JPH06218495A - Manufacture of supporting body for planographic printing plate - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for supporting body, in which the unevenness of material of the aluminum supporting body is reduced and the yield of the electrolytic roughening surface treatment is improved and a planographic printing plate having excellent surface quality can be manufactured. CONSTITUTION:The molten aluminum is supplied into a twin roll continuous caster 2 from a melting and holding furnace 1 to form a strip, and the strip is wound with a coiler 6 and successively, applied to a heat treatment device, cold rolling mill and straightening device. At the time of rolling to the prescribed thickness by passing the cast steel through the cold rolling mill 3, in order to arrange the size of crystal grain, the intermediate annealing, etc., is executed by a heat treatment furnace 4. Successively, the straightening is executed with the straightening device 5 to give a prescribed flatness and this surface is roughened. Factors which give the effect to the size of crystal grain on the surface are cooling velocity, casting velocity, variation of the strip thickness during casting, rolling reduction rate of the cold rolling and the temp. of annealing process. The size of the crystal grain is made to be 2-500mum after casting and 2-100mum in the finish condition in the vertical cross section to the casting and rolling direction.

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 lithographic printing plate support, and more particularly to a method for producing an aluminum support having a good electrolytic graining property.

[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 alternating current electrolytic etching method is generally adopted as a roughening method for an aluminum support for a printing plate, and an ordinary sinusoidal alternating current or a special alternating waveform current such as a rectangular wave is used as a current. . 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 a method thereof, a surface roughening method using a special electrolytic power source waveform (Japanese Patent Laid-Open No. 53-67507), a ratio of an electric quantity at the time of an anode and a cathode at the time of electrolytic surface roughening using an alternating current A54
-65607), power supply waveform (JP-A-55-253)
No. 81), a combination of energization amount per unit area (Japanese Patent Laid-Open No. 56-29699) and the like are known.

Further, a method combined with mechanical surface roughening (Japanese Patent Laid-Open No. 55-142695) 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: 4 mm).
00-600mm, width 1000-2000mm, length 2
000 to 6000 mm) and subjected to a chamfering step of cutting the impurity textured portion of the slab surface with a chamfering machine in 3 to 10 mm increments, and then in a soaking furnace for removing stress inside the slab and homogenizing the texture. A soaking treatment step of holding at 480 to 540 ° 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, in order to make the plate uniform and to have a good flatness, annealing is performed to make the rolled structure and the like uniform, and then cold rolling is performed to a prescribed thickness for straightening. The aluminum support thus prepared was used as a support for a lithographic printing plate.

On the other hand, the present applicant has previously made a planographic printing plate excellent in quality by reducing variations in the material of the aluminum support and improving the rate of electrolytic surface roughening treatment. As a method of making, an aluminum support which is cast from an aluminum melt and hot-rolled continuously to form a hot-rolled coil of a thin plate, then cold-rolled, heat-treated, and further straightened is used. It proposes a method for producing a support for a lithographic printing plate, which is characterized by: (JP-A-3-79798)

[0005]

However, also in the manufacturing method of the present applicant previously proposed, the size of the aluminum crystal grains on the surface of the aluminum plate after final cold rolling or heat treatment is It was found that it had a great influence on the quality of the surface. Further, it has been found that, among the trace alloy components, it is particularly important for Fe to form a solid solution in a certain amount or more in order to carry out uniform roughening.

An object of the present invention is to reduce variations in the material of the aluminum support, improve the yield of the electrolytic surface roughening treatment, and to obtain a high-quality lithographic printing plate having excellent surface quality after roughening. An object of the present invention is to provide a method for producing a lithographic printing plate support capable of making a plate.

