JP2003287891A - Planographic printing plate for scanning exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planographic printing plate for scanning exposure having good preservability. <P>SOLUTION: In the planographic printing plate obtained by sequentially coating the top of a support with at least an undercoat layer, a silver halide emulsion layer containing a sensitizing dye which imparts maximum spectral sensitivity in a wavelength region of ≥600 nm and a physical developing nucleus layer, an aliphatic carboxylic acid having at least one hydroxyl group or an alkali metallic salt thereof is contained. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type lithographic printing plate utilizing a silver complex salt diffusion transfer method suitable for using laser light as a light source. [0002] A lithographic printing plate using a silver complex salt diffusion transfer method (DTR method) is disclosed in, for example, US Pat. No. 3,728,114.
Nos. 4,134,769 and 4,160,67
No. 0, No. 4,336,321, No. 4,501,8
No. 11, 4,510,228 and 4,621,
No. 041, etc. According to this, the exposed silver halide crystal undergoes chemical development by DTR development to become black silver, forming a hydrophilic non-image area,
On the other hand, unexposed silver halide crystals are converted into a silver salt complex by the silver salt complexing agent in the developing solution and diffused to the physical development nucleus layer on the surface. An image portion mainly composed of physically developed silver is formed. In recent years, with the spread of CTP (computer to plate), a lithographic printing plate for scanning exposure corresponding to an output machine having a light source such as a helium / neon laser, an argon laser, a semiconductor laser, and a light emitting diode has been developed. It has become widely used. For example, U.S. Pat. No. 4,501,811 and JP-A-59-7105.
5, No. 59-71056, No. 60-61752, No. 60-75838, No. 60-100148, No. 6
JP-A-114235 and JP-A-63-47756 disclose lithographic printing plates used for helium / neon lasers, argon ion lasers, semiconductor lasers, light emitting diodes, and the like. However, as described in the above-mentioned patent specification, in a lithographic printing plate utilizing a silver complex salt diffusion transfer method, the surface physical development nucleus layer has a large effect on the spectral sensitization, so that the target laser The sensitivity to light is reduced, the storage stability is deteriorated, and as a result of forming a soft transferred silver image by silver complex salt diffusion transfer development, the sharpness, the resolving power is reduced, and further background smearing occurs,
Since a silver image is removed during printing and sufficient printing durability cannot be obtained, it has been difficult to obtain a target high-quality lithographic printing plate. Therefore, a sensitizing dye satisfying these requirements has not only a sufficiently high sensitivity at the wavelength of the laser beam, but also a good storage stability, and a high contrast transferable silver image can be formed. In addition, it must satisfy such conditions that there is no adverse effect such as background contamination, and that a strong transfer-precipitated silver which cannot be formed even during minute printing can be formed. [0005] Such properties are also influenced by factors such as the halogen composition of the silver halide emulsion, the silver halide grain size, the type and degree of chemical sensitization. Emulsions mainly composed of silver chloride as silver halide have the advantage that diffusion transfer development occurs promptly, and that transfer precipitation silver used as an ink receiving portion is easily generated. However, in general, the sensitivity is low, and if chemical sensitization is performed sufficiently to achieve high sensitivity, the sensitivity to laser light will be lower.If diffusion transfer development is too fast, the print strength of the transferred silver will be reduced. Tend to be weak. A lithographic printing plate having sensitivity to a scanning exposure light source having a wavelength of 600 nm or more has been developed to satisfy the above-mentioned various properties, but a sensitizing dye used for enhancing the photosensitivity of 600 nm or more has been developed. The time-dependent change of the lithographic printing plate coated with the emulsion prepared by using the emulsion was remarkably large as compared with other types, and there was a problem in storability. Various methods have been proposed for improving the storage stability. JP-A-6-130
No. 673, No. 7-159999 and the like, a method using a mercaptotriazole compound or a mercaptotetrazole compound, and in No. 7-36191, a method of adjusting the film surface pH to 3.0-4.0. 10-260535
No., 11-295897, 2000-2145
No. 89 and the like describe a method using latex and the like. However, it was not yet at a satisfactory level. SUMMARY OF THE INVENTION An object of the present invention is to provide a printing medium having a sufficiently good storage stability and excellent printing durability.
