JPH0345377B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to a lithographic printing plate using a silver complex diffusion transfer method suitable for using laser light, particularly semiconductor laser light, as a light source, and a method for making the same. (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 as ink receptivity has already been published in Japanese Patent Publication No. 48-30562 and Japanese Patent Application Laid-Open No.
53-21602, 1982-103104, 1982-9750, etc., and are 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, and a subbing layer for preventing halation, a silver halide emulsion layer, and a physical development nucleus layer are formed on the support. When a photosensitive material consisting of 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 latent image has been formed is dissolved by the action of a silver halide complexing agent contained in the processing solution and diffused onto the surface of the photosensitive material. The dissolved and diffused silver complex salt is deposited as a silver image on the physical development nuclei of the surface layer by the reducing action of the developing agent. The resulting silver image is subjected to development and, if necessary, a sensitization treatment to enhance its ink receptivity, and then placed in an offset printing press.
The ink image is transferred to the printed material. In conventional methods, the silver halide emulsion layer is
By merocyanine dye, cyanine dye, etc.
It was spectrally sensitized to have a maximum sensitivity in the green region around 550 nm, and exposed for several seconds to several tens of seconds using a plate-making camera with a normal light source such as a tungsten light source. However, the above-mentioned conventional method has limitations even though the lithographic printing plate originally has excellent sharpness and resolution. Moreover, if one tries to obtain color printed matter from a color original, there are still problems in that not only the resolution is insufficient, but also the production of printing plates and plate-making operations are complicated. Today, as one method for solving the above-mentioned problems, plate making using laser light has been proposed. For example, US Pat. No. 4,501,811,
Unexamined Japanese Patent Applications 1986-71055, 1983-75838, 1983-
100148 and the like disclose a lithographic printing plate for use with a helium-neon laser or a light emitting diode. As described in these patent specifications, in these lithographic printing plates using the silver complex diffusion transfer method, the surface physical development nucleus layer has a large effect on the spectral sensitization, and as a result, the desired sensitivity to laser light is achieved. In addition, as a result of forming a soft transferred deposited silver image due to silver complex salt diffusion transfer development, sharpness and resolution decrease, and furthermore, background stains may occur, and the silver image may deteriorate. It is difficult to obtain a lithographic printing plate of high quality as desired because it may come off during printing, and sufficient printing durability cannot be obtained. Therefore, a sensitizing dye that meets these requirements must of course have sufficiently high sensitivity at the wavelength of laser light;
It satisfies all of the following requirements: good storage stability, the ability to form a high-contrast transferred deposited silver image, no negative effects such as scumming, and the ability to form strong transferred deposited silver that cannot be removed during printing even with minute silver. It must be something that can be done. Various types of lasers are known, but
The method of using a laser light source such as helium-neon or argon as a scanner type light source has drawbacks such as a large and expensive device capable of obtaining high output, and low power consumption efficiency. On the other hand, semiconductor lasers have advantages such as being small, inexpensive, easy to modulate, and have a long life. Semiconductor lasers include Ga/As/P; Ga/Al/As; Ga/As;
Semiconductors of systems such as In/P; In/As are used,
The wavelength of this laser light is generally longer than 700 mμ, and in particular there are many wavelengths longer than 750 mμ. A photosensitive lithographic printing plate using such long wavelength semiconductor laser light as a light source for imagewise exposure is described, for example, in Japanese Patent Laid-Open No. 61752/1983. This patent specification describes, as a particularly preferred embodiment, a photosensitive layer having a non-silver photosensitive layer (for example, a photosensitive layer made of an 0-naphthoquinone diazide compound and a photosensitive silver halide emulsion layer) capable of sequentially forming a lipophilic image on a support. A lithographic printing plate is shown, and the sensitizing dyes used in the emulsion layer and having maximum spectral sensitivity in the wavelength region longer than 700 mμ are disclosed as general formulas () to (). Specific dyes are used as silver halide photographic light-sensitive materials for semiconductor lasers in JP-A-59-191032 and JP-A-59-1910.
