JP5623167B2 - Aluminum alloy foil and manufacturing method thereof, aluminum alloy foil molded container, food packaging body - Google Patents

Description

  TECHNICAL FIELD The present invention generally relates to an aluminum alloy foil and a method for producing the same, an aluminum alloy foil molded container, and a food package, and specifically, an aluminum alloy foil used for containing food such as noodle foods and pot foods. The present invention also relates to a method for producing the same, an aluminum alloy foil molded container, and a food packaging body.

  A food package with an aluminum foil molded container for storing food such as noodle ingredients and pot food ingredients can be cooked and cooked as it is without transferring the food to a separate container, and the container can be disposable after eating Because of its convenience, it has been widely used for many years.

  For example, in the pamphlet of International Publication No. 2009/041429 (hereinafter referred to as Patent Document 1), an aluminum foil molded container used as a container for food packaging suitable for cooking by an electromagnetic cooker, and aluminum as a material of the container Alloy foils have been proposed.

  On the other hand, foods stored in aluminum foil molded containers have been diversified in recent years. As pot food ingredients, for example, tomato pots, black vinegar pots and the like that have not been conventionally proposed as creative dishes. Thus, there is a need for an aluminum foil molded container with better corrosion resistance in a state where it cannot be predicted what kind of food will be accommodated.

International Publication No. 2009/041429 Pamphlet

  However, the aluminum alloy foil proposed in Patent Document 1 has a problem that the corrosion resistance is not sufficient for various foods.

  Accordingly, an object of the present invention is to provide an aluminum alloy foil having a moldability necessary for molding a container and a strength necessary for the container, and having excellent corrosion resistance, a method for producing the same, an aluminum alloy foil molded container, a food It is to provide a package.

  In order to solve the above-mentioned problems, the present inventors have made various studies. As a result, in the aluminum alloy foil, the content of at least manganese, silicon, iron, copper, and magnesium, and the aluminum-manganese system present in the aluminum alloy foil It has been found that by controlling the compound particles, moldability necessary for molding the container, strength required for the container, and excellent corrosion resistance can be obtained simultaneously. The present invention has been made based on such knowledge of the present inventor.

  The aluminum alloy foil according to the present invention comprises 0.8% by mass or more and 3.0% by mass or less of manganese, 0.1% by mass or more and 0.9% by mass or less of silicon, and 0.1% by mass or more of 1. 0 mass% or less of iron, 0.05 mass% or more and 0.2 mass% or less of copper, and 0.000001 mass% or more and 0.01 mass% or less of magnesium, with the balance being aluminum and inevitable impurities The ratio of the number of aluminum-manganese compounds having a particle diameter of 0.1 μm or more and 0.5 μm or less to the number of aluminum-manganese compounds having a particle diameter of 1.0 μm or more is 20 or more It is.

The thickness of the aluminum alloy foil 40μm or more of the present invention 250μm or less, a tensile strength of 150 N / mm ² or more 250 N / mm ² or less, strength is 70N / mm ² or more 130N / mm ² or less, elongation of 25% 10% or more or less Preferably there is.

Further, in the aluminum alloy foil of the present invention, the corrosion acceleration X when immersed in an aqueous solution of 1.2 molar hydrochloric acid maintained at a temperature of 40 ° C. is X (μm / second ² ) = foil thickness t (μm) / (Time until the foil breaks (seconds)) ² , the corrosion acceleration X is preferably 0.08 × 10 ⁻³ or more and 0.8 × 10 ⁻³ or less.

Furthermore, in the aluminum alloy foil of the present invention, it is preferable that 70 to 250 aluminum-manganese compounds having a particle size of 0.1 μm or more and 0.5 μm or less are present in a cross-sectional area of 2500 μm ² .

Furthermore, in the aluminum alloy foil of the present invention, it is preferable that 1 to 20 aluminum-manganese compounds having a particle diameter of 1.0 μm or more are present in a sectional area of 2500 μm ² .

  In the aluminum alloy foil of the present invention, the average crystal grain size of the aluminum alloy is preferably 1 μm or more and 20 μm or less.

  The manufacturing method of the aluminum alloy foil of this invention is a manufacturing method of the aluminum alloy foil which has one of the above-mentioned characteristics, Comprising: The following processes are provided.

