JPH02287357A - Lithographic printing plate for scanning exposure - Google Patents

Abstract

PURPOSE:To improve a preservable property and to obtain a high sensitivity and high printing resistance by incorporating specific silver halide particles and a water soluble high-polymer having a carboxyl group and a specific average mol.wt. into a silver halide emulsion layer. CONSTITUTION:This planographic printing plate has the silver halide emulsion layer contg. a sensitizing dye having the max. spectral sensitivity in a wave length region longer than 70nm and a surface 3 physical development nucleus layer on a base and is developed by a developing soln. for silver complex salt diffusion transfer after scanning ray exposing for a short period of time with a high illuminance. This silver halide emulsion is such silver halide emulsion, >=90% of the total particle number of which forms a (100) face, >=90% of the total particle number is within + or -30% of the average particle size and the aver age particle of the silver halide particles is >=0.3mu.The emulsion layer contains the water soluble high polymer of <=20,000 average mol. wt. having the carboxyl group. The high sensitivity to semiconductor laser light of low output and hard contrast characteristics are obtd. in this way and the excellent preservable property is obtd. The high printing resistance is obtd. and scumming is eliminat ed in the scanning exposing.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a lithographic printing plate for scanning exposure using a silver complex diffusion transfer method suitable for using laser light, particularly semiconductor laser light, as a light source.

(B) Prior art and its problems A lithographic printing plate in which a transferred silver image obtained by the silver complex diffusion transfer method can be immediately used for ink receptivity has already been disclosed in Japanese Patent Publications No. 48-30562 and No. 53-2160.
2, Kaishu 54-103104, 1982-9750, etc., and is well known.

According to a typical implementation method of the silver complex diffusion transfer method suitable for the plate-making method of such a lithographic printing plate, a support is provided, a subbing layer that also serves to prevent Halesin carbon dioxide, a silver halide emulsion layer, and a physical development layer are formed on the support. When a photosensitive material comprising a core layer is imagewise exposed and developed, the silver halide on which a latent image has been formed becomes blackened silver in the emulsion layer. At the same time, silver halide on which no t-image has been formed is dissolved by the action of the silver halide lead-forming agent contained in the processing solution and diffused onto the surface of the photosensitive material. The silver complex salt that has been dissolved and diffused is deposited as a silver image on the physical development nuclei in the surface layer by the reducing action of the developing agent. After development and, if necessary, a sensitization treatment to enhance the ink receptivity of the resulting silver image, it is placed in an offset printing press and the ink image is transferred to a printed product.

In recent years, a method has been proposed for making a lithographic printing plate using laser light. For example, U.S. Patent No. 4.501,8
No. 11, JP-A No. 59-71055, JP-A No. 60-7583
No. 8, No. 60-100148, etc., disclose a lithographic printing plate used for a helium-neon laser-1 or a light emitting diode. Also, JP-A-62-103649,
No. 105147-105150, No. 62-1983
No. 113148, No. 139555, No. 13955, No. 62
141561 and the like discloses a lithographic printing plate using a scanner type plate making method using a semiconductor laser.

The advantages of using a semiconductor laser are that it is smaller, cheaper, easier to modulate, and has a longer life than a method using a helium-neon, argon, or other laser light source as a scanner type light source.

However, when using a semiconductor laser as a light source for a lithographic printing plate, several problems and characteristics of the lithographic printing plate must be understood.

Semiconductor lasers include Ga /A s /P;
a/At/As: Ga/As; I
A semiconductor of the system such as n/P: I n /A s is used, and the wavelength of this laser light is generally 700 n
There are many wavelengths longer than m, especially wavelengths longer than 750 nm. Optically, compared to helium-neon and argon light sources, it is difficult to narrow down the light beam, making it difficult to obtain high resolution.

On the other hand, lithographic printing plates are printed using a transferred and deposited silver image through silver complex salt diffusion transfer development, so if semiconductor laser light is used, high resolution cannot be obtained, and the exposure method uses scanning exposure, so Due to exposure factors, the amount of transferred silver decreases, thinning of fine lines, deterioration of resolution, and background smearing occur, making it difficult to obtain a lithographic printing plate of the desired high quality.

Therefore, photographic properties that meet these requirements include not only sufficiently high sensitivity at the wavelength of laser light, but also good storage stability, and the ability to form a high-contrast transferred deposited silver image. All requirements must be met, including the absence of background smudges, the formation of strong transfer deposits of silver that cannot be removed during printing, and the formation of scales.

