JPH0754111A - Production of substrate for planographic printing plate - Google Patents

Abstract

PURPOSE:To provide the planographic printing plate having a favorable electrolytic surface roughening property and excellent mechanical strength and appearance. CONSTITUTION:The caption number 1 denotes a melting and holding furnace where ingots are melted and held. The molten metal is sent from this furnace to a twin roll continuous casting device 2. Namely, a hot rolled coil of a sheet of 4 to 30mm is formed directly from the aluminum melt. This sheet is coiled by a coiler 3. The coil is thereafter rolled by a cold rolling mill 4, by which its thickness is reduced to 0.3-3.0mm. The rolled sheet is in succession treated by a heat treating stage (induction heating system) 5 and is subjected to two passes of intermediate annealing for 1-600 seconds at 500-660 deg.C and is again rolled by the cold rolling mill 4 as the final rolling, by which the thickness is reduced to 0.1-1.0mm. The sheet is thereafter straightened by a straightening device 6. The sheet material obtd. in such a manner is subjected to a surface roughening treatment. The induction heating is used twice for the heat treating stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a support for a lithographic printing plate, and more particularly to a method for producing an aluminum support having good electrolytic graining characteristics and excellent mechanical strength.

[0002]

2. Description of the Related Art Aluminum plates (including aluminum alloy plates) are used as aluminum supports for printing plates, especially as supports for offset printing plates. Generally, in order to use an aluminum plate as a support for an offset printing plate, it is necessary to have 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 uniform and fine grain. This roughening treatment has a significant influence on the printing performance and printing durability of the plate material when offset printing is actually carried out after plate making, and therefore its quality is an important factor in the plate material production.

An AC electrolytic etching method is generally adopted as a method for roughening the aluminum support for a printing plate, and an ordinary sine wave AC current or a special alternating waveform current such as a rectangular wave is used as a current. It is used. Roughening treatment of the aluminum plate is performed by alternating current using an appropriate electrode such as graphite as a counter electrode, which is usually performed in a single treatment, but the pit depth obtained there is generally shallow. The printing durability was inferior. Therefore, various methods have been proposed in order to obtain an aluminum plate suitable as a printing plate support having a grain in which pits having a depth deeper than its diameter are present uniformly and densely. As the method, a surface roughening method using a special electrolysis power source waveform (Japanese Patent Laid-Open No. 53-67507), a ratio of the amount of electricity at the time of anode and cathode at the time of electrolytic surface roughening using alternating current A54
-65607), power supply waveform (JP-A-55-253)
No. 81), combinations of energization amount per unit area (Japanese Patent Laid-Open No. 56-29699), and the like are known. Also, in combination with mechanical surface roughening (Japanese Patent Laid-Open No. 55-
Japanese Patent No. 142695) is also known.

On the other hand, as a method of manufacturing an aluminum support, an aluminum ingot is melted and held to form a slab (thickness 400 to 600 mm, width 1000 to 2000 m).
m, length 2000 to 6000 mm), and for removing the stress inside the slab and homogenizing the structure after a chamfering step of cutting the impurity structure part of the slab surface with a chamfering machine to cut it by 3 to 10 mm , 480-540 in soaking furnace
A soaking treatment step of maintaining the temperature at 6 ° C for 6 to 12 hours is performed, and then hot rolling is performed at 480 to 540 ° C. After hot rolling to a thickness of 5 to 40 mm, cold rolling is performed to a predetermined thickness at room temperature. Further, after that, annealing is performed to homogenize the structure to homogenize the rolled structure and the like, and then cold rolling is performed to a prescribed thickness to correct the plate so as to have a good flatness. The aluminum support thus prepared 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 influence of the aluminum support as a target,
When manufacturing the aluminum support through the process of melting and holding → casting → chamfering → soaking, heating and cooling are repeated,
Even if there is a step of scraping off the surface layer called surface grinding, variations in metal alloy components and the like occur in the surface layer, which causes a reduction in the yield as a lithographic printing plate.

