| 摘要 |
<p>1,262,101. Polymerization process. NALCO CHEMICAL CO. 13 Feb., 1969 [29 Nov., 1968], No. 7820/69. Heading C3P. Water-soluble polymers are prepared by polymerizing one or more polar solvent-soluble monomers, which undergo polymerization exothermically, by means of the following steps: (A) forming a polar solvent solution of the monomer(s) and a polymerization catalyst while maintaining a temperature of at least 100‹ F. but below the polymerization temperature, (B) forming the thus prepared solution into a layer 1-30 mm. thick, (c) heating the layer by means of a heated gas in a closed atmosphere to a temperature sufficient to initiate polymerization, and (D) thereafter continuing the polymerization in said closed atmosphere by the exothermic heat of reaction while utilizing said gas as a coolant until the desired polymerization is completed. In a preferred embodiment, the solution is formed into layers by placing in metal trays coated with polytetrafluoroethylene, and the trays heated in a drier unit wherein the heated gas is air; alternatively, the layers can be formed on a conveyer belt which is moved continuously through a drying chamber. After polymerization, the temperature can be increased to remove the solvent from the polymer product. The process is suitable for the preparation of acrylamide polymers, e.g. polyacrylamide and acrylamide-acrylic acid copolymers, which polymers are useful as flocculating agents for suspensions of solid particles. Polymerization catalysts specified are azobisisobutyronitrile, ammonium persulphate, and ammonium persulphate/sodium metabisulphite. In examples polymerization is effected in aqueous solution.</p> |
