JPH1184671A - Lithographic printing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high printing durability, scratching resistance and contamination, resistance by incorporating a matting agent comprising fine particles of a small average particle size into a silver halide emulsion layer and incorporating a matting agent comprising particles of a large average particle size into a base coating layer so as to control the center line average roughness of a lithographic printing material to a specified range. SOLUTION: The matting agent comprising fine particles to be added to a silver halide emulsion layer has the average particle size smaller than the dry film thickness of the binder of the silver halide emulsion layer. Preferably, the matting agent has 0.1 to 1.0 μm average particle size. The matting agent to be added to the base coating layer contains particles having a larger average particle size than the fine particles of the matting agent incorporated into the silver halide emulsion layer. The average particle size is >=1.0 μm, preferably 1.5 to 5 μm. The amt. of the matting agents incorporated into the silver halide emulsion layer and the base coating layer depends on the average particle size, particle content and binder content of each matting agent used for the respective layer, however, the amt. is controlled to obtain 0.6 to 1.2 center line surface roughness Ra.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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.

In such a lithographic printing plate, a silver image deposited on a physical development nucleus layer provided on a gelatin-silver halide emulsion layer is used as an ink-receiving image portion. (For example, a PS plate, etc.), the image portion has insufficient resistance to mechanical abrasion (referred to as printing durability), and the image portion is missing or the ink receptivity of the image portion gradually decreases. It has the disadvantage of being easily lost.

[0006] In order to overcome this drawback, it is known that a matting agent is contained in the silver halide emulsion layer or the undercoat layer. Storing for a long period of time until plate making causes the generation of background stains and the deterioration of ink receptivity.

In US Pat. No. 5,281,509, the surface roughness Ra is set to 1.2 or less, and in JP-A-8-137109, the surface roughness Ra is set to 0.6 or less. Thus, a matting agent technique for an undercoat layer which improves the stain resistance is described. However, when Ra is reduced, stain resistance is improved, but printing power and scratch resistance are deteriorated, and the matting agent technology described in JP-A-8-137109 is not satisfactory. As described above, since the stain resistance property and the printing durability and scratch resistance properties are inconsistent properties, it has been very difficult to satisfy these properties at a high level at the same time. .

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic printing material using a silver complex salt diffusion transfer method, which satisfies all of the printing durability, scratch resistance and stain resistance at a high level. is there.

[0009]

The object of the present invention is to provide a silver halide emulsion layer containing a fine-grained matting agent having a small average particle size and a matting agent particle having a large average particle size in an undercoat layer. This is achieved by setting the center line average roughness Ra value of the lithographic printing material to 0.6 or more and 1.2 or less.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The fine particle matting agent contained in the silver halide emulsion layer has an average particle size (.mu.m) smaller than the dry thickness (.mu.m; the same applies hereinafter) of the binder (usually gelatin or the like) of the silver halide emulsion layer. The same applies hereinafter). It is preferable that the matting agent has an average particle size of 0.1 μm or more and 1.0 μm or less. Further, it is preferable that 90% or more of the total number of matting agent particles are monodisperse particles having a particle diameter of ± 30% of the average particle diameter. The dry thickness of the silver halide emulsion layer is preferably 2 μm or less, particularly preferably 1.5 μm or less.

The matting agent contained in the undercoat layer preferably contains at least matting agent particles having a particle size larger than the dry thickness of the binder of the undercoat layer. It may be smaller or larger. Specifically, an average particle size larger than that of the fine particle matting agent contained in the silver halide emulsion layer is used, and the average particle size is 1.0 μm or more, preferably 1.5 μm to 5 μm. Preferably, a matting agent having an average particle size 1.5 times or more, preferably 3 times or more, larger than the average particle size of the fine particle matting agent is used. The matting agent for the undercoat layer may be monodisperse or polydisperse. The undercoat layer may be composed of a plurality of layers. In this case, it is preferable that at least the undercoat layer adjacent to the silver halide emulsion layer contains a matting agent. The dry thickness of the undercoat layer is 8 μm or less,
In particular, it is preferably 6 μm or less.

The dry thickness is the thickness of only a binder such as gelatin or a polymer. For example, gelatin has a specific gravity of about 1
Approximately corresponds to the coating weight (g) per 1 m ^{2 of} gelatin. The average particle size or particle size distribution of the matting agent is measured by a known coal counter method.

Examples of the fine particle matting agent for the silver halide emulsion layer and the large particle matting agent for the undercoat layer include, for example, those described in JP-A-62-275240 and JP-A-3-168637. Inorganic compounds such as silicon dioxide (silica), magnesium oxide, manganese colloid, titanium dioxide, polystyrene, polymethyl methacrylate,
Organic compounds such as polymethyl acrylate and starch can be used.