Silver halide photographic materials containing sensitizing dyes with maximum spectral sensitivity at wavelengths longer than 700 nm are generally known to have poor storage stability. It is described in Japanese Patent Application No. 197737/1987 that by adsorbing a polymer on the surface of a sensitizing dye adsorbed on silver halide, the storage stability is improved by preventing the desorption or decomposition of the dye.

Lithographic printing plates using semiconductor lasers are required to have high sensitivity and high contrast characteristics, which are suitable for scanning exposure, in order to have high printing durability that is not affected by the laser light source.

The inventors' research has shown that these properties are due to the adsorption of the sensitizing dye to silver halide, and that the properties vary significantly depending on the silver halide grain size and crystal habit plane. It was not possible to make more effective use of the storage stability improvement, sensitization, and contrast effects of polymers. Therefore, there is a need for a lithographic printing plate for scanning star exposure that has excellent printing suitability for such scanning exposure.

(C) Purpose of the Invention The purpose of the present invention is to have high sensitivity and high-contrast characteristics for low-output semiconductor laser light, excellent storage stability, high printing durability and no scuffing during scanning exposure. An object of the present invention is to provide a lithographic printing plate for scanning fi exposure using a silver complex salt diffusion transfer method.

(D) Structure of the Invention The above object of the present invention is to provide a lithographic printing system having a silver halide emulsion layer containing a sensitizing dye having maximum spectral sensitivity in a wavelength range longer than 700 nm and a surface physical development nucleus layer on a support. In a lithographic printing plate in which the plate is exposed to high-intensity, short-time scanning lines and then developed with a developer for silver complex diffusion transfer, the halogenated emulsion has 90 or more of the total grains forming (100) planes, and A silver halide emulsion in which 90% or more of the grains are within ±30 inches of the average grain size, the average grain size of the silver halide grains is 0.3 μ or more, and the emulsion layer has a carboxyl group and has an average molecular weight of 20,000 or less. This was achieved using a lithographic printing plate characterized by containing a water-soluble polymer.

The present invention will be further explained in detail below.

More than 90% of the total number of particles used in the present invention is substantially (
The most common method for obtaining silver halide grains with a 100) plane is to simultaneously add a silver nitrate aqueous solution and an alkali halide aqueous solution while keeping the pAg value at a constant value of 8.5 or less during grain formation ( The so-called controlled double jet method).

More preferably, the pAg value is 8.0 or less.

The silver halide emulsion used in the present invention can be silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, etc., and preferably silver halide containing 50 mole or more of silver chloride. It is. The average grain size of these silver halide grains is preferably 0.3 to 0.8μ, more preferably 0.
．． 3 to 0.5μ is good.

Furthermore, 90% or more of the total number of silver halide grains is within ±30% of the average grain size, and the more uniform the grain size, the better.

Regarding the grain crystal habit, 90% or more of the total number of grains are (100) planes.

Further, the crystal structure of the silver halide grains may be similar up to the inside, or may have a layered structure with different inside and outside, or may have a converged glass structure. Further, it may be of a type in which a latent image is mainly formed on the surface, or a type in which an internal latent image is formed inside the particle.

When forming the silver halide grains, a silver halide solvent for controlling the growth of the grains, or a compound adsorbed to the grain surfaces to control the crystal habit, etc. can be used during the grain formation. Also, at any time during the production of silver halide emulsions, compounds of metals belonging to Group 1 of the periodic table,
For example, by using salts such as cobalt, nickel, rhodium, palladium, iridium, and platinum, direct plate making for scanning exposure with particularly high sensitivity, high sharpness, and excellent reciprocity failure can be obtained. 1
It ranges from 10-8 to 10-s mole per mole.

The polymer used in the present invention is characterized by carboxyl groups (
It is a water-soluble polymer with a low molecular weight, that is, a number average molecular weight of 20,000 or less.

Such water-soluble polymers include olefinically unsaturated compounds containing carboxyl groups as monomer units, such as acrylic acid, methacrylic acid, turicic acid, maleic acid,
7 Maric acid, itaconic acid.

It can be a homopolymer of citraconic acid or the like, or a copolymer of an olefinically unsaturated compound containing a carboxyl group as a monomer unit and a vinyl monomer copolymerizable therewith.

