JP2007210880A - Bismuth-based glass composition and bismuth-based sealing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bismuth based glass composition free from devitrification in primary firing at ≥480°C and capable of securing excellent flowability and sealing strength in secondary firing of a next step and a bismuth based sealing material. <P>SOLUTION: The bismuth based glass composition contains a glass composition of 30-50% Bi<SB>2</SB>O<SB>3</SB>, 20-35% B<SB>2</SB>O<SB>3</SB>, 10-25% ZnO, 1-15% BaO and 3-15% BaO+SrO+MgO+CaO by mol and satisfies Bi<SB>2</SB>O<SB>3</SB>/B<SB>2</SB>O<SB>3</SB>of 1.0-1.75 (where 1.75 is excluded) and ZnO/(BaO+SrO+MgO+CaO) of 1.0-3.5 by mol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bismuth-based glass composition and a bismuth-based sealing material suitable for sealing flat display devices, electronic parts, and the like, and in particular, a plasma display panel (hereinafter referred to as PDP), a field emission display (hereinafter referred to as FED). Bismuth-based glass composition and bismuth-based sealing material suitable for sealing flat display devices such as fluorescent display tubes (hereinafter referred to as VFD) and sealing electronic parts such as crystal resonators and IC packages It is about.

  Conventionally, glass has been used as a sealing material for flat display devices and the like. Glass is excellent in chemical durability and heat resistance as compared with a resin-based adhesive, and is suitable for ensuring airtightness of a flat display device or the like.

  These glasses require various properties such as mechanical strength, fluidity, and electrical insulation depending on the application, but they are used at a temperature that does not deteriorate at least the fluorescence properties of phosphors used in flat display devices. It is required to be possible. Therefore, as a glass that satisfies the above characteristics, lead borate glass (see, for example, Patent Document 1) containing a large amount of PbO that has an extremely large effect of lowering the melting point of the glass has been widely used.

However, recently, environmental problems have been pointed out with respect to PbO contained in lead borate glass, and it is desired to replace lead borate glass with glass containing no PbO. Therefore, various low melting glass has been developed as a substitute for lead borate glass. Among them, the bismuth glass (also referred to as Bi ₂ O ₃ —B ₂ O ₃ glass) described in Patent Document 2 is a lead borate glass in various properties such as chemical durability and mechanical strength. Therefore, it is expected as an alternative candidate.

By the way, the sealing material used for PDP goes through the following processes. First, using a kneading apparatus such as a three-roll mill, the sealing material and the vehicle are uniformly mixed to form a paste. In general, a vehicle contains an organic solvent, a resin, and the like, and a nitrocellulose, an acrylic resin, or the like that is thermally decomposed well at a temperature below the softening point of glass is used as the resin. Next, the paste prepared on the outer peripheral edge of the rear glass substrate of the PDP is applied, and the vehicle components are pyrolyzed or incinerated at a high temperature to perform primary firing (glaze firing, temporary firing). The primary firing is performed under temperature conditions where the resin used in the vehicle is completely pyrolyzed. Further, secondary firing (main firing) of the sealing material is performed to seal the front glass substrate and the back glass substrate of the PDP. Finally, the inside of the PDP is evacuated through the exhaust pipe, and then a necessary amount of rare gas is injected to seal the exhaust pipe. In this way, the PDP is manufactured.
Japanese Unexamined Patent Publication No. Sho 63-315536 JP-A-6-24797

  In recent years, for the purpose of improving the production efficiency of PDP, primary firing of a sealing material and a phosphor material may be performed simultaneously.

  Here, the phosphor material is used after the phosphor powder is uniformly dispersed in a vehicle made of an organic solvent or resin and processed into a paste. Generally, as a resin used for this vehicle, ethyl cellulose having good viscosity characteristics and the like are used. Note that ethyl cellulose has a higher decomposition temperature and inferior thermal decomposability than nitrocellulose and acrylic resins. Therefore, when the primary firing of the phosphor material and the sealing material is performed at the same time, the temperature condition is such that the thermal decomposition of ethyl cellulose proceeds sufficiently. Further, in order to satisfy the demand for improving the production efficiency of PDP, it is necessary to thermally decompose ethylcellulose in a short time, and the conditions for primary firing need to be 480 ° C. or higher and about 30 minutes. In other words, if the temperature condition of the primary firing is less than 480 ° C., it takes a long time for the thermal decomposition of ethylcellulose, which may reduce the production efficiency of PDP.

  On the other hand, as a resin used for the vehicle in which the phosphor material is dispersed, a method using a resin having good thermal decomposability, such as nitrocellulose, is conceivable, but such a resin is not sufficiently viscous, Since it is difficult to secure sufficient viscosity and the workability of applying the phosphor material is deteriorated, there is a possibility that the manufacturing efficiency of the PDP may be reduced.

  Further, the secondary firing provided after the primary firing of the sealing material is performed at a temperature that does not deteriorate the fluorescent characteristics of the phosphor, and is performed at as low a temperature as possible in consideration of energy efficiency and the like. Specifically, the secondary firing condition of the sealing material is 500 ° C. or less, preferably 450 to 480 ° C. for about 30 minutes.

  By the way, the conventional lead boric acid-based sealing material has good thermal stability, so that crystals are not deposited on the glass after primary firing at 480 ° C. or higher, and further secondary firing is performed at 450 to 480 ° C. Also, no crystals were deposited on the glass. However, the bismuth-based sealing material has a narrower temperature range that can be used stably than the lead boric acid-based sealing material, and is inferior in thermal stability. That is, it is possible to obtain a bismuth-based sealing material in which crystals are not deposited on the glass after primary firing at 480 ° C. or higher, and crystals are not deposited on the glass even if secondary firing is performed at 450 to 480 ° C. could not. In particular, when the primary firing of the bismuth-based sealing material is set to 500 ° C. or higher, crystals are deposited on the glass, and crystals are further grown by the secondary firing provided thereafter. In this case, the bismuth-based sealing material cannot be ensured in fluidity by secondary firing, and the sealing material is not properly crushed by secondary firing, and there is a possibility that the airtightness of the PDP cannot be secured. In addition, when the fluidity of the bismuth-based sealing material is poor, there is a problem that the reaction at the interface between the glass substrate and the sealing material does not proceed sufficiently and the sealing strength of the PDP is poor.

  Patent Document 2 describes a bismuth-based sealing material that can be used for sealing electronic parts. However, this bismuth-based sealing material has poor devitrification resistance as compared with the lead boric acid-based sealing material. In particular, when a refractory filler powder is contained, the devitrification property is remarkable. Therefore, when the bismuth-based sealing material described in Patent Document 2 is used, when the primary firing of the bismuth-based sealing material and the phosphor material is performed simultaneously, that is, when firing at 480 ° C. or higher, the bismuth-based glass is lost. Through and subsequent secondary firing, it becomes difficult to flow, and as a result, the hermetic reliability of the PDP cannot be ensured.

