JPH1152578A - Lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithographic printing plate good in storage stability and in running processing aptitude, superior in ink removability and using a silver complex salt diffusion transfer method by using a sensitizing dyestuff having no acid group and a low molecular weight gelatin. SOLUTION: The photosensitive material for this lithographic printing plate has a silver halide emulsion layer spectrally sensitized with a sensitizing dye containing not any acid group composed of a sulfo group and a carboxy group. The emulsion layer and/or a layer lower than this layer contains a low molecular weight gelatin. The sensitizing dye is represented, preferably, by the formula in which each of Z<4> and Z<5> W<1> is an atomic group necessary to form a 5- or 6-membered heterocyclic ring; each of R<4> and R<5> is an alkyl group or the like; R<6> is an H atom or the like; each of L<8> -L<12> is a methine group or the like; each of (s) and (t) is 0 or 1; each of (h) and (l) is 0, 1, 2, or 3; (i) is 1; X3 is a counter ion, such as a methylsulfuric acid ion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithographic printing plate using an aluminum plate as a support, and more particularly to an aluminum lithographic printing plate using a silver complex salt diffusion transfer method.

[0002]

2. Description of the Related Art A planographic printing plate using a silver complex salt diffusion transfer method (DTR method) is described in "Photographic Silver Halide," published by Focal Press, London New York (1972), by Andrelot and Edith Weide. Some examples are described in "Diffusion Processes", pp. 101-130.

As described therein, a lithographic printing plate using the DTR method includes a two-sheet type in which a transfer material and an image receiving material are separated, or a monolithic plate in which they are provided on a single support. Two types of sheet type are known.
A two-sheet type lithographic printing plate is disclosed in
This is described in detail in JP-A-158844. For the mono-sheet type, see JP-B-48-30562.
No. 51-15765, JP-A-51-111103
And JP-A Nos. 52-150105.

[0004] A lithographic printing plate using paper as a support is difficult to print with high quality including printing durability due to plate elongation during printing and penetration of moisture. A film support is used for the purpose of improving these problems and improving printing performance.

[0005] However, lithographic printing plates using a film as a support are improved in terms of plate elongation and moisture penetration, as compared with paper-based printing plates, but they have improved printing durability, water retention and printing. The problem remains in terms of the ability to hang the plate on the machine.

In order to solve the above-mentioned various problems of the lithographic printing plate using a paper or a film as a support, a lithographic printing plate of a silver salt type using a metal, particularly an aluminum plate as a support has been known. And JP-A-57-118244, JP-A-57-158844, JP-A-63-260491, JP-A-3-116151, JP-A-4-282295, and JP-A-5-282495.
It is described in detail in respective gazettes such as 216236 and 6-81194.

JP-A-63-260491, JP-A-3-26049
116151, 4-282295, 5-216
Nos. 236 and 6-81194 disclose a roughened and anodized aluminum plate as a support,
A planographic printing plate utilizing a DTR method is described in detail, which is a monosheet type in which a physical development nucleus is carried thereon and a photosensitive silver halide emulsion layer is further provided thereon. According to it
After the lithographic printing plate is subjected to image exposure and DTR development, the silver halide emulsion layer is removed by washing with warm water, and then treated with a finishing solution to prepare a lithographic printing plate.

A DTR using such an aluminum plate
Printing plates have various problems as compared with DTR printing plates using paper or film as a support. For example, spot-like fog (accordingly, the DTR-transferred silver portion becomes spot-like white spots) due to storage time caused by the support of the aluminum plate, or streak-like desensitization (thus streaky streaks in the non-image portion) Transfer silver is generated).

Further, a silver halide emulsion layer which is not substantially hardened has a problem that it swells at the time of development due to a remarkably high swelling degree, thereby deteriorating the image quality, particularly the reproducibility of fine lines. This decrease in image quality is caused by argon laser, He-Ne
This is a particularly important problem in a printing plate for scanning exposure such as a laser, a red LD laser, an LED, and an infrared LD laser.