A specific example is disclosed in 192242. However, the present inventors have discovered that many infrared sensitizing dyes, including the sensitizing dyes specifically shown in these patent specifications, have a physical development nucleus layer as the outermost surface layer described above. When incorporated into the silver halide emulsion layer of a lithographic printing plate, only a lithographic printing plate with insufficient sensitivity and resolution and poor printing durability was obtained for plate making with semiconductor laser light. (C) Purpose of the Invention The purpose of the present invention is to provide a high-sensitivity, high-resolution,
It is an object of the present invention to provide a lithographic printing plate and a plate-making method that use a silver complex diffusion transfer method that has high printing durability and is free from scumming. (D) Structure of the Invention The above object of the present invention was achieved by incorporating a sensitizing dye to be described later into the silver halide emulsion layer of a lithographic printing plate. That is, the present invention provides a lithographic printing plate having at least a silver halide emulsion layer and a surface physical development nucleus layer on a support, in which the emulsion layer contains at least one sensitizing dye represented by the following general formula []. A lithographic printing plate characterized by containing: General formula [] (In the formula, Z ₁ is a 5- or 6-membered nitrogen-containing heterocycle,
Z ₂ represents an atomic group necessary to form a 5-membered nitrogen-containing heterocycle. R ₁ and R ₂ may be the same or different, and each represents an alkyl group or an alkenyl group. R ₃ is an alkyl group, an alkenyl group,
Represents an aryl group. R ₄ to _{R 9} may be the same or different, and each represents a hydrogen atom, a halogen atom, an alkyl group, or an aryl group. Y
represents a sulfur atom, an oxygen atom, or N-R ₁₀ (R ₁₀ represents an alkyl group). X represents an acid anion, l, m, n, p and q are each 1 or 2
represents. However, if m and n are both 1, l
is 2. ) Specific examples of Z ₁ and N ₂ include thiazole, benzothiazole, naphtho[1,2-d]thiazole, naphtho[2,1-d]thiazole, naphtho[2,3-d]thiazole, selenazole, benzo selenazole, naphtho[2,1-d] selenazole, naphtho[1,2-d] selenazole, oxazole, benzoxazole, naphtho[1,2
-d]oxazole, naphtho[2,1-d]oxazole, naphtho[2,3-d]oxazole,
Examples include nitrogen-containing heterocycles such as 2-quinoline, 4-quinoline, 3,3-dialkylindolenine, imidazole, benzimidazole, naphtho[1,2-d]imidazole, and pyridine. These heterocycles include alkyl groups (e.g. methyl,
ethyl, butyl, trifluoromethyl, etc.), aryl groups (e.g., phenyl, tolyl, etc.), hydroxyl groups, alkoxy groups (e.g., methoxy, ethoxy, butoxy, etc.), carboxy groups, alkoxycarbonyl groups (e.g., methoxycarbonyl, ethoxy carbonyl, etc.), halogen atoms (e.g.
Substituents such as fluorine, chlorine, bromine, iodine), aralkyl groups (e.g., benzyl, phenethyl, etc.), cyano groups, alkenyl groups (e.g., allyl, etc.)
Alternatively, it may have two or more. In R ₁ and R ₂ , the alkyl group is methyl,
Lower alkyl groups such as ethyl, propyl, butyl,
Hydroxyalkyl groups such as β-hydroxyethyl and γ-hydroxypropyl, alkoxyalkyl groups such as β-methoxyethyl and γ-methoxypropyl, and acyloxyalkyl groups such as β-acetoxyethyl, γ-acetoxypropyl and β-benzoyloxyethyl. , carboxyalkyl groups such as carboxymethyl, β-carboxyethyl, alkoxycarbonylalkyl groups such as methoxycarbonylmethyl, ethoxycarbonylmethyl, β-ethoxycarbonylethyl, β-sulfoethyl, γ
Examples of the alkenyl group include sulfoalkyl groups such as -sulfopropyl and δ-sulfobutyl, aralkyl groups such as benzyl, phenethyl, and sulfobenzyl, and allyl. Examples of R ₃ include alkyl groups and alkenyl groups as described above for R ₁ and R ₂ , and aryl groups such as phenyl, tolyl, methoxyphenyl, chlorophenyl, and naphthyl. In R ₄ and R ₉ , the alkyl group and aryl group include the groups mentioned above for R ₁ and R ₂ ,
Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Examples of R ₁₀ include lower alkyl groups such as methyl and ethyl. Examples of the acid anion of It does not exist if . Further, l, m, n and q each represent 1 or 2. Representative examples of sensitizing dyes used in the present invention are shown below. The sensitizing dye used in the present invention can be synthesized by methods 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 are in the range 1.times.10.sup. ^-5 to 1.times.10.sup.- ² mol per mol of silver halide. The optimum amount to be added varies depending on the conditions of the silver halide emulsion, such as the halogen composition, the average grain size of the silver halide grains, and the crystal habit. The silver halide emulsion of the lithographic printing plate of the present invention can be silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, etc., and preferably silver chloride is a halogen containing 50 mol% or more. It is chemical silver. The average particle size of these silver halide grains is preferably in the range of 0.2 to 0.8 microns, but ranges other than this can also be used. Furthermore, silver halide accounts for 90 of the total number of grains.
It is preferable that the emulsion is a monodispersed emulsion having a grain size within ±30% of the average grain size. Although silver halide grains are preferably substantially cubic or tetradecahedral, silver halide having other crystal habits may also be used. The binder used in the silver halide emulsion of the lithographic printing plate of the present invention is usually gelatin.
