JPS6152466B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for making a lithographic printing plate using a silver complex salt diffusion transfer method, and more particularly to a method for making a lithographic printing plate with significantly improved printing durability. Disadvantages associated with lithographic printing plates made by the silver complex diffusion transfer method (DTR method) include, for example, insufficient resistance to mechanical abrasion, and the hydrophobic areas carrying the ink image gradually deteriorate. This results in a loss of ink receptivity, resulting in a decrease in printing durability. Furthermore, the hydrophilic areas gradually become hydrophobic, so that the non-imaged areas or areas become smeared with ink. Furthermore, the uniform greasy ink receptivity in the hydrophobic image areas is compromised, which causes variations in the ink receptivity in said image areas, so that the areas to be printed do not receive a uniform amount of ink. Become. Printing plates that apply the DTR method and use the formed metallic silver pattern as ink receptivity are already known (for example, U.S. Pat. No. 3,220,837, U.S. Pat. No. 3,721,559).
No., Special Publication No. 16725, No. 48-30562, No. 1672
4482, 1973-21602, etc.), although some of them have been realized, they still have the above-mentioned drawbacks. As with other planographic printing plates, the printing durability of planographic printing plates to which the DTR method is applied is required to be increased by changing the composition of the plate material, the composition of the processing liquid, printing conditions, etc. The influence of the state of developed silver particles on the printing characteristics of a printing plate is one of the major factors. In order for the silver particles transferred and developed by the DTR method to have better printing durability, the conditions for producing the transferred silver particles, For example, important factors include the diffusion rate, stability, and reduction rate of the silver complex salt, as well as the size and shape of the developed silver particles obtained thereby. JP-A No. 47-26201 discloses that ink loading in the early stages of printing is improved by using a transfer developer consisting essentially of a developing agent, a silver halide solvent component, and an organic compound having a mercapto group or a thione group as its basis. It is stated that good quality of printed matter can be obtained. However, in order to maintain the characteristics of lithographic printing plates produced by the DTR method, such as excellent image reproducibility and high photosensitivity suitable for direct plate-making, there is still an unsatisfactory level in order to achieve higher printing durability. However, there is a need for a dramatic improvement in printing durability. On the other hand, effective use of silver resources is required, and therefore it is desirable to use as little silver as possible in the silver halide emulsion layer, but as the amount of silver is reduced, printing durability generally deteriorates. It is desired to provide a lithographic printing material with improved printing durability despite a low silver content and a plate-making method thereof. In addition to the method of diffusion transfer development using an alkaline processing solution containing a developing agent such as hydroquinone as described in JP-A No. 47-26201, there is also a method in which a developing agent is contained in the lithographic printing material and substantially the developing agent is A method is known in which diffusion transfer development is carried out using an alkaline processing solution that does not contain a so-called alkaline activating solution.
The method using an alkaline activating solution has the advantage that the durability of the processing solution is significantly improved because air oxidation of the developing agent can be essentially avoided. The amount of printing material to be processed naturally increases, and the number of plates to be made with a tired alkaline activating solution also increases.Therefore, there is a risk that the printing properties are likely to be unsatisfactory. There is also a demand for a plate-making method that does not reduce printing properties, especially printing durability. An object of the present invention is to provide a method for making a lithographic printing plate using a silver complex diffusion transfer method, which dramatically improves printing durability. Another object of the present invention is to provide a lithographic printing material with high printing durability suitable for treatment with an alkaline activating liquid and a plate-making method thereof. Still another object of the present invention is to provide a lithographic printing material with a low silver content and a plate-making method thereof, which has significantly improved printing durability. Further objects and advantages of the present invention will be understood from the following description. As a result of extensive research to achieve the above objective, the present inventors have discovered that a specific organic compound dramatically improves printing durability, unlike conventionally used organic compounds. It has been found that the lower the silver content of the lithographic printing material, the more useful it is. The present invention was achieved by performing a diffusion transfer development treatment in the presence of a specific organic compound in a method for making a lithographic printing plate using a silver complex diffusion transfer method. The compound used in the present invention has a thione group that does not undergo enolization, and next to the thione group,

