JPS62208378A - Dual-openable vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application to which the Invention Pertains) The present invention relates to a dual-ovenable container, and more specifically, to a dual-ovenable container that allows various foods to be heated and cooked efficiently and without any trouble using microwaves. The present invention relates to a container having heat resistance that can be used for cooking in a toaster oven.

(Problems to be solved by conventional technology and the invention) In recent years, advances in electronics have led to lower prices for microwave ovens, and as they enable faster and easier cooking, their popularity has been remarkable, and in the United States 45-50
%, and is about to reach 40 to 45% in Japan, and if you add it to the ovens (electric or gas) that have been used up until now, the penetration rate will be considerable.

Aluminum has excellent heat resistance, so it is used as a tray for oven-heated cooked food, and is the most consumed tray. , arcs may fly between the tray and other containers, damaging the inside of the refrigerator and damaging the magnetron that oscillates microwaves. Furthermore, if there is not much to be heated (food), the microwaves reflected from the aluminum surface may damage the magnetron or cause the inner wall of the microwave oven to reach an abnormally high temperature, making it unsuitable for use in microwave ovens. There is.

For these reasons, a dual e-ovenable tray that can be used in both ovens and microwaves was developed, and mainly in the United States, paper + PET laminate, pulp molded PET, unsaturated polyester, and crystallized PE were developed.
Trays made from T, have been commercialized, and aluminum trays have disappeared! The amount is on a decreasing trend. Because aluminum trays have excellent heat resistance, dual ovenable trays that can be used in microwave ovens are also being developed. However, this required painting with a special paint and limiting the shape of the container, so there was a problem that it could only be used for very limited items.

Furthermore, since aluminum trays have a high reflectance of infrared rays, there is a problem that heating efficiency is poor when heating them in an oven.

On the other hand, the above-mentioned dual ovenable tray made of materials other than aluminum is said to be applicable to ovens, but its heat resistance is 220 to 230°C, and it can only be applied to electric ovens with a temperature control device. 0
For example, in the toaster oven that is most popular in Japan and cannot be controlled, the tray temperature is 25.
The temperature may rise to 0 to 300°C, and the tray may become deformed or damaged, making it unsuitable.

Therefore, it is not a dual ovenable tray in the true sense, and it also has (1) excellent heat resistance, (2) good heating efficiency, and (3) no need for special paint. 4) There is a demand for a microwaveable or dual ovenable tray that does not require any restrictions on the container shape and (5) is inexpensive.

(Means for Solving the Problems) The present inventors have discovered that a container of a certain shape formed by press molding of a foil or plate of surface-treated steel or a structure covered with a protective film thereof,
It was discovered that this container has dual ovenable characteristics, allowing the contents to be cooked efficiently using microwaves without causing trouble such as damage to the magnetron, and that this container also has the heat resistance to withstand heating in a toaster oven. Ta.

In other words, the dual-ovenable container of the present invention is made of surface-treated steel foil or plate or its adhesive. This container is a tray-shaped container manufactured by press molding of a membrane-coated structure, and this container has the following formula % formula % (2) where S represents the surface fi (mm2) per one side of the container, F is the oblateness defined by 2F = (S' / H (where S' is the container opening area (mm2) and H is the container height m + *), which satisfies the following. It is characterized by having a certain shape and size.

(Function) The surface-treated steel foil or plate of the present invention exhibits 70% corrosion resistance even against highly corrosive contents, and is significantly more resistant than microwave cooking containers made of aluminum. This utilizes the property of having excellent microwave absorption and scattering properties.

That is, using a container made of this material not only provides high heating efficiency, but also reduces microwave reflection from the container to the magnetron, eliminating the tendency to damage the magnetron even when the container is empty. Decreasing becomes a corridor.

In addition, surface-treated steel sheets and the like have excellent heat resistance and have a higher infrared absorption rate than aluminum and the like, so that high heating efficiency can be achieved when cooking and heating in a toaster oven.

Table 1 below summarizes the properties of aluminum and surface-treated steel sheets when heated in a microwave oven and in a toaster oven.

From the results in Table 1, it can be seen that steel exhibits microwave absorption heating properties that are one order of magnitude higher than aluminum, and is superior in terms of heating efficiency. It can be seen that the heating efficiency can be increased by about 20% or more compared to that made of aluminum.

As detailed above, the present invention utilizes the property that steel absorbs microwaves efficiently with a small penetration depth.The microwave penetration depth and absorption heating efficiency for each metal are as follows. Shown in Table 2.

Table 2 Or 4.18 Xl044.06X102Fe 1.
422X10-5 0.69AI 1.885X10-
” 1.83X10-2Ni 1.933X1 (15
0,37 Cu 1.332X10゛' 1.30X1f12^
'g 1.293X10-" 1.25X10-2A
u1. θ75X10-4 1.82XIQ-2Sn
3.431X104 3.32XIO-2 steel 1.
78OX 10-5 0.85 From the results in Table 2 above, it can be clearly understood that steel has the property of absorbing microwaves and efficiently generating heat with a significantly small penetration depth.

The penetration depth of a metal material is determined by the following formula, where ρ represents the specific resistance of the material and ω is the angular frequency of the microwave, i.e. the value used in microwave ovens, 2πX
2.45X 109, and Le represents the magnetic permeability of the material, which can be determined as follows.

