JP4447980B2 - Aluminum foil excellent in strength after annealing and method for producing the aluminum foil - Google Patents

Description

  The present invention relates to an aluminum foil premised on final annealing for the purpose of evaporating the rolling oil adhering to the foil surface in the foil rolling step, and a method for producing the aluminum foil.

Aluminum foil used for food packaging, chemical packaging, and other packaging, or household aluminum foil (so-called aluminum foil) is usually subjected to hot rolling and cold rolling (including a foil rolling process). ). This aluminum foil is used as it is, or is further used by being bonded to paper, film or the like via an adhesive. In the aluminum foil, an Al—Fe alloy such as JIS 8021 and 8079, or an Al—Fe alloy containing 0.9 to 1.7% of Fe for the purpose of modifying these alloys (Patent Document 1). Browse) is used.
By the way, the rolling oil that is used in the foil rolling process and adheres to the foil surface may interfere with adhesion to paper or film or contaminate the package contents. Later, final annealing is performed. The temperature necessary for transpiration of the rolling oil is usually 200 ° C. or higher.
Japanese Patent Laid-Open No. 2003-239052

  However, when the final annealing is performed as described above, there is a problem that the aluminum foil is softened and the strength is inevitably reduced. In order to suppress softening, it is necessary to make the annealing temperature as low as possible, but in that case, it is necessary to make the annealing time long, and there are problems in terms of productivity and cost. Further, Patent Document 1 discloses a method of refining recrystallized grains after annealing by regulating manufacturing conditions such as a cooling rate at the time of casting and solidification, thereby increasing strength after annealing. However, even by such a method, there is no change in recrystallization after annealing, and there is a limit to the strength that can be secured.

  The present invention has been made against the background of the above circumstances, and an aluminum foil excellent in post-annealing strength capable of obtaining a sufficiently high strength even when subjected to annealing for the purpose of evaporating rolling oil, and the aluminum foil An object is to provide a manufacturing method.

In view of the above-mentioned problems, the present inventors have studied a method for securing high strength even when annealing is performed at a temperature at which the rolling oil evaporates in a short time. As a result, softening is prevented if recrystallization during final annealing is suppressed. I got the conclusion that I could do it. As a result of further investigation, the aluminum foil containing a predetermined amount of Fe, Si, Cu and further adding an appropriate amount of Zr has the effect of suppressing softening during annealing without impairing the foil rollability. The inventor has completed the present invention.

That is, the aluminum foil excellent in strength after annealing of the present invention is in mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu: 0.001% or more. 0.1% or less, Zr: 0.01% or more, containing 0.04% or less, it has a composition the balance of Al and unavoidable impurities, 140 hours or more 8 hours 180 ° C. or higher 400 ° C. or less It is used for the final annealing hold | maintained below, It is characterized by the above-mentioned.

The manufacturing method of the aluminum foil excellent in the strength after annealing of the present invention is mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu: 0.001 % Or more, 0.1% or less, Zr: 0.01% or more, 0.04% or less , the balance is composed of Al and inevitable impurities, and an aluminum foil having a thickness of 5 to 200 μm The annealing is performed under the condition that the temperature is maintained at 180 ° C. or higher and 400 ° C. or lower for 8 hours or longer and 140 hours or shorter.

  The composition and production conditions limited in the present invention will be described below. In addition, all content in each component is displayed by the mass%.

Fe: more than 0.7 to 2%
Fe is dispersed as an intermetallic compound in the Al substrate to improve the strength after annealing. If the amount is less than the predetermined amount, a desired effect cannot be obtained. If the amount exceeds the predetermined amount, coarse crystals are formed and pinholes increase, so the Fe content is limited to more than 0.7% to 2%.
For the same reason, it is desirable that the lower limit is 0.8% and the upper limit is 1.6%.

Si: 0.01 to 0.7%
Si is dispersed as an intermetallic compound in the Al substrate to improve the strength after annealing. If the amount is less than the predetermined amount, the desired effect cannot be obtained. If the amount exceeds the predetermined amount, coarse crystals are formed and pinholes increase, so the Si content is limited to 0.01 to 0.7%.
For the same reason, it is desirable that the lower limit is 0.02% and the upper limit is 0.3%.