The amount of the matting agent contained in the silver halide emulsion layer and the undercoat layer varies depending on the average particle size, content, binder amount, etc. of the matting agent used in each layer. The Ra value is adjusted so as to be 0.6 or more and 1.2 or less. In other words, the Ra value depends greatly on these factors.

Generally, the amount of the fine particle matting agent in the silver halide emulsion layer is in the range of 0.01 to 1 g / m ² , more preferably 0.05 to 0.5 g / m ² . The amount of the matting agent in the undercoat layer is 0.1 to 3 g / m ² , preferably 0.5 to ² g / m ² .
g / m ² . The fine particle matting agent for the silver halide emulsion layer has a high surface smoothness and is superior in print image quality and stain resistance, and furthermore has improved scratch resistance in the development processing. In addition, the large particle matting agent located in the undercoat layer improves printing durability and scratch resistance in combination with the effect of the fine particle matting agent.

The matting agent for the silver halide emulsion layer and the undercoat layer preferably contains the above-mentioned matting agent alone, but has a center line surface roughness Ra of 0.6 or more.
Within the range of 2 or less, matting agents having different substances, particle diameters, and shapes can be used in combination as needed.

The center line average roughness of the lithographic printing material is a value before the plate making process, and can be measured by using a surface roughness profile measuring device, for example, Surfcom 500B, Tokyo Seimitsu Co., Ltd. A portion having a measurement length l is extracted from the roughness curve in the direction of the center line, and the center line of the extracted portion is denoted by X.
Axis, the direction of the vertical magnification is the Y axis, and the roughness curve is y = f (x)
When represented by, the center line average roughness Ra value is expressed in units of micrometers, and can be calculated by the equation (1).

[0018]

(Equation 1)

The lithographic printing material of the present invention contains gelatin, and the layer containing the gelatin may be a silver halide emulsion layer, an undercoat layer, or a physical development nucleus layer. These gelatin-containing layers can be hardened with a gelatin hardener. Examples of gelatin hardeners include chrome alum,
Formalin, glyoxal, N-methylol compound,
Mucochloric acid, 2,4-dichloro-6-hydroxy-s
-Triazine salts and 2,4-dihydroxy-6-chloro-
Compounds having an active halogen, such as s-triazine salts, divinyl sulfone, compounds having two or more active three-membered ethyleneimino groups or epoxy groups in a molecule, dialdehyde starch as a polymer hardener And the like, or one or more of various compounds.

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 producing the coating liquid or in-line at the time of coating.

Part of the gelatin in the gelatin-containing layer of the present invention is water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethylcellulose, gum arabic, 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 undercoat layer preferably contains a pigment such as carbon black, a dye or the like for the purpose of preventing halation. It is particularly preferable to contain a non-swellable latex such as a styrene-butadiene latex described in U.S. Pat. No. 5,281,509 and titanium dioxide. The latex content (solid content) is 0.5 to 5 g /
The content of m ² and titanium dioxide is in the range of 1 to 10 g / m ² . Further, a developing agent such as hydroquinone, methylhydroquinone and catechol can be contained. The undercoat layer is disclosed in JP-A-48-5503 and JP-A-48-100203.
And Japanese Unexamined Patent Publication No. 49-16507.

The silver halide emulsion layer includes, 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, 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 monodisperse crystal containing 70 mol% or more of silver chloride containing a rhodium salt or an iridium salt.

Silver halide emulsions can be chemically sensitized in various ways as they are 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. Further, a developing agent as described above can be included.

The surface layer present above the emulsion layer contains physical development nuclei. Physical development nuclei include metal colloid fine particles of silver, cadmium, cobalt, lead, nickel, palladium, rhodium, gold, platinum and the like, and sulfides, polysulfides, selenides of these metals, or mixtures thereof. Is also good. 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 and a hardener as described above.

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. And an antifoggant, 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. The surface of the support may be coated on one or both sides 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 include paper coated on both sides or one side with a polyolefin polymer, a polyester film, a polyester film having a hydrophilized surface, an aluminum plate having been 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 and the like, sulfites as preservatives, silver halide solvents such as thiosulfates, thiocyanates, cyclic imides, 2-mercaptobenzoic acid, alkanolamines,
Thioethers, mesoionic compounds and the like, thickeners such as hydroxyethylcellulose, carboxymethylcellulose and the like, antifoggants such as mercaptotetrazole,
Potassium bromide, compounds described in JP-A-47-26201, etc., developing agents such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, etc., development modifiers,
For example, it can contain a polyoxyalkylene compound, an onium compound, and the like. 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.

