JP4740896B2 - Method for producing aluminum alloy plate for lithographic printing plate - Google Patents

Description

  The present invention relates to an aluminum alloy plate for a lithographic printing plate, and more particularly to a method for producing an aluminum alloy plate for a lithographic printing plate that is suitable for roughening by electrochemical etching and has excellent productivity during production.

  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.

  Further, in order to improve the printing durability of the printing plate, a printing plate having an aluminum alloy plate as a support is exposed and developed by a usual method, and then a heating temperature of 200 to 290 ° C. and a heating time of 3 to 9 minutes. The image portion is reinforced by heat treatment (burning treatment) under the conditions, and heat resistance (burning resistance) is required so that the strength of the support does not decrease during the burning treatment. Furthermore, when processed as a printing plate, it is also important that there is no uneven structure of the aluminum alloy plate support, generation of streaks due to non-recrystallized portions, and uneven patterns.

  A relatively uniform electrolytic surface roughening is obtained by the electrochemical etching treatment, and an aluminum alloy plate that satisfies the above-mentioned strength and heat resistance requirements is based on an A1050 (aluminum purity 99.5%) equivalent material or an A1050 equivalent material. A material in which a specific amount of Mg and Zn coexist is applied (see Patent Document 1), and a clear printed material of 100,000 sheets can be obtained by appropriately selecting a photosensitive layer applied on a support. Can be obtained.

  Conventionally, an aluminum alloy material for a lithographic printing plate based on the above A1050 is subjected to homogenization treatment, hot rolling, cold rolling, and intermediate annealing treatment in the middle of cold rolling. By making the recrystallized structure having an average crystal grain size of 40 μm or less on the recrystallized grains on the surface of the plate, secondary cold rolling is performed to make uniform the generation of pits during the electrochemical etching process. Streaks are prevented from occurring when processing is performed. However, reduction in productivity and increase in manufacturing cost due to intermediate annealing are inevitable, and improvement is 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 of 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 2).
JP 2005-15912 A Japanese Patent Laid-Open No. 11-335761

  In order to omit the intermediate annealing, it is necessary to recrystallize at the stage of winding as a coil after completion of hot finish rolling, but the recrystallized grain size to be formed does not become coarse, As with the annealed material, it is important that the material is fine and uniform, and that the degree of recrystallization of the plate surface layer portion is uniform.

  In order to obtain such a structure, the inventors conducted tests and examinations based on the above proposed method, and as a result, there were regions where recrystallization hardly occurred and strain was hardly introduced due to microsegregation during casting. If present, coarse recrystallized grains and fine recrystallized grains are likely to be mixed after the hot rolling is finished, so that a fine recrystallized structure is formed at the end of the hot rough rolling, and the surface layer portion is made uniform. It is important to obtain a fine and uniform recrystallized structure by imparting moderate processing strain in hot finish rolling, and for that purpose, the hot rough rolling start temperature, hot rough rolling end to hot finish 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 pits are generated during the electrochemical etching process It is an object of the present invention to provide a method for producing an aluminum alloy plate for a lithographic printing plate that is uniform and does not generate streaks when it is processed as a printing plate, and that can improve productivity and reduce manufacturing costs.

  In order to achieve the above object, an aluminum alloy plate for a lithographic printing plate according to claim 1 has Mg: 0.05 to 1.5%, Fe: 0.1 to 0.7%, Si: 0.03 to 0 An ingot of aluminum alloy containing 15%, Cu: 0.0001 to 0.10%, Ti: 0.0001 to 0.1% and having a composition composed of the balance aluminum and unavoidable impurities is 500 to 610 ° C. After performing the homogenization treatment for 1 hour or more in the temperature range, hot rough rolling is performed with a start temperature of 430 to 500 ° C. and an end temperature of 400 ° C. or more. Before starting rolling, the hot rough rolled material is held for 60 to 300 seconds to recrystallize the surface of the hot rough rolled material, and then hot finish rolling is performed, and the hot finish rolling is performed at a temperature of 320 to 370 ° C. End in a hot and coiled as a coil The average recrystallized grain size in the direction perpendicular to the rolling direction of the surface of the raised rolled material, characterized in that the 50μm or less.

