JP3529271B2 - Manufacturing method of aluminum foil - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foil used for foods and other packaging, film capacitors, labels, tobacco, etc., and particularly used for an ultrathin aluminum foil having a foil thickness of 15 μm or less. The present invention relates to a method for producing an aluminum foil having excellent pinhole characteristics.

[0002]

2. Description of the Related Art Conventionally, for aluminum or aluminum alloy for thin foil, pure aluminum such as JIS 1N30, 8079 alloy or 8021 alloy has been used as a foil material. In the following, pure aluminum and aluminum alloys are collectively referred to as aluminum. Aluminum foil is generally produced by subjecting these aluminum ingots to homogenization treatment, hot rolling, cold rolling and intermediate annealing, and then, if necessary, cold rolling. There is.

Then, the aluminum foil obtained is subjected to foil rolling and final annealing to obtain an aluminum foil. By the way, although 5.5 to 7 μm aluminum foil has been put into practical use, most of the foil demand is 6 to 7 μm, and it is desirable to use JIS1N30 for aluminum foil of the same thickness due to compatibility in foil rolling. Is strongly requested. Generally, as a problem associated with the reduction of foil thickness, the number of pinholes is significantly increased, and the barrier property against light, gas, liquid, etc., which the foil originally should have, is deteriorated, and at the time of rolling by pinholes, It is known that foil breaks occur.

It is known that finishing foil rolling of thin foil is usually carried out by polymerization rolling, and pinholes are formed at the maximum waviness of matt surface by connecting with bright surface oil pits. It is also known that pinholes are mainly governed by matte roughness as compared with surface defects such as oil pit surfaces. Further, it is considered that the oil pits are mainly controlled by rolling conditions (reduction / back tension), and the matte surface is formed by free deformation of crystal grains, and the factor controlled by the foil is large (Japanese Patent Publication No. 3-60562). No. Gazette, 70th Reconstruction of Japan Institute of Light Metals 33, 34, 35).

Therefore, in order to reduce the matte surface roughness,
As a foil capable of suppressing work hardening by decreasing the Fe solid solubility by changing the manufacturing conditions after the Fe content increase and the homogenization treatment and by refining the crystal grains, JP-A-63-2632.
It is disclosed in Japanese Patent Publication No. 2 and the like. Further, it is known to add other elements, for example, as a foil capable of exhibiting the miniaturization of crystal grains and suppression of work hardening by addition of Ni, Mn and Cr, as disclosed in JP-A-63-228228. Japanese Patent Laid-Open No. 63-282244 and Japanese Patent Laid-Open No. 8-3
It is disclosed in Japanese Patent No. 3644 and the like.

[0006]

However, Fe,
The aluminum foil material to which Ni, Mn and Cr are added does not have the above-mentioned merit of compatibility. Also, JIS1N3
With a composition equivalent to 0 (when there is no Fe content), even if the precipitation is promoted by changing the manufacturing conditions after the homogenization treatment, in the foil rolling to obtain an aluminum foil having a foil thickness of 6 to 7 μm, a large work hardening is caused. Not only can you not obtain the suppression effect,
Depending on the process change, the crystal grains may become large on the contrary, which causes problems such as an increase in the amount of pinholes and frequent occurrence of foil tears.

The present invention has been made in view of the above problems, and provides a method for producing an aluminum foil, which has a composition equivalent to JIS 1N30 and can be thinned without impairing foil rolling and pinhole characteristics. The purpose is to do.

[0008]

The method for producing an aluminum foil according to the present invention is as follows: Fe: 0.3 to 1.0% by weight, S:
i: Semi-continuous casting of a molten aluminum alloy containing less than 0.15% by weight and the balance being Al and unavoidable impurities at a cooling rate during solidification of 0.3 to 3.0 ° C./sec. after scalped, subjected to homogenizing treatment at a temperature range of 400 to 620 ° C., subjected to cold rolling after hot rolling,
By performing intermediate annealing at 300 to 450 ° C. for 2 hours or more and further cold rolling, the grain size is 0.1 to 0.8.
The average interparticle distance of the intermetallic compound of μm is 0.7 to 2.
The aluminum foil having a thickness of 5 μm is obtained , and the aluminum foil
The foil foil is rolled in a temperature range of 70 to 110 ° C.

