JPH07224339A - Aluminum alloy plate stock for electrolytically roughened planographic printing plate and its production - Google Patents

Abstract

PURPOSE:To improve the uniformity of the electrolytical roughening of an aluminum alloy plate stock for an electrolytically roughened planographic printing plate and the uniformity in the appearance of the roughened face. CONSTITUTION:This is an aluminum alloy cold rolled sheet by continuous casting and rolling, and it has a compsn. cong., by weight, 0.20 to 0.80% Fe, and the balance aluminum and crystalline grain refining elements with inevitable impurity elements. Among the impurity elements, the content of Si is regulated to <=0.3% and Cu to <=0.05%, and as for the crystalline grains in the surface layer part, the width of the direction parallel to the plate face and vertical to the cold rolling direction is regulated to <=150mum, and the length in the direction parallel to the cold rolling direction is regulated to <=8 times the same width. For obtaining the crystalline grains like the same, heat treatment is executed in the process of cold rolling to recrystallize the grains. This heat treatment is executed preferably by rapid heating so as to prevent the coarsening of the recrystallized grains.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent electrolytic surface roughening properties,
In particular, the present invention relates to an electrolytically roughened aluminum alloy base plate for a lithographic printing plate having a uniform surface appearance and a method for producing the same.

[0002]

2. Description of the Related Art As an aluminum alloy base plate used for a support for electrolytic surface-roughened lithographic printing plate, JI is generally used.
A cold rolled sheet made of S A1050, A1100, A3003 or the like and having a sheet thickness of about 0.1 to 0.5 mm is used.
In general, such an aluminum alloy cold-rolled sheet is generally heated to a predetermined temperature after the surface of the ingot obtained by semi-continuous casting (DC casting) is removed by grinding and, if necessary, homogenized. It is manufactured by heating and hot rolling, performing intermediate annealing during the subsequent cold rolling, and then performing final cold rolling.

Further, Japanese Patent Laid-Open No. 3-79798 discloses that
Disclosed is a method of obtaining an aluminum alloy support for electrolytically roughened lithographic printing plates by forming strip coils from molten aluminum alloy by continuous casting and rolling, followed by cold rolling, heat treatment, straightening and the like.

Further, in Japanese Patent Application Laid-Open No. 5-156414, twin roll continuous casting rolling is performed, and hot rolling is performed to obtain a thickness of 4 to 30.
After making a coil with a strip of 1 mm, the thickness during cold rolling is 1 m
In the stage of m, heat treatment is performed at 400 ° C. or higher, and further cold rolling is performed to obtain an aluminum alloy support for electrolytic surface roughening lithographic printing, and twin roll continuous casting and rolling are performed to obtain a thickness of 4 to 4 by hot rolling. After making a coil of 30mm strip, 3
A method for obtaining an aluminum alloy support for electrolytically roughened lithographic printing plates is disclosed in which heat treatment is performed at 00 ° C. or higher and further heat treatment is performed at 300 ° C. or higher during cold rolling.

[0005]

The conventional general method described above has a drawback that the manufacturing process is complicated, requires a long processing step, and inevitably increases the manufacturing cost.

In the above-mentioned conventional general method, in order to improve the electrolytic surface roughening property and to make the roughened surface have a uniform appearance, casting, homogenizing heat treatment, hot rolling, and intermediate annealing during cold rolling are performed. It is necessary to control the conditions for each step. Further, in particular, in order to make the appearance of the roughened surface uniform, it is necessary to control the crystal grains in each step of casting, homogenizing heat treatment, hot rolling, and intermediate annealing during cold rolling.

Moreover, in order to produce an aluminum alloy base plate having a required thickness from an ingot obtained by semi-continuous casting (DC casting), high temperature and long time steps such as homogenizing heat treatment and hot rolling are essential. is there. Even if each of the above-mentioned steps is controlled, an element which is a supersaturated solid solution during casting is precipitated during this high-temperature and long-time step, and coarse recrystallized grains are easily generated during hot rolling. Even if small recrystallized grains can be generated by subsequent heat treatment or processing, the outline of coarse recrystallized grains generated during hot rolling remains, and this appears as streaks (streak-like unevenness) extending in the rolling direction. This causes deterioration of the appearance uniformity of the electrolytically roughened surface.

On the other hand, when the methods disclosed in the above-mentioned JP-A-3-79798 and JP-A-5-156414 and the heat treatment conditions during cold rolling are not appropriate, the electrolytic graining is uniform. However, there was a drawback that the roughened surface had a non-uniform appearance.

