JPS63143235A - Aluminum alloy for printing plate - Google Patents

Abstract

PURPOSE:To make an electrolytically etched pattern uniform and to improve the plate wear of a printing plate and the sharpness of an image by using an Al alloy contg. prescribed percentages of Mg, Fe and Zn in Al contg. reduced amts. of Si, Mn, Ti, Cr and Cu. CONSTITUTION:This Al alloy for a printing plate contains, by weight, 1-6% Mg, 0.05-1% Fe and 0.05-0.5% Zn in Al contg. <=0.15% Si, <=0.8% Mn, <=0.05% Ti, <=0.3% Cr and <=0.1% Cu as impurities.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an aluminum alloy for printing plates, particularly an aluminum alloy used for offset printing plates.

[Prior art and its problems]

Aluminum alloy for printing plates (hereinafter simply referred to as aluminum)
When using aluminum for printing, the aluminum surface is first treated by one or more of mechanical, chemical, and electrochemical methods in order to improve water retention and adhesion with photosensitizers. After the surface is roughened through the combined steps, it is usually subjected to predetermined post-treatments (anodizing treatment, hydrophilization treatment, inactivation treatment) to further improve printing characteristics. As for aluminum, for example, JIS^105
Those corresponding to 0, ^1100, and ^3003 are used. In particular, when roughening the aluminum surface by an electrochemical method, that is, by alternating current electrolytic etching treatment, Fe,
Materials equivalent to ^1050 with low impurity elements such as Si, Zn, Cu, Mg, and Mn have good surface treatability, which is an important condition for printing plates, and have good surface roughness (electrolytic etching bit pattern) after roughening. It has been said that it is desirable because of its uniformity. However, in recent years, in order to reduce material costs, aluminum has been made thinner and tougher by improving its yield strength, and its fatigue strength has been improved.
There has been a demand for aluminum alloy materials for printing plates with improved isotropy (no difference in fatigue strength in the aluminum rolling direction and in the direction perpendicular to the rolling head).In order to meet this demand, various aluminum alloy materials have been developed. Magnesium alloy-based aluminum is used, for example, in JP-A-58-42745, JP-A-59-133355, and JP-A-60-6334.
6, JP-A-60-220395, JP-A-60-220395, JP-A-6
It has been proposed as shown in Publication No. 1-26746 and the like. However, compared to the conventional ^1050 material, these proposed aluminum materials have greatly improved the yield strength and fatigue strength of aluminum, and have improved bending resistance during handling and plate elongation resistance during printing. Although improvements in properties and thinning can be obtained, the electrolytic etching bit pattern tends to be non-uniform;
It can be said that the printing properties are deteriorated, and that no product that is preferable for practical use has yet been provided.

[Disclosure of the invention]

