WO2018008117A1 - Packaging bag - Google Patents

Abstract

[Problem] To provide a packaging bag that has excellent bag-making characteristics, with which it is possible to perform microwave cooking while the packaging bag remains sealed, and with which it is possible to easily identify an appropriate heating state of food in the packaging bag. [Solution] A packaging bag 1 with which it is possible to heat a heating subject M in a state of being contained in a containment space 1h, wherein: the packaging bag 1 is formed by a multilayer film F provided with an inner layer film 3, which has a pore formation film F1 and an adhesive layer BL containing a thermally adhesive resin, and an outer layer film 4 of a cover film F2 having a smaller extensibility and a higher heat resistance than the inner layer film 3; when a tension is applied at a temperature equal to or greater than a given temperature, a large number of through holes h penetrating from the obverse side to the reverse side is formed in the inner layer film 3; the packaging bag 1 is provided with linking parts 5, 10 having an inner surface linking part at which the inner surfaces of the pore formation film F1 are linked; and the peeling part linking strength is less than the inner surface linking strength, and greater than the lamination linking strength at portions other than the linking parts 5, 10.

Description

Packaging bag

The present invention relates to a packaging bag. More specifically, the present invention relates to a packaging bag that can heat food contained in a cooking device using microwaves (hereinafter referred to as a microwave oven) as it is in a sealed packaging bag.

In recent years, along with lifestyle changes, a large number of processed foods and frozen foods that can be cooked in a short time and simply have been developed. In particular, the microwave oven is easy to use and anyone can easily heat and cook food. For this reason, development of the processed food and frozen food which can be cooked with a microwave oven is advancing.

Processed foods and frozen foods such as those described above are sold in the state of being packaged in a packaging bag or the like, but when heated in a microwave oven, the pressure inside the packaging bag is caused by water vapor generated from the processed foods and frozen food inside. There was a risk that packaging bags and the like would burst. For this reason, in the conventional processed food and frozen food, it was necessary to open a packaging bag beforehand or to take out from a packaging bag before cooking with a microwave oven.

In order to save time and labor as described above, packaging bags that can be heated in a microwave oven while sealing processed foods and frozen foods have been developed (for example, Patent Documents 1 to 3).

Patent Documents 1 and 2 disclose a packaging bag provided with an exhaust hole for allowing water vapor to escape in order to prevent the bag from bursting. In this packaging bag, water vapor can be discharged from the exhaust hole through the exhaust hole. Therefore, even if the processed food or frozen food is heated in a microwave oven with the packaging bag, the internal pressure of the packaging bag can be reduced, so that the packaging bag can be prevented from bursting.

However, in the packaging bags as disclosed in Patent Documents 1 and 2, since the exhaust holes are provided in advance, it is necessary to close the exhaust holes with a seal or the like so that foreign matter does not enter through the holes. There is a problem that it takes time and effort. In addition, when cooking by heating, the consumer needs to remove the seal or the like, and there is a problem that it takes time to prepare for cooking.

Therefore, a packaging bag is disclosed in which a hole is formed when the internal pressure of the bag is increased by water vapor generated when the processed food or frozen food inside is heated by a microwave oven without providing a hole in the bag in advance. (Patent Document 3). The packaging bag of Patent Document 3 is formed by a film in which a synthetic resin stretched film as an outer layer and a synthetic resin unstretched film as an inner layer are bonded together. In addition, a weakly bonded portion is provided by providing a portion (low melting point portion) where a low-melting-point heat sealing agent is applied and bonded or by applying a release agent. Moreover, in the stretched film made of synthetic resin, a cutting line is engraved at a portion corresponding to the weakly bonded portion.

For this reason, when this packaging bag is put in a microwave oven or the like and heated to increase the pressure in the bag, the bag swells, and the stretched film and the unstretched film are peeled off at the weakly bonded portion, and the stretched film is cut along the cutting line. It is described that an opening is formed in the stretched film. When the opening is formed, stress concentration occurs at the boundary between the weakly connected portion and the strongly bonded portion (the portion having a stronger adhesive force than the weakly connected portion), that is, the edge of the opening, and the unstretched film at that position Describes that a small hole is opened.

Japanese Patent Laid-Open No. 5-270549 JP2013-32168A International Publication No. 2001/082011

However, in the packaging bag of Patent Document 3, in order to properly open the package when heated, the stretched film must be provided with a break line, and extra processing is required for the film. In addition, a heat-melting agent or release agent having a low melting point must be applied so that the position of the break line of the stretched film and the weakly bonded portion overlap. Then, pitch management in the bag making process is very difficult, and it is difficult to carry out bag making at high speed. That is, in the packaging bag of Patent Document 3, although the trouble of providing the exhaust hole is reduced, the bag making process is complicated, and thus the problem that the bag making is troublesome still remains.

In addition, the packaging time for processed foods and frozen foods describes the warming time when cooking frozen foods with a microwave oven. However, due to various factors such as the characteristics of the microwave oven and how to place processed foods and frozen foods, processed foods and frozen foods may not be heated properly even when heated for a specified time. In the case of frozen food, the specified time is set according to the internal standards of each food manufacturer. However, consumers do not always heat from a frozen state in line with the internal standards of each food manufacturer. For example, frozen foods may be heated in a microwave oven from a completely frozen state lower than the food manufacturer's internal standards. In this case, even if the frozen food is heated in the microwave for a specified time, the heating is insufficient. In addition, frozen foods may be heated in a microwave oven from a slightly melted state higher than the food manufacturer's internal standards. In this case, if the frozen food is heated in the microwave oven for a specified time, it will be overheated. Moreover, when the temperature of processed food or frozen food is lower than expected, even if it is heated for a specified time in a microwave oven, heating is insufficient.

In the above-described packaging bag, it is desirable that the timing at which water vapor is generated from the bag coincides with the timing at which the processed food or frozen food is appropriately heated. However, at present, in the packaging bag as described above, when the pressure in the bag exceeds a certain level, the water vapor in the bag is merely released, and the processed food and frozen food are in an appropriate state (the most delicious) It is structured such that the consumer cannot easily grasp that it has been heated to (state).

Due to the circumstances described above, consumers should stop the microwave oven from touching packaging bags, processed foods and frozen foods, or eat a little cooked food, so as not to overheat or underheat. To check the heating status. However, even if the heating state is confirmed by the method as described above, it is very difficult for the consumer to determine whether or not the heating state is appropriate. Currently, there are many cases where insufficient heating or overheating occurs. .

If the consumer can easily grasp that the processed food or frozen food has been heated to an appropriate state (the most delicious state), the consumer can eat the processed food or frozen food deliciously. In addition, manufacturers of processed foods and frozen foods can provide foods to consumers with the originally planned taste, and therefore, packaging bags having such functions are required.

In view of the above circumstances, the present invention provides a packaging bag that is excellent in bag making suitability, can be cooked in a microwave oven as it is in a sealed packaging bag, and can easily grasp the appropriate heating status of food in the packaging bag. For the purpose.

The packaging bag of the first invention is a packaging bag capable of heating an object to be heated in a state in which the object to be heated is accommodated in an internal accommodating space, the packaging bag comprising a pore-forming film and the pores An inner layer film located on the inner side having an adhesive layer provided on the outer side of the formed film, and an outer layer located on the outer side of the inner layer film, which has a cover film having a lower extensibility and higher heat resistance than the inner layer film. The inner layer film is formed with a plurality of communication holes penetrating the front and back surfaces when a certain level of tension is applied at a certain temperature or higher, and the bonding The agent layer contains a heat-adhesive resin, and includes a connecting portion having an inner surface connecting portion that connects inner surfaces of the pore-forming film in the inner layer film, and the outer layer in the connecting portion The peeling portion connection strength between the film and the adhesive layer is weaker than the inner surface connection strength between the inner surfaces of the pore-forming films of the inner layer film in the inner surface connection portion, and the outer layer film and the adhesion in a portion other than the connection portion It is characterized by being stronger than the lamination connection strength of the agent layer.
The packaging bag of the second invention is characterized in that, in the first invention, the thermoadhesive resin contained in the adhesive layer in the inner layer film has a biquad softening point of 40 ° C. or more and less than 100 ° C. To do.
The packaging bag of the third invention is characterized in that, in the first or second invention, the weight ratio of the heat-adhesive resin to the total weight of the adhesive layer in the inner layer film is 30 to 80% by weight.
In the packaging bag of the fourth invention, in the first, second or third invention, in the adhesive layer in the inner film, the surface in contact with the outer film is a surface not subjected to corona discharge treatment. Features.
The packaging bag according to a fifth aspect of the present invention is the packaging bag according to any one of the first to fourth aspects, wherein a lamination connection strength between the adhesive layer and the outer layer film when not heated is 0.5 to 1.5 N / 15 mm. Features.
The packaging bag according to a sixth aspect of the present invention is the packaging bag according to any one of the first to fifth aspects, wherein the peel-off portion connection strength between the adhesive layer and the outer layer film when not heated is 1.3 to 4.0 N / 15 mm. It is characterized by.
The packaging bag of the seventh invention is the packaging bag of any one of the first to sixth inventions, wherein the pore-forming film and the adhesive layer in the inner layer film contain a granular member, The weight ratio of the granular member to the weight is 20 to 60% by weight, and the weight ratio of the granular member to the total weight of the adhesive layer is 20 to 60% by weight.
The packaging bag of the eighth invention according to any one of the first to seventh inventions, wherein the pore-forming film and the adhesive layer in the inner layer film include a low melting point polyolefin resin having a melting point of less than 100 ° C. The weight ratio of the low melting point polyolefin resin to the total weight of the pore-forming film is 5 to 70% by weight, and the weight ratio of the low melting point polyolefin resin to the total weight of the adhesive layer is 5 to 45% by weight. It is characterized by being.
In the packaging bag of the ninth invention according to any one of the first to sixth inventions, the expansion ratio of the pore forming film and the adhesive layer in the inner layer film is 1.1 to 2.5 times. Features.

