Patent ID: 6077903
Filing Date: 2000-06-20
Classification: C08F,C08L

Abstract:
A process for preparing a rubbery polymer which can be blended with polyvinyl chloride to make leathery compositions having good heat and ultraviolet light resistance, said process comprising continuously carrying out the steps of (1) charging (a) butyl acrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile monomer, (d) a crosslinking agent, (e) a sulfonate surfactant, (f) a dispersant selected from the group consisting of aromatic formaldehyde condensation products and polycarboxylates, (g) water and (h) a free radical generator into a first polymerization zone; (2) allowing the monomers to polymerize in the first polymerization zone under emulsion polymerization conditions to a monomer conversion of at least about 80 percent to produce a low solids polymerization medium having a solids content of no more than about 10 percent; (3) charging (a) the low solids polymerization medium, (b) additional butyl acrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer and (e) additional crosslinking agent into a second polymerization zone; (4) allowing the monomers to polymerize in the second polymerization zone under emulsion polymerization conditions to a monomer conversion of at least about 80 percent to produce an intermediate solids polymerization medium having a solids content of no more than about 20 percent; (5) charging (a) the intermediate solids polymerization medium, (b) additional butyl acrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer and (e) additional crosslinking agent into a third polymerization zone; (6) allowing the monomers to polymerize in the third polymerization zone under emulsion polymerization conditions to a monomer conversion of at least about 80 percent to produce a high solids polymerization medium having a solids content of no more than about 30 percent; (7) charging (a) the high solids polymerization medium, (b) styrene, (c) additional acrylonitrile and (d) additional crosslinking agent into a fourth polymerization zone; (8) allowing the monomers to polymerize in the fourth polymerization zone under emulsion polymerization conditions to a monomer conversion of at least 80 percent to produce an emulsion containing the rubbery polymer; and (9) recovering the rubbery polymer from the emulsion containing the rubbery polymer.