JPH11258810A - Planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a planographic printing plate excellent in printing resistance and water retentiveness and having good water retentiveness particularly in long term storage by incorporating a homo- or copolymer of acrylamide and a water-dispersible particulate polymer into a physical developing nucleus layer. SOLUTION: A planographic printing plate material contg. a homo or copolymer of acrylamide and a water-dispersible fine particulate polymer in a physical developing nucleus layer is used. The water-dispersible particulate polymer, that is, a synthetic polymer latex may be selected from various polymer latices. The polymer is preferably a copolymer of an ethylenically unsatd. monomer, that is, a vinyl monomer classified particularly in a soft polymer latex having <=0 deg.C min. film formation temp. The vinyl monomer is, e.g. an acrylic ester, an α-substd. acrylic ester, acrylamide, a vinyl ester, a vinyl halide, a vinylidene halide or a vinyl ether.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithographic printing material to which a silver complex salt diffusion transfer method is applied.

[0002]

2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image portion that receives oily ink and an oil-repellent non-image portion that does not receive ink. Generally, the non-image portion includes a hydrophilic portion that receives water. It is configured. In normal lithographic printing, both water and ink are supplied to the plate surface, the image portion selectively receives color ink, the non-image portion selectively receives water, and the ink on the image is coated on paper, for example, paper. Printing is performed by transferring the image to a print body.

[0003] Therefore, in order to obtain good printed matter, the difference between the lipophilicity and the hydrophilicity of the image area and the non-image area is sufficiently large, and when water and ink are supplied to the printing plate, the image area has a sufficient amount of ink. It is necessary that the non-image portion accepts no ink at all.

A lithographic printing plate using a silver complex salt diffusion transfer 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. 3,728,114;
Nos. 4,134,769 and 4,160,670
No. 4,336,321 and 4,501,81
No. 1, 4,510,228 and 4,621,0
No. 41, etc., the exposed silver halide crystal undergoes chemical development by silver salt diffusion transfer development and becomes black silver to form a hydrophilic non-image portion. On the other hand, unexposed silver halide crystals are converted into a silver salt complex by the silver salt complexing agent in the developing solution and diffused to the physical development nucleus layer on the surface. To form an image part mainly composed of a physically developed silver having a characteristic.

[0005] As described above, the lithographic printing plate requires gelatin-
Since the silver image deposited on the physical development nucleus layer on the silver halide emulsion layer is used as an image area having ink receptivity, the image area has a lower strength than a general lithographic plate (for example, PS plate). However, it has a disadvantage that it is sufficient and the ink receptivity is easily lost.

To overcome this drawback, techniques for increasing the degree of hardening of gelatin and increasing the amount of physical development nuclei are known. However, soiling during printing tends to occur. As a result, the performance of the lithographic printing plate was often significantly reduced. Further, there is also a disadvantage that the lithographic printing plate is stored for a long period of time from production to plate making, thereby causing background stains and deteriorating ink receptivity. As for the improvement of water retention (stain resistance), attempts have been made to include various water-soluble polymers in the physical development nucleus layer. Examples of the water-soluble polymer include JP-A-53-2
No. 1602, a copolymer of acrylamide and imidazole, high water-retentivity polymer of JP-A-2-282750, pullulan of JP-A-4-277747, and JP-A-4-277748
No. 6-230596, polysaccharide No. 8-221
No. 614, a copolymer of acrylamide and methylstyrene substituted with guanylthiourea or the like. Other,
Gelatin, methyl vinyl ether, maleic anhydride copolymer, polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, gum arabic and the like are known. However, a stable high level of water retention has not yet been obtained, and there has been no effect particularly on the reduction in water retention due to long-term storage of the lithographic printing material.

The water-dispersible fine particle polymer used in the present invention is disclosed in Japanese Unexamined Patent Publication No.
No. 6564, No. 5-80519, No. 6-3244
No. 96 and the like, and an effect of improving water retention, printing durability, and ink / water responsiveness has been proposed. In addition, 57-1
No. 9730 proposes a technique for improving the running processability, the printing durability immediately after plate making, and the photographic preservability by using the silver halide emulsion layer or the like. However, although these techniques improve printing performance to some extent, they are not sufficient techniques for obtaining stable water retention and printing durability for long-term storage of lithographic printing plates.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithographic printing plate using a silver salt diffusion transfer method, which has excellent printing durability and water retention, and particularly good water retention for long-term storage. It is.

