JPH1059433A - Packaging bag having automatic pressure adjusting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow pressure to escape reliably and automatically from a specific part of a bag when inside the bag reaches a predetermined internal pressure. SOLUTION: A bag 1 is prepared with sealant layers 21, 21 of sheets 2, 2 placed oppositely and heat-sealed. A part of a heat-sealed part 3 of the bag 1 is formed on a thin film interposed sealed part 32 with a thin film 4 interposed between the sealant layers 21, 21 of the sheets 2, while sealing strength of the sealed part 32 is made to be smaller than that of a sealed part 31 without a thin film interposed. Further a part of the sealed part 32 is formed on a narrow sealed part 32a having a smaller heat-sealed width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging bag capable of automatically releasing the pressure in a bag when the inside of the bag reaches a predetermined internal pressure during cooking, that is, a packaging bag having an automatic pressure regulation function. It is about bags.

[0002]

2. Description of the Related Art When a pouch package containing frozen foods and the like is put into a heater such as a microwave oven and cooked, the inside of the bag is over-pressurized due to generated steam, and the bag eventually bursts. Therefore, the contents may be scattered in a heater such as a microwave oven. Such a rupture not only results in food loss, fouling of the heater, shortening the life of the heater, but also endangers the surrounding people.

Therefore, it is effective to damage the package with scissors or a cutter before cooking with a heater such as a microwave oven.

In order to prevent the contents from being scattered due to the rupture of the package, it is conceivable to devise the structure of the packaging bag itself, for example, to make the heat seal strength of the package smaller than normal strength.

[0005] Further, Japanese Patent Application Laid-Open No. 3-2 filed by the present applicant.
Japanese Patent No. 40674 discloses a bag manufactured by arranging at least one sheet having a sealant layer so that both sealant layers face each other and heat-sealing the sheet.
A part of the heat seal portion of the bag is formed with a thin film interposed between the sealant layers, and the seal strength of the thin film interposed portion is relatively smaller than the seal strength of the non-thin film interposed portion. A packaging bag having the following structure is shown.

[0006]

Prior to cooking with a heater such as a microwave oven, a method of scratching the package with scissors or a cutter (it is impossible to damage the package at the manufacturing stage in consideration of distribution) This shifts responsibility to the general consumer who actually cooks the package. In addition, not all general consumers without special knowledge always read the instruction manual and sometimes forget it.

[0007] Among the above prior arts, setting the heat seal strength of the package to a predetermined weak seal strength is not perfect in terms of manufacturing control, considering that the package is produced in an enormous amount. Inspection man-hours and loss of the package consumed for the inspection also become enormous. Further, if the heat sealing strength of the package is made lower than the normal sealing strength, the sealing of the contents in the distribution process may be impaired, so that it cannot be adopted immediately.

The method described in Japanese Patent Application Laid-Open No. Hei 3-240675 in which a thin film is interposed to reduce the heat seal strength at that portion aims at solving the conventional problems.
However, (i) in a commercial microwave oven with a rated high-frequency output of 1600 W, there is a situation that the internal pressure rises rapidly
(ii) When the contents contain a large amount of water, there is a situation that unless the bag is made large, the internal pressure is suddenly increased and the bag is easily broken. Therefore, in cases (1) and (ii), even in the case of the packaging bag of this publication, it is unknown where in the thin-film intervening part the bag breaks, and the bag from the thin-film intervening part is all at once. Easy to happen. Therefore, in consideration of the safety when the user uses it, it is desirable to further improve the packaging bag of this publication.

Against this background, the present invention further develops the technology of Japanese Patent Application Laid-Open No. HEI 3-240675 filed by the present applicant, and when the inside of the bag reaches a predetermined internal pressure, the bag is specified. An object of the present invention is to provide a safe packaging bag (a packaging bag having an automatic pressure regulation function) that can reliably and automatically release pressure from a site.

