JPH0226215B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a silver halide photographic material for producing a lithographic printing plate by a silver complex salt diffusion transfer method and a plate-making method thereof. A lithographic printing plate consists of an oleophilic image area that accepts oil-based ink and an oil-repellent non-image area that does not accept ink, and the non-image area generally consists of a hydrophilic area that accepts water. has been done. In normal planographic printing, therefore, both water and ink are supplied to the plate surface, and the image area selectively receives colored ink and the non-image area selectively receives water, and the ink on the image line is transferred to the paper, for example. This is done by transferring to a substrate such as Therefore, in order to obtain good printed matter, the difference in lipophilicity and hydrophilicity between the surface of the printed area and the background non-printed area must be sufficiently large so that when water and ink are applied, the printed area is It is necessary that a sufficient amount of ink be accepted, and that the non-image area should not receive any ink. Printing plates that apply the silver complex diffusion transfer method (DTR method) and use the formed metallic silver pattern as ink receptivity are already known (for example, U.S. Patent No.
No. 3220837, No. 3721559, Special Publication No. 1972-16725,
1972-30562, 4482-4482, 53-21602
etc.), some of which have been realized. In the lithographic printing plate in which the physical development nucleus particles are not embedded in the layer but are distributed in a partially exposed state as described in the above-mentioned Japanese Patent Publication No. 48-30562 and Japanese Patent Application Publication No. 53-21602, Since the transferred surface silver image itself is used for ink receptivity, the characteristics of the transferred silver image, such as contrast, sharpness, resolution, image reproducibility, and ink receptivity, have a large influence on print quality. I have to say that. However, in today's world where silver resources are limited and effective use is desired, there is a need for technology that does not impair printing quality as described above even when using a small amount of silver halide even in lithographic printing plates that apply the DTR method. Ru. From such a point of view, the present inventors have proposed the
DTR basically described in JP-A-53-21602 etc.
We conducted research and development to reduce the amount of silver halide used for lithographic printing plates using the method, but 1
In lithographic printing plates containing less than the amount of silver halide equivalent to 4 mmol of silver per square meter, especially 8 mmol of silver (0.51 grams of silver nitrate), the contrast, sharpness, resolution of the transferred silver image, It was also found that the image reproduction characteristics (characteristics for faithfully reproducing fine lines in manuscripts) were degraded, and the product did not meet the various performance standards required as a commercial product. As is well known, lithographic printing plates to which the DTR method is applied have high photosensitivity and excellent properties such as contrast, sharpness, and resolution.
Moreover, since such various characteristics are important for direct plate making, the above-mentioned drawbacks must be said to be serious drawbacks. An object of the present invention is to provide a method for making a lithographic printing plate that does not have the above-mentioned drawbacks. The present inventors believe that the above-mentioned drawbacks of lithographic printing plates using the DTR method with a small amount of silver can be solved by the adoption of the immersion method, which is a well-known diffusion transfer method, and which has actually been commercialized as an automatic plate-making machine. This drawback was solved by adopting a development method in which a diffusion transfer developer was applied to the entire print in the required amount, resulting in a high silver content despite the small amount of silver. It has been found that a lithographic printing plate having good contrast, sharpness, resolution, and image reproducibility characteristics and without a decrease in printing durability can be obtained. That is, the present invention is a plate-making method for a lithographic printing plate that utilizes a transferred silver image formed by a silver complex diffusion transfer method as ink receptivity, and the silver halide emulsion layer used contains 4 mmol of silver per square meter. The following is a plate-making method for a lithographic printing plate, characterized in that the alkaline processing liquid for diffusion transfer development is supplied to the plate surface in an amount substantially necessary for development. According to the present invention, the amount of silver halide coating corresponding to 4.6 mmol of silver per square meter described in JP-A-52-112402 can be made smaller, making it practical even in lithographic printing plates. . A plate-making method for always obtaining a constant lithographic printing plate by applying and supplying the amount of solution necessary for development onto a printing plate without immersing it in a diffusion transfer developer and eliminating changes in the developer has been disclosed in Japanese Patent Publication No. It is known in 1976-76603. However, the above-mentioned usefulness in the lithographic printing plate with extremely low silver content used in the present invention has not been demonstrated at all. Although the above patent focuses on the problem when organic compounds having mercapto or thione groups are present in the transfer developer, it is not necessary for the present invention to contain these organic compounds. However, of course, in the plate-making method of the present invention, the developer coating and supply system described in the above-mentioned patent can also be adopted. Namely, these methods include liquid lifting coating method, dripping method roller coating method, dripping method knife coating method, spray coating method, brush coating method, etc., and are not limited to specific developing processing machines. It is also possible to adopt developing processing methods and processing machines. The present invention can also be applied to a plate-making method such as that described in Japanese Patent Publication No. 16725/1983, in which a printing plate and a silver halide photosensitive material are separately produced, and the two materials are brought into close contact with each other for diffusion transfer development. in this case,
The transfer developer may be applied and supplied to a printing material having a physical development nucleus layer, or may be applied and supplied to a photosensitive material and then supplied from the photosensitive material to the printing material (by adhesion). The diffusion transfer developer preferably contains one or more of carboxymethyl cellulose, sodium polyacrylate, sodium alginate, gum arabic, polyethylene glycol, etc. as thickening components, as described in JP-A-48-76603. . Preferred thickeners are polyfunctional synthetic polymers having a functional group having an affinity for physical development nuclei and a functional group imparting hydrophilic activity as described in JP-A-53-21602; It can also be used in a physical development nucleus layer of a lithographic printing plate. The silver halide emulsion used in the present invention can be any of silver chloride, silver bromide, silver chlorobromide, and silver halides consisting of silver iodide and silver chloride. silver halide in a mole % or more. The size of silver halide grains,