  (A) A step of obtaining an aluminum alloy ingot by casting a molten aluminum alloy to a thickness of 3 mm to 10 mm at a cooling rate of 100 ° C./second to 500 ° C./second

  (B) A step of obtaining a cold rolled foil of an aluminum alloy by cold rolling the ingot to a thickness of 40 μm or more and 250 μm or less.

  (C) A step of annealing the cold-rolled foil by heating and holding at a temperature of 350 ° C. or higher and 650 ° C. or lower for 0.001 second or more and 60 seconds or less.

  The aluminum alloy foil molding container of the present invention is formed by molding an aluminum alloy foil having any one of the above-described characteristics, and includes at least a bottom wall and a peripheral wall extending upward from the bottom wall.

  The food packaging body of this invention is equipped with said aluminum alloy foil shaping | molding container.

  As described above, the aluminum alloy foil of the present invention has the moldability necessary for molding a container, the strength necessary for the container, and excellent corrosion resistance, so that it has corrosion resistance against a wide variety of foods. The aluminum alloy foil of the present invention can be used for an aluminum alloy foil-molded container and a food packaging body provided with the same.

  First, an aluminum alloy foil as an embodiment of the present invention includes 0.8 mass% or more and 3.0 mass% or less manganese, 0.1 mass% or more and 0.9 mass% or less silicon, It contains iron in an amount of not less than 1.0% by mass and not more than 1.0% by mass, copper in an amount of not less than 0.05% by mass and not more than 0.2% by mass, and magnesium in an amount of not less than 0.000001% by mass and not more than 0.01% by mass. And unavoidable impurities.

  The reason for limiting the amount of manganese (Mn) contained in the aluminum alloy foil to 0.8 mass% or more and 3.0 mass% or less is as follows. Manganese is an element that contributes to the strength of the aluminum alloy foil. In addition, by controlling the particle size and number of aluminum (Al) -manganese (Mn) compounds, manganese has the effect of increasing corrosion resistance as well as mechanical properties such as tensile strength, proof stress, and elongation of aluminum alloy foils. Have. When the content of manganese is less than 0.8% by mass, sufficient above characteristics cannot be obtained. On the other hand, if the manganese content exceeds 3.0% by mass, the strength of the aluminum alloy foil becomes too high, and it may be difficult to roll into a thin foil and form into a container. The preferable content of manganese is 1.0% by mass or more and 3.0% by mass or less, and more preferably 1.0% by mass or more and 1.5% by mass or less.

  The reason why the amount of silicon (Si) contained in the aluminum alloy foil is limited to 0.1 mass% or more and 0.9 mass% or less is as follows. Silicon is an element that contributes to the strength of the aluminum alloy foil. In addition, silicon has an effect of promoting precipitation of other elements, particularly promoting precipitation of an Al—Mn compound having a particle diameter of 0.1 μm or more and 0.5 μm or less. If the silicon content is less than 0.1% by mass, sufficient mechanical properties and corrosion resistance of the aluminum alloy foil cannot be obtained. On the other hand, if the silicon content exceeds 0.9% by mass, the strength of the aluminum alloy foil becomes too high, and it may be difficult to roll into a thin foil and to form into a container.

  The reason why the amount of iron (Fe) contained in the aluminum alloy foil is limited to 0.1% by mass or more and 1.0% by mass or less is as follows. Iron is an element that contributes to the strength of the aluminum alloy foil. Further, iron has an effect of promoting precipitation of other elements, and particularly promoting precipitation of an Al—Mn compound having a particle size of 0.1 μm or more and 0.5 μm or less. If the iron content is less than 0.1% by mass, sufficient mechanical properties and corrosion resistance of the aluminum alloy foil cannot be obtained. On the other hand, if the iron content exceeds 1.0% by mass, the strength of the aluminum alloy foil becomes too high, and it may be difficult to roll into a thin foil and to form into a container.

