JP5257829B2 - Sealing material - Google Patents

Description

  The present invention relates to a sealing material suitable for an electronic component or a flat display device. In particular, the present invention relates to a sealing material suitable for sealing a front glass substrate and a back glass substrate of a plasma display panel (PDP).

  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 can be used at temperatures that do not deteriorate the fluorescent properties of phosphors used in flat display devices. It is required to be. Therefore, as a glass that satisfies the above characteristics, lead borate glass having a large effect of lowering the melting point of the glass has been widely used (see Patent Document 1).

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, bismuth-based glass (Bi ₂ O ₃ —B ₂ O ₃ -based glass) described in Patent Document 2 and the like has substantially the same characteristics as lead borate glass in various properties such as thermal expansion coefficient. Although it is expected as an alternative candidate, the actual situation is that it does not reach that of lead borate glass in terms of characteristics such as fluidity and thermal stability.

  Furthermore, the sealing material is generally a composite material containing glass powder and refractory filler powder, and conventionally, low expansion lead titanate or the like has been used as the refractory filler powder. However, as in the case of glass, it is desired to replace lead titanate and the like with a refractory filler containing no PbO.

By the way, the PDP is manufactured by the following manufacturing process, and the sealing material is subjected to the following heat treatment process. First, a sealing material dispersed in a vehicle is applied to the outer peripheral edge of the rear glass substrate of the PDP, and then the vehicle components are pyrolyzed or incinerated to perform primary firing (glazing process, pre-baking process). A vehicle that uniformly disperses the sealing material contains an organic solvent, a resin, and the like. In general, as the resin, nitrocellulose, an acrylic resin, or the like that is thermally decomposed well at a temperature below the softening point of glass is used. The sealing material and the vehicle are processed into a paste by uniformly kneading using a kneading apparatus such as a three-roll mill. The primary firing is performed under temperature conditions where the resin is completely thermally decomposed. In the primary firing, if the thermal decomposition of the resin is incomplete, a resin residue remains in the glass in the subsequent secondary firing (sealing step, sealing step), and as a result, the glass is devitrified. Or it becomes easy to produce a fatal defect when ensuring the airtightness of PDP, such as a bubble. Next, after aligning the front glass substrate and the back glass substrate, secondary firing is performed, and the front glass substrate and the back glass substrate are sealed with a sealing material. 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

  As described above, the PDP is manufactured through a primary firing process, a secondary firing process, and a vacuum exhaust process. Usually, the primary firing process and the secondary firing process are performed in the air, and the vacuum exhaust process is performed in a high vacuum reduced pressure atmosphere. The evacuation process is a process that requires a long time (usually 7 to 10 hours at 430 ° C.) in order to make the inside of the apparatus into a high vacuum, which is a cause of reducing the production efficiency of the PDP. In view of such circumstances, in recent years, attempts have been made to perform the evacuation process at a high temperature in order to improve the manufacturing efficiency of the PDP. When the evacuation process is performed at a high temperature, specifically 450 to 500 ° C., the inside of the apparatus can be brought into a high vacuum state in a short time, and thus the production efficiency of the PDP can be greatly increased.

  Further, if the evacuation step is performed at 450 ° C. to 500 ° C., the amount of residual gas and impurities inside the device can be reduced. In other words, the degree of vacuum inside the device can be increased. The purity of the gas can be increased, and as a result, the luminance characteristics of the PDP can be improved.

  However, when the evacuation process is performed at 450 to 500 ° C., the following problems occur.

  Generally, a sealing material using amorphous glass powder is used for sealing the front glass substrate and the rear glass substrate of the PDP. The primary firing step and the secondary firing step of the PDP need to be performed at a temperature of 530 ° C. or lower, preferably 510 ° C. or lower in order to prevent deterioration of the phosphor or the like. Therefore, the sealing material is 530 ° C. or lower. It is required to flow well at a temperature of In order to allow the sealing material to flow well at a temperature of 530 ° C. or lower, it is necessary to lower the softening point of the glass powder. In such a case, if the vacuum evacuation step is performed at 450 ° C. or higher, the vacuum evacuation step is performed. In the process, the glass is re-softened, and the sealing material is drawn into the apparatus, so that the airtight reliability of the PDP is easily impaired. In addition, the sealing portion drawn into the apparatus is easily damaged by mechanical impact, and the airtight reliability of the PDP is easily impaired.

  In addition, bismuth-based glass has a higher softening point than lead borate-based glass. Therefore, in sealing materials containing bismuth-based glass powder and refractory filler powder, the softening point of bismuth-based glass powder has been conventionally used. It has been a main technical problem to improve the fluidity of the sealing material by lowering. However, when the fluidity of the sealing material is increased by a conventional method, the sealing material is easily drawn into the apparatus in the vacuum exhaust process, and it is difficult to increase the temperature of the vacuum exhaust process.

  Therefore, the present invention provides a sealing material containing a bismuth-based glass powder and a refractory filler powder, which flows well at a temperature of 530 ° C. or less and hardly deforms in a vacuum exhaust process at 450 ° C. to 500 ° C. It is a technical problem to improve characteristics and manufacturing efficiency of PDP and the like by obtaining materials.

