JPH0342465B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lithographic printing materials. More specifically, the present invention relates to a method for producing direct lithographic printing with excellent image gradation in a printing plate in which a silver image obtained by a silver salt diffusion transfer method is receptive to lipophilic ink.

Conventionally, many methods have been known for producing lithographic printing plates using the silver salt diffusion transfer method, and representative ones include U.S. Pat.
Methods described in various specifications of No. 3161508, Japanese Patent Publication No. 16725/1983, etc. are known. In addition, special public service
There are also methods described in publications such as No. 42453 and No. 48-30562. In the former method, the photosensitive element and the development nucleus layer, which is a printed image element, are each made up of separate units, whereas in the latter method, they are integrated.

Direct lithographic printing plates using the silver salt diffusion transfer method have the advantage of being simpler and faster in processing than PS plates, etc., as they do not require a return film. In order to be applied as a lithographic printing plate, it must: [1] It must have high sensitivity, high contrast, and stable photographic properties that allow for good reproduction of halftone line images.

[2] High ink receptivity, that is, lipophilicity, in the printed area;
In addition, the ink repellency, ie, hydrophilicity, of the non-image area is high.

etc. are particularly important.

In a lithographic printing plate applied to a silver salt diffusion transfer method in which a silver halide emulsion and physical development nuclei are the main elements, a silver salt diffusion transfer material containing a developer as a constituent element is already known.

The advantage of this method is that the oxidation of the developing agent in alkaline baths, which occurs in the case of developers, is avoided.

However, since the developing agent is contained in the photosensitive material, it is undeniable that the layer undergoes air oxidation to some extent, and as a result, undesirable phenomena such as a decrease in sensitivity and a decrease in contrast occur during storage of the photosensitive material. As a result, the halftone image reproducibility becomes unfavorable.

It is generally known that rhodium salts are used during the formation of silver halide grains in order to obtain high-contrast silver halide emulsions, and it is considered an extremely useful method because it allows the gradation of photographic emulsions to be easily controlled. ing.

However, while achieving high contrast, it not only causes a significant decrease in sensitivity, but also has many drawbacks, such as the loss of high contrast and sensitization over time during raw storage of the photosensitive material. was the reality.

Therefore, there has been a strong desire for a direct lithographic printing plate that stably has a high-contrast halftone gradation and has good halftone quality.

The first object of the present invention is to provide a lithographic printing material for use in silver salt diffusion transfer, which contains a developing agent in an amount that can be developed in an alkaline activation bath, and to improve sensitivity and stability during storage. An object of the present invention is to provide a lithographic printing material that prevents a decrease in contrast.

A second object of the present invention is to provide a lithographic printing plate with good image reproduction, sufficient ink receptivity, and no background staining.

As a result of intensive study, the present inventors have determined that the above purpose can be achieved from 70 mol% of silver chloride containing rhodium salt
It was discovered that this can be achieved by adding a surfactant having at least one sulfonic acid group in the molecule to a photosensitive silver halide emulsion containing 100 mol%, and this led to the present invention. It is ivy.

The above object could not be achieved by adding a general surfactant to the silver chloride emulsion, and the effect of adding a surfactant having a sulfonic acid group is noteworthy.

Other objects and advantages of the invention will become more apparent from the description below.

The rhodium salt used in the present invention may be any water-soluble rhodium salt well known in the art, typically rhodium chloride, rhodium trichloride,
Rhodium ammonium chloride and the like are used.

In order to add these rhodium salts to the silver halide emulsion, it is preferable to add them during the grain formation period of the first ripening (during physical ripening), and the amount of the rhodium salts to be added is as follows:
It varies depending on the purpose, but from about 10 ^-9 mol
It can be freely changed between 10 ^-6 mole/1 mole of silver halide.

Next, at least one
Surfactants containing two sulfonic acid groups are generally well known as anionic surfactants.
It can be expressed as the following general formula [].

R-SO ₃ M or R-OSO ₃ M General formula [] In the formula, R is a lipophilic group having 6 to 40 carbon atoms, and M is a hydrogen atom, an alkali metal, an anthenium group or a substituted ammonium group.

