JP5975050B2 - Packaging material - Google Patents

Description

  The present invention relates to a packaging material for obtaining a package in which food solids are vacuum-filled.

  Among food solids, for example, frozen hamburgers are packaged by storing hamburgers as solids in the packaging material and then sealing the packaging material in a vacuum state, that is, vacuum packaging. The package is then frozen by chilled hamburger as a solid food product, shipped in the frozen state, and sold through a distribution process. The vacuum packaging is a packaging form that is often used conventionally since it can maintain the freshness of the filling. However, when such a vacuum-packed package is chilled by refrigeration, the inside of the package is reduced in volume during vacuum packaging, so that the filling and the packaging material come into contact with each other, and are frozen in that state. As a result of rapid cooling of the inner material, condensation occurs on the surface of the packaging material, and a large amount of frost is generated. Moreover, frost may adhere not only at the time of manufacture of a chilled package but in the process of distribution of a package.

  When frost adheres to the surface of the package, it is difficult to visually recognize the display of the contents or the like attached to the surface of the packaging material of the package during the distribution and sale of the package. In this case, the function of displaying the contents of the packaging material cannot be sufficiently achieved.

  It has excellent transparency, and can be made into a film that does not crush food when pressure is applied to the food. It is disclosed that a container capable of range heating is a package that is vacuum-packed with a transparent water-impermeable film that is covered in close contact, and this transparent film is a laminated film containing an ionomer resin (patent) Reference 1).

JP 2006-327658 A

  However, the generation of frost in the rapidly cooled vacuum package could not be sufficiently prevented only by using a specific laminated film as the film constituting the packaging material as described above.

  The present invention advantageously solves the above-mentioned problem, and in the case of obtaining a vacuum package, the packaging material printed during rapid cooling of the inclusions during chilling or during the circulation of the package It is an object of the present invention to provide a packaging material that can suppress frost from adhering to the surface and thus ensure the visibility of the printed display on the surface of the packaging material.

The packaging material of the present invention that advantageously solves the above problems includes an inner bag that contains frozen food or chilled food as an inner filling, and an outer bag that covers the inner bag and is joined to the inner bag. The inner bag comprises a laminate having at least a base layer and a heat seal layer and no barrier layer, and an air passage is formed in a part of a portion where the inner bag and the outer bag are joined, The air passage is 20% to 60% with respect to the entire length of the joined portion, and the air bag communicates with the atmosphere through the air passage.

In the packaging material of the present invention, the filling material contained in the inner bag is a hamburger or similar frozen food or chilled food.
Further, the inner bag can be a three-sided bag or a pillow-type bag in which edges of two laminated bodies having at least a base layer and a heat seal layer are joined.
Furthermore, it is preferable that the junction part of this inner bag and an outer bag is an edge part of an inner bag and an outer bag.
Furthermore, it is preferable that the air passage is a partial unjoined portion at a joint portion between the inner bag and the outer bag.

  According to the packaging material of the present invention, an air passage is formed in a part of the joint portion between the inner bag and the outer bag in the double bag composed of the inner bag and the outer bag, and between the inner bag and the outer bag. Since the inner bag communicates with the atmosphere, the inner bag surface is condensed due to freezing of the inner filling, and even if frost is generated, the surface of the inner bag where the frost is generated and the outer bag on which printing is performed Since it is separated from frost, frost is not generated and attached to the outer bag. For this reason, the visibility of the printed display on the surface of the packaging material can be maintained.

It is a perspective view of the packaging material of one Embodiment of this invention. It is a perspective view of the packaging material of another embodiment of this invention. It is typical sectional drawing of the laminated body which comprises the inner bag of the packaging material of one Embodiment of this invention. It is typical sectional drawing explaining the junction part of the packaging material of one Embodiment of this invention.

  Hereinafter, an embodiment of the packaging material of the present invention will be specifically described with reference to the drawings.

  In the perspective view shown in FIG. 1, the packaging material 1 is a double bag including an inner bag 11 and an outer bag 12 having a rectangular plane. In the inner bag 11, an embedded material such as a hamburger is accommodated. On the surface of the outer bag 12, it is possible to print and display the contents of the inner material accommodated in the inner bag 11. The outer bag 12 has the same size as the inner bag 11 and is joined at three sides of the inner bag 11. An air passage 1p is formed in a part of the joint 1s between the inner bag 11 and the outer bag 12. In the illustrated example, a plurality of air passages 1 p are formed in each of the side edges of the packaging material 1. Between the inner bag 11 and the outer bag 12 is communicated with air through the air passage 1p.

