JPH0127416B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lithographic printing plate using a silver complex diffusion transfer method suitable for plate making using a light emitting diode exposure device. 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 developed 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 manufacturing and plate-making operations of the printed matter are complicated. Today, as a method to solve the above-mentioned problems, direct plate making using a high-intensity, short-time (10 ^-5 seconds or less) scanning exposure method such as laser light or light emitting diode is considered, but it is not well known. As described above, these exposure methods cause high-intensity reciprocity failure, resulting in unsatisfactory characteristics such as low sensitivity and soft contrast. Especially light emitting diode LED,
Because the output is lower than neon-helium laser light, it has higher sensitivity, higher contrast, sharpness, and
There is a need for a lithographic printing plate that has excellent resolution and does not cause scumming or remove silver images during printing. Therefore, sensitizing dyes that meet these requirements are
Not only does it have sufficiently high sensitivity in the wavelength range of about 600 to 730 nm (oscillation wavelength width is about 15 nm), which is generally stably used for LEDs, but it also has good storage stability and high contrast transfer deposited silver. It must be able to form images, be free from background smudges, and be able to form strong transferred deposited silver that cannot be removed during printing even with minute amounts of silver. JP-A-53-21601 describes the use of betaine or anionic cyanine sensitizing dyes as offset printing plates with high sensitivity and improved printing characteristics, and silver bromide is used to obtain high sensitivity. It has also been shown that it is preferable to use silver halide emulsions with a high content. On the other hand, it is known that silver halide emulsions with a high silver chloride content have lower spectral sensitization effects in high-intensity, short-time exposures (for example, Japanese Patent Publication No. 48-42172), and also in high-intensity reciprocity rules. It is also known to have a large failure rate (for example, Photographic Science and Engineering Vol. 26, 1982), and is generally unsuitable as an emulsion for LEDs. However, by using a specific sensitizing dye in a silver halide emulsion with a high silver chloride content, the present inventors have achieved sufficiently high sensitivity to exposure using an LED light source and good printing characteristics. We have discovered that a lithographic printing plate using the silver complex diffusion transfer method can be obtained. An object of the present invention is to provide a lithographic printing plate using a silver complex diffusion transfer method that is highly sensitive to exposure using an LED as a light source and has good printing characteristics. The above object of the present invention is for silver complex salt diffusion transfer using a light emitting diode as a light source, characterized in that a silver halide emulsion layer containing at least 70 mol% of silver chloride contains a sensitizing dye of the following general formula (). Achieved by lithographic printing plates. General formula () In formula (), R ₁ and R ₂ are each an alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, β-sulfoethyl group, γ-sulfopropyl group, γ-sulfobutyl group, vinylmethyl group, β
-carboxyethyl group, γ-carboxypropyl group, δ-carboxybutyl group, etc.), alkenyl group,
represents an aryl group or an aralkyl group, R ₁ and
At least one of R ₂ is a group having a sulfo group or a carboxyl group. R ₃ and R ₄ are each a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a hydroxyl group, an alkoxycarbonyl group,
It represents a halogen atom, and R ₃ and R ₄ may form a benzene ring. R ₅ represents an alkyl group, an aryl group, or an aralkyl group. Y ₁ and Y ₂ represent an S atom and a Se atom, respectively. X represents a cation such as hydrogen, alkali metal, ammonium, etc.
represents 1 or 0. Next, typical sensitizing dyes used in the present invention are illustrated. The dyes used for comparison are shown below. The sensitizing dye used in the present invention can be synthesized by methods known to those skilled in the art. The additive can be added to the silver halide emulsion at any time before the emulsion is coated. 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 is a silver halide containing 70 mol% or more, preferably 80 mol% or more of silver chloride, such as silver chloride, silver chlorobromide, or silver chlorobromoiodide. The average particle size of these silver halide grains is preferably in the range of 0.2 to 0.6 microns, but ranges other than this can also be used.
