JPH06212375A - Production of copper foil good in water wettability - Google Patents

Abstract

PURPOSE:To provide the method for producing copper foil good in water wettability on the surface. CONSTITUTION:At first, copper foil subjected to cold rolling by the conventional well-known method is obtd. This copper foil is subjected to heating treatment at >=180 deg.C in an inert gas atmosphere or in a vacuum. Before the heating treatment is executed, if desired, degreasing treatment by the conventional well known organic solvent may be executed. By this heating treatment, rolling oil stuck on the surface of the copper foil is evaporated away. At this time, the rolling oil is removed away from the surface of the copper foil so as to regulate the wetting index into >=34 (dyne/cm). The wetting index of the copper foil small in the residual amt. of the rolling oil is regulated to >=34 (dyne/cm), and its water wettability is made good. Thus, at the time of plating the copper foil with a film made of synthetic resin, the surface of the copper foil can uniformly be coated with and adhesive soln. or the like, or by the reduction of the rolling oil interposed between the copper foil and the film made of synthetic resin, the adhesive strength between the copper foil and the film made of synthetic resin improves to better the durability of the laminated product.

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 copper foil whose surface has a property of being easily wet with water.

[0002]

2. Description of the Related Art Conventionally, copper foil has been used in various applications, but in recent years, it has begun to be used in applications such as electromagnetic wave shielding materials, flexible printed circuit boards, and battery electrode boards. For example, when it is used as an electromagnetic wave shielding material, it is not used as a single copper foil but as a synthetic resin film and a copper foil that are bonded together. Therefore, if the adhesiveness between the copper foil and the synthetic resin film is not good, the copper foil and the synthetic resin film are easily peeled off, and the durability is lowered. In addition, when used for a flexible printed circuit board, after laminating a copper foil and a synthetic resin film, a predetermined masking is applied on the copper foil, and then the copper foil at a portion where the masking is not applied. Flexible printed circuit boards have been manufactured by etching away portions. Therefore, even in this case, if the adhesion between the copper foil and the synthetic resin film is not good, the copper foil and the synthetic resin film are easily peeled off, and the circuit formed by the copper foil is likely to be short-circuited. It turns out that.

By the way, the conventional copper foil is manufactured as follows. That is, after melting and casting copper, hot rolling is performed, then cold rolling and intermediate annealing are repeatedly performed, and when the final thickness reaches 1.0 to 0.1 mm, intermediate annealing is performed and then cold rolling. Then copper foil is manufactured. Then, at the time of cold rolling, rolling oil is applied to the surface of the copper thin plate or the copper foil in order to favorably perform the cold rolling. Therefore, in order to finally remove the rolling oil adhering to the surface of the copper foil, a degreasing treatment with an organic solvent is performed as a final step. During this degreasing treatment, the rolling oil adhering to the surface of the copper foil is not completely removed, but a certain amount of it remains. The reason for this is that if the rolling oil on the copper foil is completely removed, the copper is exposed to the atmosphere and is oxidized and discolored.

The copper foil produced by the above method has a drawback that it has poor adhesion to a synthetic resin film because rolling oil adheres to the surface of the copper foil. That is, when an adhesive solution is applied to such a copper foil and bonded to a synthetic resin film, the rolling oil on the copper foil repels the adhesive solution, and uniform adhesion cannot be achieved. Further, even when the synthetic resin film is softened or melted and bonded to the copper foil, rolling oil is present between the synthetic resin film and the copper foil to reduce the adhesive force between the two. Therefore, this copper foil
It was unsuitable as a material such as an electromagnetic wave shield material.

[0005]

Therefore, according to the present invention, while suppressing the oxidation and discoloration of the copper foil surface to the minimum,
It is intended to obtain a copper foil having excellent adhesiveness with a synthetic resin film by maximally removing the rolling oil present on the surface of the copper foil.

[0006]

Means for Solving the Problems That is, according to the present invention, a copper foil rolled to a desired thickness is subjected to degreasing treatment with an organic solvent, if desired, and then under an inert gas atmosphere or under vacuum and By subjecting the rolling oil adhering to the surface of the copper foil to evaporation by heat treatment at a temperature of ℃ or more, water having a wetting index of 34 (dyne / cm) or more on the surface of the copper foil. The present invention relates to a method for producing a copper foil having good wettability.

First, in the present invention, a copper foil is manufactured by any conventionally known method. For example, after melting and casting copper, hot rolling is performed, then cold rolling and intermediate annealing are repeatedly performed, and when the final thickness reaches 1.0 to 0.1 mm, intermediate annealing is performed and then cold rolling is performed. Then, a copper foil is manufactured. The thickness of this copper foil can be arbitrarily determined, but is generally about 100 μm or less. As described above, the rolling oil remains on the surface of this copper foil.

