| 摘要 |
Polyvinyl alcohols are manufactured by displacing the polyvinyl alcohol from an organic compound thereof (which, if it is an ester, is soluble in alcohol), by means of a practically anhydrous alcohol in the presence of an acid or alkaline substance. The products are useful as protective colloids, adhesives, sizing agents, especially for artificial silk, for the manufacture of moulded articles and sound records with or without suitable additional substances or filling agents, as intermediate layers for safety glass with or without additional substances, e.g. glycerine, as a substitute for rubber, for medicinal and pharmaceutical purposes, for the preparation of printing pastes, and for working up into plates, balls, threads and films. In examples: (1) a solution of polyvinyl alcohol - formaldehyde acetal in absolute alcohol is boiled with the addition of sulphuric acid; (2) polyvinyl acetate is boiled with a solution of hydrogen chloride in absolute alcohol; (3) a solution of polyvinyl acetate in absolute alcohol is boiled with the addition of sulphuric acid; (4) polyvinyl acetate is boiled with a solution of caustic potash in absolute alcohol; (5) a solution of polyvinyl butyrate in benzene is mixed with absolute alcohol and sodium ethylate is added; (6) a solution of polyvinyl acetate in acetone and absolute alcohol is boiled with a solution of caustic soda in absolute alcohol; 7) polyvinyl acetate is heated with a solution of caustic potash in absolute methyl alcohol; (8) a solution of polyvinyl acetate in acetone is mixed with anhydrous glycol and sodium ethylate is added; (9) a solution of polyvinyl chloracetate in acetone is heated to 120 DEG C. in a sealed tube with a solution of dry ammonia in absolute alcohol. Mixtures of alcohols may also be used. |
