Packaging bags

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. In particular, it is a packaging bag made of a laminate with a plastic film as a base material. When this packaging bag is torn for opening, even when the tear lines of the front and back laminates are displaced between the front body part and the rear body part, the tear line does not stop at the seal part on the opposite side, and the present invention relates to a packaging bag that can easily open and separate the packaging bag by tearing.

[0002] In addition, the packaging bag according to the present invention can be used for heat cooking in a microwave oven, has an automatic steam venting mechanism that automatically discharges the steam generated by heating to the outside, and relates to a packaging bag that can be easily opened by tearing with fingers after heat cooking.

Background Art

[0003] A packaging bag, which is a type of packaging material, is widely spread and is composed of a single or laminated body with a plastic film as a base material. Various forms of it are used in a wide range of applications and have become indispensable for modern life.

[0004] For example, it is also used as a liquid container, widely used not only for beverages but also in the food field such as retort foods, and various products in the fields of daily necessities and toiletries are filling the shelves of supermarkets, drugstores, and convenience stores. In addition to liquid containers, various applications have been developed.

[0005] The advantages of the packaging bag include that it is cheaper than containers such as cans and bottles, can be dealt with by a fine material design according to the required quality, or is lightweight and space-saving before filling the contents and during distribution and storage. Also, the packaging bag can be said to be environmentally adaptable from the viewpoint of reducing waste.

[0006] Furthermore, high-definition printing on the visible surface layer can enhance the product's image and display necessary information about its contents. Barcode printing, for example, serves as a source of information for product distribution and marketing.

[0007] Packaging bags are constantly evolving in terms of functionality, with features such as self-standing capabilities, microwave-safe design, and improved preservation of contents.

[0008] For example, in microwave cooking, from the perspective of ease of use for consumers, it is preferable to have some kind of steam release mechanism, as the steam generated inside the packaging bag during cooking can cause a rapid increase in internal pressure.

[0009] Furthermore, when opening the packaging bag after cooking by tearing it open with your fingers, important considerations include preventing burns from residual steam, ensuring the opening is easy to open, and maintaining the shape of the opening.

[0010] Patent Document 1 proposes a packaging bag equipped with a steam venting mechanism that aims to improve the ease of tearing and opening, and this proposal aims to improve the accuracy of the tear line direction by using a tearable polyester resin film.

[0011] However, this may limit the freedom of material selection and does not necessarily guarantee that the tear lines on the front and back of the body will align. Furthermore, when the tear reaches the opposite side, it will hit the seal, making it not always easy to tear this section and separate the packaging bag. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2015-196512 [Overview of the project] [Problems that the invention aims to solve]

[0013] The present invention has been made in view of the above circumstances, and aims to provide a packaging bag that has an automatic steam release mechanism and is suitable for microwave heating, which allows for easy opening and separation along the tear line even when the direction of the tear line does not perfectly coincide on the front and back of the body of the packaging bag, resulting in misalignment. [Means for solving the problem]

[0014] As a means to solve the above problems, the invention described in claim 1 is, A packaging bag having an automatic steam release mechanism that allows for heating and cooking in a microwave oven, This packaging bag is made by using a plastic film as a base material, stacking laminates having at least one sealant layer with the sealant layers facing each other, and sealing the periphery of the packaging bag. 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 at a position directly facing the protruding sealing portion. The packaging bag is characterized in that the laminate further contains a plastic film layer having straight-line cutting properties.

[0015] Furthermore, the invention described in claim 2 is, The packaging bag according to claim 1, characterized in that the laminate further includes a gas barrier film layer formed by vapor deposition of an inorganic compound on the surface of a plastic film. Furthermore, the invention described in claim 3 is, The packaging bag according to claim 1 or 2 is 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 seal portion (a) > offset of the tear line (b) [Effects of the Invention]

[0016] According to the present invention, in a packaging bag that has an automatic steam release mechanism and is suitable for microwave heating, it is possible to provide a packaging bag that can be easily opened and separated along the tear line even when the direction of the tear line does not perfectly coincide on the front and back of the body of the packaging bag, resulting in misalignment.

[0017] In this invention, the automatic steam release mechanism has a protruding seal portion on one side of the peripheral edge of the packaging bag, which is curved and protrudes inward. When the packaging bag is heated in a microwave oven, the internal pressure increases due to the generation of steam, causing the seal on the protruding seal portion to peel off and the steam inside to be released to the outside.

[0018] Furthermore, when attempting to open the packaging bag after cooking is complete and tear it open to secure the opening, the tear line reaches the peeling portion of the seal, making tearing and separation easier. This is because the peeling portion of the seal does not have a double layer of laminated material on the front and back of the body, making it easy to tear.

