JPH09227154A - Sealing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sealing composition containing a specific phosphoric acid-tin oxide glass powder having low melting point and a low-expansion ceramics filler, free from lead and useful for improving the hydrostatic strength and thermal strength of a cathode-ray tube, plasma display panel and fluorescent display tube. SOLUTION: A sealing composition having a thermal expansion coefficient of 80×10<-7> to 110×10<-7> / deg.C between room temperature and 300 deg.C after baking is produced by compounding 50-99wt.% of a phosphoric acid-tin oxide low- melting glass powder composed of 50-72mol% (in terms of SnO) of a tin oxide, 0-10mol% of ZnO and 25-40mol% of P2 O5 with 1-50wt.% of a low-expansion ceramics filler having an average thermal expansion coefficient of 70 to 10<-7> / deg.C between room temperature and 300 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sealing composition and a plasma display panel (PDP) or a fluorescent display tube (VFD) for sealing a funnel with a cathode ray tube panel which can be sealed by heat treatment at a low temperature. The present invention relates to a sealing composition for sealing.

[0002]

2. Description of the Related Art Conventionally, a panel and a funnel of a color cathode ray tube are made of a PbO-B ₂ O ₃ -ZnO-SiO ₂ -based crystalline low melting point glass of the type disclosed in Japanese Patent Publication No. 36-17821, 440-450. 30-40 at a temperature of ℃
It was held for about a minute and sealed. The thus sealed panel and funnel are exhausted while being heated to 300 to 380 ° C. in order to obtain a high vacuum of 10 ⁻⁶ Torr or more inside.

[0003] Conventionally, a glass substrate of PDP or VFD is sealed with a low melting point glass, and 440-400 is used.
It was sealed at 500 ° C. In the case of a PDP, the sealed panel is heated to 250 to 380 ° C. and evacuated, and neon and He are heated to 100 to 500 Torr.
A discharge gas such as -Xe is filled, and in the case of VFD, it is heated to 250 to 380 [deg.] C. to obtain a vacuum, and then exhausted and sealed.

Conventionally, glass containing a lead component has been used as the powder glass for sealing, but recently, a glass containing no lead component is required.

Further, the conventional powder glass for sealing does not have a coefficient of thermal expansion matching that of the glass substrate, and the panel is cracked, or the solder is fluidized, foamed, or sealed on the glass substrate due to heating during exhaust. The wearing part was cracked.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a glass-ceramic composition for encapsulating cathode ray tubes, PDPs and VFDs, which uses glass powder containing no lead component.

[0007]

The present invention is a composition comprising 50 to 99% by weight of a phosphoric acid-tin oxide low melting point glass powder and 1 to 50% by weight of a low expansion ceramic filler. The composition of the powder is substantially in mol,
Tin oxide converted to SnO: 50 to 72%, ZnO:
There is provided a sealing composition comprising 0 to 10% and P ₂ O ₅ : 25 to 40%.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The composition range of the phosphoric acid-tin oxide low melting point glass in the present invention will be described below. In the present invention, a relatively low temperature of 400 to 500
The crystalline low-melting point glass has the following composition range in terms of mol% so that it can be sufficiently flowed and sealed at a temperature of a short period (6 minutes to 1 hour).

Tin oxide converted to SnO: 50 to 72%, ZnO: 0 to 10%, P ₂ O _5: 25 to 40%.

The content of tin oxide converted to SnO is 5
If it is less than 0 mol%, the softening point becomes too high, the fluidity is poor, and the strength and airtightness of the sealed portion are impaired, and the softening point is 400 to 50
It cannot be sealed at 0 ° C. If its content exceeds 72 mol%, vitrification becomes difficult. In the above range, SnO is particularly preferably 52 to 70 mol%.

Although ZnO is not an essential component, its inclusion can reduce the coefficient of thermal expansion of the sealing composition after firing and can match the coefficient of thermal expansion of the object to be sealed.
However, if the content exceeds 10 mol%, the softening point becomes too high and sealing cannot be performed at 400 to 500 ° C. ZnO is particularly preferably 0 to 8 mol% in the above range.

When the content of P ₂ O ₅ is less than 25 mol%, vitrification becomes difficult, and when it exceeds 40 mol%, the water resistance of the sealing material is lowered. It is preferred P ₂ O ₅ is in the above range, in particular 27 to 38 mol%.

The low expansion ceramic filler referred to in the present invention means a ceramic filler having an average coefficient of thermal expansion of 70 × 10 ^-7 / ° C. or less from room temperature to 300 ° C.

