JP2003238199A - Press frit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lead-free noncrystalline glass usable in cementing and sealing various members, to provide a method for producing the same, and to provide a sealing material using the glass. <P>SOLUTION: The lead-free press frit comprises 30-100 vol.% low-melting-point glass powder, 20-68% SnO, 2-8% SnO<SB>2</SB>, 20-40% P<SB>2</SB>O<SB>5</SB>and SnO+SnO<SB>2</SB>+P<SB>2</SB>O<SB>5</SB>being 100%, the % being mol.% in terms of the oxide, and 0-70 vol.% refractory filler powder. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to SnO and P ₂ O ₅
The present invention relates to a press frit using a low-melting-point glass powder containing as a main component, and particularly relates to a press frit having improved glass fluidity. In addition, mere "%" used in the text
The display is "mol%".

[0002]

2. Description of the Related Art A press frit is a low melting glass powder or a mixture of a low melting glass powder and a refractory filler powder (hereinafter referred to as a low melting glass powder), which is used as a sealing surface of an object to be sealed by press molding. It is a sealing material that has been processed into a similar shape, and is used for adhesive parts of metal, glass, ceramics, etc. that require reliability such as insulation, airtightness, watertightness, heat resistance and the like. Its characteristics are that it can be sealed simply by setting a press frit on the seal part and heating it, so it is easier to handle than a sealing material in powder form, the amount used can be kept constant, and automation is easy. . Its applications were to seal the mouth of sheathed heaters, to insulate and fix glow plug metal parts for engines, to fix exhaust pipes for displays, and to vacuum-seal thermos bottles.

Conventionally, these press frits have been required to be capable of performing sealing work at a temperature as low as possible in order to prevent damage to metal parts such as electrodes, and in response to this, PbO-B ₂ O ₃ system and PbO-B having a low glass transition point are required. Materials based on ₂ O ₃ —ZnO-based glass have been widely used.

Recently, however, a lead-free sealing material has been strongly demanded from the viewpoint of environmental problems and the health of workers, and a sealing material having a working temperature of 500 ° C. or lower that can be used for the above-mentioned applications is particularly required. Kaihei 6-183775,
JP-A-7-69672, JP-A-11-29256
No. 4 and Japanese Patent Laid-Open No. 2001-48579.

Japanese Unexamined Patent Publication No. 6-183775 aims to provide a lead-free sealing glass.
25 to 50 mol% P ₂ O ₅ and SnO: Zn
SnO and Zn so that the molar ratio of O is 1: 1 to 5: 1
O and SnO-ZnO-P ₂ O ₅ glass containing is disclosed.

Japanese Unexamined Patent Publication No. 7-69672 has a coefficient of thermal expansion of 120 to 140 × 10 ⁻⁷ / ° C.
An object of the present invention is to provide a lead-free sealing glass frit suitable for fusion sealing between electric parts.
O-P ₂ O ₅ based glass in _{R 2 O, B 2 O 3} , Al 2 O 3, Si
A sealing glass containing at least one selected from the group consisting of O ₂ and WO ₃ as a stabilizing oxide is disclosed. R ₂ O is Li ₂ O, Na ₂ O and K ₂ O.

Japanese Unexamined Patent Publication No. 11-292564 discloses a glass containing lead-containing glass having the same characteristics as a sealing glass,
The purpose of the present invention is to provide a sealing material using SnO 30-80 mol%, B ₂ O ₃ 5-60 mol%, and P ₂ O ₅ 5-24 mol% tin borate-based. Glass is disclosed.

Japanese Unexamined Patent Publication No. 2001-48579 discloses a glass containing lead-containing glass having properties equivalent to those of the sealing glass.
The purpose is to provide a sealing material using the same, and tin silica phosphate based glass having a composition of SnO 30 to 80%, SiO ₂ 5.5 to 20 mol%, and P ₂ O ₅ 10 to 50 mol%. Is disclosed.