An object of the present invention is to provide a lithographic printing plate for scanning exposure having a maximum spectral sensitivity in the above wavelength range. [0008] At least an undercoat layer, a silver halide emulsion layer containing a sensitizing dye imparting maximum spectral sensitivity in a wavelength region of 600 nm or more, and a physical development nucleus layer are sequentially formed on a support. This is achieved by including in a lithographic printing plate obtained by coating an aliphatic carboxylic acid having at least one hydroxyl group or an alkali metal salt thereof. DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail. The aliphatic carboxylic acid having at least one hydroxyl group or an alkali metal salt thereof to be contained in the lithographic printing plate of the present invention is a monocarboxylic acid, dicarboxylic acid, tricarboxylic acid or the like having one or more hydroxyl groups or an alkali metal thereof. Salts, for example, lactic acid, tartaric acid, malic acid, citric acid, gluconic acid, etc., and the alkali metal salts are partially or wholly substituted with hydrogen ions of the carboxylic acid by an alkali metal such as lithium, sodium, or potassium. ing. The aliphatic carboxylic acid having at least one hydroxyl group or an alkali metal salt thereof to be contained in the lithographic printing plate of the present invention can be added to a silver halide emulsion layer (and / or an undercoat layer). A preferred amount is in the range of 0.0003 to 0.03 mol per mol of silver halide. In the present invention, the silver halide has a thickness of 600 nm.
Sensitizing dyes that impart maximum spectral sensitivity to the above wavelength regions are:
Helium neon laser, red semiconductor laser, red LE
Examples of sensitizing dyes for sensitizing the red region such as D include JP-A-2-251854, JP-A-3-274405, and JP-A-4-9.
Sensitizing dyes described in Nos. 853 and 9-244196,
As sensitizing dyes for sensitizing the near infrared region of 700 nm or more for applications such as infrared semiconductor lasers, US Pat.
No. 5,854, No. 2,095,856, No. 2, 9
No. 55,939, No. 3,482,978, No. 3,
552, 974, 3,573,921, 3,582,344, and 3,623,881, and the like. It is not limited to these. The addition amount can vary over a wide range, but good results are obtained at 1 × 10 ^-6 to 1 × 10 ^-2 mol, more preferably 5 × 10 -4 to 1 × 10 ^-2 mol, per mol of silver halide. Can be obtained when a relatively large amount of a sensitizing dye is added. The optimum addition amount varies depending on the conditions of the silver halide emulsion, for example, the halogen composition, the average grain size of silver halide grains, crystal habit, and the like. Hereinafter, specific examples of the red sensitizing dye used in the present invention are shown in the following chemical formulas (1) to (4), and specific examples of the infrared sensitizing dye are shown in the following chemical formulas (5) to (7). It is not limited to these sensitizing dyes. Also, these sensitizing dyes can be used in combination. Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image The lithographic printing plate of the present invention contains gelatin and other high molecular compounds, and the layer containing the lithographic printing plate may be an undercoat layer, an emulsion layer, or a physical development nucleus layer. These gelatin-containing layers can be hardened with a gelatin hardener. Preferred hardeners are disclosed in
Aldehyde hardeners such as formalin, glyoxal, malealdehyde and glutaraldehyde described in 1-2202494, the amount of which is 0.05 to 50 mmol, preferably 0.1 to 10 mmol, per 1 g of gelatin.
mol. Aldehyde hardeners include other hardeners, for example, inorganic compounds such as chrome alum, N-methylol compounds such as urea and ethylene urea, and 2,4-dichloro-6-hydroxy. -S-triazine salt, 2,4
A compound having an active halogen such as -dihydroxy-6-chloro-S-triazine salt, divinyl sulfone, divinyl ketone or N, N, N-trichloroylhexahydrotriazine, an ethyleneimino group which is an active three-membered ring, Compounds having two or more epoxy groups in the molecule, various compounds such as dialdehyde starch as a polymer hardener, and the like can be used. Hardeners can be added to all layers or to some or only one layer.
Of course, in the case of two-layer simultaneous application, the diffusible hardener can be added to only one of the layers. The addition method can be added at the time of emulsion production or in-line at the time of coating. The gelatin in the gelatin-containing layer of the present invention is partially composed of another polymer compound such as water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, gum arabic, polyvinyl alcohol, polyvinyl pyrrolidone, It can be substituted with one or more hydrophilic polymers such as carboxymethylcellulose, polyacrylamide, styrene-maleic anhydride copolymer, and polyvinylmethylether-maleic anhydride copolymer. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer. The gelatin and / or high molecular compound of the undercoat layer of the present invention is generally 0.5 to 10 g / m ² , preferably 1 to 4 g / m ² . The undercoat layer may contain pigments such as carbon black, dyes and the like for the purpose of preventing halation. Further, a photographic additive such as a developing agent can be included. The undercoat layer is disclosed in JP-A-48-5503,
Nos. 100203 and 49-16507. The silver halide is silver chloride, silver chloroiodide, silver chlorobromide or silver chloroiodobromide containing 95 mol% or more of silver chloride. More preferably, it is silver chloroiodide containing 0.1 to 3 mol% of silver iodide. These silver halides contain rhodium salts in an amount of 1 × 10 ^-4 to 1 × 1 per mol of silver halide.
