JPH09304934A - Preparation method for planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the printing performance, especially the printing stability by processing a photographic material in the presence of a hydrazine compound. SOLUTION: In a preparation method for a planographic printing plate, comprising the steps of exposing a photographic material having a silver halide emulsion layer, developing the same, and then selectively making the undeveloped silver halide image part or the developed metal silver image part lipophilic to be ink-acceptable, the photographic material is processed in the presence of a hydrazine compound. In the case of containing the hydrazine compound in the photographic material, it is preferable to contain it in the silver halide emulsion layer, but it is also all right to contain it in a hydrophilic colloid layer adjacent to the silver halide emulsion layer. The content of the hydrazine compound in the layer depends on the characteristic of the used silver halide emulsion, the chemical structure of a compound and developing conditions, so that suitable content varies over a wide range, but the range about 1×10<-6> -1×10<-2> mol per silver one mol in the silver halide emulsion is useful in practically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of preparing a printing plate having high printing durability in a method of preparing a printing plate which applies a photographically formed silver halide image as lipophilicity and ink receptivity. .

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2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image-forming portion that accepts oil-based ink and an oil-repellent non-image-forming portion that does not accept ink. Generally, the non-image-forming portion receives water. It is composed of hydrophilic parts.

Therefore, in the ordinary lithographic printing, both water and ink are supplied to the plate surface, the image area selectively receives the coloring ink and the non-image area receives water, and the ink on the image area is, for example, paper. It is made by transferring to a substrate such as.
Therefore, in order to obtain a good printed matter, the difference between the lipophilicity and hydrophilicity of the surface of the image area and the background non-image area is sufficiently large, and when water and ink are applied, the image area has a sufficient amount of ink. It is necessary that the non-image area does not accept ink at all.

Photographic materials consisting of silver halide emulsions having high sensitivity and being spectrally sensitized are suitable for automatic production of printing plates, and several methods are already known. The methods for making a lithographic printing plate using a photographic gelatin / silver halide emulsion are roughly classified into the following methods.

(1) A method utilizing tanning development,
A method in which a hydrophilic gelatin silver halide emulsion is subjected to tanning development to harden the gelatin in the developing area to make it lipophilic and ink-receptive (US Pat. No. 3,146,104).

(2) A printing plate which applies the silver diffusion transfer method to make the formed surface metallic silver pattern lipophilic and uses it as ink acceptability (US Pat. Nos. 3,721,559, 3,490,905, Japanese Patent Publication No. 48-30562). J.Phot.Sci, 8,26〜32 (1960) A Rott & L.
DeHaes)

(3) By applying etching bleach, the developed silver image portion or the silver image portion formed by transfer development is treated with a bleaching solution, and at the same time, the gelatin in the silver image portion is destroyed to remove the lipophilic surface. A method of making a lithographic printing plate by exposing it. (U.S. Pat.Nos. 3,385,701 and 3,814,6
(No. 03, Japanese Patent Publication No. 44-27242)

(4) A method of selectively oleophobicizing an undeveloped silver halide image portion of a silver halide emulsion layer to make it ink-receptive (US Pat. Nos. 3,454,398, 3,764,323 and 3,099,20)
No. 9, Japanese Patent Publication No. 57-3939, JP-A No. 4-12353, etc.).

The lithographic printing plate of the present invention belongs to the above category (4).

Therefore, in the processing step of the lithographic printing plate according to the principle of (4) above, after image exposure, development processing (not including diffusion transfer development) is performed with a developing solution for silver halide photographic light-sensitive material, and thereafter, , A processing solution containing an organic compound which reacts with a silver halide solvent and a silver ion to form a sparingly soluble compound in order to make an undeveloped silver halide (undeveloped silver halide) ink-receptive It is treated as an oil-sensitizing treatment liquid), and if necessary, stabilization treatment is performed, followed by washing and drying.

