Patent ID: 6861462

Claim:
A process of preparing a nanocomposite comprised of an elastomer and at least partially exfoliated platelets from a water-swellable clay which comprises blending: (A) an aqueous pre-formed elastomer latex comprised of elastomer particles with cations on the surface thereof prepared by aqueous free radical induced polymerization of monomers in the presence of a free radical generating polymerization initiator and surfactant; wherein said monomers are comprised of: (1) styrene and 1,3-butadiene monomers which contain from about 0.1 to about 40 weight percent styrene monomer, (2) styrene and isoprene monomers which contain from about 0.1 to about 40 weight percent styrene monomer, (3) isoprene monomer, (4) 1,3-butadiene monomer, (5) isoprene and 1,3-butadiene monomers, (6) 1,3-butadiene and acrylonitrile monomers which contain from about 5 to about 45 weight percent acrylonitrile monomer; or (7) isoprene and acrylonitrile monomers which contain from about 5 to about 45 weight percent acrylonitrile monomer wherein said free radical generating polymerization initiator is selected from: (1) a cationic aqueous polymerization initiator, or (2) an anionic aqueous polymerization initiator, or (3) neutral aqueous polymerization initiator, or (4) a redox free radical initiator system; wherein said elastomeric polymer particles are stabilized in said latex by a surfactant selected from: (1) non free-radically polymerizable cationic surfactant, and/or (2) free-radically polymerizable cationic surfactant; (B) an aqueous mixture of water and a multilayered water-swellable clay which contains cationically exchangeable ions in its galleries between said layers, exclusive of an intercalant for said clay, wherein said water-swellable clay is comprised of a plurality of stacked platelets with water-swollen galleries between said platelets.