JPH03240674A - Bag for packaging and manufacture thereof - Google Patents

Abstract

PURPOSE:To give an automatic pressure control function automatically relieving pressure when the inside of a bag reaches specified internal pressure by interposing a thin-film between sealant layers and making the seal strength of the thin-film interposing section relatively smaller than that of a thin-film non-interposing section in one part of the bag. CONSTITUTION:All of both side edges and bottom edges of surface and rear sheets 2, 2 are heat-sealed and heat seal sections 3 are formed in a bag 1. The sheets 2, 2 are composed of the laminates of base materials 2b and sealant layers 2a, and the inner surface sides are formed in the sealant layers 2a. A thin-film 4 is shaped in the cross direction at approximately the central position of the bag 1 under the state in which it is interposed between the sheets 2, 2. According to the constitution, the seal strength of thin-film interposing sections 3b is made relatively smaller than that of thin-film non-interposing sections 3a in the heat seal sections 3. Steam is generated by heating during cooking and internal pressure is increased gradually in a package in which the bag 1 is filled with food, but the seals of the thin-film interposing sections 3b are broken and internal pressure is made to escape when internal pressure reaches certain pressure, thus completely removing possibility in which the package is burst and contents are scatterred during cooling.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a packaging bag that can automatically release the pressure inside the bag when the inside of the bag reaches a predetermined internal pressure. The present invention also relates to a method of manufacturing such a packaging bag.

Conventional technology When a pouch package containing frozen foods, etc. is placed in a heating device such as a microwave oven for cooking, the generated water vapor creates overpressure inside the bag, which eventually causes the bag to burst.
The contents may splatter inside a heating device such as a microwave oven. Such a rupture not only causes loss of food, contamination of the Z-heater, and shortened lifespan of the heater, but also poses a danger to surrounding people.

In order to prevent the contents from scattering due to the package rupturing, it is conceivable to make the heat seal strength of the package lower than the normal strength.

It is also effective to scratch the package with scissors or a cutter before cooking with a heater such as a microwave oven.

Problem to be Solved by the Invention However, setting the heat-sealing strength of the package to a predetermined low sealing strength is difficult to ensure perfection in terms of manufacturing control, considering that packages are produced in huge quantities. In addition, the number of man-hours required for inspection and the loss of packages due to inspection become large. Also,
Making the heat sealing strength of the package lower than the normal sealing strength cannot be immediately adopted because there is a risk that the sealing of the contents during the distribution process will be impaired.

Before cooking with a heating device such as a microwave oven, the person cooking the package should not damage the package with scissors or a cutter (in consideration of distribution, the package cannot be damaged at the manufacturing stage). Considering that this is a general customer base with no special knowledge, this is still unreasonable. This is because cooks do not always read the instruction manual and sometimes forget to read it.

In view of this situation, an object of the present invention is to provide a packaging bag that can automatically release pressure when the inside of the bag reaches a predetermined internal pressure, that is, a packaging bag that has an automatic pressure adjustment function. This is what was done.

Means for Solving the Problems The packaging bag of the present invention includes a sealant layer (2a), (2a
) A bag (1) made by heat-sealing at least one sheet (2) having two sealant layers (2a) and (2a) facing each other, the bag (1) comprising:
A part of the heat sealing part (3) of the bag (1) is thin between the sealant layers (2a) and (2a)! ! (formed with 0 interposed, and the thin film interposed part (3b)
The sealing strength of the thin film non-intervening portion (3a) is relatively smaller than that of the thin film non-intervening portion (3a).

In addition, the method for manufacturing a packaging bag of the present invention also includes a sealant layer (2
a), (2a) is arranged and run so that both the sealant layers (2a), (2a) face each other, and both of the facing sealant layers (2a) are run. A tape-shaped long thin film (4) is interposed between 2a) and (2a) in the same direction as the running direction of the sheet (2), and these long sheets (2) and the long thin film ( While the sheet (4) is running, heat sealing is performed in the width direction of the sheet (2) or in the width direction and the traveling direction, so that the sealing strength of the thin film intervening part (3b) of the heat sealing part (3) is equal to the sealing strength of the thin film non-intervening part (3a). ) is characterized in that the sealing strength is relatively smaller than that of the bag (1).

The present invention will be explained in detail below.

The packaging bag of the present invention, like the conventional packaging bag, has at least one sheet (2) having sealant layers (2a), (2a), both sealant layers (2a), (2a) facing each other. It consists of a bag (1) made by arranging the bags in the following manner and heat-sealing them.

