Packaging bag

Abstract

To provide a packaging bag which can be easily opened and which can be separated by a tearing line even in the case where the directions of the tearing lines are not completely matched on the front side and the rear side of a body part of the packaging bag in opening and a deviation occurs, in the packaging bag which includes an automatic steam vent mechanism and which can be heated and cooked in a microwave oven.SOLUTION: Part of a seal part of any one side of a peripheral edge part is an overhanging seal part having a shape curved and overhanging in the inside direction of a packaging bag. The overhanging seal part is an automatic vent mechanism in heating cooking, and at the seal part of another side opposing to the seal part of this side, at the position opposing to the overhanging seal part, a cut line is provided.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a packaging bag, particularly a packaging bag made of a laminate with a plastic film as a base material, which can be easily opened and separated by tearing even when the tear line of the front and back laminates is misaligned between the front body section and the back body section when tearing to open the packaging bag, without the tear line stopping at the seal section on the opposite side.

[0002] In addition, the packaging bag according to the present invention can be used for cooking in a microwave oven, has an automatic steam vent mechanism that automatically expels water vapor generated by heating to the outside, and is a packaging bag that can be easily opened by tearing with fingers after cooking. [Background technology]

[0003] Packaging bags, a type of packaging material, are widely used and are made of simple or laminated plastic film as a base material. They come in a variety of shapes and are used for a wide range of purposes, making them an indispensable part of modern life.

[0004] For example, plastics are used as liquid containers, and are widely used in the food industry, including beverages and retort foods, as well as in the fields of daily necessities and toiletries, with a wide variety of plastics products lining the shelves of supermarkets, drugstores, and convenience stores. In addition to liquid containers, plastics are being used for a variety of other purposes.

[0005] The advantages of packaging bags compared to containers such as cans and bottles are that they are inexpensive, that detailed material design can be implemented depending on the required quality, and that they are lightweight and space-saving before filling and during distribution and storage. Packaging bags can also be said to be environmentally friendly from the perspective of reducing waste.

[0006] In addition, high-resolution printing on the layer visible from the surface can improve the product's image and display necessary information about the contents, and printing of bar codes, for example, can also serve as a source of product distribution and marketing information.

[0007] Packaging bags continue to evolve in terms of their functionality, with some being self-supporting, some allowing cooking in the microwave, and some improving the shelf life of the contents.

[0008] For example, when cooking using a microwave oven, from the standpoint of ease of use for consumers, it is considered preferable to have some kind of steam release mechanism, because water vapor generated inside the packaging bag during cooking can cause a sudden increase in internal pressure.

[0009] Furthermore, when opening a packaging bag after cooking by tearing it with one's fingers, it is important to prevent burns from residual water vapor, to make the opening easy to open, and to maintain the shape of the opening.

[0010] Patent Document 1 proposes a packaging bag that is equipped with a steam vent mechanism and that attempts to make it easier to tear open, and the proposal is to increase the accuracy of the direction of the tear line by using a tearable polyester resin film.

[0011] However, this method may limit the freedom of choice in terms of materials, and does not necessarily guarantee that the tear lines on the front and back of the body will be aligned in the same direction. Also, when the tear reaches the opposite side, it hits the sealed part, so tearing this part and separating the packaging bag is not necessarily easy. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2015-196512 A Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in consideration of the above circumstances, and has an object to provide a packaging bag that has an automatic steam release mechanism and can be used for cooking in a microwave oven, and that can be easily opened and separated along the tear line even when the tear line along which the front and back of the body of the packaging bag are cut is not completely aligned and misalignment occurs when opening the bag. [Means for solving the problem]

[0014] As a means for solving the above problem, the invention described in claim 1 is: A packaging bag having an automatic steam release mechanism and capable of being heated and cooked in a microwave oven, A packaging bag is made by stacking a laminate having at least a sealant layer, with the sealant layers facing each other, and sealing the periphery of the packaging bag, A part of the seal on one side of the periphery is a protruding seal that curves and protrudes toward the inside of the packaging bag, The protruding seal portion is an automatic steam release mechanism during cooking, A notch is provided in a seal portion on one side opposite to the seal portion on the other side at a position directly opposite the protruding seal portion, The packaging bag is characterized in that the laminate further contains a plastic film layer having straight cuttable properties.

