JPH0880687A - Treatment of silver salt planographic printing plate - Google Patents

Abstract

PURPOSE: To enhance not only the ink receptivity of an image part without damaging the formation of image silver but also plate placing properties in a planographic printing plate utilizing image silver as ink receptivity. CONSTITUTION: A planographic printing plate utilizing image silver as ink receptivity is treated in a treatment apparatus having a developing tank, a neutralizing tank and a tank containing an ink receptivity promotor. Therefore, in the planographic printing plate utilizing image silver as ink receptivity, good printed matter free from density irregularity can be rapidly obtained without damaging an image part and good plate placing properties can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate surface treatment for improving the ink acceptability of the image area at the start of printing and the plate-making property after plate making in a lithographic printing plate using image silver as the ink acceptability. It is about the method.

[0002]

2. Description of the Related Art A printing plate using a silver halide emulsion having high sensitivity and capable of spectral sensitization has already been put into practical use in several forms. Among them, offset printing plates that utilize image silver for ink acceptance are disclosed in US Pat. Nos. 3,721,559, 3,490,905 and JP-B-4.
8-30562, U.S. Pat. Nos. 3,385,701, 3,814,603, JP-B-44-27242, JP-A-53-21602, U.S. Pat. Nos. 3,454,398, 3764323, 3099209, and JP-A-3099209. 5
3-9603, etc.

The method for producing these printing plates is roughly classified into several types, but they are common in that the image silver is made to be ink-receptive. The planographic printing plate is
It is composed of an image portion which accepts lipophilic ink and a non-image portion which is hydrophilic and accepts water. Therefore, in ordinary lithographic printing, both water and ink are supplied to the plate surface, the image portion selectively receives the coloring ink, and the non-image portion selectively receives water,
This is done by transferring the ink on the image to a substrate such as paper.

In order to obtain a good printed matter, it is required that the difference in lipophilicity and hydrophilicity between the surface of the image portion and the non-image portion is sufficiently large.

The plate making method of a printing plate using the above-mentioned silver halide emulsion is simple, reliable and quick, can be automated, and is characterized by high sensitivity, high resolution and high image reproducibility. However, the difference in lipophilicity and hydrophilicity between the image portion and the non-image portion was not sufficiently large as compared with a printing plate (PS plate) or the like that has been realized from an organic colloid such as a diazo light-sensitive material.

In order to overcome such drawbacks, Japanese Patent Publication No. 48
No. 29723, JP-A No. 58-127928 and the like show that a compound having a mercapto group or a thione group acts on image silver to improve ink acceptability.

The above-mentioned compound having a mercapto group or a thione group can act on the printing plate in various stages before printing. That is, it is added to the developing solution and / or the neutralizing solution. Further / or, directly on the printing plate before printing.

However, each of the above methods has various problems. That is, if it is contained in the developing solution, it may adversely affect the formation of image silver if it is used in an excessively large amount, and if it is contained in the neutralizing solution, the neutralizing solution generally keeps its action. Due to the high salt concentration, it was difficult to maintain the stability of the liquid, and in any case it was not possible to use a sufficient amount. Further, the method of wiping the plate surface with a liquid containing the compound after plate making becomes complicated in operation, and recently, without performing such an operation, only the dampening water is first supplied by the operation of the printing machine at the start of printing. To moisten the plate,
It is becoming more popular to start printing after that.

Further, not only the problem of the initial ink riding,
In the printing plate using the above-mentioned silver halide emulsion, it has a drawback that it is difficult to place the plate for a long time after the plate making due to an extreme decrease in printing durability.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for processing a lithographic printing plate which utilizes image silver as an ink-receptive property, using a stable processing solution without compromising the production of image silver, which is complicated. Another object of the present invention is to provide a processing method that improves the ink acceptability of the image area regardless of the above method.

Another object of the present invention is to impart stable plate-setting property after plate making in a lithographic printing plate which uses image silver as an ink receptivity.

[0012]

The above objects of the present invention are as follows.
In a processing method of a lithographic printing plate utilizing image silver as an ink acceptability, it was achieved by processing in a processing apparatus having a developing tank, a neutralizing tank, and a tank containing an ink riding accelerator following these tanks.

