JP3375779B2 - Lithographic printing plate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing material to which a silver complex salt diffusion transfer method is applied. 2. Description of the Related Art A lithographic printing plate is composed of an oleophilic image portion that receives oily ink and an oil-repellent non-image portion that does not receive ink. Generally, the non-image portion is formed of water. It is composed of a hydrophilic part that accepts. In normal lithographic printing, both water and ink are supplied to the plate surface, the image portion selectively receives color ink, and the non-image portion selectively receives water, and the ink on the image line is, for example, paper or the like. Printing is performed by transferring to a printing medium. [0003] Therefore, in order to obtain good printed matter, the difference between the lipophilicity and the hydrophilicity between the image area and the non-image area is sufficiently large, and when the water and the ink are supplied to the printing plate, the image area is not sufficient. It is necessary to accept the amount of ink and not to accept the ink at all in the non-image area. A lithographic printing plate using a silver complex salt diffusion transfer method (DTR method), particularly a lithographic printing plate having a physical development nucleus layer on a silver halide emulsion layer, is disclosed, for example, in US Pat.
No. 8,114, No. 4,134,769, No. 4-1
No. 60,670, No. 4,336,321, No. 4,
Nos. 501,811, 4,510,228, and 4,621,041, and the like. The exposed silver halide crystal undergoes chemical development by DTR development to produce a black color. It becomes silver and forms a hydrophilic non-image area.On the other hand, unexposed silver halide crystals are converted into a silver salt complex by a silver salt complexing agent in a developing solution and diffused to the physical development nucleus layer on the surface to form nuclei. Causes physical development to form an image portion mainly composed of physically developed silver having ink receptivity. [0005] As described above, the lithographic printing plate requires gelatin-
Since the silver image deposited on the physical development nucleus layer on the silver halide emulsion layer is used as an ink-accepting image area, the image area is higher than that of a general lithographic printing plate (for example, PS plate). The parts have insufficient resistance to mechanical abrasion, and have the drawback that the image area is missing or the ink receptivity of the image area is easily lost. In order to overcome this drawback, the hardness of gelatin is increased, the abrasion resistance is improved by including a matting material in the undercoat layer or the silver halide emulsion layer, and the amount of physical development nuclei is increased. Then, soiling occurred. Further, there is a drawback in that when a lithographic printing plate is stored for a long period of time from production to plate making, scumming occurs and ink receptivity deteriorates. JP-A-5-80519, 5-66564,
5-80517, etc., various efforts were made to add water to latex to the undercoat layer to lower the surface roughness, and to make the water retention and ink detachability close to those of the PS plate. Latex is added to the main undercoat layer, and the ratio of gelatin is large to constitute the latex film, and it is difficult to obtain water resistance and low water absorption, which are characteristics of the latex film, and the undercoat layer swells and prints. Ink / water responsiveness was poor. In addition, there is a need for further improvement in development progress as a lithographic printing plate described in Japanese Patent Application No. 5-34028, for example, as a rapid, small-liquid development process. In order to improve water retention, Japanese Patent Application Laid-Open No.
77777 proposes to include pullulan in the physical development nucleus layer or / and adjacent layers,
Japanese Patent Application Laid-Open Nos. 4-277748, 5-88370, etc. have proposed hydrophilic polymers, but they have not yet reached a level of sufficient improvement. Also, ink ride,
Ink detachability was not sufficiently good. In order to improve the printing durability, Japanese Patent Publication No. Sho 62-
296143, JP-B-63-226658, 63
No. 249852, Japanese Patent Publication No. 1-261643, JP-A-5-100430, JP-A-5-80518, and JP-A-5-80518.
Nos. 80519 and 5-80520 propose various matting agent techniques, but they have not been satisfactory in terms of printing durability, water retention, ink lamination, printing quality, and scratch resistance. SUMMARY OF THE INVENTION An object of the present invention is to improve printing characteristics (printing durability, water retention, ink coverage, etc.), and particularly to improve water retention, ink detachability, and printing image quality. Another object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method.
Another object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method which is adaptable to rapid, small-liquid development processing. An object of the present invention is to provide a lithographic printing material to which a silver complex salt diffusion transfer method having at least an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer on a support is applied. In, the undercoat layer contains carbon black.