As the low expansion ceramics filler, at least one selected from zircon, cordierite, aluminum titanate, alumina, mullite, silica, β-eucryptite, β-spodumene and β-quartz solid solution is particularly preferable. In order to improve the sealing strength, cordierite and zircon are desirable.

In the present invention, the content of the low-melting glass powder is in the range of 50 to 99% by weight with respect to the total amount of the low-melting glass powder and the low-expansion ceramic filler, and the content of the low-expansion ceramic filler is low. 1 to 50 relative to the total amount of the melting point glass powder and the low expansion ceramics filler
% By weight. If the low melting point glass powder exceeds 99% by weight, the amount of the low expansion ceramic filler is small,
The coefficient of thermal expansion after firing becomes too large, the average coefficient of thermal expansion does not match the object to be sealed, and it is easily cracked. When the content is less than 50% by weight, the glass content is small and the fluidity is deteriorated, and the airtightness of the sealed portion is impaired. The content of the low-melting glass powder with respect to the total amount of the low-melting glass powder and the low-expansion ceramics filler is preferably 55 to 99% by weight,
The content of the ceramic filler is particularly preferably 60 to 99% by weight, preferably 1 to 45% by weight, particularly preferably 1 to 40% by weight.

The coefficient of thermal expansion of the thus obtained sealing composition at room temperature to 250 ° C. after firing is 60 × 10 ^{−7 to} 110 ×.
It is preferably 10 ⁻⁷ / ° C. If the coefficient of thermal expansion deviates from this range, it becomes difficult to match the coefficient of thermal expansion of the object to be sealed.

When the sealing composition of the present invention is applied to seal a cathode ray tube panel and a funnel,
Consists of phosphoric acid-tin oxide low melting glass powder 60 to 99% by weight and low expansion ceramics filler 1 to 40% by weight, and has a thermal expansion coefficient of 80 × 1 at room temperature to 300 ° C. after firing.
It is preferably 0 ^{−7 to} 110 × 10 ⁻⁷ / ° C.

Such a sealing composition has a temperature of 400 ° C to 500 ° C.
By holding at a temperature of ℃ for 5 minutes to 1 hour, the panel of the cathode ray tube and the funnel can be sealed, and after the sealing,
Heating at the time of evacuation to 380 ° C. does not cause fluidization, foaming, or loss of mechanical strength.

When the sealing composition of the present invention is applied to seal a panel of a cathode ray tube and a funnel, when the content of the low melting point glass powder exceeds 99% by weight, the amount of the low expansion ceramic filler is small. For this reason, the coefficient of thermal expansion becomes too large, the average coefficient of thermal expansion does not match that of the panel and the funnel, and the panel is easily cracked. When the content is less than 60% by weight, the glass content is small and the fluidity is deteriorated, and it is difficult to obtain a sufficient vacuum for a cathode ray tube. In this case, the content of the low-melting glass powder with respect to the total amount of the low-melting glass powder and the low expansion ceramics filler is more preferably 65 to 99% by weight, particularly preferably 70 to 99% by weight,
The content of the ceramics filler is more preferably 1 to
35% by weight, particularly preferably 1 to 30% by weight.

The average thermal expansion coefficient of the sealing composition after firing at room temperature to 300 ° C. is 80 × 10 ^{−7 to} 110 ×.
When the temperature is out of the range of 10 ⁻⁷ / ° C., tensile stress acts on the panel glass or funnel glass or the sealed portion after sealing,
The pressure resistance of the valve decreases.

When the sealing composition of the present invention is applied to PDP sealing or VFD sealing, the phosphoric acid-tin oxide low melting glass powder is 50 to 98% by weight and the low expansion ceramics filler is 2 to 50% by weight. It is preferable that the thermal expansion coefficient at room temperature to 250 ° C. after firing is 60 to 90 × 10 ⁻⁷ / ° C.

The composition for sealing is 400 to 500 ° C.
The glass substrate for PDP or VFD can be sealed by holding at the temperature of 5 minutes to 1 hour.
When exhausted at 80 ° C., it does not flow, foam, or lose mechanical strength due to heating.

In the case of applying the sealing composition of the present invention to PDP sealing or VFD sealing, if the content of the crystalline low melting point glass powder exceeds 98% by weight, the amount of the low melting point filler is small, so that after firing, The coefficient of thermal expansion becomes too large and the coefficient of thermal expansion does not match that of the substrate glass, and tensile stress remains in the seal frit portion after sealing and cracks easily. If it is less than 50% by weight, the glass content is small and the fluidity becomes poor, so that PDP and V
As an FD, sufficient airtightness of the sealed portion cannot be obtained. In this case, the content of the low-melting glass powder with respect to the total amount of the low-melting glass powder and the low-expansion ceramics filler is more preferably 55 to 98% by weight, particularly preferably 60 to 98% by weight, and the content of the ceramics filler. Is more preferably 2 to 45% by weight, particularly preferably 2 to 40% by weight.

