JPH02126540A - Method of increasing rupture strength of cathode ray tube and enforced cathode ray tube - Google Patents

Abstract

PURPOSE:To increase rupture strength of a panel glass by coating a skirt portion of the panel glass of a cathode ray tube with a specific sol liquid and forming the panel glass into a minute successive membrane by heat treatment at a temperature lower than a strain point of the panel glass. CONSTITUTION:Water and acid are added to the solution composed by dissolving metallic alkoxide and metallic salt as precursor of metallic acid of one kind or more into organic solvent such as alcohol to form sol liquid in which compand is dispersed as hydrophilic oligomer. A skirt portion of a panel glass of a cathode ray tube is coated with the sol liquid and heated at a temperature lower than a strain point of the panel glass to be a minute membrane. Thus, flaw on the glass surface is restricted to grow by stress. Further, the stress is not concentrated on an edge of the flaw. Therefore, rupture strength of the cathode ray tube is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention aims to reduce the probability of cathode ray tubes being destroyed during evacuation. A method for increasing the breaking strength of a cathode ray tube by forming a coating and a reinforced cathode ray tube.

[Conventional technology] Conventionally, methods for increasing the breaking strength of glass include the air-cooling strengthening method, in which glass is heated to a temperature near its softening point and then rapidly cooled; There are two known chemical strengthening methods: and ion exchange. However, the air-cooling strengthening method requires high-temperature treatment at 700° C., which deforms the cathode ray tube, while the chemical strengthening method has problems such as high manufacturing costs and a decrease in strength due to ion migration associated with the upper temperature limit.

[Problems to be Solved by the Invention] An object of the present invention is to reduce the probability of destruction of a cathode ray tube during vacuum evacuation after sealing to 0.1% or less. Furthermore, with the recent increase in the size of panels, there is an increasing demand for their weight reduction, and the present invention is intended to make this possible.

In general, the reason why glass is much weaker than its theoretical strength and easy to break is because of the extremely small scratches that exist on the glass surface.
Riffimh Flow- is being considered. When stress is applied to the glass, it deforms in a direction that widens this flaw, causing stress concentration at the tip of the glass, causing a crack to grow and breakage. Conventional strengthening methods attempt to alleviate stress concentration at the tip of a flaw by forming a compressive stress layer on the glass surface. In the present invention, therefore, by forming a dense glassy film fixed to the glass surface, the expansion of the wound due to stress is reduced and the concentration of stress at the tip of the wound is alleviated.

[Means for Solving the Problems] The present invention has been made to solve the problems of conventional strengthening methods, such as high manufacturing costs and high-temperature treatment, and provides a method for increasing the breaking strength of cathode ray tubes and a method for reinforcing them. The present invention provides a cathode ray tube.

The purpose of coating the glass surface in the present invention is to reduce the expansion of scratches existing on the glass surface due to stress and to alleviate stress concentration at the tip of the scratch, so the coating is strongly adhered to the glass surface by chemical bonds. , it is essential that the film be a continuous glassy coating that is sufficiently dense and free of microcracks. Therefore, the coating is preferably a metal oxide that can chemically bond with the glass surface group, and its precursors include metal alkoxides, l'iriates, acetates, and metal salts of halide caps. One type or a combination of two or more types can be used, and silicon alkoxides such as ethyl silicate are particularly effective. In addition, the main component metal elements of this iTI precursor include Ti, 7. rA
A glass material made of vitreous material such as L, Na, etc. can be used. Furthermore, in order to obtain a sufficiently dense and continuous coating without microcracks, it is desirable that the sol in the coating liquid be a sufficiently hydrolyzed hydrophilic oligomer. Furthermore, when forming a film on panel glass, it is important to form a dense continuous film by heat treatment at a low temperature below the strain point (usually 30°C to 470°C). This is because if the temperature is 470° C. or lower, baking can be performed simultaneously with the frit sealing of the panel, and slow cooling is not necessary. In addition, in order to form a film by firing at a low temperature, ethyl silicate has a low condensation degree and a highly reactive surface. It is desirable to have it exist in a metastable manner.

In the present invention, for coating the panel glass with the treatment liquid, a method such as a dissipative method, a spray method, or a brush coating method can be selected as appropriate.

