JPS6237974B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a stainless steel vacuum double container. Traditionally, vacuum double-walled glass containers have been commonly used as thermos flasks and other heat-insulating containers, but in recent years, these containers have become less resistant to mechanical shock.
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, it is impossible to cause a silver mirror reaction even if you try to form a silver mirror plating like in a glass vacuum double container to prevent heat loss due to radiation. It was hot. For the purpose of preventing heat loss due to gas release and radiation from inside this stainless steel to the vacuum space, for example,
Publication No. 22571 discloses a structure in which a vitreous layer containing silicon dioxide as a main component is formed on the surface of the inner and outer metal bottles that form the space of the vacuum double container, and a silver mirror layer is laminated on the vitreous layer. , also published in 1987-
No. 75621 proposes a structure in which nickel plating is applied to the surfaces of the inner and outer bottles that form the space, and a silver mirror layer is laminated thereon. 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 Non-evaporable materials such as Zr-Al alloy getters are usually used as getters for this purpose, but their gas adsorption performance deteriorates when they are left in the atmosphere or come into contact with water. Therefore, it has to be installed immediately before welding the container parts, 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, the shoulder member, the outer container body member, and the outer container bottom member, are manufactured using stainless steel plates. and then 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, welding the inner container and the shoulder member of the outer container at their necks, and then attaching the shrink tube. 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 apply silver mirror plating liquid to the space between the inner container and outer container of the double container. After putting it in and forming a silver mirror layer, washing with water and drying,
The inner container with the outer container shoulder member, the outer container body member, and the outer container bottom member are disassembled again, a getter is attached to one of the parts, for example, the inside of the outer container body member, and then all these parts are welded. After evacuating air from the space between the inner and outer containers with a vacuum pump through a tip tube provided in advance on the bottom member of the outer container, the tip tube was sealed and cut, and then the getter attachment part was removed. about
The manufacturing method used is to activate the getters by heating them to 900°C. 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.
Its gist is that it has a double wall structure consisting of an inner container and an outer container made of stainless steel, a space formed between the two containers is a vacuum, and at least one of the surfaces of both containers forming the space is In a method for manufacturing a stainless steel vacuum double container in which a silver mirror layer is formed on the outer surface of the body of the inner container, Zr-V-Fe is applied to the space forming surface of one stainless steel component constituting the double container.
A ternary alloy non-evaporable getter is installed, the parts are welded together with other stainless steel parts to form a double container, and then silver mirror plating liquid is introduced into the space between the inner and outer containers of the double container. The present invention provides a method for manufacturing a vacuum double container made of stainless steel, which is characterized by silver mirror plating. That is, the present invention breaks the conventional wisdom and shows that the Zr-V-Fe ternary alloy non-evaporable getter can be immersed in water even if it is immersed in water.
Even if it is immersed in a silver mirror plating solution containing ammonia water, glucose, stannous chloride, nonionic surfactants, etc., it will be activated and its adsorption ability will not be impaired as long as it is heated in a vacuum after drying. , and
It was discovered that it has the property of being activated at a relatively low temperature of 300 to 600°C, and was completed based on this knowledge. The Zr-V-Fe ternary alloy non-evaporable getter used is Zr45~75% by weight, V20~50% by weight, Fe5~
Those having a component composition of 35% by weight are preferred. This is because if Zr is outside the above range, the alloy will release hydrogen when water is adsorbed, or the plasticity will become too high, making it difficult to make the alloy into fine powder. Further, if V is less than 20% by weight, the desired gas sorption ability cannot be obtained, and if it exceeds 50% by weight, spontaneous ignition becomes high and it is not practical. Further, Fe is added to reduce spontaneous ignition, and if it is less than 5% by weight, this effect cannot be obtained, and if it exceeds 35% by weight, the sorption performance will decrease. In a preferred embodiment of the invention, an oxide layer is formed on the surface of the stainless steel component on which the silver mirror layer is to be formed, before the getter is attached. It is impossible to cause a silver mirror reaction with the raw material of stainless steel, but when the surface is oxidized to an appropriate degree, a film mainly composed of ferric oxide is formed on the surface, and this film causes a silver mirror reaction. This is based on new knowledge that makes it possible. This oxidized layer is preferably formed by firing the stainless steel component in air or in an oxidizing atmosphere. In another embodiment, the surface of the component on which the silver mirror layer is to be formed is nickel plated instead of forming the oxide layer, although this increases the cost. 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-V-Fe ternary alloy non-evaporable getter 9 is attached to the body member 2a 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 when unfired or in a state close to this, the silver mirror reaction is inhibited by chromic oxide that coexists with ferric oxide, and when oxidized excessively, ferric oxide is present on the surface. It is presumed that this is because the chromium oxide becomes almost exclusively chromium oxide. After forming the oxide film as described above, a Zr-V-Fe ternary alloy non-evaporable 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 and The outer bottle bottom member 2b is sequentially welded to the shoulder member 2c to complete the outer bottle 2, making it a double-walled bottle. Note that a tip tube 5 is attached to the outer bottle bottom member 2b in advance.
