JPH02312136A - Manufacture of charge preventing film and cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a charge preventing film having a stable charge preventing effect by coating and sintering silica sol including a conductive particle. CONSTITUTION:A particle such as being stable in a silica sol without any deterioration of its property at a temperature required for sintering is suitable for a conductive particle. Generally, the content of the conductive particle in the silica sol is preferably about 10-70wt.% with respect to a solid substance (oxide conversion) in the silica sol. It is enough for the silica sol to basically generate silica SiO2 by sintering of a tunnel kiln, infrared irradiation or the like. The concentration of the silica sol can be determined adequately, and 1-10wt.% with respect to a solid substance (oxide conversion) is preferable. As a coating method, various techniques such as spraying spin-coating, and dipping techniques can be used. A thus obtained charge preventing film is high in strength, is table without any deterioration of its property due to an exterior environment, and further can be fabricated easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing an antistatic film and a cathode ray tube using the same.

(Prior Art) The front panel of a cathode ray tube used in personal computers, various display terminals, etc. is easily charged with electricity, resulting in problems such as difficulty in viewing images due to adhesion of atmospheric dust and the like. To deal with this problem, Japanese Patent Laid-Open No. 118946/1983 discloses a technique for forming an antistatic film containing silanol groups.

5L(OR)4(R
SnO was created by normal pressure CVD on an antireflection film that was spray-coated with an alkyl group (alkyl group) and then baked.

A technique for forming an antistatic film of In, O, has been disclosed. The former is easily influenced by the external environment such as humidity and has insufficient antistatic effect. Furthermore, since the latter uses the CVD method, the manufacturing cost is high.

On the other hand, antistatic issues are not limited to cathode ray tubes.

This is also a problem for office automation equipment that has many glass and plastic parts. Particularly in copy machines and the like, static electricity is easily generated. Conventionally, conductive paints based on organic binders have been used, but they lack heat resistance.

There were problems such as weak film strength, and the stable antistatic effect was still insufficient.

(Problems to be Solved by the Invention) Although there is a wide range of demands for antistatic films as described above, the present situation is that no satisfactory film can be obtained. In particular, there has been a great desire for an antistatic film that is easy to manufacture and has a stable antistatic effect.

The present invention has been made in consideration of the above points.

It is an object of the present invention to provide a manufacturing method by which an antistatic film having a stable antistatic effect can be easily obtained, and also to provide a cathode ray tube that can obtain a good antistatic effect using this method.

[Structure of the invention]

(Means and effects for solving IAG) The present invention is a method for producing an antistatic film characterized by coating and baking a silica sol containing conductive fine particles.

The conductive fine particles may be those that are stable in the silica sol and whose characteristics do not deteriorate at the temperature required for firing. In particular, when high transmittance is required, the -order particle size is 200
SnO2 and In2O of Å or less, even 150Å or less,
At least one of these is preferred. Especially when the -order particle size is 150
When the thickness is Å or less, a film with a transmittance of 90% or more can be formed, which is effective for use in optical equipment. Also, SnO2: Sb, SnO,: P, In with additives added as necessary
2O,: Sn, etc. may also be used. The amount of these conductive fine particles in the silica sol can be set as appropriate to achieve a sheet resistance of 1010 Ω/or less, which is good for an antistatic film, but it is generally determined by the solid content (in terms of oxide) in the silica sol. On the other hand, about 10 to 70% by weight is preferable.

Regarding silica sol, basically silica (S i Oz ) can be produced by firing in a tunnel furnace, infrared irradiation, etc., but 5i (OR), an alcoholic solution containing (R is an alkyl group) as the main component is preferable because it can form a film at a low temperature of 100 to 600°C. The concentration can be set as appropriate depending on the coating conditions, but the solid content (in terms of oxide) is 1 to 10 νt.
% is desirable. Although it is a silica sol, other elements may be added, for example, M(OR) x (M; for example, Zrt
AQ2Mg, Ca) can be added.

