JPH06301216A - Judgeing method for fatigue degree of processing liquid for planographic printing plate - Google Patents

Abstract

PURPOSE:To rapidly and easily detect and judge the time to change a fatigued processing liquid by adding an acid-base indicator to the processing liquid for a planographic printing plate. CONSTITUTION:A specified amt. of acid-base indicator is added to a processing liquid for a planographic printing plate which uses a silver complex salt diffusion transfer method. In this case, the acid-base indicator is preferably added to any of a developer and stabilizer. However, since pH of the developer in a strong alkali region differs much from pH of the stabilizer in an acid region side, different indicators shoud be used. To detect more accurately the fatigue degree, indicators respectively for a developer and a stabilizer may be added. These acid-base indicators are well-known and commercially available. For example, when the indicator is to be used in the high pH side for a developer, phenolphthalein or alizarin yellow is used. For a neutral region, bromocresol purple, bromothymol blue, phenol red, etc., is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing solution for a lithographic printing plate, particularly a lithographic printing plate to which a silver complex salt diffusion transfer method is applied. The present invention relates to a method for determining the degree of fatigue of a lithographic printing plate processing liquid, which is characterized by making a determination.

[0002]

2. Description of the Related Art A processing solution for a lithographic printing plate, particularly a lithographic printing plate using a silver complex salt diffusion transfer method, is composed of two solutions, a developing solution and a neutralizing solution. Is processed into a printable printing plate. Developers are generally high p
The lithographic printing plate processing liquid in the H region, particularly utilizing the silver complex salt diffusion transfer method, is used for the purpose of reducing the silver halide in the plate to metallic silver. The current developers are roughly classified into two types: a developer type in which a developing agent is added to the solution and an activator type in which the developing agent is not included in the solution because the developing agent is added to the plate. It can be divided into liquids. In particular, many of the silver complex salt diffusion transfer methods are activator types, and their performance is that the composition of the solution can be simplified, and the storage stability of the solution against air oxidation is better and longer than that of the developer type. It's life.

The neutralizing solution is used for the purpose of stopping the development reaction and fixing and stabilizing the image, and its main component contains a pH buffering agent such as citric acid or phosphoric acid. In addition, various chemicals may be added in order to improve printability such as water retention, printing durability, and ink riding property of the printing plate after development.

The fatigue level of a general processing liquid or the timing of liquid replacement is controlled mainly by measuring the pH and conductivity of the processing liquid.
It is known that, especially in the case of the activator type, the degree of fatigue of the developer is almost proportional to the degree of decrease in pH, and the neutralizing solution used in combination with this type of developer also has the degree of fatigue and pH.
It is easy to manage because it is proportional to the rising rate of. However, this measurement operation is still troublesome because it is necessary to periodically collect the liquid or insert the electrode part of the simple measuring instrument for pH or the like into the processor. Also, some processors have a built-in measuring device for pH, etc. for the purpose of liquid management, but this is easy to manage, but the cost of the device itself is high, and the calibration operation of the measuring device is also troublesome. Not very practical.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention relates to a planographic printing plate, particularly a planographic printing plate processing liquid to which a silver complex salt diffusion transfer method is applied. An object of the present invention is to provide a method for judging the degree of fatigue of a lithographic printing plate processing liquid, which is characterized by easily detecting and judging.

[0006]

[Means for Solving the Problems] The solution to the above problems has been achieved by adding a certain amount of an acid-base indicator to a lithographic printing plate processing solution to which a silver complex salt diffusion transfer method is applied. .

The acid-base indicator preferably used in the present invention may be added to either the developing solution or the stabilizing solution.
However, since the pH of the developing solution and that of the stabilizing solution are divided into a strong alkaline side and an acidic side, different indicators must be used. If it is necessary to detect the fatigue level more reliably, each indicator may be added to both the developing and stabilizing solutions.

These acid-base indicators are known and are commercially available. For example, when used in a developing solution on the high pH side, phenolphthalein, alizarin yellow,
When used near neutral, bromocresol purple,
There are bromothymol blue, phenol red and the like.