The compounds having a mercapto group or a thione group used in the present invention are described in JP-B-48-29723, JP-A-58-72143 and JP-A-58-127928. Basically, it has a structure composed of a mercapto group or a thione group and a lipophilic group.

The compound having a mercapto group or a thione group used in the present invention has the following general formula.

[0015]

Embedded image

(In the formula, R is hydrogen, an alkyl group having 12 or less carbon atoms, an allyl group, an aralkyl group, and Z is N or C in the formula.
And the remaining atomic groups necessary for forming a 5- or 6-membered ring are shown. )

Specific examples of the 5- or 6-membered ring include imidazole, imidazoline, thiazole, thiazoline,
Oxazole, oxazoline, pyrazoline, triazole, thiadiazole, oxadiazole, tetrazole, pyridine, pyrimidine, pyridazine, pyrazine, triazine, etc., and these rings may be two or more condensed rings. It may be condensed with or a naphthalene ring.

Typical examples of such compounds include 2
-Mercapto-4-phenylimidazole, 2-mercapto-1-benzylimidazole, 2-mercapto-benzimidazole, 1-ethyl-2-mercapto-benzimidazole, 2-mercapto-1-butyl-benzimidazole, 1,3- Diethyl-benzimidazoline-2-thione, 1,3-dibenzyl-imidazolidine-
2-thione, 2,2'-dimercapto-1,1'-decamethylene-diimidazoline, 2-mercapto-4-phenylthiazole, 2-mercapto-benzothiazole,
2-mercaptonaphthothiazole, 3-ethyl-benzothiazoline-2-thione, 3-dodecyl-benzothiazoline-2-thione, 2-mercapto-4,5-diphenyloxazole, 2-mercaptobenzoxazole,
3-pentyl-benzoxazoline-2-thione, 1-
Phenyl-3-methylpyrazolin-5-thione, 3-mercapto-4-allyl-5-pentadecyl-1,2,4
-Triazole, 3-mercapto-5-nonyl-1,
2,4-triazole, 3-mercapto-4-acetamide-5-heptyl-1,2,4-triazole, 3-mercapto-4-amino-5-heptadecyl-1,2,4
-Triazole, 2-mercapto-5-phenyl-1,
3,4-thiadiazole, 2-mercapto-5-phenyl-1,3,4-thiadiazole, 2-mercapto-5
-N-heptyl-oxathiazole, 2-mercapto-
5-phenyl-1,3,4-oxadiazole, 2-heptadecyl-5-phenyl-1,3,4-oxadiazole, 5-mercapto-1-phenyl-tetrazole,
2-mercapto-5-nitropyridine, 1-methyl-quinoline-2 (1H) -thione, 2-mercapto-4-hydroxy-6-pentadecylpyridine, 3-mercapto-4-methyl-6-phenyl-pyridazine, 2-mercapto-5,6-diphenyl-pyrazine, 2-mercapto-4,6-diphenyl-1,3,5-triazine, 2-
Amino-4-mercapto-6-benzyl-1,3,5-
Triazine and the like can be mentioned, and the mercapto compound and the like are contained in the treatment liquid in an amount of 0.1 to 3 g / L, preferably 0.5 to 1
It is preferable to contain it at a concentration of g / L.

The above-mentioned compound having a mercapto group or a thione group can be generally dissolved in an organic solvent or a highly alkaline aqueous solution, but for use in the developing tank and the tank subsequent to the neutralizing tank of the present invention, an amine compound or a quaternary ammonium salt is used. It is preferable to dissolve in water by using a salt type cationic surfactant or the like.

Examples of the amine compound used in the present invention include amino alcohols such as monoethanolamine, diethanolamine, triethanolamine and aminoethylethanolamine, monoamines such as propylamine and butylamine, and diamines such as dimethylaminoethylamine. And polyamines such as N-aminopurupylpropanediamine and cyclic amines such as pyridine and piperidine. Amino alcohols are preferred.

The amine compound used in the present invention has a weight ratio of 5: 1 to 30: to the above mercapto compound.
It is advisable to add and mix in water at a ratio of 1, preferably 10: 1 to 20: 1. After that, it is prepared by adding other compounds and the like to the mixed solution as necessary, or is prepared by adding the mixed solution to a solution containing other additives and the like.

