JPH06108209A - Aluminum foil excellent in surface cleanliness and its production - Google Patents

Abstract

PURPOSE:To produce an Al foil excellent in laminating property, printing property, and surface cleanliness by properly controlling the residual quantity of rolling oil on the surface of Al foil and the thickness of a surface oxide film, respectively, at the time of rolling and annealing an Al stock and working it into Al foil. CONSTITUTION:At the time of rolling Al and producing Al foil, rolling is done by using rolling oil as lubricant and the resulting Al foil is heated in a heating furnace of air atmosphere to undergo final annealing. As the conditions at the time of this annealing, annealing temp. is regulated so that it is not lower than the distillation end point temp. of the rolling oil remaining on the surface of the Al foil, and also annealing time (t) is regulated to a time satisfying the following inequality: 0.1<=W/(RaXt)<1/2=0.6 [where Ra is the mean value (mum), at the top and the rear surface, of average roughness along the longitudinal-direction center line at the surface of the Al foil, and W is the width (m) of the Al foil coil]. At this annealing the contact angle of the Al foil surface with pure water is regulated to <=30 deg. and also the thickness of an oxide film resulting from annealing is regulated to <=3nm, thereby, the Al foil excellent in laminating property and printing property and having superior surface cleanliness can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum foil having excellent laminating and printing properties and excellent surface cleanliness, and a method for producing the same.

[0002]

2. Description of the Related Art Aluminum foil has a plate thickness of about 5 to 200 μm and is mainly used for packaging foods, medicines and the like. This aluminum foil is often used by adhering it to polyethylene, vinyl, paper, resin or the like, and in many cases, the foil is directly printed and then laminated.

Conventionally, aluminum foils for such applications have JIS-1N30 () and JIS-1050 (Al9
9.50 wt% or more), JIS-1100 (Al-0.1
Pure aluminum such as 2 wt% Cu) is mainly used. This aluminum foil is cast into a slab by a molten aluminum or semi-continuous casting method, and is hot-rolled and cold-rolled into a plate material (foil base) having a thickness of about 0.3 to 0.6 mm. It is generally manufactured by winding a strip of foil thinned to a thickness of about 200 μm into a coil, and further subjecting it to annealing treatment (foil annealing). If necessary, the ingot is usually homogenized before hot rolling, and intermediate annealing is usually performed during cold rolling.

When the aluminum foil is rolled, a rolling oil obtained by adding a fatty acid, an alcohol, an ester or the like as an additive to a mineral oil as a base is used as a lubricant. After the rolling, the foils to be laminated are subjected to a final annealing treatment to be softened, and at the same time, a rolling oil remaining on the surface is removed by evaporation or oxidation. For this final foil annealing treatment, an atmospheric furnace that does not adjust the annealing atmosphere is often used in terms of cost.

[0005]

When there is a large amount of rolling oil remaining after annealing, when the adhesive is applied in the laminating step, the wettability with the adhesive is insufficient, and adhesive cissing occurs and good adhesion is achieved. Can't do it. Further, when printing is performed directly on the aluminum foil, there is a problem that ink repelling occurs and good printing cannot be performed.

On the other hand, the aluminum foil which has been subjected to the final annealing treatment using an atmospheric furnace has an oxide film formed by surface oxidation. This oxide film becomes thicker as the annealing treatment time becomes longer, and cohesive failure of the film is likely to occur, resulting in a problem that adhesive strength is reduced.

[0007] Therefore, the foil which is required to have the laminating property and the printing property is required to be a foil having an appropriate residual amount of rolling oil and an appropriate surface oxide film thickness and excellent surface cleanability. It is necessary to perform the final annealing under the conditions of the final foil annealing that gives good properties.

[0008]

SUMMARY OF THE INVENTION In view of this, the present invention has made various investigations, found appropriate conditions for the surface state of the foil after the final foil annealing and the final foil annealing conditions therefor, and further investigated the surface cleanliness. It has developed an excellent aluminum foil and its manufacturing method.

That is, the aluminum foil of the present invention, after foil rolling,
In a foil that is subjected to final foil annealing using an atmospheric furnace, the contact angle between the foil surface and pure water is 30 ° or less, and the surface oxide film thickness is 3 nm or less. is there.

In the manufacturing method of the present invention, after the foil rolling, the annealing time t at a temperature equal to or higher than the distillation end point temperature of the foil rolling oil is used.
(Hr) is 0.1 ≦ w / (Ra × t) ^1/2 ≦ 0.6 (where Ra is the average value of the upper and lower surfaces of the center line of the foil surface in the longitudinal direction (μm), and W is the coil width). The final annealing is performed by using an atmospheric furnace under the condition range (m).

