JP2002348152A - Metallic vacuum double container and method for making the same, sealing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic vacuum double container having no problem against human and environment, having no problem in recycling stainless steel, or having excellent yield in sealing and which is coated with a fluororesin. SOLUTION: The purpose is attained by carrying out the sealing using a low melting point glass sealing material 43 having a softening temperature higher than fluorocarbon coating sintering temperature and degassing temperature at the time of evacuation, and not impeding reusing of inner and outer containers 1, 2 even in simultaneous melting together with the inner and outer containers 1, 2, for example, which does not contain lead or others contained in conventional low melting point glass sealing materials, and which does not contain ingredients having food hygienical problem.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vacuum double container, a method for producing the same, and a sealing composition which can be used for these containers, for example, an electric pot, a portable heat-insulating bottle, a lunch jar, a heat-insulating cooking pot, a mug, etc. The present invention relates to a metal vacuum double container suitable for use in eating and drinking, a production method thereof, and a sealing composition.

[0002]

2. Description of the Related Art A vacuum double metal container has a high heat insulation property in which a vacuum insulation space is provided between an inner and an outer container, and a stainless steel container is mainly used because of its low thermal conductivity, corrosion resistance and strength. To make a vacuum insulation space between the inner and outer containers, first,
Vacuum exhaust is performed through the exhaust hole, and then the exhaust hole is sealed with a sealing material while maintaining the vacuum exhaust state,
The vacuum insulation space is sealed.

[0003] Vacuum evacuation is performed in a heating atmosphere in a heating furnace in order to increase the evacuation efficiency, and sealing processing is performed by softening or melting a sealing material in an evacuation state and closing the evacuation holes.
This is performed by curing the sealing material.

[0004] Here, the higher the temperature at the time of vacuum evacuation, the better the evacuation efficiency, but if the temperature is such that the sealing material is softened or melted, the inner and outer containers are subjected from the stage of subjecting the sealing material to the evacuation operation. Cannot be placed against It is difficult to place the sealing material later while maintaining the evacuated state. Therefore, conventionally, the evacuation temperature is set to be lower than the softening point of the sealing material, and then the encapsulation process is performed by raising the temperature to a temperature at which the sealing material softens or melts while maintaining the evacuation state. To be.

Japanese Patent Application Laid-Open No. 06-169850 discloses that a low-temperature molten glass having a softening temperature of 200 ° C. to 600 ° C. is used as a sealing material, and a vacuum exhaust temperature is originally a high-temperature exhaust of about 950 ° C. On the other hand, the exhaust temperature
A technique that can be suppressed to 600 ° C. is disclosed.

This is a low-temperature molten glass of B_TwoO
_Three-PbO system, B_TwoO_Three-ZnO-based, PbO-B_TwoO_Three−
ZnO-SiO_TwoSystem, PbO-B_TwoO_Three-Al_TwoO_Three-S
iO _TwoSystem, PbO-B_TwoO_Three-SiO_TwoSystem, PbO-B_Two
O_Three-Using solder glass such as BaO-SiO2
ing.

As a result, low-temperature exhaustion and low-temperature sealing can be performed, so that the vacuum heating furnace is not special and the cost is reduced. In addition, the metal double container does not oxidize, and the work for removing oxides becomes unnecessary. The wettability of the sealing material with the double container is improved, and the yield is improved. Since the double vessel will be low-temperature annealed,
Hardness is higher than in the case of high temperature annealing. It has such advantages.

On the other hand, in a metal vacuum double container in which at least one surface of the inner and outer containers is coated with fluorine, the fluorine paint firing temperature is as high as about 380 ° C. as shown in FIG. May be. To cope with this, conventionally, a metal vacuum double container coated with fluorine has a N
Sealing treatment is performed using a metal sealing material such as i-wax to prevent the sealing from being broken by high temperatures during the subsequent firing of the fluorine paint.

[0009]

However, when a metal sealing material is used, the sealing treatment temperature becomes as high as about 1010.degree. No benefit from sealing.

Further, even if the above-mentioned conventional glass sealing material having a high-temperature softening point region is employed, since it is mainly composed of lead, it affects human bodies, environment, and equipment. Furthermore, if it is used for a heat-insulating container for food and drink, it is a problem in food hygiene. Conventionally, a sealing treatment section is provided with a seal to prevent concealed water or the like from entering, and to prevent lead from being eluted by the entered water, but it takes time and effort. Also, in a vacuum heating furnace that heats in a vacuum and in particular, the metal oxide component in the sealing material, which is particularly softened or melted, evaporates and easily flies, and is included in the exhaust air that is evacuated. Is difficult to completely separate from the operator. For this reason, it is necessary for the worker to take a protective measure using a protective mask or protective clothing, which limits the movement of the worker, which makes the work difficult and reduces the work efficiency. In addition, it is necessary to completely remove lead components and the like in the exhaust gas so as not to pollute the environment. In any case, a large amount of cost is required, which causes an increase in product cost. In addition, lead radiated in the vacuum heating furnace naturally adheres and accumulates on the inner surface of the furnace. The deposited lead is in the state of so-called vapor-deposited plating and is difficult to remove, and it also becomes a secondary source of lead emission, so that the equipment reaches its service life relatively early and requires maintenance and replacement of the equipment. The running cost increases and the product cost is affected.