The quaternary ammonium salt cationic surfactant used in the present invention includes those having the following general formula.

[0023]

Embedded image

(In the formula, R1 to R4 represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an aryl group and an aralkyl group, and X is an anion such as chlorine ion, bromide ion, sulfate ion or acetate ion. is there.)

As a concrete example, ARCARD T-30, 12-50, 2C commercially available from Lion Co., Ltd.
-75, etc., such as cations AB and BB marketed by NOF CORPORATION. Particularly preferred is the alkylbenzyl ammonium chloride type,
Examples include Catiolite BC-50 marketed by Kyoeisha Yushi Kagaku Kogyo Co., Ltd., Arcard BC-50 marketed by Lion Co., Ltd., and Cation F2-20R marketed by NOF CORPORATION.

The quaternary ammonium salt type cationic surfactant used in the present invention is in a weight ratio to the above compound of 10: 1 to 30: 1, preferably 15: 1 to 25: 1.
Add and mix in the ratio of the range. After that, it is prepared by adding other compounds and the like to the mixed solution as necessary, or is prepared by adding the mixed solution to a solution containing other additives and the like.

According to the above method, the ink transfer accelerator can be added to the neutralization tank, but the neutralization tank has a high salt concentration and cannot be kept stable because of precipitation and the like. Cannot be used in large quantities.

In order to improve ink stains, colloidal fine particles may be contained in the developing tank and the neutralization tank, which are subsequently provided with an ink-carrying accelerator. The colloidal fine particles referred to herein mean fine particles that are stably dispersed in a colloidal form, and preferably have a particle size of about 100 mμ or less, and representative examples thereof include colloidal silica and colloidal alumina. However, colloidal silica is preferable. About 0.01 to about particle solid content
It is used in the range of 100 g / L, preferably 10-
It is preferable to use it in the range of 100 g / L. The effect of the present invention increases as the amount of addition increases, but if the amount is too large, the ink acceptability of the image area deteriorates, so it is not preferable to use more than these ranges.

Further, a hygroscopic polyol compound may be contained in a tank for containing an ink vehicle, which follows the developing tank and the neutralizing tank. The hygroscopic polyol compound as referred to herein is a hygroscopic compound having two or more hydroxyl groups, and specific examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, α-propylene glycol, glycerin and polyethylene glycol. (Molecular weight of 1000 or less, especially 200
However, among these, ethylene glycol, diethylene glycol, α-propylene glycol, glycerin and the like having a relatively low molecular weight are preferable. The addition amount may be in the range of 0.1 to 50 g / L, but preferably 1 to 3
It is preferably used in the range of 0 g / L. If the amount added is too large, the printing plate after photographic processing is difficult to dry, which is inconvenient when stored in the plate state, and the ink acceptability of the image area is deteriorated, which is not preferable.

The components of the developing solution which can be used in the present invention include alkaline substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide and sodium triphosphate, sulfites as preservatives and halogenated compounds. Silver solvents such as thiosulfates, thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines, thickeners such as hydroxyethyl cellulose, carboxymethyl cellulose, antifoggants such as potassium bromide, JP-A-47- 262
01 compounds, etc., developers such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone,
Development modifiers such as polyoxyalkylene compounds and onium compounds can be included. Further, examples of the developing solution include compounds such as those described in U.S. Pat. No. 3,776,728, which improve ink transfer of the surface silver layer.

The components of the neutralizing solution that can be used in the present invention are:
Citric acid, acetic acid, phosphoric acid, boric acid, sulfurous acid and alkali metal salts thereof can be used as pH adjusters / buffers. Further, for example, sodium hexametaphosphate as a water softener, and formalin, glyoxal, glutaraldehyde, tannic acid, dimethylolurea, an ethyleneurea resin or other organic compound as a binder curing agent to prevent abrasion of the plate surface during printing, chromium. Inorganic compounds such as alum and potassium alum can be used as necessary.

The present invention will be described below with reference to examples, but of course the present invention is not limited thereto.

