JPH0329780A - Multiple layer container capable of microwave heating and its heating method - Google Patents

Abstract

PURPOSE:To permit an easy microwave heating, shorten the heating time, and prevent the nonuniform heating in order to produce a utilizing effectiveness in retort sterilization and barrier capacity and shelf life extension by providing a multiple layer container consisting of plastic and metal and having a metal foil and a magnetic body layer oppositely positioned with a plastic layer interposed therebetween. CONSTITUTION:The main body 2 of a multiple layer container 1 consists of an inner plastic layer 3, a metal layer 4 in contact with the outside of the inner plastic layer and an outer plastic layer 5 provided outside the metal layer 4. A magnetic body layer 6 is provided on the bottom of the main body 2 of this container 1, i.e., the outside of the outer plastic layer 5, in opposing relation to the inner metal layer 4 through the outer plastic layer 5. In the case of this multiple layer container 1, the contents are heated by applying the heat produced by the metal foil layer and the magnetic body layer 6. This permits an easy microwave heating within the frequency range of 300-30GHz in this container, whereby the heating time can be shortened and the uniform heating can be effected.

Description

Detailed Description of the Invention [Industry L's Icheon Field] The present invention relates to a composite container capable of microwave heating, and in particular, to a composite container that can be heated with aluminum foil when containing contents such as food and heating with microwaves in a microwave oven. and plastic composite container technology. [Prior art] The JJ method is generally referred to as external heating, in which the food is heated in a container and heated by a gas burner or the like to heat the container from the outside. ing. On the other hand, a method in which the food mouth body is used as a heating element and is heated from within is generally referred to as internal heating, and one of these heating methods is a heating method using electromagnetic waves (microwaves). This microwave has a frequency of 300 M I+ 7.
From 30 GH 7. Microwave is a general term given to radio waves in the range of 11F.Microwaves are used for TV broadcasting on LJ 11F, etc.In order to prevent radio wave interference, frequencies are assigned internationally based on the purpose of use. Due to the regulations of the Radio Law, 2 4 for microwave heating.
Regarding the relationship between the three frequencies for which the use of 50 MHZ 4i} is allowed and the heating applications as described in (G), the frequency is 30 to 300 KHz or 300 to 3000.
The K H Z range is called induction heating and is 30-300M
II Z is dielectric heating, 300 to 30 G I{ 7
．． is called microwave heating. Microwave ovens have become widely used in households, and are used to warm food and thaw frozen foods, as well as to cook food, and to microwave the contents of a container. Examples of such containers include composite containers made of a multilayer combination of metal foil such as aluminum (Aj2>71 or Sudir foil) and plastic. Because plastic has retortability, can be retorted, and has a barrier property, it allows for long-term storage of low-acid foods such as meat and fish, and flavored foods such as curry, compared to plastic containers. The authors put the contents into various containers and heated them to 300 to 300
After careful consideration of heating using microwaves of 0 0 HZ, we found that metal containers such as those made of iron, which are conventionally used for induction heating with a lower frequency than the microwaves, cannot be heated using microwaves. In addition, in the case of the above-mentioned composite container with excellent retortability and barrier properties, the metal foil reflects most of the microwaves when heated in an electric oven, so heating from the sides and bottom cannot be expected. It takes too long to heat up, resulting in uneven heating, which is difficult as a container for microwave ovens.
It was found that the advantages of retortability and long-term storage cannot be taken advantage of. In addition, at that time, heating of the composite container containing metal foil in an electric oven is promoted [1st, we tried placing an aluminum vapor-deposited film on the outside of the container, this aluminum T5 vapor-deposited film was Since it is used as a wave absorption heating element, it was expected that it would produce good results. 7- Contrary to my expectations, it was also found that it does not easily generate heat. , 19. [Problems to be Solved by Akira] The present invention aims to solve the problems found in microwave heating using a composite container as described above. Ku M and Brassi
Microwave heating using an electric oven using a composite container with a polygonal structure including ribs can be easily performed, reducing heating time and preventing uneven heating. 7” + retort sterilization which is an advantage of this composite container + jj functionality Yabalya-f
l-. JP length + 1 VJ+
11 things are 11 things. [．． ．． ! ! [Means for Solving the Problem] and [Effect 1 In the present invention, 300 to 30G If Z using a composite container
In microwave heating of 300~30G
+I 7'. Magnetic materials such as iron foil, iron plates, and iron nets that generate almost no heat when exposed to microwaves. Plastic and metal composite containers such as L, which reflect most of the microwave and take a long time to heat, are separated by a layer of Blastic I! −． When the metal foil and the magnetic material are placed opposite each other as shown in the figure, heat generation of more than 200°C occurs directly on the contents, the metal foil layer, and the magnetic material ribs, and this heats up the contents in the composite container. Based on this knowledge, the present invention was completed. The principle of microwave heating is that when the contents (dielectric material) such as food in a container (f) or its segments are repeatedly reversed by microwaves, the valleys (r) etc. collide and rub against each other, generating heat and causing the food to cook. In addition to the internal heating, according to the present invention, there is no heat generation from the bottom or side of the composite container as described in L, and the heating time is shortened. This makes it possible to prevent uneven heating, and to even out heating in a deep-bottom container in particular. In the present invention, the magnetic body M and/or the plastic layer are separated.
