JPH07271039A - Lithographic printing plate - Google Patents

Abstract

PURPOSE:To provide an aluminum lithographic printing plate capable of being handled even in a substantially bright room environment, having high picture quality and printing durability and obtained by using a silver complex salt diffusion transfer method. CONSTITUTION:A roughened and anodized aluminum sheet is used as a substrate, a physical developing nucleus layer is formed thereon, and a silver halide emulsion layer contg. 10<-8> to 10<-3>mol of water-soluble rhodium salt per mol of silver halide and/or 0.2-200mg of org. desensitizer per mol of silver halide is further furnished thereon to constitute a monosheet-type lithographic printing plate. The working environment is improved and the quality is stabilized by using this aluminum lithographic printing plate capable of being handled in a substantially bright room environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate using an aluminum plate as a support, and more particularly to a lithographic printing plate using a silver complex salt diffusion transfer method which can be handled substantially in a bright room environment.

[0002]

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

As described therein, a lithographic printing plate using the DTR method is a two-sheet type in which a transfer material and an image receiving material are separately provided, or a monolith in which they are provided on a single support. Two types of sheet type are known.
For a two-sheet type lithographic printing plate, see JP-A-57
It is described in detail in Japanese Patent Laid-Open No. 158844. For mono-sheet type, Japanese Patent Publication No. Sho 48-30562
No. 51-15765, JP-A-51-111103.
No. 52-150105 and the like.

A lithographic printing plate using paper as a support is difficult to perform high-quality printing including printing durability because of plate elongation during printing and water penetration. A film support is used for the purpose of improving these problems and improving printing performance. For example, a cellulose acetate film, a polyvinyl acetal film, a polystyrene film, a polypropylene film, a polyethylene terephthalate film, or a composite film obtained by coating a polyester film, a polypropylene film, a polystyrene film or the like with a polyethylene film can be used as a support.

However, the lithographic printing plate having a film as a support has improved printing elongation, water retention and printing, although it is improved in plate extensibility and water penetration as compared with a paper-based printing plate. There is a problem in terms of ease of printing on the machine.

Therefore, in order to solve various problems of the above-mentioned planographic printing plate using a paper or film as a support, a silver salt type planographic printing plate using a metal, particularly an aluminum plate as a support is known. The details are described in JP-A-57-118244, JP-A-57-158844, JP-A-63-260491, JP-A-3-116151, and JP-A-4-282295.

JP-A-63-260491, JP-A-3-
No. 116151, No. 4-282295, and the like, a roughened and anodized aluminum plate is used as a support, and physical development nuclei are carried thereon, and a photosensitive silver halide emulsion is further provided thereon. Mono sheet type with layers DT
A lithographic printing plate utilizing the R method is detailed. According to it, after the planographic printing plate is imagewise exposed and DTR developed,
The silver halide emulsion layer is washed with warm water and removed to prepare a printing plate. However, these patents are technologies aimed at preventing the corrosion of the aluminum plate caused by the contact between the silver halide emulsion and the aluminum plate, and the image quality of the transferred silver image, the ink acceptability, and the printing durability are improved. The point was not enough.

In general, an aluminum support used for a lithographic printing plate has a roughened surface in order to improve wettability (water retention) with dampening water during printing and to improve adhesion with a photosensitive layer. Is done. This roughening treatment (so-called graining) is performed by mechanically roughening treatment such as ball graining, wire graining, brush graining, or by chemically dissolving aluminum with chloride, fluoride or the like. There are known a chemical roughening treatment, an electrolytic roughening treatment performed by electrochemically dissolving aluminum, and a roughening method using these methods in combination. For example, JP-A-48-28123,
53-123204, 54-146234, 55-25381, 55-132294, 56-.
55291, 56-150593, 56-28.
893, 58-167196, U.S. Pat.
44,510, 3,861,917, 4,
No. 301,229 and so on. Regarding the surface shape of the aluminum plate, U.S. Pat. No. 2,344,510 has a grain structure in which mechanical roughening and electrolytic roughening are combined to form a superposed composite, and U.S. Pat. No. 4,301,229 is a pit. Cumulative frequency distribution of diameter and centerline average roughness, U.S. Pat. No. 3,861,917 is rough surface depth, Canadian patent 955449 is rough mountain peak height and diameter, West German patent 1,813, No. 443 describes the height difference of rough surfaces.

