Desensitizing solution for lithographic printing plate

Claim 2

A process for preparing a lithographic printing plate which comprises exposing a lithographic printing plate forming material having a photopolymerizable photosensitive layer containing an ethylenically unsaturated compound, developing said exposed material and treating the exposed material with a desensitizing solution comprising a free radical photopolymerization inhibitor, a hydrophilic colloid and water, said free radical photopolymerization inhibitor being present in the desensitizing solution in an amount sufficient to normally prevent selectively the formation of stain on non-imaged areas during printing.

Claim 3

The process of claim 1, wherein said hydrophilic colloid is selected from the group consisting of gum arabic, gelatin, cellulose derivatives, dextrin, shellac, alginates, polyvinyl pyrrolidone, polyvinyl alcohol or derivatives thereof, polyacrylamide or copolymers thereof, acrylic acid copolymers, vinyl methyl ether/maleic anhydride copolymer, vinyl acetate/maleic anhydride copolymer, and styrene/maleic anhydride copolymer.

Claim 4

The process of claim 1, wherein said hydrophilic colloid is present in an amount of about 0.1 to 20 wt%.

Claim 5

The process of claim 1, wherein said polymerization inhibitor is present in an amount of about 0.001 to 20 wt%.

Claim 6

The process of claim 1, wherein said solution additionally comprises a nonionic surfactant or a polyhydroxyalkane.

Claim 7

The process of claim 5, wherein said surfactant or polyhydroxyalkane is present in an amount of about 3 to 30 wt%.

Claim 8

The process of claim 1, wherein said solution additionally comprises an organic solvent.

Claim 9

The process of claim 7, wherein said solvent is present in an amount of about 0.01 to 20 wt%.

Claim 10

The process of claim 1, wherein said solution additionally comprises an anionic surfactant.

Claim 11

The process of claim 9, wherein said anionic surfactant is present in an amount of about 0.1 to 20 wt%.

Claim 12

The process of claim 1, wherein said solution additionally comprises an acetate.

Claim 13

The process of claim 1, wherein said solution additionally comprises at least one compound selected from the group consisting of molybdic acid, boric acid, nitric acid, phosphoric acid, polyphosphoric acid and water-soluble alkali metal salts and ammonium salts thereof.

Claim 14

The process of claim 1, wherein said polymerization inhibitor is a quinone compound, an amine compound, a nitro compound, a nitroso compound, a nitron compound, a phenol, a disulfide, a hydrazine, a mercaptan, a thioether, a dithiocarbamic acid, a sulfene amide, a phosphate, a phosphite, a phosphine, or a borate.

Claim 15

The process of claim 6, wherein said polyhydroxyalkane is a polyalkylene glycol, a polyethylene glycol alkyl ether, a polyethylene glycol alkylphenyl ether, a polyethylene glycol ester, a polyalkanol containing therein three or more hydroxy groups, a phosphoric acid ester of an alkanol, or a phosphoric acid ester of a monohydroxy ether.

Claim 16

The process of claim 1, wherein said desensitizing solution additionally comprises a polyalkylene glycol represented by the formula HO--C z H 2z O) a H wherein z is an integer of 1 to 6 and a is an integer of from 1 to about 500.

Claim 17

The process of claim 1, wherein said hydrophilic colloid is gum arabic.

Claim 18

The process of claim 1, wherein the lithographic printing plate is further subjected to post-exposure.

Claim 19

The process of claim 1, wherein said free radical polymerization inhibitor is selected from the group consisting of quinone compounds, amine compounds, nitro compounds, nitroso compounds, nitron compounds, phenols, disulfides, hydrazines, mercaptans, thioethers, dithiocarbamic acids, sulfene amides, phosphates, phosphites, phosphines, borates and mixtures thereof.

Claim 20

The process of claim 1, wherein the free radical polymerization inhibitor is selected from the group consisting of hydroquinone, p-benzoquinone, chlorobenzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, methyl-p-benzoquinone, o-, m- or p-phenylenediamine, phenyl-β-naphthylamine, diphenylamine, N-N'-diphenyl-p-phenylenediamine, p-hydroxy-diphenylamine, o-, m- or p-dinitrobenzene, 2,4-dinitrotoluene, 1,3,5-trinitrobenzene, 1,3,5-trinitroanisole, 1,3,5-trinitrotoluene, dinitrodurene, o-, m- or p-nitrophenol, 2,4-dinitrophenol, o-, m- or p-nitrophenylcarboxylic acid, o-, m- or p-nitroaniline, 2,4,6-trinitrophenol, nitrosobenzene, methyl-α-nitrosoisopropyl ketone, phenyl-t-butylnitron, pyrogallol, catechol, α- or β-naphthol, tertiary butyl catechol, tertiary butyl phenol, 2,4,6-trimethylphenol, cresol, o-, m- or p-ispropylphenol, 2-amino-4-methylphenol, tetramethylthiuram disulfide, 2,2-benzoylaminodiphenyl disulfide, 2-mercaptoimidazole, 2-mercaptobenzimidazole, zinc diethyl dithiocarbamate, N-oxydiethylene benzotriazole, 2-sulfene amide, tri-n-butyl phosphine, triphenyl phosphite, trimethyl phosphate, p-nitrophenyl acetic acid and triphenyl borate.