As a result of diligent efforts, the present inventor, in a sealing material containing a bismuth-based glass powder and a refractory filler powder, shows the glass composition range of the bismuth-based glass powder in terms of mass% in terms of the following oxide, Bi ₂ O _{3 73 ~81.4%, B 2 O} 3 2~12%, Al 2 O 3 0~5%, ZnO 1~9.9%, BaO 0~10%, 0~5% CuO, Fe 2 O 3 _0~3%, CeO 2 _0~5%, after having regulated the _Sb 2 O 3 _0~5%, while regulating the values of the mass ratio _{Bi 2 O 3 / B 2 O} 3 to 8.1 to 11, As a refractory filler powder, the present inventors have found that the above technical problem can be solved by containing 2.1 to 45 volume% of zirconium phosphate ((ZrO) ₂ P ₂ O ₇ ), and propose as the present invention. is there. That is, the sealing material of the present invention is a sealing material containing a bismuth-based glass powder and a refractory filler powder. The bismuth-based glass powder has a glass composition represented by mass% in terms of the following oxide, and is expressed as Bi ₂ O. _{3 73 ~81.4%, B 2 O} 3 2~12%, Al 2 O 3 0~5%, ZnO 1~9.9%, BaO 0~10%, 0~5% CuO, Fe 2 O 3 _{0~3%, CeO 2 0~5%,} Sb 2 O 3 containing 0 to 5%, the value of the mass ratio _{Bi 2 O 3 / B 2 O} 3 is 8.1 to 11, and a refractory filler powder And containing 2.1 to 45 vol% of zirconium phosphate.

  The sealing material of the present invention contains 2.1 to 45% by volume of zirconium phosphate as a refractory filler powder. When 2.1 volume% or more of zirconium phosphate is contained in the sealing material, the glass is hardly deformed in the heat treatment process, and the sealing material is not easily drawn into the apparatus in the vacuum exhaust process. On the other hand, if the content of zirconium phosphate is regulated to 45% by volume or less, the fluidity of the sealing material can be ensured in the secondary firing step. That is, by containing 2.1 to 45 volume% of zirconium phosphate, the sealing material is less likely to be drawn into the apparatus even when the evacuation process is performed at 450 to 500 ° C. While being able to make a high vacuum state, a sealing material can be made to flow favorably at the temperature of 530 degrees C or less. As a result, the manufacturing efficiency of the PDP can be greatly increased, and the luminance characteristics of the PDP can be improved.

  The sealing material of the present invention regulates the glass composition range of the bismuth-based glass powder as described above. In this way, the thermal stability of the glass can be improved, and the bismuth-based glass is less likely to be devitrified in the primary firing step and the secondary firing step, and the front glass substrate and the rear glass substrate of the PDP are sealed. Strength can be increased.

  In addition, if the glass composition range of the bismuth-based glass powder is regulated as described above, the softening point of the glass powder can be lowered, so that the fluidity of the sealing material can be increased, and the temperature of the sealing material is 530 ° C. or lower. Can be made to flow well. Further, in this way, even if PbO is not contained in the glass composition, the softening point of the glass can be lowered, so that recent environmental demands can be satisfied.

Secondly, the sealing material of the present invention preferably has an average particle diameter D ₅₀ of zirconium phosphate is 6～40Myuemu. Here, the “average particle diameter D ₅₀ ” referred to in the present invention refers to a value measured by a laser diffraction method.

Third, the sealing material of the present invention, the 10% particle size _{D 10} of zirconium phosphate is preferably 1~6μm and / or 90% particle diameter _{D 90} of an 15～80Myuemu. “10% particle diameter D ₁₀ ” and “90% particle diameter D ₉₀ ” indicate values measured by a laser diffraction method. Further, “average particle diameter D ₁₀ ” is a particle diameter at which the accumulated particle amount is 10%, and “90% particle diameter D ₉₀ ” is a particle diameter at which the accumulated particle amount is 90%.

Fourthly , it is preferable that the sealing material of the present invention has a bismuth-based glass powder having a glass composition having a mass ratio Bi ₂ O ₃ / B ₂ O ₃ of 8.1 to 10.2 .

Fifth, the sealing material of the present invention is preferably non-crystalline. Here, the term “non-crystalline” means that a crystallization peak does not appear at a temperature of 550 ° C. or higher, preferably 570 ° C. or higher, more preferably 600 ° C. or higher by differential thermal analysis (DTA). In addition, DTA is performed in air | atmosphere and a temperature increase rate starts at 10 degree-C / min and room temperature.