  Therefore, an object of the present invention is to provide a bismuth system that does not devitrify even when subjected to primary firing at 480 ° C. or higher, and can ensure good fluidity and sealing strength by secondary firing provided thereafter. It is to provide a glass composition and a bismuth-based sealing material.

The inventors of the present invention regulate the glass composition of bismuth glass within a predetermined range, and when the molar ratio (molar fraction) of ZnO and alkaline earth metal oxide is regulated within a predetermined range, primary baking is performed at 480 ° C. or higher. However, it has been found that crystals are not generated in the bismuth-based glass and that the bismuth-based glass flows well by secondary firing at 450 to 480 ° C. Furthermore, when the molar ratio of Bi ₂ O ₃ and B ₂ O ₃ is regulated within a predetermined range, it is found that it can be suitably used under PDP firing conditions, and is proposed as the present invention.

  Further, the bismuth glass composition of the present invention regulates the glass composition of the bismuth glass to a predetermined range, and thus has a thermal stability equal to or higher than that of the lead borate sealing material, and is stable. The usable temperature range is extremely wide. In particular, even when the primary firing is set to 500 ° C. or higher, no crystals are precipitated on the bismuth-based glass, and no crystals are precipitated by the subsequent secondary firing. Furthermore, the bismuth-based glass composition of the present invention also has a feature that the softening point is low, and even if the primary firing is set to 500 ° C. or higher, it flows well in the secondary firing at 450 to 480 ° C. that is provided thereafter. be able to.

Specifically, the bismuth-based glass composition of the present invention is a mol% in terms of the following oxide, and the glass composition is Bi ₂ O ₃ 30-50%, B ₂ O ₃ 20-35%, ZnO 10-25. %, BaO 1-15%, BaO + SrO + MgO + CaO 3-15%, and Bi ₂ O ₃ / B ₂ O ₃ 1-1.75 (but not 1.75) in molar ratio, ZnO / (BaO + SrO + MgO + CaO) ) Characterized by satisfying the relationship of 1 to 3.5.

Second, the bismuth-based glass composition of the present invention is characterized in that B ₂ O ₃ is 24.4 to 35% (excluding 24.4%).

Third, the bismuth-based glass composition of the present invention is characterized by containing CuO 0 to 10% and Fe ₂ O ₃ 0 to 10%.

  Fourth, the bismuth-based glass composition of the present invention is characterized by substantially not containing PbO. Here, “substantially does not contain PbO” refers to a case where the content of PbO in the glass composition is 1000 ppm or less.

  Fifth, the bismuth-based sealing material of the present invention is characterized in that it contains 45 to 95% by volume of glass powder made of the above-described bismuth-based glass composition and 5 to 55% by volume of refractory filler powder. .

  Sixth, the bismuth-based sealing material of the present invention is characterized in that the refractory filler powder is cordierite, willemite, alumina, tin oxide or a combination thereof.

  Seventh, the bismuth-based sealing material of the present invention is characterized by being used for sealing a PDP. Here, for sealing of the PDP, sealing of the front glass substrate and the back glass substrate, sealing of the exhaust pipe and the back glass substrate, and sealing of a spacer material in some cases are assumed.

  The bismuth-based sealing material having the above-described configuration has a thermal stability equivalent to or higher than that of the lead boric acid-based sealing material, and the temperature range in which it can be stably used is extremely wide. Therefore, the bismuth-based sealing material of the present invention does not precipitate crystals on the bismuth-based glass after the primary firing at 480 ° C. or higher, and even if the secondary firing is performed at 450 to 480 ° C. Does not precipitate. In particular, even when the primary firing is 500 ° C. or higher, there is no situation in which crystals are deposited on the bismuth-based glass and the crystals are further grown by the subsequent secondary firing. Therefore, the bismuth-based sealing material of the present invention can ensure good fluidity in the secondary firing, and the sealing material can be accurately crushed in the secondary firing, so that the airtightness of the PDP is sufficiently secured. can do.

  Further, since the bismuth-based sealing material of the present invention has good fluidity, the reaction at the interface between the glass substrate and the bismuth-based sealing material also proceeds sufficiently, and the sealing strength between the front glass substrate and the rear glass substrate is increased. Can be significantly increased. In addition, since the bismuth-based sealing material of the present invention has good fluidity, an accurate sealing shape can be secured, and the bismuth-based sealing material, the exhaust pipe, the bismuth-based sealing material, and the back glass Generation of cracks at the interface of the substrate can be effectively avoided.

  Furthermore, the bismuth-based sealing material of the present invention has excellent thermal stability in addition to the low softening point of the bismuth-based glass, so that it does not cause a decrease in fluidity due to devitrification. The reliability of the PDP can be reliably maintained.

  Eighth, the bismuth tablet of the present invention (the tablet is also referred to as press frit, glass sintered body, glass molded body, etc.) is a bismuth tablet obtained by sintering a bismuth sealing material into a predetermined shape. The bismuth-based sealing material is characterized in that it is the bismuth-based sealing material described above. The shape of the bismuth tablet of the present invention is not particularly limited, but it is preferably a ring shape when fixing the exhaust pipe is assumed.

  Ninthly, the tablet-integrated exhaust pipe of the present invention is characterized in that the above-described bismuth-based tablet is attached to the tip of the expanded exhaust pipe. Here, in the present invention, the “tip portion of the exhaust pipe” refers to a surface portion of the exhaust pipe having an enlarged diameter, and the exhaust pipe bottom surface and the exhaust pipe outer peripheral side surface on the side in contact with the panel in the enlarged diameter portion Point to. Further, the bismuth-based tablet includes not only an aspect in which the bismuth-based tablet is adhered only to the distal end portion of the exhaust pipe but also an aspect in which the bismuth tablet is adhered to a part of the distal end portion of the exhaust pipe.

  Tenth, the tablet-integrated exhaust pipe of the present invention has the above-mentioned bismuth-based tablet and a high melting point tablet having a softening point of 520 ° C. or higher attached to the tip of the expanded exhaust pipe, and The bismuth-based tablet is attached to the front end side of the expanded exhaust pipe, and the high melting point tablet is attached to the rear end side of the bismuth-based tablet. Further, the “softening point” in the present invention refers to a value measured by a macro type differential thermal analysis (DTA) apparatus.

  The reason for limiting the glass composition range of the bismuth-based glass composition of the present invention as described above is as follows. In addition, the following% display points out mol% except the case where there is a notice.

