JP2000239042A - Frit for crt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a frit for a cathode-ray tube(CRT) capable of sealing a panel and a funnel of a CRT bulb at a low temperature in a short time. SOLUTION: This frit is used for sealing a panel and a funnel of a CRT bulb and comprises an amorphous glass powder and a refractory filler powder. The amorphous glass powder has a composition of 76-90 wt.% of PbO, 8-18 wt.% of B2O3, 0-5 wt.% of ZnO, 0.1-3 wt.% of SiO2, 0.1-3 wt.% of Al2O3, 0-1 wt.% of V2O5 and 0-5 wt.% of Bi2O3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT frit, and more particularly, to a CRT frit used for sealing a panel of a color CRT valve and a funnel.

[0002]

2. Description of the Related Art Conventionally, a panel and a frame of a color CRT valve have been used.
The seal of the channel is PbO-B_Two O _Three -ZnO-Si
O_Two -BaO-based crystalline glass powder and fire resistant material such as zircon
Crystalline frit for CRT composed of crystalline filler powder
Use and keep at 440-460 ° C for 30-60 minutes
It is done by.

[0003] The crystalline frit used here has excellent heat resistance, and the valve is set to 350 in the evacuation process after sealing.
It is characterized in that no misalignment occurs between the panel and the funnel even when the panel is reheated to 400 ° C.

[0004]

In recent years, the evacuation technique has advanced, and it has become possible to perform evacuation by heating at a low temperature. For this reason, the heat resistance to the CRT frit is no longer required. Instead, from the viewpoint of energy cost reduction and productivity improvement, lower temperature and
It is becoming increasingly important to be able to seal a valve in a short time. However, with conventional frit,
In order to obtain the desired characteristics, high temperature as described above, and
Long firing is required, and cannot meet such a demand.

[0005] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a CRT frit capable of sealing a panel and a funnel of a CRT valve at a low temperature in a short time.

[0006]

The present inventors Means for Solving the Problems] Where various experiments, a specific composition range PbO-B ₂ O ₃ -Z
It found that the object can be achieved by using an amorphous glass nO-SiO ₂ -Al ₂ O ₃ system,
It is proposed as the present invention.

That is, the frit for CRT of the present invention has a CR
C used for sealing T-valve panel and funnel
A RT frit consists amorphous glass powder and the refractory filler powder, PbO 76-90% amorphous glass powder in weight _{percent, B 2 O 3 8~18%,} Zn
O 0-5%, SiO ₂ 0.1-3%, Al ₂ O ₃ .
_{1~3%, V 2 O 5 0~1} %, and having a composition of Bi ₂ O ₃ 0~5%.

[0008]

The frit for a CRT according to the present invention is hardly devitrified due to the high stability of glass, and exhibits good fluidity.
Further, since the glass transition point and the softening point are low, the valve can be sealed at a low temperature in a short time.

The reason for limiting the glass composition to the above range in the present invention will be described below.

PbO is a component that forms the skeleton of glass, and its content is 76 to 90%, preferably 79 to 87%.
%. If the content of PbO is more than 90%, the thermal expansion coefficient becomes too large, and if it is less than 76%, the fluidity of the glass decreases and the firing temperature becomes too high.

B ₂ O ₃ is also a component forming the skeleton of glass, and its content is 8 to 18%, preferably 10 to 15%.
%. If B ₂ O ₃ is more than 18%, the chemical durability is lowered, which is not preferable for practical use. If B ₂ O ₃ is less than 8%, the fluidity of the glass is deteriorated.

[0012] ZnO has an effect of suppressing devitrification of glass by adding a certain amount, and its content is 0 to 5%, preferably 1 to 4%. If ZnO exceeds this range, the glass tends to be devitrified.

[0013] SiO ₂ has the effect of stabilizing the glass of this system, and its content is 0.1 to 3%, preferably 0.2 to 2.5%. If the content of SiO ₂ is more than 3%, the softening point becomes high, and the firing temperature becomes too high. Also 0.
If it is less than 1%, the glass becomes unstable and devitrifies.

Al ₂ O ₃ also has an effect of stabilizing the glass of this system, and its content is 0.1 to 3%, preferably 0.2 to 2.5%. If the content of Al ₂ O ₃ is more than 3%, the softening point becomes high, and the firing temperature becomes too high. If the content is less than 0.1%, the glass becomes unstable and devitrifies.

V ₂ O ₅ has an effect of lowering the softening point of the glass of this system, and its content is 0 to 1%, preferably 0 to 0.8%. If V ₂ O ₅ is more than 1%, devitrification tends to occur.

