JPS5940507B2 - Self-cleaning wall forming method for the inner wall of a cooking appliance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a metal porous body containing an oxidation catalyst that oxidizes and decomposes organic substances such as fats and oils is used on the wall surface of the cooking cabinet to remove dirt scattered from food during cooking. The present invention relates to an improvement in a method for forming a self-cleaning wall surface that automatically cleanses.

U.S. Patent No. 3266 discloses a method for automatically cleaning dirt that scatters and adheres to the inner wall surface of the cooker when cooking food using a cooker such as an open or open range cooker.
No. 477, Special Publication No. 47-17832, Special Publication No. 49-2
8120, Japanese Patent Application Laid-Open No. 53-85812, etc. are known. These products oxidize and decompose dirt at cooking temperatures through the action of an oxidation catalyst dispersed in a porous coating layer. In all of the above methods, a porous layer is formed by coating enamel or a glassy frit or alkali silicate on an enamel base layer on a base metal. That is, in these products, a fairly porous coating layer is formed so that dirt can easily come into contact with the oxidation catalyst and air in order to improve the purification ability of the oxidation catalyst contained therein. Therefore, these current products have catalytic ability, but on the other hand, the surface of the porous coating layer is brittle, so they have poor adhesion to the underlying layer or underlying metal, and are easy to peel off, making them unsatisfactory. It's not a thing. In other words, in porous layers formed by coating with enamel, glass frit, alkali silicate, etc., catalytic ability and mechanical strength of the porous layer and adhesion to the substrate have contradictory properties. Therefore, it can be said that it is difficult to achieve both good performance at the same time. The present invention provides a method for forming a self-cleaning wall surface that overcomes the drawbacks of the current methods described above and has good cleaning ability.

Specifically, the self-cleaning wall surface of the present invention uses a metal porous body as the porous layer containing the oxidation catalyst without using a coating layer, and the oxidation catalyst is adhered to the metal porous body to improve heat resistance. It is manufactured by a method of bonding to the surface of the base metal using an inorganic bonding material having the following properties.

The metal porous body used in this case is generally formed by molding metal powder.
It is manufactured by sintering, forming metal fibers into a felt shape, and sintering, and is mainly used for filters with a filter function and for separating and concentrating gases and night bodies.

In addition, the inorganic bonding material having heat resistance mentioned here refers to a temperature of 250 to 350, which is the temperature of the inner wall of the cooking appliance during cooking.
These are inorganic substances such as alkali metal silicates, colloidal silica, colloidal alumina, and aluminum phosphates that have sufficient bonding ability even at ℃. Low melting point metals such as solder and silver solder do not belong to this category. do. Generally speaking, bonding materials are typified by adhesives, and most of their components are organic polymer compounds such as phenolic resins, urea resins, epoxy resins, polyamides, and cyanoacrylates. These items generally have a maximum operating temperature of 150°C or less, and the temperature is 250°C to 350°C, such as the inner wall of a cooking appliance.
In such cases, those containing these organic polymer compounds as main components cannot be used. By the way, in this invention, as a method for depositing and forming an oxidation catalyst on a metal porous body, Pt, Pd, Ni, CO, Cu, Mn,
This is carried out by immersing the metal porous body in a solution containing salts of at least one metal such as Ag, Fe, etc., whose oxidation catalyst is an elemental metal or its oxide, and then thermally calcining the body.

A more detailed explanation will be given below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing the most common conventional self-cleaning coating layer. In FIG. 1, reference numeral 1 denotes a base metal of the inner wall of the cooking appliance, and for example, steel plate, stainless steel plate, aluminized steel plate, galvanized steel plate, etc. are used. Reference numeral 2 is a covering layer, and enamel, glass frit, alkali silicate, etc. are used.

3 is oxidation catalyst particles contained and dispersed in the coating layer 2.

The self-cleaning coating layer constructed as shown in FIG. 1 has a very porous surface, so it easily peels off and is weak in strength. FIG. 2 is a schematic cross-sectional view of a self-cleaning wall formed by the method of the present invention.

In FIG. 2, 4 is a porous metal layer containing oxidation catalyst particles 3. 5 is an inorganic bonding material layer having heat resistance.

