GB1371125A - Photographic process for producing metallic image bonded to a roughened support and products produced thereby - Google Patents

Abstract

1371125 Printing plates; measuring surface roughness ITEK CORP 9 Aug 1972 [23 Aug 1971] 37101/72 Headings G2C and G2J [Also in Division G1] A process of producing an imaged metal plate useful as a printing plate comprises contacting a physically developable image on a grained metallic support with a solution of metal ions until the image formed is a conductive metallic image adherently bonded to the support, the grain of the metallic support (i) being capable of forming a bond with a metallic image and (ii) when tested on an Optical Scanning Roughness Meter as described below, producing a trace having a Peak Height A of between 0À25 and 0À90, at a Position B of between 0À35 and 0À80 and having a psi value C of between 0À40 and 1À0. The metal support carrying the physically developable image may be obtained by the silver salt diffusion process using a grained metal support as described above as the receptor element, or by exposure of a photo-sensitive element having such a grained metal support. Thus a photo-sensitive element may comprise a photo-sensitive layer of less than 2 microns thickness containing a photo-sensitive material capable of producing a physically developable image on exposure, e.g. silver chloride or a photo-conductor such as TiO 2 , ZnO, ZrO 2 , GeO 2 , InO 2 , CdS, ZnS, SnS 2 or CdSe, on a grained aluminium support having a grain as described above. The printing plate is made by exposing the above element to form a physically developable image, contacting the element with a solution of metal ions, e.g. a stabilized physical developer solution containing AgNO 3 , ferrous ammonium sulphate, ferric nitrate, citric acid, acetic acid and surfactants with or without sulphur compounds such as sodium thiosulphate, cysteine, mercaptoacetic acid or mercaptobenzthiazole, until a conductive metal image adherently bonded to the metal support is formed. The Optical Surface Roughness Meter comprises a coherent light source e.g. a laser 1 to pass coherent light through a spatial filter 2, a collimating objective 3 and a beam splitter 4, the light then striking the surface 5 of the rotating sample being tested and being reflected back through the beam splitter and through a transforming objective 8 to focus on a pinhole aperture 9 which has a photo-tube 10 positioned behind it. The output voltage from the photo-tube is amplified and multiplied by the voltage output of a sinusoidal potentiometer linked to the sample rotator 7, and plots of the power spectrum of the reflected coherent light as modulated by the surface irregularities of the sample are recorded on the X-Y recorder.