JP5968637B2 - Surface-treated aluminum alloy plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a surface-treated aluminum alloy plate, and more particularly, to a surface-treated aluminum alloy plate that can be suitably used for vehicles such as automobiles, ships, and aircraft, and particularly for automobile panels, and a method for manufacturing the same.

  As is well known, various aluminum alloy plates have been conventionally used for each alloy for transporting machines such as automobiles, ships, airplanes or vehicles, machines, electrical products, architecture, structures, optical instruments, equipment members and parts. It is widely used depending on the characteristics. And in recent years, in response to global environmental problems caused by exhaust gas, etc., the improvement of fuel efficiency has been pursued by reducing the weight of automobile bodies. Therefore, instead of steel materials that have been used in the past, specific gravity is about 3 and the use of aluminum alloy plates having excellent energy absorption for automobile bodies is increasing.

  When an aluminum alloy plate is used as an automobile panel, formability, weldability, adhesion, chemical conversion treatment, corrosion resistance after painting, aesthetics, and the like are required. And the method of manufacturing an automobile panel using an aluminum alloy plate is as follows: 1) molding (cutting out to a predetermined dimension, press molding to a predetermined shape), 2) joining (welding and / or bonding), 3) chemical conversion treatment ( Degreasing with cleaning agent → surface adjustment → zinc phosphate treatment), 4) coating (undercoating by electrodeposition coating → intermediate coating → overcoating), which is basically the same as when using a conventional steel plate.

  On the other hand, modularization of automobile parts is progressing, and there is a tendency that a period from when the aluminum alloy plate itself is manufactured until the automobile panel manufacturing process and the vehicle body manufacturing process are started becomes longer. The modularization of automobile parts is a method in which individual parts that have been directly attached to a vehicle body at an automobile manufacturer are sub-assembled in advance at a parts company and then attached to the car body. This modularization is mainly aimed at simplifying difficult work for automobile manufacturers and increasing production efficiency, and also has the effect of shortening the production process and reducing work in progress. The modularization of automobile parts increases the burden on the parts company, but it is effective in reducing the cost of the automobile company and the parts company as a whole, and consequently contributes to the cost reduction of the automobile.

  And since the period from the time when the aluminum alloy plate itself is manufactured until it enters the above manufacturing process becomes longer than before, from the viewpoint of protecting the surface of the aluminum alloy plate, a process of applying rust preventive oil to the aluminum alloy plate Is done. However, in such a case, the surface characteristics of the aluminum alloy plate inevitably change over time, and there is a problem that the aluminum alloy plate has an adverse effect on the degreasing and chemical conversion properties. That is, as the surface characteristics of the aluminum alloy plate change with time, the degreasing property during the chemical conversion treatment deteriorates and the chemical conversion treatment film becomes difficult to adhere, resulting in an influence on the corrosion resistance after coating. In addition, in aluminum alloy automobile panels joined with adhesives, moisture, oxygen, or salt content penetrates into the joints during use, causing the interface between the adhesive and the aluminum alloy plate to deteriorate over time and cause interface peeling. Is generated, and the adhesive strength is a problem.

  For this reason, conventionally, the degreasing property, the chemical conversion treatment property and the adhesion property have been improved by removing the oxide film formed on the surface of the aluminum alloy plate, particularly the oxide film containing Mg, by washing or the like. (For example, see Patent Documents 1 to 5). However, it has been difficult to completely remove the oxide film, and it has been difficult to obtain an excellent surface stability with little change in surface characteristics over time. Moreover, since it was necessary to wash | clean strongly in order to remove an oxide film completely, it was inferior to productivity and was not economical.

  Then, the Mg amount and OH amount of the oxide film of an aluminum alloy plate are adjusted, and antirust oil is applied within 14 days after the adjustment of the oxide film (see, for example, Patent Document 6). Further, a surface film composed of a phosphate film and an aluminum oxide film formed thereon is formed on the surface of the aluminum alloy plate, and antirust oil is applied on the surface film (aluminum oxide film). (For example, refer to Patent Document 7).

Japanese Patent Laid-Open No. 06-256980 Japanese Patent Laid-Open No. 06-256881 Japanese Patent Laid-Open No. 05-070741 Japanese Patent Laid-Open No. 04-214835 Japanese Patent Laid-Open No. 02-115385 JP 2006-200007 A Japanese Patent No. 2744697

  However, the time-dependent change in the surface characteristics of the aluminum alloy plate is the greatest in the amount of change from immediately after the production of the aluminum alloy plate to about one week, and the change thereafter is relatively small. Therefore, in the aluminum alloy plate described in Patent Document 6, since the antirust oil is applied within 14 days after the surface adjustment, the surface protection of the aluminum alloy plate may be insufficient, and the intended degreasing There exists a problem that property, chemical conversion treatment property, and adhesiveness cannot be obtained. In addition, in the aluminum alloy plate described in Patent Document 7, the structure of the surface film is specified by the sample evaluation result left for one week after oil application, so that the desired degreasing property, chemical conversion treatment property and There is a problem that adhesiveness cannot be obtained.

  The present invention solves the above-described problems, and is excellent in degreasing properties, chemical conversion treatment properties, and adhesive properties even if the period from the production of an aluminum alloy plate itself to the production process of an automobile panel or the like becomes longer. It is an object of the present invention to provide a surface-treated aluminum alloy plate and a method for producing the same.

In order to solve the above problems, a surface-treated aluminum alloy plate according to the present invention is a surface-treated aluminum alloy plate comprising a substrate made of an aluminum alloy containing magnesium and an oxide film formed on the surface of the substrate. The oxide film has a thickness of 1 to 30 nm, a magnesium concentration of 1 to 20 atomic%, a zirconium concentration of 0.2 to 10 atomic%, a silicon concentration of 2 to 10 atomic%, a halogen concentration and a phosphorus concentration. Each of the concentrations was less than 0.1 atomic%.
Note that “the halogen concentration and the phosphorus concentration are each less than 0.1 atomic%” means that substantially no halogen and phosphorus are contained, as will be described later. And not containing halogen and phosphorus means that when measuring halogen and phosphorus with fluorescent X-rays and GD-OES, it cannot be measured, that is, less than the measurement limit.

