Planographic diazo printing plate

Abstract

Abstract A PAPER-BASED PLANOGRAPHIC PRINTING PLATE GIVING UP TO 1500 OR MORE GOOD PRINTS WITH REPRODOUCTION OF FINE SCREEN AREAS IS OBTAINED BY PROVIDING A WATER-REPELLENT COATING ON THE PAPER SURFACE, ON THAT COATING AN INTERMEDIATE LAYER OF FILLER-PERMEATED MIXTURE OF A HYDROPHILIC ORGANIC BINDER AND A HYDROPHOBIC THEREMOPLASTIC FILM-FORMING POLYMER, ON THAT LAYER A FILLER-PERMEATED PLANOGRAPHIC LAYER OF CROSS-LINKED POLYVINYL ALCOHOL HAVING A DEGREE OF HYDROLYSIS GREATER THAN 98% AND A LIGHTSENSITIVE DIAZO COMPOUND COATED ON THE PLANOGRAPHIC LAYER. THE INTERMEDIATE LAYER IS FORMED FROM AN AQUEOUS DISPERSION OF HYDROPHOBIC POLYMER AND FILLER, ADVANTAGEOUSLY FINELY DIVIDED CLAY, HAVING THE HYDROPHILLIC BINDER, E.G., A STARCH DERIVATIVE, AND A CROSSLINKING AGENT IN THE CONTINUOUS PHASE. THE FILLER IN THE PLANOGRAPHIC LAYER ADVANTAGEOUSLY IS PIGMENTARY TIO2. THE LIGHT-SENSITIVE COATING IS FORMED INTO A WATER-INSOLUBLE INK-RECEPTIVE IMAGE BY IMAGEWISE EXPOSURE AND DEVELOPMENT WITH AN AZO COUPLING COMPONENT GIVING A POSITIVE IMAGE, IN USE OF A DIAZONIUM SALT OF HIGH COUPLING ACTIVITY, E.G., A 4BENZOLYLAMINO-2,5-DIALKOXY BENZENE DIAZONIUM SALT, AND BY IMAGEWISE EXPOSURE GIVING A NEGATIVE IMAGE WHEN A DIAZO RESIN IS USED.

Inventors

• 👤 J Haaf
• 👤 L Heuts

Bibliographic Details