JPS63193101A - Antireflection film - Google Patents

Abstract

PURPOSE:To form an antireflection film having fine and uniform ruggedness and to increase the mechanical strength of the film by coating a soln. of a specific compd. added with fine SiO2 particles on the surface of a glass body and calcining the coating. CONSTITUTION:The antireflection film consisting of the fine SiO2 particles 1 and a thin SiO2 film coating the fine particles 1 is formed on the surface of the glass body used for a cathode ray tube liquid crystal display device, etc. This film is formed by coating an alcohol soln. of Si(OR)4 (where R is an alkyl group) added with the fine particles 1, for example, an ethanol soln. of ethyl silicate on the surface of the glass body and calcining the coating. The SiO2 formed by decomposition of the above-mentioned silicate is made continuous to form the film 2 which is fixed to the glass body. Since the film 2 having the fine and uniform ruggedness is thereby obtd., an antireflection effect is improved and the mechanical strength is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an antireflection coating on a glass surface used in cathode ray tubes, liquid crystal display devices, and other display devices.

[Conventional technology]

Conventionally, this anti-reflection coating for rice has been made by etching glass with hydrofluorosilicic acid Hz S i Fs, etc.
Depth 50-30000A on the surface, pitch 100-2
000A with unevenness to give non-reflection performance (US Patent No. 2,490,662), or s l (OR
).

(R is an alkyl group) was sprayed with an alcohol solution and then baked to form unevenness consisting of 5 lots of film (Japanese Patent Laid-Open No. 6
1-118932).

[Problem that the invention seeks to solve]

In the former conventional example, deposits from etching remain on the surface, and the etched recesses are also chemically damaged, so the wear resistance is weak, and when the surface is rubbed, the unevenness easily collapses, resulting in non-reflective performance. decreases. Also, in the latter case, sprayed 5t (oR).

The droplets of the alcohol solution spread thinly on the glass surface, and only the periphery rises high. As a result, uniform unevenness is difficult to form.

The object of the invention is to provide a glass antireflection film that has fine and uniform irregularities and has high mechanical strength.

[Means for solving problems]

The above problem can be solved by applying an alcoholic solution of Si(OR)4 (R is an alkyl group) to which fine particles of 5i(h) have been added onto the surface of the glass body and then firing the solution.

[Effect]

A thin film of S L (h) formed by hydrolysis of 81 (OR) coats uniformly dispersed S i OH fine particles and fixes them to the surface of the glass body.

〔Example〕

The surface of the glass substrate on which the antireflection film is to be formed is preheated to about 50°C. On the other hand, ethyl silica) (81 (OCIHs)
) 4) is dissolved in ethanol, and a solution is prepared by adding H,0 for hydrolysis and HNOs as a catalyst. In this solution, 5
101 fine particles (approximately spherical particle shape) are added in an amount of 10% by weight. At this time, PR of KJI liquid to ensure sufficient dispersion.
Adjust. ``This mixed solution is breathed onto the surface of the glass substrate, and further coated uniformly with a spinner.

After that, it was baked in air at 150°C for about 30 minutes, and 5i (
O1'l)a (R is C-Hs) is decomposed. Sin! added to the solution! The fine particles are decomposed and formed into S I Ox
The glass substrate is firmly fixed by a continuous, uniform thin film, and irregularities are formed on the surface of the glass substrate. By using pre-sized fine particles and uniformly dispersing them in the solution, when observed with an electron microscope, as shown in Figure 1, there were particles on the outermost surface at a depth of 1000λ±200. An antireflection film having uniform irregularities with a pitch of about 5ooX was formed. In Fig. 1, 11 is 810m fine particle, 2 is 81(O
8 i (h 2 O thin film) formed by the decomposition of R).

Light was incident on the glass surface on which this antireflection film was formed at an incident angle of 5°, and the reflectance was measured.
The reflectance was less than . This value is a value that fully satisfies the conditions for a VDT (visual display terminal).