  As described above, the air passage 1p is formed in a part of the joint 1s between the inner bag 11 and the outer bag 12, so that the atmosphere communicates between the inner bag 11 and the outer bag 12. . Thereby, even if the surface of the inner bag 11 is condensed due to the freezing of the filling material housed in the inner bag 11 and vacuum-packed, and the frost is generated, the surface of the inner bag 11 where the frost is generated and the printing Since the outer bag 12 is separated from the outer bag 12, frost is not generated and attached to the outer bag 12. For this reason, the visibility of the printed display attached | subjected to the surface of the outer bag 12 which comprises the packaging material 1 can be maintained.

  The packaging material 1 according to the present embodiment is particularly effective for the filling material accommodated in the inner bag 11 that is vacuum-packed and frozen in the inner bag 11, particularly for hamburgers.

  In the packaging material of FIG. 1, the inner bag 11 is a three-sided bag formed by heat-sealing the edges of the two laminated bodies 11A and 11B. The inner bag 11 is a three-sided bag in which two films of the laminates 11A and 11B are joined at the respective edges, thereby producing a packaging material 1 that can contain an inner filling of a hamburger-sized food. It can be manufactured with good performance. However, the packaging material of the present invention is not limited to a three-sided bag.

  Each of the stacked body 11A and the stacked body 11B includes a base layer 11a and a heat seal layer 11b. Since the laminated body 11A and the laminated body 11B have the heat seal layer 11b, the inner bag 11 can be manufactured by joining the laminated body 11A and the laminated body 11B by heat fusion. Good. These laminated bodies 11A and 11B are superposed such that both surfaces facing each other are the heat seal layer 11b, and the three sides of the laminated body 11A and 11B are heat-sealed by heating and pressing the edges of the superposed three sides. The inner bag 11 is used.

  Specific examples of the base layer 11a and the heat seal 11b constituting the inner bag laminate 11A and laminate 11B include, for example, [polyamide resin / polyamide resin / heat seal resin] and [polyester resin / polyamide resin]. As long as the film on the side in contact with the embedded material is formed of a heat-sealable resin layer, such as a combination of / heat-sealable resin], and can be formed as a sealed bag, the configuration is It doesn't matter. The thicknesses of the laminated body 11A and the laminated body 11B may have a thickness that is usually used for vacuum packaging and chilled packaging of an embedded material such as a hamburger.

  Moreover, it can also be set as a laminated body by joining the base layer 11a and the heat seal layer 11b with an adhesive agent. The following structures are mentioned as a typical structural example of the laminated | multilayer film which can be used preferably. However, it is not limited to these configurations, and various combinations of laminated films can be used. In the following, the ON film is a biaxially stretched nylon film, the OPP film is a biaxially stretched polypropylene film, the PET film is a biaxially stretched polyethylene terephthalate film, and L / LDPE is a linear low density polyethylene. HDPE refers to high density polyethylene, LDPE refers to low density polyethylene, CPP film refers to cast (unstretched) polypropylene film, and EVOH film refers to saponified ethylene-vinyl acetate copolymer film.

(1) ON film / adhesive / L / LDPE film (sealant layer)
(2) ON film / adhesive / PET film / adhesive / L / LDPE film (sealant layer)
(3) ON film / adhesive / PET film / adhesive / CPP film (sealant layer)
(4) ON film / adhesive / biaxially stretched HDPE film / adhesive / L / LDPE film (sealant layer)
(5) ON film / adhesive / OPP film / adhesive / L / LDPE film (sealant layer)
(6) ON film (silica or alumina deposited layer) / adhesive / biaxially stretched HDPE film / adhesive / L / LDPE film (sealant layer)
(7) ON film / anchor coat layer / co-extrusion coat layer (HDPE) layer / L / LDPE layer) (sealant layer is L / LDPE layer)
(8) ON film / anchor coat layer / co-extrusion coat layer (HDPE layer / LDPE layer) / adhesive / L / LDPE film (sealant layer)
(9) PET film / adhesive / L / LDPE film (sealant layer)
(10) PET film / adhesive / ON film / adhesive / L / LDPE film (sealant layer)
(11) PET film / adhesive / (silica or alumina deposited layer) ON film / adhesive / L / LDPE film (sealant layer)
(12) PET film / adhesive / ON film / adhesive / CPP film (sealant layer)
(13) PET film / adhesive / EVOH film / adhesive / ON film / adhesive / CPP film (sealant layer)

  In the above, the anchor coat is a kind of primer coat which is pre-coated on the base film side in order to improve the adhesiveness when the resin is laminated by extrusion coating.