On the other hand, the applicant of the present invention reduced the variation in the material of the aluminum support and improved the yield of the electrolytic surface roughening treatment to obtain a lithographic printing plate of excellent quality and good yield. As a method for producing, in a method for producing a lithographic printing plate support, which is obtained by continuously casting a molten aluminum melt into a plate directly by twin rolls, then cold rolling and heat treating, and then further roughening the straightened aluminum support. ,
Making a thin plate of 4 to 30 mm by the continuous casting and rolling,
After reducing the thickness to 0.3 mm to 3.0 mm by cold rolling, it is performed at 500 ° C. to 660 ° C. for 1 to 600 seconds, 260
We proposed a method for producing a lithographic printing plate support characterized by performing two types of intermediate annealing at 8 ° C to 300 ° C for 8 hours to 12 hours and reducing the thickness to 0.1 mm to 1.0 mm by finish rolling ( Japanese Patent Application No. 5-91908).

[0007]

However, in the manufacturing method proposed by the applicant of the present invention, recrystallized grains grow large in the batch furnace system in which the temperature rising rate is slow, and the mechanical strength is remarkably lowered. There was a problem.

An object of the present invention is to solve the conventional problems and to provide a method for producing a lithographic printing plate support which is capable of producing a lithographic printing plate having good electrolytic surface-roughening property, excellent mechanical strength and excellent appearance. To provide.

That is, the above-mentioned object of the present invention is a lithographic printing method in which an aluminum melt is directly cast and rolled into a plate shape by twin rolls, then cold-rolled and heat-treated, and the straightened aluminum support is roughened. In the method for manufacturing a plate support, 4 mm to 30 mm is obtained by the continuous casting and rolling.
0.3mm ~ 3.0m by cold rolling
After reducing the thickness to m, 500 ℃ by induction heating method
A method for producing a support for a lithographic printing plate, which comprises performing intermediate annealing twice at 660 ° C. for 1 second to 600 seconds and reducing the thickness to 0.1 mm to 1.0 mm by finish rolling. Achieved by

As a method for continuously casting and rolling a sheet of aluminum directly into a plate using the twin rolls of the present invention to form a coil of a thin plate, a thin plate continuous casting technique such as a Hunter method or a 3C method has been put into practical use. . In addition, JP-A-60-2380
No. 01, Japanese Patent Laid-Open No. 60-240360 and the like disclose a method of forming a thin plate coil. First, a thin plate of 4 mm to 30 mm is made by continuous casting and rolling.
Next, the thickness is 0.3 mm to 3.0 m by cold rolling.
m, and subsequently, as a heat treatment step, an intermediate heating is performed twice at 500 ° C. to 660 ° C. for 1 second to 600 seconds by an induction heating method, and finally, a cold rolling mill is reapplied for 0.1 second.
The thickness is reduced to mm to 1.0 mm, and then it is subjected to a straightening device to obtain a plate with good flatness.

The embodiment of the method for producing the aluminum support used in the present invention will be described more specifically with reference to the process conceptual diagram of FIG. In FIG. 1A, 1 is a melting and holding furnace, in which the ingot is held by melting. From here, it is sent to the twin roll continuous casting device 2. That is, it is wound by the coiler 3 which directly forms a hot rolled coil of a thin plate of 4 mm to 30 mm from the molten aluminum. Then, Figure 1
As shown in (B), put it on the cold rolling mill 4 and make it 0.3mm thick.
˜3.0 mm, followed by the heat treatment step 5 (induction heating annealing device) 5 of FIG. 1 (C), two intermediate anneals at 500 to 660 ° C. for 1 to 600 seconds, and then final Rolling is applied again to the cold rolling mill 4 shown in FIG. 1 (B) to reduce the thickness to 0.1.
mm to 1.0 mm. Then, it is applied to the correction device 6 shown in FIG. The plate material thus obtained is subjected to surface roughening treatment. The present invention is characterized in that induction heating is used twice in the heat treatment process of FIG.

