JPH0651521A - Plate making method for planographic printing plate - Google Patents

Abstract

PURPOSE:To enable rapid plate making processing and the reproduction of a large quantity of planographic printing plates always with stable characteristics and further, to drastically decrease the volume of a waste liquid by supplying a neutralizing liquid only to the surface coated with silver halide emulsion layers CONSTITUTION:The planographic printing plate M is transported by transporting rollers 1a, 1b. The developer is supplied by a fixed delivery pump P1 and flows out of a slit aperture 5. This developer is supplied only to the surface coated with the silver halide emulsion layers. The excess developer is squeezed by developer squeezing rollers 2a, 2b. The neutralizing liquid is fed by a fixed delivery pump P2 and flows out of a slit aperture 7. This neutralizing liquid is supplied only to the surface on which the developer acts. The excess neutralizing liquid is squeezed by neutralizing liquid squeezing rollers 3a, 3b. The squeezed developer and neutralizing liquid are respectively recovered in recovering trays W1, W2 and are discharged to the outside.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for making a lithographic printing plate by a silver complex salt diffusion transfer method.

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image-forming portion that accepts oil-based ink and an oil-repellent non-image-forming portion that does not receive ink. Generally, the non-image-forming portion is hydrophilic. It is composed of sex parts. In ordinary lithographic printing, both water and ink are supplied to the plate surface, the image area selectively receives the coloring ink, and the non-image area selectively receives water, and the ink on the image area, such as paper Printing is performed by transferring it to a printing medium.

Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the image area and the non-image area is sufficiently large, and the image area is sufficient when water and ink are supplied to the plate surface. It is necessary to accept a certain amount of ink and not to accept ink in the non-image area.

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. 3,72.
No. 8,114, No. 4,134,769, No. 4,1
No. 60,670, No. 4,336,321, No. 4,
No. 501,811, No. 4,510,228, No. 4,621,041 and the like. The exposed silver halide crystals cause chemical development by DTR development to give a black color. It becomes silver and forms a hydrophilic non-image area, while 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 nucleus layer on the surface to form nuclei. In the presence of the above, physical development is caused to form an image area mainly composed of ink-receptive physically developed silver.

[0005] In the plate making method in which such a lithographic printing plate has been realized, an automatic plate making camera having a developing tank and a neutralizing tank is used. That is, in the case of plate making with the above automatic plate making camera, after immersing the lithographic printing plate in a developing solution, the developing solution is mechanically processed, for example, by passing the lithographic printing plate between squeezing rollers having a certain contact pressure to obtain a plate surface. The developer above is forcibly removed. The planographic printing plate obtained by squeezing the developing solution still has a high plate surface pH, and if it is left as it is, the storage stability and ink acceptability of the planographic printing plate are extremely deteriorated. The planographic printing plate is immersed in a neutralizing solution having pH buffering ability (sometimes called a stabilizing solution) to adjust the plate surface pH from neutral to weakly acidic. The neutralization liquid is described in, for example, Japanese Patent Publication No. 56-41992.

In such a current plate making method, a user who uses a large amount of planographic printing plates produces a large amount of waste liquid discharged from the automatic plate making camera, and installs a very large tank. Must be frequently collected in centralized processing facilities. This is a huge mental and financial burden on the user.

Further, the conventional plate-making method using a plate-making camera for dip-developing a lithographic printing plate is not sufficient in terms of rapid processing, and further, the pH is lowered and the developing rate is lowered by continuing the treatment, and silver sludge There are many drawbacks such as generation of a drag pattern due to the generation and movement of the developer, and image deletion due to the flow of the silver complex. Also, maintenance is troublesome.

Japanese Unexamined Patent Publication Nos. 48-76603 and 57
JP-A-115549 discloses a method of plate-making by applying and supplying a developing solution in an amount necessary for developing a lithographic printing plate onto the plate surface. However, this method has the advantage that the planographic printing plate can always be developed with a fresh developer and the amount of developing waste liquid is reduced, but it can be said that it is quite sufficient from the viewpoint of the total amount of waste liquid discharged from the plate-making camera. Absent.

[0009]

The object of the present invention is to eliminate the drawbacks of the dip development method, to enable rapid plate making processing, to reduce the total amount of processing liquid waste, and to stabilize a large number of lithographic printing plates at all times. It is to provide a method for making a lithographic printing plate using a silver complex salt diffusion transfer method which can be reproduced with various plate making characteristics.

