JP2002099091A - Aluminum planographic printing plate material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum planographic printing plate forming a silver image high in acceptability of ink and exhibiting excellent printability. SOLUTION: The planographic printing plate characterized by containing an oil dispersing solution in at least one of layers in the planographic printing plate using a method of transferring silver complex salt diffusion in which at least a silver halide emulsion layer is provided on an anodically oxidized aluminum substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithographic printing plate using an aluminum support, and more particularly to a lithographic printing plate using a silver complex salt diffusion transfer method.

[0002]

2. Description of the Related Art A planographic printing plate using a silver complex salt diffusion transfer method (DTR method) is described in "Photographic Silver Halide," published by Focal Press, London New York (1972), by Andrelot and Edith Weide. Some examples are described in "Diffusion Processes", pp. 101-130.

There are two types of lithographic printing plates using the DTR method, a two-sheet type in which a transfer material and an image receiving material are separated, or a mono-sheet type in which they are provided on a single support. For the former, see, for example,
JP-A-158844 discloses the latter, for example, JP-B-48-30562, JP-B-51-15765, and JP-A-5-15765.
It is described in detail in respective gazettes such as 1-1111103 and 52-150105.

A monosheet type lithographic printing plate using an aluminum plate as a support and utilizing a silver complex salt diffusion transfer method (hereinafter referred to as an aluminum lithographic printing plate) is disclosed in
No. 118244, No. 57-158844, No. 63-2
60491, JP-A-3-116151, 4-28
No. 2,295, U.S. Pat. Nos. 4,567,131 and 5,427,889.

The aluminum lithographic printing plate has a basic structure in which a physical development nucleus is supported on a roughened and anodized aluminum support, and a substantially uncured silver halide emulsion layer is provided thereon. Consists of A general plate-making method for this aluminum lithographic printing plate comprises, after exposure, development, washing with water (wash-off: removal of a silver halide emulsion layer and the like), and finishing.

More specifically, a metal silver image portion is formed on a physical development nucleus by a development process, and a silver halide emulsion layer is removed by a subsequent washing process to form a metal silver image portion (hereinafter referred to as silver) on an aluminum support. Image portion) is exposed. At the same time, the anodized aluminum surface itself is exposed as a non-image area.

The exposed silver image area and the non-image area are treated with a finishing solution containing a protective colloid such as gum arabic, dextrin, carboxymethylcellulose, polystyrene sulfonic acid, etc. to protect the silver image area and the non-image area. Is applied. The finishing solution is also called a fixing solution or a finishing solution, and generally contains a compound (for example, a nitrogen-containing heterocyclic compound having a mercapto group or a thione group) that renders a silver image portion lipophilic.

The above aluminum lithographic printing plate has a higher printing durability than a lithographic printing plate in which an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer are sequentially provided on a flexible support such as a film or RC paper. On the other hand, there is an advantage that a printing plate excellent in the above is easily obtained, but there are various problems. For example, there is a problem that a sufficiently high ink receptivity cannot be stably obtained during printing.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aluminum lithographic printing plate capable of exhibiting excellent printability by constantly forming a silver image having high ink receptivity stably. .

[0010]

The present inventors have conducted intensive studies to solve the above-mentioned problems of the aluminum lithographic printing plate. As a result, the aluminum lithographic printing plate containing an oil dispersion in at least one of the layers was subjected to development treatment. By doing so, a silver image having high ink receptivity and strong printing durability was obtained, and it was found that the object of the present invention could be achieved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lithographic printing plate used in the present invention generally has a physical development nucleus layer and at least a silver halide emulsion layer on an aluminum support in order. An intermediate layer may be provided between the physical development nucleus layer and the silver halide emulsion layer, or a protective layer may be provided on the silver halide emulsion layer. The present invention is to contain an oil dispersion in any of these layers, and more preferably, to contain an organic compound having a lipophilic group and being soluble in an aqueous alkaline solution, in the oil dispersion. Is the thing.