[0015] The invention described in claim 2 is as follows: 2. The packaging bag according to claim 1, wherein the laminate further includes a gas barrier film layer formed by depositing an inorganic compound on a surface of a plastic film. The invention described in claim 3 is as follows: The packaging bag according to claim 1 or 2, characterized in that the vertical width (a) of the protruding seal portion and the offset (b) of the tear line have the following relationship: Vertical width of overhanging seal (a) > offset of tear line (b) Effect of the Invention

[0016] According to the present invention, it is possible to provide a packaging bag that has an automatic steam release mechanism and can be used for cooking in a microwave oven, and that can be easily opened and separated along the tear line even when the tear line when opening is not completely aligned on the front and back of the body of the packaging bag and misalignment occurs.

[0017] In the present invention, the automatic steam release mechanism is a mechanism in which a portion of the seal on one side of the peripheral edge of the packaging bag is a protruding seal that curves and protrudes toward the inside of the packaging bag, and when the packaging bag is heated and cooked in a microwave oven, water steam is generated, causing the internal pressure to increase, and the seal of the protruding seal is peeled off, allowing the water vapor inside to be released to the outside.

[0018] In addition, when the packaging bag is opened after cooking is completed and an opening is to be obtained by tearing and separating the bag, the tear line reaches the peeled portion of the sealed portion, which has the effect of making the tearing and separation easier. In other words, the peeled portion of the sealed portion is not overlapped by the laminate of the front and back body portions, so that the peeled portion can be easily torn.

[0019] In addition, as described above, when tearing the packaging bag, a notch is provided in the seal portion of one side opposite the seal portion of the other side, at a position directly opposite the protruding seal portion. This has the effect of enabling the tearing to begin from the notch, so that the tear line can reach the peeled portion of the seal portion even if there is some misalignment in the opposing protruding seal portion at the front and back body portions.

[0020] Furthermore, according to the invention particularly described in claim 2, the laminate further contains a plastic film layer that has straight-line cuttability in the direction from the notch to the protruding seal portion, thereby ensuring even more straight-line cuttability and making it possible to produce a packaging bag that is easy to open.

[0021] In other words, a protruding seal portion that curves and protrudes toward the inside of the packaging bag is provided on one of the sealed sides of the peripheral portion as an automatic steam release mechanism during cooking. Therefore, the cut lines on the front and back from the incision directly opposite this portion can be cut without leaving any part uncut, as long as it is within a certain range, making it easy and reliable to open and separate the packaging bag.

[0022] Furthermore, according to the invention described in claim 3 in particular, the laminate further includes a gas barrier film layer formed by vapor deposition of an inorganic compound on the surface of the plastic film, thereby improving the preservation of the contents and making it possible to prevent changes such as deterioration of the contents due to the environment.

[0023] Furthermore, when such a gas barrier film layer is used, unlike gas barrier layers using metal foils or the like, there is no problem with cooking in a microwave oven, such as the generation of sparks. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic plan view illustrating the overall shape and the positional relationship between the cuts and the protruding seal portions in one embodiment of the packaging bag according to the present invention. [Diagram 2] FIG. 2 is a schematic plan view illustrating how an automatic steam release mechanism works during cooking in a microwave oven in one embodiment of the packaging bag of the present invention. [Diagram 3] FIG. 3 is a schematic plan view illustrating a packaging bag according to one embodiment of the present invention, for explaining how the packaging bag is torn open after cooking with heat in a microwave oven. [Figure 4] FIG. 4 is a schematic plan view illustrating a packaging bag according to one embodiment of the present invention, which is cut open and then separated after cooking with heat in a microwave oven. [Diagram 5]FIG. 5 is a schematic partial cross-sectional view for explaining one embodiment of a laminate constituting a packaging bag according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The present invention will be described in more detail below with reference to Figs. 1 to 5. However, the present invention is not limited to the examples shown here. The present invention is limited by the claims.