[0007]

Means and Actions for Solving the Problems The present inventors have
The present invention has been found as a result of intensive research on the relationship between the aluminum support and the electrolytic surface roughening treatment. That is, the above-mentioned object of the present invention is a lithographic plate which is obtained by directly casting a molten aluminum melt into a plate directly by twin rolls, and then performing cold rolling and heat treatment one or more times each, and further straightening the aluminum support for roughening. In the method for producing a printing plate support, F
e content of 0.4% to 0.2%, Si content of 0.
20% to 0.05%, Cu content of 0.02% or less,
Al purity is 99.5% or more, the crystal grain size of the aluminum plate after continuous casting is 2 μm to 500 μm in a cross section perpendicular to the casting progress direction, and the aluminum plate after the final cold rolling or annealing is A method for producing a lithographic printing plate support, wherein the crystal grain size is 2 μm to 100 μm in a cross section perpendicular to the casting and rolling direction, and more preferably, the solid solution amount of Fe is 10 ppm or more, This is achieved by the method for producing a lithographic printing plate support described above.

As a method of forming a coil continuously cast from the molten aluminum of the present invention by using twin rolls, a thin plate continuous casting technique such as Hunter method or 3C method has been put into practical use. The present invention, when continuously cast from the molten aluminum with twin rolls, by keeping the crystal grain size within a certain range,
It is possible to keep the distribution of alloy components that tend to collect at the grain boundaries within a certain range. Furthermore, by deforming the grain boundaries and diffusing the alloy components in the rolling and annealing processes after continuous casting, it is possible to make the distribution of alloy components in the final aluminum plate uniform, but Since it cannot be completely eliminated, the crystal grain size of the final aluminum plate is kept within a certain range. By these methods, it is possible to produce a lithographic printing plate support of excellent quality having a uniform surface during roughening at low cost and with good efficiency. The embodiment of the method for producing an aluminum support used in the present invention will be described more specifically with reference to the process conceptual diagram of FIG.
Reference numeral 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 machine 2. That is, it may be wound by the coiler 7, which directly forms a thin plate coil from the molten aluminum, or may be subsequently subjected to heat treatment, a cold rolling mill, and a straightening device.

The manufacturing conditions thereof will be described in more detail. In the melting and holding furnace 1, it is necessary to hold the temperature at the melting point of aluminum or higher, and the temperature changes timely depending on the aluminum alloy component. Generally, it is 800 ° C or higher. Further, as measures for suppressing the generation of oxides in the molten aluminum and removing the alkali metal which 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 machine 2. Although there are various casting methods, most of them currently operating industrially include the Hunter method and the 3-C method. The casting temperature varies depending on the cooling conditions of the mold, but the optimum temperature is around 700 ° C. The crystal grain size after continuous casting, the cooling conditions, the casting speed, and the amount of change in plate thickness during casting are controlled, and the plate material thus obtained by continuous casting is rolled to a specified thickness by the cold rolling mill 3. . At that time, in order to align the crystal grains to a predetermined size, the grain may be subjected to a heat treatment machine 4 such as an intermediate annealing, and then a cold rolling machine 3 may be inserted and sandwiched. Next, straightening is performed by the straightening device 5 to give a predetermined flatness, and an aluminum support is prepared and roughened. Further, straightening may be included in the final cold rolling. At this time, the size of the aluminum crystal grains is 2 to 500 μm after continuous casting in a cross section perpendicular to the direction of casting and rolling, and 2 in the final state.
˜100 μm.

Various methods such as mechanical surface roughening, chemical surface roughening, electrochemical surface roughening, and combinations thereof may 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. An alternating current electrolytic etching method is generally adopted as the electrochemical graining method, and a special alternating current such as an ordinary sinusoidal alternating current or a rectangular wave is used as the current. Further, as a pretreatment for this electrochemical graining, etching treatment with caustic soda may be performed. Further, 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. A detailed description will be given 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 . Especially in the case of a support with a large amount of impurities, 0.01
Appropriately 1 g / m ² (applicant filed on November 25, 1987 by the present applicant). Subsequently, a substance insoluble in alkali (smut) is applied to the surface of the aluminum plate that has been alkali-etched.
Remains, so desmutting treatment may be performed if necessary.