As a result of intensive research into the above-mentioned problems, the present inventor has found that Si as an impurity is 0.15% by weight or less, M
n is 0.8% by weight or less, Ti is 0.05% by weight or less, C
In an aluminum material in which r is 0.3% by weight or less, Cu is 0.1% by weight or less, and the balance consists of 11 unavoidable substances and Al, 1.0 to 6.0% by weight of Mg, 0.05 ~1.
Aluminum alloys containing 0% by weight of Fe and 0.05 to 0.5% by weight of Zn provide a uniform electrolytic etching bit pattern that cannot be obtained with conventional aluminum-magnesium alloys, and therefore have improved printing durability. , it is possible to obtain an improvement in the clarity of the image, and also to obtain an improvement in isotropy and fatigue strength.
．． 4,6.8) Even if the material is approximately 0.05 to 0.3 mm thick, the yield strength is approximately 15 kg/So II2 or more, improving plate handling properties and preventing plate elongation during printing. I found out what I could get. In particular, this aluminum alloy is JIS^105011
For example, when the aluminum alloy of the present invention is used, a 0.05 mm thick one meets the above JIS standard.
^1050 It was comparable to 0.24mm thick HI3 material. Here, the content of Mg, Zn, etc. is limited as described above based on the following reason. That is, Mg is an element added for the purpose of improving strength and fatigue resistance, and it can be made to be a solid solution in aluminum materials, or be present at grain boundaries or within grains as an intermetallic compound of the ^f-M system. It is based on When the Mg content is less than 1.0% by weight, in order to ensure isotropy of fatigue strength in the rolling direction of aluminum and in the direction perpendicular to the rolling grain, 111n or 112n material is tempered and If the yield strength is about 15Kg/mm2 or more,
On the other hand, when the Mg content exceeds 6.0% by weight, the intermetallic compounds coarsely precipitated at the grain boundaries or inside the grains due to temper annealing are unevenly and deeply deposited by electrolytic etching. This is because it has been found that due to etching, defects such as stains in non-image areas are likely to occur. In addition, Fe usually exists as an intermetallic compound of ^Z-Fe system, f-Fe-Si system, or ^N-Fe-Nn-3i system, and most of them are crystallized in the matrix after casting. It exists as a solid solution or precipitates in the matrix. The effect of the addition of Fe is: (1) improvement in strength due to refinement of crystal grains or uniformity of structure (2); acting as a starting point for the initial bit during fermentation etching. When the content of Fe is less than 0.05% by weight, the above effect decreases, and conversely, when it is contained more than 1.0% by weight, coarse crystals such as N-Fe system are formed. This is because it has been found that there is a drawback that the rough surface after electrolytic etching tends to become non-uniform due to the presence of substances. Further, Zn is considered to be solidly dissolved in the matrix at the concentration of addition according to the present invention. Then, the Zn content is set to 0.05 to 0.5% by weight at a concentration of 1.0 to 6.0% by weight, where M is 1.0 to 6.0% by weight, at which the improvement in IR mechanical properties targeted by the present invention can be achieved. By doing so, the current ^
It has been found that an etching bit pattern equivalent to that of aluminum equivalent to 1050 can be obtained. That is, if Zn is less than 0.05% by weight, the rough surface after electrolytic etching will be uneven and the degree of etching will be small, resulting in poor efficiency; It was found that the rough surface after electrolytic etching tends to be non-uniform and that there are localized large bits due to over-etching. In particular, Hg is 1.0 to 6.0% by weight in aluminum.
When contained, an oxide film on the aluminum surface (usually ^
lzO*) becomes dense due to the presence of Mg element in the film, and if Zn is not added, it is difficult to be etched during the specified electrolytic etching, and unetched parts are likely to exist in the matrix part. However, Zn
The density of the oxide film is reduced by adding JIS^
The etching pattern will be the same as that of pure aluminum equivalent to 1050, and if Zn is contained in excess of 0.5% by weight, the oxide film will become brittle and the matrix will be easily etched excessively. It has been found that this makes it difficult to obtain a uniform etching pattern that is sequentially etched around the initial bit starting point, which is typified by intermetallic compounds such as -Fe-based. As other impurity elements, Si acts as the starting point of the initial bit.N-Fe-5i system, ^j! -Fe-M
It exists as an n-5i intermetallic compound (crystallized product), but basically it is a solid solution M8 in the Hg alloy.
It is sufficient if the concentration is such that MgzSi, which is precipitated and produced by the combination with , is not present. Therefore, the Si content must not exceed 0.15% by weight. Also, Mn is ^I! -Fe-Mn-based intermetallic compounds and some solid solutions exist, but basically,
This serves to improve the strength of the material and serve as a starting point for the initial bit. Therefore, ^#-Fe-Mn system, f-F