It is desirable that the acid-base indicator used in the present invention is contained in an amount of 0.01 to 1% by weight, preferably 0.03 to 0.3% by weight, based on at least the lithographic printing plate processing liquid.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide,
Lithium hydroxide, sodium triphosphate, sulfite as a preservative, silver halide solvent such as thiosulfate, thiocyanate, cyclic imide, 2-mercaptobenzoic acid, amine and the like, viscous agent such as hydroxyethyl cellulose,
Antifoggants such as carboxyethyl cellulose such as potassium bromide, compounds described in JP-A-47-26201, developers such as hydroquinones, catechol, 1
Development modifiers such as -phenyl-3-pyrazolidone and the like, such as polyoxyalkylene compounds and onium compounds, may be included. Further, in the developing solution, US Pat.
Compounds such as those described in No. 776,728, which improve ink transfer of the surface silver layer, can be used.

In carrying out the silver complex salt diffusion transfer method, for example, British Patent Nos. 1,000,115 and 1,01
No. 2,476, No. 1,017,273, No. 1,042,4
As described in the specification of No. 77 and the like, a developer is incorporated into a silver halide emulsion layer and / or an image receiving layer or another water permeable layer adjacent thereto. Therefore, as the processing liquid used in the developing stage in such a material, a so-called "activator type developing liquid" containing no developer can be used.

The lithographic printing plate is composed of an oleophilic image-forming portion that receives ink and a hydrophilic non-image-forming portion that does not receive ink, and the non-image-forming portion generally receives water. Therefore, in normal lithographic printing, both ink and water are supplied to the plate screen, and the image area selectively receives the colored ink and the non-image area selectively receives the water to transfer the ink on the image to the paper. It is done by letting.

Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the surface of the image area and the non-image area is sufficiently large, and when the water-ink in the emulsified state comes, It is necessary that the line parts sufficiently receive the ink and the non-image parts sufficiently receive the water. The lithographic printing plate relating to the invention is also printed on the same principle.

One of the lithographic printing plates relating to the present invention is a lithographic printing plate to which the silver complex salt diffusion transfer method is applied. This printing plate material has silver precipitation nuclei in the hydrophilic polymer binder layer or on the surface thereof, and silver halide crystals in the emulsion layer undergo chemical development by silver complex salt diffusion transfer processing to become black silver and become hydrophilic. Form a non-image area. On the other hand, unexposed silver halide crystals become a silver salt complex by the silver salt complexing agent in the developing solution and diffuse to the physical development nuclei layer on the surface. An image area mainly composed of developed silver is formed. Here, the silver image is made ink-receptive and the surface of the hydrophilic binder in the non-image area is made ink-repellent for printing. The surface of the hydrophilic binder is hydrophilic but poor in water retention, and the repulsion of the printing ink is extremely poor. Therefore, ink stains on the non-image area due to printing are remarkable, and it cannot be practically used at all. As a method of improving the ink resilience of the surface of this kind of binder, it is known to roughen the surface by means such as dispersing fine particle powder such as silica or starch in the binder layer to impart water retention property. There is.

The hydrophilic binder forming the ink repellent emulsion layer used in the present invention is gelatin, acylated gelatin, graft gelatin, water-soluble gelatin, starch, dextrin, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylacrylamide. , Carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl methyl ether, methyl vinyl ether / maleic anhydride copolymer, styrene / maleic anhydride copolymer, isobutylene / maleic anhydride copolymer, polyvinyl alcohol and styrene maleic anhydride copolymer Condensate, condensate of polyvinyl alcohol and isobutylene / maleic anhydride copolymer, gum arabic, albumin, sodium alginate, cellulose sulfate, described in JP-A-53-21602. Tetrafunctional synthetic polymers such as various natural or synthetic polymers are used alone or in combination of two or more. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer. The lithographic printing plate which is the object of the present invention contains gelatin, and the containing layer may be an undercoat layer, an emulsion layer or a physical development nucleus layer.

In order to provide the above emulsion layer with sufficient mechanical strength as a printing plate, formalin, glyoxal, glutaraldehyde, tannic acid, urea, dimethylolurea and ethyleneurea resin are used as a hardening agent for gelatin contained in the emulsion layer. One or more N-methylol compounds such as N-methylol compounds, organic compounds such as mucohalogenic acids (mucochloric acid, mucobromic acid), and inorganic compounds such as chromium alum and potassium alum are used as necessary. The hardener can be added to all layers, or some or only one layer. Of course, the diffusible hardener can be added to only one layer in the case of simultaneous coating of two layers. As an addition method, it may be added at the time of emulsion production or in-line at the time of coating.

