JP2016211012A - Aluminum alloy sheet for packaging containers - Google Patents

Abstract

An aluminum alloy plate for packaging containers having excellent corrosion resistance and adhesion after formation of a resin film is provided.
[Solution]
An Al alloy plate 1 for a packaging container, which is formed in a coil shape and formed by chemical conversion treatment containing Zr and phosphoric acid while continuously passing an Al alloy plate 2 containing Mg, and forming the chemical conversion film 3. 3 is formed by performing a degreasing treatment with an aqueous solution containing a surfactant and an etching treatment with an alkaline aqueous solution having a pH of more than 11, followed by a chemical conversion treatment with a Zr chemical conversion solution having a nitric acid concentration of 250 to 4000 ppm. Furthermore, the ratio of the content of Mg and Zr in the chemical conversion film 3 calculated from the content of Mg contained in the Al alloy plate 2 is 0.01 to 8 in terms of Mg / Zr. 0.5, and the coating amount of the chemical conversion film 3 is characterized in that Zr is 0.5 to 20 mg / m ² and phosphorus is 0.1 to 7 mg / m ² .
[Selection] Figure 1

Description

  The present invention relates to an aluminum alloy plate for packaging containers.

  Aluminum alloy plates are not only lightweight and have an appropriate strength, but also are not toxic, and are excellent in processability and recyclability, and are therefore widely used in beverage and food packaging containers.

  Aluminum alloy plates for packaging containers used as packaging containers for beverages and foodstuffs are generally subjected to chemical conversion treatment to improve the corrosion resistance and adhesion after the resin film is formed, and the surface of the aluminum alloy plate A chemical conversion film is formed. Conventionally, a chromate conversion coating has often been formed as a conversion coating. However, in recent years, chromate conversion coatings have been avoided from the viewpoint of environmental protection, and non-chromate conversion coatings that do not use chromium are often formed instead.

  As the non-chromate chemical conversion film, for example, there is a zirconium chemical conversion film formed by zirconium chemical conversion treatment. However, the corrosion resistance and adhesion after the formation of the resin film in the aluminum alloy plate on which the zirconium conversion film is formed tend to be inferior compared to those in which the chromate conversion film is formed.

For example, Patent Documents 1 and 2 disclose an invention aimed at forming a zirconium chemical conversion film having excellent corrosion resistance and adhesion after formation of a resin film.
Specifically, in Patent Document 1, a zirconium compound is converted to 2 to 20 mg / m ^{2 in} terms of zirconium atoms, a phosphorus compound is converted to 1 to 10 mg / m ^{2 in} terms of phosphorus atoms on at least one surface of an aluminum alloy plate, A resin-coated seamless aluminum can that has an organic-inorganic composite surface treatment layer containing an organic compound in an amount of 5 to 60 mg / m ^{2 in} terms of carbon atoms, and further has a thermoplastic resin layer thereon, and is excellent in corrosion resistance and adhesion. Has been.

  Further, in this Patent Document 1, it is preferable that a step of washing the aluminum alloy plate with an acid is performed first before the treatment of the aluminum alloy plate is performed, and further, before the step of washing with an acid, the aluminum alloy plate is performed. It is preferable that the step of washing with alkali is performed, and the most preferable aspect is described as a method of sequentially performing each step of alkali washing → water washing → acid washing → water washing → non-chromium metal surface treatment → water washing → drying. .

Patent Document 2 includes a base material made of an aluminum plate or an aluminum alloy plate, a chemical conversion film formed on at least one surface of the base material, and a resin coating film formed on the chemical conversion film. There is described a resin-coated aluminum plate, which is a resin-coated aluminum plate, wherein the amount of aluminum hydrated oxide contained in the chemical conversion film is 100 mg / m ² or less.

JP 2007-76012 A JP 2007-107033 A

According to the inventions disclosed in Patent Documents 1 and 2, improvement in corrosion resistance and adhesion after formation of a resin film in an aluminum alloy sheet on which a zirconium chemical conversion film is formed is being achieved.
However, development of an aluminum alloy plate for a packaging container that is further excellent in corrosion resistance and adhesion after formation of a resin film is desired from the industrial world.

  This invention is made | formed in view of such a condition, and makes it a subject to provide the aluminum alloy plate for packaging containers excellent in the corrosion resistance after resin film formation and adhesiveness.

