JPH1030142A - Aluminum alloy sheet for printing plate, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an aluminum alloy sheet for printing plate, capable of uniformly forming surface roughing pits, and to provide its production method. SOLUTION: The aluminum alloy sheet for printing plate has a composition consisting of, by weight, 0.20-0.6% Fe, 0.03-0.15% Si, 0.005-0.05% Ti, 0.005-0.20% Ni, and the balance Al with inevitable impurities. Further, the maximum value of the real number axis component in the impedance locus extended on the complex plane is regulated to 100-10000(Ω).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy plate for a printing plate used as a support for offset printing or the like, and more particularly to an aluminum alloy plate for a printing plate capable of forming a uniform electrolytically roughened surface. It relates to the manufacturing method.

[0002]

2. Description of the Related Art Conventionally, in offset printing, an aluminum or aluminum alloy (hereinafter referred to as aluminum) plate is generally used as a support. This aluminum plate for a printing plate is obtained by subjecting the surface of an aluminum plate to a surface roughening treatment in order to impart adhesion to a photosensitive film and water retention of a non-image portion. Conventionally, mechanical treatment methods such as a ball polishing method and a brush polishing method have been used as the surface roughening method. Recently, however, an electrolytic solution mainly containing hydrochloric acid or hydrochloric acid or an electrolytic solution mainly containing nitric acid has been used. An electrolytic surface roughening method for electrochemically roughening the surface of an aluminum plate using a liquid, and a processing method combining the above-mentioned mechanical processing method and this electrolytic surface roughening method are mainly used. It is becoming. This is because the rough plate obtained by the electrolytic surface roughening method is suitable for plate making, and also has excellent printing performance,
Further, the electrolytic surface roughening method is suitable for the case where the aluminum alloy plate is coiled and subjected to continuous processing.

As described above, it is required that the surface of the aluminum alloy plate to be roughened be formed with uniform irregularities (pits) by the roughening treatment. In an aluminum alloy plate for a printing plate on which uniform irregularities are formed,
Adhesion with the photosensitive film and water retention are improved, and excellent image clarity and printing durability can be obtained. Also, recently, in order to reduce the cost of the surface roughening treatment, there is a strong demand for the development of a material capable of forming uniform irregularities in a shorter time or with a smaller amount of current.

[0004] An aluminum plate suitable for such an electrochemical surface roughening treatment can be obtained by adding Fe, Cu and other trace elements.
0.2 to 1.0% by weight, Cu: 0.1 to 2.0% by weight, and 0.05 to 0.1% by weight of one or more elements selected from Sn, In, Ga and Zn. Aluminum alloy plates have been proposed (Japanese Patent Laid-Open No. 58-2101).
No. 44). This aluminum alloy plate is characterized by a high dissolution rate with respect to chemical etching.

Further, as an aluminum alloy plate having excellent roughness uniformity, Fe: 0.05 to 0.5% by weight, Mg:
0.1 to 0.9% by weight, Si: 0.2% by weight or less, and Cu: 0.05% by weight or less, and one or more elements selected from the group consisting of Zr, V and Ni. 0.0
An aluminum alloy plate containing 1 to 0.3% by weight and the balance consisting of Al and unavoidable impurities has been proposed (JP-A-62-230946).

Further, as an aluminum alloy plate having good strength and uniformity of pits, Mg: 0.30 to 3% by weight, Fe: 0.15 to 0.50% by weight, Ni: 0.0
05 to 0.30% by weight and Ti: 0.01 to 0.1
0 wt%, Si, Cu, and Mn are each regulated to 0.20 wt% or less, and the balance is Al and the content of each element is 0.10 wt% or less. Has been proposed (JP-A-63-30294).

Further, while forming a uniform rough surface,
As an aluminum alloy plate that prevents contamination of non-image areas and improves tone reproducibility and color tone (brightness) of image areas, F
e: 0.1 to 1.0% by weight, Si: 0.02 to 0.
There has been proposed an aluminum alloy plate containing 15% by weight and an impurity of Cu: 0.003% by weight or less, with the balance being unavoidable impurities other than Al and Cu (Japanese Patent Publication No. 47545/1994).