Attach 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 In other words, in order to speed up the silver precipitation rate and at the same time deposit it uniformly, the oxide film is activated by being wetted with an activating solution containing stannous halide as the main component, and then treated with a silver mirror solution. It is formed. Note that the activation process can be omitted, but
This is desirable in order to shorten the silver mirror layer formation time. 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, the wall surface of the space is washed with water, dried, and further heat is applied from the outside to the mounting part of the getter 9 to 300 to 900°C to activate the getter 9 while performing vacuum treatment. tube 5
By melt-sealing, a stainless steel thermos flask can be manufactured, and by fixing a bottom cover 6 to protect the tip tube 5 and provide stability, the structure shown in FIG. 1 can be 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 70wt%Zr-24wt%V-6wt%
An assembly in which a commercially available Zr-V-Fe ternary alloy non-evaporable getter 9 made of Fe is attached to the inside of the body member 2a, and then the body member 2a and bottom member 2b of the outer bottle 2 are welded and integrated. 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. Activates the outer surface of
After 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 poured from the tip tube 5 into the space 4, and the double bottle is held horizontally in the axial direction, just as in the case of a glass thermos flask, and the bottle is held at high speed. A silver mirror was deposited by injecting the solution while rotating it, thereby forming a silver mirror layer 8 shown in FIG. After that, it was washed with water and dried in the same manner as for a glass thermos flask, and 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 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 rubble bottle 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-retaining ability of the heat-retaining bottle 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-retaining effect for 6 hours and 24 hours was 82.5°C and 59.9°C, respectively. It was hot.
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. [Test conditions] Pouring temperature: 95℃ Hot water amount: Full Plug: Sealed plug (45mmφ) Ambient temperature: 20℃ The gloss of the outer surface of the inner bottle after buffing and degreasing is 122, and the gloss after baking treatment The temperature was 101, a decrease of 21 points compared to before firing. This gloss value is JIS
Based on the measurement method specified in Z8741, the angle of incidence is 60
゜、The glossiness of the standard sample 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 test whether or not the gettsuta that had been wetted with the silver mirror plating liquid had lost its function, after one month had elapsed using the polishing bottle produced in the above example,
After disassembling and removing the gettuta, we investigated the remaining absorption capacity of the gettuta by absorbing H ₂ and CO gas.
60% of H ₂ and 40% of CO remained, which were the same as those taken out from the conventional method. As is clear from the above description, according to the present invention, by using the Zr-V-Fe 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 the drawing]

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)

[Scope of Claims] 1. A double-walled structure consisting of an inner container and an outer container made of stainless steel, a space formed between the two containers being a vacuum, and both containers forming the space. 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, Zr is applied to the space forming surface of one stainless steel component constituting the double container. - Attach a V-Fe ternary alloy non-evaporable getter, weld this part together with other parts to form a double container, and then introduce silver mirror plating liquid into the space of the double container to perform silver mirror plating. A method for manufacturing a stainless steel vacuum double container, characterized by: 2. The method according to claim 1, wherein the getter is a ternary alloy non-evaporable getter comprising 45 to 75% by weight of Zr, 20 to 50% by weight of V, 5 to 35% by weight of Fe, and unavoidable impurities. 3. The method according to claim 1 or 2, wherein an oxide layer is formed on the surface of the component on which the silver mirror layer is to be formed, prior to attaching the getter. 4. The method according to claim 3, wherein the oxidized layer is formed on the surface of the stainless steel component on which the silver mirror layer is to be formed by firing the component in air or in an oxidizing atmosphere. 5. The method according to claim 1 or 2, wherein the surface of the stainless steel component on which the silver mirror layer is to be formed is nickel-plated before the getter is attached.