JP5886619B2 - Method for producing aluminum alloy plate for lithographic printing plate - Google Patents

Description

  The present invention relates to a method for producing an aluminum alloy plate for a lithographic printing plate.

In lithographic printing, a PS plate is widely used as it is, after a photosensitive layer is formed in advance and developed, and then used as it is or after baking (burning) the photosensitive layer. The PS plate is coated with a photosensitive agent. It has a rough surface.
This PS plate is manufactured through a predetermined manufacturing process using an aluminum alloy, but is subjected to a surface treatment prior to the application of the photosensitive agent. In this surface treatment, the surface of the printing plate is roughened by electrolytic etching and then anodized as desired.

By the way, in newspaper printing and commercial printing for producing a large amount of printed matter, mechanization and speeding up of the printing process are progressing. For this reason, lithographic printing plates are required to have material strength that can withstand such mechanization and high speed. On the other hand, in terms of print quality, the lithographic printing plate is required to have a fine and uniform grained surface on the lithographic printing plate in order to realize printing with high resolution. ing.
So far, various aluminum alloy plates for lithographic printing plates and methods for producing the same have been proposed for the purpose of improving the uniformity of the roughening treatment by electrolytic etching and realizing material strength suitable for lithographic printing. (For example, see Patent Documents 1 to 4).

JP 2011-157628 A JP 2010-053410 A JP 2005-330588 A JP 2005-042187 A

However, the conventional method for producing an aluminum alloy plate for a lithographic printing plate has a problem that it is difficult to achieve both improvement in the uniformity of the roughening treatment by electrolytic etching and optimization of the material strength.
The object of the present invention has been made in view of the above circumstances, and improves the uniformity of the surface roughening treatment by electrolytic etching, and has an aluminum alloy plate for lithographic printing plates having material strength suitable for lithographic printing. An object of the present invention is to provide a method for producing an aluminum alloy plate for a lithographic printing plate capable of producing a lithographic printing plate.

That is, among the methods for producing an aluminum alloy plate for a lithographic printing plate of the present invention, the first present invention is a method for producing an aluminum alloy plate for a lithographic printing plate to be subjected to electrolytic etching,
In mass%, Fe: 0.2-0.6%, Si: 0.02-0.2%, Cu: 0.001-0.02%, Zn: 0.01-0.1%, Mg: 0.01% or more and less than 0.1%, Ti: 0.001 to 0.05%, with the balance being heated to a temperature exceeding 550 ° C. with respect to an aluminum alloy ingot having a composition consisting of Al and inevitable impurities The hot rolling is started without performing, and the hot rolling is finished at a temperature of less than 300 ° C. to obtain an aluminum alloy plate having a thickness of 2 to 6 mm, and intermediate annealing is performed on the aluminum alloy plate after the hot rolling. The aluminum alloy plate for a lithographic printing plate having a tensile strength of 180 MPa to 220 MPa is obtained by performing cold rolling with a cold rolling rate of 80% or more without applying a finish and finishing to a predetermined final plate thickness. .

  The method for producing an aluminum alloy plate for a lithographic printing plate according to the second aspect of the present invention is characterized in that, in the first aspect of the present invention, the final plate thickness is 0.1 to 0.4 mm.

  That is, according to the present invention, Fe and Si that contribute to uniform etching pits, Cu that contributes to improvement in electrolysis, Zn that contributes to improvement in reactivity in the cathode region, and Mg that contributes to improvement in etching property , And an appropriate amount of Ti that contributes to the refinement of crystal grains. Moreover, since the hot rolling is started without heating the aluminum alloy ingot having the above composition to a temperature exceeding 550 ° C., it is possible to suppress the coarsening of the intermetallic compound and the decrease in the density. it can. Therefore, according to the present invention, the uniformity of the surface roughening treatment by electrolytic etching can be improved, and an aluminum alloy plate for a lithographic printing plate having a fine and uniform grained surface can be obtained. .