[0010]

According to the present invention, there is provided a packaging bag having an automatic pressure control function, comprising: at least one sheet (2) having sealant layers (21), (21); (twenty one)
Are placed so as to face each other and heat-sealed to form a bag (1).
Part of (3), a thin film between the sealant layer (21), (21)
(4) is formed in the thin-film interposed seal portion (32) with the interposed portion, and the seal strength of the thin-film interposed seal portion (32) is made smaller than the seal strength of the non-thin-film interposed seal portion (31). Further, a part of the thin film interposed seal portion (32) is formed in a narrow seal portion (32a) having a narrow heat seal width,
It is characterized by the following.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0012] The packaging bag of the present invention comprises, as in a conventional packaging bag, at least one sheet (2) having sealant layers (21), (21), and both sealant layers (21), (21). Bags made by placing them so that they face each other and heat sealing
(1)

As the sealant layer (21), polyolefin (polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ionomer,
Ethylene-propylene copolymer, polypropylene, etc.),
Examples include layers of various resins having heat sealing properties, such as polyester and acrylic copolymers.

The sheet (2) may be formed of only the sealant layer (21). However, from the viewpoint of strength, heat resistance and storage stability of the contents, the sheet (2) may be formed on the base material layer (22). ) Are usually laminated.

The base layer (22) is exemplified by a single-layer or multi-layer plastic sheet, metal foil, metal foil-laminated plastic sheet, non-woven fabric, non-woven laminate plastic sheet, metal-deposited plastic sheet and the like. Is done.

The lamination of the sealant layer (21) on the base material layer (22) can be achieved by a method such as coextrusion, coating, extrusion coating, and dry lamination. The sealant layer (21) may be provided partially on the base material layer (22).

The bag (1) is formed, for example, by a sealant layer
One sheet (2) having (21) is folded back so that the sealant layers (21) and (21) are opposed to each other, or two sheets (2) having the sealant layer (21) are attached to each sealant layer. (2
This is done by arranging 1) to face each other and then heat sealing.

According to the present invention, a part of the heat seal portion (3) formed by heat sealing is replaced with a thin film interposed seal having a thin film (4) interposed between the sealant layers (21) and (21). The seal strength of the thin-film interposed seal portion (32) is made smaller than the seal strength of the thin-film non-intervened seal portion (31). That is, by performing heat sealing with the thin film (4) interposed therebetween, the sealing strength of the thin film interposed seal portion (32) is made smaller than that of the other portions.

Examples of such a thin film (4) include the following. Although it has heat sealability, it is inherently a sealant layer
Heat seal temperature is higher than (21) and the sealant layer (2
Depending on the heat sealing operation at a temperature suitable for 1) and (21), the seal strength between the sealant layer (21) and the thin film (4) is smaller than the seal strength between the sealant layers (21) and (21). Thin film. For example, a resin film having a higher melting point than the resin constituting the sealant layer (21), a resin film obtained by blending a resin having a higher melting point than the resin constituting the sealant layer (21), and the like. Although heat sealing can be performed by heat sealing at a temperature suitable for the sealant layers (21) and (21), the seal strength between the sealant layer (21) and the thin film (4) is low.
A thin film that is inherently smaller than the seal strength between 1) and (21). For example, a resin film obtained by adding a substance having a heat sealing strength reducing function to a resin having a heat sealing property, a resin film having a heat sealing resin sheet coated or impregnated with a substance having a heat sealing strength reducing function, and the like. Composed of two layers of laminated film, one side has high sealing strength with sealant layer (21), the other side has sealant layer
(21), and the sealant layer (21), (2
1) By performing a heat sealing operation at a temperature suitable for each other, the seal strength between the latter surface and the sealant layer (21) is made smaller than the seal strength between the sealant layers (21) and (21). Thin film.

Assuming that the seal strength of the thin-film interposed seal portion (32) is T ₂ and the seal strength of the non-thin-film interposed seal portion (31) is T ₁ , T ₂ / T ₁ = 0.02 to 0.8 (preferably 0.05 0.5 and, especially, 0.07 to 0.25), the sealant layer (21) and the thin film (4) are selected, and the heat sealing condition is set to a temperature suitable for the sealant layers (21) and (21). It is desirable to set conditions.

