JPS5935040A - Sealing material - Google Patents

Abstract

PURPOSE:A sealing material, obtained by incorporating a low-melting lead-boric acid type glass with a filler having a low expansion coefficient and ultrafine metallic oxide particles at a specific weight ratio, suitable for sealing liquid crystal display tubes, etc., and having improved chemical and water resistance and printability. CONSTITUTION:A sealing material obtained by incorporating (A) 60-85wt% powder having about 10-20mum average particle diameter of a low-melting lead- boric acid type glass, having <=450 deg.C softening point, and obtained by using PbO as a main raw material with (B) 14-38wt% powder having about 5-15mum average particle diameter of a filler, e.g. lead titanate or zirconium silicate, having a low expansion coefficient and (C) 0.05-15wt% ultrafine particles of a metallic oxide, e.g. silicon dioxide or titanium oxide, having <=1mum average particle diameter in a mixer or a dispersing machine, and applying an ultrafine particulate metallic oxide 13 to the surface of the low-melting glass 11 and further to the surface of the filler 12 at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on a low melting point glass used for airtightly sealing the envelopes of various display devices such as fluorescent display tubes and liquid crystal display tubes, and packages of other live conductor elements. Regarding the sealing material, in particular, fine particles of metal oxide were added, and it had excellent chemical resistance and water resistance, as well as excellent printing quality. This relates to sealing materials.

The present invention can be used for sealing ITJI devices and packages in addition to various display devices made of glass or ceramics, and an embodiment of a fluorescent display tube will be described below.

As shown in FIG. 1, a conventional fluorescent display tube includes an insulating substrate 1 made of glass or ceramics, a wiring conductor 2, an insulating layer 3 provided with through holes, and a through hole 71 through which the wiring conductor 2 is passed. A control vvL pole (i and , and a filament-shaped cathode 7 is disposed further above.A front envelope 8 made of a glass plate shaped like a flat-bottom boat is polymerized with the substrate 1 and a sealing material 9 so as to cover these electrodes. A fixed envelope is constructed.The type in which the envelope is thus composed of the substrate 1 and the front envelope 8 in the shape of a flat-bottom boat is referred to as a one-piece type.

In other types of fluorescent display tubes, as shown in FIG. 2, the glass base Fi1 has a wiring conductor 2, an insulation M3 with a through hole, an anode conductor 4, as in the molded front type.
It has a configuration in which +1t)m of phosphors M5 are disposed. However, the front envelope lO is a front plate made of glass]
, Oa, and a side plate 10b, which is also made of glass, are bonded and assembled around the front plate 10a with a sealing material. They are bonded and fixed by a sealing material 9. In this way, the envelope is the substrate 1.

Previous unit 10 with front panel 10FI and side panel iob assembled
The type consisting of the above is called the assembled front type.

A sealing material mainly composed of low-melting glass is printed and coated on the sealed parts of both types of envelopes, and the various parts are polymerized and heat-treated at 400 to 500°C to form a bonded seal. I was wearing it.

In addition to the main component of low-melting glass, conventional sealing materials include
The substances shown in Table 1 are added as C-color in powder form. The reason for adding this filler is that the coefficient of thermal expansion of the main component, low melting point glass, is a relatively large value of 100 to 115 x 7 107°C, so the coefficient of thermal expansion is 05 to 05 x 10/'C. When the envelope of a k-optical display tube consisting of a glass plate is sealed with a sealing material whose main component is low melting point glass, the sealed part has a thermal expansion of nI.
They had the disadvantage that they could break or crack due to thermal stress caused by the difference in coefficient of stress. In order to eliminate this drawback, a sealing material with a small coefficient of thermal expansion was obtained by dispersing in the form of particles a substance having a coefficient of thermal expansion smaller than that of the low-melting glass in the low-melting glass as the main component.

The names and thermal expansion coefficients of the materials used as the filler are shown in Table 1.

