JP3101432B2 - Processing solution for offset 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 an offset printing plate using a silver image as ink acceptability, and more particularly to a processing solution for a direct offset printing plate using a silver complex salt diffusion transfer method. It is intended to improve the ink receptivity of the formed silver image. More specifically, a silver image of an offset printing plate formed by a diffusion transfer method is processed at an optional stage in a printing process with a specific processing agent as appropriate to improve the ink receptivity of the silver image itself. Liquid.

[0002]

2. Description of the Related Art There have been many attempts as offset printing plates for forming a silver image by a photographic or physical method and using the silver image as ink receptivity.
For example, Japanese Patent Publication No. 48-29723, 51-157
No. 62 discloses a technique for improving the ink receptivity of a silver image by treating a photographically formed silver image with a lipophilic agent containing a certain organic mercapto compound. However, the mercapto compound used here is usually extremely low in solubility in neutral water. Therefore, an alkaline aqueous solution in which an alkali metal hydroxide or the like is dissolved or an organic solvent such as alcohol, THF, DMF, or acetone is used. Can be added to the treatment liquid by a method of dissolving in a mixed solution of water and water, or a method of previously dissolving in an organic solvent having a high boiling point and adding this to form an oil-in-water dispersion emulsion.

However, workability in a printing plate processing step,
In recent years, from the viewpoint of safety or stability over time of the processing solution, a neutral aqueous solution type is desired as the plate surface processing solution, and the compound described in the above patent has a high pKa,
Satisfactory results are not obtained in a processing solution containing no organic solvent. Further, the demands on the printing image quality of the printing plate are increasing year by year, and a processing solution containing a compound that allows the image portion of the printing plate to receive the ink sufficiently in a short time and does not cause background staining of the non-image portion is strongly desired. ing.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an offset printing plate processing solution containing an oleophilic agent for improving the ink receptivity of a silver image. An object of the present invention is to provide a processing liquid which improves the ink receptivity of an image and has less background stain on a non-image portion.
Another object of the present invention is to provide a processing solution for an offset printing plate which does not contain an organic solvent and improves the ink receptivity of a silver image by using a lipophilic agent having high water solubility.

[0005]

The object of the present invention has been attained by incorporating a compound represented by the formula (3) or a compound represented by the formula (4) into a treatment liquid as an oleophilic agent.

[0006]

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[0007]

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Wherein l is 1 to 3, m is 3 to 5, and n is 1 to
3, r represents an integer of 3 to 7.

This compound has a pKa of about 3 to 4,
It dissociates even in a neutral aqueous solution and adsorbs on a silver image to improve ink receptivity. The terminal alkyl group (: Cm H2m + 1 or Cr H2r + 1) may be linear or have a side chain, but is preferably a linear one. Also,
For m, n and r, l = 1 to 3, m = 3 to 5, n = 1
3 and r = 3 to 7, an arbitrary number can be selected. However, when m is 6 or more or r is 8 or more, the effect of improving the ink receptivity of the silver image becomes weak, and the solubility in water becomes poor. Also gets worse. For l and n, l = 1 to 3, n = 1
Any number between 3 and 3 can be selected, but when it is 4 or more, the effect of improving the ink receptivity also weakens. Hereinafter, typical compounds used in the present invention will be described, but the present invention is not limited thereto.

## STR1 ## Examples of compounds of formula 3

[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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[0016]

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Example of compound of formula

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[0018]

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[0019]

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[0020]

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[0021]

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The compounds of formulas 3 and 4 of the present invention can be easily synthesized by converting the corresponding amino compound into isothiocyanate and then cyclizing it with sodium azide. The details of the synthesis method are described below using synthesis examples.