The aluminum alloy plate for packaging containers according to the present invention that has solved the above problems is coiled, and a chemical conversion film containing zirconium and phosphoric acid is formed by continuously forming an aluminum alloy plate containing magnesium and forming a chemical conversion film. An aluminum alloy plate for a packaging container, wherein the chemical conversion film is subjected to a degreasing treatment with an aqueous solution containing a surfactant and an etching treatment with an alkaline aqueous solution having a pH of more than 11, followed by a nitric acid concentration of 250 ppm or more. Magnesium and zirconium contents in the chemical conversion film formed by chemical conversion treatment with a zirconium chemical conversion solution of 4000 ppm or less and calculated from the magnesium content contained in the aluminum alloy plate The Mg / Zr ratio is 0.01 or more and 8.5 or less, and the amount of the chemical conversion film , Zirconium 0.5 mg / m ² or more 20 mg / m ² or less, and with it the phosphorus is 7 mg / m ² or less 0.1 mg / m ² or more.

  Thus, since the aluminum alloy plate for packaging containers according to the present invention is degreased with an aqueous solution containing a surfactant, oil on the surface of the aluminum alloy plate can be removed. Therefore, the subsequent surface treatment is improved, and the finish (appearance) can be made beautiful. Moreover, since the aluminum alloy plate for packaging containers according to the present invention is etched with an alkaline aqueous solution having a pH of more than 11, a dense oxide film on the surface of the aluminum alloy plate can be removed and the surface roughness can be reduced. Can be high. Therefore, the adhesiveness after resin film formation improves. Furthermore, the aluminum alloy plate for packaging containers according to the present invention is formed by performing chemical conversion treatment with a zirconium chemical conversion treatment solution having a nitric acid concentration in the above range after being sequentially processed as described above, while removing smut. A film can be formed. That is, the chemical conversion film can be formed by omitting the desmutting treatment. Furthermore, since this chemical conversion treatment also has an effect of roughening the surface of the aluminum alloy plate, it is possible to improve the adhesion after the resin film is formed. And the aluminum alloy plate for packaging containers which concerns on this invention performs the above-mentioned chemical conversion treatment, the ratio (Mg / Zr) of the content of magnesium and zirconium in a chemical conversion film is made into a predetermined range, and a chemical conversion film Since the amount of the film can be set to a predetermined condition, the film can be excellent in corrosion resistance and adhesion.

  In the aluminum alloy plate for packaging containers according to the present invention, it is preferable that a resin film having a thickness of 1 μm or more and 25 μm or less is formed on the chemical conversion film.

  As described above, the aluminum alloy sheet for packaging containers according to the present invention is superior in corrosion resistance and adhesion after the resin film is formed because the resin film having a thickness of 1 μm or more and 25 μm or less is formed on the chemical conversion film. It can be.

  In the aluminum alloy plate for a packaging container according to the present invention, the resin film is composed of one or more layers using at least one of a paint, a primer, and a film, and the resin film is a polyester resin, and It is preferably formed using at least one of epoxy resins.

  Thus, since the aluminum alloy plate for packaging containers according to the present invention has the resin film as described above, it can be surely excellent in corrosion resistance and adhesion after the resin film is formed.

  The aluminum alloy plate for packaging containers according to the present invention is subjected to a chemical conversion treatment under a predetermined condition after performing a predetermined treatment to form a chemical conversion film having a predetermined film amount. Therefore, the aluminum alloy plate for packaging containers according to the present invention can be excellent in corrosion resistance and adhesion after the resin film is formed.

It is the schematic explaining each process and structure which are performed with respect to the aluminum alloy plate for packaging containers which concerns on 1st Embodiment of this invention. It is the schematic explaining the preferable aspect of 1st Embodiment of this invention. It is the schematic explaining each process and structure which are performed with respect to the aluminum alloy plate for packaging containers which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of an aluminum alloy plate for packaging containers according to the present invention will be described in detail with reference to the drawings as appropriate.

[Aluminum alloy sheet for packaging containers]
(First embodiment)
FIG. 1 is a schematic diagram illustrating each process and configuration performed on an aluminum alloy plate for packaging containers according to the first embodiment of the present invention.
As shown in FIG. 1, an aluminum (Al) alloy plate 1 for a packaging container according to a first embodiment of the present invention includes an Al alloy plate 2 serving as a base material and a chemical conversion formed on the surface of the Al alloy plate 2. And coating 3.
In addition, although the aspect which formed the chemical conversion film 3 only in the single side | surface of the Al alloy plate 2 is shown in FIG. 1, you may form the chemical conversion film 3 in both surfaces of the Al alloy plate 2 (not shown). ).

