JP2767280B2 - Manufacturing method of direct heat type cathode - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a direct heat type cathode used as a direct heat type linear cathode of a fluorescent display tube or the like, and particularly to a method for manufacturing a high melting point metal core wire such as tungsten. The present invention relates to an electrodeposition method for electrophoretically coating alkaline earth carbonates such as BaCO ₃ , SrCO ₃ , and CaCO ₃ .

[Conventional technology]

Conventionally, this type of electrodeposition method involves crushing an alkaline earth carbonate such as BaCO ₃ , SrCO ₃ , CaCO ₃ or a mixture thereof, a solid solution or the like into a suitable size, for example, a diameter of about 0.1 to 2.0 μm, An electrodeposition solution is prepared by suspending this and an organic binder serving as a binder in an appropriate organic solvent, and in the electrodeposition solution, as a high melting point metal core wire, for example, a tungsten core wire having a diameter of 5 to 20 μm and an electrode serving as a counter electrode. Is soaked, and a DC voltage of about 10 to 500 V is applied to perform so-called electrodeposition in which alkaline earth carbonate is electrophoretically coated on the tungsten core wire. In this case, as shown in FIG. 4, a tungsten core wire 3 is inserted into a cylindrical electrode or a plate-like electrode (not shown) as an opposing electrode 2 in the electrodeposition liquid 1, and the opposing electrode 2 is used as an anode, Electrodeposition is performed using 3 as a cathode. Incidentally, an electrolyte, a surfactant and the like may be added in order to carry out the electrodeposition effectively.

[Problems to be solved by the invention]

However, according to the electrodeposition method described above, since a cylindrical electrode or a plate-shaped electrode is used as the counter electrode 2, convection of the electrodeposition liquid 1 is prevented, and the electrodeposition liquid 1
Was thin and non-uniform, and as a result, the electrodeposition efficiency was reduced with the elapse of the electrodeposition time, and the coating was also non-uniform, so that long-time electrodeposition was impossible. In order to solve such a problem, various measures have been taken, such as increasing the stirring speed of the electrodeposition liquid 1 or disposing the counter electrode 2 only on one side. Are disturbed, and the coating becomes non-uniform, and the latter method has a problem that the cross-sectional method is not a uniform circular shape, and an improvement in this respect has been desired.

Therefore, the method for manufacturing a direct heat type cathode according to the present invention has been made in order to solve the above-mentioned conventional problems, and minimizes the change with time during electrodeposition as much as possible, and makes the electrodeposition for a long time. It is an object of the present invention to provide a method for manufacturing a direct heat type cathode in which a reduction in electrodeposition efficiency is small even when the method is carried out and a uniform coating is ensured.

[Means for solving the problem]

The method for producing a direct heat cathode of the present invention uses a perforated electrode having an opening having a minimum hole diameter of 0.5 mmφ or more and an opening ratio of 30% or more and less than 90% in area ratio as a counter electrode for a high melting point metal core wire. It is.

[Action]

In the present invention, by using a perforated electrode, convection of the electrodeposition liquid is promoted and the particle diameter is 0.1 to 2.0 μm.
Alkaline earth carbonate particles of mφ are quickly circulated in the opening, and the concentration is made uniform. Here, set the minimum hole diameter to 0.
The reason for limiting the diameter to 5 mmφ or more is that the flow rate of the particles is not rapid below this, and the area ratio of the opening is 30% to 90%.
The reason for limiting the amount to less than 30% is that if the amount is less than 30%, the flow of particles is not rapid, and if the amount exceeds 90%, the strength of the electrode becomes insufficient.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a structure of an electrodeposition apparatus for explaining one embodiment of a method of manufacturing a direct heat type cathode according to the present invention, and the same parts as those in the above-mentioned figures are denoted by the same reference numerals. .
In the figure, reference numeral 4 denotes an electrodeposition tank for accommodating the electrodeposition liquid 1, 5 denotes a direction changing spool of the tungsten core 3 disposed in the electrodeposition liquid 1, 6 denotes a core spool in which the tungsten core 3 is wound, 7 Reference numeral 8 denotes an energizing spool for applying an anode voltage to the tungsten core wire 3, and reference numeral 8 denotes a counter electrode, in which an opening 8a having a minimum hole diameter of 0.5 mmφ or more is formed in an area ratio of 30% or more and less than 90% as shown in FIG. The perforated cylindrical electrode 8 is formed by, for example, forming a punched metal into a cylindrical shape. Reference numeral 9 denotes an electrodeposition wire in which alkaline earth carbonate particles are electrodeposited on the tungsten core wire 3 by passing through the perforated cylindrical electrode 8, and 10 denotes a take-up spool for winding the electrodeposition wire 9.

