Patent GB-568652-A (GB)
Title: Improvements in sensitive photographic materials
IPC: G03C1/805
Filed: 1943-09-22
Abstract: 568,652. Photographic stripping material. KODAK, Ltd., SOPER, A. K., BATLEY, A., and BRANCH, L. E. T. Sept. 22, 1943, No. 15547. [Class 98 (ii)] Photographic dry-stripping material comprises a silver salt emulsion layer carried, through an intermediate dry-stripping layer, on a temporary support from which it can be dry-stripped and having on the sensitive side of the material an outermost inseparable non- sensitive dry layer of a hydrophilic binder other than gelatine. The material may be drystripping. The hydrophilic layer may comprise methyl cellulose, a partially hydrolysed cellulose acetate which may contain from 25 to 35 per cent acetyl, or a hydrophilic resin, such as a partially hydrolysed polyvinyl ester, e.g. acetate. A hydrophobic layer (e.g. a hydrophobic cellulose ester or resin) or, alternatively, a layer coated from an aqueous-organic solution of gelatine and a resin may be coated between the emulsion and the hydrophilic layer. The temporary support may be paper coated with a wax or resin stripping layer. The stripping materials of Specifications 549,371 and 555,383 may be coated with a hydrophilic layer. In example 1, paper is successively coated with a trichlorethylene solution of beeswax, a processtype emulsion, a cellulose nitrate layer coated from a composition comprising cellulose nitrate, tricresyl phosphate, triphenyl phosphate, methyl triple solvent, and butyl alcohol, and then with a partially hydrolysed polyvinyl acetate layer (comprising 85 per cent acetyl calculated as vinyl acetate) from a solution in industrial spirit. The material of example 2 is similar, but the hydrophilic layer is formed by coating an aqueous-acetone solution of partially hydrolysed cellulose acetate (comprising 20 to 25 per cent acetyl). In example 3, the hydrophilic layer is formed by coating a trichlorethylene-industrial spirit solution of ethyl cellulose. The final support may be anodized, polished aluminium coated with lacquer comprising cellulose nitrate, ester gum, di-n-butyl phthalate, ethyl acetate, and n-butyl acetate. A softener solution is applied to the lacquer or hydrophilic layer or both before contacting. A mixture of industrial spirit and ethylene glycol monomethyl ether may be used. The temporary support may be opaque or coloured. For photolithography, the emulsion may have a low melting point, e.g. below 160‹ F. Amatting material, 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 hydrophilic layer may contain a white or coloured pigment (e.g. titanium dioxide) or dye or a matting agent. The layer applied to the permanent support may also contain a pigment or dye. A latent image may be formed in the emulsion by the reflexprinting process as in Specifications 529,041 and 550,785, and the temporary support may be strongly diffusing or reflecting (e.g. white paper) or white pigment may be incorporated in one of the layers between the temporary support and the emulsion. The emulsion may be dye-sensitized to a portion of the spectrum outside the range of its natural sensitivity, e.g. to yellow-green. A further emulsion of low speed may be coated between the coloursensitized emulsion and the hydrophilic layer, and the latter may contain a yellow colouring matter. The emulsion may contain a filter dye (e.g. yellow). The emulsion may be relatively transparent (e.g. a thin silver chloride or Lippmann emulsion) and may be used in the production of a masking image. A removable layer (e.g. polyvinyl phthalate or the resin layer described in example 2 of Specification 550,775 may be coated between the emulsion and the stripping layer. Such material may be made by successively coating paper with a trichlorethylene solution of beeswax, a solution of rosin-maleic anhydride resin in acetone, industrial spirit, and water, sensitive emulsion, and a hydrophilic layer, with or without an intermediate layer. The removable layer may also be coated from a solution comprising " Abrailac P " (Registered Trade Mark), acetone, and ethyl acetate. A water-soluble dry-stripping layer (e.g. formed by coating an aqueous solution of triethanolamine stearate) may be used. Specifications 520,157, 530,618, 554,292, 554,298, 554,300 and 554,301 also are referred to.