The sealant layer (2a) is made of polyolefin (polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer,
Various resins having heat-sealing properties include acrylic ester copolymers, ionomers, ethylene-propylene copolymers, polypropylene, etc.), polyesters, and acrylic copolymers.

The sheet (2) may be formed of only the sealant layer (2a), but from the viewpoint of strength, heat resistance, and storage stability of the contents, the sealant layer (2a) is laminated on the base layer (2b). There are many things to do.

Here, examples of the base material layer (2b) include single-layer or multi-layer plastic sheets, metal foils, metal foil laminated plastic sheets, nonwoven fabrics, nonwoven fabric laminated plastic sheets, metal vapor-deposited plastic sheets, and the like.

The sealant layer (2a) can be laminated onto the base material M (2b) by methods such as coextrusion, coating, extrusion coating, and dry lamination. The sealant layer (2a) can also be partially provided on the base layer (2b). The bag (1) is formed by folding back one sheet (2) having the sealant layer (2d). 2a).

(2a) facing each other, or by arranging two sheets (2) having sealant layers (2a) so that their respective sealant layers (2a) face each other, and then heat sealing. Sealant! In the case of the sheet (2) made of an inflation tube having the shape (2a), the bag (1) can be formed by simply heat-sealing it in the width direction.

Now, in the present invention, a part of the heat-sealed part (3) formed by heat-sealing is formed by the sealant layer (2).
a) and (2a) with a thin #l (0) interposed between them, and the seal strength of the SS intervening part (3b) is relatively higher than the seal strength of the thin film non-intervening part (3a). In other words, thin W5! (4)
By performing heat sealing with the thin film intervening portion (3b) interposed, the sealing strength of the thin film intervening portion (3b) is made smaller than that of the other portions.

Such a thin H (4) has the following properties: ■ Although it has heat sealability, the heat sealing temperature is originally higher than that of the sealant layer (2a), and the sealant layer (2a) and (2a) can be heated at a temperature suitable for each other. Depending on the sealing operation, the sealant layer (2a), (2a)
Sealant layer (2a)/thin film (4)
), such as a resin film with a higher melting point than the resin constituting the sealant layer (2a),
Sealant) M (2a) Resin films that are blended with resins that have a higher melting point than M (2a), etc. ■ Sealant Layer (2a)/Thin I! (4) A thin film whose sealing strength between the sealant layers (2a) and (2a) is originally lower than the sealing strength between the sealant layers (2a), for example, a resin film in which a substance having a function of reducing heat sealing strength is added to a resin having heat sealing properties. , a resin film made by coating or impregnating a resin sheet with heat-sealing properties with a substance that reduces the heat-sealing strength, etc.; ■ Consisting of two layers of laminate film, one side of which has a high sealing strength with the sealant layer (2a);
The sealing strength between the other side and the sealant layer (2a) is low, and the sealant layer (2a) can be sealed between the latter side and the sealant layer (2a) by heat sealing at a temperature suitable for the sealant layer (2a). The sealing strength is the sealant layer (2a).

(2a) A thin film whose seal strength is smaller than the seal strength between the two.

Now, when the seal strength of the thin film intervening part (3b) is Tb and the seal strength of the thin film non-intervening part (3a) is Ta, T b/
T a = 0.02 to 0.8 (preferably 0.05 to
The sealant layer (2a) and the thin film (4) are selected so as to satisfy the relationship of
2a) It is desirable to set temperature conditions suitable for both.

For household and commercial microwave oven food, the absolute value of the seal strength is Ta 1 to 10 kg/15
m5 or more, especially 2.5 to 5 kg/1
The thickness is about 5 mm, and the Tb is about 0.3 to 1.5 kg/15 m (however, Tb≦0.8 Ta).

By optimally setting the sealing strength of the part without a thin film (3a) and the part with a thin film (3b), and by appropriately selecting the ratio of the part without a thin film (3a) and the part with a thin film (3b), it is possible to achieve the desired goal. Customized product packaging can be designed.

It is also possible to provide each bag (1) with a plurality of thin film intervening parts (3b), (3b) having different sealing strengths so that the seal with the lowest sealing strength is torn first.

The above-mentioned packaging bag can be manufactured by various methods, but industrially it is desirable to manufacture it as follows.

First, at least one elongated sheet (2) having the sheet tent layers (2a) and (2a) is coated with both sealant layers (
In order for the two sealant layers (2a), (2a) to face each other, two sealant layers (2), (2) must be placed so that they face each other. They may be stacked, one sheet (2) may be folded in half, the body overlapped, or the body clasped together, or an inflation tube may be used.

