JPH0935630A - Method of forming blackened film on steel plate part for color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a blackening film in which enough radiation rate can be obtained and also adhesion is stable, by treating an iron oxalate film made on the surface in one or two kinds of atmosphere out of nitrogen gas, combustion gas, and steam. SOLUTION: An iron oxalate film is formed on the surface of a steel plate part by showering or soaking a steel plate part for a color cathode ray tube, which has iron for its main ingredient, with or in iron oxalate dilute aqueous solution of 0.2-7wt.%. Next, a blacked film is made on the steel plate part by heat-treating this part within the furnace in one or two kinds of atmosphere out of combustion gas, nitrogen gas, and steam so as to blacken it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel plate part for a color cathode ray tube in which a blackening film containing iron trioxide as a main component is formed on the surface of a steel plate part containing iron as a main component to be installed in a color cathode ray tube. The present invention relates to a method for forming a blackened film.

[0002]

2. Description of the Related Art In a general color cathode ray tube, a shadow mask as a color selection electrode, a mask frame for holding the shadow mask at its skirt portion, and a mask frame fixed to the mask frame and extended to the electron gun side. Steel plate parts mainly made of iron such as an internal magnetic shield are installed inside, and the surface of these steel plate parts prevents rusting during the production of color cathode ray tubes, reduces the diffusion of electron beams, and reduces the heat dissipation effect. For various purposes such as facilitation, a blackened film containing ferrosoferric oxide as a main component is usually formed.

This blackening film has heretofore been used for the above steel plate parts in the atmosphere of a blackening treatment furnace filled with a single gas of nitrogen gas, carbon dioxide gas, combustion gas, or steam, or a mixed gas of two or more of these gases. It was formed by charging and heating.

However, the heat treatment for forming the blackened film is performed by, for example, CO ₂ concentration of 10.5 to 11.0% and dew point of 3.
600 ° in a combustion gas atmosphere of 5 ° C to 40 ° C
When the heating is carried out at C for 10 minutes, the thickness of the blackened film formed is about 0.7 μm to 1.2 μm, and the emissivity is poor, so that various purposes of the blackened film can be achieved. Is not enough.

Further, when the heat treatment is performed in the steam atmosphere under the same temperature condition, the thickness of the blackened film formed is 2.4 μm.
The thickness is too thick as m to 4.5 μm, welding splash occurs during electric resistance welding when assembling steel plate parts, and the blackened film may be peeled off by a slight deformation.

[0006] Further, a steel plate part made of Invar material containing about 35% of nickel is difficult to form a blackening film on its surface, and is formed even by heating at 650 ° C for 10 minutes in the above combustion gas atmosphere. The blackened film is not 0.5 μm thick,
The emissivity is also poor, and since it is heated by high heat, there is a problem that the steel sheet parts press-formed with high dimensional accuracy are deformed.

[0007]

As described above, the emissivity is sufficient to prevent rusting during the manufacturing process of the color cathode ray tube, reduce the diffusion of the electron beam, and promote the heat dissipation effect. In order to obtain a blackened film that has, the conventional blackened film forming method requires heating at a considerably high temperature including the Invar material,
As a result, the assembly dimensions of the steel plate parts become worse, and if a thick blackening film is formed to obtain a high emissivity, a large amount of welding splash will occur during electrical resistance welding for the assembly of the steel plate parts. However, there is a problem that the blackened film is peeled off due to the occurrence of a crack or a slight deformation.

The present invention has been made in order to solve the above problems, and provides a blackened film which has a sufficient emissivity even in a blackening atmosphere at a relatively low temperature and has a stable adhesive force. The purpose is to obtain a blackening treatment method that can be formed.

[0009]

According to the method for forming a blackening film of a steel plate component for a color cathode ray tube according to the present invention, an iron oxalate coating film is formed on the surface of a steel plate component for a color cathode ray tube made of a steel plate member containing iron as a main component. And a step of forming a blackening film on the steel plate part on which the iron oxalate coating is formed in a single gas of nitrogen gas, combustion gas or steam, or a mixed gas atmosphere of at least two gases of these gases. .

The steel plate part for a color cathode ray tube is an invar material containing 30 to 40% of nickel in addition to iron.
Further, the step of forming the iron oxalate coating is a step of forming an iron oxalate coating on the surface of the steel sheet component by showering or dipping washing with a dilute aqueous solution of oxalic acid in the final washing step of degreasing the press-formed steel sheet component. Is.
Further, a step of forming an iron oxalate coating film on the surface of the steel plate part for a color cathode ray tube comprising a steel plate member containing iron as a main component,
It includes a step of forming a blackening film on a steel plate component on which an iron oxalate coating has been formed in a heating atmosphere of a heat treatment furnace such as a stabilization furnace, a panel baking furnace or a frit sealing furnace.

