JPH06127168A - Treatment solution for offset printing plate - Google Patents

Abstract

PURPOSE:To enhance the ink receptivity of the silver image formed on an offset printing plate by adding a compd. represented by a specific chemical formula to the treatment soln. used in the offset printing plate utilizing the silver image as an ink receiving image. CONSTITUTION:A treatment soln. for an offset printing plate is used in the offset printing plate utilizing a silver image as an ink receiving image. At this time, a compd. represented by chemical formula (wherein R<1> is a 3-8C alkyl group, R<2> is a hydrogen atom or a 3-8C alkyl group and n is an integer of 2-4) is added to the treatment soln. The ink receptivity of the silver image formed on the offset printing plate is enhanced by the treatment soln. That is, the silver image of the offset printing plate is treated with the treatment soln. in a printing process to enhance the ink receptivity of the silver image itself.

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 a 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 part 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 which improves 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 treatment liquid for an offset printing plate which 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 a compound represented by Chemical formula 2 or a compound represented by Chemical formula 4 as a lipophilic agent into a treatment liquid.

[0006]

[Chemical 2]

[In the formula, R ¹ is an alkyl group having 3 to 8 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 3 to 8 carbon atoms. n is an integer from 2 to 4. ]

The terminal alkyl group may have a straight chain or a side chain, but a straight chain is particularly preferable.
When the carbon number of the alkyl group is 2 or less, the effect of improving the ink receptivity becomes weak, and when the carbon number of 9 or more, the solubility in the treatment liquid is low and the effect of improving the ink receptivity becomes weak. Further, the number of alkyl groups may be one or two, but those having one alkyl group are particularly preferable in terms of the effect of improving the ink acceptability of a silver image. Further, when the number (n) of methylene chains is 5 or more, the ink acceptability of a silver image and the temporal stability of the processing liquid are deteriorated, so 2 or more and 4 or less are preferable. The representative compounds of the compounds used in the present invention are described below,
It is not limited to these.

[0009]

[Chemical 3]

[0010]

[Chemical 4]

[0011]

[Chemical 5]

[0012]

[Chemical 6]

[0013]

[Chemical 7]

[0014]

[Chemical 8]

[0015]

[Chemical 9]

[0016]

[Chemical 10]

[0017]

[Chemical 11]

[0018]

[Chemical 12]

[0019]

[Chemical 13]

[0020]

[Chemical 14]

The compound of formula 2 of the present invention is synthesized by using alkylamine or dialkylamine and thiirane or the like.
Can be easily synthesized. Details of the synthesis method will be described in the following synthesis example.

Synthesis of Synthesis Example 1 (Chemical Formula 6) 9.6 g of n-heptylamine was dissolved in 100 ml of THF, 5.0 g of thiirane was dissolved in 40 ml of THF, and the mixture was heated under reflux for 5 hours. From the reaction solution, THF was distilled off under reduced pressure, and the remaining liquid was distilled under reduced pressure to obtain 8.5 g of n-peptylaminoethanethiol as a transparent liquid.
bp. 83 ° C (10 mmHg)

1 H-NMR (CDCl ₃ ): δ (ppm
) 2.80 (2H, m, CH ₂ ) 2.68 (2H, m, CH ₂ ) 1.48 (4H, m, C)
H ₂ ) 1.29 (9H, m, CH ₂ + SH) 0.91 (3H,
t, CH ₃ )

13 C-NMR (CDCl ₃ ): δ (ppm) 51.9 (N-CH ₂ ), 49.0 (N-CH ₂ ), 3
1.4, 29.8, 28.6, 26.9, 24.6, 2
2.2, 13.7 (CH ₃ )

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 development process of silver image 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 the ink acceptability of the plate can be improved.

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. Sho 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.

[0028]

【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 subjected 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 Isopropanol 400 ml Water 600 ml

<Moisturizing liquid> (use liquid is 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 stains 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 12,
Chemical formula 13 was used.

[0035]

[Chemical 15]

[0036]

[Chemical 16]

The evaluation results are summarized in Table 1.

[0038]

[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.

[0041]

[Chemical 17]

[0042]

[Chemical 18]

[0043]

[Chemical 19]

[0044]

[Chemical 20]

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

Chemical compounds 17, 18, and 1 as comparative compounds
9 and 20 were used. The evaluation results are shown in Table 2. The results of the treatment liquid after aging are shown in the lower row.

[0047]

[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 stability over time.

[0049]

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 compound of formula 1 is included,
A processing liquid for offset printing plates that uses a silver image as ink acceptability. [Chemical 1] [Wherein R ¹ is an alkyl group having 3 to 8 carbon atoms,
R ² is a hydrogen atom or an alkyl group having 3 to 8 carbon atoms. n is an integer from 2 to 4. ]