From this point of view, Mn should not be contained in an amount exceeding 0.8% by weight. must not. In addition, T1 is added to refine the ingot structure, and excessive addition causes the formation of linear micro defects due to the presence of ^/-Ti-based intermetallic compounds, so its content is must not exceed 0.05% by weight. In addition, Cr is an element that causes uniform precipitation of intermetallic compounds such as ^1-Fe and ^l-Hg, but if it is present in an amount exceeding 0.3% by weight, Cr causes ^1-Cr intermetallic compounds. The content should be 0.3% by weight or less because it may cause new compounds to be generated and tend to impede the uniformity of the electrolytically etched bit pattern. Further, if Cu is present in an amount exceeding 0.1% by weight, it tends to cause non-uniformity in the bit pattern after electrolytic etching depending on the concentration of Mg, so the content must be 0.1% by weight or less. In addition, when casting an aluminum alloy with the above-mentioned components and component ratios, electrolytic etching can be achieved by removing Hg oxides, N-Ti particles, etc. in the base metal components using a cartridge filter, etc. This is more desirable because it prevents micro-defects on the surface that will be generated later. The aluminum alloy ingot thus adjusted to a predetermined composition is subjected to predetermined processes such as homogenization treatment, hot rolling, cold rolling, intermediate annealing, cold rolling, and final annealing to give an approximately 0.05% ~0.3 mm thick plate material. Next, the aluminum alloy plate thus obtained is subjected to an electrolytic etching treatment, but since the surface of the plate is contaminated with oil and other deposits,
Prior to electrolytic etching, it is desirable to degrease and wash the aluminum alloy plate according to a conventional method. It is desirable to remove fat by degreasing or the like. After this, usually to remove the natural oxide film on the surface,
Etching treatment is performed by immersing in a caustic soda aqueous solution with a concentration of 1 to 15% at a temperature of 20 to 80°C for 5 seconds to 3 minutes, and then in a nitric acid or sulfuric acid aqueous solution with a concentration of 10 to 20%.
℃ temperature for 5 seconds to 3 minutes to perform neutralization and desmutting after alkali etching. After this treatment, an electrolytic etching treatment is performed, and the electrolytic etching is carried out, for example, in an aqueous solution of hydrochloric acid and/or nitric acid, and when an aqueous solution of hydrochloric acid is used, the concentration is 0.3 to 3% by weight, preferably 0. A range of .5 to 2% by weight is preferred. In addition, chloride, nitrate, amines, phosphate, etc. may be added to this solution as a stabilizer. Electrolytic conditions vary depending on the electrolytic solution used and the desired degree of electrolytic etching, so they cannot be determined unambiguously, but -
In terms of temperature, the temperature is about 10 to 40°C, preferably 20 to 30°C.
℃, the current density (alternating current) is about 20-200^/da",
Preferably 50-150^/dm2, time 2-12
It is 0 seconds. When performing electrolytic etching using such an electrolytic solution, the alternating current used should have an alternating current waveform such as a rectangular wave or trapezoidal wave, which is obtained by alternating positive and negative polarities. However, normal commercial alternating current, ie, sinusoidal single-phase or three-phase alternating current, is sufficient. Aluminum alloy plates that have been electrolytically etched under the above conditions are then desmutted after being washed with water.
The conditions may be those of a conventional method, such as immersion in an aqueous alkali or acid solution at about 10 to 80° C. for about 5 seconds to 3 minutes, and desmutting is carried out in this manner. When the electrolytically etched plate thus obtained is used as a support for a printing plate, it may be subjected to a predetermined post-treatment, such as anodization treatment, according to a conventional method. Specifically, the concentration of sulfuric acid or phosphoric acid, etc. This is carried out by electrolyzing an aqueous solution of 10 to 50% by weight at a Th flow density of 1 to 10^/dm2. Thereafter, if necessary, immersion treatment or the like is performed in an aqueous solution containing hot water, silicate, dichromate, acetate, or a hydrophilic polymer compound for hydrophilization or inactivation. The photosensitizer (photosensitive substance) applied to the aluminum plate obtained in this way is not particularly limited, and six commonly known photosensitizers can be used, such as hydrophilic polymers and diazonium salts. composition, a composition of a quinonediazide compound and an alkali-soluble resin, a polymer whose constituent components are unsaturated carboxylic acids that trimerize upon irradiation with actinic rays, such as cinnamic acid and phenylene diacrylic acid;
Examples include a composition of a binder polymer and a compound that causes a polymerization reaction upon irradiation with actinic rays, or an azide-based photosensitive composition. Then, these photosensitizers are dissolved in a suitable solvent together with various well-known additives, applied to the aluminum material of the present invention, and dried to form a composite adhesive. If an object is layered on this photosensitive lithographic printing plate and exposed and developed according to a conventional method, it has excellent hydrophilicity and water retention, and has extremely high adhesion between the image area made of the photosensitive agent and the aluminum material, and is highly resistant. A printing plate with excellent printing power can be obtained.

