JP2016210463A - Container and package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container which can prevent explosive boil and can shorten a time for heating by an electronic oven.SOLUTION: A liquid is charged into a container and a package is heated by an electronic oven. The container is formed from a microwave transmission material. For example, the microwave transmission material includes a synthetic resin, a paper, a pottery, a glass or the like. The container comprises a bottom 1 and a shank 2. A microwave heating material 3 is provided at a position which is a liquid level corresponding position or lower on a container inner face (for example, a bottom inner face). The microwave heating material 3 comprises a metallic thin film. When the microwave heating material generates heat, the liquid contacting the microwave heating material is further heated. In association with a temperature difference, heat convection occurs, thereby agitating the liquid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a container and a package that are heated in a microwave oven.

  Normally, a liquid will boil when heated. However, it may not boil even though the liquid reaches the boiling point by heating. In such an overheated state, a phase transition from a liquid to a gas occurs due to a physical impact or contamination with foreign matter, resulting in sudden and intense boiling. This phenomenon is called bumping. Bumping is unpredictable and can cause burns.

  On the other hand, it is known that bumping can be prevented by stirring while heating. For example, when cooking with an IH heater or gas stove, stir the liquid or fluid in the cooking pan with a cooking utensil.

  By the way, bumping can occur even by heating with a microwave oven. However, it cannot be stirred during heating in the microwave. In particular, heating by a microwave oven is uniform, and since there is little temperature gradient in the container and heat convection hardly occurs, bumping is likely to occur. To prevent bumping in a microwave oven, there are methods such as examining the heating time to prevent overheating, or waiting for several minutes after heating, but this is not a drastic measure.

  In contrast, a container for preventing bumping in a microwave oven has been proposed (for example, Patent Document 1).

  The container of patent document 1 is shape | molded with the microwave permeation | transmission material, and the microwave impermeability material is provided in the outer peripheral surface or lid | cover more than a liquid level equivalent position. The microwave opaque material is, for example, an aluminum foil.

  The microwave impervious material blocks microwave irradiation and suppresses heating near the liquid surface. As a result, the container is heated from the lower side, and convection gradually occurs in the container. This stirs the liquid and prevents bumping.

Japanese Patent No. 480646

  However, the container of Patent Document 1 has the following problems.

  The microwave irradiated to the microwave opaque material is reflected. This phenomenon is wasteful from an energy point of view. Generally, the approximate heating time is determined according to the type of liquid to be heated (for example, water, tea, soup, milk, liquor, etc.), the amount, and the ability of the microwave oven. There is a possibility that a sufficient amount of heat cannot be supplied by heating for a predetermined time.

  On the other hand, in order to apply a predetermined amount of heat, the heating time becomes longer. Microwave ovens have the advantage of being able to cook in a short time, and this advantage is lost when heating time is prolonged. With prolonged heating, the bottom of the container may become a cause of scorching.

  This invention solves the said subject, and it aims at providing the container which can shorten the heating time by a microwave oven while preventing bumping.

  In order to achieve the above object, the present invention includes a microwave heating material provided on the inner surface of a container, which is formed of a microwave transmitting material and includes a bottom portion and a body portion.

  A temperature difference is formed in the liquid by the heat generated by the microwave heating material. Thermal convection causes agitation, thereby preventing bumping. Compared with the prior art that partially suppresses microwave irradiation, energy can be used effectively. As a result, the heating time by the microwave oven can be shortened.

  Preferably, in the above invention, the microwave heating material is a metal thin film.

  Preferably, in the above invention, the microwave heating material is provided below the position corresponding to the liquid level.

  Thereby, the heat convection from the lower part to the upper part occurs more reliably.

  Preferably, in the above invention, the microwave heating material is provided at the bottom.

  In the above invention, preferably, the body portion is divided into a plurality of portions and intermittently disposed in the circumferential direction.

  In order to achieve the above object, a package of the present invention includes the container filled with a liquid content and a lid for sealing the opening of the body.

  According to the container of the present invention, bumping can be prevented and the heating time by the microwave can be shortened.

Container according to the first embodiment Container according to the second embodiment Container according to the third embodiment Container according to the fourth embodiment Outline of manufacturing method of container according to first embodiment

~ General configuration ~
In the present invention, the container is filled with a liquid (including a fluid) and heated by a microwave oven. The present invention relates to a container and a package in which the container is filled with a liquid. The package may be appropriately sealed with a lid.

  For liquids, liquid foods such as water, tea, soup, milk, and liquor are targeted. Some solid matter may be included. As long as it is heated in a microwave oven, it can be applied to other than liquid food.

  By the way, in heating with a microwave oven, the microwave is reflected when it hits a metal or the like, is transmitted through a substance with low dielectric loss (glass, ceramics, plastic, etc.), and is absorbed by a substance with high dielectric loss (water, food). Heat the material.