  Further, according to the present invention, an appropriate amount of Mg that contributes to improvement of material strength and heat softening resistance by solid solution is contained. Moreover, since hot rolling is complete | finished at the temperature below 300 degreeC, the solid solution amount of Fe can be ensured appropriately. Therefore, the material strength of the aluminum alloy plate for planographic printing plates can be improved. In addition, an aluminum alloy plate having a thickness of 2 to 6 mm is obtained by hot rolling, and the cold rolling rate is set to 80% or more, so that appropriate material strength can be obtained when cold rolling is performed to the product thickness. . Moreover, since intermediate annealing is not performed between a plurality of cold rolling operations, material strength can be ensured. Therefore, according to the present invention, an aluminum alloy plate for a lithographic printing plate having material strength suitable for lithographic printing can be obtained.

  Below, the reasons for limitation such as components and production conditions defined in the present invention will be described. In addition, all component content is shown by the mass%.

Fe: 0.2 to 0.6%
Fe is an element that contributes to uniform etching pits by forming an AlFe-based crystal precipitate (intermetallic compound) that is a fine precipitate when contained in an appropriate amount. To obtain an appropriate amount of intermetallic compound particles, Fe is 0. It is necessary to contain 2% or more. If the Fe content is less than 0.2%, the formation of crystal precipitates is insufficient, the number of etching pit start points is small, and the etching pits are non-uniform. As a result, desired etching properties cannot be obtained. On the other hand, if the Fe content exceeds 0.6%, the etching pits become non-uniform due to the formation of giant crystal precipitates. For this reason, content of Fe is defined in 0.2 to 0.6% of range. For the same reason, it is desirable to set the lower limit to 0.2% and the upper limit to 0.5%.

Si: 0.02 to 0.2%
Si is an element that contributes to uniform etching pits by being precipitated in an aluminum matrix when contained in an appropriate amount to refine crystal grains. However, if the Si content is less than 0.02%, the crystal grains are not sufficiently refined, the etching pit start points are small, and the etching pits are non-uniform, resulting in desired etching properties. Can not. Moreover, if the Si content is reduced to less than 0.02%, the cost increases due to the use of high-purity bullion, causing problems in terms of industrial properties. On the other hand, when the Si content exceeds 0.2%, Si-based giant crystal precipitates are formed, making the etching pits non-uniform, and also contributing to ink stains. For this reason, the Si content is set to a range of 0.02 to 0.2%. For the same reason, it is desirable to set the lower limit to 0.05% and the upper limit to 0.15%.

Cu: 0.001 to 0.02%
Cu is an element that contributes to the improvement of the electrolytic property in electrolytic etching by containing an appropriate amount, makes it easy to form etching pits, and enables formation of uniform etching pits. However, if the Cu content is less than 0.001%, a large current is required to form etching pits by electrolytic etching. Under normal conditions, formed etching pits are shallow or etching pits are difficult to form. Become. On the other hand, when the Cu content exceeds 0.02%, the depth of the etching pits increases, but local electrolytic etching occurs, and large etching pits are formed unevenly. For this reason, content of Cu is defined to be 0.001 to 0.02% of range. For the same reason, it is desirable to set the lower limit to 0.001% and the upper limit to 0.01%.

Zn: 0.01 to 0.1%
Zn is an element that contributes to the improvement of the etching property by improving the reactivity in the cathode region in the electrolytic etching by containing an appropriate amount. However, if the Zn content is less than 0.01%, the reactivity in the cathode region is insufficient, and it becomes difficult to sufficiently improve the etching property. On the other hand, if the Zn content exceeds 0.1%, it will be a cause of hindering recycling of the used lithographic printing plate. For this reason, the Zn content is set in the range of 0.01 to 0.1%. For the same reason, it is desirable to set the lower limit to 0.025% and the upper limit to 0.08%.

Mg: 0.01% or more and less than 0.1% Mg is dissolved in an aluminum crystal when contained in an appropriate amount to contribute to improvement of material strength and heat softening resistance, and the formed oxide film is an acidic electrolyte. It is an element that contributes to the improvement of etching property by acting on the surface. However, if the Mg content is less than 0.01%, the material strength and strength after burning are insufficient, and the etching property is lowered. On the other hand, if the Mg content is 0.1% or more, the material strength becomes too high and bending workability becomes insufficient, so that it is difficult to wind around the plate cylinder during printing. For this reason, the Mg content is set in a range of 0.01% or more and less than 0.1%. For the same reason, it is desirable to set the lower limit to 0.02% and the upper limit to 0.04%.