At the same time as the sheet (2) runs, the facing sealant layer (
2a) and (2a), a tape-like long thin film (0 is interposed in the same direction as the running direction of the sheet (2). Thin II (4) may be one strip or multiple strips. There may be.

These long sheets (2) and long thin films 1
While the sheet (4) is running, heat sealing is performed in the width direction of the sheet (2) or in the width direction and the traveling direction.In addition to the case where this heat sealing is performed before filling the bag (1) with contents,
Recently, bag making and filling machines have become popular, so the filling may be performed at the same time as or after filling the bag (1) with the contents.

The bag (1) is obtained by heat sealing, but at this time, the sealing strength of the thin film intervening part (3b) of the heat sealing part (3) is made to be relatively smaller than the sealing strength of the thin film non-intervening part (3a). conditions (sealant layer (2a) and thin film (4)
) and set the heat seal temperature). Furthermore, the area and position of the thin film intervening portion (3b) are also set to be optimal.

Functions and Effects of the Invention In the packaging bag of the present invention, a thin film (4) is interposed in a part of the heat-sealed part (3) of the bag (1), and the seal of the thin film-interposed part (3b) is Strength is in the part without thin film (3a)
The seal strength is relatively smaller than that of

In this case, the sealing strength of the *S intervening part (3b) is set within an allowable range, so that the sealing performance of the package filled with contents such as food in the bag (1) may be impaired during the distribution process. No situation arises.

The package in which the bag (1) is filled with food can be put into a heating device such as a microwave oven as it is for cooking.

During cooking, steam is generated due to heating and the internal pressure increases, but when a certain pressure is reached, the seal of the thin film intervening part (3b) is broken and the internal pressure is released, so the package may burst during cooking. The risk of the contents scattering is completely eliminated.

Example Next, the present invention will be further explained with reference to Examples.

Example 1 Figure 1 is a front view showing an example of the packaging bag of the present invention, Figure 2 is a front view showing an example of the packaging bag of the present invention.
The figure is a sectional view taken along line AA, and FIG. 3 is a sectional view taken along line BB. FIG. 4 is a partial plan view showing an example of bag making. Note that in FIGS. 2 and 3, the thickness is exaggerated.

In Figures 1 to 3, (1) has a height of 250 mm and a width of 15 mm.
The bag has a width of 10 mm, and both side edges and the bottom edge of the front and back sheets (2) and (2) are heat-sealed to a width of 10 mm to form a heat-sealed portion (3).

Sheets (2), (2) are made of a laminate of a base material (2b) and a sealant layer (2a), and the inner surface (food contact side)
is the sealant layer (2a). In this example, 1 liter of base material (32 mm thick) consisting of a dry laminated film of a biaxially oriented polyethylene terephthalate film and an ethylene-vinyl alcohol copolymer film is used.
A sealant layer (2a) is formed by coating the ethylene-vinyl alcohol copolymer film side of 2b) with low-density polyethylene to a thickness of 401L.
These are used as sheets (2) and (2).

(4) is a thin film with a width of 60 cm, and in this example, a propylene-ethylene copolymer film with a thickness of 20 μLWA and a melting point of 140° C. is used. This thin film (4) is interposed between the bag (1) and (2).
) is provided in the width direction at approximately the center position.

The heat-sealed part (3) consists of a thin film intervening part (3b) and a thin film non-intervening part (3a), and in a peel test using a peel tester, the seal strength Ta of the thin film intervening part (3b) was 0.
7 kg/15 mm, and the non-seal strength Tb of the thin film non-intervening part (3a) was 3.5 kg/15 mm. Tb/Ta is 0
．． It becomes 2.

In Figure 4, there are two running long sheets (2
), overlapping long sheets (2) with one tape-like long thin film (4) running at 1/4 of each edge from each edge. 2), (
Both edges of 2) are heat-sealed to form a long sheet (2),
(2) Heat sealing is also performed at regular intervals in the width direction. In the heat seal part (3) formed by these heat seals, a long sheet (2),
(2) Sealant layer (2a).

(2d) are fused together, but sheets (2) and (
Since the heat seal in the width direction of 2) crosses the above-mentioned thin film (4), only this part is covered with the sealant layer (2a),
(2a) is fused with thin #(4) interposed therebetween.

In Fig. 4, the dashed dot line at the center of the sheet (2), (2) in the running direction and the dashed dot line at the center of the heat sealed part (3) in the width direction are both cutting lines, and after the heat sealing is completed, these lines are cut. When cut along the dashed line, the packaging bag shown in FIGS. 1 to 3 is obtained.

