JPS63307085A - Food package for microwave oven cooking - Google Patents

Abstract

PURPOSE:To realize the optimum cooking condition, by providing a steam escape hole to a container and adhering a valve sheet having a layer of a substance generating heat caused by a microwave to a base film so as to close said hole. CONSTITUTION:A steam escape hole 4 is provided to the lid 31 of a container 3 and a valve sheet 5 having a layer 52 of a substance generating heat by a microwave is adhered to a base film 51 using an adhesive 6 so as to close the hole 4. As the substance generating heat caused by a microwave, indium oxide, tin oxide or a metal such as aluminum, nickel or tin is used and the membrane of this heat generating substance is provided so as to set the surface resistance thereof to a range of 10<1>-10<4>OMEGA/cm<2>. When a food package 1 is heated in a microwave oven, since the layer 52 of the substance generating heat generates heat, the adhesive 6 is softened to lower in its bonding strength. When the pressure of steam generated from content is raised to a certain limit or more, a part of the valve sheet 5 is naturally exfoliated from the periphery of the hole 4 of the lid 31 to release steam and the package naturally contracts to return to the original volume.

Description

[Detailed description of the invention]

1 plate of shellfish

[Industrial application field]

The present invention relates to an improvement in a package for cooking food in a microwave oven.

[Conventional technology]

When cooking packaged foods such as wontons, oden, meatballs, etc. in a microwave, it is convenient to be able to heat the entire container in which the food is packaged. (simply referred to as packaging) are becoming popular. This package is sealed to prevent foreign matter and bacteria from getting mixed in during the distribution process, and if you heat it in the microwave, the pressure of the steam generated will cause the container to rupture, so just before cooking, do not heat the package. It is used by making a hole for escape and removing the lid. This kind of thing is troublesome and tends to result in over-heating or under-heating.
This is because the time suitable for heating each food package differs depending on the wattage of the microwave oven. Recently, we have developed a package that saves the hassle of making holes for water vapor to escape, and also makes it easy to tell when the necessary heating has been completed.
When the seal was peeled off, there were several holes, and as the internal pressure rose, the lid expanded to open the holes. The lid swells as steam escapes through the holes, and once this is done, cooking is complete. Therefore, over-heating or under-heating can be avoided. In order to sufficiently heat the contents of this type of package, even if water vapor is generated, it should not be immediately released, but should be stored for a certain period of time so that the temperature increases as the pressure increases. However, it is difficult to control and create a package so that the hole opens when the inside reaches a desired temperature and pressure.

[Problems to be solved by the invention]

The purpose of the present invention is to improve the above points, eliminate the need to make holes for steam to escape prior to cooking, and raise the internal temperature by storing a certain amount of steam without the problem of overheating or underheating. It is an object of the present invention to provide a food package for cooking in a microwave oven, which can realize optimum cooking conditions. Gorika for Yu

[Means to solve the problem]

As shown in FIGS. 1 and 2, a food package 1 for cooking in a microwave oven according to the present invention is a package 1 for cooking food 2 in a microwave oven. 31 is provided with a hole 4 for letting water vapor escape, and this hole is blocked to form a base film 51 as shown in FIG.
It is characterized in that a valve seat 5 having a layer 52 of an object that generates heat by microwaves is attached thereon using an adhesive 6. The container has an outer surface made of polyester, polypropylene, nylon, cellophane, or a plastic film coated with polyvinylidene chloride, and an inner surface made of a plastic coating layer or film of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or ionomer. It may be made of a certain laminated material and made into a three-sided sealed bag or a pillow-type bag, or it may be a tray with a lid formed by suitable means such as vacuum forming. The shape of the hole for escaping water vapor is arbitrary, but the diameter is 2 to 10 mm.
A round hole of about * is suitable. As the base film for the valve seat, a plastic film with relatively high heat resistance, such as polyester, nylon, or polypropylene, may be used. Indium tin oxide or metals such as aluminum, nickel, and tin are used as the object that generates heat by microwaves, and a thin film is formed. The thin film is formed by vapor deposition, sputtering, or the like. It is preferable that the thin film of the heat-generating object is provided so that the surface resistance is in the range of 10 to 10<4 >Ω/i. As shown in FIGS. 3 and 4, a protective film 7 may be provided on the layer of the object that generates heat by microwaves to protect the surface. As the protective film, the same one as the base film for valve seats may be used. Adhesives include adhesives such as rubber-based and acrylic resin-based adhesives, hot-melt adhesives such as ethylene-vinyl acetate copolymer-based, polypropylene-based, polyester-based, and polyamide-based adhesives, and polyester-based and ethylene-vinyl acetate copolymer-based adhesives. Use hot lacquers or heat sealants such as polyethylene, polypropylene, ethylene-vinyl acetate copolymers, ionomers, etc. In either case, it is preferable that the adhesive force suddenly decreases when the temperature reaches a certain level.