[0009]

The object of the present invention is to provide a lithographic printing plate to which a silver complex salt diffusion transfer method having at least a silver halide emulsion layer and a physical development nucleus layer on a support is used. This is achieved by a lithographic printing material characterized in that the layer contains a homopolymer or a copolymer of acrylamide and a water-dispersible fine particle polymer.

As the water-dispersible fine particle polymer used in the present invention, so-called synthetic polymer latex, a wide range of polymer latex can be used. Preferably, it is a copolymer of an ethylenically unsaturated monomer, a so-called vinyl monomer, and is particularly classified as a polymer latex having a minimum film forming temperature of 0 ° C. or less. The minimum film formation temperature can be measured by a temperature gradient plate method as described in Soichi Muroi, Chemistry of Polymer Latex (1970), p. 260. The minimum film forming temperature can be changed by selecting the components and the composition ratio.

[0011] Suitable vinyl monomers include acrylates (methyl acrylate, ethyl acrylate,
Propyl acrylate, butyl acrylate, t-butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, etc., α-substituted acrylate (methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, etc.) ), Acrylamide (butylacrylamide, hexylacrylamide, etc.), vinyl ester (vinyl acetate, etc.), vinyl halide (vinyl chloride, etc.), vinylidene halide (vinylidene chloride, etc.), vinyl ether (vinyl methyl ether, vinyl octyl ether, etc.) styrene , Ethylene, butadiene, acrylonitrile and the like.

Particularly preferred are alkyl acrylate and alkyl methacrylate. Alkyl acrylate or alkyl methacrylate copolymers containing acrylic acid, methacrylic acid, itaconic acid or vinyl monomers having sulfonic acid groups in a proportion of 30 mol% or less are particularly useful. Specific examples of these are disclosed in JP-B-46-225.
06, JP-A-56-56227 and 51-59942
Etc. can be referred to. The synthetic polymer latex disclosed in the above-mentioned patent specification can be used particularly advantageously. For example, preferred synthetic polymer latexes can be used particularly advantageously. For example, preferred synthetic polymer latices include (butyl acrylate-acrylic acid) copolymer, (methyl acrylate-acrylic acid)
Copolymer, (ethyl acrylate-acrylic acid) copolymer, (butyl acrylate-itaconic acid) copolymer, (ethyl acrylate-methacrylic acid) copolymer, (propyl acrylate-acrylic acid) copolymer, (butyl acrylate-styrene sulfonic acid) copolymer, (ethyl Acrylate-styrene sulfonic acid)
Copolymer, (methyl acrylate-sulfopropyl acrylate) copolymer, (ethyl acrylate-acrylic acid-2-acetoacetoxy-ethyl methacrylate) copolymer, (methyl methacrylate-acrylic acid) copolymer, (methyl methacrylate-itaconic acid) copolymer, (styrene -Butadiene) copolymer, (vinyl acetate-ethylene) copolymer and the like.

Although there are many techniques for using a synthetic polymer latex with a binder constituting a photographic layer such as gelatin as described above, the present invention is characterized by a physical development nucleus layer using a trace amount of a binder. The use amount of the polymer latex of the present invention is 1 g / m ² or less in a lithographic printing material to exhibit the effects of the present invention.
0.1 mg to 100 mg / m ² .

The present invention provides a stable water retention property immediately after production by incorporating a homopolymer or a copolymer of the polymer latex and acrylamide into a physical development nucleus layer. Improvement can be achieved. Other monomers copolymerized with acrylamide include, for example, styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, and methacrylic acid. Methyl methacrylate alkyl esters such as methyl, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, methacrylate aryl esters such as phenyl methacrylate and benzyl methacrylate, or Amyl group-containing methacrylic esters such as alkylaryl esters, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, and acrylic esters. Examples similar to the corresponding methacrylic acid esters, or monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, monoalkyl maleate, monoalkyl fumarate , Allylamine, amino group-containing monomers such as diallylamine,
Alternatively, 4-vinylpyridine, 2-vinylpyridine,
Monomers having a nitrogen-containing heterocycle such as N-vinylimidazole and N-vinylcarbazole, or acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-methylolacrylamide, N-isopropylacrylamide, Acrylamide or methacrylamide derivatives such as acetone acrylamide and N-methoxyethyl acrylamide, and vinyl esters such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, and vinyl benzoate And vinyl ethers such as methyl vinyl ether and butyl vinyl ether; and other substances such as N-vinylpyrrolidone and acryloylmorpholine. Tetrahydrofurfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, may be used glycidyl methacrylate and various monomers as timely copolymerized monomers. The molecular weight of the obtained polymer is preferably in the range of 5,000 to 1,000,000 as a weight average molecular weight.

