JPH09171255A - Planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain planographic printing plate using a silver complex salt diffusion transfer process, excellent in various printing characteristics such as printing resistance, water retentivity and ink receptivity and having especially improved water-ink responsiveness by incorporating a silicone compd. into the undercoat layer of a planographic printing material applying a silver complex salt diffusion transfer process. SOLUTION: In a planographic printing material with at least an undercoat layer, a silver halide emulsion layer, a physical developing nucleus layer and a back coating layer on the substrate, a silicone compd. is contained in the undercoat layer by 1-100wt.%, preferably 10-50wt.% of the amt. of a binder in the layer. In the case of <1wt.%, water-ink responsiveness is little improved. In the case of >100wt.%, cissing is caused in a multi-ply coating and printing stain is also caused. The center line average roughness Ra of the printing material is 0.2-1.2, preferably 0.3-0.9. The objective planographic printing plate excellent especially in water-ink responsiveness is obtd.

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 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,
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 planographic printing plate, gelatin-
Since the silver image deposited on the physical development nucleus layer on the silver halide emulsion layer is used as an ink-accepting image area, the image area is higher than that of a general lithographic printing plate (for example, PS plate). The parts have insufficient resistance to mechanical abrasion, and have the drawback that the image area is missing or the ink receptivity of the image area is easily lost.

In order to overcome this drawback, the hardness of gelatin is increased, a matting material is contained in an undercoat layer or a silver halide emulsion layer to improve abrasion resistance, and the amount of physical development nuclei is increased. Then, dirt was generated. Further, there is a drawback in that when a lithographic printing plate is stored for a long period of time from production to plate making, scumming occurs and ink receptivity deteriorates.

Furthermore, if the hardness of gelatin is increased or the amount of physical development nuclei is increased, uneven coating properties of the physical development nuclei layer frequently occur, and printing durability is seen in the unevenness. Dirt,
The effects on ink deposits and ink deposits are seen, and improvements are desired.

In order to improve the water retention, JP-A-4-4-2
In 77747, it has been proposed to include pullulan in the physical development nucleus layer and / or the layer adjacent to the physical development nucleus layer, and hydrophilic polymers have been proposed in JP-A-4-277748 and JP-A-5-88370. The level of improvement effect was not enough. Further, even if a large amount of a hydrophilic polymer is used, the ink-carrying property is poor and there is a limit in improving the water / ink response.

To improve printing durability, Japanese Patent Publication No. 62-
296143, Japanese Examined Patent Publication Nos. 63-226658 and 63
No. 249852, Japanese Patent Publication No. 1-261643, JP-A No. 5-100430, No. 5-80518, and No. 5-
No. 80519, No. 5-80520, No. 5-665
64 various matting agent technologies and latex binders have been proposed, but printing durability, water retention, ink build-up,
The print quality, scratch resistance, especially water / ink responsiveness were not sufficiently satisfied.

In order to improve the responsiveness of water / ink, a proposal has been made in JP-A-5-100430 to reduce the amount of gelatin, but it has not reached the PS plate level. In off-wheel printing, it is customary to place ink on the entire surface of the PS plate, then supply a dampening liquid to the plate surface to confirm that the ink in the non-image area has been removed, and then start printing. Water responsiveness is required. In particular, in color printing, it was necessary to simultaneously start four PS plates at the same time to quickly remove the ink in the non-image areas. That is, it was not sufficiently satisfied as compared with the PS plate having a quick water / ink response.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a silver complex salt diffusion transfer method which is excellent in various printing characteristics (printing durability, water retention, ink buildup, etc.) and has particularly improved water / ink responsiveness. It is to provide the lithographic printing plate used.

[0012]

The above object of the present invention is to provide a subbing layer in a lithographic printing plate having at least a subbing layer, a silver halide emulsion layer, a physical development nucleus layer and a backing layer on a support. Achieved by including a silicone compound.

