EFFECT OF HIGHLY CARBOXYLATED SEED LATICES ON SEMIBATCH SURFACTANT-FREE EMULSION POLYMERIZATION OF BUTYL ACRYLATE

A series of highly carboxylated latices comprising methacrylic acid (M AA) (or acrylic acid (AA)), dodecyl methacrylate and methyl methacryla te was prepared and characterized. The reaction parameters include the monomer composition, the concentration of dodecyl mercaptan (used as the molecular weight regulator) and the type of carboxylic monomers. T hese carboxylated latices were then used as the seed for the subsequen t semibatch surfactant-free emulsion polymerization of butyl acrylate (BA). The unneutralized seed latices are incapable of supporting the B A polymerization. On the other hand, the seed latices containing 50 wt % MAA or AA at pH 8-9 are very effective for this purpose due to the i ncreased particle surface charge density. The seed latex containing 50 wt% AA should be a better candidate for producing latex products with a higher solid content due to the appropriate rheological properties.