(Packaging container)
Here, the packaging container should just be what can accommodate a drink or foodstuff inside, and the thing of what kind of aspect is contained. Examples of the packaging container include a two-piece can, a three-piece can, and a so-called new bottle can. The 2-piece can refers to a can composed of two parts, a can body obtained by DI (Drawing and Ironing) molding and a can lid. A three-piece can refers to a can composed of three parts: a can body, a can lid, and a can bottom. Moreover, a new bottle can means the can comprised by the cap, the can body, and the can bottom. The Al alloy plate 1 for packaging containers according to the present embodiment is particularly suitable as a plate material used for these cans. Note that the manner of the packaging container is arbitrarily set according to the user's request, and other embodiments can be adopted. Further, the shape of the packaging container can be a substantially cylindrical shape, but can also be a rectangular tube shape or the like.

(Al alloy plate)
As the Al alloy plate 2, any material can be used as long as it contains magnesium (Mg) as a chemical component. For example, as the Al alloy plate 2, 3000 series (Al-Mn series), 5000 series (Al-Mg series) defined in JIS H 4000: 2014 can be suitably used, but it is not limited thereto. Any material can be used as long as it is an Al alloy plate formed of 2000 series to 8000 series Al alloy and contains Mg. Of the 3000 series, 3004, 3014 and the like can be suitably used for the can lid and bottom, and among the 5000 series, 5052, 5082, 5182 and the like can be suitably used for the can body.

(Chemical conversion film)
As shown in FIG. 1, the Al alloy plate 1 for a packaging container is formed by applying a chemical conversion treatment containing zirconium (Zr) and phosphoric acid while continuously passing a coiled Al alloy plate 2. Formed.
As shown in FIG. 1, the chemical conversion film 3 is formed by performing a chemical conversion treatment after sequentially performing a predetermined degreasing treatment and an etching treatment.

(Degreasing treatment)
In the degreasing treatment, the surface of the Al alloy plate 2 is degreased with an aqueous solution (degreasing treatment liquid) containing a surfactant. In this way, oil on the surface of the Al alloy plate 2 can be removed, so that the subsequent surface treatment is improved and the finish is beautiful (that is, the appearance of the Al alloy plate 1 for packaging containers is excellent). ) In addition, if oil remains on the surface of the Al alloy plate 2, the surface treatment agent and the Al alloy plate 2 do not come into contact with each other. This causes a decrease in the reactivity of the chemical conversion treatment and a poor appearance, but the degreasing treatment is performed. Therefore, such a problem can be prevented.

  On the other hand, when such a degreasing treatment is not performed, the above-described effects cannot be obtained, so that not only the appearance of the Al alloy plate 1 for packaging containers is deteriorated, but also the corrosion resistance after the formation of the resin film 4 (see FIG. 3). In addition, the adhesion also deteriorates. The resin film 4 will be described later.

Most preferably, as a degreasing treatment liquid containing a surfactant, there can be mentioned Surf Cleaner EC370 manufactured by Nippon Paint Co., but is not limited thereto. The processing conditions for the degreasing treatment when using Nippon Paint Surf Cleaner EC370 as a degreasing solution containing a surfactant include, for example, a concentration of 2 to 3%, a temperature of 60 to 70 ° C., and a treatment time of 3 to 10 seconds. To do.
The concentration of the surfactant in the aqueous solution containing the surfactant and the treatment conditions (for example, the treatment time and the treatment temperature) may be set as long as the surface of the Al alloy plate 2 can be degreased.

(Etching process)
In the etching process, the surface of the Al alloy plate 2 is etched with an alkaline aqueous solution having a pH exceeding 11. In this way, since the dense oxide film on the surface of the Al alloy plate 2 is removed, the reactivity of the subsequent processing is improved. Therefore, the corrosion resistance after the formation of the resin film 4 (see FIG. 3) can be improved. Moreover, since surface roughness becomes high by performing this etching process, the adhesiveness of the chemical conversion film 3 and the resin film 4 formed on the said chemical conversion film 3 can be improved.

On the other hand, when such an etching process is not performed, the above-described effects cannot be obtained, and thus the corrosion resistance and adhesion after the formation of the resin film 4 are deteriorated.
In addition, in an alkaline aqueous solution having a pH of 11 or less, the etching power is insufficient, so that the dense oxide film on the surface of the Al alloy plate 2 cannot be sufficiently removed, and the surface roughness cannot be increased.
From the viewpoint of more surely removing the dense oxide film, the pH of the alkaline aqueous solution used in the etching treatment is preferably 12.0, and more preferably 12.5.