In particular, when used with a laser beam of 600 nm or more, a silver halide emulsion is required to have a considerably high sensitivity, so that it has a drawback that fogging is likely to occur. Alternatively, there is a problem that the background is stained and that the above-described reproducibility of the fine line is further reduced. Further, since the printing plate has a problem that the storage stability is deteriorated, the printing plate stored for a long time is liable to be stained. .

In the field of offset rotary printing presses, etching with dampening water is often omitted at the start of printing in order to prevent paper breakage. The printing method of detaching the ink is used, but there is a problem that not only the ink detaching speed of the non-image part is slow but also the ink of the image part detaches.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a storage medium having good storage stability and running processing aptitude, without causing adverse effects such as spot fog caused by an aluminum plate, and having excellent ink release properties. Another object of the present invention is to provide a DTR lithographic printing plate using an aluminum plate as a support, particularly suitable for scanning exposure.

[0013]

The above object of the present invention has been attained by using a sensitizing dye having no acid group and low molecular weight gelatin.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a lithographic printing plate having a physical development nucleus between an aluminum support and a silver halide emulsion layer, wherein the silver halide emulsion layer comprises an acid group comprising a sulfo group and a carboxy group. An aluminum lithographic printing plate which has been spectrally sensitized with a sensitizing dye having no silver halide emulsion layer and / or contains a low molecular weight gelatin in the silver halide emulsion layer and / or a layer below the emulsion layer.

The sensitizing dye used in the present invention is a sensitizing dye having no acid group in the molecule, preferably a cationic sensitizing dye. The cationic type means that the molecule does not have an acid group consisting of a sulfo group and a carboxy group.

Preferred sensitizing dyes are represented by the following general formulas (I), (II) and (III). Among them, particularly preferred are sensitizing dyes of the general formula (III).

[0017]

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In the formula, Z ^{1 to} Z ⁵ represent an atom group necessary for forming a 5- or 6-membered heterocyclic ring, and when two or more heterocyclic rings are present, they may be the same or different. R ^{1 to} R ⁵ may be the same or different and represent an alkyl group or a substituted alkyl group. R ⁶ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group or a heterocyclic group. G ¹ and G ² may be the same or different and each represents an alkyl group or a substituted alkyl group, an aryl group or a substituted aryl group, and G ¹ and G ² form a ring derived from a cyclic secondary amine. You may. W ¹ represents an atom group necessary for forming a 5- or 6-membered heterocyclic ring. L ^{1 to} L
¹² represents a methine group or a substituted methine group. p, q,
r, s and t represent 0 or 1, h, l and m represent 0, 1, 2 or 3, k and i represent 1, j
Represents 1 or 2, and n represents 0, 1 or 2. X ₁
~ X ₃ is a counter ion (eg, methyl sulfate ion,
Ethyl sulfate ion, thiocyanate ion, toluenesulfonic acid ion, chloride ion, bromine ion, iodine ion, perchlorate ion, sodium ion, potassium ion, trimethylammonium ion, etc.).

As the 5- or 6-membered heterocyclic ring represented by Z ^{1 to} Z ⁵ ,
Thiazole nucleus, benzothiazole nucleus, naphthothiazole nucleus, thiazoline nucleus, oxazole nucleus, benzoxazole nucleus, naphthoxazole nucleus, isoxazole nucleus, oxazoline nucleus, selenazole nucleus, benzoselenazole nucleus, naphthoselenazole nucleus, tellurazole nucleus, benzotellura Zole nucleus, naphthotellurazole nucleus, 3,3-dialkylindolenine nucleus, imidazole nucleus, benzimidazole nucleus, naphthoimidazole nucleus, pyridine nucleus, quinoline nucleus, imidazo [4,5-b] quinoxaline nucleus, oxadiazole nucleus, etc. Can be mentioned. These heterocyclic nuclei may have one or more substituents such as an alkyl group, an aryl group, an aralkyl group, a halogen atom, an alkoxy group, an alkoxycarbonyl group, a hydroxy group and a nitro group.

