JPH0339216B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a painted wall of a microwave oven heating chamber.
In particular, it relates to improving its corrosion resistance.

(b) Prior Art In a conventional microwave oven, the top plate 6a, which is one of the walls of the heating chamber, was as follows. In other words, type A is made of an aluminum-plated steel plate and the inner surface is coated with a catalytic purification film with a thickness of 150 to 250 μm, and type B is made of an aluminum-plated steel plate and the inner surface is coated with a catalytic purification film of 150 to 250 μm thick. As the paint film is coated, the area around the punched holes on the outer surface is an aluminum paste-based paint.The composition of the paint is, for example, aluminum...8.8%, heat-resistant silicone resin (50% solids)...20.2%, and anti-settling hardening agent...
2.2%, organic solvent…almost 10μ using 68.8% paint
The inner surface 13 is coated with a coating film of m thickness, and is made of a plated steel plate 16a of an alloy with a composition ratio of 1:1 as shown in FIGS. 6 and 7 as type C.
a is the catalyst purification coating 18a used in A type.
The coating film 22 is coated with a thickness of 200 μm and is the same as type B around the punched hole 11a on the outer surface 14a.
A was coated. In addition, 15a
17a is a base steel plate, 17a is a plating layer, 19a is an outer edge portion of the punched hole 11a, 20a is an internally exposed portion, and 21a is a burr of the edge portion 19a.

(c) Problems to be Solved by the Invention However, in a microwave oven using the above-mentioned top plate, the area around the punching hole 11a corrodes and falls off, creating a large opening and causing electromagnetic waves to leak from this opening, resulting in an unusable life. The problem was that time was short.

That is, the reason why corrosion occurs in the heating chamber top plate 6a as described above is that when the punching hole 11a is provided in the top plate 6a, an internal exposed portion 20a of a unique shape is created at the edge portion 19a of the punching hole 11a, and this internal Punching hole edge portion 19a including exposed portion 20a
In the internal exposed part 20a, where the plating layer 17a of the plated steel plate 16a is torn and the base steel plate 15a forming the steel plate is exposed, salt, moisture, protein, sulfur, etc. from the food to be cooked are exposed here. This is because it adheres to the surface.

This invention was made in view of the above circumstances,
To provide a microwave oven in which the area around the punching hole is coated with a coating film of a predetermined thickness that does not cause peeling or cracking during use of the microwave oven, thereby preventing corrosion of the heating chamber top plate (heating chamber wall). .

(d) Means for Solving the Problems This invention provides a solution to the problem in that the edge portion (internally exposed edge portion) of the punched hole in the heating chamber wall and the vicinity thereof are composed of scale-like minerals, aluminum powder, or scale-like minerals. It is coated with a paint film containing aluminum paste.

The detailed structure is a microwave oven in which punching holes are formed by punching a plated steel plate from the inner surface to the outer surface, and the inner surface is coated with a paint that has the function of purifying oil components that adhere to it. A painted wall of a microwave oven heating chamber, characterized in that a paint containing scale-like mineral substance is applied to an internally exposed portion of an edge portion protruding to the outside surface of the punched hole in the painted wall of the heating chamber. .

(e) Effect When a paint containing scale-like minerals is applied around the punched holes on the top plate, which is the heating chamber wall, the film thickness increases.
A coating film with a thickness of 300 to 350 μm is formed, and the coating film does not blister during formation and does not peel or crack when used in a microwave oven.

(f) Examples This invention will be described in detail based on the examples shown in FIGS. 1 to 5, but the invention is not limited thereby.

First, to explain the microwave oven, the microwave oven R is provided with a heating chamber 2 inside the device main body 1, and
A door body 4 is attached to the opening 3. 5
is the operation panel.

As shown in FIG. 2, the heating chamber 2 is formed by a top plate 6, a body plate 7, a back plate 8, and a front frame 9.

As shown in FIG. 3, the top plate 6 has a plurality of punched holes 10 on the supply side and punched holes 1 on the suction side so that hot air circulates in the heating chamber 2 and uniform temperature rise is obtained.
1 and an exhaust side punching hole 12 to the outside are provided by punching from the inner surface 13 side of the heating chamber to the outer surface 14 side. A sheathed heater (not shown) and a circulation fan (not shown) are installed in the device body 1, and these feed hot air into the heating chamber 2 through the supply-side punched holes 10. Cooking is done by raising the internal temperature to around 400℃.

The heating chamber wall of the present invention will be further explained below. In this embodiment, the heating is performed on the top plate 6, but other heating chamber walls such as the body plate 7 and the back plate 8 are also used.
It may be carried out in

The top plate (heating chamber wall) 6 is made of a plated steel plate 16 in which a base steel plate 15 is plated with, for example, a Zn--Al alloy having a composition ratio of 1:1. 17 is a plating layer of this plating steel plate 16.

The inner surface 13 of the top plate 6 is coated with a film made of an organic solvent-based paint whose binder is silicone resin and which has so-called catalytic purification properties that easily decomposes fat etc. from the food to be cooked (not shown) into water and carbon dioxide gas by cooking heat. For example, if the thickness is
It is coated with a catalytic purification coating 18 of 200 μm.