Furthermore, Fe: 0.1 to 0.5% by weight, Si: 0.03 to 0.30% by weight, Cu: 0.0
01 to 0.03% by weight, Ni: 0.001 to 0.0
3% by weight, Ti: 0.002 to 0.05% by weight and G
a: containing 0.005 to 0.020% by weight, and
An aluminum alloy plate having a total content of a and Ti of 0.010 to 0.050% by weight has been proposed (JP-A-3-177528). In this aluminum alloy plate, streaks (also referred to as streaks, hereinafter referred to as streaks), which are streaky irregularities, and irregular image quality irregularities are improved, and the rough surface is uniform. Dirt on the wire is prevented.

[0009]

However, recently,
In order to reduce the cost, an improvement in the electrolytic processing speed is required, and there is a need for an aluminum plate that can form uniform pits in a short electrolytic surface roughening treatment. That is, even if the pits to be formed are shallow, it is demanded that the pits are uniformly etched in a short time and that an unetched portion (an unetched portion of the aluminum plate surface) does not occur in the aluminum plate. However, the conventional aluminum plate has not satisfied such a demand.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an aluminum alloy plate for a printing plate in which roughened pits are uniformly formed, and a method for manufacturing the same.

[0011]

The aluminum alloy plate for a printing plate according to the present invention comprises Fe: 0.20 to 0.6% by weight, Si: 0.03 to 0.15% by weight, Ti: 0.0
0.05 to 0.05% by weight and Ni: 0.005 to 0.20% by weight, with the balance being Al and unavoidable impurities, and the maximum value of the real axis component in the impedance locus developed on the complex plane is 100 to 1000
(Ω).

The method for producing an aluminum alloy plate for a printing plate according to the present invention is characterized in that Fe: 0.20 to 0.6% by weight,
i: 0.03 to 0.15% by weight, Ti: 0.005 to 0.05% by weight, and Ni: 0.005 to 0.20%
% Of the aluminum alloy ingot consisting of Al and unavoidable impurities is homogenized at a temperature of 500 to 630 ° C.
A method for producing an aluminum alloy plate for a printing plate, which is hot-rolled at 0 ° C., wherein the aluminum alloy plate comprises:
The maximum value of the real number axis component in the impedance locus developed on the complex plane is 100 to 1000 (Ω). After hot rolling, cold rolling, intermediate annealing, and final cold rolling can be sequentially performed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies to obtain an aluminum alloy plate for a printing plate on which uniform roughened pits are formed. As a result, among the alloy elements contained in the aluminum alloy plate, Fe and Si more added
It has been found that it is effective to add appropriate amounts of Ni and Ti in addition to controlling the content of Ni.

By the way, for the surface roughening treatment of an aluminum alloy plate to be a printing plate, an alternating current electrolysis method is generally used. In this method, irregularities are formed on the surface of an aluminum alloy plate by cyclically generating a dissolution reaction of aluminum at the anode and a film formation reaction on the surface of the alloy plate at the cathode at a constant frequency. In particular, the initial reaction of the anode in each cycle largely governs the morphology of the rough surface, ie, the degree of unetched portions and the uniformity of the roughened pits.

[0015] From these facts, the inventors of the present invention improved the etching property by defining the resistance of the film formed on the surface of the aluminum alloy plate in an appropriate range, thereby improving the etching of the unetched portion. It has been found that formation can be prevented and the uniformity of the roughened surface is improved.

Hereinafter, the aluminum alloy plate for a printing plate of the present invention will be further described. First, the chemical components contained in the aluminum alloy plate and the reasons for limiting the composition will be described.