^0-8 mol, more preferably 1 × 10 ^-7 to 1 × 10 ^-8 mol, the iridium salt is added in an amount of 1 × 10 ^-7 mol per mol of silver halide.
^-4 to 1 × 10 ^-8 mol, more preferably 1 × 10 ^-6 to 1 ×
It preferably contains 10 ^-7 mol. The form, crystal habit and the like of the silver halide grains are not particularly limited, but those having a grain size of 0.2 μm to 0.4 μm are preferably used. The silver halide emulsion can be sensitized in various ways as it is manufactured or coated. It is preferred to chemically sensitize by methods well known in the art such as, for example, with sodium thiosulfate, alkyl thioureas, or with gold compounds such as rhodium gold, gold chloride, or a combination of both. The physical development nucleus layer present above the silver halide emulsion layer contains physical development nuclei containing a copolymer of acrylamide and methylstyrene substituted by guanylthiourea or the like. As physical development nuclei, silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold, platinum and other metal colloid fine particles, and sulfides, polysulfides, selenides of these metals, or those It may be a mixture or a mixed crystal. Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone, or catechol, or a known hardener such as formalin or dichloro-s-triazine. Each coating layer such as an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer may contain some of anionic, cationic or neutral surfactants as coating aids. And an antifoggant, a matting agent, a thickener, an antistatic agent, and the like. As the support of the lithographic printing plate of the present invention,
Paper or a synthetic or semi-synthetic polymer film, a metal plate of aluminum, iron, or the like can be used as long as it can withstand lithographic printing. The surface of the support may be coated on one or both sides with one or more polymer films or thin metal films. The surface of these supports can be subjected to a surface treatment in order to improve the adhesion to the coating layer. Particularly preferably used supports are paper coated on both sides or one side with a polyolefin polymer, a polyester film, a polyester film having a hydrophilized surface, an aluminum plate having been subjected to a surface treatment, and the like.
These supports may contain pigments for preventing halation and solid fine particles for improving the surface properties. Further, the support may be light-transmissive so that backside exposure is possible. The developing solution used in the present invention includes an alkaline substance such as sodium hydroxide, potassium hydroxide,
Lithium hydroxide, tribasic sodium phosphate, etc., sulfites as preservatives, silver halide solvents such as thiosulfate,
Thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines and the like, thickeners such as hydroxyethylcellulose, carboxymethylcellulose and the like, antifoggants,
For example, potassium bromide, compounds described in JP-A-47-26201, etc., developers such as hydroquinones, catechol, 1-phenyl-3-pyrazolidinone, etc., development modifiers such as polyoxyalkylene compounds, onium compounds, etc. Can be included. Furthermore, in the developing solution,
As described in U.S. Pat. No. 3,776,728, compounds that improve the ink running of the surface silver layer can be used. The surface silver layer after development of the lithographic printing plate of the present invention can be converted to ink receptivity or enhanced in receptivity with any known surface treating agent. Such a processing liquid is described in, for example, JP-B-48-29723 and U.S. Pat. No. 3,721,559. The printing method, the desensitizing solution, the humidifying solution, and the like to be used can be a commonly known method. EXAMPLES The present invention will be described below with reference to examples, but of course, the present invention is not limited to these examples. Example 1 A matted layer containing silica particles having an average particle size of 5 μm was provided on one side of a 100 μm-thick subbed polyethylene terephthalate base, and carbon black, 1-phenyl-4-methyl- 4-hydroxyl-3-
20% by weight of pyrazolidone and photographic gelatin
An undercoat layer containing silica powder having an average particle diameter of 4 μm and adjusted to pH 5.0, and after chemically sensitized with hypo and gold compounds, 2-mercaptobenzoic acid, and 5% by weight based on photographic gelatin. And a silver halide emulsion containing silica powder having an average particle size of 4 μm and adjusted to pH 5.0. The silver halide emulsion is added with 5 × 10 ^-6 mol of iridium salt and 5 × 10 ^-7 mol of rhodium salt per mol of silver halide during physical ripening. 0.33 μm, cubic silver chloride crystals in which 90% by weight or more of all grains are distributed within a range of ± 30% of the average grain size. At the end of physical ripening, iodide is added, and 1 mol% of iodine is added. The surface was replaced with silver halide. In the silver halide emulsion, (3)
The sensitizing dye shown in (10) was used as a solution and added in an amount of 4.times.10@-4 mol per mol of silver halide to obtain an appropriate sensitivity in a target wavelength range. To the silver halide emulsion prepared by the above method, sodium tartrate, sodium malate, and sodium citrate as the aliphatic carboxylate having at least one hydroxyl group of the present invention, without adding these as a comparison, After adding sulfuric acid as an inorganic acid as a comparative compound and sodium maleate and sodium oxalate as salts of an organic acid having no hydroxyl group, the pH of the emulsion was again adjusted.
