JP2001202879A - Method of manufacturing radiator type cathode heater and method of manufacturing electrostatic paste used in manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiator type cathode having an insulation film of uniform thickness. SOLUTION: Alumina powder made from an insulation material is cleaned by pure water, and then is mixed with the sulfate aqueous solution being regulated to electric conductive value of 0.001-0.002 S/m. The alumina powder is filtered and dried from the sulfate aqueous solution, and then organic binder dissolved in organic solvent is added to the dried alumina powder to form an electrostatic paste. An insulation film is electrodeposited on a surface of the radiator type cathode using the electrostatic paste. Therefore, there is made the electrostatic paste having the most suitable electric conductivity in the electrodeposition, and the radiator type cathode having the insulation film of uniform thickness can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an indirectly heated cathode heater used for, for example, a cathode ray tube for display, and the like.
The present invention relates to a method for producing an electrodeposition paste used therein.

[0002]

2. Description of the Related Art FIGS. 4A and 4B are configuration diagrams showing an example of an indirectly heated cathode, and FIG. 4B is an enlarged view of a portion X in FIG. This indirectly heated cathode is used, for example, in an electron gun for a cathode ray tube. As shown in FIG. 4A, a heater 1 for heating, a cylindrical sleeve 2 arranged to cover the heater 1, It comprises a cap 3 attached to the tip of the sleeve 2 and an electron-emitting substance layer 4 coated on the surface of the cap 3.

[0003] The sleeve 2 incorporates the heater 1 and supports the cap 3, and is usually formed of a heat-resistant metal such as molybdenum, tantalum, tungsten, or stainless steel. The cap 3 supports the electron-emitting material layer 4 and is made of a heat-resistant metal such as nickel or platinum. The cap 3 reduces the alkaline earth metal oxide, which is the main component of the electron-emitting material layer 4. Contains reducing metals to help. On the other hand, the heater 1 is a double coil type in which the filament of the heating element is formed into a coil-shaped single coil, and the single coil is further formed into a coil. An alloy wire of rhenium and tungsten is used as the material of the filament.

[0004] As shown in FIG. 4 (B), the heater 1 is formed by coating a surface of a single coil filament 1 a with an insulating film 1 b. The insulating film 1b electrically insulates the filament 1a from the sleeve 2 and the cap 3, and is made of a heat-resistant insulating material such as alumina.

Conventionally, in the production of such a heater 1, the production of the material of the insulating coating 1b and the production of the filament 1a
Was applied in the following process order. (A) 1.3 kg of alumina powder and 2 liters (2 liters) of pure water are put into a narrow-mouthed pot having an inner volume of 3 liters (3 liters),
The whole container is rotated (rolled) for 15 to 30 minutes at a rotation speed of about 90 rpm and stirred. (B) The whole content of the stirred narrow-mouthed port is injected into the glass filter of the suction filtration device. (C) The pure water is filtered while sucking with a rotary pump.

(D) About 2 liters of pure water is further injected into the glass filter, followed by filtration and washing. (E) The filtered and washed alumina powder is transferred to a porcelain container, placed in a drying furnace, and dried in a nitrogen atmosphere at a temperature of about 150 ° C. for 24 hours or more. (F) Dried alumina powder, an organic solvent (for example, acetone), and an organic binder (for example, nitrocellulose) are put in a container, and the whole is rotated and stirred for 24 hours to mix.

(G) A mixture of alumina powder, an organic solvent and an organic binder is mixed with an organic base (for example, tetramethyl
Ammonium hydroxide), and rotate and stir for 48 hours to mix. Thereby, an electrodeposition paste for alumina coating (hereinafter simply referred to as “paste”) is obtained. (H) The paste prepared in the step (G) is poured into a vessel for electrodeposition, and the filament 1a to be electrodeposited is set on the counter electrode (ie, the cathode side). Then, a voltage of 200 to 500 V is applied to the filament 1a to
Energize for 1 s (second). Thus, the surface of the filament 1a is coated with the insulating film 1b made of alumina powder.

[0008]

By the way, the alumina powder used as a raw material has a variation in the electrolyte contained therein, and the cleaning treatment in the above steps (A) to (D) requires
The electrolyte cannot be adjusted to a constant. For this reason, when the paste prepared in the steps (E) to (G) is electrodeposited on the filament 1a, the thickness of the insulating coating 1b of alumina powder coated on the filament 1a is not uniform. That is, as shown in FIG. 4B, there is a tendency that the thickness (do in FIG. 4) of the outer insulating coating 1b of the double coil is small and the thickness of the inside (di in FIG. 4) is large. there were.