According to the first invention, since the adhesive layer contains the heat-adhesive resin, when the packaging bag is heated by evaporation of the moisture inside the packaging bag, the thermal bonding contained in the adhesive layer. As a result of the softening of the adhesive resin, the laminate connection strength and the peeled portion connection strength are reduced. Moreover, when the packaging bag expands due to the evaporation of moisture inside the packaging bag, a force is applied to peel off the outer layer film from the adhesive layer in the inner layer film. For this reason, when the packaging bag expands due to the evaporation of moisture inside the packaging bag, the outer layer film is peeled off from the inner layer film and the inner layer film is exposed in a state in which the inner surfaces of the pore-forming films in the inner layer film are maintained. . Therefore, if the content ratio of the heat-adhesive resin is adjusted, when the object to be heated is appropriately heated and pressurized, the inner layer film can be exposed without releasing the object to be heated to the outside. it can. And if an inner layer film is exposed, since the external appearance of a packaging bag will change, it can grasp | ascertain easily that the to-be-heated material was heated and pressurized appropriately only by seeing the state of a packaging bag. Moreover, when the inner layer film is exposed, the tension applied to the inner layer film is increased, so that a large number of communication holes are formed in the pore forming film and the adhesive layer in the inner layer film, and water vapor is released to the outside. Then, since the tension applied to the inner layer film can be kept below a certain level, it is possible to prevent rupture of the packaging bag.
According to the second invention, if the Vicat softening point of the heat-adhesive resin contained in the adhesive layer in the inner layer film is adjusted to 40 ° C. or higher and lower than 100 ° C., the outer layer film and the inner layer in the state of room temperature or lower It is possible to maintain the lamination connection strength and the peel-off portion connection strength of the adhesive layer in the film so that the outer layer film does not peel from the adhesive layer. And when a packaging bag is heated, the lamination | stacking connection strength and peeling part connection strength of the adhesive bond layer in an outer layer film and an inner layer film can be reduced appropriately.
According to the third invention, if the weight ratio of the heat-adhesive resin to the total weight of the adhesive layer in the inner layer film is adjusted to 30 to 80% by weight, the laminated connection of the adhesive layer in the outer layer film and the inner layer film The strength and peeled portion connection strength can be maintained such that the outer layer film does not peel off from the adhesive layer. In addition, when the object to be heated is appropriately heated and pressurized, and the internal temperature and pressure are in an appropriate state, the laminate connection strength and the peeling portion connection strength of the adhesive layer in the outer layer film and the inner layer film are appropriately set. The inner layer film can be exposed by lowering.
According to the 4th invention, in the said adhesive bond layer in an inner layer film, the surface which contacts an outer layer film is adjusted to the surface which has not performed the corona discharge process. For this reason, since it is possible to surely weaken the lamination connection strength and the peeling portion connection strength of the adhesive layer in the outer layer film and the inner layer film as compared with the inner surface connection strength, when the object to be heated is appropriately heated, the outer layer The film can be reliably peeled from the inner layer film.
According to the fifth aspect of the present invention, the adhesive layer between the outer layer film and the inner layer film can be adjusted by adjusting the lamination connection strength of the adhesive layer between the outer layer film and the inner layer film to 0.5 to 1.5 N / 15 mm when not heated. The laminate connection strength and the peel-off portion connection strength can be reliably reduced as compared with the inner surface connection strength. Therefore, when the article to be heated is appropriately heated, the outer layer film can be reliably peeled off from the inner layer film.
According to the sixth invention, the outer layer film can be used during distribution storage, etc., if the peel-off portion connection strength between the outer layer film and the inner layer film when not heated is adjusted to 1.3 to 4.0 N / 15 mm. Can be prevented from peeling off from the inner layer film.
According to the seventh invention, in the pore-forming film and the adhesive layer in the inner layer film, the content of the granular member is 20 to 60% by weight relative to the total weight of the pore-forming film, and the granular member is based on the total weight of the adhesive layer. The content is adjusted to 20 to 60% by weight. For this reason, when the to-be-heated material is appropriately heated and pressurized, and the internal temperature and the internal pressure are in an appropriate state, pores penetrating the front and back can be formed in the inner layer film. Therefore, the inner layer film can be prevented from bursting when the object to be heated is heated.
According to the eighth invention, in the pore-forming film and the adhesive layer in the inner layer film, the weight ratio of the low-melting-point polyolefin resin to the total weight of the pore-forming film is 5 to 70% by weight, The weight ratio of the melting point polyolefin resin is adjusted to 5 to 45% by weight. For this reason, when the object to be heated is appropriately heated and pressurized and the internal temperature and the internal pressure are in an appropriate state, pores penetrating the front and back can be formed in the inner layer film. Therefore, the inner layer film can be prevented from bursting when the object to be heated is heated.
According to the ninth invention, in the pore-forming film and the adhesive layer in the inner layer film, if the expansion ratio of the pore-forming film and the adhesive layer is adjusted to 1.1 to 2.5 times, When an object is appropriately heated and pressurized and the internal temperature and internal pressure are in an appropriate state, pores penetrating the front and back of the inner layer film are formed. Therefore, the inner layer film can be prevented from bursting when the object to be heated is heated.

It is a schematic explanatory drawing of the packaging bag 1 of this embodiment, Comprising: (A) is a side view, (B) is a schematic sectional drawing. (A) is a schematic plan view of the packaging bag 1 of this embodiment, (B) is a schematic back view of the packaging bag 1 of this embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the shape change of the packaging bag 1 when the packaging bag 1 of this embodiment is heated with a microwave oven, (A) is the state before a heating, (B) is from a to-be-heated object by heating. The packaging bag 1 is swelled by the generated water vapor, and the inner layer film 3 and the outer layer film 4 are kept connected. In (C), the heating further proceeds from the state (B). 3, the outer layer film 4 is peeled off, the inner layer film 3 is exposed, and the communication hole h is formed in the inner layer film 3. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the multilayer film F used for the packaging bag 1 of this embodiment, Comprising: (A) is a schematic sectional drawing, (B) is the pore formation film F1 and the adhesive bond layer BL of a foam film. It is a schematic explanatory drawing of the state in which the cover film F2 peels off and the communication hole h penetrating the front and back is formed in the case, (C) is a film of the pore-forming film F1 and the adhesive layer BL including the particle member p It is a schematic explanatory drawing of the state in which the cover film F2 peels in the case and the communication hole h which penetrates the front and back is formed. 1 is a table 1 showing the results of Example 1. 4 is a table 2 showing the results of Example 4.

Next, an embodiment of the present invention will be described with reference to the drawings.
The packaging bag of the present invention is a packaging bag for containing an object to be heated therein, is excellent in bag making suitability, can be cooked in a microwave oven with a sealed packaging bag, and heats the object to be heated. It is characterized by a structure that allows visual confirmation of the situation from the outside.

The method for heating the object to be heated contained in the packaging bag of the present invention is not particularly limited. For example, a method capable of heating an object to be heated without causing deterioration of the packaging bag, such as heating using microwaves, can be employed. For example, an object to be heated accommodated in the packaging bag of the present invention can be heated with a microwave oven or the like.

Also, the object to be heated accommodated in the packaging bag of the present invention may be anything that can be heated by the above-described method and generates steam or the like by heating. For example, foods that require heating, such as processed foods and frozen foods, and heat insulation members such as heat insulation towels, and the like correspond to the objects to be heated. Examples of processed foods and frozen foods include udon noodles, soba noodles, Chinese noodles, buns, shochu, gyoza, fried sweet potatoes, various side dishes, and the like.

Hereinafter, a case where the heating method is a microwave oven and the heated object is a frozen food will be described as a representative.

Further, the shape of the packaging bag of the present invention is not particularly limited. For example, a general pillow packaging bag, a three-side seal bag, a four-side seal bag, a standing pouch structure bag, and the like can be cited as the packaging bag of the present invention. That is, the packaging bag of this invention should just have a connection part which connected the films which form a bag by methods, such as heat sealing | fusion, and is not specifically limited.
In the following description, the case where the packaging bag of the present invention is a general pillow packaging bag will be described as a representative.

(Definition of terms)
Although the packaging bag 1 of this embodiment is demonstrated below, the main terms used by the following description are defined.

