JPH08171211A - Lithographic printing plate processing method - Google Patents

Abstract

PURPOSE: To improve ink receptivity by carrying out treatment with a plate surface treating soln. contg. one or more kinds of silicones after development. CONSTITUTION: Treatment is carried out with a plate surface treating soln. contg. one or more kinds of silicones after development. The silicones are, e.g. straight silicones such as dimethylsilicone and methylphenylsilicone and modified silicones each having an introduced org. group such as alkyl modified, amino modified, polyether modified, epoxy modified, mercapto modified and higher fatty acid ester modified silicones but modified silicone is preferably used. Polyether modified silicone is especially preferable because the plate surface treating soln. contg. the silicone is excellent in aging stability. Silicones are added to a neutralizing soln. or an etching soln. by 3-50g/l, preferably 5-30g/l.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for improving the ink acceptability of an image area at the start of printing in a lithographic printing plate which uses image silver as the ink acceptability.

[0002]

2. Description of the Related Art A lithographic printing plate supplies both water and ink to a plate surface to selectively receive a coloring ink in an image area and water in a non-image area, for example, an ink on the image. Printing is performed by transferring to a non-printing material such as paper. Therefore, in order to obtain a good printed matter, the difference in the lipophilicity and hydrophilicity of the surface of the image area and the non-image area is sufficiently large, and when applying water and ink, the image area accepts a sufficient amount of ink, It is necessary that the non-image area does not accept ink at all.

Lithographic printing plates that utilize image silver as an ink-receptive material include US Pat. Nos. 3,721,559 and 3,490,905.
No., No. 3385701, No. 3814603, No. 3454398,
Nos. 3764323, 3099209, JP-B-48-30562, JP-B-44-27242, JP-A-53-21602, JP-A-53-9603 and the like.

The plate-making method of the lithographic printing plate using the above-mentioned silver halide emulsion as ink-accepting silver is simple, reliable and quick, can be automated and has high sensitivity,
It has the features of high resolution and high image reproducibility, but it is more lipophilic between the image and non-image areas than printing plates (PS plates), which are realized from organic colloids such as diazo photosensitive materials. And the difference in hydrophilicity was not sufficiently large.

In order to obtain a good printed matter immediately after the start of printing, it is required that the image portion has high lipophilicity and the non-image portion has high hydrophilicity.

In order to overcome such drawbacks, Japanese Patent Publication No. 48-2
No. 9723, JP-A-58-127928, and the like, a method for improving the ink acceptability by acting on a silver image before printing a compound having a mercapto group or a thione group is shown. That is, the mercapto group or the like of the compound is adsorbed on the silver image, the hydrophobic region of the compound covers the silver image, and the difference in lipophilicity and hydrophilicity between the imaged part and the non-imaged part becomes relatively large. Conceivable.

However, when the above-mentioned compound having a mercapto group is used, the lipophilicity of the image area is improved, but the hydrophilicity of the non-image area is lowered, which causes a background stain in the printed matter. It causes it. Therefore, there has been a strong demand for a method of improving the ink acceptability of the image area without lowering the hydrophilicity of the non-image area.

On the other hand, in recent years, due to problems with the natural environment of photographic processing effluents, problems with a large amount of photographic processing effluents stored by processors, and costs associated with the disposal of effluents, processing systems with reduced photographic processing effluents have been developed. There is. For example, JP-A-4-307245, 4-307246, and 5-
No. 289343 and No. 5-289344, a method of coating and supplying a developing solution in an amount necessary for developing a lithographic printing plate only to the plate surface, and Japanese Patent Application No. 5-334028 are dipped in a small processing tank. Meanwhile, a so-called dip coating treatment method of coating and treating a treatment liquid has been proposed.

However, in a printing plate processed by a processing method having these coating mechanisms (hereinafter referred to as a coating processing method), a developing solution and a neutralizing solution undergo a neutralization reaction on the plate surface, and a neutralization reaction occurs. Since the salt formed in 1 covers the image silver, the ink acceptability is extremely poor compared to the conventional immersion treatment method,
The ink acceptability was not improved by the method of improving the ink acceptability by acting on the silver image before printing the compound having a mercapto group or thione group.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the ink receptivity of an image portion in a lithographic printing plate that utilizes a silver image as the ink receptivity without deteriorating the hydrophilicity of the non-image portion. That is. Another object of the present invention is to dramatically improve the ink acceptability of the planographic printing plate processed by the coating method.

