JP2001010663A - Lunch packaging member for microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a deformation of a lunch packaging member packaged by a thermal shrinkage tube caused by a secondary shrinkage of a tube from being carried out even if the lunch packaging member is heated in a microwave oven at a shop in particular. SOLUTION: This lunch packaging member has a packaging form in which a non-thermal shrinkage film 21 and a thermal shrinkage film 22 are connected in their circumferential direction with their mutual end edges being applied as adhering margins, a tube 20 with a circumferential width of the thermal shrinkage film 22 being less than 1/2 of an entire circumferential length of the tube is used, it is shrunk into a tube circumference length which is approximately equal to an outer circumferential length of the lunch container and the film is fastened to the lunch container. As a restricting effect of an amount of shrinkage of the tube 20, it is possible to fasten the film around the lunch with a proper amount of thermal shrinking force and even if heat is applied to the lunch in the micro-wave oven while it is being kept in the packaging member, the container is not deformed and a fawarable packaged state is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved lunch box package for heating a microwave oven, and more particularly to an improved lunch box package having a plastic film tube fastened to a container by heat shrinkage.

[0002]

2. Description of the Related Art A lunch box sold at a convenience store or the like is prepared by packing cooked foods such as cooked rice, prepared dishes, and pasta in a sheet-shaped shallow box-shaped plastic container, covering the lid, and wrapping the film. It has a wrapping form.
Recently, as a packing form of a lunch box, a tube made of a heat-shrinkable plastic film (heat-shrinkable tube) is put on the lunch box container, and tightened around the container by heat shrinkage.
A packaging form in which a container body and a lid are bound is being adopted. The heat-shrinkable tube is provided with an opening diameter somewhat larger than the container cross-section of the lunch box to be attached for convenience of the fitting operation to the lunch box. Completes the packaging by heat shrinking (reducing the perimeter) to approximately match the cross-sectional diameter of the lunch box and tightening to the container peripheral surface

[0003]

However, a packed lunch using a heat-shrinkable tube tends to cause deformation of the container and distortion of the tube. FIG. 5 shows an example. (1
Reference numeral 0) denotes a lunch box, and reference numeral 30 denotes a heat-shrinkable tube. The lunch box (10) is deformed (a), and the tube (30) is distorted (b). This is a tube (3
This is because the tightening force accompanying the heat shrinkage of 0) was applied too strongly. Such a problem is caused by adjusting the processing conditions such as the heating temperature and time based on the heat shrinkage of the tube (30) and the size of the extra length given to the tube (30) so as to obtain an appropriate amount of shrinkage. If it does, it can be avoided. However, it is extremely complicated and difficult to implement such control of heat shrinkage in actual operation.

[0004] Lunch packages are often reheated in a microwave oven at the store in response to a request from the purchaser. When the food in the container is heated by microwave irradiation of the microwave oven, the tube (30) is heated by conduction of heat from the inside of the container and contact of steam and hot air generated from the inside of the container, resulting in heat shrinkage (2). Next contraction). When a strong clamping force is applied due to the heat shrinkage, as shown in FIG. 6, the container body (11) and the lid (12) are disengaged due to the deformation, and the hermetically sealed state is impaired. It will cause trouble. If the package is deformed, it is also difficult to easily remove the tube (20) with a fingertip when opening the package. An object of the present invention is to solve the above-mentioned problems relating to a microwave oven packed lunch package packaged with a heat-shrinkable tube.

[0005]

According to the present invention, there is provided a package for microwave oven heating, wherein the package is covered with a synthetic resin film tube and is fastened to the peripheral surface of the container. Is a non-heat-shrinkable film (2
1) and the heat-shrinkable film (22) are joined in the circumferential direction by using both ends of the heat-shrinkable film (2) as bonding margins, and the heat-shrinkable film (2)
The circumferential width of 2) is a cylindrical body having a length equal to or less than 1/2 of the entire circumferential length of the tube, and shrinks to a tube circumferential length substantially equal to the outer circumferential length of the lunch container due to the heat shrinkage of the heat-shrinkable film (22). And has a packaging form fastened to a lunch container.