Specific examples of the anionic surfactant used in the present invention are shown below, but the present invention is not limited thereto.

■■■ Tortoise shell [0337] ■■■ ■■■ Tortoise shell [0338] ■■■ ■■■ Tortoise shell [0339] ■■■ ■■■ Tortoise shell [0340] ■■■ ■■■ Tortoise shell [0341] ■■■ ■■■ Tortoise shell [0342] ■■■ ■■■ Tortoise shell [0343] ■■■ ■■■ Tortoise shell [0344] ■■■ ■■■ Tortoise shell [0345] ■■■ ■■■ Tortoise shell [0346] ■■■ For information on these compounds and their production methods, see "Synthesis and Application of Surfactants" by Ryohei Oda and Kazuhiro Teramura (Maki Shoten) or "Surf S Active Agents" by AW Schwartz and JW Berry.
(Interscience Publication 1NC New York), etc., and is easily available.

The above-mentioned anionic surfactant according to the present invention may be added to the above-mentioned silver halide emulsion layer or to a layer adjacent thereto, but is preferably added to the emulsion layer. The timing of addition is not particularly limited, and may be added at any time in the manufacturing process of the silver salt diffusion transfer printing plate of the present invention. However, when it is added directly to the silver halide emulsion, it is preferably added between the time when the second ripening of the emulsion is completed and the time when it is coated on the support.

The amount added is not uniform, but in the case of silver halide emulsions, it is preferably in the range of 0.1 g to 10 g, particularly 0.3 g to 5 g, per coating solution.

The silver halide emulsion used in the present invention is a high-contrast silver halide emulsion and is often a fine-grain emulsion, containing 70 mol% or more (preferably 80 mol% or more) of silver chloride as a silver halide composition, and the remaining silver halide having an odor. A silver bromide or silver iodobromide emulsion containing 0 to 2 mol % of silver or silver bromide and silver iodide must be used.

In order to improve physical developability, it is desirable that the silver halide has fine grains. If the average grain size of silver halide is 0.5μ or more, resolution will decrease and halftone reproducibility will deteriorate, and if it is less than 0.1μ, the emulsion will fail. Because it is stable and does not have sufficient sensitivity as a printing plate, the particle size
0.5μ to 0.1μ is preferable.

Such silver halide emulsions are described in TH James and CEK Mees, “The Theory of the
Photographic Process” 3rd edition, published by MaCMilan; P. Grafikides, “Chemie
It is described in books such as "Photographique" published by Panl Montel, and can be prepared by various methods such as the generally accepted ammonia method, neutral method, acid method, etc.Also, single jet method, double jet method, A controlled jet method or the like may be used, or two or more types of silver halide emulsions formed separately may be mixed.After forming such silver halide grains, water-soluble salts produced as by-products may be mixed. (e.g., potassium nitrate when silver bromide is made using silver nitrate and potassium bromide) is washed with water to remove it from the system, followed by heat treatment with chemical sensitizers such as sodium thiosulfate, N, N, N'- It is carried out in the presence of trimethylthiourea, monosulfuric gold thiocyanate complex, thiosulfate complex, stannous chloride, hexamethylenetetramine, etc., to increase sensitivity without coarsening the particles.These general methods are described in the above-mentioned book. Chemical sensitizers include, for example, gold compounds such as chlorauric acid salts and gold trichloride as shown in U.S. Patent No. 2,399,083, U.S. Pat. Patent No. 2448060, same no.
Nos. 2540086, 2566245, 2566263, and 2598079; salts of noble metals such as platinum, palladium, iridium, rhodium, and ruthenium; US Pat. Sulfur compounds that react with silver salts to form silver sulfide as described in U.S. Pat.
No. 2487850, No. 2518698, No. 2521925, No. 2521926, No. 2694637, No. 2983610,
Examples include stannous salts, amines, and other reducing substances as described in the specification of the same No. 3201254.