Generally, when electrolytically roughening an aluminum alloy base plate for a printing plate, as a pretreatment, chemical etching with an acid or an alkali is performed as a pretreatment to degrease the surface of the base plate or to remove an oxide film. To do. The electrolytic surface roughening treatment itself is a treatment for forming a pit on the surface of the raw plate to roughen the surface by applying an alternating current with graphite or the like as a counter electrode and performing electrolytic etching.

This roughening imparts the adhesiveness and water retention of the photosensitive film relating to the printing performance. Since it is necessary to obtain uniform adhesion and water retention over the entire printing plate, the pits also need to be formed uniformly over the entire printing plate. In addition, since the printing plate provided with the photosensitive film visually judges whether the development is good or not after exposure and development, it is also necessary that the roughened surface has a visually uniform appearance.

When the electrolytic surface roughening is not uniform, it means that an appropriate surface roughness cannot be obtained due to over-etching (dissolution type) in electrolytic etching or the presence of an unetched region. In this case, the adhesion of the photosensitive film is poor, the water retention and corrosion resistance of the non-image area are poor, and this causes stains on the non-image area during printing.

[0012] The uneven appearance of the roughened surface means that streaks (streak patterns) along the rolling direction are observed, or that the gloss is partially lost and looks cloudy. Say This is due to non-uniformity of chemical etching as a pretreatment and electrolytic etching as an electrolytic surface-roughening treatment (uneven etching, presence of an unetched region,
Overetching) and non-uniformity of the metal structure.

The non-uniformity of the metal structure is caused by the non-uniformity of the crystal orientation and the crystal grain size, the coarsening and the non-uniform dispersion of the intermetallic compound, which is caused by the electrolytic surface roughening (pretreatment also required for the printability). Even if it does not impair the uniformity of (including), the appearance of the roughened surface may be significantly uneven.

If the appearance of the roughened surface is non-uniform and cloud-like color unevenness occurs, it is very inconvenient for the inspection of the image area after development. That is, although this cloud-like portion remains in the non-image portion after development, it is similar to the color tone of the image portion, so it is difficult to visually determine whether or not the image portion has been sufficiently developed. become.

Therefore, one of the objects of the present invention is to provide an aluminum alloy base plate for electrolytic surface-roughening lithographic printing plate by continuous casting and rolling, which has the uniformity of electrolytic surface roughening and the appearance uniformity of the roughened surface. Is to provide.

Another object of the present invention is to provide an aluminum alloy base plate for electrolytic surface-roughening lithographic printing plate by continuous casting and rolling, which has the uniformity of electrolytic surface roughening and the appearance uniformity of the roughened surface. The object of the present invention is to provide a method for efficiently manufacturing at low cost by a simple process that does not require a long time.

[0017]

In order to achieve the above object, an aluminum alloy base plate for electrolytic graining lithographic printing plate of the present invention is an aluminum alloy cold rolled plate produced by continuous casting and rolling. 20 to 0.80 wt% Fe, with the balance being aluminum, crystal grain refining elements, and unavoidable impurity elements, of which Si content is 0.3 wt% or less and Cu content. The amount is 0.05 wt% or less, and the crystal grains in the surface layer portion have a width of 150 μm or less in a direction parallel to the plate surface and perpendicular to the cold rolling direction, and a length in a direction parallel to the cold rolling direction is 8% or more of the above width. It is characterized by being less than twice.

In order to achieve the above object, the method for producing an aluminum alloy base plate for electrolytic graining lithographic printing plate by continuous casting and rolling according to the present invention is 0.20 to 0.80 wt.
% Fe, with the balance being aluminum, grain refinement elements, and unavoidable impurity elements, of which the Si content is 0.3 wt% or less and the Cu content is 0.05 wt. % Of the aluminum alloy melt is continuously cast and rolled to form a strip having a thickness of 20 mm or less, and then heat treatment is performed during the cold rolling to determine the size and shape of the crystal grains of the cold rolled sheet surface layer portion. The width is controlled to be 150 μm or less in the direction parallel to the plate surface and at right angles to the cold rolling direction, and the length in the direction parallel to the cold rolling direction is 8 times or less the above width.

The heat treatment during cold rolling is preferably performed at least once by rapid heating capable of preventing local grain growth during heating.

