JP3244880B2 - Lithographic printing plate - Google Patents

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.

[0002]

2. Description of the Related Art A lithographic printing plate using a silver complex salt diffusion transfer method (DTR method) is described in "Photographic Silver Halide." 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 type 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. 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, polypropylene, or polystyrene film with a polyethylene film can be used as the support.

[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. These are described in detail 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-3-26049
JP-A-116151 and JP-A-4-282295 disclose that a roughened anodized aluminum plate is used as a support, a physical development nucleus is supported thereon, and a photosensitive silver halide emulsion layer is further provided thereon. A lithographic printing plate utilizing the DTR method in a monosheet type is described in detail. According to this method, the lithographic printing plate is subjected to image exposure and DTR development, and then the silver halide emulsion layer is removed by washing with warm water to prepare a printing plate. However, these patents are directed to preventing corrosion of the aluminum plate caused by contact between the silver halide emulsion and the aluminum plate, and in terms of ink receptivity of the transferred silver image and printing durability, It was not enough.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a lithographic printing plate having improved ink liquor and printing durability.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to provide a lithographic printing plate having a physical development nucleus between a roughened and anodized aluminum support and a silver halide emulsion layer having a diameter of 0.03 mm. Pit of ~ 0.30μm to 100μm
^This was achieved by a lithographic printing plate characterized in that an aluminum plate having at least 500 pits per ² and having an average diameter of those pits of 0.05 to 0.20 μm was used as a support.

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 (so-called graining) is performed by mechanically roughening such as ball graining, wire graining, and brush graining, or by chemically dissolving aluminum with chloride, fluoride, or the like. There are known a chemical surface roughening treatment, an electrolytic surface roughening treatment performed by dissolving aluminum electrochemically, and a surface roughening method using these methods in combination. For example, JP-A-48-28123,
No. 53-123204, No. 54-146234, No. 55-25381, No. 55-132294, No. 56-
No. 55291, No. 56-150593, No. 56-28
Nos. 893 and 58-167196, U.S. Pat.
No. 44,510, No. 3,861,917, No. 4,
Nos. 301 and 229. Regarding the surface shape of an aluminum plate, U.S. Pat. No. 2,344,510 discloses a grain structure in which mechanical roughening and electrolytic surface roughening are performed in an overlapping manner, and U.S. Pat. No. 4,301,229 discloses pits. Cumulative frequency distribution and center line average roughness of diameter, U.S. Pat. No. 3,861,917, Roughness Depth, Canadian Patent No. 954,449, Roughness Crest Height and Diameter, West German Patent 1,813, No. 443 describes a difference in elevation of a rough surface.

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

As described above, for the surface treatment of the aluminum plate for a printing plate, an extremely large number of roughened aluminum plates differing in the shape and structure of the roughened surface have been proposed depending on the type of the lithographic printing plate, the printing application and the like. However, in the lithographic printing plate to which the present invention is applied, it has not been known what surface shape of the aluminum plate is preferable in terms of ink acceptability and printing durability.

The present inventors have concluded that, in the lithographic printing plate to which the present invention is directed, how the transfer developed silver that governs ink acceptability and printing durability is related to the rough surface state of the aluminum plate. As a result of a thorough study based on the idea of whether or not there is a large number of extremely small pits (holes), it was found that a roughened and anodized aluminum plate forms transfer silver which is very strong for printing. The present invention has been completed. That is, in the lithographic printing plate of the present invention using the above-mentioned specific roughened aluminum plate, the transferred silver is formed in a large number of minute pits and has an anchoring effect, and the transferred silver is continuously dense. Since a highly lipophilic layer is formed and adhered to the aluminum plate, it is considered that transfer silver is not lost even in long printing, and high printing durability is exhibited.

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

Japanese Patent Application Laid-Open No. 56-28893 discloses that a plateau (primary structure) and a pit (surface of a plateau) are formed on an aluminum surface by using both mechanical surface roughening, chemical etching and electrolytic surface roughening. Secondary structure)
The grain of a composite structure consisting of The micro pit of the present invention preferably has a composite structure existing on a large pit (plateau) having an average diameter of 3 to 15 μm. The projected area of the small pit is preferably about 5 to 40%, and the projected area of the large pit (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 subjected to mechanical roughening treatment,
It depends on the combination of many conditions such as chemical surface roughening treatment, electrolytic surface roughening condition, anodic oxidation condition, aluminum plate alloy composition, etc., for example, acid type, acid concentration, electrolysis temperature, current density, It can be found relatively easily by adjusting the applied voltage and the like, performing electrolytic surface roughening treatment, and then performing anodic oxidation treatment. In the case where the number of the small pits is less than 500 or only the large pits without the small pits (plateaus), and the number of the pits having an average diameter of 0.30 μm is 500 or more per 100 μm ^{2, the} present invention can be applied. Only poor ink acceptability and printing durability are obtained compared to lithographic printing plates.

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.
The range of m is preferred. Note that desmutting is preferably performed prior to the anodizing. That is, the surface-roughened aluminum substrate is replaced with 10 to 50% hot sulfuric acid (4%).
0-60 ° C) or dilute alkali (such as sodium hydroxide)
The smut adhered to the surface is removed by the treatment.