Further, the steel plate parts for a color cathode ray tube are steel plate parts taken out from the color cathode ray tube or those which have been dropped from the line during the manufacturing process of the color cathode ray tube. Also,
The concentration of the oxalic acid aqueous solution is 0.2 wt% to 7 wt%. In addition, as a reaction accelerator for forming an iron oxalate film in an aqueous solution of oxalic acid, sodium chlorate, sodium sulfite, sodium thiosulfate, manganese dioxide, nitrate, fluoride or ferric oxalate, or a mixture thereof. Is to be added.

[0012]

According to the present invention, since the iron oxalate coating film is formed on the surface of the steel sheet part in advance and then the blackening film is formed, a sufficient thickness can be obtained even in a relatively low temperature blackening atmosphere. It is possible to obtain a blackened film having a high emissivity and a stable adhesive force.

Further, in the final washing step of degreasing the press-formed steel plate parts, an iron oxalate coating film is formed on the surface of the steel plate parts by showering or dipping washing with a dilute aqueous solution of oxalic acid. Without forming an iron oxalate coating film.

Further, after the iron oxalate coating film is formed on the surface of the steel plate part in advance, it is black in the heating atmosphere of the stabilization furnace, the panel baking furnace or the frit sealing furnace which is the heat treatment furnace in the manufacturing process of the color cathode ray tube. Since the blackened film is formed, the blackened film forming step can be omitted.

Further, the present invention can be similarly applied to a steel plate part taken out from the color cathode ray tube or a steel plate part dropped in the line during the manufacturing process of the color cathode ray tube.

The concentration of the oxalic acid aqueous solution is 0.2 wt.
% To 7 wt% is sufficient, and an iron oxalate coating film can be formed in a short time by adding a reaction accelerator.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. Hereinafter, Embodiment 1 of the present invention will be described. Using a round hole shadow mask (0.13 mm thick) after press-molding degreasing made of aluminum-killed steel containing iron as the main component, immersing it in an aqueous solution of 1.0 wt% or 3.0 wt% oxalic acid for about 30 seconds. Thus, an iron oxalate coating film was previously formed on the surface of the shadow mask, and this was heated at 600 ° C. for 10 minutes in a continuous blackening furnace in a combustion gas atmosphere. The composition of the combustion gas at this time is CO ₂ : 10.8%, CO: 1.
2%, dew point: + 38 ° C. Table 1 shows various characteristics of the blackened film thus obtained and various characteristics of the blackened film obtained when the iron oxalate coating is not formed.

[0018]

[Table 1]

In Table 1, the adhesive strength column shows the number of repeated bendings or the peeling result of the cellophane tape at the bent portion after 180 ° bending, and the rust prevention column shows the peeling result during the production of the color cathode ray tube. It shows whether the rust prevention effect is good or not. The thickness of the blackening film is thicker than that when the iron oxalate coating is not formed, the emissivity is large, and the rust prevention effect is good.

The steel plate parts for a color cathode ray tube are required to have a thickness of a blackening film, which is required depending on the purpose of use, assembling method, etc.
Emissivity, adhesion and rust prevention characteristics are different.For example, the emissivity does not require a very high emissivity in the mask frame and internal magnetic shield, and the blackening film of the mask and frame assembled by electric resistance welding is not necessary. Welding splashes are less likely to occur as the thickness is thinner, and the pressing precision of the mask and frame is required compared to the internal magnetic shield, and it is necessary to prevent deformation under high temperature blackening conditions. It is necessary to select a method of forming an iron oxalate coating film that can obtain a blackened film having appropriate characteristics depending on the situation.

Embodiment 2 FIG. Using a shadow mask (0.13 mm thick) with a round hole after press molding and degreasing made of Invar material containing about 36% nickel, 1.0 wt% or 3.0 wt% was used as in the first embodiment. After immersing in an aqueous oxalic acid solution to form an iron oxalate coating film, blackening treatment was performed in a continuous blackening furnace in the combustion gas atmosphere under the same conditions. Table 2 shows various characteristics of the blackened film thus obtained and various characteristics of the blackened film obtained when the iron oxalate coating is not formed.

[0022]

[Table 2]

According to the second embodiment, the thickness of the blackened film is thicker than that when the iron oxalate film is not formed, the emissivity is large, and the rust preventing effect is the same.

Embodiment 3. In addition, the first embodiment
Using the same aluminum killed steel or invar material shadow mask as 2 above, after press molding, degreasing and cleaning with an aqueous cleaning agent,
Instead of pure water used in the final washing step, it was immersed in an aqueous oxalic acid solution having a concentration of 2.0 wt% or 5 wt% for about 30 seconds to form an iron oxalate coating on the surface of the shadow mask, which was then manufactured as a color cathode ray tube. Among the stabilizing furnace, the panel baking furnace, and the frit sealing furnace in the process, the characteristics of the blackened film obtained when heated in the atmosphere of the stabilizing furnace of 460 ° for 25 minutes, which is a relatively high temperature treatment, Table 3 compares the characteristics of the blackened film when the iron oxalate coating is not formed.

