JPH0352973B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a vacuum double container made of stainless steel. Traditionally, glass containers with a vacuum double wall structure have been widely used as thermos flasks and other heat-insulating containers, but in recent years they have been
Vacuum double containers using stainless steel and other metal materials have been proposed. Among these metal materials, stainless steel has the advantage of excellent corrosion resistance and strong mechanical strength, but like other metal materials, when the space formed between the inner container and the outer container is placed in a high vacuum, In addition to the problem of releasing gas from the inside and gradually reducing the degree of vacuum, even if you try to form a silver mirror plating like a glass vacuum double container to prevent heat loss due to radiation, it will cause a direct silver mirror reaction on the stainless steel surface. It was impossible to do so. In order to prevent heat loss due to gas release and radiation from the inside of the stainless steel to the vacuum space, for example, Japanese Patent Publication No. 57-22571 proposes that metal inner and outer parts be used to form the space of the vacuum double container. A structure in which a vitreous layer containing silicon dioxide as the main component is formed on the surface of the bottle, and a silver mirror layer is laminated on the vitreous layer is also disclosed in JP-A-57-75621 to form a space. A structure has been proposed in which the surfaces of the inner and outer bottles are coated with nickel plating, and a silver mirror layer is laminated on top of that. These vacuum double containers can obtain sufficient heat retention power for practical use due to the action of the glass layer or nickel plating layer and silver mirror layer, but in order to maintain the heat retention power over a long period of time, it is necessary to use the vacuum double container. It is required to be placed within the space of The usual source for this purpose is
Non-evaporable materials, such as Zr-Al alloy getters, are used, but their gas adsorption performance deteriorates when they are left in the atmosphere or come into contact with water, so the container parts are coated with silver mirror plating. It has to be installed immediately before welding, which complicates the manufacturing process of the vacuum double container and causes an increase in manufacturing costs. That is, when manufacturing a stainless steel vacuum double container with the above structure, first, the constituent parts of the vacuum double container, such as the inner container, the outer container shoulder member, the outer container body member, the outer container bottom member, etc. are made of stainless steel plates. Then, after forming a nickel plating on the outer surface of the part on which the silver mirror layer is to be formed, for example, the inner container, and welding the inner container and the shoulder member of the outer container at their necks, the shrink tube or Temporarily assemble the inner container, outer container body member, and outer container bottom member using a rubber ring, etc. to make a double container, and fill the space between the inner container and the outer container of the double container with silver mirror plating liquid. After forming a silver mirror layer, washing with water and drying, it is again disassembled into an inner container with an outer container shoulder member, an outer container body member, and an outer container bottom member, and some of the parts, for example, the inside of the outer container body member After that, all these parts were welded together to form a double container, and the air was evacuated from the space between the inner and outer containers using a vacuum pump through a chip pipe installed in the bottom of the outer container. Seal and cut the chip tube, then heat the getter attachment part to approximately 900℃.
A manufacturing method has been adopted which consists of heating to activate the getters. Therefore, in this method, in order to attach the getter later, it is essential to perform silver mirror plating in a temporarily assembled state, and a large number of man-hours are required for temporary assembly and disassembly. An object of the present invention is to provide a method for easily and inexpensively manufacturing a stainless steel vacuum double container with excellent heat retention.
The gist is that it has a double-walled structure consisting of an inner container and an outer container made of stainless steel, and that the space formed between the two containers is a vacuum, and that the surfaces of both the inner and outer containers forming the space are In a method for manufacturing a stainless steel vacuum double container in which a silver mirror layer is formed on at least the outer surface of the body of the inner container, at least the inner container is made of stainless steel parts for both the inner and outer containers constituting the double container. After firing the body forming part in air or an oxidizing atmosphere to form an oxide film on the space forming surface of the part, the space part of one of the stainless steel parts for both the inner and outer containers is fired. on the forming surface
A Zr-Ni-Nb ternary alloy non-evaporable getter is attached, and this part is welded together with other parts to form a double container, and then a silver mirror plating liquid is introduced into the space of the double container. A method for manufacturing a stainless steel vacuum double container characterized by plating. In an embodiment of the present invention, the getter is
The composition used is 55 to 75% by weight of Zr, 15 to 30% by weight of Ni, 5 to 20% by weight of Nb, and unavoidable impurities. In addition, this Zr−Ni−Nb
Since ternary alloy non-evaporable getters are commercially available, it is practical to use them. Generally, it is impossible to cause a silver mirror reaction with the raw material of stainless steel, but in the present invention, the surface of stainless steel is appropriately oxidized,
A film mainly composed of ferric oxide is formed on the surface, and this film enables a silver mirror reaction on the stainless steel surface.
