JPH10175680A - Sheet having function for regulating microwave energy transmission amount, and package comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously cook a plurality of foods and beverages by a microwave oven by using a sheet comprising a perforated metallic foil and an organic thin film, and appropriately selecting the size of the holes according to the contents to reguate the transmittance of the microwave. SOLUTION: The diameter and the opening ratio of holes 6 to be opened in a metallic foil 1 are set according to the contents. Electric insulating fllms 2, 3 which is pressure resistant, and excellent in rupture unsealability and heat resistance are laminated on one side or each side of the metallic foil 1. In laminating the films 2, 3 on the metallic foil 1, the adhesive 5 is used appropriately. In the use, the diameter and the opening ratio of the holes are set to be large for the package to store the contents which take long in cooking, while the diameter and the opening ratio are set to be smaller for the package to store the contents which take short in cooking. A plurality of foods different in the cooking time in the regular method can be simultaneously cooked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet having a function of adjusting the amount of transmitted microwave energy, and a packaging material and a package comprising the sheet. In particular, the present invention relates to a food and drink package for storing various foods and drinks using the sheet and the packaging material and for easily cooking with a cooker such as a microwave oven under conditions most suitable for each food and drink.

[0002]

2. Description of the Related Art In recent years, eating habits have changed greatly. In particular, cooked foods and semi-cooked foods and drinks are increasing. For example, some foods are called retort foods, and cooked foods are placed in a container, frozen, and only need to be heated in a microwave when eating or drinking. Thus, foods and drinks that can be easily cooked in a short time using a microwave oven are increasing.

[0003] As a film sheet for a food or beverage package, a synthetic resin film, paper, metal foil, or a sheet material having a multilayer laminate structure thereof is used. The materials and functions of these packages are, for example, preservation, storage, distribution, distribution, display, and the method and form of preserving freshness, the environment in which foods and drinks are placed, and even fresh or processed products. It is different depending on. Therefore, it is necessary to appropriately select and use a packaging material having a material and a form that meets these purposes. In addition, the selected package is actually created and used in this way.

[0004] However, when cooking a food or drink package using a cooker such as a microwave oven or an electromagnetic cooker that can be quickly heated, the temperature in the package rises sharply.
There are few problems simply for the purpose of thawing or warming, but it is hard to say that it is suitable for making higher quality dishes. In the case where delicious food is obtained by gradually increasing the temperature, heating in a microwave oven is not suitable for cooking. For example, when making tofu in a microwave oven, the temperature rises sharply, so the "nest"
The tofu becomes hard and loses its original taste.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet suitable for various purposes, a packaging material using the sheet, and a package made of the packaging material at a low cost. In particular, with regard to food and drink packages, it is an object of the present invention to provide a sheet and packaging material that can be easily manufactured at a low cost, that has a constant product quality, and that can be cooked under optimal conditions for food and drink. Further, the food and drink package using the sheet and the packaging material can easily and optimally cook a plurality of dishes at the same time in a microwave oven.

A feature of the present invention is that cooking can be performed under the optimum conditions for the food or drink to be cooked, and a plurality of foods or drinks can be simultaneously cooked under the same conditions using a microwave oven or the like. This feature was not present in the conventional food and beverage package, but was made possible only by the present invention. According to the conventional method, when different foods and drinks are cooked simultaneously under the same conditions, foods that do not require time for cooking can be cooked, but foods that require time for cooking become insufficiently cooked. In addition, foods that can be cooked in a short period of time have too much heat and lose their taste. For these reasons, the simultaneous cooking of a plurality of different foods has not been put to practical use.

[0007]

The gist of the present invention is a sheet comprising a perforated metal foil and an organic thin film.
As a specific form, a sheet comprising two layers of an organic thin film layer and a perforated metal foil layer, or a sheet composed of three layers of an organic thin film layer, a perforated metal thin film layer and an organic thin film layer. No. The perforated metal foil preferably has a hole diameter of 1.5 mm or more. Further, the thickness of the metal foil is preferably 7 μm or more.
These sheets can be used as packaging materials. And various packages can be obtained using this packaging material. Among them, a food and drink package in which food and drink are packed is useful.