The average thermal expansion coefficient of the sealing composition after firing at room temperature to 250 ° C. is 60 to 90 × 10 ⁻⁷ / ° C.
If the value is out of the range, tensile stress acts on the substrate glass or the sealing portion after sealing, and the compressive strength decreases.

In the present invention, the low-expansion ceramics filler is desirably a total weight of alumina and zircon of 9% or less based on the weight of the sealing composition in terms of weight. Alumina has a coefficient of thermal expansion of 65 × 10 ⁻⁷ to 75 × 10 ⁻⁷ / ° C.
(50 to 350 ° C), zircon has a thermal expansion coefficient of 42 x 1
0 ^-7 48 a ^{× 10 -7 / ℃ (50~350 ℃} ), thermal expansion coefficient is relatively large, the effect of adjusting the thermal expansion coefficient be mixed with glass is smaller than other low-expansion filler This is because. When the content of the low-expansion ceramics filler is within the above-mentioned preferred range, a desired coefficient of thermal expansion can be obtained without significantly reducing the amount of the glass component, which is effective in improving the compressive strength.

For reference, other thermal expansion coefficients (50 to 350)
(° C, unit: × 10 ^-7 / ° C) is as shown below.

Cordierite 10 to 20, aluminum titanate 10 to 20, mullite 50 to 60, silica 5 to 6, β-eucryptite -60 to -80, β-spodumene 8 to 15, β-quartz solid solution -10. +10.

From the above viewpoint, it is more preferable that the total amount of the low expansion ceramic filler other than alumina and zircon is 16% by weight or more based on the amount of the composition for sealing. In addition, a pigment may be added to the composition for coloring.

[0029]

EXAMPLE A raw material slurry obtained by dropping 85% orthophosphoric acid into a solid raw material excluding the P ₂ O ₅ component of the glass component was well mixed and then dried at 120 ° C. to obtain a powder batch. It was created. This raw material was put into a quartz crucible, covered with a lid, melted at 1000 to 1100 ° C., and then granulated or passed through a roller to give a glass in the form of flakes. Then, this was pulverized with a ball mill for a predetermined time to produce a low melting point glass powder having a composition shown in the glass composition column of Table 1.

These low-melting glass powders and low-expansion ceramics fillers were mixed in a weight ratio shown in the constitutional column of Table 1 to prepare a sealing composition. Examples 1 to 8 are Examples and Example 9
11 are comparative examples. Further, Examples 1 to 5 and Example 9 are prepared for cathode ray tubes, Examples 6, 7, and 10 are prepared for PDP, and Examples 8 and 11 are prepared for VFD.

The results of measuring the flow button diameter, adhesive residual strain, and average thermal expansion coefficient of this sealing composition are shown in Table 1.
Shown in Each measuring method is as follows.

Flow button diameter: It shows the fluidity of the composition at the time of sealing, and is 5.5 g for the sample powder cathode ray tube of the sealing composition, 3.5 g for PDP and VFD, and the diameter is 12.
It is the diameter (unit: mm) through which the sealing composition flows when it is held at the firing temperature (unit: ° C) described in Table 1 for 30 minutes after being pressure-molded into a 7 mm columnar shape. The diameter of this flow button is 26.5 mm or more for CRT and 2 for PDP.
0 mm or more, and for VFD, 20 mm or more is desirable.

Adhesive residual strain: The sealing composition and the vehicle (solution of 1.2% nitrocellulose dissolved in isoamyl acetate) were mixed at a weight ratio of 6.5: 1 to form a paste. This paste is applied on a funnel glass piece for a cathode ray tube and on a substrate glass piece for a PDP and VFD, and after firing under the same conditions as in the case of a flow button diameter, a glass piece and a sealing composition after firing are applied. The residual strain (unit: nm / cm) generated during the measurement was measured using a polarimeter. "+" Indicates that the sealing composition is under compression strain, and "-" indicates that the sealing composition after firing is under tensile strain. This residual strain is desirably in the range of -100 to +500 nm / cm.