The silicone compound of the present invention is dimethylpolysiloxane, methylhydrogenpolysiloxane,
Amino-modified silicone, epoxy-modified silicone, epoxy-polyether-modified silicone, carboxy-modified silicone, alcohol-modified silicone, alkyl and alkyl-aralkyl-modified silicone, alkyl-aralkyl-polyether-modified silicone, polyether-modified silicone, fluorine-modified silicone, alkyl・ Higher alcohol ester-modified silicone, etc., but especially dimethylpolysiloxane is effective, and has long been known as a fiber treatment agent.
This is an application of water repellency for the effect of smoothness. Since the silicone compound added to the undercoat layer of the present invention is used in an aqueous system,
Pre-emulsified material is easy to use.

As the silicone compound of the present invention, an aqueous emulsion prepared in advance for inclusion in a gelatin binder is easy to use. Toray Dow Corning Silicone Co., Ltd. (SM7027, SM8708), Kyoeisha Chemical Co., Ltd. (R-170, PM). -50) and the like.

The amount of the silicone compound of the present invention used is in the range of 1 to 100% by weight, preferably 10 to 50% by weight, based on the binder of the undercoat layer. When the amount is small, the water / ink responsiveness of the present invention is small, and when the amount is large, cissing may occur during multi-layer coating, and printing stains may occur.

In order to exert the water / ink responsiveness of the present invention more effectively, JP-A-4-277747 and 4-2.
77748, 5-88370, etc., a higher effect is expected due to the proposed hydrophilic polymer in the physical development nucleus layer.

It is known that a general silver halide photographic light-sensitive material contains a silicone compound to improve the smoothness (to reduce the surface friction) and the rapid processing suitability of the light-sensitive material (for example, a special characteristic). Kaisho 60-14034
1, No. 60-140342, No. 60-140343, and JP-A-1-107255), it was an unexpected effect that the silicone compound improves the water / ink response in the lithographic printing plate which is the subject of the present invention. .

The Ra value of the center line average roughness of the present invention is 0.2.
˜1.2, and more preferably 0.3 to 0.9. In a lithographic printing plate containing the silicone compound,
When the Ra value was 1.2 or less, the water / ink response was remarkably improved. When the Ra value alone is 1.2 or less, the water retention property is improved, but the water / ink responsiveness is not satisfactory. The centerline average roughness of the lithographic printing plate can be measured by using a surface roughness profile measuring device, for example, Surfcom 500B, manufactured by Tokyo Seimitsu Co., Ltd. A portion of the measurement length 1 is extracted from the roughness curve in the direction of the center line, the center line of the extracted portion is taken as the X axis, the direction of longitudinal magnification is taken as the Y axis, and the roughness curve is represented by y = f (x). Center line average roughness Ra
The value is expressed in units of micrometers, and can be calculated by the equation (1).

[0019]

[Equation 1]

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.

Hardeners 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 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.
More preferably to 10 g / m ² is 1 to 6 g / m ^2.
The undercoat layer may contain a pigment or dye such as carbon black for the purpose of preventing halation, and may contain a solid powder (for example, silica particles) having an average particle size of 0.1 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-
5503, 48-100203, 49-1
It may be as described in Japanese Patent No. 6507.

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, 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 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,
Its average particle size is in the range of 0.2-0.8 μm. One preferred example is a monodispersed or polydispersed crystal containing 70% by mole or more of silver chloride containing 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 existing 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. 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 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 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, 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 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, 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, compounds described in JP-A-47-26201, etc., developers such as hydroquinones, catechol, 1-phenyl-3-pyrazolidone, etc., development modifiers such as polyoxyalkylene compounds, onium compounds, etc. 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 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.