In addition, the ratio R of the thickness of one surface treatment layer and the microwave penetration depth of the substance constituting the surface treatment layer is (1) If the surface treatment layer is a single layer, the following formula is used.
represents the thickness (c+s) of the surface treatment layer, and δ represents the microwave penetration depth (Cm) of the substance constituting the surface treatment layer.

(2) When the surface treatment layer is multi-layered, each surface treatment layer is sufficiently small compared to the microwave penetration depth of the substance that constitutes each surface treatment layer, so the following formula % formula % However, Ll, L2 in formula 1 ...Ll represents the thickness (C■) of each surface treatment layer, δI, δ2...δi represents the microwave penetration depth (cm) of the substance constituting each surface treatment layer,
Further, the oxide layer that constitutes a part of the surface treatment layer generally has a large penetration depth of microwaves, and can be ignored if the thickness is extremely thin (0, 1, 1 or less).

It can be found by

When using the container of the present invention, during microwave heating,
The effect of preventing damage to the magnetron is recognized to be related to both the excellent properties of surface-treated steel in absorbing microwaves and the excellent properties in scattering microwaves. . That is, when the reflectance of microwaves to a magnetron was actually measured, it was found that it was approximately 0% lower when a surface-treated steel container was used than when an aluminum container was used. If this reflection suppression was entirely due to absorption of microwaves, the temperature of the surface-treated steel surface would be abnormally high, similar to the melting temperature. It is recognized that scattering is also being carried out effectively. Although the cause of this has not yet been elucidated, it is thought to be closely related to the fact that the surface-treated steel is a magnetic metal.

Although it has the characteristics of high absorption heating efficiency and excellent microwave scattering properties, it is impractical to use steel itself as a container material in terms of corrosion resistance. However, the advantage of the present invention is that surface-treated steel sheets and steel foils can be made to have corrosion resistance within a range of thickness that does not inhibit the microwave absorption heating efficiency of the steel. be.

It is also extremely important to press-form this surface-treated steel sheet or steel foil into a tray-shaped container. In a container made using this molding method, all parts that come into contact with the contents are seamlessly integrated, the surface treatment layer can remain on all of the parts without destruction, and microwave heating This is because the container can have a flat shape, which is preferable for this purpose.

In the present invention, the container shape and dimensions are expressed by the formula (1),
Setting the conditions to satisfy (2) and (3) also prevents damage to the magnetron during microwave heating.
This is important to enable uniform heating.

The attached drawing, Figure 1, shows whether or not uniform heating is possible and whether damage to the magnetron occurs, with the horizontal axis representing the aspect ratio (F) and the vertical axis representing the surface area of one side of the container (S). Also, each line in the figure is represented by the following formula % formula % (2). According to the results of these plots, the area surrounded by (bi), (2') and (3').

That is, it becomes clear that in the region satisfying the above formulas (1), (2), and (3), it is possible to uniformly heat the contents while preventing damage to the magnetron due to microwave reflection. That is, in the region below curve 1 (2'), the degree of microwave absorption and scattering by the surface-treated steel decreases, so the magnetron is more likely to be damaged. Also, this kind of container must be applicable to all microwave ovens, but tune! In the region L from i(1'), in the case of a microwave oven of the downward microwave introduction type, there is a greater tendency to block the second inlet, resulting in too large microwave reflection, which tends to cause damage to the magnetron.

Furthermore, in the region to the left of the straight line (3'), microwaves are insufficiently introduced into the interior, resulting in non-uniform heating.

(Operations and Effects of the Invention) According to the present invention, a container can be provided that has an excellent combination of heating efficiency and heat resistance and can be applied to both microwave ovens and toaster ovens. By using this container, you can perform microwave heating without damaging the magnetron.
It is now possible to heat the contents uniformly and efficiently, and when heating in an oven, the contents can be heated efficiently without damaging or deteriorating the container. Sufficient corrosion resistance can also be obtained.

(Description of preferred embodiments of the invention) A second example of the dual e-ovenable container of the present invention
3, the container l is formed by press-forming a surface-treated steel foil or plate or its protective film-covered structure, and includes a bottom portion 2, a short side wall portion 3, and an open end portion 4.
It consists of It will be appreciated that in this embodiment the open end 4 consists of an outward bead or curl.

In FIG. 4, which shows an enlarged cross-sectional structure of this container, this container material 5 includes a steel substrate 6, surface treatment layers 7, 7 applied to both surfaces of the steel substrate, and optionally at least a surface that becomes the inner surface of the container. It preferably consists of a protective film 8 applied to both surfaces.

Surface-treated steel foils or plates can be processed by chemical treatment, chemical conversion treatment,
Any steel foil or plate obtained by electrolytic treatment, plating treatment, or a combination of two or more of these treatments may be used. Suitable surface treatment layers are commonly used for the permanent protection of metals, preferably consisting of a metal plating layer or an oxide layer thereon, such as a chromate layer or a zirconate layer. Although the organic resin coating is effective in preventing direct contact between the contents and the steel foil or plate, the resin coating can prevent hydrogen ions from the organic acids contained in the highly corrosive contents. It has the property of being able to pass through the chloride ions, etc., contained in salts, and to a small extent, the 7-ions, etc., contained in salts. For this reason, the coating tends to peel off at the interface between the organic resin coating and the foil or plate, and once such peeling occurs, corrosion such as rust, iron leaching, and pitting easily progresses in this area. It becomes like this.

