JPS62271864A - Sealed vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a sealed container whose lid body is sealed by a lid mainly made of thermoplastic, and which is particularly suitable for heating in a microwave oven. Concerning sealed containers.

(Prior Art) Recently, there have been many containers on the market that contain food and are sealed with lids mainly made of thermoplastic plastic. When food in a sealed container of this type is heated in a microwave oven prior to consumption, the food contains water;
For example, when cooking rice, the vapor pressure of the water in the food causes the lid or container body to burst, causing the problem that the contents spill out from the container.

(Problems to be Solved by the Invention) The present invention relates to a sealed container whose lid body is sealed by a lid mainly made of thermoplastic plastic, which stores contents including water, and which stores the contents electronically. It is an object of the present invention to provide a sealed container that is free from the risk of bursting due to the internal pressure of water vapor even when heated in a microwave oven or the like, that is, when heated by applying a high-frequency electric field.

(Means for Solving the Problems) The sealed container of the present invention is a sealed container in which the lid body is sealed by a lid mainly made of thermoplastic plastic, and the lid body is made of thermoplastic plastic in a high frequency electric field. A layer that heats up rapidly is attached locally, and when the sealed container is inserted into the high-frequency electric field, the portion of the lid body to which the layer is attached, or the layer, melts and perforates. It is characterized in that a portion is formed.

The lid body is made of thermoplastic plastic with a non-conductive inorganic coating (e.g. silicon oxide, aluminum oxide,
It may also be formed of magnesium fluoride (having barrier properties).

(Function) In the sealed container of the present invention, the layer A, which heats up rapidly due to resistance loss, magnetic loss, discharge, etc. in a high frequency electric field, is localized rather than the thermoplastic plastic or inorganic coating forming the lid body. Attached to the lid body.

Therefore, when this sealed container is placed in the high-frequency electric field, for example in a microwave oven, layer A reaches a temperature far higher than the melting point or softening point (in the case of non-grade plastic) of the thermoplastic. It heats up faster than the lid itself.

As a result, if the plastic in the part of the lid body to which layer A was attached melts due to heat transfer through layer A, reaching a temperature above the softening point and softening, this is also referred to as melting in this specification). Either only a portion is perforated, or layer A is perforated or burnt out by the heating.

Even if the inorganic film is formed, this film is very thin and brittle, so holes are formed in the layer A as it melts. Therefore, the water vapor generated within the container leaks out from the perforated portion, thereby preventing a major rupture of the container.

(Example) In FIGS. 1 and 2, l is a sealed container, in which the contents such as food containing water are placed in a cup-shaped container body 2 made of thermoplastic plastic, leaving a head space 4. 3,
For example, after filling with cooked rice, the lid 5 is heat-sealed to the flange portion 2a.

The lid 5 is made of a thermoplastic plastic such as polypropylene, linear polyester, or a laminate of these and a gas barrier plastic (such as an ethylene-vinyl alcohol copolymer). (
The printed film 7 (in the figure, a small circular shape) is formed.

The printed film 7 is formed by applying and drying a conductive paint containing conductive powder such as metal powder or Kazen powder, or a magnetic paint containing magnetic powder such as ferrite. When this sealed container 1 is placed in a high-frequency electric field in an upright position with the lid 5 facing upward, the printed film 7 will experience resistance loss due to the induced current flowing within the printed film 7 (in the case of conductive paint). Alternatively, the printed film 7 is rapidly heated due to magnetic loss due to magnetic flux induced in it (in the case of magnetic paint), and the portion 6a of the lid body 6 coated with the printed film 7 is melted due to the action of surface tension. This becomes a perforation (not shown).

During this time, the temperature rise in other parts of the lid main body 6 due to the high frequency dielectric heating effect is relatively small. On the other hand, water vapor is generated in the container 1 due to dielectric heating of the water in the contents 3, but this water vapor escapes from the perforation, so that the lid 5 or the container body 2 does not burst. Moreover, since there is a head space part 4, the contents will not spill out from the perforation part.

