JPH1159747A - Packaging body for microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic packaging body which can be heated in a microwave oven as it is, without making holes before heating or unsealing it by cutting a part thereof. SOLUTION: A multi-layer laminate body composed of a plurality of layers including at least a sealant layer which can be heat-sealed, is heat-sealed to form this packaging body 10. Cyclized rubber peelable layers 12 are formed in advance to partly contact at least a heat-sealed part of the heat-seal part 11 of the sealant and peeled to open the heat-sealed part by a pressure when the inside pressure of the packaging body has reached a certain value by heating it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package for a microwave oven used for packaging frozen foods, chilled foods and the like which can be heat-treated in a microwave oven or the like.

[0002]

2. Description of the Related Art It is accepted that frozen foods, such as dim sums such as shumai and meatballs, and baked rice balls, which can be cooked simply by heating, can be cooked easily and in a short time. Various products have been commercialized and sold according to the diversifying needs of family. Packaging materials used for these food packages are required to have good airtightness, gas barrier properties against oxygen, and the like. For this reason, packaging materials in which a heat-resistant plastic film and a metal foil are stacked and laminated are often used. As an example of the laminated packaging material, a material obtained by laminating an aluminum foil on an outer layer polyester film and laminating a polypropylene on the aluminum foil as an inner layer is often used. A bag-shaped package using this packaging material, filled with foodstuffs, and sealed by heat sealing has been commercialized.

A package made of such a metal foil or a packaging material containing a metal deposited with a metal has no problem when heated with steam (hot steam), but when heated with a microwave oven, it has a microstructure. There is a problem that sparks are generated by waves and cannot be heated by a microwave oven.

In order to be able to heat in a microwave oven,
It is necessary to use packaging materials that do not contain metals,
Plastic materials such as polyethylene, polypropylene, ethylene / vinyl alcohol copolymer, ethylene / vinyl acetate copolymer, ethylene / methacrylic acid copolymer, and polyvinylidene chloride are used. If the frozen food produced in this plastic package is heated as it is, the moisture contained in the content evaporates, increasing the pressure inside the container, and the package ruptures, and there is a risk of soiling the microwave oven and sometimes burning.

In order to prevent the rupture of the package, it is necessary to make a hole before heating with a microwave oven or to cut a part of the package to open the package, which is troublesome. There has been a strong demand to heat the package in a microwave oven without any modification. Conventionally, to release steam from the seal by the steam pressure during heating, silicone, ethylene-vinyl acetate copolymer, polyamide / Nitrocellulose coated the seal as a release agent. However, these release agents have problems such as poor production adequacy, poor sealing strength and impaired sealing, and insufficient sealing strength but not opening within the heating time.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a plastic package which can be heated in a microwave oven. The package is opened by opening a hole or cutting a part of the package before heating in a microwave oven. The present invention provides a package which can be heated in a microwave oven as it is without being heated, reliably opened from the peeling layer portion by vapor pressure, and has excellent sealing performance before heating.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a package obtained by heat-sealing a multilayer laminate comprising at least two layers including at least a heat-sealable sealant layer. The cyclized rubber peeling is performed in such a manner that at least a part of the heat seal surface of the sealant to be heat-sealed is applied in advance, and when the internal pressure of the package becomes a certain level or more, the heat seal portion can be peeled and opened by the pressure. A package for a microwave oven, wherein a package is formed.

The microwave package according to claim 1, wherein the base film of the multilayer laminate is a barrier film on which an inorganic oxide is deposited.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows the appearance of a package after heat sealing, which is an example of the present invention. FIG. 1A shows an example in which a striped cyclized rubber release layer is pattern-coated in the flow direction, and FIG. This is an example in which a striped cyclized rubber release layer is pattern-coated. FIG. 2 is a cross-sectional view of the packaging material before heat sealing, and FIG. 3 is a cross-sectional view of a heat-sealed portion of the package XX of FIG. 1A. FIG. 4 is a cross-sectional view showing a state in which an opening is formed by peeling from the cyclized rubber peeling layer when the package XX of FIG. 1A is heated. The packaging form may be a four-sided seal packaging, a three-sided seal packaging, a pillow package, a gusset package, or the like as shown in FIG.

FIG. 1 shows that the cyclized rubber peeling layer (12) is partially applied to the heat seal portion (11) of the sealant of the package (10) so that the pressure inside the package is kept above a certain level by heating. When the heat seal part (1)
1) shows a package that can be opened by peeling from the cyclized rubber peeling layer. By forming the cyclized rubber release layer (12), it is not necessary to open the package in advance when heating in a microwave oven, and it is possible to perform heating while maintaining the sealing property, and the opening is ensured. The rupture of the package due to an increase in pressure inside the package can be prevented.