[0010]

The above object of the present invention is to provide a developing solution only to the surface coated with a silver halide emulsion layer (that is, to apply a developing solution), and to remove the developing solution from the plate surface. Silver complex diffusion transfer, characterized in that a step of supplying a neutralizing solution only to the surface on which the developing solution acts (that is, applying a neutralizing solution) and a step of removing the neutralizing solution of the plate surface are sequentially provided. It was achieved by a method of making a lithographic printing plate utilizing the method.

That is, in the plate-making method of the present invention, a planographic printing plate utilizing the silver complex salt diffusion transfer method is first coated with a developing solution, and then the developing solution on the plate surface is removed by a squeezing roller or the like. In the step of removing the developing solution on the plate surface, the necessary amount of the neutralizing solution applied in the subsequent step can be further reduced, and the constituent layers of the lithographic printing plate can be rapidly and uniformly neutralized. Therefore, it is possible to adjust the plate surface to be neutral or weakly acidic with a small amount of the neutralizing liquid, and at the same time, to minimize the total amount of the waste liquid of the processing liquid.

Subsequent to the step of removing the developing solution on the plate surface,
The neutralizing liquid is applied, and the neutralizing liquid on the plate surface is removed by a squeezing roller or the like. Further, in an automatic plate-making camera or the like, plate making is completed through a drying process.

As a method for supplying the developing solution and the neutralizing solution only to the surface coated with the silver halide emulsion layer, the method described in JP-A-48-76603, that is, the liquid-up coating method, Examples of the method include, but are not limited to, a dropping method roller coating method, a dropping method knife coating method, a spray coating method, and a brush coating method. For example,
It is also possible to use a so-called doctor in which a bar is wound around a rod of an appropriate material, and specifically, a developing solution and a neutralizing solution are applied to the surface of the printing plate which is kept horizontal and coated with the silver halide emulsion layer. A method of dropping and spreading the developing solution and the neutralizing solution with a doctor can also be adopted. The method of applying and supplying the developing solution and the neutralizing solution may be different.

The plate making / developing apparatus preferably used in the plate making method of the present invention is a unit having a liquid supply section on the upper side and a slit-shaped opening at the lower end, and substantially the slit-shaped opening from the liquid supply section. It is configured so that the supplied liquid is in close contact with the liquid so that the supplied liquid spreads in the width direction and flows down, which will be shown in Examples described later.

The amount of the developing solution applied to the lithographic printing plate varies depending on the type of the lithographic printing plate and the developing solution, but is 10 to 150 ml, preferably 20 to 8 per square meter of the lithographic printing plate.
The development time (the time from the application of the developing solution to the application of the neutralizing solution) is 15 seconds or less, preferably 2 to 0 ml.
The range of 10 seconds is particularly preferable for achieving the object of the present invention. The pH of the developing solution is about 11 or more, and the developing temperature is 15-
It is preferably about 35 ° C.

The coating amount of the neutralizing solution on the lithographic printing plate varies depending on the basicity of the developing solution, the acidity of the neutralizing solution and the like, but in view of the object of the present invention, the plate surface pH of the lithographic printing plate is about 8. Below, it is preferably the amount necessary to bring the pH to about 3 to about 7.5. When the plate surface pH is 8 or more, printing characteristics such as ink receptivity deteriorate. Generally, it is in the range of 10 to 200 ml, preferably 20 to 150 ml per square meter of the lithographic printing plate. It goes without saying that it is desirable to keep the amount of both the developing solution and the neutralizing solution to the minimum necessary. The pH of the neutralization solution is preferably in the range of about 3 to about 7.5. The time from the neutralization treatment to the squeezing with the squeezing roller is not particularly limited because it can be neutralized in a few seconds, but a range of about 3 to 6 seconds is preferable.

The developing solution and the neutralizing solution removed by the squeezing roller or the like may be separately collected, mixed in the developing processing apparatus or outside the developing processing apparatus, neutralized, and discarded.

The developer used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide,
Lithium hydroxide, sodium triphosphate, etc. and sulfites as preservatives (potassium sulfite, sodium sulfite, etc.)
Is essential, but other compounds such as sulfates (sodium sulfate, ammonium sulfate, etc.), silver halide solvents (thiosulfates, thiocyanates, cyclic imides,
Thiosalicylic acid, amines, etc., thickener (acacia,
Hydroxyethyl cellulose (HEC), carboxemethyl cellulose (CMC), sodium alginate, carboxymethyl starch, methyl cellulose, etc., antifoggant (potassium bromide, 1-phenyl-5-mercaptodetrazole, JP-A-47-26201). Compounds described, etc.), developing agents (hydroquinone, 1-phenyl-3
-Pyrazolidone, methol, catechol, pyrogallol, glycine, etc.), a development modifier (polyoxyalkylene compound, onium compound), etc. may be contained. Further, one or more kinds of surfactants and aminopolycarboxylic acid salts (sodium ethylenediaminetetraacetate, etc.) may be contained. In addition to these, a hydratable organic solvent (methanol, ethanol, propanol, isopropyl alcohol, n-butyl alcohol, dimethylformaldehyde, dioxane, etc.) can be contained.