The lid 15 shown in FIG.
A conductive (e.g., aluminum, chromium, tin oxide, or indium oxide) vapor-deposited film 18 is formed, and a thermoplastic film (e.g., a polyethylene terephthalate film) having the same shape as the sheet 17 is formed thereon.
19 It is completely glued together. In this specification, the sheet 17 and the film 19 are collectively referred to as the lid body 16.

In this case, the vapor deposited film 18 is rapidly heated by electric discharge in the high frequency electric field, and the portion 17a1 of the sheet 17 of the lid body below it and the portion 19a of the film 19 of the lid body above it are melted, and the vapor deposition film 18 is It burns away and a perforation is formed.

The lid 35 shown in FIG. 4 and FIG.
A ring 38 made of aluminum or iron foil (m) is embedded by thermocompression bonding. The ring 38 has a locally narrowed portion 38a formed therein. When placed in a high-frequency electric field, an induced current flows along the wire 38, and since the narrow portion 38a has a particularly large resistance, it generates a particularly high amount of heat.
The lower portion 36a of the lid body 36 is melted to form a perforation.

Note that a ring may be used in which the width of the portion corresponding to the narrow portion 38a is the same as that of the other portions, but is particularly thin. In the case of the example shown in FIG. 7, if the inner diameter of the ring 38 is small, there is a risk that the water content will boil before the perforation is formed. Therefore, it is necessary to set the inner diameter of the ring 38 to a size that does not cause the above-mentioned phenomenon, depending on the material, thickness, width, and type and amount of contents of the ring 38. For example, when the ring 38 is made of aluminum or iron foil with a thickness of about 15 to 20 μm and the width (excluding the narrow portion 38) is 1.6 m, the inner diameter of the ring 38 is preferably about 30 m or more.

Note that the ring 38 may be formed of a metal vapor-deposited film having a thickness of about 1 μm or more instead of the metal foil.

The lid 45 shown in FIGS. 6 and 7 has a ring 48 embedded in a lid body 46 made of thermoplastic plastic. The main part of the guide 8 is a metal (for example, aluminum or iron) foil or sheet portion 48a;
A portion is made of a conductive coating film or glass portion 48b (hereinafter referred to as conductive resin portion) containing conductive powder or the like. In this case, in the high-frequency electric field, the conductive resin part 48b, which has a high electrical resistance, heats up particularly rapidly and melts or burns out, and the lower part 46a of the lid body 46 melts and becomes perforated. give rise to part.

The lid 55 shown in FIGS. 8 and 9 has a lid main body 561C made of thermoplastic plastic and a ring 58 made of thermoplastic plastic mixed with metal powder embedded throughout its entire thickness. Although most of the ring 58 is a relatively narrow portion 58a, it has a wide portion 58b that locally protrudes outward in the radial direction. The wide part 58b has a higher content of metal powder per unit volume than the narrow part 58a, and therefore the narrow part 58a has more resistance loss in a high frequency electric field. The narrow portion 58a is melted to form a circular hole, but the wide portion 58b is not melted and remains as it is.

The present invention is not limited to the above embodiments,
For example, the container body may be a glass bottle or a relatively shallow and wide metal can, and the lid may be sealed by an appropriate method depending on the combination of the lid and the container body, such as adhesion with hot melt adhesive, Alternatively, a double-sealing method or the like is adopted. Further, the shape of the lid can also be changed to an appropriate shape.

Next, a specific example will be described.

Specific example l.

After filling the container body 2 of the type shown in FIG. 1 with cooked rice leaving a head space 4 of height h5, the lid 15 of the type shown in FIG. 3 is heat-sealed to the flange 2a to seal it. A container was made.

The container body 2 is a laminate made of a 380 μm thick polypropylene outer layer, a 40 μm thick ethylene/vinyl alcohol copolymer intermediate layer, and a 380 μm inner polypropylene layer by plug-assisted vacuum forming. and has an internal volume of 75 cc and a flange portion 2a.
The outer diameter is 70 m, the inner diameter is 65 mm, and the total height is 28 mm.
It was a filler.