Examples of the vinyl monomer for obtaining the copolymer used in the present invention include styrene, styrene substituted with alkyl such as methyl and ethyl, styrene substituted with alkoxy such as methoxy and ethoxy, styrene derivatives such as styrene substituted with halogen such as chlor, Ethylenically unsaturated monoolefins such as ethylene, fluoropylene, butylene, and imbutylene; vinyl halides such as vinyl chloride, vinylidene chloride, and vinyl bromide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl penzoate, and vinyl butyrate. kind,
Methyl, ethyl, propyl, inbutyl, n-budel,
Alkyl esters of acrylic acid or methacrylic acid such as n-octyl and 2-ethylhexyl, derivatives of acrylic rR1 or methacrylic acid such as acrylonitrile, methacrylonitrile, and acrylamide, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. Examples include vinyl ethers, vinyl compounds such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopronyl ketone, N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, and N-vinyl pyrrolidone, and vinyl naphthalenes. The copolymer component may be a different type of olefinically unsaturated compound containing a carboxyl group.

The amount of olefinically unsaturated compounds containing carboxyl groups in the copolymer is about 10 weight or more, preferably about 20 weight or more. This carboxyl group may be a salt of sodium, potassium, ammonium, etc.
It may be an acid anhydride (for example, maleic anhydride).

The water-soluble polymer used in the present invention has a number average molecular weight (M
n) is 20,000 or less, especially about 1.00
A range of 0 to about 10,000 is preferred.

The water-soluble polymer used in the present invention can be easily produced by known production methods such as solution polymerization, and can also be obtained as a commercially available product.

A specific example is shown below. In addition, the polymerization ratio is shown in weight%.

0ONH4 0OH H3 ■ [15) Hg Mn: 4500 CH2COONa Hg Mn: l Q Q Q H2C-CH2 H2 The water-soluble polymer used in the present invention is halogenated @ about 0.2 to about 100 per mole? , preferably about 1 to about 5
It is preferable to add within the range of. The addition time may be any time before coating the silver halide emulsion. Since the water-soluble polymer inhibits diffusion transfer development seen in high molecular weight polymers such as gelatin, it is not necessary to reduce the amount of gelatin in the silver halide emulsion, but in some cases, the amount of gelatin may be reduced. It's okay.

The sensitizing dye used in the present invention and having maximum spectral sensitivity in a wavelength region longer than 700 nm is disclosed in, for example, US Patent Box 2.
No. 095,854, No. 2.095,856, No. 2
, 955,939, 3.482,978, 3,552,974, 3,573,921, 3,582.344, ! Ha,s 23.8 g
It can be the one described in Specification No. 1 etc.

Preferably, for example, dyes represented by the following general formulas (1) to (IV) are used.

(Left space below) In general formula (I) ~ (It/), Z + and a:
Zl (c) may be the same or different, and each represents a group of eight atoms forming a 5-membered or 6-membered nitrogen-containing heterocycle. R1 and R2 may be the same or different and each represents an alkyl group or an alkenyl group. R5 represents an alkyl group, an alkenyl group, or an aryl group. R4 to RIQ may be the same or different, and each represents a hydrogen atom, a 710gen atom, an alkyl group,
Represents an aryl group or an alkoxy group. However, 几6 and fL
y or R8 and 几9 can also be linked to each other to form a 5- or 6-membered negative ring. R11 and R12 may be the same or different, each represents an alkyl group or an aryl group, and Rj1 and R12 may be linked to each other to form a 5-membered or 6M ring. 6Y is a sulfur atom,
Arsenic atom, 〉NR+i (Rls is an alkyl group).

X represents an acid anion. t, m, n, p and q each represent 1 or 2.

Specific examples of Zl and Zl include thiazole, benzothiazole, n7) (1,2-d) thiazole, n7) C
2,1-d) Thiazole, naphtho1: 2.3-d) Thiazole, selenazole, benzoselenazole, naphtho1)
[:2,1-d) selenazole, naphtho[:1
．． 2-di selenazole, oxazole, benzoxazole, naphthoC1,2-d) oxazole, naphtho [
2,1-d:l oxazole, naphtho[2°3-d]oxazole, 2-quinoline, 4-quinoline, 3,3-dialkylindolenine, imidazole, benzimidazole, naph) [1,2-d) imidazole , pyridine and other nitrogen-containing heterocycles. These heterocycles include alkyl groups (e.g., methyl, ethyl, butyl, trifluoromethyl, etc.), aryl groups (e.g., phenyl, tolyl, etc.), hydroxy groups, alkoxy groups (e.g., methoxy, ethoxy, butoxy, etc.), Carboxy group, alkoxycarbonyl group (e.g., methoxycarbonyl, ethoxycarbonyl, etc.), halogen atom (e.g.,
fluorine, chlorine, bromine, iodine), aralkyl groups (e.g.
benzyl, phenethyl, etc.), cyano group, alkenyl group (
For example, it may have one or more substituents such as allyl, etc.).