Ti: 0.001 to 0.05%
Ti is an element that contributes to refinement of crystal grains when contained in an appropriate amount. However, if the Ti content is less than 0.001%, the crystal grains cannot be refined. On the other hand, if the Ti content exceeds 0.05%, the etching pits become non-uniform due to the formation of giant crystal precipitates. For this reason, the Ti content is set to a range of 0.001 to 0.05%. For the same reason, it is desirable to set the lower limit to 0.005% and the upper limit to 0.02%.

  The ingot of aluminum alloy contains the above components, and the remainder has a composition composed of Al and inevitable impurities, and can be cast by a conventional method. Examples of inevitable impurities include Mn, Y, Sn, Zr, Ga, Ni, and In, and the content of these impurities is preferably individually suppressed to 0.03% by mass or less. .

  In addition, for the ingot of aluminum alloy having the above composition, the hot rolling described below can be started without performing the homogenization process or after performing the homogenization process at a temperature of 550 ° C. or less. . The reason why the homogenization process is omitted or the temperature of the homogenization process is set to 550 ° C. or less is to prevent the intermetallic compound from becoming coarse and reducing the density. Even when the homogenization treatment is omitted, there is no inconvenience because the number of fine intermetallic compounds contributing to the uniformity of electrolytic etching is not reduced.

Hot rolling Hot rolling is performed without heating the aluminum alloy ingot having the above composition to a temperature exceeding 550 ° C. Since hot rolling is started without heating to a temperature exceeding 550 ° C., coarsening of the intermetallic compound can be suppressed, and uniform etching pits can thereby be formed. If heat treatment is performed to heat to a temperature exceeding 550 ° C. before starting the hot rolling, the intermetallic compound becomes coarse and the etching pits become non-uniform.

Moreover, hot rolling is complete | finished at the temperature below 300 degreeC. Thus, by setting the finishing temperature of hot rolling to less than 300 ° C., the solid solution amount of Fe can be appropriately secured and the material strength can be improved. When the finishing temperature of hot rolling is 300 ° C. or higher, the amount of Fe precipitation increases and the solid solution amount of Fe decreases, resulting in a decrease in material strength. Note that the lower limit of the hot rolling finishing temperature is preferably 220 ° C., because the rolling load becomes high and the rollability deteriorates when the temperature during rolling is low.
An aluminum alloy plate having a thickness of 2 to 6 mm is obtained by hot rolling under the above conditions. Thus, by setting the finishing plate thickness by hot rolling to 2 to 6 mm, it is possible to obtain an appropriate material strength when rolling to the product plate thickness by subsequent cold rolling. If the finished plate thickness is less than 2 mm, work hardening is insufficient and sufficient material strength cannot be obtained. If the finished plate thickness exceeds 6 mm, the number of subsequent cold rolling passes increases. Productivity will be reduced.

Cold rolling Cold rolling is performed without intermediate annealing on the aluminum alloy sheet after the hot rolling. When intermediate annealing is performed, softening in burning can be suppressed, but the material strength is reduced. As for softening by burning, heat resistance softening can be improved by containing Mg as described above, and softening by burning can be suppressed.
Further, the number of passes in cold rolling is not particularly limited as the present invention, but the cold rolling rate is 80% or more. If the cold rolling rate is less than 80%, work hardening is insufficient and sufficient material strength cannot be obtained. By setting the cold rolling rate to 80% or more, sufficient material strength can be obtained.

  The aluminum alloy plate after the cold rolling preferably has a plate thickness of 0.1 to 0.4 mm and a tensile strength of 180 MPa to 220 MPa. By having such a plate thickness and tensile strength, it is possible to prevent deformation against high stress caused by machine conveyance and rotation of a rotary press at high speed, and has workability applicable to various plate cylinders. It can be suitably used as an aluminum alloy plate for a lithographic printing plate. However, the present invention is not limited to the above plate thickness and tensile strength.