(Inner surface connection part and inner surface connection strength)
An inner surface connection part means the part which the inner surfaces of the pore formation film F1 in the connection parts 5 and 10 of the packaging bag 1 of this embodiment connected.
The inner surface connection strength means the connection strength between the inner surfaces of the pore-forming film F1 at the inner surface connection portion. As will be described later, when the connecting portions 5 and 10 are formed by heat sealing, it means the heat sealing strength between the inner surfaces of the pore forming film F1.

(Laminated connection strength)
The laminated connection strength means the connection strength between the adhesive layer BL and the cover film F2 in the multilayer film F. More specifically, the laminate connection strength means the laminate strength of the adhesive layer BL and the cover film F2 in a state where the multilayer film F is not heated from the outside. Therefore, when the packaging bag 1 is formed of the multilayer film F, the connection strength between the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 is the lamination connection strength in the portions other than the connection portions 5 and 10. Is maintained.

(Peeling part connection part and peeling part connection strength)
The peeling portion connecting portion means a portion where the adhesive layer BL and the cover film F2 are connected in the connecting portions 5 and 10 of the packaging bag 1 of the present embodiment.

The peeling portion connection strength means the connection strength between the adhesive layer BL and the cover film F2 in the above-described peeling portion connection portion. In the packaging bag 1 of this embodiment, when the connection parts 5 and 10 are formed by heat sealing, the adhesive layer BL is heated at that position. Therefore, the connection strength between the adhesive layer BL and the cover film F2 at the positions of the connection portions 5 and 10 is stronger than the lamination connection strength of portions other than the connection portions. Therefore, a portion where the adhesive layer BL and the cover film F2 are connected at the positions of the connecting portions 5 and 10 is referred to as a peeling portion connecting portion, and the connection strength of the portion is referred to as a peeling portion connecting strength.

(Packaging bag 1 of this embodiment)
The packaging bag 1 of the present embodiment has a multilayer film F in which peeling occurs between the adhesive layer BL in the inner film 3 of the multilayer film F and the cover film F2 in the outer film 4 when the article to be heated M is heated. It is formed using.

As shown in FIG. 1 and FIG. 2, the packaging bag 1 of this embodiment is a member formed in a bag shape with the article to be heated M accommodated therein. Specifically, the packaging bag 1 of the present embodiment blocks the internal space 1h from the outside in an airtight and liquid-tight manner by connecting portions 5 and 10 which are heat-sealed by overlapping the edges of a multilayer film F described later. It is formed in the shape of a pillow packaging bag.

The packaging bag 1 of the present embodiment is formed by a multilayer film F described later. In the multilayer film F, the inner layer film 3 and the outer layer film 4 are connected by the adhesive layer BL in the inner layer film 3. For this reason, the inner layer film 3 located inside, that is, the inner layer film 3 that functions as an interior bag for directly packaging the object to be heated M is formed by the pore forming film F1 and the adhesive layer BL containing the heat-adhesive resin. Is done. On the other hand, the outer layer film 4 positioned outside the inner layer film 3, that is, the outer layer film 4 functioning as an outer bag covering the inner bag is formed by the cover film F2. In addition, as will be described later, the cover film F2 is made of a film having lower extensibility and higher heat resistance than the pore-forming film F1 and the adhesive layer BL constituting the inner layer film 3.

And in the packaging bag 1 of this embodiment, the pore formation film F1 in the inner layer film 3 is heat-sealed in a state of being overlapped so as to be in surface contact with each other, thereby forming the connecting portions 5 and 10. That is, the pore-forming films F1 in the inner layer film 3 are overlapped so as to be in surface contact with each other, and the portion is sandwiched from the outside (that is, from the outer surface of the cover film F2 that is the outer layer film 4). The connecting portions 5 and 10 are formed by heat-sealing F1. Therefore, the connection parts 5 and 10 are the inner surface connection part in which the pore forming films F1 in the inner layer film 3 are connected to each other, and the peeling part connection part in which the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 are connected. Will have. In addition, since the connection parts 5 and 10 are formed as mentioned above, in the connection parts 5 and 10, the cover films F2 are not in contact with each other (that is, not connected).

The inner surface connection strength of the inner surface connection portion between the pore forming films F1 in the inner layer film 3 of the connection portions 5 and 10 is the lamination connection of the adhesive layer BL in the inner layer film 3 of the multilayer film F and the cover film F2 in the outer layer film 4. It is formed to be stronger than the strength. Moreover, since the adhesive layer BL in the inner layer film 3 contains a heat-adhesive resin, when the pore-forming films F1 are heat-welded, the heat-adhesive resin contained in the adhesive layer BL The peeled portion connection strength of the adhesive layer BL in the inner layer film 3 of the connecting portions 5 and 10 and the cover film F2 in the outer layer film 4 can be made weaker than the inner surface connecting strength while being made stronger than the laminated connection strength. Furthermore, when the article to be heated M is heated by the heat-adhesive resin contained in the adhesive layer BL (in other words, when the temperature of the packaging bag 1 is increased), the packaging bag 1 is at a temperature below room temperature. Compared with the state which exists, the peeling part connection strength and lamination | stacking connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 can be reduced. Then, when tension is applied to the packaging bag 1 when the temperature of the packaging bag 1 is increased, the connection between the inner layer film 3 and the outer layer film 4 is released at the separation portion coupling portion in the coupling portions 5 and 10, and the inner layer film 3. Can be exposed.

For example, if the amount or material of the heat-adhesive resin contained in the adhesive layer BL in the inner layer film 3 is adjusted, the adhesion in the inner layer film 3 can be achieved with the strength measured by a known test method (JIS K 6854-3). The laminated connection strength of the cover film F2 in the adhesive layer BL and the outer layer film 4 is about 0.5 to 1.5 N / mm, and the peeled portion connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 is 1. About 3 to 4.0 N / mm. If the peel-off portion connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 is about 1.3 to 4.0 N / mm, the inner layer film 3 and the outer layer film 4 are firmly connected. Therefore, even if force is applied to the packaging bag 1, it is difficult to release the connection between the two.

On the other hand, if the amount and the material of the heat-adhesive resin contained in the adhesive layer BL in the inner layer film 3 are adjusted, the temperature of the packaging bag 1 is maintained while maintaining the above-described laminated connection strength and peeling portion connection strength. When becomes high, the lamination | stacking connection strength and peeling part connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 can be reduced. That is, when the temperature of the packaging bag 1 is increased, the adhesive layer BL and the outer layer in the inner layer film 3 are reduced due to a decrease in the adhesive force due to the heat of the heat-adhesive resin contained in the adhesive layer BL in the inner layer film 3. The laminate connection strength and peel-off portion connection strength of the cover film F2 in the film 4 are reduced. Then, when tension is applied to the packaging bag 1, the connection between the inner layer film 3 and the outer layer film 4 can be released at the peeling portion connecting portion in the connecting portions 5 and 10. Therefore, when tension is applied to the packaging bag 1 when the temperature of the packaging bag 1 is increased, the outer layer film 4 is peeled off from the inner layer film 3 at the peeling portion connecting portion in the connecting portions 5 and 10, and the inner layer film 3 is removed. Can be exposed.

In addition, the inner surface connection strength of the inner surface connection portion between the pore forming films F1 in the inner layer film 3 is a strong physical adhesion in which the surfaces are heat-melted and mixed at the time of heat welding. On the other hand, the lamination connection strength and the peel-off portion connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 are weak chemical adhesion due to functional groups on each other. For this reason, the inner surface connection strength of the inner surface connection portion between the pore forming films F1 in the inner layer film 3 is higher than the lamination connection strength and the peeling portion connection strength of the adhesive film BL in the inner layer film 3 and the cover film F2 in the outer layer film 4. Become stronger. Therefore, when the temperature and pressure of the packaging bag 1 are increased, the connecting portions 5 and 10 do not peel off the pore-forming films F1 connected by the inner surface connecting portion, but the adhesive layer in the inner layer film 3 The outer layer film 4 can be peeled from the inner layer film 3 at the peeling portion connecting portion where the cover film F2 in the BL and the outer layer film 4 is connected.

Further, in the inner layer film of the multilayer film F, the connection strength between the pore forming film F1 and the adhesive layer BL is the lamination connection strength or the peeled portion connection strength between the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4. It is firmly connected so as to be stronger. The method for connecting the pore forming film F1 and the adhesive layer BL is not particularly limited. Even when the temperature and pressure of the packaging bag 1 are increased, the connecting portion between the pore forming film F1 and the adhesive layer BL is released. Any connection method may be used.

For example, in the case of a laminated product in which the pore-forming film F1 and the adhesive layer BL are coextruded, the surface where both are in contact with each other becomes a strong physical adhesive surface that is heat-melt mixed. For this reason, even when the temperature and pressure of the packaging bag 1 are increased, the connection strength between the pore-forming film F1 and the adhesive layer BL is set so that the adhesive layer BL in the inner film 3 and the cover film F2 in the outer film 4 are laminated. It can be made stronger than the connection strength and the peeled portion connection strength.