[0011] Further, even if the stainless steel inner and outer containers sealed with a sealing material containing lead are melted and reused, there is a problem if a large amount of lead remains in the melted stainless steel, which cannot be reused. There is.

Further, in the conventional low melting point glass sealing material,
The coefficient of thermal expansion with stainless steel still has a gap, which hinders further improvement in yield in terms of adhesion and sealing properties.

The main object of the present invention is to provide a low-melting glass sealing material that satisfies at least one of the following: no problem with humans and the environment; no problem with recycling stainless steel; and excellent sealing process yield. And provide a fluorine-coated metal vacuum double container, and furthermore, it has an adverse effect on the human body, environment, and equipment, hinders the reusing of inner and outer containers, prevents adhesion and sealing to stainless steel, Provided are a metal vacuum double container which can solve at least one of the conventional problems such as low retentivity and low product yield, a method of manufacturing the same, and a sealing glass composition usable for these. It is in.

[0014]

In order to achieve the above-mentioned object, a metal vacuum double container of the present invention is provided with a vacuum insulation process between a stainless steel inner and outer container by a vacuum exhaust process through an exhaust hole. A low-melting glass seal having a space and a fluorine coating on at least one surface of the inner and outer containers, wherein an exhaust hole has a softening point higher than a fluorine paint firing temperature and a degassing temperature during vacuum exhaust. One feature is that the low-melting-point glass sealing material does not hinder reuse of the inner and outer containers due to simultaneous melting with the inner and outer containers.

[0015] Accordingly, the low-melting point glass can be reduced in thickness by the amount of work hardening due to being evacuated and sealed in a lower temperature range than the metal sealing material corresponding to the low-melting point glass sealing material and not being annealed. Since the softening point of the sealing material is higher than the degassing temperature, softening, melting and deformation during the degassing operation, the sealing process is reliably achieved without flowing, etc.,
It is possible to provide a fluorine-coated metal vacuum double container without breaking the sealing by being higher than the fluorine coating firing temperature, compared to the conventional one that uses a metal sealing material for fluorine coating. Weight and product cost.

Further, it is conceivable to reuse the metal vacuum double container when it is discarded for reasons such as deformation, damage, fouling, discoloration, malfunction, and outdated fashion. For this purpose, the stainless steel material of the discarded metal vacuum double container is once melted, but if a conventional glass sealing material containing lead is used, if this remains in the dissolved stainless steel component, It becomes a problem due to the effects on food hygiene, the environment, and equipment, and cannot be reused.

However, by forming a stainless steel vacuum double container using a low-melting-point glass sealing material containing substantially no lead, it is difficult to dissolve and reuse the stainless steel material of the inner and outer containers. Contributes to resource saving and product cost reduction. Here, the phrase "substantially free of lead" means that a raw material containing lead as a main component such as PbO is not used at all, and a trace amount of lead derived from impurities in the raw material of each component constituting glass is reduced. It does not exclude mixed glass.

Further, lead causes a problem in food hygiene together with other heavy metals and the like, but the low-melting glass sealing material sealing the exhaust hole of the present invention does not contain any component having a problem in food hygiene. It is also characterized. Thus, there is no problem when the metal vacuum double container is used for eating and drinking, such as an electric pot, a portable heat-insulating bottle, a lunch jar, a heat-insulating cooking pot, and a mug. Therefore, in the conventional low melting point glass sealing material having a problem in food hygiene, the sealing position is limited to a part of the outer container, and the degree of freedom in selecting the sealing position is reduced by half, and even the sealing position in the outer container is exposed to water or hot water. The lead component is eluted, or there is a problem that it takes time and effort to seal and prevent harm by touching people, but with low melting glass sealing materials that do not substantially contain lead, These problems are solved, and safety of use and cost reduction can be achieved. At the same time, in the sealing process in a vacuum heating furnace, lead harmful to humans, the environment, and equipment will not emanate around, eliminating the need for countermeasures such as when lead emanate, and extending equipment life. Therefore, a metal vacuum double container can be easily and inexpensively manufactured.

The low-melting-point glass sealing material capable of coping with the above-mentioned fluorine coating, food hygiene, and dissolution and reuse of stainless steel has a smaller coefficient of thermal expansion than that of stainless steel and a difference in coefficient of thermal expansion of 25 × 10 ^−7. It is also characterized by having a coefficient of thermal expansion of / K or less. As a result, the low-melting-point glass sealing material is compressed at the exhaust holes of the inner and outer containers by the difference in shrinkage during cooling due to the thermal expansion coefficient being smaller than the thermal expansion coefficient of stainless steel, thereby enhancing mutual adhesion. However, since the difference in thermal expansion coefficient between the two is small, the compression does not cause a problem such as peeling, so that the sealing property is improved and the yield of the product in the sealing treatment is improved.