By using a -Nb ternary alloy non-evaporable getter, it is possible to perform silver mirror plating with the getter attached. That is, the above
The Zr-Ni-Nb ternary alloy non-evaporable getter breaks the conventional wisdom and, for example, even when immersed in water,
In addition, even if immersed in a silver mirror plating solution containing sodium hydroxide, ammonia water, glucose, stannous chloride, and nonionic surfactants, it will be activated and adsorbed as long as it is heated in a vacuum after drying. Moreover, it is activated at a relatively low temperature of 300 to 600°C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described with reference to the accompanying drawings showing an embodiment in which the present invention is applied to a stainless steel thermos flask. In the figure, 1 is an inner bottle made of stainless steel, 2 is an outer bottle made of stainless steel, and both are joined at the mouth part 3 by brazing, welding, or other means to form a double wall structure, and the inner bottle is made of stainless steel. A space 4 formed between the outer bottle 1 and the outer bottle 2 is evacuated and made into a vacuum.
The inner bottle 1 is formed by joining a body member 1a and a bottom member 1b by means such as welding or brazing, and the outer bottle 2 is formed by joining a body member 2a, a bottom member 2b, and a shoulder member 2c. It is formed by twisting.
A tip tube 5 that serves as an exhaust port for evacuating the space 4 is joined to the bottom member 2b of the outer bottle 2 by brazing or the like, and a bottom cover is attached to the bottom member 2b to protect the tip tube 5. 6 is attached with adhesive. On the other hand, in order to improve the heat retention ability of the stainless steel vacuum double container, the walls of the inner and outer bottles forming the space 4, that is, the outer surface of the inner bottle 1 and the inner surface of the outer bottle 2, are coated as shown in FIG. As shown, an oxide film 7 is formed, and a silver mirror layer 8 is laminated thereon. In the illustrated embodiment, the silver mirror layer 8 is formed on the outer surface of the inner bottle and the inner surface of the outer bottle.
The silver mirror layer may be formed only on the outer surface of the inner bottle or only on the outer surface excluding the neck.
This is particularly advantageous in reducing costs in the case of containers with large contents. In addition, in order to maintain heat retention over a long period of time,
A Zr-Ni-Nb ternary alloy non-evaporable getter 9 is attached to the bottom member 2b of the outer bottle 2. According to the present invention, the stainless steel thermos flask having the above structure can be manufactured as follows. That is, first, the inner bottle and outer bottle parts constituting the thermos bottle are molded from stainless steel plates, and the inner bottle parts 1a, 1
b is welded to form the inner bottle 1, and the outer bottle shoulder member 2c is welded to the mouth of the inner bottle 1. Next, the obtained inner bottle 1 with the outer bottle shoulder member is attached to the outer bottle body member 2a and the outer bottle bottom member 2b.
At the same time, it is fired in an oxidizing atmosphere to oxidize the outer surface of the inner bottle 1 and the inner surfaces of the outer bottle forming members 2a, 2b, and 2c, thereby forming an oxide film 7. This firing treatment is usually carried out in the oxidizing atmosphere at 250 to 550°C for 5 to 120 minutes, preferably at 300 to 450°C for 10 to 60 minutes. The degree of oxidation of the stainless steel surface is preferably such that the gloss of the stainless steel surface after firing is 10 to 50 lower than the gloss of the polished surface before firing. This is because oxidation that reduces the gloss level to less than 10 cannot cause a silver mirror reaction on the stainless steel surface, and excessive oxidation that reduces the gloss level to more than 50 makes it difficult to cause a silver mirror reaction. This is because. The reason why this phenomenon occurs is that in unfired or similar conditions, the silver mirror reaction is inhibited by chromic oxide that coexists with ferric oxide, and if it is excessively oxidized, ferric oxide forms on the surface. It is presumed that this is because chromium oxide ceases to exist and becomes almost only chromium oxide. After forming the oxide film as described above, a Zr-Ni-Nb ternary alloy getter is attached to the inside of the outer bottle body member 2a welded to the inner bottle 1, and then the outer bottle body member 2a is welded to the inner bottle 1.