  Most preferably, the alkaline aqueous solution having a pH exceeding 11 can include, for example, Surf Cleaner 420N-2 manufactured by Nippon Paint Co., but is not limited thereto. The processing conditions of the etching process when using Nippon Paint's Surf Cleaner 420N-2 as an alkaline aqueous solution having a pH exceeding 11 are, for example, a concentration of 2 to 3%, a temperature of 60 to 70 ° C., and a processing time of 3 to 10 seconds. However, it is not limited to this. As described above, it is sufficient that the dense oxide film on the surface of the Al alloy plate 2 can be sufficiently removed and the surface roughness can be increased, and the processing conditions described above should be appropriately changed depending on the chemical used. Can do.

(De-smut treatment)
In the present embodiment, since the concentration of nitric acid in the zirconium chemical conversion treatment solution used in the chemical conversion treatment is 250 ppm or more and 4000 ppm or less as will be described later, it is possible to form the chemical conversion film 3 by omitting the generally performed desmutting treatment. it can.
However, even in such a case, the desmutting process can be performed between the etching process (and its water washing) and the chemical conversion process as shown in FIG. In the desmutting treatment, for example, the surface of the aluminum alloy plate 2 may be washed with an aqueous solution having a pH of 5 or less. By doing in this way, the smut produced | generated by the etching process can be removed more reliably. Therefore, the reactivity of the chemical conversion treatment of the next process can be improved.
Examples of the aqueous solution having a pH of 5 or less include nitric acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, and citric acid aqueous solution.

(Chemical conversion treatment)
In the chemical conversion treatment, the surface of the Al alloy plate 2 is formed with a Zr chemical conversion treatment solution having a nitric acid concentration of 250 ppm or more and 4000 ppm or less to form a chemical conversion film 3. Thus, the reactivity of the chemical conversion treatment can be improved while removing the smut by performing the chemical conversion treatment using the Zr chemical conversion treatment liquid having a nitric acid concentration in the above range. That is, the chemical conversion film can be formed by omitting the desmutting treatment. Therefore, the corrosion resistance of the Al alloy plate 1 for packaging containers can be improved. In addition, since this chemical conversion treatment also has an effect of roughening the surface of the Al alloy plate 2, the adhesion after the formation of the resin film 4 (see FIG. 3) can be improved.
In general, the effect of improving the adhesion after the resin film formation obtained by the chemical conversion film formed using the Zr chemical conversion treatment liquid is obtained by adding an organic component to the Zr chemical conversion treatment liquid to the organic-inorganic composite film. To achieve it. However, when an organic component is added to the Zr chemical conversion treatment solution, there are problems such as uneven color generation and aggregation of the organic component. On the other hand, in this invention, the adhesiveness after resin film 4 formation can be improved, without producing such a problem by prescribing | regulating the range of the nitric acid concentration of a Zr chemical conversion liquid.

When the above-described chemical conversion treatment is not performed, the above-described effects cannot be obtained, so that the corrosion resistance and adhesion after the formation of the resin film 4 are deteriorated.
On the other hand, when the concentration of nitric acid in the Zr chemical conversion treatment solution is less than 250 ppm, the nitric acid concentration is too low, so that the removal of smut becomes insufficient. Therefore, the chemical conversion film 3 is not sufficiently formed. In this case, the appearance is deteriorated. Further, since the nitric acid concentration is too low, the surface of the Al alloy plate 2 is not sufficiently roughened, and the corrosion resistance and adhesion after the formation of the resin film 4 is deteriorated.
On the other hand, if the concentration of nitric acid in the Zr chemical conversion treatment solution exceeds 4000 ppm, the concentration of nitric acid is too high, so that the adhesiveness is lowered by the nitrate radical and the corrosion resistance is deteriorated.
From the viewpoint of more surely removing smut and improving the reactivity of the chemical conversion treatment, the concentration of nitric acid in the zirconium chemical conversion treatment solution is preferably 500 ppm or more. For the same reason, the concentration of nitric acid in the zirconium chemical conversion treatment liquid is preferably 2000 ppm or less, and more preferably 1300 ppm or less.

The Zr chemical conversion treatment liquid is most preferably a chemical conversion treatment bath containing 20 to 600 ppm of zirconium and 10 to 200 ppm of phosphoric acid, phosphoric acid is H ₃ PO ₄ , and zirconium is provided from zirconium hydrofluoric acid. Is done. The phosphoric acid content in the treatment bath is limited to that derived from the phosphoric acid, and as treatment conditions, the temperature is room temperature to 60 ° C., the treatment time is 3 to 60 seconds, and the treatment bath pH is 2.0 to 2. .7.

