JP2001019473A - Sealing material for display tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the volatilization of a boric acid component and a phosphoric acid component in firing and to prevent the generation of bubbles by incorporating a PbO-B2O3, P2O5-SnO or P2O5-SnO-B2O3 glass powder and specifying water content. SOLUTION: This sealing material contains a glass powder containing B2O3 and/or P2O5 and capable of sealing at a low temperature, e.g. a PbO-B2O3, P2O5-SnO or P2O5-SnO-B2O3 glass powder and has <=100 ppm, preferably about <=50 ppm water content. The glass powder having a low water content is obtained by bubbling oxygen or an inert gas such as nitrogen in the melting of glass. Thus, the evaporation of water in firing is reduced, so that the volatilization of a boric acid component and a phosphoric acid component are reduced, the generation of bubbles from the sealing material is prevented and an adverse effect on the electron emission part of a display tube is eliminated. The sealing material is applicable to the sealing of a cathode-ray tube, a plasma display, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CR)
T), a sealing material for a display tube used for sealing a plasma display (PDP), a fluorescent display tube (VFD), a field emission display (FED), and the like.

[0002]

2. Description of the Related Art For sealing a cathode ray tube, a plasma display, a fluorescent display tube, a field emission display and the like, a sealing temperature is 430 to 500 ° C. and a thermal expansion coefficient is 70 to 100 × 1.
A material having a characteristic of about 0 ⁻⁷ / ° C. is used.

Conventionally, in this type of sealing material, the sealing material mainly composed of sealing possible PbO-B ₂ O ₃ -based glass at low temperatures has been widely used. Also from the viewpoint of environmental problems in recent years, and the sealing material is obtained which does not contain lead, P ₂ O ₅
Sealing material using -SnO-based glass or _{P 2 O 5 -SnO-B 2} O 3 based glass has been proposed.

[0004]

However, in the above-mentioned conventional sealing material, the boric acid component and the phosphoric acid component are liable to volatilize at the time of firing, so that bubbles are generated from the material, and the electron emission portion of the display tube is generated. May adversely affect the system.

An object of the present invention is to provide a display tube sealing material in which a boric acid component and a phosphoric acid component hardly volatilize during firing.

[0006]

As a result of various studies, the present inventor has found that if the amount of water contained in the material is large, the volatilization amount of the boric acid component and the phosphoric acid component increases, and the present invention provides It is a suggestion.

That is, the sealing material for a display tube of the present invention is a sealing material for a display tube containing glass powder, and has a water content of 100 ppm or less.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sealing material for a display tube of the present invention contains glass powder as a main component. Adjustment of thermal expansion coefficient,
Various refractory filler powders and the like can be contained for the purpose of improving mechanical strength, improving fluidity, and the like.

Further, the sealing material of the present invention is characterized in that the water content is 100 ppm or less. When the water evaporates during firing, the boric acid component and the phosphoric acid component in the glass are also volatilized. However, when the water content is 100 ppm or less, the volatilization amount of the water decreases. The acid component is less likely to evaporate.

More specifically, even with the same water content, there are components that are easily volatilized during firing and components that are hardly volatilized. Further, since most of the water is contained in the glass powder, the volatilization amount depends on the composition system of the glass. According to the study of the present inventors, among the glass components generally used for the sealing material, the borate component is the most volatile, and then the phosphoric acid component. In addition, P ₂ O ₅ -based glass has a more fragile network than PbO-based glass, and thus tends to increase the amount of volatilization. The following, among glass used for sealing the display tube, PbO-B ₂ O ₃ based glass is the main composition system, P ₂ O ₅ -SnO-based glass, P ₂ O ₅ -SnO-B
_{The 2} O ₃ glass will be described.

When a PbO—B ₂ O ₃ -based glass containing PbO as a main component is used, since the glass network is robust, the water content is 100 ppm or less (preferably 50 ppm).
(ppm or less), the volatilization of the boric acid component does not appear remarkably, and there is no possibility of causing a problem. As a preferable example of the glass of this system, for example, PbO 60
_{~90%, B 2 O 3 5~25} %, SiO 2 0~5%,
0% ZnO, include glass having a composition of Al ₂ O ₃ 0~10%.

When a P ₂ O ₅ —SnO-based glass is used, B
_Since it does not contain ₂ O ₃ , there is no need to consider the volatilization of the boric acid component. However, in this type of glass, since the glass network is not as robust as glass containing PbO as a main component, the phosphoric acid component may be volatilized. Therefore, in this system, the water content is 100 ppm or less (preferably 50 ppm).
ppm or less). A preferred example of this type of glass is P ₂ O ₅
0%, SnO 30-75%, ZnO 0-20%, L
i ₂ O 0-10%, Al ₂ O ₃ 0-10%, SiO ₂
Glass having a composition of 0 to 10% is exemplified.

