JPH01104791A - Production of electrolytic aluminum foil - Google Patents

Abstract

PURPOSE:To produce high purity electrolytic Al foil by safe work by using an electrolytic bath consisting of aluminum chloride and alkylpyridinium chloride or further contg. an org. solvent. CONSTITUTION:An electrolytic bath consisting of 50-75mol% aluminum chloride and 25-50mol% alkylpyridinium chloride having 1-5C alkyl group or further contg. an org. solvent is prepd. An Al plate as the anode is put in the electrolytic bath and electrolysis is carried out at about 0-150 deg.C temp. of the bath and about 0.1-30A/dm<2> current density to electrodeposit Al on a substrate. The deposited Al is stripped from the substrate to obtain Al foil. This electrolytic Al foil is free from pinholes and has satisfactory ductility.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing aluminum electrolytic foil at low cost using an electrolyte solution that is safe to work with.

(Prior Art) Conventionally, copper foil used for printed circuit boards and the like has been produced in a length of 3 m by electrolysis, while aluminum foil used for electrolytic capacitors and the like has been produced by a rolling method.

(Problems to be Solved by the Invention) However, in manufacturing by the rolling method, since work hardening occurs due to rolling, annealing must be repeated each time rolling is performed.
The drawback was that the structure was complicated.

Further, the thickness that can be produced by the rolling method is limited to about 3 μm, and it has been difficult to make it thinner than that.

For this reason, it is possible to manufacture aluminum foil by electrolysis like body foil, but until now no electrolytic solution has been developed that is safe to work with and can be manufactured at low cost.

The present invention is to develop an electrolytic solution as described above and produce aluminum foil by an electrolytic method.

(Means for Solving the Problems) As a result of various studies aimed at developing a method for producing aluminum foil using an electrolytic method, the inventors of the present invention have developed a method using a molten salt bath of aluminum halide and alkylpyridinium halide. did. That is, aluminum chloride 50
Electrolysis is carried out using an electrolytic bath consisting of ~75 mol% and 25-50 mol% of furkylpyridinium chloride (the alkyl group is an alkyl group of CWL 1 to 5), or an electrolytic bath to which an organic solvent is added.

M version? A mixture of 50 to 75 mol% of aluminum and 25 to 50 mol% of furkylpyridinium chloride is a eutectic mixture that melts at room temperature and ionizes to produce ^1 ions, so if electrolyzed, aluminum can be electrified at the cathode. can be analyzed. Therefore, if the electrodeposited aluminum is peeled off, it can be made into foil.

The reason why the mixing ratio of aluminum chloride should be 50 to 75 mol% is that if it is less than 50 mol%, the concentration of alkylvinonium ions will be high, and during electrolysis, the reduction reaction of these ions will proceed at the same time, causing the bath to deteriorate. If it exceeds 75 mol%, it will cause deterioration, decrease in current efficiency, and poor surface appearance of the foil.
This is because the Ii rate becomes low (and the vapor pressure becomes high).

A mixture of aluminum chloride with the above-mentioned mixing ratio,
Furkylpyridinium chloride in the electric MWL is the remainder and therefore amounts to 25 to 50 mol%.

The alkyl group of this bilinonium compound should have 1 to 5 carbon atoms since electrolysis becomes difficult when the number of carbon atoms increases.

When this electrolytic solution is blended with an organic solvent, the viscosity can be lowered, the current density during electrolysis can be increased, and the appearance of the foil can be made specular and glossy.

Examples of organic solvents include aromatic hydrocarbon solvents, such as
For example, toluene, benzene, xylene, etc. are preferable in terms of solubility, and the blending amount is 10 to 75 vol based on the total amount of aluminum chloride and furkylpyridinium chloride.
It is preferable to set it to 1%. If it is less than 10 vol%,
The blending effect is small, and when it exceeds 75 vol%, the concentration of aluminum chloride becomes low, so the current efficiency during electrolysis becomes significantly low.

The electrolyte is safe even if it comes into contact with oxygen or moisture, but in order to prevent the oxidation of ions, electrolysis must be performed in a dry, oxygen-free atmosphere (e.g., in dry N, LF, or gas). Gyoho electrolysis uses direct current or pulsed current in a dry oxygen-free atmosphere at a liquid temperature of 0 to 150°C and a current density of 0.1 to 30°C.
/d1112, if the bath temperature is lower than 0° C., solidification of the electrolyte will occur, making it difficult to perform electrolysis at a high current density. In addition, the bath temperature was increased to higher than 150°C, and the current density was increased to 30°C.
When Δ/Cl is higher than 112, the foil becomes gray and the crystals become rough dendrite crystals, which deteriorates the appearance and workability.When electrolyzing at a current density near 30^/dm2, Preferably, the bath temperature is 100°C or higher.