The sheet of the present invention is a sheet comprising a perforated metal foil and an organic thin film, such as paper or plastic film. Typically, a paper or plastic film laminated on one or both sides of a perforated metal foil can be used, but is not limited thereto. FIG. 1 shows a cross section of a sheet in which an organic thin film is laminated on both sides of a metal foil of the present invention. The laminated sheet 10 is formed by laminating films 2 and 3 on the front surface and the back surface of the metal foil 1 where holes 6 are partially formed.
Adhesive layers 4 and 5 are provided between the films 2 and 3 and the metal foil, and bond the film layer and the metal foil. The organic thin film laminated on the metal foil may be laminated on both the front and back surfaces, or may be laminated only on the back surface or the front surface. When the organic thin film is laminated on one side only, the adhesive may ooze out, or the metal foil may be peeled off or the hole diameter may change due to friction with other objects, so the organic thin film is laminated on both sides. Is preferred. Of course, it is also possible to laminate three or more layers.

[0009] The size of the hole formed in the metal foil is 1.
5 mm or more is preferable. This is because if the hole diameter is smaller than 1.5 mm, the microwave transmittance becomes extremely low, which is practically meaningless. When a plurality of holes are formed, holes having different sizes may be formed in the metal foil. However, from the viewpoint of adjusting the microwave transmittance, it is preferable to form holes having the same diameter. Further, it is also possible to divide the area of the sheet and make holes having different hole diameters for each of the sections. This is suitable for simultaneous cooking of a plurality of different dishes. That is, by putting a plurality of dishes in the same container and attaching the sheet of the present invention to the container such that an area of a sheet having a hole diameter suitable for cooking of each dish comes to each dish portion, A plurality of dishes can be cooked simultaneously in the same container.

For example, in FIG. 5, the laminated sheet of the present invention is divided into four areas. Each area is provided with a hole having a different diameter depending on the food or drink coming under the sheet. The area H is a portion without a hole, and a portion that does not require heating is placed below this.
The area F has a large diameter hole. Below this are those that require a lot of energy. Area E,
The area G and the hole diameter are small. Those that require less energy in this order will be placed under each area. In this way, a plurality of different foods and beverages can be cooked simultaneously and under optimal conditions. The number of holes formed in the metal foil may be one or more. The number of holes is appropriately selected according to the size of the holes depending on what is put in the package.

FIG. 2A is a sectional view of a laminated sheet laminated on both sides of a metal foil used in the present invention.
(B) is a plan view of a part of the laminated sheet used in the present invention. One unit area used for the inner package of the wide sheet is shown as a portion surrounded by AA ', BB', CC 'and DD'. It is recommended that the hole 6 provided in the metal foil 1 has a circular shape, an elliptical shape or a shape similar thereto, which does not form a sharp corner. It is not preferable to have sharp corners because microwaves are concentrated at the corners to cause a spark phenomenon. Further, the metal foil 1 needs to have a certain thickness. A metal thin film formed by metal vapor deposition is not preferable because defects such as minute cracks and scratches easily occur. This is because microwaves are concentrated at this defective portion, causing a spark phenomenon as well. For these reasons,
The thickness of the metal foil is preferably 7 μm or more.

With respect to the resin film to be laminated on the metal foil, an electrically insulating resin film or the like having excellent pressure resistance, tear-opening property and heat resistance is preferable. Specifically, polyethylene,
Polypropylene, a biaxially stretched nylon film, a biaxially stretched polyester film, and the like can be used. The organic thin film used is not limited to this. Needless to say, films made of polyethylene, polypropylene, polyester, nylon, polyvinyl chloride, polyvinylidene chloride, polystyrene, and the like, paper, synthetic paper, and the like can be used. The lamination can be performed by a lamination method. Of course, it is not limited to this.

Although the thickness of the resin film varies depending on the raw materials used, it is preferably at least 20 μm for low-density polyethylene, at least 10 μm for linear high-density polyethylene, and at least 10 μm for biaxially stretched nylon and polyester films. This is to ensure the pressure resistance.

In order to perform lamination, an adhesive is applied to one of the films or metal foils, the metal foil to be laminated and the film are superimposed, pressed by a roller or the like, and dried by a wet lamination method. A dry lamination method in which a film and a metal foil are laminated by laminating a film after applying an adhesive and removing the solvent of the adhesive by drying, and a film or metal foil in a molten state containing an adhesive consisting of 100% solids containing no solvent Hot lamination method in which a film and a metal foil are overlapped and pressed together, and a resin is extruded into a film by an extruder, and then an extruded lamination method in which the metal foil and another film are pressed, cooled and laminated by cooling. Method, can be used.