In the case of P ₂ O ₅ —SnO—B ₂ O ₃ glass,
A boric acid component and a phosphoric acid component are easily volatilized because they contain a boric acid component that is easily volatilized and the glass network is fragile. In particular, when the content of P ₂ O ₅ is 5 mol% or more, more water is brought in than the phosphoric acid raw material, and the volatilization of boric acid becomes a problem. Also, when the B ₂ O ₃ content is 3 mol% or more, a large amount of boric acid is volatilized, which tends to adversely affect the electron emission portion of the display tube. Therefore, in the glass of this system, when the content of P ₂ O ₅ is 5 mol% or more, or when the content of B ₂ O ₃ is 3% or more, it is extremely important to strictly control the water content. Become. In this case, the water content is 50 ppm or less (preferably 20 pp).
m or less). Preferable examples of the glass of this type include P ₂ O ₅ 15 to 35 in mol%.
_{%, SnO 30~65%, B 2} O 3 15~25%, Z
nO 0 to 15%, Li ₂ O 0 to 10%, Al ₂ O ₃
0-10%, and a glass having a composition of SiO ₂ 0 to 5%.

[0014] Note that the glass powder used in the present invention is not limited to the above composition system, for example, Ag ₂
The O-AgI-B ₂ O ₃ based glass or the like can be used.

Next, a method for reducing the water content in the sealing material will be described.

Most of the water contained in the sealing material comes from glass powder. Therefore, the moisture content can be reduced by decreasing the moisture content of the glass. As a method, a glass raw material having a low moisture content is selected, such as using boric anhydride with little adsorbed water as a boric acid raw material, or using a phosphoric acid compound instead of orthophosphoric acid as a phosphoric acid raw material. To remove water from the glass raw material by a method such as drying, bubbling with oxygen or an inert gas at the time of glass melting, and performing glass melting in a vacuum. Can be obtained.

The most effective method among these methods is a method of bubbling with oxygen or an inert gas at the time of melting glass. Bubbling at the time of melting is widely applied in large kilns of several tons or more per month to prevent segregation of glass raw materials.However, the present invention aims to remove water to a very small amount. , And can be applied from small-scale production in which melting is performed in a crucible of about 500 ml. Note that oxygen bubbling is performed in P ₂ O ₅ where glass raw materials are easily oxidized.
The -SnO-based glass and _{P 2 O 5 -SnO-B 2} O 3 based glass or the like can not be applied. In such a case, an inert gas such as a nitrogen gas may be used instead of the oxygen gas. It is desirable to use a gas having a purity of 99% or more and not containing water, but any gas used for general industry can sufficiently obtain the effect.

In the present invention, the moisture content of the sealing material can be measured by a simultaneous thermogravimetric / mass spectrometric method (TG-MS method). This analysis method is a method in which a mass spectrometer is directly connected to a thermogravimetric analyzer, and a change in the weight of a measurement sample during heating and a change in the concentration of gas generated from the sample are tracked as a function of temperature while measuring. This method is excellent in temperature control, can analyze the generated moisture and the like in a wide temperature range, and can obtain data according to the firing conditions of the sealing material. Therefore, it is suitable for accurate measurement of trace moisture according to the actual industrial production level. The moisture in the glass can be measured by infrared absorbance, but this method has a disadvantage that accurate comparison of the amount of moisture cannot be made if the composition is different.

The moisture content of the low melting point sealing material was determined by TG-M
In the measurement by the S method, helium is used as a carrier gas, for example, the temperature is increased from room temperature to 500 ° C., and the temperature is maintained at a constant temperature of 500 ° C. for 1 hour. The moisture generated during this heating process is measured, and the moisture content can be determined from the total amount. This is because, when held at 500 ° C. for 1 hour, normally generated gas completely disappears, and it is considered that all the moisture in the material is released. Note that the heating schedule may be appropriately changed according to the material. FIG. 1 shows a moisture generation rate curve (schematic diagram) obtained by this method. In the case of a sealing material using crystalline glass, it is preferable to measure the water content at or below the temperature at which crystals precipitate. Most realistically, it is desirable to perform the measurement under conditions that match the actual temperature conditions at which the sealing is performed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

Example 1 Table 1 shows that P2O5-SnO-
Examples of the present invention (sample Nos. 1 to 3) and a conventional example (sample No. 1) using a glass powder composed of B2O3-based glass.
4).

