JPH09304946A - Retouching agent for printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep performance as a consumable from being lowered in long-term storage by containing a compound for forming an iron ion and a complex or a specified compound in a retouching agent containing an organic oxygen ferric salt and sulfite. SOLUTION: A compound for forming an iron ion and a complex or a compound expressed by the formula R<1> -NP-R<2> -A is added to a retouching agent containing an organic oxygen ferric salt and sulfite. In the formula, R<1> indicates an alkyl group, an alkenyl group, or an aryl group, R<2> indicates a bivalent connecting base, and R<1> and R<2> may be bonded together to form a ring. A indicates an acid radical. As a compound for forming an iron ion and a complex used in this case, cited are aminopolycarboxylic acid or its salt, polyphosphoric acid or its salt, -diketones, sulfosalicylic acid or its salt and acethylacetone and so on. As an aminopolycarboxylic acid and its salt, cited are ethylene diaminetetra acetic acid, nitrilotriacetic acid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset printing plate that utilizes a silver image as an ink-receptive material, and a silver image correcting agent formed on the printing plate. By appropriately surface-treating unnecessary portions on the offset printing plate formed by a conventional method with a specific treating agent at any stage in the printing process, there is no particular problem with printing characteristics, equipment, etc. The present invention relates to completely hydrophilizing and eliminating ink acceptability. Usually, in the printing field, such a process is called "correction", and the present inventors will follow it. Further, the processing agent used for the correction operation will be referred to as "correction agent".

[0002]

2. Description of the Related Art In general, a printing original plate produced by a photoengraving method needs to be corrected in such a manner that it already exists in a copy original, that which occurs during exposure, and other uneven development processing steps. There are things caused by.

That is, for example, an unnecessary image is generated in a copy original, or when an original made by pasting various originals is used, a shadow is projected at the time of exposure. In order to obtain a good printed matter, all of these areas must be corrected at the stage of plate making and printing. Generally speaking, the correction operation is indispensable, and it is desirable that the necessary correction can be performed at any stage of the plate making and printing process.

Further, stability of the liquid over time is also required. The stability with time is required to be that before the correction agent is applied to the printing plate and that after the correction agent is applied. The stability after coating is required to be stable with time until printing, and that the initial erasability is not lost even if printing is started and then interrupted and printing is restarted.

Many attempts have been made as a method of correcting unwanted images in offset printing plates which utilize a silver image as the ink receptivity. For example, JP-A-48-92101 and JP-A-51
21901, 54-53002, 59-96
The compounds having a mercapto or thione group and a hydrophilic group described in 61, etc. can surely and almost instantaneously hydrophilize a silver image. However, these compounds have drawbacks such as a strong acid effect on the human body and lack of stability over time which is considered to be mainly caused by oxidation. JP-A-63-141064 describes a correcting agent which eliminates adverse effects on the human body by containing a ferric salt of an organic acid and soluble bromide and soluble iodide. 141063 further describes a modifier containing sulfite. However, even in this case, the stability over time was not sufficient.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a correcting agent containing a ferric organic acid salt and a sulfite salt, which is used for a lithographic printing plate utilizing a silver image as an ink accepting property, for a long period of time. It is an object of the present invention to provide a correction agent having improved stability over time without deteriorating the performance as an erasing agent even during storage.

[0007]

The above object of the present invention is to add a compound which forms a complex with iron ion or a compound of the following general formula (I) to a modifier containing ferric salt of organic acid and sulfurous acid. Achieved by General formula ^{(I) R 1 -NH-R} 2 -A wherein R ¹ is an alkyl group, an alkenyl group, an aryl group, R ² represents a divalent linking group, R ¹ and R ² are bonded to each other To form a ring. A represents an acid group.

Further, the correction ability is improved by adding a thiosulfate having a complexing ability higher than that of the soluble bromide salt or soluble iodide salt to the correction agent.

Examples of the compound which forms a complex with iron ion used in the present invention include aminopolycarboxylic acid or a salt thereof, polyphosphoric acid or a salt thereof, β-diketones, sulfosalicylic acid or a salt thereof, acetylacetone and the like. .

Aminopolycarboxylic acids and salts thereof include ethylenediaminetetraacetic acid (EDTA) and EDT.
A disodium salt, EDTA diammonium salt, EDT
A tetra (trimethylammonium) salt, EDTA tetrapotassium salt, EDTA tetrasodium salt, EDTA
Trisodium salt, diethylenetriaminepentaacetic acid,
Diethylenetriaminepentaacetic acid pentasodium salt,
Ethylenediamine-N- (β-oxyethyl) -N,
N ', N'-triacetic acid, ethylenediamine-N- (β-
Oxyethyl) -N, N ', N'-triacetic acid triammonium salt, propylenediaminetetraacetic acid, propylenediaminetetraacetic acid disodium salt, nitrotriacetic acid trisodium salt, cyclohexanediaminetetraacetic acid,
Cyclohexanediaminetetraacetic acid disodium salt, iminodiacetic acid, dihydroxyethylglycine, ethyletherdiaminetetraacetic acid, ethylenediaminetetrapropionic acid and the like, preferably hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, nitrilotriacetic acid, triethylene. Examples include tetramine hexaacetic acid.