[0006] The tube (20) of the packed lunch package comprising a combination of the non-heat-shrinkable film (21) and the heat-shrinkable film (22) of the present invention is a partially shrinkable tube, and the heat-shrinkable film (22). ) Is regulated to less than half the circumference of the tube (the length in the circumferential direction of the tube).
Compared to the case where the entire tube is a heat-shrinkable film, the decrease in the opening diameter (shortening of the tube circumference) due to heat shrinkage is small, and the heat-shrinkage rate remaining in the heat-shrinkable film (22) after mounting is also small. . As the effect of regulating the amount of shrinkage,
In the heat treatment step of attaching the tube to the lunch box, it is easy to fasten the tube (20) around the container with an appropriate heat shrinking force, and the container main body (11) and the lid (12) have a moderate tightening force. To obtain a bundled packaging form. Even in the case where microwave heating is performed at a store, excessive heat shrinkage that may deform the container can be avoided, and a predetermined packaging form can be stably maintained.

[0007] The non-heat-shrinkable film (21) of the tube (20) is substantially used for both heat treatment for attaching the tube to the lunch box and heating in the microwave oven for heating the contents of the packed lunch box. There is no significant shrinkage deformation, so that a bar code, the date of manufacture, a description article (A) of the contents, etc. can be printed on the film surface, and a clear printed display can be maintained as it is.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a tube (20) used for a lunch package of the present invention. Tube (2
0) connects the non-heat-shrinkable film (21) and the heat-shrinkable film (22) to each other's edge portions (21 ₁ , 21 ₂ ) (2).
2 ₁ , _{2 2 2} ) are stacked one on top of the other as an adhesive margin, and are formed into a cylindrical shape by heat bonding or bonding via an appropriate adhesive.

The non-heat-shrinkable film is a plastic film (heat shrinkage at 100 ° C .: less than 3%) which does not substantially cause heat shrinkage. For example, a biaxially stretched film made of polyester, polypropylene, polyamide or the like is used. used. The film (21) constituting the tube (20) has a film thickness of 10 to 100 µm (preferably 12 to 40 µm).

The heat-shrinkable film (22) is preferably a uniaxially stretched film, and the stretch direction (heat-shrinkage direction) of the heat-shrinkable film (22) is joined to the non-heat-shrinkable film (21) in the circumferential direction of the tube (20). Construct a tube (20). The heat shrinkage of the heat shrinkable film is usually about 30 to 70%. In addition, even in the case of a biaxially stretched film, the main shrinkage is one direction (one heat shrinkage rate in two directions perpendicular to the plane is about 3%).
(0 to 70%, the other about 15% or less), it can be used in the same manner as the uniaxially stretched film. The material type of the heat-shrinkable film (22) is, for example, polyester (such as polyethylene terephthalate), polypropylene,
Polystyrene, polyvinyl chloride, etc., and the film thickness is 10 to 100 μm (preferably 20 to 40 μm).

The above-mentioned tube (20) is provided with the above-mentioned tube (30) in order to ensure the operability of being fitted to the lunch box (10).
Similarly, the opening diameter is larger than the cross-sectional size of the attached lunch box (10). For example, the circumference is about 2 to 20% of the outer circumference of the lunch box (10) to be mounted.
It is additional length. The circumferential length of the heat-shrinkable film (22) is equal to or less than 全 of the entire circumferential length of the tube (20), thereby preventing the tube (20) from undergoing excessive heat shrinkage. The specific width size of the heat-shrinkable film (22) is determined by the heat shrinkage of the film and the tube (2).
It is set according to the total circumference of 0), heating conditions (temperature / time) in the tube mounting step, and the like.