[0033]

【Example】

Example 1 In the same manner as in Example 1 of JP-A-53-21602 except that the physical development nucleus layer of the offset printing plate (plate No. 3) contained 1.0 g / m 2 of hydroquinone. To produce a lithographic printing material. The lithographic printing material was imagewise exposed and then developed with the following silver complex salt diffusion transfer developer at 30 ° C. for 30 seconds.

<Transfer developer> Water 700 ml Potassium hydroxide 20 g Sodium sulfite anhydrous 50 g 2-Mercaptobenzoic acid 1.5 g 2-Methylaminoethanol 15 g Water is added to make 1 liter.

After the development treatment, the original plate was passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds and squeezing rollers to remove the excess solution. Removed.

<Neutralization liquid> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% liquid) 5 ml Ethylene glycol 5 ml Water is added to make 1 liter.

After the neutralization treatment, the original plate was passed between two squeezing rollers to remove excess neutralizing liquid, and immediately treated with a liquid having the following composition at 25 ° C. for 5 seconds, and squeezing rollers were used to remove the excess liquid. Removed and dried at room temperature.

<Ink Riding Accelerator-Containing Liquid> Water 600 ml Mercapto compound 1 g Mercapto compound solubilizer 20 g Phosphoric acid is added to adjust the pH to 6 and then adjusted to 1 liter with water.

The printing plate prepared by the above operation is set on the offset printing machine, and AM MULTILI is set on the printing machine.
TH OFFSET DUPLICATORS 125
0 (ADDRESSOGRAPH MULTIPRAP
H offset printing machine), ink is ABDick3-
1012 Black ink (made by ABDick), SL as a moisturizing liquid
Printing was performed using M-OD30 (manufactured by Mitsubishi Paper Mills). The fountain solution was supplied to the printing plate before printing. The printing room is 22
The temperature and humidity were 60%.

The results are summarized in the table below.

[0041]

[Table 1]

Compound A in Table 1 is 2-mercapto-5-
n-heptyl-oxadiazole, B is 2-mercapto-4-phenylimidazole.

As a comparison, the printing plate of No. 1 was not processed in the developing tank and the neutralization tank, which were followed by a tank containing an ink-carrying accelerator. The printing plate of No. 2 was treated with a neutralizing solution containing 1 g of compound A and 20 g of triethanolamine.
It was not treated in a tank containing an ink transfer accelerator following the neutralization tank.

The ink acceptability was evaluated as the number of prints until the ink was brought into contact with the plate surface and at the same time the paper was fed, and a printed matter with good image density and no density unevenness was obtained.

As can be seen from these results, it can be seen that a good printed matter having no density unevenness can be quickly obtained by treating with a tank containing the ink-carrying aid of the present invention.

Further, in the printing plate of Comparative Example 2, good ink transfer was obtained, but when the treatment was continued for 1 month, precipitation occurred in the neutralizing solution tank.

Example 2

The printing plates 1 and 3 used in Example 1 were stored in a black polyethylene bag for 3 months. Ryobi Co., Ltd. 2800CD is used for the printing machine, and the ink is ABDick3.
-1012 Black ink (made by ABDick), S as a dampening liquid
Printing was performed up to 10,000 sheets using LM-OD30 (manufactured by Mitsubishi Paper Mills). Before printing, an sensitizing liquid having the following composition was supplied to the printing plate. The printing room had a temperature of 22 ° C. and a humidity of 60%.

<Sensitizer> Water 400 ml Citric acid 1 g Sodium citrate 3.5 g Compound A 0.5 g Ethylene glycol 50 ml

In the printing plate 1 (comparative example), image fading appeared on about 1,000 sheets, but in printing plate 4 (the present invention), 1
Good prints were obtained up to 000 sheets.

[0051]

According to the embodiments of the present invention, it is possible to quickly obtain a good printed matter having no density unevenness in a lithographic printing plate that uses image silver as an ink-receptive property without hindering an image portion.

It was possible to obtain a more stable plate formability.

Claims (1)

[Claims] 1. A method of processing a lithographic printing plate which utilizes image silver as an ink accepting property, wherein the processing is carried out by a processing apparatus having a developing tank, a neutralizing tank, and a tank containing an ink transfer accelerator following these tanks. The processing method characterized by.