Cu: 0.001 to 0.1%
Cu dissolves in the Al substrate to improve the strength after annealing, and suppresses recrystallization during the final annealing. If the amount is less than the predetermined amount, the desired effect cannot be obtained. If the amount exceeds the predetermined amount, the foil rollability is remarkably lowered, so the Cu content is limited to 0.001 to 0.1%. For the same reason, it is desirable that the lower limit is 0.005% and the upper limit is 0.05%.

Zr: 0.01-0.04 %
Zr disperses as an intermetallic compound in the Al substrate to increase the strength after annealing, and remarkably suppresses recrystallization during the final annealing to increase the strength after annealing. If the amount is less than the predetermined amount, the desired effect cannot be obtained. If the amount exceeds the predetermined amount, no further effect can be expected, and the foil rollability is significantly reduced. Therefore, the Zr content is limited to 0.01 to 0.04% . To do. For the same reason, it is desirable to set the lower limit of 0.02%.

  In addition to the above, the aluminum foil according to the present invention includes inevitable impurities such as Mn, Mg, Cr, Zn, Ti, Ni, and Ga, components derived from a casting finer such as Ti and B, and components derived from a casting flux such as Na and K. May be contained. As the inevitable impurities, Mn: 0.02% or less, Mg: 0.02% or less, Cr: 0.02% or less, Zn: 0.02% or less, Ti: 0.05% or less, Ni: 0.0. Examples include 05% or less and Ga: 0.05% or less. Moreover, when containing a casting fine agent, Ti: 0.002-0.05% and B: 0.001-0.01% can be illustrated. Furthermore, Na: 0.001% or less, K: 0.001% or less can be illustrated.

4) Annealing temperature: 180-400 ° C
When an aluminum alloy foil having the above composition is annealed, the rolling oil does not sufficiently evaporate and remains on the foil surface at a temperature lower than a predetermined temperature, which causes problems such as hindering bonding and contaminating the package contents. On the other hand, when the temperature exceeds a predetermined temperature, recrystallization proceeds and the strength after annealing decreases. From these viewpoints, in the manufacturing method of the present invention, the final annealing temperature after cold rolling is limited to 180 to 400 ° C. For the same reason, it is desirable that the lower limit is 190 ° C. and the upper limit is 300 ° C.

5) Annealing time: 8 to 140 hours When the annealing time in the above final annealing is less than a predetermined time, the rolling oil does not sufficiently evaporate and remains on the foil surface, which hinders bonding or contaminates the package contents. Occurs. On the other hand, even if the predetermined time is exceeded, a further effect cannot be expected, and the cost increases. From these viewpoints, in the manufacturing method of the present invention, the final annealing time after cold rolling is limited to 8 to 140 hours. For the same reason, it is desirable to set the lower limit to 20 hours and the upper limit to 120 hours.

That is, according to the aluminum foil excellent in strength after annealing according to the present invention, in mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu: 0.00%. 001% or more, 0.1% or less, Zr: 0.01% or more, containing 0.04% or less, it has a composition the balance of Al and unavoidable impurities, 8 hours 180 ° C. or higher 400 ° C. or less Since it is used for the final annealing held for 140 hours or less, high strength can be obtained even after the final annealing performed after the cold rolling. Therefore, the final annealing conditions are rarely restricted in terms of strength after annealing, and the remaining rolling oil can be evaporated and removed by sufficient annealing, and various problems due to the remaining rolling oil are solved. Moreover, since it has sufficient intensity | strength as aluminum foil, there exists an effect which a use use is expanded.

