| 摘要 |
Films are prepared by bringing casein into aqueous solution of such high concentration and viscosity that the mineral salts and other impurities become insoluble therein, filtering the solution, treating with a deficiency of a setting agent, coating a base with the solution, and drying the coating. A suitable concentration for the solution is 15 per cent. The viscosity of this solution may be made about the same as that of glycerine, e.g. by adding alkali until the pH value is about 7,2. In order to prevent deterioration by fermentation, the temperature of the solution is preferably kept at about 71 DEG C. Plasticizers, such as glycerine and sulphonated castor oil may be added. The setting agent, e.g. formaldehyde, hexamethylenetetramine, trioxymethylene, aldehydes, chromium salts, tannic acid, or acetone, may be added to the solution, or the formed layer of casein solution may be passed through a bath containing it. A suitable amount of formaldehyde (40 per cent solution), is 1 per cent of the amount of casein solution treated. The film produced may be rendered moisture proof by coating with a cellulose lacquer. The process may be applied to the coating of foils or sheets of other materials with casein.
|