[For use]

When the food package 1 for microwave cooking of the present invention is heated in a microwave oven, the package swells slightly due to the pressure of water vapor generated from the contents. On the other hand, since the layer 51 of the heat-generating object absorbs microwaves and generates heat, the adhesive 6 is softened by the heat and its adhesive strength is reduced. During this time, heating efficiency is high because no heat escapes. When the temperature of the valve seat 5 reaches a certain limit and the water vapor pressure rises above a certain limit, as shown in FIG. It peels off naturally from its surroundings, creating a path for water vapor. Once the water vapor escapes, the package will naturally shrink back to its original shape. In this way, heating is carried out without the bag breaking, and optimal cooking can be achieved, with the food being cooked only when it deflates and returns to its original shape.

Example 1 A thin film of indium tin oxide was provided on a polyester film having a thickness of 12 μm, and the film was cut into a size of 1 Q x 10 mm to prepare a valve seat. (Outside) Polyester 12μ/Polyethylene 40μ (Inside)
A laminated material was prepared by dry lamination, and a circular drop lid with an outer diameter of 150 am was made using this material, and a round hole with a diameter of 5 m was provided on the surface of the lid. The surface of the polyester film of the valve seat was bonded onto the hole of the drop lid using an ethylene-vinyl acetate copolymer hot melt adhesive. Separately, using a polypropylene film of 500μ, an outer diameter of 1
A circular container body containing 50 shoes was made. The cooked Yakisoba was placed in this container body, and the drop lid was sealed by heat-sealing to form a food package for microwave cooking. When the package was placed in a microwave oven and heated, the drop lid of the package expanded and after a while, a portion of the valve seat peeled off from around the hole in the lid, and water vapor escaped through the passageway, causing the drop lid to close. Concave. When a portion of the valve seat was peeled off from the lid, the temperature of the valve seat portion was measured and found to be 80°C. When the package was opened, delicious Yakisoba was found. (Example 2) A valve seat was made by laminating a polyester film with a thickness of 50μ as a protective film on the same valve seat as in Example 1. (Outer) A laminate of 12μ polyester/40μ polypropylene (inner) A drop lid similar to Example 1 was prepared by dry lamination. The above valve sheet was pasted on the hole of the drop lid using polyester hot lacquer.A container body similar to Example 1 After putting the cooked thalam chowder into the container and sealing it by gluing the above-mentioned drop lid with a heat seal, it was sterilized in a retort at a temperature of 120°C for 30 minutes. Under these conditions, of course, the valve seat did not come off. When the food package for microwave cooking was heated in a microwave oven, the temperature of the valve seat part was 140℃.
At this point, a portion of it peeled off from the lid. [Examples 3 to 5] Examples 3 to 5 were carried out in the same manner as in Example 1, except that the following adhesive was used, and similar results were obtained. Also record the temperature of the valve seat when part of the valve seat peels off from the lid. Circulation Adhesive Temperature 3 Rubber adhesive 80℃ 4 Polyamide hot melt 120℃ 5 Acrylic resin adhesive 90℃

Example 6 A 12 μm thick polyester film having a thin aluminum film was cut into a size of 1 Q x 10 mm to form a valve seat. Other than that, it was carried out in the same manner as in Example 1, and the same results were obtained. When a portion of the valve seat was peeled off from around the hole in the drop lid, the temperature of the valve seat portion was 80°C. By using the food package for microwave cooking of the present invention, there is no need to make holes to release water vapor prior to cooking, and cooking can be carried out without overheating or underheating. The best condition is when the container is deflated, and there is no need to adjust the heating time according to the microwave instructions.

[Brief explanation of the drawing]

1 and 2 both show an example of the food package for microwave cooking of the present invention, with FIG. 1 being a plan view and FIG. 2 being a sectional view. 3 and 4 are detailed views of the valve seat portion for explaining the function of the package of the present invention,
3 is a cross-sectional view taken along the line I--I in FIG. 1 before the package is heated, and FIG. 4 is the same cross-section as above with the package heated. 1... Food package for microwave cooking 2... Food 3... Container 31... Lid 4... Hole 5... Valve seat 51... Base film 52... Heat generation Layer 6 of the object to be attached...Adhesive 7...Protective film Figure 1

Claims (3)

[Claims] (1) In the package 1 for cooking food 2 in a microwave oven, holes 4 are provided in the container 3 to allow water vapor to escape,
A food package 1 for cooking in a microwave oven is characterized in that this hole is closed and a valve seat 5 having a layer 52 of an object that generates heat by microwaves is attached onto a base film 51 using an adhesive 6. (2) The food package 1 for microwave cooking according to claim 1, wherein the object that generates heat by microwaves is selected from indium tin oxide, aluminum, nickel, and tin. (3) The food package 1 for microwave cooking according to claim 1, wherein the object that generates heat by microwaves has a surface resistance of 10^1 to 10^4 Ω/cm^2.