[0019] Furthermore, as mentioned above, the packaging bag has the effect of allowing the tearing to reach the peeled portion of the seal even if there is some misalignment between the front and back sides of the bag, by starting the tearing from the notch on the seal portion of the other side facing the seal portion of the other side, opposite the seal portion of the other side.

[0020] Furthermore, according to the invention described in claim 2 in particular, the laminate further includes a plastic film layer that has straight-line cutting properties in the direction from the cut to the protruding seal portion, thereby ensuring even straight-line cutting properties and making it possible to create a packaging bag that does not interfere with opening.

[0021] That is, in the seal part on any one side of the peripheral part, there is a protruding seal part that curves and protrudes in the direction of the inside of the packaging bag, and is provided as an automatic steam venting mechanism during heat cooking. Therefore, as long as the cut lines on the front and back from the cut facing this part are within a certain range, it is possible to cut without leaving any residue, and the opening and separation of the packaging bag can be made easy and reliable.

[0022] Further, according to the invention described in claim 3 in particular, the laminate further includes a gas barrier film layer formed by vapor-depositing an inorganic compound on the surface of the plastic film, thereby enhancing the storage stability of the contents and making it possible to avoid changes such as deterioration of the contents due to the environment.

[0023] Also, when using such a gas barrier film layer, unlike a gas barrier layer using a metal foil or the like, it does not interfere with heat cooking by a microwave oven, such as the generation of sparks.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a plan schematic view for explaining the overall shape and the positional relationship between the cut and the protruding seal part in one embodiment of the packaging bag according to the present invention. [Figure 2] FIG. 2 is a plan schematic view for explaining the state in which the automatic steam venting mechanism operates during microwave heating cooking in one embodiment of the packaging bag according to the present invention. [Figure 3] FIG. 3 is a plan schematic view for explaining the state in which the packaging bag is torn and opened after microwave heating cooking in one embodiment of the packaging bag according to the present invention. [Figure 4] FIG. 4 is a plan schematic view for explaining the state in which the packaging bag is separated after being torn and opened after microwave heating cooking in one embodiment of the packaging bag according to the present invention. [Figure 5]Figure 5 is a schematic partial cross-sectional view illustrating one embodiment of a laminate constituting a packaging bag according to the present invention. [Modes for carrying out the invention]

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

[0026] Figure 1 is a plan view diagram illustrating one embodiment of a packaging bag according to the present invention, showing the overall shape and the positional relationship between the cutout and the protruding seal portion.

[0027] The present invention relates to a packaging bag (100) that has an automatic steam release mechanism and can be heated in a microwave oven. The example shown in Figure 1 is a plan view taken from the front side of the body (17).

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

[0029] The automatic steam release mechanism consists of a protruding seal portion (3) that curves and protrudes inward from a part of the seal portion on one side of the periphery of the packaging bag (100). In the example of the roughly rectangular packaging bag shown in Figure 1, the protruding seal portion (3) is provided in the central part of the seal portion (2) on the right side.

[0030] This protruding seal portion (3) is an automatic steam release mechanism for microwave heating. When heating, water vapor is generated inside, and the expansion of its volume causes the packaging bag to inflate, simultaneously increasing the internal pressure and releasing the water vapor to the outside of the packaging bag from this portion.

[0031] Therefore, this protruding seal portion (3) has weaker sealing strength or a narrower sealing width compared to other sealing portions, and as the internal pressure increases, the seal in this portion is destroyed, the seal of the laminated material on the front and back that makes up the body peels off, the inside and outside of the packaging bag (100) are connected at the peeled portion, and steam is released from this portion.

[0032] Weakening the seal strength does not impose any particular restrictions on the means or methods of doing so. For example, a state in which the seal strength is weaker compared to other sealed areas can be achieved by adjusting the sealing conditions or by inserting a layer effective in weakening the seal during the sealing process.

[0033] Furthermore, a narrower seal width compared to other sealed areas 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 having weaker sealing strength, a narrower sealing width, or both, compared to other sealing portions, making it effective as an automatic steam release mechanism during microwave cooking.

[0035] Furthermore, in the present invention, a notch is provided in the seal portion on the other side opposite to the seal portion on the side with the protruding seal portion, at a position directly facing the protruding seal portion. In the example shown in Figure 1, a notch (4) is provided in the central part of the left side seal portion (1), which is directly facing the protruding seal portion (3) provided on the right side seal portion (2).

[0036] This positional relationship is intended to separate the packaging bag (100) when attempting to open it by tearing it open with one's fingers. This separation is intended to start from the notch (4), reach the protruding seal portion (3), and then tear further to the right end (9) of the body of the packaging bag (100). The intention is to ensure complete separation so that there is no hindrance to removing the contents from the opening.