Further, in the present invention, it is preferable that the addition amount of Cu added to the aluminum alloy is 0.02% by weight or less and the addition amount of Ti is 0.03% by weight or less.

Further, in the present invention, by controlling the cooling rate at the time of solidification by casting, homogenization treatment conditions, cold rolling rate and intermediate annealing conditions, the interparticle distance is optimized, and thus the foil rolling property is excellent. After the foil rolling, it is possible to obtain an aluminum foil with few pinholes.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION From the research on aluminum foils and foils up to now, the present inventors have found that reducing pinholes reduces matte surface roughness, that is,
It was found that it is necessary to miniaturize the deformed block when rolling the finishing foil. Furthermore, they have found that the matte surface is formed not only by the crystal grain size but also by free deformation of the dislocation cell size. Further, it is known that suppressing work hardening is effective for reducing pinholes, but it was also clarified that this was achieved by forming subgrains by dislocation organization.

Therefore, as a result of intensive studies to develop an aluminum foil having the above-mentioned characteristics, the interparticle distance of the intermetallic compound having a particle size of 0.1 to 0.8 μm was adjusted to the dislocation cell size. It has been found to be effective. Further, in the case of the JIS1N30 composition, it is difficult to adjust the interparticle distance properly only by changing the manufacturing conditions after the conventional homogenization treatment, and it is difficult to adjust the forging conditions after the homogenization treatment and the homogenization treatment. It was found that the objective can be achieved by controlling the temperature range of foil rolling while controlling the combination of foil manufacturing conditions. The present invention has been made based on this finding.

That is, in the present invention, Fe: 0.3 to 1.0% by weight, Si: less than 0.15% by weight,
A molten aluminum alloy having a composition in which the balance is Al and inevitable impurities has a cooling rate of 0.3 to 3.0 during solidification.
400 ~ 6 after semi-continuous casting at ℃ / sec and chamfering
Subjected to a homogenization treatment at a temperature range of 00 ° C., <br/> after hot rolling performed cold rolling, subjected to 2 hours or more <br/> intermediate annealing at 300 to 450 ° C., between further cold rolling By doing so, an aluminum foil having an average interparticle distance of the intermetallic compound having a particle diameter of 0.1 to 0.8 μm is 0.7 to 2.5 μm is obtained. The aluminum foil is foil-rolled in the temperature range of 70 to 110 ° C. to obtain an aluminum foil.

The reasons for limiting the components of the aluminum foil in the present invention will be described below.

[0015]Fe: 0.3 to 1.0% by weight Fe has a small solid solubility in aluminum, and
Between Al-Fe-based metals by bonding with other elements in the aluminum
An element that produces a compound. In addition, this Al-Fe system
Since the intermetallic compound of F acts as a nucleus of recrystallization,
The addition of e is effective in making the crystal grains finer. Fe content is
In the case of less than 0.3% by weight, between the metals that crystallize during casting
Insufficient number of compounds has the effect of refining crystal grains.
Hard to get. On the other hand, when the Fe content exceeds 1.0% by weight
In this case, a large number of Al-Fe-based intermetallic compounds are formed.
Therefore, the grain refining effect is great, but it is
Since the deformation resistance is increased, the rolling property is extremely reduced. Servant
Thus, the Fe content is 0.3 to 1.0% by weight.

[0016]Si: less than 0.15% by weight Si is one of the inevitable impurities in the metal. Si
Easily forms a coarse Al-Fe-Si-based intermetallic compound.
Smaller, the number of pinholes increases.
good. Therefore, the Si content is less than 0.15% by weight.
Is desirable.