Physical development nuclei include fine particles of metal colloids such as silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold and platinum, and sulfides, polysulfides, selenides, and the like of these metals. Alternatively, a mixture or a mixed crystal thereof may be used.

Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone or catechol, or a known hardener such as formalin or dichloro-s-triazine.

The silver halide emulsion layer includes, for example, silver chloride,
It comprises 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, a platinum salt, and the like, in an amount of 10 ^-8 to 10 ^-3 per mol of silver halide. Is a mole. The crystal form of the silver halide is not particularly limited, and may be cubic to tetradecahedral grains, or core-shell or tabular grains. The silver halide crystals may be monodisperse or polydisperse crystals, and the average grain size is in the range of 0.2 to 0.8 μm. One preferred example is a monodispersed or polydispersed crystal containing 70% by mole or more of silver chloride containing a rhodium salt or an iridium salt.

The silver halide photographic emulsion of the present invention can be a so-called primitive emulsion which is not subjected to chemical sensitization, but is usually chemically sensitized. For chemical sensitization, a sulfur sensitization method using a compound that can react with active gelatin or silver, a reduction sensitization method using a reducing substance, a noble metal sensitization method using a noble metal compound, etc. are performed alone or in combination. I do. The silver halide photographic emulsion of the present invention can be sensitized using a quaternary ammonium salt, a thioether compound, a polyethylene oxide derivative, a diketone, or the like.

The silver halide photographic emulsion used in the present invention can be sensitized by various methods when it is manufactured or coated. It is preferred to chemically sensitize by methods well known in the art such as, for example, with sodium thiosulfate, alkyl thioureas, or with gold compounds such as rhodium gold, gold chloride, or a combination of both. Silver halide emulsions can also be sensitized or desensitized positively or negatively by, for example, cyanine dyes, merocyanine dyes, trinuclear cyanine dyes, oxonol dyes, and the like. There is no particular limitation on the wavelength range in which the sensitization or desensitization can be performed. Therefore, orthosensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, and semiconductor laser sensitization can be performed, and UV sensitization and visible light reduction for a bright room can be performed. You can feel it.

The silver halide photographic emulsion and the non-photosensitive hydrophilic colloid solution may be used in various ways for the purpose of preventing fog during the production process, during storage or development as a product, or for stabilizing photographic performance. Can be contained. That is, compounds known as antifoggants or stabilizers can be added.

For example, thiazoles such as benzothiazolium salts, nitroindazoles, triazoles and benzimidazoles (particularly nitro- or halogen-substituted): heterocyclic mercapto compounds such as mercaptothiazoles, mercaptothiadiazoles and mercaptobenz Thiazoles, mercaptobenzimidazoles, mercaptotetrazoles (especially 1-phenyl-
5-mercaptotetrazole), mercaptopyrimidines: the above heterocyclic mercapto compounds having a water-soluble group such as a carboxyl group or a sulfone group: thioketo compounds, such as oxazolinethione: azaindenes, such as tetraazaindenes (particularly 4-hydroxy There are antifoggants or stabilizers such as substituted (1,3,3a, 7) tetraazaindenes: benzenethiosulfonic acids: benzenesulfinic acids: and the like.

It is advantageous to use gelatin as a protective colloid which can be used in the silver halide photographic emulsion layer and the non-photosensitive hydrophilic colloid layer of the present invention. Can be used in place of For example, colloidal albumin, casein, carboxymethyl cellulose, derivatives such as hydroxyethyl cellulose, agar, sodium alginate, sugar derivatives such as starch derivatives, synthetic hydrophilic colloids such as polyvinyl alcohol, poly N-vinyl pyrrolidone, polyacrylamide or derivatives thereof And partial hydrolysates.

In the present invention, a silver halide photographic emulsion,
The non-photosensitive hydrophilic colloid solution may contain various surfactants for the purpose of coating aid, antistatic, improving slipperiness, emulsifying and dispersing, preventing adhesion and improving photographic properties.

