JPH0588370A - Planographic printing plate - Google Patents

Abstract

PURPOSE:To greatly improve the water-retaining property of a planographic printing plate material to which a silver complex salt diffusion transfer method is applied and further to ameliorate the deterioration in its printing performance by preservation. CONSTITUTION:Hyaluronic acid is incorporated into the physical development nucleus layer or/and the layer adjacent thereto of the planographic printing material which has at least a silver halide emulsion layer and the physical development nucleus layer on a base and to which the silver complex salt diffusion transfer method is applied.

Description

Detailed Description of the Invention

[0001]

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 is composed of an oleophilic image-forming portion that accepts oil-based ink and an oil-repellent non-image-forming portion that does not receive ink. Generally, the non-image-forming portion is hydrophilic to receive water. It is composed of sex parts. In ordinary lithographic printing, both water and ink are supplied to the plate surface, the image area selectively receives the coloring ink, and the non-image area selectively receives the water, and the ink on the image area is, for example, paper. Printing is performed by transferring to a printing medium.

Therefore, in order to obtain a good printed matter, the difference in lipophilicity and hydrophilicity between the image area and the non-image area is sufficiently large, and the image area is sufficient when water and ink are supplied to the plate surface. It is necessary to accept a certain amount of ink and not to accept ink 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 in, for example, US Pat.
No. 8,114, No. 4,134,769, No. 4,1
No. 60,670, No. 4,336,321, No. 4,
No. 501,811, No. 4,510,228, No. 4,621,041 and the like, the exposed silver halide crystals cause chemical development by DTR development to give a black color. It becomes silver and forms a hydrophilic non-image area, while unexposed silver halide crystals become a silver salt complex by the silver salt complexing agent in the developer and diffuse to the physical development nucleus layer on the surface to form nuclei. In the presence of the above, physical development is caused to form an image area mainly composed of ink-receptive physically developed silver.

As described above, in the planographic printing plate, gelatin-
Since the silver image deposited on the physical development nuclei layer on the silver halide emulsion layer is used as the ink-receptive image area, the image area is larger than that of a general lithographic printing plate (eg PS plate). There is a defect that the resistance to mechanical abrasion of the image area is insufficient, the image area is missing, and the ink receiving property of the image area is gradually lost.

In order to overcome this drawback, if the hardness of gelatin is increased or the amount of physical development nuclei is increased, scumming occurs and the printing durability of the lithographic printing plate remarkably decreases.
Further, there are drawbacks such as background stain and deterioration of ink receptivity due to storage for a long period from the production of the lithographic printing plate to the production of the lithographic printing plate, and improvement is desired.

[0007]

An object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method, which has improved water retention. 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]

The above object of the present invention is, in 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 hyaluronic acid in the layer.

Hyaluronic acid according to the present invention is a kind of mucopolysaccharide which is a temperate component of connective tissue in the living body,
It has a structure of a block copolymer of D-glucuronic acid and N-acetyl-D-glucosamine and has a molecular weight of about 10 ⁶ to 10 ⁷ .

[0010]

[Chemical 1]

In the living body, the hyaluronic acid of the present invention becomes a water-absorbing gel having strong viscoelasticity and water-retaining ability and is complexed with a protein to form a jelly-like matrix. In the cell, it functions to maintain the morphology of the cell, control the movement of intercellular substances, prevent the invasion of bacteria, and alleviate mechanical stimuli from the outside. The hyaluronic acid is produced by extraction from living organisms or fermentation production from sugars, and is produced by Croda Chemi.
0.2 in Cromoist HYA made by cal Ltd.
It contains ~ 0.3%, and hyaluronic acid alone is also available.

The content of hyaluronic acid used in the present invention is preferably 500 mg / m ² or less, more preferably 2
˜200 mg / m ² . The method for incorporating hyaluronic acid into the constituent layer is not particularly limited, and it is included in the physical development nucleus layer or / and its adjacent layer, and may be added before or after coating the physical development nucleus, but the quality is stable. From the viewpoint of properties and easiness in production, the method of giving it together with the physical development nuclei is most advantageous, and it is rational to add it at the time of producing the coating solution.

The hyaluronic acid of the present invention may be used in combination with a water-soluble polymer used in the 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 of acid can be further improved.