Conventionally, the planographic printing plate produced by the above method (4) has a problem of poor printing durability. That is, ink-receptive parts, especially fine lines and minute dots,
There is a problem that when a large amount of prints are made, the prints gradually become thin and the printed matter changes depending on the number of printed sheets. Due to this problem, the lithographic printing plate of this system has not been put to practical use.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to improve printing durability in processing a lithographic printing plate prepared by the above method (4).

[0013]

SUMMARY OF THE INVENTION The above object of the present invention is to provide a photographic material having a silver halide emulsion layer after exposure and development,
In a method for producing a lithographic printing plate which selectively makes an undeveloped silver halide image portion or a developed metallic silver image portion lipophilic and ink-receptive, the photographic material is subjected to development treatment in the presence of a hydrazine compound. It was achieved by a method of making a lithographic printing plate characterized by.

As a result of extensive studies, the present inventor has found that by developing in the presence of a hydrazine compound, printability,
In particular, they have found that the printing durability is remarkably improved.

The hydrazine compound is a general photographic light-sensitive material,
In particular, it is known that a plate-making film can obtain a high contrast property. However, in the planographic printing plate targeted by the present invention, it is a novel finding that a printing plate having good printing durability can be obtained, which is completely unexpected.

The hydrazine compound used in the present invention will be described in more detail below.

The hydrazine derivative used in the present invention includes hydrazine sulfate, hydrazine hydrochloride and the like, and US Pat. Nos. 4,224,401 and 4,243,734,
No. 4,272,614, No. 4,385,108
No. 4,169,929, 4,323,64
No. 3 and JP-A-59-106244, 61-2.
No. 67759, No. 61-230145, No. 62-27
No. 0953, No. 62-178246, No. 62-180
No. 361, No. 62-275247, No. 63-2533
57, 63-265239, JP-A-2-2713.
No. 51, No. 2-277048, Japanese Patent Application No. 6-1432
There are hydrazine derivatives described in the specification such as No. 63 and the like, which can be used in the present invention. Typical examples of the hydrazine derivative are shown below, but the scope of the present invention is not limited to these.

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[Chemical formula 26]

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In the present invention, when the human collagen compound is contained in the photographic material, it is preferably contained in the silver halide emulsion layer, but may be contained in the hydrophilic colloid layer adjacent to the silver halide emulsion layer. . Such a layer is a layer having any function, such as a subbing layer, an intermediate layer, a filter layer, a protective layer, or an antihalation layer, as long as it does not prevent the hydrazine compound from diffusing into the silver halide grains. Good. Since the content of the hydrazine compound in the layer varies depending on the characteristics of the silver halide emulsion used, the chemical structure of the compound and the development conditions, the appropriate content can vary over a wide range, but in the silver halide emulsion A range of about 1 × 10 ^-6 to 1 × 10 ^-2 mol per mol of silver is practically useful.

Further, in the present invention, the hydrazine compound may be added to the developing solution. In this case, in the developer, 1 × 10 ^-6 to 1 × 10 ^-3 mol / l is preferably 1 × 10 ^{-5 to} 5 × 10 ^-4
More preferred is mol / l.

Further, JP-A-61-267759, JP-A-60-179734 and US Pat. No. 5,104,769.
No. 4,798,780, JP-A-1-179939.
U.S. Pat. No. 4,998,6.
04, 4,994, 365, JP-A-6-3139.
37, the amino compound described in 7-39139, etc.,
The phosphonium compound may be contained in the photographic material or the developing solution.

As the developing agent of the developer used in the present invention, hydroquinone, chlorohydroquinone, bromohydroquinone, isopropylhydroquinone, methylhydroquinone, 2,3-dichlorohydroquinone, 2,5-
Examples include dichlorohydroquinone, 2,3-dibromohydroquinone, 2,5-dimethylhydroquinone and hydroquinone monosulfonate.

In the present invention, in addition to the above developing agent, 1-phenyl-3-pyrazolidone or a derivative thereof, or a developing agent of p-aminophenol type or the like can be added. Specific examples include 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone, 1-phenyl-5-methyl. -3-Pyrazolidone, 1-p-aminophenyl-4,4-dimethyl-3-
Pyrazolidone, 1-p-tolyl-4,4-dimethyl-3
-Such as pyrazolidone. As the p-aminophenol-based developing agent used in the present invention, N-methyl-p-aminophenol, N- (β-hydroxyethyl) -p-aminophenol, N- (4-hydroxyphenyl) glycine, 2-methyl- There are p-aminophenol, p-benzylaminophenol, etc., among which N-methyl-p
-Aminophenol is preferred.