In order to consistently produce uniform foils using industrial continuous electrolysis, it is necessary to replenish the electrolytic bath with ^1 ions and control the ^1 ions in the bath within a certain range. When aluminum is used as the anode, aluminum is replenished from the anode, making it possible to keep the concentration of ions in the bath almost constant. When an insoluble anode (for example, Ti-PL gold alloy is used, ^1 ions are consumed, so ^1 ions are replenished by adding aluminum chloride. In this case,
A reaction occurs that generates a large amount of halogen on the anode surface, and the halogen component in the bath decreases. Because of this, the bath composition fluctuates and the bath j? Life becomes shorter.

As a foil electrodeposition base material during electrolysis, metal a-ru or metal strip (
For example, the electrodeposited aluminum foil may be peeled off using a stainless steel copper strip.

Prior to electrolysis, the metal ^1 is placed in the electric IW bath and left to stand, or 0.5^/d t is placed in the IW bath.
When electrolyzed at a low current density of n 2, impurities such as Fe, Pb, and ! Therefore, the purity of the foil can be increased.

The purity of the foil produced by an unpurified bath is about 99.00% at most, as even high-purity aluminum chloride does not contain impurities, but if the bath is purified by this purification method, the purity of the foil is about 99.00%.
．． It can be increased to about 99%.

(Example) Example 1 Using an electrolytic bath with a composition of 67 mol % aluminum chloride and 33 mol % butylpyridinium chloride, an aluminum plate was used as an anode in a nitrogen atmosphere, and the bath temperature was 40° C., the current density was 1^/ Electrolyze with DC current at dI112 and SU
Electrodeposit 2μIll of aluminum on the S430wI plate.
child. Thereafter, the aluminum was peeled off from the stainless steel grooved plate to obtain an aluminum foil. The foil showed no pinholes and was ductile.

Example 2 Using an electrolytic bath consisting of 60 mol% of aluminum chloride and 40 mol% of butylpyridinium chloride, an aluminum foil with a thickness of 3 μm was produced in the same manner as in Example 1. Electrolysis is
The test was carried out at a bath temperature of 60° C. and a pulsed current (duty ratio 1/10, average current density 5Δ/cln2), and the pinholes and ductility of the foil were as good as in Example 1.

Example 3 50% by volume of benzene was added to the electrolytic bath of Example 1, and an anode aluminum plate was electrolyzed with a direct current at 50°C and a current density of 58/d+a2 to a thickness of 20%.
A μll aluminum foil was produced.

The performance of this foil is the same as in Example 1, and the hardness is 3511v.
Met. Furthermore, the gloss was improved compared to that produced in Example 1.

Example 4 50 vol. , and an average current density of 10Δ/(IIIJ) to produce an aluminum foil with a thickness of 50 μm.

The performance of this foil was similar to that of Example 3.

Example 5 Using the electrolytic bath of Example 1, the bath temperature was 80°C and the 'Ki flow density was 2.
0 A/dm'' and electrolyzed to produce 91 pieces of aluminum foil of 3#+J!;

Example 6 Put the ^1 wire into the electrolytic bath of Example 1 and open it at 10 o'clock jn
When electrolyzed under the same conditions as in Example 1, the purity of the aluminum foil was 99.97%, compared to 99.00% before purification.
Met.

Example 7 S[I5
Electrolysis was carried out on a 430 wJ plate under the same conditions as in Example 1 to deposit 2 μIn of aluminum. Thereafter, the aluminum was peeled off from the stainless steel plate to obtain an aluminum foil. The pinholes and ductility of this foil were as good as in Example 1.

(Effects of the Invention) As described above, according to the method of the present invention, aluminum foil can be manufactured by an electrolytic method.

Claims (5)

[Claims] (1) Using an electrolytic bath consisting of 50 to 75 mol% of aluminum chloride and 25 to 50 mol% of alkylpyridinium chloride (the alkyl group has 1 to 5 carbon atoms) or an electrolytic bath in which an organic solvent is added to this bath. 1. A method for producing aluminum electrolytic foil, which comprises electrolyzing. (2) The method for producing aluminum electrolytic foil according to claim 1, wherein the organic solvent is an aromatic hydrocarbon. (3) The method for producing aluminum electrolytic foil according to claim 1, wherein the blending ratio of the organic solvent is 10 to 75 vol%. (4) Using direct current or pulse current in a dry oxygen-free atmosphere at a bath temperature of 0 to 150°C and a current density of 0.1 to 30 A.
The method for producing aluminum electrolytic foil according to claim 1, characterized in that electrolysis is carried out at /dm^2. (5) The method for manufacturing an aluminum electrolytic foil according to claim 1, characterized in that an aluminum anode is used as the anode.