[0009]

However, in the above,
Amorphous glass disclosed in JP-A-6-183775
The composition for sealing using the glass is glass during heating during sealing.
Tetravalent tin and pi formed by oxidation of divalent tin contained in
It is said that a compound with loric acid precipitates and hinders fluidity.
There was a problem. Therefore, the above-mentioned conventional technique (Japanese Patent Laid-Open No. 7-
69672, JP-A-11-292564 and JP-A-11-292564
(Disclosed in 2001-48579).
Al as a component for stabilizing the lath₂O₃, Si
O₂, B₂O ₃Developed as a glass component
Was done.

However, in the glass thus developed, the softening point of the glass remarkably rises and the fluidity deteriorates due to the above stabilizing component. In particular, B ₂ O _{3, which} is effective for stabilization, causes a phase separation and foaming during heating when the compounding amount is large, and it cannot be used for sealing parts that require high airtightness. There has been a problem that fluidity is deteriorated when a glass frit having a melting point is used as a press frit.

Therefore, an object of the present invention is to provide a press frit which is substantially free of lead and which can be used for joining and sealing various members.

[0012]

SUMMARY OF THE INVENTION In consideration of the above problems, the present invention has conducted various tests to evaluate low melting glass and a sealing material obtained by adding a refractory filler to low melting glass. did. As a result, even when low-melting glass with the same composition, when used as a sealing material depending on the manufacturing conditions, I noticed that a large difference was seen in the evaluation by the flow button, and when the low-melting glass was analyzed in detail, ,
It was found that there was a difference in the content of SnO ₂ contained in the glass, and a verification test was conducted, and it was found that SnO ₂ is closely related to the fluidity at the time of sealing.

It is presumed that the effect of SnO ₂ is due to the following phenomenon. In the prior art, the container being melted was capped and the supply of oxygen to the raw material being melted was restricted so that Sn contained in the glass was in the state of Sn ²⁺ .
The melting atmosphere was filled with nitrogen to obtain a nitrogen atmosphere, and a reducing agent such as a saccharide was added to the raw material composition. As a result, the obtained glass has an excessive P bond in the Sn—O—P structure, and this excess P bond is stimulated by an external factor such as heating to cause the pyrophosphate-based It is considered that this caused the formation of tin compounds (tetravalent), resulting in deterioration of fluidity during the sealing operation.

On the other hand, when a certain amount of SnO ₂ is contained, the excess state of the P bond in the Sn-O-P structure is relaxed, resulting in a more stable bond state, and pyrroline even when heated during the sealing operation. It is considered that the acid-based tin compound (tetravalent) was not produced.

Further, B ₂ when used as a press frit
As a result of verifying the effect of O ₃ on the fluidity, it was found that the method was different depending on the method of producing the press frit. This difference is a mixture of organic binders,
It appeared in the unmixed product, and the fluidity of the mixed organic binder was remarkably deteriorated. When the present inventors analyzed this, the B ₂ O ₃ component was likely to undergo phase separation when the glass softened, and the phase separated B ₂ O ₃ component remained in the press frit. It was found that the reaction product caused an esterification with the alkyl group of the binder and precipitated as a crystal to affect the fluidity.

Here, in general molding of a press frit, from the viewpoint of workability after molding, stability of quality, etc., an organic system containing a C ₁₀ or higher aliphatic alcohol as a main component in a low-melting glass powder or the like. The binder was mixed and the organic binder was removed by heating after press molding.

Therefore, in order to solve the above-mentioned problems, the present invention relates to claim 1, wherein the press frit does not substantially contain lead and SnO 20 to 68 in terms of oxide expressed in mol%. %, SnO ₂ 2-8%, P ₂ O _{5
20~40%, SnO + SnO 2 +} P 2 O 5 90~100
%, B ₂ O ₃ 0-2% low melting point glass powder 30
~ 100 volume% and refractory filler powder 0-70 volume%
And are included.

The invention corresponding to claim 2 corresponds to claim 1.
In the press frit of the invention, the low melting point glass
As a stabilizing component in the powder, 0.5-10 mol% of S
iO ₂Was included.