According to the present invention, by providing a surface treatment layer consisting of a metal plating layer or further a chromate layer on the steel foil, this metal plating layer acts as a barrier layer against the above-mentioned corrosive components, and furthermore, the organic resin coating layer It acts to increase the adhesion with. In this case, when a chromate layer is provided on the metal plating layer, the adhesion with the organic resin coating is further improved.

As the metal plating layer, Cr, Xi, Sn, Zn, A
Examples include a plating layer consisting of one or two types of materials such as I, or an alloy layer of these and iron. Examples of the chromate layer include those formed by a known chemical conversion treatment and/or chemical treatment.

It is desirable that the surface-treated steel material has a thickness of at least 0.020 m+* in order to prevent the material from overheating during microwave heating, and in the case of foil containers, it is 0.0
It is normal to have an intestinal thickness of 20 to 0.150 m, while in the case of iron plate containers, it is 0.150 to 0.35 m.
It is common to have a thickness of 0-carbonate.

From the standpoint of utilizing the properties of steel, the thickness of the surface treatment layer is preferably equal to or less than the penetration depth of the surface treatment layer, most preferably less than Z. In particular, when the surface treatment layer is coated with chromate, In the case of having a fully curved oxide layer as in the case of FIG.

As the steel foil or plate, both soft (ductile) and hard (full hard) ones are used. For the pre-applied type, cold-rolled steel sheets are annealed, then subjected to secondary cold rolling, annealed again, and, if necessary, subjected to post-treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment. It can be obtained by carrying out one kind or two or more kinds.

The latter type is obtained by subjecting a cold rolled steel plate to secondary cold rolling after annealing, and if necessary, performing post-treatments such as galvanizing, tin plating, nickel plating, electrolytic chromic acid treatment, chromic acid treatment, etc. . A full-hard type steel plate with a metal plating layer is also manufactured by annealing a cold rolled steel plate, subjecting it to tempering treatment, applying metal plating thereto, and then subjecting it to secondary cold rolling.

The M retaining film may be coated with an organic resin or may be coated with an inorganic paint.

As the organic resin coating layer, any resin that can be drawn while in close contact with the N4 foil or the plate can be used. Suitable examples of such resins include, but are not limited to:

(a) Polyolefins; polypropylene, polyethylene, polybutene-1, propylene-ethylene copolymer,
Propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ionically crosslinked olefin copolymer (ionomer).

(b) Polyamides; especially general formula In the formula, n is a number from 3 to 13, m is a number from 4 to is the number 11 Polyamides consisting of repeating units represented by

For example, poly-ω-7 minocaproic acid, poly-ω-amine hebutanoic acid, poly-ω-aminocaprylic acid, poly-ω
- aminopelagoic acid, poly-ω-aminodecanoic acid, poly-ω-7 minoundecanoic acid, poly-ω-7 minododecanoic acid.

Poly-ω-aminotridecanoic acid, polyhexamethylene adipamide, polyhexamethylene dodecamide, polyhexamethylene dodecamide, polyhexamethylene tridecamide, polydecamethylene adipamide, polydecamethylene adipamide Mido, polydecamethylene dodecamide, polydecamethylene tridecamide, polydodecamethylene adipamide, polydecamethylene adipamide, polydodecamethylene dodecamide, polydodecamethylene tridecamide, polytridecamethylene adipamide, polytridecamethylene sebamide,
Polytridecamethylene dodecamide, polytridecamethylene tridecamide, polyhexamethylene dodecamide, polydecamethylene azeramide, polydecamethylene azeramide, polytridecamethylene adipamide, or a copolyamide thereof.

(C) Polyesters; in particular, polyesters comprising repeating units represented by the general formula %, where R1 is a fullkylene group having 2 to 6 carbon atoms, and R2 is an alkylene group or arylene group having 2 to 24 carbon atoms.

For example, polyethylene terephthalate, polyethylene terephthalate/isophthalate, polytetramethylene terephthalate, polyethylene/tetramethylene terephthalate, polytetramethylene terephthalate/isophthalate, polyethylene terephthalate/in7thalate, polytetramethylene/ethylene terephthalate, polyethylene/tetramethylene terephthalate/ Isophthalate, polyethylene/oxyhenshade, or blends thereof.

(d) Polycarbonates; especially general formula +o-R3-0
-C:+ In the formula R3 is a hydrocarbon group having 8 to 15 carbon atoms.

Polycarbonate represented by.

For example, poly-p-xylene glycol biscarbonate, polydioxydiphenyl-methane carbonate,
Polydioxydiphenylethane carbonate, poly-
Dioxydiphenyl 2,2-propane carbonate, poly-dioxydiphenyl 1,1-nithane carbonate)'
II(e) Vinyl chloride resin of polyvinyl chloride, vinyl chloride-butane diene copolymer, vinyl chloride-styrene-butadiene co-hair polymer rod.

(f) Vinylidene chloride resins such as vinylidene chloride-vinylidene chloride copolymer and vinylidene chloride-vinylpyridine copolymer.

(g) High nitrile resins such as 7-acrylonitrile-butadiene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer with high nitrile content.

(h) Polystyrene resin, styrene-butadiene copolymer, etc.