In a packaging bag for food for microwave cooking for home use or business use, the absolute value of the seal strength is T _1.
Is about 1-10kg / 15mm or more, especially 2.5 ~
5kg / 15mm about, T ₂ is about 0.3~1.5kg / 15mm.
However, care should be taken to satisfy the relationship 0.02 ≦ T ₂ / T ₁ ≦ 0.8.

The seal strength between the non-membrane seal portion (31) and the thin film seal portion (32) is optimally set, and the area ratio between the non-thin film seal portion (31) and the thin film seal portion (32) is reduced. By appropriate selection, a product package suitable for the purpose can be designed.

Although the above-mentioned packaging bag can be produced by various methods, it is desirable from an industrial viewpoint to produce it as follows.

First, at least one long sheet (2) having sealant layers (21), (21) is
1) and (21) are placed facing each other and run. In order for both sealant layers (21), (21) to face each other,
Overlap one sheet (2), (2) or one sheet
For (2), fold in two, or superimpose or fuselage.

Simultaneously with the running of the sheet (2), a tape-like long thin film (4) is placed between the opposing sealant layers (21) and (21) so as to be in the same direction as the running direction of the sheet (2). Intervene.
The number of the thin film (4) may be one or plural.

While the long sheet (2) and the long thin film (4) are running, heat sealing is performed in the width direction of the sheet (2) or in the width direction and the traveling direction. This heat sealing is performed before filling the contents of the bag (1), and since the bag making and filling machine has recently become widespread, the heat sealing is performed simultaneously with or after filling the contents of the bag (1). May go.

The bag (1) is obtained by the above heat sealing. At this time, the thin film interposed sealing portion (3) of the heat sealing portion (3) is obtained.
Conditions (2) such that the seal strength of the sealant layer (21) and the thin film
(4), heat seal temperature).

The thin-film sealing portion (32) may be formed on either the bottom side of the bag (1) or the side of the bag (1).
It is preferable to form it on the bottom side of (1). By doing so, the presence of the thin film (4) is inconspicuous, which is advantageous in terms of commercial value.In addition, the seal at the bottom of the bag (1) breaks when water vapor is released, so when removing the contents after cooking This makes it easier to open the package.

It is also possible to form the bottom side of the bag (1) in a W-shaped gusset folded inward, and to form a thin film sealing portion (32) on one bottom side of the W-shape. In this case, if the mixture is heated in a microwave oven with the thin film interposed seal portion (32) formed side up, the juice does not spill even after cooking.

In the present invention, a part of the thin film interposed seal portion (32) is formed in a narrow seal portion (32a) having a narrow heat seal width. The point of the present invention is that such a device is added together with the formation of the thin film interposed seal portion (32).

Thin film interposed seal part (32) and narrow seal part
The shape of (32a) can be set variously. An example of a preferred shape is that a part of the boundary line of the thin film interposed seal portion (32) near the bag central region protrudes toward the bag central region, and the outside of the bag is located in a region closer to the bag periphery than the overhanging line (32b). By forming a non-seal part (32c) communicating with the
The area between the overhanging line (32b) and the non-sealing portion (32c) is formed in the narrow sealing portion (32a).

<Function> In the packaging bag of the present invention, the bag
A thin film (4) is interposed in a part of the heat seal portion (3) of (1), and the seal strength of the thin film interposed seal portion (32) is smaller than that of the non-thin film seal portion (31). It is.
In addition, a part of the thin film interposed seal portion (32) is formed into a narrow seal portion (32a) having a narrow heat seal width.

The package in which the bag (1) is filled with food can be put into a heater such as a microwave oven for cooking as it is (without cutting or partially opening). During cooking, steam is generated by heating and the internal pressure rises, but when a certain pressure is reached, the seal of the narrow seal portion (32a) of the thin film interposed seal portion (31) is broken and the internal pressure increases. Is escaped, so that the possibility of the package exploding during cooking and the contents being splattered is completely eliminated. When the cooking temperature is high or the heating rate is sudden and the internal pressure rises unexpectedly, first the bag is broken at the narrow seal (32a),
In accordance with the height of the internal pressure, the rupture point only spreads around the narrow seal portion (32a) of the thin film interposed seal portion (31) (see FIGS. 3 and 4 described later). In this manner, the breakage point is specified, and the breakage point expands in accordance with the level of the internal pressure, so that the user has high reliability in cooking safety. Therefore, when the content is a food for microwave cooking containing a large amount of water, when the bag volume is relatively small, or when heating with a commercial microwave oven having a large output, There is no trouble.