The invention corresponding to claim 3 is the press frit according to claim 1 or 2, wherein ZnO and Al _{2 are} contained in the low melting point glass powder as a stabilizing component.
O ₃ , WO ₃ , MoO ₃ , Nb ₂ O ₅ , TiO ₂ , ZrO ₂ ,
Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, CuO, MnO,
At least one selected from MgO, CaO, SrO and BaO is contained in a total amount of 15 mol% or less.

The invention corresponding to claim 4 is a method for producing a press frit, which does not substantially contain lead and has a mol%
20 to 68% SnO, SnO ₂ 2 in terms of oxides shown
_{~8%, P 2 O 5 20~40} %, SnO + SnO 2 + P 2
30 to 100% by volume of low melting point glass powder containing 90 to 100% of O _{5 and} 0 to 2% of B ₂ O _{3, the} refractory filler powder of 0 to 70% by volume, and an organic binder are mixed to form a granular powder. And a step of putting the granular powder in a molding die and pressing to form a press-molded body, and heating the press-molded body to remove the organic binder and sinter. did.

The reasons for limiting the low melting point glass composition of the present invention will be described below. SnO is an essential component for lowering the melting point of glass, and when the content of SnO is less than 20%, the viscosity of the glass becomes high and the sealing temperature becomes too high, and when it exceeds 70%, it vitrifies. Disappear. The preferable range is 40 to 65%.

SnO ₂ is an essential component for stabilizing the glass, and in particular, it is indispensable for preventing the formation of SnO ₂ precipitates which are separately formed in the softened and melted glass during the heating of the sealing operation. It is an ingredient. By including this SnO ₂ , the fluidity is not impaired even if it is repeatedly heated as in the conventional lead-based amorphous glass,
The sealing work can be performed stably. However, if the content is less than 2%, the effect of suppressing the generation of precipitates cannot be obtained, and if the content exceeds 8%, SnO ₂ precipitates are generated from the molten glass. The preferable range is 2.5 to 6%.

P ₂ O ₅ is an essential component for forming a glass skeleton, and if its content is less than 20%, it does not vitrify, and if its content exceeds 40%, it is a drawback peculiar to phosphate glass. Causes deterioration of weather resistance. A preferred range is 25-40%.

B ₂ O ₃ can be contained because it has the effect of lowering the coefficient of thermal expansion in addition to stabilizing the glass, but it can suppress the esterification reaction with the above-mentioned residual binder such as low-melting glass powder. In order to increase its content to 2%
Below. It is preferably 1% or less.

SiO ₂ is a component that may be added to form a glass skeleton, but if its content exceeds 10%, the transition point and softening point of the low-melting glass powder will rise and the present invention You won't get what you want. It is preferably 5% or less.

The low-melting-point glass powder formed of the components described in claim 1 or 3 has a low glass transition point and is sufficiently suitable as a sealing material for low temperatures. It may be contained. However, when the total amount other than the components described in claim 1 or 3 exceeds 15%,
Even if the glass becomes unstable and devitrification occurs during low-melting-point glass molding, or even if devitrification does not occur, the glass transition point and the softening point rise and the press frit intended by the present invention cannot be obtained.

As additive components, ZnO, Al ₂ O ₃ , W
O ₃ , MoO ₃ , Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Li
₂ O, Na ₂ O, K ₂ O, Cs ₂ O, CuO, MnO ₂ , M
A glass stabilizing component such as gO, CaO, SrO and BaO may be contained.

ZnO has the effect of lowering the coefficient of thermal expansion in addition to stabilizing the glass, and its content is 0-15.
%. If it exceeds 15%, the tendency of the glass to crystallize becomes strong and the fluidity tends to decrease. As mentioned above,
Since it is possible to adjust the coefficient of thermal expansion of glass,
In order to obtain a preferable low melting point glass, ZnO is an essential component and its content is 2 to 10%.

Al ₂ O ₃ , WO ₃ and MoO ₃ also have the effect of lowering the coefficient of thermal expansion in addition to stabilizing the glass, so that each component can be contained in the glass in an amount of 0 to 10%. When the content exceeds 10%, the viscosity of glass becomes high and the fluidity is impaired. Further, these components are not used alone but at least one of them is ZnO.
It is preferable to use together with. Further, the content in the glass is preferably 7% or less.