The support for the lithographic printing material according to the present invention includes:
Examples include nitrate film, cellulose acetate film, cellulose acetate butyrate film, polystyrene film, polyethylene phthalate film, polycarbonate film, laminates thereof, and paper. Additionally, papers coated or laminated with Paraita or α-olefin polymers, especially polymers of α-olefins having 2 to 10 carbon atoms, such as polyethylene, polypropylene, and ethylene butylene copolymers,
47-19068, in which the adhesion with other polymeric substances is strengthened by roughening the surface, or the surface roughening method described in Japanese Patent Publication No. 135840, 1983, etc. A support can be used.

In order to strengthen the adhesion between the support and the coating layer, the surface of the support may be subjected to a preliminary treatment such as corona discharge, ultraviolet irradiation, flame treatment, or the like. Regarding corona discharge, the method described in US Patent No. 2018189 is representative.

Also, a known method of increasing adhesion by previously applying an undercoat layer on the support can also be applied.

For the purpose of increasing sensitivity, increasing contrast, or accelerating development, the photographic emulsion of the present invention may contain, for example, polyalkylene oxide as described in U.S. Pat. No. 2,441,389,
Ethers, esters, and amides of polyalkylene oxides as described in U.S. Pat. No. 2,708,161, British Patent No. 1,145,186, Japanese Patent Publication No. 1983
No. 10989, No. 45-15188, No. 46-43435, No. 47
-8106, 47-8742, and other polyalkylene oxide derivatives; US Patent No.
3046132 to 3046135, thioether compounds described in Japanese Patent Publications No. 45-9019 and 47-11119, thiomorpholins described in Japanese Patent Publication No. 47-28325; US Patent No. 3772021 Quaternary ammonium compound described; Japanese Patent Publication No. 1983-27037
Urethane or urea derivatives described in Japanese Patent Publication No. 40-23465; imidazole derivatives described in Japanese Patent Publication No. 47-45541; polymers described in Japanese Patent Publication No. 45-26471;
It may also contain 3-pyrazolidones described in Japanese Patent Publication No. 45-27670.

Furthermore, various compounds can be added to the photographic emulsion of the photographic light-sensitive material used in the present invention in order to prevent a decrease in sensitivity and the occurrence of fog during the manufacturing process, storage, or processing of the light-sensitive material. These stabilizer compounds include 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene, 1-phenyl-5-mercaptotetrazole,
A large number of compounds have been known for a long time, including many heterocyclic compounds, mercury-containing compounds, mercapto compounds, and metal salts. Examples of compounds that can be used include TH James and CEK Mees, “The
Theory of the Photographie Process, 3rd edition (1966), published by MacMillan, with original references cited, as well as U.S. Patent No. 1758576;
No. 2110178, No. 2131038, No. 2173628, No. 2697040, No. 2304962, No. 2324123,
No. 2394198, No. 2444605 to No. 2444608,
Same No. 2566245, Same No. 2694716, Same No. 2697099,
Same No. 2708162, Same No. 2728663-5, Same No.
No. 2476536, No. 2824001, No. 2843491, No. 2886437, No. 3052544, No. 3137577,
Same No. 3220839, Same No. 3226231, Same No. 3236652,
Same No. 3251691, Same No. 3252799, Same No. 3287135,
3326681, 3420668, 3622339 specifications, British Patent Nos. 893428, 403789,
Specifications of the same No. 1173609 and the same No. 1200188 are mentioned.

