GB383069A - Process for manufacturing films from casein - Google Patents

Abstract

Casein is brought into colloidal solution in an alcoholic dispersion liquid, a coagulating agent added, and the solution poured upon a surface to form a film. The colloidal solution is formed in the following manner. The casein and an alcohol or mixture of lower alcohols are placed in a mixer together if desired with a plastifier such as glycerine or terpin hydrate, and an alkaline salt (sodium carbonate), an oxidizing agent (hydrogen peroxide), and more of the dispersion liquid are progressively and alternately added so as to avoid coagulation, the temperature of the mixture being at the same time gradually raised to 100 DEG C. The colloidal solution obtained is submitted to electrolysis which has the effect of (1) dehydration, (2) transformation of the sodium carbonate to sodium hydroxide, (3) purification by deposition of microscopic impurities, and (4) displacement of the pH value. A coagulating agent is then added, e.g., hexamethylene tetramine, formol, tannin, or trioxymethylene together if necessary with substances which affect the rate of coagulation, such as glycerine or propyl alcohol. Acidification at this stage gives the products to be obtained a higher impermeability. The mixture is poured on to a glass plate or moving nickel-plated or chromium-plated iron sheet, and the hardening of the film accelerated by passage through a vacuum or by suitably raising the temperature. The treatment of the detached film comprises, (1) partial dissolution of the surface of the film, e.g. in glacial acetic acid, (2) hardening, simultaneously with (1) by means of organic liquids, e.g., butyl, propyl, or isoamyl alcohol, acetone, or benzene, (3) plastification by means of acetin, triacetin, engenol, cyclohexanol, glycerin, amyl acetate, butyl acetate, or the like. The films may finally be hot calendered.