JPH11192537A - Manufacture of supporting body for lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the generation of streaks of picture which appear continuously or intermittently in the rolling direction of an aluminum plate at the time of manufacturing a supporting body for a lithographic printing plate. SOLUTION: Aluminum is melted and the molten metal is fed between a pair of cooling rolls from a molten metal feeding nozzle 3 wherein a release agent which contains aggregate particles of particle size distribution of 5 μm-20 μm in median diameter and 4 μm-12 μm in mode diameter is coated on the inner surface coming into contact with molten metal 2, and the molten aluminum is continuously poured and rolled into a aluminum plate. Thereafter, either of cold rolling or heat treatment or both of them are applied one time or more to make an aluminum thin plate of 0.1 mm-0.5 mm thickness, flatting is further applied to make the aluminum supporting body, and roughening is applied to manufacture the supporting body for the lithographic printing plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aluminum support for a lithographic printing plate using a twin-roll continuous casting method. In particular, the present invention relates to a method for producing an aluminum support for a lithographic printing plate having good surface quality by eliminating streak-like surface defects that occur continuously or intermittently in the rolling direction of an aluminum plate.

[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. In general, in order to use an aluminum plate as a support for an offset printing plate, it is necessary that the aluminum plate has an appropriate mounting property with respect 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. As the current, a special alternating waveform current such as a normal sine wave AC current or a rectangular wave is used. Used. The surface of the aluminum plate is roughened by alternating current using an appropriate electrode such as graphite as a counter electrode, and is usually performed in a single process, but the pit depth obtained there is generally shallow. And the printing durability was 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. Examples of the method include a surface roughening method using a special electrolytic power source waveform (Japanese Patent Application Laid-Open No. 53-67507), and a ratio of the amount of electricity between an anode and a cathode during electrolytic surface roughening using alternating current ( Showa 54
JP-A-65607), a power supply waveform (JP-A-55-253).
No. 81) and combinations of the amount of current per unit area (JP-A-56-29699). Further, in combination with mechanical roughening (Japanese Patent Laid-Open No. 55-14 / 55)
No. 2695) is also known.

On the other hand, as a method of manufacturing an aluminum support, a slab (thickness 400 to 600 mm, width 1000 to 2000 m) is melted and held in an aluminum ingot.
m, length 2000-6000 mm), and after passing through a face milling step of cutting the impurity structure portion of the slab surface by a face mill at a rate of 3 to 10 mm, 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, the structure is refined to homogenize the rolled structure and the like, and then cold-rolled to a specified thickness and straightened to obtain a plate having good flatness. The aluminum support thus produced was used as a support for a lithographic printing plate.

[0005] However, the electrolytic surface roughening treatment is particularly susceptible to the effect of the target aluminum support.
When manufacturing aluminum support through the process of melting and holding → casting → facing → soaking, repeat heating and cooling,
Even if there is a step of chamfering the surface layer, variations in metal alloy components and the like occur in the surface layer, causing a reduction in the yield of a lithographic printing plate.

[0006] On the other hand, the applicant of the present invention has reduced the dispersion of the material of the aluminum support and improved the yield of the electrolytic surface roughening treatment, thereby producing a lithographic printing plate of excellent quality and a good yield. As a method that can be made, continuous casting and hot rolling from molten aluminum to form a hot-rolled coil of a thin plate, and then roughening the aluminum support that has been cold-rolled, heat-treated, and straightened. A method for producing a lithographic printing plate support characterized by the following was proposed. (Japanese Patent Laid-Open No. 3-7
No. 9798) In addition, when the present applicant previously performed continuous casting and rolling into a plate shape directly from a molten aluminum with twin rolls, and then subjected to cold rolling, heat treatment, and straightening, the aluminum support was roughened. A method for defining the temperature difference at the tip of the molten metal supply nozzle (JP-A-6-262308) and a method for defining the casting start temperature (JP-A-7-40017) have been proposed.