Hardening of the photographic emulsion and/or other constituent layers can be carried out according to conventional methods. Examples of curing agents include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and cyclopentanedione, and bis(2
-chloroethylurea), 2-hydroxy-4,6
-dichloro-1,3,5-triazine, and other compounds having reactive halogens as shown in U.S. Patent No. 3288775, U.S. Patent No. 2732303, British Patent No. 974723, U.K. Patent No. 1167207, etc.; Divinyl sulfone, 5-acetyl-1,3-diacryloylhexahydro-1,3,5-triazine, and others U.S. Pat. No. 3635718, U.S. Pat. No. 3232763
No. 3490911, No. 3642486, British Patent No.
No. 994869 Compounds with reactive olefins as shown in various specifications, N-hydroxymethylphthalimide, etc. US Patent No. 2732316
No. 2,586,168, N-methylol compounds as shown in the specifications, and U.S. Patent No.
Isocyanates as shown in US Pat. No. 3103437, etc.; aziridine compounds as shown in US Pat. No. 3,017,280, US Pat. No. 2,983,611, etc.; US Pat. Acid derivatives as shown in each specification, carbodiimide compounds as shown in US Pat. No. 3,100,704, etc., epoxy as shown in US Pat. No. 3,091,537, etc. compounds, isoxazole compounds as shown in U.S. Pat. Inorganic hardeners include chromium alum and zirconium sulfate. Moreover, instead of the above-mentioned compounds, compounds in the form of precursors such as alkali metal bisulfite aldehyde adducts, methylol derivatives of hydantoin, primary aliphatic nitroalcohols, etc. may be used.

Examples of the physical development nuclei of the physical development nucleus layer used in the present invention include palladium, gold, silver,
A noble metal such as platinum, preferably a colloid thereof, a metal sulfide such as silver, palladium, zinc, or a metal selenide can be used, and the particles have an average particle size of about 20 to 100 mm. Among these, metal particles obtained by reducing silver compounds (for example, silver nitrate), gold compounds (for example, gold chloride), noble metal colloids, silver sulfide, palladium sulfide, etc. are particularly preferred.

Next, as the binder for the development nucleus layer of the present invention,
It functions as a binder for physical development nuclei such as the colloidal fine particles described above, and is preferably selected from those that are soluble in water or a water-based solvent and have a film-forming ability.

Specifically, it is a hydrophilic polymer compound, such as gelatin, gelatin derivatives such as phthalated gelatin, polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, hydroxyethylcellulose, hydroxymethylcellulose, ethylcellulose, methylcellulose, carboxyethylcellulose, carboxylic acid, etc. Celluloses such as methylcellulose and hydroxypropylcellulose, polyvinylpyrrolidone, sodium alginate, gum arabic, polyacrylamide,
Maleic anhydride-vinyl acetate copolymer, maleic anhydride-ethylene copolymer, maleic anhydride-methyl vinyl ether copolymer, maleic anhydride-
Styrene copolymers, half esters thereof, methacrylic acid copolymers, etc. are included, and these can be used alone or in combination of two or more.

The photosensitive material of the present invention contains a filter dye or an anti-irradiation dye as disclosed in the US Pat.
It may contain the compounds described in the specifications of No. 2274782, No. 2527583, No. 2956879, No. 3177078, No. 3252921, and Japanese Patent Publication No. 39-22069. These dyes may be mordanted, if necessary, by the method described in US Pat. No. 3,282,699. Furthermore, colored layers such as pigments (for example, lamp black, carbon black, fast black, ultramarine, maskite green, crystal violet) can also be used as the above-mentioned antihalation layer.

The constituent layers of the lithographic printing material according to the present invention can be coated on the above-mentioned support using coating methods well known in the art. Examples include a dip method, an air knife method, an extrusion doctor method, and the bead coating method described in US Pat. No. 2,761,791 is particularly preferred.

A silver halide developing agent is incorporated in the constituent layers of the lithographic printing material according to the present invention. In this case, development after exposure can be carried out by activation treatment using an alkaline aqueous solution.

The developing agent is used in the silver halide photosensitive layer or its adjacent layer (undercoat layer, intermediate layer or antihalation layer,
It can be contained in a release layer). Note that the developer may naturally contain a developer.

Specific compounds for the developer include polyhydroxybenzenes such as hydroquinone, catechol, chlorohydroquinone, pyrogallol, bromohydroquinone, isopropylhydroquinone,
toluhydroquinone, methylhydroquinone, 2,3
-dichlorohydroquinone, 2,5-dimethylhydroquinone, 2,3-dibromohydroquinone, 1,
4-dihydroxy-2-acetophenone, 2,5
-dimethylhydroquinone, 4-phenylcatechol, 4-t-butylcatechol, 4-n-butylpyrogallol, 4,5-dibromocatechol,
Included are 2,5-diethylhydroquinone, 2,5-benzoylaminohydroquinone, 4-benzyloxycatechol, 4-n-butoxycatechol, and the like.