[0026] FIG. 1 is a schematic plan view illustrating the overall shape and the positional relationship between the cuts and the protruding seal portions in one embodiment of the packaging bag according to the present invention.

[0027] The present invention relates to a packaging bag (100) that has an automatic steam release mechanism and allows cooking with a microwave oven. The example shown in Fig. 1 is a plan view seen from the front body portion (17) side.

[0028] The packaging bag (100) is a packaging bag (100) produced by stacking laminates having at least a sealant layer, with the sealant layers facing each other, using a plastic film as a base material, and sealing the peripheral edges of the packaging bag (100).In the example shown in Figure 1, the peripheral edges on all four sides are sealed to produce a roughly rectangular packaging bag (100).

[0029] The automatic steam release mechanism is provided by a protruding seal portion (3) that curves and protrudes toward the inside of the packaging bag (100) in part of the sealed portion on either side of the peripheral edge. In the example of the roughly rectangular packaging bag shown in Figure 1, the protruding seal portion (3) is provided in the center of the sealed portion (2) on the right side as viewed from the front.

[0030] This protruding seal portion (3) is an automatic steam release mechanism for cooking in a microwave oven. When heated, water vapor is generated inside, and the packaging bag expands due to the expansion of its volume. At the same time, the internal pressure increases, and water vapor is released from this portion to the outside of the packaging bag.

[0031] Therefore, this protruding seal portion (3) has weaker sealing strength or can be sealed with a narrower seal width than other sealed portions, and when the internal pressure increases, the seal in this portion is destroyed and the seals of the front and back laminates that make up the body are peeled off, connecting the inside and outside of the packaging bag (100) at the peeled portion, and steam is released from this portion.

[0032] There are no particular restrictions on the means and methods for weakening the seal strength. For example, a state in which the seal strength is weaker than other sealed parts can be achieved by adjusting the sealing conditions or by inserting a layer that is effective for weakening the seal strength in this part during sealing.

[0033] Furthermore, a narrower seal width compared to other sealed portions can be achieved by adjusting the shape and width of the seal bar.

[0034] In other words, this protruding seal portion (3) is characterized by being sealed with weaker sealing strength, or with a narrower seal width, or both, compared to other sealed portions, and is therefore effective as an automatic steam release mechanism during cooking in a microwave oven.

[0035] In addition, in the present invention, a notch is provided in a position directly opposite the protruding seal portion in the seal portion on one side that faces the seal portion on the other side having the protruding seal portion. In the example shown in Figure 1, a notch (4) is provided in the central portion of the seal portion (1) on the left side that faces the protruding seal portion (3) provided in the seal portion (2) on the right side.

[0036] This positional relationship is intended so that when an attempt is made to tear the packaging bag (100) with one's fingers to open it, the tear will begin at the notch (4), reach the protruding seal portion (3), and continue to tear up to the right end portion (9) of the body of the packaging bag (100), thereby separating the packaging bag (100).The intention is that by separating the packaging bag completely, there will be no hindrance to removing the contents from the opening, etc.

[0037] The notch (4) is provided in the center of the sealed portion (1) on the left side. The sealed portion is double-layered with the front and back laminates sealed together, making it resistant to tearing. However, the presence of the notch (4) effectively acts as an opening for easy tearing.

[0038] FIG. 2 is a schematic plan view illustrating how an automatic steam release mechanism works during cooking in a microwave oven in one embodiment of the packaging bag of the present invention.

[0039] Therefore, this packaging bag (100) can be used for cooking food, for example, and is intended to cook the moisture contained in the food contents using the high frequency waves of a microwave oven for consumption. After a certain amount of water vapor is generated during cooking, it is discharged to the outside of the packaging bag (100) by an automatic steam release mechanism due to an increase in internal pressure created by the bag itself.

[0040] That is, in the example shown in Figures 1 and 2, when cooking with a microwave oven, water vapor is generated from the contents inside the packaging bag (100) due to heating, and the packaging bag (100) expands due to the volume expansion, and at the same time, the internal pressure increases.