If the stainless steel is a martensitic stainless steel, there is an advantage that the stainless steel is not sensitized to low-temperature exhaust and low-temperature sealing at a temperature higher than the fluorine paint firing temperature.

The low-melting glass sealing material becomes substantially lead-free.
Bismuth-based glass satisfies all of the above characteristics,
Bi_TwoO_Three70 to 90 wt%, ZnO 0 to 2 wt%
%, B _TwoO_ThreeFrom 5 to 29 wt%, SiO_Two1 to 15w
t%, Al_TwoO_Three0 to 10 wt%, and CuO from 0 to 10 wt%.
% by weight. In this case, the
Metal such as Al other than stainless steel and ceramics
Sealing material or glass composition for sealing
Is also effective.

As described above, CuO may not be essential, but 70 to 90 wt% of Bi ₂ O ₃ , 0 to ₂ wt% of ZnO, 5 to 28 wt% of B ₂ O ₃ and 1 to ₂ wt% of SiO ₂ . 15 wt%, 0-10 wt% of Al ₂ O _3, CuO
It was intended to include 0.5~6wt%, a B ₂ O ₃ 5 to 28
If CuO is made essential, for example, by being slightly suppressed to wt%, the adhesion to metal can be particularly improved.

In order to produce a metal vacuum double container exhibiting the above-mentioned characteristics, a low-melting-point glass sealing material is passed through an exhaust hole between the inner and outer containers made of stainless steel using the above-mentioned materials. After evacuating and degassing at a temperature lower than the softening point, the low-melting glass sealing material is softened or melted at a temperature equal to or higher than the softening point in this evacuated state to seal the exhaust holes. I just need.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings to facilitate understanding of the present invention.

In this embodiment, an electric pot B as shown in FIG.
This is an example of a case in which the metal vacuum double container A constituting the above is formed from a stainless steel plate and manufactured. However, any form and application may be used in which the inner and outer containers 1 and 2 are combined and the vacuum heat insulating space 3 is provided between them. Further, the metal vacuum double container itself may be formed by joining the inner and outer containers 1 and 2 in any unit or integrally formed.

In the electric pot B of this embodiment, a metal vacuum double container A is housed in a synthetic resin outer case 21 to form a vessel 23, and the outer case 21 and the metal vacuum double container A
The synthetic resin shoulder member 22 provided between the upper end of the container and the container 23 forms a container opening 25 communicating with the mouth portion 24 of the metal vacuum double container A of the container 23, and the cover 26 of the container 23 is attached to the rear part. At the hinge pin 27 so that it can be opened and closed. A heater 29 is applied to the single bottom portion 28 of the metal vacuum double container A to heat the content liquid. The electric pump 31 is provided on the single bottom portion 28 of the metal vacuum double container A.
A discharge path 32 for discharging the content liquid to the outside is connected through the connection. A manual pump 33 is provided in the lid 26 to pressurize and extrude and discharge the content liquid through the discharge path 32. The lid 26 is provided with a metal inner lid 34 for closing the opening 24 of the metal vacuum double container A, and a vapor passage 35 for releasing vapor to the outside. An operation panel 36 is provided on the upper surface of the protruding portion 22a protruding from the front portion of the shoulder member 22, and the discharge port 32a of the discharge path 32 faces the lower surface of the protruding portion 22a and opens downward.

The metal vacuum double container A is subjected to a degassing operation in which the space between the inner and outer containers 1 and 2 is evacuated through the exhaust hole 41 shown in FIG.
1 has been sealed. After the sealing process, a fluorine coating layer 37 as shown in FIGS. 1 and 2 is provided on the surface of the inner container 1 of the metal vacuum double container A, that is, on the inner peripheral surface. The metal vacuum double container A may constitute an electric pot or a heat retaining bottle in which the metal double container A is exposed. In this case, the surface of the outer container 2, that is, the outer peripheral surface may be coated with fluorine. . As an example, the exhaust hole 41 is formed at the innermost part of the dome-shaped recess 40 in the outer container 2, and the inner and outer containers 1,
2 is such that the sealing material is stably positioned in the dent 40 when the vacuum evacuation is performed with the dent 40 facing upward, and the sealing material naturally flows into the exhaust hole 41 when softened or melted after the evacuation. When the air is cooled and solidified, the closing of the exhaust hole 41 is completed. A getter 42 as a degassing agent is provided in the vacuum heat insulating space 3 thus formed, and absorbs a gas generated with time in the vacuum heat insulating space 3 to maintain a predetermined degree of vacuum. .

Fluorine coating is performed by carrying a baking process by conveying the inside of a furnace set at about 385 ° C. after the coating film is formed, and following the temperature change as shown in FIG. It is kept at a high temperature.