In R1 and R2, the alkyl group includes lower alkyl groups such as methyl, ethyl, propyl, butyl, hydroxyalkyl groups such as β-hydroxyethyl and γ-hydroxypropyl, β-methoxyethyl, γ-methoxypropyl, etc. Alkoxyalkyl group, β-acetoxyethyl, γ-
Acyloxyalkyl groups such as acetoxypropyl, β-benzoyloxyethyl, carboxyalkyl groups such as carboxymethyl, β-carboxyether, alkoxycarbonylalkyl groups such as methoxycarbonylmethyl, ethoxycarbonylmethyl, β-ethoxycarbonylethyl, β-sulfoethyl , T-sulfopropyl, δ-sulfobutyl and other sulfoalkyl crystals, benzyl, 7-enether, sulfobenzyl and other acyl group rings, and alkenyl groups such as allyl.

Examples of R5 include alkyl groups and alkenyl groups as described above for R1 and R2, and aryl groups such as phenyl, tolyl, methoxyphenyl, chlorophenyl, and naphthyl.

几4 to Rho are a hydrogen atom, a halogen atom, (for example, chlorine, A, iodine, fluorine), an alkyl group as described for R1 and R2, an aryl group, or an alkoxy group having an alkyl as described for R1 and R2. group (i.e. OR1 group)
The 5-membered or 6JA ring formed by R6 and R7 or R8 and R9 may be substituted with a lower alkyl group or the like. R11 and RI2 represent an alkyl group or an aryl group as described for R1 and R2, and R11 and R12 can also be linked to each other to form a 5- or 6-membered ring. Examples of 几13 include the alkyl groups described for R1 and R2.

Examples of the acid anion of It does not exist when it has a betaine-like structure.

Specific examples of the sensitizing dye used in the present invention are illustrated below.

2H5 2H5 2H5 Engineering ■ 0s [19) ■ ! Os 0s (CH2)4 0s Hs CHbe+80s 2H5 2H5 ■ The sensitizing dye used in the present invention can be synthesized by a method known to those skilled in the art. It can be added to the silver halide emulsion at any time before coating the emulsion. The amount added can vary within a wide range, but good results have been obtained with I x 10-6 per mole of silver halide.
~lXl0-' mol. The optimum amount to be added varies depending on the composition of the silver halide emulsion, for example, the halogen composition, the average grain size of the silver halide grains, the crystal habit, etc.

The binder used in the silver halide emulsion of the lithographic printing plate of the present invention is usually gelatin, and gelatin partially contains starch, hydroxyethyl cellulose, gum arabic, and polyvinyl alcohol.

polyvinylpyrrolidone, carboxymethylcellulose,
It can also be replaced with one or more hydrophilic polymer binders such as polyacrylamide, styrene-maleic anhydride copolymer, and polyvinyl methyl ether-maleic anhydride copolymer. Furthermore, an aqueous vinyl polymer dispersion (latex) can also be used. It is desirable that the amount of these binders is at most twice as much as the silver halide, preferably up to 1.5 times (by weight).

Silver halide emulsions can be sensitized in a variety of ways when they are manufactured or coated. Preferably, it is chemically sensitized by methods well known in the fractional art, such as by sodium thiosulfate, alkylthioureas, or by gold compounds such as rhodan gold, gold chloride, or a combination of both.

The silver halide emulsion layer can contain conventional additives such as coating aids, hardening agents, anti-capri agents, matting agents (water retention agents), and developing agents.

Below the silver halide emulsion layer (support side), an undercoat layer is provided to improve adhesion, or an undercoat layer which may contain a coloring agent such as carbon black or a compound that absorbs light of 700 nm or more is used. This layer can also contain a developing agent, a matting agent, and the like.

The image-receiving layer is provided above the silver halide emulsion layer, that is, as the outermost surface layer.

