JP5149582B2 - Aluminum alloy plate for lithographic printing plate and method for producing the same - Google Patents

Description

  The present invention relates to an aluminum alloy plate for a lithographic printing plate, particularly to an aluminum alloy plate for a lithographic printing plate suitable for roughening by an electrochemical etching treatment and a method for producing the same.

  In general, an aluminum alloy plate is used as a support for lithographic printing plates (including offset printing plates), and the support is rough from the viewpoint of improving the adhesion of the photosensitive film and improving the water retention of the non-image area. In recent years, the surface of the aluminum alloy plate for the support is roughened by electrochemical etching because of its excellent plate-making suitability and printing performance, and continuous processing with coil materials. The approach to surface is developing rapidly.

As an aluminum alloy plate capable of obtaining a relatively uniform electrolytic surface roughening by electrochemical etching treatment, a material equivalent to A1050 (aluminum purity 99.5%) or a material added with a small amount of alloy components based on A1050 equivalent material is used. These aluminum alloys for lithographic printing plates are applied with homogenization treatment and hot rolling, and then subjected to intermediate annealing and recrystallized structure And then cold rolling, or cold rolling, and performing an intermediate annealing process in the middle of cold rolling to form a recrystallized structure on the surface of the rolled plate, and then performing secondary cold rolling to perform electrochemical The generation of pits during the general etching process is made uniform, and the occurrence of streaks when processing as a printing plate is prevented.
JP-A-8-337835 JP 2000-108534 A

  For the purpose of obtaining an aluminum alloy material for a lithographic printing plate capable of achieving uniform and fine pit formation in electrolytic treatment by improving electrolytic characteristics, the inventors have used a conventionally proposed material as a base for component composition. As a result of re-examination, Mg and Pb were included, and the Mg and Pb concentrations in the surface layer portion were increased by a specific magnification as compared with the Mg and Pb concentrations in the deeper region than the surface layer portion, and the precipitation of Mg in the matrix was suppressed. It has been found that the material is effective and that the control of the hot rough rolling start temperature and the hot finish rolling end temperature is important in order to produce an aluminum alloy sheet having such a texture.

  The present invention has been made as a result of further tests and studies based on the above knowledge, and the purpose thereof is to obtain an appropriate Mg concentration and Pb concentration in the surface layer portion, and to achieve electrochemical properties. An object of the present invention is to provide an aluminum alloy plate for a lithographic printing plate that has uniform pit generation during etching and does not cause streak when processing as a printing plate and a method for producing the same.

  In order to achieve the above object, an aluminum alloy plate for a lithographic printing plate according to claim 1 has Mg: 0.1 to 0.5%, Si: 0.03 to 0.15%, Fe: 0.2 to 0 .6%, Ti: 0.005 to 0.05%, Pb: 2 to 30 ppm, having a composition composed of the balance aluminum and inevitable impurities, and average recrystallization in the direction perpendicular to the rolling direction of the surface layer portion The particle diameter is 50 μm or less, the Mg concentration in the surface layer portion from the surface to a depth of 0.2 μm is 1.2 to 10 times the average Mg concentration, and the Pb concentration in the surface layer portion from the surface to a depth of 0.2 μm is 3 It is characterized in that the amount of Mg deposited in the matrix is 0.03% or less by ˜25 times.

  An aluminum alloy plate for a lithographic printing plate according to claim 2 is characterized in that, in claim 1, Cu: 0.05% or less is contained.

  The method for producing an aluminum alloy plate for a lithographic printing plate according to claim 3 comprises homogenizing the aluminum alloy ingot according to claim 1 or 2 in a temperature range of 500 to 610 ° C. for 1 hour or more, and then setting a starting temperature. Hot rough rolling is performed at 350 to 450 ° C., then hot finish rolling is performed, the hot finish rolling is finished at a temperature of 300 ° C. or lower, and then subjected to intermediate annealing at a temperature of 400 ° C. or higher, and processed. Cold rolling at a degree of 80% or more is performed.

  The method for producing an aluminum alloy plate for a lithographic printing plate according to claim 4 comprises homogenizing the aluminum alloy ingot according to claim 1 or 2 in a temperature range of 500 to 610 ° C. for 1 hour or more, and then setting a starting temperature. Hot rough rolling is performed at 350 to 450 ° C., then hot finish rolling is performed, the hot finish rolling is finished at a temperature of 300 ° C. or less, and then cold rolling is performed. The intermediate annealing is performed at a temperature of 400 ° C. or higher, and the total degree of cold rolling is 80% or more.

  According to the present invention, moderate Mg and Pb enrichment in the surface layer portion can be obtained, the generation of pits during the electrochemical etching process is uniform, and the occurrence of streaks when processing as a printing plate is performed. An aluminum alloy plate for lithographic printing plates and a method for producing the same are provided.