[0017]Intermetallic compound with a particle size of 0.1 to 0.8 μm
Average particle-to-particle distance: 0.7 to 2.5 μm Intermetallic compounds with a particle size of 0.1 to 0.8 μm are mainly deposited.
It is a good product and is produced by homogenization, hot rolling and intermediate annealing.
To achieve. The distribution of these intermetallic compounds is
In order to affect the accumulation and rearrangement,
Affects the cell-order deformation block size in
You Average interparticle distance of deformed block size intermetallic compounds
If the separation is less than 0.7 μm, the
It becomes a stop, that is, dislocation accumulation becomes excessive, and the polymerization pressure after
Since it becomes a deformed block in units of multiple dislocation cells by extension
Moreover, the matte surface becomes rough and pinholes frequently occur. one
The mean interparticle distance of intermetallic compounds with deformed block size
If the separation exceeds 2.5 μm, it may be
Dislocation simplification becomes easier and it becomes a deformed block in a single cell.
However, the matte surface is rough because coarse cells are easily formed.
And pinholes occur frequently. Therefore, the particle size is 0.1
The average interparticle distance of the intermetallic compound of 0.8 μm is 0.7
To 2.5 μm.

Foil rolling temperature: 70 to 110 ° C. The foil rolling temperature affects the degree of dislocation accumulation and reduction, and therefore affects the dislocation cell order deformation block size in the subsequent polymerizing rolling. When the foil rolling temperature is lower than 70 ° C., the rearrangement of the foil before rising cannot be expressed, and it becomes a deformed block in a plurality of unit cells in the subsequent polymerizing rolling, so that the matte surface becomes rough and the pin There are many holes. On the other hand, when the foil rolling temperature exceeds 110 ° C., dislocation rearrangement becomes too easy, dislocation disappears before one rise, and dislocation accumulation occurs before the next rise. Since it becomes a deformed block in units of a plurality of dislocation cells, the matte surface becomes rough and pinholes frequently occur.

[0019]Cu: 0.02 wt% or less Cu is an element that forms a solid solution in aluminum, and solid solution hardening
Is effective in improving the strength of O material, and if necessary, added
You may add. When the Cu content is less than 0.005% by weight
In this case, solid solution hardening is insufficient and the O material strength is improved.
Hard to get strength. On the other hand, the Cu content is 0.02% by weight.
If it exceeds, the degree of solid solution hardening is too great and the foil is rolled.
Since the deformation resistance of No. 1 increases, the rolling property is extremely reduced.
Therefore, if Cu is 0.02 wt% or less, it is necessary.
You may add according to it.

[0020]Ti: 0.03 wt% or less Ti is added as an Al-Ti or Al-Ti-B mother alloy.
And used for refining the ingot structure. Foil pressure
If streaking becomes a problem after stretching, 0.03% by weight or more
It may be added in the range below, but without adding it
The finer the intermetallic compounds crystallized in the ingot.
Therefore, if there is no hindrance to the streak pattern, less Ti is preferable.
Yes. Therefore, if Ti is 0.03% by weight or less, it is necessary.
You may add according to.

[0021]Inevitable impurities As unavoidable impurities other than the above contained in aluminum
For Mn, Mg, Zn, Cr, V, Zr, Bi, S
n, In, Pb, etc. may be mentioned, but JIS 1100 and J
If the content range is around IS1N30, the purpose of the present invention will be impaired.
It's not like that.

Next, the reasons for limiting the condition treatment in the method for producing an aluminum foil according to the present invention will be described.

[0023]Cooling rate during solidification: 0.3 to 3.0 ° C /
sec As mentioned above, it exhibits excellent pinhole characteristics as a foil.
In order to achieve this, a metal with a grain size of 0.1 to 0.8 μm
It is necessary to optimize the average interparticle distance of the interstitial compound. This
The homogenization process that has been performed in the past
It is difficult to make adjustments only by changing the manufacturing conditions thereafter.
Combining the foil manufacturing conditions after the optimization and homogenization
The purpose is achieved by controlling by. That is,
Optimizing the cooling rate during solidification is appropriate for the distance between particles.
Will contribute to the reduction of pinholes.