Since Nb ₂ O ₅ , TiO ₂ and ZrO ₂ also have the effect of improving the chemical durability, 0 to 10% of each component can be contained in the glass. If the content exceeds 15%, the glass tends to crystallize.
It is preferably 8% or less.

Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O
Has the effect of lowering the softening point of the glass and improving the fluidity, so that each component can be contained in the glass in an amount of 0 to 15%. If its content exceeds 15%, crystals will precipitate in the glass and the fluidity will be impaired. Preferably 10
% Or less.

Since CuO and MnO ₂ also have the effect of improving chemical durability, each component in the glass is 0 to
10% can be contained. If the content exceeds 10%, the softening point increases and the fluidity decreases. It is preferably 5% or less.

MgO, CaO, SrO and BaO are
Since it also has the effect of adjusting the glass viscosity and the thermal expansion coefficient, 0 to 10% of each component can be contained in the glass. If the content exceeds 10%, the softening point increases and the fluidity decreases. It is preferably 5% or less.

It is also possible to lower the softening point by incorporating halogen into the glass by using a halide raw material such as fluoride or chloride as the raw material.

The low melting glass powder used in the present invention described above has a glass transition point of 250 to 350 ° C.,
Excellent fluidity at a temperature of 500 ° C or less, particularly 320 to 480 ° C, and 90 to 150 × 1 at 30 to 250 ° C.
It has a coefficient of thermal expansion of 0 ^-7 / ° C.

The frit powder obtained by mixing 30 to 100% by volume of the low melting glass powder and 0 to 70% by volume of the refractory filler powder is press-molded to obtain the press frit of the present invention. They can be mixed to adjust the coefficient of thermal expansion of the frit and to improve the mechanical strength of the press frit. If the mixing amount of the refractory filler powder exceeds 70% by volume,
Fluidity as a sealing material cannot be obtained. Preferably 55
Volume% or less.

As the refractory filler powder, silica glass, quartz, cordierite, eucryptite,
Mullite, zircon, zirconium phosphate and willemite can be used, but silica glass, cordierite and zirconium phosphate are preferable in view of compatibility with glass.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The press frit of the present invention contains substantially no lead, SnO 20 to 68%, SnO ₂ 2
_{~8%, P 2 O 5 20~40} %, SnO + SnO 2 + P 2
A glass of the low melting point glass powder containing 30 to 100% by volume of a low melting point glass powder containing 90 to 100% of O _{5 and} 0 to 2% of B ₂ O _{3 and} 0 to 70% by volume of a refractory filler powder. The skeleton-forming agent may contain 0.5 to 10% of SiO ₂ . As a component for further stabilizing, 15% or less of at least one of the following optional components may be contained. As an optional component, ZnO, Al ₂ O ₃ , W
O ₃ , MoO ₃ , Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Li
₂ O, Na ₂ O, K ₂ O, Cs ₂ O, CuO, MnO ₂ , M
gO, CaO, SrO and BaO. Further, an organic binder is added when the low melting glass powder and the refractory filler powder are mixed.

Then, the raw materials are mixed so as to have the composition range described above (however, the same raw material for SnO ₂ is used as the raw material for SnO) to prepare a batch raw material. The mixture was placed in a furnace adjusted to 1200 ° C., and the batch raw material was heated for 10 to 90 minutes to perform an oxidation treatment. Then, a lid was attached to the quartz crucible and further melted for 30 to 50 minutes. The melted glass was shaped into a sheet with a water-cooling roller, crushed, and then passed through a sieve with an opening of 105 μm to obtain low-melting glass powder.

30 to 100% by volume of this low melting point glass powder
Then, 0 to 70% by volume of a refractory filler adjusted to have a certain particle size or less is added to obtain a frit powder. Next, an organic binder having a decomposition temperature not higher than the transition point temperature of the low melting point glass powder is added to this frit powder with respect to 100% by mass of the frit powder.
The granules obtained by adding 0.2 to 10% by mass and mixing and drying are sized with a sieve to a particle size of 44 to 256 μm to obtain a granular powder.