  In the crystalline sealing material, once crystals are deposited on the glass, the glass is difficult to be softened and deformed, and the sealing material can be prevented from being drawn into the apparatus in the vacuum exhaust process. However, the crystalline sealing material can easily change the crystal deposition time due to impurities generated in the glass melting process, pulverization process, refractory filler powder mixing process, etc., depending on the production lot of the sealing material, It has the property that the precipitation time of crystals tends to fluctuate. As described above, since a flat display device such as a PDP undergoes a plurality of heat treatment steps, it is difficult to stably seal the front glass substrate and the rear glass substrate when a crystalline sealing material is used. Become. Specifically, if crystals are deposited on the glass in the primary firing step, the crystals deposited on the glass in the secondary firing step grow, and the fluidity of the sealing material is reduced. The sealing strength of the glass substrate tends to decrease, and it becomes difficult to ensure the airtight reliability of the PDP. In that respect, if the sealing material is non-crystalline, the above-mentioned problem does not occur, and the characteristics of the sealing material hardly change due to impurities generated in the manufacturing process of the sealing material. The sealing strength can be ensured. The sealing material of the present invention does not exclude the case where it is crystalline. For example, in the PDP manufacturing process, the heat treatment temperature is increased in the primary firing process, and the crystal is intentionally crystallized on the surface of the sealing site. This does not exclude the aspect of causing

Sixth, it is preferable that the sealing material of the present invention does not substantially contain PbO. Here, “substantially not containing PbO” in the present invention refers to a case where the content of PbO in the glass composition is 1000 ppm or less. In this way, environmental demands in recent years can be satisfied.

Seventh, the sealing material of the present invention is preferably used for sealing the front glass substrate and the rear glass substrate of the PDP.

  The reason for limiting the glass composition range of the bismuth-based glass powder as described above in the sealing material of the present invention will be described below. In addition, the following% display points out the mass% except the case where there is particular notice.

Bi ₂ O ₃ is a main component for lowering the softening point. Its content is 73 to 81.4%, preferably 7 from 3 to 80.5%, more preferably 73-79%, more preferably less than 75 to 77%. When the content of Bi ₂ O ₃ is less than 73 %, the softening point of the glass becomes too high and it becomes difficult to seal at a temperature of 530 ° C. or lower. On the other hand, when the content of Bi ₂ O ₃ is more than 81.4%, the glass becomes thermally unstable, and the glass is easily devitrified at the time of melting or firing.

B ₂ O ₃ is a component that forms a glass network of bismuth glass and is an essential component. Its content is 2 to 12%, preferably 3 to 10%, more preferably 4 to 10%, still more preferably 5 to 9.6%. If the content of B ₂ O ₃ is less than 2%, the glass becomes thermally unstable, and the glass tends to devitrify during melting or firing. On the other hand, if the content of B ₂ O ₃ is more than 12%, the viscosity of the glass becomes too high and it becomes difficult to seal at a temperature of 530 ° C. or lower.

Al ₂ O ₃ is a component that improves the weather resistance of glass. Its content is 0-5%, preferably 0-2%. If the content of Al ₂ O ₃ is more than 5%, the softening point of the glass becomes too high, and it becomes difficult to seal at a temperature of 530 ° C. or lower.

ZnO is a component that has an effect of suppressing devitrification of the glass during melting or firing. The content is 1 to 9.9% , preferably 2 to 9.9 %, more preferably 3 to 9%, and still more preferably 4 to 8%. When the content of ZnO is less than 1%, it becomes difficult to obtain an effect of suppressing devitrification of the glass during melting or firing. When the content of ZnO is 9.9 % or more, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, and as a result, the glass is easily devitrified.

  BaO, SrO, MgO, and CaO are components that have an effect of suppressing devitrification of the glass during melting or firing. These components can be contained in the glass composition up to 15% in total. When the total amount of these components is more than 15%, the softening point of the glass becomes too high and it becomes difficult to seal at a temperature of 530 ° C. or lower.

  The content of BaO is preferably 0 to 10%, more preferably 0 to 8%, and still more preferably 1 to 7%. When the content of BaO is more than 10%, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, and as a result, the glass is easily devitrified. Further, from the viewpoint of improving the thermal stability of the glass, the BaO content is preferably 1% or more (desirably 3% or more).

  Each content of SrO, MgO, and CaO is preferably 0 to 5%, and more preferably 0 to 2%. When the content of each component is more than 5%, the glass is easily devitrified or phase-separated.

  CuO has an effect of suppressing devitrification of the glass at the time of melting or firing, and can be added up to 5%. If the content of CuO is more than 5%, the glass tends to devitrify and the fluidity of the glass tends to be impaired. Further, from the viewpoint of improving the thermal stability of the glass, it is preferable to add a small amount of CuO. Specifically, the content of CuO is 0.01% or more (desirably 0.1% or more, more desirably 1% or more).

Fe ₂ O ₃ has an effect of suppressing devitrification of the glass at the time of melting or firing, and its content is preferably 0 to 3%, more preferably 0 to 2%. When the content of Fe ₂ O ₃ is more than 3%, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, and as a result, the glass is easily devitrified. From the viewpoint of improving the thermal stability of the glass, it is preferable to add a small amount of Fe ₂ O _3. Specifically, the content of Fe ₂ O ₃ is 0.01% or more (desirably 0.1%). % Or more).