The insulating film 1b electrically insulates the sleeve 2 and the cap 3 from each other, and has a predetermined thickness at a portion facing the sleeve 2 and the cap 3, that is, outside the double coil. is necessary. For this reason, if the outer insulating coating 1b of the double coil is made to have a predetermined thickness, the inner insulating coating 1b becomes thicker than necessary, it takes time to heat the cathode, and the screen is displayed on the cathode ray tube surface. There was a problem that the time of the increase.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and a method of manufacturing an indirectly heated cathode heater having an insulating film having a uniform thickness, and a method of forming an electrodeposition paste used in the manufacturing thereof. It is intended to provide a manufacturing method.

[0011]

SUMMARY OF THE INVENTION A first aspect of the present invention is as follows.
Production of electrodeposition paste, alumina powder as raw material,
The treatment is performed by treating with a solution in which the electric conductivity is adjusted to a predetermined value, for example, a sulfuric acid aqueous solution, and adding an organic binder to the paste to form a paste.

Therefore, according to the first aspect of the present invention, it is possible to produce an electrodeposition paste having a suitable conductivity.
By electrodepositing the electrodeposition paste on the cathode heater, an insulating film having a uniform thickness can be formed on the surface of the cathode heater.

In the second embodiment of the present invention, the paste for electrodeposition is manufactured by first using an alumina powder as a raw material for an insulating film to be electrodeposited on the surface of a cathode heater with a solution having a concentration of 1% or more, for example, a sulfuric acid aqueous solution. Processing to give a relatively high electrical conductivity,
Next, while washing the alumina powder with pure water, a washing treatment is performed until the electric conductivity of the filtrate reaches a predetermined value, and an organic binder is added to the alumina powder after the washing treatment, and the paste is added. It is to make it.

Therefore, according to the second aspect of the present invention, it is possible to produce an electrodeposition paste having a suitable conductivity.
By electrodepositing the electrodeposition paste on the cathode heater, an insulating film having a uniform thickness can be formed on the surface of the cathode heater.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The first aspect of the present invention basically comprises mixing a washed alumina powder with a solution whose electric conductivity is adjusted to a predetermined value, and converting the alumina powder from the solution. The electrodeposition paste is formed by filtering and drying, and adding an organic binder dissolved in an organic solvent to the dried alumina powder. The degree is
It is preferably adjusted to a value of 0.001 to 0.002 S / m. However, this is merely an example, and other embodiments are possible.

In the second embodiment of the present invention, basically, an alumina powder to be an insulating material is mixed into a solution, the alumina powder is filtered from the solution, and the alumina powder is washed in the filtered alumina powder. Pure water for washing, and the filtrate after the washing is washed until the electric conductivity of the filtrate reaches a predetermined value. Thereafter, the washed alumina powder is dried, and then dissolved in the alumina powder with an organic solvent. The organic binder is added to form a paste. The solution is desirably a sulfuric acid aqueous solution, and more preferably, a solution having a concentration of 1% or more is used in order to give the alumina powder a specified conductivity or more. Further, the washing treatment of the alumina powder is preferably performed until the electric conductivity of the filtrate decreases to a value of 0.001 to 0.002 S / m.

The paste for electrodeposition prepared as described above is electrodeposited on an indirectly heated cathode heater, thereby producing an indirectly heated cathode heater.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. First Embodiment FIG. 1 is a flowchart showing a first embodiment of the method of manufacturing an indirectly heated cathode heater according to the present invention. The production of the material for the insulating film of the indirectly heated cathode heater and the coating on the filament 1a are performed in the following steps 1 to 9.

(1) Step 1 In a narrow-necked pot having an internal volume of 3 liters (3 liters), 1.3 kg of alumina powder and 2 liters (2 liters) of pure water are put.
The container is rotated and stirred at a rotation speed of about 90 rpm for 30 minutes. (2) Step 2 Into the glass filter of the suction filtration device, the entire contents of the stirred narrow-mouthed port are injected, and then 2 l of pure water is injected into the glass filter.

(3) Step 3 The pure water is filtered while suctioning with a rotary pump. (4) Step 4 The alumina powder deposited in the glass filter after the filtration was transferred to a container, and the electric conductivity of the container was adjusted to a predetermined value (for example, 0.001 to 0.002 S / m). Inject 2 l (2 l) of aqueous sulfuric acid. Then, the whole container is rotated and stirred so that the alumina powder and the aqueous solution of sulfuric acid are well mixed.

