Easy-open packaging bag and method for manufacturing the same

Abstract

To provide an easy-openable container which is excellent in a tearing property, a barrier property, productivity, and appearance, and to provide a manufacturing method which manufactures the easy-openable container with good moldability.SOLUTION: There is provided an easy-openable packaging bag which is sealed by heat-sealing a lamination film. The lamination film includes: an inner layer film; an intermediate layer film where an opening induction cut having a small width is formed; and an outer layer film. Further, there is provided a manufacturing method of the easy-openable packaging bag which is suitable for manufacturing the packaging bag.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a packaging bag excellent in tear-opening property that is sealed by heat-sealing a laminated film, and a method for manufacturing the same.

Background Art

[0002] It is a widely used technique to process an easy-opening line for easily opening a bag by breaking a film on a flexible packaging material bag. However, when cutting is performed on the outermost layer of the laminated film constituting the packaging material, a problem arises in that the barrier performance deteriorates. To solve this problem, in Patent Document 1, a packaging bag having a multilayer structure including a light-shielding layer for controlling laser processing, a support layer for protecting the barrier layer, a barrier layer, and a thermoplastic resin layer is proposed on the inner surface side. However, in addition to the high cost due to multi-layerization, there is a problem in that the transparency is low because it includes a light-shielding layer.

[0003] On the other hand, as disclosed in Patent Document 2, when a cutting line is processed at the tearing portion of the intermediate layer film of a packaging bag made of a laminated film provided with an intermediate layer between the barrier layer and the inner layer, it is possible to suppress a decrease in barrier properties. However, when the intermediate layer film is cut into a single layer and then laminated, if the peripheral portion of the cut of the intermediate layer overlaps vertically during bonding, a backbone-like undulation portion is formed during winding, resulting in poor appearance. For this reason, there were problems in formability such as the need to adjust the slack for each raw roll.

[0004] Further, Patent Document 3 discloses a pouch in which a defective portion of a laminated film using a barrier film provided with an opening induction defect in an intermediate layer is covered with barrier ink. According to this method, the barrier property is ensured, but since the number of steps increases, the productivity is low and the cost is high.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The object of the present invention is to provide an easy-open container with excellent tear resistance, barrier properties, productivity, and appearance, and to provide a manufacturing method for producing an easy-open container with good moldability. [Means for solving the problem]

[0007] According to the present invention, there is an easy-to-open packaging bag that is sealed by heat sealing a laminated film, wherein the laminated film comprises an inner layer film, an intermediate layer film having an opening-inducing defect with a width of 0 μm to 20 μm, and an outer layer film.

[0008] The aforementioned easy-open packaging preferably has an opening-inducing defect with a width of 0 μm or more and less than 10 μm.

[0009] In the aforementioned easy-open packaging, it is preferable that the tip of the opening-inducing defect reaches the inside of the inner or outer film.

[0010] The aforementioned easy-open packaging preferably has multiple opening-inducing defects.

[0011] In the aforementioned easy-open packaging, it is preferable that the intermediate film has barrier properties.

[0012] The aforementioned easy-open packaging preferably has an intermediate film made of polyamide or polyester.

[0013] The aforementioned easy-open packaging preferably has an outer layer film that is a biaxially oriented film with a molecular orientation angle of less than 49 degrees.

[0014] The aforementioned easy-open packaging preferably has an outer layer film made of polyamide or polyester.

[0015] The aforementioned easy-open packaging preferably has a steam venting mechanism.

[0016] Furthermore, according to the present invention, a method for manufacturing a packaging bag that is sealed by heat sealing a laminated film is provided, wherein the laminated film comprises an inner layer film, at least one intermediate layer film, and an outer layer film, and the method for manufacturing an easily openable packaging bag includes a first lamination step of laminating the intermediate layer film and the inner layer film, a step of applying an opening-inducing defect with a width of 0 μm to 20 μm from the intermediate layer side of the laminated film, and a second lamination step of laminating the film with the opening-inducing defect applied to the outer layer film.

[0017] Furthermore, according to the present invention, a method for manufacturing a packaging bag that is sealed by heat sealing a laminated film is provided, wherein the laminated film comprises an inner layer film, at least one intermediate layer film, and an outer layer film, and the method includes a first lamination step of laminating the intermediate layer film and the outer layer film, a step of applying an opening-inducing defect with a width of 0 μm to 20 μm from the intermediate layer side of the laminated film, and a second lamination step of laminating the film with the opening-inducing defect applied to the inner layer film.

[0018] The method for manufacturing the easy-open packaging bag preferably includes a heat treatment step in one of the steps following the second lamination step.

