JP3311553B2 - Lithographic printing plate processing method - Google Patents

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 receptivity of an image portion at the start of printing in a lithographic printing plate utilizing image silver as ink receptivity.

[0002]

2. Description of the Related Art A lithographic printing plate supplies both water and ink to a plate surface, and selectively receives a colorable ink in an image portion and water in a non-image portion. Printing is performed by transferring the image to a non-printing material such as paper. Therefore, in order to obtain good printed matter, the difference between the lipophilicity and hydrophilicity of the surface of the image area and the non-image area is sufficiently large, and when water and ink are applied, the image area receives a sufficient amount of ink, It is necessary that the non-image part does not receive any ink.

As a lithographic printing plate utilizing image silver with ink receptivity, US Pat. Nos. 3,721,559 and 3,490,905
No. 3857701, 3814603, 3454398,
Nos. 3764323, 3099209, JP-B-48-30562, 44-27242, JP-A-53-21602, and JP-A-53-9603.

[0004] The method of making a lithographic printing plate using the above-described silver halide emulsion and using image silver as ink acceptability is simple, reliable and rapid, can be automated, has high sensitivity,
It has the features of high resolution and high image reproducibility. However, compared to printing plates (PS plates) that are realized from organic colloids such as diazo photosensitive materials, the lipophilicity between the image part and the non-image part is higher. 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 lipophilicity of the image portion is high and the hydrophilicity of the non-image portion is high.

In order to overcome such disadvantages, Japanese Patent Publication No. Sho 48-2
No. 9723, Japanese Patent Application Laid-Open No. 58-127928, etc., show a method of improving the ink receptivity by acting on a silver image before printing a compound having a mercapto group or a thione group. That is, the difference in the lipophilicity and hydrophilicity between the image portion and the non-image portion is such that the mercapto group or the like of the compound is adsorbed on the silver image and the hydrophobic region of the compound covers the silver image. Conceivable.

However, the use of the above-mentioned compound having a mercapto group improves the lipophilicity of the image area, but has the disadvantage of lowering the hydrophilicity of the non-image area. Cause Therefore, there has been a strong demand for a method for improving the ink receptivity of the image area without reducing the hydrophilicity of the non-image area.

On the other hand, in recent years, a processing system with a reduced amount of photographic processing waste liquid has been developed due to a problem with the natural environment of the photographic processing waste liquid, a problem of storing a large amount of photographic processing waste liquid by a processing company, and a problem of cost for processing the waste liquid. I have. For example, JP-A-4-307245, JP-A-4-307246, and JP-A-5-307246
JP-A-289343 and JP-A-5-289344 disclose a method of making a plate by applying and supplying an amount of a developing solution necessary for developing a lithographic printing plate only to the plate surface, and immersing it in a small processing tank in Japanese Patent Application No. 5-33428. A so-called dip coating method has been proposed in which a processing liquid is applied and processed while the coating is performed.

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 the neutralization reaction occurs. Since the salt formed in the above covers the image silver, the ink receptivity is extremely poor compared to the conventional immersion treatment method,
In a method in which a compound having a mercapto group or a thione group acts on a silver image before printing to improve the ink receptivity, the ink receptivity was not improved.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to improve the ink receptivity of an image portion without reducing the hydrophilicity of a non-image portion in a lithographic printing plate utilizing a silver image as the ink receptivity. That is. Another object of the present invention is to dramatically improve the ink receptivity of a lithographic printing plate treated by a coating method.

[0011] The above object of the present invention is to provide a printing method after developing.
Use image silver as ink acceptability
This is achieved by treating a lithographic printing plate treatment solution with a plate treatment solution containing at least one or more silicones.

Examples of the silicones used in the present invention include straight silicones such as dimethyl silicone and methylphenyl silicone, and organic groups such as alkyl-modified, amino-modified, polyether-modified, epoxy-modified, mercapto-modified and higher fatty acid ester-modified. , But is not limited thereto. Modified silicones are preferred, and polyether-modified silicones are particularly preferred because they have excellent temporal stability of the solution when contained in the plate surface treating solution.

