JP2012149325A - Aluminum alloy foil for electromagnetic cooker, and aluminum foil container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy foil for an electromagnetic cooker, having an electric specific resistance suitable for heating and cooking by an electromagnetic cooker, being excellent in formability and corrosion resistance, and providing a container having sufficient strength, and an aluminum foil container formed of the aluminum alloy foil.SOLUTION: The aluminum alloy foil for an electromagnetic cooker contains ≥0.1 and ≤0.4 mass% of Fe, ≥1.0 and ≤1.6 mass% of Mn, ≥1.2 and ≤2.0 mass% of Mg, >0 and ≤0.3 mass% of Si, >0.005 and ≤0.1 mass% of Cu, and the balance of aluminum and inevitable impurities, and a content of Fe, Mn, and Mg, in mass%, satisfies a relational expression of [Fe] +1.05 [Mn] +0.25 [Mg] ≤2.1.

Description

  The present invention relates to an aluminum alloy foil for an electromagnetic cooker and an aluminum foil molded container.

Molded containers using disposable aluminum foil are widely used as containers for heated foods such as noodles and pots because of their good processability, high thermal conductivity, and lightness. In the past, when heating the container, heating by a direct heating with a gas stove was common. However, recently, an electromagnetic cooker that can be heated without using fire has been rapidly spread, and an aluminum foil molded container that can be used in an electromagnetic cooker has been demanded.
An electromagnetic cooker is a heating device using electromagnetic induction. When current generated by electromagnetic induction flows through the container, Joule heat is generated by the electrical resistance of the container, and the food inside the container is cooked by this heat generation.

Conventional aluminum foil molded containers for direct fire have low electrical resistance, and the amount of Joule heat generated by electromagnetic induction is small, so they are not suitable for an electromagnetic cooker. As a method of increasing the electrical resistance of an aluminum foil molded container, there is a method of reducing the thickness of the aluminum foil molded as a container. However, if the thickness of the aluminum foil is reduced, the strength as the container is insufficient and the container is deformed. There is a problem that happens.
Then, the aluminum foil shaping | molding container improved for electromagnetic cookers is disclosed by adding Mg etc. and raising the electrical resistance of aluminum foil (refer patent documents 1-4).

Japanese Patent No. 3668710 JP 2007-270351 A JP 2008-266749 A JP 2009-97077 A

  In the technique described in Patent Document 1, the electrical resistance of the aluminum foil container is increased by adding a large amount of Mg and Cr. Moreover, in the technique described in Patent Document 2, the electrical resistance of the aluminum foil molded container is increased by adding Mn, Mg, and Cr. However, according to the knowledge of the present inventors, when a large amount of Mg is added, the strength of the aluminum foil becomes too high, and there is a possibility that molding becomes difficult. In addition, the addition of Cr increases the recrystallization temperature of the aluminum alloy, which may cause discoloration on the foil surface during final annealing.

  In the technique described in Patent Document 3, the electrical resistance of the aluminum foil molded container is increased by adding Mn and Cr without adding Mg. In Patent Document 3, casting is performed by rapid solidification in order to dissolve Mn having a small solid solubility limit as much as possible in a supersaturated state. Specifically, in the examples, casting is performed by rapid solidification at a cooling rate of 500 ° C./second, and such rapid solidification causes surface segregation and centerline segregation of the foil, which adversely affects the formability and corrosion resistance of the aluminum foil. May affect.

  In the technique described in Patent Document 4, the electrical resistance of the aluminum alloy foil molded container is increased by adding Mg, Mn, and Cr, but the content of Si and Fe is 0 <Si ≦ 0.1 mass%, It is necessary to make the value as extremely low as 0 <Fe ≦ 0.2% by mass, and it is disadvantageous in terms of cost to set the contents of Si and Fe in the above range. Moreover, in the Example of patent document 4, casting is performed by rapid solidification at a cooling rate of 500 ° C./second, and segregation or the like occurs in the foil as in the above-mentioned patent document 3, which adversely affects the formability and corrosion resistance of the aluminum foil. There is a possibility of effect.