  As explained above, according to the method for producing an aluminum alloy plate for a lithographic printing plate of the present invention, the mass% is Fe: 0.2-0.6%, Si: 0.02-0.2%, Cu: 0.001 to 0.02%, Zn: 0.01 to 0.1%, Mg: 0.01% or more and less than 0.1%, Ti: 0.001 to 0.05%, the balance being Thickness of aluminum alloy ingot having a composition composed of Al and inevitable impurities starts hot rolling without heating to a temperature exceeding 550 ° C., and finishes the hot rolling at a temperature below 300 ° C. A 2 to 6 mm aluminum alloy plate is obtained, and the hot rolled aluminum alloy plate is subjected to cold rolling with a cold rolling rate of 80% or more without intermediate annealing, and finished to a predetermined final plate thickness. So improve the uniformity of surface roughening process by electrolytic etching Rutotomoni, it is possible to manufacture the aluminum alloy strip for lithographic printing plates having suitable material strength in lithographic printing.

It is a flowchart which shows the manufacturing method of the aluminum alloy plate for lithographic printing plates of one Embodiment of this invention.

Hereinafter, the manufacturing method of the aluminum alloy plate for planographic printing plates of one Embodiment of this invention is demonstrated based on FIG.
First, an aluminum alloy ingot that is a material of an aluminum alloy plate for a lithographic printing plate can be cast by a conventional method, and can be obtained by adjusting the components so as to be within the component range of the present invention and casting. (Step s1).

  Next, the obtained aluminum alloy ingot is subjected to chamfering for removing a non-uniform portion of the surface layer and, if desired, a homogenization treatment at a temperature of 550 ° C. or less (step s2). The reason why the temperature of the homogenization treatment is set to 550 ° C. or less is to suppress the coarsening of the intermetallic compound. The homogenization process may be omitted. By omitting homogenization, coarsening of intermetallic compounds due to homogenization heating can be avoided. In addition, when performing chamfering and a homogenization process, the process after these processes is not limited.

After the homogenization process, hot rolling is performed (step s3). Hot rolling is started without heating to a temperature exceeding 550 ° C. including the homogenization treatment. By starting hot rolling without heating to a temperature exceeding 550 ° C., it does not exceed 550 ° C. even during hot rolling, and coarsening of the intermetallic compound can be suppressed. For this reason, uniform etching pits can be formed in the roughening treatment by electrolytic etching described later.
The hot rolling is finished at a temperature lower than 300 ° C. to obtain an aluminum alloy plate having a thickness of 2 to 6 mm. By setting the finishing temperature of hot rolling to less than 300 ° C., it is possible to appropriately secure the solid solution amount of Fe and improve the material strength. Moreover, when the finished plate thickness by hot rolling is 2 to 6 mm, an appropriate material strength can be obtained when the product is rolled to the product plate thickness by subsequent cold rolling.

Cold rolling is performed on the aluminum alloy sheet after the hot rolling without performing intermediate annealing (step s4). By not performing the intermediate annealing during the cold rolling, it is possible to avoid a decrease in material strength due to the intermediate annealing and obtain a sufficient material strength. Moreover, softening by burning can be suppressed by containing Mg in the said range instead of intermediate annealing.
Note that the number of cold rolling passes is not limited to one, but can be appropriately set to two or more according to the characteristics required of the aluminum alloy plate for planographic printing plates.

Thus, the aluminum alloy plate is finished to a predetermined plate thickness at a cold rolling rate of 80% or more by a plurality of cold rolling operations without intermediate annealing. By setting the cold rolling rate to 80% or more, sufficient material strength can be obtained without insufficient work hardening.
The aluminum alloy plate after the above-described cold rolling has, for example, a plate thickness of 0.1 to 0.4 mm and a tensile strength of 180 MPa to 220 MPa.

  The aluminum alloy plate obtained as described above can be supplied as a PS plate after surface cleaning, roughening treatment, formation of an anodized film, and application of a photosensitive agent. Hereinafter, these steps will be described with reference to them. Note that the following steps do not define the present invention.

  In the case of an alloy plate, surface cleaning is usually performed prior to application of a photosensitive agent. In surface cleaning, cleaning is generally performed for the purpose of removing oil, dirt, etc. adhering to the surface. This washing is usually performed by caustic treatment using caustic soda. However, the present invention may include an acid treatment and other treatments, or may comprise a treatment that does not include a caustic treatment. . The solution used for washing, the washing procedure, conditions, etc. are not particularly limited as the present invention, and can be carried out by a conventional method. Further, the surface cleaning may be performed by mechanical polishing together with the cleaning step or without passing through the cleaning step.