The silicones are classified into an oil type, an emulsion type and a solution type, and are preferably an emulsion type or a solution type. These silicones are available from Shin-Etsu Chemical Co., Ltd. as Shin-Etsu Silicone Polon-MF-14Ec (amino-modified silicone), KM-870 (alkyl-modified silicone), and KF-352 (polyether-modified silicone). Toray Dow Corning Silicone Co., Ltd.
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 type depending on the number and position of the organic groups to be introduced.

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

The amount of the silicone used in the neutralizing solution and the etchant of the present invention is 3 to 50 g / l, preferably 5 to 30 g / l. The compounds may be used in combination of two or more. Thereafter, the mixture is prepared by adding other compounds and the like to the mixed solution as needed.

In the neutralizing solution and the etching solution, buffers, preservatives, preservatives and the like generally used in addition to the above-mentioned compounds are used.
Wetting agents and surfactants can be mixed. For example, as a buffer, an inorganic acid such as phosphoric acid or sulfuric acid, or an organic acid such as succinic acid or propionic acid is used to keep the pH at 5 to 7. Further, complexing agents such as iminodiacetic acid and ethylenediaminetetraacetic acid can be mixed. In addition, inorganic fine particles such as colloidal silica can be mixed as long as the action of the compound is not inhibited.

A compound having a mercapto group or a thione group can be mixed as long as the hydrophilicity of the non-image area is not reduced.

Specific examples of such compounds include 2-mercapto-4-phenylimidazole, 1,3-dibenzylimidazolidine-2-thione, 2-mercapto-4-
Phenylthiazole, 2-mercapto-4,5-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]
-S-triazoline and the like, but are not limited thereto.

Regarding a lithographic printing plate utilizing image silver as ink receptivity, a silver supply source for a printing original plate sheet having an image receiving layer by a silver salt diffusion transfer method, even if the silver halide emulsion is contained in the printing original plate itself. May be provided on another negative sheet.

The silver halide emulsion includes silver chloride, silver bromide,
Any of silver chlorobromide and those containing iodide therein may be used, and gelatin is preferable as the binder.A part or all of gelatin may be replaced with another colloidal substance, for example, casein, albumin, a cellulose derivative or the like. Good. Silver halide is 0.5 to 7 g in terms of 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 art. In particular, the production method for use in a printing plate is described in the above-mentioned known patent documents, and can be referred to.

The lithographic printing plate used in the present invention is generally treated with an alkali developer after image exposure. As such a developer, any one of an ordinary photographic developer containing a developing agent such as hydroquinone, a developer of a silver diffusion transfer method containing hypo and the like, and an alkali developer which has been activated can be used.

The coating treatment system described in the present invention is different from the conventional immersion treatment, that is, a treatment method in which a lithographic printing plate is sufficiently immersed in a treatment solution. This is a processing method for 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
Nos. 5,289,343, 5-289344, and the like, and a photosensitive material in a small processing tank described in Japanese Patent Application No. 5-33428. Is dipped and the photosensitive material is coated with the processing liquid described above, such as a so-called dip coating method.

When development and neutralization are performed by such a coating method, particularly when the neutralization processing is performed by a coating method, salts generated by the neutralization reaction with the developer remain on the plate surface. However, these salts significantly deteriorated the ink receptivity. Therefore, in the lithographic printing plate treated by the coating treatment method, the degree of improvement in ink receptivity of the conventional method for improving ink receptivity was extremely lower than that of the lithographic printing plate subjected to immersion treatment.

By using the above-described processing method of the present invention as the coating method, the ink receptivity is remarkably improved. In this case, the neutralizing solution may be made to contain silicones, or after being treated with a neutralizing solution containing no silicones, it may be treated with an etching solution 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 is of course not limited thereto.

Example 1 A matted layer containing silica particles having an average particle size of 5 μm was provided on one side of a polyester film support subjected to a subbing treatment, and an amount of carbon having an optical reflectance of 3% was provided on the opposite side. Including black, 20% by weight based on photographic gelatin
An anti-halation undercoat layer (adjusted to pH 4) containing silica powder having an average particle size of 7 μm, and 5% by weight of silica powder having an average particle size of 7 μm after chemical sensitization with respect to gelatin for photography.
And a high-sensitivity silver chloride emulsion (adjusted to pH 4) spectrally sensitized to the green sensitive region containing the above-mentioned ratio.

