JP3031438B2 - Lithographic printing plate material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel lithographic printing plate material, and more particularly, to the occurrence of stains around the printed material since the anodic oxide film on the inner edge of the aluminum support has substantially no cracks. And a plate material that provides a lithographic printing plate that is preferably used for newspaper printing.

[0002]

2. Description of the Related Art As a lithographic printing plate material, a PS plate material having a photosensitive layer provided on an aluminum support is mainly used.
This PS plate material is generally roughened by degreasing and washing a sheet-like or coil-like aluminum support by various methods, then graining (polishing) by a mechanical method or an electrical method, and furthermore, a chemical etching treatment. After the surface treatment, anodizing treatment and, if necessary, hydrophilization treatment, and then providing the photosensitive layer after cutting the support to a size suitable for a desired printing machine, or providing the photosensitive layer , It is created by cutting it to fit its size.
For the cutting process, for example, a rotary shear, a flange shear, a down cut shear, or the like is used. The PS plate material thus obtained can be used as a printing plate by placing a required original film on the photosensitive layer at the time of use, irradiating the film with actinic light such as ultraviolet rays, and then subjecting it to a development treatment.

Meanwhile, in the PS plate material obtained by the above method, cracks occur in the anodic oxide film near the end face of the aluminum support, and as a result, printing is performed using a printing plate obtained from the plate material. When printing, it is unavoidable that the printing ink adheres to the cracks, and especially when printing continuously on roll-shaped paper using a rotary press such as newspaper printing, a printing plate is required for the width of the paper. When the width of the printing plate is small, there is a problem that the printing ink adhering to the edge of the printing plate is transferred to the paper and appears as a linear stain on the edge of the newspaper.

[0004] As a method for preventing such contamination, for example, a method is known in which a corner of an end of an aluminum support is shaved with a file or the like (Japanese Patent Publication No. 57-46754). However, this method does not actually produce the effect immediately after the start of printing, and requires the printing plates to be processed one by one, and is not suitable for mass processing. Have the drawback that the surface of the printing plate may be damaged.

A method of desensitizing the end surface of an aluminum support before performing image forming processing has been disclosed (Japanese Patent Publication No. 62-61946). In this method, the desensitizing processing is performed. When one plate material is manually processed, there is a disadvantage that the desensitizing agent wraps around the photosensitive layer and the back surface of the aluminum support, and the printing plate material does not peel off when these are stacked and packaged. To prevent this, a method of applying a desensitizing agent after stacking in a packaging unit is also conceivable, but in this case, there is a disadvantage that the desensitizing agent permeates between the plate materials and hinders peeling, It has not been put to practical use.

[0006]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a lithographic printing plate material which does not cause stains around the printed matter and can provide a printing plate particularly suitable for newspaper printing. The purpose of this is to provide.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a lithographic printing plate material that provides a printing plate that does not cause the generation of stains around a printed material. After sequentially performing the surface treatment and the anodic oxidation treatment, the lithographic printing plate material provided with the photosensitive layer is cut into a desired shape using a slitter after the anodic oxidation treatment, and then the photosensitive layer is provided. The inventors have found that cracks are not substantially generated in the anodic oxide film on the inner edge of the end face, and that the object can be achieved, and based on this finding, the present invention has been completed.

That is, the present invention is characterized in that a surface of an aluminum support is subjected to a roughening treatment and an anodic oxidation treatment in that order, then cut into a desired shape using a slitter, and then a photosensitive layer is provided. An object of the present invention is to provide a lithographic printing plate material in which substantially no cracks have occurred in the anodic oxide film on the inner edge of the end face of the support.

As the aluminum support used in the planographic printing plate material of the present invention, any one can be selected from those conventionally used for PS plate materials. Any of these may be used.

The lithographic printing plate material of the present invention comprises a photosensitive layer provided on an aluminum support which has been sequentially subjected to a surface roughening treatment and an anodic oxidation treatment. It is necessary that substantially no crack is generated in the anodic oxide film on the inner edge of the end face. If the film has cracks, when printing is performed using a printing plate obtained from the plate material, printing ink adheres to the cracks and is transferred to paper, causing linear stains on printed matter. .

In the present invention, in order to prevent the occurrence of cracks, the surface of the aluminum support is subjected to a roughening treatment and an anodic oxidation treatment sequentially, and then cut into a desired shape using a slitter. Is provided.

The surface of the aluminum support is usually subjected to a roughening treatment after the surface is degreased and washed by a known method.
This surface roughening treatment is generally performed by graining (polishing) by a mechanical method or an electric method, by chemical etching, or by combining these treatments.

The thus roughened aluminum support is anodized in a sulfuric acid bath or the like to form an anodic oxide film on the surface thereof, and then subjected to a hydrophilic treatment as required. After that, it is cut into a desired shape using a slitter. When cutting is performed using another cutter, for example, a rotary shear, a flange shear, a down cut shear, an up cut shear, or the like, cracks easily occur in the anodic oxide film on the inner helicopter on the end face of the support.

After cutting in this manner, a photosensitive layer is provided. The photosensitive layer is not particularly limited.
What is commonly used as a photosensitive layer in an S plate material, for example, one comprising a diazo resin and a hydrophobic resin, one comprising an o-quinonediazide compound and a novolak resin, an addition-polymerizable unsaturated monomer, a photopolymerization initiator and an organic A material composed of a high molecular compound can be used.

In this way, a lithographic printing plate material in which cracks are not substantially generated in the anodic oxide film on the inner edge of the support edge is obtained.

Next, an example of a preferred method for making a printing plate using the plate material of the present invention will be described. First, a desired original film is vacuum-adhered to the surface of the photosensitive layer of the plate material. Active light such as ultraviolet rays is selectively irradiated to cause a difference in solubility between the irradiated portion and the non-irradiated portion with respect to a developing solution, and then subjected to a development process to form a relief image corresponding to the original film. Then, if necessary, a lithographic printing plate is obtained by applying a gumming treatment without causing stains on the periphery of the printed matter.

[0017]

The lithographic printing plate material of the present invention has substantially no cracks in the anodic oxide film on the inner helicopter of the end face of the support. Therefore, the printing plate obtained from this plate material is applied to the periphery of the printed matter. It is suitable for printing on large paper such as newspapers without causing stains.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-19315 (JP, A) JP-A-1-127389 (JP, A) JP-A-59-97146 (JP, A) JP-A-4-193 67992 (JP, A) JP-A-63-256495 (JP, A) JP-B-57-46754 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41N 1/08 B41N 3 / 03

Claims (1)

(57) [Claims] 1. A surface of an aluminum support, which is sequentially subjected to a surface roughening treatment and an anodic oxidation treatment, then cut into a desired shape using a slitter, and then provided with a photosensitive layer. A lithographic printing plate material with substantially no cracks in the anodic oxide film on the inner edge.