JP3054719B2 - Method for producing a lithographic printing plate support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a lithographic printing plate support, and more particularly to a method for producing an aluminum support having good electrolytic surface roughening properties.

[0002]

2. Description of the Related Art An aluminum plate (including an aluminum alloy plate) is used as an aluminum support for a printing plate, particularly as a support for an offset printing plate. Generally, in order to use an aluminum plate as a support for an offset printing plate, it is necessary that the aluminum plate has appropriate adhesiveness to a photosensitive material and water retention. For this purpose, the surface of the aluminum plate must be roughened so as to have a uniform and dense grain. Since the surface roughening treatment has a remarkable effect on the printing performance and printing durability of the plate material when offset printing is actually performed after plate making, its quality is an important factor in plate material production. As a method for roughening the aluminum support for a printing plate, an AC electrolytic etching method is generally employed, and a normal sine-wave AC current is used as a current. Then, with an appropriate electrode such as graphite as a counter electrode, an alternating current is used to perform a surface roughening treatment on the aluminum plate.
Usually, it is performed in one process, but the pit depth obtained therefrom is generally shallow, and the printing durability is poor.
For this reason, various methods have been proposed so that an aluminum plate suitable as a support for a printing plate having a grain having uniform and dense pits deeper than the diameter thereof can be obtained. As a method therefor, a surface roughening method using a special electrolytic power source waveform (Japanese Patent Application Laid-Open No. 53-67507), a ratio of the quantity of electricity between the anode and the cathode during electrolytic surface roughening using an alternating current (Japanese Patent Application Laid-Open No. 54-65607), a power supply waveform (Japanese Patent Application Laid-Open No. 55-25381), a combination of energization amounts per unit area (Japanese Patent Application Laid-Open No. 56-29699), and the like are known. Further, a combination with mechanical roughening (Japanese Patent Application Laid-Open No. 55-142695) is also known.

On the other hand, as a method for manufacturing an aluminum support, an aluminum ingot is melted and held, and a slab (400 to 600 mm in thickness and 1000 to 2000 m in width) is prepared.
m, length 2,000-6000 mm), and after passing through a face milling process of cutting the impurity structure portion of the slab surface by a face mill at 3 to 10 mm each, in order to remove stress inside the slab and homogenize the structure, 480-540 ° C in a soaking furnace,
A soaking process is performed for 6 to 12 hours, followed by hot rolling at 480 to 540 ° C. 5 to hot rolling
After rolling to a thickness of 40 mm, cold rolling is performed to a predetermined thickness at room temperature. After that, in order to make the structure uniform and to obtain a plate having good flatness, annealing is performed to homogenize the rolled structure and the like, and then cold-rolled to a specified thickness and straightened. The aluminum support thus produced was used as a support for a lithographic printing plate. However, in the case of electrolytic surface roughening treatment, it is particularly susceptible to the effect of the target aluminum support, and when the aluminum support is manufactured through a process of melting and holding → casting → facing → soaking, the metal alloy component is added to the surface layer. Such variations have caused the lithographic printing plate to have a reduced yield.

[0004] Therefore, the manufacture of a lithographic printing plate support for producing a lithographic printing plate of excellent quality and good yield by reducing the variation in the material of the aluminum support and improving the yield of electrolytic surface roughening treatment. As a method, after the casting and hot rolling are continuously performed from the molten aluminum to form a hot-rolled coil of a thin plate, the aluminum support that has been cold-rolled, heat-treated and straightened is roughened. A method for producing a lithographic printing plate support characterized by the following was proposed. (Japanese Unexamined Patent Publication
-79798)

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to further improve the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 3-79798,
A method for manufacturing a lithographic printing plate support that can produce a lithographic printing plate of excellent quality and a high yield by further reducing the variation in the material of the aluminum support and further improving the yield of the electrolytic surface roughening treatment. To provide. Still another object is to provide a process with low running cost.

[0006]

Means for Solving the Problems The present inventors have intensively studied the relationship between the electrolytic surface roughening treatment of an aluminum support and found the present invention. That is, the above objects of the present invention are as follows: (1) Twin roll continuous casting of molten aluminum, hot rolling is continuously performed to form a hot rolled coil of a thin plate, and then cold rolling, heat treatment, and straightening are performed. In the method for producing a lithographic printing plate support, in which the performed aluminum support is subjected to a surface roughening treatment, a coil having a thickness of 4 to 30 mm is formed by the hot rolling, and then a heat treatment is performed at 300 ° C. or more.
Cold rolled, heat treated again at 300 ° C or higher,
This is achieved by a method for producing a lithographic printing plate support, characterized in that after being cold-rolled to a thickness of 0.3 mm, after correction, etching is performed for 1 μm or more and electrolytic surface roughening treatment is performed.

