JP5210103B2 - 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, and more particularly to an aluminum alloy plate for a lithographic printing plate that is suitable for roughening by electrochemical etching and has excellent productivity during production, 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. Applied, for example, a material containing a small amount of Pb (see Patent Document 1), and a small amount of Cu, so that the Cu concentration in the surface layer portion is higher than the Cu concentration in a region deeper than the surface layer portion. A material (see Patent Document 2) has been proposed.

  Conventionally, these aluminum alloy materials for lithographic printing plates are homogenized, hot-rolled ingots, cold-rolled, and subjected to intermediate annealing in the middle of cold-rolling to recrystallize the rolled plate surface. After forming the structure, by performing secondary cold rolling, the generation of pits during the electrochemical etching process is made uniform, and the occurrence of streaks when the process as a printing plate is performed is prevented. A decrease in productivity and an increase in manufacturing costs due to annealing are inevitable, and improvements are desired.

As a method of obtaining an aluminum alloy plate for lithographic printing plates by performing cold rolling without performing annealing treatment after hot rolling, in hot rolling consisting of hot rough rolling and hot finish rolling, The starting temperature is set to 450 ° C. or more, rolling is performed at a rolling speed of 50 m / min or more from the starting pass, a reduction amount of 30 mm or more, or a one-pass reduction ratio of 30%, and the end temperature of hot rough rolling is set to 300 to A method for controlling recrystallization of the plate surface by setting the temperature to 370 ° C. and then setting the end temperature of hot finish rolling to be 280 ° C. or higher and winding the coil as a coil has been proposed (see Patent Document 3).
JP-A-8-337835 JP 2000-108534 A Japanese Patent Laid-Open No. 11-335761

  In order to omit intermediate annealing, it is necessary to recrystallize at the stage of winding as a coil after completion of hot finish rolling. It is important that the recrystallized grain size does not become coarse and is fine and uniform as in the material subjected to the intermediate annealing, and that the degree of recrystallization of the plate surface layer part is uniform.

  The inventors have renewed the component composition based on the conventionally proposed materials 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. As a result of examining and examining the manufacturing method omitting the intermediate annealing, Mg and Pb were included, and the Mg and Pb concentrations in the surface layer portion were compared with the Mg and Pb concentrations in the deeper region than the surface layer portion. In order to produce an aluminum alloy sheet having such a textured property without intermediate annealing, a material with an increased specific magnification is effective. It was found that holding the material until rolling and controlling the finishing temperature of hot finish rolling are important.

  The present invention has been made as a result of further tests and examinations based on the above knowledge, and the purpose of the present invention is to restore the surface layer portion of the plate at the stage of winding as a coil after the hot finish rolling. The degree of crystal is uniform, the recrystallized grains are fine and uniform, can be cold-rolled to the final thickness without intermediate annealing after hot rolling, and moderate Mg and Pb in the surface layer part Aluminum alloy plate for lithographic printing plates with high concentration, uniform pit generation during electrochemical etching, and no streak when processed as a printing plate, and improved productivity and manufacturing An object of the present invention is to provide a method for producing an aluminum alloy plate for a lithographic printing plate that can reduce the cost.

  In order to achieve the above object, an aluminum alloy plate for a lithographic printing plate according to claim 1 is composed of Si: 0.03-0.15%, Fe: 0.2-0.7%, Mg: 0.05-0. .15%, 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 a direction perpendicular to the rolling direction of the surface layer portion The particle size is 50 μm or less, the Mg concentration in the surface layer portion from the surface to a depth of 0.2 μm is 10 to 40 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 100 to 400 of the average Pb concentration. The amount of Mg precipitated in the matrix is 0.03% or less.

  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.

  An aluminum alloy plate for a lithographic printing plate according to claim 3 is characterized in that in claim 1 or 2, it has a tensile strength of 180 MPa or more.

