JPH09160249A - Planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a planographic printing plate having excellent contamination resistance and scratching resistance which uses a silver complex salt diffusion transfer method by incorporating an acicular matting agent into structural layers on the emulsion layer side of the planographic printing plate. SOLUTION: This planographic printing plate has at least one base coating layer, silver halide emulsion layer and physical developing nuclei layer successively formed on a base body by coating. The structural layers in the emulsion layer side of the planographic printing plate contain an acicular matting agent. The acicular matting agent has >=3μm average length and 0.01-0.2μm average diameter. Moreover, the acicular matting agent can be included in any structural layers, and especially, it is preferably included in the base coating layer. Even when the acicular matting agent is densely included in the base coating layer, high surface smoothness can be obtd. so that scratching resistance can be improved while contamination resistance is maintained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lithographic printing plate 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. 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 when water and ink are supplied to the plate surface,
It is necessary that the image area receives a sufficient amount of ink and the non-image area does not receive ink at all.

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,
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.

As described above, in the lithographic printing plate, since the silver image deposited on the physical development nucleus layer on the gelatin-silver halide emulsion layer is used as the ink-receptive image area,
Compared to general lithographic printing plates (such as PS plates), the resistance of the image area to mechanical abrasion is insufficient, and the image area may be missing or the ink acceptance of the image area may gradually increase. It has the drawback of being easily lost.

In order to overcome this drawback, if the hardness of gelatin is increased, a matting agent is contained, or the amount of physical development nuclei is increased, scumming occurs and the lithographic printing plate is subjected to printing durability. The power is significantly reduced.

The influence of the surface irregularities of the lithographic printing plate on the printability is well known in the field of PS plates, but it is also an important factor in the lithographic printing plate using the silver complex salt diffusion transfer method of the present invention. It is known. In particular, in a lithographic printing plate using the silver complex salt diffusion transfer method, the non-image area is mainly composed of a gelatin film, and although it is originally highly hydrophilic, it is used to improve the printing durability of the image area. It was general that the agent is designed to have a large matte surface (large unevenness on the surface). Japanese Unexamined Patent Application Publication No. 5-66564, No. 5-80517, No. 5-80518, and No. 5-805.
20, Dohei 5-80519, Dohei 5-100430, and U.S. Pat. No. 5,281,509, it is disclosed that there is a correlation between the matteness of the surface and the print stain, and the surface is smoothed. Disclose that the print stain on the non-image area can be significantly reduced.

However, although smoothing the surface was effective in improving print stains, scratches were likely to occur on the plate surface in the development processing step during plate making, particularly by processing with an automatic developing machine. This phenomenon is likely to occur when a polyester film is used as a support, and the scratches appear to overlap the image area, which is a serious defect in practical use.

[0008]

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 excellent stain resistance and improved scratch resistance.

[0009]

In a lithographic printing plate comprising a support, at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer, which are successively coated, on the emulsion layer side of the lithographic printing plate. It was achieved by including an acicular matting agent in the constituent layers of.

The needle-shaped matting agent used in the present invention means an elongated shape, and the shape of the details is not particularly limited. That is, it may have a tapered shape, an elongated cylindrical shape, or a prismatic shape. Preferably, acicularity (average length / average diameter; the average diameter here is a value obtained by averaging diameters when the maximum cross-sectional area of each acicular matting agent particle is converted into a circle).
Is 10 or more and preferably 20 or more. Specifically, the average length is 3 μm or more, and the average diameter is 0.01 to 0.2 μ.
m is preferably used. Examples of the acicular matting agent of the present invention include acicular titanium oxide (F
TL-100, 200) and the like, but of course the invention is not limited to this.

In the present invention, the acicular matting agent can be contained in any constituent layer, but it is particularly preferable to contain it in the undercoat layer. When the silver halide emulsion layer and the undercoat layer are separately added, it is preferable to contain 90% by weight or more in the undercoat layer. The addition amount of the acicular matting agent varies depending on the binder amount, but when the binder amount is usually ² to 6 g / m ² , the acicular matting agent is
Preferably at 5.0 g / m ² is added 1.0 g / m ² or more, the center line average roughness at that time (Ra value) is adjusted to be 1.2 or less.