Also, a method of laminating the pore forming film F1 and the adhesive layer BL by laminating with a general ether adhesive or ester adhesive, or laminating by dry lamination, extrusion lamination or thermal lamination is adopted. You can also In the case of a laminated product in which the pore-forming film F1 and the adhesive layer BL are laminated, the connecting portion between the pore-forming film F1 and the adhesive layer BL is a chemical bond that is weaker than the physical adhesion. Even in this case, the surface energy can be increased by performing corona discharge treatment on the surfaces in contact with each other. Then, the connection strength between the pore forming film F1 and the adhesive layer BL can be made stronger than the lamination connection strength and the peeling portion connection strength between the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4.

(Operational effect of the packaging bag 1 of the present embodiment)
Since the packaging bag 1 of this embodiment has the above configuration, it functions as follows.

(At room temperature or frozen)
First, in the multilayer film F, the peeled portion connection strength and the laminated connection strength of the inner layer film 3 and the outer layer film 4 have such a strength that they are not easily peeled off at normal temperature or in a frozen state. In addition, since the connecting portions 5 and 10 are likely to be peeled off from each other, the peeled portion connecting strength is such that the peeled portion connecting strength is not peeled even during distribution storage (about 1.3 to 4.0 N / mm). Damage such as peeling from the inner layer film 3 is less likely to occur.

Note that the inner surface connection strength between the inner surfaces of the pore forming film F1 in the inner layer film 3 and the connection strength between the pore forming film F1 and the adhesive layer BL are as follows: the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 Stronger than the peeled portion connection strength. Therefore, the connecting portions 5 and 10 are not peeled between the inner surface connecting portions of the pore forming films F1, and the inner layer film 3 is connected between the connecting portions of the pore forming film F1 and the adhesive layer BL. Problems such as peeling off do not occur.

(During cooking)
On the other hand, when cooking processed foods and frozen foods in a microwave oven, the packaging bag 1 of the present embodiment functions as follows. Can be heated.

First, the packaging bag 1 containing the article to be heated M is put into a microwave oven as it is, and the microwave oven is operated (FIG. 3 (A)). Then, the moisture in the object to be heated M generates heat, the object to be heated M is heated, and the water contained in the object to be heated M evaporates to become water vapor. When the multilayer film F comes into contact with the water vapor, the multilayer film F is heated and pressurized, and its temperature and pressure rise.

Since the adhesive layer BL in the inner film 3 of the multilayer film F contains a heat-adhesive resin, when the multilayer film F reaches a certain temperature or more, the adhesive force of the adhesive layer BL decreases. That is, the lamination connection strength and the peeling portion connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 are lowered. On the other hand, in the inner surface connecting portion between the inner surfaces of the pore-forming film F1 in the inner layer film 3, since the pore-forming films F1 are one layer heat-sealed by heat sealing, the multilayer film F has a constant temperature. Even if it becomes above, inner surface connection intensity | strength does not fall.

On the other hand, when the heat generation of the water in the heated object M progresses, the internal pressure of the packaging bag 1 rises due to the water vapor generated from the heated object M, and the packaging bag 1 expands. The tension is applied along the line.

When the pore forming film F1 and the adhesive layer BL in the inner layer film 3 constituting the multilayer film F are compared with the cover film F2 in the outer layer film 4, the extensibility of the cover film F2 in the outer layer film 4 is the smallest. For this reason, the tension | tensile_strength added along the surface direction of the multilayer film F will be supported by the cover film F2.

In the connecting portions 5 and 10, the inner surfaces of the pore forming film F1 in the inner layer film 3 are connected to each other at the surface contact portion, but the cover films F2 in the outer layer film 4 are not connected to each other. For this reason, the tension applied to the cover film F2 acts as a force for peeling off the inner surface connecting portions of the connecting portions 5 and 10 and a force for peeling the outer layer film 4 (that is, the cover film F2) from the adhesive layer BL in the inner layer film 3. become.

As described above, although the inner surface connection strength between the inner surfaces of the pore-forming film F1 in the inner layer film 3 does not decrease even when the temperature of the multilayer film F increases, the heat-adhesive resin contained in the adhesive layer BL in the inner layer film 3 Adhesive strength due to heat decreases. Then, due to the influence of the decrease in the adhesive force, the lamination connection strength and the peeling portion connection strength between the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 are reduced. Moreover, the inner surface connection strength between the inner surfaces of the pore-forming film F1 in the inner layer film 3 in the state of room temperature or the like is the lamination connection strength of the adhesive layer BL in the inner layer film 3 and the cover film F2 in the outer layer film 4 and the peeling portion connection The connecting force is stronger than the strength. For this reason, the outer layer film 4 is peeled off from the adhesive layer BL of the inner layer film 3 before the inner surface connecting portions of the connecting portions 5 and 10 are peeled off due to the tension applied along the surface direction of the multilayer film F. The pore forming film F1 and the adhesive layer BL are exposed. That is, when the outer layer film 4 is peeled off from the adhesive layer BL in the inner layer film 3, an appearance change in which the inner layer film 3 is exposed occurs.
(FIG. 3C).

The timing at which the outer layer film 4 is peeled off from the adhesive layer BL of the inner layer film 3 (timing at which the inner layer film 3 is exposed) is adjusted by adjusting the heat-adhesive resin of the adhesive layer BL in the inner layer film 3 and the like. It can control by adjusting the peeling part connection strength and lamination | stacking connection strength of the agent layer BL and the cover film F2. Therefore, according to the object to be heated M, the adhesive layer BL thermal adhesive resin or the like is adjusted, and the adhesive layer BL and the cover film F2 in the inner layer film 3 are appropriately adjusted in the peeled portion connection strength and the laminated connection strength. Then, when the heated object M is heated and pressurized in a state that the producer can taste the heated object M most deliciously, the inner layer film 3 (that is, the adhesive layer BL) is exposed. Can do.

As described above, in the packaging bag 1 of the present embodiment, the consumer can easily grasp that the heating of the article to be heated M has been completed only by looking at the state of the packaging bag 1. That is, since the packaging bag 1 of this embodiment has a function (deliciousness sensor) which makes a consumer grasp | ascertain the heating state of the to-be-heated material M, a consumer can eat the to-be-heated material M deliciously. it can. In other words, it is possible to provide the consumer with the food of the taste planned by the food manufacturer.

Further, when the adhesive layer BL of the inner layer film 3 is exposed, the internal pressure is supported only by the inner layer film 3 (that is, the pore forming film F1 and the adhesive layer BL). For this reason, if the expansion of the inner layer film 3 continues even after the adhesive layer BL of the inner layer film 3 is exposed, the inner layer film 3 may burst. However, as will be described later, the pore-forming film F1 and the adhesive layer BL forming the inner layer film 3 penetrate the front and back when the tension applied along the surface direction increases in a state where the temperature is higher than a certain temperature. A large number of communication holes h are formed.

After the inner layer film 3 (the pore forming film F1 and the adhesive layer BL) is exposed, if a tension is applied to the inner layer film 3, a large number of communication holes h are formed in the pore forming film F1 and the adhesive layer BL. Is formed. Then, since water vapor | steam is discharge | released outside from many communicating holes h, after the inner layer film 3 is exposed, the tension | tensile_strength added to the pore formation film F1 and the adhesive bond layer BL should be kept below a fixed magnitude | size. Can do. Therefore, rupture of the inner layer film 3, that is, rupture of the packaging bag 1 can be prevented.

In addition, the size of the communication hole h formed in the inner layer film 3 is not particularly limited, but it is desirable that the size is not more than a certain size (for example, 30 μm or less). With such a size, even if the communication hole h is formed, it is possible to prevent the heated object M from being discharged to the outside from the communication hole h.

(Improvement of product value)
The packaging bag 1 of the present embodiment is formed of a multilayer film F in which the cover film F2 in the outer layer film 4 is bonded to the adhesive layer BL in the inner layer film 3. In addition, when the edges of the multilayer film F are overlapped and heat-sealed (that is, the connecting portions 5 and 10), the inner surfaces of the pore forming film F1 in the inner layer film 3 constituting the multilayer film F are heat-sealed. It is supposed to be. Moreover, since the adhesive layer BL in the inner layer film 3 contains a heat-adhesive resin, it has the property of being able to adhere to the cover film F2 in the outer layer film 4 with heat and to be peeled off with heat. As described above, when a certain temperature and pressure are applied to the packaging bag 1, the inner layer film 3 including the pore-forming film F1 and the adhesive layer BL, which form a large number of communication holes, is heated. Water can be discharged while confining in a bag. Then, as a property required for the film used as the cover film F2, the property of forming pores is not necessary. Therefore, it becomes possible to use a highly transparent film having excellent printing characteristics as the cover film F2. Furthermore, if back printing is performed on the highly transparent cover film F2 excellent in printability and bonded to the inner layer film 3, it is possible to prevent the printing from dropping off or printing transfer. That is, since it becomes possible to print on the packaging bag 1 in the same manner as a conventional outer packaging bag of frozen food, it is possible to wrap the article to be heated M only with the multilayer film F, thereby increasing the commercial value. I can do it.

Thus, when using a highly transparent film excellent in printing characteristics as the cover film F2, the packaging bag 1 of the present embodiment has a function (cannot burst) that can be cooked by a microwave oven or the like, Since it can have good printing characteristics (clear printing, printing omission, and prevention of transfer of printing), the following advantages are also obtained.