According to such a configuration, by providing an oxide film containing zirconium and silicon formed on the surface of the substrate, it is possible to perform degreasing, chemical conversion, and adhesion without performing acid cleaning or the like that has been conventionally performed. Will improve. In particular, in the oxide film, the surface treatment film suppresses the adsorption of the rust-preventing oil because the adhesion amount specified in terms of zirconium dioxide is within a predetermined range. It can be removed sufficiently and good water wettability is maintained. As a result, the occurrence of chemical conversion unevenness due to poor degreasing (bad wettability) is suppressed. In addition, since the surface treatment film and the oxide film to form a total oxide film is firmly bonded, interfacial peeling between the surface-treated aluminum alloy sheet and the adhesive is prevented from occurring. In particular, in the oxide film, when the silicon amount is within a predetermined range, adhesion is enhanced as compared with the zirconium film alone, and interfacial peeling may occur between the surface-treated aluminum alloy plate and the adhesive. It is suppressed. In addition, since the surface treatment film in the entire oxide film does not contain halogen and phosphorus, a surface treatment solution that does not contain halogen and phosphorus is used when producing a surface-treated aluminum alloy sheet, which imposes a load on the production equipment. Is reduced and the environmental impact is reduced.

The method for producing a surface-treated aluminum alloy plate according to the present invention includes a substrate production step for producing the substrate by rolling, and a heating step for heating the substrate to 400 to 580 ° C. to form an oxide film on the surface of the substrate. Cooling the substrate on which the oxide film is formed, and subjecting the surface of the oxide film to a surface treatment, wherein the halogen concentration and the phosphorus concentration are each less than 0.1 atomic% in the cooling step Yes, a zirconium nitrate concentration is 0.005 to 5 g / L, a silane coupling agent concentration is 0.001 to 1 g / L, and a mixed aqueous solution having a pH of 1 to 5 is used as a coolant. . The substrate is made of a heat-treatable aluminum alloy in which the substrate is an Al—Cu—Mg alloy (2000 series), an Al—Mg—Si alloy (6000 series), or an Al—Zn—Mg alloy (7000 series). The heating process itself is a solution treatment process for subjecting the substrate to a solution treatment, and the cooling process itself is a quenching process for subjecting the substrate on which the oxide film has been formed to a quenching process. preferable.

  According to such a procedure, in the method for producing a surface-treated aluminum alloy plate, an oxide film having a predetermined film thickness is formed on the surface of the substrate by performing a heating step of heating at a predetermined temperature, and the surface-treated aluminum alloy The strength of the board is adjusted. Moreover, in the manufacturing method of the surface treatment aluminum alloy plate, the surface formed on the surface of the oxide film is subjected to a cooling process of cooling with a predetermined mixed aqueous solution, and the film formed by performing the surface treatment is formed. It becomes the board provided. Moreover, in the manufacturing method of a surface treatment aluminum alloy plate, since the surface treatment liquid which does not contain a halogen and phosphorus is used as a cooling liquid in the cooling step, a production facility for treating halogen and phosphorus is not necessary. The impact on the environment is reduced and the environmental impact is reduced. As heat-treatable aluminum alloys, Al-Cu-Mg alloys (2000 series), Al-Mg-Si alloys (6000 series), and Al-Zn-Mg alloys (7000 series) are known.

The surface-treated aluminum alloy plate of the present invention is excellent in degreasing properties, chemical conversion properties, and adhesiveness, and can reduce the load on manufacturing equipment, and is excellent in environmental response.
In addition, the method for producing a surface-treated aluminum alloy plate according to the present invention produces a surface-treated aluminum alloy plate that is excellent in degreasing properties, chemical conversion treatment properties, and adhesiveness, and that can reduce the load on production equipment and is environmentally friendly. it can. Moreover, since the manufacturing method according to the present invention can omit the conventional acid cleaning and the like, the cost can be reduced.
Further, by adding a silane coupling agent to the treatment liquid, it is possible to further improve the adhesion in the manufactured surface-treated aluminum alloy plate.

It is sectional drawing which shows typically the structure of the surface treatment aluminum alloy plate which concerns on this invention. It is a process flow which shows the manufacturing method of the surface treatment aluminum alloy plate which concerns on this invention.

≪Surface treatment aluminum alloy sheet≫
Hereinafter, the surface-treated aluminum alloy plate according to the present invention will be specifically described with reference to FIG. As shown in FIG. 1, a surface-treated aluminum alloy plate 10 according to the present invention includes a substrate 1 and a film 2 formed on the surface of the substrate 1. As will be described later, in the manufacturing method, the film 2 is formed by first forming an oxide film, and then zirconium nitrate (formal name: zirconium dinitrate oxide, common name: zirconium oxynitrate) on the surface of the formed oxide film. , Zirconyl nitrate, zircon nitrate, etc.) and a mixed aqueous solution of a silane coupling agent (commercially available epoxy-based, amine-based and the like are not limited), and a surface treatment is performed together with cooling to form film 2 as a whole. I am doing so.
Here, the surface of the substrate 1 means at least one surface of the surface of the substrate 1 and includes a so-called front surface and back surface.
Hereinafter, each configuration of the surface-treated aluminum alloy plate will be described.