It has a substituted nitrogen atom represented by [Formula], and the remainder is a 5- or 6-membered heterocycle selected from carbon, nitrogen, oxygen, and sulfur atoms that may have substituents represented by R. consisting of the atomic groups necessary to form a ring, the ring does not have an aromatic fused ring, and R is a substituent having 1 to 4 carbon atoms or having no carbon atoms. It is a thione compound. The characteristics of the compound used in the present invention are (1) having at least one thione group that does not undergo enolization, (2) being a heterocyclic compound having no aromatic condensed ring, and (3) adjacent to the thione group. (4) none of the substituents must have a group having 5 or more carbon atoms, such as an alkyl group or an aryl group;
It is. Examples of substituents on the nitrogen atom adjacent to the thione group that does not enolize include substituents that can be bonded to the nitrogen atom through a carbon atom, oxygen atom, sulfur atom, or nitrogen atom; It has been found that having five or more carbon atoms not only fails to achieve the object of the present invention, but also impairs various properties as a lithographic printing plate. Specific examples include alkyl groups having 1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, 2-sulfoethyl, carboxymethyl, 2-carboxyethyl, 2-hydroxyethyl, 2-methoxyethyl, methoxycarbonylmethyl, chloroethyl,
Methanesulfonamidoethyl, etc.), N-C bond substituents such as alkenyl groups (allyl groups, etc.), N-C bond substituents such as hydroxyl groups, acyl groups (acetyl groups, etc.), and alkylcarbonyloxy groups (acetoxy, propionyloxy, etc.) O-bond substituents, N-N bond substituents such as amino groups (amino, methylamino, diethylamino, etc.), ureido groups (N,N-dimethylureido, etc.), thioureido groups, alkylcarbonylamino groups (acetamide, etc.) , a methylthio group, and the like, but are not limited thereto.
The carbon atom or nitrogen atom forming the heterocycle may also have a substituent as described above, and furthermore, for example, a saturated ring may be formed in which the carbon atoms at the 4th and 5th positions in a 5-membered heterocycle are connected by a methylene chain. You can also. It can also be a bis-isomer in which, for example, atoms at the 3rd, 4th, or 5th positions are bonded with, for example, a methylene chain. The methylene chains at the 4- and 5-positions or the methylene chains in the bis form can be simply counted as 1/2 of the number of carbon atoms in the substituent. The compound used in the present invention can be represented by the following general formula (1). General formula (1) Z is an atomic group necessary to form a 5- or 6-membered ring selected from C, N, O, and S atoms; R is a substituent as defined above, each of which may be different;
n represents an integer from 1 to 4. Representative examples of thione compounds used in the present invention are shown below.