By performing the above-described chemical conversion treatment, the Al alloy plate 1 for a packaging container according to the present embodiment contains Mg and Zr in the chemical conversion film 3 calculated from the content of Mg contained in the Al alloy plate 2. The ratio of the amount can be 0.01 or more and 8.5 or less in Mg / Zr.
Furthermore, by performing the chemical conversion treatment described above, the Al alloy plate 1 for packaging containers according to the present embodiment has a Zr of 0.5 mg / m ² or more and 20 mg / m ² or less of the coating amount (attachment amount) of the chemical conversion film 3. Phosphorus (P) can be 0.1 mg / m ² or more and 7 mg / m ² or less.
These will be described later.

The degreasing treatment, etching treatment, desmutting treatment, and chemical conversion treatment described above can be performed with general equipment and conditions such as spraying and dipping.
After each process, as shown in FIGS. 1-3, a water washing process is performed by a conventional method.
As described above, the chemical conversion film 3 in the present embodiment can be formed without performing desmutting treatment. That is, since the number of steps can be omitted as compared with the conventional case, the Al alloy plate 1 for packaging containers can be quickly produced, and the cost can be reduced.

(Ratio of content of Mg and Zr in chemical conversion film)
In the present invention, the chemical conversion film 3 is formed on the surface of the Al alloy plate 2 by performing the chemical conversion treatment described above, and the ratio of the content of Mg and Zr in the formed chemical conversion film 3 is Mg / Zr. It is 0.01 or more and 8.5 or less. When the ratio of Mg to Zr content in the chemical conversion film 3 (Mg / Zr) is within this range, it means that the removal of the smut and the roughening of the surface of the Al alloy plate 2 have been performed reliably. Thus, the corrosion resistance and adhesion after the formation of the resin film 4 can be improved.

In addition, when the ratio of the content of Mg and Zr in the chemical conversion film 3 exceeds 8.5 in terms of Mg / Zr, it means that etching is too strong. If the etching is too strong, the amount of Mg smut generated in the etching remains in the chemical conversion film 3 and the corrosion resistance after the resin film 4 is formed deteriorates.
From the viewpoint of obtaining superior corrosion resistance and adhesion, the ratio of the content of Mg and Zr in the chemical conversion film 3 is preferably 0.10 or more, and preferably 4.32 or less in terms of Mg / Zr.

  The content ratio (Mg / Zr) of Mg and Zr in the chemical conversion film 3 can be controlled by setting the etching treatment and the chemical conversion treatment to the above-described conditions.

  The ratio of the content of Mg and Zr in the chemical conversion film 3 (Mg / Zr) is determined by quantitatively analyzing the surface of the chemical conversion film 3 by, for example, glow discharge emission spectroscopy (GD-OES). The Mg / Zr ratio can be determined from the atomic percent of Mg and Zr obtained.

(Chemical coating amount)
As described above, in the present invention, the chemical conversion film 3 is formed on the surface of the Al alloy plate 2 by performing the chemical conversion treatment.
In the present invention, the amount of the formed chemical conversion film 3 is such that Zr is 0.5 mg / m ² or more and 20 mg / m ² or less, and P is 0.1 mg / m ² or more and 7 mg / m ² or less. When the film amount of the chemical conversion film 3 is set as described above, the surface of the Al alloy plate 2 can be sufficiently covered. Therefore, the Al alloy plate 1 for a packaging container is excellent in corrosion resistance and adhesion after the resin film 4 is formed. In addition, Zr in the chemical conversion film 3 is Zr (OH) ₄ , ZrF _4-n (OH) _n , ZrF _4-3m-n (PO ₄ ) _m (OH) _n , ZrF _4-n O _{n / 2} , _{ZrF 4-3m-n O n / 2} (PO 4) m, ZrFxOy, may be present in the form of a Zr compound such as _{ZrF x O y (PO 4)} x. P in the chemical conversion coating _{3, AlF x-3m (PO 4} ) m (OH) 3-x, AlF x O (3-x) / 2, AlF x-3m O (3-x) / 2 (PO 4 ) _m, it may be present in the form of a P compound such as _{AlF x O y (PO 4)} x. These Zr compound and P compound are contained in the Zr chemical conversion treatment liquid described above. Note that m, n, x, and y each represent an integer.