Next, heat treatment is applied to this copper foil. The heat treatment is performed under an inert gas atmosphere or under vacuum. The reason for this is to prevent the surface of the copper foil from being easily oxidized and discolored. As the inert gas, nitrogen, argon,
Helium or the like is used. In particular, it is preferable to use nitrogen for economic reasons. For example, when heat treatment is performed in an atmosphere of an active gas atmosphere, the surface of the copper foil is oxidized and discolored, and the commercial value is reduced. The temperature of heat treatment is 180 ° C or higher. If the temperature is lower than 180 ° C. and the heat treatment is performed, the rolling oil remaining on the surface of the copper foil cannot be sufficiently removed, which is not preferable. The time of the heat treatment is a matter that can be arbitrarily determined, but is generally 3 to 25.
It's about time.

Further, in the present invention, a degreasing treatment with an organic solvent which is conventionally performed may be performed before the heat treatment. When this degreasing treatment is performed, the amount of rolling oil remaining on the surface of the copper foil decreases, and even if the temperature of the heat treatment is slightly low or the heat treatment time is slightly short,
It becomes possible to sufficiently remove the rolling oil on the surface of the copper foil.

By the above heat treatment, the rolling oil adhering to the surface of the copper foil evaporates, and the rolling oil is almost completely removed from the surface. How much rolling oil remains on the surface of the copper foil can be determined by evaluating the wettability of the surface of the copper foil. That is, the smaller the remaining amount of rolling oil, the better the water wettability. Therefore, the better the water wettability of the copper foil, the smaller the amount of rolling oil remaining, and the better the adhesiveness with the synthetic resin film. In the present invention, water wettability is measured as a wettability index (dyne / cm).
Make sure it is at least 35 (dyne / cm). Wetting index is 35
If it is less than (dyne / cm), a large amount of rolling oil still remains on the surface of the copper foil, and the adhesiveness with the synthetic resin film is not sufficiently improved, which is not preferable. The wetting index is measured according to the method described in JIS K 6768.

[0011]

【Example】

Examples 1 to 20 and Comparative Examples 1 to 6 After tough pitch copper having a purity of 99.90% or more is melted and cast, hot rolling is performed, and then cold rolling is performed. Furthermore, by repeating intermediate annealing and cold rolling, the thickness of 15
A copper foil of μm was obtained. If desired, after subjecting the copper foil to a conventionally known solvent degreasing treatment, under the conditions shown in Tables 1 and 2,
Heat treatment was performed. The wetting index (dyne / cm) on the surface of the copper foil obtained as described above was measured according to the method described in JIS K6768. In addition, those that cannot be measured with the standard solution of wetting index described in JIS K 6768 are expressed as "30 or less" or "56 or more", respectively. The above results are shown in Table 1 and Table 2.
It was shown to.

[0012]

[Table 1]

[Table 2]

As is clear from the results shown in Tables 1 and 2,
The copper foils obtained by the methods according to Examples 1 to 20 are wet as compared with those without heat treatment (Comparative Examples 1 and 2) and those with a heating temperature of 150 ° C (Comparative Examples 3 to 6). You can see that the index is large. Therefore, the residual rate of rolling oil is small on the surface of the copper foil obtained by the method according to the example, and the use of this copper foil improves the adhesiveness with the synthetic resin film. Further, as is clear from a comparison between Examples 1 and 4, for example, when the solvent degreasing treatment is performed before the heat treatment,
It can be seen that the wetting index becomes larger than that when the solvent degreasing treatment is not performed.

[0014]

As described above, if the copper foil on which the rolling oil applied during cold rolling remains is subjected to heat treatment under an inert gas atmosphere or under vacuum and at a temperature of 180 ° C. or higher. When the rolling oil evaporates and the removal proceeds, and when the copper foil and the synthetic resin film are bonded together, the adhesive force between the two is improved. Therefore, when this bonded product is used as an electromagnetic wave shielding material or the like, it is possible to obtain an electromagnetic wave shielding material or the like that is difficult to peel and has durability. Further, even when various coating materials are applied to the copper foil, almost no rolling oil remains on the surface of the copper foil, so that the adhesive force between the formed coating film and the copper foil is improved. Therefore, when the copper foil having the coating film formed thereon is applied to various uses, the durability of the copper foil is improved.

Claims (2)

[Claims] 1. A copper foil rolled to a desired thickness is subjected to a heat treatment at a temperature of 180 ° C. or higher in an inert gas atmosphere or under vacuum, whereby the copper foil adhered to the surface of the copper foil is rolled. Evaporating the oil, the wetting index of the copper foil surface is 34 (dyne / cm)
A method for producing a copper foil having good water wettability, characterized by the above. 2. A copper foil rolled to a desired thickness is subjected to a degreasing treatment with an organic solvent, and then subjected to a heat treatment at a temperature of 180 ° C. or higher under an inert gas atmosphere or in a vacuum. A method for producing a copper foil having good water wettability, characterized in that the rolling oil adhering to the surface of the copper foil is evaporated so that the wettability index of the surface of the copper foil is 34 (dyne / cm) or more.