There are no restrictions on crystal habit, distribution, etc., and any method known in the ordinary photographic field may be used for producing the silver halide emulsion. Silver halide emulsions can be sensitized by well-known chemical sensitization techniques, and can also be spectrally sensitized in blue, green, and red. In addition, antifoggants, stabilizers, developing agents, hardeners, matting agents (graining agents), and the like may be added as appropriate. The binder for the silver halide emulsion is preferably gelatin, but some or all of the gelatin may be substituted with other natural and/or synthetic hydrophilic colloids,
For example, substitution may be made with albumin, casein, polyvinyl alcohol, sodium alginate, sodium salt of carboxymethyl cellulose, and the like. The weight ratio of hydrophilic colloid to silver halide, expressed as silver nitrate, is generally from 5 to 0.3, preferably from 0.2 to 1.0. Lower side of the silver halide emulsion layer (closer to the support)
An undercoat layer may also be provided for the purpose of preventing halation or the like. Supports that can be used can be any supports commonly used in the art, such as paper, glass, films such as cellulose acetate films, polyvinyl acetal films, polystyrene films, polypropylene films, polyethylene terephthalate films. Alternatively, the support may be a composite film such as a polyester, polypropylene or polystyrene film coated with a polyethylene film, a metal, a metallized paper or a metal/paper laminate.
Paper supports coated on one or both sides with an α-olefin polymer, such as polyethylene, are also useful. These supports may contain antihalation dyes or pigments; the silver halide emulsion-coated side of the support may optionally contain water-permeable binders such as methyl cellulose, sodium salts of carboxymethyl cellulose, hydroxyethyl cellulose. , hydroxyethyl starch, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, etc. can be formed thinly as the uppermost layer. 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 of the present invention may be a so-called "alkaline activating solution" that does not contain a developer. An alkaline activating solution that does not contain a silver halide solvent can also be used, in which case the silver halide solvent is mixed into the constituent layers of the printing plate. In this way, the transfer developer has the advantage of containing substantially only an alkaline agent. The physical development nucleus layer, that is, the image-receiving layer, which is preferably adjacent to the silver halide emulsion layer of the present invention, may be disposed either above or below the silver halide emulsion layer, but is preferably above (further than the support). side). 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 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 also be included. 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 titanium sulfate dioxide, china clay and silver, a developing agent such as hydroquinone, and a hardening agent such as formaldehyde. The DTR treatment solution used in the method of the present invention contains alkaline substances, such as sodium hydroxide, potassium hydroxide, sodium triphosphate, etc., silver halide solvents, such as thiosulfate, thiocyanate, etc., as a preservative. sulfites, thickening agents such as hydroxyethylcellulose, carboxymethylcellulose, antifoggants such as potassium bromide, 1-phenyl-5-mercaptotetrazole, developers,
For example, hydroquinone, 1-phenyl-3-pyrazolidone, developer modifiers such as polyoxyalkylene compounds, onium compounds, etc. can be included. 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. 3,721,559. The printing method, the desensitizing liquid, the dampening liquid, etc. used can be any commonly known method. The present invention will be explained below using reference examples and examples, but is not limited thereto. Reference example A matting layer containing silica particles with an average particle size of 5 μm was provided on one side of a 135 g/m ² double-sided polyethylene-coated paper, and the opposite side was subjected to corona discharge machining.
An antihalation layer containing carbon black was provided, and an ortho-sensitized high-sensitivity silver chloride emulsion containing silica particles having an average particle size of 5 μm was coated thereon at 1.0 g/m ² as silver nitrate. The antihalation layer and the emulsion layer contain formalin as a hardening agent. After drying and heating at 40° C. for 3 days, palladium sulfide sol prepared by the method described below was applied onto this emulsion layer at a speed of 5 m/min. Preparation of palladium sulfide sol Solution A Palladium chloride hydrochloric acid solution 5g 40ml 1 Solution B Sodium sulfide solution 8.6g 1 Mix solutions A and B with stirring, and after 30 minutes add ion exchange resin made for pure water production. It was purified by passing it through a column, and liquid C was added to prepare a coating liquid. (Adjusted to pH 4) Liquid C No. 3 Polymer 10% Saponin Aqueous Solution of JP-A No. 53-21602 10g 20.0ml 18 Plate-making camera CP-404 which has an image reversal mechanism in the lithographic printing plate master thus obtained (manufactured by Mitsubishi Paper Industries), image exposure was carried out, and development was carried out at 30° C. for 1 minute by immersion in the following silver complex salt diffusion transfer developer. Transfer developer water 750ml Potassium hydroxide 20g Anhydrous sodium sulfite 50g Hydroquinone 10g 1-phenyl-3-pyrazolidone 1g Sodium thiosulfate 10g Add water to make 1. 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. Neutralized liquid water 600ml Citric acid 10g Sodium citrate 35g Colloidal silica (20% liquid) 5ml Ethylene glycol 5ml Add water to make 1. The lithographic printing plate prepared by the above procedure was mounted on an offset printing machine, the following desensitizing liquid was applied all over the plate surface, and printing was carried out using the following dampening liquid. Desensitized liquid water 600ml Isopropyl alcohol 400ml Ethylene glycol 50g 3-mercapto-4-acetamide-5-n-
Heptyl-1,2,4-triazole 1g Humidifying liquid O-phosphoric acid 10g Nickel nitrate 5g Sodium sulfite 5g Ethylene glycol 100g Colloidal silica (20% liquid) 28g Add water to make 2. The printing machine is AB Deitsku 350CD (A.
A B. Dick offset printing press (trademark) was used. The photographed manuscript contained ruled lines from 10 μm to 200 μm prepared for evaluation, and an exposure amount was given to reproduce the 200 μm ruled lines as they were on the printing plate when photographed at full size. The silver halide in the silver halide emulsion layer of the lithographic printing plate mentioned above is 0.6, 0.4 and
It was produced in the same manner, processed and printed in the same manner, except that it was coated at 0.2 g/m ² . The results for each print version were as follows.