[0011]

In the present invention, the contact angle between the aluminum foil surface after the final foil annealing and pure water is 30 ° or less. The contact angle has a correlation with the residual amount of rolling oil on the foil surface. In the case of rolling oil having the same composition, the larger the residual amount of rolling oil, the larger the contact angle.
If this contact angle exceeds 30 °, adhesive repellency, ink repellency, and reduction in contact strength occur. Therefore, the contact angle between the aluminum foil surface and pure water needs to be 30 ° or less.

The oxide film thickness is 3 nm or less. The oxide film is mainly generated by the reaction between oxygen in the atmosphere and the aluminum foil in the final foil annealing, and tends to become thicker as the annealing time becomes longer and the annealing temperature becomes higher. When the thickness of the oxide film exceeds 3 nm, the oxide film causes cohesive failure and the adhesive strength decreases. Therefore, the oxide film thickness needs to be 3 nm or less.

Next, the final foil annealing temperature of the aluminum foil is set to a temperature equal to or higher than the distillation end point temperature of the foil rolling oil. In general, rolling oil begins to evaporate when it reaches the distillation temperature and completely evaporates at the endpoint temperature. When the annealing temperature is lower than the end point temperature of the rolling oil, the rolling oil does not evaporate completely and the residual amount increases. On the other hand, even if the annealing exceeds the distillation end point temperature of the foil rolling oil + 100 ° C, not only the effect of the rolling oil evaporation is saturated, but also the growth of the oxide film on the foil surface is promoted. Therefore, the final foil annealing temperature must be higher than the distillation end point temperature of the foil rolling oil, and the end point temperature + 100
It is desirable to set the temperature below ℃.

The annealing time t (hr) is 0.1≤w /
The condition range is (Ra × t) ^1/2 ≦ 0.6. (However, Ra is the average value of the upper and lower surfaces of the average roughness along the longitudinal center line of the foil surface (μm), W is the coil width (m)) However, the temperature is maintained at the distillation end point temperature of the foil rolling oil or higher. When the time t to be performed is 0.6 <w / (Ra × t) ^1/2 , the residual amount of rolling oil increases and the contact angle exceeds 30 °. On the other hand, when w / (Ra × t) ^1/2 <0.1, not only the effect of reducing the residual amount of rolling oil is saturated, but also the growth of the surface oxide film is promoted and the annealing time is prolonged. Productivity will decrease. Therefore, the time t for keeping the temperature of the foil rolling oil at the distillation end point temperature or higher is
It must be in the range of 0.1 ≦ w (Ra × t) ^1/2 ≦ 0.6.

Here, the time of maintaining the temperature of the foil rolling oil at the distillation end point temperature or higher is defined as the time of maintaining the temperature at a constant temperature during the foil annealing and the distillation end point temperature of the foil rolling oil or higher during the temperature rising and cooling. This is the total time that the temperature has been reached. In the case of the final annealing of the foil, especially in thin foil, if the temperature is rapidly lowered, thermal strain may occur and wrinkles may occur in the foil. To prevent this, perform slow cooling at 10 ° C / hr or less. There is. Therefore, during the temperature rise and especially during the temperature decrease, the time at which the temperature is equal to or higher than the distillation end point temperature of the foil rolling oil is long and cannot be ignored.

The above conditional expression has been experimentally found, but the following theoretical estimation can be made. At the time of the final annealing, the rolling oil is vaporized to become steam, which is reduced by diffusing from the central portion in the width direction of the coil toward both end faces of the coil. Therefore, the amount of rolling oil remaining in the central portion in the width direction of the coil is the largest. At the same time, oxygen in the atmosphere diffuses from the coil end face toward the center of the coil and reacts with the rolling oil vapor or the foil surface. Therefore, the thickness of the oxide film on the foil surface at the widthwise end of the coil is the largest.

Since the rolling oil vapor moves by diffusion during foil annealing, it is presumed that it follows the diffusion formula of C = C ₀ × erf {x / 2 (Dt) ^1/2 }. However, C: residual rolling oil amount, _C0 : initial residual rolling oil amount, x: diffusion distance, D: diffusion coefficient, t: time, Since the movement is promoted, the initial residual rolling oil amount (C ₀ ) at the time when the reduction of the rolling oil vapor is due to diffusion is considered to be almost constant. Therefore, in order to keep the final target residual rolling oil amount (C) below a certain value, erf
It suffices that {x / 2 (Dt) ^1/2 } be set to a certain value or less, that is, x / (Dt) ^{1/2 be set} to a certain value or less.

