JP2000203658A - Packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a packaged article in a distribution stage and, at the same time, to obviate a rupture when it is heated. SOLUTION: A surface modification treatment is applied to a proper location of a peripheral portion of a fused side surface of each of films 11, 12, in pairs, constituting a packaging bag 1, and the treated portions of the films 11, 12 are brought into abutting engagement to heat the entire peripheral portions thereof, thereby fusing the portions to each other. In the packaging bag 1 of such construction, an article W packaged in the bag can be protected in the distribution stage, while the packaging bag can be prevented from rupturing when the article W is cooked by heat, and hence the article W being packaged in the bag 1 can be desirably heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging bag for hermetically sealing an article to be packaged, such as food, and for heating the packaged state.

[0002]

2. Description of the Related Art In recent years, in the distribution industry of foods and the like, for example, as a part of reduction in distribution costs, cooked foods and the like are hermetically packaged in a packaging bag made of a film material such as polyethylene or polypropylene. In many cases, a distribution method of distributing the packaged food as it is to the market is adopted.

[0003] On the other hand, on the consumer side, when purchasing the above-mentioned packaged food distributed on the market, when eating the packaged food, the packaged food is kept in a sealed packaging state by the packaging bag, for example, in an electronic package. Often, a cooking method of heating by heating with a heating means such as a microwave is used.

In this case, if the packaged food is heated by a microwave oven without any modification, the packaging bag gradually expands due to steam generated from the food as the temperature of the food rises. It is feared that this will explode.

[0005] In order to prevent the rupture of the packaging bag accompanying the heating of the food packaged by such a packaging bag, various methods have conventionally been taken, for example, prior to heating the food. For example, the food is taken out of the packaging bag and the food is heated only, or an air hole is appropriately provided in the sealed packaging bag and then heated.

[0006] However, when the food or the like sealed and packaged in the packaging bag is cooked by heating, the food is taken out of the packaging bag prior to heating, or an air hole is provided in the packaging bag. According to this, although the occurrence of a situation in which the packaging bag is ruptured due to the heating and cooking can be prevented, the operation is troublesome.

[0007] From such a background, there is a demand for the development of a technology which can eliminate the trouble of taking out the food from the packaging bag or forming an air hole in the packaging bag when cooking the packaged food by heating. In response, for example,
A method has been proposed in which the sealing strength of the sealed portion of the packaging bag by heat fusion is reduced in advance, or an air hole is formed in the packaging bag in advance before putting the food into the distribution market. .

[0008]

However, according to the method in which the sealing strength of the packaging bag is reduced in advance, even if the packaging bag is heated by a microwave oven, the sealing pressure of the packaging bag is automatically increased due to an increase in the internal pressure of the packaging bag. Since the sealing part is peeled off and water vapor can be released, that is, gas can be released, it is possible to prevent the packaging bag from being ruptured, but it is necessary to secure the sealing properties required for handling products in the distribution process. There is a concern that the protective function of the food packaged by the packaging bag will be impaired as a result. In addition, according to the method of forming air holes in the packaging bag in advance in the distribution process, although the packaging bag does not burst during heating in the microwave oven, the food as a package is not distributed in the distribution process. A problem that cannot be overlooked in the distribution of food that freshness cannot be maintained due to exposure to the outside air occurs.

In view of the above, the present invention has been made to provide a packaging bag capable of both protecting a packaged object such as food in a distribution process and preventing rupture during heating. is there.

[0010]

BACKGROUND OF THE INVENTION The inventors of the present invention have studied a method for solving the problems in the conventional packaging bag as described above, and from the viewpoint of improving the adhesiveness, printability, antifogging property, etc. of the film material, Attention was paid to the surface modification treatment of the film material which has been adopted.

That is, FIG. 7 shows a surface-treated portion of a pair of film materials in which a predetermined surface wetting tension is imparted by performing a surface modification treatment such as a corona discharge treatment on the side surfaces of the film materials to be fused. A large number of samples were prepared for each surface wetting tension of the surface treatment section, and a tensile test was performed on each of these samples. The figure shows the value obtained when the load value when each sample breaks is determined as the heat seal strength (g / 15 mm width).