Table 1 The main raw material for low-melting glass is pbo, as well as 11, 03 and 7. It is a boric acid-based glass with the addition of ++(l), and the conventional formulation of -· is as follows.

11bO---=-1'7~+13W 7%+3,0!
......7~11n 7,n O...7~12n S,i(1,--1-3n The 11b O component, which is the main raw material among the above components, is chemically slightly It is unstable and tends to bond with solvents etc.
Also, II, ``(1) has the property of absorbing moisture from the air, and conventional low melting point glass has the disadvantage of adsorbing moisture in the atmosphere and deteriorating with water and acid phase. In addition, the substances mentioned above as fillers are effective in reducing the coefficient of thermal expansion, but they are not effective in reducing the coefficient of thermal expansion. It reacts with low melting point glass and changes its quality, and even during the heat treatment during sealing, the water becomes difficult to evaporate and remains in the form of bubbles in the sealing material layer of the fluorescent display tube.This phenomenon occurs. After forming on the fluorescent display tube, moisture and gas are generated inside the display tube, causing problems such as lowering the brightness of the fluorescent display tube and shortening its lifespan.

In addition, as a method of applying the sealing material, it is generally applied around the substrate 1 by a screen printing method, in which low melting point glass, filler, ethyl cellulose, terpineol mw1. Mix in a vehicle dissolved in water to form a paste. To print this paste 1~, if you lower the viscosity of paste 1~, the printability will improve, but after printing, it will smear or run and the printing accuracy will deteriorate.6 If you increase the viscosity of the paste, the paste will come out from the screen. There was also a problem in that printability deteriorated even more.

The present invention has been made in view of the above-mentioned circumstances.The present invention has been made in view of the above-mentioned circumstances. One layer of fine particles is coated to form a Sin. The object of this invention is to provide a sealing material which inhibits the reaction with melting point glass, does not produce a paste of ultrafine particles, and has excellent printing properties due to the dixotropic effect.

Hereinafter, details will be given of one example M 1f1 showing the present invention in the drawings.
This will be explained in Section 1II.

FIG. 3 is an enlarged view of the sealing material of the present invention.

11 are particles of low melting point glass, and 12 are particles of Builer material. Ultrafine particles 13 of gold X oxide, such as silicon dioxide, are attached to the surfaces of these low melting point glass 11 and filler 12 particles. %, low melting point glass is 60-85% and low expansion coefficient filler is 14-38%.
and 0 ultrafine particles of gold R oxide with an average particle size of 1 μm or less.
．． The ratio is 0.05 to 15%.

The low melting point glass has a softening point of 450'C or less, and is a button-boric acid based low melting point glass powder made of pbo as the main raw material.

Examples of the components of the low melting point glass are as follows. Each component is expressed in weight percent.

r'bo...1...77~83% ■、0.・・・・・・7～11! ! ^1yo Ol...3~13u S, io, 1-3 u The above components were melted in a platinum crucible for tFf and then cooled.

Can you pass 150 meshes through 3Ir1 with a ball mill? Powder so that it has a diameter of J76) ~6 Therefore, the maximum particle size is about 10oI
Lm, and the average particle size is 10 to 20 μm. As mentioned above, the chemical properties of this low melting point glass include chemical resistance,
It had poor water resistance. The coefficient of thermal expansion of this low melting point glass is a relatively large value of about 100 to 115 x 10 /'C.

However, the heat flux ++q ratio of the glass plate used for the envelope of the fluorescent display tube is approximately 85 to 95 x 10-'/℃4
Therefore, if low melting point glass is used as it is, the difference in thermal expansion coefficient will be too large and the sealed portion will break or crack, making it unusable.Therefore, a filler is mixed in to reduce the thermal expansion coefficient.

``Substances that can be used as fillers are those shown in Table 1 above that have a small coefficient of thermal expansion. The particle size of these fillers is almost the same as that of the previous low melting point glass, and the average particle size is 5 to 5.
6 The substance to be mixed as a filler is ditanic acid button, which falls within the 1iPII range of 151Lwl.