Average coefficient of thermal expansion: The composition for sealing was baked under the same conditions as in the case of the flow button diameter, and then ground to a predetermined size,
The amount of elongation is measured by a thermal expansion measuring device at a temperature rising rate of 10 ° C./min, and an average coefficient of thermal expansion at room temperature to 300 ° C. (for cathode ray tube) or room temperature to 250 ° C. (for PDP or VFD) (unit: × 10 ⁻⁷ / ° C.) was calculated. In the use of cathode ray tube glass, the average coefficient of thermal expansion is 80 to 110 × 10 considering the matching of coefficients of thermal expansion.
The range of ^-7 ℃ ^-1 is desirable. Substrate glass for PDP, VFD
Considering the matching of the coefficient of thermal expansion, the average coefficient of thermal expansion is 60 to 90 × 10 ^{−7 in the} application of glass for substrates.
The range of ^-1 is desirable.

Further, the strengths of cathode ray tubes, PDPs, and VFDs sealed with these sealing compositions were measured.

For a cathode ray tube, a sealing composition is interposed between a 25-type funnel and a panel, and the composition is 400-5.
The valve was manufactured by keeping the funnel and the panel sealed at 00 ° C for 30 minutes, and the water pressure resistance and heat resistance of the valve were measured.

With respect to the PDP, the sealing composition was preliminarily placed at the end of the substrate of the PDP, and
A panel was manufactured by holding at ~ 500 ° C for 30 minutes and sealing.

Further, in the case of VFD, a grid is placed between the end portions of the glass substrate on which the electrodes and the like are formed to interpose 4
A panel was manufactured by holding the glass substrate at 00 to 500 ° C. for 30 minutes to seal the glass substrates together.

Table 1 shows the results of measuring the water pressure resistance and heat resistance of these panels. Each measuring method is as follows. Water pressure resistance strength: The pressure difference at the time of breaking by applying a pressure difference due to water to the inside or outside of the valve or panel was measured (unit: k
g / cm ² , 5 average value). In order to guarantee the strength as a valve or panel, this water pressure resistance strength is usually 3k.
It is preferably g / cm ² or more.

Heat resistance: The temperature difference between water and hot water was applied to the inside and outside of the valve or panel to measure the temperature difference (unit: ° C, average of 5 pieces). CRT, PD
Considering the thermal stress generated in the heat treatment process for manufacturing P and VFD, it is usually desirable that the heat resistance strength is 45 ° C. or higher.

From Table 1, it can be seen that the sealing composition according to the present invention has the properties superior to those of the conventional products. In Examples 1 and 2, since the total amount of zircon and alumina having a relatively large coefficient of thermal expansion is small, the water pressure resistance strength is higher than that in Example 3. Also,
In Example 6 as well, since the total amount of zircon and alumina having a relatively large thermal expansion coefficient is small, the water pressure resistance strength is higher than that in Example 7.

[0042]

[Table 1]

[0043]

EFFECTS OF THE INVENTION According to the present invention, a sealing composition containing no lead and suitable for sealing cathode ray tubes, PDPs, VFDs and the like can be obtained. Braun tubes, PDPs and VFDs sealed with the sealing composition of the present invention are particularly excellent in water pressure resistance and heat resistance.

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Claims (5)

[Claims] 1. A phosphoric acid-tin oxide-based low-melting glass powder 5
0 to 99% by weight and low expansion ceramic filler 1 to 50
The composition of the low-melting-point glass powder is substantially in terms of mol, and the tin oxide converted to SnO is 50 to 72%, ZnO is 0 to 10%, and P ₂ O _{5 is} 25 to 40%. A composition for sealing, which comprises: 2. The low expansion ceramics filler is one or more selected from the group consisting of zircon, cordierite, aluminum titanate, alumina, mullite, silica, β-eucryptite, β-spodumene and β-quartz solid solution. The composition for sealing according to claim 1. 3. A phosphoric acid-tin oxide-based low melting point glass powder 6
0 to 99% by weight and low expansion ceramic filler 1 to 40
%, And has a thermal expansion coefficient of 80 × 10 ^{−7 to} 110 × 10 ⁻⁷ / ° C. at room temperature to 300 ° C. after firing, for sealing a funnel panel and a cathode ray tube panel. The composition for sealing according to claim 1 or 2. 4. A phosphoric acid-tin oxide-based low melting point glass powder 5
0-98% by weight and low expansion ceramic filler 2-50
For sealing a plasma display or a fluorescent display tube, characterized by having a thermal expansion coefficient of 60 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C. at room temperature to 250 ° C. after firing. The composition for sealing according to claim 1 or 2. 5. The sealing composition according to claim 1, 2, 3 or 4, wherein the low expansion ceramics filler has a total amount of alumina and zircon of 9% or less based on the weight of the sealing composition in terms of weight.