After such a surface-roughening treatment, anodizing treatment is carried out in an electrolytic solution such as sulfuric acid, phosphoric acid, nitric acid or a mixture thereof.

As described above, as the surface treatment of the aluminum plate for a printing plate, an extremely large number of roughened aluminum plates having different shapes and structures of the rough surface have been proposed depending on the type of the planographic printing plate and the printing application. However, in the lithographic printing plate targeted by the present invention, in addition to the function of improving the wetting (water retention) with dampening water during printing and improving the adhesion with the photosensitive layer, halogenated Diffusion transfer development of silver affects the printing function of the silver film formed on the aluminum surface. Specifically, what surface shape the aluminum plate has in terms of ink acceptability and printing durability. No one knew what was preferable. Further, various factors for controlling the diffusion transfer development of silver halide to form a silver image of high image quality and preferable in terms of printing durability on the aluminum surface have not been clarified.

At present, a PS (Pre-Sensitized) plate in which a photosensitive material layer such as a photopolymer is provided on an aluminum plate which is widely used in the planographic printing field can be handled substantially in a bright room environment. .

The PS plate is manufactured by applying a photosensitive substance such as a photopolymer onto an aluminum plate which has been subjected to surface treatment such as surface roughening treatment and anodic oxidation treatment and drying. Since the PS plate has sensitivity in the ultraviolet region, it can be handled under safe light containing substantially no ultraviolet light, that is, in a substantially bright room, and is exposed by a light source containing a large amount of ultraviolet light. After image exposure with ultraviolet rays, a plate-making process such as development, washing with water, gumming, etc. is performed to complete a printing plate. The undissolved photosensitive layer formed by the development process forms an image part, and the part where the photosensitive layer is removed and the aluminum surface is exposed becomes hydrophilic to form a non-image part.

Although PS plates are widely used as lithographic printing plates, they have some problems. When the image is exposed, the PS plate is brought into close contact with the film and exposed to ultraviolet rays. However, since the PS plate has low sensitivity, it is necessary to expose it with strong ultraviolet rays for a long time. Intense ultraviolet rays are bad for the eyes and are not preferable as a working environment. Further, a large amount of developer containing a highly alkaline agent, an organic solvent, etc. is used for the development processing.
It is not preferable to use such a developing solution in the working environment, and a large amount of waste solution is a serious problem in terms of global environmental protection. Other than this, improvements such as stabilization of quality and speeding up of processing are being continued.

Under the above circumstances, regarding the planographic printing plate using an aluminum plate as a support using the silver complex salt diffusion transfer method, the technology relating to the prevention of corrosion of the aluminum surface, the development processing method, etc. are described in the above-mentioned patent specifications. Although it is disclosed in a book or the like, there is no mention of a lithographic printing plate using an aluminum plate as a support, which can be handled in a bright room environment and has a high image quality and a high printing durability and which uses a silver complex salt diffusion transfer method. Absent.

[0015]

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to use a silver complex salt diffusion transfer method which can be handled in a substantially bright room environment and has high image quality and high printing durability. It is to provide a novel lithographic printing plate having an aluminum plate as a support.

[0016]

The above object of the present invention is to use a surface-roughened and anodized aluminum substrate as a support, on which a physical development nucleus layer is provided, and further 1 mol of silver halide. 10-3 to 10-8 mol of water-soluble rhodium salt and / or 0.2 to 2 per mol of silver halide
This is achieved by a monosheet type lithographic printing plate provided with a photosensitive silver halide emulsion layer containing 00 mg of an organic desensitizer.

As the water-soluble rhodium salt used in the present invention, conventionally known ones are used, but typically, rhodium monochloride, rhodium dichloride, rhodium trichloride, rhodium ammonium chloride and the like are used. Addition amount is 10-8 per mol of silver halide
It may be in the range of 10 @ -3 mol. The rhodium salt is generally preferably used at the time of precipitation of silver halide or physical ripening, but it may be at any time thereafter.