After the anodic oxidation treatment, a post-treatment can be performed if necessary. For example, a method of dipping in an aqueous solution of polyvinylphosphonic 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 it is selected depending on the properties of the photosensitive layer provided thereon.

The physical development nuclei of the physical development nucleus layer used in the present invention may be those used in the known silver complex salt diffusion transfer method. For example, colloids such as gold and silver, and water-soluble salts such as palladium and zinc may be used. Metal sulfide mixed with sulfide can be used. Various hydrophilic colloids can be used as the protective colloid. For details and manufacturing method,
For example, Focal Press, London New York (1972), Andre Lott and Edith
See Weide, "Photographic Silver Halide Diffusion Processes".

Various hydrophilic colloids can be used as protective colloids in the photosensitive silver halide emulsion layer of the printing plate of the present invention. That is, various gelatins such as acid-treated gelatin, alkali-treated gelatin, gelatin derivatives, and grafted gelatin can be used, and hydrophilic polymer compounds such as polyvinylpyrrolidone, various starches, albumin, polyvinyl alcohol, gum arabic, and hydroxyethyl cellulose. Can be contained. Examples of the hydrophilic colloid used include gelatin, a gelatin derivative, polyvinyl alcohol, and polyvinylpyrrolidone. Preferably, a substantially hardener is used to facilitate release of the hydrophilic colloid layer after physical development. It is desirable to use a hydrophilic colloid layer containing no.

The types of the photosensitive silver halide emulsion used in the present invention include commonly used silver chloride, silver bromide, and silver halide.
It is selected from silver iodide, silver chlorobromide, silver chloroiodobromide, silver iodobromide and the like. The emulsion type may be either a negative type or a positive type. These silver halide emulsions can be chemically or spectrally sensitized as necessary.

The developer used in the present invention includes a developing agent such as polyhydroxybenzenes, 3-pyrazolidinones, and alkaline substances such as potassium hydroxide, sodium hydroxide, lithium hydroxide, tertiary sodium phosphate, and amines. Addition of compounds, preservatives such as sodium sulfite, thickeners such as carboxymethylcellulose, antifoggants such as potassium bromide, 1-phenyl-5-mercaptotetrazole, development modifiers such as polyoxyalkylene compounds, etc. Agents and the like can be included.

The pH of the developer is usually about 10 to 14, preferably about 12 to 14. The pretreatment (for example, anodic oxidation) 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-off for removing the gelatin layer can be performed by rinsing with running water at a temperature of about 20 to 30 ° C.

[0024]

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

Example An aluminum plate having a surface shape shown in Table 1 below and having a thickness of 0.30 mm was obtained by the difference in conditions of electrolytic surface roughening treatment and anodic oxidation.

[0026]

[Table 1]

In Table 1, the number of pits is about 5 μm in average diameter.
0.03 to 0.30 μm on the plateau of m
Is the number of pits of 100 .mu.m.times., 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.

A gelatin solution was added to a silver sol prepared by the Curey Lea method on these aluminum supports, and a physical development nucleus solution prepared so that the weight ratio of silver to gelatin was 2 was obtained. Applied. After drying, a silver halide emulsion layer was applied and dried to prepare a photosensitive lithographic printing plate.

After performing image exposure on the lithographic printing plate thus obtained, developing with a diffusion transfer developing solution described in Example 1 of JP-A-4-282295, the gelatin was immediately washed with running water. The layer was washed off (washed off).
Before the plate surface dries, apply a plate surface protection solution with absorbent cotton or the like and dry. The lithographic printing plate thus prepared was applied to a printing machine AB Dick 350CD (trademark of an offset printing machine manufactured by ABDick) to evaluate ink acceptability and printing durability.

The ink receptivity was evaluated based on the number of printed sheets until a printed material having a good image density was obtained while simultaneously starting paper feeding while bringing the ink roller into contact with the plate surface. The printing durability was evaluated based on the number of printed sheets when printing became impossible due to either poor ink application in the image area or line skipping. Table 2 shows the results.

[0031]

[Table 2]

[0032]

According to the present invention, it is possible to obtain a lithographic printing plate having good ink running and extremely high printing durability.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-11259 (JP, A) JP-A-61-100497 (JP, A) JP-A-61-117548 (JP, A) JP-A-62-100 143057 (JP, A) JP-A-62-143056 (JP, A) JP-A-62-285255 (JP, A) JP-A-3-116151 (JP, A) US Patent 3,861,917 (US, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/07 G03F 7/09 501 B41N 1/08 B41N 3/03

Claims (2)

(57) [Claims] 1. A lithographic printing plate having a physical development nucleus between a roughened and anodized aluminum support and a silver halide emulsion layer, wherein pits having a diameter of 0.03 to 0.30 μm are formed in an amount of 500 per 100 μm ^2. A lithographic printing plate comprising at least a plurality of pits and an aluminum plate having an average diameter of the pits of 0.05 to 0.20 μm as a support. 2. The lithographic printing plate according to claim 1, wherein the depth of the pit is not less than 1/3 of the diameter.