Since the sealing strength of the thin film interposed seal portion (32) is set within an allowable range, the sealing performance of the package in which the contents such as food are filled in the bag (1) is impaired in the distribution process. Such a situation does not occur.

[0035]

The present invention will be further described with reference to the following examples.

Example 1 FIG. 1 is a front view showing an example of a packaging bag according to the present invention.
FIG. 2 is an AA cut end view of the packaging bag of FIG. However, the layer thickness is exaggerated. FIG. 3 is an explanatory view when the packaging bag of FIG. 1 is broken small. FIG. 4 is an explanatory diagram when the packaging bag of FIG. 1 is greatly broken.

In FIG. 1, (1) shows a height of 287 mm and a width of 1
A 50 mm bag, both sides of the front and back sheets (2) and (2) are heat-sealed to a width of 10 mm, the bottom edge is heat-sealed as described later, and heat-sealed portions (3) are formed on three sides. Have been.

The front and back sheets (2) and (2) are both
It consists of a laminate of (22) and a sealant layer (21), and the inner side (food contact side) is a sealant layer (21). In Example 1, the thickness of a dry laminate film of a biaxially stretched polyethylene terephthalate film and an ethylene-vinyl alcohol copolymer film was 55 mm.
a thickness of 40 μm, commonly called CPP, on the surface of the base material layer (22) having a thickness of
The propylene-ethylene copolymer film was dry-laminated into a sealant layer (21) to form a sheet (2),
Used as (2).

(4) is a thin film having a width of 18 mm. In Example 1, an ethylene-vinyl acetate copolymer film having a thickness of 20 μm and a melting point of 90 ° C. is used. The thin film (4) is provided in the width direction on the bottom side along the bottom of the bag (1) in a state interposed between the sheets (2) and (2).

The heat seal portion (3) has a seal portion formed on both side edges to have a width of 10 mm, and a thin film non-intervening seal portion (31)
The seal formed on the bottom edge is a thin film interposed seal (3
2). The peeling test with peel tester, seal strength T ₁ of the seal strength T ₂ of the thin film interposed sealing portion (32) is 0.7 kg / 15 mm, a thin film non-intervening seal portion (31) at 3.5kg / 15mm, T ₂ / T
₁ was 0.2.

The above-mentioned thin film interposed seal portion (32) is formed as shown in FIG. That is, the portions of the thin film interposed seal portion (32) except for both ends of the boundary line near the bag central region project in a wavy line toward the bag central region, and the projecting line (32
By forming a semi-ring-shaped non-seal portion (32c) communicating with the outside of the bag in the region closer to the bag bottom side than b), the region between the overhanging line (32b) and the non-seal portion (32c) is heated. It is formed in a narrow seal portion (32a) having a narrow seal width. In addition,
The semicircular portion surrounded by the semi-ring-shaped non-seal portion (32c) is a seal portion.

The bag (1) was filled with food, and the opening was heat-sealed to produce a number of packages. When this package was placed in a microwave oven and cooked as it was, the package began to swell with the elapse of the heating time, but after 1 to 5 minutes, the thin seal portion (32) of the thin film interposed seal portion (32) Three
The seal at the portion 2a) was broken as shown in FIG. 3 or FIG. 4, and the water vapor inside the package was released. After completion of cooking, the package was observed, but no abnormality was found in the seal of the thin film non-intervening seal portion (31).

Embodiment 2 FIG. 5 is a perspective view showing another example of the packaging bag of the present invention. FIG. 6 is a sectional view taken along the line BB of the packaging bag of FIG.

In the second embodiment, the sheets (2), (2)
As a laminate film of a polyamide film and a propylene-ethylene copolymer film having a relatively high melting point, and as a thin film (4), polypropylene and ethylene-
A coextruded multilayer film with a vinyl acetate copolymer was used.