The developing agent is usually 0.03 mol / L to 0.8.
It is preferably used in an amount of mol / L. When a combination of dihydroxybenzenes and 1-phenyl-3-pyrazolidones or p-aminophenols is used, the former is 0.1 mol / L to 0.5 mol / L and the latter is 0.0 mol / L.
It is preferably used in an amount of 1 to 0.1 mol / L or less.

Examples of the sulfite preservative used in the present invention include sodium sulfite, potassium sulfite, sodium bisulfite, potassium metabisulfite, and formaldehyde sodium bisulfite. The amount used is not particularly limited, but is preferably 0.05 mol / L to 1.0 mol / L
Used in the range.

The developer may contain a buffering agent, an alkaline agent, a solubilizing agent, a pH adjusting agent, a development accelerator, a surfactant, a hardener and the like.

The developing solution may further contain an antifoggant and a chelating agent.

Additives used in addition to the above components include development inhibitors such as sodium bromide and potassium iodide, ethylene glycol, diethylene glycol, triethylene glycol, dimethylformamide, methyl cellosolve, hexylene glycol, ethanol, methanol. Such an organic solvent may be contained, and if necessary, a toning agent, a defoaming agent, a water softening agent and the like may be contained.

The pH value of the developer thus adjusted is selected to an extent sufficient to give the desired density and contrast, but it is preferably in the range of about 8-12.

As an automatic processor which can be used in the processing of the present invention, L manufactured by Dainippon Screen Mfg. Co., Ltd.
D281Q, LD360, LD381, LD480Q,
FG680A, FG950 manufactured by Fuji Photo Film Co., Ltd.
A, FG710A, etc., but the type of automatic processor is not limited. Further, an automatic developing machine used for processing a lithographic printing plate utilizing the silver complex salt diffusion transfer method can also be used for the processing.

The development processing temperature and time of the light-sensitive material are interrelated and determined in relation to the total processing time, generally 10 seconds to 3 minutes at about 20 to 50 ° C., but in the case of high speed rapid processing. Is about 30 to 50 ° C. and 10 to 40 seconds.

The oil-sensitizing treatment solution used in the present invention has a wide range of combinations of organic compounds and silver halide solvents that make the surface of the silver halide image portion lipophilic, as described in detail in JP-B-57-3939. However, particularly preferred silver halide solvents include sodium iodide, potassium iodide,
Iodide such as ammonium iodide, sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, thiosulfate, potassium thiocyanate, sodium thiocyanate, thiocyanate such as ammonium thiocyanate,
Sulfite salts such as potassium sulfite, sodium sulfite, sodium hydrogen sulfite and potassium hydrogen sulfite are used.

Examples of the organic compound to be made lipophilic include those described in JP-B-57-3939. Preferred are those represented by the following chemical formulas 60 and 61.

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[Chemical formula 61]

In the formula, R is hydrogen, an alkyl machine having 12 or less carbon atoms, an aryl group, an aralkyl group, and Z is a remaining atom of a bond necessary to form a 5- to 6-membered heterocycle with N and C in the formula. Represents a group.

Specific examples of the 5- or 6-membered ring include imidazole, imidazoline, thiazole, thiazoline, oxazoline, oxazole, pyrazoline, triazole, thiadiazole, oxadiazole, tetrazole, pyridine, pyrimidine, pyridazine, pyrazine and triazine. Yes, these rings may be two or more condensed rings. Typical examples of the compounds represented by Chemical formulas 60 and 61 are 2-mercapto-5-heptyl-1,3,4-oxadiazole and 2-mercapto-5-phenyl-1,3. 4-oxadiazole, 2-mercapto-4-phenylimidazole, 2-mercapto-1-benzylimidazole, 2-
Mercaptobenzimidazole, 2-mercapto-1-
Ethyl-benzimidazole, 2-mercapto-1-butyl-benzimidazole, 1,3-diethyl-benzimidazoline-2-thione, 2,2'-dimethylcapto-1,1'-decamethylene-diimidazoline, 2-mercapto -4-Phenylthiazole, 2-mercaptonaphthothiazole and the like.