The above-mentioned object of the present invention is achieved in a lithographic printing plate utilizing image silver as an ink-receptive material, after the development treatment, it is treated with a plate surface treatment solution containing at least one kind of silicones. Was done.

Examples of silicones used in the present invention include straight silicones such as dimethyl silicone and methylphenyl silicone, organic groups such as alkyl modified, amino modified, polyether modified, epoxy modified, mercapto modified and higher fatty acid ester modified. However, the present invention is not limited to these. Modified silicones are preferable, and polyether-modified silicones are particularly preferable because they have excellent stability over time when contained in a plate surface treatment liquid.

The silicones are classified into oil type, emulsion type and solution type, preferably emulsion type or solution type. These silicones include Shin-Etsu Silicone Polon-MF-14Ec (amino-modified silicone), KM-870 (alkyl-modified silicone), KF-352 (polyether-modified silicone), and other modified silicones. Toray Dow Corning Silicone Co., Ltd.,
It is commercially available from Toshiba Silicone Co., Ltd.

The structure of the modified silicone used in the present invention can be any structure of side chain type, both terminal type, one terminal type, and both side chain terminal type depending on the number and position of the introduced organic groups.

The plate surface treating solution of the present invention is a neutralizing solution (stabilizing solution) and a plate surface treating solution (etching solution) used immediately before the start of printing.

The addition amount of the silicones used in the neutralizing solution and the etching solution of the present invention is 3 to 50 g / l, preferably 5 to 30 g / l. Further, the compounds may be used in combination of two or more kinds. After that, other compounds and the like are added to the mixed solution, if necessary, to prepare.

In addition to the above compounds, buffers, preservatives, preservatives, and other commonly used neutralizing solutions and etchants
A wetting agent, a surfactant and the like can be mixed. For example, an inorganic acid such as phosphoric acid or sulfuric acid or an organic acid such as succinic acid or propionic acid is used as the buffering agent, and the pH is kept at 5 to 7. Further, a complexing agent such as iminodiacetic acid or ethylenediaminetetraacetic acid can be mixed. Inorganic fine particles such as colloidal silica can also be mixed in a range that does not inhibit the action of the compound.

A compound having a mercapto group or a thione group can also be mixed in a range that does not reduce the hydrophilicity of the non-image area.

Specific examples of such compounds include 2-mercapto-4-phenylimidazole, 1,3-dibenzylimidazolidine-2-thione and 2-mercapto-4-.
Phenylthiazole, 2-mercapto4,5-diphenyloxazole, 3-mercapto-4-acetamide-5
-Heptyl-1,2,4-triazole, 2-mercapto-5-n-heptyl-oxadiazole, 5-mercapto-1-phenyltetrazole, 2-mercapto-5
-Nitropyridine, 2-mercapto-4,6-diphenyl-1,3,5-triazine, 1,5-dimercapto-
3,7-Diphenyl-s-triazolino [1,2-a]
Examples thereof include, but are not limited to, -s-triazoline.

Regarding a lithographic printing plate utilizing image silver as an ink receiving property, a silver source may be contained in a printing original plate itself or a silver source for a printing original plate having an image receiving layer by a silver salt diffusion transfer method. Alternatively, it may be provided on another negative sheet.

The silver halide emulsion comprises silver chloride, silver bromide,
Any of silver chlorobromide and those containing iodide may be used, and gelatin is preferably used as the binder, but a part or all of gelatin may be replaced with another colloidal substance such as casein, albumin, or a cellulose derivative. Good. 0.5 to 7g of silver halide converted to silver nitrate
/ M ² , and the binder can be usually used in the range of 0.5 to 10 g / m ² .

The silver halide emulsion can be produced by a method known in the ordinary photographic industry. In particular, the manufacturing method for use in a printing plate is described in the above-mentioned publicly known patent documents and can be referred to.