[0041] At this time, the volume expansion occurs three-dimensionally radially from the volume center (8) of the internal space of the packaging bag (100), and is indicated by eight arrows from the volume center (8) in the example shown in Figure 2. This volume expansion applies pressure to the seal portion, particularly the vertical seal portion in Figure 2, in the protruding seal portion (3), which acts as a peeling force on the front and back laminates.

[0042] For example, in the example shown in Figure 2, the packaging bag has its edges sealed, and even if volume expansion occurs due to water vapor, it is possible for the bag to deform from the roughly rectangular shape shown in Figure 2 into a three-dimensional inflated shape as long as the internal pressure is low.

[0043] However, this radial three-dimensional volume expansion also attempts to expand spherically, resulting in a discrepancy with the expansion room of the packaging bag.

[0044] At this time, since the protruding seal portion (3) has a curved shape toward the inside of the packaging bag (100), it is positioned closer to the volume center (8). Therefore, in the example shown in Figure 2, due to three-dimensional radial volume expansion, it receives stronger pressure to peel in the forward and backward directions toward Figure 2, so that the stress concentration in this part becomes more severe, and the sealed portion of the protruding seal portion (3) peels off.

[0045] In Fig. 2, this portion is shown as peeled portion (5), and the peeled portion (5) connects the inside and outside of the packaging bag (100) to form an automatic steam release mechanism. Steam is released in the direction of one of the eight arrows in Fig. 2, and water vapor (40) is released to the outside from peeled portion (5) of the protruding seal portion (3).

[0046] In other words, this part acts as an automatic steam release mechanism, so that the internal pressure of the packaging bag (100) is rapidly reduced, and such peeling does not occur in the other sealed parts around the periphery of the packaging bag (100).

[0047] Furthermore, in the present invention, the protruding seal portion (3) is sealed with weaker sealing strength, narrower sealing width, or both, compared to the other peripheral seal portions, so that destruction or peeling of the seal portion due to volume expansion occurs more reliably at the protruding seal portion (3), providing a stable and reliable automatic steam release mechanism.

[0048] FIG. 3 is a schematic plan view illustrating a packaging bag according to one embodiment of the present invention, for explaining how the packaging bag is torn open after cooking with heat in a microwave oven. One of the features of the present invention is that a notch is provided in the seal portion on one side opposite the seal portion on the other side where the protruding seal portion is located, at a position directly opposite the protruding seal portion.

[0049] That is, in the example shown in FIG. 3, a protruding seal portion (3) is provided in the center of the seal portion (2) on the right side, and a notch (4) is provided in the seal portion (1) on the left side, making it easier to start the opening operation by using this notch (4) as a trigger.

[0050] The cut (4) may be V-shaped as shown in Fig. 3, or may simply be a cut in the sealed portion, so long as it provides an opening for tearing when opening. If necessary, the position of this cut may be indicated on the outer surface of the body of the packaging bag so that it can be easily seen from outside the packaging bag.

[0051] Next, the body of the packaging bag (100) can be torn with the fingers toward the protruding seal portion (3) located directly opposite the cut (4). The torn is performed on both the front body portion (17) and the rear body portion (18).

[0052] At this time, the slit line (6) of the front body part and the slit line (7) of the rear body part of the front and back laminates do not necessarily match perfectly, and there may be a slight misalignment. In the example shown in Figure 3, this is shown as the misalignment of the slit lines (b).

[0053] As already described in the explanation of the example shown in FIG. 2, the protruding seal portion (3) peels off to become a peeled portion (5) as the sealed portion acts as an automatic steam release mechanism, and the vertical width of this portion is the vertical width (a) of the protruding portion in FIG. 3.

[0054] That is, as shown in the example in Figure 3, Vertical width of overhanging seal (a) > offset of tear line (b) Within this range, both of the tear lines will reach the peeled portion (5) of the protruding seal portion (3), and the tearing can proceed easily.

[0055] In fact, since the notch (4) is provided in a position directly opposite the protruding seal portion (3) and the cutting operation starts toward the peeled portion (5) of the protruding seal portion (3), it is easy to reach the peeled portion (5) of the protruding seal portion (3) in a normal tearing operation.

