as to maintain the stability of the latex.