The aluminum alloy plate whose surface has been cleaned is then subjected to a roughening treatment in order to roughen the surface. This roughening treatment is usually performed by electrolytic etching. This roughening is performed for the purpose of firmly fixing a photosensitive agent described later on the printing plate surface and improving the water retention of dampening water attached to the non-image area during printing. In the present invention, etching conditions including electrolytic etching are not particularly limited, and can be performed by, for example, a conventional method.
The material of the present invention is excellent in etching property, and the etching provides a rough surface with few unetched portions and uniform etching pits.

  Further, in the above printing plate, an anodized film is usually formed after the roughening treatment for anticorrosion, abrasion resistance and hydrophilicity. This film treatment can be performed by a conventional method, and the present invention is not particularly limited with respect to production conditions and film properties, and it is possible to select not to form an anodized film. After forming the anodized film, a desired photosensitizer is applied to the surface. The type of the photosensitive agent is not limited in the present invention, and a known photosensitive agent can be used. Further, an apparatus, a coating method, and a coating amount used for coating the photosensitive agent are appropriately selected. After application of the photosensitive agent, it is supplied as a PS plate.

Examples of the present invention will be described below.
First, an aluminum alloy having the composition shown in Table 1 (the balance being Al and inevitable impurities) was melt cast to obtain a slab. Next, as a homogenization treatment, the slab was heated at the slab heating temperature shown in Table 1 for 4 hours. Furthermore, hot rolling and cold rolling were sequentially performed under the production conditions shown in Table 1 to obtain an aluminum alloy plate having the final thickness shown in Table 1.
In Comparative Example 10 where only the intermediate annealing was performed, intermediate annealing was performed at a sheet thickness of 1 mm and a temperature of 420 ° C., and then cold rolling was performed to a sheet thickness of 0.3 mm at a cold rolling rate of 70%.

About each aluminum alloy plate obtained as mentioned above, the tensile strength was measured by JISZ2201, and the uniformity was evaluated by performing electrolytic etching.
Moreover, the uniformity of electrolytic etching was evaluated as follows. That is, after performing electrolytic etching on an aluminum alloy plate in 2% hydrochloric acid at 25 ° C. under conditions of an AC frequency of 50 Hz, a current density of 60 A / dm ² , and an electrolysis time of 30 seconds, the surface of the aluminum alloy plate is scanned. Observation was performed with an electron microscope (SEM). As a result of observation, “「 ”indicates that the area ratio of the unetched portion on the surface is less than 2%,“ ◯ ”indicates that the area ratio is 2% or more and less than 5%, and“ × ”indicates that the area ratio is 5% or more and less than 10%. % Or more was evaluated as “XX”.
Table 1 shows the measurement results of tensile strength and the evaluation results of the uniformity of electrolytic etching.

  As shown in Table 1, the material of the present invention has a tensile strength suitable for lithographic printing and is excellent in the uniformity of electrolytic etching. On the other hand, the comparative material that does not satisfy the above-described conditions of the present invention has a tensile strength that is unsuitable for lithographic printing or inferior in uniformity of electrolytic etching.

Claims (2)

A method for producing an aluminum alloy plate for a lithographic printing plate subjected to electrolytic etching,
In mass%, Fe: 0.2-0.6%, Si: 0.02-0.2%, Cu: 0.001-0.02%, Zn: 0.01-0.1%, Mg: 0.01% or more and less than 0.1%, Ti: 0.001 to 0.05%, with the balance being heated to a temperature exceeding 550 ° C. with respect to an aluminum alloy ingot having a composition consisting of Al and inevitable impurities The hot rolling is started without performing, and the hot rolling is finished at a temperature of less than 300 ° C. to obtain an aluminum alloy plate having a thickness of 2 to 6 mm, and intermediate annealing is performed on the aluminum alloy plate after the hot rolling. The aluminum alloy plate for a lithographic printing plate having a tensile strength of 180 MPa to 220 MPa is obtained by performing cold rolling with a cold rolling rate of 80% or more without applying a finish and finishing to a predetermined final plate thickness. Manufacturing method of aluminum alloy plates for lithographic printing plates .   2. The method for producing an aluminum alloy plate for a lithographic printing plate according to claim 1, wherein the final plate thickness is 0.1 to 0.4 mm.

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