In order to perform the sealing process, the metal vacuum double container A of the present embodiment has a temperature lower than that of the conventional metal sealing material because the sealing is not broken even by the fluorinated paint firing temperature. A low-melting-point glass sealing material 43 that can be softened or melted to perform low-temperature exhaust and low-temperature sealing is used. In other words, the vacuum insulation space 3 is formed between the inner and outer containers 1 and 2 made of stainless steel by vacuum evacuation through the exhaust hole 41, and the fluorine coating layer 37 is applied to at least one surface of the inner and outer containers 1 and 2. , The basic configuration is that the exhaust hole 41 is sealed by a low-melting-point glass sealing material 43 having a softening point higher than the fluorine paint baking temperature and the degassing temperature during evacuation. The low-melting-point glass sealing material 43 can be softened or melted or sealed in a temperature range where sensitization of the inner and outer containers 1 and 2 does not occur and a temperature range where work hardening remains and the thickness of the inner and outer containers 1 and 2 can be suppressed to a small value. The degassing temperature is set lower than that. When a martensitic stainless steel such as SUS436 of JIS is used as the stainless steel, it does not become sensitized even at 600 ° C., and the work hardening can be left as in the case of general stainless steel.

Here, the softening point of the low-melting-point glass sealing material 43 is set to 380 so as not to be affected by the firing temperature of the fluorine paint.
It is necessary to be higher than or equal to about 600C. From the viewpoint of the degassing efficiency by vacuum evacuation, the degassing temperature is 45 degrees below 600 ° C., which is the upper limit of the softening point of the low-melting glass sealing material 43.
It is preferable to set the temperature to about 0 ° C. or more and less than 600 ° C.
Therefore, the practical softening point range of the low melting point glass sealing material 43 is up to about 450 ° C. to 600 ° C., and the low melting point glass sealing material 43 is set at a temperature higher than the fluorine paint firing temperature and higher than the degassing temperature. To be satisfied.

As a result, the metal vacuum double container A of the present embodiment is subjected to vacuum evacuation and sealing at a temperature lower than that of the metal sealing material corresponding to the low melting point glass sealing material 43, and the work hardening by not being annealed. Since the softening point of the low-melting glass sealing material 43 is higher than the degassing temperature while softening, melting and deforming during the degassing operation, the sealing treatment is reliably performed without any loss, etc. Achieved, it is possible to provide a fluorine-coated metal vacuum double container without breaking the seal by being higher than the fluorine paint firing temperature, the conventional using a metal sealing material for fluorine coating Lighter weight and product cost are reduced as compared to those of products.

By the way, it is conceivable to reuse a metal vacuum double container when it is discarded due to deformation, scratching, fouling, discoloration, malfunction, delay of fashion, or the like. For this purpose, the stainless steel material of the discarded metal vacuum double container is once melted, but if a conventional glass sealing material containing lead is used, if this remains in the dissolved stainless steel component, It becomes a problem due to the effects on food hygiene, the environment, and equipment, and cannot be reused.

However, in this embodiment, the use of the low-melting-point glass sealing material 43 containing substantially no lead does not prevent the stainless steel material of the inner and outer containers from being melted and reused, thereby saving resources. Contribute to reducing product costs.

Although lead causes a problem in food hygiene together with other heavy metals, the low-melting-point glass sealing material 43 sealing the exhaust hole 41 of this embodiment is composed of lead and other components having a problem in food hygiene. Is not included. Thus, there is no problem when the metal vacuum double container A is used for eating and drinking, such as an electric pot, a portable heat retaining bottle, a lunch jar, a heat retaining cooking pot, and a mug. Therefore, in the conventional low-melting glass sealing material having a problem in food hygiene, the sealing position is limited to a part of the outer container 2 and the degree of freedom in selecting the sealing position is halved. The lead component is eluted by touching, and there is a problem that it takes time and effort to seal and prevent harm caused by touching by a person, but the low melting point substantially free of lead in the present example These problems are solved by the glass sealing material 43, and safety in use and cost reduction can be achieved. At the same time, in the sealing process in a vacuum heating furnace, lead harmful to humans, the environment, and equipment will not emanate around, eliminating the need for countermeasures such as when lead emanate, and extending equipment life. Therefore, the metal vacuum double container A can be manufactured easily and inexpensively.

The low-melting-point glass sealing material 43 of the present embodiment capable of coping with the above-mentioned fluorine coating, food hygiene, and melting and reusing stainless steel has a smaller coefficient of thermal expansion than that of stainless steel and has a difference in coefficient of thermal expansion. It has a thermal expansion coefficient of 25 × 10 ⁻⁷ / K or less. As a result, the low-melting glass sealing material 43 receives compression at the exhaust holes of the inner and outer containers due to a difference in shrinkage during cooling due to a thermal expansion coefficient thereof being smaller than a thermal expansion coefficient of stainless steel, thereby improving mutual adhesion. While increasing, the difference in thermal expansion coefficient between the two is small, so that the compression does not cause problems such as peeling, so that the sealing property is improved and the yield of products in the sealing process is improved.

When the stainless steel is a martensitic stainless steel represented by SUS436, there is an advantage that the stainless steel is not sensitized to low-temperature exhaustion and low-temperature sealing at a temperature higher than the calcination temperature of the fluorine paint.