These resins are generally formed into a film shape and adhered to the above-mentioned steel foil or plate by thermal fusion, or bonded using an adhesive. Adhesives that are excellent for a wide range of thermoplastic resin films and steel foils are urethane adhesives, and for polyolefin films, acids that are graft-modified with ethylenically unsaturated carboxylic acids or their anhydrides are suitable for use with polyolefin films. Modified olefin resins can be used, and for polyamide films, low melting point copolyamides can be used.
For polyester films, low-melting copolyesters can respectively be used as adhesives.

An organic resin paint can also be used instead of the above-mentioned thermoplastic resin film. Such paints include any protective paints consisting of thermosetting and thermoplastic resins: modified epoxy paints, such as phenolic epoxy paints, amino-epoxy paints; e.g. vinyl chloride-vinyl acetate copolymers, vinyl chloride- partially saponified vinyl acetate copolymer,
Vinyl or modified vinyl paints such as vinyl chloride-vinyl acetate-maleic anhydride copolymers, epoxy-modified, epoxyamino-modified, or epoxyphenol-modified vinyl resin paints; acrylic resin paints; styrene-butadiene copolymers, etc. These synthetic rubber paints can be used alone or in combination with two or more.

These paints can be applied to metal materials in the form of organic solvent solutions such as enamels or lacquers, or in the form of aqueous dispersions or solutions, in the form of roller coating, spray coating, dip coating, electrostatic coating, electrophoretic coating, etc. Of course, if the resin paint is thermosetting, the paint may be baked if necessary.

These resin films and paints can be used in various forms depending on the purpose and characteristics of the container.For example, if the surface-treated steel material is relatively thin and mechanical reinforcement by resin coating is desired, a resin film may Also, if the surface-treated steel material is relatively thick and mechanical reinforcement is not so required, a coating may be used.Of course, a resin film can be applied to one surface of the surface-treated steel material, and a resin film can be applied to the other surface. A coating film may be provided on the surface, or a coating film may be first provided on the surface of the steel material,
A resin film may be provided on one of the coating films.

As an organic resin coating on one or both of the steel materials,
It is desirable to use a material that has a pigment that has a processability effect and also has a blocking effect and a concealing effect against corrosive components. That is, by using a coating containing the above-mentioned pigment, the processing of steel foil can be improved. For example,
As mentioned above, steel foil is significantly inferior in drawability and formability to steel sheets due to the thickness effect. This is because wrinkles occur during the drawing process, and even if the wrinkle-pressing force is removed to prevent wrinkles, the wrinkle-pressing force is not partially transmitted to the foil surface through the organic film. Moreover, if the wrinkle pressing force is increased too much, the steel foil will have a low strength and will break, making it impossible to form a container.

The pigment in the organic resin coating hardens the organic resin coating itself, so the wrinkle suppressing force is efficiently transmitted to the foil.
It is thought that it is possible to mold a tray container without wrinkles.

Furthermore, by using a coating with the pigments described above,
The corrosion tendency of steel foil, which is a corrosive component, is significantly suppressed, and for example, hydrogen generation is significantly suppressed, significantly extending the shelf life of the container. is hidden, the appearance characteristics are well maintained over a long period of time, and the commercial value can be increased.

Titanium dioxide, especially rutile titanium dioxide, can be mentioned as a pigment having both of the above-mentioned functions. This titanium dioxide has the greatest anticorrosion effect among various pigments against the corrosion of steel foil caused by corrosive components, and also has excellent hiding power, making it possible to maintain the white color of packaging materials permanently. It becomes possible. This titanium dioxide is contained in a resin film, an adhesive layer, or a paint so that the coating amount of titanium dioxide is 0.5 to 30 g/rlf, particularly 1 to 20 g/rn'. In place of titanium dioxide or in combination with titanium dioxide, aluminum flake pigments, tin oxide pigments, zinc oxide pigments, etc. can be used as pigments having both of the above-mentioned functions. Its coverage rQ
The amount can be in accordance with the above range.

Furthermore, the outer surface coating located on the outer surface of the container can contain a heat ray absorbing pigment such as carbon black to increase the heat ray absorbing property during open heating.

The thickness of the organic resin coating varies depending on whether it is a paint or a film, but it is generally desirable to have a thickness in the range of 1 to 200 µm, particularly 2 to 150 µm.

Inorganic paint can be used instead of organic resin coating,
Here, as inorganic paints, ■alkali metal silicates,
A paint whose binder is a pure inorganic polymer whose main component is colloidal silica or an acidic metal phosphate, etc. is used as a paint whose main chain is an inorganic polymer whose main component is silicone varnish or an organometallic compound such as alkyl silicate or metal alcoholade. A paint whose binder is an organic group introduced into the side chain is blended or co-used with an organic polyester such as an epoxy resin or an acrylic resin and an inorganic polymer such as a silicone varnish or an organometallic compound or a silicate. It includes paints in which the main chain is a composite inorganic/organic polymer as a binder.

The molding into a tray-shaped container is performed by a known molding method using the above-mentioned raw material, except that the shape and dimensions are within the range defined by the formulas (1) to (3).

This molding is performed by press molding using a female mold and a male mold corresponding to the shape of the container. The open end of the molded container that is formed can have one variety of shapes.