Contains hydrophilic polymer as binder
The main feature is that it contains polymer latex
It was achieved by a lithographic printing material. That is, the present inventor has described, as a photographic constituent layer,
The present inventors have found that printing performance can be remarkably improved by breaking the conventional wisdom of mainly using gelatin and mainly using latex, leading to the present invention. The latex used in the present invention is an aqueous dispersion of a vinyl polymer, and includes a styrene / butadiene latex, an acrylonitrile / butadiene latex,
Polybutadiene and styrene-butadiene-based latex, acrylate-based latex, vinyl chloride-based latex, styrene-isoprene-based latex, etc., and the amount of the latex used in the undercoat layer is 1 to 5 g / m ² by weight of the solid component, Preferably ^{2 to 4} g / m ²
It is. In order to further exert the effects of the present invention, various sizes and types such as a matting agent, a flat matting agent, and a spherical matting agent having an average particle size of 1.0 to 5.0 microns can be selected. Alternatively, the effect of the present invention can be further exerted by reducing the surface roughness Ra value to 0.6 or less by using them together. The amount of the matting agent is preferably 1 to 5 g / m
² , and more preferably in the range of 1.5 to 3.5 g / m ² . The center line average roughness Ra value of the lithographic printing plate is:
The surface roughness can be measured by using a surface roughness shape measuring instrument, for example, Surfcom 500B manufactured by Tokyo Seimitsu Co., Ltd. Extract a part of the measurement length l from the roughness curve in the direction of its center line,
When the center line of the extracted portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness curve is represented by y = f (x), the center line roughness Ra value is expressed in units of micrometers, and Can be calculated by the following equation. ## EQU1 ## On the other hand, Japanese Patent Application Laid-Open No. Hei 6-230575 proposes a combination of a methylolated form of acrylamide and a water-soluble polysaccharide. However, the effect of the polymer in the physical development nucleus layer can be further enhanced. , Water retention, ink detachability, and print quality can be improved. In the present invention, the amount of the hydrophilic polymer used in the undercoat layer is 15% by weight or less based on the total binder in the undercoat layer, and the content is 1 g / m ² or less, preferably 0.5 g / m ^{2. 2} or less, preferably 10% by weight
It is as follows. When the content exceeds 15% by weight, the ink releasability deteriorates, and the water retention and image quality gradually deteriorate. The term "ink detachability" as used herein means that printing may be started with little or no humidifying liquid on the plate surface in web offset printing and color printing. In this case, printing is performed with the plate surface covered with ink. Begins, and naturally, it becomes an undesired printed matter, and the ink needs to be quickly released from the plate surface. The PS plate naturally has a high ink detachability due to the structure of the aluminum surface, and it is expected that the binder composition of the present invention will have an ink detachability close to that of the PS plate. In the present invention, an embodiment in which no hydrophilic polymer is contained in the undercoat layer is of course included. In this case, the binder in the undercoat layer is substantially only latex, and the adhesion to the support is further improved, and the ink releasability is also preferable. Further, the heating until the application of the physical development nucleus layer can be shortened, and in some cases, the physical development nucleus layer can be applied simultaneously with the undercoat and the silver halide emulsion layer.
It is also conceivable that a film is formed in the production process, and it is preferable to consider the production stability by using a hydrophilic polymer in combination with several percent. The latex of the present invention is preferably a latex which does not swell in water, is a latex which absorbs water and a humidifying liquid for printing and has a swelling ratio of 1.2 or less, preferably 1.1. The following latex. The non-swellable latex for water used in the present invention is a latex having a low swelling property for water, and the following coating solution is prepared and 5
0 g / m ^{2 was} applied and heated at 50 ° C. for 24 hours.
