JPH09160250A - Plate making method of planograhpic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain a planographic printing plate which uses silver complex salt diffusion transfer method (DTR method) and has high durability against printing and no contamination on the base even when a small amt. of a developer is applied on the printing plate for development. SOLUTION: In this plate making method, a developer is applied on the plate surface of a planographic printing plate which uses DTR method and the amt. of the developer applied is <=60ml per 1m<2> of the planographic printing plate. The developer contains at least each one kind of alkanol amine and 2-mercapto-5-alkyloxa-3,4-diazole having alkyl groups of >=4 carbon number.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate making method utilizing a silver complex salt diffusion transfer method, and more particularly to a plate making method using coating and developing.

[0002]

2. Description of the Related Art A lithographic printing plate supplies both water and ink to a plate surface to selectively receive a coloring ink in an image area and water in a non-image area, for example, an ink on the image. Printing is performed by transferring to a printing medium such as paper.

A lithographic printing plate using a silver complex salt diffusion transfer method (DTR method), particularly a lithographic printing plate having a physical development nucleus layer on a silver halide emulsion layer is described in, for example, US Pat.
No. 114, No. 4,134,769, No. 4,16
0,670, 4,336,321, 4,5
01, 811, No. 4,510, 228, No. 4,
621,041.

The exposed silver halide crystals undergo chemical development in the emulsion layer by development processing to become blackened silver, forming hydrophilic non-image areas. On the other hand, the unexposed silver halide crystals are solubilized by the silver complex salt forming agent in the developer, diffused to the physical development nucleus layer on the surface, and the reducing action of the developing agent on the physical development nuclei causes the ink-accepting image silver. Is deposited as.

The DTR method has a mechanism in which chemical development and dissolution physical development simultaneously proceed in a single development process.
Therefore, in order to obtain a good printed matter, it is important to balance the speed between the area where the chemical development which becomes the non-image area occurs and the area where the dissolution physical development becomes the image area.

For example, if the physical development by dissolution is prioritized over the chemical development, it causes a printing defect due to background stains and softening of the image. On the contrary, if the chemical development has priority over the dissolution physical development, the printing durability becomes poor.

By the way, as a plate making processing method that has been realized for a DTR planographic printing plate, an automatic plate making camera having a built-in developing tank is generally used. That is, after exposure with a plate making camera, the printing plate passes through a developer tank, and the developer remaining on the plate surface after passing is removed by a mechanical method, for example, a method of passing between squeezing rollers having a contact pressure. Next, the pH of the plate
The solution is passed through a neutralizing solution tank in order to prepare the solution, and the neutralizing solution remaining on the plate surface like the developing solution is removed by a mechanical method.

In the plate-making processing method described above, a developer who has a large amount of plate-making processing discharges a large amount of developer liquid, which is a waste liquid. Economically, it was a heavy burden on employers.

[0009] Needless to say, it takes time to pass through the developing solution tank and the neutralizing solution tank, and it also has disadvantages such as fatigue of the developing solution due to processing of a large number of sheets, such as a decrease in pH and generation of sludge. I was

As a processing method for improving these problems, JP-A-48-76603 and JP-A-57-1155 have been disclosed.
No. 49, US Pat. No. 5,398,092, and the like, a method of coating and supplying a developing solution to the plate surface of a lithographic printing plate to make a plate, and Japanese Patent Application No. 5-334028 discloses an instant method in which a very small developing tank is used. Although a treatment method of applying a developing solution while dipping the film is disclosed, it has not been put to practical use due to various problems under conditions different from those of the conventionally put to practical use.

That is, in the developing system having these coating mechanisms, as compared with the immersion developing system, new developing solution is not replenished to the plate surface after coating and supplying, and moreover, the amount of waste of the developing solution is reduced. If you reduce the amount of developer applied,
The slight fluctuation of the coating amount of the developing solution tends to disturb the balance between the chemical development and the physical development, often resulting in background stains and a printing plate having inferior printing durability.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to provide DT
It is an object of the present invention to provide a plate making method capable of stably obtaining a printing plate having high printing durability and free of background stain even when a planographic printing plate utilizing the R method is applied and developed with a small amount of a developing solution.

[0013]

The above object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method, in which a developing solution is applied to the plate surface of the lithographic printing plate. 2-mercapto-5-alkyloxa-3 having an alkanolamine and an alkyl group having 4 or more carbon atoms, the developer having a volume of 60 ml or less per square meter.
It was achieved by a plate making method characterized in that it contains at least one of each of the 4-diazoles.