In such a configuration, the tungsten core wire 3 wound around the core spool 6 is supplied by being pulled at a constant speed in the direction of arrow A by the rotating power of the take-up spool 10, and is brought into contact with the current-carrying spool 7 to contact the cathode spool. A voltage is applied and the electrode is immersed in the electrodeposition liquid 1, turned in the direction by the direction changing spool 5, and inserted through the perforated cylindrical electrode 8 to which the anode voltage is applied. The carbonate-like particles are electrophoretically electrodeposited to form an electrodeposited wire 9 and wound up on a take-up spool 10 to be completed. In this case, in the perforated cylindrical electrode 8 through which the tungsten core wire 3 is inserted, as shown in FIG. 2, an opening 8a having a minimum hole diameter of 0.5 mmφ or more has an area ratio of 30%.
The convection is promoted by ordinary stirring of the electrodeposition liquid 1 and the particle diameter is 0.1 to 2.0 μm.
Since m alkaline earth carbonate particles quickly flow through the openings 8a, the concentration of the electrodeposition liquid 1 is made uniform, and coating with a uniform film thickness is efficiently performed.

3 (a) and 3 (b) show another embodiment of the counter electrode according to the present invention. FIG. 3 (a) is a plan view from the side, and FIG. 3 (b) is the same figure. It is a BB 'line sectional view of (a). In the figure, the minimum hole diameter is 0.
A first parallel plate electrode 8A and a second parallel plate electrode 8B in which openings 8a of 5 mm square or more are formed at a ratio of 70% or more in area ratio are opposed to each other and are electrically connected, but not shown, and combined. A perforated parallel plate electrode 8 'is used. The perforated parallel plate electrode 8 'is easily formed, for example, by cutting an expanded metal into an appropriate size and electrically connecting the cut metal.

In order to make the cross section of the alkaline earth carbonate layer electrodeposited on the tungsten core wire 3 into a perfect circle by using the perforated parallel plate electrode 8 'constructed as described above, the cylinder shown in FIG. Although the configuration of the electrode 8 is preferable, the electric field of the parallel plate electrode 8 ′ can be sufficiently increased by increasing the facing area of the first parallel plate electrode 8 A and the second parallel plate electrode 8 B with respect to the diameter of the tungsten core wire 3. As a result, the cross-section also extends to the side where the parallel plate electrodes 8A and 8B are not present, and a circular section having practically no problem is obtained.

Table 1 below shows the results of experiments performed on the conventional example having no opening and the present example having the opening when the electrode shape as the counter electrode is formed in a cylindrical shape or a flat plate shape.

As is clear from Table 1 above, according to the present embodiment, the length of one uniform electrodeposition can be extended to about two to three times that of the conventional example, and the electrodeposition state is uniform and good. In addition, the electrodeposition efficiency can be improved to about two to three times the conventional example.

〔The invention's effect〕

As described above, the present invention provides an opening having a minimum hole diameter of 0.5 mmφ or more as an opposite electrode for electrodepositing alkaline earth carbonate particles on a high-melting metal core wire in an area ratio of 30% or more and 90% or more.
By using a perforated electrode having a ratio of less than
Since the convection of the electrodeposition liquid is promoted and the particles of the alkaline earth carbonate are quickly circulated through the opening, the uniform electrodeposition length can be greatly extended and a uniform and good electrodeposition state can be maintained. In addition, extremely excellent effects such as a significant improvement in electrodeposition efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of an electrodeposition apparatus for explaining one embodiment of a method of manufacturing a direct heat type cathode according to the present invention, and FIGS. 2 (a) and 2 (b) show counter electrodes according to the present invention. FIG. 3A is a plan view of a perforated cylindrical electrode viewed from the side, FIG. 3B is a sectional view taken along the line BB ', and FIGS. 3A and 3B are other examples of the counter electrode according to the present invention. 4 (a) and 4 (b) are plan views as viewed from the side of a perforated parallel plate electrode, showing a cross section taken along the line BB 'of FIG. , BB 'line sectional view. DESCRIPTION OF SYMBOLS 1 ... Electrodeposition liquid, 3 ... Tungsten core wire, 4 ... Electrodeposition tank, 5 ... Direction change spool, 6 ... Core wire spool, 7
... energized spool, 8 ... perforated cylindrical electrode, 8 '...
Perforated parallel plate electrode, 8A ... first parallel plate electrode, 8B
... Second parallel plate electrode, 8a ... opening, 9 ... electrodeposition wire, 10 ... take-up spool.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Higashi, 2160, Yatsunami, Yasu-cho, Asakura-gun, Fukuoka Prefecture 2160 Kyushu Noritake Co., Ltd. (56) References JP-A-60-63848 (JP, A) JP-A-58-192247 (JP, A) JP-A-50-55885 (JP, A) JP-A-49-10521 (JP, Y1) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 9/04 C25D 13/16

Claims (1)

(57) [Claims] 1. A high-melting metal core wire is immersed in an electrodeposition solution containing alkaline earth carbonate particles by inserting it between opposed electrodes.
In a method for producing a direct heat type cathode in which alkaline earth carbonate particles are electrodeposited on the high melting point metal core by applying a DC voltage between the high melting point metal core and the counter electrode, the counter electrode is A method for manufacturing a direct heat type cathode, comprising using a perforated electrode having an opening having a minimum hole diameter of 0.5 mmφ or more in an area ratio of 30% or more and less than 90% in area ratio.