Base plate and lithographic plate prepared by sensitization thereof

Claim 2

A lithographic plate comprising: a substrate comprising a metal support and over said support a silicate barrier layer having a water-wettable hydrophilic surface, and over said substrate a lithographic coating comprising two layers applied in separate sequential coating steps, said layers comprising: an inner oleophilic nonwater-redispersible reinforcing layer applied in a first coating step and which, as applied to the substrate, is subject to removal by a water/polar organic solvent mixture and permeable to penetration by a light-sensitive condensation product, said inner layer comprising an olephilic nonwater-redispersible ink-receptive acrylic resin overlying said substrate and in direct contact with said surface, and an outer water-soluble light-sensitive layer applied in a subsequent step over said inner layer, said outer layer comprising a negative-working light-sensitive condensation product of an aryl diazo compound and a carbonyl compound generally overlying said inner layer but sufficiently contiguous with said substrate by penetration of said condensation product through said layer so that both said inner layer and said outer layer become anchored to the substrate in the areas of exposure when the light-sensitive outer layer is exposed to light, said outer layer becoming ink-receptive and resistant to removal by water in said areas of exposure and said inner layer becoming resistant in said areas to removal by water/polar organic solvent mixtures that are capable of removing said inner layer prior to exposure.

Claim 3

A lithographic plate as set forth in claim 1 wherein said condensation product is a water soluble derivative of the condensation product of 4-diazo-1,1' diphenylamine and formaldehyde.

Claim 4

A lithographic plate as set forth in claim 1 wherein said acrylic resin is an emulsion-polymerized, nonwater redispersible resin.

Claim 5

A lithographic plate as set forth in claim 3 wherein said arcylic resin has a minimum film-forming temperature of between about 8° C. and about 75° C.

Claim 6

A lithographic plate as set forth in claim 4 wherein said acrylic resin has a minimum film-forming temperature of between about 35° C. and about 75° C.

Claim 7

A lithographic plate as set forth in claim 1 wherein said metal support is aluminum.

Claim 8

A lithographic plate as set forth in claim 6 wherein said aluminum support is anodized.

Claim 9

A lithographic plate as set forth in claim 6 wherein said aluminum support is grained.

Claim 10

A lithographic plate as set forth in claim 1 wherein said inner layer as applied to the plate is porous.

Claim 11

A lithographic plate as set forth in claim 1 wherein said inner layer as applied to the plate is discontinuous.

Claim 12

A planographic printing plate produced by exposing the plate of claim 1 to actinic light through a photographic negative and removing said coating in the non-light struck areas using a subtractive developer comprising water and a polar organic solvent.

Claim 13

A planographic printing plate comprising: a substrate comprising a metal support and over said support a silicate barrier layer having a water-wettable hydrophilic surface, and an ink-receptive image on the substrate comprising a coating comprised of an inner oleophilic reinforcing layer composition acrylic resin in contact with one surface and a light-reacted outer layer comprising the light induced reaction product of a water-soluble condensation product of an aryl diazo compound and a carbonyl compound, said inner layer having been applied over said substrate in a first coating step and, as initially applied to said substrate, having been subject to removal by a water/polar organic solvent mixture and permeable to penetration by said condensation product, and said light-reacted outer layer being the light reaction product of a light-sensitive water-soluble outer layer comprising said condensation product, said water-soluble outer layer having been applied over said inner layer in a coating step subsequent to said first step and generally overlying said inner layer but sufficiently contiguous with said substrate by penetration of said condensa- tion product through said inner layer so that both the inner and the light-reacted outer layer are anchored to the substrate as a result of exposure of said condensation product to light, said condensation product and inner layer having been removed from the non-light struck areas of the plate by a developing composition comprising water and a polar organic solvent, thereby uncovering said hydrophilic silicate surface in the non-image areas of the plate.

Claim 14

A planographic printing plate comprising: a substrate comprising a metal support and over said support a silicate barrier layer having a water-wettable hydrophilic surface, and an ink-receptive image on the substrate comprising a coating comprised of an inner oleophilic reinforcing layer composition acrylic resin in contact with one surface and a light-reacted outer layer comprising the light induced reaction product of a water-soluble condensation product of an aryl diazo compound and a carbonyl compound, said inner layer having been applied over said substrate in a first coating step and, as initially applied to said substrate, having been subject to removal by a water/polar organic solvent mixture and permeable to penetration by said condensation product, and said light-reacted outer layer being the light reaction product of a light-sensitive water-soluble outer layer comprising said condensation product, said water-soluble outer layer having been applied over said inner layer in a coating step subsequent to said first step and generally overlying said inner layer but sufficiently contiguous with said substrate by penetration of said condensa- tion product through said inner layer so that both the inner and the light-reacted outer layer are anchored to the substrate as a result of exposure of said condensation product to light, said condensation product and inner layer having been removed from the non-light struck areas of the plate by a developing composition comprising water and a polar organic solvent, thereby uncovering said hydrophilic silicate surface in the non-image areas of the plate.

Claim 15

A lithographic plate comprising: a substrate comprising a metal support and over said support a silicate barrier having a water-wettable hydrophilic surface, and over said substrate a lithographic coating comprising two layers applied in separate sequential coating steps, said layers comprising: a resilient inner oleophilic nonwater-redispersible reinforcing layer applied in a first coating step and which, as applied to the substrate, is subject to removal by a water/polar organic solvent mixture and permeable to penetration by a light-sensitive diazo resin, said inner layer comprising an oleophilic nonwater-redispersible ink-receptive acrylic resin overlying said substrate and in direct contact with said surface, and a relatively fragile outer water-soluble light-sensitive layer applied in a subsequent step over said inner layer, said outer layer comprising a negative-working light-sensitive condensation product of an aryl diazo compound and a carbonyl compound generally overlying said inner layer but sufficiently contiguous with said substrate by penetration of said condensation product through said inner layer so that both said inner layer and said outer layer become anchored to the substrate in the areas of exposure when the light-sensitive outer layer is exposed to light, said outer layer becoming ink-receptive and resistant to removal by water in said areas of exposure and said inner layer becoming resistant in said areas to removal by water/polar organic solvent mixtures that are capable of removing said inner layer prior to exposure.

Claim 16

A lithographic plate comprising: a substrate comprising a metal support and over said support a silicate barrier having a water-wettable hydrophilic surface, and over said substrate a lithographic coating comprising two layers applied in separate sequential coating steps, said layers comprising: a resilient inner oleophilic nonwater-redispersible reinforcing layer applied in a first coating step and which, as applied to the substrate, is subject to removal by a water/polar organic solvent mixture and permeable to penetration by a light-sensitive diazo resin, said inner layer comprising an oleophilic nonwater-redispersible ink-receptive acrylic resin overlying said substrate and in direct contact with said surface, and a relatively fragile outer water-soluble light-sensitive layer applied in a subsequent step over said inner layer, said outer layer comprising a negative-working light-sensitive condensation product of an aryl diazo compound and a carbonyl compound generally overlying said inner layer but sufficiently contiguous with said substrate by penetration of said condensation product through said inner layer so that both said inner layer and said outer layer become anchored to the substrate in the areas of exposure when the light-sensitive outer layer is exposed to light, said outer layer becoming ink-receptive and resistant to removal by water in said areas of exposure and said inner layer becoming resistant in said areas to removal by water/polar organic solvent mixtures that are capable of removing said inner layer prior to exposure.