<Board>
The substrate 1 is made of an aluminum alloy, and the plate thickness is appropriately set according to the use of the surface-treated aluminum alloy plate 10. Also, the aluminum alloy used as the material of the substrate 1 is appropriately selected from various non-heat-treatable aluminum alloys or heat-treatable aluminum alloys specified by JIS or similar to JIS, depending on the use of the surface-treated aluminum alloy plate 10 Is done. Non-heat treatment type aluminum alloys are pure aluminum (1000 series), Al-Mn series alloys (3000 series), Al-Si series alloys (4000 series) and Al-Mg series alloys (5000 series). Aluminum alloys are an Al-Cu-Mg alloy (2000 series), an Al-Mg-Si alloy (6000 series), and an Al-Zn-Mg alloy (7000 series).

  As a specific example, when the surface-treated aluminum alloy plate is used for automobiles, it is preferably a high-strength substrate having a 0.2% proof stress of 100 MPa or more. As an aluminum alloy that constitutes a substrate satisfying such characteristics, it is a general-purpose alloy having a relatively high proof stress such as 5000 series, 6000 series, 7000 series, etc., which is generally used for this type of structural member application, A tempered aluminum alloy is preferably used if necessary. It is preferable to use a 6000 series aluminum alloy in terms of excellent age-hardening ability and a relatively small amount of alloying elements and excellent scrap recyclability and formability.

  As an example of a composition of a suitable aluminum alloy, Mg: 0.2-1.5 mass%, Si: 0.3-2.3 mass%, Cu: 1.0 mass% or less are contained, and further Ti: 0.1% by mass or less, B: 0.06% by mass or less, Be: 0.2% by mass or less, Mn: 0.8% by mass or less, Cr: 0.4% by mass or less, Fe: 0.5% by mass Hereinafter, an aluminum alloy containing at least one selected from Zr: 0.2% by mass or less and V: 0.2% by mass or less, with the balance being made of Al and inevitable impurities may be mentioned. The reasons for limiting the numerical value of each element are as follows.

(Mg: 0.2-1.5% by mass)
Mg has the effect of improving strength. When the Mg content is less than 0.2% by mass, the effect of improving the strength is small. On the other hand, if the Mg content exceeds 1.5% by mass, the moldability tends to decrease.

(Si: 0.3-2.3 mass%)
Si has an effect of improving strength. When the Si content is less than 0.3% by mass, the effect of improving the strength is small. On the other hand, if the Si content exceeds 2.3 mass%, the formability and hot rollability are likely to deteriorate.

(Cu: 1.0% by mass or less)
Cu has the effect of improving strength. However, if the Cu content exceeds 1.0% by mass, the corrosion resistance tends to decrease.

(Ti: 0.1 mass% or less, B: 0.06 mass% or less, Be: 0.2 mass% or less, Mn: 0.8 mass% or less, Cr: 0.4 mass% or less, Fe: 0.0. 5% by mass or less, Zr: 0.2% by mass or less, V: one or more selected from 0.2% by mass or less)

Ti has the effect of making the crystal grains of the ingot finer and improving the formability. However, if the Ti content exceeds 0.1% by mass, the formability tends to decrease due to the formation of coarse crystals.
B has the effect of making the crystal grains and crystallized matter of the ingot fine and improving the formability. However, if the content of B exceeds 0.06% by mass, the formability tends to decrease due to the formation of coarse crystals.

Be has the effect of improving hot rollability and formability. However, when the content of Be exceeds 0.2% by mass, the effect is saturated.
Mn, Cr, Fe, Zr, and V have the effect of improving strength. However, when the content exceeds 0.8% by mass, 0.4% by mass, 0.5% by mass, 0.2% by mass, and 0.2% by mass, respectively, formation of coarse crystallized products leads to molding. It becomes easy to fall.

  Inevitable impurities include Ca, Zn, Ni and the like.

<Composition of film>
The film 2 is formed on the surface of the substrate 1 with a predetermined thickness with a predetermined component in order to improve the degreasing property, reduce the unevenness of the chemical conversion treatment, and improve the adhesion. Here, the formation of the film 2 is performed by performing a surface treatment on the oxide film by a cooling process using a predetermined mixed aqueous solution after the oxide film is formed by the heating process, and the entire oxide film subjected to the surface treatment. The film 2 is formed. That is, the film 2 is a hybrid film that combines an oxide film formed on the surface of the substrate 1 and a surface treatment film formed on at least one of the surface and the inside of the oxide film.

(Film thickness)
This film 2 is formed on the substrate 1 with a film thickness in the range of 1 to 30 nm. When the film 2 has a film thickness of less than 1 nm, adsorption of ester components in the rust preventive oil and press oil is suppressed, and therefore, degreasing, chemical conversion and adhesiveness are ensured even without a surface treatment film. However, acid cleaning or the like is required to control the film thickness to less than 1 nm as a whole. Therefore, it is inferior in productivity and is not practical. On the other hand, when the film thickness is more than 30 nm, the surface is uneven due to the excessive film amount, resulting in chemical unevenness and chemical conversion processability. In addition, the suitable range of a film thickness is 10-20 nm.

  The film thickness of the film 2 is largely determined by the oxide film formed by the heating process described later. For this reason, surface treatment with a predetermined mixed aqueous solution used as a cooling liquid in the cooling process described later results in a state in which zirconium dioxide and silicon adhere to or enter the oxide film, and the majority is determined by the film thickness of the oxide film. It is done.

(Magnesium concentration)
The film 2 has a magnesium concentration in the range of 1 to 20 atomic%. When the substrate 2 contains a magnesium component, it is difficult to suppress the magnesium concentration to less than 1 atomic%, and processing for that is required. On the other hand, when the magnesium concentration exceeds 20 atomic%, the degreasing property, chemical conversion property, etc. cannot be ensured even if the treatment of the present invention using a predetermined mixed aqueous solution is performed. In addition, the suitable range of the magnesium concentration in the film 2 is 2 to 15 atomic%. Further, the magnesium concentration in the film 2 is controlled by the amount of magnesium contained in the substrate 1 and the manufacturing conditions. In particular, here, the amount of magnesium contained in the substrate 1 (0.2 to 1.5% by mass) is determined. The magnesium concentration of the film 2 is controlled in the range of 1 to 20 atomic% by controlling and the manufacturing method described later.