For example, in Figures 5-A to 5-F showing several examples of the shapes of these open ends, the end 4 may have a flat flange shape as shown in Figure 5-A, or the end 4 may have a flat flange shape as shown in Figure 5-B. As shown in Figure 5-C, Figure 5-D and m5.
It can have a bead or curling structure, as shown in Figure 5-E, or a folded structure, as shown in Figure 5-F.

In addition, as shown in Figures 6 and 7, in the microwave oven,
In order to prevent the generation of spark discharge between the containers or between the containers and the wall of the oven, a coating 10 of a dielectric material made of plastic, ceramic, etc. is provided over the entire circumference of the open end 4 of the container. (FIG. 6), or a coating 10 of the dielectric material can be provided on a part of the corner of the open end 4 of the container (FIG. 7).

As the dielectric material 10, plastics or ceramics having a dielectric constant greater than that of air, preferably twice that of air, or the like is used. To cover the open end 3 with the dielectric material 10, as shown in Figure 8-A, a plastic film 10 is pasted by a width t that protrudes outward in the water direction from the outer end of the open end 4. method (t is O,
10 mm or more is preferable), as shown in Figure 8-B, the open end 4 is glued and wrapped with plastic tape 10, or as shown in Figure 8-0, the open end 3 is wrapped in a stretched plastic film and the heat is applied. How to cover this by shrinkage,
As shown in FIG. 8-D, a ring-shaped or sectioned member 10 formed by injection molding or pressure molding is fitted around the entire circumference or corner of the opening end, and if necessary, it is bonded. As shown in Fig. E, a method is used in which a resin in a molten state, a sol state, or a gel state is applied to the opening 4 and solidified.

(Example) ■ Examples 1 to 11. Comparative Examples 1 to 8 are about the adverse effects on the magnetron of the microwave oven and the uniform heating state of food when the tray-shaped container is heated in a microwave by changing the metal material and coating film while changing the aspect ratio and surface area per side of the container. This is what I researched.

Example 1 A steel foil with a thickness of 50 g+* is electrolytically treated with chromic acid using a conventional method, and the surface treatment includes metallic chromium of 0.0151 Lw thickness and chromium oxide of 15 mg/rn' (approximately 0.015 gm thickness) as metallic chromium. I made steel foil. An epoxy-phenol paint was applied onto this surface-treated steel foil so that the thickness after baking was approximately 2 μm, and baking was performed at 280° C. for 30 seconds. The thus obtained coated surface-treated steel foil was press-molded into a product with a diameter of 90.3 m, a height of 29 VW, an aspect ratio of 2.8, and a surface area of 1.4 x 10' per side of the container.
A tray-shaped container was manufactured by curling the open end of No. 2. This tray-shaped container was placed in the center of the table of the microwave oven, which was modified to be able to measure the incident power and reflected power of microphone A-waves by modifying a reprinted table-rotating microwave oven.The tray-shaped container was heated and observed for the occurrence of spark discharge. and incident power P2 were measured.

The measured incident power PI and reflected power p2 are (VSWR)
I asked for

The adverse effect of a microwave oven on the magnetron can be determined from the magnitude of the voltage standing wave ratio, and was evaluated as follows.

To evaluate the uniformity of food, put gratin in a container to fill approximately 95% of its internal volume, place the container in the center of a microwave oven, and heat it until a part of the surface of the gratin becomes browned (process II is completed). The temperature of the gratin at the center bottom of the container on the tray was measured at the time when the temperature of the gratin was evaluated as follows.

The presence or absence of arc generation was visually evaluated.

The evaluation results are shown in Table 3.

Examples 2 to 11 In Examples 2 to 11, the same coated surface-treated steel foil as in Example 1 was used, and the diameter x height was 90.3 mm x 20 mt, respectively.
, 140mmX30mm, 180mm
X35sm, 90.3+smX15mm, 90
．． 3mmX13mm, 140mmX15+wa
+, 180IX15m+*, 140m
mX10mm, 180mmX8mm, 20
0m+sX7mm.

Evaluation was carried out in the same manner as in Example 1, except that a tray-shaped container with a curled open end having an aspect ratio and a surface area per side of the container as shown in Table 3 was molded by press. The results are shown in Table 3.

Comparative Examples 1 to 8 Comparative Examples 1 to 8 used painted surface-treated steel foil similar to the example, and the diameter x height was 90.3 mm, respectively.
, 90.3mm x 32mm, 18hm x 4h
a, 70mmX15rats, 200m+a
X40mm, 80mmX1Bmm, 120
mmX7mm.

Example 1 except that a tray-shaped container with a curled opening end was press-formed, measuring 180 mm x 8.5 mm, and having a trouble rate and a surface area per side of the container as shown in Table 3.
It was evaluated in the same manner. The results are shown in Table 3.

From Examples 1 to 11 and Comparative Examples 1 to 8, no spark discharge was observed in either the Examples or Comparative Examples;
), that is, S/S2<1, will have an adverse effect on the magnetron of the microwave oven, and that does not satisfy equation (3), that is, S/S3>1, the food will be heated unevenly. Ru.

■ Examples 12 to 15; Comparative Examples 9 to 11 were heated in a downward microwave introduction type microwave oven with the metal material and coating of the tray-shaped container kept constant, the aspect ratio and the surface area per side of the container changed. This study investigated the adverse effects of microwave ovens on magnetrons.