Current frozen foods are usually double-wrapped with an outer bag that is clearly printed and has improved airtightness, and an inner bag that simply wraps an object to be heated. For this reason, it is necessary to take out the inner bag from the outer bag and put only the inner bag into a microwave oven for cooking.

On the other hand, the packaging bag 1 of the present embodiment is formed by a single-layer packaging of the multilayer film F that is clearly printed, airtight, and has a function that does not burst. You can cook it in the microwave. Then, the convenience of the consumer who cooks frozen food can be improved significantly.

Moreover, in the present frozen food, in the process of packaging the object to be heated, the inner bag packaging process in which the object to be heated is enclosed in the inner bag, and the inner bag are clearly printed and airtightness is improved. Two processes of the outer bag packaging process enclosed in an outer bag are required. However, since the packaging bag 1 of the present embodiment is a single-layer packaging that can be clearly printed and can improve airtightness, the packaging of the object to be heated can be completed in one step. Then, in the production of frozen foods, the process can be simplified and labor can be reduced, and the manufacturing cost can be reduced.

Furthermore, if printing is performed on the inner surface (the surface in contact with the adhesive layer BL) of the cover film F2 in the outer layer film 4, it is possible to prevent the printing from dropping off or transferring the printing.

(Multilayer film F)
As described above, the packaging bag 1 of the present embodiment is formed by the multilayer film F formed by laminating films having different properties. Below, the multilayer film F used for the packaging bag 1 of this embodiment is demonstrated in detail.

As shown in FIG. 4, the multilayer film F includes a pore-forming film F1, a cover film F2, and an adhesive layer BL provided between the pore-forming film F1 and the cover film F2.

(Pore forming film F1)
The pore-forming film F1 is a film that has a certain degree of extensibility and is formed of a material having a function of heat-sealing (heat-sealability) when heated in a state where the pore-forming films F1 are stacked. . The material of the pore forming film F1 is not particularly limited as long as it has the above properties. For example, a polyolefin resin can be employed as the material of the pore forming film F1. Specifically, mainly polyethylene such as high density polyethylene, medium density polyethylene, high pressure method low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, etc. It is possible to employ polypropylene such as copolymers, propylene homopolymers, propylene-ethylene copolymers, and mixtures of polyethylene and polypropylene.

Moreover, the pore-forming film F1 is adjusted so that a hole (communication hole h) penetrating the front and back is formed when a tension is applied along the surface direction in a state where the temperature is equal to or higher than a predetermined temperature. Yes. If the pore-forming film F1 contains a granular member or a low melting point polyolefin resin, or the pore-forming film F1 is a foamed film, the pore-forming film F1 having the above function can be obtained.

In addition, the predetermined temperature mentioned above means the temperature which the pore formation film F1 heated by the water vapor | steam generated from the to-be-heated material M can take in the state which formed the packaging bag 1 with the pore formation film F1. Yes. The temperature of the water vapor generated from the article to be heated M changes depending on the atmospheric pressure (internal pressure) in the packaging bag 1, and how much the atmospheric pressure in the packaging bag 1 becomes to form the communication hole h (that is, the water vapor is generated). Whether or not to discharge is varied depending on how much the object to be heated M is heated. Therefore, the predetermined temperature changes according to the object to be heated M accommodated in the packaging bag 1, and when the object to be heated M is heated to a desired state, in other words, the water vapor in the packaging bag 1 is discharged. The temperature close to the temperature of the water vapor in the packaging bag 1 at the timing corresponds to the predetermined temperature described above. For example, if the temperature of the water vapor in the packaging bag 1 at the timing of discharging the water vapor in the packaging bag 1 is 100 ° C., the predetermined temperature is a temperature below 100 ° C. and a temperature close to 100 ° C. (for example, 90 ° C.). ~ 99 ℃).

The pore-forming film F1 may be a single layer or may have a plurality of layers.

(Cover film F2)
The cover film F2 is a film having a smaller extensibility and higher heat resistance than the pore-forming film F1 and the adhesive layer BL described later. The cover film F2 is not particularly limited as long as it has the above functions, and its material, manufacturing method, and the like are not limited. For example, a stretched film such as a biaxially stretched polypropylene, biaxially stretched polyester, or biaxially stretched polyamide film can be used as the cover film F2.

In addition, the cover film F2 should just have heat resistance of the grade which does not melt | dissolve in the temperature at which the pore formation film F1 is heat-sealed, or the temperature at which the adhesive layer BL and the pore formation film F1 are bonded. For example, if the material of the pore forming film F1 is a foamed polyethylene material and the material of the adhesive layer BL is a material containing a granular member and a low-melting polyethylene, a material that does not melt up to about 200 ° C. is formed on the cover film F2. Can be used as a material.

Further, the cover film F2 may be a single layer or may have a plurality of layers. If a plurality of layers are used, durability against external impacts and the like can be enhanced.

(Adhesive layer BL)
The adhesive layer BL is a layer containing a heat-adhesive resin, and has a function of connecting the pore forming film F1 and the cover film F2. That is, one surface of the adhesive layer BL is connected to the pore forming film F1, and even when the temperature is equal to or higher than the predetermined temperature described above, the connection portion with the pore forming film F1 is not released. It is strong. On the other hand, the other surface of the adhesive layer BL is connected to the cover film F2 with a predetermined laminated connection strength. For example, the other surface of the adhesive layer BL and the cover film F2 are connected so that the laminated connection strength is about 0.5 to 1.5 N / 15 mm when not heated.

Furthermore, the adhesive layer BL is adjusted so that a large number of communication holes h are formed when tension is applied along the surface direction in a state where the temperature is equal to or higher than the predetermined temperature described above. For example, the adhesive layer BL is adjusted so that the communication hole h is formed at substantially the same timing as the communication hole h is formed in the pore forming film F1. The adhesive layer BL having the above function can be formed, for example, by adding a granular member or a low-melting-point polyolefin resin to the adhesive layer BL, or by forming the adhesive layer BL as a foamed film.

The thermal adhesive resin contained in the adhesive layer BL has a biquad softening point of 40 ° C. or higher and lower than 100 ° C. By using the heat-adhesive resin having such a biquad softening point, the laminate connection strength and the peel-off portion connection strength between the adhesive layer BL and the cover film F2 can be easily changed from the adhesive layer BL to the cover film F2 at a temperature below room temperature. It can be maintained to the extent that it does not peel off. That is, the laminated connection strength between the adhesive layer BL and the cover film F2 is about 0.5 to 1.5 N / 15 mm, and the peeled portion connection strength between the adhesive layer BL and the cover film F2 is about 1.3 to 4.0 N / 15 mm. Can be maintained. Moreover, when the packaging bag 1 is heated and pressurized, the lamination connection strength and the peel-off portion connection strength between the adhesive layer BL and the cover film F2 so that the cover film F2 is peeled off from the adhesive layer BL at an appropriate timing. Can be reduced.

When the biquad softening point is less than 40 ° C., the lamination connection strength and the peeling portion connection strength between the adhesive layer BL and the cover film F2 become weak even at around room temperature. Therefore, during bag making processing, transportation, storage, etc. The cover film F2 may be peeled off from the adhesive layer BL. On the other hand, when the biquad softening point is 100 ° C. or higher, even if the packaging bag 1 is heated, there is a possibility that the lamination connection strength and the peeling portion connection strength between the adhesive layer BL and the cover film F2 are not weakened. Accordingly, the thermoadhesive resin contained in the adhesive layer BL preferably has a biquad softening point of 40 ° C. or higher and lower than 100 ° C., and more preferably has a biquad softening point of 50 ° C. or higher and 90 ° C. or lower.

As the heat-adhesive resin having a biquad softening point as described above, various adhesive resins such as modified polyolefin resins in which a polar group is graft-polymerized to polyolefin can be used. Examples include Modic (registered trademark) manufactured by Mitsubishi Chemical Corporation, Husabond (registered trademark) manufactured by DuPont, and Admer (registered trademark) manufactured by Mitsui Chemicals.

Particularly, in the adhesive layer BL, the weight ratio of the heat-adhesive resin to the total weight of the adhesive layer BL is 30 to 80% by weight, and the surface in contact with the cover film F2 is subjected to corona discharge treatment. It is preferable that the state is not performed. By doing so, the laminated connection strength with the cover film F2 at the time of non-heating is set to an appropriate strength that does not easily peel off during storage, that is, the laminated connection strength with the cover film F2 is 0.5 to 1.5 N / It can be 15 mm. Further, the peeled portion connection strength with the cover film F2 when the connecting portions 5 and 10 are heat-sealed is adjusted to 1.3 to 4.0 N / 15 mm, which does not peel off during bag making processing, transportation, storage, etc. It is possible to prevent the cover film F2 from being peeled off from the adhesive layer BL at the connecting portions 5 and 10.

