JPH0345374B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention is an improved method for improving the printing properties of offset printing plates obtained by applying the silver complex diffusion transfer method, particularly water retention, control of staining, and ink receptivity. It is related to. (B) Prior art and its problems Normally, in lithographic printing, both water and ink are supplied to the plate surface, and the image area (consisting of lipophilic areas that easily accept ink) is filled with colored ink. of,
Non-image areas (consisting of hydrophilic areas that do not accept ink but accept water) are created by selectively accepting water and transferring the ink on the image to a substrate such as paper. Therefore, in order to obtain good printed matter, the difference in lipophilicity and hydrophilicity between the surface of the image area and the background non-image area must be sufficiently large, and when water and ink are applied, the image area must receive a sufficient amount of ink. It is necessary that the receiving and non-printing areas do not accept ink at all. In general, the water retention capacity of a lithographic printing plate, that is, the occurrence of printing stains, is not caused by a single cause, but is caused by a combination of various factors.
It is well known in the industry. For example, this may be due to the inherent properties of the plate material, or may be due to the printing ink, dampening water, or printing paper, or the condition of the printing press, or the temperature and humidity at the time of printing. This may be due to the influence of environmental conditions such as Therefore, it is important to properly maintain these conditions and environment during printing. However, from a practical point of view, materials are required that can be printed under as wide a range of conditions as possible. A disadvantage of lithographic printing plates made by the silver complex diffusion transfer method (DTR method) is that they have insufficient resistance to mechanical abrasion, and the hydrophobic areas that carry the ink image gradually lose their ink receptivity. This is to reduce the printing durability in order to lose the printing quality. Furthermore, the hydrophilic areas gradually become hydrophobic, and the non-image areas become smeared with ink. Furthermore, the uniform greasy ink receptivity in the hydrophobic image areas is compromised, which induces variations in ink receptivity in the image areas, such that the printed area is unable to accept a uniform amount of ink. Printing plates that utilize the metallic silver pattern formed by the DTR method as ink receptivity are already known.
(For example, U.S. Pat. No. 3,220,337; U.S. Pat. No. 3,721,559,
16725-16725, 30562-30562, 30562-3056-
4422, 1983-21603, etc.) Although some of them have been put into practical use, they still have the above-mentioned drawbacks. (C) Purpose of the Invention The purpose of the present invention is to chemically alleviate the loss of hydrophobic and hydrophilic portions caused by mechanical abrasion of lithographic printing plates, improve water retention, and thereby control staining. This should be done in consideration of the chemical structure, or physical properties, of the organic solvent used. The object of the invention is achieved as follows. (D) Structure of the invention A lithographic printing plate using transferred silver by a silver complex salt diffusion transfer method as an ink receiving part, the printing plate having a silver halide emulsion layer and a physical development nucleus layer on a support, and A solvent having a solubility in water (40°C) of 10% or less and having the general formula described in [] and/or [] is contained in both layers or one layer in an amount of 1 to 10 mg per ¹ m2. This is a coated printing plate material. [] R ¹ O-CH ₂ CH ₂ OX (In the formula, R ¹ represents an alkyl group, an aryl group, an aralkyl group, a heterocyclic residue, or an alkenyl group; or X represents hydrogen or a lower acyl group.) R ² -Y-R ³ In the formula, R ² and R ³ may be the same or different,
Each represents an alkyl group or an aryl group. Moreover, Y is a divalent group,