Examples 12 to 15 Examples 12 to 15 used the same coated surface-treated steel foil as in Example 1, and the diameter x height was 230 mm x 40 mm, respectively.
, 230wm x 20 layers, 200 intestinal layers x 15
A tray-shaped container with a curled open end having a layer size, 220 m intestine x 15-layer intestine, 230 m intestine x 8 layer intestine, and an oblateness ratio and a surface area per one side of the container as shown in Table 4 was manufactured.

The microwave oven of the reprinted version was modified to be able to measure the incident microwave power in the same way as in Example 1. This tray-shaped container was placed in the center of the microwave table and heated. The VSWR was determined and the adverse effect on the magnetron was evaluated. The results are shown in Table 4.

Comparative Examples 9 to 11 Comparative Examples 9 to 11 used the same coated surface-treated steel foil as in Example 1, each having a diameter of 240 mm and a height of 2
Evaluation was conducted in the same manner as in Example 12, except that a tray-shaped container with a curled open end was press-molded with the weight, aspect ratio, and surface area per side of the container as shown in Table 4. . The results are shown in Table 4.

From Examples 12 to 15 and Comparative Examples 9 to 11, it can be seen that those that do not satisfy formula (1), that is, S/S+>1, have an adverse effect on the magnetron of a microwave oven.

■ In Examples 17 to 23 and Comparative Examples 12 to 15, the tray shape and coating were kept constant, the type of metal material was changed, and the effects on microwave ovens, uniform heating of food in microwave ovens, and toaster ovens were investigated. This study investigated the effect of heating efficiency on heating efficiency.

Example 17 Nickel, tin, chromium, and chromium oxide were added to a low carbon steel plate with a thickness of 0.21 m in order from the steel plate side using a conventional method, each having a thickness of 0.002 m, 0.1 m, and 0.1 m, respectively. 00
5gm, 10mg/rn' (thickness approx. 0.01 gm)
A surface-treated steel plate was created by plating the material in a similar manner.

From this surface-treated steel plate, a layer with a width of 80 rm and a length of 150 l,
Depth 15m■, Oblateness 7.6. A tray-shaped container with a curled open end having a surface area of 2.0 x 10'ms+ per side of the container was manufactured, and the adverse effect on the magnetron of a microwave oven was determined in the same manner as in Example 1, and the toaster oven was tested according to the following method. The heating efficiency was evaluated. The result is the fifth
Shown in the table.

The heating efficiency of a toaster oven is to measure the temperature of the gratin around the bottom of the tray-shaped container after 15 minutes when the surface of the gratin has finished cooking. The heating efficiency was investigated by measurement. Heating efficiency was evaluated as follows.

Example Technique 8 Tin is added to a 0.15 mm thick low carbon steel plate by a conventional method.
Plated to the thickness of 4 pots, then cold rolled to a thickness of 80JA
No. 11 tin-plated steel foils were created. A tray-shaped container was manufactured in the same manner as in Example 17 except that this tin-plated steel foil was used, and the same tests as in Example 17 were conducted. The results are shown in Table 5.

Example 19.20 In Example 19.20, a low carbon steel plate with a thickness of 0 and 15 mm was electrolytically treated with chromic acid using a conventional method, and each plate had a thickness of 0.791.
Lm, 2.0 JLts, as metal chromium and metal chromium +5+ag/rn' (approximately 0.015 gm thickness)
, 1 (lag/rn' (approximately 0.01 body 1 thickness) surface-treated steel sheets having chromium oxide were prepared.A tray-shaped container was prepared in the same manner as in Example 17 except that these electrolytic chromic acid treated steel sheets were used. It was manufactured and tested in the same manner as in Example 17. The results are shown in Table 5.

Examples 21 to 23 Steel foil with a thickness of 5 Qpm was electrolytically treated with chromic acid by a conventional method,
0.02g layer thickness of metallic chromium and 20 as metallic chromium
A surface-treated steel foil with 1 g/m' of chromium oxide was prepared. In Examples 21 to 23, epoxy e-urea paint, epoxy phenol paint, and
The thickness of each polysiloxic acid paint after baking is approximately 5B.
m, about 2 wins, about 5 finishes ■.

280℃ x 20 seconds, 280℃ x 30 seconds, respectively.
seconds.

Baking was performed at 200°C for 5 minutes. A tray-shaped container was manufactured in the same manner as in Example 17 from the thus obtained surface-treated steel foil with a protective film, and the same tests as in Example 17 were conducted. The results are shown in Table 5.

Comparative Example 12 A low carbon steel plate with a thickness of 0 and 15 mm was electrolytically treated with chromic acid using a conventional method to create a surface-treated steel plate with metallic chromium of 2.2 p, ra thickness and chromium oxide of 15 mg/rn' as metallic chromium. . A tray-shaped container was manufactured in the same manner as in Example 17 except that this electrolytic chromic acid treated steel plate was used, and the same tests as in Example 17 were conducted.

The results are shown in Table 5.

Comparative Example 13 A low carbon steel plate with a thickness of 0.15 layers was electrolytically treated with chromic acid using a conventional method to create a surface-treated steel plate with a thickness of 2.81 L of metallic chromium and 15 mg/rn' of chromium oxide as metallic chromium. . A tray-shaped container was manufactured in the same manner as in Example 17 except that this electrolytic chromic acid treated steel plate was used, and the same tests as in Example 17 were conducted.