For example, saponins (steroids), alkylene oxide derivatives (eg, polyethylene glycol, polyethylene glycol / polypropylene glycol condensate, polyethylene glycol alkyl ethers or polyethylene glycol alkyl alcohol ethers, polyethylene glycol esters, polyethylene glycol sorbitan ester) , Polyalkylene glycol alkylamines or amides, polyethylene oxide adducts of silicone), glyoxide-lyl derivatives (eg, alkenyl succinic acid polyglyceride, alkylsoenol polyglyceride, etc.), fatty acid esters of polyhydric alcohols, sugars Non-ionic surfactants such as alkyl esters, alkyl carboxylate,
Alkylsulfonic acid, alkylbenzenesulfonic acid salt,
Carboxy groups such as alkyl naphthalene sulfonates, alkyl sulfates, alkyl phosphates, N-acyl-N-alkyl taurines, sulfosuccinates, sulfoalkyl polyoxyethylene alkyl phosphates, and the like; Anionic surfactants containing acidic groups such as sulfo groups, phospho groups, sulfate groups, and phosphate groups, amino acids, aminoalkyl sulfonic acids, aminoalkyl sulfates or phosphates, alkyl betaines, amine oxides, etc. Amphoteric surfactants, alkylamine salts, aliphatic or aromatic quaternary surfactants
Cationic surfactants such as quaternary ammonium salts, heterocyclic quaternary ammonium salts such as pyridium and imidazolium, and phosphonium or sulfonium salts containing aliphatic or heterocyclic rings can be used.

In the present invention, a mat can be formed by adding silica, starch powder, colloidal silica, glass powder and the like.

In the present invention, the physical properties of the gelatin film may be modified by adding a polymer latex or the like to the gelatin film. Preferred examples of the polymer latex used in the present invention include an alkyl ester of acrylic acid, a hydroxyalkyl ester, or an alkyl ester of methacrylic acid as a monomer unit, and have an average molecular weight of 100,000 or more, and particularly preferably 30 to 50. Ten thousand polymers,
The polymer latex is preferably used in an aqueous dispersion of a water-insoluble polymer having an average particle diameter of 20 to 200 mμ, and the dry weight ratio is particularly preferably 0.1 to 1.0 with respect to gelatin 1.0 used as a protective colloid. Is 0.1 to 0.8
It is.

The lithographic printing plate which is the object of the present invention contains gelatin, which is a subbing layer, an emulsion layer and a backing layer. These gelatins can be hardened with a gelatin hardener. As a gelatin hardener,
The silver halide photographic emulsion solution and the non-photosensitive hydrophilic colloid solution may contain an inorganic or organic hardener. For example, chloric acid (chrom alum, chromium acetate, etc.), aldehydes (formaldehyde, glyoxal, glutaraldehyde, malealdehyde, etc.), N-methylol compounds such as urea and ethylene urea (dimethylol compounds, methylol dimethylhydantoin, etc.), dioxane derivatives (2,3-dihydroxydioxane, etc.), active vinyl compounds (1,3,5-triacroyl-hexahydro-S-triazine, 1,3-vinylsulfonyl-
2-propanol and the like, compounds having an active halogen (such as 2,4-dichloro-6-hydroxy-S-triazine), mucohalic acids (such as mucochloric acid and mucofenoxycyclolic acid), and ethylene as an active three-membered ring Compounds having two or more imino groups or epoxy groups in the molecule,
Various compounds such as dialdehyde starch as a polymer hardener can be used alone or in combination.

Hardeners can be added to all layers or to some or only one layer.
Of course, in the case of two-layer simultaneous application, the diffusible hardener can be added to only one of the layers. The addition method can be added at the time of emulsion production or in-line at the time of coating.

The polymer binder of the undercoat layer is generally 0.5
More preferably to 10 g / m ² is 1 to 6 g / m ^2. The undercoat layer may contain a pigment or dye such as carbon black for the purpose of preventing halation, and may contain a solid powder (for example, silica particles) having an average particle size of 2 to 10 microns for improving printing durability. Further, a photographic additive such as a developing agent can be included. The undercoat layer is disclosed in JP-A-48-550.
3, and those described in JP-A-48-100203 and JP-A-49-16507.

Various compounds other than those described above, for example, an antistatic agent, an antihalation dye, a plasticizer, a developing agent, a development accelerator and the like may be added to the silver halide photographic emulsion or the non-photosensitive hydrophilic colloid solution of the present invention. Arbitrarily.

Part of the gelatin in the gelatin-containing layer of the present invention is water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene. It can 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.