It was immersed in 2N caustic soda for 1 minute, and the swelling ratio was determined by the amount of liquid absorbed. In other words, the swelling ratio is defined as the ratio of the amount of liquid absorption of the sample containing latex to the comparison containing no latex. <Test coating solution> Gelatin 5 g Test latex (solid content) 45 g Carplex (Shinogi Pharmaceutical Co., Ltd., average particle size 1.2 microns) 25 g Carbon black dispersion (solid content 32%) 20 g 10% formaldehyde 3 g Total The planographic printing plate which is the subject of the present invention contains a hydrophilic polymer such as gelatin as a whole, and the layer containing the same is an undercoat layer, an emulsion layer and a physical development nucleus layer. sell. These gelatin-containing layers can be hardened with a gelatin hardener. Gelatin hardeners include, for example, inorganic compounds such as chrome alum, aldehydes such as formalin, glyoxal, malealdehyde, glutaraldehyde, N-methylol compounds such as urea and ethylene urea, mucochloric acid, 2,3-dihydroxy- Aldehydes such as 1,4-dioxane,
2,4 dichloro-6-hydroxy-S-triazine salt, a compound having an active halogen such as 2,4 dihydroxy-6-chloro-triazine salt, divinyl sulfone, divinyl ketone and N, N, N-tricloylhexahydrotriazine; Compounds having two or more active three-membered ethyleneimino or epoxy groups in the molecule,
One or more of various compounds such as dialdehyde starch can be used as a polymer hardener. 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 hydrophilic polymer of the present invention is, in addition to gelatin, water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, acacia, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene-anhydromaleic. One or more binders of hydrophilic polymers such as acid copolymers, polyvinyl methyl ether-maleic anhydride copolymers and polysaccharides can also be used. The undercoat layer may contain pigments and dyes such as carbon black for the purpose of preventing halation, and may contain solid powder (for example, silica particles) having an average particle size of 1 to 5 microns for improving printing durability. obtain. Further, a photographic additive such as a developing agent can be included. The silver halide emulsion layer may be, for example, silver chloride,
It consists of silver bromide, silver chlorobromide, and those containing silver iodide. The silver halide crystal may contain a heavy metal salt such as a rhodium salt, an iridium salt, a palladium salt, a ruthenium salt, a nickel salt, a platinum salt, and the like, in an amount of 10 ^-8 to 10 ^-3 per mol of silver halide. Is a mole. The crystal form of the silver halide is not particularly limited, and may be cubic to tetradecahedral grains, or core-shell or tabular grains. The silver halide crystal may be a monodisperse or polydisperse crystal,
Its average particle size is in the range of 0.2-0.8 μm. One preferred example is a monodispersed or polydispersed crystal containing 70% by mole or more of silver chloride containing a rhodium salt or an iridium salt. 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. Silver halide emulsions can also be sensitized or desensitized positively or negatively by dyes such as cyanine, merocyanine and the like. There is no particular limitation on the wavelength range in which the sensitization or desensitization can be performed. Therefore, orthosensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, and semiconductor laser sensitization can be performed, and UV sensitization and visible light reduction for a bright room can be performed. You can feel it. The surface layer present above the emulsion layer contains physical development nuclei. 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. The physical development nucleus may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethylcellulose, gum arabic, sodium alginate, hydroxyethylcellulose, polystyrene sulfonic acid, vinyl imidazole and acrylamide It may contain a polymer, a hydrophilic polymer such as polyvinyl alcohol or an oligomer thereof, and the content is preferably 0.5 g / m ² or less. 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. , 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, 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. One or both surfaces of the support may be coated with one or more polymer films or metal thin films. The surface of these supports can be subjected to a surface treatment in order to improve the adhesion to the coating layer. Particularly preferred supports are paper coated on both sides or one side with a polyolefin polymer, a polyester film, a polyester film having a hydrophilic surface, an aluminum plate 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-pyrazolidone, etc., development modifiers such as polyoxyalkylene compounds, onium compounds, etc. Can be included. Further, as the developing solution, a compound or the like described in U.S. Pat. No. 3,776,728 which improves 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. Examples of such a processing solution include JP-B-48-29723 and U.S. Pat.
721, 559 and the like. 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 Subbed polyethylene terephthalate film (17
(5 micron, manufactured by DuPont).