[0007] As a method for continuous twin roll casting of molten aluminum in the present invention, a thin plate continuous casting technique such as a hunter method or a 3C method has been put to practical use. It can be applied if possible to ３０30 mm. Japanese Patent Application Laid-Open No. 58-58963
JP-A-61-1456, JP-A-1-21544
No. 1 discloses a method for producing a continuous cast coil of a thin plate, and these methods may be used. The present invention is a continuous casting directly from molten aluminum,
By performing the heat treatment and the cold rolling, the generation and mixing of oxides are reduced as compared with the conventional process, and the step of facing is unnecessary. In the present invention, various methods such as mechanical surface roughening, chemical surface roughening, electrochemical surface roughening, and a combination thereof are used for the method of roughening the support for a lithographic printing plate. Mechanical graining methods include, for example, ball grain, wire grain, brush grain, and liquid honing. As an electrochemical graining method, an AC electrolytic etching method is generally adopted, and as an electric current,
A special alternating current such as a normal sine wave alternating current or a rectangular wave is used. In addition, as a pretreatment for the electrochemical graining, an etching treatment with caustic soda may be performed. First, the aluminum support is first alkali etched. Preferred alkaline agents are caustic soda, caustic potash, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate and the like. Concentration 0.01-20
%, The temperature is suitably selected from the range of 20 to 90 ° C., and the time is selected from the range of 5 sec to 5 min, and it is necessary to perform etching of 1 μm or more. Subsequently, since a substance (smut) insoluble in alkali remains on the surface of the alkali-etched aluminum plate, desmutting may be performed as necessary. The pre-processing is as described above,
In the present invention, electrolytic surface roughening treatment is subsequently performed. That is, AC electrolytic etching is performed in an electrolytic solution mainly containing hydrochloric acid or nitric acid. The frequency of the alternating current is 0.1 to
100 Hz, more preferably 0.1 to 1.0 or 10 to 10
60 Hz. The liquid concentration is 3 to 150 g / I,
More preferably, the amount of aluminum dissolved in the bath is preferably 5 to 50 g / I, and the amount of aluminum dissolved in the bath is preferably 50 g / I or less, more preferably 2 to 20 g / I. Additives may be added if necessary, but in the case of mass production, it becomes difficult to control the liquid concentration. The current density is 5 to 100 A / dm.
² is suitable, but 10 to 80 A / dm ² is more preferable. The power supply waveform is selected as appropriate depending on the quality required and the components of the aluminum support used.
It is more preferable to use the special alternating waveforms described in JP-B-56-19280 and JP-B-55-19191. Such waveform and liquid conditions are appropriately selected depending on the quality required together with the quantity of electricity, the components of the aluminum support used, and the like.

[0008] The electrolytically roughened aluminum is then immersed in an alkaline solution to dissolve the smut as part of the smut treatment. As the alkaline agent, there are various types such as caustic soda, and the pH is 10 or more, and the temperature is 25 to 60 ° C.
It is preferable to carry out in a very short time of 10 sec. Next, it is immersed in a liquid mainly composed of sulfuric acid. As for the sulfuric acid solution conditions, the concentration is 50 to 400 g / I, and the temperature is 25 to 6 which is much lower than the conventional one.
5 ° C. is preferred. If the concentration of sulfuric acid is 400 g / I or more, or the temperature is 65 ° C. or more, corrosion of the treated layer and the like becomes large, and in the case of aluminum alloy containing manganese of 0.3% or more, sand which is electrochemically roughened is used. My eyes collapse. The dissolution amount of the aluminum base is 0.2 g / m ²
When the above is etched, the printing durability decreases, so
It is preferable that the content be 0.2 g / m ² or less. The anodic oxide film has a thickness of 0.1 to 10 g / m ² , more preferably 0.3 to 10 g / m ² .
5 g / m ² is preferably formed on the surface.

The anodic oxidation treatment conditions vary depending on the electrolytic solution to be used, and thus cannot be unconditionally determined. However, in general, the concentration of the electrolytic solution is 1 to 80% by weight, and the liquid temperature is 5 to 70%.
° C, current density 0.5-60 A / cm ² , voltage 1-100
V, an electrolysis time of 1 second to 5 minutes is appropriate. The grained aluminum plate having an anodized film obtained in this way is stable and excellent in hydrophilicity, so that a photosensitive film can be immediately provided on the surface, but if necessary, the surface can be further coated. Processing can be performed. For example, a silicate layer of the alkali metal silicate described above or an undercoat layer of a hydrophilic polymer compound can be provided.
The coating amount of the undercoat layer is preferably from 5 to 150 mg / m ² . Next, a photosensitive coating film is provided on the aluminum support thus treated, and after image exposure, development and plate making, the film is set in a printing machine and printing is started.

[0010]

The present invention will be described in detail with reference to examples. However, the invention is not name limited only to this embodiment.