The lid 15 is made by forming a circular aluminum vapor-deposited film 18 with a diameter of 15 groups on the center of the outer surface of a sheet 17 made of polypropylene with a thickness of 50 μm, and then attaching an ethylene terephthalate film with a thickness of 12 μm via an adhesive (urethane type). It was made by pasting.

The thickness of the vapor deposited film 18 has an electrical resistance of 4000 (JIS C
8 out of 2316. , 3. , 5 measured by metal film resistance method)
It was determined to be the following (in this case, 250Ω). This is to enable the vapor deposited film 18 to discharge when placed in a microwave oven.

When the sealed container prepared as described above was placed in a household microwave oven (frequency: 2.45 GHz, output: 0.5 kW) and taken out after 60 seconds, the vapor deposited film 18 was perforated. There was more steam coming out, but other than that, there was no abnormality in any part of the container, and the cooked rice was heated to about 75 degrees Celsius.

Specific example 2゜Specific example 1. After filling the same container body 2 with cooked gratin, leaving a head space 4 with a height h5m,
A lid 35 of the type shown in FIGS. 4 and 5 is attached to the flank portion 2a.
A sealed container was prepared by heat sealing.

The lid 35 was manufactured by hot-pressing a ring 38 to a lid body 36 made of polypropylene with a thickness of 150 μm and having an outer diameter of 71 m. The ring 38 is made of aluminum with a thickness of 50 μm, an inner diameter of 50 m, and a width of the narrow part 38 of 0.5 rm.
, the circumference was 26 circles, and the width of the other parts was 5 square meters.

When the sealed container produced as described above was placed in the same microwave oven as in Example 1 and taken out after 60 seconds, a hole was found in the narrow part 38a, but there was no abnormality in any other part of the container. The temperature of the gratin content is about 70℃.
It was heated to ℃.

(Effects of the Invention) The sealed container of the present invention stores contents containing water, and even when the contents are heated in a microwave oven or the like, that is, reheated by applying a high-frequency electric field, the container will be damaged by the internal pressure of water vapor. This has the effect that there is no risk of rupture.

[Brief Description of the Drawings] Fig. 1 is a plan view of a sealed container according to a first embodiment of the present invention, Fig. 2 is a longitudinal sectional view taken along line U-U in Fig. 1, and Fig. 3 is a main FIG. 4 is a longitudinal sectional view of a lid used in a sealed container that is a second embodiment of the invention, FIG. 4 is a plan view of a lid used in a sealed container that is a third embodiment of the invention, and FIG. FIG. 6 is a plan view of a lid used in a sealed container according to a fourth embodiment of the present invention, FIG. 7 is a longitudinal cross-sectional view of FIG. 6, and FIG. Plan view of the sealed container which is Example 5, No. 9
The figure is a longitudinal sectional view of FIG. 8. l... Sealed container, 5, 15, 35, 45, 5.5...
・Lid, 6, 16, 36, 46.56... Lid body, 7・
...Printed film, 18... Vapor deposited film, 38... Narrow width part, 4
8b... Conductive resin part, 58a... Narrow width part. Figure 1 Figure 2 Figure 3 Figure 5 Figure 5 Name Sealed Container 3 Relationship with the case of the person making the amendment Patent Applicant Address 4439-2 Kamariya-cho, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture
6 Name Kishimoto 4th generation Masato 248 Address 2-14-13 Nishi-Kamakura, Kamakura City, Kanagawa Prefecture Telephone 0467
-31-6092 6 "Detailed Description of the Invention" column 7 of the specification to be amended Contents of the amendment (1) In the 7th page, line 10 of the specification, replace the text "1 Figure 7" with 1" 4ryJ ”. (Refer to page 12, line 4 of the same page for ``1 Heat reform'').
Correct to ``Heating''.

Claims (1)

[Claims] (1) In a hermetically sealed container whose lid body is primarily made of thermoplastic plastic, the lid body is locally provided with a layer that heats up more rapidly than the plastic in a high-frequency electric field. A sealed container characterized in that when the sealed container is placed in the high-frequency electric field, a portion of the lid body to which the layer is attached or the layer melts, forming a perforation.