The lithographic printing plate which is the object of the present invention contains gelatin, and its content 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.
Examples of gelatin hardeners include inorganic compounds such as chromium alum, aldehydes such as formalin, glyoxal, malealdehyde and glutaraldehyde, N-methylol compounds such as urea and ethyleneurea, mucochloric acid, and 2,3-dihydroxy. Aldehydes such as 1,4-dioxane, 2,4-dichloro-6-hydroxy-S
A compound having an active halogen such as a triazine salt or a 2,4-dihydroxy-6-chloro-triazine salt,
Divinyl sulfone, divinyl ketone, N, N, N-triacroylhexahydrotriazine, compounds having two or more ethyleneimino groups or epoxy groups which are active three-membered rings in the molecule, and 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, the diffusible hardener can be added to only one layer in the case of simultaneous coating of two layers. As an addition method, it may be added at the time of emulsion production or in-line at the time of coating.

Gelatin in the gelatin-containing layer of the present invention comprises a part of water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethyl cellulose, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylamide, styrene. It may 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 polymeric binder of the subbing layer is generally 0.5.
It is preferably 1 to 6 g / m ^2, more preferably 10 to 10 g / m ² . The undercoat layer may contain a pigment such as carbon black, a dye, etc. for the purpose of preventing halation, and may contain a solid powder (for example, silica particles) having an average particle diameter of 2 to 10 microns for improving printing durability. Further, photographic additives such as developing agents can be included. The undercoat layer is disclosed in JP-A-48-550.
3, the same as those described in JP-A-48-100203 and JP-A-49-16507 may be used.

The silver halide emulsion layer is, for example, silver chloride,
It comprises 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 and a platinum salt, and the addition amount is 10 ^-8 to 10 ^-3 per mol of silver halide. It is a mole. The crystal form of silver halide is not particularly limited, and may be cubic or tetradecahedral grains, or core-shell type or tabular grains. The silver halide crystals may be monodisperse or polydisperse crystals,
The average particle size is in the range of 0.2 to 0.8 μm. One of the preferable examples is a monodisperse or polydisperse 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, for example with sodium thiosulfate, alkyl thioureas, or with gold compounds such as gold rhodanide, gold chloride, or a combination of both. Silver halide emulsions can also be positively or negatively sensitized or desensitized with dyes such as cyanines, merocyanines. There is no particular limitation on the wavelength range that can be sensitized or desensitized. Therefore, ortho sensitization, panchromatic sensitization, helium-neon laser sensitization, argon laser sensitization, LED sensitization, semiconductor laser sensitization can be performed, and UV sensitization and visible light desensitization for bright rooms. You can feel it.

The surface layer present on top of the emulsion layer contains physical development nuclei. Physical development nuclei include fine particles of metal colloid such as silver, antimony, bismuth, cadmium, cobalt, lead, nickel, palladium, rhodium, gold and platinum, and sulfides, polysulfides, selenides of these metals, or those. It may be a mixture or a mixed crystal. The physical development nuclei may or may not contain a hydrophilic binder, but gelatin, starch, dialdehyde starch, carboxymethyl cellulose, gum arabic, sodium alginate, hydroxyethyl cellulose, polystyrene sulfonic acid, vinyl imidazole and acrylamide A polymer, a hydrophilic polymer such as polyvinyl alcohol, or an oligomer thereof can be contained, and the content thereof is preferably 0.5 g / m ² or less. Further, the physical development nucleus layer may contain a developing agent such as hydroquinone, methylhydroquinone and catechol, and a known hardener such as formalin and dichloro-s-triazine.

Each of the coating layers such as the undercoat layer, the silver halide emulsion layer and the physical development nucleus layer may contain some of an anion, a cation or a neutral surfactant as a coating aid. , Antifoggants, matting agents, thickeners, antistatic agents and the like.

The support for the lithographic printing plate of the present invention includes:
Paper or a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron, which can withstand lithographic printing, can be used. The surface of the support may be coated on one side or both sides with one or more polymer films or metal thin films. The surface of these supports may be surface-treated in order to improve the adhesion with the coating layer.

Particularly preferably used supports are papers whose both surfaces or one surface is coated with a polyolefin polymer, polyester films, polyester films whose surfaces have been hydrophilized, and surface-treated aluminum plates.
These supports may contain pigments for preventing halation and solid fine particles for improving surface properties. The support may also be light transmissive so that backside exposure is possible.