The neutralizing solution used in the practice of the present invention, as described in JP-B-56-41992, has a p
Citric acid, acetic acid, boric acid, phosphoric acid, sulfurous acid and their alkali metal salts are used as the H regulator and buffer. Also, sodium hexametaphosphate as a water softener, formalin, glyoxal, glutaraldehyde, dimethylolurea, organic compounds such as ethyleneurea resin, etc. as a binder curing agent to prevent abrasion of the plate surface during printing, chromium alum, potassium alum, etc. Inorganic compounds are used as needed. In addition, a printing property improving agent such as a desensitizing accelerator, an antiseptic / antifungal agent, a wetting agent, a thickener, and a surfactant can be used. For example, gum arabic, carboxymethylcelluloses, sodium alginate, vinylpyrrolidone, vinylimidazole, a copolymer of methyl vinyl ether and maleic anhydride, oxydide cellulose alginate, methylcellulose, sulfates (sodium sulfate, ammonium sulfate, etc.), hydroxy groups of 2 One or two kinds of polyol compounds having at least one (polyethylene glycol, pentaerytriol, diethylene glycol, glycerin, hexylene glycol, etc.), inorganic fine particles (colloidal silica, alumina, etc.), polyacrylic acid, ethylenediamine tetraacetic acid sodium salt, etc. The above can be used. In addition to these, in consideration of the liquid distinguishability, colorants such as phthalocyanine dyes, malachite green, and ultramarine, and hydratable organic solvents (methanol, ethanol, propanol, isopropyl alcohol, n-butyl alcohol, dimethylformaldehyde, Dioxane, etc.).

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 or silver chlorobromoiodide, preferably silver chloride. 70
It is a silver halide of mol% or more. These silver halide emulsions include spectral sensitizers (light sources, spectral sensitizing dyes depending on the application, such as camera type, laser light type, panchromatic type for color separation), gelatin hardening agents, coating aids, antifoggants. , A plasticizer, a developing agent, a matting agent and the like.

The binder used in the silver halide emulsion of the lithographic printing plate of the present invention is usually gelatin. Gelatin is a part of starch, albumin, sodium alginate, hydroxyethyl cellulose (HEC),
Hydrophilic polymer bonds such as gum arabic, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), carboxymethyl cellulose (CMC), polyacrylamide, styrene-maleic anhydride copolymer, polyvinyl methyl ether-maleic anhydride copolymer, etc. It is also possible to substitute with one or more agents. Further, a vinyl copolymer aqueous dispersion (latex) can also 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, and a developing agent, a matting agent and the like are contained in this layer. Can be included.

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

Physical development nuclei used in the physical development nuclei layer are known to be chemicals of this kind, and include antimony, cadmium,
Metals such as cobalt, palladium, nickel, silver, lead and zinc and their sulfides can be used. This physical development nucleus layer may also contain a developing agent or may contain a hydrophilic binder.

[0025]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example A silver master (trade name) manufactured by Mitsubishi Paper Mills Co., Ltd. was used as the lithographic printing plate M utilizing the silver complex salt diffusion transfer method. The lithographic printing plate precursor was imagewise exposed with a plate-making camera having an image reversing mechanism. Then, in a room kept at approximately 25 ° C,
Plate-making processing was performed using an apparatus as shown in (side view) and FIG. 2 (perspective view). FIG. 1 is a side view showing an example of a plate making apparatus used in the present invention, and FIG. 2 is a perspective view thereof.

In the developing solution supply unit, the sheet H1a and the sheet H1b are in close contact with each other over substantially the entire surface thereof, and at a position above the sheet H1a and the sheet H1b, from the developing solution tank T1 to the sheet H1 by the metering pump P1.
It has a basic structure in which a developer supply unit 4 for supplying a developer is provided between a and the sheet H1b.

The neutralizing solution supply unit has the same structure having the sheet H2a, the sheet H2b, the metering pump P2, the neutralizing solution tank T2, and the neutralizing solution supplying section 6 corresponding to the above-mentioned developing solution supplying unit. ing.