On the other hand, if the Zr is less than 0.5 mg / m ^{2 with} respect to the coating amount of the chemical conversion film 3, the chemical conversion film 3 cannot sufficiently cover the Al alloy plate 2, so that the corrosion resistance and adhesion after the resin film 4 is formed. Becomes worse. Regarding the coating amount of the chemical conversion coating 3, even when P is less than 0.1 mg / m ² , the corrosion resistance and adhesion after the formation of the resin coating 4 are deteriorated for the same reason as Zr.
In addition, with respect to the coating amount of the chemical coating 3, if Zr exceeds 20 mg / m ² , the coating amount of the chemical coating 3 is too large. Adhesion is poor. Moreover, since there are too many film | membrane amounts of the chemical conversion film 3, the change to which an external appearance is not desired arises, or cost becomes high. As for the amount of the chemical conversion film 3, even when P exceeds 7 mg / m ² , adhesion is deteriorated for the same reason as Zr, an undesired change in appearance is caused, and cost is increased.
From the viewpoint of obtaining better corrosion resistance and adhesion, and further obtaining an appearance, the coating amount of the chemical conversion coating 3 is preferably such that Zr is 1.7 mg / m ² or more and P is 0.4 mg / m ² or more. Zr is 14.8 mg / m ² or less, preferably set to P is mg / m ² or less 6.3 mg / m ² or less.

  The coating amount of the chemical conversion film 3, that is, the Zr deposition amount and the P deposition amount can be determined by quantitatively analyzing the chemical coating film 3 by, for example, X-ray Fluorescence Analysis (XRF). .

(Second Embodiment)
FIG. 3 is a schematic diagram illustrating each process and configuration performed on the Al alloy plate for packaging containers according to the second embodiment of the present invention.
As shown in FIG. 3, the Al alloy plate 10 for a packaging container according to the present embodiment includes an Al alloy plate 2 serving as a base material, a chemical conversion film 3 formed on the surface of the Al alloy plate 2, and a chemical conversion film 3. And a resin film 4 formed on the substrate.

  In addition, the Al alloy plate 10 for packaging containers according to the second embodiment and the Al alloy plate 1 for packaging containers according to the first embodiment are such that the Al alloy plate 10 for packaging containers has a resin film 4. The other components are the same. Hereinafter, although the Al alloy plate 10 for packaging containers which concerns on 2nd Embodiment is demonstrated, the same code | symbol is attached | subjected about the same component as the Al alloy plate 1 for packaging containers which concerns on 1st Embodiment shown in FIG. Therefore, the description on the corresponding component is used, and the description here is omitted.

(Resin film)
As shown in FIG. 3, the resin film 4 is formed on the chemical conversion film 3 of the Al alloy plate 2 by a resin film formation process performed after the chemical conversion process.
The thickness of the resin film 4 is preferably 1 μm or more and 25 μm or less, for example. When the thickness of the resin film 4 is within this range, the corrosion resistance and adhesion after the formation of the resin film 4 can be further improved.
If the thickness of the resin film 4 is less than 1 μm, the film thickness is so thin that sufficient corrosion resistance and adhesion may not be obtained. On the other hand, when the thickness of the resin film 4 exceeds 25 μm, the film thickness is so thick that the adhesion may be deteriorated.
From the viewpoint of further improving the corrosion resistance and adhesion after the formation of the resin film 4, the thickness of the resin film 4 is preferably 3 μm or more, and more preferably 20 μm or less.
The thickness of the resin film 4 can be controlled by adjusting the coating amount when the resin film 4 is a paint, and when the resin film 4 is a film, It can be controlled by adjusting the thickness of the film.
In addition, it is conventionally known that there is a hydrogen bonding parameter as one index expressing the adhesion between the base material (Al alloy plate 2) and the coating resin (resin film 4). The chemical conversion film 3 formed in the present invention has a higher affinity to the resin film 4 having more hydrogen bonding components than the conventional chromate treatment material, and tends to improve adhesion. Therefore, high corrosion resistance can be obtained. For example, the hydrogen bond component of the surface free energy of the chemical conversion film 3 is about 15 N / m, and the hydrogen bond component of the conventional chromate treatment material is about 7 N / m. On the other hand, in the resin film 4, the hydrogen bond component of the solubility parameter is about 1.2 (cal / cm ³ ) ^{1/2 for} vinyl chloride and about 5.1 (cal / cm ³ ) ^{1/2 for} polyester. In contrast to the chemical conversion film 3, there was a tendency that the corrosion resistance of the polyester was higher than that of the vinyl chloride. In order for the resin film 4 to improve the adhesiveness with the chemical conversion film 3, it is preferable that the hydrogen bond component of a solubility parameter is 3.0-5.0 (cal / cm < ³ >) < ^1/2 >.