(Example- 1 ) A molten aluminum was put between φ600 cooling twin rolls to form a coil having a thickness of ± 10 mm.
And then cold-rolled to a thickness of 1 mm.
After a heat treatment at 0 ° C. for 30 minutes, it is cold-rolled again to a thickness of 0.3 mm, straightened, and subjected to aluminum coil (JIS 1050
Material) was created. The aluminum plate thus prepared was used as a support for a lithographic printing plate, and then etched with a 15% aqueous sodium hydroxide solution at a temperature of 50 ° C. to 2 μm (5.4 g / m ² ). 1 in sulfuric acid solution
It was immersed for 0 sec, desmutted, and washed with water. The support was further placed in a 16 g / I aqueous nitric acid solution,
The surface was electrochemically roughened using the alternating waveform current described in JP-A-1. As the electrolysis conditions, the anode voltage V _A = 1
At 4 V and cathode voltage Vc = 12 V, the quantity of electricity at the anode was set to 350 coulomb / dm ² . The support anodized film 2.5 g / m ² provided dry with 20% sulfuric acid, such a coil creates 100 a coil, the substrate B ₁ ~
B ₁₀₀ .

(Comparative Example 1) Melting and holding from an aluminum ingot → Slab casting → Face milling → Hot rolling to a thickness of 6 mm after soaking, further cold rolling, annealing at 400 ° C to 0.3 mm JIS1050 material was prepared by cold rolling (including straightening). The aluminum plate thus obtained was used as a support for a lithographic printing plate, and then 2 μm at 50 ° C. with a 15% aqueous sodium hydroxide solution.
m (5.4 g / m ² ) and after washing with water, 150 g
/ I, immersed in a sulfuric acid solution at 50 ° C. for 10 seconds, desmutted, and washed with water. Further, the support was electrochemically roughened in a 16 g / I aqueous nitric acid solution using an alternating waveform current described in JP-B-55-19191. The electrolysis conditions were as follows: anode voltage V _A = 14 V, cathode voltage Vc =
When the voltage at the anode is 12 V, the amount of electricity at the anode is 350 coulombs / dm ²
It was made to become. The support was provided with an anodic oxide film of 2.5 g / m ² in 20% sulfuric acid, and dried.
00 coils were created and designated C _{1 to} C ₁₀₀ . Board that was created as described above (B ₁ ~B ₁₀₀₎ a (C ₁ ~C ₁₀₀₎ below the composition, coating weight after drying was coated so as to become 2.0 g / m ² photosensitive layer Was provided. Photosensitive solution composition N- (4-hydroxyphenyl), methacrylamide / 2-hydroxyethyl methacrylate / acrylonitrile / methyl methacrylate / methacrylic acid (= 15: 10: 30: 38: 7 molar ratio) copolymer (average molecular weight) 5.00 g Hexafluorophosphate of condensate of 4-diazodiphenylamine and formaldehyde 0.5 g Phosphorous acid 0.05 g Dictriapable-BOH (Manufactured by Hodogaya Chemical Co., Ltd.) 0.1 g 2-methoxyethanol 100 g The transparent lithographic printing plate thus prepared was passed through a transparent negative film in a vacuum furnace. After exposing for 50 seconds with a 3 kw metal halide lamp from a distance of 1 m, developing with a developing solution of the following composition Gumming and was a lithographic printing plate with an aqueous solution. Developer composition Sodium sulfite 5 g Benzyl alcohol 30 g Sodium carbonate 5 g Sodium isopropylnaphthalene sulfonate 12 g Pure water 1000 g using plate-making lithographic printing plate, the result of printing in a normal procedure, in the embodiment 1, 100 coils all samples dirt 0 has been passed by clearing 100% or more printing, Comparative example 1 Sample of 13 coils out of 100 coils failed.

[0013]

As described above, the lithographic printing plate manufactured by the method for manufacturing a lithographic printing plate support of the present invention is superior in quality and uniform in comparison with the conventional lithographic printing plate, and the lithographic printing plate is made uniform. Is also remarkably good, and the rationalization of the production process of the aluminum support has a great effect of reducing the raw material cost. In particular, it greatly contributes to the quality improvement and cost reduction of the lithographic printing plate support.

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Claims (1)

(57) [Claims] 1. A twin roll continuous casting of molten aluminum,
A method for producing a lithographic printing plate support in which hot rolling is continuously performed to form a hot rolled coil of a thin plate, and then the aluminum support subjected to cold rolling, heat treatment and straightening is subjected to a surface roughening treatment. In the above, the thickness is 4 to 30 mm by the hot rolling.
After the coil is formed, heat-treated at 300 ° C. or more, cold-rolled, heat-treated again at 300 ° C. or more, cold-rolled again to a thickness of 0.3 mm, and 1 μm after straightening.
A method for producing a lithographic printing plate support, characterized in that an electrolytic surface roughening treatment is performed by etching at least m.