JPH1152577A - Lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithographic printing plate high in printing resistance and good in running processing aptitude, superior in ink removability and using a silver complex salt diffusion transfer method and by incorporating a photographic gelatin and a gelatin having a specified average molecular weight. SOLUTION: The photosensitive material for this lithographic printing plate has a silver halide emulsion layer containing the photographic gelatin and the low molecular weight gelatin having an average molecular weight of about 50,000 or less, preferably, that in the range about 3,000- about 30,000. A preferable amount of the low molecular weight gelatin to be added into the silver halide emulsion layer is 1-150 weight % of the photographic gelatin, preferably, 2-100 weight % in the case of an average molecular weight of <= about 30,000, and in the case of about 30,000- about 50,000, in an amount of 3-200 weight %, preferably, 5-150 weight % of the photographic gelatin.

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
The printing plate has various problems as compared with a DTR printing plate using paper or a film as a support. For example, a silver halide emulsion layer that is not substantially hardened has a remarkably high degree of swelling, so that it swells during development, which causes a problem that image quality, particularly, reproducibility of fine lines is reduced. This reduction in image quality is a particularly important problem in printing plates for scanning exposure such as an argon laser, a He-Ne 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, the silver halide emulsion is required to have a considerably high sensitivity, so that it has a drawback that fogging is likely to occur, and furthermore, the storage stability is deteriorated. Therefore, a printing plate stored for a long period of time has a problem that background stains are liable to occur, and in particular, the so-called running process suitability for developing a large amount of printing plates is deteriorated.

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.

Japanese Patent Application Laid-Open (JP-A) No. 8-110641 discloses an aluminum printing plate using gelatin having an average molecular weight of 70,000 or less, and describes that use of such gelatin improves ink receptivity. . However, when the average molecular weight of gelatin is small, the ink receptivity is easily improved, but there is a problem that the ink removal property is reduced by the running treatment.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an aluminum plate as a support, which has high printing durability, good running processing suitability, and excellent ink detachability.
It is an object of the present invention to provide a DTR planographic printing material particularly suitable for scanning exposure.

[0013]

The above objects of the present invention have been attained by using a combination of photographic gelatin and low molecular weight gelatin having an average molecular weight of about 50,000 or less.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lithographic printing material having a physical development nucleus between an aluminum support and a silver halide emulsion layer, wherein the silver halide emulsion layer has a photographic gelatin and an average molecular weight of about 50,000. An aluminum lithographic printing material comprising a combination of the following low molecular weight gelatins:

Further, the present invention relates to a lithographic printing material having a physical development nucleus between an aluminum support and a silver halide emulsion layer, wherein the silver halide emulsion layer has a low molecular weight of about 50,000 or less with respect to photographic gelatin. An aluminum lithographic printing material comprising gelatin and a low molecular weight gelatin having an average molecular weight of about 50,000 or less below the silver halide emulsion layer.

The low molecular weight gelatin used in the present invention is:
For example, JP-A-1-158426 and JP-A-4-34053
It can be produced by various methods described in No. 9, etc., preferably by an enzymatic decomposition treatment. The average molecular weight is about 50,000 or less, preferably about 3,000 to about 3
It is in the range of about ten thousand. An average molecular weight of 50,000 or less is not a strictly critical numerical value, and is, for example, considered to be acceptable up to an upper limit of about 5%. 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. 10,000 or less gelatin is 1-1
Gelatin having 50% by weight, preferably 2 to 100% by weight, and an average molecular weight of about 30,000 to about 50,000 is preferably added in an amount of 3 to 200% by weight, preferably 5 to 150% by weight.

The low molecular weight gelatin used in the present invention is:
Further, it is used below the above-mentioned silver halide emulsion layer, that is, as a nucleus layer or an intermediate layer between the emulsion layer and the nucleus layer which may be provided as necessary. In that case, low molecular weight gelatin may be used alone or in combination with photographic gelatin (the ratio is about the same as that of the emulsion described above). Of course, it may be used in a plurality of layers, for example, a silver halide emulsion layer and a layer below the silver halide emulsion layer.

The silver halide emulsion layer can be spectrally sensitized with a known sensitizing dye according to the wavelength of a light source such as a laser. For example, sensitizing dyes represented by the following general formulas (I), (II) and (III) are used.

[0019]

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In the formula, Z ^{1 to} Z ⁵ represent an atomic group necessary for forming a 5- or 6-membered heterocyclic ring, and when there are two or more heterocyclic rings, 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 of 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.

Preferred examples of W ¹ include the following.

[0023]

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The following are specific examples of the sensitizing dye.

[0025]

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[0026]

Embedded image

[0027]

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[0028]

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These dyes may be used alone or 2
More than one species may be used in combination. The use amount of these sensitizing dyes is not particularly limited, but 1 × 10 5 per mol of silver halide.
^-7 to 1 × 10 ^-2 mol, preferably 1 × 10 ^-6 to 1 × 10 ^-3 mol. The timing of addition may be any time before the silver halide emulsion is coated.

In general, the surface of an aluminum support used for a lithographic printing plate is roughened in order to improve wettability (water retention) with a fountain solution during printing and to improve adhesion to a 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 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 physical development nucleus generally 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 or the like. 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.