Preferably, W ^{1 is} as follows.

[0021]

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Among the methine groups and substituted methine groups of L ^{1 to} L ¹² , examples of the substituent include an alkyl group (eg, methyl and ethyl), an aryl group (eg, phenyl group), an aralkyl group (eg, benzyl group), Examples thereof include a halogen (chloro, bromo, etc.) alkoxy group (methoxy, ethoxy, etc.), and a methine chain substituent may form a 4- to 6-membered ring.

The alkyl group and substituted alkyl group represented by R ^{1 to} R ⁶ and G ^{1 to} G ² include, for example, carbon atoms of 1 to 1
8, preferably 1 to 7, particularly preferably 1 to 4, unsubstituted alkyl groups (methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, etc.), substituted alkyl groups (benzyl, 2-phenylethyl, 2-hydroxy Ethyl, 3-hydroxypropyl, 2-methoxyethyl,
2- (pyrrolidin-2-one-1-yl) ethyl, 2-
Acetoxyethyl, carbomethoxymethyl, 2-methanesulfonylaminoethyl, allyl group, etc.). R ⁶
And aryl groups and heterocyclic groups represented by G ^{1 to} G ² include phenyl, 2-naphthyl, 3-chlorophenyl,
3-methylphenyl, 2-pyridyl, 2-thiazolyl and the like.

The following are specific examples of the sensitizing dye used in the present invention.

[0025]

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[0026]

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[0027]

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[0028]

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In the present invention, these dyes may be used alone or in combination of two or more. The amount of these sensitizing dyes to be used is not particularly limited, but is preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻² mol, particularly 1 × 10 ⁻⁶ to 1 mol per mol of silver halide.
It is preferably × 10 ^-3 mol. The timing of addition may be any time before the silver halide emulsion is coated.

The low molecular weight gelatin used in the present invention is
Gelatin having an average molecular weight of about 70,000 or less. For example, JP-A-1-158426, JP-A-4-340439, and JP-A-8
No. 110641, etc. JP-A-8-11
No. 0641 describes that the use of a low molecular weight gelatin in a DTR printing plate using an aluminum plate improves ink receptivity. However, by combining with a sensitizing dye having no acid group, storage stability is improved, and spot fog (white spots on transferred silver) and background stain after storage are not generated, and ink releasability is improved. Was unexpected.

The low molecular weight gelatin used in the present invention can be produced by the method described in the above patent, for example, preferably by an enzymatic decomposition treatment. The average molecular weight is about 70,000 or less, preferably about 50,000 or less, particularly preferably about 3,000 to about 30,000. The amount used varies depending on the average molecular weight and the like, but when the silver halide emulsion layer is contained in the silver halide emulsion layer, the average molecular weight is about 3 to 100% relative to the photographic gelatin (gelatin having an average molecular weight of about 100,000 or more) of the emulsion layer. Gelatin having a molecular weight of 10,000 or less should be added in an amount of 1 to 150% by weight, preferably 2 to 100% by weight, and gelatin having an average molecular weight of about 30,000 or more should be added in an amount of 3 to 200% by weight, preferably 5 to 150% by weight. Is preferred.

The low molecular weight gelatin used in the present invention is
Although it is preferable to use the silver halide emulsion layer, it may be used as a nucleus layer or an intermediate layer between the emulsion layer and the nucleus layer which may be provided as necessary, in which case low molecular weight gelatin alone may be used. And photographic gelatin. Of course, it may be used for a plurality of layers.

