GB510706A - Sheeting suitable for use as photographic film base and solutions for the manufacture thereof - Google Patents

Abstract

510,706. Cellulose ester compositions ; films &c. KODAK, Ltd., Feb. 4, 1938, No. 3549. Convention date, Feb. 4, 1937. [Class 2(ii)] [Also in Group XX] Sheeting suitable for use as photographic film base is made from a composition comprising a cellulose acetate-propionate having a propionyl content of approximately 10-40 per cent., or a cellulose acetate-butyrate having a butyryl content of approximately 8-40 per cent., or mixtures of these, or a cellulose acetatepropionate-butyrate having a combined propionyl and butyryl content of approximately 8-40 per cent., dissolved in a solvent mixture consisting of 95-70 per cent. of propylene chloride and 5-30 per cent. of a lower aliphatic alcohol such as methyl alcohol. The cellulose ester, or each of the cellulose esters in the case of a mixture, must have a total acyl content of at least 42 per cent., and the cellulose ester or mixture of cellulose esters must have a viscosity of at least 20 seconds as determined by a method indicated. Plasticisers may be added but not in amount greater than 35 per cent. of the cellulose ester content. Plasticisers mentioned are organic phosphates such as triphenyl, tricresyl, tributyl, diphenyl monocresyl, and monophenyl dibutyl phosphates, phthalates such as dibutyl and ethoxyethyl phthalates and methyl phthalyl ethyl glycollate, esters of higher fatty acids such as methyl stearate, and diesters of aliphatic dibasic acids such as diethoxyethyl adipate. Colouring materials or materials to give opaqueness such as dyes, pigments or colloidal materials may also be incorporated in the film-forming composition. The sheeting may be prepared by flowing out the composition upon the surface of a band or a rotating drum in an evaporative atmosphere and then stripping. Details are given of the preparation of suitable cellulose esters and of the preparation of photographic film from the sheeting, reference being made to the application of subsidiary coatings to the film, in particular of extra heavy cellulose nitrate coatings or of a series of coatings the successive layers of which are of cellulose esters hydrolysed to a progressively increasing extent. The sheeting may be used in the preparation of laminated structures together with glass, other cellulose materials, resinous materials, wood, paper, or metal. Specifications 406,011, 470,565, 477,153, 477,289 and 478,357, [all in Group XX], are referred to.