For 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 generally 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 which is preferable for the lithographic printing plate of the present invention is preferably an alkali-processed 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 types of silver halide emulsions. In particular, those in which silver chloride has a halogen composition of 70 mol% or more are particularly preferred.

The average grain size of the silver halide crystals is 0.1.
It is 5 to 0.5 μm, preferably 0.20 to 0.45 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 a silver halide crystal, 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 emulsion layer of the lithographic printing plate of the present invention may optionally contain an anion, a cation, a betaine, a nonionic surfactant, a thickening agent such as carboxymethyl cellulose, a coating aid such as an antifoaming agent, etc. 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 40 ° C.

[0046]

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 using an average molecular weight of 1
Using 100,000 photographic gelatin A, a control double jet method, doped with potassium hexachloroiridate (IV) having an average particle size of 0.25 μm and 0.006 mmol per mol of silver, 15 mol% of silver bromide, Silver iodide 0.4
A mol% silver chloroiodobromide emulsion was prepared. Thereafter, the emulsion was flocculated and washed. Further, after this emulsion was subjected to sulfur gold sensitization, a stabilizer was added, and then the emulsion was spectrally sensitized using a sensitizing dye (D-8) (Emulsion A).

Instead of photographic gelatin A, gelatin B having an average molecular weight of 70,000 or gelatin C having an average molecular weight of 40,000
In the same manner as Emulsion A except that
Emulsion C was prepared.

Next, the emulsion A was divided into 5 parts, and as additional gelatin, the gelatin A, the gelatin B, the gelatin C, the gelatin D having an average molecular weight of 20,000 or the gelatin E having an average molecular weight of 10,000 were converted into gelatin A for photography. It was added in a proportion of 20% by weight. Similarly, as an additional gelatin, gelatin B was added to the emulsion B, and gelatin C was added to the emulsion C at a ratio of 20% by weight based on the gelatin of the emulsion. All emulsions were subjected to a final adjustment so that the total amount of gelatin was 1.2 g with respect to 1.0 g of silver.
g / m ² was applied to the aluminum plate coated with the physical development nucleus layer and dried to prepare lithographic printing plates of the present invention and comparative examples.

For 50 plates of each of these samples, 6
The output was performed at a resolution of 2400 dpi while changing the laser power with an output device using a 33 nm red LD laser as a light source, and immersed in a developer for diffusion transfer (22 ° C.) for 15 seconds,
The silver halide emulsion layer was washed off with warm water at 35 ° C., subjected to plate making with a finishing solution, and dried to obtain a lithographic printing plate. 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.

These lithographic printing plates were printed on an offset rotary printing press. The printing durability was evaluated according to the following criteria, based on the number of sheets on which the printed matter had poor ink running or soiling. 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, feeding dampening water, 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

Diffusion transfer developer Sodium hydroxide 20 g Hydroquinone 20 g 1-Phenyl-3-pyrazolidinone 2 g Anhydrous sodium sulfite 80 g Monomethylethanolamine 6 g Sodium thiosulfate (pentahydrate) 8 g Sodium ethylenediaminetetraacetate 5 g 1000 ml with deionized water did. pH (25 ° C.) = 13.4

Table 1 shows the results. The upper row shows the results of the first edition, and the lower row shows the results of the 50th edition.

[0057]

[Table 1]

As is clear from the results in Table 1, Samples 5 to 7, which are the aluminum lithographic printing plates of the present invention, are superior in the printing durability and the ink detachability as compared with Comparative Samples 1 to 4. In particular, it was confirmed that this excellent performance was maintained even during the running process.

Example 2 In the preparation of the silver halide emulsion A of Example 1, a silver chloroiodobromide emulsion comprising 98 mol% of silver chloride and 0.4 mol% of silver iodide and a sensitizing dye were prepared according to (D-10). Emulsion A-2 was prepared in the same manner as in Sample 6 of Example 1 except that (1) was used. Aluminum support coated with physical development nuclei of Example 1 and emulsion A-2
In the meantime, 0.5 g of each of gelatins A to E of Example 1 was applied per 1 m ² to provide an intermediate layer, thereby preparing five lithographic printing plates of the present invention. When printing was performed in the same manner as in Example 1, the samples using gelatins C to E for the intermediate layer were superior to the samples using gelatins A and B for the intermediate layer in terms of ink detachability and printing durability. Was.

[0060]

According to the above-described embodiment, a lithographic printing plate having a physical development nucleus between an aluminum support and a silver halide emulsion layer is used in combination with photographic gelatin and low molecular weight gelatin having an average molecular weight of about 50,000 or less. By doing
Even in the case of the running treatment, a lithographic printing plate excellent in printing durability and especially in ink detachability and suitable for scanning exposure was obtained.

Claims (2)

[Claims] 1. A lithographic printing material having physical development nuclei between an aluminum support and a silver halide emulsion layer, wherein the silver halide emulsion layer has a photographic gelatin and an average molecular weight of about 5
An aluminum lithographic printing material characterized by containing not more than 10,000 gelatin. 2. A lithographic printing material having a physical development nucleus between an aluminum support and a silver halide emulsion layer, wherein the silver halide emulsion layer has a photographic gelatin and an average molecular weight of about 5
An aluminum lithographic printing material containing up to 10,000 gelatin, and gelatin below the silver halide emulsion layer having an average molecular weight of about 50,000 or less.