JPH108268A - Partition membrane for electrolytic cell used for electrolytic regeneration of chloride-based etching solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a partition membrane which does not cause decrease in performance or strength even under rather high temp. condition and can realize improvement in sealing property without increase in voltage by laminating a tetrafluoroethylene resin porous body on a synthetic resin base body. SOLUTION: For example, a tetrafluoroethylene resin (PTFE)/PVAc copolymer is dissolved in methylethylketone to prepare 0.3wt.% soln. A porous PTFE film having 40μm thickness and 80% porosity is impregnated with the soln. thus prepared and then the film is fixed on a frame and dried at 60 deg.C for 5min. This procedure is repeated five times. Then the obtd. film is dipped in ethanol containing sodium methoxide and subjected to heat treatment for 30min. for saponification. The obtd. hydrophilic film is washed with water. Then the hydrophilic porous PTFE film is dipped in 1% methanol soln. for 30sec, taken out, fixed on a frame and dried at room temp. for 1hour. The dried film is laminated on a PP nonwoven fabric base body to obtain a partition membrane. The obtd. partition membrane can be used even under high temp. condition at about >60 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chloride-based etching solution containing copper or nickel, for example, a copper printed circuit board,
The present invention relates to a method for regenerating an etching solution used in a manufacturing process of a semiconductor lead frame, a cathode ray tube shadow mask, and the like, and particularly relates to a diaphragm used in an electrolytic cell used when regenerating the solution by electrolysis.

[0002]

2. Description of the Related Art The applicant of the present invention has disclosed in Japanese Patent Application Laid-Open No. HEI 5-11787.
No. 9, JP-A-6-240475, etc.
Electrolytic regeneration methods for chloride-based etchants containing copper and nickel have been proposed, but the conditions for the diaphragm of the diaphragm electrolyzer used in these electrolytic regeneration methods should be as low as possible, and the voltage rise should be as small as possible. Can be suppressed,
In order to prevent mixing of the catholyte and the anolyte, the airtightness is high, the chemical resistance is excellent, especially the chlorination resistance, and the film itself is electrically neutral, that is, has no polarity.

The diaphragm selected to satisfy these conditions in the above-mentioned publication is a filter cloth made of synthetic resin such as modacrylic or polyester, and is inexpensive.
If the temperature is lower than ℃, it is sufficient for practical use.

[0004]

However, such a synthetic resin filter cloth has a problem in terms of durability when used at a high temperature exceeding 60 ° C., and if the airtightness is to be further enhanced, It is necessary to close the stitches or increase the thickness, which results in an increase in voltage.

Therefore, the present invention provides a diaphragm to be used in an electrolytic cell for carrying out electrolytic regeneration of a chloride-based etching solution containing copper or nickel, and has a performance degradation and strength even at a high temperature of 60 ° C. or more. It is an object of the present invention to provide a diaphragm that does not decrease and that improves airtightness without increasing a voltage.

[0006]

The object of the present invention has been achieved by forming a diaphragm by laminating a porous body of tetrafluoroethylene resin (PTFE) on a synthetic resin base material. As a method of laminating the PTFE porous body on the synthetic resin substrate, a conventionally known method, for example, a method of applying a PTFE coating solution on the surface of the substrate and drying the same, and a method of laminating PTFE formed in advance.
A method of laminating the film on the surface of the substrate, a method of impregnating the porous structure of the substrate with the PTFE coating film, and the like can be given.

At that time, as a synthetic resin substrate, polyester, polypropylene, polyvinyl chloride, polyvinylidene chloride, modacrylic, acrylic, polyethylene, polysulfone, tetrafluoroethylene, vinylidene difluoride, etc.
Resin nets, nonwoven fabrics and woven fabrics that can withstand hydrochloric acid and oxidizing agents can be used. Here, the net is a net formed by integrally molding a synthetic resin, and the shape of the lattice may be any shape such as a round shape, a honeycomb shape, and a square shape, and is not particularly limited. Although mechanical strength suitable for use is required, it is preferable that the thickness be as thin as possible in the range of 50 to 1000 μm, because the electric resistance is reduced. When the base material is a non-woven fabric, compared to the base material of a woven fabric or a net, it is possible to obtain a diaphragm having a smaller thickness and sufficient mechanical strength,
Even more preferred.