It is desirable that the rapid heating is performed at a temperature rising rate of 1 ° C./sec or more.
It is desirable to carry out at a temperature of 600 ° C.

[0021]

As a result of various studies to solve the problems of the prior art, the inventor continuously casts and rolls an aluminum alloy having the above-specified chemical composition, and determines the size of crystal grains in the surface layer of the cold-rolled sheet.・ By keeping the shape within the specified range,
It was found that the uniformity of electrolytic surface roughening and the uniformity of the appearance of the roughened surface can be ensured, and the aluminum alloy base plate for electrolytic surface roughening lithographic printing plate of the present invention was realized.

Then, the size of the crystal grains within the above specified range
The shape is found to be obtained by heat treatment and recrystallization during cold rolling of the aluminum alloy after continuous casting and rolling, and a method for producing an aluminum alloy base plate for electrolytic graining lithographic printing plate of the present invention. It was realized.

The reason why the continuous casting and rolling method is used in the present invention is as follows. In continuous casting and rolling, the casting material is much thinner than DC casting, and the solidification rate of the casting material is high, so the crystallized substances are fine and uniform, and it is necessary to heat-treat the ingot as in the DC casting method. Absent. Therefore, since high-temperature long-time treatment is not performed, neither precipitation of supersaturated solid solution elements nor formation of coarse recrystallized grains occurs, and streak (streak unevenness) caused thereby reduces the uniformity of the appearance of the electrolytically roughened surface. Absent.

Since the cast material produced by continuous casting and rolling is much thinner than the DC ingot, it can be used for cold rolling without hot rolling. In addition, since the cast material is relatively thick, even when hot rolling is performed before cold rolling, the cast material obtained by continuous casting and rolling is very thin as compared to the ingot produced by DC casting.
Hot rolling to obtain a thickness suitable for cold rolling is extremely short and does not require high temperature and long time. The reason for using the above-defined chemical composition in the present invention is as follows.

The Fe content is in the range of 0.20 to 0.80 wt%. Fe is necessary for improving the mechanical strength,
If the content is less than the lower limit, the effect cannot be sufficiently obtained, and if it exceeds the upper limit, coarse Al—Fe-based intermetallic compounds are crystallized to impair the uniformity of pits on the electrolytically roughened surface. It is preferably 0.50 wt% or less.

The Si content is 0.3 wt% or less. Si
Is an element contained as an impurity in the aluminum alloy, and if the content is excessive, the uniformity of electrolytic surface roughening is impaired, so the content is made 0.3 wt% or less.

The Cu content is 0.05 wt% or less. C
u is an element contained as an impurity in the aluminum alloy, but is preferably 0.00 because it is preferable for the uniformity of electrolytic surface roughening.
It is desirable to contain 1 wt% or more. However, if the content is too large, the pits are likely to become coarse during electrolytic surface roughening, and the uniformity of electrolytic surface roughening is impaired.
wt% or less. It is preferably 0.03 wt%.

The crystal grain refining element may be appropriately added in order to refine the crystal grains during casting and prevent cracking.
Therefore, for example, Ti can be added in the range of 0.01 to 0.04 wt% and B can be added in the range of 0.0001 to 0.02 wt%.

As the impurity element, Mg, Mn, Cr,
Zr, V, Zn, Be, and the like may be contained, but these impurities do not have a great adverse effect if the amount is 0.05 wt% or less.

Next, in the aluminum alloy cold-rolled sheet of the present invention, the crystal grains in the surface layer portion have a width of 150 μm or less in a direction parallel to the plate surface and perpendicular to the cold-rolling direction, and a length in a direction parallel to the cold-rolling direction. Is less than 8 times the above width. Here, "surface layer" means
It refers to a region from the surface involved in roughening to a depth of at least about 30 μm.

In the continuously cast rolled aluminum alloy cold-rolled sheet having the chemical composition in the above-mentioned specified range, the metal structure of the surface layer portion is set as described above, so that the hot-rolling process such as the DC cast aluminum alloy cold-rolled sheet occurs. Since coarse recrystallized grains do not exist, deterioration of appearance uniformity of the electrolytically roughened surface due to streaks (streak patterns) caused by the coarse recrystallized grains does not occur.

If the crystal grains in the surface layer of the cold-rolled sheet have widths and lengths outside the above-specified ranges, streaks occur and the appearance uniformity of the roughened surface cannot be obtained.