Then, the outer bottle bottom member 2b is sequentially welded to the shoulder member 2c to complete the outer bottle 2, resulting in a double-walled bottle. Note that the tip tube 5 is previously attached to the outer bottle bottom member 2b by welding or brazing. Thereafter, a silver mirror solution is poured into the space between the inner and outer bottles of this double bottle from the tip tube 5 to form a silver mirror layer 8 on the oxide film 7, but this is done in the same way as when manufacturing a glass thermos flask. It can be formed by That is,
In order to accelerate the silver precipitation rate and to deposit it uniformly, the oxide film is activated by wetting it with an activating solution containing stannous halide as a main component, and then treating it with a silver mirror solution. Although the activation treatment can be omitted, it is desirable to perform it in order to shorten the time required to form the silver mirror layer. Further, as the silver mirror liquid, a silver mirror plating liquid that is commonly used when manufacturing glass thermos flasks may be used. After forming the silver mirror layer, wash the wall of the space with water.
The stainless steel thermos flask is dried, and further heat is applied from the outside to the mounting part of the getter 9 during vacuum treatment to heat it to 300 to 900°C to activate the getter 9, and then the tip tube 5 is melt-sealed. If a bottom cover 6 is fixed to protect and stabilize the tip tube 5, the structure shown in FIG. 1 is obtained. Example Inner bottle 1 made of 0.5mm thick stainless steel plate (SUS304)
At the same time, the shoulder member 2c, body member 2a, and bottom member 2b of the outer bottle 2 are made from 0.6 mm thick stainless steel plates, and the shoulder members 2c of the inner bottle 1 and outer bottle 2 are welded at their mouth parts 3. This was then baked in air at 350°C for 30 minutes. Then 68wt%Zr−22wt%Ni−10wt
After attaching a commercially available Zr-Ni-Nb ternary alloy non-evaporable getter 9 made of %Nb to the inside of the bottom member 2b, the body member 2a and bottom member 2b of the outer bottle 2 are welded to form an integrated assembly. The solid body is welded to the fired inner bottle 1 to form a double wall structure, and an aqueous solution containing 10 ppm of stannous chloride is injected into the space 4 from the chip tube 5 joined to the outer bottle bottom member 2b, and the inner bottle is closed. After activating the outer surface of No. 1 and draining the aqueous solution, it was washed with water. Next, a commonly used silver mirror solution, for example, a silver mirror solution prepared according to the following recipe, is transferred from the tip tube 5 into the space 4, and the double bottle is held horizontally in the axial direction, as in the case of a glass thermos flask. A silver mirror was deposited by injection while rotating at a high speed to form a silver mirror layer 8 shown in FIG. 2. After that, it was washed with water and dried in the same manner as for a glass thermos flask, and then the outer surface of the getter attachment was heated to about 450°C while reducing the pressure in the space 4 to a degree of vacuum of about 10 ^-3 to 10 ^-4 Torr using a vacuum pump. The getter was activated, the tip tube 5 was melt-sealed, and the bottom cover 6 was fitted and secured to obtain the stainless steel thermos flask shown in FIG. 1. Its content is 0.75. (Prescription of silver mirror solution) Dissolve 10g of silver nitrate in a small amount of water and add 28%
Aqueous solution made by adding 500ml of ammonia water and water to make 4800ml, and further dissolving 10g of sodium hydroxide.