Punching holes 10, 1 are provided on the outer surface 14 of the top plate 6.
Punching holes 10 and 1 in the edge portions 19 of 1 and 12
There is an internal exposed portion 20 that was created during the formation of 1 and 12. A burr 21 is formed on the internal exposed portion 20 and has an extremely complicated shape.

However, the composition of aluminum powder, silica powder, barium sulfate, alumina, zinc powder...30 to 70%, for example, mica powder, is found around the punching hole edge 19 on the outer surface 14 side of the top plate heating chamber, including this internal exposed portion 20. Colored pigment consisting of scaly mineral...10-20%, _TiO2 , aluminum paste, etc....5-15
%, silicone resin (solid content 50%)...10-30%,
Edge-covering coating film 2 with a coating film of 300 to 350 μm formed by a heat-resistant silicone resin paint containing an antisettling agent...0 to 10% and an organic solvent...0 to 30%.
1 is coated.

The state of use of the top plate (heating chamber wall) 6 will be explained below. When the food to be cooked (not shown) is placed in the heating chamber 2, the door 4 is closed, and the switches on the operation panel 5 are operated to heat the inside of the heating chamber 2 to a predetermined temperature.
A very small amount of salt, protein, water, fat, sulfur, etc. from the surface of the food to be cooked in the heating chamber 2 becomes gaseous, and some of it touches the inner surface 13 of the heating chamber, and the rest is passed through the suction side punched hole 11 and the exhaust gas. It is exhausted to the outside of the heating chamber 2 through the hole 12. Heating chamber interior surface 13
In this case, the catalytic purification coating film 18 decomposes fat, protein, etc. into water carbon dioxide gas by cooking heat, self-cleans, and prevents fat, protein, etc. from adhering.
On the other hand, at the edge portion 19 of the outer surface of the heating chamber of the suction side punching hole 11, even if the above gas passes through, there is no burr 2.
Since the inner surface exposed portion 20 including 1 is covered with the coating film 22, the base steel plate 15 will not rust.
Also, since the inside of the heating chamber 2 is heated, the edge portion 1
9 also reaches a high temperature, but the coating film 22 in this area does not crack or peel. The same applies to the exhaust hole 12 and the edge portion of the supply punching 10. Therefore, the top plate 6 of the microwave oven R is less susceptible to corrosion and has an extremely long service life. By the way, high temperature corrosion test [400℃ in oxidizing atmosphere (air)
After being left for 24 hours, it was continuously subjected to the JIS salt spray test.
A high-temperature corrosion test lasting 24 hours is carried out as one cycle, and the total test time and degree of corrosion are investigated. ] The results were as shown by D in FIG.
The extent was that red rust was raised on the edge portion 19. This means that Microwave Oven R has a service life of 10 years.

Note that A, B, and C in the graph are the results shown in the conventional example.

Further, the composition of the paint for the edge-covering coating film 22 may be as shown below. Paint F consists of silica powder...21.6%, barium sulfate...28.5%,
Mica powder…14.4%, organic bentonite…0.3%,
Contains silicone resin (50% solid content)...16.0%, aromatic thinner...12.0%, if the coloring pigment is white, it is titanium oxide, and if it is silver, it is aluminum paste...7.2%. Paint G is silica powder...50.1
%, mica powder…14.4%, organic bentonite…0.3
%, silicone resin (50% solid content)...16.0%, aromatic thinner...12.0%, if the coloring pigment is white, it is titanium oxide, and if it is silver, it is aluminum paste...7.2%.

(G) Effects of the Invention This invention has the outer edge of the punched hole in the heating chamber wall formed with a paint containing flake-like mineral material to a desired thickness, and does not peel or crack due to cooking heat. Coating with a coating prevents corrosion from the edges, thereby providing a microwave oven with a long service life.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the main part configuration showing one embodiment of the present invention, FIG. 2 is a plan view of a top plate using this, and FIG.
The figure is a perspective view of a heating chamber using this, Figure 4 is an explanatory diagram of the configuration of a microwave oven using this, Figure 5 is a graph showing the results of a high temperature corrosion test, and Figure 6 is the main part configuration of a conventional example. The explanatory diagram, FIG. 7, is an explanatory diagram of the main part configuration showing the corrosion state in the conventional example. 6...Top plate, 10, 11, 12...Punching holes, 13...Top plate inner surface (heating chamber wall inner surface), 14...
...Outer surface of the top plate (outer surface of the heating chamber wall), 15...Base steel plate,
16... Plated steel plate, 17... Plated layer, 18...
... Catalyst purification coating film, 19... Edge portion, 20... Internal exposed portion, 21... Burr, 22... Coating film.

Claims (1)

[Scope of Claims] 1. Punched holes are formed by punching a plated steel plate from the inner surface to the outer surface, and the inner surface is coated with a paint that has a purifying function to remove adhering oil components. A painted wall of a microwave oven heating chamber, characterized in that a paint containing scale-like mineral substance is applied to an internally exposed portion of the edge portion protruding to the outside surface of the punched hole. 2. The painted wall of a microwave oven heating chamber according to claim 1, wherein the scale-like mineral substance is mica powder. 3. The painted wall of a microwave oven heating chamber according to claim 1, wherein the content of scale mineral substance is 10 to 20%.