From materials with low expansion coefficients such as zirconium silicate, β-spodumene, β-eucryptite, Coriley 1-1 quartz glass, or aluminum titanate;
One kind of discovered substance or a mixture of two or more kinds of substances in a predetermined ratio is used.

Is the metal oxide silicon dioxide? li (Si(1,), aluminum oxide (^17 (IJ), ditanium oxide ('I
'i0. ), etc., are formed into ultrafine tIγ particles having a particle size of 1 μm or less. As an example, the case of silicate dioxide will be explained. The raw material is silicon tetrachloride I (Si C11).1. :(7) SiC1p
It was synthesized by aggregating silicon dioxide by hydrolyzing it in 1 ml of oxyhydrogen.

2 Il, +-→2110 When silicon dioxide is synthesized by the gas phase reaction as described above, ultrafine particles with an average particle size in the range L of 10 to 20 millimicrons are formed. Sin was created in this way.

is amorphous silicon dioxide, and the specific surface area is approximately 20
The number of particles is as large as 0ir/g, and the number of particles is as large as 10'' per gram.

Furthermore, silicon dioxide has silanol groups (SiOl) on its surface.
1), water molecules gather at the silanol groups of silicon dioxide and can absorb up to about 1 ovt% of water. The moisture in this is.

Moisture can be easily released by heating silicon dioxide.

This thing J, III sucks? The temperature range of moisture content starts from around 100 degrees Celsius, and the adsorbed water is released up to about 20+1 degrees Celsius.

Furthermore, even when heated or heated, the specific surface area decreases at around 550°C ('J), but does not decrease at 550°C4.

Therefore, by coating the surface of the low melting point glass "L" with the silicon dioxide fine particles to form a protective layer before turning it off and IH, moisture is adsorbed by the silicic acid and is directly exposed to the low melting point glass. Since the adsorbed water does not come into contact with the silicon dioxide, no reaction occurs with the low-melting point glass, and it has the effect of preventing deterioration of the low-melting point glass.Also, once the adsorbed water has arrived at Jk1, it is easily released from the silicon dioxide by heating. Therefore, it remains in the sealing material layer.

In addition to the above-mentioned protective effect, silicon dioxide has the effect of adjusting the softening point, and if too large a quantity is added, the softening point of the glass will become too high, which is not preferable.

, therefore -(r) the entire surface of the low melting point glass particle with a few nails
To achieve this, it is necessary to reduce the particle size and increase the specific surface area. Therefore, the average particle size was set to 1 μm or less. Furthermore, if a large amount of fine particles is added, the bulk specific gravity of the frit will increase, and heating: 'I FA (I) will cause the volume to decrease, making it undesirable as a sealing agent. Therefore, up to 115% It is.

It is also known that ultrafine silicon dioxide particles have silanol groups (SiOll) on their surfaces. The silanol groups on this surface tend to form water cross-links and bond with each other, but since these hydrogen bonds are in a weak state, just by applying a slight external force, they are split again and the viscosity increases. A decrease occurs. When the external force is removed and the material is left to stand still, the silicon dioxide particles bond again.

This phenomenon is called the dixotropic effect and has the effect of improving printing characteristics. In other words, when printing a paste containing ultrafine particles of silicon dioxide, when it passes through the mesh of the screen, external force is applied by the squeegee, which causes the bonds to break and the viscosity to decrease, improving fluidity and allowing it to pass through the mesh of the screen. 6. However, the paste passes through the screen and the board is blind; once it is printed, it remains stationary, so hydrogen bonding occurs and the viscosity increases, so the paste must be printed accurately without dripping or flowing out. can,
The above-mentioned Dixo1-Robie effect also exists in ultrafine particles of aluminum oxide and ditanium oxide, and like silicon dioxide,
6 Example 1 Low melting point glass powder 1500g 138. OWt,
%Lead titanate 700. 31. ．． 7H
Ultrafine particles-5in, 7.4g 0.3 I
+The low melting point glass used had the following composition.