The developing solution used in the present invention contains an alkaline substance such as sodium hydroxide or potassium hydroxide,
Lithium hydroxide, sodium triphosphate, etc., sulfites as preservatives, silver halide solvents, such as thiosulfates,
Thiocyanates, cyclic imides, 2-mercaptobenzoic acid, amines, thickeners such as hydroxyethyl cellulose, carboxymethyl cellulose, antifoggants,
For example, potassium bromide, the compounds described in JP-A-47-26201, developers, such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, development modifiers,
For example, a polyoxyalkylene compound and an onium compound can be included. Further, compounds such as those described in U.S. Pat. No. 3,776,728, which improve ink transfer of the surface silver layer, can be used in the developing solution.

The surface silver layer after development of the lithographic printing plate of the present invention can be converted into ink receptivity or the receptivity can be enhanced with any known surface treating agent. Examples of such treatment liquid include Japanese Patent Publication No. 48-29723 and US Pat. No. 3,7.
21, 559 and the like. The printing method, the desensitizing solution, the dampening solution or the like to be used may be a commonly known method. The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[0026]

【Example】

135 g / m ² A matte layer containing silica particles having an average particle size of 5 μ was provided on one surface of a double-sided polyethylene-coated paper, carbon black and silica having an average particle size of 7 μ were formed on the opposite surface after corona discharge machining. An undercoat layer containing powder (gelatin 3.5 g / m ² ) and an ortho-sensitized high-sensitivity silver chloride emulsion having 1-phenyl-3-pyrazolidone 0.1 g / m ² thereon (gelatin 0.8 g / m ² ). m ²
(Including the above) as silver nitrate so as to be 1.0 g / m ² , and two layers were simultaneously coated.

As a hardening agent, 2,4-dichloro-6-
Hydroxy-S-triazine sodium in the undercoat layer 1
70 mg / m ² and N-methylol ethylene urea was contained in the emulsion layer at 80 mg / m ² . After drying, the core coating solution described in Example 2 of JP-A-58-21602 (containing a copolymer of No. 3 acrylamide and imidazole as a polymer and 0.8 g of hydroquinone as a developing agent) was used.
/ M in a proportion of ²⁾ coated, dried Comparative Example A of the present invention
I made a planographic printing plate.

The lithographic printing plate which is an example of the present invention is the same as the above lithographic printing plate (Comparative Example A), but further contains hyaluronic acid in the core coating solution at 50 mg / m ² and 200 mg / m ² , respectively. Then, planographic printing plates C and D of the present invention were prepared.

Further, as a lithographic printing plate of Comparative Example B, 50 mg of carboxymethyl cellulose was added to the core coating solution of Comparative Example A.
It was made to contain so that it would be / m ² . Immediately after the production of these four types of lithographic printing plates and after storing them for 5 days under the conditions of 50 ° C. and 80% relative humidity, they were subjected to image exposure with a plate-making camera having an image reversal mechanism, and the silver complex salt diffusion transfer development described below The solution was developed at 30 ° C. for 1 minute. Table 1 shows the types of planographic printing plates.

[0031]

[Table 1]

<Transfer developer> 700 ml of water 20 g of potassium hydroxide 50 g of 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 treatment, the original plate is passed between two squeezing rollers to remove excess developer, immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds, and the excess fluid is removed with a squeeze roller at room temperature. Dried in.

<Neutralization liquid> Water 600 ml Citric acid 10 g Sodium citrate 35 g Colloidal silica (20% liquid) 5 ml Ethylene glycol 5 ml Water is added to make 1 liter. The lithographic printing plate prepared by the above operation was mounted on an offset printing machine, and the following desensitizing liquid was applied all over the plate surface,
Printing was performed using the following dampening liquid.

<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

<Moisturizing liquid> 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 AB Dick 350CD
(Trademark of AB Dick offset printing machine) is used, and the number of printed sheets at the time when the image is skipped due to background stains on the non-image area and missing of the silver image area It was judged according to 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 2.

On the other hand, in order to see the water retention (background stain) in the non-image area, the ink is F Gloss Purple 68S manufactured by Dainippon Ink.
AB Dick350 with water as the moisturizer
The number of printed sheets when the CD was stained and became unusable for printing was judged by 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 2.

In the above evaluation of the printing durability, an ink running test was also conducted at the same time. Table 2 shows the number of printed ink.

[0039]

[Table 2] From the above results, it was confirmed that the use of hyaluronic acid of the present invention has excellent printing characteristics, particularly excellent water retention, and excellent temporal stability.

[0040]

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

Claims (1)

[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 applied, in the physical development nucleus layer and / or in a layer adjacent thereto. A lithographic printing material characterized by containing hyaluronic acid.