Among these, hydroquinone and methylhydroquinone are particularly preferably used.

Other developing agents include 3-pyrazolidone compounds such as 1-phenyl-3-pyrazolidone, 1-p-tolyl-3-pyrazolidone, and 1-pyrazolidone.
-phenyl-4-methyl-3-pyrazolidone, 1
-Phenyl-4,4-dimethyl-3-pyrazolidone, 1-p-chlorophenyl-3-pyrazolidone, 1-p-methoxyphenyl-3-pyrazolidone, 1-phenyl-2-acetyl-3-pyrazolidone, 1-phenyl -5,5-dimethyl-3-pyrazolidone, 1-o-chlorophenyl-4-methyl-4-ethyl-3-pyrazolidone, 1-m-acetamidophenyl-4,4-diethyl-3-pyrazolidone, 1, 5-diphenyl-3-pyrazolidone, 1-(m-tolyl)-5-phenyl-3-pyrazolidone, 4,4-dihydroxymethyl-1-phenyl-3-pyrazolidone, 4,4-dihydroxymethyl-1-tolyl- 3-pyrazolidone, 4-
Hydroxymethyl-4-methyl-1-phenyl-
3-pyrazolidone, 4-hydroxymethyl-4-
Included are methyl-1-(p-chlorophenyl)-3-pyrazolidone and the like.

In addition, as aminophenols, for example, p-
(Methylamino)phenol, p-aminophenol, 2,4-diaminophenol, p-(benzylamino)phenol, 2-methyl-4-aminophenol, 2-hydroxymethyl-4-aminophenol, etc. .

The above developing agents can be used alone or in combination. In particular, a combination of a polyhydroxybenzene compound and a 3-pyrazolidone compound is preferred. The amount of the developing agent used in the constituent layers is not uniform, but may be in the range of 0.001 g to 1 g per 1 m ² , and in the case of a silver halide photosensitive layer, it is 0.01 g to 3 g per m 2 .
g/g of silver halide.

In the constituent layers of the present invention, if necessary, a compound called a complexing agent that tends to form a soluble silver complex salt with silver halide in the unexposed area can be included to advantageously promote physical development.

Examples of complexing agents include thiosulfates, thiocyanates, amine sulfates as described in US Pat. No. 3,169,962, or cyclic imides as described in US Pat. No. 2,857,276;
A mercapto compound described in Japanese Patent No. 46-11957 and the like can be contained.

The above-mentioned developing agents may be added to the coating solution after being dissolved in water or a hydrophilic solvent such as methanol, or may be added after being dissolved in a high-boiling point organic solvent or a low-boiling point organic solvent. The high boiling point organic solvent generally has a boiling point of about 180 DEG C. or higher, and includes, for example, alkyl esters of phthalic acid such as ethyl phthalate and n-butyl phthalate, or phosphoric acid esters such as tricresyl phosphate.
In addition, as a low boiling point organic solvent, it is generally about 30℃~150℃.
It has a boiling point at ℃, such as lower alkyl acetates such as ethyl acetate and butyl acetate.

Further, these high and low boiling point solvents may be used in combination, and the dissolved developing agent may be dispersed in the hydrophilic colloid by any known method.

When added to the constituent layers of the lithographic printing material according to the present invention, gelatin or a synthetic polymer compound such as polyvinyl alcohol, polyvinyl pyrrolidone, U.S. Pat. Examples include alkyl acrylates, sulfoalkyl acrylates, and acrylic acid copolymers described in No. 3488708.

When developing the lithographic printing material of the present invention, a processing solution containing various substances can be used.