[0032]

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 0.2 g / m 2 of silica particles having an average particle size of 3.5 μm (Coulter counter method) was coated on one side (backing, gelatin 2 g / m ² ) of a 175-micron subbed polyethylene terephthalate film. ² is provided with a matting layer, the opposite surface is subjected to corona discharge machining, and then carbon black and silica powder having an average particle diameter of 2.5 μ (Fuji Silysia Chemical Ltd. SY435) 0.4, 0.8 and 1. Two
An undercoat layer (gelatin 3.5 g / m ² ) containing g / m ² and 1-phenyl-3-pyrazolidone 0.1 g / m ² thereon.
An ortho-sensitized high-sensitivity silver chloride emulsion (containing 0.8 g / m ^{2 of} gelatin) having ^{2 or more} was simultaneously coated as two layers so as to have a silver nitrate content of 1.0 g / m ² .

As a hardener, 2,4-dichloro-6-
Hydroxy-s-triazine sodium was used as the undercoat layer.
0 mg / m ² and containing, in the emulsion layer and backing layer to N- methylol urea was 80 mg / m ² containing. After drying, the core coating solution described in Example 2 of JP-A-53-21602 (containing a copolymer of No. 3 acrylamide and imidazole as a polymer and hydroquinone as a developing agent at a rate of 0.5 g / m ²⁾ was used. In Japanese Patent Laid-Open No. 4-2777.
6 mg / m ² of 47 pullulan was applied and dried to prepare planographic printing plates corresponding to Comparative Examples A, B and C of the present invention.

The lithographic printing plates as the examples of the present invention were prepared by preparing lithographic printing plates D to K containing the silicone compound of the present invention in the undercoat layer, in comparison with Comparative A, B and C in the above lithographic printing plates. The planographic printing plates are summarized in Table 1.

Immediately after the production of these 11 kinds 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 each having an image reversing mechanism, and the following silver complex salt was used. 1 at 30 ° C with diffusion transfer developer
Development processing was performed for a 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 the development processing, the original plate was passed between two squeezing rollers to remove excess developer, and immediately processed with a neutralizing solution having the following composition at 25 ° C. for 20 seconds. And dried.

<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 created by the above operation is mounted on an offset printing machine, and the following desensitizing solution is applied to the plate surface,
Printing was performed using the following humidifying solution.

<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

<Humidifying 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.

Printing was performed using Ryobi 3200CD (trademark of Ryobi KK offset printing machine), ink was F gloss black N made by Dainippon Ink, and printing was started in a dry state without etching the plate surface. The water / ink responsiveness was evaluated by the number of prints until a non-printed product was obtained. Specifically, at the start of printing, ink is placed on the entire surface of the plate, printing is repeated, emulsified water penetrates into the ink in the non-image area, and the ink is detached because the surface of the non-image area is hydrophilic. come. In other words, the faster the ink removal speed is
/ It is a preferable printing plate because of its quick ink response. The water / ink responsiveness result was set as Test 1, the plate surface was once etched and printed with a desensitizing liquid, and printing was restarted 3 minutes after the stoppage of the test 2. The printing result was set as Test 3 after 1 minute of the stoppage. Each is shown in Table 2.

[0042]

[Table 1]

The silicone compounds shown in Table 1 are R-170 (active ingredient 30%) from Kyoeisha Chemical Co., Ltd. and SM7027 (active ingredient 38%) from Toray Dow Corning Silicone Co., Ltd. (38% active ingredient). Toray B
Y22-820 (20% active ingredient) is a carboxyl modified silicone.

[0044]

[Table 2]

From the above results, it was confirmed that the silicone compound of the present invention is excellent in various printing characteristics, and particularly excellent in water / ink response. Further, it was confirmed that the water / ink responsiveness was further excellent due to the higher surface smoothness.

[0046]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a lithographic printing plate which is excellent in various printing characteristics of the lithographic printing plate to which the silver complex salt diffusion transfer method is applied, and particularly excellent in water / ink response.

Claims (2)

[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 applied, wherein the undercoat layer contains a silicone compound. And planographic printing plate. 2. The planographic printing material according to claim 1, wherein the center line average roughness and Ra value are 1.2 or less.
Lithographic printing plate.