As the coating method, various methods such as spraying, spin cord, dipping, etc. can be used. When used on the outer surface of the front panel of a cathode ray tube, it is preferable to use spray coating in order to provide an anti-reflection function.In this case, the formed film surface will have minute irregularities.
A good antireflection effect can be obtained. Although it can be adjusted in any way depending on the processing conditions, the average thickness of the formed film should be around 1000 mm, the pitch of the unevenness should be around 10 to 30 μm, and the height of the unevenness should be around 0.5 μs in terms of surface roughness. This is particularly effective in terms of optical characteristics such as resolution. Further, after forming the antistatic film according to the present invention, an antireflection film can be separately provided by spraying and baking a silica sol that does not contain conductive particles.

The antistatic film obtained by the present invention has strong film strength and is stable without deterioration of characteristics due to external environment. Also, apply
Since it can be formed by firing, it is easy to manufacture.

In particular, according to the present invention, a cathode ray tube can be obtained which is provided with antistatic ability without deteriorating its optical characteristics.

(Example) The present invention will be explained in detail below.

Examples 1 to 4 Silica sol shown in Table 1 (ethyl alcohol solution of S x (OCt Hs ) 4, 5 vt% a degree in terms of oxide) was applied on a glass plate, and the results were heat-treated under the conditions listed in the table. shows. In either case, a low resistance of 1010 Ω/hole or less can be achieved, and a good antistatic effect can be obtained.

The following is a margin: Table 1 The obtained film has a basic matrix of Sio.
It is possible to obtain an antistatic film that is strong and has excellent heat resistance and is not affected by the surrounding environment. Furthermore, Examples 3 and 4 are almost transparent and do not damage the base color. Also, the processing temperature is low. It can also be applied to plastics constituting the bodies of OA equipment, etc. 6 It is particularly suitable for use in low humidity environments where charging is likely to occur.

Coating liquids of Examples 5 to 9 and Comparative Examples having the compositions shown in Table 2 were prepared. Each solution was spin-coded onto the surface of a cathode ray tube panel and passed through a tunnel furnace at 400°C. When the panel surface resistance of each cathode ray tube was measured, it was 107 to 10,907 ports. Especially Example 2~
No. 4 had a high transmittance of 90% or more, and no clouding was observed in the drawing. In Example 5, the transparency increased when the outer surface was reheated at 800°C. Comparative Examples 10 to 14 Each of the coating solutions used in Examples 5 to 9 was applied by spraying onto the surface of a cathode ray tube panel, and the cathode ray tubes obtained by passing through a tunnel furnace were designated as Example 2a.

The surface resistance was 109Ω/mouth or less in all cases, and reflections were reduced. Particularly in Examples 11 to 13, almost no clouding was observed.

Examples 15 to 19 An alcohol solution of Si(○C2Hs)4 containing no conductive particles was applied by spraying onto the surface of each of the cathode ray tube panels of Examples 5 to 9, and the screen was heated to 150°C. These cathode ray tubes are referred to as Examples 15 to 19, respectively. The surface resistance was 10"Ω/mouth or less in all cases, and reflections were also reduced. Particularly in Examples 16 to 18, almost no clouding was observed. In addition, in Examples 1 to 19, the humidity was 1.
In an environment of 0 to 90%, the surface resistance did not rise above 1010 Ω/mouth.

Furthermore, when the time required for the induced voltage to reach OV after switching off the cathode ray tubes of Examples 5 to 19 was measured, all of them were 60 seconds or less. Against this.

In the case of the comparative example, it took more than 5 minutes.

Table 2 (Blank below) [Effects of the Invention] As explained above, according to the present invention, it is possible to easily obtain an antistatic film having a high film strength and a stable charging effect, especially for cathode ray tubes. It becomes an excellent iF antistatic film.

Agent: Patent Attorney Noriyuki Chika Same as Mitsuyuki Matsuyama

Claims (4)

[Claims] (1) A method for producing an antistatic film, which comprises applying a silica sol containing conductive fine particles and then subjecting it to heat treatment. (2) A cathode ray tube characterized in that an antistatic film is formed on the outer surface of the front panel by the manufacturing method according to claim 1. (3) The cathode ray tube according to claim 2, wherein an antireflection film is formed on the antistatic film by spray coating and baking silica sol. (4) The method for producing an antistatic film according to claim 1, wherein the conductive fine particles are fine particles containing at least one of SnO_2 and In_2O_3 as a main component and having a primary particle diameter of 150 Å or less.