(Zirconium concentration)
The film 2 has a zirconium concentration in the range of 0.2 to 10 atomic%. When the zirconium concentration is less than 0.2 atomic%, the coating 2 cannot suppress the adsorption of the ester component in the press oil and cannot obtain desired performance such as degreasing and chemical conversion properties. On the other hand, when the zirconium concentration of the coating 2 is more than 10 atomic%, the surface has too much zirconium, and the chemical conversion treatment reaction is inhibited, resulting in chemical conversion treatment unevenness and chemical conversion treatment performance is lowered. In addition, the suitable range of a zirconium density | concentration is 0.4-8 atomic%. The zirconium concentration can be controlled by the concentration of zirconium nitrate in the mixed aqueous solution used in the cooling step described later.

(Silicon concentration)
The film 2 has a silicon concentration in the range of 2 to 10 atomic%. When the silicon concentration of the coating 2 is less than 2 atomic%, the adhesion of the coating is not strengthened and the desired performance with respect to adhesiveness cannot be obtained. On the other hand, when the silicon concentration is more than 10 atomic%, the coating 2 has too much silicon on the surface, and the chemical conversion treatment reaction is hindered, resulting in chemical conversion treatment unevenness and chemical conversion treatment performance is lowered. Further, the surface is easily contaminated and the degreasing property is lowered. In addition, the suitable range of silicon concentration is 4-8 atomic%. The silicon concentration can be controlled by the concentration of the silane coupling agent in the mixed aqueous solution used in the cooling step described later.

  The coating 2 has the above-described predetermined magnesium concentration, the above-described predetermined zirconium concentration, and the above-described predetermined silicon concentration, and does not contain halogen and phosphorus. For example, when halogen and phosphorus are measured, fluorine: less than 0.1 atomic%, chlorine: less than 0.1 atomic%, bromine: less than 0.1 atomic%, iodine: less than 0.1 atomic%, astatine: 0.0. Less than 1 atomic%, phosphorus: less than 0.1 atomic%. Furthermore, about halogen, the total of each element is also less than 0.1 atomic%. When the surface treatment film contains halogen, a load is imposed on the production equipment corresponding to the halogen. Moreover, when the surface treatment film contains phosphorus, precipitation tends to occur when the surface treatment liquid is drained, and the environment is likely to be contaminated.

  Further, the coating 2 contains the above elements (magnesium, zirconium, silicon, halogen, and phosphorus), and the balance consists of oxygen, aluminum, and impurities. Preferable contents of oxygen and aluminum are 20 to 65 atomic%, respectively. Impurities include C, Ca, Fe, Cu, Mn, Ti, Zn, Ni, etc. Content of less than 5 atomic percent is acceptable for C, and content of less than 0.5 atomic percent is acceptable for other impurities. The

  In addition, the oxide film formed by the heating process of the film 2 is an uneven porous film formed on the surface of the substrate 1. When the substrate 1 is made of a 6000 series alloy, magnesium oxide is the main component. It is a film to do. Here, the film thickness of the oxide film is 1 to 30 nm, and is controlled by the heating temperature in the manufacturing process (heating process) of the surface-treated aluminum alloy plate 10. When the film thickness of the oxide film is less than 1 nm, the adsorption of the ester component in the rust preventive oil and press oil is suppressed, so that the degreasing property, the chemical conversion property and the adhesiveness are ensured even without the surface treatment film, In order to control the film thickness to less than 1 nm, acid cleaning or the like is required. Therefore, it is inferior in productivity and is not practical. On the other hand, if the thickness of the oxide film exceeds 30 nm, the chemical conversion property cannot be ensured even if the film 2 is provided. The film thickness of the oxide film is preferably 10 to 20 nm.

  In addition, the surface treatment performed on the surface of the oxide film uses a predetermined mixed aqueous solution that does not contain halogen and phosphorus in the cooling step on the surface of the oxide film. It is done in. In the surface treatment, the zirconium concentration and the silicon concentration are controlled by the cooling conditions in the manufacturing process (cooling step) of the surface-treated aluminum alloy plate 10. If the zirconium concentration is less than 0.2 atomic% by the surface treatment, the uneven oxide film cannot be sufficiently covered, and even if the oxide film can be sufficiently covered, the Zr component in the oxide film is insufficient, so that the degreasing property is eliminated. , Chemical conversion processability and adhesiveness cannot be secured. On the other hand, when the zirconium concentration by the surface treatment exceeds 10 atomic%, the effect of improving the degreasing property is saturated, and the zirconium distribution tends to be non-uniform, which may reduce the chemical conversion treatment property. The zirconium concentration by the surface treatment is preferably 0.4 to 0.8 atomic%. In addition, when the silicon concentration is less than 2 atomic% by the surface treatment, the uneven oxide film cannot be sufficiently covered, and even if the oxide film can be sufficiently covered, the Si component in the oxide film is insufficient, Adhesion cannot be secured. On the other hand, when the silicon concentration by the surface treatment exceeds 10 atomic%, the effect of improving the adhesiveness is saturated, and the silicon distribution is likely to be non-uniform, so that the chemical conversion treatment property may be lowered and the degreasing property is decreased. May also decrease. Further, the silicon concentration by the surface treatment is preferably 4 to 8 atomic%.

<Element concentration and film thickness measurement method in film>
The element concentration (magnesium concentration, zirconium concentration, silicon concentration, concentration of halogen, phosphorus, etc.) in the film 2 on the surface of the surface-treated aluminum alloy plate 10 is GD-OES (Glow Discharge Optical Emission Spectroscopy). )), And after measuring the film thickness of the coating 2, the average value of the predetermined element concentrations can be calculated in the depth profile. GD-OES can also measure the film thickness of the film 2. That is, the depth at the half value of the maximum zirconium concentration in the depth direction profile measured by GD-OES can be used as the thickness of the film. In addition, it cannot be overemphasized that element concentration and a film thickness can be made into the average value of the several measurement result in the membrane | film | coat 2 surface.

