Presensitized planographic printing plate

Claim 2

The presensitized printing plate of claim 1 in which said oxide is titanium dioxide.

Claim 3

The presensitized printing plate of claim 1 in which said developing agent is 4-phenyl catechol and said oxide is zinc oxide.

Claim 4

The presensitized printing plate of claim 4 in which said silver halide is silver chloride and said 4-phenyl catechol is in said emulsion layer.

Claim 5

The presensitized printing plate of claim 1 in which said silver halide is silver chloride and said developing agent is 4-phenyl catechol which is contained in said layer between said emulsion layer and said support.

Claim 6

The presensitized printing plate of claim 1 in which said layer between said emulsion layer and said support contains an antihalation dye.

Claim 7

The presensitized printing plate of claim 1 in which said emulsion is a direct-positive emulsion.

Claim 8

The presensitized printing plate of claim 8 in which said emulsion layer contains grains comprising a central core of silver halide containing centers which promote deposition of photolytic silver and an outer shell covering said core comprising a fogged silver halide that develops to silver without exposure.

Claim 9

The presensitized printing plate of claim 9 in which said developing agent is 4-phenyl catechol and said oxide is titanium dioxide.

Claim 10

The presensitized printing plate of claim 9 in which said developing agent is 4-phenyl catechol and said oxide is zinc oxide.

Claim 11

The presensitized printing plate of claim 10 in which said emulsion layer is a hardened gelatin photographic silver chloride emulsion layer containing grains comprising a central core of silver chloride containing centers which promote deposition of photolytic silver and an outer shell covering said core comprising a fogged silver chloride that develops to silver without exposure and said 4-phenyl catechol is in said emulsion layer.

Claim 12

The presensitized printing plate of claim 9 in which said emulsion has adsorbed to the fogged grains a halogen-accepting compound having an anodic polarographic halfwave potential less than 0.85 and a cathodic polarographic halfwave potential which is more negative than -1.0.

Claim 13

The presensitized printing plate of claim 13 in which said halogen-accepting compound is a merocyanine dye.

Claim 14

The presensitized printing plate of claim 13 in which said emulsion also contains a sulfonated compound having the formula: R-SO3M wherein R represents a polynuclear aromatic group and M represents a hydrogen atom or a water-soluble cation salt group.

Claim 15

A process which comprises (a) exposing to a subject a presensitized printing plate comprising a support, a hardened gelatin photographic silver halide emulsion layer, and between said emulsion layer and said support, a layer containing an oxide of titanium or zinc and having an average Reflectance of at least 60 percent over wavelengths in the visible region of the spectrum in the range of about 420 to about 500 millimicrons and (b) developing the emulsion layer with a polyhydroxybenzene developing agent which is a halogen suBstituted, phenyl substituted or two-six carbon atoms containing alkyl substituted polyhydroxybenzene developing agent and which renders gelatin oleophilic in developed areas.

Claim 16

The process of claim 16 wherein said silver halide is silver chloride, said developing agent is 4-phenyl catechol which is contained in said layer between said emulsion layer and said support, and said developing step (b) is accomplished by contacting said exposed emulsion layer with an alkaline solution.

Claim 17

The process of claim 16 wherein said printing plate is a positive-working presensitized printing plate comprising a support, a hardened gelatin photographic emulsion layer containing grains comprising a central core of photographic silver halide containing centers which promote deposition of photolytic silver and an outer shell covering said core comprising a fogged photographic silver halide that develops to silver without exposure.

Claim 18

The process of claim 18 which includes step (c) inking the developed areas with greasy printing ink and printing therefrom in a lithographic printing press.

Claim 19

The process of claim 18 wherein said emulsion has adsorbed to the fogged grains a halogen-accepting compound having an anodic polarographic halfwave potential which is more negative than -1.0.

Claim 20

The process of claim 20 wherein said halogen-accepting compound is a merocyanine dye.

Claim 21

The process of claim 20 wherein said emulsion also contains a sulfonated compound having the formula: R-SO3M wherein R represents a polynuclear aromatic group and M represents a hydrogen atom or a water-soluble cation salt group.