In the second embodiment, the bottom side of the bag (1) is formed into a W-shaped gusset, and one of the bottom sides of the W-shape (the bottom side which is to be the front surface of the bag (1)). ) Is slightly shorter than the other bottom side, a thin-film interposed seal portion (32) is formed on one of the bottom sides, and a part of the thin-film interposed seal portion (32) is narrowed similarly to the first embodiment. Seal part (32
a) is formed.

The bag (1) was filled with food, the opening was heat-sealed to prepare a package, and the package was heated in a microwave oven with the thin-film interposed seal portion (32) formed side facing up. No juice spilled after cooking.

[0047]

As described in the section of the operation, in the packaging bag of the present invention, a part of the heat sealing portion (3) of the bag (1) is partially sealed with a thin film sealing portion (3) having a small sealing strength. 32), and a part of the thin film interposed seal portion (32) is formed into a narrow seal portion (32a) having a narrow heat seal width.

For this reason, when the package in which the bag (1) is filled with food is put into a heater such as a microwave oven and used for cooking, when the internal pressure reaches a certain pressure, the thin film interposed seal portion (31) is opened. Since the seal at the narrow seal portion (32a) is broken and the internal pressure is released, the possibility that the package ruptures during cooking and the contents are scattered is completely eliminated. When the cooking temperature is high or the temperature rise rate is sudden and the internal pressure rises unexpectedly, first the bag is broken at the narrow seal part (32a), and the thin film interposed seal part (31) according to the high internal pressure. Narrow seal part (3
The area of the bag break is spread around 2a). In this way, the breakage point is specified and the breakage point expands according to the level of the internal pressure.
It is highly reliable in terms of safety when the user cooks.

Therefore, in the packaging bag of the present invention, when the content is a food for cooking a microwave oven containing a large amount of moisture, when the bag volume is relatively small, and when the content is a business-use microwave oven having a large output, heating is performed. Even if it does, no trouble occurs during cooking.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a packaging bag of the present invention.

FIG. 2 is an AA cut end view of the packaging bag of FIG. 1;

FIG. 3 is an explanatory view when the packaging bag of FIG. 1 is broken small.

FIG. 4 is an explanatory view when the packaging bag of FIG. 1 is greatly broken.

FIG. 5 is a perspective view showing another example of the packaging bag of the present invention.

FIG. 6 is a sectional view taken along the line BB of the packaging bag of FIG. 5;

[Explanation of symbols]

(1) ... bag, (2) ... sheet, (21) ... sealant layer, (22) ...
Base material layer, (3) ... heat seal part, (31) ... thin film non-intervening seal part, (32) ... thin film intervening seal part, (32a) ... narrow seal part, (32b) ... overhang line, (32c) … Non-seal part, (4)…
Thin film

Claims (5)

[Claims] A bag is formed by arranging at least one sheet (2) having sealant layers (21) and (21) such that both sealant layers (21) and (21) face each other and heat-sealing the sheets. In the bag (1), a part of the heat seal portion (3) of the bag (1) is replaced with a thin film interposed seal portion (a thin film (4) interposed between the sealant layers (21) and (21)). 32) and its thin film interposed seal
The seal strength of the thin film non-intervening seal portion (31) is made smaller than the seal strength of the thin film non-intervening seal portion (31). (32a) A packaging bag having an automatic pressure regulation function, characterized in that: 2. The packaging bag according to claim 1, wherein the thin film interposed seal portion (32) is formed on the bottom side of the bag (1). 3. A part of the boundary line of the thin film interposed seal portion (32) near the bag central region projects toward the bag central region, and extends outside the bag in a region closer to the bag periphery than the overhanging line (32b). A region between the overhanging line (32b) and the non-seal portion (32c) is formed in the narrow seal portion (32a) by forming a non-seal portion (32c) that communicates. Item 7. The packaging bag according to Item 1. 4. The bag (1) has a bottom side formed in a W-shaped gusset folded inward, and a thin-film sealing portion (32) is formed on one bottom side of the W-shape. Part of the seal part (32) is a narrow seal part with a narrow heat seal width
The packaging bag according to claim 1, wherein the packaging bag is formed in (32a). 5. The packaging bag according to claim 1, which is a packaging bag for foods for microwave cooking containing a large amount of water.