JP4556544B2 - Glass for sealing - Google Patents

Description

  The present invention relates to a sealing glass used for sealing a metal product such as a metal vacuum double container used for a thermos (water bottle / launcher), for example.

  As shown in FIG. 2, the metal vacuum double container 10 includes an outer container 11 and an inner container 12, the outer container 11 and the inner container 12 are overlapped, and a hollow portion between the outer container 11 and the inner container 12. Reference numeral 13 denotes a container kept in a vacuum. This container is widely used in thermos bottles because it has high heat retention and does not break.

  As one method of manufacturing a metal vacuum double container, a method of vacuum-sealing using a low-melting glass at an exhaust port provided in either the outer container or the inner container has been proposed (for example, a patent Reference 1).

In order to seal the exhaust port of a metal vacuum double container, PbO—B ₂ O ₃ based low melting point sealing glass has been used conventionally (for example, see Patent Document 2), but recently. From the viewpoint of environmental problems, low melting point sealing glass containing no lead is required.

SnO—P ₂ O ₅ -based glass has been proposed as a low-melting-point sealing glass that does not contain lead (see, for example, Patent Documents 3 and 4).
Japanese Patent No. 27747748 JP 2002-125866 A JP-A-7-69672 JP 2004-67406 A

When a metal object to be sealed, for example, a metal vacuum double container, is vacuum-sealed using SnO-P ₂ O ₅ glass, many bubbles are generated in the glass. There is a high possibility that the airtightness of the sealing portion is impaired due to leakage.

An object of the present invention is a highly reliable sealing glass made of SnO—P ₂ O ₅ glass, which does not impair hermeticity over a long period of time even when a metal object is sealed. Is to provide.

The present inventor conducted various experiments. When the exhaust port of the metal double container was vacuum-sealed by heating and softening the SnO-P ₂ O ₅ glass, the components contained in the glass and the double container It has been found that when the metal (stainless steel) reacts, many bubbles are generated at the interface between them, and when the MoO ₃ is added to the SnO—P ₂ O ₅ glass, the foaming can be suppressed. I came to propose.

That is, the sealing glass of the present invention is a sealing glass made of SnO—P ₂ O ₅ glass used for sealing a metal object to be sealed, and the glass is expressed in mol%. , SnO 30 to 60%, P ₂ O ₅ 18 to 45%, MoO ₃ 0.1 to 5%.

  When the sealing glass of the present invention is used for vacuum sealing of a metal double container, sealing can be performed at a temperature of 400 to 600 ° C., and bubbles generated when the sealing glass reacts with stainless steel can be reduced. Moreover, the glass for sealing of the said composition does not crystallize or discolor after the vacuum sealing. Therefore, it is possible to perform highly reliable hermetic sealing that does not leak even after long-term use.

The reason why the composition range of the SnO—P ₂ O ₅ glass is limited as described above will be described below.

  SnO is a component that lowers the melting point of glass. When SnO is less than 30%, the viscosity of the glass increases and the sealing temperature tends to increase, and when it exceeds 60%, vitrification becomes difficult. In addition, since it will become easy to devitrify at the time of sealing when there is much SnO, it is preferable that it is 57% or less. Moreover, if it is 40% or more, since it is excellent in fluidity | liquidity and high airtightness is obtained, it is preferable.

P ₂ O ₅ is a glass forming oxide. If the P ₂ O ₅ content is less than 18%, it is difficult to obtain sufficient glass stability. If it is in the range of 18 to 45%, sufficient stability can be obtained for the glass, but if it exceeds 45%, the moisture resistance tends to deteriorate. Further, if P ₂ O ₅ is 20% or more, the glass is further stabilized, but if it exceeds 35%, the weather resistance of the sealing glass tends to be slightly deteriorated, so it is 20 to 35%. Is preferred.

MoO ₃ is an essential component of the present invention. The sealing glass has an effect of suppressing the reaction with the metal object to be sealed during vacuum sealing and reducing foaming due to the reaction. In this reaction, it is considered that a redox reaction occurs between the metal object to be sealed and the glass component. If MoO ₃ is less than 0.1%, there is almost no effect. On the other hand, if it exceeds 5%, the viscosity at the time of melting the glass becomes high, so that it becomes difficult to pour out and it is difficult to obtain sufficient fluidity at the time of metal sealing. Moreover, it becomes easy to devitrify. A preferable MoO ₃ composition range is 0.3 to 4.8%.