In forming the self-cleaning wall surface shown in FIG. 2, the following configuration and method were used. Base metal (1)... 7.5 x 10 (177! 1.5 mm thick stainless steel plate oxidation catalyst (3)...50 after immersed in 5% chloroplatinic acid solution
Porous metal layer (4)... 7.5 x 10 (177! 1.5 mm thick plate) Material: Ni, specific surface area 8.000 I/I inorganic bonding material layer (5)
...Sodium silicate (heat resistant temperature: 1000°C), coating amount: 80T179/CTil, dried at room temperature for 1 hour, then heated and cured at 120°C for 30 minutes, that is, in Figure 2,
A base metal 1 flat plate and a plate-shaped porous metal body 4 to which an oxidation catalyst 3 is attached are bonded using an inorganic bonding material 5, and after bonding, both at room temperature and 400°C, the weight is 25 kg/(7
i! The tensile shear strength value was obtained.

With a self-cleaning wall constructed as shown in Figure 2, there is no concern that the surface is brittle and easily peels off like the coating layer shown in Figure 1, and the bond strength with the base metal is sufficient. be.

Next, the dirt cleaning ability of the self-cleaning wall surface according to the present invention was investigated.

The following materials were used as the oxidation catalyst and the metal porous body, and the other configurations and bonding methods were the same as those in FIG. 2 described above. Oxidation catalyst (3)...10%Mn(NO3)2
A mixture of 5% Ni(NO3)2 and 5%Ni(NO3)2 was immersed overnight and then thermally fired at 350℃ to form MnO2 and NiO on a porous metal layer (4)...The shape is as shown in Figure 2. Same as, material Ag, specific surface area 600
0i/M3 Butter 50Tn9 was adhered to the surface of the self-purifying wall surface prepared in this way, and heated from 150℃ to 500℃.
The dirt purification ability was measured from the weight loss after being left in an electric furnace at 400° C. for 20 minutes each, and a purification ability characteristic diagram of the self-cleaning type wall according to the present invention was created.

This is shown in Figure 3. As is clear from FIG. 3, it can be seen that the self-cleaning wall surface formed by the method of the present invention has a high dirt cleaning ability at a temperature of 250 to 350° C., which is the temperature of the inner wall of the cooking appliance during cooking.

In addition, the metal porous bodies used in this invention include those called ultrafine metal porous bodies with pore diameters of 5G to several thousand, metal powder sintered bodies with pore diameters of 1 to several 100 μm, and spongy metals. In addition to the plate-like shape used in the embodiments of this invention, various molded products are commercially available. As for the material, in addition to Ni and Ag used in the embodiments of this invention, Cu,
Fe, Zn, etc., Ni-Cr, Fe-Cr, Cu-
Some are made of alloys such as Ni. According to experiments, the material is N.
It seemed that the l type and the Ag type had better dirt purifying ability using the oxidation catalyst. Furthermore, the heat-resistant inorganic bonding material in this invention includes commercially available heat-resistant inorganic adhesives. As described above, the method for forming a self-cleaning wall surface according to the present invention involves depositing and forming an oxidation catalyst on the surface and inside of a porous metal body, and then bonding the oxidation catalyst to a base metal using a heat-resistant inorganic bonding material. This method is used to form a self-cleaning wall for use inside a cooking appliance, which has a high cleaning ability and is robust.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a self-cleaning wall formed by a conventional method, FIG. 2 is a schematic sectional view of a self-cleaning wall formed by the method of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. Note that the same symbols in the figures indicate corresponding parts, 1 is the base metal, 2
3 is a coating layer, 3 is an oxidation catalyst particle, 4 is a porous metal layer, and 5 is an inorganic bonding material layer.

Claims (1)

[Claims] 1. A method for forming an inner wall of a cooking appliance, characterized in that an oxidation catalyst is deposited and formed on a porous metal body, and then this body is bonded to a base metal surface using a heat-resistant inorganic bonding material. Purification type wall forming method. 2. Claim 1, wherein the metal porous body is formed by molding metal fibers into a felt shape and sintering them.
A self-purifying wall forming method for the inner wall of a cooking appliance as described in . 3. The method according to claim 1 or 2, wherein the inorganic bonding material is made of any one of alkali metal silicate, colloidal silica, colloidal alumina, and aluminum phosphate. A self-purifying wall forming method for the inner wall of a cooking appliance. 4. The method of depositing and forming an oxidation catalyst on the metal porous body is based on at least one metal such as Pt, Pd, Ni, Co, Cu, Mn, Ag, or Fe, or an oxide thereof, which serves as an oxidation catalyst. Self-purification of the inner wall of a cooking appliance according to any one of claims 1 to 3, characterized in that the metal porous body is immersed in a solution containing salts and then thermally fired. Mold wall forming method. 5 The above metal porous body may be made of Ni-based element or alloy, or Ag.
4. A self-purifying wall forming method for an inner wall of a cooking appliance according to any one of claims 1 to 3, characterized in that the metal body is made of a metal body.