The silver halide emulsion can be sensitized in various ways as it is manufactured or coated. It is preferred to chemically sensitize by methods well known in the art, for example with sodium thiosulfate, alkyl thioureas, or with gold compounds such as gold rhodanide, gold chloride, or a combination of both. Further, the silver halide emulsion can be positively or negatively sensitized or desensitized with a dye such as cyanine or merocyanine. There is no particular limitation on the wavelength range that can be sensitized or desensitized. Therefore, ortho sensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, semiconductor laser sensitization can be performed, and UV sensitization and visible light desensitization for bright rooms. I can do it.

Above the emulsion layer is a physical development nucleus layer containing physical development nuclei. Physical development nuclei include fine particles of metal colloid such as silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold and platinum, and sulfides, polysulfides, selenides of these metals, or those. It may be a mixture or mixed crystal of. The physical development core may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, vinyl imidazole and acrylamide It may contain a polymer, a hydrophilic polymer such as polyvinyl alcohol, or an oligomer thereof, and the content thereof is 0.5.
It is preferably g / m ² or less. Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone and catechol, and a known hardener such as formalin and dichloro-s-triazine.

The surfactant is generally used as a wetting agent for improving the wetting when forming the hydrophilic polymer binder layer on a suitable strip-shaped substrate. In particular, in a lithographic printing plate having a silver image to which the silver complex salt diffusion transfer method is applied as an ink accepting property, it may be contained as a coating aid in any of the antihalation layer, emulsion layer and physical development nucleus layer. You can stay. The activator may be any of cationic, anionic, amphoteric or nonionic type. The proper amount of the surfactant used as a coating aid is preferably in the concentration range of 1% to 0.01% in terms of moisture in the layer forming coating liquid. Further, an antifoggant, a thickener, and an antistatic agent can be included.

The support for the planographic printing plate material of the present invention includes polyethylene terephthalate, polycarbonate,
Synthetic resin film such as polypropylene and polystyrene,
Any polyolefin-coated paper, polyolefin laminated film, or aluminum-reinforced composite support that can withstand lithographic printing can be used. Also,
The surface of these supports may be surface-treated in order to improve the adhesion to the coating layer.

The present invention is applicable to lithographic printing plate materials having a roughened hydrophilic binder surface. As a method for forming a roughened surface, a method using a support having a roughened surface, a method of molding the surface of the hydrophilic binder layer using a rough surface roll, etc., fine particles on the surface of the hydrophilic binder layer There are a method of incorporating powder and a method of combining these. The roughening of the support having a hydrophobic surface can be obtained by a solvent processing method, a foaming method, a pressure bonding method using a rough surface body, or the like. These suitable combinations give more favorable results in the present invention. The depth of these rough surfaces is preferably 2 to 20 μ, and the size is about 10 to 100 μ. As used herein, "depth" refers to the distance from the uneven valley on the surface to the top of the mountain, and "size" refers to the distance from the mountain to the mountain.

The printing plate obtained from the planographic printing plate material of the present invention is ink repellent to a processing solution for desensitizing treatment which is carried out as necessary during printing, and further to dampening water supplied during printing. Colloidal particles such as silica and alumina, and a polyol compound such as ethylene glycol, diethylene glycol, α-propylene glycol, and glycerin may be contained for the purpose of assisting the water retention of the surface.

[0023]

EXAMPLES Next, representative examples of the present invention will be explained, but the present invention is not limited to them.

Example A lithographic printing plate utilizing the silver complex salt diffusion transfer method was prepared under the following conditions and procedures. Roughness of the surface is an average depth of 7μ,
After hydrophilic treatment of the rough surface of a double-sided polyethylene-coated paper support having a roughened surface with an average size of 50μ by corona discharge, a liquid having the following composition was used in a moisture content by changing the amount of gelatin. It was applied so as to be 60 cc / m ² . Gelatin 3.5 g Silica (average particle size 7 μ) 10 g Titanium oxide 50 g Formalin (12% aqueous solution) 3 ml Carbon black dispersion (solid content 32%) 5 ml Saponin (10% aqueous solution) 10 ml Latex 50 g Add water to bring the total volume to 600 cc Do

Furthermore, an ortho-sensitized high-sensitivity silver halide emulsion having the following composition was added at a moisture content of 13 cc / m ²
Was applied. Silver halide emulsion (silver chlorobromide emulsion prepared using 15 g of silver nitrate and 12 g of gelatin) (gelatin, equivalent to 0.72 g / m ² ) 96 g Silica (average particle size 7 μ) 1 g Formalin (12% aqueous solution) 3 ml Interface Activator (10% solution) 10 ml Add water to bring the total volume to 130 cc