[0037] Furthermore, the notch (4) is provided in the central part of the seal portion (1) on the left side. The seal portion is a double layer where the laminated materials on the front and back are sealed together, making it robust against tearing. However, the presence of the notch (4) effectively acts as an easy starting point for tearing.

[0038] Figure 2 is a plan view diagram illustrating the operation of an automatic steam release mechanism during microwave heating in one embodiment of the packaging bag according to the present invention.

[0039] Therefore, this packaging bag (100) can be used for purposes such as heating food, and is intended to heat the moisture contained in the food contents using the high frequency of a microwave oven to make it edible. After a certain amount of steam is generated during heating, the steam itself causes an increase in internal pressure, which is then discharged to the outside of the packaging bag (100) by an automatic steam release mechanism.

[0040] In other words, in the examples shown in Figures 1 and 2, when cooking using a microwave oven, steam is generated from the contents inside the packaging bag (100) due to heating, and the packaging bag (100) inflates due to the volume expansion of the steam, and at the same time the internal pressure increases.

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

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

[0043] However, this radial, three-dimensional volume expansion, in an attempt to further expand spherically, results in a conflict with the expansion capacity of the packaging bag.

[0044] At this time, because the protruding seal portion (3) is curved toward the inside of the packaging bag (100), it is located closer to the volume center (8). Due to the three-dimensional radial volume expansion, in the example shown in Figure 2, it receives stronger pressure in the front-to-back direction toward Figure 2, causing stress concentration in this area to become more severe, and the seal portion of the protruding seal portion (3) to peel off.

[0045] Furthermore, in Figure 2, this portion is shown as the peel-off portion (5), and the peel-off connects the inside and outside of the packaging bag (100) at this peel-off portion (5), thus creating an automatic steam venting mechanism. Steam venting is performed in the direction of the one colored arrow among the eight arrows in Figure 2, and water vapor (40) is ejected to the outside from the peel-off portion (5) of the protruding seal portion (3).

[0046] In other words, because this part acts as an automatic steam release mechanism, the internal pressure of the packaging bag (100) decreases rapidly, and such delamination does not occur in the other peripheral seal portions of the packaging bag (100).

[0047] Furthermore, in this invention, the protruding seal portion (3) is sealed with weaker sealing strength, a narrower sealing width, or both, compared to the sealing portions of other peripheral edges. Therefore, the failure and peeling of the seal portion due to volume expansion occurs more reliably in this protruding seal portion (3), resulting in a stable and reliable automatic steam venting mechanism.

[0048] Figure 3 is a plan view diagram illustrating one embodiment of the packaging bag according to the present invention, showing how the packaging bag is opened by tearing it after microwave heating. One of the features of this invention is that a notch is provided in the sealing portion on the other side opposite to the sealing portion on the side with the protruding sealing portion, at a position directly facing the protruding sealing portion.

[0049] In other words, in the example shown in Figure 3, a protruding seal portion (3) is provided in the central part of the seal portion (2) on the right side, and there is a notch (4) in the seal portion (1) on the left side, so that the opening process can be started more easily by using this notch (4) as a starting point.

[0050] The notch (4) may be V-shaped as shown in Figure 3, or it may simply be a notch in the seal portion, as long as it serves as a starting point for tearing when opening the package. If necessary, the location of this notch may be indicated on the outer surface of the body of the packaging bag so that it can be easily seen from the outside of the packaging bag.

[0051] Next, the body of the packaging bag (100) can be torn by hand, towards the protruding seal portion (3) at a position directly opposite the cut (4). The tearing is performed on both the front body (17) and the back body (18).

[0052] In this case, the cut lines (6) on the front side of the laminated body and the cut lines (7) on the back side of the body may not perfectly coincide, and a slight misalignment may occur. In the example shown in Figure 3, this is indicated by the misalignment of the cut lines (b).

[0053] Furthermore, as already mentioned in the explanation of the example shown in Figure 2, the protruding seal portion (3) has a seal portion that acts as an automatic steam release mechanism, and the seal portion peels off to become a peeled portion (5). The vertical width of this portion is the vertical width (a) of the protruding portion in Figure 3.

[0054] In other words, as shown in the example in Figure 3, Vertical width of the protruding seal portion (a) > offset of the tear line (b) Within this range, both tear lines reach the peeled portion (5) of the protruding seal portion (3), and the tearing can be easily carried out.