[0008] The amount of water permeability, which is a measure of the airtightness of the membrane, is:
At a differential pressure of 2 kg / cm ² G, the pressure is preferably 0.5 ml / cm ² · second or less, because current efficiency can be increased.

When used in electrolytic treatment, the surface of the diaphragm that contacts the anolyte must be able to withstand strong oxidizing power such as chlorine gas, while the surface that contacts the catholyte is charged or charged by the metal deposited on the cathode. Although it is necessary to prevent metal deposition on the surface due to adhesion of particles, these conditions can be satisfied by laminating a PTFE porous body on both surfaces of the diaphragm.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on embodiments. (Production of diaphragm) A tetrafluoroethylene / vinyl acetate copolymer was dissolved in methyl ethyl ketone to prepare a 0.3% by weight solution. Porous PTF having a thickness of 40 μm and a porosity of 80%
After impregnating the E film with the above solution, it was fixed on a frame, and
Dried for minutes. The same process was repeated five times. The obtained membrane was immersed in ethanol containing sodium methoxide and heated for 30 minutes to wash the saponified hydrophilic membrane with water.

The hydrophilic porous PTFE membrane was immersed in a 1% methanol solution for 30 seconds, taken out, fixed on a frame, and dried at room temperature for 1 hour. Using a polypropylene nonwoven fabric as a base material, the above-mentioned dried film was laminated to prepare a diaphragm (thickness: 100 μm, pore size: 0.5 μm). Examination of its properties revealed that the differential pressure was 0.2 kg / cm ² G at 0.2 kg / cm ² G.
The amount of water permeation of ml / cm ² · sec was shown.

(Electrolytic Treatment) Using the electrolytic cell provided with the diaphragm prepared as described above, a copper chloride solution was subjected to electrolytic treatment by a batch method. The composition of the stock solution was 23 g / l of divalent copper and 105 g / l of chlorine, and 1100 ml of this solution was filled in an electrolytic cell. The cathode plate on the cathode chamber side partitioned by a diaphragm uses expanded metal of titanium, and the anode plate is RuO ₂ / T.
i (DSA, so-called dimensionally stable anode) expanded metal was used. The current density based on the geometric area is 125 mA /
Electrolysis was performed at a total current of 10 A in cm ² . The energization time was 30 minutes, and the composition after the electrolysis was analyzed by mixing a catholyte and an anolyte. The results are as follows.

[0013]

[Table 1]

[0014]

By using the diaphragm according to the present invention, electrolysis can be performed with low voltage and high current efficiency, and the size of the electrolysis apparatus can be reduced. That is, by increasing the current efficiency, the power supply capacity can be reduced, and the electrode area can be reduced. Along with this, it has become possible to bring out a reduction in running costs.

Claims (4)

[Claims] 1. A diaphragm for an electrolytic cell used for regenerating an etchant, comprising a PTFE porous body laminated on a synthetic resin base material. 2. The method according to claim 1, wherein the substrate is at least one selected from the group consisting of polyester, polypropylene, polyvinyl chloride, polyvinylidene chloride, modacrylic, acrylic, polyethylene, polysulfone, tetrafluoroethylene, and vinylidene fluoride. The diaphragm according to claim 1, comprising a resin. 3. The synthetic resin substrate is made of a nonwoven fabric,
The diaphragm according to claim 1 or 2, wherein a porous PTFE body is laminated on both surfaces thereof. 4. The water permeability is 0.5 at a differential pressure of 2 kg / cm ² G.
2. The flow rate is not more than ml / cm ² · second.
The diaphragm according to any one of claims 3 to 3.