[0007] Further, it is generally known that when continuous casting and rolling is performed from an aluminum melt directly into a plate shape using twin rolls, a liquid containing graphite is sprayed onto a pair of cooling rolls (double rolls). I have. (Light
Metal Age Magazine, 1975 October, p. 19) Further, regarding a molten metal supply nozzle used for continuous casting and rolling directly from a molten aluminum into a plate shape using twin rolls, for example, Light Metal Age Magazine, 1975 O
The outline shape is described on page 6 of Ctober No., and further detailed shapes are described in JP-B-52-23327, JP-A-2-290652, JP-A-1-215441,
JP-A-62-248543, JP-A-61-1456
No., UK Patent GB2198976, U.S. Pat.
S4716956 and Canadian patent CA614991 are known as known patents.

[0008]

However, even if the above-mentioned various proposed methods and the previously proposed manufacturing method of the present applicant are used, they appear continuously or intermittently in the rolling direction of the aluminum plate. A streak-like surface quality defect may occur. That is, the flow of the molten metal in the molten metal nozzle changes due to the difference in the particle size distribution of the release agent applied in the molten metal supply nozzle, and the molten metal does not flow uniformly and stably. For this reason, the portion where the flow is disturbed becomes a stripe-like surface quality defect, and there is a problem that the production yield is reduced. An object of the present invention is to provide a method and an apparatus for producing a lithographic printing plate support having an excellent production yield by suppressing the occurrence of streak-like surface defects that appear continuously or intermittently in the rolling direction of an aluminum plate. Is to provide.

[0009]

Means for Solving the Problems The present inventors have intensively studied the relationship between the non-uniform state generated during casting using a twin roll continuous casting apparatus and the surface quality defect of an aluminum support for a lithographic printing plate. As a result, the present invention has been found. That is, the object of the present invention is to provide a molten metal supply nozzle in which aluminum is melted and a release agent containing aggregate particles having a median diameter of 5 μm or more and a mode diameter of 4 μm to 12 μm is applied to the inner surface in contact with the molten metal. After supplying a molten aluminum between a pair of chill rolls and continuously casting and rolling plate-shaped aluminum, cold rolling, heat treatment or one or both of the heat treatments are performed once or more to a thickness of 0.1 mm to 0.5 mm. This is achieved by a method of manufacturing a lithographic printing plate support in which an aluminum thin plate is formed and further straightened to form an aluminum support, which is roughened.

According to the method of the present invention, a median diameter of 5 μm to 20 μm and a mode diameter of 4 μm to
With a configuration in which a mold release agent containing aggregate particles is applied with a particle size distribution of 12 μm, an aluminum melt is supplied from this melt supply nozzle to finally produce an aluminum thin plate having a thickness of 0.1 mm to 0.5 mm, Even if there is contact between the cooling roll and the molten metal supply nozzle, the action of the release agent containing the aggregate particles as described above stabilizes the flow of the molten metal in the molten metal supply nozzle uniformly, so that a streak-like surface is formed. It prevents quality defects. With the above-described configuration, a strip-like surface quality defect that appears continuously or intermittently in the rolling direction can be eliminated, and a lithographic printing plate support having a good surface quality can be efficiently manufactured.

In the present invention, boron nitride (BN) or the like is used as a release agent, and water or an organic solvent is used as an aggregate contained in the release agent. In addition, as a method of forming a thin coil by casting directly from an aluminum melt into a plate shape using a twin roll, a hunter method, 3C
Thin plate continuous casting technology such as the method has been put to practical use.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the method for manufacturing an aluminum support according to the present invention will be described more specifically with reference to the drawings. FIG. 1 is a schematic view showing steps of a method for manufacturing an aluminum support according to the present invention. As shown in FIG. 1, molten aluminum is sent to a gutter 2 by tilting a melting and holding furnace 1. And the liquid level of the gutter 2 is
By controlling the motor 9 for tilting the melting furnace through the amplifier 8 and being detected by the liquid level sensor 7, the supply amount of the molten metal is controlled to maintain the liquid level of the gutter 2 constant. In addition, if necessary, the crystal grain refinement wire 10 is supplied to the molten metal. As a measure for suppressing the generation of oxides in the molten aluminum and removing alkali metals that are harmful to quality, an inert gas purge, a flux treatment, and the like are appropriately performed. The molten metal is supplied to a pair of cooling rolls from a molten metal supply nozzle 3 applied to an inner surface of a molten metal having a median diameter of 5 μm to 20 μm and a modal diameter of 4 μm to 12 μm in a particle size distribution including aggregate particles in contact with the molten metal. 4
The steel sheet is supplied to the gaps a and 4b, solidified, cooled, and rolled to produce a cast plate. Cooling rolls 4a, 4b
Can be taken up by, for example, the coiler 6 or can be appropriately sampled by the cutter 5.

