| 摘要 |
Dispersed polymer particles in a butadiene polymer synthetic rubber latex containing 2 to 10 parts of a water soluble soap of a soap-forming mono-carboxylic acid and having a pH from 8 to 11 are increased in size by reducing the pH to 55 to 75 in the presence of 0,05 to 1% of polyvinyl alcohol or polyethylene polyamine based on the solids weight and then increasing the pH to 8 to 11. The latex may then be concentrated e.g. from a solids content of 25 to 50% to one of 55 to 70%. Specified polymers are those of butadiene, 2-methylbutadiene, 2, 3-dimethyl butadiene, piperylene, and their copolymers, with styrene, substituted styrenes, vinyl naphthaline, acrylic acid, methyl acrylate or methacrylate, acrylonitrile, methacrylonitrile, methacrylamide, vinyl pyridines, methyl vinyl ketone and vinylidene chloride. Specified soaps are, the alkali metal, ammonium and amine salts of higher fatty acids having 10 to 24 carbon atoms in the molecule or of rosin acids including dehydrogenated, hydrogenated and disproportionated rosin acids. Other types of surface active dispersing agents may also be present. The pH is reduced with anidic material, e.g. carbon dioxide, formic acid, acetic acid, sodium silicofluoride, and ammonium and formaldehyde. The pH is increased by the addition of ammonia or sodium or potassium hydroxide.
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