Organic desensitizers are generally known to be used directly in positive-working silver halide emulsions. Specific examples of such organic desensitizers are described in numerous patent specifications and documents, and all of them have the same action in the present invention. For example, Japanese Patent Publication No. 36-17595 and Japanese Patent Publication No. 39-20261, Dosho 4
0-26751, Dosho 43-13167, Dosho 45-8
833, Dosho 47-8746, Dosho 47-10197,
50-37530, JP-A-48-24734, 49-84639, 56-142525, US Pat. No. 2,271,229, 2541472, 30.
No. 35917, No. 3062651, No. 31244
Compounds described in the specifications such as No. 58, No. 33266867, No. 367254 and the like can be used. Specific examples are shown below. (A) 1,3-diethyl-1'-methyl-2'-phenylimidazo [4,5, b] -quinoxalino 3'-indolocarbocyanine iodide (B) pinacryptol yellow (C) 1,1 ', 3,3, 3 ′, 3′-hexamethyl-5,5′-dinitroindocarbocyanine / P-toluenesulfonate (D) 5,5-dichloro-3,3′-diethyl-6,
6'-Dinitrothiacarbocyanine iodide (E) 1,1'-dimethyl-2,2'-diphenyl-3,3'-indolocarbocyanine bromide (F) 1,1 ', 3,3'-tetraethylimidazo [4 5-b] Quinoxanocarbocyanine chloride (G) 5-m-nitrobenzylidene rhodanine (H) 6-chloro-4-nitro-nitrobenzotriazole (I) 1,1'-dibutyl-4,4'-bipyridinium Dibromide (J) 1,1'-ethylene-2,2'-bipyridinium dibromide (K) 4- (Pn-amyloxyphenyl) -2,6
-Di (P-ethylphenyl) thiapyrium perchlorate (L) 2-mercapto-4-methyl-5-nitrothiazole (M) 2- (O-nitrostyryl) -3-ethylbenzothiazolium P-toluenesulfonate (N) 2- (P -Nitrostyryl) -quinoline P-toluenesulfonate (O) Phenosafuran (P) Pinacryptol green (Q) 2,3-Dimethyl-6-nitro-benzothiazolium P-toluenesulfonate

The amount of the organic desensitizer used is selected in the range of 0.2 to 200 mg, preferably 1 to 50 mg, per mol of silver halide. As for the timing of addition, it is generally added after completion of aging.

The aluminum support used in the present invention is a surface-treated aluminum plate used for printing, and has been subjected to a generally roughening treatment (so-called graining). For the roughening,
As mentioned above, mechanical surface roughening treatment, chemical surface roughening treatment,
And electrolytic graining treatment, and a graining method using these methods in combination. In the present invention, the diameter is 0.03
~ 0.30 µm pits have 500 or more per 100 µm ² , and the average diameter of these pits is 0.05 ~
A rough aluminum plate having a thickness of 0.20 μm is preferable.

In the lithographic printing plate targeted by the present invention, the inventors of the present invention are concerned with the rough surface state of the aluminum plate in terms of the quality of the transferred and developed silver that governs image quality, ink acceptability and printing durability. As a result of diligent examination based on the idea that
It has been found that by using a roughened and anodized aluminum plate having a large number of extremely small pits (holes), a transfer silver having excellent image quality and very strong for printing is formed. That is, the lithographic printing plate of the present invention using the above-mentioned specific rough surface aluminum plate is rapidly dissolved in the silver halide emulsion layer by the silver halide solvent contained in the diffusion transfer developing solution, Diffused over the surface,
It is estimated that the presence of a large number of minute pits causes favorable diffusion control and leads to high image quality. Also, by the preferred diffusion transfer development, transfer silver is formed in a large number of minute pits and has an anchoring effect, and the transfer silver forms a continuous and dense lipophilic layer and adheres to the aluminum plate. Therefore, the transfer silver does not drop even with long printing,
It is considered to exhibit high printing durability.

