JPH0667436A - Treating liquid for offset printing plate - Google Patents

Abstract

PURPOSE:To improve ink receiving property of a silver picture image and to decrease contamination of the base in a nonpicture area by incorporating a specified compd. into a treating liquid CONSTITUTION:The treating liquid is used for an offset printing plate in which a silver picture image is rendered as ink receiving, especially for a direct offset printing plate using silver complex salt diffusion transfer method. The treating liquid contains a compd. expressed by formula I or a compd. expressed by formula II as an agent to give oleophilicity. In formula I, l is an integer 1 to 3 and m is an integer 3-5. In formula II, n is an integer 1 to 3 and Y is integer 3-7. These compds. have about 3 to 4pKa and are dissociated even in a neutral soln. and adsorbed to a silver picture image to improve the ink receiving property. The alkyl group (CmH2m+1 or CrH2r-1) at the end of the molecule may be straight or have side chains, and especially, a straight-chain type is preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing liquid for an offset printing plate using a silver image as an ink accepting property, particularly a direct offset printing plate using a silver complex salt diffusion transfer method. The purpose is to improve the ink receptivity of the formed silver image. More specifically, the offset printing plate is treated by a specific processing agent at an arbitrary stage in the printing process to process the silver image of the offset printing plate formed by the diffusion transfer method to improve the ink receptivity of the silver image itself. Regarding liquid.

[0002]

2. Description of the Related Art Many attempts have hitherto been made as an offset printing plate in which a silver image is formed by a photographic or physical method and the silver image is used as an ink acceptability.
For example, Japanese Examined Patent Publication Nos. 48-29723 and 51-157.
No. 62 discloses a technique for improving the ink acceptability of a silver image by treating a silver image formed photographically with a lipophilic agent containing a certain organic mercapto compound. However, since the mercapto compound used here is usually extremely low in solubility in neutral water, 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. It can be added to the treatment liquid by a method of dissolving it in a mixed solution of water and water, or by dissolving it in a high-boiling point organic solvent in advance and adding it to obtain an oil-in-water dispersion emulsion.

However, workability in the printing plate processing process,
From the viewpoint of safety or stability of the treatment liquid over time, a neutral aqueous solution type has recently been desired as a plate surface treatment liquid, and the compounds described in the above patents have high pKa,
It does not give satisfactory results in processing solutions containing no organic solvent. Further, the demand for the printing image quality of the printing plate is increasing year by year, and a treatment liquid containing a compound which does not cause background smear in the image portion of the printing plate in a short time is sufficiently desired. ing.

[0004]

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

[0005]

The above objects of the present invention have been achieved by incorporating the compound represented by Chemical formula 3 or the compound represented by Chemical formula 4 as a lipophilic agent into a treatment liquid.

[0006]

[Chemical 3]

[0007]

[Chemical 4]

In the formula, 1 is 1 to 3, m is 3 to 5, and n is 1
3, r represents an integer of 3 to 7.

This compound has a pKa of about 3-4,
It dissociates even in a neutral aqueous solution and adsorbs to a silver image, improving ink receptivity. The terminal alkyl group (: Cm H2m + 1 or Cr H2r + 1) may have a straight chain or a side chain, but a straight chain is particularly preferable. Also l,
For m, n, and r, l = 1 to 3, m = 3 to 5, n = 1
˜3, r = 3 to 7 can be selected, but 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 is low. Also gets worse. For l and n, l = 1 to 3, n = 1
Any number between 3 and 3 can be selected, but if it is 4 or more, the effect of improving the ink acceptability also weakens. The representative compounds of the compounds used in the present invention are described below, but the invention is not limited thereto.

Examples of compounds of Chemical formula 3

[0011]

[Chemical 5]

[0012]

[Chemical 6]

[0013]

[Chemical 7]

[0014]

[Chemical 8]

[0015]

[Chemical 9]

[0016]

[Chemical 10]

Examples of compounds of Chemical formula 4

[Chemical 11]

[0018]

[Chemical 12]

[0019]

[Chemical 13]

[0020]

[Chemical 14]

[0021]

[Chemical 15]

Basically, the compounds of the chemical formulas 3 and 4 of the present invention can be easily synthesized by converting the corresponding amino compound into isothiocyanate and then subjecting it to reaction cyclization with sodium azide. The details of the synthesis method will be described below using synthesis examples.