CeO ₂ has an effect of suppressing devitrification of the glass at the time of melting or firing, and its content is 0 to 5%, preferably 0 to 2%, more preferably 0 to 1%. When the content of CeO ₂ is more than 5%, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, and the glass is easily devitrified. Further, from the viewpoint of improving the thermal stability of the glass, it is preferable to add a small amount of CeO _2. Specifically, the CeO ₂ content is preferably 0.01% or more.

Sb ₂ O ₃ is a component for suppressing the devitrification of the glass, and its content is 0 to 5%, preferably 0 to 2%, more preferably 0.1 to 1%. Sb ₂ O ₃ has the effect of stabilizing the network structure of bismuth-based glass. If Sb ₂ O ₃ is appropriately added to the bismuth-based glass, the content of Bi ₂ O ₃ is large, for example, Bi ₂ O. _{Even if} the content of ₃ is 76% or more, the thermal stability of the glass is hardly lowered. However, when the content of Sb ₂ O ₃ is more than 5%, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, and as a result, the glass is easily devitrified. From the viewpoint of improving the thermal stability of the glass, it is preferable to add a small amount of Sb ₂ O _3. Specifically, the Sb ₂ O ₃ content is 0.1% or more (preferably 0.4%). % Or more).

  The bismuth-based glass powder can contain, for example, the following components in addition to the above components in the glass composition in a total amount of 20%, preferably 10% in addition to the above components.

SiO ₂ is a component that improves the weather resistance of glass. Its content is 0 to 10%, preferably 0 to 3%. When the content of SiO ₂ is more than 10%, the softening point of the glass becomes too high, and it becomes difficult to seal at a temperature of 530 ° C. or lower.

WO ₃ is a component for suppressing the devitrification of the glass, and its content is preferably 0 to 10%, more preferably 0 to 2%. In bismuth-based glasses, it is necessary to increase the content of Bi ₂ O _{3 in} order to lower the softening point of the glass. However, if the content of Bi ₂ O ₃ increases, crystals tend to precipitate from the glass during firing. Therefore, the fluidity of the sealing material tends to be hindered. In particular, when the content of Bi ₂ O ₃ is large, for example, when the content of Bi ₂ O ₃ is 76% or more, the tendency becomes remarkable. However, if WO ₃ is appropriately added to the bismuth-based glass, the thermal stability of the glass is hardly lowered even if the Bi ₂ O ₃ content is 76% or more. However, if the content of WO ₃ is more than 10%, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, and as a result, the glass is easily devitrified.

In ₂ O ₃ and Ga ₂ O ₃ are not essential components, but are components for suppressing the devitrification of the glass. The total content is preferably 0 to 5%, more preferably 0 to 3%. . _{In 2 O 3, Ga 2 O} 3 has the effect of stabilizing the network structure of the bismuth glass, the bismuth glass, by adding _{In 2 O 3, Ga 2 O} 3 as appropriate, Bi ₂ O ₃ when the content of large, even for example the content of Bi ₂ O ₃ is more than 76%, thermal stability of the glass is hardly lowered. However, if the content of In ₂ O ₃ and Ga ₂ O ₃ is more than 5% in total, the balance in the glass composition is lost, and conversely, the thermal stability of the glass is impaired, resulting in loss of the glass. It becomes easy to see through. In addition, the content of In ₂ O ₃ is more preferably 0 to 1%, and the content of Ga ₂ O ₃ is more preferably 0 to 0.5%.

The Li, Na, K, and Cs oxides are components that lower the softening point of the glass. However, since they have an action of promoting devitrification of the glass during melting, the total amount is preferably 2% or less.

P ₂ O ₅ is a component that suppresses the devitrification of the glass at the time of melting. However, if the amount added is more than 1%, it is not preferable because the glass tends to phase-separate at the time of melting.

MoO ₃ , La ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ are components that suppress the phase separation of the glass at the time of melting. However, if the total amount of these is more than 3%, the softening point of the glass is high. It becomes too difficult to fire at a temperature of 530 ° C. or lower.

  Moreover, even if it is another component, it can add to a glass composition to 15% (preferably 5%) in the range which does not impair the characteristic of glass.

