JPH07319164A - Lithographic printing plate - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the change in storage sensitivity of lithographic printing plates using the silver salt diffusion transfer method. [Structure] At least one kind of pyridine is contained in a lithographic printing plate to which a silver salt diffusion transfer method is applied, which has at least one silver halide emulsion layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing material to which a silver salt diffusion transfer method is applied, and more particularly to a lithographic printing material having improved sensitivity and storage characteristics.

[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 oleophobic non-image-forming portion that does not receive ink. Generally, the non-image-forming portion receives water. It is composed of hydrophilic parts. In ordinary lithographic printing, both water and ink are supplied to the plate surface, and the image area selectively receives the colored ink and the non-image area receives water, and the ink on the image area is transferred to, for example, paper. Printing is performed by transferring it to a printing medium. Therefore, in order to obtain a good printed matter, the lipophilicity and hydrophilicity difference between the image area and the non-image area are sufficiently large, and when water and ink are supplied to the plate surface, the image area has a sufficient amount. It is necessary to accept ink and not accept ink in non-image areas.

In a lithographic printing plate using the silver salt diffusion transfer method (DTR method), the silver salt crystals, which have photosensitized nuclei upon exposure, undergo chemical development by development to become black silver and form hydrophilic non-image areas. On the other hand, unexposed silver salt crystals become silver salt complex by the silver salt complexing agent in the developing solution and diffuse to the nucleus layer, and physical development is caused by the presence of nuclei to produce ink receptive silver. The main image area is formed.

As described above, a lithographic printing plate to which the silver salt diffusion transfer method is applied has a delicate mechanism different from that of general photographic materials in that physical development and chemical development simultaneously proceed in parallel. The selection of a silver transfer solvent and an additive such as a fog inhibitor for forming the silver of the line portion has a fatal influence on the printing durability of the lithographic printing plate.

This is because the delicate balance between physical development and chemical development, the diffusion rate of the silver complex, the stability of the silver complex, the coordination energy, etc., and further to silver halide, chemically developed silver, physically developed silver, etc. This is because the coordination morphology of the additive influences the amount of deposited silver and subtle differences in morphology, and greatly changes the printing durability. An ideal lithographic printing plate having high printing durability and good photographic characteristics can be obtained only when the consistency of these factors is properly meshed. Therefore, the lithographic printing plate and the constitution of the transfer developing solution thereof, in particular, the transfer solvent and other compounds having a coordinating property with respect to silver ions and precipitated silver are
Only very limited are effective, the choices not being expected from common photographic materials, are extremely difficult. In particular, it has been a conventional problem to improve the storage stability of sensitivity without lowering the printing durability.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate to which the silver salt diffusion transfer method, which is remarkably improved in storage stability of sensitivity, is applied.

[0007]

The object of the present invention is to provide at least one layer of pyridine and pyridine in a lithographic printing plate to which a silver complex salt diffusion transfer method containing at least one silver halide emulsion layer is applied on a support. Achieved by a lithographic printing plate containing at least one of substituted derivatives (hereinafter referred to as pyridines).

Preferred examples of pyridines used by the present inventor are shown in Formula 1 (Formula A).

[0009]

[Chemical 1]

(In the formula A, R ¹ -R ⁵ represent the same or different substituents, which are respectively a hydrogen atom, a halogen atom, a cyano group, a nitro group, an alkyl group, an alkenyl group, an aralkyl group, Aryl group, alkoxy group, hydroxy group, sulfide group, amino group, carboxy group, sulfone group, alkoxycarbonyl group, aminocarbonyl group, acylamide group, sulfonamide group, ureido group,
Represents a carbamoyl group. R ^{1 to} R ⁵ may be connected to each other to form a ring. The molecular weight of formula A is 1000 or less. )

Specific preferred examples of the pyridines in the present invention are listed below, but the present invention is not limited to these compounds.

[0012]

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[0028]

[Chemical 18]

The preferred amount of the pyridine compound used in the present invention is in the range of 10 ^-7 mol-10 ^-3 mol / m ² . The layer to be added may be any layer having a water-permeable relationship with the silver salt emulsion layer, but is preferably a silver salt emulsion layer.

The lithographic printing plate used in the present invention preferably further contains dihydroxybenzenes. The dihydroxybenzenes preferably used are hydroquinone, methylhydroquinone, chlorohydroquinone, methoxyhydroquinone, ethoxyhydroquinone and ethylthio. Examples thereof include hydroquinone, 2,5-dimethylhydroquinone, phenylhydroquinone, catechol, and the like, but are not limited thereto.