  The reason for limiting the amount of copper (Cu) contained in the aluminum alloy foil to 0.05 mass% or more and 0.2 mass% or less is as follows. Copper is an element that improves the rolling property to a thin foil but reduces the corrosion resistance. If the copper content is less than 0.05% by mass, sufficient elongation and rollability of the aluminum alloy foil cannot be obtained. Moreover, when content of copper exceeds 0.2 mass%, the corrosion resistance of aluminum alloy foil will be impaired remarkably.

  The reason why the amount of magnesium (Mg) contained in the aluminum alloy foil is limited to 0.000001 mass% or more and 0.01 mass or less is as follows. Magnesium is an element that contributes to the strength of the aluminum alloy foil. If the magnesium content exceeds 0.01% by mass, the strength becomes too high, and rolling to a thin foil and molding into a container may be difficult. Here, although the minimum of content of magnesium is not specifically limited, Generally it is about 0.000001 mass%. A more preferable magnesium content is 0.005 mass% or less.

  The aluminum alloy foil of the present invention may contain elements such as chromium (Cr) and titanium (Ti) in such a content that does not affect the above characteristics and effects.

  Next, in the aluminum alloy foil as an embodiment of the present invention, the aluminum-manganese compound having a particle size of 0.1 μm or more and 0.5 μm or less with respect to the number of the aluminum-manganese compound having a particle size of 1.0 μm or more. The number ratio is 20 or more. By doing in this way, the aluminum alloy foil excellent in intensity | strength and corrosion resistance can be obtained.

In the aluminum alloy foil as an embodiment of the present invention, it is preferable that 70 to 250 aluminum-manganese compounds having a particle diameter of 0.1 μm or more and 0.5 μm or less are present in a cross-sectional area of 2500 μm ^2. . Further, it is preferable that 1 to 20 aluminum-manganese compounds having a particle size of 1.0 μm or more are present in a cross-sectional area of 2500 μm ² .

  As described above, the aluminum alloy foil of the present invention has a limited composition, and since the particle size and abundance ratio of the aluminum-manganese compound present in the aluminum alloy foil are limited, the strength and corrosion resistance are reduced. Are better. As a result, the aluminum alloy foil of the present invention combines the moldability required to mold the container, the strength required for the container, and excellent corrosion resistance, so corrosion resistance is required for a wide variety of foods. The aluminum alloy foil of the present invention can be used for an aluminum alloy foil molded container and a food packaging body provided with the same.

  As one preferable embodiment of the present invention, the thickness of the aluminum alloy foil is 40 μm or more and 250 μm or less, more preferably 40 μm or more and 180 μm or less, and more preferably 50 μm or more and 100 μm or less. If the thickness of the aluminum alloy foil is less than 40 μm, the strength of the container formed from the aluminum alloy foil is lowered, and there is a possibility that the food cannot be held or deformed. If the thickness of the aluminum alloy foil exceeds 200 μm, it may be difficult to form into a container.

Furthermore, an aluminum alloy foil as the preferred one embodiment of the present invention has a tensile strength of 150 N / mm ² or more 250 N / mm ² or less, strength is 70N / mm ² or more 130N / mm ² or less, elongation of 10% or more 25 % Or less.

Tensile strength less than 150 N / mm ² of the aluminum alloy foil, or the yield strength is less than 70N / mm ^2, the strength of the container becomes insufficient, or no longer to hold the food, there is a risk of or deformed. When the tensile strength of the aluminum alloy foil exceeds 250 N / mm ² or the proof stress exceeds 130 N / mm ² , rolling to a thin foil and forming into a container may be difficult.

  If the elongation of the aluminum alloy foil is less than 10%, rolling to a thin foil and forming into a container may be difficult. If the elongation of the aluminum alloy foil exceeds 25%, the shape-retaining property as a container becomes insufficient, and there is a possibility that the food cannot be held or deformed.

As one preferred embodiment of the present invention, in an aluminum alloy foil, the corrosion acceleration X when immersed in an aqueous solution of 1.2 molar hydrochloric acid maintained at a temperature of 40 ° C. is X (μm / sec ² ) = foil. when the thickness t ([mu] m) / a expressed as (foil time (in seconds) before breaking) ^2, corrosion acceleration X is 0.8 × 10 ^-3 or less 0.08 × 10 ^-3 or more. The corrosion acceleration can be controlled to 0.8 × 10 ⁻³ μm / second ² or less by controlling the above composition, the particle diameter and the number of aluminum-manganese compounds. The lower limit value of the corrosion acceleration is not particularly limited, but is about 0.08 × 10 ⁻³ μm / second ² which is equivalent to that of pure aluminum (equivalent to JIS 1070).