Main examples include alkaline agents (e.g. alkali metal or ammonium hydroxides, carbonates, phosphates), PH adjusting or buffering agents (e.g. weak acids or groups with acetate or sulfate groups, and their salts). ), development accelerators (e.g. U.S. Pat. No. 2,648,604
Various pyridinium compounds and cationic compounds described in No. 3671247, etc.
Potassium sulfate and sodium nitrate, U.S. patent no.
Polyethylene glycol condensates and their derivatives as described in the specifications of British Patent No. 2533990, British Patent No. 2577127, British Patent No. 2950970, etc., as well as compounds described in British Patent No. 1020033 and British Patent No. 1020032. nonionic compounds such as polythioethers, polymer compounds with sulfite esters such as those described in U.S. Pat. No. 3,068,097, organic amines such as pyridine, ethanolamine, cyclic amines, benzyl alcohol, hydrazines, etc.), antifoggants (for example, alkali chloride, alkali bromide, alkali iodide, nitrobenzimidazoles described in U.S. Pat. Nos. 2,496,940 and 2,656,271, mercaptobenzimidazole, 5 Methylbenzotriazole, 1-phenyl-5-mercaptotetrazole, U.S. Pat. No. 3,113,864;
3342596, 3295976, 3615522, 3597199, etc., thiosulfonyl compounds described in British Patent No. 972211, or Japanese Patent Publication No. 1983-41675 Phenazine-N-oxides as described in the Publication No. 2, fog suppressants as described in Scientific Photographic Handbook Vol. 29 to 47), as well as U.S. Pat. Stain or sludge inhibitors as described in British Patents Nos. 1030442, 1144481 and 1251558; (Fighting accessories, etc.) In addition, metal sequestering agents such as sodium hexametaphosphate and ethylenediaminotetraacetic acid, saponins,
Wetting agents such as ethylene glycol can be used.

In addition, the developer contains silver halide solvents such as sodium thiosulfate, sodium thiocyanate, potassium thiocyanate, alkanolamines, cyclic amines, alkyl-substituted amino alcohols, thiourea, thiosalcylic acid, and thiosalcylic acid that forms in alkaline solutions. For example, 5-methylcarbamoylthiosalicylic acid may be contained.

If it is necessary to stop the development of the lithographic printing material according to the present invention after development, a neutralizing solution can be dissolved. This neutralizing solution can be a normal acid stop bath, and the pH
is adjusted to approximately 3.0 to 8.0. This neutralizing solution may contain a water softener, a PH regulator, a buffer, a hardening agent, etc., and may also contain colloidal silica or polyols for the purpose of eliminating ink stains on the printing plate being processed. etc. may be added.

After the material according to the present invention is processed as described above to obtain a plate, various post-treatments can be performed for the purpose of improving and improving printability. For example, for the purpose of improving ink receptivity, US Pat.
No. 10910, No. 48-29723, No. 51-15762, No. 52
-15762 It is processed by the method described in each publication.

Also, for the purpose of eliminating ink stains on printed matter,
For example, US Patent No. 3547632, Japanese Patent Publication No. 39-
No. 5114, No. 40-763, No. 47-16946, No. 47-
The methods described in Publications No. 25242, No. 54-26921, and No. 54-33164 can be applied.

Furthermore, for the purpose of correcting printing plate images, for example,
The method described in Publication No.-21901 etc. can be applied.

The development nucleus layer used in the present invention can be applied to any printing plate to which the silver salt diffusion transfer method is applied.

For example, US patent No.
No. 3547641, Specification No. 3721559, Special Publication No. 1977-
30562, or by the two-sheet method, for example, U.S. Patent No. 3250616,
Specification No. 3736872, Japanese Patent Publication No. 48-16725, etc.
Furthermore, the etching bleaching method is used, for example, in US Pat. No. 2,360,105, US Pat.
There are methods described in Publications No. 44-27242 and No. 56-1629.

Also, U.S. Patent No. 3511656, which is a wash-off method.
The methods described in JP-A-54-148602 and the like are advantageously applied.

Next, preferred embodiments to which the present invention can be applied will be specifically explained.

As a support, a laminated paper whose surface was treated by extrusion coating of polyethylene and whose surface was then patterned with an embossing calender was subjected to a corona discharge treatment to make it hydrophilic.