Examples of the low melting point glass sealing material 43 which satisfies the above characteristics, include bismuth glass, Bi ₂ O
_{3, ZnO, B 2 O 3} , SiO 2, Al 2 O 3, CuO
Those having a composition containing

Here, Bi ₂ O ₃ is a glass network former, and is preferably contained in the range of 70 to 90 wt%. If it is less than 70 wt%, the softening point of the glass becomes too high, and there is a possibility that sealing cannot be performed by heat treatment at a temperature of about 600 ° C. or less. In addition, 90wt%
If it exceeds, the glass tends to be devitrified (crystallized) and the glass transition point may be too low. In consideration of the softening point, melting property, and the like of the glass, the content of Bi ₂ O ₃ is more preferably 75 to 86 wt%.

ZnO is a component that is highly effective in reducing the melting of glass, but is a component that has a high vapor pressure and is easily volatilized. Therefore, there is transpiration, especially during heat treatment in a vacuum,
2w to prevent fluctuation of composition and contamination of heat treatment furnace
It is preferably set to t% or less. Considering low melting of the glass, it is desirable that ZnO be contained at 0.5 wt% or more.

B_TwoO_ThreeEven glass network former
And is an essential component for reducing the melting of glass. B_TwoO
_ThreeIs preferably contained in the range of 5 to 29 wt%.
No. B _TwoO_ThreeIs less than 5 wt%, the effect of low melting is small.
Conversely, if it exceeds 29 wt%, the water resistance may deteriorate.
There is. Considering the low melting and water resistance of glass,_Two
O _ThreeIs more preferably 6 to 21 wt%.
No.

SiO _{2 is} also a glass network former, and is an essential component for stabilizing glass. Preferably, SiO ₂ is contained in the range of ₁ to 15 wt%. If the content of SiO ₂ is less than 1% by weight, the effect of stabilizing the glass may be insufficient. Conversely 15wt
%, The softening point is too high, and there is a possibility that the heat treatment at a predetermined temperature makes it impossible to seal and seal. Further, when the base material is a metal such as stainless steel, the coefficient of thermal expansion becomes too small as compared with that of the base material, stress may be generated, and the adhesion may be reduced. Considering glass stabilization, softening point, thermal expansion coefficient, etc., the content of SiO ₂ is ₂ to 10 wt.
% Is more preferable.

Al ₂ O ₃ is a component for preventing the devitrification of the glass and stabilizing the glass. However, if the content exceeds 10 wt%, the softening point is too high, and sealing and sealing are performed by heat treatment at a predetermined temperature. It becomes difficult to do. In consideration of glass stabilization, softening point, and the like, the content of Al ₂ O ₃ is more preferably 1 to 6 wt%.

When the substrate is a metal, particularly stainless steel, CuO can be contained in an amount of 10 wt% or less for the purpose of increasing the adhesion of the glass to the stainless steel substrate. C
If uO exceeds 10% by weight, the softening point may be too low. In consideration of the adhesion to the substrate, the softening point, and the like, the content of CuO is preferably 0.5 to 6 wt%.

From the above, in order for the bismuth-based low-melting-point glass sealing material 43 to satisfy any of the above characteristics, 70 to 90 wt% of Bi ₂ O ₃ , 0 to ₂ wt% of ZnO, and 5 to 5 wt% of B ₂ O ₃ ~29wt%, the SiO ₂ 1~15wt%, Al ₂ O
_It is preferable that the composition contains 0 to 10 wt% of ₃ and 0 to 10 wt% of CuO. In this case, it is also effective as a glass composition to be used as a sealing material for other materials such as metals other than stainless steel such as Al and ceramics. It is.

[0045] Further, although may not be a CuO as essential components as described above, 70～90Wt% of Bi ₂ O _3, Zn
0 to ₂ wt% of O, 5 to 28 wt% of B ₂ O ₃ , SiO
₂ to 1 wt%, Al ₂ O ₃ to 0 to 10 wt%, C
The uO is intended to include 0.5~6wt%, 5~ the B ₂ O ₃
If CuO is made indispensable, for example, by being slightly suppressed to 28 wt%, the adhesion to metal can be particularly enhanced.

Also, Bi ₂ O ₃ is contained in an amount of 70 to 90 wt%,
nO of 0 to ₂ wt%, B ₂ O _{3 of 5} to 23 wt%, Si
O _{2 1} to 10 wt%, Al ₂ O _{3 0} to 6 wt%, C
If uO is contained in an amount of 0.5 to 6 wt%, it is more suitable for sealing and sealing with stainless steel.

Further, Bi ₂ O ₃ is contained in an amount of 70 to 86 wt%,
nO of 0 to ₂ wt%, B ₂ O _{3 of 5} to 21 wt%, Si
₂ to 10 wt% of O ₂ , 0 to 6 wt% of Al ₂ O ₃ , C
If uO is contained in an amount of 0.5 to 6 wt%, it is suitable for stainless steel, particularly martensitic stainless steel.

