JPH05289347A - Plate making method for planographic printing plate - Google Patents

Abstract

PURPOSE:To enable rapid processing, to enhance a maintenance characteristic and to enable the formation of a uniform printing image by recovering an unused developer by width adjusting type scraping blades from the developer in the non-contact part of a planographic printing plate and a liquid lifting roller. CONSTITUTION:The liquid lifting coating roller 1a is partly immersed in the developer of a developer tank 2. This roller lifts the developer by rotation and applies and supplies the developer to a planographic printing plate P transported with its photosensitive surface downward. The developer is transferred to the planographic printing plate P from the coating roller 1a when the plate arrives at between the nips of the coating roller pair. The width adjusting type scraping blade 4 is brought into contact with the liquid lifting coating roller 1a to recover the unused developer in such a case. This width adjusting type scraping blade 4 has a function to adjust the scraping part in conformity with the width of the planographic printing plate P. The blade 5 for scraping the used developer sticking to the liquid lifting coating roller 1a is provided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for making a silver halide photosensitive lithographic printing plate. In particular, it relates to a method of making a lithographic printing plate using 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 to receive water. 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 the water, and the ink on the image area is, for example, paper. Printing is performed by transferring 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 disclosed in, for example, US Pat.
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 developer 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.

In a typical plate making method of such a lithographic printing plate,
An automatic plate-making camera with a built-in developing tank and neutralizing tank is used. However, the plate-making processing by this plate-making camera is not sufficient in terms of rapid processing and maintenance is troublesome, and there is a demand for the development of a plate-making processing system that is faster and substantially maintenance-free. Further, the developing method in which the lithographic printing plate is dipped in the developing tank has drawbacks such that a drag pattern appears due to the movement of the developing solution and an image deletion occurs due to the flow of the silver complex.

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 on a plate surface in an amount necessary for developing a lithographic printing plate. However, in order to carry out uniform development with the necessary amount of developing solution, the developing solution must diffuse and penetrate into the plate surface of the lithographic printing plate very rapidly and uniformly. However, there was a limit only in terms of composition and physical properties.

[0007]

The object of the present invention is to eliminate the drawbacks of plate making by the dip development method, to enable rapid processing, excellent maintenance, and the formation of extremely uniform printed images.
Providing a method for making a silver halide photosensitive lithographic printing plate that can suppress the excess developing solution when the developing solution is supplied to the lithographic printing plate by adjusting the width to reduce drainage and save unused developer It is to be.

[0008]

The above object of the present invention is to provide a plate making method in which a developing solution in a developing solution tank is coated on a silver halide photosensitive lithographic printing plate by a liquid-rolling roller coating method to develop. The unused developing solution is collected by the width adjustment type scraping blade of the developing solution in the non-contact area between the planographic printing plate and the liquid pick-up roller, and the excess developing solution adhering to the roller is scraped and developed by another scraping blade. It was achieved by a method for making a silver halide light-sensitive lithographic printing plate characterized by performing a developing treatment so as not to substantially return to a liquid bath.

The plate making method of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a side view showing an example of a developing device used in the plate making method of the present invention, and FIG. 2 is a top view of the main part of FIG. 1 seen from above.

In FIG. 1, 1a and 1b indicate a pair of developing solution coating rollers, and a lower roller 1a is a liquid level coating roller.
The liquid-applying roller 1a is partially immersed in the developer in the developer tank 2 and lifts the developer by rotation,
It is applied and supplied to the planographic printing plate P that has been conveyed with the photosensitive surface facing downward. When the planographic printing plate P reaches the nip between the pair of coating rollers, the developing solution is transferred from the coating roller 1a. Conventionally, when the lithographic printing plate P is conveyed by the coating roller pair, the conveyance speed of the lithographic printing plate P and the rotation speed of the coating roller are equal. Therefore, the developing solution lifted by the coating roller according to the nip pressure of the coating roller pair. Was usually set to be used virtually all.

In the plate-making method of the present invention, the lithographic printing plate P is a conveying roller 3 which is driven separately from the coating roller pair.
Since they are conveyed by a and 3b, the coating roller and the conveying roller can be rotated in different directions. Therefore, by rotating the coating roller 1a in the direction opposite to the conveying rotation direction, a pool of the developer is formed between the photosensitive surface of the lithographic printing plate P and the coating roller 1a, and this pool allows the plate surface of the lithographic printing plate P to be sufficiently covered. Since the developing solution is supplied and can be applied to the photosensitive surface of the lithographic printing plate P without unevenness, a lithographic printing plate having a good printing image can be produced in spite of rapid processing.

Of course, even if the direction of rotation of the coating roller and the direction of conveyance of the lithographic printing plate are the same, the above-mentioned pool of developer can be formed, but in this case, the viscosity of the developer is necessarily high. However, since a large amount of the polymer as a thickening agent adheres to the plate surface, it causes a problem such as a decrease in ink acceptability, which is not preferable as a printing plate. Therefore, the method of the present invention has an advantage of being effective even in a developer having a low viscosity. Further, even if the nip pressure of the coating roller pair is increased, the developer can be collected, but in this case, there is a problem that the supply amount of the developer is insufficient. On the contrary, although the coating liquid supply amount of the developing solution can be increased by lowering the nip pressure, the excess developing solution on the plate surface falls into the developing solution tank 2 after the planographic printing plate leaves the coating roller pair. Then, the fresh developer will be exhausted.