[0025]

[Table 3]

In the third embodiment, a shadow mask made of unblackened aluminum-killed steel or invar material is used, but the result of the third embodiment is that the shadow mask or the frame which has been blackened has a color once. It is effective even if it is applied to a product in which the blackening film is partially missing or thinned by passing through the cathode ray tube manufacturing line due to wear etc., and a relatively high emissivity is not required and it is not reused It can be used as a simple blackening method for steel plate parts.

As described above, by forming the iron oxalate coating film before forming the blackened film on the surface of the steel plate part, as compared with the case where the iron oxalate coating film is not formed even under the same blackening condition. It was confirmed that the blackened film formed was thick, the emissivity was improved, and the adhesion of the blackened film and the rust preventing property were comparable.

In each of the above embodiments, the blackening film is formed in the blackening atmosphere of the combustion gas, but the blackening film may be formed in the blackening atmosphere of nitrogen gas or water vapor in the same manner as above. Very good results were obtained.

When only a relatively high emissivity is required as in the case of a shadow mask, after forming an iron oxalate coating as in the third embodiment, a stabilizing furnace which is a color cathode ray tube manufacturing process is used. By passing it through, it was possible to obtain an emissivity at the same level as the emissivity obtained by the conventional blackening method.

Further, the concentration of the oxalic acid aqueous solution used in the first to third embodiments is 1.0 wt% to 5.0 wt%, and a reaction accelerator such as sulfate, nitrate, manganese dioxide, ferric oxalate is added. However, as a result of performing various tests by adding these reaction accelerators alone or by adding two or more kinds, the optimum concentration of the oxalic acid aqueous solution is 0.2 wt% to 7.
It was 0 wt%, preferably 0.5 wt% to 5.0 wt%, and good results were obtained even if the concentration of the oxalic acid aqueous solution was thin.

[0031]

As described above, according to the method for forming a blackening film of a steel plate part for a color cathode ray tube of the present invention, various characteristics which are stable and have sufficient characteristics even under the blackening treatment conditions in a relatively low temperature range are obtained. It is possible to form a blackened film having

On the surface of the steel plate component, 0.2 to 7.0 w
Since the iron oxalate coating film is formed with t% oxalic acid solution, it becomes easy to form a blackened film of an aluminum killed material or an Invar material containing nickel of 30 to 40%. The blackened film can be formed in the atmospheric heat treatment process (stabilize furnace, panel baking furnace, frit sealing furnace) that is a cathode ray tube manufacturing process.

Further, by using an oxalic acid aqueous solution for degreasing cleaning after press molding, the iron oxalate coating film can be formed without increasing the number of steps.

Also, the same effect can be obtained by applying it to a line dropping or reproduction mask.

Further, by adding a reaction accelerator such as sulfate or nitrate to the 0.2 to 7.0 wt% oxalic acid solution, it is easy to form an iron oxalate coating film on the surface of the steel plate component. it can.

Claims (7)

[Claims] 1. A step of forming an iron oxalate coating film on the surface of a steel plate part for a color cathode ray tube comprising a steel plate member containing iron as a main component, a single gas of nitrogen gas, combustion gas or water vapor,
Alternatively, the step of forming a blackening film on the steel plate component on which the iron oxalate coating has been formed in a mixed gas atmosphere of at least two gases of these gases, the formation of a blackening film on a steel plate component for a color cathode ray tube. Method. 2. The method for forming a blackened film on a steel plate part for a color cathode ray tube according to claim 1, wherein the steel plate part for a color cathode ray tube is an Invar material containing 30 to 40% of nickel in addition to iron. 3. The step of forming an iron oxalate coating film comprises a final washing step of degreasing a press-formed steel plate part,
The method for forming a blackened film on a steel plate part for a color cathode ray tube according to claim 1, which is a step of forming an iron oxalate coating film on the surface of the steel plate part by showering or dipping and cleaning with a dilute aqueous solution of oxalic acid. 4. A step of forming an iron oxalate coating film on the surface of a steel plate component for a color cathode ray tube comprising a steel plate member containing iron as a main component, heating of a heat treatment furnace such as a stabilizing furnace, a panel baking furnace or a frit sealing furnace. A method for forming a blackening film on a steel plate component for a color cathode ray tube, comprising the step of forming a blackening film on the steel plate component on which the iron oxalate coating is formed in an atmosphere. 5. The steel plate part for a color cathode ray tube according to claim 4, wherein the steel plate part for a color cathode ray tube is a steel plate part taken out from the color cathode ray tube or a steel plate part whose line has been dropped during the manufacturing process of the color cathode ray tube. Method for forming blackened film on parts. 6. The concentration of the oxalic acid aqueous solution is from 0.2 wt% to
It is 7 wt%, The blackening film forming method of the steel plate components for color cathode ray tubes according to any one of claims 1 to 5. 7. A sodium chlorate, sodium sulfite, sodium thiosulfate, manganese dioxide, nitrate, fluoride or ferric oxalate as a reaction accelerator for forming an iron oxalate film in an aqueous solution of oxalic acid, or The method for forming a blackened film on a steel plate component for a color cathode ray tube according to any one of claims 1 to 6, wherein a mixture of these is added.