The amount of the silver halide solvent effective for the purpose of the present invention is not uniform depending on the composition of the silver halide emulsion, but is within the range of 10 ^-2 mol / liter to 1 mol / liter. The amount of the organic compound for lipophilicity is not necessarily uniform for each compound, but it is used at a concentration of 10 ^-3 mol / liter to 10 ^-1 mol / liter.

The sensitizing solution containing an organic compound for lipophilicity and a silver halide solvent contains methanol, ethanol, propanol, ethylene glycol, diethylene glycol or the like in order to improve the solubility of the organic compound. It may contain a water-miscible organic solvent.

Further, the sensitizing solution is preferably buffered at a pH of 4-8. The pH buffering agent can be selected from acids having a pKa value of 4 to 8 such as acetic acid, citric acid and phosphoric acid, and salts thereof. Further, the conversion liquid may contain various other components. For example, water-soluble polymers such as hydroxyethyl cellulose and a surface hydrophilizing agent such as colloidal silica can be included. Further, the surfactant described in JP-A-4-12353 can be used for the purpose of preventing unevenness in the oil-sensitizing treatment.

In the present invention, the portion used for ink receptivity is undeveloped silver halide or the developed metallic silver image portion. When undeveloped silver halide is converted into an ink receiving part, it can be obtained by subjecting it to a post-development sensitization treatment as described above. When the developed metallic silver image area is converted into an ink receiving area, it is fixed after development, or after the one-bath development fixing treatment, the remaining silver image is oxidized to rehalogenate and subjected to an oil-sensitizing treatment. can get.

When an undeveloped silver halide is converted into an ink receiving part to prepare a printing plate, a positive type printing plate is used when the silver halide material used is a negative type, and a positive type silver halide light-sensitive material is used when it is a positive type. A negative type printing plate is obtained.

The silver halide of the printing plate used in the present invention is silver chloride, silver chlorobromide, silver bromide and may contain iodide. The binder of the photosensitive material is preferably gelatin.
However, some or all of it may be replaced by other colloidal substances, such as
It may be replaced with albumin, casein, polyvinyl alcohol, polyvinyl alcohol-maleic anhydride ester, polyvinyl alcohol-styrene maleic anhydride ester, alginate, cellulose derivative and the like.

The weight ratio of binder, preferably gelatin, to silver halide and the absolute amount of binder are important factors in determining the quality of the printing plates of the present invention. When the weight of silver halide expressed as silver nitrate is 1, the amount of binder is preferably 0.3 to 3.0. When the ratio of the binder is 0.3 or less, the film strength as an emulsion layer is liable to be lowered and the printing characteristics are likely to be unfavorable. On the other hand, if the proportion of the binder is high, the ink receptivity may be lowered. The silver halide emulsion layer has a silver nitrate amount of 0.6 to 7 g / m ² , and a binder amount of 0.5 to 2.5 g / m ² .
It is preferably applied at m ² .

In the production of the printing plate of the present invention, another important factor is the hardening of the light-sensitive silver halide emulsion layer. It must be fully cured, at least before printing. A hardening agent may be added to the photographic emulsion coating solution in the same manner as in the usual hardening method of a photographic emulsion layer, and it may be hardened by a method such as heat treatment before or after the development and plate making processes. May be. In order to obtain stable hardening properties, it is preferable that a silver halide emulsion containing a curing agent is coated and dried, and then appropriately heated. This heating treatment is a treatment for obtaining a good degree of curing, and is, for example, 80 to 15
The treatment may be performed at 0 ° C for several minutes or tens of minutes, or at 30 to 50 ° C for several days (about 1 to 20 days).

