PURPOSE: To obtain a soundproofing film excellent in soundproofing performance by cyanoethylating hydroxyethyl cellulose having specific properties and forming the resulting cyanoethylated hydroxyethyl cellulose into a film having a predetermined thickness.
CONSTITUTION: There is prepd. a hydroxyethyl cellulose, a 2wt.% aq.soln. of which has a viscosity at 20°C of 10 to 10,000cP. Subsequently, cyanoethylated hydroxyethyl cellulose having a degree of cyanoethyl group substitution of 0.3 to 2.5 is obtd., e.g. according to a method comprising dissolving the hydroxyethyl cellulose in, e.g. an aq.soln. of an alkali, then slowly introducing acrylonitrile into the resulting soln. being heated in a hot water bath, stirring the resulting mixture, and further refluxing it to effect addn. of cyanoethyl groups to hydroxyethyl groups and hydroxyl groups in the cellulose skeleton. Subsequently, the cyanoethylated hydroxyethyl cellulose is formed into a film of 20 to 200μm in thickness to thereby obtain a soundproofing film. The soundproofing film can be suitably used in combination with a sound absorbing material for production of a wall panel.
WATANABE TAKESHI
KAMIMURA MOTOKAZU
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