The results are shown in the ft55 table.

Comparative Example 14 A tray-shaped container was manufactured in the same manner as in Example 17 using pure aluminum foil with a recommended thickness of 0.15 m, and the same tests as in Example 17 were conducted. The results are shown in Table 5.

Comparative Example 15 A tray-shaped container was manufactured in the same manner as in Example 17 using a 0.15 m thick layer of steel foil, and the same tests as in Example 17 were conducted. The results are shown in Table 5.

From Examples 17 to 23 and Comparative Examples 12 to 15, among surface-treated steel sheets with iron (steel) as a substrate, the thickness of the surface treatment film was less than the penetration depth of the microwave into the surface treatment film. Tray-shaped containers made from steel sheets have a more negative impact on magnetrons than surface-treated steel sheets, where the thickness of the surface treatment film exceeds the penetration depth of microwaves into the surface treatment film, and tray-like containers made of aluminum or copper. There are few
It can be seen that the heating efficiency of an open toaster is excellent. Furthermore, it can be seen that the heating efficiency is excellent in the case where a protective film is provided.

■ In Examples 24 to 26 and Comparative Examples 16 and 17, the entire circumference of the open end of the tray-shaped container was made of polypropylene of different thickness (relative dielectric constant = 2.3, 2.3 times the dielectric constant of air). The microwave oven was covered with a film and the occurrence of arcing with the side wall of the microwave oven was examined.

Example 24 A tray-shaped container was manufactured by curling the open end of a surface-treated steel plate similar to that in Example 17, and a stretched polypropylene film was heat-shrinked around the entire circumference of the open end.
Covered as shown in Figure 0. The thickness of the film at that time was measured and was 0.14 m layer.

A portion of the bottom corner of the container with a radius of curvature of 20 layers is the inside wall of a commercially available rotary table type microwave oven (microwave oven A) with a rated high frequency output of 500 W or a fixed table type microwave oven (microwave oven B) with a rated high frequency output of 500 W. A container was placed so that it was in contact with the microwave oven, and when the microwave oven was operated, it was visually evaluated to see if an arc was generated between a part of the container corner and the wall of the microwave oven. In microwave oven A,
When the table rotates and a portion of the container corner contacts the wall once, it is determined whether or not an arc has occurred, and the operation is completed.

The same test was repeated 10 times using different containers.

Microwave oven B was operated for 1 minute with a portion of the corner of the container in contact with the wall surface, and the presence or absence of arc generation was determined during that time. The same test was repeated 10 times using different containers. The results are shown in Table 6.

Example 25 The thickness of the polypropylene film covering the entire circumference of the can mouth end is 0
．． The test was carried out in the same manner as in Example 24 except that there were 12 fat layers. The results are shown in Table 6.

Example 26 The thickness of the polypropylene film covering the entire circumference of the can mouth end is 0
．． The test was conducted in the same manner as in Example 24, except that the temperature was 10ts. The results are shown in Table 6.

Comparative Example 16 The thickness of the polypropylene film covering the entire circumference of the can mouth end is 0.
．． The test was conducted in the same manner as in Example 24 except that the 09 Sono layer was used. The results are shown in Table 6.

Comparative Example 17 The thickness of the polypropylene film covering the entire circumference of the can mouth end is 0.
．． The test was conducted in the same manner as in Example 24, except that 07rsrs was used. The results are shown in Table 6.

Examples 24-26. From Comparative Example 16.17, if the opening end of the container is covered with a film thickness of 0.1 ms+ or more, an arc will occur between the container and the wall even if the container comes into contact with the side wall inside the microwave oven. It can be seen that there is no negative effect on the magnetron of the microwave oven.

■ Examples 27-31. In Comparative Example 18, the open end of a tray-shaped container was molded into various shapes, and the occurrence of arcing at the open end of the container was examined in a microwave oven.

Examples 27 to 31 Iron foil with a thickness of 20 pL was electrolytically treated with chromic acid using a conventional method to create a surface-treated iron foil containing metallic chromium with a thickness of 0.021 L and chromium oxide of 20 g/rn' as metallic chromium. did. In Examples 27 to 31, tray-shaped containers similar to Example 17 were manufactured from this surface-treated iron foil, except that the opening ends of the containers were formed as shown in Figures 5-B to 5-F. be. These containers were placed in the center of the table of a commercially available microwave oven, and when the microwave oven was operated for 1 minute, it was visually evaluated to see if an arc was generated from the open end of the container.

The results are shown in Table 7.

Comparative Example 18 Using the same surface-treated iron foil as in Example 27, a tray-shaped container was manufactured in the same manner as in Example 27, except that the opening end of the container was shaped as shown in Figure 5-A. was tested.

The results are shown in Table 7.

From Examples 27 to 31 and Comparative Example 18, the opening end of the container was
If the flange shape is flat as shown in Figure A, arcing can be seen, but if the opening end of the container is from Figure 5-B to Figure 5-
It can be seen that no arc occurs when the curved structure is a bead or curling structure as shown in Figure F.

