JP2012046358A - Sealing glass tablet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass tablet containing a SnO-PO-based glass which can well seal a metallic material or the like in a middle temperature region of 450 to 800°C even in a non-oxidative atmosphere (reduced atmosphere, inert atmosphere or the like) to secure air tightness of a sealed part over a long period.SOLUTION: In the sealing glass tablet containing at least a SnO-PO-based glass, the glass composition of the SnO-PO-based glass contains, in mol%, 15 to 30% (excluding 30%) of SnO, 20 to 40% of PO, 5 to 20% (excluding 5%) of WOand 6 to 30% (excluding 30%) of ZnO, wherein the molecular ratio of SnO/ZnO is ≥1 and ≤4.5.

Description

  TECHNICAL FIELD The present invention relates to a sealing glass tablet, and particularly to a sealing glass tablet capable of satisfactorily sealing a metal material in an intermediate temperature range of 450 to 800 ° C. In the following description, “sealing” includes the concept of “sealing”.

Conventionally, various glass tablets for sealing have been used. For example, sealing glass tablets made of PbO—B ₂ O ₃ glass containing a large amount of lead, sealing glass tablets made of SiO ₂ —B ₂ O ₃ glass, and the like are used for high temperature regions. Moreover, the glass tablet for sealing is widely used for metal packages, such as a metal package for airtight terminals, a conductor holding body, an exhaust pipe integrated with a glass tablet, and the like (for example, see Patent Documents 1 to 5).

Furthermore, sealing glass tablets including SnO—P ₂ O ₅ glass, Bi ₂ O ₃ —B ₂ O ₃ glass, and the like have been proposed as sealing glass tablets for low temperature regions (for example, patent documents). 6-8).

JP 2003-158209 A JP 2005-353291 A Japanese Patent Laid-Open No. 6-29049 JP 2005-294390 A JP 2001-253724 A JP 2004-182584 A JP 2006-169018 A JP 2009-46379 A JP 2008-30972 A

  By the way, the sealing of a metal material may be performed in the middle temperature range of 450-800 degreeC using a glass tablet. For example, in the case of sealing the mouth of a sheathed heater, a glass tablet is usually used, and sealing is performed at an intermediate temperature range of 450 to 800 ° C. The metal material is usually sealed in a non-oxidizing atmosphere in order to prevent the metal material from being oxidized.

However, using a glass tablet containing the above _SnO-P 2 _{O 5} based glass, when sealing the metal material in the temperature range within 450 to 800 ° C., to the low melting point of the _SnO-P 2 _{O 5} based glass As a result, a large number of bubbles are generated in the glass tablet, and as a result, leakage from the bubbles may occur due to long-term use, and the airtightness of the sealed portion may be impaired, or the sealed portion may be peeled off. Get higher. In addition, the glass tablet may flow too much at the time of sealing, and there is a risk of contaminating parts other than the sealing part.

In recent years, Bi ₂ O ₃ —B ₂ O ₃ glass has been used as a lead-free substitute for PbO—B ₂ O ₃ glass, but Bi ₂ O ₃ —B ₂ O ₃ glass is non- There is a problem that the bismuth component is easily reduced by firing in an oxidizing atmosphere, and it is difficult to ensure a stable state (see, for example, Patent Document 9).

  Therefore, the present invention creates a glass tablet that can satisfactorily seal a metal material or the like in a middle temperature range of 450 to 800 ° C. even in a non-oxidizing atmosphere (depressurized atmosphere, inert atmosphere, etc.) It is a technical subject to ensure the airtightness of the sealed portion over a long period of time.

The present inventors have revealed that various experiments, while adopting the SnO-P ₂ O ₅ based glass as the glass material of the glass tablet, to strictly regulate the glass composition range of the SnO-P ₂ O ₅ based glass Thus, even in a non-oxidizing atmosphere, it has been found that a metal material or the like can be satisfactorily sealed at an intermediate temperature range of 450 to 800 ° C., and is proposed as the present invention. That is, the sealing glass tablet of the present invention is a sealing glass tablet containing at least SnO—P ₂ O ₅ glass, SnO—P ₂ O ₅ glass is a glass composition in terms of mol%, SnO 15 to 15 30% (not inclusive of _{30%), P 2 O 5} 20~40%, WO 3 5~20% ( not inclusive of 5%), ZnO 6 to 30% (not inclusive of 30% ) And the molar ratio SnO / ZnO is 1 or more and 4.5 or less.