  In addition, the element concentration and film thickness measurement methods are not particularly limited to GD-OES as long as they have the same accuracy as GD-OES, and are not limited to GD-OES. AES (Auger electron spectroscopy), XPS (X-ray photoelectron spectroscopy) ) Etc. For the zirconium concentration by the surface treatment, the same measurement method as that for the magnesium concentration and the silicon concentration can be used. The zirconium concentration can also be determined from the zirconium dioxide concentration of the coating 2. In other words, the zirconium dioxide concentration is obtained, and the zirconium concentration is obtained from the obtained zirconium dioxide by a predetermined calculation.

≪Method for producing surface-treated aluminum alloy sheet≫
Next, the manufacturing method of the surface treatment aluminum alloy plate which concerns on this invention is demonstrated with reference to FIG. In addition, refer to FIG. 1 for the configuration of the surface-treated aluminum alloy plate.

The manufacturing method of the surface treatment aluminum alloy plate 10 includes a substrate manufacturing step S1, a heating step S2, and a cooling step S3. And the heating temperature in heating process S2 and the density | concentration and pH of the predetermined element in the mixed aqueous solution in cooling process S3 are prescribed | regulated.
Hereinafter, each step will be described.

<Substrate manufacturing process>
The substrate manufacturing step S1 is a step of manufacturing the substrate 1 by rolling. Specifically, it is preferable to produce the substrate 1 by the following procedure.

  An aluminum alloy having a predetermined composition is melted and cast by continuous casting to produce an ingot (melting casting step), and the produced ingot is subjected to homogenization heat treatment (homogenization heat treatment step). Next, the ingot subjected to the homogenization heat treatment is hot-rolled to produce a hot-rolled sheet (hot-rolling step). Next, the hot-rolled sheet is subjected to rough annealing or intermediate annealing at 300 to 580 ° C., and cold-rolling at a final cold rolling rate of 5% or more is performed at least once to obtain a cold-rolled sheet having a predetermined thickness (substrate 1). Is manufactured (cold rolling process). By setting the temperature of rough annealing or intermediate annealing to 300 ° C. or higher, the effect of improving the moldability is more exhibited, and by setting it to 580 ° C. or lower, it becomes easy to suppress a decrease in moldability due to the occurrence of burning. By making the final cold rolling rate 5% or more, the effect of improving the formability is more exhibited. In addition, the conditions of homogenization heat processing and hot rolling are not specifically limited, The conditions in the case of obtaining a hot rolled sheet normally may be sufficient. Further, intermediate annealing may not be performed.

<Heating process>
The heating step S2 is a step of heating the substrate 1 to 400 to 580 ° C. to form an oxide film on the surface of the substrate 1. Moreover, heating process S2 is also a process of adjusting the intensity | strength of the surface treatment aluminum alloy plate 10. FIG. The heating step S2 is preferably rapid heating at a heating rate of 100 ° C./min or more.

  The heating step S2 is a solution treatment step when the substrate 1 is made of a heat-treatable aluminum alloy. When the substrate 1 is made of a non-heat-treatable aluminum alloy, the heating step S2 is performed in the annealing step (final annealing step). It is a process.

(Heating temperature: 400-580 ° C)
By rapid heating to a heating temperature of 400 ° C. or higher, the strength of the surface-treated aluminum alloy plate 10 and the strength after heating (baking) of the surface-treated aluminum alloy plate 10 are further increased. By rapidly heating to a heating temperature of 580 ° C. or less, a decrease in moldability due to the occurrence of burning is suppressed. Further, by heating at a heating temperature of 400 to 580 ° C., an oxide film having a predetermined film thickness (1 to 30 nm) is formed on the surface of the substrate 1. In addition, from the viewpoint of improving the strength, the holding time is preferably 3 to 30 seconds.

<Cooling process>
The cooling step S3 is a step in which the substrate 1 on which the oxide film is formed is cooled and the surface treatment is performed on the surface of the oxide film, that is, the cooling treatment and the surface treatment are performed simultaneously. In addition, it is preferable that the cooling step S3 is rapidly cooled to 100 ° C. at a cooling rate of 100 ° C./min or more. By setting the cooling rate to 100 ° C. at 100 ° C./min or more, a decrease in moldability is further suppressed, and the strength after baking becomes higher.

  The cooling step S3 is a quenching step when the substrate 1 is made of a heat-treatable aluminum alloy, and when the substrate 1 is made of a non-heat-treatable aluminum alloy, the cooling step in the annealing step (final annealing step). It is.

  In the cooling step S3, as the cooling liquid, the halogen concentration and the phosphorus concentration are each less than 0.1 atomic%, that is, no halogen and phosphorus are contained, the zirconium nitrate concentration is 0.005 to 5 g / L, and the silane coupling agent A mixed aqueous solution having a concentration of 0.001 to 1 g / L and a pH of 1 to 5 is used. In the cooling step S3, the cooling time is preferably 1 to 30 seconds. In the cooling step S3, for example, the substrate 1 is cooled by spraying the mixed aqueous solution by showering or spraying the substrate 1 on which the oxide film is formed, or by allowing the mixed aqueous solution to pass therethrough. I am doing so.

(Halogen concentration and phosphorus concentration are each less than 0.1 atomic% (does not contain halogen and phosphorus))
In the present invention, the mixed aqueous solution as the cooling liquid has a halogen concentration and a phosphorus concentration of less than 0.1 atomic%, that is, does not contain halogen and phosphorus, as described above. When phosphorus and phosphorus are measured, it means that they cannot be measured, that is, less than the measurement limit. And when a cooling fluid contains a halogen, a load is applied to manufacturing equipment. Further, when the cooling liquid contains phosphorus, precipitation is likely to occur when the surface treatment liquid is drained, and the environment is easily contaminated.