  In the method for producing an aluminum alloy foil of the present invention having the composition and characteristics as described above, a molten aluminum alloy having the above composition is 3 mm or more and 10 mm or less at a cooling rate of 100 ° C./second or more and 500 ° C./second or less. A step of obtaining an ingot of an aluminum alloy by casting to a thickness, a step of obtaining a cold-rolled foil of an aluminum alloy by cold rolling the ingot to a thickness of 40 μm to 250 μm, and the above A step of annealing the cold-rolled foil by heating and holding at a temperature of 350 ° C. or higher and 650 ° C. or lower for 0.001 second or more and 60 seconds or less. Thereafter, if necessary, the aluminum alloy foil is further cold-rolled to a thickness of 40 μm or more and 180 μm or less.

  The reason why the cooling rate during casting is 100 ° C./second or more is to suppress crystallization of the aluminum-manganese compound and promote solid solution. Such casting methods include various continuous casting and rolling methods, for example, (1) a belt type in which a molten metal is poured into a mold formed between parallel steel belts and blocks on both sides, and (2) instead of the belt. Examples include a connecting block type using a connecting block, and (3) a twin-roll type in which a ceramic nozzle is poured between a pair of rollers.

  The reason why the foil thickness after cold rolling is 40 μm or more and 250 μm or less is to control the average crystal grain size of the aluminum alloy by imparting sufficient working strain until annealing.

  The obtained cold rolled foil is annealed at a temperature of 350 ° C. or higher and 650 ° C. or lower in order to facilitate forming into a container. At this time, the heating and holding time at a temperature of 350 ° C. or higher is set to 60 seconds or less because the number (A) of aluminum-manganese compounds having a particle size of 0.1 μm to 0.5 μm is determined. This is because the number of aluminum-manganese compounds of 1.0 μm or more is larger than the number (B), and the ratio (A / B) of (A) to (B) is 20 or more. Preferably, the cold-rolled foil is annealed by heating and holding at a temperature of 400 ° C. to 550 ° C. for 0.01 seconds to 10 seconds. Such an annealing method is performed in a continuous casting line (CAL) or the like.

  The average crystal grain size of the aluminum alloy is not limited, but is preferably 1 μm or more and 20 μm or less, and more preferably 5 μm or more and 20 μm or less. If the average crystal grain size of the aluminum alloy exceeds 20 μm, it may be difficult to form into a container. The average crystal grain size of the aluminum alloy is preferably small, but is usually about 1 μm. The crystal grain size of the aluminum alloy in the present invention refers to the maximum width of crystal grains in the direction perpendicular to the cold rolling direction.

An aluminum alloy foil molding container according to one embodiment of the present invention is a single aluminum alloy foil formed by a known method, and has a rounded square bottom wall and spreads from the periphery of the bottom wall. It consists of a peripheral wall extending upward and a flange that projects horizontally from the upper edge of the peripheral wall. A number of embosses are formed on the bottom wall, a number of vertical ribs are formed on the peripheral wall, and edge windings are provided on the outer periphery of the flange. This aluminum alloy foil-molded container is used for cooking while containing foods such as noodle foods and pot foods. Here, the projected area of the bottom wall is preferably about 70 to 255 cm ² . If the projected area of the bottom wall is less than 70 cm ^2, it is difficult to stably install the heater on the heater. When the projected area of the bottom wall exceeds 255 cm ² , the strength as a container becomes insufficient.

  In addition, the food packaging body as one embodiment of this invention is equipped with the above-mentioned aluminum alloy foil molding container.

  Examples of the present invention will be described below.

  Ingots having a thickness of 8 mm were prepared by preparing molten aluminum alloys of Examples 1 to 6 and Comparative Examples 1 to 9 having the compositions shown in Table 1 and solidifying the molten aluminum alloys at a casting cooling rate shown in Table 2. Manufactured. Examples 1-6 have compositions within the scope of the present invention, and Comparative Examples 1-9 have compositions outside the scope of the present invention (values shown in Table 1 are underlined).

