# US 4,393,128 A · Light-sensitive lithographic printing plate precursor

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- Number: US 4,393,128 A
- Document ID: US4393128A
- Status: Granted
- Kind: A
- Application number: 06/299,421
- Filed: 1981-09-04
- Granted: 1983-07-12
- Earliest claimed: 1980-09-08
- Assignees: Fuji Photo Film Co., Ltd.
- Inventors: Keisuke Shiba; Sho Nakao; Tadao Toyama
- Web page: https://patentgrep.com/patent/US4393128A

## CPC

- G03F 7/0952: {comprising silver halide or silver salt based image forming systems, e.g. for camera speed exposure}
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

The formation of spots when making a printing plate using a presensitized printing plate comprising a silver halide light-sensitive layer formed on an aluminum support having an aluminum oxide film on the surface directly or over a non-silver light-sensitive intermediate layer is effectively prevented by incorporating a mercapto compound in one of the layers.

## Claims

### Claim 1

A light-sensitive lithographic printing plate precursor comprising an aluminum support having an aluminum oxide film on the surface thereof and having formed thereon a silver halide-containing light-sensitive layer, wherein the mean weight of said aluminum oxide film is at least 1 g/m.sup.2, and at least one layer on said support contains a heterocyclic mercapto compound and the total amount of said compound is at least 1 millimol per mol of silver halide sufficient to prevent the formation of spots during the process of making a printing plate from said light sensitive lithographic printing plate precursor.

### Claim 2 (depends on 1)

A light-sensitive lithographic printing plate precursor as in claim 1 comprising an aluminum support having an aluminum oxide film on the surface and having successively formed thereon a non-silver light-sensitive layer and a silver halide-containing light-sensitive layer, wherein at least one of the non-silver light-sensitive layer and the silver halide-containing light-sensitive layer contains said heterocyclic mercapto compound and the total amount of the heterocyclic mercapto compound contained in said layers is at least 1 millimol per mol of the silver halide sufficient to prevent the formation of spots during the process of making a printing plate from said light sensitive lithographic printing plate precursor.

### Claim 3 (depends on 1, 2)

A light-sensitive lithographic printing plate precursor as in claim 1 or 2, wherein said heterocyclic mercapto compound is selected from the group consisting of mercaptotetrazoles, mercaptotriazoles and mercaptodiazoles.

### Claim 4 (depends on 1)

A light-sensitive lithographic printing prate precursor as in claim 1 ior 2, wherein said heterocyclic mercapto compound is represented by the formula (I), (II), (III), or (IV): ##STR2## wherein M represents a hydrogen atom or an alkali metal atom; A represents an aryl group or a substituted aryl group; R represents a hydrogen atom, an alkyl group, or a substituted alkyl group; Z represents an atomic group completing an aromatic ring which may be substituted; Y represents a divalent hetero atom; and Q represents --SM, an amino group, an alkylamino group, an --SR group, or an --OR group.

### Claim 5 (depends on 4)

A light-sensitive lithographic printing plate precursor as in claim 4, wherein said heterocyclic mercapto compound can be represented by the formula (I).

### Claim 6 (depends on 4)

A light-sensitive lithographic printing plate precursor as in claim 4, wherein said heterocyclic mercapto compound can be represented by the formula (IV).

### Claim 7 (depends on 1, 2)

A light-sensitive lithographic printing plate precursor as in claim 1 or 2, wherein said heterocyclic mercapto compound is selected from the group consisting of 1-phenyl-5-mercaptotetrazole, 1-(3-pentacarboamidophenyl)-5-mercaptotetrazole, 2-mercapto-5-methylmercapto-1,3,4-thiadiazole, and 2-amino-5-mercapto-1,3,4-thiadiazole.

### Claim 8 (depends on 3)

A light-sensitive lithographic printing plate precursor as in claim 3, wherein said heterocyclic mercapto compound is used in an amount of from 1 to 50 millimoles per mole of silver halide.

### Claim 9 (depends on 1, 2)

A light-sensitive lighographic printing plate precursor as in claim 1 or 2, wherein said heterocyclic mercapto compound is used in an amount of from 1 to 20 millimoles per mole of silver halide.

### Claim 10 (depends on 1)

A light-sensitive lithographic printing plate precursor as in claim 1 wherein said silver halide-containing light-sensitive layer is coated at a dry coverage of from about 1 to 10 g/m.sup.2.

### Claim 11 (depends on 2)

A light-sensitive lithographic printing plate precursor as in claim 2, wherein said silver halide-containing light-sensitive layer is coated at a dry coverage of from about 1 to 10 g/m.sup.2 and said non-silver light-sensitive is coated at a dry coverage of from about 0.1 to 5 g/m.sup.2 .