From the test results shown in FIG. 7, the heat seal strength between the film materials subjected to the surface modification treatment by the corona discharge treatment (a) gradually decreases as the value of the surface wetting tension of the treated surface increases. That, (b) 55dyn
/ Cm, the heat seal strength is greatly reduced, but in the region of the surface modification treatment of 55 dyn / cm or less, the heat seal strength that can sufficiently withstand the impact in the distribution process or the like is secured. , Etc. were found.

This is proved by the test results shown in FIG. That is, FIG. 8 shows the relationship between the tensile load value and the amount of elongation of the sample, which was performed at room temperature (about 20 ° C.) by performing a tensile test of the sealed portion by heat fusion of the film material. Here, the curve “La ₁ ” in FIG.
FIG. 4 is a "load-elongation diagram" in the case where a sample obtained by heating and fusing the fusion side surfaces of a film material having undergone a surface modification treatment with a surface wetting tension of 50 dyn / cm on the fusion side surface. Also, the curve “Lb ₁ ” in the figure is a “load-elongation diagram” for a sample obtained by heating and fusing the fused side surfaces of a film material whose surface is not subjected to a surface modification treatment. It is.

FIG. 8 shows that, in the sample in which the fused side surfaces of the film material whose surface was subjected to the surface modification treatment were heated and fused together, as shown by the diagram "La ₁ ", 5 kgf / kg was obtained.
It can be seen that interfacial separation occurs at about 15 mm, and after elongating and deforming to about 32 mm, the fused portion is completely separated and separated at about 4.5 kgf / 15 mm. On the contrary,
In the sample in which the fused side surfaces of the film material whose surface was not subjected to the surface modification treatment were heated and fused, the diagram “Lb
_As shown by " ₁ ", it can be seen that the film material breaks at around 5.4 kgf / 15 mm. Comparing the two curves “La ₁ ” and “Lb ₁ ”, at room temperature (that is, at a temperature close to the ambient temperature in a normal distribution process), the film material having the fused side surface subjected to the surface modification treatment The same degree of heat seal strength can be obtained for both the heat-sealed side-to-side fusion-bonded sides and the heat-sealed side-to-side fusion-bonded side of a film material that has not been subjected to surface modification treatment. In other words, even if the sealing portion of the packaging bag has a configuration in which the surface to which the fusion side surfaces have been subjected to the surface modification treatment is heat-fused together, the object to be packaged is hermetically sealed and packaged. It has been found that even if distributed as it is, there is no problem in protecting the packaged object.

On the other hand, the present inventors have been interested in whether or not the above-mentioned heat seal strength at room temperature is maintained even after heating.
A similar tensile test was performed after heating to about 5 ° C., and the results are shown in FIG.

FIG. 9 shows that, for a sample in which the fusion side surfaces of a film material whose surface was subjected to a surface modification treatment were heated and fused together, as shown in the diagram "La ₂ ", 1.2 kg
It can be seen that interfacial peeling occurs at about f / 15 mm, and the peeling proceeds, leading to complete separation of the fused side surface at about 1.6 kgf / 15 mm. On the other hand, in the sample in which the fused side surfaces of the film material whose surface was not subjected to the surface modification treatment were heated and fused, the diagram "L
As shown by “b ₂ ”, it is understood that the film material is broken at around 5 kgf / 15 mm. When the two curves “La ₂ ” and “Lb ₂ ” are compared with each other, under the heating state (in other words, under the same state as when the packaged food is heated in a microwave oven), the surface of the fused side surface is modified. When the fused side surfaces of the treated film material are joined together, the heat sealing strength is lower than that of the joined film side surfaces of the film material not subjected to the surface modification treatment. It was found to be extremely low.