When the surface of the adhesive layer BL that contacts the cover film F2 is subjected to corona discharge treatment, the surface energy becomes high, and the laminated connection strength between the cover film F2 and the adhesive layer BL is determined by the packaging bag 1 being heated and pressurized. Even when done, it will have a strong connection strength. That is, even when the packaging bag 1 is heated and pressurized, the cover film F2 is not peeled off from the adhesive layer BL. As a result, even when a certain temperature and tension are applied to the multilayer film F, the inner layer film 3 composed of the pore forming film F1 and the adhesive layer BL cannot be exposed. That is, even if the internal pressure in the packaging bag 1 is increased, a large number of communication holes cannot be formed in the pore forming film F1 and the adhesive layer BL. Then, if the internal pressure of the packaging bag 1 is increased and the internal pressure is further increased from the state where the packaging bag 1 is expanded, the packaging bag 1 is greatly ruptured.

On the other hand, when the surface of the adhesive layer BL that contacts the cover film F2 is not subjected to corona discharge treatment, and the ratio of the heat-adhesive resin contained in the adhesive layer BL is less than 30% by weight, the cover film F2 and The lamination connection strength and the peeling portion connection strength of the adhesive layer BL are weakened when not heated. Specifically, the laminate connection strength and the peeling portion connection strength of the cover film F2 and the adhesive layer BL are respectively weaker than 0.5 N / 15 mm and less than 1.3 N / 15 mm, and during the bag making process, The cover film F2 may be peeled off from the adhesive layer BL during transportation and storage.

Moreover, when the ratio of the heat-adhesive resin contained in the adhesive layer BL is more than 80% by weight, the slipping property of the adhesive layer BL is deteriorated, and the adhesive layer BL and the cover film F2 cannot be laminated. There is a fear.

In addition, the lamination | stacking connection strength and peeling part connection strength of the adhesive bond layer BL and the cover film F2 at the time of non-heating, and the lamination | stacking connection strength of the adhesive bond layer BL and the cover film F2 at the time of the non-heating when the packaging bag 1 is heated. The peeled portion connection strength varies depending on the weight ratio of the heat-adhesive resin contained in the adhesive layer BL. That is, if the weight ratio of the heat-adhesive resin contained in the adhesive layer BL is reduced, the laminate connection strength and the peel-off portion connection strength between the adhesive layer BL and the cover film F2 are weakened and contained in the adhesive layer BL. If the weight ratio of the heat-adhesive resin is increased, the lamination connection strength and the peel-off portion connection strength between the adhesive layer BL and the cover film F2 become stronger. Therefore, by adjusting the weight ratio of the heat-adhesive resin contained in the adhesive layer BL in accordance with the object to be heated M, the lamination connection strength and the peeling portion connection strength between the adhesive layer BL and the cover film F2 should be adjusted. For example, when the article to be heated M is appropriately heated and pressurized, and the temperature and pressure inside the packaging bag 1 are in an appropriate state, the adhesive layer BL and the cover film F2 can be peeled off. .

(About pore forming film F1 and adhesive layer BL)
Below, as above-mentioned, the conditions in case the pore formation film F1 and the adhesive bond layer BL are made into the film containing a granular member, the film containing a low melting-point polyolefin resin, and a foam film are demonstrated.

(Content of granular material)
The film including the granular member is formed of a resin and a granular member. That is, since the pore-forming film F1 and the adhesive layer BL formed of a film including a granular member are in a state where the granular member p exists in a resin serving as a base material (hereinafter referred to as the base material s), the granular member In the part located between p, the width | variety and thickness of the base material s are thin (refer FIG.4 (C)). For this reason, when a predetermined tension is applied to the pore-forming film F1 and the adhesive layer BL at a predetermined temperature or higher, the portion of the base material s where the width and thickness are thin is broken to form the granular member p. Since the accommodated space (corresponding to the void of the foamed film) is connected, a communication hole h penetrating the front and back is formed.

The material, shape, particle size, etc. of the granular member p to be contained in the pore forming film F1 and the adhesive layer BL are not particularly limited. What is necessary is just to adjust the raw material of the granular member p, a shape, and a particle size so that the communication hole h will be formed if predetermined tension is added to the pore formation film F1 and the adhesive bond layer BL above predetermined temperature.

For example, the material of the granular member p is not particularly limited as long as it has a higher melting point and lower deformability than the base material s. For example, examples of the granular member p include inorganic substances such as calcium carbonate, titanium oxide, talc, and magnesium carbonate, and organic substances such as cyclic olefin and polytetrafluoroethylene. If the granular member p formed of these substances is used, when a predetermined tension or higher is applied to the pore forming film F1 and the adhesive layer BL at a predetermined temperature or higher, the pore forming film F1 and the adhesive are bonded. The communication hole h can be reliably formed in the agent layer BL. In particular, when an inorganic material is used as the granular member p, deformation and alteration are less likely to occur compared to an organic material, so that the communication holes h can be reliably formed in the pore forming film F1 and the adhesive layer BL. .

Further, the shape and particle size of the granular member p are not particularly limited. For example, a granular member p having a spherical shape or a shape having irregularities on the surface can be used. Moreover, the particle size of the granular member p should just be small enough compared with the thickness of the pore formation film F1 and the adhesive bond layer BL. For example, if the thickness of the pore forming film F1 and the adhesive layer BL is t, the particle size d of the granular member p may be about t / d = 5 to 50. In addition, the particle diameter d here is the injection which measures the particle size by injecting the powder to be measured from the nozzle using compressed air, irradiating the powder dispersed in the air with laser light. It means the particle size measured by the mold dry measurement method.

Further, the amount of the granular member p mixed in the pore forming film F1 and the adhesive layer BL varies in an appropriate range depending on the material of the granular member p and the particle size thereof. Indicates. First, when the amount of the granular member p is reduced, the density of the granular member p in the base material s (in other words, the space in which the granular member p is accommodated) is reduced. It becomes difficult to form. On the other hand, when the amount of the granular member p is increased, the above-described communication hole h is easily formed, but it is difficult to stably manufacture the pore-forming film F1 and the adhesive layer BL. That is, when manufacturing the pore forming film F1 and the adhesive layer BL, the spreadability is lost, and problems such as the film being cut easily occur. Therefore, the amount of the granular member p mixed with the pore forming film F1 and the adhesive layer BL is appropriately determined in consideration of the formation, manufacture and handling of the communication holes h of the pore forming film F1 and the adhesive layer BL. Is set.

For example, in the pore-forming film F1, when an inorganic substance such as calcium carbonate having a particle size of t / d = 5 to 50 is used as the granular member p, the total weight of the base material s and the granular member p On the other hand, the amount of the granular member p is adjusted to 20 to 60% by weight, preferably 30 to 50% by weight. More specifically, when the pore forming film F1 is manufactured, the granular member p is 20 to 60% by weight with respect to the total weight of the resin and the granular member p as the raw material of the substrate s of the pore forming film F1. %, Preferably 30% to 50% by weight. When the granular member p is less than 20% by weight, a sufficient number of communication holes h cannot be formed, so that the water vapor cannot be discharged sufficiently and the packaging bag 1 may be ruptured. On the other hand, when the granular member p is more than 60% by weight, there is a problem that, when the pore-forming film F1 is manufactured, the extensibility is lost and the film is broken. Therefore, the amount of the granular member p is preferably 20 to 60% by weight and more preferably 30% to 50% by weight with respect to the total weight of the base material s and the granular member p in the pore forming film F1.

Similarly, when the inorganic material such as calcium carbonate having a particle diameter of t / d = 5 to 50 is used as the granular member p in the adhesive layer BL, the total weight of the base material s and the granular member p On the other hand, the amount of the granular member p is adjusted to 20 to 60% by weight, preferably 30% to 50% by weight. More specifically, when the adhesive layer BL is manufactured, the granular member p is 20 to 60% by weight with respect to the total weight of the resin and the granular member p, which are raw materials of the base material s of the adhesive layer BL, Preferably, it is blended so as to be 30% by weight to 50% by weight. When the granular member p is less than 20% by weight, a sufficient number of communication holes h cannot be formed, so that the water vapor cannot be discharged sufficiently and the packaging bag 1 may be ruptured. On the other hand, when the granular member p is more than 60% by weight, problems such as breakage of the film and breakage of the film occur when the adhesive layer BL is manufactured.

(Film containing low melting point polyolefin resin)
A plurality of polyolefin resins having different melting points may be mixed to form a material for the substrate s of the pore forming film F1 or the adhesive layer BL. In this case, there is an advantage that the communication hole h is easily formed as the content of the resin having a low melting point increases. For example, in the film including the granular member described above, the base material s may be formed of a polyolefin resin having a melting point of 100 ° C. or higher, and the polyolefin resin may contain a low melting point polyolefin resin having a melting point of less than 100 ° C. In this case, the low melting point polyolefin resin is finely dispersed in the polyolefin resin in the pore forming film F1 and the adhesive layer BL. If heat is applied to the pore-forming film F1 and the adhesive layer BL and a portion of 100 ° C. or higher is formed in the pore-forming film F1 and the adhesive layer BL, the low melting point polyolefin resin present in that portion. Is in a molten state. Then, since the part located between the granular members p becomes easy to fracture | rupture, the communicating hole h can be formed stably.