  The present invention has been made in view of such circumstances, and has an electrical specific resistance capable of being cooked by an electromagnetic cooker, has excellent moldability and corrosion resistance, and can provide a container having sufficient strength. An object is to provide an aluminum alloy foil for cooking appliances and an aluminum foil molded container made of the aluminum alloy foil.

In order to solve the above problems, the aluminum alloy foil for an electromagnetic cooker according to the present invention has Fe: 0.1% by mass to 0.4% by mass, Mn: 1.0% by mass to 1.6% by mass, Mg: 1.2% by mass to 2.0% by mass, Si: more than 0% by mass and 0.3% by mass or less, Cu: more than 0.005% by mass and 0.1% by mass or less, with the balance being Al and inevitable impurities The content of Fe, Mn, and Mg satisfies the relational expression [Fe] +1.05 [Mn] +0.25 [Mg] ≦ 2.1 in terms of mass%.
The aluminum alloy foil for an electromagnetic cooker of the present invention preferably has a thickness of 65 μm or more and 100 μm or less.
The aluminum foil molded container of the present invention is characterized by comprising the above-described aluminum alloy foil for an electromagnetic cooker.

The aluminum alloy foil for an electromagnetic cooker according to the present invention contains Fe, Mn, Mg, Si, and Cu in a predetermined content, and the content of Fe, Mn, and Mg is [Fe] +1.05 [Mn in mass%. ] +0.25 [Mg] ≦ 2.1 By satisfying the relational expression, it has an electrical specific resistance capable of being cooked by an electromagnetic cooker, has excellent formability and corrosion resistance, and is molded from the aluminum alloy foil. The container has sufficient strength.
Moreover, the electrical resistivity and intensity | strength required as an aluminum foil shaping | molding container for electromagnetic cookers can be improved more by making the aluminum alloy foil which concerns on this invention into the range of 65 micrometers or more and 100 micrometers or less.
Since the aluminum foil molded container according to the present invention is formed from the above-described aluminum alloy foil for an electromagnetic cooker of the present invention, the container has an electrical specific resistance capable of being cooked by an electromagnetic cooker and is excellent in corrosion resistance. Sufficient strength.

It is a schematic perspective view which shows an example of the aluminum foil shaping | molding container which concerns on this invention. It is a schematic diagram which shows the method of the container strength evaluation in an Example.

Hereinafter, specific embodiments of the present invention will be described.
The aluminum alloy foil for an electromagnetic cooker according to the present invention (hereinafter simply referred to as “aluminum alloy foil”) is Fe: 0.1 mass% or more and 0.4 mass% or less, Mn: 1.0 mass% or more 1 0.6 mass% or less, Mg: 1.2 mass% or more and 2.0 mass% or less, Si: more than 0 mass%, 0.3 mass% or less, Cu: more than 0.005 mass%, 0.1 mass% or less And the balance is made of Al and inevitable impurities, and the content of Fe, Mn and Mg satisfies the relational expression of [Fe] +1.05 [Mn] +0.25 [Mg] ≦ 2.1 in mass%. Features.

Hereinafter, the reason for defining the contents of these elements will be described in detail.
“Fe: 0.1% by mass or more and 0.4% by mass or less”
Fe increases the electrical resistivity of the aluminum alloy foil, and when formed into an aluminum foil molded container, the strength of the container can be increased. However, in the case of an alloy containing 1.2% by mass or more of Mg, the (Mn, Fe) Al intermetallic compound may be coarsened in view of the Mn content. Therefore, if the Fe content exceeds 0.4% by mass, it may not be possible to add Mn in an amount necessary for imparting sufficient electrical specific resistance. Further, if the Fe content is less than 0.1% by mass, the effect of increasing the electrical specific resistance of Fe cannot be exhibited sufficiently, and the strength of the aluminum foil molded container may be lowered.