  A method for producing an aluminum alloy plate for a lithographic printing plate according to claim 4 is the starting temperature after 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. The hot rough rolling is performed at 400 to 520 ° C. and the end temperature is 400 ° C. or higher. After the hot rough rolling, the hot rough rolled material is held for 60 to 300 seconds before the start of hot finish rolling. The surface of the hot rough rolled material is recrystallized, then hot finish rolling is performed, the hot finish rolling is finished at a temperature of 330 ° C. or higher, and cold rolling with a workability of 80% or more is performed. To do.

  According to the present invention, after completion of hot finish rolling, at the stage of winding as a coil, the degree of recrystallization of the plate surface layer portion is uniform, the recrystallized grains are fine and uniform, and intermediate annealing after hot rolling is performed. Can be cold-rolled to the final thickness without carrying out the process, a moderate concentration of Mg and Pb in the surface layer can be obtained, and the generation of pits during the electrochemical etching process is uniform, as a printing plate There are provided an aluminum alloy plate for a lithographic printing plate in which streak is not generated when the treatment is performed, and a method for producing an aluminum alloy plate for a lithographic printing plate capable of improving productivity and reducing manufacturing costs.

  The significance of the components contained in the aluminum alloy plate for a lithographic printing plate of the present invention and the reason for limitation will be explained. Fe forms an Al—Fe intermetallic compound and coexists with Si between Al—Fe—Si based metals. The compounds are formed and the recrystallization structure is refined by the dispersion of these compounds, and these compounds become the starting point of pit generation to make the formation of pits uniform during electrolytic treatment and to distribute the pits finely. The preferable content of Fe is in the range of 0.2 to 0.7%, 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 0.7%, 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 refines the recrystallized structure, and these compounds serve as starting points for pit generation during the electrolytic treatment. Uniform formation of pits and fine distribution of pits. 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.

  Mg secures the strength of the printing plate and forms Si and a Mg—Si intermetallic compound to suppress precipitation as elemental Si. The preferable Mg content is in the range of 0.05 to 0.15%, and if it is less than 0.05%, 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 0.15%, 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.

  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 of the surface layer portion from the surface to a depth of 0.2 μm is 10 to 40 times the average Mg concentration, and if it is less than 10 times, the roughening promoting effect cannot be obtained, and if it exceeds 40 times The pit form is uneven.

  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 portion from the surface to a depth of 0.2 μm is 100 to 400 times the average Pb concentration, and if it is less than 100 times, the effect of suppressing the influence of Mg oxide is sufficient. If it exceeds 400 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 involves ingot-making an ingot of an aluminum alloy having the above component composition by continuous casting or the like, and homogenizing the obtained ingot, followed by hot rolling, Although it is performed by hot rolling, the most characteristic point is that in the hot rolling process consisting of hot rough rolling and hot finish rolling, the rolling start temperature, the rolling end temperature, until the transition from rough rolling to finish rolling. By specifying the holding time and controlling the recrystallized grains when wound as a coil after finish rolling, a plate material of a predetermined thickness only by cold rolling without performing intermediate annealing after hot finish rolling It is in the point to.

  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 treatment temperature is less than 500 ° C., the precipitation of Fe and Si proceeds excessively, and the solid solution of the Mg—Si intermetallic compound is insufficient, so that 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, the hot rough rolling starts at 400 to 520 ° C., ends at a temperature of 400 ° C. or higher, and finishes the hot rough rolling. Before moving to the finishing stand and starting hot finish rolling, the hot rough rolled material is held for 60 to 300 seconds to recrystallize the surface of the hot rough rolled material. In addition, after completion of the hot rough rolling, the Mg concentration in the surface layer portion from the surface to the depth of 0.2 μm becomes 10 to 40 times the average Mg concentration by holding before the hot finish rolling, and the surface To 0.2 μm depth, the Pb concentration at which the Pb concentration in the surface layer part is 100 to 400 times the average Pb concentration can be obtained. The reduction amount in the hot rough rolling is desirably a reduction amount that ends with a thickness of 30 mm or more.

