JPH0740464B2 - CRT manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cathode ray tube, and in particular, in order to avoid making an image difficult to read due to extraneous light specularly reflected on the front panel surface, it is made of SiO ₂ and is transparent and fine. The present invention relates to a method for manufacturing a cathode ray tube in which a coating film having irregularities is provided to diffusely reflect external light so as to have an antiglare effect.

[Background of the Invention] Generally, since the panel surface of a cathode ray tube is in a glossy state, external light is likely to be strongly reflected, which makes it difficult to read an image displayed on the panel surface. As a solution to this problem, there has been proposed a cathode ray tube in which a panel surface is subjected to a non-glare treatment to diffusely reflect external light. Various methods have heretofore been proposed as means for forming diffuse reflection on the surface of the panel. For example, there is a method of forming irregularities by selectively etching the glass on the surface of the cathode ray tube panel with hydrofluoric acid. According to such a method, some conditions have been put into practical use by controlling the conditions sufficiently, but pollution problems are likely to occur, scratches are likely to occur, recycling processing is impossible, and finished balls There are many problems such as the inability to process. Next, there is a method of forming irregularities on the panel surface by spraying an abrasive called a sand blast method. This method has many problems such as not being able to obtain a certain quality, being unable to be regenerated, and being likely to be mixed with foreign substances such as abrasives. Another method is to coat the plastic film, but it has many drawbacks such as scratches on the surface and easy elution into organic solvents.

Further, as disclosed in Japanese Utility Model Publication No. 44-11150, an aqueous solution of an alkali salt of silicic acid (also called water glass) is sprayed onto the surface of a cathode ray tube by a spray or the like to heat-treat the surface of the surface to make it uneven. There is also a method of forming a film. However, this method has a problem that it reacts with moisture in the air and becomes cloudy or the surface elutes because it contains an alkali.

Further, as disclosed in Japanese Utility Model Publication No. 50-26277, by spraying a mixed solution of silicon tetrachloride and alcohols or esters on the surface of a cathode ray tube panel,
There is also a method of forming a fine uneven coating film. However, although this method produces a good film, it has many problems in damaging the spray nozzle, handling the equipment in the manufacturing process, handling the solution, etc. because it is a hydrochloric acid acidic solution. Further, since halogen ions such as hydrochloric acid are directly connected to the emission slump, which is the life of the cathode ray tube, a thorough removal process of the residue is required, and there is a problem that the number of processes increases and the production cost becomes expensive. Further, in order to obtain sufficient film strength in the method for forming the uneven coating film made of SiO ₂ , at least 150 ° C. or higher, more preferably 200 ° C. or higher.
It is necessary to perform baking at ℃ or above, but in that case, the chargeability becomes strong, the charge decay rate becomes slow, and dust and dirt in the air adhere, which makes the image difficult to see after long-term use. Atsuta

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object thereof is to manufacture a cathode ray tube having a SiO ₂ antireflection coating, having a good antiglare effect, and having a small amount of charge and a high charge decay rate. To provide a method.

[Outline of Invention]

In order to achieve such an object, according to the present invention, as described above, the structure of the coating film baked at a high temperature of 150 ° C. or higher is almost all changed to a Si—O—Si siloxane structure.
Paying attention to the fact that this enhances the charging property and slows the charge decay rate, an SiO ₂ antireflection coating formed by spraying and baking an alcohol solution of Si (OR) _{4 is provided on} the outer surface of the front panel. The outermost surface layer is provided with an antistatic film containing a silanol group.

In this way, the presence of the silanol group ≡Si—OH provides the antistatic effect because the surface silanol group easily adsorbs water due to the hydrogen bond as shown by the broken line in FIG.
This is because the water content lowers the electrical resistance of the glass surface to the order of 10 ⁹ Ω.

To form an antistatic film containing a silanol group, for example, there is a method of applying a silicon tetrachloride-based antistatic agent. Also, after applying Si (OR) ₄ alcohol solution, 150 ℃ ～ 80 ℃
Even if it is fired at a low temperature of ° C, an antistatic film in which ≡Si-OH is partially left in the siloxane structure of Si-O-Si can be formed.