The width of the crystal grains in the surface layer of the cold-rolled sheet is more preferably 120 μm or less. The ratio of the length to the width (elongation ratio) is generally 1.5 or more, preferably 6 or less.

The thickness of the aluminum alloy base plate for electrolytically roughened lithographic printing plate according to the present invention is generally 1 mm or less, preferably 0.1 to 0.5 mm.

According to the method of the present invention, after the coil of the aluminum alloy strip is formed by continuous casting and rolling, heat treatment for recrystallization is performed during the cold rolling, and then the steps up to the final cold rolling are performed. Thereby, the aluminum alloy base plate as a cold-rolled plate in which the size and shape of the surface layer crystal grains are within the specified range can be efficiently manufactured at low cost by a simple process that does not require a long time. it can.
At that time, it is important to properly select the conditions of the recrystallization heat treatment during continuous casting rolling and cold rolling in order to surely obtain a desirable crystal grain state in order to make the appearance of the electrolytic roughened surface uniform. Is.

In the method for producing a continuously cast rolled plate, a molten aluminum alloy melt that has been subjected to slag removal treatment or the like is melted by the Hunter method, the 3C method, the Hazarley method, or the belt caster method to obtain a strip (rolling of 20 mm or less Slab), which is wound up into a coil. As a result, the molten aluminum alloy is rapidly solidified, the alloy components are sufficiently dissolved in the matrix, and the second phase particles are crystallized uniformly and finely. If the plate thickness is 20 mm or more, this effect becomes poor,
Further, since the plate thickness is large, the number of subsequent rolling steps is increased, resulting in poor productivity.

An aluminum alloy strip having a thickness of 20 mm or less is formed from a molten aluminum alloy by continuous casting and rolling, and this is wound into a coil, which is then cold-rolled without homogenizing heat treatment and then having a predetermined plate thickness of aluminum. Use alloy base plate. At that time, when the heat treatment is not performed under appropriate conditions during the cold rolling, the electrolytic graining is not uniform and the roughened surface is also not uniform in appearance.

Particularly, in order to ensure the uniformity of the appearance of the roughened surface, the cold rolling is performed so that the width of the crystal grains in the surface layer portion after the final cold rolling in the direction perpendicular to the rolling direction is 150 μm or less. Appropriately select the heat treatment conditions during rolling, and make the length in the rolling direction of the crystal grains at the time when the desired plate thickness is obtained by cold rolling after this heat treatment a magnification (elongation rate) with respect to the width of 8 or less. It is important to appropriately select the cold rolling conditions so that

That is, the width of the crystal grains in the surface layer of the raw sheet after the final cold rolling is almost the same as the width of the recrystallized grains generated by the heat treatment performed during the cold rolling. Therefore, the grain width of the surface layer portion after the final cold rolling is almost determined by the heat treatment during the cold rolling. On the other hand, the length of the surface layer crystal grains after the final cold rolling is determined by the extent to which the length of the recrystallized grains generated by the heat treatment during the cold rolling is stretched by the cold rolling after the heat treatment.

As an example of a desirable mode of heat treatment performed during cold rolling, a continuous annealing apparatus is used to heat to a temperature of 440 to 600 ° C. at a temperature rising rate of 1 ° C./sec or more, and when a predetermined temperature is reached. Immediately or after holding at a predetermined temperature for about 30 minutes or less, immediately cool.

The heating rate is set to 1 ° C./sec or more because it is desirable that the heating rate is as high as possible in order to make the appearance of the roughened surface uniform. From the experience of the present inventor, it has been found that when the heating rate is too slow, the recrystallized grains are coarsened entirely or locally and it becomes difficult to make the appearance of the roughened surface uniform. The mechanism has not been completely clarified yet, but it is presumed that it is due to the following reasons.

In general, the size of the crystal grains when the recrystallization is completed depends mainly on the number of recrystallized nuclei and the growth rate of subgrains. That is, the larger the number of recrystallized nuclei and the faster the growth rate of subgrains, the finer the size of the recrystallized grains.

The recrystallized nuclei are likely to be generated in the non-uniformly deformed region. Examples of such regions include coarse dispersed particles and the vicinity of old grain boundaries, and deformation zones and shear zones produced by plastic working. On the other hand, the growth of subgrains is hindered by the presence of fine particles, for example finely precipitated particles.