In the present invention, as a developing method having a coating mechanism, there is generally a method of coating and supplying a developing solution to a photosensitive surface coated with a silver halide emulsion layer.
No. 76603 and the like. For example, there are a liquid application method, a dripping method roller application method, a drop method knife application method, a spray application method, and a brush application method. In addition, bar coater (ETO CHEMICAL APPARATU
The bar coating method using S Co.) and the immersion developing method described in Japanese Patent Application No. 5-334028 are also preferable.

The amount of the developing solution applied to the lithographic printing plate is 10 to 60 ml, preferably 20 to 60 ml, per square meter of the printing plate.
The development time (from the application of the developer,
Time until the developing solution stops the developing effect) is 15 seconds or less, preferably 3 to 10 seconds.

The alkanolamines used in the present invention include (2-aminoethyl) ethanolamine, diethanolamine, N-methylethanolamine, triethanolamine, N-ethyldiethanolamine, diisopropanolamine, ethanolamine, 4-aminobutanol. , N, N-dimethylethanolamine, 3-
Aminopropanol, N, N-ethyl-2,2'-iminodiethanol and the like are available, and one or more kinds can be used in combination.

The amount of the alkanolamine used in the present invention added to the developer is 0.01 to 0.
It is 8 mol, preferably 0.05 to 0.5 mol.

Alkanolamines are known as silver halide solvents and are known to be capable of forming transferred silver with good printing characteristics even in DTR printing plates. However, it was not possible to form a transfer silver having a high printing durability in the plate-making method by coating and developing of the present invention by simply using an alkanolamine, but by using the above-mentioned specific mercapto compound in combination, a lithographic plate having good printing characteristics can be obtained. The printing plate could be stably obtained.

2-mercapto-5 used in the present invention
The alkyloxa-3,4-diazole is a compound having an alkyl group having 4 or more carbon atoms at the 5-position, such as butyl, amyl, hexyl, heptyl, octyl, decyl and dodecyl.

The amount of 2-mercapto-5-alkyloxadiazole used is 0.01 to 50 mmol, preferably 0.05 to 30 mmol, per liter of the developing solution.

In the present invention, thiosulfates, thiosalicylic acid, cyclic imides, thioethers and the like can be used in combination as a silver halide solvent other than alkanolamine. Further, mercapto compounds other than 2-mercapto-1,3,4-oxadiazole, such as mercaptotriazole and mercaptotetrazole, can be used in combination.

In the present invention, in addition to alkanolamines, JP-A-4-324448 and JP-A-4-3285 are also available.
By combining the mesoionic compounds described in No. 59 and the like, more preferable results can be obtained.

Preferred mesoionic compounds are shown below.

[0024]

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[0025]

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The amount of mesoionic compound used is 0.1 to 100 mmol, preferably 0.5 to 50 mmol, per liter of the developing solution.

In the developer used in the present invention, alkaline substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium triphosphate, etc., sulfites as a preservative, thickeners such as hydroxymethyl cellulose, etc. , Carboxymethyl cellulose, antifoggant,
For example, potassium bromide, the compounds described in JP-A-47-26201 and the like, and developers such as hydroquinone and 1-phenyl-3-pyrazolidone can be contained.

In carrying out the DTR method, for example, British Patent Nos. 1,000,115, 1,012,476, and 1,01
No. 7,273, No. 1,042,477, etc., it is possible to incorporate a developer into a silver halide emulsion layer and / or an image receiving layer or another water-permeable hydrophilic colloid layer adjacent thereto. Has been done. Therefore, in such a material, the processing solution used in the developing step may be a so-called "alkaline activating solution" containing no developer.

The silver halide emulsion of the lithographic printing plate used in the practice of the present invention may be silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, etc. Silver is silver halide having 70 mol% or more. These silver halides are spectral sensitizers (light sources, spectral sensitizing dyes depending on applications, such as camera type, laser light type, panchromatic type for color separation, etc.), gelatin hardening agents, coating aids, antifoggants. , A plasticizer, a developer, a matting agent and the like.

Binders for silver halide emulsions are natural and / or synthetic binders commonly used for this purpose.
For example, gelatin, colloidal albumin, cellulose derivative and the like can be used.

An undercoat layer for improving adhesion and / or an undercoat layer for the purpose of preventing halation may be included on the lower side (support surface) of the silver halide emulsion layer.
A matting agent may be included.

The support on which the silver halide emulsion is coated is
Paper, various films, plastic, paper coated with a resin-like substance, metal, etc. can be used.

The physical development nuclei used in the physical development nuclei layer are
Metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead and zinc, and their sulfides are well known as examples of this type of chemical. The physical development nuclei described in JP-A-5-265164 can also be used. The physical development nucleus layer may also contain a developer and may contain a water-soluble binder.