The above bag (1) was filled with two frozen pork buns each weighing about 90 g, and the openings were heat-sealed to produce a large number of packages.

This package was directly placed in a microwave oven for cooking. The package started to swell as the heating time passed, but 1-
After 1.5 minutes had elapsed, the seal of the thin film intervening portion (3b) was broken, and the water vapor inside the package was released. After the cooking was completed, the package was observed, but no abnormality was observed in the seal of the thin film-free area (3a).

Example 2 FIG. 5 is a front view showing another example of the packaging bag of the present invention.

In Example 1, thin M (4) is sheet (2), (
In this embodiment, a thin M (0 is placed on the bottom side of the bag (1) with a width of 1.30) is provided in the width direction at approximately the center of the bag (1) with The other details are the same as in the first embodiment.

! It! If (4) is provided on the bottom side of bag (1) like this, it will be thinner! The presence of (4) is almost completely inconspicuous, making it more desirable in terms of commercial value.

Additionally, it is advantageous that the seal at the bottom of the bag (1) breaks when the water vapor escapes, making it easier to open to remove the contents after cooking.

Embodiment 3 FIG. 6 is a rear view showing an example of a packaging body in which an object to be packaged is housed in a packaging bag of the present invention.

The bag (1) in Figure 6 is made by folding both sides of one sheet (2) so that the sealant layer (2a) is on the inside.
Packaging is performed at the same time as bag making by wrapping the tray with holes for food (5) and folding the vq edges of the sheet (2) together on the lower side, heat sealing the folded palms, and then heat sealing in the width direction. It is.

(4) is a thin film along the inside of the sheet (2),
A first thin film (with a melting point higher than that of the sealant layer (2a))
4a) and a second thin film (4b), the first thin film (4a
) and the second thin II! In comparison with (4b), the latter (4b)
has a higher melting point.

When this package is placed in a microwave oven for cooking, first the thin film interposed part (3b) with the second thin film (4b) interposed
) will break and the water vapor inside the package will escape.

The heating is rapid and the thin film intervening part (with the second thin film (4b) interposed)
If the generated water vapor cannot escape sufficiently due to the breakage of the seal in step 3b), the seal in the thin film intervening part (3b) with the first thin film (4a) in between will be broken, so even in the unlikely event that the packaging There is no risk of the body bursting and the contents scattering.

Example 4 Example 4 except that a polypropylene film with a relatively low melting point was used as the sheet (2) and (2), and a laminate film of this polypropylene and a propylene-ethylene copolymer film was used as the thin film (4). A bag (1) was produced in the same manner as in Example 2.

The packaging bag thus obtained was also preferable as in Example 2.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of the packaging bag of the present invention;
The figure is a sectional view taken along line AA, and FIG. 3 is a sectional view taken along line BB. FIG. 4 is a partial plan view showing an example of bag making. Note that in FIGS. 2 and 3, the thickness is exaggerated. FIG. 5 is a front view showing another example of the packaging bag of the present invention. FIG. 6 is a rear view showing an example of a package in which an object to be packaged is housed in a packaging bag of the present invention. (1)...Bag, (2)...Sheet, (2a)...
Sealant layer, (2b)...Base material layer, (3)...Heat seal portion, (3a)...Thin film non-intervening portion, (3b)
...Thin film intervening part, (0...Thin film. (4a)...111th film, (4b)...Second thin film, (5)...Food holding tray

Claims (1)

[Claims] 1. At least one sheet (2) having sealant layers (2a), (2a), both sealant layers (2a), (2a).
A bag (1) made by heat-sealing the layers a) facing each other, a part of the heat-sealed portion (3) of the bag (1) having the sealant layer (2a), (
2a) are formed with a thin film (4) interposed therebetween, and the sealing strength of the thin film intervening part (3b) is relatively smaller than the sealing strength of the thin film non-intervening part (3a). A packaging bag. 2. At least one elongated sheet (2) having sealant layers (2a), (2a), both sealant layers (2a)
), (2a) are arranged and run so as to face each other, and a tape-shaped long thin film (4) is placed between the opposing sealant layers (2a), (2a) in the running direction of the sheet (2). While these long sheet (2) and long thin film (4) are running, the sheet (
Heat sealing is performed in the width direction or the width direction and the traveling direction of 2), and the sealing strength of the thin film intervening part (3b) of the heat sealing part (3) is relatively higher than the sealing strength of the thin film non-intervening part (3a). A method for manufacturing a packaging bag, which is characterized in that it is made smaller to form a bag (1).