The sheet material thus obtained is rolled to a specified thickness by the cold rolling mill 11 shown in FIG. At this time, in order to make the size of the crystal grains uniform, a heat treatment step such as intermediate sintering may be performed, and further, a cold rolling mill 11 may be inserted. Next, straightening is performed by a straightening device, a predetermined flatness is given, an aluminum support is formed, and the aluminum support is roughened. The straightening may be performed in the last cold rolling.

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 surface roughening method of the lithographic printing plate support. Examples of the mechanical graining method include a ball grain, a wire grain, a brush grain, and a liquid honing method. As an electrochemical graining method, an AC electrolytic etching method is generally adopted, and a special alternating current such as a normal sine wave AC current or a rectangular wave is used as a current. In addition, as a pretreatment for the electrochemical graining, an etching treatment with caustic soda may be performed.

In the case of performing electrochemical surface roughening, the surface is preferably roughened by an alternating current with an aqueous solution mainly composed of hydrochloric acid or nitric acid. This will be described in detail below. First, the aluminum support is first alkali etched. Preferred alkaline agents are sodium hydroxide, potassium hydroxide, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate and the like. It is appropriate that the concentration is selected from the range of 0.01 to 20%, the temperature is 20 to 90 ° C., and the time is 5 sec to 5 min.
m ² .

Particularly, in the case of a support having a large amount of impurities, 0.01
１1 g / m ² is appropriate. (JP-A-1-237197)
No.). Subsequently, since a substance (smut) insoluble in alkali remains on the surface of the alkali-etched aluminum plate, desmutting may be performed as necessary. In any case, when there is a streak-like surface defect that occurs continuously or intermittently in the rolling direction of the aluminum plate, it appears as a streak-like surface defect when the etching treatment is performed with the above-described caustic soda.

The pre-processing is as described above.
According to the present invention, alternating current electrolytic etching is performed in an electrolytic solution mainly containing hydrochloric acid or nitric acid. The frequency of the AC electrolytic current is 0.1 to 100 Hz, more preferably 0.1 to 100 Hz.
1.0 or 10 to 60 Hz. The liquid concentration is 3
To 150 g / liter, more preferably 5 to 50 g / liter, and the amount of aluminum dissolved in the bath is 50 g / liter.
1 liter or less is appropriate, more preferably 2 to 20 g
/ Liter. Additives may be added if necessary, but in the case of mass production, it becomes difficult to control the liquid concentration. Also, current density, 5~100A / dm ² but is appropriate, 10~80A / dm ² is more preferable. Also,
The power supply waveform is appropriately selected 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-A-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.

The aluminum which has been electrolytically roughened is then immersed in an alkaline solution as a part of the smut treatment to dissolve the smut. As the alkaline agent, there are various kinds such as caustic soda, and the pH is 10 or more, the temperature is 25 to 60 ° C., and the immersion time is 1
It is preferable to carry out in a very short time of 10 to 10 sec.

Next, it is immersed in a liquid mainly composed of sulfuric acid. As the liquid condition of sulfuric acid, the concentration is 50 to 400 g /
Liters and temperatures between 25 and 65 ° C are preferred. When the concentration of sulfuric acid is 400 g / liter or more, or the temperature is 65 ° C. or more, the corrosion of the treatment tank and the like increases, and in the case of aluminum alloy containing manganese of 0.3% or more, the sand which is electrochemically roughened is used. My eyes collapse. Also, when the etching rate is 0.2 / m ² or more of the dissolved amount of the aluminum base,
Since the printing durability is reduced, it is preferable to set the content to 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. Anodizing treatment conditions vary depending on the electrolytic solution to be used, and thus cannot be unconditionally determined. In general, the concentration of the electrolytic solution is 1 to 80% by weight, the liquid temperature is 5 to 70 ° C,
Current density 0.5-60 A / dm ² , voltage 1-100V,
An electrolysis time of 1 second to 5 minutes is appropriate.