Furthermore, the silver halide is preferably a monodispersed emulsion in which 90% or more of the total number of grains has 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 rhodan gold, gold chloride, or a combination of both. preferable. Furthermore, compounds of metals belonging to Groups of the Periodic Table, such as salts of cobalt, nickel, rhodium, palladium, iridium, platinum, etc., can be used at any time during the production of silver halide emulsions. The amount added is
The amount ranges from 10 ^-8 to ^{10 -3} mol per mol of silver halide. The silver halide emulsion layer contains other additives,
For example, it may contain conventional additives such as coating aids, antifoggants, matting agents (water retention agents), and developing agents. An undercoat layer may be provided below the silver halide emulsion layer (on the support side) for the purpose of improving adhesion and/or preventing halation, and this layer may contain a developer, matting agent, etc. You can also do it. The lithographic printing plate of the present invention has an image-receiving layer containing physical development nuclei. As physical development nuclei, known ones such as metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead, zinc, and their sulfides can be used. The image-receiving layer does not need to contain hydrophilic colloids, and may include gelatin, carboxymethylcellulose, gum arabic, sodium alginate, hydroxyethyl starch, dextrin, hydroxyethylcellulose, polystyrene sulfonic acid, a copolymer of vinylimidazole and acrylamide, Hydrophilic colloids such as polyvinyl alcohol may be included, preferably in amounts of up to 0.1 grams per square meter. 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. 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 also contain antihalation dyes or pigments. The DTR processing solution used in the present invention includes alkaline substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, etc., sulfites as preservatives, silver halide solvents such as thiosulfate, etc. , 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,
It can contain onium compounds and the like. 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 solution used in the development step may be a so-called "alkaline activating solution" that 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. The present invention will be explained below with reference to Examples, but of course it is 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 anti-halation undercoat layer containing silica powder with an average particle size of 7 μm (adjusted to pH 4.0) and 5% by weight of silica powder with an average particle size of 7 μm based on photographic gelatin after being chemically sensitized with a gold compound. A spectrally sensitized high-sensitivity silver chloride emulsion layer containing a proportion of (adjusted to PH4.0)
and has been established. 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°C for 14 days, the core coating liquid described in Example 2 of JP-A No. 53-21602 (the polymer is a combination of acrylamide and imidazole in No. 3) was applied on top of this emulsion layer. The polymer, hydroquinone,
0.8 g/m ² ) is coated and dried to produce a lithographic printing plate. The silver halide emulsion was prepared by adding 5 x 10 ^-6 mol of rhodium chloride per 1 mol of silver halide during physical ripening, and had an average grain size of 0.45.
It was a substantially cubic crystal with more than 90% of the total number of particles distributed within a range of ±30% of the average particle size in microns. As sensitizing dyes used in silver halide emulsions, the dyes shown in Table 1 below were used at a concentration of 3% per mole of silver halide.
Eight types of lithographic printing plates were produced in exactly the same manner as described above, except that ×10 ^-4 mol was added. Light emitting diode exposure equipment (wavelength approx. 670 to approx.
680nm) and a 10 ^-7 second exposure was given using a scanner method. After exposure, development was performed using the following diffusion transfer developer. <Transfer developer> Water 700ml Potassium hydroxide 20g Anhydrous sodium sulfite 50g 2-mercaptobenzoic acid 1.5g 2-methylaminoethanol 15g Make 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 liquid> 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, sharpness, and resolution of each lithographic printing plate. Sensitivity is the amount of exposure required to stop the formation of transfer deposited silver, and is the amount of exposure required to stop the formation of transfer deposited silver.
It is expressed as a relative value of 1.0. In addition, the sharpness and resolution were measured using gray contact screens with 100, 133, 150, 175, and 200 lines/inch. It was expressed in five grades from evaluation 1 (100 lines/inch) to evaluation 5 (200 lines/inch). <Degreasing liquid> Water 600ml Isopropyl alcohol 400ml Ethylene glycol 50g 3-mercapto-4-acetamide -5-n-heptyl-1,2,4-triazole 1g <Moistening liquid> O-phosphoric acid 10g Nickel nitrate 5g Sulfurous acid Sodium 5g Ethylene glycol 100g Colloidal silica (20% liquid) 28g Add water to make 2. The printing machine is AB Deitsku 350CD (A.
The trademark of the B. Dick offset printing press 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 flying, and is shown in the right column of Table 1 based on the following criteria.

[Table] Each lithographic printing plate shown in Table 1 was mounted on an offset printing machine, the following desensitizing liquid was applied all over the print, and printing was performed using the following dampening liquid. 1 4000 sheets or less 2 4000 to 6000 sheets 3 6000 to 8000 sheets 4 8000 to 10000 sheets 5 10000 sheets or more The lithographic printing plate of the present invention has high printing durability despite having minute halftone dots. I understand that. Also,
It was also confirmed that the lithographic printing plate of the present invention is stable and does not lose its properties even when stored for a long period of time. Example 2 Four types of emulsions were prepared in the same manner as in Example 1, except that silver chlorobromide emulsions and silver bromide emulsions containing 5, 25, 50 and 100 mol% of silver bromide were used instead of the silver chloride emulsion of Example 1. An emulsion was produced. Four types of lithographic printing plates were prepared according to Example 1 using Dye 1 in these emulsions and tested in the same manner. The results are shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1. Silver complex salt diffusion transfer using a light emitting diode as a light source, characterized in that a silver halide emulsion layer containing at least 70 mol% of silver chloride contains a sensitizing dye of the following general formula (). Lithographic printing plate. General formula () (In the formula, R ₁ and R ₂ are an alkyl group, an alkenyl group,
Represents an aryl group or an aralkyl group, R ₁ and R ₂
At least one of them is a group having a sulfo group or a carboxyl group. R ₃ and R ₄ represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a hydroxyl group, an alkoxycarbonyl group, or a halogen atom, and R ₃ and R ₄ may form a benzene ring. R ₅ represents an alkyl group, an aryl group, or an aralkyl group. Y ₁ and Y ₂ represent a sulfur atom and a selenium atom. X represents a cation, m is 1 or 0
It is. )