“Mn: 1.0 mass% or more and 1.6 mass% or less”
Mn has the effect of increasing electrical resistivity (increasing IH [Induction Heating] characteristics). Although the solid solubility limit is small, an excessive increase in strength can be suppressed, but in an alloy containing Mg, the (Mn, Fe) Al intermetallic compound becomes coarse in proportion to the Fe content, and becomes a starting point of fracture during press forming. There is a case. By setting the Mn content to be 1.0% by mass or more and 1.6% by mass or less, sufficient electrical specific resistance for an electromagnetic cooker can be obtained, and coarsening of the intermetallic compound can be suppressed. When the Mn content is less than 1.0% by mass, sufficient electrical resistivity cannot be obtained, and when the Mn content exceeds 1.6% by mass, coarse intermetallic compounds are crystallized and the formability is significantly deteriorated. There is a fear.

“Mg: 1.2 mass% or more and 2.0 mass% or less”
Mg contributes to the electrical resistivity as much as Mn. However, since solid solution hardening is larger than Mn, the strength of the aluminum alloy foil is greatly increased. If the Mg content exceeds 2.0 mass%, the strength of the aluminum alloy foil is too high, and press molding may be difficult. Further, if the Mg content is less than 1.2% by mass, sufficient electrical specific resistance may not be obtained.

“Si: more than 0% by mass and 0.3% by mass or less”
Si increases the electrical resistivity of aluminum alloy foil, and when molded into an aluminum foil molded container, it has the effect of increasing the strength of the container, but when added in large amounts, it precipitates with other elements and conversely lowers the electrical resistivity. In addition, it has the property of reducing corrosion resistance.
If the Si content is 0% by mass, the required container strength and electrical resistivity may be difficult to obtain, and if the Si content exceeds 0.3% by mass, the electrical resistivity and corrosion resistance may be reduced. . The content of Si is preferably 0.1 <Si ≦ 0.20 mass%.

“Cu: more than 0.005 mass% and 0.1 mass% or less”
Cu is effective in increasing the strength even in a small amount, but decreases the corrosion resistance. When the Cu content is 0.005% by mass or less, the required container strength may not be obtained. When the Cu content exceeds 0.1% by mass, the corrosion resistance is reduced, and when food is put in the container. Corrosion holes and discoloration may occur. The content of Cu is more preferably 0.005 <Cu ≦ 0.05% by mass.

“[Fe] +1.05 [Mn] +0.25 [Mg] ≦ 2.1”
In the aluminum alloy foil of the present invention, the contents of Fe, Mn, and Mg are mass%, and satisfy the relational expression [Fe] +1.05 [Mn] +0.25 [Mg] ≦ 2.1.
This formula has been obtained by the inventors of casting various alloys so far, and when the content of Fe, Mn and Mg exceeds 2.05 in this formula, (Mn, Fe ) It has been found that the possibility of forming an Al giant intermetallic compound is extremely high. Since the giant intermetallic compound becomes the starting point of cracks and pinholes during press molding, if the giant intermetallic compound is formed, the formability becomes extremely poor. Furthermore, when (Mn, Fe) Al giant intermetallic compound is produced, the solid solution amount of Mn in the aluminum matrix is reduced, and the electrical resistivity is lowered.
In the aluminum alloy foil of the present invention, the content of Fe, Mn, and Mg satisfies the relational expression of [Fe] +1.05 [Mn] +0.25 [Mg] ≦ 2.1. Therefore, it has good moldability and electrical resistivity.