Substituted with one or more hydrophilic polymer binders such as gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, polyacrylamide, styrene-maleic anhydride copolymer, polyvinyl methyl ether-maleic anhydride copolymer, etc. You can also. Furthermore, an aqueous vinyl polymer dispersion (latex) can also be used. Silver halide emulsions can be sensitized in a variety of ways when they are manufactured or coated. Chemically sensitized by methods well known in the art, for example with sodium thiosulfate, alkylthioureas, or with gold compounds such as gold rhodan, gold chloride, or a combination of both. is preferred. In addition, by using compounds of metals belonging to groups of the periodic table, such as salts of cobalt, nickel, rhodium, palladium, iridium, platinum, etc., at any stage in the production of silver halide emulsions, particularly high It is possible to obtain characteristics favorable for printing plates for direct plate making, such as sensitivity, high sharpness, and high resolution. The amount added is 10 ^-8 to 1 mole of silver halide.
It is in the range of 10 ⁻³ mol. The silver halide emulsion layer may contain other additives, such as coating aids, hardeners,
It can contain conventional additives such as antifoggants, 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 that may contain a coloring agent such as carbon plaque or a compound that absorbs light of 700 μm or more. 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. Physical development nuclei include antimony, bismuth,
cadmium, cobalt, palladium, nickel,
Known metals such as silver, lead, and zinc and their sulfides can be used. The image receiving layer contains gelatin, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl starch, dialdehyde starch, dextrin, hydroxyethyl cellulose, polystyrene sulfonic acid,
It may contain one or more hydrophilic colloids such as a copolymer of vinylimidazole and acrylamide and polyvinyl alcohol. The hydrophilic colloid contained in the image-receiving layer is preferably 0.1 g/m ² 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 contains pigments for preventing scumming such as barium sulfate, titanium dioxide, china clay, and silver, developing agents such as hydroquinone, and formaldehyde and dichloro-S-
Curing agents such as triazines may also be included. 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 in which polyester, polypropylene, or polystyrene film is coated with polyethylene film, metal, or metallized paper. Or it can be a support for a metal/paper laminate. Paper supports coated on one or both sides with an alpha-olefin polymer, such as polyethylene, are also useful. These supports may contain a compound capable of preventing halation. 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, and silver halide solvents such as thiosulfate. , thiocyanates, cyclic imides, thiosalicylic acid, amines, etc., thickening agents such as hydroxyethyl cellulose, carboxymethyl cellulose, antifoggants such as potassium bromide, 1-
Phenyl-5-mercaptotetrazole, JP-A-Sho
47-26201, developers such as hydroquinone, 1-phenyl-3-pyrazolidone,
Development modifiers such as polyoxyalkylene compounds, onium compounds, etc. can be included. In carrying out the silver complex diffusion transfer method, for example, British Patent No. 1000115, British Patent No. 1012476, British Patent No.
As described in specifications such as No. 1017273 and No. 1042477, a developer is mixed into the silver halide emulsion layer and/or the image receiving layer or other water permeable layer adjacent thereto. . Therefore, for such materials, the processing liquid used in the development step may be a so-called "alkaline activating liquid" which does not contain a developer. The ink receptivity of the lithographic printing plates produced according to the present invention can be changed or enhanced with compounds such as those described in Japanese Patent Publication No. 48-29723 and US Pat. No. 3,721,539. 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 A matting layer containing silica particles with an average particle size of 5 μm was provided on one side of a subbed polyester film support, and a matting layer containing silica particles with an average particle size of 5 μm was provided on the other side, and carbon black was provided on the opposite side, and 20% by weight of photographic gelatin was added to the support. An undercoat layer containing silica powder with an average particle size of 7 μm (adjusted to pH 4.0) and a silica powder with an average particle size of 7 μm after being chemically sensitized with a gold compound on photographic gelatin.
A spectrally sensitized high-sensitivity silver chloroiodobromide emulsion layer (Br3 mol%, I0.4 mol%,
(pH adjusted to 4.0 with Cl96.6 mol%). Gelatin for the undercoat layer was coated at a rate of 3.0 g/m ² , gelatin for the emulsion layer was coated at a rate of 1.0 g/m ² , and silver halide was coated at a rate of 1.0 g/m ² in terms of silver nitrate. The undercoat layer and emulsion layer contain formalin as a hardening agent in an amount of 5.0 mg/g gelatin. After drying and heating at 40℃ for 14 days, on top of this emulsion layer,
The core coating liquid described in Example 2 of JP-A-53-21602 (polymer is No. 3 copolymer of acrylamide and imidazole, hydroquinone is 0.8 g/m ²
) is coated and dried to produce a lithographic printing plate. The silver halide emulsion had 5 x 10 ^-6 mol of rhodium chloride added per mol of silver halide during physical ripening, and had an average grain size of 0.3 microns.