Bi ₂ O ₃ is a main component for lowering the softening point of bismuth-based glass, and its content is 30 to 50%, preferably 32 to 50%, more preferably 35 to 45%, and most preferably 35. ~ 40%. When the content of Bi ₂ O ₃ is less than 30%, the softening point of the bismuth-based glass becomes high and the fluidity becomes poor at a low temperature, for example, a temperature of about 450 to 480 ° C. On the other hand, when the content of Bi ₂ O ₃ is more than 50%, devitrification tends to occur during primary firing at 480 ° C. or higher.

B ₂ O ₃ is essential as a glass forming component, and its content is 20 to 35%, preferably 22 to 35%, more preferably 24.4 to 35% (however, 24.4% is not included). More preferably, it is 25 to 33%, and most preferably 25 to 30%. When the content of B ₂ O ₃ is less than 20%, a glass network of bismuth-based glass is not sufficiently formed, and devitrification tends to occur during primary firing at 480 ° C. or higher, and is necessary for secondary firing provided thereafter. It becomes difficult to ensure a good fluidity. On the other hand, if the content of B ₂ O ₃ is more than 35%, the viscosity of the bismuth-based glass tends to be high, and it becomes difficult to obtain good fluidity at secondary firing, for example, at a temperature of 450 to 480 ° C. As a result, the sealing strength and airtightness of the PDP may be impaired.

  ZnO has an effect of suppressing devitrification during primary firing, and its content is 10 to 25%, preferably 12 to 22%, more preferably 14 to 20%, and still more preferably 15 to 20%. When the content of ZnO is less than 10%, devitrification is likely to occur during primary firing at 480 ° C. or higher, and it becomes difficult to ensure the fluidity necessary for secondary firing provided thereafter. Moreover, when there is more content of ZnO than 25%, the softening point of bismuth-type glass will become high, and it will become difficult to ensure the fluidity | liquidity required by secondary baking.

  BaO has the effect of suppressing devitrification during primary firing. The content of BaO is 1 to 15%, preferably 2 to 15%, more preferably 3 to 13%, and further preferably 5 to 10%. When the content of BaO is less than 1%, it is difficult to obtain an effect of suppressing devitrification during primary firing. When the content of BaO is more than 15%, the balance with other components cannot be maintained, and conversely, devitrification tends to occur during primary firing, and it is difficult to secure the necessary fluidity in secondary firing provided thereafter. Become.

  The total amount of the alkaline earth metal oxide (BaO + SrO + MgO + CaO) is a component that affects devitrification at the time of primary firing. These contents are preferably 3 to 15%, 5 to 15%, and more preferably 7 to 12% in total. When the total amount of these components is less than 3%, it becomes difficult to obtain the effect of suppressing devitrification during primary firing. On the other hand, if the total amount of these components is more than 15%, the softening point of the bismuth-based glass becomes high, and it becomes difficult to ensure the fluidity necessary for the secondary firing, for example, 450 to 480 ° C. for sealing the PDP. In addition, it is preferable that each content of SrO, MgO, and CaO is 0 to 5%, especially 0 to 3%. When the content of each of SrO, MgO, and CaO is more than 5%, it is difficult to secure the fluidity necessary for secondary firing, for example, sealing of PDP at 450 to 480 ° C.

The molar ratio Bi ₂ O ₃ / B ₂ O ₃ is a component ratio that greatly affects the thermal stability and fluidity of the bismuth-based glass. In the bismuth-based glass, Bi ₂ O ₃ and B ₂ O ₃ are considered to be components that determine the characteristics of the bismuth-based glass because they have a large content and are the main components forming the skeleton of the glass. . Bi ₂ O ₃ is a component that lowers the softening point of bismuth-based glass, and as the content of Bi ₂ O ₃ increases with respect to B ₂ O ₃ , the softening point of bismuth-based glass tends to decrease. On the other hand, as the content of Bi ₂ O ₃ increases with respect to B ₂ O ₃ , the thermal stability of the bismuth-based glass tends to be poor. B ₂ O ₃ is a component that improves the thermal stability of the bismuth-based glass. As the content of B ₂ O ₃ increases with respect to Bi ₂ O ₃ , the thermal stability of the bismuth-based glass increases. improves. On the other hand, the softening point of bismuth glass increases as the content of B ₂ O ₃ increases with respect to Bi ₂ O ₃ . Therefore, Bi ₂ O ₃ and B ₂ O ₃ are in a trade-off relationship, and if the molar ratio of Bi ₂ O ₃ / B ₂ O ₃ is regulated within a predetermined range, the softening point of bismuth-based glass It is possible to optimize the thermal stability, so that crystals do not precipitate on the bismuth glass after primary firing at 480 ° C. or higher, and even if secondary firing is performed at 450 to 480 ° C. Does not precipitate, and a glass having good fluidity can be obtained by secondary baking at 450 to 480 ° C. In the bismuth-based glass composition of the present invention, the molar ratio Bi ₂ O ₃ / B ₂ O ₃ is 1 to 1.75 (however, 1.75 is not included), preferably 1 to 1.7, more preferably 1 It is -1.6, More preferably, it is 1.2-1.6. When the molar ratio Bi ₂ O ₃ / B ₂ O ₃ is smaller than 1, the thermal stability of the glass is improved, but the fluidity necessary for sealing the PDP at the secondary firing, for example, 450 to 480 ° C. is secured. It becomes difficult and it becomes difficult to ensure the airtightness of PDP. When the molar ratio Bi ₂ O ₃ / B ₂ O ₃ is 1.75 or more, the softening point of the bismuth-based glass is lowered, but devitrification is easily caused by primary firing at 480 ° C. or more, It becomes difficult to secure the necessary fluidity in the next firing.

  The molar ratio ZnO / (BaO + SrO + MgO + CaO) is a component ratio that significantly affects the thermal stability of the bismuth glass. ZnO and (BaO + SrO + MgO + CaO) can modify the glass network of bismuth-based glass and affect the thermal stability of bismuth-based glass, but the ZnO content is higher than the total amount of alkaline earth metal oxides. Thermal stability is extremely good within a large range. That is, if ZnO / (BaO + SrO + MgO + CaO) is regulated within a predetermined range, it is possible to improve the thermal stability without increasing the softening point. In the bismuth-based glass composition of the present invention, the molar ratio ZnO / (BaO + SrO + MgO + CaO) is 1 to 3.5, preferably 1.1 to 3.2, more preferably 1.2 to 3, and still more preferably 1.4 to 2.7, most preferably 1.5 to 2.5. If the molar ratio ZnO / (BaO + SrO + MgO + CaO) is less than 1, the bismuth glass becomes thermally unstable and tends to be devitrified by primary firing at 480 ° C. or higher, and the flow necessary for secondary firing provided thereafter. It becomes difficult to secure sex. When the molar ratio ZnO / (BaO + SrO + MgO + CaO) is larger than 3.5, the softening point becomes high, and it becomes difficult to secure the fluidity necessary for secondary firing, for example, sealing of PDP at a temperature of 450 to 480 ° C. It is difficult to ensure airtightness.

