GB1378896A - Production of gravure printing plates - Google Patents

Abstract

1378896 Photo-mechanical printing plates BADISCHE ANILIN- & SODA-FABRIK AG 10 Dec 1971 [12 Dec 1970] 57436/71 Headings G2C and G2M A gravure printing plate is prepared from a layer (S) of photo cross-linkable plastics material which is soluble in developer solution but becomes sparingly soluble or insoluble after exposure and which is supported on a dimensionally stable substrate by (a) exposing through one face via a continuous tone positive until the photocrosslinkable layer behind and only behind the completely transparent areas of the positive is crosslinked throughout its entire thickness, (b) laminating said one face of the layer directly or indirectly to a base (c) exposing the layer through its other face via a screen grid to cross-link the layer throughout its thickness in a network of doctor lines, and then (d) washing out the non- cross-linked portions of the layer with a developer solution applied to its other face. Generally the substrate is removed after step (b). Layer (S) may be laminated directly to the base by an adhesive. Alternatively the face of layer (S) exposed in step (a) may be bonded to a 5-100Á light-transmitting layer (U) of plastics material insoluble in the developer solution and/or the base may be coated with a layer (U') of a 5-500Á layer of plastics material also insoluble in the developer solution. Preferably the plastics material in layers (U) and (U') is the same as that in layer (S) but crosslinked. Layer (S) may contain 0À05-20 wt per cent of inert, actinic-light absorber. In the Examples, there is used (A) a photo-sensitive member consisting of a polyethylene terephthalate support coated with either (1) a cross-linkable layer of (hexamethylene adipate/4, 4'-diaminodicyclohexylmethane adipate/caprolactam) copolyamide, (ethylene glycol/N-methylol acrylamide) diether, α-methylol benzoin methyl ether, ethylene glycol, Na salt of N-nitrosocyclohexylamine and a Cr complex of azo dyes (derived from 4-nitro- 2-aminophenol, anthranilic acid and #-naphthol), which may be overcoated with a photocross-linked layer of similar composition but free from the Cr complex, or (2) a cross-linkable layer of copolyamide and Na salt as in (1), N-methylolacrylamide, m-xylylene and triethylene glycol bisacrylamides and 2, 4-di-nitrophenol or 2, 2-dihydroxybenzophenone, overcoated with a photocross-linked layer of similar composition but free from dinitrophenol or dihydroxybenzophenone, and (B) a base of polyethyleneterephthalate film or of an Al cylinder having the same overcoating as the photo-sensitive member.