As the physical development nucleus, known metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead, zinc, and their sulfides can be used. The image-receiving layer contains hydrophilic colloids such as gelatin, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, dialdehyde starch, dextrin, hydroxyethyl cellulose, polystyrene sulfonic acid, a copolymer of vinylimidazole and acrylamide, and polyvinyl alcohol. It may contain one or more types of gold. The amount of hydrophilic colloid contained in the image-receiving layer is preferably 0.5 g/- or less.

Hygroscopic substances such as humectants such as sorbitol, glycerol, etc. may be present in the image-receiving layer. Furthermore, the image-receiving layer may also contain pigments for preventing scumming such as barium sulfate, titanium dioxide, china clay, and silver, developing agents such as hydroquinone, and hardening agents such as formaldehyde and dichloro-8-triazine.

The support may be, for example, paper, film, such as cellulose acetate film, polyvinyl acetal film, polystyrene film, polypropylene film, polyethylene terephthalate film, or a composite film of polyester, polypropylene, or polyethylene film coated with polyethylene film, metal, or metal. It can be a support of synthetic paper or metal/paper laminate. Paper supports coated on one or both sides with an alpha-olefin polymer, such as polyethylene, are also useful. These supports include
A compound having antihalation ability may be mixed.

The developing solution used in the present invention includes alkaline substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, etc., sulfite as a preservative,
Silver halide solvents, such as thiosulfates, thiocyanates, cyclic imides, thiosalicylic acid, amines, etc., thickening agents, such as hydroxyethylcellulose, carboxymethylcellulose, antifoggants, such as potassium chloride, 1-7
22-5-mercaptotetrazole, 981 1972-
26201, developers such as hydroquinone, 1-phenyl-3-pyrazolidone, development modifiers such as polyoxyalkylene compounds, onium compounds, and the like.

In carrying out the silver complex diffusion transfer method, for example, British Patent Nos. 1,000,115 and 1,012,476,
No. 1,017,273; is being mixed in. Therefore, in such materials.

The processing liquid used in the development stage is a liquid that does not contain developer.
Use an alkaline activating solution.

The lithographic printing plate manufactured according to the present invention is, for example,
8-29723, U.S. Pat. No. 3,721,539, etc., the ink receptivity can be changed or enhanced by compounds such as those described in the patent specifications.

The printing method, the desensitizing liquid, the dampening liquid, etc. used can be any commonly known method.

(E) Examples The present invention will be explained below using examples, but it is of course not limited thereto.

Example 1 Silver halide emulsion was prepared by keeping gelatin, sodium chloride and water at 50°C in a reaction vessel, and reducing the pAg in the reaction vessel.
While maintaining Fi at 8.0, silver nitrate aqueous solution and sodium chloride aqueous solution were added by double jet method, and the average particle size i
o, adjusted to 25μ. This emulsion was named iA. Furthermore, the average particle size is 0.3μ, 0.5μ't i, i i,
They were labeled B and C, respectively. For comparison, 0.3 .mu.'t-adjustment was carried out using a single jet method, and the result was designated as D. Note that rhodium chloride is added in an amount of 5.times.10-' mol per mol of silver halide during physical thermal formation. This emulsion was washed with water, and after desalting, the pH was adjusted to 6.
．． 0, gold and sulfur sensitization was performed using sodium thiosulfate and chloroauric acid, and after chemical sensitization, F was adjusted to pH 4.5.
ili! ! I arranged it.

The crystal habit and grain size of this emulsion were confirmed using an electron microscope and a particle size distribution analyzer. The emulsions A-C have an average grain size of ±3
More than 90% of the total number of grains were distributed in the range of 0 threads, and more than 90% of all the grains were silver chloride crystals with (100) planes. The emulsion has a distribution of 70% of the total grain number in the range of ±30 inches of the average grain size, and is an emulsion with a mixture of cubic, spherical, potato-shaped, etc. grains, and 60% of the total grain number is (100).
This could be called a surface crystal habit.

These silver halide emulsions contain the above-mentioned sensitizing dye (25) in an amount of I x 10-' mol per 1 mol of silver halide,
1 per mole of silver halide in water-soluble polymer (28)'
A sample with 0f added and a sample without 0f added were prepared to form a silver halide emulsion layer (pH 4.4 - Supervised by J).