The oil dispersion preferably contains 10 mg to 1 g of oil per square meter, and more preferably 50 mg to 200 mg per square meter. The organic compound having a group that imparts water solubility under alkaline conditions and a group that imparts lipophilicity in the same molecule preferably contains 1 mg to 500 mg per square meter, and particularly preferably 5 mg to 50 mg per square meter.

[0013] The oil dispersion suitable for the present invention can be achieved by utilizing the technology in the oil-protection method for oil-soluble couplers described in US Patent No. 2,322,027. In the case of the present invention, no oil-soluble coupler is required.

It is preferable that the oil dispersion is mechanically finely divided with the aid of a surfactant and dispersed in a binder such as gelatin. The oil dispersion preferably has an average oil particle size of 5 μm or less. 0.1-1 μm is preferred. By adding such an oil dispersion to any layer such as a silver halide emulsion layer, an intermediate layer and a protective layer, the ink receptivity of the silver image area can be improved. The actual state of the action is not clear, but it is presumed to be due to the dissolution of minute oil droplets with the progress of development and adsorption to the silver image area, thereby inhibiting the adsorption of hydrophilic substances such as gelatin. .

As the oil of the oil dispersion used in the present invention, a compound having a boiling point of 100 ° C. or higher is used.
Compounds having a boiling point of at least ℃ are preferred. Specific examples of the oil will be described below, but the present invention is not limited thereto.

<Specific examples of oil> Diethylene glycol diethyl ether, triethylene glycol monobutyl ether, polyethylene glycol monohexyl ether, polypropylene glycol dibenzoate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, diamyl naphthalene, monocaprin, diproline, Dicaprin, triacetin,
Tripalmitin, palmitooleinorenin, trilaurin, tricaprin, dipropyl adipate, dibutyl succinate, diisopropyl sebacate, octyl stearate, linseed oil, soybean oil, sesame oil, sunflower oil, cottonseed oil, sesame oil, rapeseed oil, olive oil, camellia There are oil, castor oil and the like, and two or more kinds may be used in combination.

In a more preferred embodiment, good results can be obtained by partially dissolving and dispersing an organic compound having a lipophilic group and soluble in an aqueous alkali solution in the oil. The condition of the organic compound soluble in the alkaline aqueous solution described herein is that 10 mg of the organic compound is completely dissolved at 27 ° C. per liter of an aqueous solution having a pH of 9 or more, and more preferably, a pH of 10 or more. That is, 10 mg of the organic compound is completely dissolved at 27 ° C. per liter of the aqueous solution.

Specifically, groups which impart water solubility under alkaline conditions include mercapto groups, thione groups, carboxy groups,
Examples thereof include an amide group, a thioureido group, and a hydroxy group, and one or more are substituted in the molecule of the organic compound. Examples of the lipophilic group include an aliphatic group and an aromatic group each having 3 or more carbon atoms, and one or more lipophilic groups are substituted in the molecule of the organic compound. The aliphatic group imparting lipophilicity is preferably a linear, branched or cyclic alkyl group, and the aromatic group imparting lipophilicity is preferably a monocyclic or bicyclic aryl group. Specific examples include propyl, pentyl, hexyl, octyl, decyl, undecyl, hexadecyl, oleyl, phenyl, naphthyl, styryl and the like. The advantage of adding the above organic compound by oil dispersion is that the contact between silver halide and the above organic compound can be suppressed, and the influence on photographic properties can be minimized. Preferred representative examples of the organic compound are represented by the following general formula 1.
Shown in

[0019]

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R _{1 in the} general formula 1 represents an aliphatic group (eg, an alkyl group, an alkenyl group, an alkynyl group, etc.) or an aromatic group (eg, an aryl group, etc.) having 3 or more carbon atoms.
X ₁ and X ₂ represent a mercapto group, a carboxy group, an amide group,
Represents a thioureido group or a hydroxy group. L is 0 or 1
Represents The compounds of the general formula 1 used in the present invention are described below, but the invention is not limited thereto.