Next, when the surface of the glass substrate on which the antireflection film was formed was rubbed vigorously 50 times with an eraser (Lion 5o-so), the reflectance was 0.1 as shown in the curved line in Figure 2.
There was no problem at all in terms of quality, with only a shift of %li degrees to the shorter wavelength side. For comparison, a similar test was conducted on a glass surface with unevenness formed by etching, and it was found that the reflectance increased by two factors after one eraser eraser, and after five erasers). The weight resistance was exactly the same as that of the untreated glass surface shown by curve I in Figure 2.

Further, even if fingerprints were attached to the surface of the antireflection film of this example, the stains could be easily wiped off with plain paper.

The reason why the reflectance can be reduced in the glass substrate on which the above-mentioned antireflection film is formed will be explained below.

In FIG. 3, the refractive index at the position indicated by A is the refractive index n6 of air, which is approximately 1. On the other hand, at the position shown in B, S t O, is packed, and its refractive index is approximately equal to the refractive index of glass (stow), ng: 1.48. In the uneven part between A and B, the refractive index is
The volume fraction of 5iQ1, when imagining a plate with a minute thickness cut on a plane parallel to planes A and B, changes continuously according to the proportion of the volume of the 8101 part in the entire volume of the plate. do. A) Slightly inside, the refractive index at the 90 position is n! , when the refractive index at position D, which is slightly outward from B, is J, the conditions for the minimum reflectance R on the glass surface on which this anti-reflection film is formed are the conditions of g-7 凰. When satisfied, non-reflective performance can be obtained.

Here, n! The value of /n1 is determined by the shape of the unevenness, but as described above, 5S(O
R) When the alcohol solution of i is baked after blood cloth,
The wheat irregularities can be formed to approximately satisfy the above formula, and lts
It is thought that the following low reflectance was obtained.

The reason why the second highest mechanical strength is obtained is 5l (OR)
This is thought to be due to the existence of a 10 g S film formed by hydrolyzing 4 as follows, and the rod is retained [the film is thin].

S l(OCgHs )4 + 4HxO−4S i
(OH) (+ 4 (4HIIOH→3101 + 2
HxO Furthermore, since fine irregularities are made uniform by the well-sized S i 02 fine particles, a good anti-reflection effect can be obtained over the entire surface, and the resolution will not be degraded due to unnecessarily irregularities.

Furthermore, as a process for forming such an anti-reflection film, commercially available S
It is only necessary to add tO, fine particles, apply, and bake, and there is no use of harmful chemicals such as hydrofluoric acid, and it can be produced safely and at low cost.

The 5tos fine particles are not limited to a spherical shape, but may have an amorphous shape as shown in FIG. In Figure 4, IA is 5101
Fine particles, two people s t O = thin film. Moreover, the particle size is preferably about 500 to 10ooX. If the particle size is too small, the outermost surface of the formed film will be too smooth, making it impossible to obtain a sufficient antireflection effect. On the other hand, if it is too large, the diffusion effect will be too large and the resolution will decrease.
The film strength also decreases.

The method of applying the alcohol solution of 81(OR)4 containing StO and fine particles is not limited to the spinning method, but may be a dipping method, a coating method, or the like.

Further, the firing temperature after coating is suitably about 50 to 200°C.

〔Effect of the invention〕

According to the present invention, an antireflection film that has excellent antireflection effects and is mechanically strong can be obtained. Moreover, the antireflection film according to the present invention can be manufactured by a simple and safe process without using harmful processing chemicals such as hydrofluoric acid, and has excellent stain resistance.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the outermost surface of an antireflection film schematically showing an embodiment of the present invention, Figure 2 is a diagram showing the measurement results of its reflectance, and Figure 3 is a diagram illustrating the principle of antireflection. Diagram for explanation,
FIG. 4 is a sectional view of the outermost surface of an antireflection film schematically showing another embodiment of the present invention. 1.1A...SIO! Fine particles, 2,2A...
・S%oz thin film.

Claims (1)

[Claims] 1. After applying an alcoholic solution of Si(OR)_4 (R is an alkyl group) to which SiO_2 fine particles have been added onto the surface of the glass body, it is fired to attach the SiO_2 fine particles and the SiO_2 thin film covering them onto the glass body surface. Anti-reflective coating made by