The aluminum alloy foil according to the present invention may contain Cr as an inevitable impurity. When the aluminum alloy of the present invention contains Cr as an inevitable impurity, the content is preferably 0.02% by mass or less.
Cr has the effect of increasing the electrical resistivity, but also has the effect of increasing the recrystallization temperature of the alloy. For this reason, if the Cr content is too large, it is necessary to raise the temperature of the final annealing, and this increase in the final annealing temperature may cause discoloration of the foil surface. Further, if the Cr content is too large, the castability of the alloy due to the increase in the liquidus temperature is also deteriorated, so the Cr content is limited to 0.02% by mass or less. When the aluminum alloy foil of the present invention contains Cr, the lower limit of the Cr content is not particularly defined, but is about 0.001% by mass.

  The thickness of the aluminum alloy foil according to the present invention is preferably in the range of 65 μm to 100 μm. By setting the thickness of the aluminum alloy foil in the above range, sufficient electrical specific resistance necessary for an aluminum foil molded container for an electromagnetic cooker can be obtained sufficiently, and sufficient strength required for an aluminum foil molded container can be sufficiently obtained. If the thickness of the aluminum foil alloy is less than 65 μm, the strength required for a molded container may not be obtained. On the other hand, if the thickness of the aluminum foil alloy exceeds 100 μm, the electrical resistivity required as an aluminum foil molded container for an electromagnetic cooker cannot be obtained. By setting the thickness of the aluminum alloy foil within the above range, the electrical resistivity required for the electromagnetic cooker foil can be easily secured, and therefore the aluminum alloy foil of the present invention can be applied to containers of any shape.

Next, an example of the manufacturing method of the aluminum alloy foil of this invention is demonstrated.
First, an ingot of aluminum alloy having the predetermined composition range described above is melted by a conventional method such as a known semi-continuous casting method or continuous casting rolling method.
Here, the cooling rate of casting is not particularly limited. However, the higher the cooling rate of casting, the greater the amount of solid solution of the element and the higher the electrical resistivity, but the aluminum produced by surface segregation and centerline segregation. It may adversely affect the formability and corrosion resistance of the alloy foil. Therefore, the cooling rate of casting is preferably 30 ° C./second or less.
Moreover, the ingot obtained by semi-continuous casting may perform a homogenization process as needed. The homogenization treatment can be performed, for example, under conditions of 500 ° C. or higher and 580 ° C. or lower and 4 hours or longer and 7 hours or shorter.

Thereafter, an aluminum alloy plate is obtained by hot rolling, and an aluminum alloy plate can be obtained as it is depending on the continuous casting and rolling method.
Next, intermediate annealing is performed as necessary, and then cold rolling and final annealing are performed to obtain an aluminum alloy foil having a desired thickness.
The thickness of the aluminum alloy foil after the final cold rolling is not particularly limited, but as described above, the thickness is preferably in the range of 65 μm to 100 μm.
Through the above steps, the aluminum alloy foil of the present invention can be produced.

The aluminum alloy foil for an electromagnetic cooker according to the present invention contains Fe, Mn, Mg, Si, and Cu in a predetermined content, and the content of Fe, Mn, and Mg is [Fe] +1.05 [Mn in mass%. ] +0.25 [Mg] ≦ 2.1 By satisfying the relational expression, it has an electrical specific resistance capable of being cooked by an electromagnetic cooker, has excellent formability and corrosion resistance, and is molded from the aluminum alloy foil. The container has sufficient strength.
Moreover, the electrical resistivity and intensity | strength required as an aluminum foil shaping | molding container for electromagnetic cookers can be improved more by making the aluminum alloy foil which concerns on this invention into the range of 65 micrometers or more and 100 micrometers or less.