Sealing glass tablet of the present invention, the glass composition range of the SnO-P ₂ O ₅ based glass as described above is restricted. If it does in this way, a metal material etc. can be satisfactorily sealed in the middle temperature range of 450-800 ° C. That is, in this way, while appropriately flowing in the middle temperature range of 450 to 800 ° C., it is possible to prevent the occurrence of bubbles in the glass tablet and optimize the reactivity of the glass tablet and the metal material. Thus, the sealing strength can be increased. Further, even when sealing in a non-oxidizing atmosphere, it is possible to prevent the glass tablet from devitrifying and deteriorating, and thus it is possible to ensure the airtightness of the sealed portion over a long period of time. The glass tablet for sealing of the present invention is suitable for sealing metal materials, but is not limited to sealing metal materials, and can be used for sealing materials other than metal materials. is there.

  2ndly, the glass tablet for sealing of this invention is characterized by the glass transition point being 370-500 degreeC (however, 370 degreeC is not included). The glass transition point can be measured with a push rod thermal dilatometer or the like.

  Thirdly, the sealing glass tablet of the present invention is characterized by substantially not containing PbO. In this way, environmental demands in recent years can be satisfied. Here, “substantially does not contain PbO” refers to a case where the content of PbO in the glass tablet is 1000 ppm (mass) or less.

  4thly, the glass tablet for sealing of this invention is characterized by including 0-55 volume% of fireproof fillers further. If it does in this way, it will become easy to match the thermal expansion coefficient of a glass tablet with the thermal expansion coefficient of various metal materials.

Fifth, the sealing glass tablet of the present invention is characterized by being used for sealing in a reduced pressure atmosphere of 1.0 × 10 ⁻² Torr or less.

  Sixth, the sealing glass tablet of the present invention is used for sealing in an atmosphere having an oxygen concentration of 5% by volume or less.

  Seventh, the sealing glass tablet of the present invention is characterized in that all or part of the sealing object is a metal material. That is, the glass tablet for sealing of the present invention is suitable for sealing between metal materials, sealing between a metal material and a glass material, sealing between a metal material and a ceramic material, and the like.

It is explanatory drawing for demonstrating the embodiment of the glass tablet for sealing of this invention.

In the sealing glass tablet of the present invention, illustrating the reasons for limiting the glass composition range of the SnO-P ₂ O ₅ based glass below. In addition, in description of the containing range of each component,% display points out mol%.

  SnO is a component that lowers the melting point of glass, and its content is 15 to 30% (however, not including 30%), preferably 20 to 28%. If the content of SnO is less than 15%, the viscosity of the glass tablet becomes too high, and the fluidity of the glass tablet tends to decrease in the middle temperature range. In addition, since the fluidity | liquidity of a glass tablet improves in content of SnO content in 20% or more, it becomes easy to ensure high airtightness. On the other hand, if the SnO content is 30% or more, the glass tablet softens at a low temperature, and thus the glass tablet flows too much at the time of sealing, making it difficult to use in the middle temperature range.

P ₂ O ₅ is a glass-forming oxide, and its content is 20 to 40%, preferably 25 to 35%. If the content of P ₂ O ₅ is less than 20%, the glass becomes unstable. On the other hand, when the content of P ₂ O ₅ is more than 40%, the moisture resistance is lowered. Incidentally, when the content of P ₂ O ₅ is more than 25%, the glass is more stable, if 35% or less, it is possible to improve the weather resistance of the glass tablet.

WO ₃ is an essential component of the present invention, and is a component that optimizes the reactivity with the metal material and increases the sealing strength and air tightness. Further, when WO ₃ is added, the weather resistance is improved, so that the long-term reliability of the sealed portion can be improved. The content of WO ₃ is 5 to 20% (not including 5%), preferably 10 to 15%. When the content of WO ₃ is 5% or less, it is impossible to obtain the above effect. On the other hand, when the content of WO ₃ is more than 20%, the phase separation tendency becomes strong at the time of melting, and the glass becomes unstable. Incidentally, the content of WO ₃ is 10 to 15% the flowability of the glass tablet is improved in the mid temperature range. Further, when the content of WO ₃ is more than 5%, the above effect can be enjoyed. However, when sealing in an air atmosphere, the glass tablet is easily devitrified at the time of sealing. For this reason, it is preferable to use the glass tablet for sealing of the present invention for sealing in a reduced-pressure atmosphere of 1.0 × 10 ⁻² Torr or lower or in an atmosphere having an oxygen concentration of 5% by volume or lower.

