GB426023A - Manufacture of photographic supports from cellulose derivatives - Google Patents

Abstract

Softening agents for incorporating with cellulose derivatives in the manufacture of photographic films comprise a derivative or conversion product from a mixture of fatty acids consisting chiefly of those having 8 to 14 carbon atoms, which derivative or conversion product has no odour or only a faint odour, and, when it is a mixture of esters, consists of aliphatic alcohol-monocarboxylic acid esters. As suitable parent materials there are specified saponified vegetable fats, particularly coco-nut oil and palm kernel oil, and fatty acids obtained by oxidizing paraffins. From these materials softening agents are obtained by esterifying the mixture of acids with an aliphatic alcohol, e.g. amyl alcohol, or by reducing it to the corresponding fatty alcohols. These alcohols may be converted into esters of monocarboxylic acids, or ethers, or halides of the paraffin series. Before use of the softeners the portions of low and high molecular weight are removed, for example, the first by fractional distillation, and the second by fractional crystallization. A particularly suitable softener for cellulose nitrate is the fraction of the alcohols obtained by reduction of the fatty acids of coco-nut oil, which boils at 150 DEG C./13 mm. The following examples are given. (1) Nitrocellulose containing 12,2 per cent of nitrogen is dissolved in a mixture comprising the amyl esters of the fatty acids of coco-nut oil, acetone, and ethyl alcohol, and the solution cast into films. (2) A film is made from a solution containing nitrocellulose, ether, alcohol, and the alcohols obtained by reduction of the fatty acids of coco-nut oil. (3) The alcohols obtained by the reduction of the fatty acids of coco-nut oil of example 2 are replaced by a mixture of monochlorides of the hydrocarbons corresponding to the said alcohols. (4) Acetyl cellulose and a mixture of alcohols obtained by the catalytic oxidation of liquid paraffin, reduction of the acids to the corresponding alcohols, and isolation of the fraction boiling between 120 and 250 DEG C., are dissolved in a mixture of methylene chloride, chloroform, and amyl alcohol, and the solution cast into films. Tables are given of various physical properties of the films of each of the examples.