JPH0667435A - Planographic printing plate - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to significantly improve the water retention and further improve the deterioration of the printing performance due to the preservation in a lithographic printing plate material to which the silver complex salt diffusion transfer method is applied. To do. In a lithographic printing material to which a silver complex emulsion diffusion transfer method having at least a silver halide emulsion layer and a physical development nucleus layer on a support is applied, acrylamide or acrylamide and acrylic acid are formed on the physical development nucleus layer. A planographic printing plate, which comprises applying a coating liquid containing at least one sodium copolymer and having a pH of 4 or more.

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. 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 water, and the ink on the image area, such as paper Printing is performed by transferring it 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 described in, for example, US Pat. No. 3,72.
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 developing solution 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 nucleus 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 part is insufficient, the image part is missing, and the ink receiving property of the image part 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. In order to improve water retention (stain resistance), in Japanese Patent Application No. 3-65546, a water-soluble synthetic polymer represented by Chemical Formula 1 or / and Chemical Formula 2 is contained in a physical development nucleus layer or / and an adjacent layer thereof. It was proposed to include at least one, but it did not reach the level where the improvement effect was sufficient.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing plate using a silver complex salt diffusion transfer method, which has further 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 to provide 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. Achieved by applying a coating solution containing at least one water-soluble synthetic polymer of the following Chemical Formula 1 or / and Chemical Formula 2 on the development nucleus layer, and adjusting the pH of the coating solution to 4 or more. It was

R1 in Chemical Formula 1 represents H or an alkyl group, and n is 100 to 3500.

In the chemical formula 2, R2 represents H or an alkyl group, and R3 represents H or an alkali metal. The ratio of n: m is 10: 0 to 1: 9, and the degree of polymerization (n + m) is 100 to 35.
00.

The content of the polymers of the chemical formulas 1 and 2 used in the present invention is preferably 300 mg / m ² or less, more preferably ^{2 to} 150 mg / m ² . A coating liquid containing the polymer is coated on the physical development nucleus layer, and
The pH of the coating liquid is 4 or more. In Japanese Patent Application No. 3-65546, the method of applying together with the physical development nuclei is the most advantageous from the viewpoint of stability of quality and easiness in production, and a method of adding it at the time of producing a coating solution is proposed. The method of the invention is more effective for further improving water retention. p
When H is lower than 4, improvement in water retention cannot be seen.

The molecular weights of the polymers of the chemical formulas 1 and 2 of the present invention are such that the fixability (not flowing out) of the polymer during the development process,
It is preferably in the range of 10,000 to 500,000, and more preferably in the range of 100,000 to 300,000 in order to cause problems in the stability of the coating solution, coatability and the like and to cause problems as a lithographic printing plate.

The polymers of the chemical formulas 1 and 2 of the present invention can be used in combination, and further, a water-soluble polymer contained in the physical development nucleus layer described later, for example, carboxymethyl cellulose, gum arabic, sodium alginate, a copolymer of vinyl imidazole and acrylamide. It can also be used in combination with coalescence and the like, and the effects of the polymers of Chemical Formulas 1 and 2 of the present invention can be further improved.

While other water-soluble polymers have poor ink-carrying properties with the amount used, the polymers of the present invention show less ink-carrying defects with the amount used, and can be used in larger amounts than other polymers. The effect also increases.

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 contents can be hardened with a gelatin hardener.
Examples of the gelatin hardener 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, 2,3- Aldehydes such as dihydroxy-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 a maleic anhydride copolymer and a 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 from 10 to 10 g / m ² , more preferably from 1 to 6 g / m ² .
The undercoat layer may contain a pigment such as carbon black, a dye or the like 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-48-55.
03, Dosho 48-100203, Dosho 49-16507
May be as described in.

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 from 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 crystal may be a monodisperse or polydisperse crystal,
The average particle size is in the range of 0.2 to 0.8 μm. One preferable example is a monodisperse or polydisperse crystal containing rhodium salt or iridium salt and having a silver chloride content of 80 mol% or more.

The silver halide emulsion can be sensitized in various ways as it is manufactured or coated. It is preferable to chemically sensitize by methods well known in the art, for example, with sodium thiosulfate, alkyl thiourea, or with a gold compound such as gold rhodanide, gold chloride, or a combination of both. The silver halide emulsions can also be sensitized or desensitized positively or negatively 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. I 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 core 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 anionic, cationic or neutral surfactants as coating aids. , 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, and the like can be used as long as they can withstand lithographic printing. 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 can 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 U.S. Pat. No. 3,7.
21, 559 and the like. The printing method, or the desensitizing liquid, the dampening liquid, or the like to be used may be a commonly known method.