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] Approximately 10mg/~5g/in the case of diffusion transfer processing liquid
about 0.5 mg per square meter in at least one of the constituent layers in the case of printing materials.
It can be used in a range of about 1 g, and two or more kinds of compounds can also be used in combination. Of course, other organic compounds having mercapto or thionic groups can also be used. Japanese Patent Publication No. 48-29723 discloses that ink receptivity can be enhanced by applying an organic compound having a mercapto group or a thione group to the surface of a printing plate after development by the DTR method. The thione compound used in the present invention can also improve ink receptivity to a certain extent by applying it to the transferred silver after development, but compared to the organic compounds specifically shown in Japanese Patent Publication No. 48-29723, For example, ink receptivity is poor. In order to improve ink receptivity, it is preferable that these organic compounds have a relatively lipophilic group, such as an alkyl group or a phenyl group having a large number of carbon atoms. It is thought that the same applies to the organic compound described in JP-A No. 47-26201 mentioned above. However,
By making the thione compound with a specific structure used in the present invention exist in a diffusion transfer developer and/or a lithographic printing material and performing a development process using the DTR method, it is possible to obtain a thione compound with a specific structure that cannot be obtained using the organic compound shown in the above patent. It was discovered that a dramatically high level of printing durability could be obtained, and the present invention was developed based on this discovery. It is believed that the thione compound used in the present invention has a unique effect so that the printability of the transferred silver particles is extremely satisfactory during diffusion transfer development. Particularly preferable examples of the lithographic printing plate used in the present invention are JP-B No. 48-30562, JP-A No. 48-16725, and JP-A No. 48-16725.
53-21602, etc., the physical development core particles are not buried in the binder, but are partially exposed on the surface. As the developing agent in the lithographic printing material for activation treatment, known ones such as dihydroxybenzenes such as hydroquinone and 3-pyrazolidones such as 1-phenyl-3-pyrazolidone can be used in any amount range. can. Generally, hydroquinone is 0.2 to 2 per square meter.
g/m ² , preferably 0.3 to 1.5 g/m ² , per square meter for 1-phenyl-3-pyrazolidone
It ranges from 0.01 to 1 g/m ² , preferably from 0.02 to 0.5 g/m ² . The developing agent can be used in at least one layer containing a hydrophilic binder, such as a silver halide emulsion layer, an antihalation layer, and a layer containing physical development nuclei. Although the present invention is preferably applied to processing with an alkaline activating solution, processing with an alkaline developer containing a developing agent may also be applied. The silver halide emulsion used in the present invention can be any of silver chloride, silver bromide, silver chlorobromide, and silver halides made of these and silver iodide, and particularly preferably silver chloride is about 70% silver halide in a mole % or more. The size of silver halide sulfur,
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, 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, such as albumin, casein, polyvinyl alcohol, sodium alginate, carboxymethyl cellulose, etc. Good too. The weight ratio of hydrophilic colloid to silver halide, expressed as silver nitrate, is generally from 0.2 to 5, preferably from 0.2 to 2.0. The amount of silver halide present on the support is coated to equal about 0.1 g to about 5 g/m ² , preferably 0.2 to 3.0 g/m ² of silver nitrate. As previously mentioned, lithographic materials having silver halide equivalent to silver nitrate of less than about 1 g/m ² , preferably less than about 0.8 g/m ² are particularly useful.
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. The support may be a polypropylene film, a polyethylene terephthalate film, 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 also contain antihalation dyes or pigments. Such supports are
It can also be used for materials that do not have a silver halide emulsion layer, such as, but have a physical development nucleus-containing layer (image-receiving layer) that can be used as a printing plate. In a lithographic printing material having both a silver halide emulsion layer and a physical development nucleus layer on the same support, either of them may be placed on top, but preferably the physical development nucleus layer (image-receiving layer) is preferably in the upper 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 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. Additionally, the image-receiving layer may also contain pigments for preventing scumming, such as barium titanium sulfate dioxide, china clay, and silver, and hardeners, such as formaldehyde. The diffusion transfer processing solution used in the present invention contains an alkaline substance such as sodium hydroxide, potassium hydroxide, sodium triphosphate, etc., a silver halide solvent such as sodium thiosulfate, potassium thiocyanate, 2-mercaptobenzoic acid, cyclic imide compounds, alkanolamines, etc., sulfites as preservatives, thickening agents such as hydroxyethylcellulose, carboxymethylcererose, antifoggants such as potassium bromide, developing agents such as hydroquinone, 1-phenyl-3-pyrazolidone. ,
Development modifiers such as polyoxylalkylene compounds, onium compounds, etc. can be included. The PH of the diffusion transfer processing solution can range from about 10 to 14. The ink receptivity of the lithographic printing plates produced according to the invention can be enhanced with compounds such as those described in Japanese Patent Publication No. 48-29723, 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 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 135 g/m ² double-sided polyethylene-coated paper, and the opposite side was subjected to corona discharge machining.
An antihalation layer (gelatin 3.5 g/m ² ) containing carbon black and 1-phenyl-3-pyrazolidone (0.2 g/m ² ), on which ortho-sensitized silica particles with an average particle size of 5 μm is provided. 1.8 as silver nitrate
It was applied at g/m ² . The antihalation layer and emulsion layer contain formalin as a hardening agent. After drying and heating at 40°C for 3 days, a palladium sulfide sol containing polymer No. 3 and hydroquinone (0.7 g/m ² ) described in JP-A-53-21602 was coated on the emulsion layer, and a lithographic plate was applied. Printing materials were produced. The lithographic printing plate master thus obtained was subjected to image exposure using a letterpress camera having an image reversal mechanism, and the following silver complex salt diffusion transfer developer was used at 30°C for 10 minutes.
A minute development process was performed. <Transfer developer> Water 700ml Potassium hydroxide 20g Anhydrous sodium sulfite 50g 2-mercaptobenzoic acid 1.5g 2-methylaminoethanol 15g Organic compound 1.0g Add water to make a total volume of 1. The above organic compounds represent thione compounds used in the present invention and comparative compounds, and are as shown in Table 1 showing the printing results. 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. 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. <Degreasing 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. The printing machine is A. B. Deitsuku 350CD (AB
Using Dick's offset printing machine trademark),
Table 1 shows the results of evaluating ink receptivity and printing durability using the following methods. 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. 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.