  ZnO is an intermediate oxide and a component having a large effect of stabilizing the glass, and its content is 6 to 30% (excluding 30%), preferably 6 to 28%. Considering the overall glass stability (devitrification resistance, phase separation, etc.), the ZnO content is preferably 8% or more. However, when the ZnO content is 30% or more, the component balance of the glass composition is impaired, and devitrification is likely to occur on the surface of the glass tablet during sealing. If the ZnO content is 28% or less, the stability of the glass is improved in the middle temperature range.

  The molar ratio SnO / ZnO is 1 or more and 4.5 or less, preferably 1 or more and 4 or less. When the molar ratio SnO / ZnO is smaller than 1, the glass tends to be unstable. On the other hand, when the molar ratio SnO / ZnO is larger than 4.5, the glass tablet flows too much at the time of sealing, and it becomes difficult to seal the metal material, and bubbles are easily generated in the glass tablet.

  The following components can be added as optional components.

  MgO is a network-modifying oxide and a component that stabilizes the glass. The content of MgO is preferably 0 to 20%, particularly preferably 0 to 5%. If the content of MgO is more than 20%, devitrification tends to occur on the surface of the glass tablet during sealing.

SiO ₂ is a glass-forming oxide and a component that suppresses devitrification of the glass, and its content is preferably 0 to 15%, particularly preferably 0 to 8%. If the content of SiO ₂ is more than 15%, the viscosity of the glass tablet becomes too high, and the fluidity of the glass tablet tends to decrease in the middle temperature range.

B ₂ O ₃ is a glass-forming oxide and a component that stabilizes the glass, and its content is 0 to 25%. When the content of B ₂ O ₃ is more than 25%, the viscosity of the glass tablet becomes too high, and the fluidity of the glass tablet is remarkably lowered at the time of sealing, which may impair the airtightness of the sealed part. . In particular, in the SnO—P ₂ O ₅ glass according to the present invention, when the content of B ₂ O ₃ is more than 25%, the glass is likely to be phase-separated. B ₂ O ₃ tends to increase the viscosity of the glass tablet. For this reason, when it is desired to greatly reduce the softening temperature, it is preferable that B ₂ O ₃ is not substantially contained, that is, 0.1% or less.

Al ₂ O ₃ is an intermediate oxide, a component that stabilizes the glass, and a component that further reduces the thermal expansion coefficient. The content of Al ₂ O ₃ is preferably 0 to 10%, and particularly preferably 0.5 to 5% in consideration of the thermal stability, thermal expansion coefficient, fluidity and the like of the glass tablet. When the content of Al ₂ O ₃ is more than 10%, the viscosity of the glass tablet is too high, the fluidity of the glass tablet is liable to decrease at medium temperature range.

R ₂ O (R is any one of Li, Na, K, and Cs) is not an essential component, but when at least one of R ₂ O components is added, the sealing strength with a metal material such as stainless steel is increased. improves. The content of R ₂ O is preferably 0 to 20%, particularly preferably 0.1 to 10%. When the content of R 2 _O is more than 20%, the glass tablet is liable to be devitrified during sealing. Of the R ₂ O components, Li ₂ O has a great effect of increasing the sealing strength with the metal material.

The lanthanoid oxide is a network-modified oxide, and its content is preferably 0 to 25%, 0.1 to 20%, particularly preferably 0.5 to 15%. When the content of the lanthanoid oxide is more than 25%, the viscosity of the glass tablet becomes too high, and the fluidity of the glass tablet tends to be lowered in the middle temperature range. As the lanthanoid oxide, La ₂ O ₃ , CeO ₂ , Nd ₂ O ₃ or the like can be used. Moreover, if content of a lanthanoid oxide shall be 0.1% or more, the weather resistance of a glass tablet can be improved.

In addition to the lanthanoid oxide, the weather resistance can be further improved by adding a rare earth oxide such as Y ₂ O ₃ . The total content of rare earth oxides is preferably 0 to 5%.

Furthermore, in order to stabilize the glass, MoO ₃ , Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , CuO, MnO, In ₂ O ₃ , R′O (R ′ is any of Mg, Ca, Sr, and Ba). ) Etc. may be added up to 35% in total. In addition, when there is more content of these components than 35% in total, the component balance of a glass composition will be impaired, glass will become unstable on the contrary, and manufacture of a glass tablet will become difficult. In addition, if content of these components is 25% or less in total, glass will not become unstable easily.

The content of MoO ₃ is preferably 0 to 20%, particularly preferably 0 to 10%. When the content of MoO ₃ is more than 20%, too high viscosity of the glass tablets, glass tablet is hardly fluidized at medium temperature range.

