Patent GB-559843-A (GB)
Title: Improvements in sensitive photographic materials
IPC: G03C1/74
Filed: 1942-05-19
Abstract: 559,843. Photographic stripping materials. KODAK, Ltd., BATLEY, A., SOPER, A. K., and BLABER, M. P. W. May 19, 1942, No. 5700/43. Divided out of 554,292. [Class 98 (ii)] Photographic stripping material comprises a sensitive silver salt emulsion layer carried on a temporary support from which it can be drystripped and on the sensitive side an inseparable non-sensitive dry outermost layer formed by coating thereon a liquid lacquer. The lacquer layer may be of cellulose ester (cellulose nitrate) or resin (shellac). The stripping layer may be a wax or resin layer. The lacquer layer may be coloured, and the temporary support opaque or coloured, to render them absorbent of light to which the emulsion is sensitive. The lacquer layer may contain a matting agent or may be pigmented with titanium dioxide to provide a white reflecting background to the final image. A lacquer layer applied to the permanent support may also be pigmented, dyed, or otherwise coloured. A matting agent, e.g. starch, may be incorporated in the emulsion, in a layer between the emulsion and the temporary support, or in the temporary support. The emulsion may contain a filter dye (e.g. yellow). For the photolithography, the emulsion should have a low melting point (e.g. below 160‹ F.). An image may be formed in the emulsion by the reflex process as in Specifications 529,041 and 550,785, and in this case the temporary support is strongly diffusing or reflecting (e.g. white paper), and the emulsion dye-sensitized to a spectral region outside its natural sensitivity (e.g. to yellow-green). A further emulsion of low speed may be provided between the colour-sensitized emulsion and the lacquer layer, and the latter may contain a yellow colouring matter. The emulsion may be very transparent (e.g. a thin silver chloride or Lippmann emulsion) and be used in masking. Any layer between the emulsion and stripping layers should be removable in alkaline developing solutions or permeable thereto (e.g. polyvinyl phthalate) ; the resin layer described in Example 2 of Specification 550,775 may be used. Such a material may be made by coating a paper base successively with a trichlorethylene solution of beeswax, a solution of rosinmaleic anhydryde resin in acetone, industrial spirit, and water, an emulsion, and an adhesive layer of cellulose nitrate. The removable layer may also be coated from a solution of "ABRALAC" P (Registered Trade Mark) in acetone and ethyl lactate. The stripping layer may be a water-soluble layer permiting the emulsion layer to be stripped therefrom in a dry state, e.g. a layer of triethanolamine stearate. The lacquer layer may be applied to the stripping materials of Specifications 549,371 and 555,383. In an example, paper is successively coated with a trichlorethylene solution of beeswax, a process-type emulsion, and a composition comprising cellulose nitrate, ester gum, di-n-butyl phthalate, formamide, acetone, nbutyl acetate, n-butyl alcohol, and amyl acetate. The permanent support comprises anodized polished aluminium coated with a composition comprising cellulose nitrate, ester gum, di-n-butyl phthalate, ethyl acetate, and n-butyl acetate. One or both lacquer surfaces are treated with a softener, e.g. industrial spirit and ethylene glycol mono-methyl ether, and pressed together, and after curing the paper temporary support stripped off. The lacquer composition may also comprise cellulose nitrate, triphenyl phosphate, tri-cresyl phosphate, methyl triple solvent, n-butyl acetate, and industrial spirit. Specifications 11821/95, [Class 98], 520,157, 530,618, 554,292, 554,298, 554,300 and 554,301 also are referred to.