When the cooling rate at the time of solidification exceeds 3.0 ° C./sec, the ingot-cast slab is subjected to subsequent homogenization treatment, hot rolling treatment and intermediate annealing, so that the supersaturated solid solution Fe is formed. The number of precipitates discharged as fine precipitates and having a grain size of 0.3 μm or less is extremely increased, and the grain size is 0.1 to 0.
The average interparticle distance of the intermetallic compound of 8 μm becomes narrow, which causes frequent occurrence of pinholes. On the other hand, if it is less than 0.3 ° C / sec, floating crystals are generated in the glass screen,
It is difficult to make an ingot as a rolling slab. Therefore, the cooling rate during solidification is 0.3 to 3.0 ° C./sec. Preferably, the cooling rate during solidification is 0.3 to 2.
4 ° C./sec.

[0025]Homogenization treatment: 400 to 620 ° C After chamfering a slab having the composition and ingot of the present invention,
Apply chemical treatment. This homogenization process controls solid solution and precipitation.
Metals with a particle size of 0.1 to 0.8 μm
It is an important process to optimize the average interparticle distance of intermetallic compounds.
Contributes to the reduction of pinholes. Homogenization temperature is 4
When the temperature is less than 00 ° C, the number of precipitates due to the precipitation of solid solution elements is
Insufficient to increase the distance between particles, pinhole
Cause frequent occurrence. It should be noted that when annealing for a long time, it is homogeneous
The solid solution element is sufficiently precipitated even when the chemical treatment temperature is less than 400 ° C.
However, it is not preferable because the production efficiency is deteriorated. on the other hand,
If the homogenization temperature exceeds 620 ° C, the solid solution element
The number of precipitates due to the precipitation of
Therefore, many pinholes are caused. Therefore, the homogenization process
The processing temperature is 400 to 620 ° C. This homogenization process
The time is not specified, but it should be 2 hours or more.
And are preferred.

The intermediate annealing: 300 to after 450 ° C. homogenization process described above, hot rolling, then subjected to cold rolling, further intermediate annealing. This annealing is performed for the purpose of precipitating and recrystallizing the solid solution element, and the above-mentioned inter-grain distance is affected by the intermediate annealing temperature. When the intermediate annealing temperature is less than 300 ° C., the number of precipitates due to the precipitation of the solid solution element becomes insufficient and the interparticle distance is widened, resulting in frequent occurrence of pinholes. When performing annealing for a long time, solid solution elements are sufficiently precipitated even if the intermediate annealing temperature is lower than 300 ° C, but this is not preferable because the production efficiency is deteriorated. on the other hand,
When the intermediate annealing temperature exceeds 450 ° C., the number of precipitates due to the precipitation of the solid solution element becomes insufficient, and the inter-grain distance is widened, so that pinholes frequently occur and the average crystal grain size becomes coarse. Material strength is also insufficient. Therefore, the intermediate annealing temperature is set to 300 to 450 ° C. This intermediate annealing time is not particularly specified, but it is preferably performed for 2 hours or more.

[0027]

EXAMPLES Examples of the aluminum foil manufactured by the manufacturing method according to the present invention will be specifically described below in comparison with comparative examples.

[0028] Table molten aluminum having the composition shown in the first embodiment the following Table 1
After semi-continuous casting at the cooling rate during solidification shown in 2 and chamfering the slab, homogenization treatment is performed at a temperature of 550 ° C for 5 hours, hot rolling is started immediately after that, and hot rolling is performed at 240 ° C. Rolling was completed to obtain an aluminum plate having a plate thickness of 5 mm. After that, cold rolling was performed at a rolling rate of 86%, and the obtained plate was 375 ° C.
Intermediate annealing was performed at the temperature of 4 hours. Further, it was cold-rolled to produce an aluminum foil having a thickness of 0.3 mm .