Synthesis of Synthesis Example 1 (Chemical Formula 6) 34 g of calcium carbonate in 400 ml of chloroform and 200 ml of water, N, N-di-n-butylethylenediamine 26
g is added, and 19.6 g of thiophosgene is added dropwise thereto, and the mixture is stirred at room temperature for 3 hours to be reacted. After separating the chloroform layer, the aqueous layer is further extracted with chloroform and added to the chloroform layer. The solvent was distilled off from the chloroform layer under reduced pressure to obtain 30 g of 2- (di-n-butylamino) ethyl isothiocyanate as a tan oil. This isothiocyanate is dissolved in a mixed solution of 300 ml of ethanol and 20 ml of water, 27 g of sodium azide is added, and the mixture is heated under reflux for 4 hours. Ethanol was distilled off from the reaction solution under reduced pressure, and the remaining oil was dissolved in 250 ml of water and washed three times with 50 ml of ether. Add 1N hydrochloric acid to the aqueous solution and adjust the pH to 7-8.
The precipitated oil was extracted three times with 50 ml of chloroform, dried over anhydrous sodium sulfate. After sodium sulfate was filtered off, chloroform was distilled off under reduced pressure, and the remaining oil was separated by silica gel column chromatography (chloroform: methanol = 10: 1) to give 1- [2
8.5 g of-(di-n-butylamino) ethyl] -5-mercapto-tetrazole were obtained as a yellow oil.

1 H-NMR (CDCl ₃ ): δ (ppm
) 12.6 (1H, br.s, -SH) 4.92
_{(2H, m, CH 2)} 3.70 (2H, m, CH 2) 3.12 (4H, br.s, CH 2) 1.62 (2H, b
r. s, CH ₂ ) 1.42 (4H, m, CH ₂ ) 1.33 (2H, m, C
_{H 2) 0.98 (6H, t} , CH 3)

13C-NMR (CDCl): δ (ppm
), 154 (C-tetrazole - _{Le) 54 (CH 2), 42} (CH 2), 35 (CH 2) 32 (CH 2), 20 (CH 2), 13 (CH 3)

Synthesis of Synthesis Example 2 (Chemical formula 12) 19 g of calcium carbonate and 15 g of 2- (n-hexylthio) ethylamine in 200 ml of chloroform and 100 ml of water.
Was added thereto, and 10.8 g of thiophosgene was added dropwise thereto, followed by stirring at room temperature for 3 hours to cause a reaction. After separating the chloroform layer, the aqueous layer was further extracted, and chloroform was distilled off under reduced pressure to obtain 18.3 g of 2- (n-hexylthio) ethyl isothiocyanate as a yellow-brown oil. Also, 2-
(N-Hexylthio) ethylamine was synthesized by S-alkylating 2-aminoethanethiol with n-hexyl bromide. 2- (n-hexylthio) ethyl isothiocyanate was treated with 150 ml of ethanol and 20 ml of water.
The mixture was dissolved in a 1 ml mixed solution, 17 g of sodium azide was added, and the mixture was heated under reflux for 4 hours. Ethanol was distilled off from the reaction solution under reduced pressure, and the remaining oil was dissolved in 250 ml of water.
Wash 5 times with 0 ml. Add 6N hydrochloric acid to the aqueous solution and adjust the pH.
= 1 and 2, the precipitated oil was chloroform 30 ml
5 times, and dried by adding anhydrous sodium sulfate.
After filtering off sodium sulfate, chloroform was distilled off under reduced pressure, and the remaining oil was developed and purified by silica gel column chromatography (chloroform: methanol = 10: 1) to give 1- [2- (n-hexylthio) ethyl. ] -5
10 g of mercapto-tetrazole were obtained as a brown oil.

1 H-NMR (CDCl ₃ ): δ (ppm
) 14.2 (1H, br.s, -SH) 4.99
_{(2H, t, CH 2)} 3.04 (2H, t, CH 2) 2.60 (2H, t, CH 2) 1.61 (2H, m, C
_{H 2) 1.38 (2H, m} , CH 2) 1.30 (4H, m, C
_{H 2) 0.89 (3H, t} , CH3)

The compound of the present invention has high solubility in neutral water and exhibits a good effect when used in the form of a treatment solution containing no organic solvent such as alcohol. Of course, alcohols, THF, It can be used as a treatment liquid containing an organic solvent such as DMF and acetone, and its effect is not so good or bad.

The compound of the present invention is most effectively processed in the form of a solution after the development process. However, the process of making an offset printing plate, more specifically, the developing process of a silver image and the stopping process It is preferable to apply it by including it in the developing solution and the stop processing solution, and it is possible to improve the ink receptivity of the plate.

The concentration of the lipophilic agent added to the treatment liquid of the present invention is 0.1 to 10 g / l, preferably 0.5 g to 1 g.
5 g / l. Further, other additives can be used in combination, and thickeners such as polyvinyl alcohol, glycerin, and ethylene glycol can be contained, but these are not essential elements. The processing liquid of the present invention improves the ink receptivity of the silver image area of the printing plate, while reducing background smear of the non-image area. In addition, the stability of the processing solution over time is excellent.