The contents of Nb ₂ O ₅ , TiO ₂ , and ZrO ₂ are all preferably 0 to 15%, particularly preferably 0 to 10%. If these components are each more than 15%, the component balance of the glass composition is impaired, and conversely, the glass tends to be unstable.

  The content of CuO and MnO is preferably 0 to 10%, particularly preferably 0 to 5%. If each of these components is more than 10%, the component balance of the glass composition is impaired, and the glass tends to be unstable.

In ₂ O ₃ is a component that can be used for the purpose of obtaining high weather resistance when the cost is not taken into consideration. The content of In ₂ O ₃ is preferably 0 to 5%.

  The total content of R′O is preferably 0 to 15%, particularly preferably 0 to 5%. When the content of R'O is more than 15% in total, the component balance of the glass composition is impaired, and conversely, the glass tends to become unstable.

  In addition to the above components, other components can be added up to 5%, for example. In addition, as mentioned above, it is preferable that PbO is not included substantially from an environmental viewpoint.

The SnO—P ₂ O ₅ glass has a glass transition point of about 370 to 500 ° C., a deformation point of about 380 to 530 ° C., and a thermal expansion coefficient of about 60 × 10 ⁻⁷ to 30 to 300 ° C. 110 × 10 ⁻⁷ / ° C. In a reduced-pressure atmosphere of 1.0 × 10 ⁻² Torr or less, a metal material can be satisfactorily sealed in a temperature range of 500 to 800 ° C., and the residual oxygen concentration is 5 The metal material can be satisfactorily sealed in a temperature range of 450 to 650 ° C. in an atmosphere of volume% or less, for example, an inert atmosphere such as nitrogen or argon.

In the glass tablet for sealing of the present invention, the glass transition point is preferably 370 to 500 ° C (excluding 370 ° C), particularly preferably 400 to 450 ° C. When the glass transition point is less than 370 ° C., the glass tablet flows too much in the middle temperature range, and it becomes difficult to seal the metal material, and bubbles are easily generated in the glass tablet. On the other hand, if the glass transition point is higher than 500 ° C., the viscosity of the glass tablet becomes too high, and the fluidity of the glass tablet tends to decrease in the middle temperature range. Similarly, the glass transition point of the SnO—P ₂ O ₅ glass according to the present invention is also preferably within the above range.

In the glass tablet for sealing of the present invention, the yield point is preferably 380 to 530 ° C, particularly preferably 440 to 480 ° C. When the yield point is lower than 380 ° C., the glass tablet flows too much in the middle temperature range, and it becomes difficult to seal the metal material, and bubbles are easily generated in the glass tablet. On the other hand, when the yield point is higher than 530 ° C., the viscosity of the glass tablet becomes too high, and the fluidity of the glass tablet tends to decrease in the middle temperature range. Similarly, the yield point of the SnO—P ₂ O ₅ glass according to the present invention is also preferably within the above range. The yield point can be measured with a push rod thermal dilatometer or the like.

In the sealing glass tablet of the present invention, a thermal expansion coefficient in a temperature range of 30 to 300 ° C. is 30~110 × ^{10 -7} / ℃, particularly preferably 40~85 × ^{10 -7} / ℃. If it does in this way, since it becomes easy to match the thermal expansion coefficient of a metal material, the stress concerning a sealing part can be reduced. The thermal expansion coefficient in the temperature range of 30 to 300 ° C. can be measured with a push rod type thermal dilatometer or the like.

The glass tablet for sealing of the present invention can satisfactorily seal various metal materials. Moreover, the glass tablet for sealing of the present invention is sealed in a reduced pressure atmosphere of 1.0 × 10 ⁻² Torr or lower, or in an atmosphere having an oxygen concentration of 5% by volume or lower in order to prevent oxidation of the metal material during sealing. It is preferable to use for.

The glass tablet for sealing of the present invention may be combined and used by adding a refractory filler in order to adjust the thermal expansion coefficient. When mixing the refractory filler, the mixing amount is SnO—P ₂ O ₅ based glass 45 to 100% by volume, refractory filler 0 to 55% by volume, particularly SnO—P ₂ O ₅ based glass 50 to 99% by volume, 1-50 volume% of a refractory filler is preferable. When the content of the refractory filler is more than 55 vol%, the proportion of relatively SnO-P ₂ O ₅ based glass is reduced, the glass tablet is hardly flow.

Various materials can be used as the refractory filler, such as quartz, cordierite, zircon, tin oxide, niobium oxide, zirconium phosphate, willemite, and mullite. NbZr (PO ₄ ) ₃ series ceramics have good compatibility with SnO—P ₂ O ₅ series glasses because they contain phosphoric acid in their components. The NbZr (PO ₄ ) ₃ ceramic is preferably added with a small amount (for example, 2% by mass) of MgO as a sintering aid.