The low-melting-point glass sealing material 43 in this embodiment.
Is applied to the sealing and sealing of substrates made of various materials,
It is necessary that the thermal expansion coefficients be close to each other, but on the other hand, the sealing and sealing are not broken by the processing temperature required for the base material, and the low melting point glass sealing material 43 is used.
It is also necessary to satisfy a softening point that does not impair the functions of various materials such as a material on the base material side and a semiconductor mounted on the material depending on the sealing and sealing temperatures. In general, increasing the softening point increases the coefficient of thermal expansion.

When a base material is a martensitic stainless steel or a material having an equivalent thermal expansion coefficient, the bismuth-based low-melting glass preferably has a thermal expansion coefficient of 82 to 105 × 10 ⁻⁷ / K. The point is preferably 450 to 550 ° C. Further, the glass transition point is preferably from 370 to 450 ° C.

Table 1 below shows Examples 1 to 6 and one comparative example for the above composition.

[0051]

[Table 1] The measurement of the glass transition point, the glass softening point, the coefficient of thermal expansion, and the evaluation of adhesion, appearance, and sealing property were performed as follows.

The glass transition point and softening point were determined to be about 45
Approximately 80 mg of each powder sample of ~ 75 µm is placed in a platinum microcell of a differential thermal analyzer (DTA),
The measurement was carried out by increasing the temperature to 800 ° C. at a heating rate of / min. The temperature of the shoulder at the end of the endothermic start which appeared first was taken as the glass transition point, and the temperature at which the endothermic end through the minimum point was taken as the softening point.

The coefficient of thermal expansion was measured using a thermomechanical analyzer (TMA).
The sample was processed into a glass rod having a diameter of about 5 mm and a length of 15 to 20 mm using, quartz glass was used as a standard sample, and the temperature was increased from room temperature at a rate of 10 K / min to obtain a TMA. The average value at 30 to 350 ° C. was obtained from the curve.

The adhesion and the appearance were as follows. A glass rod formed into a diameter of about 2 mm and a length of about 6.5 mm was laid on the exhaust port of a stainless steel double container and placed at 600 ° C. for 1 hour.
Heat treatment was performed at a pressure of 1.33 Pa or less for 5 minutes to obtain a sealed state and evaluated. The adhesion was evaluated based on whether the glass flowed and adhered to the exhaust port, and the appearance was visually evaluated. The appearance is mainly determined by the presence and degree of devitrification and bubbles. The sealing property was evaluated based on the presence or absence and degree of vacuum leakage due to peeling of the glass sealing material after firing of the fluorine paint at 400 ° C. and slipping into the exhaust port. In each of the evaluations, good was evaluated as ○, slightly poor as Δ, and poor as ×.

Here, the glass transition point, the glass softening point, and the thermal expansion coefficient of the conventional low melting glass sealing material, which is lead glass, are shown in Table 2 below.

[0056]

[Table 2] In addition, JI used for conventional stainless steel bottles
Table 3 below shows a comparison between the thermal expansion coefficients of the S standard SUS304 and the SUS436 used in the present example.

[0057]

[Table 3] In order to manufacture the metal vacuum double container A exhibiting the above-described characteristics, the material in each of the above cases is used, and as shown in FIG. After evacuation and degassing at a temperature lower than the softening point of the low-melting glass sealing material 43, for example, 450 ° C., the low-melting glass sealing material 43 is heated to a temperature higher than the softening point in this evacuated state. For example, the exhaust holes 41 are softened or melted at 600 ° C. to close the exhaust holes 41, and then the fluorine paint is baked at about 380 ° C. to form the fluorine coating layer 37, and there is no problem.

More specifically, as shown in FIG. 1, a low-melting glass sealing material 43 is placed in a recess 40 of the inner and outer containers 1 and 2 to prepare a preparation chamber, a first degassing chamber to a third degassing chamber. Passing sequentially at a constant speed for 30 minutes, successively at a constant speed for about 15 minutes in the next brazing chamber and about 1 hour in the subsequent cooling chamber without heater, the final N ₂ In the gas cooling chamber, the gas is passed at a constant speed in about 40 minutes. At this time, in the preparation room, the temperature is raised from room temperature to 430 ° C. and kept at that temperature. In the next first degassing chamber, the temperature is raised to 450 ° C. at an early stage and then maintained at that temperature. The above 450 ° C. is maintained in the second degassing chamber and the third degassing chamber. During this time, the first to third degassing chambers are set to a predetermined degree of vacuum, for example, a pressure of 1.33 Pa or less, and the space between the inner and outer vessels 1 and 2 is evacuated to a pressure of 1.33 Pa or less. In the brazing chamber, the low-melting glass sealing material 43 is softened or melted at a sealing temperature of about 600 ° C. while maintaining the same pressure state as the previous chamber at a sealing temperature of about 600 ° C., and the exhaust hole 41 is sealed to form a vacuum insulating space 3. Form. After the sealing process, the temperature is reduced to about the temperature at the time of evacuation by natural cooling in a slow cooling chamber without a heater, and then forcedly cooled to about normal temperature in a N ₂ gas chamber. The temperatures in parentheses in FIG. 3 indicate a series of processing temperatures when a conventional low-melting glass sealing material is used. The metal vacuum double container A sealed in this way is coated with fluorine and baked while being conveyed at a constant speed by a conveyor in a heating furnace maintained at about 385 ° C. as shown in FIG. The layer 37 is formed. The baking time is about 30 minutes, and the metal vacuum double container A is kept at about 380 ° C. for about 17 minutes in the latter half.