[Brief explanation of drawings]

Figure 1 shows the horizontal axis and the surface area of one side of the container (S).
This is a graph plotting whether or not uniform heating is possible and whether damage to the magnetron will occur with the vertical axis as the vertical axis. 2 is a top view of the container of the present invention, FIG. 3 is a side sectional view of the container of FIG. 2, FIG. 4 is an enlarged sectional view of the container of FIG. 2, and FIG. 5-B, 5-C, 5-D, 5-E, and 5-F are partial sectional views showing various shapes of the opening end of the container. 7 and 7 are top views showing other examples of the container of the present invention in which the open end is provided with a dielectric coating, FIG. 8-A, FIG. 8-B, FIG. 8-C, Figures 8-D and 8-E are partial cross-sectional views showing several examples of telephone body material coatings. 1 is a container, 2 is a bottom, 3 is a side wall, 4 is an open end, 5 is a container material, 6 is a steel substrate, 7 is a surface treatment layer, 8 is a protective film,
lO is a coating of dielectric material. Figure 5-D Figure 5-E Figure 5-F Figure 6 Figure 7 Figure 8-A Figure 8-8 Figure 8-C Figure 8-D Figure 8-E Procedure page...Regular stamp plow April 28, 1986 Director General of the Patent Office Uga Michibu Tono 1 , Indication of the case Patent Application No. 41956 of 1985 2 Name of the invention Dual ovenable container 3 Relationship to the case by the person making the amendment Patent applicant address 4439-2 Kamaritani-cho, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture
6 Name: Kishi Kishi 4, Agent address: 105 5, No date of amendment order 6, Subject of amendment (1) In the 9th line from the top of page 4 of the specification, the phrase "abnormality in the inner wall" was replaced by T inner wall. is abnormal,” he corrected. (2) The third line from the top of page 9 should be corrected as follows. (3) In the 9th line from the top of page 17, the phrase ``Used. Organic resin coating'' is corrected to r.Organic resin coating used. (4) In the fifth line from the top of page 19, the words "first arrival" should be corrected to "former." (5) In the fifth line from the bottom of page 19, the phrase "metal plating" is corrected to rmetal platingj. (6) On page 21, lines 17 to 18 from the top, the phrase "polydecamethylene azeramide" is corrected to read "polydecamethylene azeramide J." (7) In the 8th line from the bottom of page 22, the text "tetramethylene terephthalate" is corrected to rtetramethylene terephthalate J. (8) In the first line from the bottom of page 26, the text ``small teme'' should be corrected to ``r small''. (9) On the 8th line from the bottom of page 32, it says, "The incident power P2 was measured." The incident power P2 and the reflected power P2 were measured. Correct it as j. (lO) In the 9th line from the top of page 35, the phrase ``to form'' is corrected to ``to form 1.'' (11) In the first line from the bottom of page 36, the phrase "Substitute the value of the flatness ratio F" should be corrected to "Substitute the value of the flatness ratio F." (12) On page 39, "Evaluation of the adverse effects of the magnetron in a microwave oven" is corrected to "Evaluation of the adverse effect on the magnetron of a microwave oven." (13) On page 40, line 1 from the top "Example 17~
23'' should be corrected as ``Examples 17-231.'' (14) In the fourth line from the bottom of page 41, add ``0.4 ru''. Corrected as rO04RUrin1. (15) Table 5 on page 45 is corrected as shown in the attached sheet. (1B) In the second line from the top of page 47, correct the text ``Complete'' to read ``Completion''. (17) In the 10th line from the top of page 47, the phrase "can mouth end" is corrected to ropening end J. (18) On page 47, line 7 from the bottom, the phrase "can mouth end" should be corrected to "opening end." (18) In the third line from the bottom of page 47, the phrase ``can mouth end'' should be corrected to ``opening end''. (20) In the second line from the top of page 48, the phrase ``can mouth end'' should be corrected to ``opening end''. that's all

Claims (9)

[Claims] (1) A tray-shaped container manufactured by press-forming a surface-treated steel foil or plate or a protective film-coated structure thereof, which meets the following formula S≦1.47/F+4.15+10^4 S≧ 44.5F^2-188F+9300 S≦2.16×10^4F-4.65×10^4 In the formula,
S represents the surface area (mm^2) per side of the container, and F
is the formula F=(S')^(^1^/^2^)/H (where S
′ is the container opening area (mm^2), and H is the container height (mm). A container that can be used for both cooking and cooking in a toaster oven. (2) The container according to claim 1, wherein the surface treatment layer of the container has a thickness smaller than one half of the microwave penetration depth of the substance constituting the surface treatment layer. (3) The container according to claim 1, wherein the surface treatment layer is made of chromium, nickel, tin, an alloy of these with iron, an oxide of the metal, or a combination thereof. (4) The container according to claim 1, wherein the open end is curled or folded back. (5) The container according to claim 1, wherein a part or the entire circumference of the open end is covered with a dielectric material made of plastic or ceramic. (6) Claim 1 in which the protective film is an organic resin coating.
Containers listed in section. (7) The container according to claim 1, wherein the surface treatment layer has a metallic chromium layer on the steel substrate and a chromium oxide layer thereon. (8) The container according to claim 1, wherein the surface treatment layer has a tin-iron-nickel alloy layer, a metal tin layer, a metal chromium layer, and a chromium oxide layer in this order on the steel substrate. (9) The container according to claim 1, wherein the protective film is coated with an inorganic paint.