  The container is formed of a microwave transmitting material. For example, synthetic resin, paper, earthenware, glass and the like are microwave transmission materials. The container includes a bottom portion 1 and a trunk portion 2. As appropriate, a leg portion provided continuously with the lower end of the bottom portion 1 and a flange protruding to the outer periphery at the upper end of the trunk portion 2 may be provided. Rectangular, circular, and elliptical planar shapes are common.

  In the present invention, the microwave heating material 3 is provided on the inner surface of the container at a position equal to or lower than the position corresponding to the liquid level.

  Specific examples of positions below the liquid level equivalent position will be described in the following first to fourth embodiments.

  The microwave heating material is a material that generates heat when heated by a microwave oven, that is, by microwave irradiation. Any conductive thin film may be used. Examples include metal thin films and conductive paints.

  The principle that the microwave heating material generates heat by the microwave is heating by Joule heat of eddy current generated in the metal layer. When a metal foil such as an aluminum foil is irradiated with a microwave, it is reflected. However, when the metal foil is made thinner, a part of the microwave is transmitted. At this time, a part of the thin metal layer becomes an eddy current, and this eddy current flows through the thin metal layer having electric resistance, thereby generating Joule heat and heating the liquid in contact therewith. For example, it is known that heat is generated at 5 to 70 nm in the case of aluminum vapor deposition.

  There are various metals and oxides that can be applied, such as aluminum, stainless steel, and indium oxide. Aluminum is generally used from the viewpoint of cost and safety. A thin metal layer can be formed by a vapor deposition method, a sputtering method, a coating method, a kneading method, or the like, but a vapor deposition method is common because of cost and effect.

-Action and effect-
In the heating by the microwave oven, the microwave heats the liquid that is the content, the microwave heating material generates heat, and the liquid that is in contact with the microwave heating material is further heated. As a result, the temperature of the portion of the liquid that is in contact with the microwave heating material is higher than the temperature of the other portions. That is, a temperature difference occurs in the liquid.

  Along with the temperature difference, the hot liquid moves toward the cold liquid. When thermal convection occurs, the upper liquid surface is in contact with air, the upper liquid is cooled by this air, the lower hot liquid moves upward, and the upper liquid cooled by the density difference convects downward. Is done. Further, when the liquid is heated, the surface tension is reduced, and it is considered that the liquid is pulled toward the cold liquid having a large surface tension. Therefore, an upward force is applied, and convection occurs vertically due to a temperature difference. Such thermal convection stirs the liquid. Thereby, bumping is prevented.

  Next, the effect of this embodiment will be described by comparing with the prior art.

  In the prior art, a microwave impervious material is provided on the outer peripheral surface or the lid at a position equivalent to or higher than the liquid level. As a result of suppressing the heating near the liquid level by the microwave impermeable material, the material is heated from the lower side of the container, and convection is gradually generated in the container. This stirs the liquid and prevents bumping. In other words, a temperature difference is formed by partially suppressing microwave irradiation.

  On the other hand, in the present embodiment, the microwave heating material is provided on the inner surface of the container at a position equal to or lower than the liquid surface equivalent position. A high temperature part is formed by the heat generated by the microwave heating material. In other words, a part of the microwave irradiation is used for heat generation of the microwave heating material, and the rest is used effectively for heating the liquid, thereby forming a temperature difference.

  Therefore, this embodiment can effectively use energy as compared with the prior art. As a result, a predetermined amount of heat can be supplied in a short heating time.

When the heating time is short, the advantage of the microwave oven that can be cooked in a short time can be further enhanced. Further, the risk of burning the bottom of the container can be reduced.
~Example~

  Examples and test examples of the present invention will be specifically described below. In each Example, arrangement | positioning of a microwave heat generating material differs. It is common that the position is equal to or lower than the position corresponding to the liquid level. The liquid surface equivalent position is a position that is assumed to be a liquid surface when the liquid is filled. In a package filled with liquid, it is the position of the liquid level.

  FIG. 1 is a schematic cross-sectional view and a plan view showing a container according to a first embodiment. The microwave heating material 3 is provided on the inner surface of the container bottom 1. In the illustrated example, it is provided on substantially the entire bottom, but may be provided on a part.

  FIG. 2 is a schematic cross-sectional view and a plan view showing a container according to the second embodiment. The microwave heat generating material 3 is provided on the inner surface of the container body 2. The microwave heat generating material 3 is divided into a plurality (four in the illustrated example) and is intermittently disposed in the circumferential direction. Furthermore, in the divided microwave heating material in the illustrated example, the upper end and the lower end are shifted in the circumferential direction. That is, the arrangement is similar to the roots of the fan blades. This arrangement contemplates swirling agitation (described below).

  FIG. 3 is a schematic cross-sectional view and a plan view showing a container according to a third embodiment. The microwave heat generating material 3 is provided on the inner surface of the container body 2 and almost the entire surface below the position corresponding to the liquid level.

  FIG. 4 is a schematic cross-sectional view and a plan view showing a container according to a fourth embodiment. The microwave heat generating material 3 is provided on the inner surface of the container body 2 and about half of the position corresponding to the liquid level or less.