The lithographic printing plate used in the present invention is generally treated with an alkali developing solution after imagewise exposure. As such a developing solution, any developing solution such as a normal photographic developing solution containing a developing agent such as hydroquinone, a silver diffusion transfer method developing solution containing hypo, etc., or an activated alkali developing solution can be used.

The coating treatment method described in the present invention is different from the conventional dipping treatment, that is, the treatment method in which the lithographic printing plate is sufficiently dipped in the treatment liquid. This is a treatment method of applying a predetermined amount of liquid. For example, JP-A-48-76603 and JP-A-57-1155.
No. 49, No. 4-307245, No. 4-307246
No. 5,289,343, No. 5-289344, etc., roller coating, liquid coating, spray coating, etc .; And a so-called dipping coating method in which the photosensitive material is coated with the above-mentioned processing liquid.

When the development and neutralization treatments are carried out by such a coating treatment system, particularly when the neutralization treatment is carried out by the coating treatment system, salts produced by the neutralization reaction with the developer remain on the plate surface. However, this salt markedly deteriorated the ink acceptability. Therefore, the lithographic printing plate treated by the coating treatment method has a very low degree of improvement in ink acceptability by the conventional method for improving the ink acceptability as compared with the dipping-treated lithographic printing plate.

By using the above-described treatment method of the present invention as the coating treatment method, the ink acceptability is remarkably improved. In this case, the neutralizing solution may contain silicones, or may be treated with a neutralizing solution containing no silicones and then with an etchant containing silicones. Absent. The method for treating the etchant is not particularly limited. Usually, a method of wiping the plate surface with absorbent cotton or the like is used.

[0027]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 A matting layer containing silica particles having an average particle size of 5 μ was provided on one surface of a polyester film support which had been subjected to a subbing treatment, and an amount of carbon having an optical reflectance of 3% was provided on the opposite surface. 20% by weight of photographic gelatin, including black
Of an anti-halation undercoat layer containing silica powder having an average particle size of 7 μm (adjusted to pH 4) and silica powder having an average particle size of 7 μm after being chemically sensitized to 5% by weight of photographic gelatin.
And a high-sensitivity silver chloride emulsion spectrally sensitized (adjusted to pH 4) in the green range.

The gelatin of the undercoat layer was 3.5 g / m ² , the gelatin of the emulsion layer was 0.8 g / m ² , and the silver halide equivalent to silver nitrate was 1.0 g / m ² . The undercoat layer and the emulsion layer contain formalin as a hardening agent in an amount of 5.0 mg / g gelatin with respect to gelatin. After drying 4
After heating at 0 ° C. for 14 days, it was placed on the emulsion layer.
No. 103104 Example 2 plate No. The core coating solution described in 31 is applied and dried to produce a lithographic printing plate. The silver halide emulsion is 4 × per mol of silver halide during physical ripening.
10 ⁻⁶ mol of rhodium chloride was added, and the average particle size was 0.4 μm.

The lithographic printing plate precursor thus obtained was image-exposed with a plate-making camera having an image reversing mechanism, and was subjected to immersion treatment with the following developing solution (use solution) and neutralizing solution. Development process is 3
The neutralization treatment is performed at 0 ° C. for 30 seconds and at 25 ° C. for 15 seconds. <Developer> Sodium hydroxide 24 g Potassium hydroxide 8 g Anhydrous sodium sulfite 50 g 2-Methyl-2-amino-1-propanol 30 g Water to make 1 liter.

<Neutralization liquid> Phosphoric acid 1.2 g Potassium monophosphate 25 g Anhydrous sodium sulfite 2.5 g Ethylene glycol 10 g Compound A 5 g Water is adjusted to 1 liter (adjusted to pH 6). Compound A is as shown in Table 1.

The printing plate prepared by the above operation is set on the offset printing machine, and the RYOBI3200C is set on the printing machine.
D (Ryobi offset printing machine trademark), ink is
AB-Dick3-1012 black ink was used for the ink acceptability test, Dainippon Ink F Gloss Purple ink was used for the stain resistance test, and SLM-OD30 (a moisturizing liquid manufactured by Mitsubishi Paper Mills) was used as the moisturizing liquid. Printing was performed by etching with the same dampening liquid.