The gelatin of the undercoat layer was applied at a ratio of 3.5 g / m ² , the gelatin of the emulsion layer was applied at a ratio of 0.8 g / m ² , and the silver halide was converted to silver halide at a ratio of 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 relative to gelatin. 4 after drying
After heating at 0 ° C. for 14 days,
No. 103104, plate No. 2 of Example 2. A lithographic printing plate is manufactured by applying and drying the core coating solution described in No. 31. The silver halide emulsion was 4 × per mole of silver halide during physical ripening.
It had 10 ^-6 mol of rhodium chloride added and had an average particle size of 0.4μ.

The lithographic printing plate precursor thus obtained was image-exposed with a plate making camera having an image reversing mechanism, and immersed in the following developing solution (used solution) and neutralizing solution. Development processing is 3
The neutralization treatment is carried out at 0 ° C. for 30 seconds and at 25 ° C. for 15 seconds. <Developer> 24 g of sodium hydroxide 8 g of potassium hydroxide 50 g of anhydrous sodium sulfite 30 g of 2-methyl-2-amino-1-propanol 30 g Make up to 1 l with water.

<Neutralized solution> 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 in an offset printing press, and the printing press is used for RYOBI3200C.
D (Ryobi brand offset printing press), ink is
AB-Dick 3-1012 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 humidifier manufactured by Mitsubishi Paper Mills) was used as a humidifier. Printing was performed by etching with the same humidifier.

[0033]

[Table 1]

Compound B of the present invention 4 comprises 2-mercapto-5-n
-Heptyloxadiazole, 0.2 g / l was added. In Comparative 2, 50 g / l of propylene glycol and 0.3 g / l of compound B were added to the above stabilizer.

The evaluation of ink acceptability is the number of prints until a good print is obtained at the same time that the ink is brought into contact with the plate surface and the paper starts to be fed. Was evaluated according to the following criteria. ；: No stain is generated. Δ: Partial or thin stains have occurred. ×: Light dirt is generated on the entire surface. Table 2 shows the printing results.

[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 in the same manner as in Example 1 was etched using the following etchant except that the stabilizer obtained by removing Compound A from the stabilizer of Example 1 was used. The same printing test as in No. 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 Make up to 1 l with water.

For compound A, the same compound as used in Example 1 was used.
In Comparative Example 2, a liquid prepared by adding 1.0 g / l of the compound B of Example 1 instead of the compound A was used.

In the ink acceptability and stain resistance tests, the same results as in Example 1 were obtained.

Embodiment 3 A processing apparatus having a coating mechanism is disclosed in Japanese Patent Application No. 5-33402.
The processing apparatus described in the example of No. 8 was used. A plate making process was performed on the developing section and the stabilizing section using the developing solution and the stabilizing solution described in Example 1, respectively. The printing test and evaluation method were the same as in Example 1. The results are shown in Table 3.

[0042]

[Table 3]

From the above results, when treated by the coating treatment method, the neutralizing solution containing the silicones of the present invention dramatically improved the ink receptivity as compared with the comparative neutralizing solution conventionally used. You can see that In particular, a lithographic printing plate subjected to plate making processing by a processing apparatus having a coating mechanism was found to have an effect of improving ink receptivity better than conventionally known compounds having a mercapto or thione group.
From the stability of the liquid, polyether-modified silicone was found to be particularly effective.

Example 4 A printing plate prepared in the same manner as in Example 3 except that the neutralizing solution obtained by removing Compound A from the neutralizing solution of Example 3 was etched using the etching solution of Example 2. The same printing test as in Example 1 was performed.

For compound A, the same compound as used in Example 1 was used.
In Comparative Example 2, a liquid prepared by adding 1.0 g / l of the compound B of Example 1 instead of the compound A was used.

In the ink acceptability and stain resistance tests, the same results as in Example 3 were obtained.

[0047]

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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-202337 (JP, A) JP-A-5-289341 (JP, A) JP-A-6-32081 (JP, A) JP-A-6-32081 199066 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03F 7/07 B41N 3/08

Claims (1)

(57) [Claims] 1. Use after development processing until the start of printing.
Plate for lithographic printing plates using image silver as ink acceptability
A method for treating a lithographic printing plate, comprising treating the treatment solution with a plate surface treatment solution containing at least one type of silicones.