[0021]

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[0022]

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Another preferred example of the organic compound used in the present invention is shown in the general formula 2.

[0024]

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R ₂ and R _{4 in} the general formula 2 have 3 or more carbon atoms and preferably represent an alkyl group, an alkenyl group, an aralkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group or an arylthio group. ₃ represents hydrogen, an alkyl group, an alkenyl group, an aralkyl group or an aryl group. m, n represents an integer of 1 or more, R ₃
Is an alkyl group, an alkenyl group, an aralkyl group or an aryl group having 3 or more carbon atoms, n may be 0. Z is 5 to 6 together with carbon, nitrogen and sulfur atoms in the formula.
The remaining atomic groups of the bond necessary to form a member ring are shown.

Specific examples of the 5- or 6-membered ring include imidazole, imidazoline, thiazole, thiazoline,
Oxazole, oxazoline, pyrazoline, triazole, thiadiazole, oxadiazole, tetrazole, pyridine, pyrimidine, pyridazine, pyrazine, triazine, etc., and these rings may be two or more condensed rings; And those condensed with a naphthalene ring.

Specific examples of related specific compounds include 2
-Mercapto-4-phenylimidazole, 2-mercapto-1-benzylimidazole, 2-mercapto-1
-Butylbenzimidazole, 1-methyl-4-butylimidazolidin-2-thione, 2-mercapto-4-phenylthiazole, 3-butylbenzothiazoline-2-
Thione, 3-dodecylthiazoline-2-thione, 3-pentylbenzoxazoline-2-thione, 1-phenyl-3-methylpyrazolin-5-thione, 3-mercapto-5-nonyl-1,2,4-triazole, 2 -Mercapto-5-phenyl-1,3,4-thiadiazole, 2
-Mercapto-5-pentylthio-1,3,4-thiadiazole, 2-mercapto-5-heptyl-1,3,4
-Oxadiazole, 2-mercapto-5-phenyl-
1,3,4-oxadiazole, 2-mercapto-5
Decyl-1,3,4-oxadiazole, 5-mercapto-1-phenyltetrazole, 5-mercapto-1-
Hexadecyltetrazole, 3-mercapto-4-methyl-6-phenylpyridazine, 2-mercapto-5,6
-Diphenylpyrazine, 2-mercapto-4-phenyl-1,3,5-triazine, 2-amino-4-mercapto-6-benzyl-1,3,5-triazine and the like, but are not limited thereto. Not something.

The aluminum support used in the present invention is a roughened and anodized aluminum plate,
1.0g or more per square meter, preferably 1.5g
Those having 5 g of porous aluminum oxide are used.

The physical development nuclei of the physical development nucleus layer may be those used in a known silver complex salt diffusion transfer method. For example, a sulfide is mixed with a water-soluble salt such as a colloid such as gold or silver or a palladium or zinc. Metal sulfide and the like can be used. In some cases, it can be carried out without using a physical development nucleus. Various hydrophilic colloids can be used as the binder. These details and the production method are described in, for example, JP-B-48-30562 and JP-A-48-5540.
Nos. 2, 53-21602, Focal Press, London New York (1972), Andre
See Lott and Edith Weide, Photographic Silver Halide Diffusion Processes. Also, even if the physical development nucleus is not used, D
It is known that TR development is possible, and it is not always necessary to use it.

The silver halide emulsion grains used in the present invention can be formed by various methods known so far. That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and a method of reacting a soluble silver salt with a soluble halide may be any of a single jet method, a double jet method, a combination thereof and the like. . As one type of the double jet method, a method in which pAg in a liquid phase in which silver halide is formed is kept constant, that is, a controlled double jet method can be used. Further, as described in British Patent Nos. 1,535,016, JP-B-48-36890, and JP-B-52-16364, the addition rate of silver nitrate or an aqueous alkali halide solution is changed according to the grain formation rate. How to make
U.S. Pat. No. 4,242,445, JP-A-55-158
No. 124 or the like, a method of changing the concentration of the aqueous solution may be used, and a method of rapidly growing the solution within a range not exceeding the critical supersaturation degree may be used. In addition, multilayer structured particles such as core-shell particles composed of the inside (core portion) and the outside (shell portion) of the particles can also be used.