The lithographic printing plate produced by the present invention is, for example, Japanese Patent Publication No. 48-29723, US Pat. No. 3,721,539.
Can be converted or enhanced to ink receptivity by the compounds described in the specification.

The printing method or the desensitizing liquid, dampening liquid or the like to be used can be based on a commonly known method.

[0036]

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

Example 1 As a coating type developing device, the developing device described in JP-A-6-27680 was used.

A lithographic printing plate utilizing the DTR method comprises an antihalation layer containing silica particles on an undercoated polyester film support, an ortho-sensitized silver chloride emulsion layer,
Physical development nucleus layer sequentially applied width 254 mm, length 400
The lithographic printing plate (10th plate) was exposed to a fine line image using a plate making camera having an image reversing mechanism.

As the plate-making treatment liquid, the following developer A and stabilizer were used. The treatment temperature of the developer A and the stabilizer is 30 ° C., the coating amount of the developer A and the stabilizer is 40 ml per square meter of the lithographic printing plate, and the stabilizer is applied 8 seconds after the developer is applied. did.

Developer A: potassium hydroxide 17 g sodium hydroxide 7 g potassium sulfite 44 g N- (2-aminoethyl) ethanolamine 15 g 3-mercapto-4-acetamido-5-n-butyl-1,2,4-triazole Make up to 1000 ml with 0.1 g water.

Neutralizing solution: monopotassium phosphate 32 g phosphoric acid 2 g sodium sulfite 3 g EDTA-Na 1 g Water to 1000 ml.

Instead of the above-mentioned mercaptotriazole in the developer A, 0.5 mmol of 1-phenyl-5-mercaptotetrazole was added to contain the developer B and 2-mercapto-5-heptyloxa-3,4-diazole. 0.
A developing solution C containing 5 mmol was prepared, and a plate-making process was carried out in the same manner as the developing solution A.

For printing, a Heidenberg TOK offset printing machine was used, and the etching liquid was applied all over the plate surface.
Printing was performed using a DTR lithographic printing plate humidifier.

The lithographic printing plate (A) prepared by using the developer A has two ink plates out of ten, and some ink-transfer defects are generated at the leading end and both ends thereof. The fine line was missing and the ground stains occurred. Further, the lithographic printing plate (B) prepared by using the developing solution B had slightly better ink transfer than the lithographic printing plate (A), but the printing durability and background stain of fine lines were similarly poor.
On the other hand, the lithographic printing plate (C) made with the developer C has good ink coverage on all 10 plates, does not cause scumming like the lithographic printing plate (A) up to printing 5000 sheets, and has high printing durability. there were.

For reference, the coating amount of each of the developing solutions A, B and C and the neutralizing solution was 80 per square meter.
When it was carried out in a volume of 0.1 ml, a lithographic printing plate having good ink acceptability, high printing durability and no background stain was obtained from any of the lithographic printing plates prepared by the developing solutions.

Example 2 Instead of N- (2-aminoethyl) ethanolamine of Example 1, N-methylethanolamine or 4-
Example 1 was repeated except that aminobutanol was used. Similar results were obtained.

Example 3 Developer A was prepared by adding 4 mmol of Exemplified Compound 2 as a mesoionic compound to each of Developers A, B and C of Example 1.
Example 1 was repeated except that -1, B-1, and C-1 were prepared and the coating amount of the developing solution was 25 ml per square meter. The planographic printing plates (A-1) and (B-1) prepared by using the developing solutions A-1 and B-1 were 40
When 100 sheets were printed, fine lines of 100 microns were missing and scumming occurred. On the other hand, the lithographic printing plate (C-1) prepared with the developing solution C-1 showed a high printing durability capable of printing 8,000 sheets in all 10 plates.

Example 4 Example 3 was repeated except that Exemplified Compound 7 was used as the mesoionic compound of Example 3. Similar results were obtained.

[0049]

According to the present invention, even if a lithographic printing plate utilizing the DTR method is applied and developed with a small amount of a developing solution, a lithographic printing plate having high printing durability and no background stain can be stably obtained. it can.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Urasaki 3-4 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills, Ltd.

Claims (2)

[Claims] 1. A plate-making method in which a developing solution is applied to the plate surface of a lithographic printing plate using a silver complex salt diffusion transfer method, wherein the coating amount of the developing solution is 60 ml or less per square meter of the lithographic printing plate, and the developing solution is A plate-making method comprising at least one of alkanolamine and at least one mercaptooxadiazole having an alkyl group having 4 or more carbon atoms. 2. The plate-making method according to claim 1, which is a developing solution further containing a mesoionic compound.