【formula】

【formula】

[Formula] is shown. Here, R ⁴ represents a lower alkyl group. For example, with cyanine dyes such as sulfoanion and sulfobetaine sensitizing dyes dissolved in a solvent (water, alcohol, DMF, etc.),
% or less and a solvent having a hydroxyl group, an ester group, or a keto group with a high vapor pressure (however, the total number of carbon atoms is n≧3). The solvent used in the present invention is dissolved in this while taking into account the amount of the sensitizing dye that can be completely dissolved at 40° C. or higher, and the solution is added to the silver halide emulsion and adsorbed. Furthermore, when producing the physical development nucleus layer, it can also be used together with a solvent that dissolves the development nucleus and the developing agent. The present invention is characterized by the fact that the organic solvent has both hydrophilic and lipophilic properties, and by incorporating it into the emulsion layer or the development nucleus layer, it is possible to control the water retention of offset printing plates, that is, ink staining. can be improved. Furthermore, considering the physical properties, the amount of colloid used can be reduced, and the amount of sensitizing dye can be reduced.
Adsorption to AgX can also be increased. Therefore, it also has the advantage that the same sensitivity can be reproduced even if the amount of dye is reduced. Next, specific examples of the solvent used in the present invention will be shown. 1 Ethylene glycol monoethyl ether 2 Ethylene glycol monopropyl ether 3 Ethylene glycol monobutyl ether 4 Ethylene glycol monophenyl ether 5 Cellosolve acetate 6 Ethyl butyl ketone 7 Isobutyl acetate 8 Methyl phenyl carbinol The optimum usage amount of the solvent is 30 to Available at 60mg/ ^m2
Use of ^more than 100 mg/m2 may cause problems in coating properties.
Deteriorates DTR developability. When the emulsion layer contains the solvent, it is used by adding it to the following typical sensitizing dye solutions. Specific examples of the dye will be shown, but the invention is not limited thereto. As the silver halide emulsion of the lithographic printing plate of the present invention, any silver halide consisting of silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, or silver chlorobromoiodide can be used, and in particular, Preferably, about 50 mole percent silver chloride
or more silver halide. There are no restrictions on the size, crystal habit, distribution, etc. of the silver halide grains, 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, and the like may be added as appropriate. The binder for the silver halide emulsion is preferably gelatin, although some or all of the gelatin may be replaced with other natural and/or synthetic hydrophilic colloids, such as albumin, casein, polyvinyl alcohol, sodium alginate, sodium salt of carboxymethylcellulose, etc. You can leave it there. 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, calmium, 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 contains 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, 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. The present invention will be explained below with reference to examples, but of course it is not limited thereto. (E) Example A matting layer containing silica particles with an average particle size of 5 μm was provided on one side of a subbed-treated polyester film support, and the opposite side contained carbon black, with a weight of 20% by weight relative to photographic gelatin. An anti-halation 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 chloride emulsion layer (adjusted to PH4.0) containing % by weight
and has been established. The undercoat layer and emulsion layer were coated at a rate of 3.0 g/m ² of gelatin in the undercoat layer, 1.0 g/m ² of gelatin in the emulsion layer, and 1.0 g/m ² of silver halide converted to silver nitrate. It contains 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. Silver halide is silver iodide 2
Silver iodochloride emulsion containing mol% (this silver halide is a cubic crystal with an average grain size of 0.3 μm and more than 90% of the total grain number distributed within ±30% of the average grain size) The emulsion is divided after chemical ripening using the usual gold sensitization method and sulfur sensitization method. As shown in Table 1 below, a predetermined amount of the solvent used in the present invention is added to a predetermined amount of a sensitizing dye solution completely dissolved in alcohol or the like. Ten types of lithographic printing plates were produced using the method described above, and the samples were divided to examine the following quality characteristics (spectral sensitivity printing characteristics). One was light wedge exposure using a sensitometer with a light source with a color temperature of 2666°K. the other one
The first was to use a camera processor CP-1 for the purpose of investigating the printing characteristics of a printing plate (offset master).
404- (manufactured by Dainippon Screen), the plate was exposed to light with a direct contact screen (manufactured by Dainippon Screen) in close contact with the plate, and developed. Development after exposure was carried out using the following diffusion transfer developer. <Transfer developer> Water 70ml Potassium hydroxide 20g Anhydrous sodium sulfite 50g 2-mercaptobenzoic acid 1.5g 2-methylaminoethanol 1.5g 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 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. Regarding the spectral sensitivity, the reflection density was measured using a densitometer manufactured by Macbeth, and the total sensitivity (white) was shown in Table 1. Table 2 shows the results of ink receptivity, stain evaluation (water retention), image reproducibility (sharpness and resolution), and printing durability of each sample as a printing plate. However, the characteristics of the sample were evaluated as follows. B. Ink receptivity characteristics: The paper starts feeding as soon as the inked roller comes into contact with the plate surface, and the number of prints until a print with good image density is obtained.Evaluation of stain (water retention): 3000 sheets were printed, and then Based on the degree of dirt on the printed matter, the following 3
Evaluated in stages. 1 Dark stains occur all over the area. 2 Partial or light stains occur. 3 No stains occur at all. C Image reproducibility (sharpness and resolution) Image reproducibility is 100, 133, 150, 175 and 200 lines/
Ratings range from 1 (100 lines/inch) to 5 based on the number of screen lines on which fine halftone dots (5% dots) can be clearly reproduced.
(200 lines/inch). D. Printing durability: After printing 4,000 or more sheets, the printing durability is evaluated based on the number of sheets that cannot be printed due to stains or silver flying, based on the following criteria. 1 4000 sheets or less 2 4000-6000 sheets 3 6000-8000 sheets 4 8000-10000 sheets 5 10000 sheets or more

