JPH0627679A - Developing device for planographic printing plate - Google Patents

Abstract

PURPOSE:To provide a developing device of planographic printing plate capable of rapidly processing, excellent in maintenance, capable of developing with a small quantity of developer, small in waste solution, capable of obtaining a excellently well-balanced printing image. CONSTITUTION:The developing device for planographic printing plate is constituted by having a developer supply part 5 upward and making the bottom a slit opening 6 and providing a bar-shaped member 9 at the under side of the tip of the bottom opening part 6 in width direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive lithographic printing plate developing apparatus, and more particularly to a lithographic printing plate developing apparatus utilizing a silver 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. However, the plate-making process by this plate-making camera is not sufficient in terms of rapid processing, and maintenance is troublesome, and from the viewpoint of environmental problems, the amount of waste liquid is small or absent. Is required to develop a maintenance-free platemaking processing system. Furthermore, the development method in which the lithographic printing plate is dipped in the developing tank reduces the pH and development rate due to continuous processing, the generation of silver sludge and the generation of a drag pattern due to the movement of the developing solution, and the flow of the silver complex causes image deletion. There were many drawbacks such as

Japanese Patent Laid-Open 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, in order to achieve uniform development with only a developing solution substantially required for development, it is difficult with the conventional coating supply system, and a considerable amount of excess developing solution is required.

JP-A-62-238564 discloses that
As a so-called PS plate development processing method, a method has been proposed in which a developer is supplied onto the PS plate through a slit formed by two plate materials. However, even when the lithographic printing plate using the silver complex salt diffusion transfer method is developed using the method described in the above specification, the developer supply amount is too large and the same as the coating supply method described in the patent. Have a problem.

[0008]

The object of the present invention is to eliminate the drawbacks of plate making by the dip development method, enable rapid processing, have excellent maintenance, reduce the amount of waste developer, and form an extremely uniform printed image. To provide a developing device suitable for developing a lithographic printing plate using a silver complex salt diffusion transfer method.

[0009]

SUMMARY OF THE INVENTION The above object of the present invention is a developer supply unit having a developer supply section on the upper side and a slit-shaped opening at the lower end, and the lower end of the slit-shaped opening section. And a bar-shaped member is provided in the width direction so that the developer flowing out from the slit-shaped opening comes into contact with the developing device for a lithographic printing plate.

The developing device of the present invention will be described below in more detail with reference to the drawings, but the present invention is not limited to the embodiments of these drawings. FIG. 1 is a side view showing an example of the developing device of the present invention, and FIG. 2 is a perspective view thereof. FIG. 3 is an enlarged side view of the slit-shaped opening 6 of FIG.

The developer supply unit 1 has a slit-shaped opening 6 formed by a sheet 2a and a sheet 2b (which is expressed as a sheet for convenience, but it does not necessarily mean two sheets). A bar-shaped member 9 is provided in the width direction, and a developer supply unit 5 for supplying a developer from the developer tank 4 to the sheets 2a and 2b by the metering pump 3 is provided at an upper position. It has a structure.

In a preferred embodiment of the present invention sheet 2
The sheet a and the sheet 2b are used as the developer supply unit 1 in which both ends and the upper end are hermetically closed, and only the lower end 6 is opened, whereby the amount necessary to substantially develop the lithographic printing plate M. Only the developing solution is supplied by the metering pump 3, stably spreads uniformly in the width direction, and flows out from the slit-shaped opening 6. While the planographic printing plate M is being conveyed, the developer sent from the metering pump 3 flows out from the slit-shaped opening 6, but when the planographic printing plate M is not being conveyed, the metering pump 3 does not operate and the developer is It does not flow out while being confined in the developer supply unit 1. The shape in which only the lower end 6 of the developing solution supply unit 1 is opened may be integrally formed, or the sheet may be folded and the folds may be formed as the upper ends and the both ends may be joined with a tape, an adhesive or the like, or may be fused. May be created.

As the material of the sheet constituting the developing solution supply unit 1, for example, a plastic film such as polyester, polypropylene, polyvinyl chloride, polyethylene, polystyrene or the like, a metal such as stainless steel, a sheet of rubber or the like can be used. It is necessary to select a material that does not cause corrosion due to the pH of the developer and various components. The thickness depends on the material, but is preferably about 100 to 500 microns. Further, the lengths of the lower end openings 6 of the sheets 2a and 2b may be the same or one of the sheets may be longer.

The developing solution supply unit 1 is provided with a developing solution supply section 5 at an upper position thereof, but it is not always necessary to attach the developing solution supply section 5 to the upper ends of the sheets 2a and 2b as shown in FIG.
It may be provided on the sheet 2a or the sheet 2b to supply the developing solution. The length from the developer supply unit 5 to the slit-shaped opening 6 is preferably as short as possible because the developer stays in the unit when the planographic printing plate M is not conveyed, but when it is too short, Since it is difficult for the developer to spread uniformly in the width direction, the sheet 2
The optimum length is determined according to the distance between a and the sheet 2b, the width of the planographic printing plate M, and the like. A length of about 30 mm to 300 mm is suitable. However, this length varies depending on the viscosity of the developer, the liquid properties such as surface tension, the supply rate of the developer, and the like, and can be changed as necessary.

