JP2907652B2 - Plate surface treatment liquid for lithographic printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate surface treating solution for improving the ink receptivity of an image portion at the start of printing in a lithographic printing plate utilizing image silver as ink receptivity.

[0002]

2. Description of the Related Art Printing plates using silver halide emulsions having high sensitivity and spectral sensitization have already been put into practical use in several forms. Among them, US Pat. No. 3,721,559, US Pat. No. 3,490,905, and Japanese Patent Publication No. Sho.
Nos. 8-30562, U.S. Pat. Nos. 3,385,701 and 3,814,603, JP-B-44-27242, JP-A-53-21602, U.S. Pat. 5
No. 3-9603.

Although these are roughly classified into several types of printing plate manufacturing methods, they are common in that image silver is made ink receptive. A lithographic printing plate is composed of an image portion that receives a new oil-based ink and a non-image portion that is hydrophilic and receives water. Therefore, in normal lithographic printing, both water and ink are supplied to the printing plate, the image portion selectively receives color ink, the non-image portion selectively receives water, and the ink on the image line is, for example, paper. This is done by transferring it to a substrate.

[0004] In order to obtain good printed matter, it is required that the difference between the lipophilicity and the hydrophilicity of the surface of the image portion and the non-image portion is sufficiently large.

The plate making method using the above-mentioned silver halide emulsion is simple, reliable and quick, can be automated, and has the features of high sensitivity, high resolution and high image reproducibility. However, the difference between the lipophilicity and the 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 realized from an organic colloid such as a diazo photosensitive material.

In order to overcome such a disadvantage, Japanese Patent Publication No. Sho 48
JP-A-29723 and JP-A-58-127928 show that a compound having a mercapto group or a thione group acts on a silver image to improve ink receptivity. That is, the difference in lipophilicity and hydrophilicity between the image portion and the non-image portion is such that the mercapto group or the like of the compound is adsorbed on the image silver and the hydrophobic region of the compound covers the image silver. It is considered.

However, most of the above-mentioned compounds having a mercapto group or the like are insoluble in water or soluble only in an alkaline solution, and are weakly acidic at a pH of 5 to 7 as required for a plate surface treatment solution according to the present invention. It did not dissolve in the area. Conventionally, to dissolve the compound,
Solvents such as ethyl alcohol and isopropyl alcohol have been used.

[0008]

At present, reduction of the solvent component, particularly reduction of the solvent having a low boiling point, is said from the viewpoint of environmental problems and safety. Generally, attempts have been made to solubilize the above compounds with a surfactant. Although a method using a surfactant is effective as a solubilization method, a compound having a mercapto group or the like is present in micelles of the activator in solubilization with the activator, so that the ink has a sufficient ink receiving effect. It had the disadvantage that it could not be obtained.

It is an object of the present invention to provide a compound having a mercapto group or a thione group in a weakly acidic pH range of 5 to 7 required for a stabilizing solution and an etching solution without using a solvent component. Solubilization without impairing the improvement effect.

[0010]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
The object of the present invention has been attained by providing, in a plate surface treating solution for a lithographic printing plate utilizing image silver as ink receptivity, at least one or more compounds having a mercapto group or a thione group and an amine compound.

The amine compound used in the present invention includes amino alcohols such as monoethanolamine, diethanolamine, triethanolamine and aminoethylethanolamine; monoamines such as propylamine and butylamine; diamines such as dimethylaminoethylamine;
Polyamines such as N-aminopropylpropanediamine; and cyclic amines such as pyridine and piperidine. Preferred are amino alcohols. These amine compounds can be obtained from Nippon Emulsifier Co., Ltd., Koei Chemical Industry Co., Ltd. or the like.

The compounds having a mercapto group or a thione group used in the present invention are described in JP-B-48-29723 and JP-A-58-127728. Basically, it has a structure consisting of a mercapto group or a thione group and a lipophilic group.

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

[0014]

Embedded image

(Wherein R is hydrogen, an alkyl group having 12 or less carbon atoms, allyl group, aralkyl group, and Z is N, C
And the remaining atomic groups necessary to form a 5- or 6-membered ring together with )

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; And those condensed with a naphthalene ring.

A typical example of such a compound is 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-imidazolidin-
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-acetamido-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,
Amino-4-mercapto-6-benzyl-1,3,5-
Triazine and the like, and the mercapto compound and the like can be contained in the treatment solution in an amount of 0.1 to 3 g / l, preferably 0.5 to 1 g.
/ L concentration.

The amine compound used in the present invention is in a weight ratio of 5: 1-30:
It is preferable to add and mix in water at a ratio of 1, preferably 10: 1 to 20: 1. Thereafter, the mixture is prepared by adding other compounds or the like as necessary to the mixed solution, or the mixed solution is added to a solution containing other additives or the like to prepare the mixed solution.

As described above, the present invention relates to a plate surface treatment solution for improving the ink receptivity at the start of printing on a lithographic printing plate using image silver as ink receptivity, and from the development process to the start of printing. Is a plate surface treatment liquid to be applied to the printing plate surface. In addition to the above compounds, commonly used buffers, preservatives, preservatives, wetting agents, surfactants, desensitizing agents, and the like can be mixed with the plate surface treating solution. For example, phosphoric acid, inorganic acids such as sulfuric acid, succinic acid, organic acids such as propionic acid, polyvinyl alcohol,
Water-soluble synthetic polymers such as polyacrylic acid, arabic gum,
Natural polymers such as hydroxycellulose, polyol compounds such as polyethylene glycol and glycerol, inorganic fine particles such as colloidal silica, and complexing agents such as iminodiacetic acid and ethylenediaminetetraacetic acid.