In the bismuth-based glass according to the present invention, it is preferable to regulate the value of the mass ratio Bi ₂ O ₃ / B ₂ O ₃ in the glass composition as follows. The mass ratio Bi ₂ O ₃ / B ₂ O ₃ is a component ratio that greatly affects the thermal stability and softening characteristics of the bismuth-based glass. In addition, in Bismuth-based glass, Bi ₂ O ₃ and B ₂ O ₃ , when combined, have a large content in the glass composition and are the main components that form the glass skeleton. It is thought that it is a component that determines. Bi ₂ O ₃ is a component that lowers the softening point of the glass, and as the content of Bi ₂ O ₃ increases with respect to B ₂ O ₃ , the softening point of the glass tends to decrease. On the other hand, the thermal stability of the glass becomes poor, and devitrification tends to occur. _Further, B 2 _{O 3} is a component for improving the thermal stability of the glass, as to _Bi 2 _{O 3} becomes large content of _B 2 _{O 3,} it improves the thermal stability of the glass. On the other hand, the softening point of glass tends to increase. Therefore, Bi ₂ O ₃ and B ₂ O ₃ have a trade-off characteristic, and if the mass ratio Bi ₂ O ₃ / B ₂ O ₃ is regulated within a predetermined range, the glass softening point and heat It is possible to optimize the mechanical stability, and it is easy to prevent the sealing material from being drawn into the apparatus in the vacuum exhaust process while ensuring the fluidity of the sealing material in the secondary firing process. Mass ratio _{Bi 2 O 3 / B 2 O} 3 is 8.1 to 1 1, the good Mashiku 8.1 to 10. 8, more preferably 8.1 to 10.2, particularly preferably 8.1 to 9. Nine . If the value of the mass ratio Bi ₂ O ₃ / B ₂ O ₃ is larger than 11, the softening point of the glass is lowered, but the glass is easily devitrified in the primary firing process, or the sealing material is used in the vacuum exhaust process. It becomes easy to be drawn inside.

The bismuth glass having the above glass composition is an amorphous glass exhibiting good fluidity at a temperature of 530 ° C. or less, and has a thermal expansion coefficient of about 100 to 120 × 10 ⁻⁷ / ° C. at 30 to 300 ° C. It is.

  The sealing material of the present invention contains 2.1 to 45% by volume of zirconium phosphate, preferably 3 to 25% by volume, more preferably 4 to 18% by volume, and further preferably 5 to 15% by volume as a refractory filler powder. %contains. Zirconium phosphate is a component that has a remarkable effect in maintaining the shape of the sealing site after firing. When the amount of zirconium phosphate is less than 2.1% by volume, the shape maintaining effect is poor, and the sealing material is easily drawn into the apparatus in the vacuum exhaust process. On the other hand, when the amount of zirconium phosphate is more than 45% by volume, the sealing material becomes difficult to flow, and it becomes difficult to secure desired fluidity in the primary firing step and the secondary firing step.

In the sealing material of the present invention, the 10% particle diameter D ₁₀ of zirconium phosphate is preferably 1 to 6 μm, more preferably 2 to 5 μm. A 10% particle size D ₁₀ of zirconium phosphate 1μm smaller, since the zirconium phosphate during firing tends penetration in glass, the sealing material is less likely to flow, a desired in first firing step and the secondary sintering step It becomes difficult to secure fluidity. On the other hand, the 10% particle size D ₁₀ of zirconium phosphate is greater than 6 [mu] m, the shape maintaining effect of zirconium phosphate is poor, the sealing material is easily pulled into the apparatus by the vacuum exhaust process.

In the sealing material of the present invention, the average particle diameter D ₅₀ of zirconium phosphate is preferably 6 to 40 μm, and more preferably 10 to 30 μm. When the average particle diameter D _{50 of} zirconium phosphate is smaller than 6 μm, the zirconium phosphate is easily dissolved in the glass at the time of firing, so that the sealing material becomes difficult to flow, and the desired flow in the primary firing step and the secondary firing step. It becomes difficult to secure sex. On the other hand, when the average particle diameter D ₅₀ of zirconium phosphate is larger than 40 μm, the shape maintaining effect of zirconium phosphate is poor, and the sealing material is easily drawn into the apparatus in the vacuum exhaust process.

In the sealing material of the present invention, the 90% particle diameter D ₉₀ of zirconium phosphate is preferably 15 to 80 μm, more preferably 20 to 70 μm, still more preferably 25 to 60 μm. If the 90% particle diameter D _{90 of} zirconium phosphate is smaller than 15 μm, the zirconium phosphate is likely to be dissolved in the glass at the time of firing, so that the sealing material is difficult to flow and is desired in the primary firing step and the secondary firing step. It becomes difficult to secure fluidity. On the other hand, when the 90% particle diameter D ₉₀ of zirconium phosphate is larger than 80 μm, the shape maintaining effect of zirconium phosphate is poor, and the sealing material is easily drawn into the apparatus in the vacuum exhaust process.

In the sealing material of the present invention, the specific surface area of the zirconium phosphate is preferably ^{0.1~3m 2 / g, 0.5~2m 2 /} g is more preferable. Here, the “specific surface area” in the present invention refers to a value measured by a gas adsorption BET method, and a value measured by a method based on JIS R1626. When the specific surface area of zirconium phosphate is less than 0.1 m ² / g, the shape maintaining effect of zirconium phosphate is poor, and the sealing material is easily drawn into the apparatus in the vacuum exhaust process. On the other hand, if the specific surface area of zirconium phosphate is larger than 3 m ² / g, zirconium phosphate is likely to be dissolved in the glass at the time of firing, so the fluidity of the sealing material is deteriorated and sealing is performed at a temperature of 530 ° C. or lower. It becomes difficult.