[0059]

According to the present invention, the thickness of the work hardened portion can be reduced by performing vacuum evacuation and sealing at a lower temperature range than a metal sealing material corresponding to a low melting point glass sealing material and not annealing. However, since the softening point of the low-melting glass sealing material is higher than the degassing temperature, the sealing process is reliably achieved without softening, melting and deformation during the degassing operation, etc., and is higher than the fluorine paint firing temperature. As a result, it is possible to provide a fluorine-coated metal vacuum double container without destroying the seal, and to reduce the weight and product cost compared to the conventional one using a metal sealing material for fluorine coating. Is reduced.

Further, it is conceivable to reuse the metal vacuum double container when it is discarded due to deformation, scratching, fouling, discoloration, malfunction, delay of fashion, or the like. For this purpose, the stainless steel material of the discarded metal vacuum double container is once melted, but if a conventional glass sealing material containing lead is used, if this remains in the dissolved stainless steel component, It becomes a problem due to the effects on food hygiene, the environment, and equipment, and cannot be reused.

However, the use of a stainless steel vacuum double container using a low-melting glass sealing material substantially free of lead prevents melting and reuse of the stainless steel material of the inner and outer containers. Contributes to resource saving and product cost reduction.

Further, lead causes a problem in food hygiene together with other heavy metals and the like, but the low-melting-point glass sealing material sealing the exhaust hole of the present invention does not contain any component having a problem in food hygiene. It is also characterized. Thus, there is no problem when the metal vacuum double container is used for eating and drinking, such as an electric pot, a portable heat-insulating bottle, a lunch jar, a heat-insulating cooking pot, and a mug. Therefore, in the conventional low melting point glass sealing material having a problem in food hygiene, the sealing position is limited to a part of the outer container, and the degree of freedom in selecting the sealing position is reduced by half, and even the sealing position in the outer container is exposed to water or hot water. The lead component is eluted, or there is a problem that it takes time and effort to prevent harm by touching with a person, but the low melting point glass sealing of the present invention substantially containing no lead. The material solves these problems, and can be used safely and reduce costs. At the same time, in the sealing process in a vacuum heating furnace, lead harmful to humans, the environment, and equipment will not emanate around, eliminating the need for countermeasures such as when lead emanate, and extending equipment life. Therefore, a metal vacuum double container can be easily and inexpensively manufactured.

The low-melting-point glass sealing material capable of coping with the above-mentioned fluorine coating, food hygiene, and dissolution and reuse of stainless steel has a thermal expansion coefficient smaller than that of stainless steel and a difference in thermal expansion coefficient of 25 × 10 ^−7. It is also characterized by having a coefficient of thermal expansion of / K or less. As a result, the low-melting-point glass sealing material is compressed at the exhaust holes of the inner and outer containers by the difference in shrinkage during cooling due to the thermal expansion coefficient being smaller than the thermal expansion coefficient of stainless steel, thereby enhancing mutual adhesion. However, since the difference in thermal expansion coefficient between the two is small, the compression does not cause a problem such as peeling, so that the sealing property is improved, and the yield of the product in the sealing process is also improved.

When the stainless steel is a martensitic stainless steel, there is an advantage that the stainless steel is not sensitized to low-temperature exhaustion and low-temperature sealing at a temperature higher than the fluorine paint firing temperature.

The low-melting glass sealing material becomes substantially lead-free.
Bismuth-based glass satisfies all of the above characteristics,
Bi_TwoO_Three70 to 90 wt%, ZnO 0 to 2 wt%
%, B _TwoO_ThreeFrom 5 to 29 wt%, SiO_Two1 to 15w
t%, Al_TwoO_Three0 to 10 wt%, and CuO from 0 to 10 wt%.
% by weight. In this case, the
Metal such as Al other than stainless steel and ceramics
Glass composition which is also effective as a sealing material for various materials
Things are obtained.

As described above, CuO may not be essential, but 70 to 90 wt% of Bi ₂ O ₃ , 0 to ₂ wt% of ZnO, 5 to 28 wt% of B ₂ O ₃ and 1 to ₂ wt% of SiO ₂ . 15 wt%, 0-10 wt% of Al ₂ O _3, CuO
It was intended to include 0.5~6wt%, a B ₂ O ₃ 5 to 28
If CuO is made essential, for example, by being slightly suppressed to wt%, the adhesion to metal can be particularly improved.

In order to manufacture a metal vacuum double container exhibiting the above-mentioned characteristics, a low-melting-point glass sealing material is formed between the inner and outer containers made of stainless steel through the exhaust holes using the materials in the above cases. After evacuating and degassing at a temperature lower than the softening temperature and performing degassing, in this evacuated state, the low melting glass sealing material is softened or melted at a temperature equal to or higher than the softening point and the exhaust hole is sealed. Good.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bottom portion showing an example of an electric pot of a metal vacuum double container obtained in an embodiment of the present invention.