[0033]

[Table 1]

The compound B of the present invention 4 is 2-mercapto-5-n.
-Heptyloxadiazole, 0.2 g / l was added. In Comparative Example 2, propylene glycol (50 g / l) and compound B (0.3 g / l) were added to the above stabilizing solution.

The ink acceptability is evaluated by the number of prints until a good printed matter is obtained by starting to feed the paper at the same time when the ink is brought into contact with the plate surface, and the stainability is evaluated by the stain on the printed matter after printing 1000 sheets. The degree was evaluated according to the following criteria. ◯: No dirt is generated. Δ: Partial or light stain is generated. X: Light stain is generated on the entire surface. The printing results are shown in Table 2.

[0036]

[Table 2]

From the results, it was possible to improve the ink acceptability without lowering the hydrophilicity of the non-image area.

Example 2 A printing plate prepared by the same procedure as in Example 1 was etched using the following etchant except that the stabilizer obtained by removing the compound A from the stabilizer in Example 1 was used. The same printing test as 1 was performed. <Etching solution> Citric acid 1 g Sodium citrate 2 g Polyethylene glycol 29 g Colloidal silica (20% solution) 11 g Compound A 20 g Water to make 1 liter.

As the compound A, the same compound as used in Example 1 was used, and in the comparison 1, the liquid without addition of the compound A was used.
In Comparative Example 2, the solution in which 1.0 g / l of the compound B of Example 1 was added instead of the compound A was used.

Both the ink acceptability and stain resistance tests gave the same results as in Example 1.

Example 3 Japanese Patent Application No. 5-33402 as a processing apparatus having a coating mechanism.
The processor described in the Example of No. 8 was used. The plate making process was carried out using the developing solution and the stabilizing solution described in Example 1 for the developing section and the stabilizing section, respectively. The printing test and the evaluation method were in accordance with Example 1. The results are shown in Table 3.

[0042]

[Table 3]

From the above results, when treated by the coating method, the neutralizing liquid containing the silicone of the present invention dramatically improves the ink acceptability as compared with the conventionally used comparative neutralizing liquid. I understand that In particular, the effect of improving the ink acceptability of the lithographic printing plate, which has been subjected to the plate-making process by the processing apparatus having the coating mechanism, was recognized as compared with the conventionally known compounds having a mercapto or thione group.
From the stability of the liquid, it was found that the polyether-modified silicone is particularly effective.

Example 4 A printing plate prepared by the same procedure as in Example 3 was etched using the etching solution of Example 2 except that the neutralization solution obtained by removing the compound A from the neutralization solution of Example 3 was used. Then, the same printing test as in Example 1 was performed.

As the compound A, the same compound as used in Example 1 was used, and in the comparison 1, the liquid without addition of the compound A was used.
In Comparative Example 2, the solution in which 1.0 g / l of the compound B of Example 1 was added instead of the compound A was used.

Both the ink acceptability and stain resistance tests gave the same results as in Example 3.

[0047]

According to the embodiments of the present invention, in a lithographic printing plate that uses a silver image as the ink acceptability, it is possible to improve the ink acceptability without lowering the hydrophilicity of the non-image area. I can. In particular, in the case of processing by a coating method having a coating mechanism, ink acceptability is dramatically improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yoshida 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills, Ltd.

Claims (4)

[Claims] 1. A method for treating a lithographic printing plate which utilizes image silver as an ink accepting agent, which is characterized in that after development treatment, it is treated with a plate surface treatment liquid containing at least one kind of silicone. 2. A processing method of applying a neutralizing solution after development processing using a processing apparatus having a coating mechanism, wherein the neutralizing solution contains at least one kind of silicone, and image silver is provided. A method of processing a lithographic printing plate used as ink acceptability. 3. An image silver ink, characterized in that after the developing treatment, a neutralizing liquid is applied using a treating apparatus having a coating mechanism and then treated with an etchant containing at least one kind of silicone. Lithographic printing plate processing method used for acceptability. 4. The method according to claim 1, 2 or 3, wherein the silicone is a polyether-modified silicone.