  The resin film 4 is preferably composed of one layer or two or more layers using at least one of a paint, a primer, and a film, for example. Moreover, it is preferable that this resin film 4 (namely, all the above-mentioned coating materials, a primer, and a film) are formed using at least 1 type of a polyester resin and an epoxy resin, for example. If it does in this way, the Al alloy plate 1 for packaging containers excellent in the corrosion resistance and adhesiveness after resin film 4 formation can be obtained.

  In the case where the resin film 4 is a paint (top coat paint) and a primer (undercoat paint), for example, the paint film is processed by a roll coater, a die coater, a knife coater, a bar coater, a gravure coater, a spray coater, etc. For example, it may be formed by applying to the surface of the Al alloy plate 2 and then curing the resin by heat treatment or ultraviolet irradiation.

  The resin film formation process in the case where the resin film 4 is a film can be performed, for example, by laminating the film on the surface of the Al alloy plate 2 on which the chemical conversion film 3 is formed using a known laminator.

  Next, the content of the present invention will be specifically described with reference to an example that exhibits the effects of the present invention and a comparative example that does not.

  No. in Table 1 Samples were manufactured by appropriately performing a degreasing treatment, an etching treatment, and a chemical conversion treatment on an Al alloy plate (thickness 0.26 mm) defined in JIS H 4000: 2014 shown in 1 to 25. For some samples, desmutting treatment was performed between the etching treatment and the chemical conversion treatment.

The ratio of the content of Mg and Zr in the chemical conversion film calculated from the content of Mg contained in the manufactured sample was determined as Mg / Zr (referred to as the Mg / Zr ratio in the chemical conversion film). Moreover, while calculating | requiring the coating amount (Zr adhesion amount and P adhesion amount) of the sample chemical conversion film, the external appearance, corrosion resistance, and adhesiveness were evaluated.
In addition, each process of a degreasing process, an etching process, a pickling process, and a Zr chemical conversion process used the following chemical | medical agent etc., and performed all by the spray.

(Degreasing treatment)
・ Drug: Surf Cleaner EC370 (Nippon Paint Co., Ltd.)
・ Concentration: 1% by mass
・ Temperature: 70 ℃
・ Processing time: 5 seconds

(Etching process)
・ Drug: Surf cleaner 420N-2 (manufactured by Nippon Paint)
・ Concentration: 2.0% by mass
-PH: listed in Table 1-temperature: listed in Table 1-treatment time: listed in Table 1

(De-smut treatment)
・ 5% nitric acid (pH 0.24)
・ 0.07 mol / L citric acid (pH 1)
・ Temperature: 40 ℃
Treatment time: 9 seconds As shown in Table 1, 5% nitric acid and citric acid were used alternatively.

(Chemical conversion treatment)
・ Drug: Alsurf ST550 (manufactured by Nippon Paint)
・ Nitric acid concentration: described in Table 1 ・ pH: described in Table 1 ・ Zr concentration: described in Table 1 ・ Phosphoric acid concentration: described in Table 1 ・ Concentration: 5% by mass
・ Temperature: 60 ℃
・ Processing time: 4 seconds

(Mg / Zr ratio in chemical coating)
The Mg / Zr ratio in the chemical conversion film was determined from the atomic% of Mg and Al obtained by quantitative analysis of the surface of the chemical conversion film using GD-OES.

(Chemical coating amount)
The coating amount (Zr adhesion amount and P adhesion amount) of the chemical conversion film was determined by quantitatively analyzing the surface of the chemical conversion film with XRF.

(Corrosion resistance)
A coating material in which a vinyl chloride sol coating was applied onto the chemical conversion film of the manufactured sample and a resin film was formed by coating and baking under the conditions that the PMT (Peak Metal Temperature) was 260 ° C. and the baking oven passage time was 30 seconds ( Resin film thickness: 130 mg / dm ² ).
The coated material is then stretched to a height of 2 mm using a 4 mmφ cylindrical mold, immersed in Coca-Cola (registered trademark, manufactured by Nihon Coca-Cola), and sealed so that carbonic acid does not escape. And kept at 60 ° C. for 1 week. By observing with a microscope, it was determined that the case without corrosion was OK and the case without corrosion was NG.

(Adhesion)
A coating material having a resin film formed under the same conditions as described for corrosion resistance was produced.
And after processing the coating material in an autoclave at 121 degreeC for 30 minutes, the T-type peeling test was implemented. A comparative evaluation with a phosphoric acid chromate treatment material was performed, and a material exhibiting a peel strength equal to or higher than that of the phosphoric acid chromate treatment was determined to be OK.