  As refractory filler powder, in addition to zirconium phosphate, willemite, zircon, tin oxide, cordierite, β-eucryptite, aluminum titanate, celsian, quartz glass, mullite, β-spodumene, alumina, silica-based ceramics, etc. A variety of materials can be used. These refractory filler powders are preferable because they have a low thermal expansion coefficient and high mechanical strength. In particular, as the refractory filler powder, willemite and cordierite are more preferable because they are less likely to devitrify bismuth-based glass, have low expansion, and are excellent in mechanical strength.

  In the sealing material of the present invention, the mixing ratio of the glass powder and the refractory filler powder is preferably 40 to 90% by volume of glass powder and 10 to 60% by volume of refractory filler powder, 50 to 75% by volume of glass powder, and refractory. The filler powder is more preferably 25 to 50% by volume. The reason for defining the ratio of the two in this way is that when the refractory filler powder is less than 10% by volume, it becomes difficult to match the thermal expansion coefficient of the sealing material to the thermal expansion coefficient of the sealed object such as a glass substrate, and the residual The sealed part and the sealed object such as the glass substrate are easily broken by the stress. On the other hand, when the amount of the refractory filler powder is more than 60% by volume, the content of the glass powder is relatively reduced, so that the fluidity of the sealing material is deteriorated, and the desired fluidity is obtained in the primary firing process and the secondary firing process. It becomes difficult to secure.

In the sealing material of the present invention, the density of the sealing material is preferably 7.0 g / cm ³ or less, more preferably 6.4 g / cm ³ or less, and still more preferably 6.1 g / cm ³ or less. When the density of the sealing material is larger than 7.0 g / cm ³ , the weight per fixed volume for forming the sealing site is excessively increased, and the raw material cost of the sealing material may increase. In order to reduce the density of the sealing material, a low-density refractory filler may be used, or the Bi ₂ O ₃ content in the glass composition of the bismuth-based glass powder may be reduced. The density refers to a value measured by a known Archimedes method.

In the sealing material of the present invention, the softening point of the sealing material is preferably 530 ° C. or less, more preferably 500 ° C. or less, and further preferably 465 ° C. or less. If the softening point of the sealing material is higher than 530 ° C., the sealing material becomes difficult to flow at a temperature of 530 ° C. or less, and a desired sealing strength may not be ensured. In order to lower the softening point of the sealing material, the Bi ₂ O ₃ content in the glass composition of the bismuth-based glass powder may be increased or the B ₂ O ₃ content may be reduced. The softening point indicates a value measured with a DTA apparatus. DTA is performed in the atmosphere, and the measurement is started from a temperature rising rate of 10 ° C./min and room temperature.

In the sealing material of the present invention, the thermal expansion coefficient of the sealing material is preferably 62 to 78 × 10 ⁻⁷ / ° C. when the material to be sealed is a high strain point glass substrate (about 83 × 10 ⁻⁷ / ° C.). 63-76 × 10 ⁻⁷ / ° C. is more preferable. In the case of a soda glass substrate (about 90 × 10 ⁻⁷ / ° C.), 62 to 85 × 10 ⁻⁷ / ° C. is preferable, and 69 to 76 × 10 ⁻⁷ / ° C. is more preferable. When the material to be sealed is an alumina substrate (about 78 × 10 ⁻⁷ / ° C.), 60 to 76 × 10 ⁻⁷ / ° C. is preferable, and 62 to 74 × 10 ⁻⁷ / ° C. is more preferable. If it does in this way, the distortion concerning a sealing part after sealing can be made into a compression (compression) side, and destruction of a sealing part can be prevented. Further, if the thermal expansion coefficient of the sealing material is outside the above range, unreasonable stress tends to remain at the sealing portion, and airtight defects are likely to occur in the flat display device or the like. In addition, a thermal expansion coefficient points out the value measured with the push rod type | formula thermal expansion coefficient measuring apparatus, and a measurement temperature range shall be 30-300 degreeC.

  The sealing material of the present invention is preferably amorphous. This makes it difficult for crystals to precipitate on the surface of the glass at a temperature of 530 ° C. or lower, that is, it is difficult for the glass to devitrify before the glass flows, and it becomes easy to ensure the desired fluidity. Further, when the sealing material is amorphous, the reaction between the object to be sealed and the sealing material is promoted, so that the sealing strength is increased and it is easy to ensure the airtight reliability of the PDP.

The sealing material of the present invention does not exclude the embodiment containing PbO, but as described above, it is preferable that the sealing material does not substantially contain PbO for environmental reasons. In addition, when PbO is contained in the glass composition, Pb ²⁺ present in the glass diffuses, and the electrical insulation of the sealing material may be lowered.

  The sealing material may be used as a powder, but it is easy to handle when the sealing material and the vehicle are uniformly kneaded and used as a paste material. 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 material. Moreover, surfactant, a thickener, etc. can also be added as needed. The produced paste material is applied onto an object to be sealed such as a glass substrate 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 the viscosity of the paste material is easily secured and the thermal decomposability is good.