The amount of dihydroxybenzenes used is preferably 10 ^-4 -10 ^-1 mol / m ² , more preferably 10 ^-3 -10 ^-2 mol / m ² .

The lithographic printing plate used in the present invention preferably contains 1-phenyl-3-pyrazolizone.
Examples of phenyl-3-pyrazolidones include 1-phenyl-3-pyrazolidone, 1-phenyl-5,5dimethyl-3-pyrazolidone, 1-phenyl-5-methyl-
3-pyrazolidone, 1-phenyl-5-hydroxymethyl-5-methyl-3-pyrazolidone, 1-phenyl-
5,5-di (hydroxymethyl) -3-pyrazolidone,
However, the present invention is not limited to these.

The preferred amount of 1-phenyl-3-pyrazolidones used is 10 ^-4 -10 ^-3 mol / m ² .

The method of incorporating pyridines, dihydroxybenzenes, and 1-phenyl-3-pyrazolidones in the constituent layers in the present invention may be at any stage during emulsion production or may be added in-line during coating. Good.

The lithographic printing plate used in the present invention contains lime-treated or acid-treated gelatin in its constituent layers. The gelatin-containing layer is an undercoat layer, an emulsion layer, and may be a catalyst core layer. These gelatin-containing layers are usually hardened with a gelatin hardener. Examples of gelatin hardeners 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. -Aldehyde-related compounds such as dihydroxy-1,4-dioxane,
A nitrogen-containing 6-membered ring compound having an active halogen such as 2,4-dichloro-6-hydroxy-s-triazine salt or 2,4-dihydroxy-6-chloro-s-triazine salt, an active vinyl group A type of various compounds having divinyl sulfone, divinyl ketone, or compounds having two or more active ethylene-imino groups or epoxy groups in the molecule, and dialdehyde starch as a polymer hardening agent. Alternatively, two or more kinds may be used in combination.

The hardener may be added to all layers, or may be added to some or only one layer. Needless to say, the diffusible hardener may be added to any one layer when two layers are simultaneously coated. Can be added to. As an addition method, it can be added in-line at the time of emulsion production or coating.

The 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 is also possible to substitute one or more hydrophilic polymers such as maleic anhydride copolymer, polyvinyl methyl ether-maleic anhydride copolymer and the like. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

The silver halide emulsion layer is, for example, silver chloride,
It comprises silver bromide, silver chlorobromide, and those containing silver iodide. The silver halide crystals may contain heavy metals such as rhodium salt, iridium salt, palladium salt, ruthenium salt, and copper salt. The crystal form is not particularly limited, and may be monodisperse or polydisperse crystal, or core-shell type crystal or tabular crystal. One preferable example is a monodisperse or polydisperse crystal containing 80% or more of silver chloride containing a rhodium salt or an iridium salt.

The silver halide can be sensitized in various ways as it is manufactured or coated. For example, with sodium thiosulfate, alkyl thiourea,
Alternatively, it can be chemically sensitized by a gold compound, for example, gold rhodanide, gold chloride, or a combination thereof, by a method well known in the art.

The silver halide can also be positively or negatively sensitized or desensitized with organic sensitizing dyes such as cyanine, hemicyanine. 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 do it.

The catalyst nucleus layer existing above or below the emulsion layer contains physical development nuclei. As the physical development nuclei, fine particles of metal such as silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold, platinum and iron, and sulfides, polysulfides, selenides of these metals, or It may be a mixture or mixed crystal thereof.

The catalyst nucleus layer may or may not contain a hydrophilic binder, but gelatin, starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, vinyl imidazole and acrylamide co-weighing. It may contain a polymer, a hydrophilic polymer such as polyvinyl alcohol, or an oligomer thereof. Further, the catalyst core layer may contain a known hardener such as formalin and succinaldehyde.

Each coating layer such as a silver halide emulsion layer and a catalyst nucleus layer may contain some of an anion, a cation or a neutral surfactant as a coating aid, or a thickener. Antistatic agents can also be included.