Various evaluations of the obtained aluminum foil
Valuable. First, the foil is rolled at the temperature shown in Table 2 below to obtain the thickness.
Of aluminum foil with a size of 6 μm and rolling during foil rolling
The sex was evaluated. As a result, smooth rolling
When the rolling was successful, ○ (good), under the same rolling conditions,
It is difficult to reduce the wall thickness or the rolling speed is high due to insufficient strength.
Traverse that cannot be performed or flatness control such as plate thickness distribution is difficult
When there was a strong tendency of occurrence of cracks, it was defined as × (bad).
In addition , those in which the slab could not be removed for rolling due to the generation of floating crystals during the ingot making were also marked as x (defective).

The foil rolling temperature is controlled by controlling the advance rate, tension, pass scale and rolling load, and the coil temperature after each foil rolling pass is measured by a contact thermometer. And the maximum temperature.

Further, the number of pinholes (having a diameter of 5 μm or more) per 1 m ² was measured with a pinhole detector for an aluminum foil having a thickness of 6 μm. 100 or less pinholes / m ² are excellent.

The cooling rate during solidification and the average interparticle distance
Away it was measured with a method described below. The cooling rate at the time of solidification is to collect a steady part on the bottom side of the molten metal by the ingot after ingot formation, then collect a small piece from the position of 100 mm from the skin of the central part of the long side surface, and further after electrolytic polishing, intersect Method and secondary branch method DAS
Was calculated by measuring Specifically, the method is described in Research Report No. 20 of the Japan Institute of Light Metals, "Dentrite Arm Spacing of Aluminum and Measuring Method of Cooling Rate", and the correction of the measured values of the intersection line method and the secondary branch method is a mathematical formula. The empirical formula shown in 1 was used. Regarding the calculation of the cooling rate at the time of solidification, Equation 2 is used when the Fe content is 0.65% by weight or less, and Equation 3 is used when the Fe content exceeds 0.65% by weight.
It was calculated using.

[0033]

## EQU1 ## dr = 1.49 × ds dr: DAS by the intersecting line method, ds: DA by the secondary branch method
S

[0034]

[ ^Formula 2] ds = 33.4 × C ^−0.33 C: Cooling rate during solidification

[0035]

[ ^Formula 3] ds = 77 × C ^−0.42 C: Cooling rate during solidification

The average interparticle distance is such that the particle diameter is 0.1 to 0.
It is the average interparticle distance of the intermetallic compound of 8 μm. The average interparticle distance was measured using a transmission electron microscope and the image processing apparatus. That is, 7.5m from aluminum foil
Take a small piece of m square, grind it to a thickness of 0.1 mm, and
mm had the disconnect out in the shape of a disc. This was subjected to dislocation removal treatment under conditions of a temperature of 350 ° C. and a time of 5 minutes, and was then jet-polished to prepare an observation sample having a thickness of 5 μm. These were observed at a magnification of 10000 times, and the total area was 3
A photograph was taken with a field number of 512 μm ² . Further, at the time of this observation, the observation volume was calculated by measuring the thickness of the observation point by the fringe method. Further, the particle size counted by this observation volume and image processing is 0.1 to 0.
The average interparticle distance was calculated based on the total number of intermetallic compounds of 8 μm.

Rolling measured and evaluated by the method described above
The properties, number of pinholes and average distance between particles are summarized in Table 2 below.
I will show you.

[0038]

[Table 1]

[0039]

[Table 2]

As shown in Table 2 above, Nos. 1 to 6 of the examples obtained good rolling property. In addition, regarding the number of pinholes, Example Nos. 1 to 6 were preferable values, and a good aluminum foil could be obtained over the whole.

On the other hand, in Comparative Example No. 20, although the number of pinholes was good, the rolling property was deteriorated due to the addition of excessive Fe. In Comparative Example No. 21, the rolling property was good, but the number of pinholes was inferior to that in the Examples because the crystal grains could not be made fine due to insufficient addition of Fe. Comparative Examples 22 and 24 were good in rolling property,
Comparative example No. 22 is a comparative example No. 2 due to the addition of excess Si.
In No. 4, a large amount of pinholes were generated due to the excessive addition of Ti. Comparative Example No. 23 had a poor rollability and a large amount of pinholes due to the addition of excessive Cu.