When metal layers such as 1g foil are placed opposite each other, heat generation occurs in the contents, the magnetic layer in addition to the metal foil, and depending on the microwave output, the container may be deformed, the appearance may be poor due to melting, or the container may be removed from the microwave. It may cause problems such as burns, so don't worry! lJ the plus 1,000 soku layer 11<
For example, use a thermal insulation layer made of paper or the like. My husband also gave it. , Next, the structure of the present invention will be explained with reference to an example of the structure. , a magnetic layer is attached to the bottom back surface of the container. FIG. 2 is a sectional view of the M section of the container. ``1 The main body 2 of the composite container 1 consists of a bottom and a body extending obliquely from the bottom in the lJ direction, and the body has 1 at its 1 end.
1; Attach the bottom part marked i and the flange protruding from the line 1' to A]1
Ru. A part of the wooden body 2 is open. The main body 2 consists of an inner layer of brass scrap 3, a metal scrap 4 bonded to the outside thereof, and the metal M rib 4, as indicated by R in the cross-sectional view of Fig. 2.
and a separate plastic layer 5 contained on the outside of the
, 11 At the flange portion of the main body 2 of the container 1, one end of the outer plastic waste 5 is connected to the -′. It protrudes from the L end of the collapsible structure A. ．． The outer peripheral plastic layer 5 is made of inner plastic waste: I'? [See 11, <<. A magnetic material counterfeit 6 is attached to the outside of the outer blasting plate Pc 45 at the bottom of the wooden body 2 of the container l. As shown in the 1 m cross-section of FIG. 2, the magnetic material 6 is placed opposite to the inner metal layer 4 with the outer plastic scrap 5 in between. In the embodiment shown in FIG. 2, at the bottom of the main body 2 of the container 1, the magnetic material 6 is opposed to the metal scrap 4 via the outer plastic 5. FIG. 3 shows another structural example of a composite container to which the present invention is applied. An example of the structure of the N section of the container 1 shown in FIG. 3 is as follows:
As shown in FIG. 4, a plastic layer 7, a metal layer 8, and a plastic layer 9 are sequentially arranged from the inside to the outside.
and a four-layer structure F3 consisting of a magnetic layer IO, and a plastic layer II disposed outside the magnetic layer 10 in the four-layer structure B. {TL Tenaru. As shown in FIG. 5, an example of the pond having the cross-sectional structure of the N part of the container 1' includes a plastic layer 7, a metal layer 8, a plastic layer 9, and a magnetic layer 10, which are sequentially arranged from the inside to the outside. A four-layer structure I3 consisting of a four-layer structure I3, and a four-layer structure B
The plastic layer 11, the heat insulating layer l2, and the plastic layer 11 are sequentially disposed outside the magnetic layer 10 in FIG. Still another example of the structure of the N section of the container 1' is shown in the sixth section.
As shown in the figure, similarly to E, a four-layer structure 13 and a plastic NI+ layer sequentially arranged outside the magnetic layer IO
．． #A What do you do with the thermal plastic layer 3? The metal layers 4 and 8 in the composite container of the present invention must have barrier properties that do not allow oxygen to pass through, and are made of, for example, metal foil. , steel foil.゛5 In order to obtain the barrier property, the thickness should be 3μ or more.
It is preferable that it is 1. The composite container of the present invention does not contain such barrier waste (metal layer).