  Moreover, the glass for sealing of this invention can add various components in addition to the said component.

  ZnO is an intermediate oxide. ZnO is not an essential component, but is desirably 4% or more because it has a great effect of stabilizing the glass. However, if ZnO exceeds 20%, devitrification tends to occur on the glass surface during sealing. The ZnO content is desirably 5 to 15%.

Al ₂ O ₃ is an intermediate oxide. Al ₂ O ₃ is not an essential component, but it is desirable to contain Al ₂ O _{3 because} it has the effect of stabilizing the glass and the effect of reducing the thermal expansion coefficient. However, if it exceeds 10%, the softening temperature rises and the sealing temperature becomes too high. In addition, when the stability of glass, a thermal expansion coefficient, fluidity | liquidity, etc. are considered, the range of 0.5 to 5% is more preferable.

SiO ₂ is a glass forming oxide. Although SiO ₂ is not an essential component, it is desirable to contain it because it has an effect of suppressing devitrification. If it exceeds 15%, the softening temperature rises and the sealing temperature tends to be high.

B ₂ O ₃ is a glass forming oxide. B ₂ O ₃ is not an essential component but has an effect of stabilizing the glass. However, if it exceeds 30%, the viscosity of the glass becomes too high, the fluidity at the time of sealing is remarkably deteriorated, and the airtightness of the sealing part tends to be impaired. A preferable range of B ₂ O ₃ is 0 to 25%. Since B ₂ O ₃ has a strong tendency to increase the viscosity of glass, it is required to have very high fluidity, and when it is necessary to significantly lower the softening point, B ₂ O ₃ should not be contained.

R ₂ O (R is Li, Na, K, Cs) is not an essential component, but at least one of the R ₂ O components is added to the composition to improve the adhesive strength with metals such as stainless steel SUS304. Tend to. However, if the total amount exceeds 20%, devitrification tends to occur during sealing. In consideration of surface devitrification and fluidity, the total amount of R ₂ O is preferably 10% or less. Further, among R ₂ O, Li ₂ O is most likely to improve the adhesive force with a metal such as stainless steel SUS304.

Lanthanoid oxides such as La ₂ O ₃ and CeO ₂ are network-modified oxides. By including the lanthanoid oxide in the glass component in a total amount of 0.1% or more, the weather resistance of the glass is easily improved. On the other hand, if the lanthanoid oxide exceeds 25%, the sealing temperature tends to be high. In consideration of the improvement in weather resistance and the balance between the sealing temperatures, the total content of the lanthanoid oxide is preferably 2 to 15%, particularly 4 to 15%.

In addition to the lanthanoid oxide, the use of other rare earths such as Y ₂ O ₃ is effective for improving the weather resistance of the glass. The amount of rare earth added excluding the lanthanoid oxide is preferably 0 to 5%.

  R′O (R ′ is Mg, Ca, Sr, Ba) is not an essential component, but is useful as a component that stabilizes the glass. When the total amount of R′O exceeds 15%, devitrification tends to occur. Therefore, the content of R′O is desirably 15% or less, more preferably 10% or less.

In addition, for example, components that stabilize the glass, such as Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , CuO, MnO, In ₂ O _3, can be contained in a total amount of up to 20%. In addition, when content of these stabilization components exceeds 20%, glass will become unstable and it will become difficult to manufacture. In order to obtain a more stable glass, the content is preferably 15% or less.

The contents of Nb ₂ O ₅ , TiO ₂ , and ZrO ₂ are all 0 to 15%, particularly preferably 0 to 10%. If each of these components exceeds 15%, the glass tends to be unstable.

  The contents of CuO and MnO are both 0 to 10%, particularly preferably 0 to 5%. If each of these components exceeds 10%, the glass tends to become unstable.

In ₂ O ₃ 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%.

If it exists in the above composition range, it has the glass transition point of about 270-330 degreeC, the softening point of about 360-410 degreeC, and the glass for sealing which shows favorable sealing property in the temperature range of 400-600 degreeC. Obtainable. Further, it can have a thermal expansion coefficient of about 100 to 130 × 10 ⁻⁷ / ° C. at 30 to 250 ° C.

  The shape of the sealing glass of the present invention is not limited as long as it can be stably disposed in the recess formed in either the inner container or the outer container of the metal double container. For example, a rectangular parallelepiped, a cylinder, a sphere, a hemisphere, an elliptical sphere, a flat sphere, an egg shape, or a lump having a shape similar to the above may be used.