  Then, cold rolling foil was produced by rolling to the thickness of 100 micrometers by cold rolling, without giving homogenization process to each obtained ingot.

  Furthermore, the aluminum alloy foil of Examples 1-6 and Comparative Examples 1-9 was obtained by annealing each obtained cold-rolled foil on the heating conditions shown in Table 2. In addition, the total holding time above each temperature (300 ° C. or 350 ° C.) shown in Table 2 includes the time for heating and cooling above that temperature.

  About the obtained aluminum alloy foils of Examples 1 to 6 and Comparative Examples 1 to 9, various characteristics (number of Al-Mn compounds, average crystal grain size of aluminum alloy, tensile strength, yield strength, elongation, corrosion acceleration, and , Rolling property). The evaluated characteristics are shown in Tables 3 and 4.

Here, “particle diameter of Al—Mn compound (μm)” and “density (pieces / mm ² )” were measured as follows. A sample with a width of 10 mm is embedded in an epoxy resin so that the LT-ST plane (cross section perpendicular to the rolling direction) becomes the observation plane, and the observation plane is buffed (diamond polishing), and then a scanning electron microscope (SEM) Observed. Then, the area of each Al-Mn compound is obtained from images of 20 fields of view (1000x magnification) taken at random using image analysis software (product name: WinROOF, manufactured by Mitani Corporation) and has the area. The diameter of the circle was the particle diameter (μm) of each Al—Mn compound. Further, the number of Al—Mn compound particles having a particle diameter of 0.1 μm or more and 0.5 μm or less, the number of Al—Mn compound particles having a particle diameter of 1.0 μm or more, and the area to be observed are used for each particle The density (particles / mm ² ) of the Al—Mn compound particles having a diameter was determined using image analysis software. From the obtained density of Al—Mn compound particles (number / mm ² ), as shown in Table 3, the number of Al—Mn compounds having a particle diameter of 0.1 μm or more and 0.5 μm or less per 2500 μm ² (A) and the number (B) of Al—Mn compound particles having a particle diameter of 1.0 μm or more were calculated, and the ratio A / B was calculated.

  The “average crystal grain size” of the aluminum alloy is the value of the crystal grains perpendicular to the cold rolling direction in any 100 crystal grain photographs taken from the aluminum alloy grain photographs taken with an optical microscope. The maximum width was measured and determined as the average value.

“Tensile strength (N / mm ² )”, “proof strength (N / mm ² )” and “elongation (%)” were evaluated as follows. About each aluminum alloy foil, the tension test was done with the tension tester according to JISB7721, and tensile strength, yield strength, and elongation were calculated | required as follows. A sample having a width of 10 mm and a length of 150 mm was fixed so that the distance between chucks was 50 mm, and a tensile test was performed 10 times at a tensile speed of 10 mm / min, and tensile strength, proof stress, and elongation were measured. The 0.2% elongation was taken as “elongation”, the tensile strength at 0.2% elongation was taken as “proof strength”, and the tensile strength at break was taken as “tensile strength”, and the average value was obtained.

The “corrosion acceleration” was evaluated as follows. About 30 ml of a 1.2 molar hydrochloric acid aqueous solution is maintained at 40 ± 1 ° C., and a sample of each aluminum alloy foil having a width of 10 mm and a length of 30 mm is immersed so that a portion having a length of 15 mm is an interface, The time from the immersion to the complete fracture of the interface was measured, and the corrosion acceleration X (μm / sec ² ) was determined from the following equation. The number of samples was 5, and the average value of three points excluding the maximum value and the minimum value was determined and used as the corrosion acceleration.

Corrosion acceleration X (μm / second ² ) = foil thickness t (μm) / (time until the foil breaks (second)) ²

  “Rollability” was evaluated as “◯” when an aluminum alloy foil having a thickness of 100 μm was continuously rolled up to a thickness of 40 μm without breaking, and “x” when being broken or not rolled during rolling.