[0056] In other words, the tear lines in both the front body portion (17) and the rear body portion (18) reach the peeled portion (5) of the protruding seal portion (3) and further reach the right end portion (9) of the body portion, making it easy to separate the packaging bag (100) by tearing it with the fingers.

[0057] The portion from the peeled portion (5) of the protruding seal portion (3) to the right end portion (9) of the body portion is on the outside of the packaging bag (100) when viewed from the protruding seal portion (3). This portion is not sealed, and the front and back laminates are separate and not double-sealed, so it can be easily torn apart.

[0058] For example, if the positional relationship between the notch (4) and the protruding seal portion (3) does not correspond to the directly facing positional relationship specified in the present invention, and the tip of the tear line directly reaches the seal portion (2) on the right side, this portion will be sealed against the sealant of the laminate, and since the laminate is double-layered, it will be difficult to cut this portion by tearing with the fingers.

[0059] FIG. 4 is a schematic plan view illustrating a packaging bag according to one embodiment of the present invention, which is cut open and then separated after cooking with heat in a microwave oven.

[0060] As described in the explanation of Figures 1 to 3, when the contents of the packaging bag (100) are cooked in a microwave oven, steam is automatically released from the protruding seal portion (3) of the packaging bag (100), and the bag is torn by fingers starting from the slit (4).

[0061] As a result, the packaging bag (100) according to the present invention can be easily separated into upper and lower parts as shown in Fig. 4. In the example shown in Fig. 4, separation into upper and lower parts is indicated by the up and down arrows in Fig. 4.

[0062] In the example shown in FIG. 4, the slit line (6) on the front side of the same part and the slit line (7) on the rear body part are misaligned, but each of them runs from the cut (4) through the peeled part (5) of the protruding seal part (3) to the right end part (9) of the body part.

[0063] In this manner, the packaging bag (100) can be easily separated, which has the effect of facilitating handling of the cooked packaging bag (100) and its contents, as well as removal of the contents.

[0064] For example, if a portion of the bag remains continuous and the packaging bag (100) cannot be separated into two, it may be difficult to secure an opening, and it may be difficult to remove the contents or handle the packaging bag (100) itself.

[0065] FIG. 5 is a schematic partial cross-sectional view for explaining one embodiment of a laminate constituting a packaging bag according to the present invention.

[0066] As described above, the present invention relates to a packaging bag having an automatic steam release mechanism and capable of being used for cooking in a microwave oven, and this packaging bag (100) is produced by stacking laminates having at least a sealant layer, with the sealant layers facing each other, using a plastic film as a base material, and sealing the peripheral edges of the packaging bag.

[0067] 5, the laminate (30) has a plastic film substrate layer (11) and a sealant layer (15). In addition, the laminate (30) may contain other layers as necessary.

[0068] For example, the laminate constituting the packaging bag (100) of the present invention may further include a plastic film layer (10) that can be cut straight in the direction from the slit (4) to the protruding seal portion (3).

[0069] The plastic film layer (10) having the linear cutting property can be, for example, a plastic film that utilizes the molecular orientation. The molecular orientation can be achieved, for example, by stretching the film in one direction.

[0070] In such a case, the straight cutting ability of the slit line is further improved, so that the deviation (b) of the slit line between the front and back is smaller, and the risk of it deviating from the vertical width (a) of the protruding portion is further reduced.

[0071] In the present invention, the laminate constituting the packaging bag (100) may further include a gas barrier film (20) having an inorganic compound layer (13) formed on the surface of the plastic film (14) by vapor deposition.

[0072] This is because, when a metal foil such as an aluminum foil is used as a gas barrier layer, problems such as sparks occurring during cooking in a microwave oven can occur. However, the gas barrier film (20) makes it possible to avoid the risk of sparks without impairing the gas barrier properties.

[0073] The plastic films used in each layer of the laminate (30) are films made of polymeric resin compositions, such as polyolefins (polyethylene, polypropylene, etc.), polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (nylon-6, nylon-66, etc.), polyimides, etc., and are selected appropriately depending on the application.