[Examples 1 to 8] Aluminum alloy materials having the compositions shown in Table 1 were melted and cast, and an ingot with a thickness of about 300 mm with both sides cut was homogenized, and then hot rolled and cold rolled under normal conditions. Perform rolling, 0
．． A 24 mm thick H1n material is obtained. Next, this H1n material was degreased, then immersed in an 8% sodium hydroxide solution at a temperature of 50°C for 30 seconds to perform alkaline etching, and then washed with water for 10 minutes.
% nitric acid solution at room temperature for 30 seconds, and after desmutting, the substrate is washed again with water, and after this water washing, an electrolytic etching treatment is performed. The conditions for this electrolytic etching treatment are as follows: a 2% aqueous hydrochloric acid solution is used, the temperature is 25°C, the current is 50°C alternating current, the current density is 50/dm'', and the time is 25 seconds. After etching, it is washed with water, immersed in an 8% sodium hydroxide solution at a temperature of 50°C for 5 seconds, then washed again with water, and neutralized by immersed in a 10% nitric acid solution for 30 seconds at room temperature. It is treated and washed with water to obtain an aluminum alloy plate material for printing plates.

[Comparative Examples 1 to 8] Using aluminum alloys having the compositions shown in Table 2, the same procedure as in the example was carried out to obtain aluminum alloy plate materials for printing plates.

【Characteristic】

The mechanical properties (yield strength and fatigue strength) and uniformity of the electrolytic etching bit pattern after alternating current electric field etching treatment were investigated for the aluminum alloy plates for printing plates obtained on each side above. The results are shown in Table 3. . The yield strength was evaluated by a normal tensile test, and the fatigue strength was determined by cutting out a test piece of 20 mm medium and 100 m long chain, fixing one end of this test piece to a jig, and applying tension. The other end was bent at an angle of 90° with the other end bent, and then returned to its original state. This was counted as one time, and the evaluation was made by repeating this and counting the number of times until it broke. For the etching bit pattern, a uniform etching bit pattern is indicated by an O symbol, an uneven etching bit pattern is indicated by an X symbol, and a pattern in between these is indicated by a Δ symbol. Table 3 According to this, the alloy of this example exhibits excellent uniformity of the electrolytic etching pit pattern, which is comparable to that using JIS^1050. -63346 publication or JP-A-61-
It exhibits excellent mechanical strength such as yield strength and fatigue strength that are comparable to those using ^f-M alloys as proposed in Publication No. 26746, and is superior to conventional ones. In contrast, either the uniformity of the electrolytic etching pit pattern or the mechanical strength was sacrificed.
It can be seen that both properties are excellent without sacrificing either property. Patent and patent applicant: Mitsubishi Aluminum Corporation. Agent Uko
Katsumi ′ゝ'c～'・

Claims (1)

[Claims] Si as an impurity is 0.15% by weight or less, Mn is 0.15% by weight or less.
8% by weight or less, Ti 0.05% by weight or less, Cr 0.
3% by weight or less, Cu is 0.1% by weight or less, and the balance is unavoidable impurities and Al.
．． An aluminum alloy for printing plates, characterized in that it contains 0 to 6.0% by weight of Mg, 0.05 to 1.0% by weight of Fe, and 0.05 to 0.5% by weight of Zn.