  The sealing material of the present invention is preferably used for sealing the front glass substrate and the rear glass substrate of the PDP. As described above, the sealing material of the present invention flows well at a temperature of 530 ° C. or lower, and even if the evacuation process is 450 ° C. to 500 ° C., the sealing material is not easily drawn into the apparatus. Suitable for this application.

  Although this specification has described the present invention centering on the PDP, the fluorescent display tube and the field emission display (hereinafter referred to as FED) also have a vacuum evacuation process in which the inside of the apparatus is evacuated. Similarly, if the temperature of the evacuation process can be increased, manufacturing efficiency and luminance characteristics can be improved. Needless to say, the FED includes various types of FEDs having various electron-emitting devices.

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

(Experimental example 1)
Tables 1 to 3 show examples of the present invention (sample Nos . 2 to 7 , 9 , 11 , and 13 to 15) and comparative examples (samples No. 1, 8 , and 17 to 19) of the present invention. Sample No. Reference numerals 10, 12, and 16 are reference examples.

First, a glass batch in which raw materials such as various oxides and carbonates were prepared so as to have the glass composition shown in the table was prepared, and this was put in a platinum crucible and melted at 1000 to 1200 ° C. for 2 hours. Next, the molten glass was formed into a thin piece with a water-cooled roller. Finally, the glass flakes were pulverized by a ball mill and passed through a sieve having an opening of 200 mesh to obtain glass powder samples having an average particle diameter D ₅₀ of 10 μm.

As the refractory filler powder, zirconium phosphate powder having an average particle diameter D ₅₀ of 20 μm (indicated as ZP in the table), willemite powder having an average particle diameter D ₅₀ of 8 μm (indicated in the table as WIL), average particle diameter D Cordierite powder ₅₀ (expressed as CDR in the table) and tin oxide powder (expressed as SnO _{2 in the} table) having an average particle diameter D ₅₀ of 8 μm were used.

  Using the above powder sample, Sample No. 1 to 19 were prepared, and the density, glass transition point, softening point, flow diameter, devitrification state, residual stress, and retractability were evaluated.

  The density was measured by the well-known Archimedes method.

  The glass transition point was measured with a push rod type thermal expansion coefficient measuring device.

  The softening point was measured with a DTA apparatus. The DTA measurement was started from room temperature in the atmosphere, and the heating rate was 10 ° C./min.

  The thermal expansion coefficient was measured with a push rod type thermal expansion coefficient measuring apparatus. The measurement temperature range was 30 to 300 ° C.

  The flow diameter was dry-pressed into a button shape having an outer diameter of 20 mm using a mold with a weight corresponding to the true specific gravity of the sealing material, and the button sample was subjected to a high strain point glass substrate (PP-made by Nippon Electric Glass Co., Ltd.). 8C), placed in an air-flow heat treatment furnace, heated in air at a rate of 10 ° C / min, held at 510 ° C for 20 minutes, and then brought to room temperature at a rate of 10 ° C / min. The temperature was lowered, and evaluation was performed by measuring the diameter of the fired button obtained. In addition, if a flow diameter is 20 mm or more, it means that fluidity | liquidity is favorable.

  The devitrification state was evaluated as follows. First, after each sample and vehicle (acrylic resin-containing α-terpineol) were uniformly kneaded with a three-roll mill and formed into a paste, the end of a high strain point glass substrate (PP-8C manufactured by Nippon Electric Glass Co., Ltd.) Was applied in a linear shape (length 40 × width 3 × 1.5 mm thickness) and dried in a drying oven at 150 ° C. for 10 minutes. Next, the temperature was raised from room temperature at 10 ° C./minute, the substrate was baked at 510 ° C. for 20 minutes, and then the temperature was lowered to room temperature at 10 ° C./minute. Finally, the surface of the fired body obtained was observed with an optical microscope (50 times), and “◯” was given when no crystal was observed on the surface, and “X” when crystal was found on the surface. did.

  Residual stress was evaluated as follows. First, a powder having a weight corresponding to the true specific gravity of the sealing material is dry-pressed into a button shape having an outer diameter of 20 mm using a mold, and the button sample is placed on a high strain point glass substrate (PP-8C manufactured by Nippon Electric Glass Co., Ltd.). Placed. Next, this was put into an air-flow type heat treatment furnace, heated in air at a rate of 10 ° C./min, held at 510 ° C. for 20 minutes, and then cooled to room temperature at a rate of 10 ° C./min. Finally, the case where no cracks occurred in the obtained glass substrate immediately below the fired button was indicated as “◯”, and the case where cracks occurred was indicated as “x”.