The surface-roughened and anodized aluminum plate used in the present invention is 50,000 using a scanning electron microscope.
It can be easily confirmed by the photograph of the magnification of double. The number of pits having a diameter of 0.03 to 0.30 μm is 500 per 100 μm ² , preferably about 1,
There are more than 000. The upper limit is preferably about 15,000. The average diameter of pits having a diameter of 0.03 to 0.30 μm is 0.05 to 0.20 μm, preferably 0.05 to 0.15 μm. The diameter of the pit is the dimension when the diameter of the pits other than the circular shape is regarded as the circular shape. The center depth of this pit is ⅓ (0.01 to 0.10 μm) or more of the diameter of the pit,
Preferably 1/2 (0.015 to 0.15 μm) to 3
(0.03 to 0.90 μm) is desirable.

In the above-mentioned JP-A-56-28893, a plateau (primary structure) and a pit (plateau surface) are formed on the aluminum surface by using mechanical surface roughening, chemical etching and electrolytic surface roughening in combination. Secondary structure that can be
The grain of the composite structure consisting of is described. The fine pits of the present invention preferably have a composite structure existing on large pits (plateaus) having an average diameter of 3 to 15 μm. The projected area of the small pits is preferably about 5 to 40%, and the projected area of the large pits (plateau) is 50%.
About 95% is preferable. The center line average roughness (Ra) is preferably in the range of 0.3 to 1.0 μm. The aluminum plate having such a surface shape of the present invention is mechanically roughened,
It can be relatively easily found depending on the conditions of chemical surface roughening treatment, electrolytic surface roughening treatment, and anodizing treatment method.
If the number of micro pits is less than 500 or only the large pits (plateau) without the micro pits are mentioned above, 100 μm of pits with an average diameter of 0.30 μm
^Even if the number is 500 or more per ² , the ink acceptability and printing durability are inferior to those of the planographic printing plate of the invention.

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 μm.
A range of m is preferred. Desmutting treatment is preferably performed prior to the anodizing treatment. That is, the roughened aluminum substrate is treated with 10-50% hot sulfuric acid (4
0-60 ℃) or dilute alkali (sodium hydroxide, etc.)
The smut adhering to the surface is removed by treating with.

After the anodic oxidation treatment, a post treatment can be carried out if necessary. For example, the method of immersion treatment in an aqueous solution of polyvinylphosphonic acid disclosed in British Patent No. 1,230,447 is used. Also,
An undercoat layer of a hydrophilic polymer may be provided if necessary, but it is selected depending on the properties of the photosensitive layer provided thereon.

The physical development nuclei of the physical development nuclei layer provided on the aluminum support may be known ones commonly used in the silver complex salt diffusion transfer method, for example, colloids of gold, silver, etc., and further palladium, zinc. A metal sulfide obtained by mixing a sulfide with a water-soluble salt such as can be used. For the details and the manufacturing method thereof, the techniques described in JP-B-48-30562, JP-A-49-55402 and JP-A-53-21602 can be used.

Silver halide, silver chlorobromide, silver chloroiodobromide, and silver chloroiodide are used as the silver halide used in the photosensitive silver halide emulsion provided on the physical development nucleus layer, and any of them is used. A silver halide containing 80 mol% or more, preferably 90 mol% or more of silver chloride.

In the present invention, a negative type lithographic printing plate can be prepared by using a direct positive silver halide emulsion as the photosensitive silver halide emulsion. Direct positive silver halide emulsions are disclosed in US Pat. No. 3,501,307.

The emulsion may be mixed by any known method such as forward mixing, reverse mixing and simultaneous mixing. The method for preparing the emulsion may be any of the ammonia method, neutral method and acidic method. The size distribution of the silver halide grains may be either monodisperse or heterodisperse, but monodispersion is preferred for the uniformity of grain sensitivity. The crystal habit of the particles may be cubic, octahedral, or any other type.
The particle size is 1 μm or less, preferably 0.5 μm or less. More preferably, it is 0.3 μm or less. This is because it is necessary to prevent the developed silver particles from becoming rough and to make them finer in order to save silver.

As the protective colloid of the light-sensitive silver halide emulsion, various gelatins such as acid-treated gelatin, alkali-treated gelatin, gelatin derivatives and grafted gelatin can be used, and polyvinylpyrrolidone, various starches, albumin, polyvinyl alcohol, A hydrophilic polymer compound such as gum arabic or hydroxyethyl cellulose may be contained.