Next, an embodiment of an aluminum foil molded container according to the present invention will be described.
FIG. 1 is a schematic perspective view showing an example of the structure of an aluminum foil molded container that can be produced by molding an aluminum alloy foil for an electromagnetic cooker according to the present invention. An aluminum foil molded container 10 shown in FIG. 1 is generally composed of a circular bottom wall 11, a peripheral wall 12 rising from the peripheral edge thereof, and a flange portion 13 extending from the upper end portion of the peripheral wall 12 to the outer peripheral side. A large number of wrinkles 14 are formed in the standing direction of 12. Such an aluminum foil molded container 10 can be produced by drawing the bottom wall 11 to form the peripheral wall 12 while applying wrinkles 14, forming the flange portion 13, and then edge-wrapping the outer periphery. . In addition, the aluminum foil shaping | molding container of this invention is not limited to this example, The wrinkle 14 does not need to be formed in the surrounding wall 12, A shape etc. can be changed suitably.

  Since the aluminum foil molded container according to the present invention is formed from the above-described aluminum alloy foil for an electromagnetic cooker of the present invention, the container has an electrical specific resistance capable of being cooked by an electromagnetic cooker and is excellent in corrosion resistance. Sufficient strength.

  As mentioned above, although each embodiment of the aluminum alloy foil for aluminum cookers and aluminum foil shaping | molding container which concerns on this invention was described, each part which comprises the above-mentioned aluminum foil shaping | molding container 10 is an example, Comprising: It does not deviate from the scope of the present invention. The range can be changed as appropriate.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

"Preparation of aluminum alloy foil and aluminum foil molded container"
(Examples 1-15, Comparative Examples 1-10)
An aluminum alloy melt containing each element with the content shown in Table 1 and the balance consisting of Al and inevitable impurities was cast at a cooling rate of 11 ° C./second by semi-continuous casting. In Example 9, the casting was performed at a cooling rate of 260 ° C./second.
Next, after performing a homogenization treatment at a temperature of 560 ° C. and a holding time of 4 hours, the ingot was chamfered to remove the surface nonuniform layer. Then, it was set as the board | plate material of thickness 6.4mm by hot rolling. Subsequently, cold rolling was performed to a thickness of 0.6 mm, and intermediate annealing was performed at a temperature of 360 ° C. for 3 hours. Then, the aluminum alloy foil was produced by finishing to the thickness of Table 1 by cold rolling, and finally performing the final annealing for 7 hours at the temperature of 350 degreeC.
The obtained aluminum alloy foil was press-molded to produce an aluminum foil-molded container having a shape shown in FIG. 1 (bottom wall diameter: 11.6 cm, peripheral wall height: 5.6 cm, flange width: 1.4 cm). .

"Evaluation"
The aluminum alloy foil and aluminum foil molded container produced in each example and each comparative example were evaluated for IH characteristics, formability, container strength, and corrosion resistance as follows. The results are shown in Table 2.

1. IH (Induction Heating) characteristic evaluation IH characteristic evaluation was performed as an index having sufficient electrical resistivity as an aluminum alloy foil for an electromagnetic cooker. The evaluation of the IH characteristics was performed by adding 350 cc of water to an aluminum foil molded container (bottom wall diameter: 11.6 cm, peripheral wall height: 5.6 cm, flange width: 1.4 cm) having the shape shown in FIG. 1 after press molding. It was carried out by measuring the time required for the water temperature to rise from 24 ° C. to 90 ° C. using an electromagnetic cooker. If the required time is 115 seconds or less, it is judged that it has sufficient performance (electrical resistivity) as an aluminum alloy foil for an electromagnetic cooker, the IH characteristic is “◯”, the required time exceeds 115 seconds and is 130 seconds or less. In this case, the IH characteristic was determined as “Δ”, and when the required time exceeded 130 seconds, the IH characteristic was determined as “x”. In addition, the test was implemented at a point of 500 m above sea level, and the electromagnetic cooker used was HT-B6S (200 V, 3.0 kW) manufactured by Hitachi. Even if the determination result is Δ, there is no practical problem as an aluminum foil for an electromagnetic cooker, but it is desirable that the determination result is ○.