(5) Step 5 Alumina powder mixed with an aqueous sulfuric acid solution is poured into a glass filter of a suction filtration device, and the aqueous sulfuric acid solution is filtered while suctioning with a rotary pump. (6) Step 6 The alumina powder that has been washed and filtered with a sulfuric acid aqueous solution is transferred to a porcelain container and placed in a drying furnace and dried in a nitrogen atmosphere at a temperature of about 150 ° C. for 24 hours or more.

(7) Step 7 Dried alumina powder, an organic solvent such as acetone, and an organic binder such as nitrocellulose are put in a container, and the whole is rotated and stirred for 24 hours to mix. (8) Step 8 The mixture of the alumina powder, the organic solvent and the organic binder is
An organic base such as tetramethylammonium hydroxide is injected, and the mixture is rotated and stirred for 48 hours together with the container. Thereby, a paste for alumina coating is generated.

(9) Step 9 The paste produced in Step 8 is poured into a vessel for electrodeposition, and a filament 1a to be electrodeposited is set on the counter electrode. Then, a voltage of 200 to 500 V is applied to the filament 1a to energize for 0.5 to 1 s (second). Thus, the surface of the filament 1a is coated with the insulating film 1b made of alumina powder.

FIG. 2 is a graph showing the relationship between the electrical conductivity of the cleaning liquid and the ratio between the inside and outside of the thickness of the insulating film. That is, the horizontal axis of FIG. 2 shows the electric conductivity of the aqueous sulfuric acid solution used for washing the alumina powder in the above step 4. On the vertical axis, the ratio of the inner thickness to the outer thickness of the insulating film 1b coated on the filament surface in step 9 using the paste generated in steps 5 to 8 (see FIG. (di / do) is shown.

As is clear from FIG. 2, when the electric conductivity of the sulfuric acid aqueous solution is 0.001 to 0.002 S / m, the ratio between the inside and the outside is minimum, that is, the inner and outer thicknesses of the insulating film are smaller. It is almost uniform. From this, the electric conductivity of the sulfuric acid aqueous solution used for washing the alumina powder in the step 4 was set to 0.00
It is understood that the best result can be obtained by setting the value to 1 to 0.002 S / m.

As described above, in the method of manufacturing the indirectly heated cathode heater 1 of the first embodiment, in the step 4, the filtered alumina powder is replaced with sulfuric acid whose electric conductivity is adjusted to a predetermined value. Treated with aqueous solution. For this reason, the electrolyte contained in the raw material alumina powder is homogenized, and a paste having appropriate conductivity can be produced. This allows
In step 9, when the paste is electrodeposited on the filament 1a, the outside and inside of the filament 1a can be coated with the insulating film 1b having a uniform thickness.

Second Embodiment FIG. 3 is a flowchart showing a second embodiment of the method of manufacturing an indirectly heated cathode heater according to the present invention. The production of the material for the insulating film of the indirectly heated cathode heater and the coating on the filament are performed in the following steps 11 to 16. (1) Step 11 1.3 kg of alumina powder and 2 liters of 1% or more sulfuric acid aqueous solution are put into a small-necked pot having an internal volume of 3 liters for about 15 to 30 minutes and about 9 minutes.
At 0 rpm, the container is rotated and stirred.

(2) Step 12 The entire contents of the agitated narrow-mouthed port are poured into a glass filter of a suction filtration device, and the sulfuric acid aqueous solution is filtered while suctioning with a rotary pump. (3) Step 13 Further, pure water is injected into the glass filter, and the filtrate is washed and filtered while sucking the filtrate with a rotary pump. (4) Step 14 The electric conductivity of the filtrate sucked in the above step 13 is measured,
The processes of Steps 13 and 14 are continued until the value decreases to a predetermined value (for example, 0.001 to 0.002 S / m).

(5) Step 15 When the electric conductivity of the filtrate reaches a predetermined value, the washing with pure water is finished, the washed alumina powder is transferred to a porcelain container, and placed in a drying furnace. It is dried in a nitrogen atmosphere at a temperature of about 150 ° C. for at least 24 hours. (6) Step 16 Subsequent processes are the same as steps 7 to 7 in the first embodiment.
Same as 9.

As described above, in the method of manufacturing the indirectly heated cathode heater according to the second embodiment, first, in step 11, the alumina powder as a material is treated with an aqueous sulfuric acid solution so as to give conductivity of a specified value or more. Then, in steps 13 and 14, the washing is performed until the electric conductivity of the washing filtrate decreases to a predetermined value. Therefore, at the end of the washing, the electrolyte contained in the raw material alumina powder is homogenized, and a paste having appropriate conductivity can be produced. Thereby, the same advantages as those of the first embodiment can be obtained.