In order to uniformly disperse the organic binder in the frit powder, the organic binder is dissolved and mixed in a low boiling point solvent such as alcohols such as benzene, ethyl ether, acetone and ethanol, and then added. Is preferred. Benzene, ethyl ether, acetone,
When a solvent such as alcohols such as ethanol is used, it is necessary to perform a drying treatment at 30 to 100 ° C. for about 0.5 to 5 hours after forming the granules.

Unless the particle size of the above granules is 44 to 256 μm, it becomes difficult to obtain a good press frit. That is, if the particle size is less than 44 μm, the contact area between the particles increases, so that the flow of the granules is hindered and the bulk density when filling the molding die decreases, and the shrinkage rate during firing increases. However, if a measure that promotes the flow of granules by vibrating when filling is used, particles having a diameter of less than 44 μm can also be used. On the other hand, if the particle size exceeds 256 μm, the number of contacting parts of the granules after pressing becomes small and the porosity increases, the molded body becomes brittle and the shrinkage rate during firing increases.

Pour the granular powder into the mold in the desired amount,
After press molding at a pressure of 5 to 50 × 10 ⁴ kPa and heating at 200 to 250 ° C. for 30 to 120 minutes to decompose and remove the organic binder component, further 10 to 120 minutes at a temperature equal to or higher than the glass softening point. Baking and sintering give a press frit. Here, the temperature at the time of sintering is 0 to 50 ° C. with respect to the softening point of the low melting point glass powder obtained by a differential thermal analyzer so that the formed shape is not deformed by softening or the like.
By firing at a high temperature, the press frit can be sintered without deformation. It should be noted that upon sealing, it is preferable to carry out the sealing in an atmosphere as inactive as possible, such as argon or nitrogen, in order to prevent oxidation of SnO contained in the sealing material, since good results can be obtained.

[0044]

EXAMPLES Examples and comparative examples of the present invention will be described in detail below with reference to Tables 1 and 2.

[Table 1]

Example 1 Stannous oxide (SnO ₂ may be included as an impurity) was used as a raw material for SnO and SnO ₂ , and SnO + SnO ₂ 68.9%, P ₂ O ₅
The raw materials are mixed so as to be 29.8%, ZnO 0.8%, and SiO ₂ 0.5% to prepare a batch raw material. This batch raw material was put into a quartz crucible and put into a melting furnace adjusted to 1100 ° C., and the quartz crucible was heated for 10 minutes without being covered to be oxidized, and then the quartz crucible was covered and melted for 50 minutes. . Then, the molten glass is molded into a sheet having a size of 0.3 to 0.5 mm by a water cooling roller, and the opening 105
What passed through a sieve of μm was used as a low melting point glass powder. Further, when the SnO and SnO ₂ components in the low melting point glass were analyzed, they were SnO 66.5% and SnO ₂ 2.4%.

To 70% by volume of this low-melting glass powder, 30% by volume of zirconium phosphate powder passed through a 45 μm sieve as a refractory filler was added to obtain a frit powder. The fluidity of this frit powder was confirmed by the flow button method. 3.8 g of the frit powder was pressure-molded into a cylindrical shape having a diameter of 12 mm, and the frit powder was placed on a soda-lime glass substrate for 3 times.
The mixture was heated at 90 ° C for 10 minutes and gradually cooled to 50 ° C over 15 hours to prepare a flow button. When this flow button was measured with a caliper, it was 23 mm (if the diameter of the flow button is 22 mm or more, the fluidity is good). The surface condition of the flow button was visually observed and observed with a 50 × optical microscope. As a result, no foreign matter such as devitrification was contained and the surface was glossy. From this result, it was confirmed that the frit powder had no problem in sealing.