Further, since the rolling path of the rolling oil vapor is a gap wound in a coil shape, the size of the gap depends on the average roughness upper and lower surfaces along the longitudinal center line of the foil surface used as a strip. It is considered to be proportional to the value (Ra), and the diffusion distance x becomes 1/2 of the coil width (that is, the width of the strip) w. The temperature dependence of diffusion is represented by D ₀ exp (−Q / RT) (Q
Is an activation energy of diffusion, R is a gas constant, T is an absolute temperature), and the final annealing temperature range of the foil is substantially 250 to
Since it is about 400 ° C., D ₀ exp in this range
Assuming that (-Q / RT) is a constant value, the above D is approximately Ra.
It is considered to be proportional to. Therefore, in order to keep the residual rolling oil amount (C) below a certain value, w / (Ra × t)
^It is considered that ^1/2 should be set to a certain value or less.

The aluminum foil used in the present invention is JI
S-1N30, JIS-1050, JIS-1100, and other pure aluminum foils and JIS-3003 (Al-0.
15 wt% Cu-1.1 wt% Mn), JIS-8079
It can be applied to any aluminum alloy foil such as (Al-0.4 wt% Si-1.0 wt% Fe).

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Example 1) Coil width of foil 0.5 m, 1.
Thickness of 0m, 1.5m JIS-1N30 alloy composition 7μ
The m foil was manufactured by a usual method to obtain a coil before annealing. The final foil rolling at the time of foil rolling was polymerized rolling, and one surface of the foil was a polymerized surface having a large waviness. The surface roughness of these foils was a polymerized surface Ra = 0.35 μm and a brided surface Ra = 0.13 μm. The average roughness of the upper and lower surfaces of the foil was Ra = 0.24 μm. Rolling oil having a distillation end point of 260 ° C. was used for foil rolling.

These foil coils were heated to 300 ° C. at a heating rate of 50 ° C./hr, and various holding times t above the end point temperature were set as shown in Table 1 and then 10
The temperature was lowered at a rate of ° C / hr. For these foils, the contact angle with pure water at the center of the coil width direction was measured, and the repellency of the paste when water-soluble glue was applied was observed. Was measured.
The results of these measurements are shown in Table 1.

[0023]

[Table 1]

As is clear from Table 1, 0.1 ≦ w /
The foils of Inventive Examples Nos. 1 to 6, which were annealed under the condition of satisfying the relationship of (Ra × t) ^1/2 ≦ 0.6, had a contact angle of 30 ° or less and did not cause adhesive cissing. Moreover, the thickness of the surface oxide film is 3 nm or less. On the other hand, 0.6 <w / (Ra ×
The foils of Comparative Examples Nos. 7, 9 and 11 having t) ^1/2 had a contact angle of more than 30 ° and adhesive cissing occurred. See you
Comparative Example No. 8, ^{1 in which} / (Ra × t) ^1/2 <0.1
The 0, 12 foils have a surface oxide film thickness of more than 3 nm.

(Example 2) The surface roughness was adjusted by adjusting the roll roughness at the time of foil rolling, the presence or absence of polymerization rolling, and the amount of reduction at the time of polymerization rolling. A 1.0 m foil was manufactured and used as a coil before annealing. Rolling oil having a distillation end point of 280 ° C. was used for foil rolling.

These foil coils were heated to 330 ° C. at a heating rate of 70 ° C./hr, and various holding times t above the end point temperature were taken as shown in Table 2 and then 40 ° C.
The temperature was lowered at a rate of / hr. The same measurements as in Example 1 were performed on these annealed foils. Table 2 shows the surface roughness of these foils and the measurement results.

[0027]

[Table 2]

As is clear from Table 2, 0.1≤w /
The foils of Inventive Examples Nos. 13 to 18 which were annealed under the condition of satisfying the relationship of (Ra × t) ^1/2 ≦ 0.6 had a contact angle of 30 °.
It is below, no adhesive repellency is generated, and the surface oxide film thickness is 3 nm or less. On the other hand, 0.6 <w / (Ra
The contact angles of the foils of Comparative Examples Nos. 19, 21, and 23 having × t) ^1/2 were over 30 °, and adhesive repelling occurred.
Comparative Example No. 2 in which w / (Ra × t) ^1/2 <0.1
The 0, 22, 24 foils have a surface oxide film thickness of more than 3 nm.