The pretreatment is as described above, but
AC electrolytic etching is performed in an electrolytic solution containing mainly hydrochloric acid or nitric acid. The frequency of the alternating electrolysis current is 0.1
-100 Hz, more preferably 0.1-1.0 or 10
-60 Hz. The liquid concentration is 3 to 150 g /
1, 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 preferable. The power source waveform is properly selected according to the desired quality and the components of the aluminum support used, but the Japanese Patent Publication Nos. 56-19280 and 55-1919.
It is more preferable to use the special alternating waveform described in each publication of No. 1. Such waveforms and liquid conditions are appropriately selected depending on the quality required along with the quantity of electricity, the components of the aluminum support used, and the like. The electrolytically grained aluminum is then immersed in an alkaline solution as part of the smut treatment to dissolve the smut. As the alkaline agent, there are various kinds such as caustic soda, but it is preferable that the pH is 10 or more and the temperature is 25 to 60 ° C. and the immersion time is 1 to 10 seconds, which is an extremely short time.
Next, it is dipped in a liquid containing mainly sulfuric acid. As the liquid condition of sulfuric acid,
50-400g / l, temperature 25
~ 65 ° C is preferred. Sulfuric acid concentration of 400g / l or more,
Alternatively, when the temperature is set to 65 ° C. or higher, corrosion of the treated layer and the like becomes large, and in an aluminum alloy containing 0.3% or more of manganese, electrochemically roughened grain is broken. In addition, the dissolution amount of aluminum base is 0.2 g /
If it is etched by m ² or more, the printing durability will decrease, so it is preferably 0.2 g / m ² or less. The anodized film has a thickness of 0.1 to 10 g / m ² , and more preferably a density of 0.1.
It is preferable to form ³ to 5 g / m ² on the surface. The treatment conditions for anodic oxidation 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, the liquid temperature is 5 to 70 ° C., and the current density is 0.5 ~
60 A / cm ² , voltage 1 to 100 V, electrolysis time 1 second to 5
A range of minutes is suitable.

The thus-obtained grained aluminum plate having an anodized film is itself stable and excellent in hydrophilicity, so that a photosensitive coating film can be immediately provided on it, but it is necessary. Can be further surface treated. For example, a silicate layer formed by the alkali metal silicate circle described above or an undercoat layer made of a hydrophilic polymer compound can be provided. The coating amount of the undercoat layer is 5 to 150 mg
/ M ² is preferred. 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.

[0013]

EXAMPLE An aluminum plate material having a thickness of 6 mm was formed by a continuous casting thin plate apparatus as shown in FIG.
According to JIS105, cold rolling is performed to a sheet thickness of m, annealing is performed at 400 ° C., and then cold rolling (including straightening) is performed to 0.3 mm.
0 material was formed. At this time, the aluminum material having the composition shown in Table 1, casting conditions, rolling and annealing conditions were appropriately changed, and the combination of particle diameters after continuous casting and in the final state was
It was created as an example and a comparative example of the present invention. A cross-section (see FIG. 2) perpendicular to the casting and rolling direction of this plate material is processed into a mirror surface with a buff and etched in a 10% hydrofluoric acid solution,
Observation and measurement of the crystal grain size of the surface were performed using a polarization microscope. Further, the amount of Fe in solid solution was measured by extracting Fe existing as an intermetallic compound from the aluminum plate material in the final state.

[0014]

[Table 1]