To measure the coefficient of thermal expansion of the frit powder, first, put a certain amount of the frit powder in a mold and heat the same at 390 ° C. for 10 minutes and slowly cool the resulting block in the same manner as in the production of flow buttons. It was 78 × 1 when it was polished and the amount of elongation at 30 to 250 ° C. was measured to measure the average coefficient of thermal expansion.
It was 0 ^-7 / ° C.

Next, a 20% by mass solution of myristyl alcohol dissolved in acetone was added to the frit powder at a ratio of 10% by mass to 100% by mass of the frit powder,
After mixing for 30 minutes, drying was performed at 35 ° C. for 30 minutes to obtain a granular form from which acetone as a solvent was removed, and a granular powder having a particle size range of 44 to 256 μm was prepared. This granular powder 0.2
2 g was press-molded at 20 × 10 ⁴ kPa to a diameter of 5 mm × height of 5 mm to obtain a press-molded body. This press-molded body was subjected to heat treatment at 350 ° C. for 20 minutes to remove myristyl alcohol as an organic binder by heating to obtain a press frit. This press frit was placed on a soda lime glass substrate, heated at 390 ° C. for 10 minutes, and gradually cooled to 50 ° C. over 15 hours to prepare a flow button. When this flow button was measured with a caliper, it was 9 mm (in this case, if the diameter of the flow button is 7 mm or more, the fluidity is good). The surface condition of the flow button was visually observed and observed with a 50 × optical microscope. As a result, no foreign matter such as devitrification was contained and the surface was glossy.

When the residual myristyl alcohol in the press frit was analyzed, it was 50 p in terms of CO _2.
However, since B ₂ O ₃ was not contained in the low melting point glass powder, a fluidity was excellent and an excellent press frit for sealing was obtained.

For (Example 2) to (Example 12), the raw materials were adjusted so that the compositions shown in Table 1 were obtained, and the low melting point glass, frit powder, and
A sealing material and a press frit were obtained. Where SnO
And stannous oxide, stannous chloride, or tin pyrophosphate are used as the raw materials for SnO ₂ and cordierite powder, silica glass powder, zirconium phosphate powder are used as the refractory filler (however, In Example 10, no refractory filler was used), and as the organic binder, acetone was used as a solution in which any one of myristyl alcohol, stearyl alcohol, and cetyl alcohol was dissolved alone or as a mixture.

Then, as shown in Table 1, in the evaluation of the frit powder by the flow button, it was found that in all the examples, the flow diameter was 22 mm or more and the surface was good and glossy. It was In addition, in the evaluation using the flow button of the press frit, the flow diameter was 7 in all the examples.
A good product having a thickness of at least mm and a glossy surface was obtained.

The amount of residual binder is 3 in terms of CO _2.
0 to 60 ppm, especially in Examples 4 to 1
In No. 2, B ₂ O ₃ was contained in the low melting point glass, but no precipitate due to esterification of B ₂ O ₃ and the alkyl group of the binder was generated.

Comparative Example Table 2 shows a comparative example of the present invention.

[Table 2]

Comparative Example 1 In this comparative example, as shown in Table 2, raw materials were blended in a low melting point glass so that the B ₂ O ₃ component was 2.2%, and the raw materials were melted. A low-melting glass powder was prepared in the same manner as in Example 1 except that the oxidation treatment was not performed. SnO in this low melting point glass powder was 58.0% and SnO ₂ was 1.6%. This low melting point glass powder has 69% by volume, 45 μm
31% by volume of cordierite powder that passed through the sieve of No. 1 was added to obtain a frit powder. This frit powder was used in Example 1 above.
When the flow button was evaluated in the same manner as above, the flow diameter was as short as 17 mm, and crystals were also deposited on the surface, resulting in dullness, making it unusable for press frit. I didn't. Therefore, if oxidation treatment is not performed,
No frit powder suitable for sealing is obtained.

(Comparative Example 2) This comparative example is the same as the comparative example 1 described above.
The low melting point glass powder was obtained by performing the oxidation treatment with the same raw material. SnO in this low melting point glass powder was 57.
3% and SnO ₂ was 2.3%. Then, as in Comparative Example 1, the frit powder obtained by mixing the low melting point glass powder and the cordierite powder was evaluated by the flow button. As a result, the flow diameter was as good as 22 mm and the surface was glossy.