1'b0 8310;% rl, 0.　　　　　g　.

5i (L 3 n Al, Ox 5 n -1) The low melting point glass consisting of the two components is formed into a powder form, and a 150 mesh passed product is used.The average particle size is 5 to 5.
The diameter is 10 μm, and the maximum particle size is about 100 μm. The melting point is 450°C or less. This low melting point glass
Weigh 0g.

Lead titanate is used as a type of boiler.

70% of particles with an average particle size of 10μIll to the above ratio.
0 F.

weigh the scales.

Ultrafine silicon dioxide particles were prepared by weighing 7.4 g of amorphous fine particles with an average particle size of 0.01 μm and placing them in a mixer or dispersion machine.
:Mix thoroughly and add the mixture as shown in Figure 3 (not shown in Figure 3).
0 (ultrafine silicon dioxide 1 on the surface of the melting point glass 11)
Coat the surface with 1 kftIM.

At the same time, the surface of lead titanate, which is a filler, is coated, but not only does it have no effect on the effect of lowering the expansion coefficient, but in the case of amorphous silicon dioxide, the thermal expansion coefficient is 5X10/℃. Since it is a small value, it can also effectively act on lowering the thermal vJ expansion coefficient. In addition, Big Men 1 may be added to add color.

Beagle 230 is added to the sealing material mixed as above.
Add g and form into a paste.

The vehicle contains 1 to 2% of a cellulose binder such as edylcellulose or methylcellulose and 98% of an alcohol, such as terpineol, as a solvent for the binder.
It is composed of ~90v%.

This vehicle is the previous II+! Sealing (8-10 for the price)
Add at a ratio of 7% to make a base l-shape. The base material thus formed has dixotropic properties and excellent printing properties.

Example 2 Low melting point glass 79v% Button n' IQ++ Zirconium silicate 1SLOLL Ultrafine silicon dioxide l/11n In this example, a two-component material with a low expansion coefficient of lead titanate and zirconium silicate was used as a filler. In addition, ultrafine silicon dioxide particles were mixed at lv 7% to prevent deterioration of low melting point glass and improve thixotropy.
This is an example in which the value is larger than yt゛.

The only difference from Example 1 is the ratio of the ingredients, and the rest is the same as Example 1, so the explanation will be omitted.

The present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof. According to the sealing material, since ultrafine silicon dioxide is added to the low melting point glass particles, which are the main component in the sealing material, it acts as a protective layer for the chemically weak low melting point glass.
Without moisture or chemicals directly adhering to low melting point glass,
Further, it can be released by heat treatment during sealing. Therefore, it has the effect of providing a material with strong chemical resistance and water resistance.8 Also, since silicon dioxide is made into ultrafine particles of 1 μm or less, it has thixotropic properties and has the effect of significantly improving printing characteristics.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of general fluorescent display tubes;
The figure is an enlarged view of the sealing material of the present invention. 11...Low melting point glass 12.Old...Filler substance 13...5in2 of ultrafine particles

Claims (4)

[Claims] (1) In terms of weight percent, the button-boric acid low melting point glass with a softening point of 450'C or less is 60-85%, the low expansion coefficient is 14-38%, and the average particle size is 1μ Gold H below
Arrival material consisting of 0.05 to 15% ultrafine particles of ire compound. (2) The function M (point glass and low-expansion filler are uniformly dispersed, and the metal oxide fine particles are attached to almost the entire surface of each of them. Claim tiS1) arrival of materials. (3) The low-swelling filler comprises at least one substance selected from lead ditanate, zirconium silicate, β-spodumene, β-eucributylene, cordierite, etc. Sealing material according to item 2. (4) The sealing material according to claim 1, 2, or 3, wherein the metal oxide comprises at least one substance selected from silicon dioxide, aluminum oxide, and ditanium oxide.