In general, the surface of an aluminum support used for a lithographic printing plate is roughened in order to improve the wetting (water retention) with a fountain solution during printing and to improve the adhesion to the photosensitive layer. Is done. The surface roughening treatment (so-called graining) includes mechanical graining treatments such as ball graining, wire graining, and brush graining, and electrolytic dissolution by chemically dissolving aluminum with chloride fluoride or the like. A surface roughening treatment and a surface roughening method using these methods in combination are known. For example, JP-A-48-28123 and JP-A-53-123204
No. 54-146234, No. 55-25381,
Nos. 55-132294, 56-55291, 5
6-150593, 56-28893, 58-
167296, U.S. Pat. Nos. 2,344,510, 3,861,917, and 4,301,229. US Patent No. 2,
No. 344,510 performs mechanical surface roughening and electrolytic surface roughening,
Superposed composite grain structure, U.S. Pat. No. 4,301,2
No. 29 is the cumulative frequency distribution and center line roughness of the pit diameter, U.S. Pat. No. 3,861,917 is the rough surface depth, Canadian Patent No. 954449 is the height and diameter of the rough peak, West German Patent No. 1 , 813,443 each describe a difference in elevation of a rough surface.

After performing such a surface roughening treatment, anodic oxidation is performed in an electrolytic solution such as sulfuric acid, phosphoric acid, nitric acid, or a mixture thereof.

The thickness of the anodized layer of the roughened and anodized aluminum plate used in the present invention is about 0.3 to 3.0.
The range of μm is preferred. Note that desmutting is preferably performed prior to the anodizing. That is, the desmut adhered to the surface is removed by treating the roughened aluminum substrate with hot sulfuric acid (40 to 60 ° C.) at 10 to 50 ° C. or dilute alkali (such as sodium hydroxide).

After the anodic oxidation treatment, a post-treatment can be performed if necessary. For example, a method of dipping in an aqueous solution of polyvinyl sulfonic acid disclosed in British Patent No. 1,230,447 is used. Also,
If necessary, an undercoat layer of a hydrophilic polymer can be provided, but is selected depending on the properties of the photosensitive layer provided thereon.

The physical development nucleus of the physical development nucleus layer used in the present invention may be a known one usually used in a silver complex salt diffusion transfer method, for example, a metal colloid such as gold or silver or a silver or palladium or zinc. A metal sulfide obtained by mixing a water-soluble salt and a sulfide can be used. As the protective colloid, various hydrophilic colloids including the low molecular weight gelatin of the present invention can be used. These details and the production method are described, for example, in JP-B-48-30562 and JP-A-48-554.
No. 02, No. 53-21602, Focal Press,
Published by London New York (1972), by Andre Lott and Edith Weide, Photographic
Silver Halide Difusion Processes "
Can be referred to.

In the production of silver halide emulsions, gelatin, casein, dextrin, gum arabic, polyvinyl alcohol, starch and the like are used as protective colloids. Among them, gelatin is commonly used. Gelatin is acid-treated gelatin, alkali-treated gelatin, gelatin derivative,
Although there are many types such as grafted gelatin, it is common to use the high molecular weight photographic gelatin described above.

The gelatin used as the protective colloid of the silver halide emulsion for the lithographic printing plate of the present invention is preferably an alkali-treated gelatin, and more preferably a desalted gelatin. The amount used is preferably from 0.3 to 5 g per 1 g of silver halide expressed by silver nitrate. In addition, casein, dextrin, gum arabic, polyvinyl alcohol, starch and the like can be partially used in combination.

In the present invention, silver chloride, silver chlorobromide, silver chloroiodide, and silver chloroiodobromide are used as the type of silver halide emulsion. In particular, those in which silver chloride has a halogen composition of 70 mol% or more are particularly preferred.

The silver halide crystals have an average grain size of 0.1
It is 5 to 0.5 μm, preferably 0.2 to 0.4 μm.

In general, silver halide crystals have a regular hexahedron, regular octahedron, regular hexahedron, flat plate and the like, and a regular hexahedron is preferred as a silver halide crystal used in the lithographic printing plate of the present invention.

In forming the silver halide crystals, an iridium compound and a rhodium compound may be contained.

The silver halide emulsion used in the lithographic printing plate of the present invention may be subjected to chemical sensitization such as reduction sensitization, sulfur sensitization, gold sensitization, sulfur gold sensitization, etc., if necessary, to obtain a higher sensitivity. Can be.