[Table] The evaluation details are as follows. Ink receptivity: Paper feeding begins as soon as the inked roller comes into contact with the plate surface, and evaluation is performed by the number of sheets until a print with good image density is obtained. Image reproducibility: The minimum reproducible ruled line width when given appropriate exposure (the amount of exposure necessary to reproduce a 200 μm ruled line), expressed in μm. Printing durability: Expressed as the number of sheets printed when printing becomes impossible due to either poor ink adhesion in the image area or background smearing. Example 1 5 g/carboxymethyl cellulose was added to the transfer developer shown in Reference Example, and the liquid was filled into a roller liquid-lift type developing machine to the extent that the lower part of the rotating roller was immersed in the liquid. Subsequently, the printing plates A to D shown in the reference example were exposed in the same manner as in the reference example, moved in the same direction as the rotation direction of the roller, and the processing liquid lifted by the roller was supplied to the printing plate surface, and then,
Excess processing liquid was removed, and printing was then carried out in the same manner as in the reference example. The results are shown in Table 1.

[Table] Printing plate A is not affected much by the development method, but printing plates B to D have improved ink receptivity and image reproducibility by using the coating method compared to the dipping method of the reference example. It is clear that this is a significant improvement, and it is understood that the present invention is extremely effective for lithographic printing plates with low silver content. The liquid raising roller can be one or more (rotating directions may be the same or opposite), and the amount of liquid lifting can be adjusted as appropriate depending on the characteristics of the printing plate, the composition of the transfer developer, etc. can. Example 2 A negative type lithographic printing plate using a direct positive silver chlorobromide (95 mol % or more silver bromide) emulsion was produced in exactly the same manner as described in Example 1 of JP-A-52-112402. However, the amount of coated silver is 1.5g/m ² (printing version E) or 0.5g/m ² as silver nitrate per square meter.
(Printing plate F) The only difference is that the emulsion was applied so that it became (printing plate F). The results of printing the printing plates E and F according to the reference example are shown in the upper row of Table 2, and the results of printing the printing plates E and F according to Example 1 are shown in the lower row of Table 2.

[Table] Example 8 Hydroquinone and 1-phenyl-3-pyrazolidone were added to the physical development nucleus layer of printing plates A to D shown in Reference Examples, and 2-mercaptobenzoin as a silver halide solvent was added to the silver halide emulsion layer. Four types of printing plates were produced in the same manner except that acid was added. When these printing plates were printed according to Reference Example and Example 1 except that the following transfer developer was used, exactly the same results were confirmed. Transfer developer water 750ml Potassium hydroxide 20g Anhydrous sodium sulfite 50g Carboxymethyl cellulose 7g 2-phenyl-5-mercaptooxathiazole 0.15g Add water to make 1.

Claims (1)

[Claims] 1. A plate-making method for a lithographic printing plate that uses a transferred silver image formed by a silver complex diffusion transfer method as an ink receptivity, using an emulsion layer containing silver halide equivalent to 4 mmol or less of silver per square meter. A method for making a lithographic printing plate, which comprises applying and supplying an alkaline processing solution for diffusion transfer development onto the plate surface in an amount necessary for substantially developing the plate.