As the curing agent, compounds which are commonly used as curing agents for photographic emulsion layers can be used. For example, formalin, glyoxal, glutaraldehyde, aldehyde-based curing agents such as mucochromic acid, further urea-formalin condensate, melanin-formalin condensate are also effective, and epoxy-based, aziridine-based compounds, active olefins, isocyanates. Compounds known as curing agents for photographic emulsions such as organic curing agents such as system compounds and inorganic polyvalent metal salts such as chromium, aluminum and zirconium can be used alone or in combination.

Further, the silver halide photographic emulsion layer has a grain size of about 2 to prevent abrasion of colloid during printing.
It is preferable to contain fine particles having a diameter of 10 μ, and silica, clay, talc, sequrite, rice starch, etc. can be used, but silica is particularly preferable.

Silica is added to the silver halide emulsion in an amount of 0.01 to 1 g per m ² . If the concentration of silica particles becomes excessively high, it will be difficult to increase the concentration of ink during printing, or a scumming phenomenon will occur.

For the purpose of improving the photographic sharpness, and finally the resolution and sharpness of the printed matter, it is preferable to apply a so-called antireflection dye or pigment. These should be applied in the silver halide emulsion layer or in the so-called antireflection layer between the support and the silver halide emulsion layer, or in the layer opposite to the silver halide emulsion layer with the support in between. The purpose is achieved by.

Further, a light-reflecting pigment such as titanium oxide,
The object can also be achieved by using a white pigment or a yellow organic pigment such as barium sulfate or magnesium oxide in combination with a light absorbing dye or pigment.

The most preferable embodiment of the photographic light-sensitive material in the method for producing a printing plate of the present invention has a colloid subbing layer having an antireflection dye or pigment on a support, and a silver halide emulsion is provided on this subbing layer. It has a layer.

The colloidal undercoat layer containing the antireflection dye or pigment is preferably made of gelatin and contains the above-mentioned fine particles having a particle size of 2 to 10 μm. The preferred particulate is silica. The binder gelatin is 0 per m ² .
From 5 g to 2.5 g should be cured as good as a silver halide emulsion layer. Also, silica is applied in an amount of 0.1 to ²⁰ g per m ² .

The subbing layer containing fine particles as in the present construction improves the abrasion property of the colloid during printing,
It has the effect of improving printing durability. In this case, fine particle silica is not always necessary in the emulsion layer.

The support for the silver halide emulsion may be any support commonly used in the art. For example, paper having both sides coated with polyethylene, a resin film, a metal sheet, or the like can be used.

In addition, a surfactant for improving coating properties, a stabilizer for maintaining photographic sensitivity, an antifoggant, a sensitizing dye, a developer, a development accelerator and a photographic emulsion layer are colored. Dyes, pigments and the like can be optionally contained for the purpose.

In the printing plate used in the present invention, a part or all of an organic thiol compound or a thione compound which imparts ink receptivity or other organic heterocyclic compound is preliminarily incorporated in a material having a silver halide emulsion layer. , Can also be added. It may be a layer other than the photosensitive silver halide emulsion layer. Further, these organic compounds may be added after being dissolved in an oil agent and dispersed in the form of fine oil droplets.

[0115]

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

Example 1 (1) Production of lithographic printing plate A gelatin undercoat liquid containing silica particles (average particle size 5 μm) and carbon black was applied onto corona-shaped electrical discharge machined polyethylene-coated paper. Further, formalin and dimethylolurea were added as a colloid layer curing agent. The adhesion amounts of gelatin and silica were 1.2 g and 0.7 g per m ^2, respectively. The reflection density of this layer was 0.9. Subsequently, an ortho-sensitized silver halide emulsion containing formalin and dimethylolurea as a hardening agent for the colloid layer was coated on the undercoat layer.