The silver halide emulsion used in the lithographic printing plate of the present invention is spectrally sensitized with the above-described sensitizing dye and spectrally sensitized so as to have a maximum photosensitive wavelength in the wavelength region of a scanning exposure light source.

The emulsion layer of the lithographic printing plate of the present invention may optionally contain anionic, cationic, betaine, nonionic surfactants, thickeners such as carboxymethylcellulose, and coating aids such as antifoaming agents. A chelating agent such as ethylenediaminetetraacetate and a developing agent such as hydroquinone, polyhydroxybenzenes and 3-pyrazolidinones may be contained. In the lithographic printing plate of the present invention, an intermediate layer may be provided between the lithographic printing plate and the physical development nucleus layer, if necessary, and a protective layer as the uppermost layer may be provided in addition to the silver halide emulsion layer.

The developing solution used in the present invention includes developing agents such as hydroquinone, polyhydroxybenzenes, 3-pyrazolidinones, and alkaline substances such as potassium hydroxide, sodium hydroxide, lithium hydroxide, and sodium tertiary phosphate. Silver halide solvents such as sodium thiosulfate, potassium thiocyanate, alkanolamines, preservatives such as sodium sulfite, thickeners such as carboxymethylcellulose, antifoggants such as potassium bromide, 1-phenyl-5-mercaptotetrazole And a development modifier, for example, an additive such as a polyoxyalkylene compound. After the development, 1-phenyl-5 is added to improve the ink receptivity.
-A sensitizing treatment may be performed with a sensitizing solution containing a mercapto compound such as mercaptotetrazole, and a finishing solution containing gum arabic or the like may be applied for the purpose of preserving the plate.

The pH of the developer is usually about 10 to 14, preferably about 12 to 14. The pretreatment (for example, anodizing) of the aluminum support of the lithographic printing plate to be used,
It depends on the photographic element, the desired image, the type and amount of various compounds in the developer, the development conditions, and the like.

Wash for removing the gelatin layer
The turning off can be performed by rinsing with running water having a temperature of about 20 to 30 ° C.

[0050]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 An average diameter of about 5 μm was obtained by electrolytic surface roughening treatment and anodic oxidation.
A 0.30 mm thick aluminum plate having about 5,600 pits having a diameter of 0.03 to 0.30 μm per 100 μm ² on the plateau and having an average diameter of the pits of 0.08 μm was obtained. . This aluminum plate is anodized after the surface roughening treatment, and has an average roughness (Ra) of 0.5 to
It was 0.6 μm.

On this aluminum support, a palladium sulfide nucleus solution was applied and then dried. The amount of nuclei contained in the physical development nucleus layer was 3 mg / m ² .

The silver halide emulsion was prepared by using alkali-processed gelatin A having an average molecular weight of about 100,000, and adding potassium hexachloroiridate (IV) having an average particle size of 0.25 μm by a control double jet method to 0 mol / mol of silver. .
A silver bromoiodide chlorobromide emulsion containing 15 mol% of silver bromide and 0.4 mol% of silver iodide, which was doped with 006 mmol, was prepared. Thereafter, the emulsion was flocculated and washed with water.

This emulsion was further subjected to sulfur gold sensitization to give 2-
Mercaptobenzoic acid and 1-phenyl-5-mercaptotetrazole are each added in an amount of 1 mol per mol of silver halide.
0 ^-3 mol was added. The emulsion was divided and spectrally sensitized using the sensitizing dyes of the present invention shown in Table 1 and the sensitizing dyes of the following formulas 7 and 8 for comparison, each at 3 mg per 1 g of silver. Further, low-molecular-weight gelatin B having an average molecular weight of 10,000, low-molecular-weight gelatin C having an average molecular weight of 20,000 or the above-mentioned alkali-processed gelatin A was added to these silver halide emulsions in an amount of 5% by weight based on the alkali-processed gelatin A of the silver halide emulsion. Each of the emulsions had a total amount of 1.3 g of gelatin per 1.0 g of silver.
Was applied to an aluminum plate coated with the physical development nucleus layer and dried so that the silver amount was 2.0 g / m ² , to prepare a sample of the present invention and a comparative sample.