A matting layer containing silica particles with an average particle size of 5 μm is provided on one side of a subbed-treated polyester film support, and a matting layer containing carbon black with an average particle size of 7 μm at 20 Mfii% relative to photographic gelatin is provided on the opposite side. An undercoat layer (adjusted to pH 4.5) containing silica powder was provided.

The gelatin in the undercoat layer is 3.0 fld, and the gelatin in the emulsion layer is 1.0'/? It was applied at a rate of 1.2 parts silver halide converted to silver nitrate. The undercoat layer and emulsion layer contain formalin as a hardening agent in a ratio of 5.01 parts gelatin to gelatin. After drying and heating at 40° C. for 14 days, a core coating solution of Brae) A11 in Example 1 of JP-A-54-103104 was prepared in the same manner on top of this emulsion layer. Apply.

These samples were exposed to light as follows immediately after production (however, they were left overnight at 35°C) and after being stored at 50°C and 80% relative humidity for 4 days.

Attach a dark red filter (8C-70 manufactured by Fuji Photo Film) to the light source that transmits light and sound with wavelengths longer than approximately 700 nm.
Each sample was subjected to a 10-5 second flash exposure through a light wedge to provide a sensitometric sample.

On the other hand, for these samples, a laser diode scanner that emits at 780 nm, the UltraSet
Image exposure was performed using TER (manufactured by Ultre, Inc., USA) to prepare a sample for paulownia.

Each image-exposed sample was treated with the following DTR developer for 2 hours.
Developed at 5° C. for 30 seconds.

After the development process, the original plate is passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing liquid having the following composition for 25" Cl2O seconds, and the excess liquid is removed using a squeezing roller, Dry at room temperature.

Transfer developer〉 Neutralizing liquid〉 To test the printing durability, paste each sample onto a sheet, place this sheet in an offset printing machine, apply the following desensitizing liquid all over the plate surface, and apply the following desensitizing liquid to the plate surface. Printing was carried out using the dampening liquid. The printing machine is N.B.Dick 350CD (A
-B @ Trademark of Dick offset printing machine) All were used. The printing durability according to the number of sheets that could not be printed was evaluated based on the following criteria and is shown in Table 1.

Evaluation: 1゜2゜3゜4゜5゜1.000 sheets or less 1.000 to 3,000 sheets 3.000 to s, ooo sheets s, ooo to 7,000 sheets? , Goo sheets or more <Desensitizing liquid><Moisturizingliquid> Sensitivity is expressed as a relative value, with the sensitivity immediately after production of the sample being 100, which is the exposure amount required to stop forming transfer deposits.

Table 1 Example 2 Laser diode scanner using the same emulsions A-D as in Example 1 and emitting light at 780 nm, UltraBet
Image exposure was performed at ter, 50, 100, 150.2
The resolution was evaluated by printing a 00μ thin line.

Table 2 shows the deterioration from the start of printing when s, ooo sheets of thin line images are printed.

Table 2 Table 3 Example 4 5+! Emulsions B and D are the same as in Example 1, but the mixing ratio is changed to show changes in the habit plane ratio of the silver halide emulsions.

Example 3 Similarly, images were created using m light intensity changes using ULTRE 5etter, and the relationship between the printing durability of the sub-exposure factor and scumming was evaluated. The exposure amount is shown as a relative value with the appropriate exposure amount being 100.

CF) Effects of the Invention According to the present invention, a sensitizing dye having maximum spectral sensitivity at 700 nm or more is used, and it has excellent storage stability against semiconductor laser light, high sensitivity, high printing durability, and high resolution. It was possible to obtain a lithographic printing plate for scanning exposure using a silver complex diffusion transfer method that has good image quality and no background smudge.

Claims (1)

[Scope of Claims] 1. A lithographic printing plate having a silver halide emulsion layer containing a sensitizing dye having maximum spectral sensitivity in a wavelength range longer than 700 nm and a surface physical development nucleus layer on a support is subjected to high illumination for a short time. In a lithographic printing plate which is developed with a developer for silver complex diffusion transfer after exposure to scanning lines of
00) silver halide grains having a plane crystal habit, in which 90% or more of the total number of grains are within ±30% of the average grain size; b) the silver halide emulsion has a grain size of 0.3 μ or more; c) the emulsion; A lithographic printing plate for scanning exposure, characterized in that the layer contains a water-soluble polymer having a carboxyl group and an average molecular weight of 20,000 or less.