JPH08943B2 - Aluminum alloy for printing plate - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

TECHNICAL FIELD The present invention relates to an aluminum alloy for a printing plate, particularly an aluminum alloy used for a plate plate for offset printing.

[Prior art and its problems]

When an aluminum alloy for printing plates (hereinafter simply referred to as aluminum) is used for printing, in order to improve water retention and adhesion with a photosensitizer, first, the aluminum surface is subjected to a mechanical method, a chemical method, an electrochemical method. After roughening by any one of the above, or a combination of two or more steps, usually a predetermined post-treatment (anodizing treatment, hydrophilizing treatment, deactivating treatment) is applied to further improve the printing characteristics. ing. And as aluminum, for example, JIS A1050, A
The equivalent of 1100 and A3003 is used. In particular, when the aluminum surface is roughened by an electrochemical method, that is, AC electrolytic etching treatment, Fe, S
A1050 equivalent materials with few impurity elements such as i, Zn, Cu, Mg, and Mn have good surface treatability, which is an important condition in printing plates, and even unevenness (electrolytic etching pit pattern) after roughening. It has been said to be desirable due to its nature. However, in recent years, in order to reduce the material cost, thin wall toughness is improved by improving the yield strength of aluminum, fatigue strength is improved, and isotropic (there is no difference in the fatigue resistance strength between the rolling direction of aluminum and the direction perpendicular to the rolling grain). There has been a demand for an aluminum alloy material for printing plates having improved heat resistance. In order to meet this requirement, various aluminum-magnesium alloy-based aluminums have been disclosed, for example, in JP-A-58-42745 and JP-A-58-42745.
59-133355, JP 60-63346, JP 60-22
It is proposed as disclosed in Japanese Patent No. 0395 and Japanese Patent Laid-Open No. 61-26746. However, compared with the conventional A1050 material, the aluminum that becomes these proposals greatly improves the proof stress and fatigue strength of the aluminum, and the bending resistance during handling, the elongation resistance of the plate during printing, and the Although it is possible to obtain an improvement in thinning, it can be said that the electrolytic etching pit pattern is likely to be non-uniform, the printing characteristics are deteriorated, and a practically preferable one is not yet proposed.

