GB482979A - Improvements in or relating to photographic film supports - Google Patents

Abstract

<PICT:0482979/IV/1> <PICT:0482979/IV/2> An extremely thin discontinuous layer of finely divided water-soluble or water-swellable colloid is deposited on a film-forming surface, a layer of particles of another colloid which is thermo-plastic is deposited over said layer, and the mass is colloidized to a continuous sheet by the action of heat and pressure. In a modification, a solution of the second colloid is deposited over the layer of the water-soluble or water-swellable colloid and the mass is congealed by removal of solvents. The continuous colloid layer may consist of cellulose acetate or a vinyl resin, and the discontinuous layer of gelatin or casein. Using the apparatus of Fig. 1, a discontinuous layer of the water-soluble or water-swellable colloid is obtained by applying the finely divided colloid from the hopper 2 of the endless steel band 4. The band passes under the hopper 6 from which it receives a layer of the thermoplastic colloid, and then under a second endless band 10 and between heated pressure rollers 17, 18, 19, 20, 21 and 22. Fig. 5 shows the cross-section of the film after the colloid particles 1 have been swollen and the light-sensitive emulsion 25 applied. Specification 351,082 is referred to. The Specification as open to inspection under Sect. 91 relates also to a modification in which the finely divided water-soluble or water-swellable colloid particles are incorporated with the film-forming dope, and also includes the use of powders other than water-soluble or water-swellable colloids, which powders may be rendered sticky or adherent by partial solvent action. The subject-matter of Specification 482,995 also is included. This does not appear in the Specification as accepted.