The amount of aminopolycarboxylic acid or a salt thereof used in the present invention is 0.
0005 to 0.2 mol, especially 0.004 to
It is preferably 0.04 mol.

The polyphosphoric acid and its salt are disclosed in JP-A-55-65957, JP-A-57-53794, and JP-A-59-1.
84344, 61-11745 and 61-4266.
The compounds shown in 0 and the like are used. For example, the compounds shown in the following chemical formulas 1 to 8 are listed.

[0013]

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[0014]

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[0015]

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[0016]

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[0017]

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[0018]

[Chemical 6]

[0019]

[Chemical 7]

[0020]

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The amount of the above compound added to the correction agent of the present invention is 0.0005 to 0.2 mol per liter of the correction agent,
It is preferably 0.004 to 0.04 mol.

The compound represented by formula (I) will be described in more detail below.

In the compound of the general formula (I), R ¹ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, or an alkenyl group, or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (eg, phenyl). Group, naphthyl group, etc.). In the case of an alkyl group or an alkenyl group, it may be linear, branched or cyclic. R ¹ and R ² may combine with each other to form a ring, and a saturated heterocycle containing one or more heteroatoms (eg oxygen atom, sulfur atom, nitrogen atom, etc.) therein. May be cyclized to form, for example, methyl group, ethyl group, isopropyl group, n-butyl group, cyclopropyl group, pyrrolidyl group,
Examples thereof include a morpholino group. Also, R ¹
As the substituent of, for example, an alkoxy group, a sulfone group,
There are sulfamoyl group, carbamoyl group, ureido group and hydroxyl group.

R ² is a divalent linking group. The divalent linking group represented by R ² is an atom or atomic group containing at least one of C, N, S and O.

Specific examples of R ² include alkylene groups (preferably having 1 to 5 carbon atoms, such as methylene group, ethylene group, propylene group) and alkenylene groups (preferably having 2 to 5 carbon atoms). , For example, vinylene group), alkynylene group, preferably those having 2 to 5 carbon atoms, such as ethynylene group), arylene group (preferably phenylene group, etc.), —O—, —NH—, —N =,
-CO-, or -SO ₂ - is made of a single or combination of two or more of such (these groups may have a substituent).

A represents an acid group. Examples of the acid group include those capable of being dissociated into a anion in the developing solution. Particularly, a sulfonic acid group and a carboxylic acid group are preferable.

The acid group represented by A may be in the form of an acid anion. In this case, it may have a suitable cation as a charge balance counter ion. As such a cation,
For example, ammonium salts (eg, trimethylammonium, pyridinium, etc.), alkali metal ions, etc. may be mentioned.

Specific examples of the compound represented by formula (I) are shown below, but the present invention is not limited to the following compounds.

[0029]

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[0030]

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[0031]

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[0032]

[Chemical 12]

[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

[Chemical 21]

[0042]

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[0043]

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[0044]

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In the present invention, the amount of the compound represented by the general formula (I) to be added to the modifying agent is 0.0005 to 0.2 mol, preferably 0.0
It is 04 to 0.04 mol.

Representative examples of the thiosulfate used in the present invention include sodium thiosulfate, ammonium thiosulfate,
Examples thereof include lithium thiosulfate and calcium thiosulfate. The amount of thiosulfate contained in the modifying agent is preferably 0.007 to 2 mol, and preferably 0.6 to 1.8 mol, per 1 L of the modifying agent.

In the present invention, the iron ion liberated from the ferric organic acid complex salt acts on the sulfite which is a reducing agent to reduce its preservative action, whereas the compound which forms a complex with the iron ion is By recomplexing the liberated iron ion, it prevents the action on sulfite and maintains the preservative action. Further, it is considered that the compound of the general formula (I) prevents deterioration of sulfite due to air oxidation and improves stability with time.

Further, in a modifier having improved stability by adding the above compound, it has been conventionally used.
Replace the oxidized image silver with soluble bromide salt or soluble iodide salt, which has a relatively low ability to complex and impart hydrophilicity,
It becomes possible to contain thiosulfate having high hydrophilicity. However, there is no problem even if the thiosulfate and the soluble bromide salt or the soluble iodide salt are used at the same time.

A preferred example of the ferric organic acid salt in the present invention is ferric aminocarboxylic acid salt, but ferric phosphonic acid salt and the like can also be used. The ferric salt of an organic acid is usually used in the form of a complex salt, but ferric salts such as ferric sulfate, ferric chloride, ferric nitrate, ferric ammonium nitrate and ferric phosphate. A ferric ion complex salt may be formed in a solution using ferric iron and an organic acid. The ferric aminopolycarboxylic acid salt is a complex of ferric ion and aminopolycarboxylic acid or a salt thereof.