  The bismuth-based glass composition of the present invention may contain the following components as optional components in addition to the above components.

  CuO is a component having an effect of suppressing devitrification during primary firing, and its content is 0 to 10%, preferably 0.1 to 10%, and more preferably 1 to 8%. When the content of CuO is more than 10%, the balance with other components is lacking, and conversely, the deposition rate of crystals becomes extremely high, that is, the tendency of devitrification increases and the fluidity tends to deteriorate.

Fe ₂ O ₃ is a component that improves the thermal stability of the bismuth-based glass and suppresses devitrification during primary firing. The content is 0 to 10%, preferably 0.1 to 10%, more preferably 0.3 to 5%. If the content of Fe ₂ O ₃ is more than 10%, the balance with other components is lost, and conversely, when the bismuth glass becomes thermally unstable and is primarily fired at a temperature of 480 ° C. or higher, devitrification occurs. It tends to be easy to do.

Al ₂ O ₃ is a component that improves the thermal stability of the bismuth-based glass and suppresses devitrification during primary firing. The content is 0 to 10%, preferably 0.1 to 8%, more preferably 0.1 to 5%, and still more preferably 0.1 to 1%. When the content of Al ₂ O ₃ is more than 10%, the softening point of the bismuth-based glass becomes too high, and it is difficult to ensure the fluidity necessary for secondary firing, for example, sealing of PDP at a temperature of 450 to 480 ° C. In addition, it becomes difficult to ensure the airtightness of the PDP.

Sb ₂ O ₃ is a component that has an effect of preventing devitrification during primary firing. Moreover, it has the effect of making it difficult for devitrification to occur during secondary firing. The Sb ₂ O ₃ content is 0 to 5%, preferably 0.01 to 5%, more preferably 0.1 to 1.5%. When the content of Sb ₂ O ₃ is more than 5%, in the melting step of bismuth-based glass, the tendency of the molten glass to form an alloy with the platinum container becomes remarkable, and the result is that platinum is an expensive refractory metal. As a result, the manufacturing cost of bismuth glass increases.

SiO ₂ can be added up to 5% for the purpose of improving the weather resistance. When the content of SiO ₂ is more than 5%, the softening point of the bismuth-based glass becomes high, and it becomes difficult to ensure fluidity necessary for secondary firing, for example, sealing of PDP at a temperature of 450 to 480 ° C.

  The oxides of Li, Na, K and Cs are components that lower the softening point of bismuth-based glass, but have the effect of promoting devitrification of bismuth-based glass, so the total amount may be regulated to 2% or less. preferable.

P ₂ O ₅ is a component that suppresses devitrification, but if its content is more than 1%, it tends to cause phase separation, which is not preferable.

MoO ₃ , La ₂ O ₃ , Y ₂ O ₃ and CeO ₂ are components that thermally stabilize the bismuth-based glass. If the total amount of these is more than 3%, the softening point of the bismuth-based glass It becomes difficult to secure the fluidity necessary for the secondary firing, for example, the sealing of the PDP at a temperature of 450 to 480 ° C. In particular, from the viewpoint of improving the thermal stability of the bismuth-based glass, the content of CeO ₂ is preferably 0.01 to 3%, more preferably 0.1 to 2%, and still more preferably 0.2 to 1%. .

The bismuth-based glass composition of the present invention does not exclude an embodiment containing PbO, but as described above, it is preferable that PbO is not substantially contained for environmental reasons. In addition, when PbO is contained in the glass, Pb ²⁺ present in the glass may diffuse to reduce the electrical insulation.

The bismuth-based glass composition having the above glass composition does not devitrify even when subjected to primary firing at 480 ° C. or higher, and further exhibits extremely thermal stability in which crystals do not precipitate even when subjected to secondary firing at a temperature of 450 to 480 ° C. Is a non-crystalline glass having a high temperature range and a wide usable temperature range. Further, this bismuth-based glass composition has a thermal expansion coefficient of about 100 to 120 × 10 ⁻⁷ / ° C. at 30 to 300 ° C. Therefore, if the material has almost the same thermal expansion coefficient as this bismuth-based glass composition, the powder composed of the bismuth-based glass composition should be used alone as a bismuth-based sealing material without adding a refractory filler powder. And can be sealed at a low temperature such as 450 to 480 ° C.

Also, sealing of a material that does not match the thermal expansion coefficient with the bismuth glass composition, such as a high strain point glass substrate (85 × 10 ⁻⁷ / ° C.), a soda plate glass substrate (90 × 10 ⁻⁷ / ° C.), etc. In this case, a bismuth glass powder and a refractory filler powder may be mixed to form a composite material, which may be used as a bismuth sealing material. It is important that the thermal expansion coefficient of the bismuth-based sealing material is designed to be about 10 to 30 × 10 ⁻⁷ / ° C. lower than the sealed object. This is to prevent the bismuth-based sealing material from being destroyed by setting the strain applied to the bismuth-based sealing material after compression to the compression (compression) side. In addition to adjusting the thermal expansion coefficient, for example, a refractory filler powder can be added to improve mechanical strength.

  When mixing the refractory filler powder, the mixing ratio is preferably 45 to 95% by volume for the bismuth glass powder and 5 to 55% by volume for the refractory filler powder, and 50 to 85% by volume for the bismuth glass powder. The refractory filler powder is more preferably 15 to 50% by volume, and the bismuth-based glass powder is more preferably 20 to 80% by volume and the refractory filler powder 20 to 40% by volume. The reason why the ratio of the two is defined in this way is that when the amount of the refractory filler powder is less than 5% by volume, the above-mentioned effect tends to be hardly obtained. This is because there is a risk that it will be impossible to wear.

  Refractory filler powder is required to have low reactivity to the extent that thermal stability does not decrease even when added to bismuth-based glass powder, and depending on the application, low thermal expansion coefficient and high mechanical strength are required. Is done. Moreover, it is preferable that a refractory filler powder does not contain PbO substantially from an environmental viewpoint. Here, “substantially contain no PbO” refers to a case where the content of PbO in the refractory filler powder is 1000 ppm or less.