The needle-shaped matting agent of the present invention can be selected in various sizes and types. It can also be used in combination with other matting agents (spherical, tabular, amorphous, etc.).

The present inventor has found that the needle-shaped matting agent of the present invention has an elongated shape which is advantageous for the physical properties of the film in the constituent layers of the lithographic printing plate. That is, the advantage of the acicular matting agent is that the smoothness of the surface can be maintained even if the constituent layers are densely packed. As mentioned above, the smoothness of the surface is important for printing stains, and the decrease in scratch resistance due to the smoothness of the surface is improved by closely packing the matting agent in the constituent layer. is there.

In the present invention, the centerline average roughness Ra value of the planographic printing plate can be measured by using a surface roughness profile measuring instrument, for example, Surfcom 500B manufactured by Tokyo Seimitsu Co., Ltd. From the roughness curve, a part of the measurement length l is extracted in the direction of the center line, and the center line of this extracted part is X.
Axes and vertical magnification are Y-axis, and roughness curve is y = f (x)
When expressed by, the center line average roughness Ra value is expressed in units of micrometers, and can be calculated by the formula of Formula 1.

[0015]

[Equation 1]

In the present invention, the center line average roughness Ra value of the lithographic printing plate is preferably 1.2 or less, and particularly preferably 1.0 or less. When the center line average roughness Ra value of the planographic printing plate is larger than 1.2, stain resistance and print image quality are deteriorated.

The binder used in the present invention is
Gelatin, water-soluble gelatin, starch, dextrin, albumin, sodium alginate, hydroxyethyl cellulose, gum arabic, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, polyacrylamide, styrene-maleic anhydride copolymer, polyvinyl methyl ether-maleic anhydride copolymer It is also possible to substitute one or more hydrophilic polymers such as polymers. Further, it is an aqueous dispersion of a vinyl polymer (latex such as styrene-butadiene copolymer).

The lithographic printing plate which is the object of the present invention contains gelatin, and its containing layer 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 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-
Compounds having an active halogen such as S-triazine salts and 2,4-dihydroxy-6-chloro-S-triazine salts, divinyl sulfone, divinyl ketone and N, N, N
-Triacroylhexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups or epoxy groups in the molecule, one of various compounds such as dialdehyde starch as a polymer hardener, or Two or more kinds 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 undercoat layer may contain pigments such as carbon black and dyes for the purpose of preventing halation. Further, photographic additives such as developing agents can be included. Further, the undercoat layer is disclosed in JP-A-48-5503 and JP-A-48-10020.
3, such as those described in JP-A-49-16507.

The silver halide emulsion layer is, 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 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, and the average particle size thereof is in the range of 0.2 to 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 on top of 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. 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, sodium polyacrylate, vinyl It may contain a copolymer of imidazole and acrylamide, a copolymer of acrylic acid and acrylamide, a hydrophilic polymer such as polyvinyl alcohol or an oligomer thereof, and the content thereof is 0.5 g / m.
It is preferably 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 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, 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. 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 papers whose both surfaces or one surface is coated with a polyolefin polymer, polyester films, polyester films whose surfaces have been hydrophilized, and aluminum plates which have been surface-treated.
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 contains an alkaline substance such as sodium hydroxide or 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, 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, 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 into ink receptivity or the receptivity can be enhanced by any known surface treatment 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, the desensitizing solution, the humidifying solution, and the like to be used can be a commonly known method.

[0029]

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

Example 1 An undercoat layer was coated as follows on a polyester film support which had been subjected to an aqueous undercoating treatment with an undercoating composition containing an epoxy compound disclosed in JP-A-60-213942 for the purpose of hydrophilization. To do.

<Undercoating liquid> Gelatin 35 g Water 200 g Matting agent Xg Water 160 g Carbon black dispersion liquid (solid content 32%) 8 g Formaldehyde (30% aqueous solution) 2 g Glyoxal (30% aqueous solution) 4 g Surfactant 6 ml Water is added to the total amount. To 600 g.