  Explaining the significance and reason for limitation of the components contained in the aluminum alloy plate for lithographic printing plates of the present invention, Mg secures the strength of the printing plate and forms a simple intermetallic compound with Si. Suppression of precipitation as Si is suppressed. If the Mg content is less than 0.1%, the effect of improving the strength is small. The Mg-Si intermetallic compound promotes the uneven distribution of pits in the crystal grains of a specific orientation (Cube orientation) during electrolysis (pit coarsening and unetched area increase), so it precipitates in the matrix. The amount of Mg is preferably 0.03% or less, and if it exceeds 0.03%, the number of non-uniform pits increases and appearance defects such as uneven surface quality become more conspicuous. If the Mg content exceeds 0.5%, the amount of Mg deposited as an Mg—Si intermetallic compound in the matrix exceeds 0.03%, and the pits during the electrolytic treatment tend to be uneven. A more preferable content range of Mg is 0.2 to 0.5%.

  In an aluminum alloy containing Mg, Mg concentrates on the surface layer part by heat treatment such as heating during homogenization treatment, hot rolling, and intermediate annealing, so that Mg oxide (MgO-based oxide) is mainly used. An oxide film is easily formed. Since this oxide film is active and porous, the wettability with the treatment liquid is improved in the electrolytic surface-roughening treatment, and coarsening is promoted, but pits are not formed. It tends to be uniform. For this reason, it is desirable that the Mg concentration in the surface layer portion from the surface to a depth of 0.2 μm is 1.2 to 10 times the average Mg concentration. If it exceeds twice, the pit form becomes non-uniform.

  Fe produces an Al—Fe-based intermetallic compound, and coexists with Si to produce an Al—Fe—Si-based intermetallic compound. By uniform dispersion of these compounds, these compounds are Thus, the formation of pits is made uniform and the pits are finely distributed during the electrolytic treatment. The preferable content of Fe is in the range of 0.2 to 0.6%, and if it is less than 0.2%, the distribution of the compound becomes nonuniform, and the formation of pits during the electrolytic treatment becomes nonuniform. If it exceeds 0.6%, a coarse compound is produced, and the uniformity of the roughened structure is lowered.

  Si coexists with Fe to produce an Al—Fe—Si intermetallic compound, and the dispersion of the compound makes these compounds the starting point of pit generation and uniform pit formation during electrolytic treatment. Is finely distributed. The preferable content of Si is in the range of 0.03 to 0.15%, and if it is less than 0.03%, the distribution of the compound becomes nonuniform, and the formation of pits during the electrolytic treatment becomes nonuniform. If it exceeds 0.15%, a coarse compound is produced, and precipitation of simple Si is likely to occur, and the uniformity of the roughened structure is lowered.

  Ti refines the ingot structure and refines the crystal grains. As a result, pit formation during the electrolytic treatment is made uniform, and streaks are prevented when processing as a printing plate is performed. The preferable content of Ti is in the range of 0.005 to 0.05%. When the content is less than 0.005%, the effect is small. When the content exceeds 0.05%, a coarse Al-Ti compound is formed. As a result, the roughened structure tends to be non-uniform. In addition, when adding B with Ti for refinement | miniaturization of an ingot structure | tissue, it is preferable to contain Ti in 0.01% or less of range.

  By concentrating Pb in the surface layer portion, the pits at the time of electrolytic treatment are refined and function to improve the uniformity of pit formation, and a desired pit pattern can be obtained. The preferable content of Pb is in the range of 2 to 30 ppm. When the content is less than 2 ppm, the effect is small, and when the content exceeds 30 ppm, the roughened structure tends to be uneven. Pb concentrated in the surface layer functions to improve the non-uniformity of the roughened structure and suppress activation by Mg oxide. The concentration of Pb is preferably such that the Pb concentration in the surface layer from the surface to a depth of 0.2 μm is 3 to 25 times the average Pb concentration, and if less than 3 times, the effect of suppressing the influence of Mg oxide is sufficient. If it exceeds 25 times, surface dissolution tends to occur.

  Cu is easily dissolved in aluminum and has an effect of refining pits in a content range of 0.05% or less. If the content exceeds 0.05%, the pits during the electrolytic treatment tend to be coarse and non-uniform.

  The production of an aluminum alloy plate for a lithographic printing plate according to the present invention is performed by ingot-making an ingot of an aluminum alloy having the above component composition by continuous casting or the like, and after homogenizing the obtained ingot, hot rolling, intermediate Annealing, cold rolling, or hot rolling is followed by cold rolling, intermediate annealing in the middle of cold rolling, and secondary cold rolling.