The manufacturing conditions thereof will be described in more detail. In the melting and holding furnace 1, it is necessary to hold the temperature above the melting point of aluminum, and the temperature changes timely depending on the aluminum alloy component. Generally, it is 800 ° C or higher. Further, as a measure to suppress the generation of oxides in the molten aluminum and to remove the alkali metal that is harmful to the quality, an inert gas purge, a flux treatment, etc. are appropriately performed.

Subsequently, it is cast by the twin roll continuous casting device 2. There are various casting methods, but most of them currently operating industrially are the Hunter method and the 3C method. The casting temperature depends on the method and alloy, but 700 ℃
The vicinity is used. When the Hunter method or the 3C method is adopted, the molten metal can be solidified and rolled between twin rolls. About the plate material obtained at this stage,
Electron probe microanalysis (hereinafter EPMA
Observation), the element distribution is non-uniform both in the thickness direction and in the width direction, leading to the problem that the roughening of the final product is not uniform. Therefore, the cold-rolling machine 4 is used to make a continuously cast thin plate 0.3 mm to 3 m.
Rolling is performed so as to reduce the thickness to m. At this point, when the element distribution on the surface is observed by EPMA, the element distribution becomes nonuniform in the form stretched in the rolling direction, and when the crystal macrostructure on the surface is observed, the crystal is also elongated in the rolling direction. This leads to a problem that streaky unevenness and streak are deteriorated after the treatment. Therefore, the first intermediate annealing is performed at 500 to 600 ° C. for 1 second to 600 seconds by the induction heating method so that the element distribution becomes uniform, and 500 ° C. to 660 ° C. for 1 second to 600 seconds in order to make the crystal grain sizes uniform. Two
Perform the second intermediate annealing. After that, a thin plate having a thickness of 0.1 mm to 1.0 mm is produced by finish rolling, and is straightened by the straightening device 6. Further, cold rolling may be performed between the first and second intermediate annealings by the induction heating method.

Various methods such as mechanical surface roughening, chemical surface roughening, electrochemical surface roughening, and combinations thereof can be used as the method of surface roughening the lithographic printing plate support of the present invention. Mechanical graining methods include, for example, ball grain, wire grain, brush grain, and liquid honing method. Further, as an electrochemical graining method, an alternating current electrolytic etching method is generally adopted, and as an electric current,
Special alternating waveform currents such as ordinary sine wave alternating current or rectangular wave are used. Further, as a pretreatment for this electrochemical graining, etching treatment with caustic soda may be performed.

In the case of performing electrochemical surface roughening, it is preferable that the surface is roughened by an alternating current with an aqueous solution mainly containing hydrochloric acid or nitric acid. The details will be described below. 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. It is suitable that the concentration is 0.01 to 20%, the temperature is 20 to 90 ° C., and the time is 5 sec to 5 min. The preferable etching amount is 0.1 to 5 g /
m ² . Particularly in the case of a support containing a large amount of impurities, 0.01
-1 g / m ² is suitable. (JP-A-1-237197
Issue). Subsequently, an alkali-insoluble substance (smut) remains on the surface of the alkali-etched aluminum plate, and therefore a desmut treatment may be performed if necessary.

The pretreatment is as described above, but
In the present invention, AC electrolytic etching is performed in an electrolytic solution containing hydrochloric acid or nitric acid as a main component. The frequency of the alternating electrolysis current is 0.1 to 100 Hz, more preferably 0.1 to 100 Hz.
It is 1.0 or 10 to 60 Hz. The liquid concentration is 3
˜150 g / l, more preferably 5 to 50 g / l, and the amount of aluminum dissolved in the bath is preferably 50 g / l or less, and more preferably 2 to 20 g / l. If necessary, additives may be added, 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 preferred. Further, the power source waveform is appropriately selected depending on the desired quality and the components of the aluminum support to be used, but it is preferable to use the special alternating waveform described in Japanese Patent Publication Nos. 56-19280 and 55-19191. More preferable. Such waveforms and liquid conditions are appropriately selected depending on the quality required along with the quantity of electricity and the components of the aluminum support used.