As the support of the lithographic printing plate of the present invention, typical supports include paper, RC paper or synthetic or semi-synthetic polymer films (polyester films such as polyethylene terephthalate, cellulose triacetate, cellulose nitrate, etc.). Polyamide film, polycarbonate film,
Polystyrene films, vinyl chloride resins, etc.), metal plates such as aluminum, iron, etc. can be used as long as they can withstand lithographic printing. One or both surfaces of the support may be coated with one or more polymer films or metal thin films. The surface of these supports can be subjected to a surface treatment in order to improve the adhesion to the coating layer.

Particularly preferably used supports are paper coated on both sides or one side with a polyolefin polymer, a polyester film, a polyester film having a hydrophilized surface, an aluminum plate having been subjected to a surface treatment, and the like.
These supports may contain pigments for preventing halation and solid fine particles for improving the surface properties. Further, the support may be light-transmissive so that backside exposure is possible.

The developing solution used in the present invention includes an alkaline substance such as sodium hydroxide, potassium hydroxide,
Lithium hydroxide, tribasic sodium phosphate, etc., sulfites as preservatives, silver halide solvents such as thiosulfate,
Thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines and the like, thickeners such as hydroxyethylcellulose, carboxymethylcellulose and the like, antifoggants,
For example, potassium bromide, a compound described in JP-A-47-26201, a developing agent such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, a developing modifier,
For example, it may contain a polyoxyalkylene compound, an onium compound, or the like, or may be an activator-type developing solution containing no developer. Further, as the developing solution, a compound or the like described in U.S. Pat. No. 3,776,728 which improves the ink running of the surface silver layer can be used.

The surface silver layer after development of the lithographic printing plate of the present invention can be converted to ink receptivity or enhanced in receptivity with any known surface treating agent. Examples of such a processing solution include JP-B-48-29723 and U.S. Pat.
21, 559 and the like. The printing method, the desensitizing solution, the humidifying solution, and the like to be used can be a commonly known method.

[0036]

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

Example 1 A matting layer (back coating layer) containing silica particles having an average particle size of 5 μm was provided on one side of 135 g / m ² double-sided polyethylene-coated paper, and the opposite side was subjected to corona discharge machining, followed by carbon black. And an underlayer containing silica powder having an average particle size of 7 μm (gelatin 3.5 g / m ² ) and an ortho-sensitized high-sensitivity chloride having 0.1 g / m ² of 1-phenyl-3-pyrazolidone thereon Two layers were simultaneously coated so that the silver emulsion (containing 0.8 g / m ^{2 of} gelatin) became 1.0 g / m ² as silver nitrate. As a hardening agent, 2,4-dichloro-
The undercoat layer contained 170 mg / m ^{2 of} 6-hydroxy-S-triazine sodium, and the emulsion layer contained 80 mg / m ² of N-methylolethylene urea. After coating and drying, 5
The mixture was heated at 0 ° C. for 2 days to prepare a photosensitive silver halide photographic material.

Next, the physical development nucleus layer applied on the photosensitive silver halide photographic material will be described. First,
The types of the polymer latex (L-1 to 4) and the polymer (P-1 to 6) used in the nucleus solution are described. The minimum film forming temperature of the polymer latex is measured by the above-mentioned temperature gradient plate method. L-1: Polyrac 518 (minimum film forming temperature 0 ° C. or less) manufactured by Mitsui Chemicals, Inc. (styrene butadiene copolymer) L-2: Bonron S485 (minimum film forming temperature 0 ° C. or less) manufactured by Mitsui Chemicals, Inc. Acrylic copolymer) L-3: Bonron S415 of the present invention Mitsui Chemicals Co., Ltd. (minimum film formation temperature of 10 ° C. or less) (acrylic copolymer) L-4: Polyrac 750 of the present invention Mitsui Chemicals Co., Ltd. (minimum film formation temperature of 15) C or lower) (styrene butadiene copolymer) P-1: copolymer of acrylamide (97) and methylsulfone (3) substituted with guanylthioureas (average molecular weight 120,000) P-2: acrylamide (97) Imidazole (3)
(Average molecular weight 100,000) P-3: polyacrylamide (average molecular weight 100,000) P-4: pullulan P-5: polysaccharide P-6: PVA polyvinyl alcohol (average molecular weight 15,000)

Next, a coating solution was prepared by changing the types of the physical development nuclei having the following formulation and the above-mentioned polymers of the present invention, and then coated and dried to prepare a lithographic printing plate. These lithographic printing plates were separated into a fresh product (leave at 25 ° C. for 5 days) and a forcedly heated product (leave at 50 ° C. and a relative humidity of 80% for 5 days) to conduct a storage stability test.