As the base film (1), polyester (PET), polypropylene (PP), nylon (N
A plastic film having heat resistance such as y) is used, and a thermoplastic resin such as unstretched polypropylene (CPP), low-density polyethylene (LDPE), or linear low-density polyethylene (L-LDPE) is used as a sealant layer. . When laminating the thermoplastic film to a base film as a sealant layer (3) to produce a packaging material, an adhesive layer (2) is provided as necessary. (Fig. 2)

Further, a barrier film on which an inorganic oxide such as silicon oxide or aluminum oxide which has a high barrier property against oxygen and water vapor for protecting the contents of food is used as a base film or as a base film. When a composite film obtained by laminating a film is used, a package having excellent gas barrier properties can be obtained.

The cyclized rubber release layer (4) is formed on a portion of the sealant layer (3) before heat-sealing which partially overlaps a portion to be heat-sealed. (See FIG. 3).

When the pressure inside the package rises to a certain level or more due to the steam generated from the food as the content due to the heating, the pressure from the interface between the cyclized rubber release layer (4) and the sealant layer (3) increases. An opening (5) is formed by peeling and opening, and the pressure is reduced by evacuating from the opening (5) to prevent the rupture of the package. (FIG. 4)

The cyclized rubber release layer is formed by diluting with an appropriate solvent such as toluene or benzene, forming an ink, and applying the ink by gravure printing or the like. The cyclized rubber release layer is heat-sealed (1
If it is formed over the entire surface of 1), the opening location cannot be determined, or the wrapper is broken when it is taken out, and it is difficult to carry. Therefore, it is preferable that the wrapping is formed so as to partially cover the heat seal portion (11).

Regarding where and how many and what width the cyclized rubber release layer (12) is to be provided in the heat seal part (11), the weight of the food as the contents,
What is necessary is just to select and determine suitably according to a kind, the shape of a package, etc. Although FIG. 1 shows the cyclized rubber release layer formed in a stripe shape, the shape of the cyclized rubber release layer may be arbitrarily set.

<Example> 20 μm thick base film
a laminate obtained by laminating a non-stretched polypropylene (CPP) having a thickness of 25 μm as a sealant layer (3) via an adhesive layer (2) on a stretched polypropylene (OPP) having a thickness of m and having no release layer ( Comparative example), one having a release layer of 5 mm width using polyamide / nitrocellulose as a release agent (Comparative example), one having a release layer of 5 mm width using cyclized rubber as a release agent (Example) Then, each food (frozen sea mai) was sealed in a four-sided manner (sealing width: 10 mm) to prepare a 20 cm square package.

These packages are placed in a microwave oven 500W, 3
After heating for one minute, the state after the heating was visually evaluated.

[Evaluation Results of Package] Evaluation Results % Opened by heating Comparative Example: Burst: 0% Comparative Example: Bursting, non-bursting mixture: 65% Example: All without bursting: 100% A package having a release layer formed of polyamide / nitrocellulose, which is a conventional release agent, may or may not be opened. However, it is reliably opened by forming a release layer of cyclized rubber as the release agent of the present invention. Was confirmed.

[0020]

According to the package of the present invention, since the opening is surely opened when heating, it is necessary to make a hole or cut a part before opening the package before heating in a microwave oven. Eliminate the hassle of becoming unnecessary. Moreover, there is no danger of burning the microwave oven and no risk of burns due to the rupture.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the package according to claim 1 of the present invention, in which (a) is an example in which a cyclized rubber release layer is pattern-coated in the flow direction, and (b) is a cyclized rubber release layer. This is an example in which a layer is pattern-coated in the width direction.

FIG. 2 is a cross-sectional view illustrating a configuration of a laminate before heat sealing.

FIG. 3 is a cross-sectional view showing a configuration of a heat-sealed portion of a package XX of FIG. 1A.

FIG. 4 is a structural sectional view of a portion of the package XX of FIG. 1A that is opened by heating.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base film 2 ... Adhesive layer 3 ... Sealant layer 4 ... Cyclic rubber peeling layer 5 ... Opening 10 ... Package 11 ... Heat seal part 12 ... Cyclic rubber peeling layer part

Claims (2)

[Claims] 1. A package obtained by heat-sealing a multilayer laminate composed of at least two layers including at least a heat-sealable sealant layer, wherein at least a portion of the heat-sealing surface of the sealant is heat-sealed in advance. A package for a microwave oven, wherein a cyclized rubber release layer is formed so that the heat seal portion can be peeled open when the internal pressure of the package becomes equal to or higher than a predetermined value. 2. The microwave oven package according to claim 1, wherein the base film of the multilayer laminate is a barrier film on which an inorganic oxide is deposited.