[0055]

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[0056]

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Immediately after manufacture and after storage for 5 days under the conditions of 50 ° C. and 80% relative humidity, these samples were passed through a transmission wedge original with an exposure machine using a xenon flash as a light source using an interference filter having a wavelength of 633 nm. The light was exposed for a short time, immersed in the following developer for diffusion transfer (20 ° C.) for 30 seconds, the silver halide emulsion layer was washed away with 30 ° C. warm water (wash off), and dried to obtain a wedge image sample.

Diffusion transfer developer 20 g of sodium hydroxide 20 g of hydroquinone 2 g of 1-phenyl-3-pyrazolidinone 2 g of anhydrous sodium sulfite 80 g of monomethylethanolamine 6 g of sodium thiosulfate / pentahydrate 8 g of sodium ethylenediaminetetraacetate 5 g of deionized water pH (25 ° C.) = 12.8

Next, for each sample, 633n
m at a resolution of 2400 dpi while changing the laser power with an output device using a red LD laser as a light source, and immersed in the diffusion transfer developer (22 ° C.) for 15 seconds.
The silver halide emulsion layer was subjected to a wash-off process with warm water, a plate making process was performed with a finishing solution, and then dried to obtain an image sample. As the output, the laser power at the time when the width of the ruled line of the negative and positive lines of 50 microns became the same was determined as the appropriate exposure.

Further, with the laser power for proper exposure,
A line image having a thickness of 8 to 24 μm (approximately 2 μm steps) was output, and after a plate making process, it was printed on a printing machine. Printing durability is
Evaluation was made according to the following criteria, based on the number of sheets on which a printed matter had poor ink riding or background stains. A: 100,000 sheets or more B: 5-100,000 sheets C: 50,000 sheets or less

The ink release property is measured by mounting the printing plate on an offset rotary printing press, placing the ink on the plate surface, sending fountain solution, and removing the ink stain on the non-image area. Was evaluated according to the following criteria. A: 10 or less B: 10 to 20 C: 20 to 50 D: 50 to 100 E: 100 or more

The degree of occurrence of spot-like white spots in the transferred silver image area was evaluated according to the following criteria. A: Not at all. B: Slightly occurs. C: Remarkably occurs.

Table 1 shows the results. The upper row shows the results immediately after production, and the lower row shows the results after storage.

[0064]

[Table 1]

As is clear from the results in Table 1, the aluminum lithographic printing plates of the present invention, Samples 2, 4 and 5,
Compared with the comparative sample, it has excellent printing durability, spot-like fog (white spots), and ink releasability. It was confirmed that this excellent performance was maintained even during the running process.

Example 2 In the preparation of the silver halide emulsion of Example 1, silver chloride 9
A silver chloroiodobromide emulsion containing 8 mol% and 0.4 mol% of silver iodide was used, and low molecular weight gelatins B and C were used as sensitizing dyes for photographic gelatin. Six samples of the present invention were prepared in the same manner except that they were used at 10% by weight and 50% by weight. Excellent results were confirmed for the four samples of the present invention containing low molecular weight gelatin, as in Example 1.

[0067]

As described above, in a lithographic printing plate having a physical development nucleus between an aluminum support and a silver halide emulsion layer, by using a specific sensitizing dye and low molecular weight gelatin, the aluminum support by storage can be used. A lithographic printing plate suitable for scanning exposure was obtained, which was not adversely affected by the body and was excellent in printing durability and ink detachability.

Claims (1)

[Claims] 1. A lithographic printing plate having a physical development nucleus between an aluminum support and a silver halide emulsion layer, wherein the silver halide emulsion layer contains a sensitizing dye having no acid group,
An aluminum lithographic printing plate characterized in that the silver halide emulsion layer and / or a layer below the emulsion layer contains low molecular weight gelatin.