4.8, it exhibits superior barrier properties compared to multi-layer barrier containers made from composites of various plastics, which have been conventionally used as retort containers for heating in electric ovens. It enables long-term storage of low-acid foods such as meat and fish and flavored foods such as curry. Various types of plastic can be used for the plastic layer 3.5.7.9.11, but the inner or innermost plastic layer 3.7 is equipped with a lid etc. to provide excellent sealing performance. It is preferable to use a thermoplastic resin, especially unstretched polypropylene (PI). High density polyethylene (IIDPE). It is preferable to use polyester (C P ET ) or the like. In the container of the present invention, in addition to the contents and the metal foil layer, the magnetic housing layer 6.
10 generates heat, heating the composite container 1.1' and its contents. In composite container 1. When the magnetic layer 6 generates heat, the outer plastic layer 5 is preferably thicker than the inner plastic layer 3 in order to prevent IL from deforming the container shape due to the heat generation. The inner waste plastic layer 3 is preferably thinner than the outer plastic layer 5 in order to transfer the high heat generated by the magnetic layer 6 to the contents inside the container. The magnetic layer 6.10 is made of, for example, iron. Ferrite. It is made of stainless steel and nickel, and a specific example thereof is iron foil. Although this embodiment shows an example in which the magnetic layer 6 is attached to the bottom of the main body 2 of the container, it may also be in the form of a plate made of a magnetic stone such as an iron plate, or it may be made of a base made of magnetic material. In the form, that. The bottom of the main body of the container I may be rested on the plate or stand made of a magnetic material, including a wire mesh, etc., to prevent deterioration of the magnetic layer 10 during retorting. 11 two, -
11 In order to hold the magnetic layer 10 or to prevent deformation of the container shape due to heat generation of the magnetic layer 10, as shown in the container 1'', the outside of the magnetic material JfilO is provided with a As shown in , it is preferable to provide a plastic layer +1. The plastic layer l1 is preferably three times or more thicker than the plastic layer 8. ?1 In the container l', for example, a metal layer made of AI2 foil is provided. 8
When faced with a magnetic layer 10 made of iron foil, for example, through a plastic layer 9, the magnetic layer 10 generates heat and transfers the heat to the container 1', but depending on the output of the microwave, , the magnetic layer IO sometimes generates too much heat. In such a case, the deformation of the container may be accelerated, so it would be better to reduce the output of the microwave, but this would also reduce the output of the microwave that heats the container internally through the opening of the container.
The heating temperature of the contents may not rise. Therefore, in consideration of this, it is preferable to provide a heat insulating layer 12 made of paper or the like within the plastic skin 11, as shown in FIG.゛I'U The heat insulating layer 12 can prevent the heat generated in the magnetic layer 10 from escaping to the outside of the container, and can also prevent troubles such as burns when the container is removed from the microwave oven. From the same point of view, as shown in FIG. 6, heat-resistant plastic scraps 13 made of polyimide or the like may be provided in the outermost layer. Next, the present invention will be explained in more detail using striped examples. Example 1. ~4. Comparative example l. ~3. As shown in Fig. 1, the bottom of a cup-shaped composite container with an opening diameter of 73 mmφ and a depth of 33 mm, in which the inner and outer plastic waste layers 3.5 are made of polypropylene (+) +1) and the metal layer 4 is made of 20 μm A4 foil. Place 75 g of water in a container with various items listed in Table 1, such as magnetic material 6, placed on the outside, and place the container in the center of a commercially available four-turn table microwave oven with a rated high-frequency output of 500 W. After heating for 5 minutes, the heat generation state of various objects such as the magnetic body 6 was observed. The evaluation results are shown in Table 1. The evaluation results were evaluated based on the molten state of the outer plastic layer 5 as follows. Comparative Examples 4-5. PI that does not contain Afi foil! 2 containers, and iron punishment,
and 100 pieces of aluminum vapor-deposited film (
The procedure was the same as in Example 1 except that a microwave absorbing heating element (microwave absorbing heating element) was attached to the bottom. Table 1 shows the juice value results. Table 1 * l 1!7mm 20μ * 2 Injection molded product containing 80% ferrite * 3 * 4 * 5 Thickness 3mm l8-8 Stainless steel (martensite) foil thickness 50μ Nickel foil thickness 50μ Copper foil List No. 1 From the table. l'l) and multi-counterfeiting works including Yafuhaku. /1g and iron. Ferrite. Sudenres.