A matting layer containing 5 μm (coulter counter method) silica particles was provided, and the opposite surface was subjected to corona discharge machining, followed by carbon black and silica powder having an average particle size of 1.2 μm (FPS101 manufactured by Shionogi & Co., Ltd.) 2 .5g / m ² containing subbing layer (gelatin 0.5g / m ^2), on which 1-
Highly ortho-sensitized silver chloride emulsion having 0.1 g / m ² of phenyl-3-pyrazolidone (0.8 g of gelatin /
(including m ² ) as silver nitrate to give 1.0 g / m ² . As hardening agents, 2,4-dichloro-6-
Sodium hydroxy-s-triazine added to undercoat
The emulsion layer contained 5 mg / m ² of N-methylolethylene urea at 20 mg / m ² . After drying,
Nuclear coating solution described in Example 2 of No. 3-21602 (a polymer containing a copolymer of acrylamide and imidazole of No. 3 and hydroquinone as a developing agent 0.8 g /
pullulan coating added 2 mg / m ² of JP-4-277747 INCLUDED) at a ratio of m ^2, dried Comparative Example A of the present invention
A lithographic printing plate was prepared. In the lithographic printing plate according to the present invention, the undercoat layer used in the lithographic printing plate (Comparative Example A) contains less latex (4.5 g / m ^{2 in} solid content) and less gelatin. The lithographic printing plates D to K of the present invention were prepared. On the other hand, as a comparative example, the total binder amount in the undercoat layer was 5 g /
to m ^2, to create the raised planographic printing plate the ratio of gelatin and B, and C. Table 1 summarizes the lithographic printing plates used in this test (hardeners were increased with increasing gelatin). Immediately after the production of these 11 types of lithographic printing plates and after storage for 5 days under the conditions of 50 ° C. and 80% relative humidity, image exposure was carried out using a plate-making camera having an image reversing mechanism. 2 at 30 ° C with diffusion transfer developer
Development processing was performed for 0 seconds. <Transfer developer> Water 700 ml Potassium hydroxide 20 g Anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1.5 g 2-methylaminoethanol 15 g Water is added to make 1 liter. After the development processing, the original plate was passed between two squeezing rollers to remove excess developer, and immediately processed with a neutralizing solution having the following composition at 25 ° C. for 20 seconds. And dried. <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-acetamido-5-n-heptyl-1,2,4-triazole 1 g <Humidifier> 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. As a printing machine, Ryobi 3200CD (trademark of Ryobi KK offset printing machine) was used, and image skipping occurred due to background smearing of non-image portions and missing silver image portions, and printing was not possible. The number of printed sheets at the time was determined according to the following evaluation criteria. The ink was ABdick3-1012.
It was used. ○ 10,000 to 20,000 sheets ５ ， 5,000 to 10,000 sheets × 2,000 to 5,000 sheets The printing results are shown in Table 2. On the other hand, in order to check the water retention (ground stain) of the non-image area, Dai Nippon Ink F Gloss Purple 68N was used as the ink.
Using Ryuobi 3200CD as a humidifier, Eu-3,1% solution (fountain solution for PS plate / etch solution made by Fuji Film) The number of printed sheets at the time of tanning was determined according to the following evaluation criteria. 5000 sheets or more ○ 1000 to 5000 sheets ３００ 300 to 1000 sheets × 1 to 300 sheets The printing results are shown in Table 2. Under the same conditions as those for checking the water retention of the non-image area, the printing was started in a state where the plate surface was dry without drying the plate surface, and the ink was printed in the number of sheets until a printed matter free of background stain was obtained. The releasability was determined, and the printing results are shown in Table 2. [Table 1] In the above evaluation of the printing durability, the image quality of the printed matter was simultaneously evaluated by the following evaluation method. The image quality was evaluated based on the following evaluation criteria to determine how a halftone dot of 100 lines made by a camera plate can be reproduced on a printed material. ◎ Reproduce halftone dots with clear contours. ○ The outline is slightly blurred. △ The outline is blurred. × Each halftone dot is irregular. Table 2 shows the printing results. [Table 2] From the above results, it was confirmed that the use of the undercoat mainly composed of the latex of the present invention was excellent in various printing properties, particularly excellent in ink detachment, water retention and printing image quality. Example 2 A lithographic printing plate prepared according to Example 1 was used in Japanese Patent Application No. 5-33.
The development processing was performed by the rapid processing apparatus described in No. 4028. The development condition is 30 ° C. for 8 seconds. As a result of evaluating the obtained lithographic printing plate according to Example 1, the lithographic printing plate of the present invention obtained the same result as that of Example 1, but the comparative example further deteriorated various performances. The latex used in Example 1 was 752A and LX407S was a styrene / butadiene latex. LX811 is an acrylate-based latex having a swelling ratio of about 1.1, and is a non-swelled latex. According to the present invention, in a lithographic printing plate to which a silver complex salt diffusion transfer method is applied, excellent printing characteristics are obtained, and in particular, ink detachability, water retention and printing quality are improved, It can be adapted to small liquid development.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-303205 (JP, A) JP-A-6-301216 (JP, A) JP-A-5-257287 (JP, A) JP-A-6-301287 316181 (JP, A) JP-A-8-211615 (JP, A) JP-A-5-66564 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 7/07 G03F 7 / 11

Claims (1)

(57) At a Claims 1. A lithographic printing material by applying the silver complex diffusion transfer process comprising at least the undercoat layer and a silver halide emulsion layer and physical development nuclei layer on a support, the Undercoat layer is car
Bon black and hydrophilic binder as binder
Does not contain limers, mainly containing polymer latex
The lithographic printing material, characterized by that.