The laminated film sheet can be used as a packaging material. Further, various packages can be manufactured using the packaging material. Of course, this package also includes food and beverage packaging. The laminated sheet is made into a bag shape or a container shape, and an article is put therein and sealed to obtain a package. A food and drink pack is obtained by putting the food and drink in the bag or the container and sealing. Examples of foods and drinks include fresh foods such as fish and meat and their frozen products, materials such as vegetables and noodles, processed foods such as Chinese buns and beef stew and their frozen products, and other favorite products. Can be given as The food and drink pack of the present invention is sufficiently useful for food transportation, preservation and storage, display in stores, and the like.

Further, the food and drink pack of the present invention has a cooking function. In addition, even if a plurality of foods and beverages are processed in a microwave oven at the same time, it is possible to perform cooking optimal for each food and beverage. At this time, foods and drinks are put in a laminated sheet suitable for each optimum cooking condition, and they are packed together and packed in the same bag, and may be processed in a microwave oven. May be put together in a microwave oven and processed at once.

Next, the operation of the present invention will be described. Metal
Block microwaves. It is considered that when a hole is made in the metal foil, the microwave enters through the hole and consequently the microwave is transmitted. However, the present inventor has conducted a study on the amount of microwave transmission of a perforated metal foil and found that the size of the hole has a great effect on the amount of microwave transmission.

The present inventor has found that, even if the areas of the holes formed in the metal foil are the same in total, if the size of each hole is different, the microwave transmittance is different. FIG. 2 (b) shows a plan view of the metal foil, taking a laminated sheet having an area of 100 cm ² as an example. In the laminated sheet having this area, holes having different diameters are made in the metal foil, and the areas of the holes are made the same in total. In this case, the ratio of the perforated portion to the whole, that is, the opening ratio was set to 30%. 3.0mm, 10mm and 61.8 diameter
Using three kinds of metal foils with holes of mm, laminated sheets were prepared by laminating polyethylene films on the front and back of the metal foils, and the microwave transmittance was measured. This result
The results are shown in Table 1.

[0019]

[Table 1]

From Table 1, it can be seen that, although the ratio of the hole area to the area of the laminated sheet, that is, the aperture ratio, is 30%, the microwave transmittance greatly depends on the size of each hole diameter. You can see that it is. Hole diameter (diameter) 3.0m
m, the transmittance is about 8%, but the pore diameter is 10 m.
m, the transmittance increases to 20%, and the pore diameter is 61.8.
In mm, the transmittance reaches 31%. The metal foil used here is an aluminum foil having a thickness of 10 μm.

Generally, when different foods and beverages are cooked in a microwave oven or the like, microwave irradiation time is extended for foods that require a large amount of heat, and those that do not require much heat are cooked. The microwave irradiation time is shortened. When microwave heating is performed in the same package under the same conditions, if the microwave irradiation time is adjusted to the one that requires a large amount of heat, those that do not require much heat will be overcooked. In addition, if the microwave irradiation time is adjusted to the one that does not require much heat, the one that requires a large amount of heat is not cooked.

However, this problem can be solved without difficulty by using the laminated sheet of the present invention. Those that do not require much heat are packed in a laminated sheet made of metal foil with a small hole diameter, and those that require a large amount of heat are packed in a laminated sheet made of metal foil with a large hole diameter,
These are packed in the same package. When this package is processed in a microwave oven or the like, it is cooked in a state convenient for both, and a plurality of dishes can be easily cooked. This cooking can be easily realized by appropriately selecting the pore size according to the food or drink to be put in the package. Needless to say, the same effect can be obtained even when a plurality of foods and drinks are not packaged in the same package but are simultaneously placed in a microwave in separate packages and processed under the same conditions.

[0023]

Next, an embodiment of the present invention will be described.
explain. In the embodiment of FIG. 1, a perforated aluminum foil was used as the metal foil. The thickness of the aluminum foil is
It is preferable to use one having a diameter of 7 μm or more. The hole diameter varies depending on the contents, but is preferably 1.5 mm or more. The aperture ratio is also 0 to 100% depending on the contents.
Set to. One or both surfaces of this metal foil are laminated with an electrically insulating film having pressure resistance, tear-opening property and heat resistance. The film to be used is, specifically, a biaxially stretched nylon film, a biaxially stretched polyester film, a polypropylene film, a polyethylene film,
Examples include polyvinyl chloride film, polyvinylidene chloride film, styrene film, synthetic paper, paper and the like. When laminating each film to the metal foil, an adhesive is appropriately used.

