JP2910951B2 - Lithographic printing plate - 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, and more particularly to a lithographic printing plate which does not cause stains around a printed material and is particularly 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 obtained by subjecting an aluminum support to a surface roughening, anodizing, and hydrophilizing treatments, and then providing a photosensitive layer. In use, a required original film is placed on the photosensitive layer. After irradiating with active light such as ultraviolet light, and then subjected to a development treatment, it can be provided as a printing plate.

However, in the case of a conventional lithographic printing plate produced in this way, when printing is continuously performed on a roll of paper using a rotary press such as newspaper printing, the width of the paper is limited. Due to the small width of the printing plate, the printing ink adhering to the edges of the printing plate is transferred to the paper, which inevitably appears as direct stains on the edges of the newspaper.

As a method for preventing such contamination, for example, a method has been proposed in which a corner of an end of an aluminum support is scraped off with a file or the like (Japanese Patent Publication No. 57-4675).
Although this method is certainly effective when the number of copies is increased, the effect is hardly recognized in the initial stage of printing (for example, 10,000 copies or less in newspaper printing).

Further, in a PS plate material in which a photosensitive layer is provided on an aluminum support having a hydrophilic surface, an end of the support is subjected to desensitization before or after performing image forming exposure and development. A method has also been proposed,
In this case, although the effect is surely obtained at the beginning of printing, the desensitizing effect gradually decreases with the increase in the number of prints, resulting in the generation of stains. There is.

[0006]

SUMMARY OF THE INVENTION The present invention provides a lithographic printing plate suitable for newspaper printing which does not cause stains in the periphery of printed matter stably even at the beginning of printing or even when the number of prints is increased. It is intended to provide a printing plate.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a lithographic printing plate having the above-mentioned preferable properties. A photosensitive layer is provided on the body, and a notch is provided according to specific conditions along two or four opposite edges of the body, and the photosensitive layer is subjected to image forming exposure and development processing. Before or after, it has been found that the object can be achieved by desensitizing the ends, and the present invention has been completed based on this finding.

That is, according to the present invention, two sides or four sides of a rectangular aluminum plate having an anodized film formed on its surface are cut using a slitter to form an anodized film along the corners of the edge. A covered upper surface notch was provided, a photosensitive layer was laminated on an aluminum support having an angle θ formed by the surface of the notch with respect to the surface of the aluminum plate of 5 ° or more, and an end portion was subjected to desensitization treatment. Thereafter, a lithographic printing plate obtained by subjecting the photosensitive layer to image forming exposure and development,
By cutting the opposite two sides or four sides of the square aluminum plate having the anodic oxide film formed on the surface using a slitter, a top notch is provided along the corner of the rim, the surface of which is covered with the anodic oxide film, A photosensitive layer is laminated on an aluminum support having an angle θ formed by the surface of the notch with respect to the surface of the aluminum plate of 5 ° or more, and the photosensitive layer is subjected to image forming exposure and development, and then to an end portion. A lithographic printing plate obtained by desensitizing the surface of a rectangular aluminum plate having an anodized film formed on a surface thereof and provided with a photosensitive layer. An upper surface notch whose surface is covered with an anodic oxide film is provided along the portion, the angle θ formed by the surface of the notch with respect to the surface of the aluminum plate is 5 ° or more, and the end portion is desensitized. , The photosensitive layer By slitting two or four opposite sides of a lithographic printing plate that has been subjected to image forming exposure and development processing, and a rectangular aluminum plate provided with a photosensitive layer on the surface of which an anodic oxide film has been formed, using a slitter An upper surface notch whose surface is covered with an anodic oxide film is provided along the corner of the edge, and the angle θ formed by the surface of the notch with the surface of the aluminum plate is 5 ° or more, and image formation on the photosensitive layer is performed. The present invention provides a lithographic printing plate obtained by subjecting edges to desensitization after exposure and development.