A lithographic printing plate P formed by conveying rollers 3a and 3b
The conveying speed of 5 to 50 mm per second, preferably 15 per second
~ 45 mm. The rotation speed of the coating roller 1a only needs to be reverse to the direction in which the planographic printing plate is conveyed, and the rotation speed of the coating roller 1a may be a speed difference capable of forming the pool of the developing solution. .. Depending on the viscosity of the developer and the nip pressure of the coating roller pair,
Generally, the rotation speed of the coating roller 1a is about 2 to 10 mm /
A speed difference of sec is preferred. The amount of the developer supplied to the lithographic printing plate is generally 10 to 1 per square meter.
The range is 00 ml.

In the developing device shown in FIG. 1, the scraping blade 4 of the width adjusting type is brought into contact with the liquid raising coating roller 1a to collect the unused developing liquid.

The function of the width-adjustable scraping blade 4 will be described in detail below.

The width adjusting type scraping blade 4 has a function of adjusting the scraping portion according to the width of the planographic printing plate P.

As the width adjusting method, the blade 4 is moved in the width direction according to the width of the planographic printing plate P, or the blade is fixed and a part of the blade is deformed to contact the blade and the roller. , There is a method to create a non-contact part.

In the latter case, the blade is normally brought into contact with the roller and only the portion which does not need to be contacted is lifted, or the blade is kept in contact with the roller at ordinary time and only the portion which needs to be contacted is pressed. There are two ways.

Next, a blade 5 for scraping off the used developer adhering to the liquid raising coating roller 1a is provided, and the scraped developer is discharged to the outside of the developer tank. For such discharging, the blade 5 may be extended to the outside of the developer tank, and the developer discharging liquid may flow thereover. The developer scraped off by the blade 5 may be collected and discharged to the outside of the developer tank with a pipe or the like. May be. As a result, the developer used for developing the lithographic printing plate is always fresh, and development processing with good image reproducibility and reproducibility can be performed quickly, and maintenance of the developing device is extremely easy, which results in coating. The amount of fresh developer supplied can be controlled,
There is an advantage that a new solution can be saved.

The blade 4 may be made of rubber, plastics, sponge or any other material as long as it does not damage the coating roller or has a shape of the contact portion.

It is preferable that the upper roller 1b of the coating roller pair is also provided with a blade so that the developer adhering thereto does not stain the back surface of the lithographic printing plate. However, the upper roller 1b is not essential. Although the excess amount of the developer is not so large, such a drain is collected by installing a drain receiving container 6 beside the developer tank. The material of the coating roller pair may be a known material such as metal, rubber or resin, and has a diameter of 3
It is in the range of 0 to 100 mm.

The rotation of the pair of coating rollers may be started when the leading edge of the planographic printing plate P reaches the nip of the pair of coating rollers, or may be started in advance so that the coating can be started earlier than that. You can It is desirable to stop the rotation of the coating roller pair when the trailing edge of the planographic printing plate P passes through the nip.

The developed planographic printing plate P is then preferably subjected to a neutralization treatment. The neutralization treatment may be carried out by dipping in a conventional neutralization tank, or in the same manner as in the developing system of the present invention, an amount of neutralizing liquid necessary for neutralization may be supplied to the plate surface by a coating roller.

The lithographic printing plate which is the object of the present invention contains gelatin, and its containing layer may be an undercoat layer, an emulsion layer or a physical development nucleus layer. These gelatin-containing layers can be hardened with a gelatin hardener.
Examples of the gelatin hardener include inorganic compounds such as chromium alum, aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylol compounds such as urea and ethyleneurea, mucochloric acid, 2,3. Aldehydes such as dihydroxy-1,4-dioxane, 2,4-dichloro-6-hydroxy-
Compounds having an active halogen such as S-triazine salts and 2,4-dihydroxy-6-chloro-S-triazine salts, divinyl sulfone, divinyl ketone and N, N, N
-Triacroylhexahydrotriazine, compounds having two or more ethyleneimino groups or epoxy groups which are active three-membered rings in the molecule, one of various compounds such as dialdehyde starch as a polymer hardener, or Two or more kinds can be used.

The hardener can be added to all layers or to 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.

Gelatin in the gelatin-containing layer of the present invention comprises a part of water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethyl cellulose, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene. It may be substituted with one or more hydrophilic polymers such as maleic anhydride copolymer and polyvinyl methyl ether-maleic anhydride copolymer. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

The polymeric binder of the subbing layer is generally 0.5.
It is from 10 to 10 g / m ² , preferably from 1 to 6 g / m ² . The undercoat layer may contain a pigment such as carbon black, a dye, etc. for the purpose of preventing halation, and may contain a solid powder (for example, silica particles) having an average particle diameter of 2 to 10 microns for improving printing durability. Further, photographic additives such as developing agents can be included. The undercoat layer is disclosed in JP-A-48-550.
No. 3, gazette 48-100203 gazette, gazette 49-
It may be as described in Japanese Patent No. 16507.