Was adjusted to 5.0 to obtain Samples 1 to 7. [Table 1] ──────────────────────────────────── Sample No. Compound addition amount Remarks １ 1 Sodium tartrate 5 mmol This invention 2 Sodium malate 5 mmol Invention 3 Sodium citrate 5 mmol Inventive 4 None Comparison 5 Sulfuric acid 5 mmol comparison 6 Sodium maleate 5 mmol comparison 7 Sodium oxalate 5 mmol comparison The gelatin of the undercoat layer was 3.0 g / m ² , the gelatin of the silver halide emulsion layer was 1.0 g / m ² , Coating was performed at a converted silver halide of 1.2 g / m ² . The undercoat layer and the silver halide emulsion layer contain formalin as a hardening agent in an amount of 5.0 mg / g gelatin based on gelatin. After drying, the mixture was heated at 50 ° C. for 1 hour and 2 days.
A lithographic printing plate was prepared by applying a liquid which was added to the core coating solution described in Example 1 of the specification of No. 5 so as to have a hydroquinone concentration of 0.7 g / m ² . Each of the lithographic printing plates was prepared at 50.degree. H. The sample after preservation heated for 6 days and the unheated sample were prepared. An original was printed on the lithographic printing plate with a laser diode scanner FT-R3050 (manufactured by Dainippon Screen Mfg. Co., Ltd.) which emits light at 633 nm, and this was used as a printing sample. Each of the image-exposed printing plates was developed with the following developers at 30 ° C. for 15 seconds. <Transfer developer> Water 700 ml Sodium hydroxide 18 g Potassium hydroxide 7 g Anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1 g Uracil 10 g 2-methylaminoethanol 30 g 5-phenyl-2-mercapto 0.1 g-1,3 1 g of potassium 4-oxadiazole bromide Add water to make 1 liter. After the development processing, the original plate is passed between two squeezing rollers to remove the excess developer, and immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds. Removed and dried at room temperature. <Neutralizing solution> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% solution) 5 ml Ethylene glycol 5 ml Add water to make 1 liter. The lithographic printing plate created by the above operation is mounted on an offset printing machine, and the following desensitizing solution is applied to the plate surface,
Printing was performed using the following humidifying solution. <Desensitizing liquid> Water 600 ml Isopropyl alcohol 400 ml Ethylene glycol 50 g 3-mercapto-4-acetamide-1 g 5-n-heptyl-1,2,4-triazole <humidifying liquid> o-phosphorus Acid 10 g Nickel nitrate 5 g Sodium nitrite 5 g Ethylene glycol 100 g Colloidal silica (20% solution) 28 g Add water to make 2 liters. The sensitivity of the obtained lithographic printing plate was represented by a value when the relative laser power of the unheated sample 4 without the compound for comparison was set to 100. A smaller value indicates higher sensitivity, and a larger value indicates lower sensitivity. As for the printing durability, 50 ° C. and 80% R.C. H. The plate after heating for 6 days was printed using Ryobi 3200CD (manufactured by Ryobi KK).
Judged. ABdick3-1012 was used as the ink. Table 2 shows the sample contents and results of each lithographic printing plate. [Table 2] ──────────────────────────────────── Sample No. Sensitivity (laser power ) Printing durability Remarks Unheated 50 ℃ 80% RH 50 ℃ 80% RH After heating for 6 days After heating for 6 days６ ───────────── 1 102 105 20,000 sheets or more The present invention 2 98 102 20,000 sheets or more The present invention 3 103 102 20,000 sheets or more The present invention 4 100 159 7000 sheets Comparison 599 157 7,000 sheets comparison 6 101 138 10,000 sheets comparison 7 103 141 8,000 sheets comparison As is clear from the above results, the lithographic printing plate of the present invention has no reduction in printing durability due to heating at 50 ° C. and 80% RH for 6 days after nucleus coating, and has no sensitivity change. Also small It can be seen that an excellent printing plate storage stability. According to the present invention, a lithographic printing plate for scanning exposure having a sufficiently high storage stability and a maximum spectral sensitivity in a wavelength region of 600 nm or more, which is excellent in printing durability, can be obtained. It is possible to obtain.

Claims (1)

Claims 1. An undercoat layer having a thickness of at least 600 nm on a support.
In a lithographic printing plate obtained by sequentially applying a silver halide emulsion layer containing a sensitizing dye imparting maximum spectral sensitivity to the above wavelength region and a physical development nucleus layer, an aliphatic carboxylic acid having at least one hydroxyl group or A lithographic printing plate for scanning exposure, comprising the alkali metal salt.