  In the above, the L / LDPE film and the CPP film of the sealant layer can be replaced with an ethylene / α-olefin copolymer polymerized using a single site catalyst. As described above, these sealant layers can be laminated by an extrusion coating method or the like in addition to pasting a film formed in advance using an adhesive by a dry lamination method or the like.

  In the configuration of the laminated film, the ON film and the PET film, when used for the outermost layer, impart mechanical strength and printability to the food bag as the base film, and when used for the intermediate layer, are mainly mechanical. Used to reinforce mechanical strength. In addition, the biaxially stretched HDPE film and OPP film used for the intermediate layer are used for increasing the thickness and rigidity, and at the same time improving the moisture permeability. The biaxially stretched HDPE film and OPP film can also be a uniaxially stretched HDPE film and a uniaxially stretched PP film. In that case, by laminating so that the stretch direction matches the direction of the cut line of the bag. , Tearing can be facilitated and the directionality can be stabilized. However, it is preferable to use a biaxially stretched film when the cut line of the bag is in both the vertical and horizontal directions of the bag.

  The silica or alumina vapor deposition layer and the EVOH film are laminated to improve the gas barrier property. Besides these, a gas barrier material such as a polyacrylonitrile film or a coating layer of polyvinylidene chloride is used. It can also be laminated.

  As the sealant layer, three examples of L / LDPE film, CPP film, and ethylene / α-olefin copolymer polymerized using a single site catalyst were given. It is excellent in stability, content resistance, stress cracking resistance, etc., and the CPP film is excellent in heat resistance and low odor. In addition, ethylene / α-olefin copolymers polymerized using single-site catalysts such as metallocene catalysts have a narrow molecular weight distribution and a stable copolymerization ratio. In addition to excellent properties, it is particularly excellent in low odor. Therefore, by selecting and using the optimum product according to the type of packaging (food) to be packaged and usage conditions, the flavor of the content is not impaired by resin odor, etc., and it is safe and has excellent performance. A food bag can be provided.

  In addition to the above, the sealant layer also contains ordinary low-density polyethylene such as high-pressure polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic acid ester copolymer, ionomer, and polyester resin. It can be appropriately selected and used.

  Moreover, the laminated body 11A and the laminated body 11B of the inner bag are not limited to the example in which the layer configuration is the same laminated body. That is, the laminated body 11A and the laminated body 11B may have different types of base layers 11a and / or heat seal layers 11b.

  The outer bag 12 is formed so as to cover the inner bag 12. This outer bag is formed by joining the edges of two films 12A and 12B to the inner bag 11. These films 12A and 12B can be made of, for example, a polyester resin or a polyamide resin. These films are films that can be printed and decorated by reverse printing. Each of the film 12A and the film 12B may be a laminate including a plurality of film layers. The thickness of the outer bag 12 is not particularly limited as long as it has a thickness usually used for printing display.

  The film 12 </ b> A and the film 12 </ b> B of the outer bag 12 are made the outer bag 12 by overlapping the surfaces of the laminated bodies 11 </ b> A and 11 </ b> B of the inner bag 11 and joining the edges thereof. The joining of the edge portions can be performed by adhering to each other with, for example, a dry laminate adhesive. At this time, the air passage 1p can be easily formed by partially bonding the joint portion between the inner bag 11 and the outer bag 12.

  The heat-sealable resin used in the laminate constituting the packaging material 1 may be any resin that can be melted by heat and fused to each other. For example, as a thermoplastic resin, low-density polyethylene, medium-density polyethylene, high-density Polyethylene, linear (linear) low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer , Ethylene-propylene copolymer, methylpentene polymer, acid-modified polyolefin resin obtained by modifying polyolefin resin such as polyethylene or polypropylene with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, other unsaturated carboxylic acid, etc. Resin consisting of one or more of these resins It can be used in the form of Lum or sheet.