The grained aluminum plate having the anodic oxide film thus obtained is stable and excellent in hydrophilicity, so that a photosensitive coating film can be immediately provided on the aluminum plate. Can further apply a surface treatment.
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 5 to 150 m
g / m ² is preferred. Next, a photosensitive coating film is provided on the aluminum support treated in this way, and after image exposure, development and plate making, it is set in a printing machine and printing is started.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic steps of this embodiment in the casting step of the method for manufacturing an aluminum support for a lithographic printing plate according to the steps of the method for manufacturing an aluminum support in FIG. 1 will be described below. First, the melting temperature of the aluminum
At 790 ° C. When the molten metal is poured, Al—Ti
A (5%)-B (1%) alloy wire is supplied as a refining agent and is melted in a molten metal.

Then, the molten metal is supplied to a molten metal supply nozzle 3 in which a release agent containing aggregate particles is applied to an inner surface of the molten metal in contact with the molten metal.
Is supplied to a gap between a pair of cooling rolls 4a and 4b, and is continuously cast and rolled into a plate having a thickness of 7.0 mm and a width of 200 mm while being solidified and cooled. Further, a cold rolling mill 11 shown in FIG.
5 mm, and then the batch annealing apparatus 12 shown in FIG.
480 ° C. × 10 (hours), and the cold rolling mill 11 finishes the heat treatment to a thickness of 0.24 mm.

The following experiment was performed as the state of the release agent containing aggregate particles applied to the inner surface of the melt supply nozzle 3 in contact with the melt. [Comparative Example 1] The melt supply nozzle 3 was not coated with a release agent. [Comparative Example 2] A median diameter of 1.5 was supplied to the molten metal supply nozzle 3.
One coated with a release agent having a particle size distribution of 1.5 μm and a mode diameter of 1.5 μm. [Embodiment-1] The molten metal supply nozzle 3 was provided with a median diameter of 6.5.
One coated with a release agent having a size of 10 μm and a particle size distribution of 10 μm. [Comparative Example 3] A median diameter of 15 µ
m, coated with a release agent exhibiting a particle size distribution having a mode diameter of 20 μm. [Comparative Example 4] A molten metal supply nozzle 3 was provided with a median diameter of 24 µm.
m, coated with a release agent exhibiting a particle size distribution having a mode diameter of 10 μm.

The sample thus prepared was etched with a 15% aqueous solution of caustic soda at a liquid temperature of 60 ° C. so that the etching amount was 5 g / m ^2, and the generation of crystal streaks was confirmed. For streaks, EP
The composition analysis of the crystal streak portion was performed by MA, and the presence or absence of segregation of Fe and Si, which is a characteristic of the streak portion, was confirmed. The results are shown in Table 1 below.

[0026]

[Table 1]

[0027]

As described above, according to the method for producing a lithographic printing plate support of the present invention, streak-like surface defects (crystal streaks) that occur continuously or intermittently in the rolling direction of an aluminum plate. Can be eliminated to produce an aluminum support for a lithographic printing plate having good surface quality.

[Brief description of the drawings]

FIG. 1 is a schematic view showing steps of a method for producing a lithographic printing plate support according to the present invention.

FIG. 2 is a schematic diagram of a cold rolling mill used in the present invention.

FIG. 3 is a schematic view of a batch annealing apparatus used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting and holding furnace 2 Molten metal 3 Molten supply nozzle 4 Twin roll continuous casting machine 5 Cutter 6 Coiler 7 Molten metal level meter 8 Amplifier 9 Melting and holding furnace tilting motor 10 Fine agent wire 11 Cold rolling mill 12 Batch annealing device 16 Fine agent Wire feeder P Continuous cast plate

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C22F 1/04 C22F 1/04 A // C22F 1/00 623 1/00 623 674 674

Claims (1)

[Claims] 1. An aluminum alloy having a median diameter of 5
An aluminum melt is supplied between a pair of cooling rolls from a melt supply nozzle in which a release agent containing aggregate particles having a particle size distribution of 4 μm to 12 μm with a mode diameter of 4 μm to 12 μm is applied to a pair of cooling rolls. After continuous casting and rolling of aluminum, cold rolling, one or both of heat treatments are performed one or more times to produce an aluminum thin plate having a thickness of 0.1 mm to 0.5 mm, which is further straightened to form an aluminum support. A method for producing a lithographic printing plate support, wherein the support is roughened.