Various materials can be used as the refractory filler powder. Specifically, cordierite, zircon, zirconia, tin oxide, aluminum titanate, quartz, β-spodumene, mullite, titania, quartz glass, β -Eucryptite, β-quartz solid solution, willemite, alumina, a compound having a basic structure of [AB ₂ (MO ₄ ) ₃ ] (herein, examples of A, B and M include the following components),
A: Li, Na, K, Mg, Ca, Sr, Ba, Zn, Cu, Ni, Mn etc. B: Zr, Ti, Sn, Nb, Al, Sc, Y etc. M: P, Si, W, Mo etc. Alternatively, a mixture of these may be appropriately selected and used depending on the application.

  Among the refractory filler powders, cordierite and willemite are more preferable. Cordierite has the least tendency to lower the thermal stability of bismuth-based glass, and when the temperature condition of primary firing is high, devitrification is less likely to occur in bismuth-based glass, for example, even at 500 ° C. or higher. In addition, since Willemite has the least tendency to lower the fluidity of bismuth glass, if Willemite is used as a refractory filler powder, the bismuth sealing material is accurately crushed by secondary firing, and the PDP is airtight. Can be sufficiently ensured, and the reaction at the interface between the glass substrate and the bismuth-based sealing material can sufficiently proceed to significantly improve the sealing strength between the front glass substrate and the back glass substrate. In particular, in sealing the exhaust pipe and the back glass substrate, the bismuth-based sealing material flows well in the secondary firing, so that an accurate sealing shape can be formed for sealing the exhaust pipe. The cracks generated at the interface between the bismuth-based sealing material and the exhaust pipe and the bismuth-based sealing material and the glass substrate can be suppressed. Furthermore, cordierite and willemite have features of low expansion and excellent mechanical strength.

  It is preferable to add an appropriate amount of tin oxide for the purpose of improving the mechanical strength of the bismuth sealing material.

  Moreover, it is preferable that the refractory filler powder is coated with alumina, zinc oxide, zircon, titania, zirconia or the like because the reaction between the bismuth glass powder and the refractory filler powder can be suppressed. In particular, alumina is preferable because it has a high melting point and hardly reacts with bismuth glass.

  The temperature range in which the bismuth-based sealing material of the present invention can be used satisfactorily is extremely wide. In other words, the temperature difference (ΔT) between the softening point and the crystallization precipitation temperature of the bismuth-based sealing material is large. Therefore, it goes without saying that the bismuth-based sealing material of the present invention is suitable not only for PDP applications but also for flat display devices and electronic parts that undergo a plurality of heat treatment steps. Specific applications include (I) PDP partition and dielectric layer forming materials, (II) VFD sealing materials, insulating layer forming materials, and (III) cathode ray tube (CRT) display sealing. Materials, (IV) Magnetic head-core-to-core or core-slider sealing material, (V) Quartz crystal resonator package, semiconductor package sealing material, and the like.

  A bismuth-based sealing material in which bismuth-based glass powder and a refractory filler powder are mixed may be used as a sealing material in the form of a powder, but a bismuth-based sealing material and a vehicle are uniformly kneaded as a paste. Easy to handle when used. The vehicle is mainly composed of an organic solvent and a resin, and the resin is added for the purpose of adjusting the viscosity of the paste. Moreover, surfactant, a thickener, etc. can also be added as needed. The produced paste is applied using an applicator such as a dispenser or a screen printer.

  As organic solvents, N, N′-dimethylformamide (DMF), α-terpineol, higher alcohol, γ-butyllactone (γ-BL), tetralin, butyl carbitol acetate, ethyl acetate, isoamyl acetate, diethylene glycol monoethyl ether , Diethylene glycol monoethyl ether acetate, benzyl alcohol, toluene, 3-methoxy-3-methylbutanol, water, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl Ether, tripropylene glycol monobutyl ether, propylene carbonate, dimethyl sulfoxide (DMSO) N- methyl-2-pyrrolidone and the like can be used. In particular, α-terpineol is preferable because it is highly viscous and has good solubility in resins and the like.

  As the resin, acrylic resin, ethyl cellulose, polyethylene glycol derivative, nitrocellulose, polymethylstyrene, polyethylene carbonate, methacrylic acid ester and the like can be used. In particular, acrylic resin and nitrocellulose are preferable because they have good thermal decomposability.

  The bismuth-based sealing material of the present invention is preferably sintered into a predetermined shape to form a bismuth-based tablet. That is, the bismuth-based tablet of the present invention is suitable for fixing the exhaust pipe of the PDP because it has good fluidity and heat resistance. If the bismuth-based sealing material of the present invention is processed into a tablet, the exhaust pipe can be easily connected to the exhaust equipment and the inclination of the exhaust pipe can be reduced with respect to the panel, that is, the panel surface. The flat panel display device can be easily attached vertically, and the flat display device can be attached so that the airtightness is maintained while maintaining the light emission capability.

  The bismuth-based tablet of the present invention is preferably ring-shaped. If it does in this way, it will become easy to insert an exhaust pipe, it will become easy to align the tip part of an exhaust pipe to the position of the exhaust hole of a panel, and it will become easy to fix with a clip etc. Further, the exhaust pipe can be easily attached to the panel by baking at the sealing temperature of the bismuth-based tablet and softening the bismuth-based tablet.

  The bismuth-based tablet of the present invention is produced through a plurality of independent heating processes as follows. First, a binder or solvent is added to a bismuth-based material to form a slurry. Thereafter, this slurry is put into a granulator such as a spray dryer to produce granules. At that time, the granules are heat-treated at a temperature at which the solvent volatilizes (about 100 to 200 ° C.). Furthermore, the produced granule is put into a mold designed to have a predetermined size and is dry press-molded into a ring shape or the like to produce a pressed body. Next, the binder remaining in the pressed body is decomposed and volatilized in a baking furnace such as a belt furnace, and baked at a temperature about the softening point of the bismuth glass to produce a bismuth tablet. Further, firing in the firing furnace may be performed a plurality of times. When the baking is performed a plurality of times, the strength of the bismuth-based tablet is improved, and the loss or breakage of the bismuth-based tablet can be effectively prevented. In addition, since the bismuth-type tablet of this invention has favorable thermal stability, even if baking near the softening point of bismuth-type glass is performed in multiple times, devitrification does not arise in bismuth-type glass.