The mixing ratio of the low melting point polyolefin resin in the pore forming film F1 is not particularly limited. For example, the low melting point polyolefin resin is preferably blended so as to be 5 to 70% by weight, more preferably 5 to 45% by weight, based on the total weight of the pore-forming film F1. adjust. When the blending ratio of the low melting point polyolefin resin is higher than 70% by weight, the entire base material s of the pore-forming film F1 is easily melted when the article to be heated M is heated. There is a possibility that a large opening is formed in the material s. On the other hand, when the blending ratio of the low-melting-point polyolefin resin is less than 5% by weight, it is difficult to exert the effect that the communication hole h is easily formed when the low-melting-point polyolefin resin is added.

The mixing ratio of the low melting point polyolefin resin in the adhesive layer BL is not particularly limited. For example, the low melting point polyolefin resin is preferably blended so as to be 5 to 45% by weight, more preferably 5 to 40% by weight, based on the total weight of the adhesive layer BL. To do. When the blending ratio of the low melting point polyolefin resin is higher than 45% by weight, the entire base material s of the adhesive layer BL is easily melted when the article to be heated M is heated, and the base material s of the adhesive layer BL is easily melted. There is a possibility that a large opening may be formed. On the other hand, when the blending ratio of the low-melting-point polyolefin resin is less than 5% by weight, it is difficult to exert the effect that the communication hole h is easily formed when the low-melting-point polyolefin resin is added.

(Foam film)
The foam film is formed of resin and bubbles. That is, since the pore forming film F1 and the adhesive layer BL formed of the foam film are in a state where the gap b exists in the base material s (see FIG. 4B), in the portion between the gaps b. The width and thickness of the base material s are thin. For this reason, when a predetermined tension is applied to the pore forming film F1 and the adhesive layer BL at a predetermined temperature or higher, the portion of the base material s where the width and thickness are thin is broken and the gap b is connected. Therefore, the communication hole h which penetrates front and back is formed.

The method for forming the pore-forming film F1 and the adhesive layer BL is not particularly limited as long as the method can disperse the voids b in the base material s in an independent state. For example, an organic chemical foaming agent such as azodicarbonamide, an inorganic chemical foaming agent such as sodium hydrogen carbonate, a physical foaming agent comprising a gas such as nitrogen gas, a supercritical gas foaming comprising a gas in a supercritical state, etc. Can be used to manufacture the pore-forming film F1 and the adhesive layer BL dispersed in the base material s so that the voids b having a desired size have a desired density.

In this case, it is preferable to adjust so that the expansion ratio of the pore-forming film F1 is 1.1 to 2.5 times. When the expansion ratio is larger than 2.5, pinholes are likely to be generated on the film surface during film formation, and it becomes difficult to maintain airtightness and liquid tightness. On the other hand, if the expansion ratio is lower than 1.1 times, the density of the voids b in the base material s becomes small, and a sufficient number of communication holes h between the voids b cannot be formed, so that water vapor cannot be discharged sufficiently. The packaging bag 1 may burst. Accordingly, the expansion ratio of the pore-forming film F1 is preferably 1.1 to 2.5 times, and more preferably 1.2 to 2.0 times.

Further, it is preferable to adjust the foaming ratio of the adhesive layer BL to 1.1 to 2.5 times. When the expansion ratio is larger than 2.5, pinholes are likely to be generated on the film surface during film formation, and it becomes difficult to maintain airtightness and liquid tightness. On the other hand, if the expansion ratio is lower than 1.1 times, the density of the voids b in the base material s becomes small, and a sufficient number of communication holes h between the voids b cannot be formed, so that water vapor cannot be discharged sufficiently. The packaging bag 1 may burst. Accordingly, the expansion ratio of the adhesive layer BL is preferably 1.1 to 2.5 times, and more preferably 1.2 to 2.0 times.

(Lamination of film containing granular material and foam film)
The pore-forming film F1 and the adhesive layer BL may be a film including the above-described granular member, a film including a low-melting-point polyolefin resin, or a single-layer film formed only from a foam film. Moreover, it is good also as a laminated | multilayer film which laminated | stacked these films. In particular, when the laminated film includes a foamed film, the foamed layer (that is, the foamed film) functions as a heat insulating layer, so that the heat insulation of the package 1 can be improved.

(Size of communication hole h)
The size (hole diameter) of the communication hole h formed in the pore-forming film F1 and the adhesive layer BL is not particularly limited. However, when the tension is removed, an object to be heated such as a liquid is not easily passed. Size is preferred. For example, in a state where tension is applied to the pore forming film F1 and the adhesive layer BL, if the opening diameter of the communication hole h on the surface is about 30 μm or less, the liquid passes in the state where the tension is removed. It becomes difficult.

(Experiment related to pore-forming film)
First, it confirmed that it became a pore formation film by putting a granular member in the base material of a film. That is, it was confirmed that by inserting a granular member into the base material of the film, communication holes can be appropriately formed in the film when a certain temperature or tension is applied to the film.

In the experiment, a pillow packaging bag (100 mm × 100 mm) was produced using a film containing a granular member, and 20 g of water was sealed inside and heated in a microwave oven (500 W). And it was confirmed whether the package could be prevented from bursting.

The film was formed by mixing a granular member with the following resin.
In addition, the following were used for the granular member.
(Granular material used)
80 wt% calcium carbonate MB (20 wt% LLDPE + 80 wt% calcium carbonate, calcium carbonate average particle size: 2.0 μm, MFR of carrier resin LLDPE (190 ° C., 2.16 kg): 8.0 g / 10 min))

(1) Polyolefin resin 1
Ethylene / propylene block copolymer (block PP), MFR (230 ° C., 2.16 kg): 1.2 g / 10 min, density: 0.900 g / cm ³ , melting point: 163 ° C.
(2) Polyolefin resin 2
α-olefin copolymer linear high density polyethylene (HDPE), MFR (190 ° C., 2.16 kg): 0.8 g / 10 min, density: 0.956 g / cm ³ , melting point: 135 ° C.
(3) Polyolefin resin 3
α-olefin copolymer linear low density polyethylene (LLDPE), MFR (190 ° C., 2.16 kg): 0.9 g / 10 min, density: 0.924 g / cm ³ , melting point: 123 ° C.
(4) Polyolefin resin 4
α-olefin copolymer linear low density polyethylene (LLDPE), MFR (190 ° C., 2.16 kg): 4.0 g / 10 min, density: 0.886 g / cm ³ , melting point: 70 ° C.

The results are shown in Table 1 (see FIG. 5).
As shown in Table 1, it was confirmed that if the addition ratio of 80 wt% calcium carbonate MB is less than 80%, it can be formed as a film regardless of the melting point of the resin.
On the other hand, when the melting point of the resin is different, it can be understood that the addition rate of 80 wt% calcium carbonate MB that can prevent the film from bursting when the temperature and tension above a certain level are applied to the film is different.

In other words, the lower the melting point, the lower the addition rate of 80% by weight calcium carbonate MB, the more effective that the film can be prevented from bursting when a certain temperature and tension are applied to the film. It was confirmed that a communication hole can be formed.

Next, it was confirmed whether even a granular member other than calcium carbonate can obtain the same burst prevention effect when a certain temperature or tension is applied to the film.

In the experiment, 70 wt% talc MB (30 wt% LDPE + 70 wt% talc, talc average particle size: 3.5 μm, carrier resin LDPE MFR (190 ° C., 2.16 kg) was added to the polyolefin resin 3 in the following proportions: 4.0 g / 10 min) and a cyclic olefin copolymer (MVR (260 ° C., 2.16 kg): 32.0 ml / 10 min, density: 1.010 g / cm ³ , glass transition temperature: 78 ° C.)) The above pillow packaging bag was formed, and 20 g of water was sealed inside and heated in a microwave oven (500 W). And it was confirmed whether the package could be prevented from bursting.

(1) Experiment 1
1) Polyolefin resin 3: 70% by weight
2) 70% by weight Talc MB: 30% by weight
(2) Experiment 2
1) Polyolefin resin 3: 40% by weight
2) Cyclic olefin copolymer: 60% by weight

In either case, it was confirmed that the film can be prevented from bursting when a certain temperature or tension is applied to the film. That is, it was confirmed that not only calcium carbonate but also talc and cyclic olefin copolymer can prevent the film from bursting when a certain temperature or tension is applied to the film.

It was confirmed whether or not it becomes easier to form communication holes in the film by adding a polyolefin resin having a melting point of less than 100 ° C. to the base material of the film.

In the experiment, in Example 1, when a certain temperature and tension were applied to the film, the film could not be prevented from bursting (addition rate of polyolefin resin 3 80% by weight, addition rate of 80% by weight calcium carbonate MB) 20% by weight), when the polyolefin resin 3 was mixed with the polyolefin resin 3, it was confirmed whether or not the film could be prevented from bursting when a certain temperature and tension were applied to the film.

When the polyolefin resin 3 was 65% by weight, the polyolefin resin 4 was 15% by weight, and 80% by weight calcium carbonate MB was 20% by weight, communication holes were formed in the film, and a certain temperature and tension were applied to the film. At that time, it was confirmed that the film could be prevented from bursting. *

That is, it was confirmed that by using a resin having a low melting point (100 ° C. or lower), even if the addition amount of 80 wt% calcium carbonate MB is reduced, communication holes are easily formed and bursting can be prevented.