The overall layer structure is not limited to two layers, and may be a multilayer structure of three or more layers. In any case, the outermost surface layer may be the antistatic film.

Example of Invention

The table shows the results of examining the characteristics of real spheres on which coatings were formed under different forming conditions. In the sample, A is a reference example in which a spray solution consisting of an alcohol solution of Si (OR) ₄ was spray-applied and baked at 180 ° C for 30 minutes, and the structure of the coating was almost all Si-O- It has a siloxane structure of Si, and it takes more than 10 minutes for the induced voltage to decay to 0% of the initial value.

On the other hand, B, C, D, and E are examples in which an antistatic film formed by spraying a silicon tetrachloride-based and ethylsilicate-based antistatic agent as a spraying liquid is laminated on the film of A, and firing is not performed. In B and D, the decay time of the above induced voltage is within 5 seconds, 80 ℃
Even if it is baked for 30 minutes, it has an excellent antistatic effect within 10 seconds. All coating structures are Si
The structure was such that ≡Si—OH was included in a part of —O—Si.

Fig. 2 shows how the induced potential observed on the outer surface 5 cm above the front panel decays after the image is turned on for the real spheres coated with A, B, C, D, and E. is there.
In the figure, △ indicates (A), A indicates ○, and (B) indicates B.
D, (C) shows the respective results of C and E, but in any of the examples of B, C, D, and E, it is markedly improved as compared with A.

By thus providing the antistatic film containing a silanol group on the outermost surface layer, it is possible to eliminate the problem of adhering dirt and dust in the air and becoming dirty. In addition, Si (O
R) SiO formed by spraying and baking the alcohol solution of _4.
A good antiglare effect can be obtained by providing the transparent and fine film having fine irregularities. Particularly, if the baking temperature is 150 ° C. or higher, a sufficiently large film adhesion strength can be obtained. In the embodiment described above, HNO ₃ is added as a catalyst to the spray liquid for forming the lower SiO ₂ antireflection coating, but this has the effect of further increasing the film adhesion strength. Since the surface of the underlying SiO ₂ film has irregularities in this way, the adhesion strength of the antistatic film laminated thereon is high.

It should be noted that SiO ₂ provided with such a multi-layered antistatic film
The coating is applied so as to cover at least the effective surface of the front panel for its original purpose of preventing reflection.

〔The invention's effect〕

As described above, according to the present invention, the antistatic film is provided on the outermost surface layer of the SiO ₂ film formed by spraying and baking the alcoholic solution of Si (OR) ₄ to obtain sufficient antiglare property. Equipped with an anti-reflective coating that is effective and has no anti-static effect and is free from dirt and dust even when used for a long period of time, making the image difficult to see or causing discomfort to the user. A cathode ray tube is obtained. Especially, the underlying SiO ₂
When the film is fired at a high temperature of 150 ° C. or higher, the film strength is very strong mechanically and chemically, and a highly reliable film can be formed.

Needless to say, the method according to the present invention is a method of coating on a finished sphere, which is a method of etching the panel surface itself with hydrofluoric acid, which is conventionally performed as a non-glare treatment for diffusely reflecting external light. Since the material is not input from the member as described above, the use magnification of the member can be reduced, and the cost is very low.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the action of silanol groups in an antistatic coating showing an embodiment of the present invention, and FIG. 2 is a diagram showing an example of charging characteristics of a cathode ray tube according to the present invention.

Continuation of the front page (56) Bibliography Sho 57-154053 (JP, U) Steady Sho 48-49945 (JP, U) Steal 50-26277 (JP, Y1) Steal 45-1946 (JP , Y1)

Claims (1)

[Claims] 1. An antireflection coating having a transparent and fine irregularity of SiO ₂ is formed by spray-coating an alcohol solution of Si (OR) ₄ (R is an alkyl group) on the outer surface of the front panel and baking it at 150 ° C. or higher. After the formation, a Si (OC ₂ H ₅ ) ₄ is sprayed on the antireflection film to form an antistatic film containing a silanol group, which is a method for producing a cathode ray tube.