  In the sealing glass tablet of the present invention, the filling rate is 71% or more, preferably 75% or more, 80% or more, and particularly preferably 83% or more. If it does in this way, since a glass tablet becomes difficult to change a dimension at the time of sealing, ie, it becomes difficult to shrink | contract a glass tablet, the fluidity | liquidity of a glass tablet can improve and it can raise sealing strength. Here, the “filling rate” refers to a value of [(actual density of glass tablet) / (theoretical density of glass tablet)] × 100 (%). The measured density of the glass tablet can be measured by a known Archimedes method or the like. The theoretical density of the glass tablet can be calculated by calculation from the density and mixing ratio of each constituent material.

  The shape of the sealing glass tablet of the present invention is not limited, and shapes such as a ring shape, a cylindrical shape, a triangular prism, and a quadrangular prism are conceivable.

  Hereinafter, the manufacturing method of the glass tablet for sealing of this invention is explained in full detail.

First, a powdered SnO—P ₂ O ₅ glass (or composite powder) is granulated to produce granules for uniform filling during dry pressure molding and improvement of the compact density. Next, the obtained granules are filled into a mold and press-molded. Further, post-processing is performed as necessary. Thereafter, the obtained press-molded body is temporarily fired to decompose and volatilize the binder contained in the granules and to sinter the granules. Thus, the glass tablet for sealing of this invention can be produced. In addition, in order to raise the mechanical strength of a glass tablet, you may perform temporary baking in multiple times.

The SnO—P ₂ O ₅ glass according to the present invention can be produced as follows. First, after preparing a glass raw material so that it may become said glass composition, it fuse | melts at 850-1000 degreeC, and obtains molten glass. Although melting does not pose a problem even if it is performed in the atmosphere, care must be taken so that SnO in the glass composition is not oxidized to SnO ₂ during melting. Since the SnO in the glass composition is prevented from oxidizing to SnO _2, or melted in N _2, etc. to N ₂ bubbling in the molten glass, it is preferable to perform the melt in a non-oxidizing atmosphere. Subsequently, after forming the molten glass, the glass powder can be obtained by pulverization and classification.

The average particle size of the glass powder is preferably 15 μm or less. If it does in this way, it will become easy to adjust the particle size of a granule. Any method may be adopted as a method of processing SnO—P ₂ O ₅ glass into a desired particle size. For example, a ball mill, a stirring mill or the like may be employed. Further, either wet pulverization or dry pulverization may be used, and the determination may be made in consideration of the water resistance of SnO—P ₂ O ₅ glass.

As the binder added to the granules, it is preferable that the glass powders can be firmly bonded to each other and the decomposition end temperature is not higher than the glass transition point of the SnO—P ₂ O ₅ glass. When the decomposition end temperature of the binder is higher than the glass transition point of SnO—P ₂ O ₅ glass, it is not completely decomposed during pre-baking, and the residual residue is decomposed during sealing, which promotes foaming in the glass tablet. It becomes easy. Also, when using the crystalline _SnO-P 2 _{O 5} based glass, the decomposition end temperature of the binder is higher than the glass transition point of the _SnO-P 2 _{O 5} based glass, the residual residue (carbon), SnO-P There is also a possibility that the crystallization temperature of the ₂ O ₅ glass is unduly lowered. If the molecular weight of the binder is lowered, the decomposition end temperature is further lowered even with the same kind of binder.

  The amount of the binder in the granule is not particularly limited, but is preferably about 0.1 to 20 parts by mass, particularly about 0.3 to 10 parts by mass with respect to 100 parts by mass of the glass powder (or composite powder).

  As the binder, polyethylene carbonate, polyethylene glycol derivatives, polypropylene carbonate, and polymethylstyrene are suitable. These binders have a very low decomposition end temperature and can be completely decomposed and volatilized at the time of temporary firing. In addition, the granule using these binders has good pressure transmission, and a press-molded body having no intergranular pores can be obtained even at a relatively low molding pressure. Also, when the mold is released from the mold, the influence of the spring back is small because the frictional force between the press-molded body and the mold is small, and the surface distortion that causes cracks hardly occurs. Nitrocellulose can be used by strictly controlling the granule preparation conditions, although the binding force between the powder particles becomes poor compared to the above binder.