【table】

[Table] As can be understood from Tables 1 and 2 above, the samples according to the present invention exhibited extremely superior properties compared to the comparative samples, such as controlling stain generation and reproducing the same sensitivity with a smaller amount of dye. ing. In other words, it was found that the printing plate containing only the dye (,,) used for comparison was significantly inferior in terms of control of printing smearing compared to the printing plate containing the dye to which the solvent used in the present invention was added. Ta. Example 2 When preparing a lithographic printing plate similar to Example 1, the solvent used in the present invention was not contained in the emulsion layer, but the following nuclear solution, that is, a nucleus containing palladium sulfide coated on the emulsion layer, was used. The solvent was contained in the liquid layer. Preparation of palladium sulfide sol A solution Palladium chloride hydrochloric acid solution 5 g 40 ml 1 B solution Sodium sulfide solution 8.6 g 1 Mix A solution and B solution with stirring, and after 30 minutes, add to a column containing ion exchange resin for producing pure water. The solution was purified by passing through the solution, and the following solution C was added to prepare a coating solution. However, the solvent used in the present invention was added to Solution C. Liquid C Copolymer of methyl vinyl ether and maleic anhydride 10% saponin aqueous solution (1.25%) Table 3 shows the lithographic printing plate samples obtained in this way, the specified amount of solvent contained therein, and the results of printing characteristics. It was shown to. From the results in Table 3, it can be seen that the samples according to the present invention have extremely well controlled occurrence of printing stains compared to the comparative samples. Further, Table 4 shows the printing test results for representative samples obtained in Examples 1 and 2 when the printing plate of the present invention was stored under high temperature and high humidity conditions and when it was left to stand. As is clear from Table 4, the corresponding printing version is
It is understood that the printing properties, in particular, are extremely good in controlling stain generation, and furthermore, have high sharpness, high resolution, and high printing durability. Furthermore, it is understood that even when the samples according to the present invention are stored under harsh conditions, there is no deterioration in photographic and printing properties.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A lithographic printing plate using transferred silver by a silver complex diffusion transfer method as an ink-receiving part, the printing plate having a silver halide emulsion layer and a physical development nucleus layer on a support, and both layers or one layer contains a solvent having a solubility in water (at 40°C) of 10% or less and having the general formula shown in [] and/or [] in an amount of 1 to 100 mg per m ² Printing plate material coated with []R ¹ O-CH ₂ CH ₂ OX (In the formula, R ¹ represents an alkyl group, an aryl group, an aralkyl group, a heterocyclic residue, or an alkenyl group; and X represents hydrogen or a lower acyl group.) [] R ² -Y-R ³ (in the formula, R ² and R ³ may be the same or different,
Each represents an alkyl group or an aryl group. Or Y
is a divalent group and represents [Formula] [Formula] [Formula]. Here, R ⁴ represents a lower alkyl group. )