[0027]

EXAMPLES The present invention will be explained below with reference to examples, but of course the present invention is not limited thereto.

Example 1 A 135 g / m ² double-sided polyethylene-coated paper was provided with a matting layer containing silica particles having an average particle size of 5 μ on one side, and the other side was subjected to corona discharge machining, followed by carbon black and an average particle size. An undercoat layer (gelatin 3.5 g / m ² ) containing 7 μ of silica powder, and 1-phenyl-3
Ortho-sensitized high-sensitivity silver chloride emulsion containing pyrazolidone 0.1 g / m ² (including gelatin 0.8 g / m ² ) is simultaneously coated in two layers so as to have 1.0 g / m ² as silver nitrate. It was

As a hardener, 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, JP-A-5
8-21602, the nucleating coating solution described in Example 2 (the polymer contains a copolymer of No. 3 acrylamide and imidazole and contains 0.8 g of hydroquinone as a developing agent).
m ² ) was applied and dried to prepare a lithographic printing plate as Comparative Example A of the present invention.

Next, lithographic printing plates of Comparative Examples B and C were prepared by adding Chemical Formula 3 and Chemical Formula 4 to the core coating solution of Comparative Example A at 50 mg / m ² , respectively. Immediately after production and after storage for 5 days at 50 ° C. and 80% relative humidity, these five lithographic printing plates were subjected to image exposure with a plate-making camera having an image reversing mechanism, and the silver complex salt diffusion transfer development described below was performed. The solution was developed at 30 ° C. for 1 minute.

[0031]

[Chemical 3] In the formula, n is 1500.

[0032]

[Chemical 4] In the formula, the ratio of n: m is 8: 2 and the degree of polymerization (n + m) is 150.
It is 0.

Next, an overcoating liquid containing each of Chemical Formula 3 and Chemical Formula 4 at 50 mg / m ² and containing a surfactant was coated on Comparative Example A to prepare the planographic printing plate of the invention. Samples 1 and 2 were prepared. The pH of the overcoat liquid was adjusted to 6.0.

Five kinds of lithographic printing plates thus prepared were used immediately after production and under conditions of 50 ° C. and 80% relative humidity.
After storage for a day, imagewise exposure was carried out with a plate-making camera having an image reversal mechanism, and development treatment was carried out at 30 ° C. for 1 minute with the following silver complex salt diffusion transfer developer.

<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, and immediately treated with a neutralizing solution having the following composition at 25 ° C. for 20 seconds. 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
(Tab of A.B.Dick offset printer) is used, and the number of printed sheets at the time when the image is not printed due to the image stain due to the background stain of the non-image part and the missing of the silver image part is as follows. 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 1.

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 made by Dainippon Ink.
AB Dick350 using water as a moisturizer
The number of printed sheets when the CD was stained and became unusable for printing was judged according to the following evaluation criteria. ◯ 5000 sheets or more □ 3000 to 5000 sheets △ 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 printing durability, a test for ink deposition was also conducted at the same time. In Table 1, the number of printed ink is evaluated.

[0042]

[Table 1] From the above results, the comparative A, B and C water retention levels are inferior, while Samples 1 and 2 which are the embodiments of the present invention are excellent in various printing characteristics, particularly excellent water retention and stability with time. It was confirmed to be excellent.

Example 2 This example shows the pH dependence of the overcoat liquid. A sample was prepared in the same manner as Sample 1 of Example 1 except that the pH of the overcoat liquid was changed according to Table 2, and print evaluation was performed. The results are shown in Table 2.

[0044]

[Table 2]

From the above results, Comparative D has an inferior level of water retention, while Samples 3, 4, which are the embodiments of the present invention.
It was confirmed that No. 5 was excellent in various printing characteristics, particularly excellent in water retention, and excellent in temporal stability.

[0046]

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 is applied on a support, and the following chemical formula 1 is formed on the physical development nucleus layer. Alternatively, and / or a coating liquid containing at least one water-soluble synthetic polymer of Chemical formula 2 is applied, and the pH of the coating liquid is 4 or more. [Chemical 1] In the formula, R1 represents H or an alkyl group, and n is 100 to
3500. [Chemical 2] In the formula, R2 represents H or an alkyl group, and R3 represents H or an alkali metal. The ratio of n: m is 10: 0 to 1: 9
The degree of polymerization (n + m) is 100 to 3500.