| 摘要 |
Polyvinyl alcohol having terminal carbonyl groups is made by cleaving polyvinyl alcohol having some carbonyl groups in the molecule by reaction with an alkaline liquid. The carbonyl groups are introduced into the polyvinyl alcohol by oxidation, e.g. with ammonium persulphate, bleaching powder, bromo-succinimide or by photo-oxidation in the presence of a photosensitizer or by irradiation. Prior to the alkaline treatment, the oxidized polyvinyl alcohol may be subjected to treatment with a dilute acid such as hydrochloric, sulphuric, formic, chloroacetic or benzenesulphonic acids. The cleavage with alkali is preferably conducted at 90 DEG -100 DEG C., under an atmosphere of nitrogen.
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