  The glass for sealing of this invention may contain 0-20 volume% of fillers for adjustment of a thermal expansion coefficient.

  As the filler, silica glass, quartz, cordierite, eucryptite, mullite, zircon, zirconium phosphate, willemite, alumina and the like can be used.

  Below, the manufacturing method of the glass for sealing of this invention is demonstrated.

  First, the raw material prepared to have a desired composition is melted at 800 to 900 ° C.

  Next, the molten glass is formed into a desired shape. For example, molten glass is drawn out into a rod shape and cut into a predetermined length. Alternatively, the molten glass is dropped, or the molten glass is solidified into a lump shape and then cut into a predetermined size. Thus, the glass for sealing of this invention can be obtained.

  Hereinafter, the glass for sealing of this invention is demonstrated in detail based on an Example and a comparative example.

  Table 1 shows examples of the present invention (samples a to d), and Table 2 shows comparative examples (samples e to h).

  The sealing glass was prepared as follows.

  For each sample, glass raw materials prepared so as to have the composition shown in Table 1 or 2 are placed in a quartz crucible, heated from normal temperature in an electric furnace in a nitrogen atmosphere, melted at 850 ° C. for 2 hours, and plate-shaped from the crucible. It was prepared by pouring out and annealing.

  The glass transition point and the coefficient of thermal expansion were measured with a push rod type thermal dilatometer (TMA manufactured by Rigaku) after molding each sample to 20 × 5 mmφ.

  The softening point was measured by a macro type differential thermal analysis (DTA) apparatus (manufactured by Rigaku).

  Foaming was evaluated as follows.

  As shown in FIG. 1, first, a sealing glass 6 was disposed in the exhaust port 5 of the metal vacuum double container M. Here, in the metal vacuum double container M, a concave portion 4 having a diameter of 10 mm and a depth of 2 mm is formed in the outer container 1, and an exhaust port 5 having a diameter of 1.5 mm is provided in the center of the concave portion 4. The sealing glass 6 is cut out from each sample into a size of 3 × 3 × 3 mm.

  Next, the metal double container M was heated to 500 ° C. under a vacuum environment (0.1 Torr) and held for 30 minutes to seal the exhaust port 5. In addition, the material of the metal double container M used stainless steel SUS304.

  After sealing, the foaming state at the interface between the metal and the glass was visually evaluated by visual observation without using an optical microscope and by optical microscope 50 times. The case where foaming could be confirmed visually was indicated as “X”, the case where the foaming could be confirmed with a 50 × optical microscope was designated as “Δ”, and the case where foaming could not be confirmed with a 50 × optical microscope was designated as “◯”.

As is clear from Table 1, samples a to d have a coefficient of thermal expansion of 98.5 to 123 × 10 ⁻⁷ / ° C., a softening point of 383 to 455 ° C., no foaming, and the like. The exhaust port was well sealed. Further, when the state after sealing was observed, no crystal deposition or discoloration was observed.

  On the other hand, as apparent from Table 2, when samples e to g were evaluated for foaming of the sealing glass, many foams were confirmed at the interface between the glass and stainless steel. Moreover, the sample h had a high viscosity at the time of melting, devitrified when the molten glass was formed, and could not be used as a sealing glass.

  The glass for sealing of the present invention does not crystallize even when heated and softened, and no bubbles are generated at the interface with the object to be sealed. It is suitable for sealing an exhaust port.

It is explanatory drawing which shows the sealing method of a metal vacuum double container. It is explanatory drawing which shows a vacuum double container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Outer container 2, 12 Inner container 3 Vacuum heat insulation layer 4 Recessed part 5 Exhaust port 6 Sealing glass M Metal vacuum double container 10 Vacuum double container 13 Hollow part

Claims (3)

A glass for sealing made of SnO—P ₂ O ₅ glass used for sealing a metal object to be sealed, the glass being expressed in mol%, SnO 30-60%, P ₂ O ₅ 18 to 45%, the sealing glass which is characterized by containing MoO ₃ 0.1 to 5%.   The glass for sealing according to claim 1, wherein the metal object to be sealed is a metal vacuum double container.   3. The sealing glass according to claim 1, which has a rectangular parallelepiped shape, a cylindrical shape, a sphere shape, an elliptical sphere shape, a hemisphere shape, a flat sphere shape, or an oval shape.