DISCLOSURE OF THE INVENTION

The present inventor, as a result of earnestly promoting research on the above-mentioned problems, the content of Mg is 1.5 to 3.0% by weight, and the content of Cu is
0.02 to 0.05 wt% and content of 85 ≧ Mg / Cu
Content of ≧ 50, and Fe content of 0.05〜
1.0% by weight, 0.15 even if Si was included as an impurity
Up to 0.8% by weight, including Mn, up to 0.8% by weight, including Ti up to 0.05% by weight, including Cr up to 0.3% by weight, including Zn up to 0.03% by weight, An aluminum alloy whose balance consists of unavoidable impurities and Al can provide a uniform electrolytic etching pit pattern that cannot be obtained by a conventional aluminum-magnesium alloy, and thus can improve printing durability and image sharpness, and the like. Improved toughness and fatigue strength are also obtained, and H1n or H2n (n = 2,
4,6,8) material has a proof stress of about 1 even if it is about 0.1 to 0.3 mm thick.
It has been found that when it becomes 5 Kg / mm ² or more, the handling property of the plate can be improved and the elongation of the plate during printing can be prevented. In particular, this aluminum alloy could also achieve the problem of thinning, which was a problem that could not be achieved with JIS A1050 H18 material. For example, when using the aluminum alloy according to the present invention, the thickness of 0.1 mm is 0.24 mm of the JIS A1050 H18 material.
It was comparable to the thick one. Here, the reason for limiting the contents of Mg, Cu and the like as described above is based on the following reason. That is, Mg is an element added for the purpose of improving the strength and fatigue strength, and most of it is present as a solid solution in an aluminum material and exists in a grain boundary or grain as an Al-Mg-based intermetallic compound. It is based on what is done. And Mg
If the content of less than 1.5% by weight, the yield strength after temper annealing to H1n or H2n material is about 15 Kg / in order to ensure the isotropic fatigue resistance in the rolling direction and rolling direction of aluminum and in the vertical direction. It is hard to be over ² mm ² , and conversely, the content of Mg is
If it exceeds 3.0% by weight, the Al-Mg-based intermetallic compound coarsely deposited at grain boundaries or within the grains due to temper annealing is unevenly and deeply etched by electrolytic etching, so that stains on non-image areas, etc. This is because it has been found that they are likely to become defective. Also, Fe is usually Al-Fe-based, Al-Fe-Si-based, or Al-Fe-Mn-Si.
It exists as an intermetallic compound of the system, and most of it exists as a crystallized substance in the matrix after casting, and a part thereof forms a solid solution or precipitates in the matrix. The effect of addition of Fe serves as a starting point of initial pits during electrolytic etching in which strength is improved by making the crystal grains finer or making the structure uniform. When the Fe content is less than 0.05% by weight,
If the content exceeds 1.0% by weight, on the contrary, there is a drawback that the rough surface after electrolytic etching tends to become non-uniform due to the presence of crystallized substances such as coarse Al-Fe system. Because it turned out. Further, Cu is solid-dissolved in the matrix at the added concentration of the present invention. And the content of this Cu, Mg that can achieve the improvement of the mechanical properties of the present invention is 1.5 ~
It was found that by setting the content concentration to 3.0% by weight to 0.02 to 0.05% by weight, it is possible to obtain an etching pit pattern equivalent to that of aluminum currently equivalent to A1050. That is, if the Cu content is less than 0.02 wt%, the rough surface after electrolytic enching becomes non-uniform, and the degree of etching is reduced, and the efficiency is poor. It was found that the rough surface after etching is likely to be non-uniform and that large pits due to overetching locally exist. When 1.5 to 3% by weight of Mg is contained in aluminum, an oxide film on the surface of aluminum (usually Al
₂ O ₃ ) becomes dense due to the presence of Mg element in the film, and when Cu is not added, it is difficult to be etched during the predetermined electrolytic etching, and unetched portions are likely to exist in the matrix portion. However, the addition of Cu reduces the denseness of the oxide film, resulting in an etching pattern equivalent to that of pure aluminum equivalent to JIS A1050.
On the contrary, if Cu is contained more than necessary, the oxide film becomes brittle and the matrix is easily etched excessively.
It has been found that it is difficult to obtain a uniform etching pattern that is sequentially etched around the initial pit starting point represented by an intermetallic compound such as -Fe system. As a result of further research based on this finding, the Cu content was Mg
It was found to be closely related to the content. That is, the relationship between the Mg content weight and the Cu content weight is 85 ≧
