| abstract |
An aqueous dispersion of a rubbery polymeric material is prepared from a feedstock which contains the material in solution in a volatile organic liquid by sub-dividing the feestock into droplets, intimately mixing the droplets with steam in conditions in which steam condenses on the droplets and all of the organic liquid is volatilized from each droplet while that droplet is free of external contact with a solid or bulk liquid and collecting the remaining portions of the droplets as a dispersion in water, in the presence of a surface-active agent, the rubbery material being soft at the temperature of collection. Specified organic liquids are toluene, heptane, chloroform, carbon tetrachloride, chlorobenzene, trichlorethylene, ethyl acetate and acetone. The feedstock may be a solution of a natural or synthetic rubber or a dispersion of such a solution and may carry such compounding ingredients as reinforcing fillers, vulcanizing agents, accelerators, antioxidants, antiozonants, blowing agents, initiators and catalysts. Example are given of the preparation of (I) a dispersion of an ethylene/propylene copolymer from a solution of a rubbery ethylene/propylene copolymer in equal parts of carbon tetrachloride and hexane, (II) a dispersion of polybutadiene from a dispersion of a solution of polybutadiene in hexane, and (III) a latex of polybutadiene containing carbon black. Apparatus for carrying out the process is described. |