Preparation of palladium sulfide sol Liquid A 5 g of palladium chloride 40 ml of hydrochloric acid 1000 ml of distilled water 1000 ml of liquid B 8.6 g of sodium sulfide Distilled water 1000 ml The liquid A and the liquid B were mixed with stirring, and after 30 minutes, the ion exchange resin (IR- 120E, IRA-400) to obtain a palladium sulfide sol. Preparation of Physical Development Nucleus Solution Containing Polymer of the Present Invention Palladium Sulfide Sol 100 ml Hydroquinone 100 g 1-phenyl-3-pyridolidone 10 g Polymer latex (L-1-4) 0.5 g Polymer (P-1-6) 5 g 10% Saponin (surfactant) 2 ml water was added to make the total volume 2000 ml, and the mixture was slide-coated so as to be coated at 20 ml / m ² .

These lithographic printing plates were prepared using Mitsubishi Paper Mills CP
Exposure and development were performed using -414S. Development was carried out at 30 ° C. for 15 seconds with the following transfer developer. For stabilization, the mixture was treated with the following stabilizing solution at 28 ° C. for 10 seconds and dried.

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

<Stabilizing solution> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% solution) 5 ml Ethylene glycol 5 ml Add water to make 1 liter. The lithographic printing plate created by the above operation is mounted on an offset printing machine, and the following desensitizing solution is applied to the plate surface,
Printing was performed using the following humidifying solution.

<Desensitizing solution> Water 800 ml Citric acid 1 g Sodium citrate 3.5 g Ethylene glycol 100 ml 2 Mercapto-5-n-heptyl-1,3,4-oxathiazole 1 g

<Humidifier> o-Phosphoric acid 10 g Nickel nitrate 5 g Sodium nitrite 5 g Ethylene glycol 100 g Colloidal silica (20% solution) 28 g Water is added to make 2 liters.

The printing machine is an Abdick 350CD
(The trademark of an offset printing machine manufactured by AB Dick Co., Ltd.), and the number of prints when the image cannot be printed due to image fouling due to background stain on the non-image area and missing silver image area. It was determined based on the evaluation criteria. A 20,000 sheets or more B 10,000 to 20,000 sheets C 5,000 to 10,000 sheets D 2,000 to 5,000 sheets E 2,000 sheets or less Printing results are shown in Table 1.

On the other hand, in order to check the water retention (ground stain) of the non-image area, Dai-Nippon Ink F Gloss Purple 68S was used as the ink.
AB Dick 350 using water as a humidifier
The number of prints when a background stain was generated on the CD and the print could not be used was determined according to the following evaluation criteria. A 3000 sheets or more B 1000-3000 sheets C 500-1000 sheets D 100-500 sheets E 100 sheets or less The printing results are shown in Table 1.

[0048]

[Table 1]

Further, as a comparative example, in the lithographic printing plate of Example 1 (Comparative C), a polymer latex (Polylac 518) was used as a solid component in an undercoating layer of 1.4 g / m ² (Comparative Example L), and in an emulsion layer. A sample was prepared by adding 0.2 g / m ² (Comparative Example M). These lithographic printing plates were tested as in Example 1. Table 2 shows the results.

L: Comparative Example Polylac 518 in the undercoat layer M: Comparative Example Polylac 518 in the emulsion

[0051]

[Table 2]

From the above results, it was confirmed that a lithographic printing plate having excellent water retention with particularly long-term stability can be obtained by including the water-dispersible fine particle polymer of the present invention in the physical development nucleus layer. .

[0053]

According to the present invention, it is possible to improve the printing characteristics of a lithographic printing plate to which the silver complex salt diffusion transfer method is applied, and particularly to improve the storability.

Claims (2)

[Claims] In a lithographic printing material to which a silver complex salt diffusion transfer method having at least a silver halide emulsion layer and a physical development nucleus layer on a support is used, the physical development nucleus layer has an acrylamide homopolymer or copolymer. A lithographic printing material characterized by containing a polymer and a water-dispersible fine particle polymer. 2. The lithographic printing material according to claim 1, wherein a minimum film forming temperature of the water-dispersible fine particle polymer is 0 ° C. or lower.