Based on the above findings, the inventors of the present invention have found that when affixing two film materials and heat-sealing the periphery thereof to obtain a packaging bag, a part of each of the seal portions is fused. By applying a surface modification treatment such as a corona discharge treatment on the side surface in advance to give a predetermined surface wetting tension, sufficient sealing strength is ensured in the distribution process at room temperature, while sealing is performed in a heated state. By reducing the strength locally, the low seal strength portion is positively peeled off by the internal pressure due to the water vapor generated from the packaged object due to the heating, and the water vapor is discharged to the outside to perform degassing, that is, It is conceived that a packaging bag can have both a function of protecting an object to be packaged in a distribution process and a function of preventing rupture during heating and cooking.

[0018]

SUMMARY OF THE INVENTION The present invention is based on the "technical background of the invention" and employs the following structure as specific means for solving the above-mentioned conventional problems. It is.

In the first invention of the present application, the peripheral portions of the pair of material films 11 and 12 which are stacked and laminated are heated and fused, and the moisture of foods or the like is put into the accommodating portion 2 formed inside the fused portion. In the packaging bag heated by the heating means in the packaged state while sealing and packaging the article W to be packaged, the surface of the pair of material films 11 and 12 is modified at appropriate positions on the peripheral edges of the fusion side surfaces 11a and 12a. Quality treatment,
The pair of material films 11 and 12 are characterized in that the entire area of the peripheral edge is heated and fused in a state where the surface modification processing portions 25 and 26 are brought into contact with each other.

According to a second aspect of the present invention, in the packaging bag according to the first aspect, the surface modification processing sections 25 and 2 are provided.
6 is characterized in that a surface wetting tension in the range of 40 to 55 dyn / cm is imparted by a surface modification treatment.

In the third invention of the present application, the first or the second
In the packaging bag according to the present invention, a peeling strength adjusting section 30 for adjusting the peeling strength of the fused section 24 is provided on the fused section 24 formed by fusing the surface modification processing sections 25 and 26 together. It is characterized by:

[0022]

According to the present invention, the following effects can be obtained by adopting such a configuration.

According to the first invention of the present application, a surface modification treatment is applied to an appropriate portion of the periphery of the fusion side surfaces 11a and 12a of the pair of material films 11 and 12 constituting the packaging bag 1, and Since the entire area of the peripheral edge portion is heated and fused in a state where the surface modification processing portions 25 and 26 of the pair of material films 11 and 12 are brought into contact with each other, the fusion of the surface modification processing portions 25 and 26 is performed. In the attachment portion, a high sealing strength that can sufficiently protect the package W in the distribution process is ensured under normal temperature conditions, while the package W is heated under heating of the package W by heating means. Since the fused portion is heated by the temperature of the steam generated with the rise of the temperature and the sealing strength is greatly reduced, the fused portion gradually peels off with an increase in the internal pressure of the housing portion 2 due to the steam, Through this stripped part The water vapor in the storage section 2 leaks to the outside, and an excessive increase in the internal pressure of the storage section 2 is prevented. As a result, the situation in which the packaging bag 1 is ruptured due to the increase in the internal pressure is surely and proactively. Will be prevented. In addition, a high sealing strength is ensured in the fused part between the parts of the packaging bag 1 other than the surface modification processing parts 25 and 26 under both the normal temperature state and the heated state.

Accordingly, in the packaging bag 1 according to the present invention, the original function of the packaging bag 1 is to protect the package W in the distribution process, which is hermetically sealed in the accommodating portion 2 of the packaging bag 1. In addition, an additional function of preventing the packaging bag 1 from bursting when the packaged object W is heated while the packaged object W is hermetically sealed in the storage portion 2 of the packaging bag 1 is also ensured. In addition, the protection of the package in the distribution process and the prevention of rupture during heating are compatible.

According to the packaging bag according to the second aspect of the present invention, the surface modification treatment sections 25 and 26 are provided with a surface wetting tension in the range of 40 to 55 dyn / cm by the surface modification treatment. Thus, the effects described above can be surely obtained.

