| 摘要 |
1,004,446. Granulating polyvinyl alcohol. RHONE-POULENC S.A. April 9, 1964 [April 11, 1963], No. 14785/64. Heading B5A. A process of granulating a polyvinyl alcohol gel, formed by the alkaline alcoholysis of a polyvinyl ester, comprises extruding the gel through the perforated plate of an extrusion granulator by means of a piston, the granules so formed being subsequently dried. The gel may be formed by catalysing a solution of polyvinyl acetate in methanol with an aqueous, methanolic or aqueous-methanolic solution of sodium hydroxide. A plasticizer such as glycerine may be added. Several detailed examples are given. |