(Zirconium nitrate concentration: 0.005 to 5 g / L)
By using a mixed aqueous solution having a predetermined concentration of zirconium nitrate as the cooling liquid, the zirconium concentration of the coating 2 falls within a predetermined range (0.2 to 10 atomic%) by performing surface treatment. When the concentration of zirconium nitrate in the mixed aqueous solution is less than 0.005 g / L, the zirconium concentration by the surface treatment is small (less than 0.2 atomic%), and the surface treatment aluminum alloy sheet 10 has a degreasing property, a chemical conversion treatment property, and an adhesion property. It cannot be secured. On the other hand, when the concentration of zirconium nitrate in the mixed aqueous solution exceeds 5 g / L, the zirconium concentration by the surface treatment is large (zirconium concentration exceeds 10 atomic%), and the effect of improving degreasing, chemical conversion treatment, and adhesiveness is saturated. . Moreover, chemical conversion processability falls. The concentration of zirconium nitrate in the mixed aqueous solution is preferably 0.05 to 0.5 g / L.

(Silane coupling agent concentration: 0.001 to 1 g / L)
By using a mixed aqueous solution in which the silane coupling agent has a predetermined concentration as the cooling liquid, the silicon concentration of the film 2 falls within a predetermined range (2 to 10 atomic%) by performing the surface treatment. When the concentration of the silane coupling agent is less than 0.001 g / L, the silicon concentration by the surface treatment is small (less than 2 atomic%), and the adhesion of the surface-treated aluminum alloy plate 10 cannot be ensured. On the other hand, when the concentration of the silane coupling agent exceeds 1 g / L, the silicon concentration by the surface treatment is large (the silicon concentration exceeds 10 atomic%), and the degreasing and chemical conversion treatment properties are deteriorated. In addition, the drug cost increases. The concentration of the silane coupling agent is preferably 0.01 to 0.1 g / L.

(PH: 1-5)
When the pH of the mixed aqueous solution as the cooling liquid is less than 1, the surface treatment cannot be properly performed, and the degreasing property, the chemical conversion property and the adhesiveness of the surface-treated aluminum alloy plate 10 cannot be ensured. On the other hand, when the pH exceeds 5, the stability of the cooling liquid is lowered and precipitation is likely to occur in the cooling liquid. If precipitation occurs in the coolant, the precipitate is pushed into the surface of the surface-treated aluminum alloy plate 10 as a foreign substance, resulting in poor appearance. As for pH of the mixed aqueous solution as cooling water, 2-4 are preferable.

  Thus, in the cooling step, the mixed aqueous solution is used as a cooling liquid, and the heated substrate 1, that is, the substrate 1 having an oxide film formed on the surface is cooled and surface-treated, thereby performing acid cleaning or the like. There is no need to remove the oxide film on the surface. Therefore, it is not necessary to perform acid cleaning or the like that is conventionally performed, and a line for acid cleaning or the like can be omitted. Furthermore, since the cooling treatment and the surface treatment can be performed in the same process, the manufacturing cost can be further reduced.

The method of manufacturing the surface-treated aluminum alloy plate 10 is as described above. However, when the surface-treated aluminum alloy plate 10 is manufactured, the process is performed between or before and after each step as long as the steps are not adversely affected. Other steps may be included. For example, a preliminary aging treatment step of performing a preliminary aging treatment after the cooling step may be provided. The preliminary aging treatment is preferably performed by heating at 40 to 120 ° C. for 8 to 36 hours at a low temperature within 72 hours. By performing the pre-aging treatment under these conditions, it is possible to improve moldability and strength after baking.
In addition, for example, a foreign matter removing step for removing foreign matter on the surface of the surface-treated aluminum alloy plate 10 and a defective product removing step for removing defective products generated in each step may be included.

And the surface treatment aluminum alloy plate 10 manufactured is apply | coated with press oil before shaping | molding. As the press oil, one containing an ester component is mainly used.
Next, a method for applying press oil to the surface-treated aluminum alloy plate 10 according to the present invention will be described.
As a method for applying the press oil, for example, the surface-treated aluminum alloy plate 10 may be simply immersed in a press oil containing ethyl oleate as an ester component. The method and conditions for applying the press oil containing the ester component are not particularly limited, and general methods and conditions for applying the press oil can be widely applied. Further, the ester component is not limited to ethyl oleate, and various materials such as butyl stearate and sorbitan monostearate can be used.

  Next, the surface-treated aluminum alloy sheet of the present invention will be specifically described by comparing an example that satisfies the requirements of the present invention with a comparative example that does not satisfy the requirements of the present invention.

  The surface-treated aluminum alloy sheet has a component of A as 6022 standard (Si: 0.8 to 1.5 mass%, Mg: 0.45 to 0.7 mass%, Cu: 0.01 to 0.11 mass) %), B as 6016 standard (Si: 1.0 to 1.5 mass%, Mg: 0.25 to 0.6 mass%, Cu: 0.2 mass%), and C as 6111 standard (Si: 0.6-1.1% by mass, Mg: 0.5-1.0% by mass, Cu: 0.5-0.9% by mass) using three types of 6000 series aluminum alloy plates, A substrate having a size of 25 mm width × 100 mm length × 1 mm thickness was produced by the manufacturing method (see Table 1).