Sheet H1a (H2a) and sheet H1b
(H2b) seals both side ends and the upper end,
This is a developer (neutralizing liquid) supply unit in which only (7) is opened, so that only a sufficient amount of developer (medium) is developed to substantially develop (neutralize) the lithographic printing plate M. Japanese solution)
Is supplied by the metering pump P1 (P2), stably spreads uniformly in the width direction, and flows out from the slit-shaped opening 5 (7). While the planographic printing plate M is being conveyed, the developing solution (neutralizing solution) sent from the metering pump flows out from the slit-shaped opening.
When the planographic printing plate M is not conveyed, the metering pump does not operate, and the developing solution (neutralizing solution) does not flow out while being confined in the developing solution (neutralizing solution) supply unit.

The developing solution (neutralizing solution) supply unit has a thickness of 2
Using a polyester film of 00 μm, the length from the developer (neutralizing liquid) supply part 4 (6) to the lower end opening 5 (7) is 120 mm, the width is 500 mm, the upper end and both ends are sealed with tape, and the lower end Only the opening 5 (7) is open.

The planographic printing plate M is conveyed by the conveying rollers (1a, 1b) at a speed of 30 mm / sec, and the planographic printing plate M is conveyed.
When the tip of the bottom reaches the lower end opening 5, the developing solution flows out from the lower end opening 5. The amount of the developing solution supplied to the unit is controlled by the metering pump P1 so that it is 30 ml per 1 m ^{2 of the} planographic printing plate. When the rear end of the planographic printing plate M reaches the lower end opening 5, the metering pump P1 is stopped. The developer remaining in the unit was hardly spilled. Developer squeezing roller (2a,
In step 2b), the excess developer is squeezed to be processed in the next neutralizing device. Neutralization liquid planographic printing plate 1 m ² per 30m
It was controlled by the metering pump P2 so as to be 1 and squeezed by the neutralizing solution squeezing rollers (3a, 3b), and processed in the same manner as in the developing operation. The squeezed developing solution and neutralizing solution are respectively received by the recovery trays (W1, W2) and discharged to the outside.

<Developer> Water 700 ml Sodium hydroxide 5 g Potassium hydroxide 14 g Anhydrous sodium sulfite 50 g 2-Methyl-aminoethanol 30 g Water is added to make 1 liter. pH = 13

<Neutralization liquid> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% liquid) 5 ml Ethylene glycol 5 ml Water is added to make 1 liter. pH = 5.1

In this way, the squeezing rollers (3a, 3b)
A part of the planographic printing plate M squeezed with was cut out, and the plate surface pH was directly measured with a pH meter C-1 (trade name) manufactured by Horiba Ltd., and it was 6.3.

Next, the planographic printing plate M was dried, set in a Heidelberg TOK offset printing machine, and printing was carried out using a dampening liquid having the following composition. Good printing of a large number of sheets was possible.

<Moisturizing liquid> Water 8 l Succinic acid 6 g Sodium sulfate 25 g Ethylene glycol 100 g Colloidal silica (20% aqueous solution) 28 g

An amount of lithographic printing plate corresponding to 5 m ² was processed by the plate-making method of the present invention, and the same result was reproduced in any lithographic printing plate. On the other hand, the developer squeezing rollers (2a, 2
A similar experiment was performed without b). The plate pH is 10.
2, the ink acceptability was remarkably poor from the beginning (first plate) of the lithographic printing plate. Further, in order to improve the ink acceptability, it was necessary to apply the neutralizing solution at a rate of 130 ml / m ² or more.

[0038]

According to the plate making method of the present invention, there are no drawbacks in the conventional dipping method, rapid processing is possible, a large amount of lithographic printing plates can be reproduced with good characteristics at all times, and the amount of processing waste liquid is significantly reduced. can do.

[Brief description of drawings]

FIG. 1 is a side view of a developing device for carrying out a plate making method of the present invention.

FIG. 2 is a perspective view showing a main part of the developing device of FIG.

[Explanation of symbols]

 1a, 1b Conveying rollers H1a, H1b Developing solution supply unit H2a, H2b Neutralizing solution supply unit 2a, 2b Developing solution squeezing roller 3a, 3b Neutralizing solution squeezing roller T1 Developing solution tank T2 Neutralizing solution tank W1, W2 Recovery tray M Lithographic printing plate

Claims (1)

[Claims] 1. A method of making a planographic printing plate using a silver complex salt diffusion transfer method, a step of supplying a developing solution only to the surface coated with a silver halide emulsion layer, and a step of removing the developing solution on the plate surface. A method of making a lithographic printing plate comprising sequentially performing a step of supplying a neutralizing solution only to the surface on which a developing solution has acted, and a step of removing the neutralizing solution on the plate surface.