[0055] In fact, since the tearing operation is performed with the cut (4) positioned directly facing the protruding seal portion (3) and the tearing is initiated toward the peeling portion (5) of the protruding seal portion (3), reaching the peeling portion (5) of the protruding seal portion (3) is easy in a normal tearing operation.

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

[0057] From the peeling portion (5) of the protruding seal portion (3) to the right end (9) of the body, the area is on the outside of the packaging bag (100) when viewed from the protruding seal portion (3). This area is not sealed, the front and back laminates are separate, and it is not a double-sealed area, so it is easy to tear.

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

[0059] Figure 4 is a plan view diagram illustrating one embodiment of the packaging bag according to the present invention, showing the packaging bag after being cut open and separated following microwave heating.

[0060] As described in the explanations of Figures 1 to 3, when the contents of the packaging bag (100) are heated in a microwave oven, steam is automatically released from the protruding seal portion (3) of the packaging bag (100), and the bag is then torn open by hand, starting from the cut (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 Figure 4. In the example shown in Figure 4, the separation of the upper and lower parts is represented by the up and down arrows in Figure 4.

[0062] In the example shown in Figure 4, the cut line (6) on the front side and the cut line (7) on the rear side of the body, although slightly misaligned, both reach the right end (9) of the body, passing through the cut (4) and the peeled portion (5) of the protruding seal (3).

[0063] By making it easy to separate the packaging bag (100) in this way, the handling of the cooked packaging bag (100) and its contents, as well as the removal of the contents, becomes easier.

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

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

[0066] As described above, the present invention is a packaging bag that has an automatic steam release mechanism and is suitable for heating and cooking in a microwave oven. This packaging bag (100) is made by using a plastic film as a base material, stacking laminates having at least one sealant layer with the sealant layers facing each other, and sealing the periphery of the packaging bag.

[0067] In the example shown in Figure 5, the laminate (30) has a sealant layer (15) on a plastic film substrate layer (11). In addition, the laminate (30) may include other layers as needed.

[0068] For example, in the present invention, the laminate constituting the packaging bag (100) may further include a plastic film layer (10) having straight-line cutting properties in the direction from the cut (4) to the protruding seal portion (3).

[0069] This plastic film layer (10) with linear cut properties can be, for example, one that utilizes the molecular orientation of the plastic film. Molecular orientation can be achieved, for example, by stretching the film in one direction.

[0070] In such cases, the straightness of the cut line is improved, resulting in a smaller misalignment (b) between the cut lines on the front and back sides, and further reducing the risk of deviating from the vertical width (a) of the protruding part.

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

[0072] This is because, while using metal foil such as aluminum foil as a gas barrier layer can cause problems such as sparking during microwave cooking, using a gas barrier film (20) makes it possible to avoid the risk of sparking without compromising the gas barrier properties.

[0073] The plastic film used in each layer of the laminate (30) is a film made of a polymer resin composition, and can be made of polyolefins (polyethylene, polypropylene, etc.), polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (nylon-6, nylon-66, etc.), polyimides, etc., and can be appropriately selected depending on the application.

[0074] Polypropylene and polyethylene terephthalate are particularly preferable as plastic films in terms of film strength and cost. Furthermore, when stretched polyamide films are used, the laminate can be given toughness against punctures and impacts.

[0075] Furthermore, the plastic film can be laminated with other layers via an adhesive layer (12) to form a laminate (30). The layer configuration, material composition, and thickness of the laminate (30) can be appropriately designed according to the required quality for the packaging bag (100).

[0076] Furthermore, for purposes such as improving the preservation of the contents, an opaque layer that blocks ultraviolet rays, such as a colored film, can be provided in the laminate (30) that makes up the packaging bag (100).

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

[0078] While metal foils such as aluminum, or plastic films with a metal vapor-deposited film on the surface, are also effective as gas barrier layers, they are unsuitable for microwave cooking due to the generation of sparks caused by high-frequency waves, as mentioned above.

[0079] In the case of gas barrier films (20), the plastic film used is a film made of a polymer resin composition, and can be, for example, polyolefins (polyethylene, polypropylene, etc.), polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (nylon-6, nylon-66, etc.), polyimides, etc., and can be appropriately selected depending on the application. Polypropylene and polyethylene terephthalate are particularly preferable as the plastic film substrate in terms of film strength and cost.

[0080] In the case of a gas barrier film (20), the gas barrier layer can consist of an inorganic compound vapor-deposited layer (13) and a coating layer. After an anchor coat is applied to the plastic film, the vapor-deposited layer and the coating layer are applied sequentially.