Bi ₂ O ₃ is also a component which lowers the softening point of the glass of this system, and its content is 0 to 5%, preferably 0 to 4%. If Bi ₂ O ₃ is more than 5%, devitrification tends to occur.

Although V ₂ O ₅ and Bi ₂ O ₃ are not necessarily essential components, glass stabilizing components such as SiO ₂ and A ₂
If the addition of l ₂ O ₃ raises the softening point too much,
It is desirable to add for adjusting the softening point.

The amorphous glass used in the present invention may contain other components as long as the glass does not become unstable. For example, TiO ₂ can be added up to 5% in order to prevent elution of the PbO component. When the glass is unstable and easily devitrified, Fe ₂ O ₃ or Cu
It is possible to stabilize the glass by adding O. The addition amount of these components is 5% or less (preferably 2% or less) for Fe ₂ O _{3 and} 3% or less (preferably 1% or less) for CuO.

The glass having the above composition has a glass transition point of about 290 to 310 ° C. and a softening point of 330 to 370 ° C.
And the fluidity is good because it is non-crystalline.

As the refractory filler powder in the present invention, alumina (Al ₂ O ₃ ) or zircon (ZrSiO
₄₎ is optimal, Other than this cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2), lead titanate (PbTiO _3), quartz glass (a-SiO _2), willemite (2ZnO · SiO ₂ ), Tin oxide (SnO ₂ )
And the like can be used, and these may be used alone or in combination.

In the present invention, the ratio of the amorphous glass powder to the refractory filler powder is 95: 5 to 7 by weight.
0:30, preferably 91: 9 to 75:25. The reason for limiting the ratio of the glass powder and the refractory filler powder in this way is as follows. If the glass powder content is less than the above range, the fluidity of the frit becomes insufficient, so that a good seal shape cannot be obtained or a dense seal layer cannot be formed. On the other hand, if the amount of the refractory filler powder is less than the above range, the coefficient of thermal expansion of the frit will not be suitable for the valve, or the mechanical strength will be insufficient.

Further, in the frit for a CRT of the present invention, 3
The coefficient of thermal expansion at 0 to 250 ° C. is 80 to 95 × 10 ^−7.
/ ° C is desirable. When the coefficient of thermal expansion of the frit is within this range, a moderate amount of strain (450 to 1000 psi) is generated in the CRT valve, and high sealing strength can be obtained. However, if it is out of this range, abnormal distortion occurs and the frit seal portion, panel, and funnel portion are easily damaged.

Since the frit for a CRT of the present invention having the above-mentioned structure is amorphous, it is not necessary to consider the crystallization characteristics at the time of firing, and the sealing conditions of the CRT valve can be freely selected to some extent. Specifically, the firing temperature is 4
The holding time can be appropriately selected within the range of 10 to 430 ° C and the holding time of 5 to 20 minutes. Note that particularly preferable firing conditions are 4
20 ° C. for 10 minutes.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The frit for a CRT according to the present invention will be described below based on embodiments.

Tables 1 and 2 show the amorphous glass powders (samples A to G) used in the present invention. Sample H in the table
Is a reference example and shows a glass used for a conventional crystalline frit.

[0026]

[Table 1]

[0027]

[Table 2]

Each sample was prepared as follows. First, lead oxide, boric acid, zinc oxide, silicon dioxide, aluminum oxide, vanadium pentoxide, bismuth oxide, iron oxide, copper oxide, and barium carbonate were prepared so as to have the proportions shown in the table, and placed in a platinum crucible for 800. It was melted and vitrified at ８850 ° C. for 1 hour and formed into a film. This was further pulverized by a ball mill, and then classified through a 100-mesh (JIS) sieve to obtain a glass powder sample having an average particle size of 5 to 6 μm.

The sample thus obtained was subjected to differential thermal analysis (DTA) to determine its glass transition point, softening point,
And the crystal precipitation onset temperature. Here, the crystal precipitation start temperature refers to a temperature at which heat generation due to crystal precipitation from glass starts in a differential thermal analysis method. The coefficient of thermal expansion is obtained by molding the obtained glass cullet to 40 × 4 mmφ,
The coefficient of thermal expansion at 30 to 250 ° C was measured with a dilatometer.

As is clear from the table, Samples A to G used in the present invention have a glass transition point of 296 to 310 ° C., a softening point of 338 to 366 ° C., and a thermal expansion coefficient of 113 to 30 ° C. to 250 ° C. １119 × 10 ⁻⁷ / ° C. In addition, no crystal precipitation start temperature was confirmed in any of the samples.