As a solvent for dissolving the binder, an organic solvent having a boiling point equal to or lower than the glass transition point of SnO—P ₂ O ₅ glass or distilled water can be used, and the water resistance of SnO—P ₂ O ₅ glass or binder What is necessary is just to select suitably in consideration of a characteristic. For example, when polyethylene carbonate is selected as the binder, N, N′-dimethylformamide, propylene carbonate, n-propyl acetate, n-butyl acetate, propionitrile, styrene, propylene carbonate, acetonitrile, dimethyl sulfoxide, N-methyl-2-pyrrolidone, ethyl methyl ketone, toluene, butanol, ethyl acetate, triethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate, m-xylene, dimethyl carbonate, Diethyl carbonate, ethylene glycols and the like are preferred. When a polyethylene glycol derivative is selected, polar solvents such as distilled water and N, N′-dimethylformamide are suitable as the solvent. When polymethylstyrene is selected, toluene or the like is suitable as the solvent. Incidentally, the use of solvents having a boiling point higher than the glass transition point of the SnO-P ₂ O ₅ based glass, may become foamed cause the glass tablet.

  When a binder and a solvent are added to glass powder (or composite powder) and granulated, granules can be produced. For granulation, glass powder (or composite powder), a slurry-like turbid liquid consisting of a binder and a solvent is spray dried and granulated (spray granulation method), glass powder (or composite powder) is stirred or vibrated. While adding a solvent and a binder to agglomerate and granulate (stirring granulation method, rolling granulation method), glass powder (or composite powder) is dispersed in an air stream, and the solvent and binder are sprayed therein. There are methods such as agglomeration and granulation (fluid granulation), which can be appropriately selected according to the purpose.

  Hereinafter, the granulation method will be described in detail by taking the case of using the spray granulation method as an example. First, a slurry-like turbid liquid is prepared. It is preferable that the addition amount of a binder is 0.1-20 mass parts with respect to 100 mass parts of glass powder (or composite powder), especially 0.3-10 mass parts. In particular, when polyethylene carbonate is used, 0.5 to 15 parts by mass, 0.3 to 10 parts by mass for polyethylene glycol derivatives, and 0.5 to 10 parts by mass for polymethylstyrene are desirable. If the amount of the binder added is too small, the bonding force between the powders becomes poor, making it difficult to obtain the desired granules. On the other hand, if the amount is too large, the radius of the granule tends to be excessive, and it becomes difficult to control the particle size of the granule. The addition amount of the binder is not limited to spray granulation but can be applied to other granulation methods.

  It is preferable to prepare so that the addition amount of a solvent may be 10-100 mass% with respect to 100 mass parts of glass powder (or composite powder). If the amount of the solvent is too small, rod-shaped granules are likely to be formed, and the mold filling rate of the granules becomes unstable. On the other hand, when the amount is too large, depressed granules are easily generated, and the mold filling rate of the granules becomes unstable as described above.

  Moreover, a plasticizer etc. can also be added before granulation so that a granule may be easily crushed at the time of subsequent press molding. If the granules are easily crushed during press molding, the powder packing density of the press-molded body is increased, and the mechanical strength of the glass tablet is easily improved.

  Subsequently, the slurry-like turbid liquid is supplied to a spray drying apparatus and granulated to obtain granules. As a spray drying method, a two-fluid nozzle method, a high-pressure nozzle method, a rotating disk method, or the like may be appropriately selected according to the purpose.

  The average particle size of the granules thus obtained is preferably in the range of 10 to 120 μm, particularly 40 to 80 μm. If the average particle size is too small, the desired fluidity (mold filling property) tends to decrease. Conversely, if it is too large, defects such as depressions are likely to occur in the granules. The average particle size of the granules can be adjusted by the amount of binder added. For example, when the addition amount of the binder is increased, the average particle size of the granules is increased.

A method for processing the granules into glass tablets is described below. First, the granules are put into a mold designed to have a predetermined size, and are dry press-molded into a ring shape, for example, to produce a press-molded body. Next, in a heat treatment furnace such as a belt furnace, the binder remaining in the press-molded body is decomposed and volatilized and pre-baked at a temperature about the softening point of SnO—P ₂ O ₅ glass. Incidentally, calcination, to prevent deterioration of the _SnO-P 2 O ₅ based glass, nitrogen, an inert atmosphere such as argon, it is particularly preferable to carry out in a nitrogen atmosphere.