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

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

[0083] As a method for forming a coating layer, a coating agent mainly composed of a water-soluble polymer and an aqueous solution or water / alcohol mixed aqueous solution containing at least one of the following: (a) one or more alkoxides or their hydrolysates, or both, or (b) tin chloride, can be applied to a film and heated and dried to form an inorganic compound layer by a coating method. At this time, by adding silane monomer to the coating agent, adhesion with the anchor coat layer can be improved.

[0084] Although the inorganic compound layer deposition (13) has gas barrier properties even with only the coating film made by vacuum deposition, a gas barrier layer can be formed by layering a coating layer, which is an inorganic compound layer made by coating, on top of the deposition layer, which is an inorganic compound layer made by vacuum deposition.

[0085] The combination of these two layers creates a reaction layer between the inorganic compound layer produced by vacuum deposition and the inorganic compound layer produced by coating, or the inorganic compound layer produced by coating fills and reinforces defects or micropores such as pinholes, cracks, grain boundaries that occur in the inorganic compound layer produced by vacuum deposition, thereby forming a dense structure.

[0086] Therefore, as a gas barrier film (20), it achieves higher gas barrier properties, moisture resistance, and water resistance, and also possesses flexibility that can withstand deformation due to external forces, thus making it suitable as a packaging material.

[0087] Furthermore, when using SiO as the gas barrier layer, for example, the coating is transparent, allowing the contents to be visually inspected from the outside of the packaging bag. These materials should be used appropriately depending on the application and required quality.

[0088] The sealant layer (15) allows for the formation of a packaging bag (100) by overlapping two laminates so that the sealant layers (15) face each other, and then heat-sealing them by heating and pressurizing to bond them together.

[0089] As for the material of the sealant layer (15), polyolefin resins among thermoplastic resins are generally used. Specifically, ethylene 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 can be used, as well as polyethylene and polybutene blend resins, homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer, among others.

[0090] The sealant layer (15) can be formed by creating a film of molten resin using an extruder or the like, and then forming 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.

[0091] If necessary, a printing ink layer (16) can be provided in the layer visible from the outside of the packaging bag within the laminate, which is based on a plastic film, for the purpose of improving the product's image, displaying necessary information about the contents, and enhancing the design. The printing ink layer (16) may also be provided in the outermost layer of the packaging bag (100), i.e., the laminate (30).

[0092] Furthermore, the printing ink layer (16) may be provided on a part of the packaging bag (100), or it may be provided over the entire surface of the packaging bag (100). Alternatively, as a method of providing a display area without using the printing ink layer (16), for example, a printed sticker can be attached to the surface of the packaging bag (100).

[0093] There are no particular restrictions on the printing method or printing ink used here; however, a known printing method may be appropriately selected considering factors such as suitability for printing on plastic film, design aspects such as color tone, adhesion, and safety as a food container.

[0094] For example, known printing methods such as gravure printing, offset printing, gravure offset printing, flexographic printing, screen printing, and inkjet printing can be selected and used. Among these, gravure printing is preferred due to its productivity, suitability for printing on plastic film, and high resolution of the image.

[0095] Thus, according to the present invention, a portion of the seal portion on one side of the peripheral edge of the packaging bag is a protruding seal portion that curves and protrudes inward towards the packaging bag, and this protruding seal portion is an automatic steam release mechanism during heating and cooking, and this protruding seal portion is sealed with weaker seal strength, a narrower seal width, or both compared to other seal portions, and a notch is provided in the seal portion on the other side opposite to this seal portion, at a position directly facing the protruding seal portion, thereby providing a packaging bag that has an automatic steam release mechanism and is suitable for microwave heating and cooking, and even if the tear line for opening does not perfectly align on the front and back of the body of the packaging bag and misalignment occurs, it is possible to provide a packaging bag that can be easily opened and separated by the tear line. [Explanation of Symbols]

[0096] 1. Seal on the left side 2. The seal on the right side. 3. Protruding sticker section 4...cuts 5...Peeling part 6. Cut line on the same part of the front side 7. Cut line on the rear of the torso 8. Center of volume 9...right side end of body 10. Plastic film layer with straight-line cutting properties 11. Plastic film substrate layer 12...Adhesive layer 13. Inorganic compound vapor-deposited layer 14. Plastic film 15. Sealant layer 16. Printing ink layer 17. Front side of the torso 18. Rear torso 20. Gas barrier film 30-layer structure 40...water vapor 100...packaging bag a... Vertical width of the protruding sticker portion b...Misalignment of the cut 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 vapor-deposited layer is formed on the surface of the third plastic film layer that faces the second 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. 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. The plastic film layer having straight-line cutting properties is formed of polyolefin or polyamide. A packaging bag characterized by the following features.

3. The packaging bag according to claim 1 or 2, 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