Example 3 A foil of JIS-8079 alloy composition having a thickness of 80 μm and a width of 0.8 m was produced by an ordinary method,
The coil was used before annealing. The average roughness of the upper and lower surfaces of this foil is R
It was a = 0.16 μm. Rolling oil having a distillation end point of 300 ° C. was used for foil rolling.

For these foil coils, as shown in Table 3, at 280 ° C., 350 ° C., and 4 ° C. at a heating rate of 40 ° C./hr.
After heating to a temperature of 20 ° C. and holding time t above the end point temperature as shown in Table 3, 60 ° C. /
The temperature was lowered and cooled in hr. The same measurements as in Example 1 were performed on these annealed foils. Further, a peeling test was performed on these foils by using test pieces obtained by heat-sealing a polymer film. The results of these measurements are shown in Table 3. In the table, the values in parentheses for the holding time t of Comparative Examples No. 29 to No. 32 indicate the time of holding at the annealing temperature of 280 ° C.

[0031]

[Table 3]

As is apparent from Table 3, 0.1 ≦ w /
The foils of Inventive Examples Nos. 25 to 28, which were annealed under the condition of satisfying the relationship of (Ra × t) ^1/2 ≦ 0.6, had a contact angle of 30 °.
It is below, no adhesive repellency is generated, the surface oxide film thickness is 3 nm or less, and the adhesive strength is high. On the other hand, the foils of Comparative Examples Nos. 29 to 32 whose annealing temperature was less than the distillation end point of the foil rolling oil had a contact angle of more than 30 ° at any annealing time, resulting in adhesive cissing and adhesive strength. Is low. Further, the foils of Comparative Examples No. 33 and 35 in which 0.6 <w / (Ra × t) ^1/2 have a contact angle of more than 30 °,
Adhesive repellency has occurred and the adhesive strength at the central part has decreased. Furthermore, Comparative Example N in which w / (Ra × t) ^1/2 <0.1
The foils of o.34 and 36 have a surface oxide film thickness of more than 3 nm, and the adhesive strength at the coil end is lowered.

W / (Ra x in Examples 1 to 3 above)
The relationship between t) ^1/2 and the surface cleanliness (contact angle) of the foil is shown in FIG. As is clear from the figure, 0.1 ≦ w / (Ra × t)
^The foil according to the present invention, which was annealed under the condition of ^1/2 ≦ 0.6, had a contact angle of 30 ° or less, did not cause adhesive repellency, and had a surface oxide film thickness of 3 nm or less. Yes,
High adhesive strength. On the other hand, the foil according to the comparative example in which 0.6 <w / (Ra × t) ^1/2 has a contact angle of more than 30 °, adhesive repellency is generated, and the adhesive strength is lowered. Also w /
The foil according to the comparative example in which (Ra × t) ^1/2 <0.1 has a surface oxide film thickness of more than 3 nm, and the adhesive strength at the coil end is lowered.

[0034]

As described above, according to the present invention, by controlling the residual amount of rolling oil and the thickness of the surface oxide film to be in appropriate ranges, it is possible to achieve excellent laminating and printing properties and excellent surface cleanability of aluminum. A foil can be provided, which has a remarkable effect industrially.

[Brief description of drawings]

FIG. 1 shows w / (Ra of an example of the present invention and a comparative example in Examples.
It is an actual measurement figure which shows the relationship between xt) ^1/2 and the surface cleanliness of foil, and the characteristic of foil.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Ishikawa 5-13-9 Nishinakajima, Yodogawa-ku, Osaka-shi, Osaka Shin-Osaka Mori Building, Nippon Foil Co., Ltd.

Claims (2)

[Claims] 1. A foil which is used after being subjected to final foil annealing using an atmospheric furnace after foil rolling, has a contact angle between the foil surface and pure water of 30 ° or less, and has a surface oxide film thickness. Is 3
Aluminum foil with excellent surface cleanliness, which is less than nm. 2. After the foil rolling, the annealing time t (hr) at a temperature equal to or higher than the distillation end point temperature of the foil rolling oil is 0.1 ≦ w / (Ra × t) ^1/2 ≦ 0.6 (however, Ra Is the average roughness upper and lower surface average values (μm) along the longitudinal center line of the foil surface, and W is the coil width (m)). A method for producing an aluminum foil having excellent surface cleanliness, wherein the contact angle between the surface and pure water is 30 ° or less and the thickness of the surface oxide film is 3 nm or less.