On the thus obtained offset printing base paper, a hydrophilic colloid solution containing a hydrophilic polymer compound such as gelatin or maleic anhydride and methyl vinyl ether copolymer is applied as an undercoat layer, and then ( For example, there is an embodiment of a printing material in which an image-receiving layer is formed by coating multiple layers of a hydrophilic coronoid solution (dispersed by reducing palladium chloride).

Another method is to coat a photosensitive silver halide emulsion in multiple layers on the printing material obtained as described above to obtain a printing material. This is an embodiment in which the emulsion is dissolved and peeled off with water to expose the development nucleus layer to the surface and used as a printing material.

Still another method is to first provide a gelatin coating layer in which carbon black is dispersed as an antihalation layer on the surface-treated base paper for offset printing as described above, and then apply photosensitive silver halide coating thereon. A printing material is obtained by coating a multilayer emulsion and then coating a development nucleus layer (for example, a hydrophilic colloid solution in which palladium chloride is reduced and dispersed) in a multilayer coating.

The present invention also provides a negative offset printing material using a substantially non-photosensitive chloride emulsion layer in which a refractory agent (for example, 1-phenyl-5-mercaptotetrazole) is adsorbed in the photosensitive silver halide emulsion layer. It is also applicable to the method described in Japanese Patent Application No. 55-99089, in which a silver halide emulsion layer mixed with silver grains is provided to form a negative printing plate.

In these specific examples described above, in order to improve printability, water retention, printing durability, etc., in the constituent layer, for example, inorganic fine particles such as:
Silica (silicon dioxide), magnesium oxide, titanium dioxide, calcium carbonate, colloidal alumina, talc, seekrite, zinc oxide, barium sulfate, clay, glass powder, etc., or polymethyl methacrylate, cellulose acetate, propionate, polystyrene, etc. Organic fine powder can be added and dispersed. Note that the average particle size of these fine powders may be in a wide range of about 0.1 μm to 20 μm, preferably in the range of about 0.5 μm to 15 μm.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 The following undercoat liquid was applied on a 160 g/m ² polyethylene-coated paper (corona discharge treated) by the fat method and dried to prepare an undercoat sample.

[Undercoating liquid] Gelatin 50g Silica powder (average particle size, approximately 7μ) 15g Formalin 4% 15ml Saponin 1% 10ml Water 1 Next, as a development nucleus layer, a colloidal gold solution with the following formulation was prepared, and the underlayer coating sample Multilayer coating was applied on top using the dip method.

[Preparation of gold colloid solution]

(a) Reaction product of polyvinyl alcohol and methyl vinyl ether/maleic anhydride copolymer
0.1g Gelatin 0.03g Finished with water 750ml (b) HAuCl ₄・4H ₂ O 0.8g Finished with water 50ml (c) NaBH ₄ 0.8g Finished with water 200ml Dissolved at room temperature (a), (b) After mixing, (c) was added and reduced under strong stirring to obtain physical development nuclei of gold.

[Preparation of silver halide emulsion]

A silver chlorobromide emulsion containing 10 mol % of silver bromide was prepared by the double jet method. This average particle size is 0.3μ
It was hot. However, for comparison, we prepared one in which rhodium chloride in an amount equivalent to 1 x 10 ^-7 mol per mol of silver was added at the time of mixing, and one in which no additive was added, and then the emulsion was washed with water and desalted, and then the usual method was used. Chemical ripening was performed by metal and sulfur sensitization.

Appropriate amounts of hydroquinone and phenidone were dispersed into this emulsion as developing agents, and then 2-methyl-4-hydroxy-1,3,3a, a known stabilizer, was added.
7-tetrazaindene was added to disperse the emulsion, and an anionic surfactant according to the present invention and a comparative activator (described below) as shown in Table 1 were added to each of the emulsions to prepare a coating solution.

Apply this coating solution onto the gold colloid layer and add 1 silver to the gold colloid layer.
A lithographic printing plate was obtained by uniformly applying the coating using the dip method to obtain a coating weight of g/m ² .