As the matting agent, needle-like matting agent (Titanium oxide manufactured by Ishihara Sangyo Co., Ltd.), amorphous silica particles (powdered silica manufactured by Fuji Silysia Chemical Ltd.), amorphous titanium oxide particles, tabular matting agent (Cope Chemical Co., Ltd., synthetic mica) was used. The particle size and the addition amount are shown in Table 1. The coating amount is 60 g / m ² in terms of moisture coating amount. An ortho-sensitized high-contrast silver chloride emulsion was coated on the undercoat layer in an amount of 1.5 g / m ² in terms of silver nitrate. After drying, the mixture was heated at 50 ° C. for 2 days, and the core coating solution described in Example 2 of JP-A-58-21602 (containing a copolymer of acrylamide and imidazole of No. 3 as a polymer and hydroquinone as a developing agent) was used. Is included at a rate of 0.8 g / m ² )
Was added in a similar manner to pullulan (trademark of Pullulan PF-20 manufactured by Hayashibara Co., Ltd.) at a concentration of 0.006 g / m ² to prepare and apply in the same manner.

[0033]

[Table 1]

Each of the above lithographic printing plates was subjected to image exposure and development processing using a plate-making camera processor CP-550II manufactured by Mitsubishi Paper Mills. The development was carried out at 30 ° C. for 20 minutes using the following diffusion transfer developer. Stabilization was carried out by treating with a stabilizing solution having the following composition at 25 ° C. for 20 seconds and drying. The following tests were performed on each of the obtained lithographic printing plates. Table 2 shows the results.

<Diffusion transfer developer> Water 700 g Sodium hydroxide 18 g Potassium hydroxide 7 g Anhydrous sodium sulfite 50 g 2-Mercaptobenzoic acid 1 g Uracil 10 g 2-Methylaminoethanol 30 g 5-Phenyl-2-mercapto-1,3,4 -Oxadiazole 0.1 g Potassium bromide 1 g Water is added to bring the total volume to 1,000 ml.

<Stabilizing Solution> Water 600 g Citric acid 10 g Sodium citrate 35 g Colloidal silica (20%) 5 g Ethylene glycol 5 g Water is added to bring the total volume to 1,000 ml.

For printing evaluation, Ryobi 3200CD (trademark of Ryobi Co., Ltd. offset printing machine) was used. In order to check the stain resistance of the non-image area, New Champion F Gloss Purple 68S manufactured by Dainippon Ink Co., Ltd. was used as the ink, and Eu-3, 1% aqueous solution (PS plate dampening water / etching solution, Fuji Film Co., Ltd.) was used to determine the number of prints when background stains occurred and printing was no longer possible. (A) 5,000 or more (B) 3,000 to 5,000 (C) 1,000 to 3,000 (D) 1,000 or less

For the evaluation of scratch resistance, the level of scratches generated on the plate surface was evaluated by the following evaluation standard after the development processing was carried out by a processor. (A) The plate surface is not scratched at all. (B) A slight scratch is seen on the printing plate. (C) A slight scar is seen during printing. (D) The scars are clearly visible during printing.

[0039]

[Table 2]

As can be seen from the above results, by using the acicular matting agent of the present invention, it is possible to improve scratch resistance while maintaining high stain resistance.

[0041]

The needle-like matting agent of the present invention can obtain high surface smoothness even when it is densely contained in the undercoat layer, so that the scratch resistance can be improved while maintaining the stain resistance.

Claims (3)

[Claims] 1. A lithographic printing plate comprising a support, on which at least one undercoat layer, a silver halide emulsion layer and a physical development nucleus layer are successively coated, in a constituent layer on the emulsion layer side of the lithographic printing plate. A lithographic printing plate comprising a needle-like matting agent in the. 2. The acicular matting agent has an average length of 3 μm.
The planographic printing plate according to claim 1, wherein the average diameter is 0.01 to 0.2 µm. 3. The center line average roughness (Ra) of the planographic printing plate.
3. The planographic printing plate according to claim 1 or 2, wherein the value) is 1.2 or less and the amount of the acicular matting agent contained in the constituent layer on the emulsion layer side is 1.0 g / m ² or more. Printed version.