  If the starting temperature of hot rough rolling is less than 400 ° C., the deformation resistance of the material is large, and the number of rolling passes is increased, thereby reducing productivity. Further, since precipitation of the Mg—Si intermetallic compound is likely to proceed, pits are unevenly distributed, resulting in uneven surface quality and a loss of appearance. When the temperature exceeds 520 ° C., coarse recrystallized grains are generated during rolling, and a streak-like non-uniform structure tends to be formed. If the end temperature of hot rough rolling is less than 400 ° C., recrystallization due to holding after the end of hot rough rolling becomes insufficient, and it becomes difficult to obtain a uniform surface layer structure, and it is difficult to obtain the concentration of Mg and Pb. . Further, if the holding time after the hot rough rolling is completed and before the hot finish rolling is started is less than 60 seconds, the recrystallization is insufficient and it is difficult to obtain a uniform surface structure. Moreover, it becomes difficult to obtain the enrichment of Mg and Pb. When the time exceeding 300 seconds is maintained, the recrystallized grains grow to form partially coarse recrystallized grains, and it becomes difficult to obtain fine recrystallized grains at the end of hot rolling, and the concentration of Mg and Pb The degree becomes difficult to obtain. Further, since the precipitation of the Mg—Si intermetallic compound is facilitated by holding for a long time, the pits are unevenly distributed to cause uneven surface quality and impair the appearance.

  Next, hot finish rolling is performed, and the hot finish rolling is finished at a temperature of 330 ° C. or higher and wound as a coil. If the start temperature of hot finish rolling is less than 400 ° C., the end temperature of this hot finish rolling will be low, resulting in insufficient recrystallization and streaks. When the finish temperature of hot finish rolling is less than 330 ° C., recrystallization occurs only partially, causing streaks. The end temperature of hot finish rolling is preferably 370 ° C. or lower.

  After performing the above hot rolling, the average recrystallized grain size in the direction orthogonal to the rolling direction of the surface layer portion of the hot finish rolled material can be reduced to 50 μm or less by winding up as a coil. After rolling, it becomes possible to make a plate material of a predetermined thickness only by cold rolling without performing intermediate annealing, and it is possible to achieve improvement in productivity and concomitant reduction in manufacturing cost, and the final after cold rolling In the rolled material, the average recrystallized grain size in the direction orthogonal to the rolling direction of the rolled material in the surface layer portion can be set to 50 μm or less to prevent unevenness in the surface quality of the printing plate. In addition, by performing hot rolling under the above conditions, Mg precipitation in the matrix is suppressed to 0.03% or less, and the roughened structure during the electrolytic treatment is improved, and as a result, surface quality unevenness is reduced. Can be prevented.

  A lithographic printing plate must have appropriate strength characteristics so that it can withstand deformation during transportation, tension when set in a printing press, and plate breakage during printing. This is related to the reduction ratio of cold rolling after hot rolling, and the degree of work during cold rolling is preferably 80% or more. If the degree of processing during cold rolling is less than 80%, sufficient strength is not given to the printing plate (printing plate support), and deformation and plate breakage are likely to occur. In order to impart the necessary strength characteristics to the printing plate, the tensile strength of the printed plate after cold rolling is desirably 180 MPa or more.

  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
An aluminum alloy having the composition shown in Table 1 is melted and cast, and the rolled surface of the resulting ingot is chamfered by 5 mm / each side to a thickness of 500 mm, and each ingot is homogenized under the conditions shown in Table 2. It processed and hot-rolled, and it wound up by the coil as predetermined plate | board thickness by hot finish rolling. After hot rolling, cold rolling was performed under the conditions shown in Table 2 without performing intermediate annealing, and a cold rolled material having a sheet thickness of 0.3 mm was obtained. 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. , Pb enrichment was evaluated. The results are shown in Table 3. In Table 3, those outside the conditions of the present invention are underlined.