[Table] Compounds A to K used for comparison are as follows. The results shown in Table 1 clearly show that the thione compounds of the present invention show a marked improvement in printing durability compared to comparative compounds A to K. Some comparative compounds inhibit the precipitation of transfer silver and even lower ink receptivity and printing durability than those containing no organic compounds, which explains the uniqueness of the compounds used in the present invention. be done. Example 2 A lithographic printing material was produced according to the method described in Example 1, except that the amount of silver nitrate was 0.6 g/m ² . Thereafter, the same operations as in Example 1 were performed, and the results shown in Table 2 were obtained. The results in Table 2 show that when the thione compound of the present invention is used even in printing plates with a low silver content, the printing durability is significantly improved, and even more remarkable improvement is observed compared to the comparative compound. It will be appreciated that it is useful in making lithographic printing plates. In addition, the lithographic printing plate obtained using the thione compound of the present invention reproduces fine line parts of the original better than the lithographic printing plate obtained using the comparative compound, and moreover, the fine line parts of the original are better reproduced. It endured long printing without mechanical wear.

[Table] Comparative compounds L to N are as follows. Example 3 The lithographic printing material of Example 1 was treated with each of the processing solutions B, E, G and Q of Example 1, and the photographic properties (contrast, etc.) and printing properties (printing durability, etc.) of the transfer silver were evaluated as printed matter. Number of printing plates processed until the quality of Example 1 can no longer be maintained (B4
(Judgment) was investigated. The results are shown in Table 3.

[Table] The number of printing plates that can be processed is significantly increased compared to Comparisons G and Q, and by using the thione compound of the present invention in a more durable alkaline activation solution (processing solutions B and E). This can make it seem possible. Example 4 The printing material of Example 1 was treated in accordance with the method of Example 1 with 0.8 g of Exemplified Compounds 7, 24, or 35 contained in the following diffusion transfer treatment solution, and then tested in the same manner. did. <Transfer developer> Water 700ml Potassium hydroxide 25g Anhydrous sodium sulfite 60g Sodium thiosulfate 10g Thione compound 0.8g Potassium bromide 1.0g Add water to bring the total volume to 1. As in Example 1, many clear prints without background stains were obtained. Example 5 Example 1 was repeated. However, the printing material was prepared by including the organic compound in the physical development nuclear sol solution at a concentration of 15 mg per square meter, and processing solution Q was used. Similar results as in Example 1 were obtained. Similar results were also obtained when treatment liquids B, E, or G were used.

Claims (1)

[Scope of Claims] 1. In a method for making a lithographic printing plate using a silver complex diffusion transfer method, the plate has a thione group that is not enolized and has a substituted nitrogen atom represented by the formula next to the thione group. The remainder consists of the atomic group necessary to form a 5- or 6-membered ring selected from carbon, nitrogen, oxygen, and sulfur atoms optionally having substituents represented by R, and The ring does not have an aromatic condensed ring, and the above R is 1
A process for making a lithographic printing plate, which comprises carrying out a diffusion transfer development treatment in the presence of a thione compound which is a substituent having ~4 carbon atoms or no carbon atoms.