(appearance)
The appearance of the manufactured sample (that is, the sample before forming the resin film) was visually inspected, and the sample having no abnormality was determined to be OK, and the sample having abnormality was determined to be NG.

  Table 1 shows the types of Al alloy sheets, degreasing treatment, etching treatment, cleaning treatment, chemical conversion treatment conditions, Mg / Zr ratio in the chemical conversion film, corrosion resistance evaluation results, adhesion evaluation results, and appearance evaluation results. Indicates. In addition, the underline in Table 1 shows that the invention specific matter of the present invention is not satisfied.

As shown in Table 1, no. Since the samples 1 to 16 satisfied the invention specific matters of the present invention, the corrosion resistance and adhesion were excellent, and the appearance was also excellent.
In contrast, no. Since the samples of 17 to 25 did not satisfy any of the invention specific matters of the present invention, either the corrosion resistance or the adhesion was inferior, and the appearance was inferior. Specifically, it was as follows.

No. Sample No. 17 was inferior in corrosion resistance because the Mg / Zr ratio in the chemical conversion film was too high.
No. Sample 18 was obtained by increasing the amount of Zr adhesion and the amount of P adhesion of the chemical conversion film by increasing the time of chemical conversion treatment. No. Sample 18 was inferior in adhesion after forming the resin film because both the Zr adhesion amount and the P adhesion amount of the chemical conversion film were too much.
No. Since 19 samples were not degreased, no chemical conversion film was formed. That is, the Zr adhesion amount of the chemical conversion film was less than the lower limit value, and the P adhesion amount was less than the lower limit value. Therefore, no. Nineteen samples were inferior in corrosion resistance and adhesion, and inferior in appearance.

No. Since 20 samples were not etched, they were inferior in corrosion resistance and adhesion.
No. Sample 21 was inferior in corrosion resistance because the pH of the alkaline aqueous solution used in the etching treatment was too low.

No. In the sample No. 22, the concentration of nitric acid in the Zr chemical conversion treatment solution used in the chemical conversion treatment was too low, that is, the concentration of the chemical conversion treatment solution was too low, so the chemical conversion film was not formed, and the corrosion resistance and adhesion were poor. The appearance was also inferior.
No. Sample No. 23 was inferior in corrosion resistance and adhesion because the concentration of nitric acid in the Zr chemical conversion treatment solution used in the chemical conversion treatment was too high.

  No. The sample of 24 performed the pre-processing equivalent to Example 7 of above-mentioned patent document 2 (Unexamined-Japanese-Patent No. 2007-107033). No. Since the sample of 24 was not performing the etching process, it was inferior to corrosion resistance and adhesiveness.

  No. Sample 25 was obtained by performing pretreatment corresponding to Example 4 of Patent Document 2 (Japanese Patent Laid-Open No. 2007-107033). No. Since the 25 samples were not etched, they were inferior in corrosion resistance and adhesion.

1 Aluminum alloy sheet for packaging containers (Al alloy sheet for packaging containers)
2 Aluminum alloy plate (Al alloy plate)
3 Chemical conversion film 4 Resin film

Claims (3)

An aluminum alloy plate for a packaging container, which is formed into a coil shape and formed a chemical conversion film by performing a chemical conversion treatment containing zirconium and phosphoric acid while continuously passing an aluminum alloy plate containing magnesium,
The chemical conversion film is sequentially subjected to a degreasing treatment with an aqueous solution containing a surfactant and an etching treatment with an alkaline aqueous solution having a pH of more than 11, followed by a chemical conversion treatment with a zirconium chemical conversion treatment solution having a nitric acid concentration of 250 ppm to 4000 ppm. Is formed by
Furthermore, the ratio of the content of magnesium and zirconium in the chemical conversion film calculated from the content of magnesium contained in the aluminum alloy plate is 0.01 to 8.5 in terms of Mg / Zr, and
Coating amount of the chemical conversion coating, zirconium 0.5 mg / m ² or more 20 mg / m ² or less, an aluminum alloy plate for a packaging container, characterized in that phosphorus is 0.1 mg / m ² or more 7 mg / m ² or less .   The aluminum alloy plate for packaging containers according to claim 1, wherein a resin film is formed after the chemical conversion treatment, and a resin film having a thickness of 1 µm to 25 µm is formed on the chemical conversion film. The resin film is composed of one or more layers using at least one of a paint, a primer, and a film, and
The said resin film is formed using at least 1 type of a polyester resin and an epoxy resin, The aluminum alloy plate for packaging containers of Claim 2 characterized by the above-mentioned.

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