[0074] In particular, polypropylene and polyethylene terephthalate are preferable in terms of film strength and cost when used as plastic films. In addition, when a stretched polyamide film is used, it is possible to impart the laminate with strength against punctures and strength against impacts.

[0075] The plastic film can also be laminated with other layers via an adhesive layer (12) to form a laminate (30). The layer structure, material structure, thickness, etc. of the laminate (30) can be designed appropriately depending on the quality required for the packaging bag (100).

[0076] In addition, for example, in order to improve the shelf life of the contents, an opaque layer that blocks ultraviolet rays, such as a colored film, can be provided in the laminate (30) that constitutes the packaging bag (100).

[0077] Alternatively, as described above, a gas barrier layer can be provided in the laminate 30. For example, a gas barrier film 20 can be used in which a gas barrier layer is provided on the surface of a plastic film.

[0078] Metal foil such as aluminum, or a metal vapor-deposited layer on the surface of a plastic film are also effective as gas barrier layers, but as mentioned above, they are unsuitable for cooking in a microwave oven because of the generation of sparks due to high frequency waves.

[0079] In the case of the gas barrier film (20), the plastic film used is a film made of a polymer resin composition, such as polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide (nylon-6, nylon-66, etc.), polyimide, etc., and is appropriately selected depending on the application. In particular, polypropylene and polyethylene terephthalate are preferable in terms of film strength and cost when used as the plastic film substrate.

[0080] In the case of the gas barrier film (20), the gas barrier layer can be composed of an inorganic compound vapor deposition layer (13) and a coating layer, and after providing an anchor coat on the plastic film, the vapor deposition layer and the coating layer are provided in that order.

[0081] For example, urethane acrylate can be used for the anchor coat layer of the gas barrier film. The anchor coat layer can be formed by using a coating method that applies a printing technique such as gravure coating with a paint in which a resin is dissolved in a solvent, or by using a commonly known coating method to form a coating film.

[0082] As a method for forming a vapor deposition layer, an inorganic compound such as SiO or AlO can be coated on a plastic film provided with an anchor coat layer by vacuum deposition to form an inorganic compound vapor deposition layer (13) by the vacuum deposition method. The thickness of the vapor deposition layer is preferably 15 nm to 30 nm.

[0083] The method for forming the coating layer can be to apply a coating agent, the main component of which is an aqueous solution or a water / alcohol mixed aqueous solution containing at least one of a water-soluble polymer and (a) one or more alkoxides or their hydrolysates, or both, or (b) tin chloride, onto the film, and then heat-dry to form an inorganic compound layer by the coating method, which can be used as the coating layer. In this case, the coating agent can be added with a silane monomer to improve adhesion with the anchor coat layer.

[0084] The inorganic compound layer vapor deposition (13) has gas barrier properties even when it is only a coating film formed by the vacuum vapor deposition method, but a gas barrier layer can also be formed by overlaying a coating layer, which is an inorganic compound layer formed by a coating method, on a vapor deposition layer, which is an inorganic compound layer formed by the vacuum vapor deposition method.

[0085] By combining these two layers, a reaction layer between the inorganic compound layer formed by the vacuum deposition method and the inorganic compound layer formed by the coating method is generated at the interface between the two layers, or the inorganic compound layer formed by the coating method fills and reinforces defects or micropores such as pinholes, cracks, and grain boundaries that occur in the inorganic compound layer formed by the vacuum deposition method, thereby forming a dense structure.

[0086] Therefore, the gas barrier film (20) can achieve high gas barrier properties, moisture resistance, and water resistance, and also has flexibility that allows it to withstand deformation due to external forces, making it suitable for use as a packaging material.

[0087] In addition, when SiO is used as the gas barrier layer, the coating is transparent, so the contents can be seen from the outside of the packaging bag. These can be used appropriately depending on the application and required quality.

[0088] The sealant layer (15) enables two laminates to be stacked with the sealant layers (15) facing each other, and bonded together by applying heat and pressure to heat seal, thereby forming the laminate into a packaging bag (100).