The emulsion thus prepared can be chemically sensitized (sulfur sensitization, gold sensitization, reduction sensitization, etc.) with a chemical sensitizer. However, chemical sensitization may not be performed at all.

The silver halide emulsion obtained by the present invention is used for general photographic purposes such as stabilizers, antifoggants, anti-irradiation agents, film physical property modifiers, surfactants, hardeners, matting agents and developing agents. The additives used in the above can be included.

The silver halide emulsion layer thus prepared can be directly coated on the physical development nuclei layer, but an intermediate layer such as gelatin may be provided to facilitate peeling. . Further, it may have a hydrophilic colloid layer such as gelatin for protecting the surface of the light-sensitive material.

The lithographic printing plate of the present invention is exposed mainly by a light source rich in ultraviolet light used in the field of printing, for example, a mercury lamp, an ultrahigh pressure mercury lamp, a metal halide, or an ultraviolet laser light source such as an ultraviolet argon laser.
Further, both before and after the above exposure, safe handling for a long time under bright bright room light can be performed.

The lithographic printing plate of the present invention is generally subjected to diffusion transfer development treatment with an alkali developing solution after imagewise exposure to remove the residual emulsion film, and then, if necessary, a neutralizing solution, a fixing solution and a sensitizing solution. , A plate making process such as a dampening liquid and a printing process are performed. The developing solution is an ordinary photographic alkaline developing solution containing a developing agent such as hydroquinone, or a so-called alkaline activated developing solution in which the developing agent is substantially free of the developing agent by including them in the material. Anything can be used. In addition, depending on various purposes, some of these developers may be used in Japanese Patent Publication No.
The compounds described in JP-A 1-486, JP-A-52-150105 and the like are added.

The composition of the neutralizing solution, the fixing solution, the oil-sensitizing solution, the moistening solution and the like used in the present invention may be those known to those skilled in the art according to their respective purposes.

[0037]

EXAMPLES The present invention will be described below with reference to examples.
Of course, the present invention is not limited to this.

Example 1 An average diameter of about 5 μm was obtained by electrolytic graining treatment and anodic oxidation.
Having a diameter of 0.03 to 0.30 μm on the plateau of about 5,600 per 100 μm ² and having an average diameter of 0.08 μm and a thickness of 0.3 mm
To obtain an aluminum plate (A). This aluminum plate was anodized after the surface roughening treatment, and had an average roughness (Ra) of 0.5 to 0.6 μm.

On the pretreated aluminum support, a silver sol prepared by the Carrey, Lea method was applied so that the silver amount was 10 mg / m ² .

Subsequently, 10-5 mol of rhodium chloride salt was used per 1 mol of silver chlorobromide containing 95 mol% of silver chloride to precipitate silver halide by a conventional method, and physical ripening was carried out to obtain an average grain size. An emulsion having a diameter of 0.2 μm was obtained. This emulsion was desalted and redissolved, and then 7 mg of pinacryptol yellow as an organic desensitizer was added per 1 mol of silver halide, and a stabilizer and a surfactant were further added.

This emulsion was coated on the above aluminum support coated with silver sol so that the amount of silver was 1.5 g / m ² and the amount of gelatin was 1.0 g / m ² , and dried.

The lithographic printing plate prepared as described above is
After imagewise exposure using a bright room printer, diffusion transfer development was carried out at 20 ° C. for 30 seconds in the following alkaline developer. Phenidone B = 4-methyl-1-phenyl-3-pyrazolidone

After the diffusion transfer development, the emulsion layer was peeled off to prepare a lithographic printing plate on which a diffusion transfer silver image was formed.

When this sample was irradiated in a bright room of about 500 lux for 1 hour and then exposed and developed in the same manner as above, there was no change in sensitivity or tone, and a lithographic printing plate on which a diffusion transfer silver image was formed was obtained. Could be made. Furthermore, when this sample was subjected to imagewise exposure and then irradiated in the bright room for 15 minutes and similarly developed, there was no change in sensitivity or tone.

Example 2 In the above Example 1, the organic desensitizers (A), (E), (O) described above were used instead of the pinacryptol yellow.
Four types of lithographic printing plates were prepared in exactly the same manner except that each of (P) was added to the re-dissolved emulsion. When a light room environment suitability was tested in the same manner as in Example 1, a lithographic printing plate having good sensitivity and tone was obtained.