When combined with a magnetic material made of nickel, heat is generated, and even when the magnetic material made of iron is attached to a container made of 1) [), no heat is generated. The attached film generates heat when used in combination with a container made of P1), but 8f2
A composite container consisting of 'FA and 1)l' does not generate heat, and furthermore, A9. and Ap. It is also reported that when combined with copper (Cu), no heat is generated. Examples 5-7. As shown in FIGS. 3 and 4, the opening diameter is 73 mmφ. 33mm deep Brassi Sok Id7, 9. 1 +
are respectively PI), and the metal i 1 0 is A
Place the magnetic layer shown in Table 2 on the bottom of the j2 foil only.Pour 75g of water at 15℃ into a composite container, heat it for 5 minutes without covering it with an overcap or plastic wrap, and heat it for 5 minutes. r-
Immediately after taking it out of the microwave, the temperature of the contents was measured. Also, the container may be deformed due to heat generation. The appearance state due to melting etc. was also observed. The measurement results are shown in Table 2. Furthermore, 7) t. In Example 5, the thickness of the plastic layer 9 was 80μ. While the thickness of the plastic layer 1l was 700μ, in Example 6 the thickness of the plastic layer 9 was 900μ. The thickness of the plastic layer II was 70μ. Comparative Examples 6-8. Aluminum foil used in Comparative Examples 1 to 3 instead of the magnetic layer 10.
The procedure was the same as in Example 5 except that a copper plate and an aluminum vapor-deposited film were used. The measurement results are shown in Table 2. Comparative example 9. The same procedure as Example 4 was carried out except that the magnetic layer IO was not used. ? The III determination results are shown in Table 2. Comparative example 10. Using a CPP sheet (casting sheet of ethylene-propylene conjugate)/steel m/CPP sheet press container, the temperature L sheet was measured in the same manner as in Example 5, and the appearance of the container was observed. did. The moisture determination results are shown in Table 2. Table 2 ○... No deformation or melting of the container due to heat generation was observed Δ...
・From Table 2, the container partially melted due to heat generation. A4
2 foil and I) P? Among SJ containers, those with iron foil or stainless steel on the bottom are 4 degrees stronger than those with aluminum, copper plate, or anodized film. It can be seen that the provision of these is effective in accelerating heating in an electric oven. Furthermore, by increasing the thickness of the plastic flit and increasing the distance from the iron foil 10 to the outer surface of the container, deformation of the container due to heat generation can be avoided. Prevents appearance defects due to melting etc.1
[I see that it is possible. [Effects of the Invention] According to the present invention, the frequency in the composite container is 300~
3 0 GH 7. Microwave heating can be easily performed, heating time can be shortened, and heating can be made more uniform.
In the present invention, in addition to providing the magnetic layer on the bottom of the container, the magnetic layer may be provided on the bottom and/or the lid. It may be provided on part or all of the body and/or the lid. In addition, the present invention is not limited to the configuration examples and embodiments shown in the drawings, and various modifications are possible. 4. Of the drawing? ffl l! Explanation: Fig. 1 is a cross-sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view of section M in Fig. 1, Fig. 3 is a sectional view showing another embodiment of the present invention, and Fig. A sectional view of the N part in FIG. 3, and FIGS. 5 and 6 are sectional views showing other examples of the N part in FIG. 3, respectively. 1, 1' - Composite container 2... Container body 3... Inner plastic layer 4... Metal layer 5... Outer plastic layer 6... Magnetic layer 7... Plastic layer 8... Metal layer 9...Plastic layer 10...Magnetic layer +1 ・Plastic layer 2...Insulating layer 13 ・Heat-resistant plastic layer

Claims (1)

[Claims] 1. In a composite container having a multi-layer structure including a metal layer and a plastic layer, the composite container may be partially or completely attached to the bottom, body and/or lid through the plastic layer. A container comprising a magnetic layer facing the metal layer, the container having a frequency of 300 to 300.
A composite container that can be heated by microwaves at 0MHZ. 2. The composite container according to claim 1, wherein a plastic layer and/or a heat insulating layer are provided on the outer surface and/or inner surface of the magnetic layer. 3. When heating the contents in a multilayer composite container containing a metal layer and a plastic layer using microwaves with a frequency of 300 to 3000 MHz, the outermost layer of the composite container is a plastic layer, and the plastic layer is 1. A method for microwave heating a composite container, which comprises heating the container with microwaves while placing the container on a plate or stand made of a magnetic material so as to face the inner metal layer of the container. 4. Claim 3, wherein the surface of the plate or stand made of magnetic material is covered with a plastic layer and/or a heat insulating layer.
Microwave heating method for a composite container described in .