In the present invention, an aluminum support having an anodized film formed on the surface of an aluminum plate, or an aluminum plate having an anodized film formed on the surface thereof and a photosensitive layer laminated thereon, that is, on the support A photosensitive layer is used as a raw material. As this aluminum plate, any one can be selected and used from those conventionally used for PS plate materials, and a plate having a square shape such as a square or a rectangle is used.
It is provided in sheet or roll form.

The aluminum support is preferably obtained by subjecting an aluminum plate to a surface roughening treatment and then performing an anodic oxidation treatment. This surface roughening treatment is usually performed after the surface of an aluminum plate is degreased by a known method, and is generally subjected to graining (polishing) by a mechanical method or an electric method, or chemical etching. Or by combining these processes.

The anodic oxidation treatment is usually performed in a sulfuric acid bath, whereby an anodic oxide film is formed on the aluminum substrate surface. After the anodic oxidation treatment is performed in this way, a hydrophilic treatment is performed as necessary.

The photosensitive layer laminated on the anodic oxide film, that is, the photosensitive layer provided on the anodic oxide film is not particularly limited, and is a photosensitive layer conventionally used as a photosensitive layer in PS plate materials. For example, those composed of a diazo resin and a hydrophobic resin, those composed of an o-quinonediazide compound and a novolak resin, those composed of an addition-polymerizable unsaturated monomer, a photopolymerization initiator and an organic polymer compound can be used. . This photosensitive layer is formed by applying a photosensitive solution on the anodic oxide film and drying it.

In the present invention, the above-mentioned raw material is cut to a required size by using a slitter, so that notches are formed along the corners of the facing two or four edges simultaneously with the cutting. This notch is formed such that its surface forms an angle θ of 5 ° or more with the surface of the aluminum plate. If the angle θ is less than 5 °, the effect of preventing the generation of stains around the printed matter cannot be sufficiently exhibited.

In general, a slitter has a different shape of a cut end, that is, a shape of a cutout portion of a lip, depending on conditions such as a clearance of a blade. Notches can be provided. If the gap is less than 10 μm, burrs may be generated on the surface, and if it exceeds 1 mm,
There is a tendency that notches covered with the anodic oxide film cannot be obtained, and burrs are generated on the back surface.

When cutting is performed using another cutter that is usually used, for example, a rotary shear, a flange shear, a down cut shear, or the like, the cut cross section becomes almost vertical, or burrs are generated on the front and back surfaces.

In the present invention, it is necessary that the surface of the notch is covered with an anodic oxide film. When the notch surface is not covered with the anodic oxide film, there is a tendency that the hydrophilicity is insufficient and the printing ink tends to adhere.

In the present invention, when the above-mentioned aluminum support is used as a raw material, a predetermined notch is formed in the aluminum support, and then a photosensitive layer is laminated.

In this manner, a printing plate material provided with a predetermined notch is obtained.

The lithographic printing plate of the present invention may be prepared by subjecting the edge of the thus obtained printing plate material to desensitization treatment and then subjecting the photosensitive layer to image formation exposure and development processing, or the printing plate material. After subjecting the photosensitive layer to image formation exposure and development, the edge is desensitized.

The desensitizing agent used in the desensitizing treatment is not particularly limited, and those conventionally used as desensitizing agents for lithographic printing plates can be used. Examples of such a desensitizing agent include an aqueous solution containing a hydrophilic organic polymer compound and an acidic compound.

Examples of the hydrophilic organic high molecular compound include gum arabic, dextrin, alginate, carboxymethylcellulose, hydroxyethylcellulose, and the like.
Hydroxypropyl methylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide,
Copolymer containing acrylamide unit, polymethacrylic acid, copolymer containing methacrylic acid unit, copolymer of vinyl methyl ether and maleic anhydride, copolymer of vinyl acetate and maleic anhydride, phosphate-modified starch Among them, gum arabic is preferable. These hydrophilic organic polymer compounds may be used alone or in combination of two or more, and the amount thereof is based on the total weight of the desensitizing agent.
Usually, it is selected in the range of 1 to 40% by weight, preferably 5 to 30% by weight.