The glass tablet for sealing of the present invention is preferably used for sealing in a reduced pressure atmosphere of 1.0 × 10 ⁻² Torr or less. If the reduced pressure atmosphere is 1.0 × 10 ⁻² Torr or less, the metal material can be prevented from being oxidized. Further, in order to reliably prevent oxidation of the metal material, it is further preferable to seal in a reduced pressure atmosphere of 1.0 × 10 ⁻³ Torr or less. On the other hand, when the pressure is larger than 1.0 × 10 ⁻² Torr, the glass tablet is easily devitrified and deteriorated during sealing. In addition, as long as the pressure is 1.0 × 10 ⁻² Torr or less, it can be reached by a commonly used rotary pump.

The sealing of the metal material may be performed in a state where the sealing atmosphere is reduced by an oil diffusion pump (diffusion pump) in order to increase the degree of vacuum in the package. In this case, the degree of vacuum in the sealing atmosphere is 1.0 × 10 ⁻³ Torr or less. The upper limit of the degree of vacuum in the sealing atmosphere is not particularly limited. When a rotary pump and a turbo molecular pump were used in combination, the pressure was reduced to 1.0 × 10 ⁻⁶ Torr and a sealing test was performed. As a result, devitrification and alteration were observed in the sealing glass tablet of the present invention. It has been confirmed that there was not. However, in actual production, the degree of vacuum of the sealing atmosphere is difficult to be 1.0 × 10 ⁻⁶ Torr or less due to the influence of the gas released from the glass tablet or the metal material.

  The glass tablet for sealing of the present invention is preferably used for sealing in an atmosphere having an oxygen concentration of 5% by volume or less, for example, an inert atmosphere such as nitrogen or argon. If it does in this way, while a glass tablet becomes difficult to devitrify and change in quality at the time of sealing, oxidation of a metal material can be prevented. On the other hand, when the oxygen concentration in the sealing atmosphere is more than 5% by volume, the glass tablet is easily devitrified and deteriorated, and the metal material is easily oxidized. Even if a vacuum pump or the like is not used, if an inert gas such as nitrogen or argon is simply allowed to flow in the sealing atmosphere, and the atmospheric concentration of the inert gas is set to 95% by volume or more, the remaining in the sealing atmosphere The oxygen concentration can be 5% by volume or less.

  Hereinafter, based on an Example, the glass tablet for sealing of this invention is explained in full detail.

  Table 1 shows examples (Nos. 1 to 7) of the present invention, and Table 2 shows comparative examples (Nos. 8 to 11) of the present invention.

  Each sample was prepared as follows. First, glass raw materials were prepared so as to have the glass composition in the table. Further, as the phosphorus introduction raw material, orthophosphoric acid (orthophosphoric acid), which is a liquid raw material, was not used, but stannous pyrophosphate and zinc metaphosphate were used, and the phosphorus introduction raw materials were all solid raw materials. When all the raw materials for introducing phosphorus are made into solid raw materials, there is an advantage that the same production equipment as other glass systems can be used. In addition, if a liquid raw material is directly put into a melting furnace and melted as a raw material for introducing phosphorus, a problem of spilling easily occurs. And in order to avoid the problem of spilling, the glass raw material must be once dried.

  Next, the prepared glass raw material was melted at 950 ° C. for 2 hours. In addition, in order to suppress the oxidation of SnO during melting, nitrogen was passed through the melting furnace. The residual oxygen concentration in the melting furnace at the time of nitrogen inflow was 1% or less.

  A thermophysical property evaluation sample was prepared as follows. Using a carbon jig, the molten glass was formed into a cylindrical shape having a diameter of 5 mm and a length of 20 mm. This columnar sample was annealed and measured for thermal expansion coefficient α, glass transition point Tg, and yield point Tf in a temperature range of 30 to 300 ° C. by a push rod type thermal dilatometer (manufactured by Rigaku).

  Moreover, the molten glass was shape | molded in the film form with the water cooling roller. Finally, the obtained glass film was pulverized by a ball mill and then passed through a sieve having an opening of 105 mesh to obtain each glass powder sample having an average particle size of about 10 μm.

The glass powder and the refractory filler described in the table (average particle size of about 10 μm) were mixed so that the mixing ratio described in the table was obtained. In the table, NZP represents NbZr (PO ₄ ) ₃ , SNZ represents stannic oxide, ZWP represents Zr ₂ (WO ₄ ) (PO ₄ ) ₂ , CDR represents cordierite, and ZP represents zirconium phosphate. .

  A slurry turbid liquid was obtained by mixing 4 parts by mass of polyethylene carbonate and 20 parts by mass of dimethyl carbonate with respect to 100 parts by mass of each powder sample. This slurry-like turbid liquid was spray-granulated to obtain a granule sample having an average particle diameter of about 50 μm.