2. Formability evaluation 1000 aluminum alloy foils were press-molded to produce 1000 aluminum foil molded containers. When there is no pinhole or cracked container at the bottom or wall surface of the formed molded container, the moldability is “◯”, the moldability is “Δ” when 1-5, and there are 6 or more Was determined to be moldability “×”. The evaluation result of the moldability is preferably ◯, but if the evaluation result is Δ or more, the moldability has no practical problem.

3. Container Strength Evaluation The container strength evaluation was performed by a static pressure test as schematically shown in FIG. FIG. 2 is a schematic diagram showing a container strength evaluation method. As shown in FIG. 2, the aluminum foil molded container was placed on a horizontal table upside down with the bottom face up. Next, a backing plate was placed on the bottom surface of the molded container, a load was applied from above the backing plate at a load speed of 20 m / sec, and the maximum load was measured at level n = 5. When the maximum load is 280 N or more, the container strength is “◯”, the maximum load is 279 N to 260 N, the container strength is “Δ”, and the maximum load is less than 260, the container strength is “x”. In addition, it has the intensity | strength which does not have a problem practically as a container with the determination result above (triangle | delta).

4). Corrosion resistance evaluation Corrosion resistance was evaluated by a salt spray test. The aluminum alloy foil of each example and each comparative example was cut into a size of 5 mm × 100 mm to obtain a test piece. After this test piece was washed with acetone, a 5% NaCl aqueous solution was used as a corrosive solution, and continuous salt spray was performed under conditions of a temperature of 35 ° C. and a humidity of 95%. The salt spray test was performed for 18 days, and the presence or absence of discoloration of the test pieces and the occurrence of corrosion holes after the salt spray test was observed. If there was no change in the test piece, the corrosion resistance was “◯”, and if there was a change in the test piece, the corrosion resistance was determined as “x”.

  As shown in Table 2, the aluminum alloy foils of Examples 1 to 15 are all excellent in moldability and corrosion resistance, have good IH characteristics, and have an electrical resistivity that can be cooked by an electromagnetic cooker. It was. Moreover, all the aluminum foil molded containers of Examples 1 to 15 had sufficient strength as containers.

On the other hand, the aluminum alloy foils of Comparative Examples 1, 2, 6, and 7 in which the contents of Fe, Mn, and Mg do not satisfy the predetermined relational expression of the present invention have low formability and corrosion resistance. Moreover, the aluminum alloy foil of Comparative Example 3 having a Mg content larger than the predetermined range of the present invention had low formability.
The aluminum alloy foils of Comparative Examples 4 and 5 having a Si or Cu content greater than the predetermined range of the present invention had low corrosion resistance. Moreover, the aluminum alloy foils of Comparative Examples 8 and 9 in which the content of Fe, Mn, or Mg is lower than the predetermined range of the present invention have low IH characteristics and container strength. Furthermore, the aluminum alloy foil of Comparative Example 10 having a Cu content less than the predetermined range of the present invention had low container strength.

  DESCRIPTION OF SYMBOLS 10 ... Aluminum foil molded container, 11 ... Bottom wall, 12 ... Perimeter wall, 13 ... Flange part, 14 ... Wrinkle.

Claims (3)

  Fe: 0.1% by mass to 0.4% by mass, Mn: 1.0% by mass to 1.6% by mass, Mg: 1.2% by mass to 2.0% by mass, Si: 0% by mass Containing 0.3% by mass or less, Cu: more than 0.005% by mass and 0.1% by mass or less, the balance being made of Al and inevitable impurities, the content of Fe, Mn, and Mg being mass%, [Fe ] The aluminum alloy foil for electromagnetic cookers characterized by satisfy | filling the relational expression of +1.05 [Mn] +0.25 [Mg] <= 2.1.   The aluminum alloy foil for an electromagnetic cooker according to claim 1, wherein the thickness is 65 µm or more and 100 µm or less.   An aluminum foil molded container comprising the aluminum alloy foil for an electromagnetic cooker according to claim 1 or 2.

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