JPH0667437A - Planographic printing plate - Google Patents

Abstract

PURPOSE:To improve water-holding property by incorporating a specified water- soluble synthetic polymer into a layer containing physical developing nucleus or/and the adjacent layers and incorporating titanium oxide in a base coating layer. CONSTITUTION:This planographic printing plate is obtd. by successively forming a base coating layer, silver halide emulsion layer, and physical developing nucleus layer on a supporting body by coating. The physical developing nucleus layer and/or the adjacent layers contain a water-soluble synthetic polymer expressed by formula. In formula, R is H or alkyl group, n is 1-100mol%, l is 0-5mol%, and m is 0-20mol%. The polymer has 2000 300000 average mol.wt. The base coating layer contains titanium oxide. As for the titamium oxide, any type such as anatase and rutile can be used, and its surface may be treated for such purpose to improve dispersion stability. Thereby, the obtd. planographic printing plate using silver complex salt diffusion transfer method shows improved printing durability and water-holding property.

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), it is proposed in JP-A-53-21602 to include a copolymer of acrylamide and imidazole in the physical development core layer, and Japanese Patent Application No. 3-65546. Proposed to include at least one acrylamide or a copolymer of acrylamide and sodium acrylate in the physical development nucleus layer and / or the layer adjacent to the physical development nucleus layer, but it has not reached a level at which the improvement effect is sufficient. Didn't.

[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 improved water retention and printing durability.

[0008]

The above object of the present invention is to provide a lithographic printing plate in which at least one undercoat layer, a silver halide emulsion layer and physical development nuclei are sequentially coated on a support, wherein the physical development is carried out. This has been achieved by containing at least one water-soluble synthetic polymer of Chemical formula 1 in the core layer and / or the layer adjacent to the core layer, and by including titanium oxide in the undercoat layer.

In the formula (1), R represents H or an alkyl group, n is 1 to 100 mol%, l is 0 to 5 mol%, and m is 0 to 20 mol%. And the average molecular weight is 2000 to 300,000.

The content of the polymer of the chemical formula 1 used in the present invention is preferably 300 mg / m ² or less, more preferably ^{2 to} 150 mg / m ² . There is no particular limitation on the method of incorporating the polymer into the constituent layer, and the polymer can be incorporated into the physical development nucleus layer or / and its adjacent layer. The physical development nucleus can be added before or after coating, but the quality is stable. From the viewpoint of the properties and the ease of production, the method of applying 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 molecular weight of the polymer of Chemical Formula 1 of the present invention causes problems as a lithographic printing plate due to problems in the fixability (not flowing out) of the polymer during development processing, the stability of the coating solution, and the coating property. The range of 2,000 to 300,000 is more preferable, and the range of 10,000 to 200,000 is more preferable.

It is possible to use the polymer of the chemical formula 1 of the present invention together.
Further, a water-soluble polymer contained in the physical development nucleus layer described later,
For example, it can be used in combination with carboxymethyl cellulose, gum arabic, sodium alginate, a copolymer of vinylimidazole and acrylamide, and the like.
It is possible to further improve the effect of the polymer.

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 depending on the amount used, and naturally exhibit a smaller effect than other polymers. Also, adverse effects due to the amount of polymer (defective printing durability, defective ink transfer, etc.) are reduced.

The method of synthesizing the polymer of the chemical formula 1 of the present invention is as follows: 400cc of pure water in which nitrogen gas is passed for 15 minutes at a bath temperature of 65 ° C.
% Potassium persulfate 30CC is added, and then 3 moles of acrylate monomer and 100CC of isopropyl alcohol are added.
Is added and 120 minutes later, 10% of 3% dihydroxyethylaniline is added to terminate the polymerization.

To the polymer of acrylic amide after polymerization, 0 to 100 mol% of formalin is added, pH is adjusted to 11 with sodium hydroxide, and methylol is formed at 30 ° C. for 6 hours to synthesize the polymer of Chemical formula 1 of the present invention. To do.

In the polymer of the chemical formula 1 of the present invention, R is H or an alkyl group, and for the purpose of the present invention, the alkyl group is a methyl or ethyl group because it is a water-soluble polymer.

The titanium oxide used in the present invention may be of any type such as anatase type and rutile type, and may be surface-treated for the purpose of dispersion stability and the like. Titanium oxide is usually dispersed in water and added at the time of make-up before application, but it is not necessarily limited thereto. The amount of titanium oxide added varies depending on various conditions, but is in the range of 1 to ²⁰ g per 1 m ² .

The lithographic printing plate which is the object of the present invention contains gelatin, and the content thereof 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 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.

The 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. The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0030]

【Example】

EXAMPLE 1 A matting layer containing silica particles having an average particle size of 5 μ was provided on one side of a 135 g / m ² double-sided polyethylene-coated paper, and the opposite 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-
Pyrazolidone 0.1 g / m high-sensitivity silver chloride emulsion (gelatin 0.8 g / m ²⁾ which is ortho-sensitized having ² to be 1.0 g / m ² as silver nitrate, was performed a two-layer simultaneous coating . As a hardening agent, 2,4-dichloro-6-hydroxy-S-triazine sodium is used as an undercoat layer in an amount of 170
mg / m ² and containing, in the emulsion layer N- methylol urea was 80 mg / m ² containing. (Intermediate sample a)

In the above-mentioned undercoat layer, 5 g / m ² of titanium oxide (TR-1 manufactured by Sakai Chemical Co., Ltd.) is added in addition to carbon black and silica powder having an average particle size of 4 μ, except that
An intermediate sample b was prepared in the same manner as the intermediate sample a.