The silver halide emulsion used in the present invention is:
The silver halide is selected from silver chloride, silver bromide, silver chlorobromide, silver chloroiodobromide, silver iodobromide, etc., which are generally used. Silver chloride is 70 mol% or more, preferably 90 to 100 mol%. Is preferred. The content of silver iodide is preferably from 0 to 2 mol%, more preferably from 0.1 to 1.0 mol%. In particular, it is preferable that after the silver iodide has formed silver chloride grains, a water-soluble iodide is added to convert the surface of the silver chloride grains with silver iodide. It is preferable to use a metal salt such as a rhodium salt or an iridium salt when forming a silver halide crystal.

The shape of the silver halide grains used in the present invention is particularly preferably one having a regular crystal such as cubic, but other octahedral, irregular or plate-like. There may be. The average grain size of the silver halide is preferably 0.6 μm or less, more preferably 0.1 to 0.5 μm, and the grain size distribution is 9 μm or less.
Monodisperse silver halide grains in which 5% of the grains fall within ± 30%, preferably ± 20% of the number average grain size are preferred.

In general, the silver halide emulsion of the present invention is preferably subjected to desalting and then sensitized with various chemical sensitizers, such as sulfur sensitization, reduction sensitization, gold sensitization and selenium sensitization. Sensitization, tellurium sensitization, etc., but gold sensitization using chloroauric acid, trichloroauric acid, thiocyanateauric acid or the like as a sensitizer is preferred. More preferably, chemical sensitization by sulfur plus gold sensitization is most preferable. As a sulfur sensitizer, in addition to sulfur compounds contained in gelatin,
Various sulfur compounds such as thiosulfates, thioureas, thiazoles, rhodanines and the like can be used.

Various gelatins such as acid-treated gelatin and alkali-treated gelatin can be used as the gelatin used in the present invention. Further, those modified gelatins (for example, phthalated gelatin, amidated gelatin, etc.) can also be used. Further, a binder such as polyvinylpyrrolidone, various starches, albumin, polyvinyl alcohol, gum arabic, and hydroxyethyl cellulose can be contained. Further, in the present invention, Japanese Patent Application Laid-Open
No. 116151, water-swellable intermediate layer;
An intermediate layer containing the hydrophobic polymer beads described in Japanese Patent No. 82295 may be provided.

The silver halide emulsion of the present invention can be spectrally sensitized using a dye known in the photographic industry as a sensitizing dye. In particular, 600 for scanning exposure of a red light source (helium / neon laser, red LED, etc.)
It is preferable to use a sensitizing dye having a spectral absorption at about 700 nm. These dyes include cyanine dyes, merocyanine dyes, composite cyanine dyes, composite merocyanine dyes,
Examples include holo-holer cyanine dyes, hemicyanine dyes, styryl dyes, and hemioxanol dyes. These sensitizing dyes may be used alone or in combination. Combinations of sensitizing dyes are often used, especially for supersensitization. Along with the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization.

The coating amount of the binder for the protective layer is in the range of 0.1 g to 3 g, preferably 0.3 to 2 g per square meter of the aluminum lithographic printing plate, and may be two or more layers.

The amount of the binder applied to the intermediate layer is preferably 0.2 g or less per square meter of the aluminum lithographic printing plate, and may be two or more layers.