The pullability was evaluated as follows. First, each sample and vehicle (acrylic resin-containing α-terpineol) were uniformly kneaded with a three-roll mill and made into a paste, and then a 100 × 100 × 1.8 mmt high strain point glass substrate having 5 mmφ exhaust holes. It was applied linearly (length 40 × width 3 × 1.5 mm thickness) to the outer periphery of PP-8C (Nippon Electric Glass Co., Ltd.) and dried in a drying oven at 150 ° C. for 10 minutes. Next, after superposing a 100 × 100 × 1.8 mmt high strain point glass substrate (PP-8C manufactured by Nippon Electric Glass Co., Ltd.) on the glaze surface, pressurizing with a clip or the like, from room temperature to 10 ° C./min. After heating up and baking at 510 ° C. for 20 minutes, the temperature was lowered to room temperature at 10 ° C./min. And the inside of the obtained glass container was evacuated with the vacuum pump through the exhaust hole. The evacuation was performed at 480 ° C. for 40 minutes, and the inside of the apparatus was adjusted to 10 ⁻⁶ Torr. After that, the inside of the glass container is observed, “○” indicates that there is no through hole (airtight leak) due to a part of the sealing part being drawn into the apparatus, and the through hole is generated by being drawn in. Was evaluated as “×”.

  Sample No. 2-7, 9-16, the glass composition range of the glass powder is regulated within a predetermined range, and since a predetermined amount of zirconium phosphate is contained in the sealing material, the flow diameter, devitrification state, Residual stress and drawability were evaluated well.

Sample No. Since No. 1 did not contain zirconium phosphate in the sealing material, the evaluation of retractability was poor. Sample No. In No. 8, the content of zirconium phosphate was excessive, and the evaluation of fluidity and devitrification state was poor. Sample No. In No. 17, the content of Bi ₂ O ₃ in the glass powder was too small, and the evaluation of fluidity and residual stress was poor. Sample No. No. 18 was poor in evaluation of the flow diameter and devitrification because the content of Bi ₂ O ₃ in the glass powder was excessive. Sample No. In No. 19, since the content of ZnO in the glass powder was excessive, the evaluation of flow diameter, devitrification, and residual stress was poor.

(Experimental example 2)
The following experiment was conducted to investigate the influence of the particle size distribution of zirconium phosphate. Table 4 shows Examples (Sample Nos. 20 to 24) of the present invention.

First, a glass batch in which raw materials such as various oxides and carbonates were prepared so as to have the glass composition shown in Table 4 was prepared, and this was put in a platinum crucible and melted at 1000 to 1200 ° C. for 2 hours. Next, the molten glass was formed into a thin piece with a water-cooled roller. Finally, the glass flakes were pulverized by a ball mill and passed through a sieve having an opening of 200 mesh to obtain glass powder samples having an average particle diameter D ₅₀ of 10 μm.

Zirconium phosphate powder (denoted as ZP in the table) was used as the refractory filler powder. The particle size distribution of the zirconium phosphate powder was adjusted by appropriately adjusting the pulverization conditions and classification conditions of the zirconium phosphate sintered body. The average particle diameter D ₅₀ was used 8μm willemite powder (denoted WIL in the tables).

  Using the above powder sample, Sample No. 20-24 were produced and the flow diameter, the devitrification state, the residual stress, and the drawing-in property were evaluated. The evaluation method of the flow diameter, devitrification state, residual stress, and retractability is the same as the evaluation method described above.

  Sample No. 20 to 24, the glass composition range of the glass powder is regulated within a predetermined range, the sealing material contains a predetermined amount of zirconium phosphate, and the particle size distribution of the zirconium phosphate is within the predetermined range. The evaluation of diameter, devitrification state, residual stress, and retractability was good.

The sealing material of the present invention is suitable for sealing PDP, FED, and fluorescent display tube. In addition, the sealing material of the present invention can be used for sealing various ceramic packages such as an organic electroluminescence display, an inorganic electroluminescence display, and an IC ceramic package, and various metal packages such as a spherical lens cap component.

Claims (7)

In a sealing material containing bismuth glass powder and refractory filler powder,
The bismuth-based glass powder has a glass composition represented by mass% in terms of the following oxide, Bi ₂ O ₃ 73 to 81.4%, B ₂ O ₃ 2 to 12%, Al ₂ O ₃ 0 to 5%, ZnO _{1~9.9%, BaO 0~10%, 0~5} % CuO, Fe 2 O 3 0~3%, CeO 2 0~5%, Sb 2 O 3 containing 0 to 5%, the mass ratio Bi ₂ A sealing material having a value of O ₃ / B ₂ O ₃ of 8.1 to 11 and containing 2.1 to 45% by volume of zirconium phosphate as a refractory filler powder. Sealing material according to claim 1, wherein the average particle diameter D ₅₀ of zirconium phosphate characterized in that it is a 6～40Myuemu. 3. The sealing material according to claim 1, wherein the zirconium phosphate has a 10% particle diameter D ₁₀ of 1 to 6 μm and / or a 90% particle diameter D ₉₀ of 15 to ₈₀ μm. The sealing according to any one of claims 1 to 3, wherein the bismuth-based glass powder has a glass composition having a mass ratio Bi ₂ O ₃ / B ₂ O ₃ of 8.1 to 10.2. Landing material.   The sealing material according to claim 1, which is non-crystalline.   The sealing material according to any one of claims 1 to 5, which does not substantially contain PbO.   The sealing material according to any one of 1 to 6, which is used for sealing a front glass substrate and a back glass substrate of a plasma display panel.