Etch bleaching processes for making lithographic printing plates using silver halide and/or diffusion transfer layers and a hydrophilic layer

Claim 1

A METHOD OF MAKING A LITHOGRAPHIC PRINTING PLATE FROM A PLATE COMPRISING A SUPPORT HAVING AN OLEPHILIC SURFACE BEARING THEREON A HYDROPHILIC INTERMEDIATE LAYER CONTAINING AT LEAST ONE COMPOUND SELECTED FROM THE FOLLOWING GROUPS A, B AND C: GROUP A: GUM ARABIC, ALGINIC ACID, HYDROXYETHYL CELLULOSE, METHYL CELLULOSE, CARBOXYMETHYL CELLULOSE, POLYACRYLAMIDE, POLYVINYL PYRROLIDONE, COPOLYMERS OF THE ABOVE COMPONENTS, POLYVINYL ALCOHOL, AND A POLYVINYL ALCOHOL DERIVATIVE; GROUP B: A MALEIC ANHYDRIDE-VINYL ACETATE COPOLYMER, A MALE;IC ANHYDRIDE-ETHYLENE COPOLYMER, A MALEIC ANHYDRIDE-METHYL VINYLETHER COPOLYMER, A MALEIC ANHYDRIDESTYRENE COPOLYMER, HALG ESTER DERIVATIVES OF THOSE COPOLYMERS, HALF AMIDE DERIVATIVES OF THOSE COPOLYMERS, AN ACRYLIC ACID COPOLYMER, AND A METHACRYLIC ACID COPOLYMER; AND GROUP C: PARTIALLY SAPONIFIED CELLULOSE ACETATE, PARTIALLY SAPONIFIED CELLULOSE BUTYRATE, AND PARTIALLY SAPONIFIED CELLULOSE ACETATE BUTYRATE; SAID INTERMEDIATE LAYER BEARING THEREON A PHOTOSENSITIVE SILVER HALIDE EMULSION LAYER A; OR A HYDROPHILIC DIFFUSION TRANSFER IMAGE RECEIVING LAYER (B) CONTAINING PHYSICAL DEVELOPMENT NUCLEI, OR A LAYER B CARRYING THEREON A SILVER HALIDE EMULSION LAYER A'' ON THE SIDE THEREOF AWAY FROM THE HYDROPHILIC INTERMEDIATE LAYER, WHICH METHOD COMPRISES: FORMING A SILVER IMAE IN LAYER A OR B, REMOVING LAYER AZ WHEN IT IS PRESENT ON LAYER B, AND ETCH BLEACHING THE SILVER IMAGE, THEREBY ETCHING AWAY LAYER A OR B AT SILVER IMAGE PORTIONS THEREOF AND AT THE SAME TIME THE HYDROPHILIC INTERMEDIATE LAYER UNDER THE SILVER IMAGE PORTIONS THEREOF TO THEREBY EXPOSE THE OLEOPHILIC SURFACE OF THE SUPPORT AT PORTIONS CORRESPONDING TO THE SILVER IMAGE PORTIONS IN LAYER A OR B.

Claim 2

A METHOD OF MAKING A LITHOGRAPHIC PRINTING PLATE FROM A PLATE COMPRISING A SUPPORT HAVING AN OLEPHILIC SURFACE BEARING THEREON A HYDROPHILIC INTERMEDIATE LAYER CONTAINING AT LEAST ONE COMPOUND SELECTED FROM THE FOLLOWING GROUPS A, B AND C: GROUP A: GUM ARABIC, ALGINIC ACID, HYDROXYETHYL CELLULOSE, METHYL CELLULOSE, CARBOXYMETHYL CELLULOSE, POLYACRYLAMIDE, POLYVINYL PYRROLIDONE, COPOLYMERS OF THE ABOVE COMPONENTS, POLYVINYL ALCOHOL, AND A POLYVINYL ALCOHOL DERIVATIVE; GROUP B: A MALEIC ANHYDRIDE-VINYL ACETATE COPOLYMER, A MALE;IC ANHYDRIDE-ETHYLENE COPOLYMER, A MALEIC ANHYDRIDE-METHYL VINYLETHER COPOLYMER, A MALEIC ANHYDRIDESTYRENE COPOLYMER, HALG ESTER DERIVATIVES OF THOSE COPOLYMERS, HALF AMIDE DERIVATIVES OF THOSE COPOLYMERS, AN ACRYLIC ACID COPOLYMER, AND A METHACRYLIC ACID COPOLYMER; AND GROUP C: PARTIALLY SAPONIFIED CELLULOSE ACETATE, PARTIALLY SAPONIFIED CELLULOSE BUTYRATE, AND PARTIALLY SAPONIFIED CELLULOSE ACETATE BUTYRATE; SAID INTERMEDIATE LAYER BEARING THEREON A PHOTOSENSITIVE SILVER HALIDE EMULSION LAYER A; OR A HYDROPHILIC DIFFUSION TRANSFER IMAGE RECEIVING LAYER (B) CONTAINING PHYSICAL DEVELOPMENT NUCLEI, OR A LAYER B CARRYING THEREON A SILVER HALIDE EMULSION LAYER A'' ON THE SIDE THEREOF AWAY FROM THE HYDROPHILIC INTERMEDIATE LAYER, WHICH METHOD COMPRISES: FORMING A SILVER IMAE IN LAYER A OR B, REMOVING LAYER AZ WHEN IT IS PRESENT ON LAYER B, AND ETCH BLEACHING THE SILVER IMAGE, THEREBY ETCHING AWAY LAYER A OR B AT SILVER IMAGE PORTIONS THEREOF AND AT THE SAME TIME THE HYDROPHILIC INTERMEDIATE LAYER UNDER THE SILVER IMAGE PORTIONS THEREOF TO THEREBY EXPOSE THE OLEOPHILIC SURFACE OF THE SUPPORT AT PORTIONS CORRESPONDING TO THE SILVER IMAGE PORTIONS IN LAYER A OR B.