By making a laminated film in which a foamed film and a film including a granular member are laminated, a certain temperature and tension are applied to the film, and when the communication hole is formed in the film, the expansion state of the film is confirmed. .

In the experiment, the following laminated film was produced, and a pillow packaging bag (Example 3) was formed in the same manner as in Example 1. The expansion situation in the microwave oven of this package was compared with the expansion situation in the microwave oven of the pillow packaging bag formed with the single layer film containing a granular member.

Laminated film (1) Film including granular member: thickness 40 μm
1) Polyolefin resin 3: 60% by weight
2) 80% by weight calcium carbonate: 40% by weight
(2) Foam film: thickness 100 μm
Polyethylene foam (Manufacturer: Nissei Chemicals, Product name: HC-10)
(3) Adhesive:
Ester adhesive for dry lamination (Manufacturer: Rock Paint, product name: RU-77T)

As a result, in the pillow packaging bag formed of a laminated film in which a foam film and a film including a granular member are laminated, the height of the packaging bag in the microwave oven was 73 mm.
On the other hand, in the pillow packaging bag formed of a single layer film including a granular member, the height of the packaging bag in the microwave oven was 87 mm.

In other words, the pillow packaging bag formed of a laminated film in which a foam film and a film including a granular member are laminated has a smaller bulge than a pillow packaging bag formed of a single layer film including a granular member. confirmed.

When the frozen food was encapsulated using the multilayer film of the present invention, it was confirmed whether the heating state could be properly determined based on the appearance of the packaging bag.

In the experiment, commercially available frozen noodles were enclosed in a pillow packaging bag formed by the multilayer film of the present invention, that is, a multilayer film having a three-layer structure of a pore-forming film, an adhesive layer, and a cover film, and thereafter The one frozen overnight in a freezer (hereinafter referred to as “repacked udon”) was used.

In the experiment, when the above repackaged udon was cooked in a microwave oven for the cooking time specified by the food manufacturer (Comparative Example 1), the cover film of the outer layer film was peeled off from the inner layer film of the pore forming film and the adhesive layer. About the udon (Example 4) cooked with the microwave oven, the heating condition of the contents (udon) was confirmed.
In Example 4, it was heated until the cover film of the outer layer film peeled off from the inner layer film of the pore forming film and the adhesive layer, and the pore forming film and the inner layer film of the adhesive layer were exposed. Cooking was carried out.

The multilayer film of the present invention used for packaging was laminated by laminating the following inner layer film (total thickness 100 μm) and a biaxially stretched polyester film (O-PET) (thickness 30 μm) cover film with an adhesive. Multi-layer film.

(1) Inner layer film: Total thickness 100 μm
The inner layer film is obtained by laminating the following (a) pore-forming film and (b) an adhesive layer by coextrusion.

(A) Pore-forming film (foamed polyethylene having a foaming ratio of 2.0 times): thickness 70 μm
・ Tubular long-chain branched low density polyethylene (LDPE): 55% by weight added
MFR (190 ° C., 2.16 kg): 0.25 g / 10 min, density: 0.922 g / cm ³ , melting point: 111 ° C.
Α-olefin copolymer linear low density polyethylene (LLDPE): 42 wt% added
MFR (190 ° C., 2.16 kg): 0.9 g / 10 min, density: 0.924 g / cm ³ , melting point: 123 ° C.
・ Azodicarbonamide foaming agent MB: 3% by weight added
Carrier resin: LLDPE, decomposition peak temperature: 200 ° C., amount of decomposition gas: 150 ml / g

(A) Adhesive layer (the surface of the outer layer film in contact with the cover film is not subjected to corona discharge treatment): thickness 30 μm
80% by weight calcium carbonate MB (granular material): 29% by weight added
20 wt% LLDPE + 80 wt% calcium carbonate MB, calcium carbonate average particle size: 2.0 μ, carrier resin LLDPE MFR (190 ° C., 2.16 kg): 8.0 g / 10 min)
Α-olefin copolymer linear low density polyethylene (LLDPE): 33% by weight added
MFR (190 ° C., 2.16 kg): 4.0 g / 10 min, density: 0.886 g / cm ³ , melting point: 70 ° C.
・ Adhesive resin: 38% by weight added
Maleic anhydride graft copolymer, MFR (190 ° C., 21.2 N): 1.0 g / 10 min, density: 0.910 g / cm ³ , melting point: 70 ° C.

(2) Outer film (the surface of the inner film in contact with the adhesive layer is subjected to corona discharge treatment): thickness 12 μm
Biaxially stretched polyester film (O-PET) (Manufacturer name: Toyobo Co., Ltd., product name: E5102)

(3) Ester adhesive for adhesive dry lamination (Manufacturer: Rock Paint, product name: RU-77T)

In addition, the lamination | stacking connection intensity | strength (lamination | strength) of the adhesive film in the inner layer film of the multilayer film of this invention and the cover film in an outer layer film is 0.88N / 15mm, The adhesive layer in an inner layer film, and the cover film in an outer layer film The peeling part connection strength (heat seal strength) of the connection part is 2.60 N / 15 mm.

The laminate strength was measured by a known test method (JIS K 6854-3). The heat seal strength was measured by a known test method (JIS Z 0238).

The results are shown in Table 2 (see FIG. 6).
As shown in Table 2, in Comparative Example 1 cooked in the microwave for the cooking time specified by the food manufacturer, the cover film of the outer film did not peel from the adhesive layer of the inner film, and the temperature of the udon did not rise sufficiently Was confirmed.

On the other hand, in Example 4 in which microwave cooking was performed until the cover film of the outer film peeled from the adhesive layer of the inner film, it was confirmed that the temperature of the whole udon was sufficiently increased.

In other words, if a pillow packaging bag is formed with the multilayer film of the present invention, the processed food or frozen food to be heated can be obtained by checking whether or not the cover film of the outer film has peeled from the adhesive layer of the inner film. It was confirmed that it was easy to grasp that it was heated to an appropriate state (the most delicious state).

The packaging bag of the present invention is suitable as a packaging bag for containing foods heated in a microwave oven such as processed foods and frozen foods.

DESCRIPTION OF SYMBOLS 1 Packaging bag 1h Storage space 3 Inner layer film 4 Outer layer film 5 Connection part 10 Connection part F Multilayer film F1 Pore formation film F2 Cover film M To-be-heated BL Adhesive layer s Base material b Bubble (foaming)
p Granular material h Communication hole

Claims (9)

1. A packaging bag capable of heating an object to be heated in a state in which the object to be heated is accommodated in an internal storage space,
   The packaging bag
   An inner layer film located inside having a pore-forming film and an adhesive layer provided on the outer side of the pore-forming film, and a cover film having a lower extensibility and higher heat resistance than the inner layer film, An outer layer film located outside the inner layer film, and is formed by a multilayer film,
   The inner layer film is
   When tension is applied at a temperature above a certain level, a large number of communication holes that penetrate the front and back are formed.
   The adhesive layer contains a thermal adhesive resin,
   It has a connecting portion having an inner surface connecting portion that connects the inner surfaces of the pore-forming film in the inner layer film,
   The connection strength between the outer layer film and the adhesive layer at the connection portion is weaker than the inner surface connection strength between the inner surfaces of the pore forming films of the inner layer film at the inner surface connection portion. A packaging bag characterized by being stronger than the lamination connection strength of the outer layer film and the adhesive layer.
2. Thermal adhesive resin contained in the adhesive layer in the inner layer film,
   The packaging bag according to claim 1, wherein the biquad softening point is 40 ° C or higher and lower than 100 ° C.
3. The packaging bag according to claim 1 or 2, wherein the weight ratio of the heat-adhesive resin to the total weight of the adhesive layer in the inner layer film is 30 to 80% by weight.
4. 4. The packaging bag according to claim 1, wherein the surface of the adhesive layer in the inner layer film that is in contact with the outer layer film is a surface that is not subjected to corona discharge treatment.
5. The packaging bag according to any one of claims 1 to 4, wherein a lamination connection strength between the adhesive layer and the outer layer film when not heated is 0.5 to 1.5 N / 15 mm.
6. The packaging bag according to any one of claims 1 to 5, wherein the peel-off portion connection strength between the adhesive layer and the outer layer film when not heated is 1.3 to 4.0 N / 15 mm.
7. The pore-forming film and the adhesive layer in the inner layer film contain a granular member,
   The weight ratio of the granular member to the total weight of the pore-forming film is 20 to 60% by weight,
   The packaging bag according to any one of claims 1 to 6, wherein the weight ratio of the granular member to the total weight of the adhesive layer is 20 to 60% by weight.
8. The pore-forming film and the adhesive layer in the inner layer film are
   A low melting point polyolefin resin having a melting point of less than 100 ° C.,
   The weight ratio of the low melting point polyolefin resin to the total weight of the pore-forming film is 5 to 70% by weight,
   The packaging bag according to any one of claims 1 to 7, wherein a weight ratio of the low-melting-point polyolefin resin to a total weight of the adhesive layer is 5 to 45% by weight.
9. The packaging bag according to any one of claims 1 to 6, wherein an expansion ratio of the pore forming film and the adhesive layer in the inner layer film is 1.1 to 2.5 times.
   
   

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