This emulsion layer has the following constitution. Silver halide composition Chlorobromide (25 mol% of silver bromide) Average grain size of silver halide 0.25μ Silver halide coating amount represented by silver nitrate 3.0g / m ² Gelatin coating amount 1.5g / m ² Silica ( Average particle size 5μ) Coating amount 0.1g / m ²

This photographic material containing a light-sensitive silver halide emulsion was heated at 40 ° C. for 3 days, and then an aqueous solution containing the water-soluble synthetic high molecular substance having the following formulation (used as an overcoat liquid) was adjusted to 15 ml / m ^2. A lithographic printing plate was prepared by coating and heating and drying. This is referred to as printing plate A.

On the other hand, a lithographic printing plate was prepared in the same process using an emulsion prepared by adding 1 × 10 ⁻⁶ mol of rhodium salt to 1 mol of silver halide in the above emulsion grains. This is referred to as printing plate B.

Topcoat Water 800 ml Sodium polyacrylate (1% aqueous solution) 200 ml 1% H ₃ PO ₄ 200 ml 10% saponin 15 ml 10% glyoxal 20 ml Add water and adjust to 1500 ml.

(2) Processing method The planographic printing plates A and B were image-exposed with a plate-making camera, and a developing solution and a sensitizing solution having the following formulations were respectively provided in the automatic developing machine LD22.
1 (made by Dainippon Screen) 1st tank and 2nd tank,
A development process was performed at 35 ° C. for 30 seconds, and an oil-sensitizing process was performed at 30 ° C. for 30 seconds. These are designated as Comparative Example 1 and Comparative Example 2.

Developer A EDTA.2Na 1 g Sodium hydroxide 48 g Potassium sulfite 108 g Hydroquinone 55 g N-methyl-p-aminophenol 1/2 sulfate 0.8 g Potassium hydroquinone monosulfonate 40 g 5-Methylbenzotriazole 0.2 g Odor Potassium iodide 4 g Diethylene glycol 25 g Nn-butyldiethanolamine 12 g KOH was adjusted to pH 11.80, and water was added to make 1 liter.

Sensitizing Treatment Water 600 ml Diethylene glycol 50 g NaOH 4 g 2-Mercapto-5-heptyl-1,3,4-oxadiazole 3 g Phosphoric acid 2 potassium 25 g Phosphoric acid (85%) 4 g KI 25 g Water was added. Set to 1L.

Chemical formula 2, Chemical formula 3, Chemical formula 22, Chemical formula 31,
Printing plates prepared by treating the printing plate A in the same manner as in Comparative Example 1 by adding 0.15 g of the hydrazine compound represented by Chemical formula 44 or Chemical formula 49 per liter are designated as Inventions 1 to 6.

The lithographic printing plate prepared by the above operation was mounted on an offset printing machine, and printing was performed under the following conditions using the following dampening liquid.

Wetting liquid o-phosphoric acid 10 g nickel nitrate 5 g sodium nitrite 5 g ethylene glycol 100 g colloidal silica (20% liquid) 28 g Water is added to make 1 liter.

The printing machine is an AB Dick 350CD (ABDick
(Trademark of offset printing machine manufactured by the company) was used, and the number of printed sheets when the image was skipped due to the background stain of the non-image area and the missing of the silver image area, and it was judged by the following evaluation criteria . A 30000-50000 sheets B 20000-30000 sheets C 10000-20000 sheets D 5000-100000 sheets E 2000-5000 sheets

Further, in order to see the gradation of the silver halide emulsion used in the planographic printing plates A and B, only the emulsion layer was coated on a polyethylene terephthalate film, and the second tank of the automatic developing machine LD221 was set to C.
Replace with F901 (trade name (manufactured by Mitsubishi Paper Mills)),
The wedge was exposed under the same conditions as those for producing the printing plate, and development and fixing were performed to measure gamma. Gamma was expressed as the average gradient from 1.0 to 2.5 transmission density. The results are shown in Table 1.

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[Table 1]

As can be seen from Table 1, the printing plate of Comparative Example 1 had poor printing durability, and the printing plate of Comparative Example 2 had the same gamma value as that of the present invention, but the printing durability was hardly improved. On the other hand, with the printing plate of the present invention, it was possible to obtain a printed matter having good printing durability.