  The joint 1s between the inner bag 11 and the outer bag 12 is preferably the edge of both. When the inner bag 11 is a three-sided bag, it is reasonable to join the outer bag 12 at the edge of the inner bag 11 because the heat-sealed portion of the inner bag 11 is a three-sided edge. But the junction part of the inner bag 11 and the outer bag 12 is not limited to both edge parts.

  In order to form the air passage 1p in the joint portion 1s, for example, in the joint portion 1s between the inner bag 11 and the outer bag 12, an unjoined portion can be partially formed. If an unjoined part is partially formed at the time of joining, this unjoined part serves as air passage 1p of packaging material 1. For example, when the inner bag 11 and the outer bag 12 are bonded to each other using, for example, a dry laminate adhesive, the unbonded portion is partially applied to the edge of the inner bag 11 and / or the outer bag 12. Apply to. If it does so, since the inner bag 11 and the outer bag 12 do not adhere | attach in the part which did not apply | coat an adhesive agent, the part becomes an unjoined part.

  Further, when the inner bag 11 and the outer bag 12 are joined by heat fusion using a heat seal layer, a portion where the heat seal layer is not formed at the joint portion between the inner bag 11 and the outer bag 12. By partially forming the air passage 1p, the air passage 1p can be formed in the joint 1s.

  The air passage 1p communicates with the atmosphere between the inner bag 11 and the outer bag 12 to prevent frost from adhering to the printed display formed on the outer bag 12, and as much air as possible in the joint portion. It is preferable to enlarge the portion of the passage 1p so that the above-described communication with the atmosphere is in good condition. Therefore, considering the bonding strength between the inner bag 11 and the outer bag 12, etc., at a predetermined ratio, for example, a ratio of 20% (20%) to 60% (60%) with respect to the entire length of the bonded portion. What is necessary is just to form in a junction part. More preferably, it is more than 40% (40%).

  Another embodiment of the packaging material of this invention is demonstrated using the perspective view of FIG. The packaging material 2 shown in FIG. 2 is an example of a pillow-type bag, and includes an inner bag 21 that contains an inner filling material and an outer bag 22 that is made of a plastic film that has been subjected to cosmetic processing such as letters and figures. In addition, although the inner bag 21 and the outer bag 22 can each be formed with a lamination sheet, in FIG. 2, it has shown with one sheet | seat for convenience.

  And these inner bag 21 and outer bag 22 are joined in each outer edge part. In the example shown in the figure, the inner bag 21 and the outer bag are bonded by heat bonding at the upper seal portion 2st, the lower seal portion 2sb, and the back seal portion 2sc as joint portions at the top, bottom, and back of the packaging material 2. 22 are bonded to each other, and the inner space of the inner bag 21 is further sealed. A packaging body is obtained by using the packaging material 2 made of such a double bag and filling an inner filling such as a hamburger and then thermally bonding the upper seal portion 2st.

  As a material of the inner bag 21 and the outer bag 22, the same material as the material used for the packaging material 1 shown in FIG. 1 can be used.

  Moreover, the seal part formed in each outer side part of the inner bag 21 and the outer bag 22 forms a heat seal layer in an adhesive surface beforehand, or is performed by dry lamination or the like. As this heat seal layer, low-density polyethylene, polypropylene, and an ethylene-vinyl acetate copolymer can be used in the same manner as the resin layer for sealant described above.

  In the present embodiment, by forming partial unjoined portions at several positions on the thermal bonding portions of the outer side portions of the inner bag and the outer bag in the back seal portion 2sc, In the part, a plurality of air passages 2p are formed for ensuring air circulation in the space between the inner bag 21 and the outer bag 22. It is sufficient for the air flow passage 2p to be about 20% to 60%, more preferably more than 40% of the length of the back seal portion 2sc as the air passage 2p.

  The air flow passage 2p does not form a heat seal layer for bonding the inner bag 21 and the outer bag 22 in a portion corresponding to the air passage 2p, or does not place an adhesive for dry lamination. As a result, an air passage 2p is formed in the back seal portion 2sc.

  The air communicates between the inner bag 21 and the outer bag 22 by the air passage 2p. Thereby, even if the surface of the inner bag 21 is condensed due to the freezing of the filling material contained in the inner bag 21 and vacuum-packed, and the frost is generated, the surface of the inner bag 21 where the frost is generated and the printing Since the outer bag 22 is separated from the outer bag 22, frost is not generated and attached to the outer bag 22. For this reason, the visibility of the printed display attached | subjected to the surface of the outer bag 22 which comprises the packaging material 2 can be maintained.