Fe: 0.20 to 0.6% by weight Fe is a main component of the aluminum alloy, and forms an Al—Fe intermetallic compound in the aluminum alloy to roughen the electric field of the aluminum alloy plate. At times,
It is an element that forms initial pits. Further, Fe has an effect of refining recrystallized grains and an effect of improving mechanical strength by homogenizing the structure. If the Fe content is less than 0.20% by weight, Fe-
Since Al-based intermetallic compounds are insufficient, the formation of initial pits during electric field surface roughening is insufficient. on the other hand,
When the Fe content exceeds 0.6% by weight, a coarse compound is formed, and the roughened surface of the electric field becomes uneven. Therefore, the Fe content is set to 0.20 to 0.6% by weight.

Si: 0.03 to 0.15 wt% Si is an element that forms an Al—Fe—Si based intermetallic compound, promotes the formation of initial pits, and improves pit uniformity. Si content is 0.03% by weight
If it is less than 1, the intermetallic compound is insufficient, and the formation of initial pits is insufficient. On the other hand, when the Si content exceeds 0.15% by weight, a coarse compound is formed,
The roughened surface of the electric field becomes uneven. Therefore, the Si content is set to 0.03 to 0.15% by weight.

Ti: 0.005 to 0.05% by weight Ti is an element having a function of refining a cast structure. Ti
If the content is less than 0.005% by weight, the effect of refining the cast structure cannot be obtained. On the other hand, Ti
Even if it is added in excess of 05% by weight, the effect will be saturated and the raw material cost will increase. In addition, uneven pits are easily formed on the roughened surface of the electric field. Therefore, the Ti content is set to 0.005 to 0.05% by weight.

Ni: 0.005 to 0.20% by weight Ni is an element that improves the chemical solubility of the material and improves the etching amount when the electric field is roughened. Ni forms an Fe-Al-Si-Ni-based intermetallic compound in the aluminum alloy. This compound is Al-Fe-S
Since the potential is more noble than the i-type compound, the formation of initial pits during the roughening of the electric field is further promoted, and a uniform roughened surface can be formed in a short time. Ni
When the content is less than 0.005% by weight, the improvement in chemical solubility becomes insufficient and the formation of initial pits becomes insufficient. On the other hand, if the Ni content exceeds 0.20% by weight, the chemical solubility is excessively promoted, and the uniformity of the pits is impaired. Therefore, the Ni content is 0.1.
005 to 0.20% by weight.

Next, the method of measuring the resistance of the film formed on the surface of the aluminum alloy plate and the reasons for limitation will be described.

Impedance locus developed on a complex plane
Maximum value of real axis component at: 100 to 1000
(Ω) There is an interface impedance as a means for capturing a phenomenon occurring on a metal surface. In the present invention, the resistance value of a film formed on the surface of an aluminum alloy plate is calculated by measuring the interface impedance. I do. The interface impedance can be graphically represented by an impedance trajectory, that is, a vector trajectory when the impedance Z (jω) is set to the angular frequency ω as a parameter.
If the coordinates are divided into a real axis component R and an imaginary axis component X on the complex plane, the impedance Z can be expressed by the following equation (1).

[0023]

## EQU1 ## Z (jω) = R (ω) + jX (ω) where ω: angular frequency.

FIG. 1 is a graph showing examples of impedance trajectories of four types of printing plates, with an imaginary axis component on the vertical axis and a real axis component on the horizontal axis. In general, when a circle close to the locus is drawn in the impedance locus, the smaller value of the real axis intercept of this close circle can be defined as the liquid resistance, and the larger value can be defined as the sum of the liquid resistance and the surface resistance. Therefore, the surface resistance can be obtained by calculating the difference between the two. The absolute value of the impedance Z is given by the following equation (2).
Can be represented by

[0025]

| Z | = {R ² (ω) + X ² (ω)} ^1/2

As shown in FIG. 1, the impedance trajectories 1, 2, 3 and 4 of the printing plate are substantially semicircular and can be regarded as being equivalent to a close circle. Is the surface resistance. Note that the impedance trajectories 1, 2, 3, and 4 respectively correspond to Example Nos.
4 shows an example of an impedance locus of a printing plate obtained according to the conditions 1, 4, 3, and 6.