The electrolytically grained aluminum is then immersed in an alkaline solution to dissolve the smut as part of the smut treatment. There are various alkaline agents such as caustic soda, but pH 10 or higher, temperature 25 to 60 ° C, immersion time 1
It is preferable to carry out in an extremely short time of 10 seconds. Next, it is dipped in a liquid containing mainly sulfuric acid. As the liquid condition of sulfuric acid, the concentration is 50-400 g / l, the temperature is 25-
65 ° C is preferred. If the concentration of sulfuric acid is 400 g / l or more, or if the temperature is 65 ° C. or more, corrosion of the processing tank and the like becomes large. Moreover, in an aluminum alloy containing 0.3% or more of manganese, the grain roughened electrochemically is broken. In addition, the dissolution amount of the aluminum substrate is 0.2 g / m
^If it is etched by ² or more, the printing durability will decrease, so it is preferably 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 5 g / m ² is formed on the surface. The treatment conditions for anodization are not generally determined because they vary depending on the electrolytic solution used, but generally the concentration of the electrolytic solution is 1 to 80% by weight, and the solution temperature is 5 to 7%.
0 ° C., current density 0.5-60 A / dm ² , voltage 1-100
V and an electrolysis time of 1 second to 5 minutes are suitable. The thus-obtained aluminum plate having an anodized film is itself stable and excellent in hydrophilicity, so that a photosensitive coating film can be immediately provided on the aluminum plate, but if necessary, the surface can be further improved. Can be processed.

For example, it is possible to provide a silicate layer made of the alkali metal silicate described above or an undercoat layer made of a hydrophilic polymer compound. The coating amount of the undercoat layer is preferably 5 to 150 mg / m ² .

Next, a photosensitive coating film is provided on the thus treated aluminum support, imagewise exposed and developed to form a plate, which is then set in a printing machine to start printing.

[0021]

【Example】

(Example-1 and Comparative Example-1) An aluminum plate having a plate thickness of 7.3 mm was formed by a continuous casting apparatus as shown in FIG. 1 (A), and cold-rolled to a plate thickness of 0.5 mm. Then, as Example-1, the intermediate annealing by the induction heating method is performed 5
It was performed twice at 00 ° C., and as a comparative example, intermediate annealing was performed twice at 500 ° C. for 10 minutes by a batch method, and then both were further cold rolled to 0.24 mm to form a test material.
The tensile strength of both test materials was 17.6 kg / in Example-1.
mm ² was shown, whereas the comparative example was 14.9 kg / mm ^2.
Met.

[0022]

Industrial Applicability The aluminum support for lithographic printing plates, which has excellent electrolytic surface roughening characteristics and excellent mechanical strength, is obtained by two intermediate annealings by the induction heating method in the method for producing a lithographic printing plate support of the present invention. I got a body.

[Brief description of drawings]

FIG. 1A is a side view of an embodiment of a twin roll continuous casting step, which is a partial step of the method for producing a lithographic printing plate support of the present invention, and a side view of an embodiment of a cold rolling step. (B),
Side view (C) of one embodiment of the heat treatment step, side view (D) of one embodiment of the straightening step

FIG. 2 is a side view of an embodiment of a conventional heat treatment process with a slow temperature rising rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melt-holding furnace 2 Twin roll continuous casting device 3 Coiler 4 Cold rolling mill 5 Induction heating annealing device (heat treatment process with fast heating rate) 6 Straightening device 7 Heat treatment process with slow heating rate

Claims (1)

[Claims] 1. A continuous casting and rolling process from an aluminum melt to a plate shape directly with twin rolls, followed by cold rolling and heat treatment,
In the method for producing a support for a lithographic printing plate, which further roughens an aluminum support that has been straightened, a thin plate of 4 to 30 mm is made by the continuous casting rolling, and a thickness of 0.3 mm to 3.0 mm is obtained by cold rolling. Is reduced, the intermediate annealing is performed twice at 500 ° C. to 660 ° C. for 1 second to 600 seconds by an induction heating method, and the thickness is reduced to 0.1 mm to 1.0 mm by finish rolling. A method for producing a support for a lithographic printing plate.