The present invention is not limited to the above embodiment, but can be variously modified. For example, the volume of a pot or the like of a container used for producing the paste, and the amount of raw materials, pure water for washing, and the like can be freely changed according to the production scale. Further, the processing time of each processing is a rough guide, and can be changed according to the situation.

[0032]

According to the first aspect of the present invention, the alumina contained in the alumina powder is treated with an aqueous solution of sulfuric acid whose electric conductivity is adjusted to a predetermined value. It is possible to produce a paste which is uniform and has an appropriate electrodeposition property. Then, since this paste is electrodeposited on the surface of the cathode heater, an insulating film having a uniform thickness can be formed.

According to the second aspect of the present invention, alumina powder, which is a raw material of an insulating film, is treated with a sulfuric acid aqueous solution to give a certain electric conductivity. When the electric conductivity of the filtrate of the treatment reaches a predetermined value, the washing treatment is completed, so that the electrolyte contained in the alumina powder can be made uniform and a paste having a suitable electrodeposition property is produced. be able to. Then, since this paste is electrodeposited on the surface of the cathode heater, an insulating film having a uniform thickness can be formed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a first embodiment of a method of manufacturing an indirectly heated cathode heater according to the present invention.

FIG. 2 is a graph showing the relationship between the electrical conductivity of a cleaning liquid and the ratio between the inside and outside of the thickness of an insulating film.

FIG. 3 is a flowchart showing a second embodiment of the method of manufacturing the indirectly heated cathode heater of the present invention.

FIG. 4 is a configuration diagram illustrating an example of an indirectly heated cathode.

[Explanation of symbols]

1 ... heater, 1a ... filament, 1b ...
Insulating coating.

Claims (6)

[Claims] 1. A method for manufacturing an indirectly heated cathode heater in which the surface of an indirectly heated cathode heater is coated with alumina for insulation, comprising the steps of: cleaning washed alumina powder as an insulating material; A treatment step of mixing the solution adjusted to a value of 0.002 S / m, a treatment step of filtering and drying the alumina powder from the solution, and an organic binder dissolved in the dried alumina powder with an organic solvent And a process of electrodepositing an insulating film on the surface of the indirectly heated cathode heater using the electrodepositing paste. Of manufacturing a cathode heater. 2. A method for producing an electrodeposition paste used for producing an indirectly heated cathode heater in which the surface of an indirectly heated cathode heater is coated with alumina for insulation, comprising the steps of: A process of mixing the solution adjusted to a value of 0.001 to 0.002 S / m in conductivity, a process of filtering and drying the alumina powder from the solution, and a process of drying the alumina powder. A method for producing an electrodeposition paste used for producing an indirectly heated cathode heater, comprising a treatment step of adding an organic binder dissolved in an organic solvent. 3. The indirectly heated type according to claim 2, wherein the solution in which the alumina powder is mixed is a sulfuric acid aqueous solution whose electric conductivity is adjusted to a value of 0.001 to 0.002 S / m. A method for producing an electrodeposition paste used for producing a cathode heater. 4. A method for manufacturing an indirectly heated cathode heater in which the surface of an indirectly heated cathode heater is coated with alumina for insulation, comprising: a process of mixing alumina powder as an insulating material with a solution having a concentration of 1% or more; A treatment step of filtering the alumina powder from the solution, passing pure water for washing through the filtered alumina powder, and the electric conductivity of the filtrate after washing is 0.001 to 0.002.
A treatment step of washing to a value of S / m, a treatment step of drying the washed alumina powder, and a treatment of adding an organic binder dissolved in an organic solvent to the dried alumina powder to form an electrodeposition paste A process for electrodepositing an insulating film on the surface of the indirectly heated cathode heater using the electrodeposition paste. A method for manufacturing an indirectly heated cathode heater, comprising: 5. A method for producing an electrodeposition paste used for producing an indirectly heated cathode heater in which the surface of an indirectly heated cathode heater is covered with alumina for insulation, comprising: a solution having an alumina powder as an insulating material having a concentration of 1% or more. A filtering step of filtering the alumina powder from the solution; passing pure water for washing through the filtered alumina powder; 001 to 0.002
A process of washing until the value of S / m is reached, a process of drying the washed alumina powder, and a process of adding an organic binder dissolved in an organic solvent to the dried alumina powder. A method for producing an electrodeposition paste used for producing an indirectly heated cathode heater. 6. A solution in which alumina powder is mixed with 1%
3. The method for producing an electrodeposition paste used for producing an indirectly heated cathode heater according to claim 2, wherein said sulfuric acid aqueous solution is used.