Typical examples of the aminopolycarboxylic acid and its salt include those mentioned above. Typical examples of the phosphonic acid or a salt thereof are diethylenetriaminepentamethylenephosphonic acid, cyclohexanediaminetetramethylenephosphonic acid, triethylenetetraminehexamethylenephosphonic acid, glycol etherdiaminetetramethylenephosphonic acid, 1,2-diaminopropanetetramethylenephosphonic acid, Methyliminodimethylenephosphonic acid, 1,
Examples thereof include 3-diaminopropan-2-ol tetramethylenephosphonic acid and ethylenediaminetetramethylenephosphonic acid. An organic acid ferric iron complex salt of any combination of these organic acids and the above-mentioned ferric iron salt can be used.

The ferric salt of an organic acid is for oxidizing a silver image used as an ink-receptive property, and a ferric salt of a mercapto compound generally used for enhancing lipophilicity is strongly adsorbed on the silver image. For oxidation, it is preferable to use a relatively large amount. Generally 0.0 per liter of modifier solution
The range is 5 to 1.0 mol, preferably 0.1 to 0.5 mol, and two or more kinds may be combined.

Examples of the sulfite used in the present invention include sodium sulfite, potassium sulfite, sodium hydrogen sulfite and the like. The amount of sulfite is in the range of about 0.1 to 1.5 mol per 1 L of the correction agent solution.

The correction agent of the present invention can be used as a correction agent using water, various alcohols or a mixed solvent thereof. In addition, carboxymethyl cellulose, polyvinyl alcohol, glycerin and other liquid-viscosity-imparting elements, and dyes, organic or inorganic pigments, etc., may be included as elements for coloring the liquid. Not an essential element.

Further, a fine particle powder as described in JP-A-51-21901 may be contained.

[0055]

【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> 700 ml of water 20 g of potassium hydroxide 50 g of anhydrous sodium sulfite 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 excess liquid. Removed and dried at room temperature.

<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.

Using the correction agent shown in Table 1, the portion to be corrected of the planographic printing plate was wiped.

The printing plate thus obtained was subjected to an offset printing machine ABDick 350CD.
The plate surface was wiped with an oil-sensitizing solution having the following formulation, and then printing was performed on 5,000 sheets. After that, remove the ink on the plate, 1
After a lapse of time, wipe the plate surface again with an oil-sensitizing solution and print 5000
I went one. 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 2-Mercapto-5-heptyl-1,3,5-oxadiazole 0.5 g Ethylene glycol 50 ml

A correction solution was prepared using the compounds shown in Table 1 below. This solution was left open for 2 weeks in a glass beaker.

[0063]

[Table 1]

The results of the correctability immediately after the preparation of the liquid are shown in Table 2.

[0065]

[Table 2]

◯ indicates that no ink is received, Δ indicates that ink is slightly acceptable, and x indicates that ink is completely acceptable.

Table 3 shows the results of the correctability after the elapse of release.

[0068]

[Table 3]

It can be seen from Table 3 that the stability of the correction agent over time is improved by the inclusion of aminopolycarboxylic acid, polyphosphoric acid or the compound of the general formula (I).

Example 2 Correction and printing were carried out according to the method of Example 1 by using a modifier prepared by using the compounds shown in Table 4.

[0071]

[Table 4]

Table 5 shows the correctability immediately after the preparation of the solution.

[0073]

[Table 5]

O indicates that no ink is received, Δ indicates that ink is slightly acceptable, and X indicates that ink is completely acceptable.

Table 6 shows the results of the correctability after the elapse of release.

[0076]

[Table 6]

From Tables 5 and 6, by containing aminopolycarboxylic acid, polyphosphoric acid or the compound of the general formula (I) and containing thiosulfate, complete correction can be made even when the number of printed sheets is large, and It can be seen that the stability is excellent.

[0078]

The correction agent of the present invention is capable of quick and reliable correction, has a long-lasting effect, and is excellent in liquid stability.

Claims (5)

[Claims] 1. A correction agent for an offset printing plate, which utilizes a silver image as an ink receiving property, comprising a compound forming a complex with iron ion in a correction agent containing a ferric salt of an organic acid and a sulfite salt. A characteristic correction agent for printing plates. 2. The printing plate correction liquid according to claim 1, wherein the compound that forms a complex with iron ions is aminopolycarboxylic acid or a salt thereof. 3. The correction agent for a printing plate according to claim 1, wherein the compound that forms a complex with the iron ion is polyphosphoric acid or a salt thereof. 4. A correction agent for an offset printing plate which utilizes a silver image as an ink receptivity, comprising a compound represented by the general formula (I) in a correction agent containing an organic acid ferric salt and a sulfite salt. A correction agent for a printing plate characterized by: General formula ^{(I) R 1 -NH-R} 2 -A wherein R ¹ is an alkyl group, an alkenyl group, an aryl group, R ² represents a divalent linking group, R ¹ and R ² are bonded to each other To form a ring. A represents an acid group. 5. The correction agent for a printing plate according to claim 1, further comprising a thiosulfate salt.