  The bismuth-based tablet of the present invention is preferably used as a tablet-integrated exhaust pipe by being attached to the distal end portion of the expanded exhaust pipe. With the above configuration, it is not necessary to simultaneously align the center of the three parts of the panel, the bismuth tablet and the exhaust pipe in the exhaust hole, and the exhaust pipe installation work can be simplified. In order to manufacture such a tablet-integrated exhaust pipe, it is necessary to bake the bismuth-based tablet in contact with one end of the exhaust pipe and bond the bismuth-based tablet to the tip of the exhaust pipe. In such a case, a method of generally fixing the exhaust pipe with a jig and inserting a bismuth-based tablet into the exhaust pipe in this state and firing can be employed. As a jig for fixing the exhaust pipe, it is preferable to use a material to which the bismuth-based tablet is not fused. For example, a carbon jig or the like can be used. Moreover, what is necessary is just to perform adhesion | attachment of an exhaust pipe and a bismuth-type tablet for about 5 to 10 minutes in the vicinity of the softening point of bismuth-type glass. Furthermore, since the bismuth-based tablet of the present invention has good fluidity, the sealing strength between the article to be sealed and the bismuth-based tablet is good. In addition, since the tablet-integrated exhaust pipe of the present invention has good thermal stability of the bismuth-based tablet, devitrification does not occur in the bismuth-based glass when the tablet-integrated exhaust pipe is assembled.

As the exhaust pipe, SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ glass containing a predetermined amount of an alkali metal oxide is suitable, but in particular, product grade “FE-2” manufactured by Nippon Electric Glass Co., Ltd. Is preferred. This exhaust pipe has a thermal expansion coefficient of 85 × 10 ⁻⁷ / ° C., a heat resistant temperature of 550 ° C., and has dimensions of, for example, an outer diameter of 5 mm and an inner diameter of 3.5 mm. Moreover, it is preferable to enlarge the diameter of the tip of the exhaust pipe, and it is preferable to form a flare or flange at the tip. Various methods can be adopted as a method for expanding the diameter of the tip of the exhaust pipe. Among them, a method of heating using a gas burner while rotating the tip of the exhaust pipe and processing it into a predetermined shape using several kinds of jigs is preferable because it is excellent in mass productivity.

  FIG. 1 shows an example of a tablet-integrated exhaust pipe having such a configuration. FIG. 1 is a cross-sectional view of a tablet-integrated exhaust pipe, the tip of the exhaust pipe 1 is enlarged in diameter, and a bismuth-based tablet 2 is bonded to the tip of the exhaust pipe on the panel side.

  In the tablet-integrated exhaust pipe of the present invention, a bismuth tablet and a high melting point tablet having a softening point of 520 ° C. or higher are attached to the tip of the expanded exhaust pipe, and the bismuth tablet is expanded. It is preferable that the high melting point tablet is attached to the rear end portion side of the bismuth-based tablet by being attached to the front end portion side of the exhaust pipe. If the tablet-integrated exhaust pipe has such a configuration, since the bismuth-based tablet is attached to the distal end side of the exhaust pipe, the area that comes into contact with the panel when the exhaust pipe is attached to the panel etc. Therefore, the exhaust pipe can be made stable on a panel or the like stably, and can be easily mounted vertically without being inclined with respect to the panel or the like. If the tablet-integrated exhaust pipe is configured as described above, when the bismuth-based tablet is fixed to the exhaust pipe in the process of manufacturing the tablet-integrated exhaust pipe, the high melting point tablet is interposed between the jig and the bismuth-based tablet. Therefore, it is possible to manufacture the tablet integrated exhaust pipe, that is, it is not necessary to use a special jig in manufacturing the tablet integrated exhaust pipe, and the manufacturing process can be simplified.

  In the tablet-integrated exhaust pipe having the above-described configuration, the bismuth-based tablet is preferably fixed to the outer peripheral surface of the tip of the exhaust pipe, more preferably only fixed to the outer peripheral surface of the tip of the exhaust pipe. It is not fixed to the front end surface, that is, the surface bonded to the panel or the like. In this way, it is possible to easily prevent the glass from flowing into the exhaust holes formed in the panel or the like. In addition, if the high melting point tablet is not directly bonded to the exhaust pipe, but is fixed to the exhaust pipe via a bismuth tablet, the exhaust pipe is pressure sealed with the high melting point tablet part fixed with a clip in the sealing process. This is preferable because it is possible.

  As the high melting point tablet, it is preferable to use product grades “ST-4” and “FN-13” manufactured by Nippon Electric Glass Co., Ltd. as materials. The high melting point tablet can be produced by the same method as the above-described bismuth tablet. Moreover, ceramics, metal, etc. can also be used as a material of the high melting point tablet.

  FIG. 2 shows an example of the tablet-integrated exhaust pipe having such a configuration. FIG. 2 is a cross-sectional view of the tablet-integrated exhaust pipe. The tip of the exhaust pipe 1 is enlarged in diameter, and the bismuth tablet 2 is bonded to the tip of the exhaust pipe 1 on the outer peripheral surface side of the flange portion 1a. ing. On the other hand, the high melting point tablet 3 is not bonded to the outer peripheral surface side of the exhaust pipe 1. The bismuth tablet 2 is attached to the front end side of the flange portion 1 a, and the high melting point tablet 3 is attached to the rear end portion side of the flange portion 1 a than the bismuth tablet 2.

  Hereinafter, the present invention will be described in detail based on examples.

  Tables 1 to 3 show examples (samples a to o) of the bismuth-based glass composition of the present invention, and Table 4 shows comparative examples (samples p to t).

  Samples a to t described in Tables 1 to 4 were prepared as follows.

  First, a glass batch prepared by preparing raw materials such as various oxides and carbonates so as to have the glass compositions shown in Tables 1 to 4 was prepared, and this was put in a platinum crucible and melted at 900 to 1000 ° C. for 1 to 2 hours. did. Next, a part of the molten glass was poured into a stainless steel mold as a sample for measuring the coefficient of thermal expansion, and the other molten glass was formed into a thin piece with a water-cooled roller. The sample for measuring the thermal expansion coefficient was subjected to a predetermined slow cooling treatment (annealing) after molding. Finally, the flaky glass was pulverized with a ball mill and then passed through a sieve having an opening of 75 μm to obtain each sample having an average particle size of about 10 μm.

  Using the above samples, the glass transition point, the softening point, and the thermal expansion coefficient were evaluated. The results are shown in Tables 1-4.

  The softening point was determined with a DTA apparatus.

  The glass transition point and the thermal expansion coefficient were determined by a push rod type thermal expansion measuring device.

As is apparent from Tables 1 to 3, samples a to o, which are examples of the bismuth glass composition of the present invention, have a glass transition point of 349 to 369 ° C, a softening point of 423 to 443 ° C, and a temperature of 30 to 300 ° C. The thermal expansion coefficient in was 106 to 118 × 10 ⁻⁷ / ° C.