  Next, the method for producing the packaging material of the present invention will be described with reference to the example of the three-sided bag shown in FIG.

  As shown in FIG. 3, a schematic cross-sectional view of the laminated body constituting the inner bag 11 of the packaging material 1 of the present embodiment, a laminated body 11 </ b> A for the inner bag 11 and a laminated body 11 </ b> B are prepared. These laminates are not limited to short pieces for manufacturing the packaging material 1 in a batch type, but may be long ones for manufacturing the packaging material 1 in a continuous type.

  These laminated body 11A and laminated body 11B are obtained by stacking the base layer 11a and the heat seal layer 11b and bonding them together. For this bonding, for example, a dry laminate adhesive b can be used.

  The obtained laminated body 11A and laminated body 11B are overlaid so that the respective heat seals 11b face each other. The edges of the laminated body 11A and the laminated body 11B for the inner bag 11 are heated with a heater and pressed in the thickness direction to heat-fuse them, and then the heat-fused part is cooled. Cool in a vessel and solidify. The inner bag 11 of a three-sided bag can be obtained by performing this heat fusion at the edges of the three sides of the stacked laminate. When the laminated bodies 11A and 11B are long objects unwound from the rolls, the heater and the cooler for heat fusion are parallel to the traveling direction of the laminated bodies and the direction perpendicular thereto. Thus, a large number of packaging materials can be continuously produced as the laminate progresses.

  Separately from the production of the inner bag 11, films 12A and 12B for the outer bag 12 are prepared. The film 12A and / or 12B is subjected to decorative printing by back printing.

  These films 12 </ b> A and 12 </ b> B are overlapped on the surfaces of the laminated bodies 11 </ b> A and 11 </ b> B constituting the inner bag 11, respectively, to form a joint 1 s. FIG. 4 shows a schematic cross section of the joint 1s. A dry laminate adhesive b is used for joining the films 12A and 12B. Moreover, joining is joined to the three sides of the inner bag 11 and the three sides of the outer bag 12 as shown in FIG. At the time of this bonding, the dry laminate adhesive is not partially applied at the bonding portion 1 s formed on the three edges of the packaging material 1. Thereby, an unjoined part is formed in joined part 1s. This unjoined portion becomes the air passage 1p.

  The method for forming the unjoined portion described above is not limited to the case where a dry laminate adhesive is used for joining the inner bag 11 and the outer bag 12. For example, a heat seal layer can be used for joining the inner bag 11 and the outer bag 12. In this case, an unjoined part is formed by not providing the heat seal layer partially at the joined part, and this unjoined part becomes the air passage 1p.

  Next, the packaging material of the present invention will be described more specifically with reference to examples.

Example 1
[Production of film for outer bag]
A biaxially stretched polyethylene terephthalate film having a thickness of 12 μm and provided with decorative printing by back printing was obtained.

[Production for inner bag]
A laminate was obtained by laminating a low-density polyethylene film having a thickness of 70 μm with a dry laminate adhesive on a polyamide film having a thickness of 15 μm. Two of these laminates were stacked with the heat seal layers inside, and three-sided bags were obtained by heat sealing.

[Production of packaging material that is a double bag]
Punch holes were formed in the vicinity of the edge of the obtained laminate for the inner bag. Next, the two laminated bodies for inner bags and the film for outer bags were piled up. At this time, the adhesive was not partially applied to the three edge portions where the outer bag film and the inner bag were bonded together by bonding with a dry laminate adhesive. Thereby, the packaging material which has the structure of the double bag in which the air path which connects the atmosphere between the inner bag and the outer bag was formed was obtained.

(Comparative Example 1)
Comparative Example 1 is an example of a general chilled packaging material that is not a double bag.

  A film having a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm and a sealant layer made of a low-density polyethylene film having a thickness of 60 μm is provided on the surface to which the decorative printing is applied. A two-sided laminate obtained by laminating with a dry laminate adhesive was heat-sealed with the sealant layers of each laminate inside each other to obtain a three-sided packaging material of Comparative Example 1.

(Comparative Example 2)
Comparative Example 2 is an example in which the packaging material is a complete double bag and does not have an air passage at the joint.