FIGS. 3 and 4 show examples of the embodiment of the package. FIG. 3 shows the laminated sheet of the present invention in a bag shape, into which foods and drinks to be cooked are put. A laminated sheet in which a polyethylene film is laminated on the back surface of a perforated metal foil 1 and a nylon film is laminated on the surface is laminated to form a bag. Foods and drinks 14 to be cooked are put in the bag. FIG. 4 shows a container made from the laminated sheet of the present invention, in which foods and drinks to be cooked are put, and the lid is similarly covered with the laminated sheet of the present invention. The container is made from a thick polyethylene film laminated on both sides of a perforated aluminum foil. The food and drink to be cooked are put in a container, and a thin polyethylene film is laminated on both sides of a perforated aluminum foil, and the container is covered with a lid.

Next, the present invention will be described in more detail based on examples.

Examples 1 to 3 In the form of FIG. 2, a laminated sheet was used in which a biaxially stretched nylon film having a thickness of 20 μm was laminated on the front side of a 10 μm thick aluminum foil and a polyethylene film having a thickness of 50 μm was laminated on the back side. Three types of packages having hole diameters of 3.0 mm, 10 mm, and 61.8 mm were prepared, with the package dimensions being 10 cm in length and width and the aperture ratio being 30%. The package was filled with 50 cc of 15 ° C. water and heated in a 500 W microwave oven. During this time, the time until the enclosed water reached boiling was observed. Table 2 shows the results.

[0026]

[Table 2]

As can be seen from the results in Table 2, the aperture ratio is 3
It can be seen that, despite the same value as 0%, the time required for boiling increases when the pore size is small, and the time required for boiling decreases when the pore size is large. That is, 342 in the case of a hole diameter of 3.0 mm.
Seconds, 142 seconds for a hole diameter of 10 mm, and 95 seconds for a hole diameter of 61.8 mm. As a comparative example, 50 cc of water was sealed in a package made of a laminate of a nylon film and a polyethylene film without using an aluminum foil and similarly heated in a microwave oven. The time required for boiling was 55 seconds. .

In this example, the time required for water to boil was observed, but this naturally means that the same result is obtained for food and drink. From this fact, it is necessary to increase the hole diameter and opening ratio for packages containing contents that require a long time to cook,
As for a package in which contents requiring a short time for cooking are to be prepared, cooking can be performed in the same cooking time by reducing the hole diameter and the opening ratio. That is, even if the time required for cooking is different in a normal method, a plurality of food and beverage packages can be cooked simultaneously by appropriately selecting the aperture ratio and the hole diameter.

[0029]

Examples 4 to 6 In the embodiment shown in FIG. 2, a laminated sheet in which a biaxially stretched nylon film having a thickness of 20 μm was laminated on the front side of an aluminum foil having a thickness of 10 μm and a polyethylene film having a thickness of 50 μm was laminated on the back side was used. Three types of packages having hole diameters of 3.0 mm, 10 mm, and 61.8 mm were prepared, with the package dimensions being 10 cm in length and width and the aperture ratio being 30%. The package was filled with water at 15 ° C. and sealed, and in a microwave oven of 500 W, the amount of water until the sealed water reached boiling for 55 seconds was experimentally determined. Table 3 shows the results.

[0030]

[Table 3]

As can be seen from the results shown in Table 3, when the pore size is small, the time required for boiling is long. Therefore, the amount of water for boiling in a certain time must be reduced. In addition, when the pore size is large, the amount of water for boiling in a certain time may be large. In fact, from Table 3, for a 3.0 mm diameter hole, the amount of water to boil in 55 seconds is 8.1 c.
c, 19.4 cc for a hole diameter of 10 mm, 28.9 cc for a hole diameter of 61.8 mm, and the amount of water to be boiled in 55 seconds is larger for a larger hole diameter and smaller for a smaller hole diameter.
It can be seen that the amount of water is reduced.

[0032]

Example 7 A laminated sheet in which a biaxially stretched nylon film having a thickness of 20 μm was laminated on the front side of an aluminum foil having a thickness of 10 μm and a polyethylene film having a thickness of 50 μm on the back side in the form of FIG. 2 was used. Observe the time (seconds) until water boils when the package dimensions are 10 cm in length and width, the aperture ratio and hole diameter are changed, and the package is filled with 15 ° C water and heated in a 500 W microwave oven. did. Table 4 shows the results.