FIG. 2 is an overall sectional view of the electric pot of FIG.

FIG. 3 is a graph showing the relationship between the temperature and the processing time when the metal vacuum double container of FIG. 1 is manufactured by evacuating and closing the container in comparison with the conventional case.

FIG. 4 is a graph showing a temperature change in a case where a fluorine paint is applied to a metal vacuum double container that has been subjected to a sealing treatment and baking treatment is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner container 2 Outer container 3 Vacuum insulation space 41 Exhaust hole 43 Low melting glass sealing material

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) C03C 8/02 C03C 8/02 8/04 8/04 (72) Inventor Yoshihiro Asano Hamamatsubara-cho, Nishinomiya-shi, Hyogo Prefecture No. 21 in Nihon Yamamura Glass Co., Ltd. (72) Inventor Yoshinori Tanigami No. 21 in Hamamatsubara-cho, Nishinomiya-shi, Hyogo F-term in Nihon Yamamura Glass Co., Ltd. 3E067 AB01 BA01 BB11 EE49 EE60 FC01 GA13 4B002 AA01 BA22 CA32 4G061 AA02 BA00 CA03 CC03 CD16 DA26 4G062 AA08 AA09 BB07 DA03 DA04 DB01 DB02 DB03 DC03 DC04 DD01 DE01 DE02 DE03 DF01 EA01 EB01 EC01 ED01 EE01 EF00 EG00 FA00 FA10 FB00 FC00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 HH03 HH04 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM08 MM09 NN40

Claims (10)

[Claims] A metal vacuum double container in which a space between stainless steel inner and outer containers is made into a vacuum insulated space by vacuum evacuation processing through an exhaust hole, and at least one surface of the inner and outer containers is coated with fluorine. Exhaust holes are sealed with a low-melting glass sealing material that has a softening point higher than the fluorine paint baking temperature and degassing temperature during vacuum evacuation and does not hinder reuse of the inner and outer containers by simultaneous melting with the inner and outer containers. A vacuum double container made of metal. 2. A metal vacuum double container in which a space between stainless steel inner and outer containers is made into a vacuum insulated space by vacuum exhaust processing through an exhaust hole and at least one surface of the inner and outer containers is coated with fluorine. It has a softening point higher than the fluorine paint baking temperature and the degassing temperature during evacuation, and the exhaust holes are sealed with a low-melting glass sealing material that does not contain ingredients that are problematic for food hygiene. Metal vacuum double container. 3. A metal vacuum double container in which a space between stainless steel inner and outer containers is made into a vacuum insulated space by vacuum evacuation through an exhaust hole, and at least one surface of the inner and outer containers is coated with fluorine. A metal having a softening point higher than a fluorine paint firing temperature and a degassing temperature during vacuum evacuation, and an exhaust hole is sealed by a low-melting glass sealing material containing substantially no lead. Vacuum double container. 4. A metal vacuum double container in which a space between stainless steel inner and outer containers is made into a vacuum insulated space by vacuum evacuation through an exhaust hole, and at least one surface of the inner and outer containers is coated with fluorine. It has a softening point higher than the fluorine paint firing temperature and the degassing temperature during evacuation, is smaller than the thermal expansion coefficient of stainless steel, and has a thermal expansion coefficient difference of 25 × 10 ⁻⁷ / K or less. A vacuum double container made of metal, wherein an exhaust hole is sealed by the low-melting glass sealing material. 5. The metal vacuum double container according to claim 1, wherein the low-melting glass sealing material is a bismuth-based glass. 6. The metal vacuum double container according to claim 1, wherein the stainless steel is martensitic stainless steel. 7. Bi_TwoO_Three70-90 wt%, ZnO
0 to 2 wt%, B _TwoO_ThreeFrom 5 to 29 wt%, SiO_Two
From 1 to 15 wt%, Al_TwoO_ThreeFrom 0 to 10 wt%, Cu
A sealing glass composition containing 0 to 10% by weight of O. 8. Bi_TwoO_Three70-90 wt%, ZnO
0 to 2 wt%, B _TwoO_Three5 to 28 wt%, SiO_Two
From 1 to 15 wt%, Al_TwoO_ThreeFrom 0 to 10 wt%, Cu
A sealing glass composition containing 0.5 to 6% by weight of O. 9. The vacuum double container made of metal according to claim 1, wherein a vacuum is evacuated between the inner and outer containers made of stainless steel at a temperature lower than the softening point of the low-melting glass sealing material through an exhaust hole. After degassing, in this evacuated state, the metal vacuum double container is characterized in that the low-melting glass sealing material is softened or melted at a temperature equal to or higher than the softening point and the exhaust hole is sealed. Production method. 10. The method for producing a metal vacuum double container according to claim 9, wherein the glass composition for sealing according to any one of claims 7 and 8 is used as a low-melting glass sealing material.