By satisfying the condition of Mg content weight / Cu content weight ≧ 50, a more uniform electrolytic etching pit pattern was obtained. As another impurity element, Si exists as an Al-Fe-Si-based or Al-Fe-Mn-Si-based intermetallic compound (crystallized substance) that acts as a starting point of the initial pit, but basically it exists. , Mg ₂ Si produced by precipitation due to the bond with the solid solution Mg in the Al-Mg alloy may be contained at such a concentration that does not exist. Therefore, Si should not be contained in excess of 0.15% by weight. Also, Mn exists as an Al-Fe-Mn-based intermetallic compound and partly exists as a solid solution, but basically, it works as an improvement in material strength and a starting point of initial pits. is there. Therefore, it does not matter as long as Mn / Fe in the Al-Fe-Mn-based or Al-Fe-Mn-Si-based intermetallic compound is contained to the extent that it does not increase. From such a viewpoint, Mn should not be contained in excess of 0.8% by weight. Further, Ti is added for refining the ingot structure, and excessive addition causes the formation of linear microdefects due to the presence of the Al-Ti-based intermetallic compound, so its content is It should not exceed 0.05% by weight. Also, Cr is an element that causes uniform precipitation of intermetallic compounds such as Al-Fe-based and Al-Mg-based, but if present in excess of 0.3% by weight, Al-Cr-based intermetallic compounds are newly formed. However, the content should be 0.3% by weight or less, since it tends to impede the uniformity of the electrolytic etching pit pattern. Further, Zn, if present in excess of 0.03% by weight, tends to cause nonuniformity in the pit pattern after electrolytic etching,
Must be less than 0.03% by weight. Incidentally, when casting the aluminum alloy of the content components and component ratios described above, Mg oxide, Al-Ti-based particles and the like in the metal component is removed by a cartridge filter or the like, after electrolytic etching It is more desirable to prevent microscopic defects in the surface that are created. Homogenization treatment of the aluminum alloy ingot adjusted to a predetermined composition in this way, hot rolling, cold rolling, intermediate annealing, cold rolling, through a predetermined step such as final annealing about 0.1 ~ 0.3 Use a plate material with a thickness of mm. Next, the plate material of the aluminum alloy thus obtained is subjected to electrolytic etching treatment. Since the surface of the plate material is contaminated with oil and other deposits, the aluminum alloy prior to the electrolytic etching. It is desirable to degrease and clean the plate material according to a conventional method.For example, degreasing with solvent such as trichlene or freon, degreasing with a weak alkaline detergent aqueous solution, degreasing with H ₂ SO ₄ aqueous solution having a concentration of 1 to 10%, etc. Is desirable. After this, usually, in order to remove the natural oxide film on the surface, it is immersed in an aqueous 1-15% caustic soda solution at a temperature of 20-80 ° C for 5 seconds-3 minutes for etching treatment, and then the concentration is increased.
Immersion in a 10 to 20% nitric acid or sulfuric acid aqueous solution at a temperature of 10 to 50 ° C. for 5 seconds to 3 minutes is carried out to carry out neutralization and desmutting after alkali etching. After this treatment, an electrolytic etching treatment is carried out. The electrolytic etching is conducted, for example, in an aqueous solution of hydrochloric acid and / or nitric acid. When an aqueous hydrochloric acid solution is used, the concentration is 0.3 to 3% by weight, preferably 0.5 to 2 A weight% range is preferred. Incidentally, chlorides, nitrates, amines, phosphates and the like may be added to the electrolytic solution as stabilizers. The electrolysis conditions differ depending on the electrolytic solution used and the desired degree of electrolytic etching, so it cannot be uniquely determined.
Generally, at a temperature of about 10-40 ° C, preferably 20-30 ° C,
Current density (alternating current) is about 20-200 A / dm ² , preferably 50-15
At 0 A / dm ² , the time is ² to 120 seconds. When performing an electrolytic etching process using such an electrolytic solution, the alternating current used has a waveform obtained by alternating positive and negative polarities, such as a rectangular waveform or a trapezoidal waveform. Ordinary commercial AC, ie sinusoidal single-phase or three-phase AC, is sufficient. The aluminum alloy plate material electrolytically etched under the above-mentioned conditions is subsequently washed with water and desmutted. The conditions may be those of a conventional method, such as about 5 seconds in an alkali or acid aqueous solution at about 10 to 80 ° C. What is necessary is that it is soaked for about 3 minutes, and thereby desmutting is performed. When the electrolytic enching plate thus obtained is used as a support for a printing plate, it may be subjected to a predetermined post-treatment, for example, an anodic oxidation treatment, according to a conventional method. 10-50% by weight aqueous solution with a current density of 1
It is carried out by electrolysis at ~ 10 A / dm ² . After this, if necessary, for hydrophilicity or inactivation,
A soaking process or the like is carried out in an aqueous solution containing hot water, silicate, dichromate, acetate, and hydrophilic polymer. The photosensitizer (photosensitive substance) applied to the aluminum plate thus obtained is not particularly limited, and generally known ones can be applied, for example, a composition comprising a hydrophilic polymer and a diazonium salt. Substance, a composition of a quinonediazide compound and an alkali-soluble resin, an unsaturated carboxylic acid that dimerizes by irradiation with actinic rays, for example, cinnamic acid,
Examples thereof include a polymer having phenylenediacrylic acid as a constituent component thereof, a composition of a compound which causes a polymerization reaction upon irradiation with an actinic ray and a binder polymer, 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 bond. When a material to be copied is superposed on this photosensitive lithographic printing plate and exposed and developed according to a conventional method, it is excellent in hydrophilicity and water retention, and the adhesiveness between the image part made of the photosensitizer and the aluminum material is extremely large, and It is possible to obtain a printing plate having excellent printing ability.