[0031]

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 A matted layer containing 4.0 micron average silica particles was provided on one side (back coat) of a 175 micron subbed polyethylene terephthalate film, and on the other side,
Carbon black, gelatin 3.2 g / m ² , titanium dioxide 4.5 g / m ² , styrene-butadiene latex
An undercoat layer containing 5 g / m ² and a matting agent shown in Table 1,
On top of that, 0.1 g / m ² of 1-phenyl-3-pyrazolidone
A two-layer simultaneous coating was carried out so that an ortho-sensitized high-sensitivity silver chloride emulsion (containing 0.8 g / m ^{2 of} gelatin) containing the matting agent shown in Table 1 was 1.0 g / m ² as silver nitrate. Was.

As the hardener, sodium 2,4-dichloro-6-hydroxy-s-triazine was contained in the undercoat layer, and N-methylolethylene urea was contained in the emulsion layer. After drying, a core coating solution described in Example 2 of JP-A-53-21602 (containing a copolymer of acrylamide and vinylimidazole of No. 3 as a polymer and hydroquinone as a developing agent in an amount of 0.8 g / m ² ). And then dry)
A lithographic printing plate was created.

These lithographic printing plates were prepared by a plate-making camera incorporating the following transfer developing solution and neutralizing solution.

<Transfer developer> Water 700 ml Potassium hydroxide 20 g Anhydrous sodium sulfite 50 g 2-mercaptobenzoic acid 1.5 g N-aminoethylethanolamine 15 g 2-mercapto-5-heptyl-1,3,4-oxadiazole Add 0.5 g water to make 1 liter.

<Neutralizing solution> Water 600 ml Sodium monophosphate 50 g Anhydrous sodium sulfite 10 g Ethylene glycol 5 ml Add water to 1 liter (adjust to pH 6).

The lithographic printing plate prepared as described above was mounted on an offset printing machine, the following desensitizing solution was applied to the plate surface, and printing was performed using the following humidifying solution.

<Desensitizing Solution> Water 600 ml Citric acid 2 g Sodium citrate 2 g Polyethylene glycol 29 g N-aminoethylethanolamine 20 g 2-mercapto-5-heptyl-1,3,4-oxadiazole 1 g

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

Using an offset printing machine, the number of prints when the image could not be used for printing due to image skipping due to the missing silver image portion was determined according to the following evaluation criteria. The ink is A
Bdick3-1012 was used. ◎ 20,000 or more ○ 10,000 to 20,000 sheets △ 5,000 to 10,000 sheets × 5,000 sheets or less

On the other hand, in order to check the water retention (dirt) of the non-image area, a commercially available moisturizing solution for a PS plate was used. The evaluation was made according to the following evaluation criteria. ◎ 5000 sheets or more ○ 1000 to 5000 sheets △ 300 to 1000 sheets × 1 to 300 sheets

The scratch resistance was evaluated by making a plate using a processor that easily causes scratches, and evaluating the level of scratches generated on the plate surface. ◎ No scratches occur. ○ Although it is very thin and scratched, there is no practical problem. △ Slightly noticeable scratches and practical problems. × Scratches occur on the entire surface, making it impractical.

Table 1 shows the results. The particle size of the silica has an average particle diameter ([mu] m), amounts in weight per 1m ² (g).

[0044]

[Table 1]

From the above results, it was found that Samples 10 to 12 of the present invention were used.
It can be seen that shows excellent properties in all of printing durability, stain resistance and scratch resistance.

Example 2 The matting agent used in the silver halide emulsion layers of Samples 10 to 12 of Example 1 was replaced with silica particles or polymethyl methacrylate particles having an average particle diameter of 0.2 μm and an Ra value of 0.9.
As a result of preparing a lithographic printing plate adjusted as described above, similarly excellent characteristics were confirmed.

[0047]

According to the present invention, it is possible to provide a lithographic printing material which is excellent in water retention, printing strength and scratch resistance of a lithographic printing plate to which a silver complex salt diffusion transfer method is applied.

Claims (2)

[Claims] Claims: 1. 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 provided with an undercoat layer and a silver halide emulsion layer. Each having a matting agent, the matting agent of the silver halide emulsion layer has an average particle size smaller than the thickness of the emulsion layer, and has a center line surface roughness Ra value of 0.6 or more and 1.2 or less. A lithographic printing material, characterized in that: 2. The matting agent of the silver halide emulsion layer has an average particle size of 0.1 to 1.0 μm, and the matting agent of the undercoat layer has an average particle size of 1.5 to 5.0 μm. Lithographic printing materials.