Comparative Example The same procedure as in Example 1 was repeated except that rhodium chloride salt was not added at the time of precipitation of the silver halide emulsion, and 0.15 mg of pinacryptol yellow was added to the emulsion after redissolution per mol of silver halide. A planographic printing plate was prepared. When this sample was exposed to light and developed in a bright room of about 300 lux for 30 minutes, the diffusion transfer silver image was an extremely thin image.

Example 3 The lithographic printing plates prepared in Example 1 and Example 2 were prepared by using a copy rapid fixing solution (Fixe) manufactured by Agfa.
After the printing plate treatment in r), printing machine Heidelberg TOK
(Headelberg offset printing machine trademark) and printed, 100,000 sheets could be printed and print quality was good. The sample of the comparative example was similarly subjected to the printing test, but it did not function as a lithographic printing plate because almost no ink was applied.

Example 4 The following Table 1 was obtained according to the difference in electrolytic surface roughening treatment and anodic oxidation.
An aluminum plate having a surface shape of and a thickness of 0.3 mm was obtained.

[0049]

[Table 1]

In Table 1, the number of pits is about 5 μm in average diameter.
0.03 to 0.30 μm diameter existing on a plateau of m
Pits per 100 μm ² , and the average diameter is the average value of the diameters of the pits. The average roughness (Ra) of these aluminum plates was 0.5 to 0.6 μm.

Lithographic printing plates A-1, B-1, C-1, D- were formed on these aluminum supports in the same manner as in Example 1.
1 and E-1 were produced.

The lithographic printing plate thus obtained was imagewise exposed, developed with the diffusion transfer developer described in Example 1, and immediately thereafter, the gelatin layer was washed off with running water (wash-off). Before the plate surface is dry, apply the plate surface protection liquid with absorbent cotton etc. and dry. The lithographic printing plate created in this way is used for printing on the Heidelberg TOK (Heidelberg) printing press.
The image quality and printing durability were evaluated by applying an offset printing machine (trademark).

Regarding the image quality, the one that can reproduce the negative ruled line and the positive ruled line of 10 μm at the same time on the printing plate surface which was exposed through the contact original and developed was marked as ◯, and the one that the negative ruled line and the positive ruled line of 15 μm could be simultaneously reproduced. The mark “Δ” indicates that the negative ruled line and the positive ruled line of 20 μm can be reproduced at the same time. The ink used is New Champion F Gloss Black N made by Dainippon Ink and printing durability is set by setting the plate pressure to 5 mm and printing is performed due to defective ink transfer in the image area or line skipping. It was evaluated by the number of prints when it became impossible. The results are shown in Table 2.

[0054]

[Table 2]

As is clear from the results shown in Table 2, the diameter is 0.0
3 to 0.30 μm pits 500 per 100 μm ²
More than one, and the average diameter of those pits is 0.0
Planographic printing plate A using an aluminum plate of 5 to 0.20 μm
It was found that -1, B-1, and C-1 were excellent in image quality and printing durability. On the other hand, a lithographic printing plate D- using an aluminum plate having an average pit diameter of 0.20 μm or more
From the results of 1 and E-1, it can be seen that A-1, B-1, and C-1 are more preferable.

[0056]

According to the present invention, an aluminum lithographic printing plate using a silver complex salt diffusion transfer system which can be handled in a substantially bright room environment and has high image quality and high printing durability can be produced.

Claims (3)

[Claims] 1. A lithographic printing plate having a physical development nucleus layer between a roughened and anodized aluminum support and a silver halide emulsion layer, wherein 10 mol per mol of silver halide are contained in the silver halide emulsion. -8 to 10-3 mol of water-soluble rhodium salt and / or 0.2 to 2 per mol of silver halide
A lithographic printing plate comprising 00 mg of an organic desensitizer. 2. A support having a rough surface aluminum plate having 500 or more pits having a diameter of 0.03 to 0.30 μm per 100 μm ² and having an average diameter of 0.05 to 0.20 μm. The planographic printing plate according to claim 1. 3. The lithographic printing plate according to claim 2, wherein the depth of the pit is 1/3 or more of the diameter.