[0022]

[Table 1]

Each sample was prepared as follows. First, the raw materials were prepared so as to have the composition shown in the table, and then 850 ° C in air.
For 1-2 hours. Sample No. For Nos. 1 to 3, a pipe was inserted into the molten glass during melting, and bubbling with nitrogen was performed. Next, the molten glass was formed into a thin plate by passing it between water-cooled rollers, pulverized by a ball mill, and then passed through a sieve having an opening of 105 μm to obtain a glass powder having an average particle size of about 10 μm. Further, a sample was prepared by mixing both at a ratio of 77% by volume of glass powder and 23% by volume of tin oxide powder.

With respect to this sample, the glass transition point, the coefficient of thermal expansion, the fluidity, and the water content by the TG-MS method were evaluated.

Next, a phosphor, a lead wire, a grid, a filament, an anode electrode, etc. were mounted inside, and a glass substrate having an insulating layer and a windshield were sealed with a sample to produce a fluorescent display tube.

Subsequently, in order to compare the influence of moisture in the material on the characteristics of the fluorescent display tube, the fluorescent display tube was actually turned on and its luminance was evaluated. Note that the luminance was
o. It was expressed as a relative value when 1 was taken as 100.

As a result, in the embodiment of the present invention, No. 1
Each of the samples Nos. 1 to 3 has a glass transition point of 331 to 335 ° C.,
The coefficient of thermal expansion at 0 to 250 ° C. is 70 to 73 × 10 ^−7.
/ ° C, and the fluidity was excellent, with a fluid diameter of 23.3 to 24.1 mm. In addition, for sample No. Three
Sample No. 2 having a water content of 48 ppm and a brightness of 75 for 30 minutes. Sample No. 2 which was bubbled for 2 hours at a luminance of 89 at 25 ppm for 2 hours. 1 is 4 ppm and brightness is 10
0, indicating a clear correlation between the moisture content in the sealing material and the brightness of the display tube. That is, the luminance of the display tube increased as the water content decreased. This is because the volatilization of the boric acid component decreases with the decrease in the water content as described above,
This is because the influence on the electron emission portion of the display tube has been reduced.

On the other hand, in the conventional example (sample No. 4) manufactured for comparison, the glass transition point, the coefficient of thermal expansion, and the fluidity were the same as those of No. 4. The samples had characteristics equivalent to those of the samples Nos. 1 to 3, but had a water content of 137 ppm and a luminance of 7 which was extremely poor. This is because the glass network structure is weak,
Moreover, since the glass powder containing a large amount of B ₂ O ₃ is used, the effect of moisture on luminance is very large.

The glass transition point is determined by differential thermal analysis (DTA).
And the coefficient of thermal expansion was determined by a push rod type thermal expansion measuring device. The fluidity was evaluated as follows. First, a sample powder having a weight corresponding to the density of the material is applied to a mold having an outer diameter of 20 mm.
mm. Next, the button was placed on a window glass, heated to a firing temperature shown in the table at a rate of 10 ° C./min, held for 10 minutes, and measured for the diameter of the button. The moisture content was measured by the TG-MS method by using helium as a carrier gas, increasing the temperature from room temperature to 500 ° C., and maintaining the temperature at a constant temperature of 500 ° C. for 1 hour. In addition, the pulverized material of the button flow test fired body used for the fluidity evaluation was used as the sample.

(Example 2) Table 2 shows an example (sample No. 5) and a conventional example (sample No. 6) of the present invention using a glass powder composed of P2O5-SnO-based glass.

[0031]

[Table 2]

Each sample was prepared as follows. First, the raw materials were prepared to have the composition shown in the table,
For 1-2 hours. Sample No. For No. 5, a pipe was inserted into the molten glass during the melting, and bubbling with nitrogen was performed. Next, a glass powder was obtained in the same manner as in Example 1. Further, both were mixed at a ratio of 75 vol% of glass powder and 25 vol% of cordierite powder to prepare a sample.

With respect to this sample, the glass transition point, the coefficient of thermal expansion, the fluidity, and the water content were evaluated in the same manner as in Example 1. A fluorescent display tube was produced in the same manner, and the luminance was evaluated. Note that the luminance was measured for Sample No. It was expressed as a relative value when 1 was taken as 100.

As a result, in the embodiment of the present invention, No. 5
The sample No. had a glass transition point of 295 ° C., a coefficient of thermal expansion at 30 to 250 ° C. of 78 × 10 ⁻⁷ / ° C., and a flow diameter of 24.5 mm, which was excellent in flowability. The water content was as low as 33 ppm, and the luminance was as high as 111.

On the other hand, in the conventional example (sample No. 6) prepared for comparison, the glass transition point, the coefficient of thermal expansion, and the fluidity were the same. The sample had the same characteristics as the sample No. 5.
However, a water content of 124 ppm and a brightness of 44
Although it was not as remarkable as a material using a P2O5-SnO-B2O3-based glass, the effect of moisture on luminance was large.