In the aluminum alloy cold-rolled sheet produced by continuous casting and rolling according to the present invention, most of the supersaturated solid solution element mainly composed of Fe during casting is maintained as it is. Therefore, the second phase compound particles are likely to be finely precipitated during the recrystallization heat treatment, the growth of subgrains is hindered by these fine particles, and the recrystallized grains become coarse. Therefore, in order to prevent this, it is important to quickly raise the temperature to the recrystallization temperature.

Further, the heat treatment temperature is set to 440 ° C. or higher because recrystallization sufficiently occurs within this temperature range and the uniformity of electrolytic surface roughening and the appearance uniformity of the roughened surface can be easily ensured. . However, if the heat treatment temperature is too high, the strength of the base plate may decrease during the heat treatment and deformation may occur, and the recrystallized grains may become coarse. Therefore, the temperature is preferably 600 ° C. or lower.

If the holding time of the heat treatment is too long, the recrystallized grains become coarse. Therefore, it is usually preferably 10 minutes or less, more preferably 2 minutes or less.

Cooling from the heat treatment temperature is preferably as fast as possible in order to improve productivity. For example, 1 ℃ / se
Cool to 100 ° C or lower at a cooling rate of c or higher. It is more desirable to perform rapid cooling by water cooling at a cooling rate of 500 ° C./sec or more.

The heat treatment may be carried out in an ordinary continuous annealing furnace, and the magnetic induction heating (Transverse Flux Induction Heatin
g) Method may be used. In particular, the magnetic induction heating method is preferable because it is heated by the heat generated from the material to be heat-treated, so that the amount of oxide film formed on the surface of the material to be treated is small and the surface roughening treatment is less adversely affected.

As already described, the heat treatment during the cold rolling described above makes the width of the surface layer crystal grains after the final cold rolling 150 μm.
m or less, so that the appearance of the roughened surface is made uniform. As described above, this heat treatment is preferably performed by rapid heating so that coarsening of recrystallized grains can be prevented. This heat treatment is performed once or plural times during the cold rolling. In case of multiple times, at least one of them
When the heating is performed by the rapid heating described above, the effect of preventing the recrystallized grains from coarsening due to the rapid heating can be obtained. Of the plurality of times, only once may be performed by a continuous annealing furnace or rapid heating by magnetic induction heating, and other heat treatments may be performed by using a batch type annealing furnace having a slow heating rate.

The crystal grain width of the surface layer portion after the final cold rolling is 150
In order to reduce the local difference in the amount of deformation zone and shear zone caused by plastic working, in addition to the condition of heat treatment performed during cold rolling, It is more desirable to consider the cumulative reduction rate. In particular, it is desirable to consider the cumulative reduction rate up to heat treatment by rapid heating. In particular, it is desirable that the cumulative reduction rate before heat treatment by rapid heating be 50% or more. Cumulative reduction refers to the total reduction given by multiple or single cold rolling passes without heat treatment.

Further, in order to make the length of the surface layer crystal grains after the final cold rolling within 8 times the width, it is desirable that the rolling reduction after the final heat treatment is 80% or less. Of course, in the design of the cold rolling process, it is necessary to set the reduction ratio of each pass and the condition and timing of the heat treatment so that the raw plate after the final cold rolling can have the required mechanical strength. .

Before the heat treatment during the cold rolling,
If necessary, deposits such as rolling oil are removed by alkali cleaning or the like.

In the present invention, since the strip formed by continuous casting and rolling is subjected to cold rolling, the hot rolling is not performed before the cold rolling, or even if the hot rolling is performed, the time is very short,
Since it is only about 1/10 of the conventional method by the DC method, it is not exposed to a high temperature for a long time. Therefore, the elements that are solid-solved in supersaturation during casting rarely precipitate during the hot rolling process, and precipitate only for the first heat treatment performed during cold rolling. Due to this precipitation that occurs in the recrystallization process, a large number of fine precipitation particles are uniformly dispersed. As a result, pit formation by electrolytic etching occurs uniformly,
That is, electrolytic graining is uniformly performed.

As described above, the heat treatment performed during the cold rolling first contributes primarily to the appearance uniformity of the roughened surface through appropriate recrystallization, but at the same time, it is supersaturated in the second sense. The precipitation of the solid solution element contributes to the uniformity of electrolytic surface roughening and the appearance uniformity of the roughened surface.