  The method for producing an aluminum alloy plate for a lithographic printing plate according to claim 2 is characterized in that, in claim 1, after the hot finish rolling, a plate material having a predetermined thickness is obtained only by cold rolling.

  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 the need to perform pits, uniform pits are generated during the electrochemical etching process, and there is no streak when printing plates are processed, improving productivity And a method for producing an aluminum alloy plate for a lithographic printing plate that can reduce the production cost.

  Explaining the significance and reasons for limitation of the components contained in the aluminum alloy plate for lithographic printing plates according to the present invention, Mg is mostly dissolved in aluminum and functions to improve strength and heat softening resistance (burning resistance). To do. Further, the formation of magnesium oxide improves the wettability with the treatment liquid during the electrolytic surface roughening, and the surface roughening is promoted. The preferable content of Mg is in the range of 0.05 to 1.5%. If the content is less than 0.05%, the effect is not sufficient. If the content exceeds 1.5%, the uniformity of the pits in the surface roughening treatment is insufficient. It becomes low and the stain | pollution | contamination of a non-image part tends to arise.

  Fe produces an Al—Fe-based intermetallic compound, and coexists with Si to produce an Al—Fe—Si-based intermetallic compound. The dispersion of these compounds refines the recrystallized structure. The compound serves as a starting point of pit generation, uniformizing pit formation during the electrolytic treatment, and finely distributing the pits. The preferable content of Fe is in the range of 0.1 to 0.7%, and if it is less than 0.1%, 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.

  Cu is easily dissolved in aluminum and has an effect of refining pits in a content range of 0.001 to 0.1%. If the content exceeds 0.1%, the pits during the electrolytic treatment are likely to be coarse and non-uniform.

  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 0.0001 to 0.1%. When the content is less than 0.0001%, the effect is small. When the content exceeds 0.1%, 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.

  The aluminum alloy plate for a lithographic printing plate according to the present invention further improves electrolytic graining properties by adding 0.005 to 0.05% of one or more of Pb, In, Sn and Ga in a total amount. The desired pit pattern can be obtained with a small amount of electricity. If the total amount of one or more elements selected from the group consisting of Pb, In, Sn, and Ga is less than 0.005%, the effect is not sufficient, and if it exceeds 0.05%, the shape of the pit tends to collapse. Become.

  The production of an aluminum alloy plate for a lithographic printing plate according to the present invention is performed by ingot-making the aluminum alloy ingot by continuous casting or the like, and homogenizing the obtained ingot, followed by hot rolling and cold rolling. The most distinctive feature is to specify the rolling start temperature, rolling end temperature, and holding time until the transition from rough rolling to finish rolling in the hot rolling process consisting of hot rough rolling and hot finish rolling. In addition, by controlling the recrystallized grains when wound as a coil after finish rolling, it is a point that a plate material of a predetermined thickness is obtained only by cold rolling without performing intermediate annealing after hot finish 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. When the homogenization temperature is less than 500 ° C., the precipitation of Fe and Si is not sufficient, 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, the hot rough rolling starts at 430 to 500 ° 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.

  When the starting temperature of hot rough rolling is less than 430 ° C., the deformation resistance of the material is large, and the number of rolling passes is increased, thereby reducing productivity. When the temperature exceeds 500 ° C., coarse recrystallized grains are generated during rolling, and a streak-like uneven structure tends to be formed. When 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 is difficult to obtain a uniform surface structure. In addition, when the holding time after the hot rough rolling is completed and before the hot finish rolling is started is less than 60 seconds, recrystallization becomes insufficient and it is difficult to obtain a uniform surface structure. If the time is maintained for more than 300 seconds, the recrystallized grains grow and partially coarse recrystallized grains are generated, and it is difficult to obtain fine recrystallized grains at the end of hot rolling.