  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 in the total intermetallic compound was examined by a phenol residue analysis method as shown in FIG. 1, and the amount of Mg deposited in the matrix was determined.

  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.

  In addition, for the test material (cold rolled plate), the following methods are used to observe the presence or absence of surface quality unevenness and streak, to evaluate the occurrence of unetched portions, to evaluate the uniformity of etch pits, Tensile strength was measured. The results are shown in Table 4. In Table 4, those outside the conditions of the present invention are underlined.

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.

  Measurement of tensile strength: A JIS No. 5 tensile test piece was taken from a test material (cold rolled plate) and subjected to a tensile test.

  As can be seen from Table 4, all of the test materials 1 to 4, the test material 12 and the test material 13 according to the present invention have no surface quality unevenness and streak, and are excellent in etching property after electrolytic treatment. Uniform etching pits are formed. Further, the tensile strength of each cold-rolled plate is 180 MPa or more, and the strength necessary for a printing plate is given.

  On the other hand, since the test material 5 had a large amount of Mg, the amount of Mg deposited in the matrix increased, resulting in uneven surface quality. Since the test material 6 has a small amount of Pb, sufficient surface roughening cannot be obtained in the electrolytic treatment, and the test material 7 has a large amount of Pb, so that the uniformity of pits in the surface roughening processing is lowered.

  Since the test material 8 has a long holding time from the end of hot rough rolling to the start of hot finish rolling, the recrystallized grains grow to generate partially coarse recrystallized grains. Fine recrystallized grains cannot be obtained, and a predetermined Mg and Pb enrichment cannot be obtained, and the test material 9 has a short holding time after the hot rough rolling to the start of hot finish rolling. Insufficient recrystallization prevents a uniform recrystallized structure from being obtained on the surface layer of the plate material, and a predetermined concentration of Mg and Pb cannot be obtained. The uniformity of was also inferior.

  The test material 10 had a low finish temperature of hot finish rolling, and since recrystallization was not sufficiently performed and non-recrystallized portions were generated, uneven patterns and streaks occurred, and the uniformity of pits during electrolytic treatment was poor. . Since the test material 11 had a low homogenization temperature, precipitation of Fe and Si proceeded excessively, the pit pattern during the electrolytic treatment became non-uniform, and an unetched part also occurred.

  Since the test material 14 has a low degree of cold work, the tensile strength is less than 180 MPa, the strength necessary for a printing plate is not imparted, and deformation and plate breakage are expected.

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

Claims (4)

Si: 0.03-0.15% (mass%, the same applies hereinafter), Fe: 0.2-0.7%, Mg: 0.05-0.15%, 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 10 to 40 times the average Mg concentration, the Pb concentration in the surface layer portion from the surface to a depth of 0.2 μm is 100 to 400 times the average Pb concentration, and the amount of Mg deposited in the matrix is 0.1. An aluminum alloy plate for a lithographic printing plate, characterized by being not more than 03%. The aluminum alloy plate for a lithographic printing plate according to claim 1, wherein Cu: 0.05% or less (not including 0%, the same shall apply hereinafter) is contained. The aluminum alloy plate for a lithographic printing plate according to claim 1 or 2, wherein the aluminum alloy plate has a tensile strength of 180 MPa or more. The aluminum alloy ingot according to claim 1 or 2 is subjected to homogenization treatment in a temperature range of 500 to 610 ° C for 1 hour or more, and then a start temperature is set to 400 to 520 ° C and an end temperature is set to 400 ° C or more. After the hot rough rolling, the hot rough rolled material is held for 60 to 300 seconds to recrystallize the surface of the hot rough rolled material after the hot rough rolling is completed, and then hot A method for producing an aluminum alloy plate for a lithographic printing plate, comprising performing finish rolling, finishing hot finish rolling at a temperature of 330 ° C or higher, and performing cold rolling with a workability of 80% or more.

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