In the conventional method of DC casting, the ingot was subjected to homogenizing heat treatment, hot rolling, and intermediate annealing in cold rolling. On the other hand, in the present invention, the strip obtained by continuous casting and rolling is not subjected to hot rolling, or is performed for a very short time, and mainly subjected to cold rolling and heat treatment in the middle thereof. Therefore, the number of steps is much smaller than that of the conventional method. As described above, the present invention is conventional in that the electrolytic roughening uniformity and the appearance uniformity of the roughened surface can be realized at low cost and efficiently by such a simple process that does not require a long time. It can be said that it is extremely advantageous over technology.

The present invention will be described in more detail below with reference to examples.

[0057]

EXAMPLE An aluminum alloy having the composition shown in Table 1 was continuously cast-rolled and was not hot-rolled or slightly hot-rolled. A rolled sheet was manufactured.

[0058]

[Table 1]

For the aluminum alloy A in Table 1,
A hunter continuous casting and rolling machine was used to form a strip coil having a thickness of 7 mm. This was made into a cold-rolled plate having a desired thickness by the plate making process shown in Table 2 and then corrected in the rolling direction to obtain an aluminum alloy base plate for a lithographic printing plate.

Regarding the aluminum alloy B in Table 1,
With a belt caster type continuous casting and rolling machine, a thickness of 15.
Cast into an 8 mm slab. After hot rolling, a cold-rolled plate having a desired thickness was prepared by the plate making process shown in Table 2 and then corrected in the rolling direction to obtain an aluminum alloy base plate for a lithographic printing plate.

The heat treatment conditions during the cold rolling were as follows. About temperature rising, rapid heating 150 ℃ / se
c or a heating rate of 10 ° C./sec, a low heating rate of 0.
The heating was performed at a temperature rising rate of 03 ° C./sec (= 100 ° C./hour). Regarding holding and cooling at a predetermined heat treatment temperature, at each heating rate, in the case of 150 ° C / sec, immediately after reaching the predetermined temperature, water cooling at a cooling rate of 500 ° C / sec or more, 10 ° C / sec
In the case of sec, it is kept at a predetermined temperature for 1 minute and then air-cooled to 0.
In the case of 03 ° C./sec, the temperature was kept at a predetermined temperature for 2 hours and then air cooling was performed.

The heating rate of 150 ° C./sec was measured by a magnetic induction heating device (Transverse Flux Induction Heater), 1
The heating rate of 0 ℃ / sec is 0.03 ℃ / se in the experimental furnace.
The temperature rising rate of c (100 ° C./hour) was obtained by a batch annealing furnace.

[0063]

[Table 2]

Nos. 1 to N obtained by the plate making process in Table 2
o. The mechanical properties of the respective alloy base plates of the present invention example and the comparative example of 17 were measured by a tensile test, and the uniformity of electrolytic roughening and the appearance uniformity of the roughened surface were measured as follows. evaluated.

In the case where the heat treatment was performed during the cold rolling according to the present invention, the solid solution amounts of the main elements were in the range of Fe solid solution amount ≦ 250 ppm, Si solid solution amount ≦ 150 ppm, and Cu solid solution amount ≦ 120 ppm. It was inside.

(1) Uniformity of Electrolytic Surface Roughening A base plate was brush-grained in a suspension of bamistone / water, and then subjected to alkali etching and desmut treatment. Next, electrolytic surface roughening was carried out by electrolytic etching in a 1% nitric acid using an electric power source having an electrolytic waveform in which the polarities are alternately converted, so that the amount of electricity at the anode was 150 coulomb / dm ² .

After washing in sulfuric acid, the surface was observed with a scanning electron microscope (SEM). Further, the uniformity of graining was evaluated by visual observation of the surface of the raw plate. The evaluation is "good (○)" for uniform grain, "somewhat difficult (△)" for a little unetched part, and "not good" for many unetched part or non-uniform grain. Poor (x) ".

(2) Appearance uniformity of roughened surface The base plate was brush-grained in a suspension of Bumistone / water, and then subjected to alkali etching and desmut treatment.

Next, using a power source having an electrolytic waveform in which the polarities are alternately converted, the amount of electricity at the anode is 150 in 1% nitric acid.
Electrolytic surface roughening was performed by electrolytic etching with Coulomb / dm ² .

After washing in sulfuric acid, an anodized film was formed in sulfuric acid, and the surface was visually observed to evaluate the uniformity of appearance. The evaluation was "good (○)" when the appearance was uniform, "somewhat difficult (△)" when the appearance was somewhat uneven, and "poor ()" when the appearance was not uniform or streaks were observed. X) ”.