As the support for the lithographic printing plate, paper, a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron, and 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 the support may be surface-treated in order to improve the adhesion with the coating layer. Particularly preferably used supports are paper, polyester film, polyester film whose surface is hydrophilized, surface-treated aluminum plate, etc., which is coated on both sides or one side with a polyolefin polymer. These supports may contain pigments for preventing halation and solid fine particles for improving surface properties. The support may also be light transmissive so that backside exposure is possible.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium triphosphate, a sulfite as a preservative, and a silver halide solvent. For example, as thiosulfates, thiocyanates, cyclic imides, thickeners,
For example, hydroxyethyl cellulose, carboxymethyl cellulose, and the like, antifoggants such as potassium bromide, 1-phenyl-5-mercaptotetrazole, the compounds described in JP-A-47-26201, and the like, for example, hydroquinones. , Catechol, 1-
Development modifiers such as phenyl-3-pyrazolidone may include, for example, polyoxyalkylene compounds, onium compounds and the like. Further, as the development processing solution, a second solution containing a compound or the like which neutralizes the alkalinity and further improves the ink transfer of the surface silver layer can be used.

The surface silver layer after development of the lithographic printing plate produced according to the present invention can be converted into or receptive to ink with any known surface treating agent. Such treatment liquid is described in, for example, Japanese Patent Publication No. 48-29723, US Pat. No. 3,721,559 and the like.

A printing method, or a desensitizing solution used,
The dampening liquid or the like can be prepared by a commonly known method.

[0048]

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

Example 1 A 135 g / m ² double-sided polyethylene-coated paper was provided with a matting layer containing silica particles having an average particle size of 5 μ on one side, and the opposite side was carbon black after corona discharge machining.
And an undercoat layer (containing 2.5 g / m ² of gelatin) containing silica powder having an average particle size of 7 μ, and an ortho-sensitized high-sensitivity silver chloride emulsion (0.8 g / m ^{2 of} gelatin, 1-
Phenyl-5,5-dimethyl-3-pyrazolidone 9x
(Including 10 ⁻⁵ mol / m ² ) as silver nitrate 1. 0 g / m
^{In 2} , two layers were simultaneously coated with an extrusion coater. As a hardener, 2,4-dichloro-6-hydroxy-s-triazine sodium was added in-line to the undercoat layer and the emulsion layer so as to give 40 mg / g gelatin. After drying and heating at 40 ° C for 5 days
Nuclear coating solution described in Example 2 of No. 21602 (containing a copolymer of acrylamide and imidazole of No. 3 as a polymer, 1-phenyl-5,5-dimethyl-
2-pyrazolidone (2 × 10 ⁻⁴ mol / m ² , hydroquinone as a developing agent in a proportion of 7 × 10 ⁻³ mol / m ² ) was applied by a dip coater and dried to prepare a lithographic printing plate.

The lithographic printing plate thus obtained was image-exposed with a plate-making camera having an image reversing mechanism. Development was carried out for 1 minute at 30 ° C. with the following silver salt diffusion transfer developer. <Transfer developer> Water 700 ml Potassium hydroxide 20 g Anhydrous sodium sulfite 50 g Thiosalicylic acid 1.5 g N, N-diethylaminoethylethanolamine 10 g Water is added to make 1 liter.

After the developing treatment, the original plate was passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds, and the squeezing roller was used to remove the excess liquid. Removed and dried at room temperature. <Neutralization liquid> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% liquid) 5 ml Ethylene glycol 5 ml Add water to make 1 liter.

The planographic 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 liquid> Water 600 ml Isopropyl alcohol 400 ml Ethylene glycol 50 g 3-Mercapto-4-acetamido-5-n-heptyl-1,2,4-triazole 1 g <Moisturizing liquid> 0-phosphoric acid 10 g Nickel nitrate 5 g Sodium sulfite 5 g Ethylene glycol 100 g Colloidal silica (20% liquid) 28 g Water is added to make 2 liters.

As the printing machine, Ryobi 2800CD (trademark of offset printing machine manufactured by Ryobi Co., Ltd.) was used, and the printing durability could not be used for printing due to image skipping due to lack of silver image in non-image area. It was judged from the number of printed sheets at that time.

The sensitivity change was measured by setting the initial relative sensitivity of the sample to 100 and showing the change in sensitivity after storage for 1 month at a temperature of 35 ° C. and a humidity of 80%. Table 1 shows the effect of adding pyridines to the emulsion layer in comparison with the case of not adding. The same effect can be obtained by adding it to layers other than the emulsion layer, but a large amount of addition is required.

[0055]

[Table 1]

[0056]

EFFECT OF THE INVENTION By using the compound of the present invention, it is possible to effectively prevent the change in sensitivity with time without lowering the printing durability of the lithographic printing plate to which the silver salt diffusion transfer method is applied.

Claims (1)

[Claims] 1. A lithographic printing plate to which a silver complex salt diffusion transfer method comprising at least one silver halide emulsion layer is applied on a support, wherein at least one layer contains at least one of pyridine and a pyridine-substituted derivative. Edition.