Regarding a lithographic printing plate utilizing image silver as ink receptivity, a silver halide emulsion can be contained in the printing plate itself or as a silver source for a printing plate having an image receiving layer by a silver diffusion transfer method. It may be on another negative sheet.

The silver halide emulsion includes silver chloride, silver bromide,
Any of silver chlorobromide and those containing iodide may be used.The binder is preferably gelatin, but a part or all of the gelatin may be replaced with another colloidal substance, for example, casein, albumin, a cellulose derivative or the like. Good. Silver halide is 0.5-7 g / m in terms of silver nitrate
² , The binder can be used usually in the range of 0.5-10 g / m ² .

The method for producing a silver halide emulsion can be produced by a method known in the ordinary photographic industry. Particularly, a method for use in a printing plate is disclosed in the above-mentioned known patent documents. Can be helpful.

The lithographic printing plate used in the present invention is generally treated with an alkali developer after image exposure. As such a developer, any one of an ordinary photographic developer containing a developing agent such as hydroquinone, a developer of a silver diffusion transfer method containing hypo and the like, or a high alkali developer obtained by converting them into an activator can be used.

[0024]

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

Example 1 A matted layer containing silica particles having an average particle size of 5 μm was provided on one side of a polyester film support having been subjected to a subbing treatment, and the opposite side was provided with carbon black in such an amount that the light reflectance was 3%. An anti-halation undercoat layer (adjusted to pH 4) containing 20% by weight of silica powder having an average particle diameter of 7 μ with respect to photographic gelatin, and a silica powder having an average particle diameter of 7 μ after chemical sensitization. 5% by weight based on gelatin
And a high-sensitivity silver chloride emulsion (adjusted to pH 4) spectrally sensitized to the green sensitive region containing the above-mentioned ratio.

The gelatin for the undercoat layer was applied at a rate of 3.5 g / m ² , the gelatin for the emulsion layer was applied at a rate of 0.8 g / m ² , and the silver halide was converted to silver nitrate at a rate of 1.0 g / m ² . The undercoat layer and the emulsion layer contain formalin as a hardening agent in an amount of 5.0 mg / g gelatin based on gelatin. After drying and heating at 40 ° C. for 14 days, the plate No. A lithographic printing plate is manufactured by applying and drying the core coating solution described in No. 31. The silver halide emulsion was obtained by adding 4 × 10 ⁻⁶ mol of rhodium chloride per mol of silver halide at the time of physical ripening, and had an average grain size of 0.4 μm.

The thus obtained lithographic printing plate precursor is image-exposed with a plate making camera having an image reversing mechanism, developed with the following developer (used solution) at 30 ° C. for 30 seconds, and then developed as follows. Treated with stabilizing solution. <Developer> Sodium hydroxide 24 g Potassium hydroxide 8 g Anhydrous sodium sulfite 50 g 2-Methyl-2-amino-1-fluoroethanol 30 g Make up to 1 liter with water. <Stabilizing solution> Phosphoric acid 1.2 g Sodium diphosphate 25 g Anhydrous sodium sulfite 2.5 g Ethylene glycol 5 g Colloidal silica (20% aqueous solution) 1 g Make up to 1 l with water. (Adjusted to pH 6)

The printing plate prepared by the above operation is set on an offset printing machine, and a plate surface treating solution as shown below is applied to the printing plate.
-Trademark of Dick offset printing press), A for ink
B-Dick 3-1012 ink, OD30 for humidifier
(Moisturizing liquid manufactured by Mitsubishi Paper Mills) was used for printing.

Citric acid 2 g Sodium citrate 2 g Polyethylene glycol 29 g Colloidal silica (20% aqueous solution) 11 g Mercapto compound 1 g Solubilizer 20 g Make up to 1 l with water. (Adjusted to pH 6) Combinations of mercapto compounds and solubilizers are as shown in Table 1.

[0030]

[Table 1]

Compound A in Table 1 is 2-mercapto-5
n-heptyl-oxadiazole, and sur-1 is polyoxyethylene octyl phenyl ether, sur
-2 is sodium stearylbenzenesulfonate.

The ink acceptability was evaluated as the number of prints until a print was obtained at a good image density, with the paper being fed simultaneously with the contact of the ink with the plate surface. The liquid stability was determined based on the state of crystal precipitation after storage at low temperature. The results are shown in Table 2.

[Table 2]

As can be seen from the results, the present invention achieved ink acceptability equivalent to that of the conventional solvent solubilization without using a solvent. It was also excellent in liquid stability. Ink receptivity and liquid stability could not be obtained by a simple method of reducing the amount of solvent or using a surfactant.

Example 2 The same test was conducted for the following mercapto compounds in place of the mercapto compound A in Example 1. 2-mercapto-4-phenylimidazole 3-dodecyl-benzothiazoline-2-thione 3-mercapto-4-amino-5-heptadecyl-1,
2,4-triazole 2-amino-4-mercapto-6-benzyl-1,3,3
5-triazine

The evaluation results of the ink receptivity correspond to the results of Example 1. The compound having a mercapto group or the like can be dissolved in the treatment solution without using a solvent, and the ink receptivity is improved. The effect was also recognized.

[0036]

According to the embodiment of the present invention, a compound having a mercapto group or a thione group which has been conventionally added to a lithographic printing plate surface treatment liquid for improving ink receptivity can be obtained without impairing this effect, and It could be solubilized without using a solvent.

Continuation of the front page (56) References JP-A-2-207255 (JP, A) JP-A-2-207256 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7 / 07

Claims (1)

(57) [Claims] Claims: 1. A lithographic printing plate surface treating solution comprising at least one or more water-insoluble mercapto compounds or thione compounds and an amine compound and utilizing image silver as ink receptivity.