In the developing device of the present invention, it is preferable that the sheet 2a and the sheet 2b are in close contact with each other from the developing solution supply section 5 to the slit-shaped opening section 6. The adhesiveness between the sheet 2a and the sheet 2b is such that the supplied developing solution has an action of spreading in the width direction of the sheet due to the capillary phenomenon, and thus, it is uniform in the width direction and is effective for developing the planographic printing plate. This makes it easier to control the required amount of developer. The optimum distance between the sheet 2a and the sheet 2b varies depending on the viscosity of the developing solution, liquidity such as surface tension, the supply rate of the developing solution, and the like, as long as the supplied developing solution spreads in the width direction. Good, and generally, it is preferably 0.5 mm or less.

When the amount of the developer flowing out from the slit-shaped opening 6 of the developer supply unit 1 is small, the spread of the developer in the width direction may not be sufficient, and the planographic printing plate M may be insufficient.
The developing solution applied to the plate surface of No. 1 often causes uneven development. However, by providing a rod-shaped member 9 below the tip of the slit-shaped opening 6 in the width direction, the developing solution that has flowed out can be discharged. When brought into contact with the member 9, the developing solution spreads in the width direction along the rod-shaped member 9 and enables uniform coating and development.

The shape of the rod-shaped member 9 is not limited to a round bar, a semi-round bar or the like as long as it has the above-mentioned function, and may have any shape and size. The rod-shaped member 9 may or may not be fixedly attached to the leading end of the sheet 2a, or may have a slight gap such that the developing solution comes into contact with it.
The rod-shaped member 9 may be made of any material such as metal such as stainless steel, rubber, plastic, and glass.

The above-described developing device of the present invention may have, for example, openings on both sides of the sheet 2a and the sheet 2b. However, in order to prevent the developing solution from leaking from the opening, as described above, The supply unit 1 has a lower end 6
It is preferred that only one is open. The width of the developer supply unit 1 may be shorter than the width of the lithographic printing plate M processed in the present invention, but is usually designed to be longer (FIG. 2). However, also in this case, there is an advantage that the developing solution hardly leaks from the lower end opening 6 that exceeds the width of the planographic printing plate M.

In the developing solution supply unit 1 of the present invention, the number of the developing solution supply section 5 may be one, but a plurality of the planographic printing plates M may be provided as needed, for example.

As shown in the figure, the developer supply unit 1 preferably has a curved surface shape with a gentle bulge on the lower side. The inclination angle of the developer supply unit 1 is preferably about 30 ° to 70 ° as a straight line connecting the upper end and the lower end.

The coating supply amount of the developing solution to the planographic printing plate M is
It depends on the type of lithographic printing plate, the type of developing solution, etc., but generally 10 to 200 ml, preferably ² per 1 m 2.
It is in the range of 0 to 100 ml. The developing time varies depending on the type of the lithographic printing plate, the conveying speed, the composition of the developing solution, the developing temperature, etc., but is generally about 3 to 30 seconds. The developing temperature is preferably in the range of 10 to 40 ° C.

The developed planographic printing plate M is then preferably subjected to a neutralization treatment. The neutralization treatment may be a method of immersing in a conventional neutralization tank, but like the developing method of the present invention,
It is preferable from the viewpoint of reducing the amount of waste liquid to coat and supply the plate surface with the necessary amount of neutralizing liquid for neutralization.

The lithographic printing plate utilizing the silver complex salt diffusion transfer method, which is processed in the developing apparatus of the present invention, has an antihalation undercoat layer, a silver halide emulsion layer and a physical development nucleus layer on a support. . The silver halide emulsion layer is composed of, for example, silver chloride, silver bromide, silver chlorobromide, and those containing silver iodide. Silver halide crystals include rhodium salt, iridium salt, palladium salt, ruthenium salt, nickel salt,
It may contain a heavy metal salt such as a platinum salt. The crystal form of silver halide is not particularly limited, and may be cubic or tetradecahedral grains, or core-shell type or tabular grains. The silver halide crystal may be a monodisperse or polydisperse crystal,
The average particle size is in the range of 0.2 to 0.8 μm.

The silver halide emulsion can be chemically sensitized by methods well known in the art, such as with sodium thiosulfate, a gold compound, or a combination of both. The silver halide emulsion can be positively or negatively sensitized with a dye such as cyanine or merocyanine. The wavelength range is not particularly limited, and ortho sensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization,
Sensitization for semiconductor lasers is also possible.

The surface layer above the emulsion layer contains 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 a mixed crystal. 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 A polymer, a hydrophilic polymer such as polyvinyl alcohol, or an oligomer thereof can be contained, and the content thereof is preferably 0.5 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.

Each coating layer such as an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer may contain some surfactants as a coating aid, an antifoggant and a matting agent. , Thickeners, antistatic agents and the like.