Samples a to e in Table 1 and samples p and q in Table 4 have substantially the same amount of the alkaline earth metal oxide and the molar ratio of ZnO / (BaO + SrO + MgO + CaO), and Bi ₂ O ₃ and B _2. The amount of components other than O ₃ is substantially the same. On the other hand, the sample p, q in Table 1 sample a~e and Table 4, the molar ratio of Bi ₂ O ₃ and B ₂ O ingredient amounts ₃ and Bi ₂ O ₃ / B ₂ O ₃ are different. In samples a to e in Table 1, sample a having the smallest Bi ₂ O ₃ / B ₂ O ₃ molar ratio has the highest thermal stability because B ₂ O ₃ is the most glass-forming oxide. It can be judged that there is. However, in the sample p, the molar ratio of Bi ₂ O ₃ / B ₂ O ₃ is smaller than that of the sample a, but the glass-forming oxide B ₂ O ₃ is excessive with respect to Bi ₂ O ₃ . The softening point is as high as 452 ° C., which can be determined to be unsuitable for sealing PDP or the like. Moreover, in the samples a to e in Table 1, the sample e having the largest Bi ₂ O ₃ / B ₂ O ₃ molar ratio has the most Bi ₂ O ₃ , so that it can be determined that the fluidity is the best. However, the sample q has a Bi ₂ O ₃ / B ₂ O ₃ molar ratio larger than that of the sample e, but the glass-forming oxide has too little B ₂ O ₃ relative to Bi ₂ O ₃ , so that the thermal stability is high. Therefore, it can be judged to be unsuitable for sealing PDP or the like.

Table 2 samples f~j and samples r in Table 4, s, together with the molar ratio of Bi ₂ O ₃ and B ₂ O ingredient amounts ₃ and Bi ₂ O ₃ / B ₂ O ₃ is substantially the same amount, The amount of components other than ZnO and alkaline earth metal oxide is substantially the same. On the other hand, samples f to j in Table 2 and samples r and s in Table 4 are different in the total amount of ZnO, alkaline earth metal oxide, alkaline earth metal oxide, and the molar ratio of ZnO / (BaO + SrO + MgO + CaO). . Samples f to j in Table 2 and samples r and s in Table 4 had substantially the same thermal expansion coefficient, glass transition point, and softening point.

In the samples k to o in Table 3, all the glass compositions are regulated within a predetermined range, and the molar ratio of Bi ₂ O ₃ / B ₂ O _{3 and} the molar ratio of ZnO / (BaO + SrO + MgO + CaO) are also regulated within the predetermined range. ing. Samples k to o in Table 3 can be determined to be suitable for sealing PDP or the like even from the characteristics such as the softening point. On the other hand, the sample t in Table 4 has an excessive ZnO component amount of 26.9%, and as a result, the softening point becomes high at 452 ° C., which can be determined to be unsuitable for sealing PDP or the like.

  Next, bismuth-based sealing materials were prepared using the bismuth-based glass compositions shown in Tables 1 to 4. Table 5 shows examples (sample Nos. 1 to 16) of the bismuth sealing material of the present invention, and Table 6 shows comparative examples (samples No. 17 to 21).

  Each sample was prepared by mixing bismuth-based glass powder and refractory filler powder in the ratios shown in Tables 5 and 6. Willemite or cordierite was used as the refractory filler powder.

Willemite is prepared by blending zinc oxide, pure silica powder, and aluminum oxide with a composition of 70% ZnO, 25% SiO _{2 and} 5% Al ₂ O ₃ by weight. After mixing, baked at 1440 ° C for 15 hours. Then, the fired product was pulverized and passed through a 250 mesh stainless steel sieve. Cordierite is prepared by mixing magnesium oxide, aluminum oxide, and pure silica powder in a ratio of 2MgO · 2Al ₂ O ₃ · 5SiO ₂ , mixing and firing at 1400 ° C. for 10 hours, then crushing the fired product And what passed through the 250 mesh stainless steel sieve was used.

  The flow diameter was dry-pressed into a button shape with an outer diameter of 20 mm using a mold and the weight corresponding to the synthesis density of each sample, and this was placed on a 40 mm × 40 mm × 2.8 mm thick high strain point glass substrate. Then, the temperature was increased in air at a rate of 10 ° C./minute, held at 500 ° C. for 30 minutes, then cooled to room temperature at 10 ° C./minute, and the diameter of the obtained button was measured. The synthetic density is a theoretical density calculated by mixing the density of the glass powder and the density of the refractory filler powder at a predetermined volume ratio. Moreover, it means that the fluidity | liquidity of a bismuth type sealing material is excellent in primary baking as a flow diameter is 22 mm or more.

  The devitrification state was evaluated by observing the devitrification state of each sample using an optical microscope (100 times magnification) after holding each sample at 500 ° C. for 30 minutes. The temperature raising / lowering rate was 10 ° C./min. As a result, “◯” indicates that no devitrification was observed, and “X” indicates that devitrification was observed. In addition, it can be judged that the sample which obtained evaluation of "(circle)" by this test does not devitrify by primary baking, and has favorable thermal stability.

  For reflowability, the button sample prepared by evaluating the flow diameter is placed in contact with a separately prepared glass substrate so that the top of the button sample is downward, and then heated at 10 ° C./min in air. The temperature was lowered to 10 ° C./min until room temperature was maintained at 480 ° C. for 30 minutes, and evaluation was made based on the degree of collapse of the buttons sandwiched between the two glass substrates. A sample having a button diameter (average button diameter of an adhesion region) on a separately prepared glass substrate of 19 mm or more was designated as “◯”, and a sample having a button diameter of less than 19 mm was designated as “X”. Here, it can be judged that the sample which obtained the evaluation of “◯” has good fluidity in the secondary firing and excellent thermal stability to the extent that devitrification does not occur in the secondary firing.

As is apparent from Table 5, sample No. 1 to 16 had a softening point of 429 to 463 ° C. and a thermal expansion coefficient of 73 to 80 × 10 ⁻⁷ / ° C. at 30 to 300 ° C. Sample No. 1 to 16 had a flow diameter of 23.1 to 25.3 mm and had good fluidity. Furthermore, sample no. 1 to 16 had good devitrification and good thermal stability. Furthermore, sample no. In Nos. 1 to 16, reflowability was also good, thermal stability was excellent to such an extent that devitrification did not occur in secondary firing, and fluidity in secondary firing was also good. Therefore, sample no. 1 to 16 can be determined to be suitable for sealing a PDP or the like.

As apparent from Table 6, the sample No. 17 to 21 had a softening point of 430 to 469 ° C. and a thermal expansion coefficient of 68 to 83 × 10 ⁻⁷ / ° C. at 30 to 300 ° C. Sample No. Nos. 17 and 21 had small flow diameters of 19.9 mm and 20.6 mm, respectively, and had poor fluidity. Sample No. In 18, 19, and 20, devitrification was observed, and the thermal stability was poor. Sample No. 17 to 21 had poor reflowability. Therefore, sample no. It can be judged that Nos. 17 to 21 are not suitable for sealing PDP or the like because at least thermal stability and fluidity are not compatible.