The silver halide emulsion layer is, for example, silver chloride,
It comprises silver bromide, silver chlorobromide, and those containing silver iodide. The silver halide crystal may contain a heavy metal salt such as a rhodium salt, an iridium salt, a palladium salt, a ruthenium salt, a nickel salt and a platinum salt, and the addition amount is 10 ^-8 to 10 ^-3 per mol of silver halide. It is a mole. 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 crystals may be monodisperse or polydisperse crystals,
The average particle size is in the range of 0.2 to 0.8 μm. One of the preferable examples is a monodisperse or polydisperse crystal containing 80 mol% or more of silver chloride, which contains a rhodium salt or an iridium salt.

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. Silver halide emulsions can also be positively or negatively sensitized or desensitized with dyes such as cyanines, merocyanines. 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. You can feel it.

The surface layer existing on top of 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 nuclei 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 of the coating layers such as the undercoat layer, the silver halide emulsion layer and the physical development nucleus layer may contain some of anionic, cationic or neutral surfactants as coating aids. , Antifoggants, matting agents, thickeners, antistatic agents and the like.

The support for the lithographic printing plate of the present invention includes:
Paper or a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron, which can withstand lithographic printing, can be used. 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 may be surface-treated in order to improve the adhesion with the coating layer.

Particularly preferably used supports are papers whose both surfaces or one surface is coated with a polyolefin polymer, polyester films, polyester films whose surfaces have been hydrophilized, and aluminum plates which have been surface-treated.
These supports may contain pigments for preventing halation and solid fine particles for improving surface properties. Further, the support may be light-transmissive so that the back surface can be exposed.

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, etc., 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 treatment liquid includes U.S. Pat.
The compounds described in JP-A No. 728, which improve the 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 No. 8-76603, for example, a viscous agent such as carboxymethyl cellulose or hydroxyethyl cellulose may be included to adjust the viscosity to 2 to 300 cp, preferably 2 to 100 cp.

The surface silver layer after development of the lithographic printing plate of the present invention can be converted into or receptive to ink receptivity with any known surface treatment agent. Such treatment liquid is described in, for example, Japanese Patent Publication No. 48-29723, U.S. Pat. No. 3,721,559 and the like. Printing method,
Alternatively, the desensitizing liquid, the dampening liquid, etc. used can be prepared by a commonly known method. The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[0037]

【Example】

Example 1 A coating roller pair 1a made of a rubber material having a roller diameter of 30 mm,
A plate-making camera having the developing device shown in FIG. 1 having 1b and a neutralization tank was prepared. Width adjustable scraping blade 4
Only the portion of the film material excluding the width of the planographic printing plate P was brought into contact with the roller. Application roller 1 using the following developer
The rotation speed of b and the transportation speed of the lithographic printing plate P are 3 respectively.
0 mm / sec, and the rotation speed of the coating roller 1a is 30
The method of the invention was set to mm / sec. The rotation of the coating roller was started before the tip of the planographic printing plate reached the nip of the coating roller. For comparison, plate making was carried out in the same manner using a plate making camera manufactured by Mitsubishi Paper Mills Co., Ltd., which is an immersion developing system. In the method of the present invention, a sufficient amount of the developer pool was formed between the nip between the coating roller 1a and the lithographic printing plate P, and the developer was uniformly applied to the entire photosensitive surface of the lithographic printing plate P. As the planographic printing plate, Silver Master (trade name) manufactured by Mitsubishi Paper Mills, Ltd. was used. The development temperature was 25 ° C.

<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.

Following the developing treatment, the printing plate is treated with a neutralizing liquid having the following composition for 20 seconds at 25 ° C., and the excess liquid is removed with a squeezing roller and dried. In both methods, the transferred silver image had no image deletion or a drag pattern and was of extremely good quality.

<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 lithographic printing plate 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 printing plate produced by the method of the present invention exhibited higher printing durability than the printing plate produced by the comparative method.

[0046]

According to the plate-making method of the present invention, rapid processing is possible, maintenance is easy, a small amount of developing solution is used, image deletion and drag pattern are not generated, and high durability is achieved. It is possible to make a lithographic printing plate with a printing force.

[Brief description of drawings]

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

FIG. 2 is a top view of a main part of the developing device in FIG.

[Explanation of symbols]

 1a, 1b Coating roller pair 2 Developer tank 3a, 3b Conveying roller 4 Width adjustment type scraping blade 5 Blade 6 Waste liquid collecting tank P Planographic printing plate

Claims (1)

[Claims] 1. A plate-making method in which a developer in a developer tank is coated on a silver halide photosensitive lithographic printing plate by a liquid-rolling roller coating system to develop, and the developer used in coating is substantially restored. Development process so that it does not exist, and at a roller position before the position where the developing solution is applied, a scraping blade whose width can be adjusted according to the width of the non-contact portion between the lithographic printing plate and the roller is brought into contact with this blade. A method for making a silver halide photosensitive lithographic printing plate, which comprises recovering the scraped unused developer by returning it to a developer tank.