In the present invention, the binder may be cured with a hardener. Examples of hardeners include formaldehyde, aldehyde compounds such as glutaraldehyde, diacetyl, ketone compounds such as chloropentanedione,
2-hydroxy-4,6-dichloro-1,3,5-triazine, a compound having a reactive halogen as described in U.S. Pat. No. 3,288,775, divinyl sulfone, U.S. Pat. No. 3,635,718 Compounds having a reactive olefin as described, N-methylol compounds as described in U.S. Pat. No. 2,732,316, U.S. Pat.
Isocyanates as described in US Pat. No. 3,437, aziridine compounds as described in US Pat. Nos. 3,017,280 and 2,983,611, US Pat. No. 3,100,70.
No. 4, carbodiimide compounds, epoxy compounds as described in U.S. Pat. No. 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chrome alum, zirconium sulfate, boric acid and the like. There are inorganic cross-linking agents such as borate, and these can be used alone or in combination of two or more.

The aluminum lithographic printing plate of the present invention has a coating amount of silver halide in terms of silver nitrate of 0.5 g to 5 g, preferably 1.0 to 3.0 g per square meter.
Is preferably within the range.

The silver halide emulsion layer may contain, if necessary, an antifoggant such as anionic, cationic, betaine or nonionic surfactants, quaternary ammonium salts, thioether compounds, polyethylene oxide derivatives, mercaptotetrazole, etc. A chelating agent such as ethylenediaminetetraacetate and a developing agent such as hydroquinone and 3-pyrazolidinones may be contained.

The developing solution used in the present invention includes developing agents such as polyhydroxybenzenes such as hydroquinone, 3-pyrazolidinones such as 1-phenyl-3-pyrazolidinone and derivatives thereof, alkaline substances such as potassium hydroxide and water. Sodium oxide, lithium hydroxide, tertiary
Sodium phosphate or amine compounds, preservatives such as sodium sulfite, thickeners such as carboxymethylcellulose, antifoggants such as potassium bromide, development modifiers such as polyoxyalkylene compounds, chelating agents such as ethylenediaminetetraacetic acid, Silver halide solvents, for example, thiosulfates such as sodium thiosulfate and potassium thiosulfate, 2-mercaptobenzoic acid and derivatives thereof,
Cyclic imides such as uracil, alkanolamines,
Diamines, mesoionic compounds, thioethers and the like can be mentioned. The pH of the developer is 11 to 14, especially pH 1
It is preferably 1.5 to 13.5.

It is preferable that the developer further contains a compound (lipophilic agent) for making the silver image area lipophilic. Examples of oleophilizers include Focal Press, London New York (1972), by Andrelot and Edith Weide, Photographic Silver Halide Diffusion Processes, 105, 10
Compounds described on page 6 can be mentioned. For example, there are a compound having a mercapto group or a thione group and a quaternary ammonium compound. In the present invention, a compound having a mercapto group or a thione group is preferably used. Particularly preferred are nitrogen-containing heterocyclic compounds having a mercapto group or a thione group, and JP-B-48-2972.
No. 3, JP-A-58-127928 and the like.

In the method of developing an aluminum lithographic printing plate of the present invention, a general immersion type development may be performed, or a development (coating development type) in which a required amount of a developing solution is supplied to the plate surface. Is also good.

The coating and developing methods in the present invention include, for example, JP-A-48-76603 and JP-A-5-289343.
, No. 6-27680, No. 6-27682, No. 10-62952, No. 10-62951 and the like.

In the step of removing the residual film after the development is completed, a general shower water washing method or the like is preferable.
A method of mechanically contacting an emulsion layer or the like, such as a release sheet described in JP-A-6151 and 4-318553, may be used.

The silver image portion and the non-image portion exposed on the aluminum lithographic printing plate surface are treated with a finishing liquid in order to increase their lipophilicity and hydrophilicity and to protect the plate surface. In the finishing solution in the present invention, for protection of the anodized layer in the non-image area and improvement of hydrophilicity, gum arabic, dextrin, sodium alginate, propylene glycol ester of alginic acid, hydroxyethyl starch, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone , A protective colloid such as polystyrene sulfonic acid and polyvinyl alcohol. Further, in order to further improve the lipophilicity of the silver image area, it is preferable to contain the above-mentioned lipophilic agent or enzyme.