FIG. 2 shows a state in which the tube (20) is fitted to a lunch box (10) to be mounted. The figure shows an example in which the tube (20) is covered in a direction in which the heat-shrinkable film (22) is located on the lower surface side of the lunch container.
The present invention is not limited to this, and may be directed to the side surface of the container, or may be covered so as to extend from the lower surface to the side surface.

The tube (2) covered by the lunch box (10)
The heat shrinking treatment of 0) is performed according to a conventional method, and the entire periphery of the tube (20) is fastened to the container peripheral surface of the lunch box with the heat shrinkage of the heat shrinkable film (22), as shown in FIG. As shown, the package is finished in a good packaging form without deformation of the container. In this heat treatment, the tube (3
0) Unlike the case where (the entire tube is made of a heat-shrinkable film), it is not necessary to heat the entire peripheral surface of the tube, and only the portion of the heat-shrinkable film (22) is heated. Can be completed, and the heat energy required for mounting the tube can be reduced.

[0014] In the microwave oven heating, the packed lunch box of the present invention equipped with the tube (20) as described above is heat-shrinkable due to heat conduction from the heated food and contact of steam / hot air generated from the food. Even if the film (22) is heated,
Since it is partially shrinkable and has a low residual heat shrinkage, the change in the circumference of the tube is small, and a good packaging form is stably maintained. In particular, when the tube (20) is attached with the heat-shrinkable film (22) facing the bottom of the container, the heat-shrinkable film (22) has little thermal influence from the inside of the container (microwave oven heating is difficult). In general, the microwave radiation from the lower side is small, and the heating and heating of the lower side of the food in the container is delayed as compared with the upper side, so that the thermal influence on the heat-shrinkable film (22) is reduced accordingly). Tube (2)
The circumference reduction of 0) does not substantially occur, or even if it occurs, the change is suppressed to a very small amount.

As a measure for facilitating the opening of the package at the time of eating a lunch, a perforation for breaking is usually engraved on the tube.
0) is not always necessary. If the bonding margin between the non-heat-shrinkable film (21) and the heat-shrinkable film (22) is adhered to the extent that it can be separated, the tube (20) can be removed by peeling off the portion. Although the adhesive surface shows a strong adhesive force against the shearing force, the direction perpendicular to the adhesive surface can be peeled off with a relatively small force of the fingertip. In order to improve the peeling property, it is preferable that the bonding margin is overlapped so that the heat-shrinkable film (22) is on the outside as shown in FIG. In addition, if the tube (20) is attached so that the joining margin (only one of the two bonding margins) is located on the side surface of the container, the opening operation is easy.

[0016]

EXAMPLE A partially packed tube is used to form a lunch package (see FIG. 4 for the specifications of each component). (1) lunch (10) the outer periphery of the container length _(L A): 324 mm Width _(w A): 120 mm Height _(h A): 42mm (2) tube (20) circumference _(L C): 360 mm (remaining Length 36mm = 360mm
-324 mm) Circumferential length (L _N ) of non-heat-shrinkable film (21): 240
mm (including the bonding margins) circumferential length of the heat-shrinkable film _{(22) (L S):} 120m
m (excluding bonding margin) Heat shrinkable film Heat shrinkage: 50% (at 90 ° C hot water x 1)
0 seconds)

(3) Attaching the tube The tube is put on the lunch box and attached by a heating treatment (hot air blowing). Hot air temperature: 100 ° C, heating time: 8 seconds. (4) Lunch package body Perimeter of tube (after heat shrinkage): 320 mm (reduction amount Δ
L = 40 mm) Width of heat-shrinkable film (after heat shrinkage): 80 mm (reduction amount ΔL = 40 mm) The perimeter of tube (20) 320 mm attached to the lunch box is slightly longer than the outer circumference length of the lunch box 324 mm. It is small and is fastened to the lunch box (10) with a moderate tightening force.