Moreover, according to the manufacturing method of the aluminum foil excellent in the strength after annealing of the present invention, in mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu : 0.001% or more, 0.1% or less, Zr: 0.01% or more, 0.04% or less, the balance is composed of Al and inevitable impurities, and the thickness is 5 to 200 μm Since the aluminum foil is annealed at a temperature of 180 ° C. or higher and 400 ° C. or lower for 8 hours or longer and 140 hours or shorter, the rolling oil is sufficiently evaporated and removed by the annealing, and the strength after annealing becomes sufficiently high. .

Hereinafter, embodiments of the present invention will be described.
In the present invention, in the above composition, that is, by mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu: 0.001% or more, 0. An aluminum alloy containing 1% or less, Zr: 0.01% or more and 0.04% or less, with the balance being Al and inevitable impurities is used.

After cold rolling, the final annealing is performed to evaporate the remaining rolling oil adhering to the aluminum foil. The final annealing is preferably performed under conditions of 180 to 400 ° C. and 8 to 140 hours.
The obtained aluminum foil can be used as it is, and can also be used by being bonded to paper, film or the like. The aluminum foil excellent in strength after annealing according to the present invention is an aluminum foil that is bonded to paper, film, etc. via an adhesive, and is used for food packaging, chemical packaging, and other packaging, or household aluminum. It is suitable for foil (so-called aluminum foil).

Examples of the present invention will be described below in comparison with comparative examples.
An aluminum alloy having the composition shown in Table 1 (the balance being Al and inevitable impurities) was melted and formed into a slab by semi-continuous casting. The slab was subjected to homogenization treatment, chamfering, hot rolling, and cold rolling to obtain an aluminum foil having a thickness of 7 μm. In the middle of cold rolling, intermediate annealing was performed under the condition of a thickness of 600 μm and a temperature of 360 ° C. for 4 hours.
The obtained aluminum foil was subjected to final annealing in the air under the conditions shown in Table 1 to obtain a test material.
The tensile strength and wettability of each test material were measured, and the results are shown in Table 1. The wettability was measured by a microsyringe method, and the wettability was different depending on the amount of residual rolling oil. Therefore, the wettability was used as an index for evaluating the amount of residual rolling oil.

  As shown in Table 1, it can be seen that the test material of the present invention is excellent in strength after annealing, has high wettability after annealing, and the remaining rolling oil is effectively removed. On the other hand, with respect to the composition of the present invention, in Comparative Example a in which the Zr content is too small, the strength after annealing was low, and the intended purpose could not be achieved. Moreover, in the comparative example b with excessive Zr content, the problem that rolling property fell occurred. Furthermore, in Comparative Example c in which the Fe, Si, and Cu contents are excessive, pinholes increased and the rollability decreased. Further, in Comparative Example d in which the Zr content is excessively low, the strength is remarkably lowered by annealing at a high temperature, and it cannot be used.

  Next, about the test material which has a composition of this invention, what deviated from the suitable annealing range was evaluated as a test example. In Test Example e where the temperature during annealing was low and the annealing time was short, the strength after annealing was sufficient, but the wettability was low, that is, the residual oil contamination was remarkable, and the annealing was insufficient. Further, in Test Example f in which annealing was performed at a high temperature for a long time, although the wettability was high, the strength was greatly reduced. However, it has been clarified that the degree of decrease in strength is small as compared with those outside the component range of the present invention.

Claims (2)

In mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu: 0.001% or more, 0.1% or less, Zr: 0.01% it above, containing 0.04% or less, have a composition the balance of Al and unavoidable impurities, it is intended to be subjected to a final annealing to hold 180 ° C. or higher 400 ° C. 140 hours or less 8 hours or more to less An aluminum foil with excellent strength after annealing. In mass%, Fe: more than 0.7%, 2% or less, Si: 0.01% or more, 0.7% or less, Cu: 0.001% or more, 0.1% or less, Zr: 0.01% As described above, an aluminum foil containing 0.04% or less and having the balance of Al and inevitable impurities and having a thickness of 5 to 200 μm is held at 180 ° C. or higher and 400 ° C. or lower for 8 hours or longer and 140 hours or shorter. A method for producing an aluminum foil having excellent post-annealing strength, characterized by subjecting to final annealing under conditions.