[0047]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

<Preparation of Sample A> The electrolytic surface roughening treatment and the anodic oxidation of the aluminum support were conducted in US Pat. No. 5,427,8.
No. 89, a pit having a diameter of 0.03-0.30 μm was formed on a plate having an average diameter of about 5 μm.
An aluminum plate having a thickness of 0.30 mm, having about 2700 pits per 00 μm ² and having an average diameter of these pits of 0.13 μm was obtained. This aluminum plate was anodized after the surface roughening treatment.
g of porous aluminum oxide having an average roughness (R
a) was 0.4 to 0.5 μm.

The aluminum support was coated with a physical development nucleus solution comprising a silver sol prepared by the Curry-Lee method, and then dried. The amount of nuclei contained in the physical development nucleus layer is 3
mg / m ² .

A silver halide emulsion was prepared by using alkali-treated gelatin as a binder, and adding potassium hexachloroiridate (IV) having an average particle size of 0.25 μm to the solution by a control double jet method in an amount of 0.005 mol / mol of silver.
A silver chlorobromide emulsion of 1.5 mol% of silver bromide doped with 6 mmol was prepared, and 0.3 mol% of silver iodide was obtained at the end of physical ripening.
To obtain a silver chloroiodobromide emulsion. Thereafter, the emulsion was flocculated and washed. Further, gelatin was added to this emulsion, and after sensitization with sulfur gold, a stabilizer was added, and sensitizing dye D-1 was added.
Was spectrally sensitized using 1 mg / g of silver. Further, a surfactant was added to prepare a silver halide emulsion.

[0051]

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The silver halide emulsion prepared in this manner was coated on the aluminum support coated with the physical development nuclei and dried so that the silver amount was 2.5 g per square meter, to obtain a sample A. Was.

<Preparation of Sample B> At room temperature, 200 g of n-dioctyl phthalate, 1.8 kg of an aqueous solution obtained by dissolving 40 g of a surfactant and 20 g of gelatin were mixed.
Using a homogenizer CM-200 manufactured by i.
By dispersing at about 00 rpm for about 1 hour, the average particle size is about 0.1 μm.
2 kg of a 4 μm oil-dispersed aqueous solution was obtained. To the same silver halide emulsion as in Sample A, 2 g of this oil dispersion was added per square meter to obtain Sample B in the same manner as in Sample A.

<Preparation of Sample C> An aqueous solution in which 200 g of polypropylene glycol dibenzoate (average molecular weight: 500), 40 g of a surfactant and 20 g of gelatin were dissolved.
8 kg and mixed in the same dispersion method as in Sample B above.
g of an oil-dispersed aqueous solution was obtained. Sample C was obtained in the same manner as for Sample B so that the oil-dispersed aqueous solution was 2 g per square meter.

<Preparation of Sample D> 200 g of di-n-butyl succinate, 1.8 kg of an aqueous solution obtained by dissolving 40 g of a surfactant and 20 g of gelatin were mixed, and 2 kg of oil was dispersed in the same manner as in Sample B. An aqueous dispersion was obtained. Sample C was obtained in the same manner as for Sample B so that the oil-dispersed aqueous solution was 2 g per square meter.

<Preparation of Sample E> At room temperature, 180 g of n-dioctyl phthalate was mixed with 2-mercapto-5- (n-
20 g of (decyl) -1,3,4-oxadiazole was uniformly dissolved, further mixed with 1.8 kg of an aqueous solution in which 40 g of a surfactant and 20 g of gelatin were dissolved, and averaged at about 10,000 rpm using an iuchi homogenizer CM-200. By dispersing for about 1 hour, 2 kg of an aqueous oil dispersion having an average particle size of about 0.4 μm was obtained. Sample E was obtained in the same manner as in Sample A by adding 2 g of this aqueous oil dispersion per square meter to the same silver halide emulsion as Sample A.

