GB1278773A - Photoprinting - Google Patents

Abstract

1278773 Photo-printing E S & A ROBINSON (HOLDINGS) Ltd 20 June 1969 [20 June 1968] 29538/68 Headings G2A and G2C A method of multi-colour printing comprises passing a web prepared for the production of a multi-colour image by a non silver halide photosensitive system through a photo-printing station, exposing the web by projecting at said station a brief flash of multi-colour light from an original on to the moving web and subsequently treating the exposed web to produce a stable multi-colour image. The systems which can be used include photo-polymerization, dye initiated photopolymerization, dye sensitized dispersion photopolymerization and dye bleach out. The web is coated by e. g. a trailing blade coater, on one or both sides by a dye mixture of e.g. aurine, brilliant cresyl blue and acid fuschine, with oxalmolydic acid as the accelerator and gelatine as the carrier. Black dye may be added as necessary. If solid white is desired in the finished image, a finely dispersed white pigment may be added to the dye stuff mixture. An intermediate drier may be provided. After exposure, some dye mixtures may need to be treated with a mordant bath. The photo-printing station comprises a stationary transparency, a condenser system with heat filter and a xenon flash-lamp. The image may be stationary in space, in which case the web path is planar at the photo-printing station, or the image may be stationary with respect to the web, in which case the web path is curved and the image movement obtained by means of a rotating mirror or prism. Successive images of the same or a different transparency may be found on the web by successive flashes of the lamp. For an opaque web coated on both sides, images may be printed on each side by means of two optical systems.