When the surface resistance of the aluminum alloy plate is less than a predetermined range, that is, when the maximum value of the real axis component of the impedance locus is less than 100Ω, the entire surface is liable to be melted, uniform pits are not formed, and the rough surface is not formed. Is reduced. On the other hand, when the surface resistance of the aluminum alloy plate exceeds a predetermined range, that is, when the maximum value of the real number axis component of the impedance locus exceeds 1000Ω, the etching property is insufficient, the unetched portion increases, and the uniformity of the rough surface is reduced. descend. Therefore, the maximum value of the real axis component in the impedance locus developed on the complex plane is 100 to 100
It is assumed to be 0Ω.

In the method for producing an aluminum alloy plate for a printing plate according to the present invention, it is important to control the homogenization treatment temperature and the hot rolling start temperature while defining the chemical components. As a result, when the obtained aluminum alloy plate is subjected to electrolytic surface roughening treatment, the etching is performed uniformly on the electrolytic surface roughened surface, and the pit size does not vary and is uniform. Becomes In this case,
After hot rolling, cold rolling, intermediate annealing, and final cold rolling may be sequentially performed.

Hereinafter, the reasons for limiting the numerical values of the homogenization treatment temperature and the hot rolling start temperature in the method for producing an aluminum alloy plate for a printing plate will be described.

Homogenization temperature: 500 to 630 ° C. When manufacturing an aluminum alloy plate from an aluminum alloy ingot by rolling or the like, it is necessary to homogenize at a predetermined temperature before rolling the ingot. . If the homogenization treatment temperature is lower than 500 ° C., homogenization becomes insufficient, so that a uniform roughened surface cannot be obtained. On the other hand, when the homogenization treatment temperature exceeds 630 ° C., the amount of solid solution in the aluminum alloy ingot becomes too large, and the starting point of initial pits at the time of electrolytic surface roughening is reduced, thereby promoting the increase of unetched portions. Therefore, the homogenization temperature is 500 to 6
30 ° C.

Hot rolling start temperature: 400 to 450 ° C. When hot rolling an aluminum alloy ingot subjected to the above homogenization treatment, it is necessary to start hot rolling at a predetermined temperature. If the hot rolling start temperature is lower than 400 ° C., dynamic recrystallization during rolling is insufficient, and the crystal structure of the rolled sheet becomes uneven, so that a uniform roughened surface cannot be obtained. On the other hand, if the hot rolling start temperature exceeds 450 ° C., crystal grains grow excessively between each pass of hot rolling, so that a uniform roughened surface cannot be obtained. Therefore, the hot rolling start temperature is set to 400 to 450 ° C.

[0032]

EXAMPLES Examples of the aluminum alloy plate for a printing plate according to the present invention will be specifically described below in comparison with comparative examples.

First, the ingots of aluminum alloys having various chemical compositions shown in Table 1 were chamfered to a thickness of 470.
mm and a homogenization treatment at 590 ° C. for 4 hours. Next, the rolling start temperature was set to 430 ° C., and hot rolling was performed, and then cold rolling, intermediate annealing, and cold rolling were sequentially performed to produce an aluminum alloy sheet having a thickness of 0.3 mm.

Thereafter, the obtained aluminum alloy plate is subjected to degreasing, neutralization washing and AC electrolysis under the processing conditions shown in Table 2 below, and further to remove oxides and the like formed by electrolysis. Was desmutted. Then, each sample subjected to the desmut treatment was washed with water and dried, cut out to a certain size to prepare a test piece, and each test piece was evaluated for the etching property and the uniformity of the roughened surface.

Further, after the prepared test pieces were degreased and neutralized under the conditions shown in Table 3 below, their impedance was measured, and the maximum value of the real axis component of the impedance locus was calculated. In the present embodiment, as a measured value of impedance, an electrochemical impedance measuring device HZ-1A is used.
(Manufactured by Hokuto Denko KK) was used. Hereinafter, the evaluation criteria of the etching property and the uniformity of the roughened surface will be described.