Next, this base material was heated to an actual temperature of 480 to 580 ° C., and was heated to room temperature, and nitric acid was added to adjust the pH to 2 to 4, and the zirconium nitrate concentration was 0.05 to 0.00. After being immersed and cooled in a mixed aqueous solution of 5 g / L and a silane coupling agent concentration of 0.01 to 0.1 g / L for 5 to 20 seconds, washed with water and dried to form an oxide film on both sides, and surface treatment A surface-treated aluminum alloy plate was prepared. On both surfaces of this surface-treated aluminum alloy plate, 0.1 to ² g / m ² of a commercially available automotive cleaning press oil (mineral oil type, kinematic viscosity 1 to 7 cSt) was applied as a test material.
However, as described below, the manufacturing conditions were appropriately changed as described below. In this way, test materials (No. 1 to 24) were produced.

In the preparation of the test materials (Nos. 1 to 12), the heating temperature (substance temperature) of the substrate, the zirconium nitrate concentration and the silane coupling agent concentration of the mixed aqueous solution, and the contact time of the mixed aqueous solution are appropriately within the above ranges. It was adjusted. The specimen (No. 13) was not cooled by the mixed aqueous solution (surface treatment), was cooled by water cooling, and the surface treatment of the present invention was not performed.
Specimen No. No. 14 was treated with a mixed aqueous solution having a heating temperature of 590 ° C., a zirconium nitrate concentration of 0.05 g / L, and a silane coupling agent concentration of 0.01 g / L.
Specimen No. No. 15 was treated using a mixed aqueous solution having a heating temperature of 500 ° C., a zirconium nitrate concentration of 0.004 g / L, and a silane coupling agent concentration of 0.05 g / L.

About the test material (No. 16, 17), the acid cleaning and the strong acid cleaning were performed after the heat treatment, and the surface treatment of the present invention was not performed.
For the sample material (No. 18), the heating temperature was 500 ° C., and an aqueous solution of aluminum dihydrogen phosphate having a concentration of 0.5 g / L was used instead of the mixed aqueous solution.
Specimen No. No. 19 was treated using a mixed aqueous solution having a heating temperature of 500 ° C., a zirconium nitrate concentration of 6 g / L, and a silane coupling agent concentration of 0.05 g / L.
Specimen No. No. 20 was treated using a mixed aqueous solution having a heating temperature of 590 ° C., a zirconium nitrate concentration of 1 g / L, and a silane coupling agent concentration of 0.05 g / L.

Specimen No. For No. 21, surface treatment was performed with a halogen-containing Zr-based aqueous solution having a concentration of 10 g / L. Here, the treatment is performed at room temperature in consideration of the environment and the load on the facility, etc., while the concentration is set higher in consideration of the reactivity.
Specimen No. No. 22 was treated with a mixed aqueous solution having a heating temperature of 500 ° C., a zirconium nitrate concentration of 0.3 g / L, and a silane coupling agent concentration of 0.0008 g / L.
Specimen No. For No. 23, the treatment was performed using a mixed aqueous solution having a heating temperature of 500 ° C., a zirconium nitrate concentration of 0.3 g / L, and a silane coupling agent concentration of 1.2 g / L.
Specimen No. For No. 24, the treatment was performed using an aqueous solution having a heating temperature of 500 ° C. and a zirconium nitrate concentration of 0.3 g / L.

  With respect to the test material obtained as described above, the film thickness of the film and the contents of Mg, Zr, Si, halogen, and P were determined by high-frequency glow discharge optical emission spectrometry (GD-OES (manufactured by Horiba Joban Yvon, Model JY-5000RF)). The results are shown in Table 1. When the total content of Mg, Zr, Si, halogen, and P does not reach 100 atomic%, O, Al, and a small amount of impurities are included. Moreover, "-" in a table | surface shows the thing which does not contain a component or cannot measure.

  The films of the test materials (No. 1 to 12, 13 to 17, 19, 20, 22 to 24) contained neither halogen nor phosphorus. The film by the surface treatment of the test material (No. 18) contained no halogen, and the average value of the phosphorus content in the depth profile of the film was 9 atomic%. In addition, specimen No. In No. 21, the film formed by the surface treatment did not contain phosphorus, but contained 0.7 atomic% of halogen.

Next, the following evaluations were performed using the above-described test materials. The results are shown in Table 1.
<Degreasing (Water wetted area ratio)>
Each specimen was left for 6 months in an environmental chamber of 50 to 90% RH at 15 to 35 ° C. After 6 months, the water wetted area ratio (front and back) with respect to the area of the test material after being immersed in a carbonated sodium carbonate degreasing bath for commercial vehicles at 40 ° C. for 2 minutes (with stirring by a stirrer) and washed for 30 seconds (running water) (The average of) was measured (the better, the higher the value, and 100% when completely wetted). Thereby, the water wettability at the time of a chemical conversion treatment, ie, a degreasing property, can be evaluated. Each test material was made into 3 sheets, respectively, and the water-wetting area rate was made into the average value of these. The initial value before being held in the humid environment chamber was 100%. Degreasability was judged to be poor when the water leakage area ratio was 80% or more, and the degreasing property was good, and less than 80%.

<Chemical conversion processability (presence or absence of chemical conversion process unevenness)>
Each test material was immersed in a sodium carbonate-based degreasing bath at 40 ° C. for 2 minutes (with stirring by a stirrer) to degrease the surface of the test material. Next, after immersing in a zinc-based surface conditioning bath at room temperature for 1 minute (with stirring by a stirrer), it was immersed in a 35 ° C. zinc phosphate bath (with stirring by a stirrer) for 2 minutes to subject the sample surface to chemical conversion treatment. . And the chemical conversion treatment nonuniformity which generate | occur | produces on the surface of the test material after chemical conversion treatment was observed visually, and chemical conversion property was evaluated. In the evaluation of chemical conversion treatment, those with no occurrence of chemical conversion treatment are marked as `` None '' in the table, and those with good chemical conversion treatment and chemical conversion treatment unevenness are marked with `` Yes '' in the table. Therefore, the chemical conversion processability was poor.

