Sensitized paper plates for producing planographic printing forms

Claim 2

A sensitized plate according to claim 1, said layer being adhered by said binder directly to the paper surface of said support.

Claim 3

A sensitized plate according to claim 1, said layer having said diazonium salt applied thereto in admixture with an acidic stabilizer comprising a mixture of boric acid and tartric acid in which the boric acid predominates.

Claim 4

A sensitized plate according to claim 1, said cross-linking agent comprising glyoxal provided initially in said layer in admixture with said polyvinyl alcohol.

Claim 5

A sensitized plate according to claim 1, said salt being a benzoylamino-dibutoxy-benzene diazonium salt, a phenylthio-benzene diazonium salt or a bis-(acetoxy-ethyl) amino-chlorophenoxy-chloro-benzene diazonium salt.

Claim 6

A sensitized plate according to claim 1, said salt being a dimethylamino-chloro-(4'' methyl-phenyl)thio-benzene diazonium salt.

Claim 7

A sensitized plate according to claim 1, said filler consisting principally of pigmentary titanium dioxide, diatomaceous earth or clay or a mixture thereof.

Claim 8

A sensitized plate according to claim 1, said filler consisting principally of pigmentary titanium dioxide diatomaceous earth or clay or a mixture thereof in admixture with a minor proportion of alumina, silica, water glass or stannic anhydride or a mixture thereof.

Claim 9

A sensitized plate for conversion into a planographic printing form, comprising a paper support carrying thereon a planographic coating consisting essentially of a layer of a water-insolubilized hydrophilic organic binder having a finely divided inorganic filler dispersed therein and a light-sensitive diazo compound applied to said layer in admixture with an acidic stabilizer, said layer containing, by weight, about 4-6 parts of said filler to 1 part of said binder and being adhered by said binder directly to the paper surface of said support, said binder consisting principally of a substantially water-insoluble product of the cross-linking, in situ in said layer, of polyvinyl alcohol having a degree of hydrolysis greater than 98 percent in admixture with glyoxal as a cross-linking agent other than said polyvinyl alcohol itself, said diazo compound being a phenylthio-benzene diazonium salt that has a higher coupling activity in aqueous solution than p-diazo-o-chloro-N,N-dimethyl aniline and that forms an ink-receptive azo dyestuff by coupling with phloroglucinol when said coating is developed with an aqueous buffered phloroglucinol solution having a pH between 4 and 8.

Claim 10

A sensitized plate according to claim 10, said polyvinyl alcohol having been cross-linked to such extent that the water-absorbing capacity of said layer is less than about 6 as measured by the Cobb test.

Claim 11

A sensitized plate according to claim 10, said diazo compound being a dimethylamino-chloro-(4'' methylphenyl)thio-benzene diazonium salt.

Claim 12

A sensitized plate according to claim 10, said filler consisting of principally of pigmentary titanium dioxide, diatomaceous earth or clay or a mixture thereof in admixture with a minor proportion of alumina, silica, water glass or stannic anhydride or a mixture thereof.

Claim 13

A planographic printing form comprising a paper support carrying thereon a planographic coating consisting essentially of a layer of a water-insolubilized hydrophilic organic binder having a finely divided inorganic filler dispersed therein and an image of an oleophilic azo-dyestuff formed on said layer, wherein said binder consists principally of a substantially water-insoluble product of the cross-linking, in situ in said layer, of polyvinyl alcohol having a degree of hydrolysis greater than 98 percent in admixture with glyoxal as a cross-linking agent and said dyestuff is a reactiOn product of a non-polymeric benzene diazonium salt applied to said layer, said salt having a higher coupling activity in aqueous solution than p-diazo-o-chloro-N,N-dimethyl aniline, and phloroglucinol.