Synthesis of Synthesis Example 1 (Formula 6) Calcium carbonate 34 g, N, N-di-n-butylethylenediamine 26 in 400 ml chloroform and 200 ml water.
g is added, thiophosgene 19.6 g is added dropwise thereto, and the mixture is stirred at room temperature for 3 hours for reaction. After separating the chloroform layer, the aqueous layer is further extracted with chloroform and added to the chloroform layer. The solvent was distilled off under reduced pressure from the chloroform layer to obtain 30 g of 2- (di-n-butylamino) ethyl isothiocyanate as a yellowish brown 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, the remaining oil was dissolved in 250 ml of water, and washed with 50 ml of ether three times. 1N hydrochloric acid was added to the aqueous solution to obtain pH = 7 to 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 was 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)

13 C-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 for reaction. After the chloroform layer was separated, the aqueous layer was further extracted, and the chloroform was distilled off under reduced pressure to obtain 18.3 g of 2- (n-hexylthio) ethyl isothiocyanate as a tan oil. Also, 2-
(N-Hexylthio) ethylamine was synthesized by S-alkylating 2-aminoethanethiol with n-hexyl bromide. 2- (n-hexylthio) ethyl isothiocyanate was added to 150 ml of ethanol and 20 ml of water.
It was dissolved in a mixed solution of ml, 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, the remaining oil was dissolved in 250 ml of water, and ether 3 was added.
Wash 5 times with 0 ml. Add pH to the aqueous solution by adding 6N hydrochloric acid.
= 1 to 2, the precipitated oil is chloroform 30 ml
It is extracted 5 times with, dried over anhydrous sodium sulfate.
After sodium sulfate was filtered off, chloroform was distilled off under reduced pressure, and the remaining oil was developed by silica gel column chromatography (chloroform: methanol = 10: 1) and purified to give 1- [2- (n-hexylthio) ethyl. ] -5-
10 g of mercapto-tetrazole was 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 a high solubility in neutral water and exhibits good effects when used in the form of a treatment liquid containing no organic solvent such as alcohol, but of course alcohols, THF, It can be used as a treatment liquid containing an organic solvent such as DMF or acetone, and its effect is not inferior or inferior.

The compound of the present invention is most effectively treated in the form of a solution after the development treatment. However, in the plate making process of an offset printing plate, more specifically, in the silver image developing process and the stopping process. It is also preferable to apply it by making it contained in the development processing solution and the stop processing solution, and it is possible to improve the ink acceptability 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
It is 5 g / l. Further, other additives may be used in combination, and a thickener such as polyvinyl alcohol, glycerin, ethylene glycol may be contained, but these are not essential elements. The treatment liquid of the present invention improves the ink receptivity of the silver image area of the printing plate, while reducing the background stain of the non-image area. In addition, the stability of the treatment liquid over time is also excellent.

An offset printing plate utilizing the silver image of the present invention as ink acceptability is disclosed in Japanese Examined Patent Publication No. 48-3056.
No. 2, JP-A-53-21602, US Pat. No. 3,72.
In addition to 1,559 and 3,490,905, offset printing plates having a silver halide image as ink receptivity, such as U.S. Pat. No. 3,454,398 and JP-A-53-9603, are included. To be done. The present invention will be specifically described below with reference to examples.

[0032]

【Example】

Example 1 In the same manner as described 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. A lithographic printing material was prepared. After exposing the lithographic printing material image-wise, a lithographic printing solution having the following formulation is used at 30 ° C.
For 30 seconds, transfer development was carried out, and subsequently, it was immersed in a stop solution having the following formulation for 30 seconds (25 ° C.), squeezed to remove excess solution, and the material was dried under atmospheric conditions.

<Transfer Developer> 700 ml of water 20 g of sodium hydroxide 60 g of anhydrous sodium sulfite 60 g of potassium bromide 0.5 g of 2-mercaptobenzoic acid 10 mmol of 2-methyl-2-amino-1-propanol 10 g of water And

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

The printing plate thus obtained was applied to an offset printing machine AB Dick 350CD (AB Dick3).
50CD brand name), the plate surface was wiped with the liquid of formula (E), and then printing was performed using a dampening liquid having the following composition.

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

<Moisturizing liquid> (use liquid should be diluted 10 times 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 property and the easiness of stain were determined by the following methods. 1) Ink-accepting property The number of prints until the printed material is obtained with 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 stains 1,000 sheets were printed, and the following three levels were evaluated from the degree of stains on the printed matter at that time. ○ No stain occurs. △ Partial or thin stain × overall thin stain Also, as a comparative compound, the following Chemical formula 16,
Chemical formula 17 was used.

[0039]

[Chemical 16]

[0040]

[Chemical 17]

The evaluation results are summarized in Table 1.

[0042]

[Table 1]

As is clear from Table 1, the compounds of the present invention have a 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 formulation of the treatment liquid was changed to the formulation (F) to treat the plate. Further, these treatment liquids were allowed to stand at 50 ° C. for 2 weeks, and then the same plate-making and printing were performed and evaluated.

[0045]

[Chemical 18]

[0046]

[Chemical 19]

[0047]

[Chemical 20]

[0048]

[Chemical 21]

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

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

[0051]

[Table 2]

As is clear from Table 2, the compound of the present invention can provide a treatment liquid which is excellent in ink receptivity and is excellent in stability over time.

[0053]

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

Claims (1)

[Claims] 1. A processing liquid for an offset printing plate, which contains a compound of Chemical formula 1 or a compound of Chemical formula 2, and uses a silver image as ink acceptability. [Chemical 1] (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.)