The thus-prepared aluminum plate was used as a support for a lithographic printing plate, and then etched with a 5% aqueous solution of caustic soda at a temperature of 60 ° C. to an etching amount of 5 g / m ² , washed with water and then washed with 150 g. It was immersed in a sulfuric acid solution of 1 / l, 50 ° C. for 20 seconds to desmut, and washed with water. Furthermore, the support was placed in a 16 g / l nitric acid aqueous solution,
Electrochemical roughening was performed using the alternating waveform current described in Japanese Patent No. 9191. As the electrolysis condition, the anode voltage V
_A = 14V and cathode voltage V _C = 12V were set, and the amount of electricity at the anode was set to 350 coulomb / dm ² . A photosensitive lithographic printing plate is obtained by applying a photosensitive solution to the substrate prepared as described above. Here, the surface quality of the substrate before applying the photosensitive solution was evaluated. The photosensitive lithographic printing plate is exposed through a negative film or a positive film and then developed, so that the surface itself of the substrate (a part of the photosensitive layer is removed) becomes a non-image part or an image part of the lithographic printing plate.
This is because the surface quality of the substrate surface itself greatly affects the printability and the visibility of the printing plate. The evaluation results of the samples shown in Table 1 before coating the photosensitive layer are shown in Table 2.

[0016]

[Table 2]

As shown in the above table, sample N not according to the invention
o. In Nos. 5 to 11, streak-like unevenness was generated and the quality was poor. Similarly, No. 2 with a small solid solution amount of Fe. 12, N
o. No. 13 had a non-uniform grain shape. Further, the stripe-shaped unevenness is caused because the crystal grain size is non-uniform, and the alloy components that are easily broken out at the grain boundaries cannot be sufficiently homogenized in the steps of rolling and annealing. Also. The uneven grain shape is due to the small amount of Fe dissolved in the matrix. On the other hand, the sample No. Nos. 1 to 4 were excellent in that no streak-like unevenness was generated and the grain shape was uniform.

[0018]

INDUSTRIAL APPLICABILITY As described above, the lithographic printing plate produced by the method for producing a lithographic printing plate support according to the present invention has less variation in the material of the aluminum support than the conventional lithographic printing plate, and electrolytic roughening. In addition to improving the yield of the surface-roughening treatment, the surface quality after roughening is remarkably improved, and there is no unevenness of the plate surface and the grain is uniform and excellent. Further, the ratio of the manufacturing process of the aluminum support is rationalized, and the effect of reducing the raw material cost is great, and in particular, it greatly contributes to the quality improvement and the cost reduction of the lithographic printing plate support.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an example of a part of the steps of the method for producing an aluminum support used in the present invention.

[Fig. 2] Conceptual diagram for observing crystal grain size from cross section after continuous casting 1 Melt-holding furnace 2 Twin roll continuous casting machine 3 Cold rolling machine 4 Heat treatment machine 5 Straightening device 6 Coiler 8 Aluminum plate obtained by continuous casting 8a Cross section perpendicular to casting direction 9 Crystal grain 9a Crystal grain boundary 9b Intragrain D Crystal grain size

Claims (2)

[Claims] 1. A support for a lithographic printing plate, which comprises continuously casting a molten aluminum directly into a plate shape with twin rolls, and then performing cold rolling and heat treatment one or more times each and further straightening to roughen the aluminum support. In the manufacturing method of, the Fe content is 0.4% to 0.2%, and the Si content is 0.20%.
˜0.05%, Cu content 0.02% or less, Al purity 99.5% or more, and the crystal grain size of the aluminum plate after continuous casting is 2 μm to 500 in a cross section perpendicular to the casting progress direction.
and a final grain size of the aluminum plate after cold rolling or annealing is 2 μm to 100 μm in a cross section perpendicular to the casting and rolling direction. Manufacturing method. 2. A support for a lithographic printing plate, which is obtained by continuously casting a molten aluminum directly into a plate shape with twin rolls, and then performing cold rolling and heat treatment one or more times each and further straightening the surface to roughen the aluminum support. In the manufacturing method of, the Fe content is 0.4% to 0.2%, and the Si content is 0.20%.
.About.0.05%, Cu content 0.02% or less, Al purity 99.5% or more, Fe solid solution amount 10 ppm or more,
The grain size of the aluminum plate after continuous casting is 2 μm to 500 μm in the cross section perpendicular to the casting progress direction, and the grain size of the aluminum plate after the final cold rolling or annealing is
A method for producing a support for a lithographic printing plate, wherein the cross section perpendicular to the casting and rolling direction is 2 μm to 100 μm.