GB395889A - Photographic anti-halation layer - Google Patents

Abstract

395,889. Photographic films. I. G. FARBENINDUSTRIE AKT.-GES., Frankfort-on-Main, Germany. Sept. 1, 1932, No. 24417. Convention date, Sept. 22, 1931. [Class 98 (ii).] A photographic film is furnished on its rear side with a thin, anti-halation, colloidal layer coloured with non-actinic colouring matter, which layer is rendered detachable in the dry or the wet state by pretreatment of the support or by choice of the solvent by which the layer is applied. A layer produced by means of an alkaline casein solution containing formaldehyde and a colouring matter, is excluded. Suitable colloids comprise albumins, cellulose derivatives or natural or artificial resins. The treatment of the support, e.g. nitrocellulose or cellulose acetate, may consist in decreasing the gelatine content of the solution of gelatine in glacial acetic acid employed prior to the application of the colloid layer ; or the solution may contain a solvent, such as alcohol, which exerts only a feeble swelling action. Alternatively, the layer is applied to the support without pretreatment, the solvent for the layer being such as to exert at most a feeble swelling action on the support. Examples are given of (1) a suspension of soot in aqueous gelatine solution applied to an untreated nitrocellulose or cellulose acetate support, (2) a similar suspension applied to a nitrocellulose film treated with a gelatine-acetic acid-alcohol solution, (3) a celluloid-graphite mixture dissolved in an ether-alcohol mixture applied to an untreated acetylcellulose film, and (4) a cellulose ether-soot mixture dissolved in benzene and applied to an untreated acetylcellulose film. Reference has been directed by the Comptroller to Specification 292,990, [Class 98 (ii), Photographic processes &c.].