JPS5846122Y2 - graphite electrode - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a graphite electrode, particularly a graphite electrode for etching aluminum.

Aluminum plates and foils used in electrolytic capacitors are electrochemically etched to create capacitors with a large capacity.

In this etching process, sulfuric acid, hydrochloric acid, oxalic acid,
Since an aqueous solution containing one or more of chromic acid, sulfamic acid, nitric acid, perchloric acid, hydrofluoric acid, etc. is used as an etching solution, a graphite material with excellent corrosion resistance is used for the cathode.

Since this graphite electrode is used as a cathode, there is almost no wear on the electrode itself, but during use, the etching solution gradually penetrates into the graphite electrode, corroding the metal lead rod connected to the top surface of the electrode plate. Conventionally, synthetic resin such as phenol resin, epoxy resin, furan resin, etc. is locally impregnated through the beam rod attachment hole, and the curing process is repeated 1 to 3 times to reduce air pressure to zero around the attachment hole.゜5～1.5kg/C
Graphite electrodes were used that had been treated to be impermeable to the extent that there would be no leakage at m2/G, but this local impregnation method required impregnating each mounting hole, which was extremely labor-intensive and difficult to mass produce. However, since it is difficult to obtain a uniform impermeability treatment layer with a constant thickness and degree of impermeability, there are also drawbacks such as variations in the service life of the metal lead rod.

The present invention relates to a graphite electrode that has been able to eliminate the above drawbacks. An impermeable graphite shoe with an internal screw hole for attaching a metal lead rod is screwed into the screw hole on the top of the graphite electrode to fix it. It is characterized by:

An example of implementing the present invention will be explained with reference to the attached drawings.

In the drawing, 1 is a metal lead rod, 2 is a graphite electrode plate supported and suspended from the bottom of this O, and the one shown is 65 x 53.
A graphite plate with dimensions of 0 x 1500 mm is used in the vertical direction, and a diameter of 4 mm is placed on its upper surface (65 x 530 mm surface).
Eight screw holes 3 of 0 mm x depth of 160 mm are drilled, and each screw hole 3 is equipped with a screw hole 4 for attaching a metal lead rod of inner diameter of 24 mm x depth of 145 mm.An impermeable graphite shoe 5 is attached to a part of the shell of the sheath. 6
The annular groove 7 provided at the top of the screw hole 3 is screwed until the screw hole 3 and the annular groove 7 come into contact with each other.

A lead rod 1 made of copper was screwed into each screw hole 4 for attaching the lead rod, and a lead plate 8 made of copper was further attached to this lead rod 1.

The impermeable graphite shoes 5 were made by impregnating an artificial graphite material with a phenol resin, curing it, applying impermeability treatment to prevent leakage at an air pressure of 4 kg/cm2G, and then processing it.

The impregnating resin may be selected as appropriate depending on the composition of the etching solution, temperature, and other usage conditions, and usually phenol resin, furan resin, divinylbenzene resin, fluororesin (for example, polytetrafluoroethylene), polyester resin, etc. are used. used.

The graphite electrode obtained by this invention was etched with an etching liquid composition:
A mixed acid aqueous solution containing 10 wt% of hydrochloric acid and 1 wt% of nitric acid,
When used as a cathode for aluminum foil etching at a liquid temperature of 60 to 80°C and a current density of 0.5 A/cm2, there was no penetration of liquid from the electrode plate to the copper lead rod, and no corrosion was observed. .

The conventional graphite electrode 10 had lead rods that were corroded due to variations in the impervious layer 9, but the product of the present invention could be used for more than two years without being replaced.

In the present invention, in order to reduce the contact resistance between the sheath and the electrode plate, or between the sheath and the lead rod, a conductive adhesive (for example, an adhesive made of silver and synthetic resin) may be applied to the sheath and the electrode plate, and the sheath and the lead rod may be attached in close contact with each other.

The graphite electrode of the present invention has the following excellent effects.

When performing conventional local impermeability treatment, the thickness of the impregnated layer must be at least 100 mm to achieve complete impermeability, and the treatment process also needs to be repeated 1 to 3 times. The idea uses a separate material to make it impermeable, so it requires less man-hours and can be mass-produced.

In addition, its impermeability is sufficient compared to the local impregnation method, and therefore, the sheath thickness is approximately 2 to 9 mm, which is sufficient for practical use.

Furthermore, by using the sheath, the thickness of the impermeable layer could be reduced, making it possible to reduce the spacing between the lead rods.

As a result, the current distribution on the electrode plate became uniform, and there were effects such as completely eliminating uneven etching of the product and improving quality.

[Brief explanation of the drawing]

Fig. 1 is a front view of a graphite electrode for etching aluminum foil according to an embodiment of the present invention, Fig. 2 is a top view thereof, Fig. 3 is an enlarged vertical cross-sectional view of the lead rod attachment part, and Fig. 4 is a conventional example. FIG. 2 shows a partially cross-sectional front view of a graphite electrode for etching aluminum foil. Explanation of symbols 1... Metal lead rod, 2...
...graphite electrode plate, 3...screw hole, 4...
・Screw hole for attaching lead rod, 5... Sheath, 6...
... Part of empty space, 7 ... Groove, 8 ... Lead plate, 9 ... Impermeability treatment layer (by local impregnation method), 10 ... ...Graphite electrode plate (conventional example).

Claims (1)

[Scope of utility model registration request] A graphite electrode made by screwing and fixing an impermeable graphite shoe with an internal screw hole for attaching a metal lead rod into the screw hole on the top of the graphite electrode.