According to the packaging bag of the third invention of the present application, the following specific effects can be obtained in addition to the effects described above or above. That is, in the packaging bag according to the present invention, the peel strength adjusting section 30 for adjusting the peel strength of the fused section 24 is attached to the fused section 24 formed by fusing the surface modification processing sections 25 and 26 together. By adjusting the peel strength of the fused portion 24 according to factors that govern the generation of water vapor during heating, for example, the type and amount of the packaged object W, the heating mode, and the like, Protection in the distribution process of the packaged product W hermetically sealed in the storage section 2 of the packaging bag 1 and prevention of the packaging bag 1 from bursting when the packaged product W is heated and cooked in a sealed packaging state. And can be further assured.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a packaging bag according to the present invention will be specifically described based on preferred embodiments.

First Embodiment FIGS. 1 to 3 show a packaging bag 1 according to a first embodiment of the present invention. As shown in FIG. 2, the packaging bag 1 has a first material film 11 and a second material film 12 having substantially the same shape, and fused side surfaces 11a and 12a thereof.
It is formed by heat-sealing the peripheral portion by heat sealing in a state where the two are in abutment with each other, and a housing for hermetically packaging an article W to be packaged such as food inside the peripheral portion. A part 2 is provided.

Actually, for example, the material film 1
In a state in which only three sides 1 and 12 are fused to form an open bag with one end opened, the article W to be packaged is accommodated in the accommodation section 2 and then the remaining side is fused. As shown in FIGS. 1 and 2, a packaging bag 1 in which an article to be packaged W is hermetically sealed in the accommodation section 2 is provided.

The material films 11 and 12 constituting the packaging bag 1 may be a single-layer film made of a single material or a laminated film (for example, a two-layer laminated film of a base material and a sealant layer, a base material and an intermediate film). Layer and a sealant layer, or a multilayer laminated film having a plurality of the above-mentioned intermediate layers). The bonding side is required to be a material excellent in the fusion property in order to secure the fusion property. Therefore, the above material film 1
When both 1 and 12 are single-layer films, the material films 11 and 12 themselves are made of polyethylene, polypropylene,
Ethylene vinyl acetate copolymer, composed of a resin material such as linear polyethylene, and when it is a laminated film, at least the sealant layer will be composed of each of the above resin materials, in this embodiment, Material film 1
The case where each of 1 and 12 is composed of a two-layer laminated film with the base material being “nylon” and the sealant layer being “linear polyethylene” will be described as an example.

As shown in FIG. 3, the packaging bag 1 has a pair of material films 11 and 12 formed by fusing side surfaces 11a and 11a.
12a are brought into contact with each other, and in such a state, the peripheral portions of the material films 11, 12, ie, the respective edges 1a to 1d of the packaging bag 1 are heat-sealed by heat sealing, respectively. There is (as mentioned above,
At least one edge is fused after the packaged object W is accommodated). In this case, at least one of the edges 1a to 1d among the fusion side surfaces 11a and 12a of the material films 11 and 12 is used. The entire area of one edge (edge 1d in this embodiment) or a portion corresponding to an area within a predetermined range in the edge length direction is subjected to a surface modification treatment by, for example, corona discharge treatment in advance, and the surface modification treatment is performed. Surface treatment unit 25, 2
Set it to 6. In this case, the surface treatment units 25, 2
In No. 6, the degree of the surface modification treatment is set so that the surface wetting tension is in the range of 40 to 55 dyn / cm, desirably about 50 dyn / cm.

Then, each of the edges 1a to 1d is subjected to a heat sealing process so that each of the material films 11, 1 is processed.
2 is heated and fused over the entire periphery of the peripheral portion to form fused portions 21 to 24 (hatched portions in FIG. 1).

In the bonding state by the heat fusion,
First to third fusion parts 21 to 3 corresponding to the respective edges 1a to 1c.
The fusion parts 23 are both fusion joints of the untreated surfaces,
The fourth fused portion 24 corresponding to the edge 1d is a fusion bonded surface-treated surface. Therefore, the first fused portion 21
To the sealing properties of the third fused portion 23 and the fourth fused portion 24
Will be different from the sealing characteristics. That is, the former is
While both have a high seal strength at normal temperature and when heated at about 105 ° C., the latter has a high seal strength at normal temperature, but has only a very small seal strength at the time of heating (see FIG. 8 and FIG. 9).