Comparative Examples 26, 28, 30 and 32 were rolled
Although the property was good, the cooling rate during solidification by casting was too fast than the range specified in the claims, and the average interparticle distance was narrowed, so that the matte surface became rough and extremely many pinholes were generated. Comparative Examples 25, 27, 29 and 31 are
A cooling slab could not be manufactured because the cooling rate during solidification by casting was too slow than the range specified in the claims and floating crystals were generated in the glass screen. Comparative example No.
Nos. 33 and 34 had many pinholes because the foil rolling temperature was out of the range defined in the claims.

Second Example Ingots having the same composition and cooling rate during solidification as those of Examples Nos. 1, 4 and 6 shown in Tables 1 and 2 were faced, and then homogenized as shown in Table 3. Immediately after that, hot rolling was performed to obtain an aluminum plate having a plate thickness of 5 mm. Board obtained
After cold rolling, intermediate annealing was performed under the conditions shown in Table 3 below.
Further, cold rolling was performed to produce an aluminum foil having a thickness of 0.3 mm . The aluminum foil obtained was rolled at the temperature shown in Table 3 to produce an aluminum foil having a thickness of 6 μm.

Measurement by the same method as the above-mentioned first embodiment
And evaluated rollability, number of pinholes, and average distance between particles
Are summarized in Table 3 below.

[0045]

[Table 3]

As shown in Table 3, Example No.
For Nos. 7 to 12, good rollability was obtained. Similarly, the number of pinholes was also a preferable value for Examples Nos. 7 to 12, and a good foil could be obtained over the whole.

Meanwhile, Comparative Example No.35 to 4 5 was better for rolling resistance. However, Comparative Example No. 3
In Nos. 5 to 43, since the homogenization treatment temperature or the intermediate annealing treatment temperature is out of the range defined in the claims,
The average interparticle distance was widened, so the matte surface became rough and pinholes occurred frequently. Further, in Comparative Examples Nos. 44 and 45, the pin rolling occurred frequently because the foil rolling temperature was out of the range specified in the claims.

[0048]

According to the present invention as described in detail above, the cooling rate during the casting solidification, by achieve an appropriate distance between particles by controlling the homogenization conditions及 beauty intermediate annealing condition foil rolling It is possible to obtain an aluminum foil having excellent properties and having a small number of pinholes after the foil is rolled.

Continuation of the front page (56) Reference JP-A-61-257459 (JP, A) JP-A-8-333644 (JP, A) JP-A-6-25781 (JP, A) JP-A-6-293931 (JP , A) JP-A-4-337043 (JP, A) JP-A-59-64754 (JP, A) Miki Isao, Iron index during solidification of Al-Fe alloys, light metal, Japan, Light Metal Society, 1975 January, Vol. 25, No. 1, p. 1-9 (58) Fields surveyed (Int.Cl. ⁷ , DB name) C22F 1/04-1/057 C22C 21/00-21/18

Claims (3)

(57) [Claims] 1. Fe: 0.3 to 1.0% by weight, Si:
A molten aluminum alloy containing less than 0.15% by weight and the balance being Al and unavoidable impurities is semi-continuously cast at a cooling rate during solidification of 0.3 to 3.0 ° C./sec. after cutting, subjected to a homogenization treatment at a temperature range of 400 to 620 ° C., subjected to cold rolling after hot rolling, 30
Subjected to intermediate annealing at least 2 hours at 0 to 450 ° C., further by cold rolling, grain size 0.1 to 0.8 micron m
The average interparticle distance of the intermetallic compound of 0.7 to 2.5 μ
m to obtain an aluminum foil, and the aluminum foil
A method for producing an aluminum foil, which comprises rolling the base in a temperature range of 70 to 110 ° C. 2. The method for producing an aluminum foil according to claim 1, wherein the amount of Cu added to the aluminum alloy is 0.02% by weight or less. 3. The method for producing an aluminum foil according to claim 1, wherein the amount of Ti added to the aluminum alloy is 0.03% by weight or less.