Then, a 20% by mass solution of myristyl alcohol dissolved in acetone was added to the frit powder at a ratio of 15% by mass to 100% by mass of the frit powder, and the same treatment as in Example 1 was performed. As a sealing material, a press frit was prepared from this sealing material, and the flow button was evaluated. As a result, the flow diameter is as short as 6 mm,
Furthermore, crystals were also deposited on the surface, and the surface was dull. When this crystal was analyzed, it was an esterified product of B ₂ O ₃ and the alkyl group of the binder. Therefore,
A low melting glass containing 2.2% of B ₂ O ₃ could not be used as a press frit.

(Comparative Example 3) This comparative example was formed without the oxidation treatment in the same manner as in Comparative Example 1 so that the low melting point glass shown in Table 2 was obtained. Was transparent and good. However, only low melting point glass powder without mixing with refractory filler,
As a result of evaluation using the flow button, the flow diameter is 18 mm.
It was too short, and crystals were also deposited on the surface to give a dull gloss, and it could not be used as a press frit. Therefore, the flow button of the press frit was not evaluated. Therefore, frit powder suitable for sealing cannot be obtained without oxidation treatment.

Comparative Example 4 In this comparative example, B ₂ O ₃ was not contained in the low melting point glass to reduce the content of the P ₂ O ₅ component. Devitrification occurred in the glass and it could not be used as a low melting point glass powder. Therefore, the evaluation after the frit powder was not performed.

The low melting point glass formed into a sheet shape in each of Examples 1 to 12 described above was transparent, but the present invention is not limited to this, and coloring materials such as CuO, MnO ₂ and Fe ₂ O _{3 can be used.} May be included. By coloring the glass according to the use and characteristics, the appearance of the sealed article is not impaired. Further, it becomes possible to judge the composition by the color of the low melting point glass powder.

[0060]

As described above, the press frit of the present invention contains substantially no lead and contains S in the low melting point glass powder.
By introducing nO ₂ by an oxidation treatment and setting the allowable amount of the B ₂ O ₃ component to 2% or less, good fluidity is obtained at 500 ° C. or less and precipitates such as devitrification and crystals are formed. Since it does not form, it can be used as an amorphous sealing material.

Therefore, for sealing the mouth of the sheathed heater,
It can be used for various applications such as insulation and fixing of metal parts for glow plugs for engines, fixing of exhaust pipes for displays, vacuum sealing of thermos bottles, etc.

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Claims (4)

[Claims] 1. SnO 20 to 68%, SnO _{2 2 to} 8%, which is substantially free of lead and is converted into oxide in terms of mol%.
_{P 2 O 5 20~40%, SnO} + SnO 2 + P 2 O 5 90
To 100%, low melting glass powder 30 to 100% by volume containing B ₂ O ₃ 0 to 2%, and refractory filler powder 0 to 7
A press frit containing 0% by volume. 2. The low melting glass powder contains 0.5 to 1
A press frit according to claim 1, characterized in that it contains 0 mol% SiO ₂ . 3. ZnO, A in the low melting point glass powder
l ₂ O ₃ , WO ₃ , MoO ₃ , Nb ₂ O ₅ , TiO ₂ , Zr
O ₂ , Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, CuO, M
The press frit according to claim 1 or 2, which contains a total amount of at least one selected from nO ₂ , MgO, CaO, SrO and BaO in an amount of 15 mol% or less. 4. Substantially no lead, SnO 20-68%, SnO ₂ 2-8% in terms of oxide expressed in mol%,
_{P 2 O 5 20~40%, SnO} + SnO 2 + P 2 O 5 90
˜100%, low melting glass powder containing 0 to 2% B ₂ O ₃ 30 to 100% by volume, and the refractory filler powder 0 to
A step of mixing 70% by volume and an organic binder into a granular powder, a step of putting the granular powder in a molding die and pressing to form a press molded body, and heating the press molded body And a step of removing the binder and sintering the press frit.