After drying each of the intermediate samples, JP-A-53-2 was used.
1602, a core coating solution described in Example 2 (containing a copolymer of No. 3 acrylamide and imidazole as a polymer and containing hydroquinone as a developing agent at a rate of 0.8 g / m ² ) and drying. A lithographic printing plate was prepared as Comparative Examples A and B, respectively.

Next, instead of the copolymer of acrylamide and imidazole in the above-mentioned core coating solution, 4 mg / cm 2 of Chemical formula 2 was used.
Comparative Example C and Sample 1 of the present invention were prepared according to Table 1 in the same manner as Comparative Examples A and B except that m ² was added.

[0035]

[Chemical 2] The average molecular weight of Chemical formula 2 is 100,000.

Furthermore, in addition to the copolymer of acrylamide and imidazole of the above-mentioned core coating solution, a chemical formula
g / m ² and 10 mg / m ² , respectively, and coated on each intermediate sample according to Table 1 and dried to prepare Comparative Examples D and E and Samples 2 and 3 of the present invention.

Each of these lithographic printing plates was image-exposed by a plate-making camera having an image reversing mechanism, and developed with the following silver complex salt diffusion transfer developer at 30 ° C. for 1 minute.

<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 development processing, the original plate
Pass through a book squeezing roller to remove excess developer, and immediately treat with a neutralizing solution having the following composition at 25 ° C. for 20 seconds,
Excess liquid was removed with a squeezing roller, and dried at room temperature.

<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, the following desensitizing liquid was applied all over the plate surface, and 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.

As the printing machine, Heidelberg TOK (trademark of offset printing machine manufactured by Heidelberg) is used, DDS (direct water supply apparatus) is used as a water supply apparatus, and New Champion F Gloss Black N made by Dainippon Ink is used as ink. The number of prints when the image was skipped due to the background stain of the non-image area and the missing of the silver image area and the image could not be printed, and the evaluation was made according to the following evaluation criteria. ○ 10,000 sheets or more □ 7,500 to 10,000 sheets △ 5,000 to 7,500 sheets ▽ 2,500 to 5,000 sheets × less than 2,500 sheets Printing results are shown in Table 1.

On the other hand, in order to check the water retention (background stain) in the non-image area, New Champion F Gloss Purple 68S manufactured by Dainippon Ink Co., Ltd. is used as the ink, and the moisturizing liquid SLM-OD50 manufactured by Mitsubishi Paper Mills is used as the moisturizing liquid. (2% aqueous solution) was used, and the number of printed sheets when Heidelberg TOK / DDS caused a background stain and the printing could not be performed was judged according to the following evaluation criteria. ○ 1,000 sheets or more □ 500 to 1000 sheets △ 300 to 500 sheets ▽ 100 to 300 sheets × less than 100 sheets The printing results are shown in Table 1.

In the above-mentioned 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.

[0044]

[Table 1]

From the results of Table 1, Samples 1, 2 and 3 which are the embodiments of the present invention are lithographic printing plates excellent in printing durability and water retention, while Comparatives A and B are printing durability. Is excellent, but water retention is inferior, and Comparative C, D, and E are inferior in printing durability, but water retention is excellent.

Example 2 Sample 1 of Example 1 except that Chemical Formula 3 was used in place of Chemical Formula 2
Sample 3 was prepared in the same manner as above, and evaluated in the same manner as in Example 1. Sample 3 exhibited the same printing durability and water retention as Sample 1.

[0047]

[Chemical 3] The average molecular weight of Chemical formula 3 is 150,000.

Example 3 Sample 1 of Example 1 except that Chemical Formula 4 was used in place of Chemical Formula 2
Sample 4 was prepared in the same manner as above and evaluated in the same manner as in Example 1. Sample 4 showed the same printing durability and water retention as Sample 1.

[0049]

[Chemical 4] The average molecular weight of Chemical formula 4 is 130,000.

[0050]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a lithographic printing plate which is excellent in printing durability and water retention in a lithographic printing plate to which the silver complex salt diffusion transfer method is applied.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taketoshi Miura 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills Co., Ltd.

Claims (1)

[Claims] 1. A lithographic printing plate comprising at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer, which are successively coated on a support, in the physical development nucleus layer, or
And a lithographic printing plate characterized by containing at least one water-soluble synthetic polymer represented by the following chemical formula 1 in the layer adjacent thereto and titanium oxide in the undercoat layer. [Chemical 1] In the formula, R1 represents H or an alkyl group, and n is 1 to 10
0 mol%, 1 is 0 to 5 mol%, m is 0 to 2
It is 0 mol%. And the average molecular weight is 2000 to 30.
In many cases.