JP2907565B2 - Lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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.

[0002]

2. Description of the Related Art A lithographic printing plate comprises 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 a hydrophilic portion that receives water. It is composed of sex parts. 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.

If the hardness of gelatin is increased or the amount of physical development nuclei is increased in order to overcome this drawback, background staining occurs and the printing durability of the lithographic printing plate is significantly reduced.
Further, since the lithographic printing plate is stored for a long period of time from production to plate making, there is a drawback that background contamination occurs and ink receptivity is deteriorated, and improvement is desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate which has improved water retention and uses 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 has improved storage stability of printing performance.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a lithographic printing plate having at least a silver halide emulsion layer and a physical development nucleus layer on a support, in the physical development nucleus layer and / or adjacent thereto. Achieved by including pullulan in the layer.

The pull run according to the present invention is defined as Black.
Yeast is a kind of polysaccharide produced extracellularly when culturing a bacterium, and sucrose and glucose sugar are used as a carbon source for culturing.

[0010]

Embedded image

The pullulan of the present invention has a molecular weight of 50,000 to 200.
Everything can be easily manufactured. The production and properties of pullulan are described in Polymer 26, p. 93 (1977). Pullulan is sold as an industrial product by Hayashibara Co., Ltd. under the trademark Pullulan PF-20 and PI-20. The molecular weight of pullulan used in the present invention is not particularly limited, but is preferably in the range of about 10,000 to 1,000,000.

The content of pullulan used in the present invention is 5
00 mg / m ² or less, more preferably ^{2 to 2} mg / m ^2.
It is in the range of 00 mg / m ² . There is no particular limitation on the method of including pullulan in the constituent layer, and the pullulan is included in the physical development nucleus layer or / and its adjacent layer. From the viewpoint of easiness in production and the like, the method of applying together with a physical development nucleus is most advantageous, and it is reasonable to add it during the production of a coating solution.

The pullulan of the present invention can be used in combination with a water-soluble polymer used in a physical development nucleus layer described later, for example, carboxymethyl cellulose, gum arabic, sodium alginate, a copolymer of vinylimidazole and acrylamide, and the like. The effect can be further improved.

The pullulan of the present invention can be used in a wider range than other water-soluble polymers, the stability of the coating solution for physical development nuclei is good, and a larger amount can be used than ever. That is, the effect of the applied amount increases.

The lithographic printing plate which is the object of the present invention contains gelatin, and its content can be an undercoat layer, an emulsion layer or a physical development nucleus layer. These gelatin contents 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
Compounds having an active halogen, such as triazine salts and 2,4-dihydroxy-6-chloro-triazine salts,
Divinyl sulfone, divinyl ketone, N, N, N-triacylhexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups or epoxy groups in the molecule, as a polymer hardener One or more of various compounds such as dialdehyde starch can be used.

The hardener 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 formed of water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, acacia, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene. It can be substituted with one or more hydrophilic polymers such as maleic anhydride copolymer and polyvinyl methyl ether-maleic anhydride copolymer. Further, an aqueous vinyl polymer dispersion (latex) can be added to the gelatin layer.

The polymer binder of the undercoat layer is generally 0.5
More preferably to 10 g / m ² is 1 to 6 g / m ^2. The undercoat layer may contain a pigment or dye such as carbon black for the purpose of preventing halation, and may contain a solid powder (for example, silica particles) having an average particle size of 2 to 10 microns for improving printing durability. Further, a photographic additive such as a developing agent can be included. The undercoat layer is disclosed in JP-A-48-550.
No. 3, No. 48-100203, No. 49-1650
No. 7 may be as described.

The silver halide emulsion layer includes, 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 80 mol% or more of silver chloride, which contains 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 an anion, a cation or a neutral surfactant as a coating aid. , 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 preferably used 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.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below by way of examples, but of course the present invention. Is not limited to this

Example 1 A matting layer containing silica particles having an average particle size of 5 μm was provided on one side of 135 g / m ² double-sided polyethylene coated paper, and the opposite side was subjected to corona discharge machining, followed by carbon black and average particle size. A subbing layer (gelatin 3.5 g / m ² ) containing 7 μm silica powder and 1-phenyl-3
-Two-layer simultaneous coating of an ortho-sensitized high-sensitivity silver chloride emulsion containing 0.1 g / m ² of pyrazolidone (including 0.8 g / m ^{2 of} gelatin) to give 1.0 g / m ^{2 of} silver nitrate. Was.

As the hardening agent, 2,4-dichloro-6-
Hydroxy-S-triazine sodium is added to the undercoat layer.
70 mg / m ² and containing, in the emulsion layer N- methylol urea was 80 mg / m ² containing. After drying, the core coating solution described in Example 2 of JP-A-58-21602 (the polymer containing No. 3 copolymer of acrylamide and imidazole and 0.8 g of hydroquinone as a developing agent)
/ M ² ), dried and dried to obtain Comparative Example A of the present invention.
A lithographic printing plate was prepared.

The lithographic printing plate according to the embodiment of the present invention is the same as the lithographic printing plate (Comparative Example A), except that pullulan (trademark of Pullulan PF-20 manufactured by Hayashibara Co., Ltd.) is further added to the core coating solution.
The lithographic printing plates C and D of the present invention were prepared by containing them at 0 mg / m ² and 200 mg / m ² , respectively.

Further, as the planographic printing plate of Comparative Example B, 50 mg of carboxymethylcellulose was added to the core coating solution of Comparative Example A.
/ M ² . Immediately after the production of these four types of lithographic printing plates and after storage at 50 ° C. and a relative humidity of 80% for 5 days, image exposure was performed with a plate making camera having an image reversing mechanism, and the following silver complex salt diffusion transfer development The solution was subjected to development processing at 30 ° C. for 1 minute.

<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 Solution> 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-phosphoric acid 10 g nickel nitrate 5 g sodium nitrite 5 g ethylene glycol 100 g colloidal silica (20% liquid) 28 g Water is added to make 2 liters.

The printing machine is an Abdick 350CD
(The trademark of an offset printing machine manufactured by AB Dick Co., Ltd.), and the number of prints when the image cannot be printed due to image fouling due to background stain on the non-image area and missing silver image area. It was determined based on the evaluation criteria. ○ 10,000 to 20,000 sheets △ 5,000 to 10,000 sheets × 2,000 to 5,000 sheets The printing results are shown in Table 1.

On the other hand, in order to check the water retention (stain on the background) of the non-image area, F Gloss Purple 68S manufactured by Dainippon Ink was used as the ink.
AB Dick 350 using water as a humidifier
The number of prints when a background stain was generated on the CD and the print could not be used was determined according to the following evaluation criteria. ◎ 3000 sheets or more ○ 1000 to 3000 sheets △ 300 to 1000 sheets × 1 to 300 sheets The printing results are shown in Table 1.

In the above evaluation of the printing durability, a test for ink application was also performed at the same time. Table 1 shows the evaluation based on the number of inks applied.

[0039]

[Table 1]

From the above results, it was confirmed that the use of the pullulan of the present invention provided excellent printing characteristics, particularly excellent water retention, and also excellent stability over time.

[0041]

According to the present invention, the water retention of a lithographic printing plate to which the silver complex salt diffusion transfer method is applied can be improved, and the deterioration of the printing performance due to storage can be improved.

Claims (1)

(57) [Claims] 1. A lithographic printing material to which a silver complex salt diffusion transfer method having at least a silver halide emulsion layer and a physical development nucleus layer on a support is used, in the physical development nucleus layer and / or a layer adjacent thereto. A lithographic printing material characterized by containing pullulan.