~ Test example ~
In the first to fourth examples and the comparative example (without the microwave heating material), the process of filling the liquid and heating it for a predetermined time with a microwave oven was observed. Water (tap water) and corn potage were used as test liquids. The test results are shown.

Test example 1 (water)
Comparative example: Large bubbles were generated without generating fine bubbles.
First Example: Fine bubbles were generated from the vicinity of the microwave heat generating material 3, and the generation of fine bubbles continued thereafter, resulting in boiling.
Second Example: Fine bubbles were generated from the vicinity of the microwave heat generating material 3, and thereafter, the generation of fine bubbles was continued, and after large bubbles were generated, boiling occurred.
Third Example: Fine bubbles were generated from the vicinity of the microwave heat generating material 3, and thereafter, after large bubbles were generated, boiling occurred.
Fourth Example: Fine bubbles were generated from the vicinity of the microwave heating material 3, and thereafter, after large bubbles were generated, boiling was reached. However, the time until boiling is longer than that in Example 3.

・ Test Example 2 (Corn Potage)
Comparative example: After large bubbles were generated in a single shot, fine bubbles were generated, leading to boiling.
First Example: Fine bubbles were generated, and after that, the generation of fine bubbles continued and resulted in boiling.
Second Example: Fine bubbles were generated, and after that, the generation of fine bubbles continued and resulted in boiling.
Third Example: Test omitted.
Fourth Example: Fine bubbles were generated, and after that, the generation of fine bubbles continued and resulted in boiling.

~ Discussion ~
The above test results were considered and the following conclusion was reached.
In Test Example 1, when the comparative example was compared with the first to fourth examples, the bumping prevention effect was recognized in all of the first to fourth examples.
In Test Example 1, there was no significant difference between the third example and the fourth example. From the viewpoint of reducing the material, the fourth embodiment is preferable. Therefore, in Test Example 2, the test of the third example was omitted.
In Test Example 2, when the comparative example and the first, second, and fourth examples were compared, the first, second, and fourth examples all showed a bumping prevention effect.

  In Test Example 1, when the first, second and fourth examples were compared, the first example yielded favorable results. By providing the microwave heating material 3 on the inner surface of the container bottom 1, it is considered that the temperature below the liquid surely becomes high and heat convection is promoted.

  By the way, the bottom part 1 and the trunk | drum 2 of a container are formed from an expansion | deployment sheet. The microwave heat generating material 3 is provided on the development sheet before forming the container, and is formed by being die-cut together with the development sheet. In order to arrange the microwave heating material 3 in a part of the body 2, the positional relationship between the microwave heating material 3 and the body 2 is adjusted, and then the microwave heating material 3 is deposited. When the vapor deposition is performed on the entire surface, it is necessary to peel off the microwave heating material 3 before die cutting or peel off after die cutting. That is, the number of processes increases. Moreover, when providing in the trunk | drum 2, examination is required for a process so that the microwave heat generating material 3 may not inhibit joining of the trunk | drum 2. FIG. Therefore, the first embodiment is preferable also from the viewpoint of process simplification.

  When the microwave heating material 3 is provided on the inner surface of the container bottom 1 as in the first embodiment, it may be a part of the bottom, but may be the entire surface as shown in FIG.

  FIG. 5 is a diagram for explaining the outline of the container manufacturing method according to the first embodiment. When the microwave heating material 3 is provided on the spread sheet and the bottom portion 1 is cut out, the microwave heating material 3 is provided on the entire bottom surface. According to this manufacturing method, other steps (for example, positional relationship adjustment between the microwave heating material 3 and the bottom portion 1) can be omitted.

  Furthermore, since the body part 2 is generally gripped when holding the container, the first embodiment can avoid the high temperature part and is easy to hold.

  On the other hand, in the second embodiment, in addition to the thermal convection in the vertical direction, the thermal convection in the circumferential direction can also be expected by intermittent in the circumferential direction. Moreover, since the upper end and the lower end are shifted in the circumferential direction, it can be expected that thermal convection from the bottom to the top is formed in an oblique direction. These are intended for swirling agitation.

  Further, when holding the container, if the portion where the microwave heating material 3 is not provided is grasped, the high temperature portion can be avoided and it is easy to hold.

1 Container bottom 2 Container body 3 Microwave heating material

Claims (6)

In a container formed of a microwave transmitting material and having a bottom portion and a trunk portion,
A container comprising a microwave heating material provided on the inner surface of the container. The container according to claim 1, wherein the microwave heating material is a metal thin film. The container according to any one of claims 1 to 3, wherein the microwave heating material is provided below a position corresponding to a liquid level. The container according to claim 3, wherein the microwave heating material is provided at the bottom. The container according to claim 3, wherein the microwave heating material is divided into a plurality of parts in the body portion and intermittently disposed in the circumferential direction. The container according to any one of claims 1 to 5 filled with a liquid content,
A lid portion for sealing the opening of the body portion;
A package characterized by comprising.

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