This granule sample was put in a mold and press-molded at a pressure of 1.0 ton / cm ² to obtain a press-molded body. Next, temporary baking was performed for 10 minutes at a temperature 60 ° C. higher than the glass transition point of the SnO—P ₂ O ₅ glass described in the table, and glass tablets having various shapes were produced.

  A thermal expansion coefficient α in a temperature range of 30 to 300 ° C. was measured with a push rod type thermal dilatometer (manufactured by Rigaku) using a glass tablet sample of 5 mmφ × 20 mm.

The sealing property of the metal material was evaluated using the glass tablet having the shape shown in FIG. Specifically, after inserting an iron-nickel-cobalt alloy (Kovar) metal lead having a thermal expansion coefficient of about 50 × 10 ⁻⁷ / ° C. into the inner hole of the glass tablet, the thermal expansion coefficient is about 80 × 10 ^−7. A glass tablet was placed on a metal base composed mainly of iron at / ° C. Next, after firing in the table and under the following conditions, check the sealing state of the metal lead and the metal base, "○" if the sealing state was good, and poor sealing state Was evaluated with “×”.

“Baking under reduced pressure” in the table is a baking while continuously reducing the pressure with a rotary pump. At the time of firing, there was a change in pressure due to the foaming gas generated from the glass tablet, but it was confirmed by a pressure gauge that the pressure was 1.0 × 10 ⁻² Torr or less. The firing conditions were a firing temperature of 650 ° C. for 10 minutes, a heating rate of 20 ° C./min from room temperature to the firing temperature, and a cooling rate of 15 ° C./min to room temperature.

  The “atmosphere firing” in the table is one in which the gas described in the table is constantly flowed at 2.0 L / min. The oxygen concentration remaining at the time of firing was confirmed to be 5% by volume or less by an oxygen concentration meter. The firing conditions were a firing temperature of 550 ° C. for 10 minutes, a heating rate of 15 ° C./min from room temperature to the firing temperature, and a cooling rate of 10 ° C./min to room temperature.

As is clear from Table 1, sample No. 1 to 7 has a thermal expansion coefficient of 52.0 × 10 ^{−7 to} 72.4 × 10 ⁻⁷ / ° C. in a temperature range of 30 to 300 ° C., and both depressurization firing and atmosphere firing are devitrified after firing, There was no change in quality and good sealing properties were exhibited.

  On the other hand, as apparent from Table 2, the sample No. In Nos. 8 and 9, neither devitrification nor deterioration was observed in both the reduced pressure firing and the atmosphere firing, but the sealing strength with the metal material was weak and the sealed portion was peeled off. Sample No. 10 had neither devitrification nor alteration in both reduced-pressure firing and atmosphere firing, but because the molar ratio SnO / ZnO was larger than 4.5, it flowed excessively and protruded from the metal base. Sample No. No. 10 has a melting point that is too low to be used in the middle temperature range. Sample No. No. 11 had neither devitrification nor alteration in both reduced pressure firing and atmospheric firing, but hardly flowed on the metal material.

  Since the glass tablet for sealing of the present invention can seal a metal material satisfactorily at an intermediate temperature range of 450 to 800 ° C., sealing a metal package such as a metal package for an airtight terminal, fixing a conductor holder, It can be used for glass tablet-integrated exhaust pipes, sealing of jumet wires, sealing the mouth of sheathed heaters, etc.

Claims (7)

In a sealing glass tablet containing at least SnO—P ₂ O ₅ glass,
_SnO-P 2 _{O 5} based glass, as a glass composition, in mol%, SnO 15 to 30% (not inclusive of _{30%), P 2 O 5} 20~40%, WO 3 5~20% ( However, 5% is not included), ZnO 6-30% (however, 30% is not included), and the molar ratio SnO / ZnO is 1 or more and 4.5 or less. Tablet.   2. The glass tablet for sealing according to claim 1, which has a glass transition point of 370 to 500 ° C. (not including 370 ° C.).   The glass tablet for sealing according to claim 1 or 2, which is substantially free of PbO.   Furthermore, 0-55 volume% of fireproof fillers are included, The glass tablet for sealing in any one of Claims 1-3 characterized by the above-mentioned. The sealing glass tablet according to any one of claims 1 to 4, wherein the sealing glass tablet is used for sealing in a reduced pressure atmosphere of 1.0 x ^10-2 Torr or less.   The sealing glass tablet according to claim 1, which is used for sealing in an atmosphere having an oxygen concentration of 5% by volume or less.   The glass tablet for sealing according to any one of claims 1 to 6, wherein all or part of the sealing object is a metal material.