An offset printing plate utilizing the silver image of the present invention as ink acceptability is disclosed in JP-B-48-3056.
No. 2, JP-A-53-21602, U.S. Pat.
In addition to 1,559, 3,490,905 and the like, offset printing plates having a silver halide image as ink acceptability, such as U.S. Pat. No. 3,454,398 and JP-A-53-9603, are included. Is done. Hereinafter, the present invention will be described specifically with reference to Examples.

[0032]

【Example】

Example 1 An offset printing plate (Plate No. 3) described in Example 1 of JP-A-53-21602 was prepared in the same manner as above except that the physical development nucleus layer contained 1.0 g / m ² of hydroquinone. A lithographic printing material was prepared. After exposing the lithographic printing material according to the image, a transfer developer of
For 30 seconds to perform transfer development. Subsequently, the material was immersed in a stop solution having the following formulation for 30 seconds (25 ° C.), squeezed to remove excess liquid, and dried under atmospheric conditions.

<Transfer developer> Water 700 ml Sodium hydroxide 20 g Anhydrous sodium sulfite 60 g Potassium bromide 0.5 g 2-mercaptobenzoic acid 10 mmole 2-methyl-2-amino-1-propanol 10 g Add water and add 1 l And

<Stop solution> Water 2 l Citric acid 10 g Sodium citrate 35 g

The printing plate thus obtained was used for offset printing machine AB Dick 350CD (AB Dick 3).
50CD (trade name), and the surface of the plate was wiped with a liquid of formula (E), and printing was performed using a humidifying liquid having the following composition.

Treatment liquid (E) Exemplary compound 1 g Ethylene glycol 50 g Water 1000 ml

<Humidifying liquid> (The used liquid is diluted 10-fold with water) Water 300 ml Succinic acid 6 g Sodium sulfate 25 g Ethylene glycol 100 g Colloidal silica (20% aqueous solution) 28 g

The ink receiving characteristics and the ease with which dirt was produced were determined by the following methods. 1) Ink receiving characteristics The number of prints until a printed matter is obtained with a good image density by starting paper feeding at the same time when the inked roller is brought into contact with the plate surface. 2) Evaluation of dirt The printing was performed on 1,000 sheets, and evaluation was made on the following three levels based on the degree of dirt on the printed matter at that time. ○ No dirt occurs. △ Partial or thin dirt × Completely thin dirt Also, as a comparative compound,
Chemical formula 17 was used.

[0039]

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[0040]

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The evaluation results are summarized in Table 1.

[0042]

[Table 1]

As is apparent from Table 1, the compounds of the present invention have high solubility in water and improve the ink receptivity of silver images.

Example 2 Printing was evaluated in the same manner as in Example 1 except that the plate was processed by changing the formulation of the treatment liquid to the formulation (F). After treating these treatment liquids at 50 ° C. for 2 weeks, plate making and printing were similarly performed and evaluated.

[0045]

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[0046]

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[0047]

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[0048]

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Treatment liquid (F) Exemplary compound 1 g Ethylene glycol 50 g Isopropanol 400 ml Water 600 ml

As comparative compounds, Chemical formulas 16, 18 and 1
9, Chemical Formula 20 and Chemical Formula 21 were used. Table 2 shows the evaluation results. The results after the aging of the treatment liquid are shown in the lower row.

[0051]

[Table 2]

As is evident from Table 2, the compounds of the present invention can provide a processing solution having excellent ink receptivity and excellent stability over time.

[0053]

The processing liquid of the present invention improves the ink receptivity of the silver image area of the offset printing plate, and is also effective in reducing the background smear in the non-image area, and also in the stability of the liquid over time. Are better.

Continuation of the front page (56) References JP-A-58-152242 (JP, A) JP-A-2-207251 (JP, A) JP-A-57-150850 (JP, A) JP-A-1-270050 (JP) , A) JP-A-3-10248 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 7/07

Claims (1)

(57) [Claims] 1. A processing solution for an offset printing plate utilizing a silver image as ink receptivity, comprising a compound of formula 1 or a compound of formula 2. Embedded image (In the formula, l is an integer of 1 to 3, and m is an integer of 3 to 5.) (In the formula, n is an integer of 1 to 3, and r is an integer of 3 to 7.)