Etchability The roughened surface of each test piece was observed at a magnification of 350 times using a scanning electron microscope (SEM), and the microscope was adjusted so that the total area of the visual field was 0.02 mm ^2. Photo taken. From the obtained photograph, the non-etching rate was calculated by the following mathematical formula 3.

[0037]

## EQU3 ## Unetched rate (%) = (area of unroughened part / total area) × 100

The etching performance was evaluated as follows when the unetched rate calculated by the above equation 3 was 8.0% or less.
(Good etching property) and the unetched rate is 8.0%
Was exceeded (poor etching).

Roughened surface uniformity The roughened surface of each test piece was measured using a scanning electron microscope.
Micrographs were taken at a magnification of 500 ×. And
A line having a total length of 100 cm was drawn on the obtained observation photograph, and the sizes (diameters) of all the pits below the line were measured. In the evaluation of uniformity, those having a difference in size between the smallest pit and the largest pit of less than 3 μm are evaluated as ○ (good uniformity), 3
Those having a size of μm or more were evaluated as x (poor uniformity).

The evaluation results of the respective examples and comparative examples are shown in Table 1 below.
Are shown together.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

As shown in Table 1 above, Example No. In Nos. 1 to 6, since the content of each element and the maximum value of the real axis component of the impedance locus were within the ranges specified in the present invention, both the etching property and the uniformity were good. In addition, in Example No. 1, the interface impedances of 1, 3, 4 and 6 are shown as impedance trajectories 1, 3, 2 and 4. The maximum value of the real number axis component of the impedance No. 1 is the impedance locus 1, The maximum value of the real number axis component of the impedance No. 3 is the impedance locus 3, and 4, the maximum value of the real axis component is impedance locus 2, Example N
o. The maximum value of the real axis component of 6 is calculated from the impedance locus 4.

On the other hand, Comparative Example No. In No. 7, since the Ni content was less than the lower limit of the range of the present invention, initial pits and chemical solubility were insufficient. For this reason, many unetched portions remained, the size of the pits varied, and the uniformity deteriorated. Also, in Comparative Example No. 8 is Ni
Since the content exceeds the upper limit of the range of the present invention, the chemical solubility was excessively promoted, and the uniformity became poor. Comparative Example No. In No. 9, since the Si content exceeded the upper limit of the range of the present invention, a coarse compound was formed, and the electrolytically roughened surface became nonuniform, resulting in poor etching properties and uniformity.

Comparative Example No. 10, since the Si content is less than the lower limit of the range of the present invention, the intermetallic compound is insufficient,
Insufficient formation of initial pits. Also, Ti
Since the content was less than the lower limit of the range of the present invention, the casting structure was insufficiently refined, and the uniformity evaluation was poor. Comparative Example No. In No. 11, since the Fe content was less than the lower limit of the range of the present invention, initial pits at the time of electrolytic surface roughening were insufficient, and the evaluation of etching property and uniformity was poor.

Further, in Comparative Example No. In No. 12, since the Fe content exceeded the upper limit of the range of the present invention, a coarse compound was formed, and the electrolytically roughened surface became non-uniform. Comparative Example No. 1
3, since the Ti content is less than the lower limit of the range of the present invention,
The crystal grains were not sufficiently refined, non-uniform pits were formed, and the uniformity was poor. Comparative Example No. 14 is T
Since the i content exceeded the upper limit of the range of the present invention, a coarse compound was formed, the size of the pits became uneven, and the uniformity became poor.

Further, in Comparative Example No. In No. 15, the pit uniformity was poor because the Ni content exceeded the upper limit of the present invention range and the maximum value of the real axis component of the impedance locus was less than the lower limit of the present invention range. Comparative Example 16
Since the maximum value of the real axis component of the impedance locus exceeds the upper limit of the range of the present invention, an unetched portion remains, resulting in poor etching property and uniformity.

Next, an embodiment of a method for manufacturing an aluminum alloy plate for a printing plate according to the present invention will be specifically described in comparison with a comparative example.