[0089] As the material for the sealant layer (15), polyolefin-based resins, which are thermoplastic resins, are generally used. Specifically, ethylene-based resins such as low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-methacrylic acid resin copolymer; blend resins of polyethylene and polybutene; and polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer can be used.

[0090] The sealant layer (15) can be formed by forming a film of molten resin using an extruder or the like to form a layer on the laminate (30). Alternatively, the sealant layer (15) can be formed on the surface of the laminate (30) by laminating a material that has already been formed into a film state.

[0091] If necessary, in order to improve the image of the product, to display necessary information about the contents, and to improve the design, a printed ink layer (16) can be provided on a layer of the laminate based on a plastic film that is visible from the outside of the packaging bag. The printed ink layer (16) may be provided on the packaging bag (100), i.e., the outermost layer of the laminate (30).

[0092] The printed ink layer (16) may be provided on a part of the packaging bag (100), or may be provided over the entire surface of the packaging bag (100). Alternatively, a method of providing a display portion without using the printed ink layer (16) may be, for example, to attach a printed sticker to the surface of the packaging bag (100).

[0093] Here, there are no particular restrictions on the printing method and printing ink, but any of the known printing methods may be appropriately selected in consideration of printability on plastic films, design such as color tone, adhesion, and safety as a food container.

[0094] For example, a printing method can be selected from known printing methods such as gravure printing, offset printing, gravure offset printing, flexographic printing, silk screen printing, inkjet printing, etc. Among them, gravure printing is preferably used in terms of productivity, printability on plastic films, and high definition of patterns.

[0095] Thus, according to the present invention, a portion of the seal portion on one of the peripheral sides of the packaging bag is a protruding seal portion that curves and protrudes toward the inside of the packaging bag, and this protruding seal portion serves as an automatic steam release mechanism during cooking, and is sealed with weaker sealing strength or a narrower seal width than the other sealed parts, or both. In the seal portion on the other side opposite this one side seal portion, a notch is provided at a position directly opposite the protruding seal portion. This makes it possible to provide a packaging bag that has an automatic steam release mechanism and can be used for cooking in a microwave oven, which can be easily opened and separated along the tear line even when the tear line when opening is not completely consistent on the front and back of the body of the packaging bag, causing a misalignment. [Explanation of symbols]

[0096] 1. Seal part on the left side 2. Right side seal 3. Protruding seal part 4. Cutting 5...Peeling part 6. Cut line on front side 7. Tear line in rear fuselage 8. Volume center 9...Right end of body 10: Plastic film layer with straight cut properties 11 Plastic film base layer 12...Adhesive layer 13. Inorganic compound vapor deposition layer 14. Plastic film 15. Sealant layer 16 Printing ink layer 17... Front body 18 Rear torso 20. Gas barrier film 30...Laminate 40...Water vapor 100...packaging bag a: Vertical width of protruding seal part b. Misalignment of the tear line

Claims

1. A packaging bag having an automatic steam release mechanism that allows for heating and cooking in a microwave oven, A packaging bag is manufactured by stacking a laminate in which a first plastic film layer, a second plastic film layer, a third plastic film layer, and a sealant layer are laminated in this order, with the sealant layers facing each other, and the periphery of the packaging bag is sealed. A portion of the seal on one side of the periphery is a protruding seal portion that curves and protrudes inward towards the inside of the packaging bag. The aforementioned protruding seal portion is an automatic steam release mechanism during cooking, In the sealing portion on the other side opposite to the sealing portion on either side, a notch is provided. One of the first plastic film layer, the second plastic film layer, and the third plastic film layer has straight-line cutting properties. An inorganic compound layer is formed in any of the first plastic film layer, the second plastic film layer, and the third plastic film layer. The second plastic film layer has the straight-line cutting properties, The third plastic film layer is laminated to the sealant layer via an adhesive layer. A packaging bag characterized by the following features.

2. The packaging bag according to claim 1, characterized in that the vertical width of the protruding seal portion (a) and the offset of the tear line (b) have the following relationship. Vertical width of the protruding sticker portion (a) > Misalignment of the tear line (b)

Images