[0033]

[Table 4]

As can be seen from the results in Table 4, the smaller the opening ratio and the smaller the hole diameter, the longer the time required for boiling, and the larger the opening ratio and the larger the hole diameter, the shorter the time required for boiling. Here, the term “single mouth opening” means that, when a pack of 10 cm square in length and width is formed, one hole is opened so as to have a predetermined opening ratio.

[0035]

Example 8 In the embodiment of FIG. 3, raw salmon 150 was placed in a bag made of a sheet in which a polyethylene film and a nylon film were laminated without using metal foil so that the back side was a polyethylene film and the front side was a nylon film.
g. On the other hand, a hole having a diameter of 10 mm was formed in an aluminum foil having a thickness of 8 μm so as to have an opening ratio of 30%, and the cream sauce 35G was put in a bag made of a laminated sheet in which a polyethylene film was laminated on the back side with a nylon film on the front side. . Both were placed in a microwave oven and heated simultaneously. The heating time was 145 seconds. Both
It was the best cook. The cream soup was put on this raw salmon, and the cooked raw salmon could be eaten deliciously.

In the case of a raw salmon using a sheet that does not use a metal foil, an optimum dish can be cooked by heating the microwave oven for 145 seconds. On the other hand, for the cream sauce, when no metal foil is used, heating for 25 seconds is sufficient. If heated further, the cream sauce will boil and become unusable. However, if a laminated sheet using no metal foil is used for raw salmon as in this example, and a laminated sheet using aluminum foil with holes is used for cream soup, even if both are heated simultaneously, The optimum energy is given to each of them, so that they can be obtained in a state of being optimally cooked as a dish.

[0037]

Embodiment 9 A hole having a diameter of 3 mm and a hole having an opening ratio of 30% were formed on aluminum having a thickness of 8 μm and a thickness of 70 μm.
The container shown in FIG. 4 was prepared by using a laminated sheet obtained by laminating the polypropylene film on both sides thereof, and 162 g of tofu was added. On the other hand, a 3 mm-diameter hole was formed in an aluminum foil having a thickness of 8 μm so as to have an opening ratio of 30%, and a laminated sheet in which a 20 μm polyethylene film was laminated on the back side and a 20 μm thick nylon film was laminated on the front side. Then, the sheet was covered with a container containing the tofu.

[0038] The package containing the tofu was heated in a microwave oven for 7 minutes to obtain delicious tofu. When tofu is heated in a microwave oven without using metal foil, tofu is completed in about 85 seconds. However,
Since this product was heated in a short time, nests entered into the tofu and the whole became hard and the taste fell. As described above, according to the present invention, food and drink to be cooked can be cooked easily under optimum conditions.

[0039]

The present invention provides a sheet having an extremely simple structure, a packaging material comprising the sheet, and a package comprising the packaging material. In particular, as a food and beverage package, the manufacturing cost is low due to its simple structure, and it can be easily cooked using a microwave oven or the like. It can be cooked at the same time, and the quality of the cooked product in each package is constant and almost the same as the cooked one is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a sheet laminated on both sides of a metal foil of the present invention.

FIG. 2A is a cross-sectional view of a sheet laminated on both surfaces of a metal foil of the present invention, and FIG. 2B is a plan view of a part of the sheet.

FIG. 3 is an example of a food and beverage package using the sheet of the present invention.

FIG. 4 is another example of a food and beverage package using the sheet of the present invention.

FIG. 5 is an example of use of the sheet of the present invention.

[Description of Signs] 1 Metal foil 2, 3 Film 4, 5 Adhesive layer 6 Hole 10 Laminated sheet 12, 14 Food and drink 15 Bag-shaped package 16 Container-shaped package A, A ', B, B', C, C ' , D, D ', E, F,
G, H Codes for indicating the area on the sheet

Claims (7)

[Claims] 1. A sheet comprising a perforated metal foil and an organic thin film. 2. The method according to claim 1, comprising two layers of an organic thin film layer and a perforated metal foil layer, or three layers of an organic thin film layer, a perforated metal thin film layer and an organic thin film layer. The sheet according to claim 1, wherein 3. The sheet according to claim 1, wherein the hole of the metal foil has a diameter of 1.5 mm or more. 4. The sheet according to claim 1, wherein the thickness of the metal foil is 7 μm or more. 5. A packaging material comprising the sheet according to any one of claims 1 to 4. 6. A package comprising the packaging material according to claim 5. 7. The package according to claim 6, wherein food and drink are packed.