<Adhesiveness (cohesive failure rate)>
The end portions of two test materials (25 mm width) having the same configuration are wrapped with a thermosetting epoxy resin adhesive (manufactured by Sunstar Giken Co., Ltd., Penguin Cement # 1086) with a wrap length of 13 mm (bonding area: 25 mm × 13 mm = 325 mm ² ). Note that a small amount of glass beads (particle size: 150 μm) was added to the adhesive to adjust the thickness of the adhesive layer to 150 μm. It was dried at room temperature for 30 minutes after being superposed, and then heated at 170 ° C. for 20 minutes to cure the adhesive. Then, it left still at room temperature for 24 hours, and was set as the adhesion test body.

The obtained adhesion test specimen was held in a humid atmosphere of 50 ° C. and 95% RH for 15 days, and then pulled at a rate of 50 mm / min with a tensile tester. The cohesive failure rate (non-interface peeling rate) of the adhesive layer was calculated. The cohesive failure rate was an average value of three adhesion test specimens. Moreover, in Formula (1), let one of the adhesion test bodies be the test piece A and the other be the test piece B. A material having a cohesive failure rate of 80% or more was considered to have good adhesion, and a material having a cohesive failure rate of less than 80% was considered to have poor adhesion.
Cohesive failure rate (%) = 100 − {(interface peel area of test piece A / bonding area of test piece A) × 1
00} + {(interface peel area of test piece B / bonding area of test piece B) × 100} (1)

As shown in Table 1, the test material No. Since 1-12 (Example) satisfy | fills the structure of this invention, the degreasing | defatting property, chemical conversion treatment property, and adhesiveness were favorable.
On the other hand, the test material No. Since 13-24 (comparative example) did not satisfy the configuration of the present invention, the following results were obtained.

  Specimen No. Since No. 13 was not surface-treated, the degreasing property, the chemical conversion property and the adhesiveness were poor. Specimen No. In No. 14, the film thickness of the film exceeded the upper limit value, so the chemical conversion treatment was poor. Specimen No. No. 15 had poor degreasing properties, chemical conversion properties, and adhesiveness because the zirconium concentration of the coating by surface treatment was less than the lower limit. Specimen No. No. 16, the film thickness of the film was within the range of the present invention, but the magnesium concentration is a relatively low pickling material, and since the surface treatment of the present invention was not performed, the zirconium concentration and the silicon concentration could not be measured, Adhesion was poor.

Specimen No. No. 17 is obtained by performing strong acid cleaning which is a stronger cleaning in which the magnesium concentration is less than the lower limit value and the zirconium concentration and the silicon concentration cannot be measured. Since the film thickness of the oxide film is less than the lower limit value, the degreasing property, the chemical conversion treatment property and the adhesiveness are good, but since the strong acid cleaning was performed, the productivity was inferior. Therefore, the test material No. The surface-treated aluminum alloy sheet according to No. 17 was not economical and not suitable for practical use.
Specimen No. No. 18 used an aqueous solution of aluminum dihydrogen phosphate as the cooling liquid, and therefore had good degreasing properties and chemical conversion properties, but had poor adhesion. Further, the cooling liquid was liable to precipitate, and the drainage processability was poor.

Specimen No. No. 19 had poor chemical conversion properties because the zirconium concentration exceeded the upper limit. Specimen No. No. 20 had poor degreasing properties, chemical conversion properties and adhesiveness because the magnesium concentration exceeded the upper limit.
Specimen No. No. 21 was surface-treated with a halogen-containing Zr system, so that the degreasing property, chemical conversion property and adhesiveness are good, but the environment and equipment load increase. Therefore, the test material No. The surface-treated aluminum alloy plate according to No. 21 was not economical and not suitable for practical use.

  Specimen No. No. 22 had poor adhesion because the silicon concentration was less than the lower limit. Specimen No. No. 23 had poor degreasing and chemical conversion properties because the silicon concentration exceeded the upper limit. Specimen No. Since No. 24 did not contain silicon, its adhesiveness was poor.

  As described above, the surface-treated aluminum alloy plate and the manufacturing method thereof according to the present invention have been described in detail with reference to the embodiments and examples, but the gist of the present invention is not limited to the above-described contents, It should be interpreted based on the description of the claims. Needless to say, the contents of the present invention can be modified and changed based on the above description.

1 Substrate 2 Coating 10 Surface-treated aluminum alloy plate

Claims (3)

A surface-treated aluminum alloy plate comprising a substrate made of an aluminum alloy containing magnesium and an oxide film formed on the surface of the substrate,
The oxide film has a thickness of 1 to 30 nm, a magnesium concentration of 1 to 20 atomic%, a zirconium concentration of 0.2 to 10 atomic%, a silicon concentration of 2 to 10 atomic%, a halogen concentration and a phosphorus concentration, respectively. A surface-treated aluminum alloy sheet characterized by being less than 0.1 atomic%. It is a manufacturing method of the surface treatment aluminum alloy plate according to claim 1,
A substrate production step of producing the substrate by rolling;
Heating the substrate to 400-580 ° C. to form an oxide film on the surface of the substrate;
Cooling the substrate on which the oxide film is formed, and a cooling step of performing a surface treatment on the surface of the oxide film,
In the cooling step, the halogen concentration and the phosphorus concentration are each less than 0.1 atomic%, the zirconium nitrate concentration is 0.005 to 5 g / L, and the silane coupling agent concentration is 0.001 to 1 g / L. A method for producing a surface-treated aluminum alloy plate, wherein a mixed aqueous solution having a pH of 1 to 5 is used as a cooling liquid. The substrate is made of a heat-treatable aluminum alloy that is an Al—Cu—Mg alloy (2000 series), an Al—Mg—Si alloy (6000 series), or an Al—Zn—Mg alloy (7000 series), The heating process itself is a solution treatment process for subjecting the substrate to a solution treatment, and the cooling process itself is a quenching process for quenching the substrate on which the oxide film is formed. The manufacturing method of the surface treatment aluminum alloy plate of Claim 2.

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