  First, the surface of the rolled surface of the ingot of the aluminum alloy having the above composition is chamfered to remove a non-uniform structure causing streaks, and then homogenized for 1 hour or more in a temperature range of 500 to 610 ° C. Process. By this homogenization treatment, Fe and Si dissolved in supersaturation are uniformly deposited, and the etching pits formed during the electrolytic treatment become fine circles, and the printing durability is improved. Moreover, since the Mg—Si intermetallic compound produced at the time of casting dissolves and uneven distribution of pits does not occur, the occurrence of uneven surface quality is suppressed and the appearance is not impaired. If the homogenization temperature is less than 500 ° C., the precipitation of Fe and Si proceeds excessively and the pit pattern tends to be non-uniform. When the homogenization treatment is performed at a temperature exceeding 610 ° C., the amount of Fe dissolved increases, and as a result, fine precipitates that are the starting point of pit generation are reduced. If the holding time of the homogenization treatment is less than 1 hr, the precipitation of Fe and Si is insufficient and the pit pattern tends to be non-uniform.

  Hot rolling is usually performed in a hot rolling line after hot rough rolling in a rough rolling stand, and then the rolled material is transferred to a finishing rolling stand and hot finishing rolling is performed in a finishing rolling stand. In this case, in this invention, hot rough rolling is started at 350 to 450 ° C., then hot finish rolling is performed, and hot finish rolling is performed at 300 ° C. End with: In this hot rolling, the Mg concentration in the surface layer portion from the surface to a depth of 0.2 μm is 1.2 to 10 times the average Mg concentration, and the Pb concentration in the surface layer portion from the surface to a depth of 0.2 μm is 3 times the average Pb concentration. A concentration of Mg and Pb that is up to 25 times can be obtained. In addition, it is possible to suppress the precipitation of Mg in the matrix and to reduce the amount of precipitated Mg to 0.03% or less, thereby obtaining a roughened structure preferable in the electrolytic treatment.

  If the starting temperature of hot rough rolling is less than 350 ° C., the deformation resistance of the material is large and the number of rolling passes is increased, thereby reducing productivity. If the temperature exceeds 450 ° C., it becomes difficult to suppress the precipitation of Mg. Following hot rough rolling, hot finish rolling is performed, the hot finish rolling is finished at a temperature of 300 ° C. or lower, and wound on a coil. When the finishing temperature of hot finish rolling exceeds 300 ° C., it becomes difficult to suppress the precipitation of Mg.

  After hot rolling under the above conditions, after intermediate annealing at a temperature of 400 ° C. or higher, and then cold rolling with a workability of 80% or higher, or after hot rolling under the above conditions The primary cold rolling is performed, the intermediate annealing is performed at a temperature of 400 ° C. or higher, and then the secondary cold rolling is performed. In the final rolled material, the average recrystallized grain size in the direction perpendicular to the rolling direction of the rolled material of the surface layer portion is 50 μm or less, and further the Mg—Si intermetallic compound precipitated in the matrix is solid-solved, and the printing plate It is possible to prevent uneven surface quality.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects of the present invention. These examples show one preferred embodiment of the present invention, and the present invention is not limited thereto.

Example 1 and Comparative Example 1
Aluminum alloy having the composition shown in Table 1 is melted and cast, and the rolled surface of the obtained ingot is chamfered by 5 mm / one side to a thickness of 500 mm, and each ingot is homogenized under the conditions shown in Table 2. Processing and hot rolling were performed, and the sheet thickness was 3 mm by hot finish rolling, and the product was wound on a coil. After hot rolling, intermediate annealing was performed at a temperature of 450 ° C., and then cold rolling was performed to obtain a cold rolled material having a plate thickness of 0.3 mm. In Tables 1 and 2, those outside the conditions of the present invention are underlined.

  Using the cold rolled material as the test material, the average recrystallized grain size in the direction perpendicular to the rolling direction of the surface layer portion of the rolled material and the amount of Mg precipitated in the matrix were measured by the following method, and Mg in the surface layer portion was measured. And the concentration of Pb were evaluated. The results are shown in Table 3.

  Measurement of the average recrystallized grain size: After degreasing and cleaning the surface of the test material, mirror polishing, anodizing with Parker's solution, observing crystal grains in the polarization mode of an optical microscope, and in the direction perpendicular to the rolling direction The crystal grain size was determined by the intercept method.

  Measurement of the amount of Mg deposited in the matrix: The amount of Mg deposited in the matrix was determined by examining the amount of Mg in the total intermetallic compound by the phenol residue analysis method as shown in FIG.

  Concentration of Mg and Pb in the surface layer part: Comparison of Mg and Pb concentration in the surface layer part and internal Mg and Pb concentration is based on depth analysis (depth profile measurement) of Mg and Pb by secondary ion mass spectrometry (SIMS). It was determined by the ratio of the count number of the highest Mg and Pb concentration on the surface to the count number from the inner aluminum substrate.