As the support for the lithographic printing plate, paper, a synthetic or semi-synthetic polymer film, a metal plate of aluminum, iron or the like can be used as long as it can withstand lithographic printing. The surface of the support may be coated on one side or both sides with one or more polymer films or metal thin films. The surface of these supports can be surface-treated in order to improve the adhesion with the coating layer. Particularly preferably used supports are paper having both surfaces or one surface coated with a polyolefin polymer, a polyester film, a polyester film having a hydrophilic surface, a surface-treated aluminum plate, and the like.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide,
Lithium hydroxide, sodium triphosphate, etc., sulfites as preservatives, silver halide solvents, such as thiosulfates,
Thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines and the like, antifoggants 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, can be included. Further, the developing solution includes U.S. Pat.
Compounds such as those described in No. 728 which improve ink transfer of the surface silver layer can be used.

The development processing solution used in the present invention is described in JP-A-4.
As described in JP-A 8-76603, for example, a viscosity-imparting agent such as carboxymethyl cellulose or hydroxyethyl cellulose is added to have a viscosity of 0.5 to 100 c.
p, preferably in the range of 1 to 20 cp.

The surface silver layer after development of the lithographic printing plate can be converted into or receptive to ink with any known surface treating agent. Examples of such a treatment liquid include Japanese Patent Publication No. 48-29723 and US Pat. No. 3,72.
1, 559 and the like. The printing method, or the desensitizing liquid, the dampening liquid, or the like to be used may be a commonly known method.

[0031]

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

Example 1 A developing device as shown in FIG. 2 was prepared. The developing solution supply unit 1 uses a polyester film having a thickness of 200 μm, and has a length 120 from the developing solution supply section 5 to the lower end opening 6.
mm, width 500 mm, the upper end and both ends are sealed with tape, and only the lower end opening 6 is opened. The inclination angle is about 45 °. As the rod-shaped member 9, a stainless rod having a diameter of 10 mm was positioned below the tip of the sheet 2a. An apparatus for supplying the neutralizing solution was also made in the same manner as the above developing apparatus.

As the lithographic printing plate M, a silver master (trade name) manufactured by Mitsubishi Paper Mills, Ltd. was used. The developing solution and the neutralizing solution used had the following compositions. The temperature was 23 ° C. in all cases.

<Transfer Developer> 700 ml of water 20 g of potassium hydroxide 50 g of anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1.5 g 2-methylaminoethanol 15 g Water is added to make 1 liter.

<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.

The planographic printing plate M is conveyed by the conveying rollers 7a and 7b.
Is conveyed at a speed of 30 mm / sec, and when the front end of the planographic printing plate M reaches the lower end opening 6, the developing solution flows out from the lower end opening 6. The amount of the developing solution supplied to the unit is controlled by the metering pump 3 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 6, the metering pump 3 is stopped. The developer remaining in the unit was hardly spilled. A small amount of excess developer is squeezed by the squeezing rollers 8a and 8b, and the processing in the next neutralizing device is performed. The neutralizing solution is controlled by a metering pump so that the volume of the neutralizing solution is 30 ml per 1 m ² of the planographic printing plate.

The lithographic printing plate M prepared by the above operation was mounted on an offset printing machine, the following desensitizing liquid was applied all over the plate surface, and printing was performed using the following dampening liquid.

<Desensitizing Solution> Water 600 ml Isopropyl alcohol 400 ml Ethylene glycol 50 g 3-Mercapto-4-acetamido-5-n-heptyl-1,2,4-triazole 1 g

<Moistening liquid> o-phosphoric acid 10 g nickel nitrate 5 g sodium nitrite 5 g ethylene glycol 100 g colloidal silica (20% liquid) 28 g Water is added to make 2 liters.

The printing machine is an AB DIC 350CD
(Trademark of offset printing machine manufactured by AB Dick) was used. The planographic printing plate M was capable of extremely uniform development over the entire plate surface, showed no development unevenness, and exhibited sufficiently high printing durability.

[0041]

According to the developing apparatus of the present invention, rapid processing is possible, maintenance is easy, and a very small amount of developing solution is used, the amount of waste liquid is small, and development unevenness does not occur. A lithographic printing plate having high printing durability can be produced.

[Brief description of drawings]

FIG. 1 is a side view of a developing device of the present invention.

FIG. 2 is a perspective view of the developing device of the present invention.

FIG. 3 is an enlarged side view of the slit-shaped opening of FIG.

[Explanation of symbols]

 1 Developer Supply Unit 2a, 2b Sheet 3 Metering Pump 4 Developer Tank 5 Developer Supply Section 6 Slit-shaped Opening 7a, 7b Conveying Rollers 8a, 8b Squeezing Roller 9 Bar-shaped Member M Planographic Printing Plate

Claims (3)

[Claims] 1. A developer supply unit having a developer supply part on the upper side and having a slit-shaped opening at the lower end, the developer flowing out from the slit-shaped opening below the tip of the slit-shaped opening. A developing device for a lithographic printing plate, characterized in that a rod-shaped member is provided in the width direction so that they come into contact with each other. 2. The developing device according to claim 1, wherein the opening of the developing solution supply unit is only a slit-shaped opening at the lower end. 3. The developing device according to claim 2, wherein the developing solution supply unit is substantially in intimate contact from the developing solution supply section to the slit-shaped opening.