  Next, hot finish rolling is performed, and the hot finish rolling is finished at a temperature of 320 to 370 ° C. and wound as a coil. If the start temperature of hot finish rolling is less than 400 ° C., the end temperature of hot finish rolling will be low, resulting in insufficient recrystallization and streaks. When the finish temperature of hot finish rolling is less than 320 ° C., recrystallization occurs only partially, causing streaks. When the finish temperature of hot finish rolling exceeds 370 ° C., the recrystallized grains become coarse, causing streaks.

  After performing the above hot rolling, the average recrystallized grain size in the direction orthogonal to the rolling direction of the surface of the hot finish rolled material can be reduced to 50 μm or less by winding up as a coil. After that, it is possible to obtain a plate material having a predetermined thickness only by cold rolling without performing intermediate annealing, and it is possible to achieve improvement in productivity and reduction in manufacturing cost accordingly. A more preferable range of the average recrystallized grain size in the direction orthogonal to the rolling direction of the surface of the hot finish rolled material is 40 μm or less.

  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 the hot rolling, cold rolling was performed without performing intermediate annealing 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 hot-rolled rolled material wound on a coil and cold-rolled rolled material as a test material, the test material is collected from the hot-finished rolled material wound on a coil, and the surface of the hot-finished rolled material is obtained by the following method. The average recrystallized grain size in the direction orthogonal to the rolling direction of was measured. 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 a cutting method.

  Further, the cold rolled material was observed for the presence or absence of uneven patterns and streaks by the following methods, and evaluated for the occurrence of unetched portions and the uniformity of etch pits. The results are shown in Table 3.

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.

About each test piece, the presence or absence of a nonuniform pattern and streak was observed. 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 uneven pattern: A case where the uneven pattern was visually observed on the surface of the test piece was evaluated as bad (×), and a case where the uneven pattern 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 10 μm are defective (×) when the area ratio exceeds 10% with respect to all pits, and those with 10% or less are good (◯) It was.

  As can be seen in Table 3, all of the test materials 1 to 5 according to the present invention have no uneven pattern or streak, 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 6 has a small amount of Mg, sufficient surface roughening cannot be obtained in the electrolytic treatment, and since the test material 7 has a large amount of Mg, the uniformity of pits in the surface roughening processing is reduced. To do.

  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 the test material 9 has a short retention time from the end of hot rough rolling to the start of hot finish rolling. A uniform recrystallized structure was not obtained, and uneven patterns and streaks occurred.

  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, the precipitation of Fe and Si was not sufficient, the pit pattern during the electrolytic treatment became non-uniform, and an unetched part also occurred.

Claims (2)

Mg: 0.05-1.5% (mass%, the same applies hereinafter), Fe: 0.1-0.7%, Si: 0.03-0.15%, Cu: 0.0001-0.10% , Ti: 0.0001 to 0.1% containing an aluminum alloy ingot having a composition composed of the balance aluminum and inevitable impurities was subjected to a homogenization treatment for 1 hour or more in a temperature range of 500 to 610 ° C. Thereafter, hot rough rolling is performed at a start temperature of 430 to 500 ° C. and an end temperature of 400 ° C. or more. After the hot rough rolling, 60 to 300 of the hot rough rolled material is obtained before the start of hot finish rolling. Hold for 2 seconds to recrystallize the surface of the hot rough rolled material, then perform hot finish rolling, finish the hot finish rolling at a temperature of 320 to 370 ° C. and wind it up as a coil, Average in the direction perpendicular to the rolling direction of the surface of the rolled material Method of manufacturing aluminum alloy plate for a lithographic printing plate, characterized in that the crystal grain size and 50μm or less. 2. The method for producing an aluminum alloy plate for a lithographic printing plate according to claim 1, wherein after the hot finish rolling, the plate material has a predetermined thickness only by cold rolling.