Further, the thickness of the coating is not particularly limited, but usually several thousand people can obtain the desired effect. In particular, when it is desired to increase the thickness of the coating, multiple coatings may be performed as necessary.

Furthermore, although the entire skirt portion of the panel glass of a cathode ray tube is usually coated, it is recommended that the coating be applied only to areas where the reinforcing effect is large, such as areas that are particularly susceptible to damage during handling or areas where tensile stress is likely to be concentrated. is also possible.

[Example] Ethyl silicate is mixed with 8 moles of ethanol and 11 times the mole of an acidic aqueous solution (all = 2 to 3) and refluxed at about 90°C for 3 hours to form a fully hydrolyzed siloxane oligomer. A sol solution with a particle size on the order of 100 particles was synthesized.

This sol solution was used as a coating solution, and was dip-coated onto a 5 mm x 5 mm x 60 mm sample piece cut out from a panel glass at a cutting speed of 10 cm/min. At this time, the sample piece has 1
The wound was inflicted using a Vickers pressure needle with a load of 1 kg. Next, this was dried at 60°C for 5 minutes, and then dried at 440°C.
Baked for 30 minutes. The thickness of the film thus produced was about 3,000. Also, the refractive index is 1.45. Dynamic indentation hardness is 380 gf/μm2, refractive index of fused silica glass is 1.458, dynamic indentation hardness is 410 gf/μm
Since the value was very close to m2, it was found that the film was a dense glassy film with no pores. The three-point bending strength of the scratched sample piece treated with such a glassy coating is approximately 800 kg/cm", which is approximately 500 kg/cm", which is the three-point bending strength of the scratched sample piece without the coating.
cm” is approximately 186 times larger.

2. Methyl silicate with 10 moles of ethanol and 2
Mix twice the molar amount of acidic aqueous solution (all = 2 to 3), and add 30
The mixture was stirred at ℃ for 2 hours to obtain a sol solution consisting of a sufficiently hydrolyzed siloxane oligomer. To this was added an equimolar titanium isopropoxide solution dissolved in 10 moles of ethanol to obtain a coating solution.

This coating liquid was dip coated on the same damaged sample piece as in Example 1, and the same heat treatment was performed. The film thus produced had a thickness of approximately 3000 mm, a refractive index of 1.95, and a dynamic indentation hardness of 340 gr/μm2. The three-point bending strength of the damaged sample piece coated with such a silica-titania mixed vitreous coating is approximately 750 kg/cm, whereas the damaged sample piece without the coating is approximately 750 kg/cm''.
It was about 1.5 times the three-point bending strength of the piece.

3. Methyl silicate with 10 moles of ethanol and 2
Mix twice the molar amount of acidic aqueous solution (pH = 2 to 3) and heat at 30°C.
The mixture was stirred for 2 hours to form a sol solution consisting of sufficiently hydrolyzed siloxane oligomers. To this, equimolar zirconium dissolved in 10 molar isopropanol, n-
A butoxide solution was added to form a coating solution.

This coating solution was dip-coated on the same damaged sample piece as in Example 1, and the same heat treatment was performed; It was 330 gf/μm2. The three-point bending strength of the scratched sample piece coated with such a silica-zirconia mixed vitreous coating is approximately 730 kg/cm2, which is approximately 15 times the three-point bending strength of the scratched sample piece without the coating. there were.

[Effects of the Invention] With the configuration described above, the present invention can coat the skirt portion of the panel glass with a continuous dense glass film at a low temperature of 470° C. or lower, which is the strain point of the panel glass. The effect of increasing the breaking strength of glass is recognized.

Claims (1)

[Scope of Claims] 1. Water and acid are added to a solution of one or more of metal alkoxides and metal salts, which are metal oxide precursors, dissolved in an organic solvent such as alcohol to convert the compound into a hydrophilic oligomer state. The breaking strength of cathode ray tubes is characterized by coating the panel glass skirt of cathode ray tubes with a sol dispersed as How to increase. 2. A method for increasing the strength of a cathode ray tube according to claim 1, which contains elements capable of forming glass, such as Ti, Zr, Al, and Na. 3. A cathode ray tube comprising a coating according to claim 1 or 2 on the panel glass skirt.