  The above-mentioned cosmetic printing was applied to a film having a 12 μm-thick biaxially stretched polyethylene terephthalate film to which decorative printing by back printing was applied and a sealant layer (thickness 60 μm) by a low-density polyethylene film. A laminate for an outer bag was obtained by laminating with a dry laminate adhesive on the surface. Also, a laminate for an inner bag was obtained by laminating a low-density polyethylene film having a thickness of 25 μm, a polyamide film having a thickness of 15 μm, and a low-density polyethylene film having a thickness of 40 μm with a dry laminate adhesive. Two of the laminates for the inner bag were overlapped so that the heat seal layers were inside. Two layers of outer bag laminates are stacked on the outside of the laminated inner bag laminate so that each heat seal layer is on the inside, and then heat sealed to form a completely double sealed bag Got. In this double sealed bag, air does not communicate between the outer bag laminate and the inner bag laminate, and air is always interposed between the outer bag inner bag and the inner bag laminate. Will do.

(Comparative Example 3)
In Comparative Example 3, air is slightly communicated between the outer bag laminate and the inner bag laminate by forming holes in the outer bag laminate in the double sealed bag of Comparative Example 2. This example is the same as Comparative Example 2 except that.

The holes were formed in the outer laminate under the conditions of a hole diameter of 0.3 mm and a hole density of 64 holes / cm ² .

(test)
Using the packaging materials of Example 1 and Comparative Examples 1 to 3, the following tests were performed.

(1) Appearance change test The hamburger was vacuum-filled and after boiling, 10 samples were stored in a refrigerator at minus 30 ° C., and the appearance change was observed.

(2) Drop strength test The retort-treated packaging body produced by the above method is dropped from the height of 120 cm onto the concrete surface once in the horizontal and vertical directions (twice in total). The presence or absence of leakage was confirmed.

(3) Puncture strength test The contents are taken out from the retort-treated packaging body produced by the above method, and a needle having a diameter of 1 mmφ is pierced from the surface of the laminate at a piercing speed of 200 mm / min, and the needle penetrates the film. The strength (N) required for the measurement was measured.

  The results of the above test are shown in Table 1. As is apparent from Table 1, the packaging material of Example 1 shows excellent properties in a well-balanced manner in all items of appearance change after retorting, drop strength and puncture strength as compared with the packaging materials of Comparative Examples 1 to 3. It was.

  As mentioned above, although the packaging material of this invention was demonstrated concretely using embodiment and an Example, the packaging material of this invention is not limited to description of these embodiment and Example, and the meaning of this invention Many variations are possible without departing from. For example, in the present invention, the shape of the packaging material is preferably rectangular or square from the viewpoint of productivity of the packaging material, but the shape is not limited to rectangular or square. In short, it is a packaging material in which an air passage is formed at a part of the joint between the inner bag and the outer bag, and communicates with the atmosphere between the inner bag and the outer bag, and is used for vacuum packaging and freezing. Any packaging material that can be applied to packaging and can be printed on a film has the above-described effects of the present invention.

  In the embodiments, the packaging material for the three-sided bag and the pillow type bag has been described. However, the present invention is not limited to this, and can be applied to various sealed double bag bodies such as a gusset type and a stand pack type. .

1, 2, Packaging material 11, 21 Inner bag 11a, 12a Base layer 11b, 12b Heat seal layer 12, 22 Outer bag

Claims (5)

An inner bag for containing frozen food or chilled food as an inclusion,
An outer bag that covers the inner bag and is joined to the inner bag;
This inner bag has at least a base layer and a heat seal layer, and consists of a laminate having no barrier layer,
An air passage is formed in a part of a portion where the inner bag and the outer bag are joined, and the air passage is 20% to 60% with respect to the entire length of the joined portion. A packaging material characterized in that the inner bag and the outer bag communicate with the atmosphere through the passage. The packaging material according to claim 1, wherein the inner bag is a three-sided bag in which edges of two laminates having at least a base layer and a heat seal layer are joined .   The packaging material according to claim 1, wherein the inner bag is a pillow type bag.   The packaging material according to any one of claims 1 to 3, wherein a joint portion between the inner bag and the outer bag is an edge portion of the inner bag and the outer bag.   The packaging material according to any one of claims 1 to 4, wherein the air passage is a partial unjoined portion at a joint portion between the inner bag and the outer bag.

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