Example 2 In the emulsion layer of the printing plate A of Example 1, 0.4 × 10 ⁻³ mol of hydrazine added in the developing solution was added per mol of silver. A light-sensitive material containing no hydrazine was designated as Comparative Example 3, and a light-sensitive material containing a hydrazine compound was designated as Inventions 7 to 12. The same topcoat liquid as in Example 1 was applied to this and dried by heating. These light-sensitive materials were developed with the developer A of Example 1 containing no hydrazine, and processed using the oil-sensitizing solution under the same conditions as in Example 1. The printing conditions and the evaluation method were in accordance with Example 1. The results are shown in Table 2.

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[Table 2]

As can be seen from Table 2, the printing plate of Comparative Example 3 had poor printing endurance, whereas the printing plate of the present invention could produce a printed product having good printing endurance.

Example 3 4 × 10 ⁻⁷ mol of iridium (III) hexachloride per mol of silver
97 mol% AgBr in the presence of potassium and ammonia,
A cubic iodobromide emulsion containing 3 mol% AgI and having an average grain size of 0.25 μ was prepared by the double jet method. This emulsion was desalted by the flocculation method, and then 40 g of inert gelatin was added per mol of silver. This emulsion was kept at 50 ° C.
5'-Dichloro-9-ethyl-3,3'-bis (4-sulfobutyl) oxacarbocyanine was added, and the mixture was allowed to stand for 20 minutes and then cooled. Using this emulsion, the compounds of chemical formula 5, chemical formula 44, chemical formula 45, chemical formula 57, and chemical formula 58 are added to 0.4 mol per mol of silver.
× 10 ^-3 mol added, 5-methylbenzothiazole,
2-Methyl-4-hydroxy-1,3,3a, 7-tetraazaindene was added. Further, 30 mg / m ^{2 of the following} chemical formula 62 was added to each sample to prepare 1,3-divinylsulfonyl-2-
Propanol was added, and 0.7 g of the silica of Example 1 was further added per m ² , and the undercoat layer used in Example 1 was coated on the polyethylene terephthalate film, and the amount of silver was 1.
The amount of coating was 5 g / m ² and the amount of gelatin was 1.0 g / m ² . This was hardened with the same hardening agent as in Example 1, and the topcoat liquid of Example 1 was applied. Of these light-sensitive materials, a material to which no hydrazine derivative was added was designated as Comparative Example 4,
Compounds represented by Chemical formula 3, Chemical formula 43, Chemical formula 44, Chemical formula 57, and Chemical formula 58 are referred to as present inventions 13 to 17.

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The coated sample was exposed to tungsten light at 3200 ° K. through an optical wedge and a 150-line gray contact screen, and the same automatic as in Example 1 was used using the developer having the following formulation and the sensitizing solution of Example 1. Processing was carried out in the developing machine. The printing durability of these printing plates was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Developer B Water 600 ml Sodium sulfite 49 g Potassium carbonate 30 g Hydroquinone 17 g 1-Phenyl-4-hydroxymethyl-4-methyl-3-pyrazolidone 0.7 g Benzotriazole 0.2 g KBr 1.5 g Ethylenediaminetetraacetic acid disodium salt After 1 g of water was added to make 1 L, the pH was adjusted to 10.50 (25 ° C.) with KOH.

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[Table 3]

As can be seen from Table 3, the printing plate of Comparative Example 4 has poor printing durability, whereas the printing plate of the present invention provides a printed product having good printing durability and improved stain resistance. I was able to.

[0140]

According to the present invention, after the silver halide emulsion layer is exposed and developed, the undeveloped silver halide image area or the developed silver halide image area is selectively made lipophilic to make it ink receptive. In the planographic printing plate described above, a printing plate having good printing durability can be obtained by performing development processing in the presence of a hydrazine compound.

Claims (1)

[Claims] 1. A lithographic plate which is exposed to a photographic material having a silver halide emulsion layer and, after development, selectively oleophilizes an undeveloped silver halide image portion or a developed metal silver image portion to make the ink receptive. A method of preparing a lithographic printing plate, which comprises developing the photographic material in the presence of a hydrazine compound.