Example 3 Table 3 shows Examples (Sample No. 7) and Conventional Examples (Sample No. 8) of the present invention using a glass powder composed of PbO—B ₂ O ₃ glass. I have.

[0037]

[Table 3]

Each sample was prepared as follows. First, the raw materials were prepared so as to have the composition shown in the table, and then 950 ° C in air.
For 1-2 hours. Sample No. For No. 7, bubbling with oxygen was performed by inserting a pipe into the molten glass during melting. Next, a glass powder was obtained in the same manner as in Example 1. Further, both were mixed at a ratio of 75% by volume of glass powder and 25% by volume of lead titanate powder to prepare a sample.

This sample was evaluated for glass transition point, thermal expansion coefficient, fluidity, and water content in the same manner as in Example 1. A fluorescent display tube was produced in the same manner, and the luminance was evaluated. Note that the luminance was measured for Sample No. It was expressed as a relative value when 1 was taken as 100.

As a result, in the embodiment of the present invention, No. 7
The sample had a glass transition point of 306 ° C., a coefficient of thermal expansion at 30 to 250 ° C. of 72 × 10 ⁻⁷ / ° C., and a flow diameter of 22.0 mm, which was excellent in flowability. Further, the water content was as low as 44 ppm and the luminance was as high as 107.

On the other hand, in the conventional example (sample No. 8) prepared for comparison, the glass transition point, the coefficient of thermal expansion, and the fluidity were the same. 7 had characteristics equivalent to those of the sample.
However, with a moisture content of 121 ppm and a luminance of 67
And P2O5-SnO-B2O3-based glass or P2O
Although not as good as the material using 5-SnO-based glass,
The effect of moisture on luminance was observed.

Example 4 Table 4 shows examples (Examples 9 to 1) of the present invention using glass powders having various compositions.
2).

[0043]

[Table 4]

Each sample was prepared as follows. First, the raw materials are prepared so as to have the composition shown in the table.
Melted at 900 ° C for 1-2 hours. At this time, a pipe was inserted into the molten glass during melting to perform bubbling with oxygen or nitrogen. Next, a glass powder was obtained in the same manner as in Example 1. Further, both were mixed at a ratio of 75 vol% of glass powder and 25 vol% of cordierite powder to prepare a sample.

With respect to this sample, the glass transition point, the coefficient of thermal expansion, the fluidity, and the water content were evaluated in the same manner as in Example 1. A fluorescent display tube was produced in the same manner, and the luminance was evaluated. Note that the luminance was measured for Sample No. It was expressed as a relative value when 1 was taken as 100.

As a result, the glass transition point was 230-360.
° C, thermal expansion coefficient at 30-250 ° C is 69-80 ×
10 ⁻⁷ / ° C., and the flow diameter was 21.9 to 26.0 mm. The water content was as low as 4 to 9 ppm, and the luminance was as high as 95 to 107.

[0047]

As described above, since the sealing material for a display tube of the present invention hardly volatilizes a boric acid component or a phosphoric acid component during firing, bubbles are generated from the material, and electron emission of the display tube is caused. No adverse effects on parts. Therefore, it is suitable as a sealing material for a display tube such as a cathode ray tube, a plasma display, a fluorescent display tube, a field emission display, and an aurora vision.

[Brief description of the drawings]

FIG. 1 is a graph showing a generation rate curve of water measured by a TG-MS method.

[Explanation of symbols]

 1 Temperature schedule 2 Moisture generation rate curve

Continued on the front page F-term (reference) 4G062 AA08 AA09 AA15 BB04 BB09 CC10 DA01 DA02 DA03 DB01 DB02 DB03 DC03 DC04 DD04 DD05 DE01 DE02 DE03 DE04 DF06 DF07 EA01 EA02 EA03 EA10 EB01 EC01 ED01 EE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FE01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH04 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM10 PP12 MM10 PP12 MM10 PP10

Claims (4)

[Claims] 1. A sealing material for a display tube containing glass powder, wherein the sealing material for a display tube has a water content of 100 ppm or less. 2. The method according to claim 1, wherein the glass powder is B ₂ O ₃ and / or P ₂ O _5.
The sealing material for a display tube according to claim 1, wherein the sealing material is made of glass containing: 3. The glass powder is PbO—B ₂ O ₃ based glass, P ₂ O ₅ —SnO based glass, or P ₂ O ₅ —SnO—B.
_{3. The method according} to claim 1, wherein the glass is made of ₂ O ₃ glass.
Sealing material for display tubes. 4. The sealing material for a display tube according to claim 1, which is used for sealing a cathode ray tube, a plasma display, a fluorescent display tube, or a field emission display.