The amount of shrinkage of the heat-shrinkable film (22) in the heating and mounting step of 40 mm is about 33% [= (120−80) / 120 × 100] in terms of shrinkage, and about 17% (= 50-33%), the residual is heat shrinkable at high temperature, the amount of shrinkage is small, and the inside of the container is heated by microwave heating at a store. Even if the food is subjected to the secondary heating by the heat from the food, a large shrinkage that deforms the container does not occur.

In the packaging of the lunch box in the above embodiment,
Instead of the partially shrinkable tube (20) of the present invention, a tube (3) consisting only of a heat shrinkable film (heat shrinkage of 50%)
0), a heat shrinkage of about 11% [= (360
mm-320mm) / 360mm × 100,%], which can be attached to the lunch box by heating conditions (temperature, time,
It requires delicate adjustment of the amount of hot air, and it is difficult to stably maintain an efficient mounting operation. Moreover, the thermal shrinkage remaining in the attached tube (20) is about 39% (= 5%).
(0-11%), when subjected to secondary heating from a heated food in a microwave oven, a large shrinkage force is generated and the container is deformed.

The heat-shrinkable film tube (30) is used to fasten it to the peripheral surface of the lunch container at the same shrinkage rate of 33% as in the example (the tube circumference is 3 mm by heat shrinkage).
If the tube is reduced to 20mm)
It is necessary to use a tube having a large opening diameter exceeding a circumference of about 477 mm, so that a large amount of film is used and an increase in material cost is inevitable. In addition, since the opening diameter of the tube is large, it is extremely difficult to position the tube relative to the lunch box (10), and the printed display on the film surface is liable to cause large distortion, which is not practical.

[0021]

According to the present invention, it is possible to obtain a packaging form free from deformation of a bento container and distortion of a tube, and the secondary shrinkage of a tube can be obtained even when the bento package is heated in a microwave oven at a store. In addition, the deformation of the package body caused thereby can be suppressed and a favorable packaged state can be stably maintained. In the tube mounting step, it is only necessary to selectively heat only the heat-shrinkable film portion, the energy consumption required for mounting the tube is reduced, and the mounting cost is improved. Further, the tube of the lunch package of the present invention,
Since the non-heat-shrinkable film is located on the upper surface of the package, the items related to the product (bar code, date of manufacture,
(E.g., description of the contents) can be printed and displayed, and a clear display can be maintained without undergoing a state change even after being subjected to the heat treatment.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a tube used for forming a lunch package of the present invention.

FIG. 2 is a view schematically showing a state in which a partially contracted tube of the present invention is put on a lunch box.

FIG. 3 is an external perspective view showing an example of a packed lunch box of the present invention.

FIG. 4 is an explanatory diagram of specifications of the packed lunch box of the present invention.

FIG. 5 is an external perspective view showing an example of a conventional lunch package.

FIG. 6 is an external perspective view showing an example of a conventional lunch package.

[Explanation of symbols]

 10: Lunch 11: Container body 12: Lid 20: Partially heat-shrinkable tube 21: Non-heat-shrinkable film 22: Heat-shrinkable film 30: Heat-shrinkable tube p: Bonding allowance A: Printed display

Claims (2)

[Claims] 1. A microwave oven-heated lunch package comprising a synthetic resin film tube placed over a lunch container packed with food and covered, and fastened to the peripheral surface of the container, wherein the tube is made of a non-heat-shrinkable film ( 21) and a heat-shrinkable film (22) are joined in the circumferential direction by using both end edges as bonding margins, and the circumferential width of the heat-shrinkable film (22) is not more than の of the entire circumferential length of the tube. A package for heating a microwave oven, wherein the package is shrunk to a tube circumferential length substantially equal to the outer peripheral length of the lunch container by heat shrinkage of the heat-shrinkable film (22) and fastened to the lunch container. 2. The package for microwave oven heating according to claim 1, wherein the tube (20) is attached to the lunch container with the heat-shrinkable film (22) facing the bottom of the container.