Therefore, the article W to be packaged is sealed (packaged food) in the container 2 enclosed by the first to fourth fusion parts 21 to 24 of the packaging bag 1. ), If you put it on the market and distribute it,
Since the distribution of goods is carried out at room temperature, the packaging bag 1
, The high sealing strength is secured in all of the first to fourth fused parts 21 to 24, and the protection of the packaged object W by the packaging bag 1 in the distribution process is ensured. When the package W is a food, the freshness or quality of the package W is maintained.

On the other hand, a consumer who has purchased the above-mentioned packaged product in the market, for example, when the above-mentioned packaged object W is a food, heats the packaged product in a packaged state by heating means such as a microwave oven when eating it. Often do. In this case, when the temperature of the packaged object W gradually increases with the progress of the heating action, steam is generated from the packaged object W, and the generated steam causes the storage section 2 of the packaging bag 1 to move.
The part expands and its internal pressure rises. On the other hand, the fourth fusion portion 24 of the packaging bag 1 is gradually heated by the temperature of the generated steam in the storage portion 2, and the sealing strength of the fourth fusion portion 24 rapidly decreases.

As a result, in the fourth fused portion 24, the inner pressure is subjected to the internal pressure, and the inner edge 24a on the accommodation portion 2 side is gradually peeled off, and this is separated from the inner edge 24a to the outer edge 24a.
When the peeling finally reaches the outer edge 24b of the fourth fused portion 24, the accommodating portion 2 communicates with the outside through the exfoliated portion, and enters into the accommodating portion 2. The filled steam leaks out. Thereby, the occurrence of a situation in which the packaging bag 1 ruptures due to an increase in internal pressure due to heating is prevented beforehand and reliably.

As described above, in the packaging bag 1 of this embodiment, protection of the package W such as food sealed in the distribution process in the distribution process, and the package W is protected by the packaging bag 1. In the case where the packaging bag 1 is heated in the sealed packaging state, the packaging bag 1 can be prevented from bursting.

Further, in the packaging bag 1 of this embodiment,
In particular, leakage of water vapor during heating (that is,
) In accordance with the situation of water vapor generation
Therefore, the peel strength adjusting section 30 described below is
Is provided. That is, in this embodiment, FIG.
As shown in FIG. 4 and FIG.
A cut-out hole 31 having a constant diameter is provided.
31 and an edge of the fourth fusion portion 24 close to the accommodation portion 2.
Spacing S with inner edge 24a₁Is the type, volume,
Increase or decrease should be set according to various factors such as water content.
Thus, the peel strength adjusting section 30 is configured. Take
By providing the peel strength adjusting section 30 having the configuration,
The attachment part 24 is peeled off and the accommodation part 2 is cut out of the cutout hole 31.
Time to communicate with the outside through the
Start time) can be adjusted. For example, packaged goods
If W is a large amount of generated steam, the above interval
S ₁Set to a relatively small size to release gas early.
Heating, as described above.
Prevention of rupture of the packaging bag 1 at the time is more accurate
Will be done. In FIG. 4, reference numeral 41 denotes peeling.
The edges are shown.

In another embodiment of the peel strength adjusting section 30, as shown in FIGS. 5 and 6, the surface-modified surfaces are fused and joined to obtain the fourth fused section 24. At this time, from the inner edge 24a of the fourth fused portion 24 to the outer edge 24b
The non-fused portion 33 is left without being fused to a predetermined range toward the non-fused portion 33, and the outer edge 33 of the non-fused portion 33 is
a and the distance S ₂ between the outer edge 24b of the fourth fused portion 24 and
The value is increased or decreased in accordance with various factors such as the type, volume, and water content of the packaged object W.
0 can also be configured. Also in the case of this embodiment, by increasing or decreasing setting of the spacing S _2, the housing part 2 in the fourth fused portion 24 is peeled off is the time to communicate with the outside through the non-fused portion 33 It can be adjusted. Further, in the case of this embodiment, the time required for degassing can be adjusted by increasing or decreasing the width of the non-fused portion 33.