First, in Example No. The aluminum alloy ingot having the composition of No. 1 was chamfered to a thickness of 470 mm, homogenized at various temperatures shown in Table 4 below, and further hot-rolled at various rolling start temperatures. Then cold rolling,
Intermediate annealing and cold rolling were sequentially performed to produce an aluminum alloy sheet having a thickness of 0.3 mm.

Thereafter, the obtained aluminum alloy sheet was subjected to Example No. Nos. 1 to 6 and Comparative Example Nos. 7 to 1
Under the same conditions as in Example 6, the etching property and the uniformity of the roughened surface were evaluated, and the maximum value of the real axis component of the impedance locus was calculated. The results of these evaluations are shown in Table 4 below.

[0052]

[Table 4]

As shown in Table 3 above, Example No. 21
In Nos. To 23, since the homogenization treatment temperature and the hot rolling start temperature are within the range of the present invention, and the maximum value of the real axis component of the impedance locus is within the range of the present invention, the evaluation of etching property and uniformity Were all good.

On the other hand, in Comparative Example No. In No. 24, the homogenization treatment temperature was lower than the lower limit of the range of the present invention, and the maximum value of the real axis component of the impedance locus was less than 100Ω, so that the uniformity was poor. Comparative Example No. In No. 25, since the homogenization temperature exceeded the upper limit of the range of the present invention and the maximum value of the real axis component of the impedance locus exceeded 1000Ω, the etching property and the uniformity were lowered.

Further, in Comparative Example No. In No. 26, since the hot rolling start temperature was below the lower limit of the range of the present invention and the maximum value of the real axis component of the impedance locus exceeded 1000Ω, the etching property and the uniformity were lowered. Comparative Example N
o. In No. 27, since the hot rolling start temperature exceeded the upper limit of the range of the present invention and the maximum value of the real axis component of the impedance locus was less than 100Ω, the uniformity was poor.

[0056]

As described above in detail, the aluminum alloy plate for a printing plate according to the present invention has a chemical composition defined and a film formed on the surface by the maximum value of the real axis component of the impedance locus. , The roughened pits are uniformly formed on the rough electrolytic surface, and the size of each pit is substantially constant.

In the method for producing an aluminum alloy plate for a printing plate according to the present invention, an aluminum alloy ingot having a predetermined chemical composition is homogenized and hot-rolled under predetermined conditions. Later, a uniform roughened pit is formed, and an aluminum alloy plate for a printing plate in which the size of each pit is substantially constant can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing an example of an impedance locus of a printing plate, with an imaginary axis component taken on a vertical axis and a real axis component taken on a horizontal axis.

[Explanation of symbols]

 1, 2, 3, 4; impedance locus

Claims (3)

[Claims] 1. Fe: 0.20 to 0.6% by weight, S
i: 0.03 to 0.15% by weight, Ti: 0.005 to 0.05% by weight, and Ni: 0.005 to 0.20%
An aluminum alloy for a printing plate, wherein the maximum value of a real axis component in an impedance trajectory developed on a complex plane is 100 to 1000 (Ω), the balance being Al and unavoidable impurities. Board. 2. Fe: 0.20 to 0.6% by weight, S
i: 0.03 to 0.15% by weight, Ti: 0.005 to 0.05% by weight, and Ni: 0.005 to 0.20%
% Of the aluminum alloy ingot consisting of Al and unavoidable impurities is homogenized at a temperature of 500 to 630 ° C.
A method for producing an aluminum alloy plate for a printing plate, which is hot-rolled at 0 ° C., wherein the aluminum alloy plate comprises:
A method for manufacturing an aluminum alloy plate for a printing plate, wherein a maximum value of a real axis component in an impedance locus developed on a complex plane is 100 to 1000 (Ω). 3. The method for producing an aluminum alloy plate for a printing plate according to claim 2, wherein cold rolling, intermediate annealing, and final cold rolling are sequentially performed after hot rolling.