On the other hand, the acidic compound may be either an organic acid or an inorganic acid, for example, a mineral acid such as phosphoric acid, sulfuric acid, nitric acid, citric acid, tannic acid, malic acid, glacial acetic acid, lactic acid, and oxalic acid. Organic acids such as acid, p-toluenesulfonic acid, and organic phosphonic acid can be mentioned, and among these, phosphoric acid and phosphonic acid are particularly preferable. These acidic compounds also have the effect of enhancing the desensitizing effect. In the present invention, one kind of these acidic compounds may be used, or two or more kinds may be used in combination. The compounding amount is usually 0.01 to 8% by weight based on the total weight of the desensitizing agent. %, Preferably in the range of 0.1 to 5% by weight.

The desensitizing agent may further contain a metal salt of a strong acid. Such metal salts include, for example, sodium salt, potassium salt, magnesium salt, calcium salt and zinc salt, sodium salt, potassium salt, sulfuric acid, magnesium salt, calcium salt and zinc salt, sodium salt of chromic acid, potassium salt Salts, magnesium salts, calcium salts and zinc salts, and sodium and potassium salts of hydrofluoric acid can be mentioned. These metal salts can be used alone or in combination of two or more. The compounding amount is usually selected in the range of 0.01 to 5% by weight based on the total weight of the desensitizing agent.

The desensitizing agent may contain a wetting agent or a surfactant. As the wetting agent, a lower polyhydric alcohol is preferable, for example, ethylene glycol,
Examples thereof include diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, glycerin, sorbitol, and pentaerythritol. Examples of the surfactant include nonionic surfactants such as polyoxyethylene alkyl phenyl ether and polyoxyethylene polyoxypropylene block copolymer, fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates, Anionic surfactants such as dialkylsulfosuccinates, alkylphosphates, and formalin condensate of naphthalenesulfonic acid, betaine-type, glycine-type, alanine-type, and sulfobetaine-type amphoteric surfactants can be used.

These wetting agents and surfactants can be contained in an amount of preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the desensitizing agent.

The desensitizing agent thus obtained is applied to the end face before or after image formation exposure and development processing, but when applied after development processing, it is applied immediately after development processing. The gum solution may be applied after the gum solution has been applied, or the gum solution may be used in combination with a desensitizing agent. When storing for a long period of time, care must be taken because the image area is rendered insensitive to oil.

The desensitizing agent has a weight of the coating film after drying of 0.1.
It is effective to apply in a range of 1 to 50 g / m ² . As an application method, for example, a brush, a sponge,
A method using a roller or a method of applying by spraying can be used, but a method of applying a desensitizing agent to the downstream side of the developing and gum processing steps of a developing device that is commercially available as a PS plate processor can be used. The use of the means is advantageous because the processing can be performed consistently. The applied end varies depending on the form of printing. If only one end of the printing plate is to be the printing surface, the desensitizing agent may be applied only to one end of the printing plate. As a result, it is advantageous to apply the coating to two opposite ends, more preferably the outer peripheral end.

The above-mentioned image forming exposure and development processing method is usually such that a desired original film is brought into vacuum contact with the surface of a photosensitive layer of a printing plate material, and this is selectively irradiated with active light such as ultraviolet light. A method is used in which a difference in solubility with respect to a developing solution is caused between an irradiated portion and a non-irradiated portion, and then development processing is performed to form a relief image corresponding to the original film.

[0029]

The planographic printing plate of the present invention does not cause stains around the printed matter stably even at the beginning of printing or even when the number of copies is increased, and is particularly suitable for newspaper printing. Can be

[0030]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example A coil-shaped thickness of 0.3 mm and a width of 12
A 00 mm aluminum plate was degreased with an aqueous sodium phosphate solution, electropolished at a current density of 3 A / dm ^{2 in} a hydrochloric acid bath, and then anodized in a sulfuric acid bath to form an anodized film on the surface. Was formed.