Sample E used for a conventional frit has a transition point of 321 ° C. and a softening point of 398 ° C.
The coefficient of thermal expansion at 0 to 250 ° C. is 106 × 10 ⁻⁷ / ° C.
Met. In addition, the crystal precipitation start temperature was 430 ° C.

Tables 3 and 4 show Examples (Sample No. 1) of the present invention prepared by mixing Samples A to G with refractory filler powder.
1 to 8). In addition, the sample No. of Table 4 9 and 1
Reference numeral 0 is a reference example, and shows a conventional crystalline frit prepared by mixing sample H and zircon powder. In the refractory filler powder, zircon used a 150 mesh pass product and alumina used a 200 mesh pass product.

[0033]

[Table 3]

[0034]

[Table 4]

Next, various characteristics of the obtained sample were evaluated.

As is clear from the table, the No. 1 of the embodiment of the present invention. Samples 1 to 8 have a flow diameter of 22.9 to 25.
It was as large as 5 mm and had a coefficient of thermal expansion at 30 to 250 ° C. of 84 to 90 × 10 ⁻⁷ / ° C. Next, using these samples, a 29-inch color CRT valve was sealed under the firing conditions shown in the table, and the seal shape was evaluated. The seal thickness was 0.15 to 0.3 mm, which was appropriate. Had adequately covered the inner and outer surfaces of the valve, and had a good shape without insufficient flow or sagging downward. Furthermore, when the water pressure resistance test of the valve was performed, it was all 6.0 kg.
/ Cm ² or more.

On the other hand, in the reference example, the firing conditions were 440 ° C.
Sample no. Sample No. 10 exhibited almost the same characteristics as those of the example of the present invention, but was baked at 420 ° C. for 10 minutes. For No. 9, the flow diameter was 21.0 mm, and the glass did not flow sufficiently. In addition, since no crystal is precipitated, the coefficient of thermal expansion is as large as 106 × 10 ⁻⁷ / ° C., and it is considered that abnormal distortion is contained in the panel glass. Further, when the frit seal portion was observed by actually sealing the CRT valve, the frit did not sufficiently cover the panel and the funnel, and the seal shape was poor.

The flow diameter was determined by pressing a powder of an amount corresponding to the specific gravity of each sample into a button shape of 20 mmφ.
After being placed on the panel glass of T and calcined under the conditions shown in the table, the diameter was measured with a vernier caliper. The coefficient of thermal expansion was measured using a dilatometer by molding a frit fired under the conditions shown in the table to a size of 40 × 4 mmφ. For the seal shape, see 29
The inch color CRT panel and the funnel were sealed using each sample under the firing conditions shown in the table, the seal thickness was measured, and the cover condition of the panel and the funnel due to the frit and the presence or absence of frit dripping were visually observed. ,evaluated. The water pressure resistance was 29 sealed under the conditions in the table.
An inch color CRT valve was placed in a water tank, and the water pressure outside the valve was gradually increased to measure the pressure at which the valve broke. In general, it is considered that there is no practical problem if the strength is 3.5 kg / cm ² or more.

[0039]

As described above, the use of the CRT frit of the present invention makes it possible to seal the panel and the funnel of the color CRT valve by firing at a lower temperature and in a shorter time than the conventional crystalline frit. In addition, it is possible to reduce energy costs and improve productivity.

Continued on the front page F term (reference) 4G062 AA08 AA09 AA15 BB04 DA02 DA03 DB02 DB03 DC03 DC04 DD01 DE01 DE02 DE03 DF07 EA01 EA10 EB01 EC01 ED01 EE01 EF01 EG01 FA01 FA10 FB01 FC01 FD01 FE01 FF01 GA01 F01 GA01 F01 GA01 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM10 MM12 NN30 NN32 PP01 PP02 PP05 PP09 5C032 BB18

Claims (3)

[Claims] 1. A frit for a CRT used for sealing a panel of a CRT valve and a funnel, comprising an amorphous glass powder and a refractory filler powder, wherein the amorphous glass powder is PbO 76 to 90 in weight percentage. %, B ₂ O
_{3 8~18%, 0~5% ZnO,} SiO 2 0.1~3
_{%, Al 2 O 3 0.1~3%} , V 2 O 5 0~1%, Bi 2
O ₃ CRT frit, characterized in that it comprises 0-5% of the composition. 2. The frit for a CRT according to claim 1, wherein the mixing ratio of the amorphous glass powder and the refractory filler powder is 95: 5 to 70:30 by weight. 3. The thermal expansion coefficient at 30 to 250 ° C. is 8
2. The frit for a CRT according to claim 1, wherein the frit is in the range of 0 to 95 * 10 < ^-7 > /[deg.]C.