  Moreover, about the test material (cold-rolled material), the presence or absence of surface quality unevenness and streaks was observed by the following methods, and the evaluation of the occurrence of unetched portions and the evaluation of etch pit uniformity were performed. The results are shown in Table 4.

Degrease the cold rolled material (solution: 5% sodium hydroxide, temperature: 60 ° C., time: 10 seconds) -neutralization treatment (solution: 10% nitric acid, temperature: 20 ° C., time: 30 seconds) -AC electrolysis Roughening treatment (solution: 2.0% hydrochloric acid, temperature: 25 ° C., frequency: 50 Hz, current density: 60 A / dm ² , time: 20 seconds) -desmut treatment (solution: 5% sodium hydroxide, temperature: 60 (° C., time: 5 seconds) -anodic oxidation treatment (solution: 30% sulfuric acid-temperature: 20 ° C., time: 60 seconds), washed with water, dried, cut into a certain size to obtain a test piece.

Each test piece was observed for surface unevenness and streak. In addition, using a scanning electron microscope (SEM), the surface was observed at a magnification of 500 times, and a photograph was taken so that the area of the visual field was 0.04 mm ^2. Pit uniformity was evaluated.

Observation of presence / absence of surface quality unevenness: The surface of the test piece where surface unevenness was visually observed was evaluated as poor (x), and the surface where surface quality unevenness was not observed was evaluated as good (◯).
Observation of presence / absence of streak: Evaluation was made that a streak was visually observed on the surface of the test piece as defective (X), and a streak was not observed as good (O).
Evaluation of occurrence of unetched (unetched) part: An unetched part exceeding 20% was judged as defective (x), and a part not exceeding 20% was judged good (◯).
Evaluation of uniformity of etch pits (pits): Large pits with an equivalent circle diameter exceeding 5 μm are defective (×) when the area ratio exceeds 10% of all pits, and those with 10% or less are good (◯) It was.

  As can be seen from Table 4, all of the test materials 1 to 4 according to the present invention do not cause uneven patterns and streaks, have excellent etching properties after electrolytic treatment, and have uniform etching pits formed on the entire surface. .

  On the other hand, since the test material 5 has a small amount of Pb, sufficient surface roughening cannot be obtained in the electrolytic treatment, and the test material 6 has a large amount of Pb. Decreased. Since the test material 7 had a large amount of Mg, the amount of Mg precipitated in the matrix increased, resulting in uneven surface quality.

  Since the test material 8 has a high start temperature for hot rough rolling and the test material 9 has a high end temperature for hot finish rolling, neither of the predetermined Mg and Pb concentrations can be obtained, and the precipitation of Mg As a result, the pit pattern during the electrolytic treatment became non-uniform.

It is a flowchart which shows the measuring method of the amount of Mg which has precipitated in a matrix.

Claims (4)

Mg: 0.1-0.5% (mass%, the same applies hereinafter), Si: 0.03-0.15%, Fe: 0.2-0.6%, Ti: 0.005-0.05% , Pb: 2 to 30 ppm, having a composition composed of the balance aluminum and inevitable impurities, and having an average recrystallized grain size in the direction perpendicular to the rolling direction of the surface layer part of 50 μm or less, from the surface to a depth of 0.2 μm The Mg concentration in the surface layer portion is 1.2 to 10 times the average Mg concentration, the Pb concentration in the surface layer portion from the surface to a depth of 0.2 μm is 3 to 25 times the average Pb concentration, and the amount of Mg deposited in the matrix is An aluminum alloy plate for a lithographic printing plate, characterized by being 0.03% or less. 2. The aluminum alloy plate for a lithographic printing plate according to claim 1, comprising Cu: 0.05% or less (excluding 0%, the same shall apply hereinafter). The ingot of the aluminum alloy according to claim 1 or 2 is homogenized for 1 hour or more in a temperature range of 500 to 610 ° C, followed by hot rough rolling at a start temperature of 350 to 450 ° C, followed by heat The lithographic printing plate is characterized by performing hot finish rolling, finishing hot finish rolling at a temperature of 300 ° C. or lower, then performing intermediate annealing at a temperature of 400 ° C. or higher, and performing cold rolling with a workability of 80% or higher. Manufacturing method of aluminum alloy plate for printing plate. The ingot of the aluminum alloy according to claim 1 or 2 is homogenized for 1 hour or more in a temperature range of 500 to 610 ° C, followed by hot rough rolling at a start temperature of 350 to 450 ° C, followed by heat Perform hot finish rolling, finish hot finish rolling at a temperature of 300 ° C. or lower, then perform cold rolling, perform intermediate annealing at a temperature of 400 ° C. or higher during the cold rolling, and total of cold rolling A method for producing an aluminum alloy plate for a lithographic printing plate, wherein the processing degree is 80% or more.

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