Furthermore, a palladium sulfide (silver precipitation nucleus) sol prepared by the following method was added thereto at a speed of 15 m / min.
And a wind pressure of 80 mmHg. Liquid A Palladium chloride 2 g Water 20 ml B liquid Sodium sulfide 0.2 g Water 20 ml C liquid Methyl vinyl ether / maleic anhydride copolymer (1.25% solution) 20 ml Saponin (10% aqueous solution) (as coating aid) 20 ml Hydroquinone 50 g 1-Phenyl-3-pyrazolidone 5 g Formalin 30 ml Surfactant 12.5 ml Water is added to bring the total amount to 1250 cc.

Mix the liquids A and B with stirring,
After a minute, this was added to the liquid C to prepare a coating liquid.

The lithographic printing plate material thus obtained was subjected to image exposure for 20 seconds by a camera having an image reversal mechanism, and a silver complex salt diffusion transfer developing solution having the following composition was used.
Development processing was performed at 30 ° C. for 30 seconds. Sodium hydroxide 20 g Potassium hydroxide 35 g Anhydrous sodium sulfite 100 g 1-Phenyl-3-pyrazolidone 1 g 1-Ethyl-2-mercaptobenzimidazole 0.05 g 3-Mercapto-4-acetamido-5-n-heptyl-1,2, 4-triazole 0.1 g A: ..... (See Table 1) Add water to bring the total volume to 2000 ml.

After the development treatment, the printing plate material was removed with a squeezing roller to remove the developing solution, and a neutralizing solution having the following composition was used to remove the developing solution.
The solution was treated at 20 ° C. for 20 seconds, the squeezing roller was used to remove the liquid, and the product was dried. Colloidal silica (20% solution) 1 g Sodium sulfite 10 g Potassium phosphate 50 g Phosphoric acid 5 g B: Indicator ... (See Table 2) Add water to make 1000 ml.

A lithographic printing plate was prepared by the above operation, and at the same time, a change in color due to the acid-base indicator added to the liquid was observed. In addition, the printing plate after plate making is mounted on the offset printing machine,
Immediately after printing the plate surface with the desensitizing solution, printing was performed.

The printing conditions at that time are as follows. Printer: RYOBI 3200 Ink: NEW-CHAMPION Black (S) (manufactured by DIC) Moisturizing liquid: Eu-3 1% aqueous solution (manufactured by Fuji Photo Film Co., Ltd.) Printing speed: 4000 sheets / hour Number of printed sheets: 5000 sheets

The type and amount of the acid-base indicator in the practical test are described below.

[Table 1]

[0033]

[Table 2]

First, an undeveloped plate is continuously passed through a processing solution with a new solution having a pH of 13.6 to change the color and p during plate-making.
As a result of observing H, alizarin yellow showed pH = 12 to 1
About 1 to purple to yellow, phenolphthalein pH
= Around 11 the color gradually changed from red to colorless. Further, preliminary printing tests and the like have revealed that the pH value at which the photographic properties and printability of the printing plate begin to deteriorate due to the fatigue of the developing solution is exactly in the range of 12 to 11. From the above, it becomes possible to easily know the timing of liquid change from the color change of the indicator in the developer.

Further, the same test as the developing solution was conducted in the neutralizing solution at the same time. As a result, in the case of bromocresol purple, the new solution having pH = 5.3 changed from yellow to purple at pH = 6.2, bromothymol blue, In the case of phenol red,
Around pH = 6.5, the color changed from yellow to blue and red, respectively. In the case of the neutralizing solution, it is known that the deterioration of the performance of the printing plate is around pH = 6.5 as in the case of the developing solution. Therefore, it is possible to easily know the time of changing the solution from the above.

Further, as a result of printing the printing plate after the treatment, the printing plate treated by adding the acid-base indicator to the treatment liquid is better in photographic property and printability than the printing plate treated without addition. The results were the same, there was no effect on the printing plate, and there was no problem regarding the life of the liquid in the comparative test.

[0037]

According to the embodiments of the present invention, it becomes possible to promptly detect the liquid replacement timing of the fatigued processing liquid,
In addition, it became possible to facilitate proper management of the processing liquid. It was confirmed that this method did not adversely affect the processing liquid and the printing plate.

Claims (1)

[Claims] 1. A method for judging the degree of fatigue of a processing solution, which comprises adding an acid-base indicator to a processing solution for a lithographic printing plate.