Suspension polymerization with cosolvent partitioning

Claim 1

Aqueous suspension process for preparing low molecular weight alkali-soluble polymers from a water insoluble vinylic monomer and an acid-containing water soluble vinylic monomer, which comprises: (a) conducting a polymerization reaction between said water soluble monomer and water insoluble monomer within nonaqueous copolymer droplets, under steady state conditions of (i) reduced steady state monomers concentration and (ii) enhanced polymerization rate, said droplets dispersed in a stabilized aqueous suspension of from 15 to 42 weight percent based on total nonvolatiles of a polar, water-insoluble lower alkanol; (b) employing (1) an oil soluble initiator and (2) a mercaptan chain transfer agent having low water solubility, to foster polymerization in said non-aqueous phase and to promote homogeneous molecular weight distribution for said copolymer product, wherein said lower alkanol efficiently partitions said water-soluble monomer, said initiator and said chain transfer agent into the polymer droplet to replace polymerized monomers therein, and; (c) removing said lower alkanol by distillation under surfactant stabilization to prevent agglomeration of said copolymer product.