The crystals were substantially cubic crystals with more than 90% of the total number of particles distributed within a range of ±30% of the average particle size. As sensitizing dyes used in silver halide emulsions, dyes shown in Table 1 below are used per mole of silver halide.
Eleven types of lithographic printing plates were produced in exactly the same manner as described above, except that 10 ^-3 mol was added. The following dyes were used for comparison. A dark red filter (SC-70, manufactured by Fuji Photo Film Co., Ltd.) that transmits light with a wavelength longer than about 700 mμ was attached to the light source, and the film original containing the fine line image and each of the above-mentioned lithographic printing plates were exposed to light in a state in close contact with each other. Flash exposure was applied in the range of 10 ^-4 to ^{10 -5} seconds depending on the sensitivity difference to achieve approximately the same degree of printing, and this was used as a print test sample. Separately, a dark red filter (SC-70) was attached to the light source, and the lithographic printing plate was exposed to flash light for 10 ^-5 seconds through a light wedge to prepare a sample for sensitometry. After exposure, development was performed using the following diffusion transfer developer. <Transfer developer> Water 700ml Sodium hydroxide 18g Potassium hydroxide 7g Anhydrous sodium sulfite 50g 2-mercaptobenzoic acid 1.5g 2-methylaminoethanol 15g Adjust to 1 with water. After the development process, the original plate was passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing solution having the following composition at 25°C for 20 seconds, and the excess liquid was removed using a squeezing roller. , dried at room temperature. <Neutralizing solution> Water 600ml Citric acid 10g Sodium citrate 35g Colloidal silica (20% liquid) 5ml Ethylene glycol 5ml Add water to bring the total volume to 1. Table 1 shows the sensitivity and printing durability of each lithographic printing plate. Sensitivity is expressed as a relative value, with the exposure amount required to stop the formation of transfer deposited silver, with the sensitizing dye (-3) being 1.0. The printing durability was determined by pasting each sample onto a single sheet, attaching this sheet to an offset printing machine, applying the following desensitizing liquid all over the plate surface, and printing using the following dampening liquid. Ivy. The printing machine is A.B.Ditzk 350CD (A.
A B. Dick offset printing press (trademark) was used. The printing durability was evaluated based on the number of sheets that could not be printed due to occurrence of scumming or silver scattering, and is shown in the right column of Table 1 using the following criteria. Evaluation 1 4000 sheets or less 2 4000-6000 sheets 3 6000-8000 sheets 4 8000-10000 sheets 5 10000 sheets or more <Desensitizing liquid> Water 600ml Isopropyl alcohol 400ml Ethylene glycol 50g 3-mercapto-4-acetamide-5-n-
Heptyl-1,2,4-triazole 1g <Moisturizing liquid> O-phosphoric acid 10g Nickel nitrate 5g Sodium sulfite 5g Ethylene glycol 100g Colloidal silica (20% liquid) 28g Add water to make 2.

【table】

[Table] Example 2 A lithographic printing plate was prepared in the same manner as in Example 1 except that a silver chloroiodide emulsion containing 0.2 mol % of silver iodide was used. However, the sensitizing dyes shown in Table 2 below were used. Thereafter, plate making and printing were performed according to Example 1 to obtain the results shown in Table 2. Sensitivity is sensitizing dye (-2)
It is a relative value with the value of 1.0.

[Table] Example 3 Each sample of Examples 1 and 2 was heated at 50℃ and 80%RH.
After being stored for 3 days at It had a desensitization rate of 1,000,000, and had a sufficiently good storage stability. (F) Effects of the Invention The lithographic printing plate of the present invention has extremely high sensitivity to light with a wavelength longer than 700 mμ, especially semiconductor laser light of 750 mμ or more, has high printing durability, and has excellent storage stability. It is excellent.

Claims (1)

[Scope of Claims] 1. In a lithographic printing plate having at least a silver halide emulsion layer and a physical development nucleus layer as a surface layer on a support, a sensitizing dye represented by the following general formula [] is provided in the emulsion layer. A lithographic printing plate characterized by containing at least one of the following. General formula [] (In the formula, Z ₁ is thiazole, benzothiazole,
Naphthothiazole or a quinoline ring, and Z ₂ represents thiazole, benzothiazole or naphthothiazole. R ₁ and R ₂ may be the same or different, and each represents an alkyl group or an alkenyl group. R ₃ represents an alkyl group, an alkenyl group, or an aryl group. R ₄ to _{R 9} may be the same or different, and each represents a hydrogen atom, a halogen atom, an alkyl group, or an aryl group. Y represents a sulfur atom. X represents an acid anion, l,
m, n, p and q each represent 1 or 2.
However, when m and n are both 1, l is 2. )