The results obtained are shown in Table 3 together with the final cold rolling rate, the width of the surface layer crystal grains, and the length of the surface layer crystal grains.

[0072]

[Table 3]

As can be seen from Table 3, the alloy base plates (Nos. 2, 3, 4, 5, 8, 10, 12, 14, 1 of the present invention are shown.
5, 16, 17), the width of the surface layer crystal grains is 15
The ratio of the length to the width (elongation rate) was 0 μm or less, and the elongation ratio was 8 or less, and both the uniformity of electrolytic surface roughening and the appearance uniformity of the electrolytic surface roughening surface were good (◯).

On the other hand, the alloy base plate of the comparative example (No. 1,
In the case of 6, 7, 9, 11, 13), the following defects occurred. Comparative Examples Nos. 1 and 11 were not subjected to the heat treatment during the cold rolling specified in the present invention, the electrolytic surface roughening was non-uniform, and the surface layer crystal grains had an acicular structure,
The appearance of the roughened surface was not uniform, with significant streaks.

In Comparative Examples Nos. 6 and 13, the ratio of the length to the width of the surface layer crystal grains (elongation ratio) exceeds 8 specified in the present invention, and the uniformity of electrolytic surface roughening is good. However, the appearance of the roughened surface was not uniform due to remarkable streaks.

In Comparative Examples Nos. 7 and 9, the width of the surface layer crystal grains exceeds 150 μm specified in the present invention.
The appearance of the roughened surface was uneven and slightly uneven.

From the results shown in Table 3, it is necessary to satisfy all the requirements specified in the present invention in order to improve both the electrolytic roughening uniformity and the roughened surface appearance uniformity. I understand.

[0078]

As described above, according to the present invention,
Provided is an aluminum alloy base plate for electrolytic surface roughening lithographic printing plate by continuous casting and rolling, which is provided with the uniformity of electrolytic surface roughening and the appearance uniformity of the roughened surface. Further, there is provided a method for efficiently producing this aluminum alloy base plate for electrolytic surface-roughened lithographic printing plate at low cost and by a simple process which does not require a long time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Suzuki, 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Nikkei Giken Co., Ltd. (72) Hirokazu Sakaki 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Fuji Shashin Film Co., Ltd. (72) Inventor Yoshinori Hotta 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Fuji Shashin Film Co., Ltd.

Claims (7)

[Claims] 1. A cold-rolled aluminum alloy sheet produced by continuous casting and rolling, containing 0.20 to 0.80 wt% Fe, the balance being aluminum, a grain refinement element, and an unavoidable impurity element, Among the impurity elements, the Si content is 0.3 wt% or less and the Cu content is 0.05
wt% or less, the crystal grains in the surface layer portion have a width of 150 μm or less in the direction parallel to the plate surface and perpendicular to the cold rolling direction, and a length in the direction parallel to the cold rolling direction of 8 times or less the width. An aluminum alloy base plate for electrolytic surface-roughening lithographic printing plate, which is characterized in that 2. The content of Fe is 0.20 to 0.80 wt%, the balance is aluminum, a grain refinement element, and an unavoidable impurity element, and the content of Si in the impurity element is 0. 3 wt% or less and Cu content of 0.05
After the aluminum alloy melt of less than wt% is continuously cast and rolled into strips having a thickness of 20 mm or less, heat treatment is performed during the cold rolling to determine the size and shape of the crystal grains in the surface layer of the cold rolled sheet. The electrolytic roughing is characterized in that the width in the direction parallel to the plate surface and perpendicular to the cold rolling direction is 150 μm or less, and the length in the direction parallel to the cold rolling direction is 8 times or less the above width. A method for producing an aluminum alloy base plate for a surface-wise planographic printing plate. 3. The method according to claim 2, wherein the heat treatment during the cold rolling is performed at least once by rapid heating capable of preventing local grain growth during heating. 4. The method according to claim 3, wherein the rapid heating is performed at a temperature rising rate of 1 ° C./sec or more. 5. The heat treatment by the rapid heating is performed at 440.degree.
The method according to claim 3 or 4, wherein the method is performed at a temperature of 600 ° C. 6. The method according to claim 3, wherein the cumulative rolling reduction before the rapid heating is 50% or more. 7. The cumulative reduction rate after the last heat treatment of the heat treatments is set to 80% or less.
7. The method according to any one of 1 to 6.