The obtained sample was subjected to a storage test under high temperature and high humidity, then subjected to image exposure using a conventional method, and then subjected to physical development at 30°C for 30 seconds in the following alkaline activation bath, followed by final exposure in water. The upper emulsion layer was dissolved and peeled off to obtain a positive plate-made image.

Activation bath formula Caustic soda 30g Sodium sulfite (anhydrous) 50g Sodium thiosulfate/5H O 2.0g Potassium bromide 1.0g 2-Methyl-5-mercaptooxadiazole
Add 0.1g water to make 1.

The obtained printing plate was coated with a commercially available oil sensitizing solution (SLM-OH
After wiping the surface with Mitsubishi Paper Mills Co., Ltd., the paper was printed on a printing press.

The results obtained are shown in Table 1 below.

The ink receptivity in the table is expressed by the number of prints that can be printed with good ink receptivity by bringing the ink roller into contact with the printing plate and feeding the paper at the same time. ◎ = 10 or less ○ = 25 or less △ = 50 Within × = 50 or more.

Also, background stains refer to ink stains in non-printing areas that occur when printing 5,000 sheets.

◎ No dirt at all ○ Slight dirt × Partially a lot of dirt Contrast is fog density + 0.1 on the characteristic curve
The slope of the straight line connecting the point and the point of fog density +0.3 was defined as the contrast.

■■■ Turtle Shell [0024] ■■■ As is clear from Table 1 above, Nos. 5 and 6, which used activators without sulfonic acid groups, had poor inking properties, which are essential for printing plates. Although there was background smudge, Samples Nos. 2 to 4 according to the present invention exhibited little decrease in contrast despite the harsh storage conditions, excellent ink receptivity, and printing plates with no background smear. It can be seen that this can be obtained.

Example 2 The following coating solution was applied as an antihalation layer onto a 140 g/m ² polyethylene-coated paper (corona discharge treated) using a slide hopper method.

[Antihalation liquid]

Gelatin 80g Carbon black 4g Formaldehyde 4% 15ml Silica powder (average particle size 7μ) 30g Finished with water to 1. Next, a silver halide emulsion (Table 2 below) prepared in the same manner as in Example 1 was added to the upper layer to prevent the above-mentioned halation. Multilayer coating was applied on top of the layer.

Subsequently, the following palladium sulfide sol was prepared as a physical development nucleus layer and coated on the emulsion layer by the dip method to obtain a lithographic printing plate.

[Preparation of palladium sulfide sol] Liquid A Palladium chloride 1g Hydrochloric acid 10ml Water 200ml Liquid B Sodium sulfide 1.7g Water 200ml Liquid C Methyl vinyl ether/maleic anhydride copolymer (1% aqueous solution) 50ml Saponin (10% aqueous solution) 50ml Water 3 After mixing liquids A and B with vigorous stirring at room temperature for 30 minutes, they were purified using an ion exchange resin, and liquid C was added to the liquid to obtain a coating liquid.

[Silver halide emulsion]

■■■ Tortoise shell [0025] ■■■ The sample thus obtained was exposed and developed in the same manner as in Example 1 to make a plate.

The results obtained are shown in Table 3 below.

However, the sensitivity in the formula is expressed as a relative sensitivity when a blank sample in same-day development of each emulsion is taken as 100. Further, the visible image quality represents the ease of viewing the image area (Dmin) and the non-image area (Dmax) after plate making, and the larger the value of Dmax-Dmin, the better the visible image quality.

■■■ Tortoise shell [0026] ■■■ From Table 3, samples No. 10, 11, 12, according to the present invention,
It can be seen that Nos. 14, 15, 16 and Nos. 18, 19, and 20 have less variation in characteristics during storage than the others, and that stable plate making with good visibility can be obtained.

Claims (1)

[Claims] 1. In a lithographic printing material for application to the silver salt diffusion transfer method, which contains a developing agent in an amount capable of developing the exposed silver halide in an alkaline activation bath, the silver halide contains a rhodium salt in an amount that increases contrast. A lithographic printing material comprising a photosensitive silver halide emulsion containing 70 mol% or more of silver chloride, and containing an anionic surfactant having at least one sulfonic acid group in its molecule.