Add 200ml to make the total volume 5000ml, and use this as Solution A. Separately, 0.25 ml of concentrated nitric acid was added to an aqueous solution of 20 g of sucrose dissolved in 50 ml of water and boiled. After adding 5 ml of a 37% formaldehyde aqueous solution to this,
Add water to bring the total volume to 5000ml, and use this as Solution B. The above liquid A and liquid B are mixed at a volume ratio of 1:1 to obtain a silver mirror liquid. In order to examine the heat retention ability of the thermos according to the present invention obtained in this manner, measurements were made under the following conditions using the test method specified in JIS2005, and the heat retention effect for 6 hours and 24 hours was 84℃ and 62℃, respectively. Ta. By the way, when nickel plating was applied instead of the oxide film, the heat retention performance was 80℃ and 56℃ under the same conditions.
From this, it can be concluded that the vacuum double container manufactured by the method of the present invention has better heat retention than the conventional vacuum double container that has a nickel plating formed on the surface of stainless steel and a silver mirror layer formed thereon. I understand. [Test conditions] Pouring temperature: 95°C Hot water amount: Full Plug: Sealed plug (45mmφ) Ambient temperature: 20°C The gloss level of the outer surface of the inner bottle after buffing and degreasing was 122, and the gloss level after firing was 122. The gloss level was 101, which was 21 points lower than before firing. This gloss value is
Based on the measurement method specified in JIS Z8741, the angle of incidence is
60°, the standard sample's glossiness is 91.1, which is 1/4 of that, 22.8.
This is the value obtained by setting . Separately, 0.3 mm thick stainless steel (SUS304) specimens were fired under the various firing conditions shown in Table 1, and then their gloss levels were measured. . The results are also shown in Table 1.

[Table] Furthermore, in order to investigate whether or not the gettsuta that had been wetted with the silver mirror plating liquid had lost its function, the thermos produced in the above example was used for one month, and then
After disassembling and removing the gettuta, we investigated the remaining absorption capacity of the gettuta by absorbing H ₂ and CO gas.
60% of _H2 and 40% of CO remained, which were the same as those taken out from a thermos produced by the conventional method. As is clear from the above description, according to the present invention, by using the Zr-Ni-Nb ternary alloy getter, there is no need to attach the getter after silver mirror plating, and therefore a temporary assembly process is no longer necessary, and manufacturing It is possible to greatly simplify the process. Also,
In order to form a silver mirror layer on the stainless steel surface, instead of glass or nickel plating as an adhesive layer interposed between the two, an oxide film can be used to further improve heat retention, and at the same time There is no need for complicated processes such as those required for forming layers or nickel plating layers, and the silver mirror layer can be formed by simply firing, and the silver mirror layer can be formed by electroless plating, improving workability and making it possible to manufacture at low cost. Excellent effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a stainless steel thermos flask showing an embodiment of the present invention, and FIG. 2 is an enlarged view of section A in FIG. 1. 1...Inner bottle, 2...Outer bottle, 4...Space, 5...
...Chip tube, 6...Bottom cover, 7...Oxide coating,
8...Silver mirror layer.

Claims (1)

[Claims] 1. It has a double wall structure consisting of an inner container and an outer container made of stainless steel, and a space formed between the two containers is a vacuum, and both the inner and outer containers forming the space are In a method for manufacturing a vacuum double container made of stainless steel in which a silver mirror layer is formed on at least the outer surface of the body of the inner container among the container surfaces, among the stainless steel parts for both the inner and outer containers constituting the double container. After firing at least the body forming part of the inner container in air or an oxidizing atmosphere to form an oxide film on the space forming surface of the part, one of the stainless steel parts for both the inner and outer containers. Zr−Ni− on the space forming surface of
A Nb ternary alloy non-evaporable getter is installed, the part is welded with other parts to form a double container, and then a silver mirror plating liquid is introduced into the space of the double container to perform silver mirror plating. A manufacturing method for a stainless steel vacuum double container. 2. The method according to claim 1, wherein the getter is a ternary alloy non-evaporable getter comprising 55 to 75% by weight of Zr, 15 to 30% by weight of Ni, 5 to 20% by weight of Nb, and inevitable impurities.