Sample No. in Table 5 1-3, 5, 6 and Sample No. Nos. 17 and 18 use cordierite as the refractory filler powder and have the same content ratio. Sample No. in Table 5 1-3, 5, 6 and Sample No. The glass composition of the glass powder used for 17 and 18 is the samples a to e of Table 1 and the samples p and q of Table 4, and as described above, these are the total amount of the alkaline earth metal oxide and ZnO / ( The molar ratio of BaO + SrO + MgO + CaO) is approximately the same, and the amounts of components other than Bi ₂ O ₃ and B ₂ O ₃ are approximately the same. Sample No. in Table 5 1-3, 5 and 6 have good evaluation of flow diameter, devitrification, and reflowability because Bi ₂ O ₃ / B ₂ O _{3 of} bismuth-based glass is regulated within a predetermined range, and PDP It has fluidity and thermal stability suitable for sealing, and can be judged to be suitable for sealing PDP. However, the sample No. using the sample p having a smaller Bi ₂ O ₃ / B ₂ O ₃ molar ratio than the sample a. 17 is excessive B ₂ O ₃ glass-forming oxides relative to Bi ₂ O ₃ in the glass composition, the softening point is as high as 469 ° C., as a result, in addition to the flow diameter is small and 19.9mm Reflowability is also poor and it can be determined that the fluidity suitable for sealing PDP or the like is not provided. Sample No. using a sample q having a Bi ₂ O ₃ / B ₂ O ₃ molar ratio larger than that of the sample e. No. 18 has a glass composition having too little B ₂ O _{3 as} a glass-forming oxide with respect to Bi ₂ O ₃ , and as a result, thermal stability is impaired, evaluation of the devitrification state becomes poor, and sealing of PDP or the like It can be judged that it does not have thermal stability suitable for wearing.

Sample No. in Table 5 7 to 11 and sample Nos. Nos. 19 and 20 use willemite as the refractory filler powder, and the content ratio is also equivalent. Sample No. in Table 5 7 to 11 and sample Nos. The glass compositions of the glass powders used in 19 and 20 are the samples f to j in Table 2 and the samples r and s in Table 4, and as described above, these are the amounts of components of Bi ₂ O ₃ and B ₂ O ₃ and The molar ratio of Bi ₂ O ₃ / B ₂ O ₃ is approximately the same, and the components other than ZnO and the alkaline earth metal oxide are approximately the same. Sample No. in Table 5 In Nos. 7 to 11, since ZnO / (BaO + SrO + MgO + CaO) of the glass is regulated within a predetermined range, the evaluation of the flow diameter, devitrification state, and reflowability is good, and the flowability and heat suitable for PDP sealing. It can be judged that it is suitable for sealing PDP. However, sample no. The sample r used in 19 has an excess of (BaO + SrO + MgO + CaO) with respect to ZnO. As a result, the thermal stability is impaired, and the evaluation of the devitrification state becomes poor. Therefore, it can be determined that the reflowability is poor and the thermal stability suitable for sealing PDP or the like is not provided. Sample No. The sample s used in No. 20 has too little (BaO + SrO + MgO + CaO) with respect to ZnO, resulting in a loss of thermal stability and poor evaluation of the devitrification state. It can be determined that the reflowability is poor and the thermal stability suitable for sealing PDP or the like is not provided.

  Sample No. in Table 5 As described above, Nos. 12 to 16 contain the glass compositions of the samples k to o within a predetermined range and contain filler powder willemite and cordierite within a predetermined range. Therefore, the sample Nos. Nos. 12 to 16 have good evaluation of flow diameter, devitrification state, reflowability, fluidity and thermal stability suitable for PDP sealing, and are suitable for PDP sealing. I can judge. However, sample no. Sample t used in No. 21 has an excessive amount of ZnO component. As a result, the softening point is increased to 462 ° C., the flow diameter is small as 20.6 mm, and the reflowability is poor. It can be judged that it does not have fluidity suitable for sealing.

  As is clear from the above description, the bismuth-based glass composition and the bismuth-based sealing material of the present invention are used for sealing flat display devices such as PDP, FED, and VFD, for sealing displays such as CRT, and for quartz. It is suitable for sealing electronic parts such as vibrators and IC packages, forming an insulating dielectric layer of a PDP, forming a partition wall of a PDP, and sealing a magnetic head-core or between a core and a slider.

It is sectional drawing which shows the tablet integrated exhaust pipe of this invention. It is sectional drawing which shows the tablet integrated exhaust pipe of this invention.

Explanation of symbols

1 Exhaust pipe 2 Bismuth tablet 3 High melting point tablet

Claims (10)

In mol% terms of oxide, as a glass composition, containing _{Bi 2 O 3 30~50%, B} 2 O 3 20~35%, 10~25% ZnO, BaO 1~15%, the 3~15% BaO + SrO + MgO + CaO And Bi ₂ O ₃ / B ₂ O ₃ 1-1.75 (however, 1.75 is not included) and ZnO / (BaO + SrO + MgO + CaO) 1-3.5 are satisfied in a molar ratio. Bismuth glass composition. B ₂ O ₃ is from 24.4 to 35% (however, 24.4% exclusive) bismuth glass composition according to claim 1, characterized in that a. The bismuth-based glass composition according to claim 1, comprising 0 to 10% of CuO and 0 to 10% of Fe ₂ O ₃ .   The bismuth-based glass composition according to any one of claims 1 to 3, which does not substantially contain PbO.   In the sealing material containing glass powder and a refractory filler powder, 45-95 volume% of glass powder which consists of a bismuth-type glass composition in any one of Claims 1-4, and refractory filler powder 5-55 volume %. A bismuth-based sealing material characterized by comprising:   The bismuth-based sealing material according to claim 5, wherein the refractory filler powder is cordierite, willemite, alumina, tin oxide or a combination thereof.   The bismuth-based sealing material according to claim 5 or 6, which is used for sealing a plasma display panel.   A bismuth-based tablet obtained by sintering a bismuth-based sealing material into a predetermined shape, wherein the bismuth-based sealing material is the bismuth-based sealing material according to any one of claims 5 to 7. Tablet.   A tablet-integrated exhaust pipe, wherein the bismuth-based tablet according to claim 8 is attached to a distal end portion of the exhaust pipe having an enlarged diameter.   An exhaust pipe in which the bismuth-based tablet according to claim 8 and a high melting point tablet having a softening point of 520 ° C or higher are attached to the tip of the expanded exhaust pipe, and the diameter of the bismuth-based tablet is expanded A tablet-integrated exhaust pipe, wherein the high-melting-point tablet is attached to the rear end side of the bismuth-based tablet.

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