The “cooling rate (° C./second)” at the time of casting was evaluated as follows. Two ingots (both ends) are embedded in epoxy resin so that the LT-ST plane (cross section perpendicular to the rolling direction) becomes the observation plane, and the observation plane is buffed (diamond polishing), then scanned It observed with the electron microscope (SEM). Secondary dendrite branches obtained by measuring the secondary dendrite branch interval d (μm) in 20 fields of view (1000 × magnification) taken at random from the surface layer and the center of each sample at five locations. The average value of the measured distance was obtained. By substituting the average value d _m (μm) of the secondary dendrite branch interval into the following equation, the cooling rate C (° C./second) at the time of solidification is calculated and “cooling rate at casting (° C./second)” is obtained. did.

d _m = bC ^-n

  Here, b is 33 and n is 0.33.

As can be seen from Table 4, in Examples 1-6 of the present invention, the tensile strength of 150 N / mm ² or more 250 N / mm ² or less, strength is 70N / mm ² or more 130N / mm ² or less, elongation of 10% or more 25 %, And the corrosion acceleration is 0.08 × 10 ⁻³ μm / sec ² or more and 0.8 × 10 ⁻³ μm / sec ² or less, and an aluminum alloy foil with good rolling properties can be obtained.

  It should be considered that the embodiments and examples disclosed above are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

For example, the aluminum foil of the present invention can be used in an aluminum alloy foil molded container that requires corrosion resistance for a wide variety of foods such as tomato pots and black vinegar pots, and food packaging bodies provided with the same.

Claims (8)

0.8 mass% or more and 3.0 mass% or less of manganese, 0.1 mass% or more and 0.9 mass% or less of silicon, 0.1 mass% or more and 1.0 mass% or less of iron; It is an aluminum alloy foil containing not less than 05% by mass and not more than 0.2% by mass of copper and 0.000001% by mass to not more than 0.01% by mass of magnesium, with the balance containing aluminum and inevitable impurities,
Aluminum having a particle diameter of more than 1.0 .mu.m - for manganese number of compounds, 0.5 [mu] m or less aluminum than 0.1μm particle size - Ri der ratio 20 or more manganese number of compounds,
Thickness 40μm or 250μm or less, a tensile strength of 150 N / mm ² or more 250 N / mm ² or less, strength is 70N / mm ² or more 130N / mm ² or less, elongation of 25% or less than 10%, an aluminum alloy foil. Corrosion acceleration X when immersed in an aqueous solution of 1.2 molar hydrochloric acid maintained at a temperature of 40 ° C. is X (μm / sec ² ) = foil thickness t (μm) / (time until the foil breaks ( ² ) The aluminum alloy foil according to claim 1, wherein when expressed as ² , the corrosion acceleration X is 0.08 × 10 ⁻³ or more and 0.8 × 10 ⁻³ or less. The aluminum alloy foil according to claim 1 or 2 , wherein 70 to 250 aluminum-manganese compounds having a particle size of 0.1 µm to 0.5 µm are present in a cross-sectional area of 2500 µm ² . In cross-sectional area of 2500 [mu] m ^2, the aluminum particle size of at least 1.0 .mu.m - manganese compound is present 20 or less 1 or more, an aluminum alloy foil according to any one of claims 1 to 3 . The aluminum alloy foil according to any one of claims 1 to 4 , wherein an average crystal grain size of the aluminum alloy is 1 µm or more and 20 µm or less. A method for producing an aluminum alloy foil according to any one of claims 1 to 5 ,
A step of obtaining an aluminum alloy ingot by casting a molten aluminum alloy to a thickness of 3 mm to 10 mm at a cooling rate of 100 ° C./second to 500 ° C./second;
Cold rolling the ingot to a thickness of 40 μm or more and 250 μm or less to obtain a cold rolled foil of an aluminum alloy;
A method for producing an aluminum alloy foil, comprising: annealing the cold-rolled foil by heating and holding at a temperature of 350 ° C. to 650 ° C. for 0.001 seconds to 60 seconds. An aluminum alloy foil molding container, which is formed by molding the aluminum alloy foil according to any one of claims 1 to 5, and includes at least a bottom wall and a peripheral wall extending upward from the bottom wall. A food package comprising the aluminum alloy foil-molded container according to claim 7 .