<Preparation of Sample F> 20 g of diphenylacetic acid was uniformly dissolved in 180 g of n-dioctyl phthalate, and 1.8 kg of an aqueous solution obtained by dissolving 40 g of a surfactant and 20 g of gelatin was mixed. By the method, 2 kg of an oil-dispersed aqueous solution was obtained. Sample F was obtained in the same manner as for Sample E so that the oil-dispersed aqueous solution was 2 g per square meter.

<Preparation of Sample G> An aqueous solution obtained by uniformly dissolving 20 g of oleic acid in 180 g of n-dioctyl phthalate, further dissolving 40 g of a surfactant and 20 g of gelatin.
8 kg and mixed in the same dispersion method as in Sample E above.
g of an oil-dispersed aqueous solution was obtained. Sample G was obtained in the same manner as in Sample E so that the oil-dispersed aqueous solution was 2 g per square meter.

<Preparation of Sample H> An aqueous solution in which 20 g of sebacic acid was uniformly dissolved in 180 g of n-dioctyl phthalate, and 40 g of a surfactant and 20 g of gelatin were dissolved.
8 kg and mixed in the same dispersion method as in Sample E above.
g of an oil-dispersed aqueous solution was obtained. A sample H was obtained in the same manner as the sample E so that the oil-dispersed aqueous solution was 2 g per square meter.

The samples A to H (half chrysanthemum size) were 633 n
m using a red LD laser as a light source, and then a plate making processor (Dupont SLT-85).
N automatic developing machine) to prepare a lithographic printing plate. The plate making processor includes a developing step (immersion at 22 ° C. for 15 seconds), a water washing step (peeling off the remaining film with a scrub roller while spraying a washing liquid at 30 ° C. for 10 seconds),
It comprises a finishing process (22 ° C., 5 second shower) and a drying process.

The compositions of the developing solution, neutralizing solution and finishing solution are shown below. <Developer> Sodium hydroxide 25 g Polystyrene sulfonic acid and maleic anhydride copolymer (average molecular weight 500,000) 10 g Sodium ethylenediaminetetraacetate 2 g Sodium sulfite 100 g Monomethylethanolamine 25 g 2-Mercapto-5- (n-heptyl) -1,3,4-oxadiazole 0.5 g sodium thiosulfate (pentahydrate) 8 g hydroquinone 15 g 1-phenyl-3-pyrazolidinone 3 g The total amount is made 1000 ml. pH (25 ° C.) = 13.1

<Washing solution> 2-mercapto-5- (n-heptyl) -1,3,4-oxadiazole 0.5 g monoethanolamine 13 g sodium bisulfite 10 g potassium monophosphate 40 g The total amount is made 1000 ml. pH = 6.0

<Finishing liquid> Phosphoric acid 0.5 g Monoethanolamine 5.0 g 2-Mercapto-5- (n-heptyl) -1,3,4-oxadiazole 0.5 g Polyglycerol (hexamer) 50 g Total amount To 1000 ml. pH = 7.2

The lithographic printing material prepared by the method described above was used for a printing press Heidelberg TOK (Heidel).
berg offset printing press), ink (New Champion Boku H made by Dainippon Ink) and commercial PS
Printing was performed using a plate moisture absorber. The evaluation of the ink receptivity of the plate was based on the following four levels of the number of sheets from the beginning of printing until the ink was uniformly applied. A 10 sheets or less B 11-20 sheets C 21-30 sheets D 31 sheets or more

[0065]

[Table 1]

Further, even when the sample of the present invention was continuously printed on 100,000 sheets, the effect of ink receptivity was not impaired.

[0067]

As is apparent from the above results, the present invention forms a silver image having high ink receptivity as compared with the comparative example,
A lithographic printing plate having excellent printing characteristics was obtained.

Claims (2)

[Claims] In a lithographic printing plate utilizing a silver complex salt diffusion transfer method having at least a silver halide emulsion layer on an anodized aluminum support, at least one of the layers contains an oil dispersion. A lithographic printing plate characterized by the following. 2. The oil dispersion has a lipophilic group,
2. The lithographic printing plate according to claim 1, further comprising an organic compound soluble in an aqueous alkaline solution.