Examples 1 to 8 Aluminum alloy materials having the compositions shown in Table 1 were melt-cast,
Homogeneous treatment of the ingot having a thickness of about 300 mm, both sides of which have been chamfered, then hot-rolled and cold-rolled under normal conditions, 0.
Obtain 24mm thick H1n material. Next, this H1n material is degreased, then immersed in an 8% sodium hydroxide solution at a temperature of 50 ° C for 30 seconds for alkali etching, then washed with water and then washed with a 10% nitric acid solution at room temperature. Desmut is carried out by immersing under water for 30 seconds, and after desmutting, it is washed again with water, followed by electrolytic etching treatment. The conditions of this electrolytic etching treatment were a 2% hydrochloric acid aqueous solution, a temperature of 25 ° C., an alternating current of 50 Hz, a current density of 50 A / dm ² , and a time of 25 seconds. After electrolytic etching treatment, rinse with water, immerse in 8% sodium hydroxide solution at a temperature of 50 ° C for 5 seconds, then rinse with water again, and immerse in 10% nitric acid solution at room temperature for 30 seconds. An aluminum alloy plate material for a printing plate which has been subjected to a Japanese treatment and washed with water is obtained.

Comparative Examples 1 to 8 Aluminum alloy plate materials for printing plates are obtained by using aluminum alloys having the compositions shown in Table 2 in the same manner as in the examples.

【Characteristic】

The aluminum alloy plate material for printing plate obtained in each of the above examples was examined for mechanical properties (proof stress and fatigue strength) and uniformity of electrolytic etching pit pattern after AC electric field etching treatment. The results are shown in Table 3. . The proof stress was evaluated by a normal tensile test, and the fatigue strength was cut out from a test piece with a width of 20 mm and a length of 100 mm, and one end of this test piece was fixed to a jig and tension was applied. The other end is bent at an angle of 90 ° and returned to its original state, counted once, and repeated to count the number of times until breakage. Also, electrolytic etching As for the pit pattern, a uniform pattern is indicated by a circle, an uneven pattern is indicated by a cross, and an intermediate pattern is indicated by a triangle. According to this, the alloy of the present example shows a feature excellent in the uniformity of the electrolytic etching pit pattern, which is not inferior to the case of using JIS A1050, and further, JP-A-60-63346. It has excellent mechanical strength such as proof stress and fatigue strength, which is not inferior to the case of using an Al-Mg alloy as proposed in Japanese Laid-Open Patent Publication No. 61-26746. However, it can be understood that, while the conventional one sacrifices either the uniformity of the electrolytic etching pit pattern or the mechanical strength, both are excellent without sacrificing any of the characteristics.

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Claims (1)

[Claims] 1. The content of Mg is 1.5 to 3.0% by weight, the content of Cu is 0.02 to 0.05% by weight, and the content of 85 ≧ Mg / C.
u content ≧ 50 is satisfied, and Fe content is 0.05
~ 1.0% by weight, 0.15% by weight Si as impurities, 0.8% by weight Mn, 0.05% by weight Ti, 0.3% by weight Cr Up to wt%, 0.0 including Zn
Aluminum alloy for printing plates, which is up to 3% by weight, the balance being unavoidable impurities and Al.