After the anodizing treatment, the substrate is sufficiently washed with water and dried, and then, on this aluminum support, naphthoquinone-
A photosensitive solution comprising 2.5 g of an esterified product of 1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin, 5 g of cresol-formaldehyde resin, 0.15 g of t-butylphenol-formaldehyde resin, 40 g of methyl ethyl ketone and 50 g of cyclohexanone, Coating was performed so that the film thickness after drying was 2 g / m ^2, and then drying was performed at 100 ° C. for 2 minutes to prepare a positive PS plate material.

Next, the PS plate material thus obtained was cut into a size of 1099 mm × 400 mm by a slitter to prepare a sample (a), and further cut into a size of 1099 mm × 400 mm by a down cut shear. The sample (b) was cut.

For each of the plate materials (a) and (b), the photosensitive layer was subjected to image forming exposure, and then subjected to JIS 3
No. 50 g sodium hydroxide, 30 g of a 40 wt% aqueous solution of potassium hydroxide and 1 liter of water, and then washed with water. A) and (B) were prepared.

When the vicinity of the end face of each of these plates was enlarged and observed, the printing plate (A) had an angle θ of 40 ° between the notch surface and the aluminum plate surface, whereas the printing plate (B) had a surface Burrs were occurring on the surface.

For each of the printing plates (A) and (B), 2 g of polyacrylamide and 10% of 85% by weight phosphoric acid were used.
g, 70 g of water and 25 g of isopropyl alcohol were applied to the end face with a sponge and dried to prepare printing plates (A ') and (B').

Using the printing plates (A), (B), (A ') and (B'), newspaper printing was performed in the same manner as in Example 1. Table 1 shows the presence or absence of the occurrence of linear dirt around the newspaper.

[0038]

[Table 1]

From the above results, it can be seen that the lithographic printing plate of the present invention has no stain on the periphery of the printed matter from the start of printing until printing of a large number of copies.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-B-57-46754 (JP, B2) JP-B 62-61946 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B41N 1/08 B41N 3/03 G03F 7/00

Claims (4)

(57) [Claims] 1. An upper surface whose surface is covered with an anodized film along a corner of a rim by cutting two opposite sides or four sides of a rectangular aluminum plate having an anodized film formed on the surface using a slitter. A notch is provided, a photosensitive layer is laminated on an aluminum support having an angle θ between the surface of the notch and the surface of the aluminum plate of 5 ° or more, and an end portion is desensitized. A lithographic printing plate obtained by subjecting a layer to image forming exposure and development. 2. An upper surface whose surface is covered with an anodized film along a corner of a rim by cutting using a slitter two opposite sides or four sides of a rectangular aluminum plate having an anodized film formed on the surface. A notch is provided, a photosensitive layer is laminated on an aluminum support having an angle θ formed by the surface of the notch with respect to the surface of the aluminum plate of 5 ° or more, and the photosensitive layer is subjected to image forming exposure and development processing. After that, a lithographic printing plate with edges desensitized. 3. An aluminum oxide film is formed on the surface, and two opposite sides or four sides of a rectangular aluminum plate provided with a photosensitive layer are cut using a slitter to form an anode along the corner of the edge. An upper surface notch portion covered with an oxide film is provided, an angle θ formed by the surface of the notch portion with respect to the surface of the aluminum plate is set to 5 ° or more, and an end portion is desensitized, and then an image is formed on the photosensitive layer. A lithographic printing plate that has been exposed and developed. 4. A two-sided or four-sided opposing side of a rectangular aluminum plate having a photosensitive layer provided on an anodic oxide film formed on a surface thereof is cut using a slitter to form an anode along a corner of the edge. An upper surface notch covered with an oxide film is provided, and the angle θ formed by the surface of the notch with respect to the surface of the aluminum plate is set to 5 ° or more. A lithographic printing plate whose parts are desensitized.