Others (1) In the above embodiment, the fourth fused portion 24 formed by heating and fusing the surface modification treatment portions to each other is set over the entire area of one edge 1d of the packaging bag 1. However, the present invention is not limited to such a configuration. For example, in another embodiment, the fourth fused portion 24 is connected to the edge 1d.
Or the fourth fused portion 24 may be set at a plurality of edges of the edges 1a to 1d, respectively, and gas may be vented from a plurality of locations.

(2) In the above embodiment, the packaging bag 1 having a substantially rectangular planar shape has been described as an example.
The present invention is not limited to such a shape, but can be widely applied to various shapes such as a triangle and a circle.

(3) In the above embodiment, a pair of material films 11 and 12 each having a rectangular shape are provided for convenience of explanation.
Are described as an example in which the packaging bag 1 is formed by laminating the material films 11 and 12 in practice.
Are supplied as a roll wound body, and are fusion-bonded while being continuously unwound from the roll wound body. The present invention is also applied to the packaging bag 1 manufactured by such a forming process. Of course, the invention can be applied. In this case, it is desirable that the surface modification treatment on the fused side surfaces 11a and 12a of the material films 11 and 12 be performed in a manufacturing process of the material films 11 and 12.

(4) In the above embodiment, the corona discharge treatment is an example of a surface modification treatment method for the fused side surfaces 11a and 12a of the material films 11 and 12.
However, the method of the surface modification treatment in the present invention is not limited to this “corona discharge treatment”, and various methods such as an additive treatment method and an ultraviolet irradiation method can be equally applied. The point is that the surface of the fused side surfaces 11a and 12a is 4
In the range of 0 to 55 dyn / cm, desirably 50 dyn / cm.
It is sufficient that a surface wetting tension of about cm can be applied.

(5) In the above embodiment, “food” is used as an example of the article W to be packaged in the packaging bag 1.
However, the article W to be packaged in the present invention is not limited to only “foods”, but includes general articles that generate steam by heating.

[Brief description of the drawings]

FIG. 1 is a plan view of a packaging bag according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the packaging bag shown in FIG.

FIG. 3 is an explanatory view of a manufacturing process of the packaging bag shown in FIG.

FIG. 4 is an explanatory view of a peeled state of a fusion bonded portion in the packaging bag shown in FIG.

FIG. 5 is a plan view of the packaging bag according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a peeled state of a fused portion in the packaging bag shown in FIG. 2;

FIG. 7 is a characteristic diagram showing a relationship between surface wetting tension and heat sealing strength when a surface modification treatment is performed on a sealing surface of a film material.

FIG. 8 is an explanatory diagram of a change in heat seal strength at normal temperature.

FIG. 9 is a diagram illustrating a change in heat seal strength under heating.

[Explanation of symbols]

1 is a packaging bag, 2 is a storage unit, 11 is a first material film,
12 is a second material film, 21 to 24 are fusion parts, 25 and 26 are surface treatment parts, 30 is a peel strength adjusting part, 31 is a ventilation opening, 33 is a non-fusion part, 41 is a peeling edge, and W is It is a packaged item.

Claims (3)

[Claims] A pair of material films (1) stacked and arranged.
1) and (12) are heat-sealed at their peripheral portions, and a package (W) containing water such as food is hermetically packaged in a housing portion (2) formed inside the fusion-bonded portion. A packaging bag heated by a heating means in a state, wherein a surface modification treatment is applied to an appropriate portion of a peripheral portion of the fusion side surfaces (11a) and (12a) of the pair of material films (11) and (12). And a pair of material films (1
1) and (12) are the surface modification treatment sections (25) and
(26) A packaging bag, wherein the entire periphery of the peripheral portion is heat-fused in a state where the two are in contact with each other. 2. The method according to claim 1, wherein the surface modification treatment sections (25) and (26) are provided with a surface wetting tension in a range of 40 to 55 dyn / cm by the surface modification treatment. Bags for packaging. 3. The fusion part (24) according to claim 1, wherein the fusion part (24) formed by fusing the surface modification processing parts (25) and (26) to each other is peeled off. A packaging bag provided with a peel strength adjusting section (30) for adjusting the strength.