[0019] In the method for manufacturing the easy-open packaging bag, it is preferable that the width of the opening-inducing defect is 0 μm or more and less than 10 μm.

[0020] In the method for manufacturing the aforementioned easy-open packaging bag, it is preferable that multiple opening-inducing defects are formed.

[0021] The manufacturing method of the easy-opening packaging bag preferably has a middle layer film with barrier properties.

[0022] The manufacturing method of the easy-opening packaging bag preferably has a middle layer film made of polyamide or polyester.

[0023] The manufacturing method of the easy-opening packaging bag preferably has an outer layer film that is a biaxially stretched film with a molecular orientation angle of less than 49 degrees.

[0024] The manufacturing method of the easy-opening packaging bag preferably has an outer layer film made of polyamide or polyester.

Advantages of the Invention

[0025] According to the present invention, it is possible to provide an easy-opening container excellent in tear resistance, barrier properties, productivity, and appearance, and a manufacturing method for manufacturing the easy-opening container with good formability.

[0026] In the present invention, by using a laminated film in which an opening induction flaw with a small flaw width is formed in the middle layer film, an easy-opening packaging bag excellent in tear resistance, barrier properties, and appearance can be obtained. Moreover, since the opening induction flaw reaches inside the inner layer film or the outer layer film, a packaging bag with better tear resistance can be obtained. Furthermore, by providing a plurality of opening induction flaws, a packaging bag excellent in productivity can be obtained.

[0027] In the configuration using a barrier film for the middle layer film, the superiority of maintaining the barrier properties by controlling the width of the opening induction flaw can be obtained. Also, by using polyamide or polyester for the middle layer film, the packaging bag can be provided with the necessary strength, barrier properties, and impact resistance.

[0028] By using a biaxially stretched film with a molecular orientation angle of less than 49 degrees for the outer layer film and a film with an opening induction flaw formed in the middle layer, a packaging bag with good tear resistance can be obtained. Furthermore, by using polyamide or polyester for the outer layer film, the packaging bag can be given the necessary strength, barrier properties, and impact resistance.

[0029] Furthermore, the inclusion of a steam release mechanism allows for easy heating in a microwave oven without tearing the bag, and the heated contents can be easily removed.

[0030] By laminating the intermediate layer film and the inner layer film together, then applying an opening-induced defect process from the intermediate layer film side, and finally laminating it with the outer layer film, it is possible to stably form small-width induced defects and multiple induced defects. Furthermore, by performing a heat treatment process after laminating the intermediate layer film and the outer layer film, the width of the induced defects can be narrowed, making it possible to form induced defects with smaller defect widths more stably.

[0031] Furthermore, by laminating the intermediate film and the outer film together, then applying an opening-induced defect process from the intermediate film side, and finally laminating it with the inner film, it is possible to stably form small-width induced defects and multiple induced defects. Furthermore, by applying a heat treatment process after laminating the intermediate layer film and the inner layer film, the width of the induced defects can be narrowed, making it possible to form induced defects with smaller defect widths more stably. [Brief explanation of the drawing]

[0032] [Figure 1] This figure shows one embodiment of a laminated film having an opening-inducing defect used in the present invention. [Figure 2] The images show cross-sectional views of an example of a laminated film used in the packaging bag of the present invention. (A) is a cross-sectional view of a laminated film with an opening-inducing defect having a defect width of 10 μm, and (B) is a cross-sectional view of a laminated film with an opening-inducing defect having a defect width of 0 μm. [Figure 3] This is a schematic diagram showing a part of the manufacturing process of a laminated film according to one aspect of the present invention. [Modes for carrying out the invention]

[0033] (packaging bag) <Inner layer film> Various known materials can be used as the innermost layer film of the packaging bag of the present invention. For example, heat-sealable polyolefins can be used. Examples of such polyolefins include low-density, medium-density, or high-density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, ethylene-propylene copolymer, polybutene-1, poly-methyl-1-pentene, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), and ethylene-acrylic acid ester copolymer. These can be used individually or as blends of two or more. Propylene-based polymers are particularly suitable from the viewpoint of heat resistance, and homopolypropylene, as well as random copolymers and block copolymers mainly composed of propylene, can be used.

[0034] <Intermediate layer film> In the present invention, at least one intermediate layer can be provided between the inner film and the outer film. Various known materials can be used as the intermediate layer film, such as polyamide and polyester. Examples of polyamides include nylon 6, nylon 66, nylon 46, nylon 69, nylon 610, nylon 612, nylon 11, nylon 12, and nylon MXD6, but nylon 6 or nylon 66 are preferred due to their ease of handling. As polyesters, condensed polymers obtained by polymerization from monomers comprising aromatic dicarboxylic acids or aliphatic dicarboxylic acids and diols, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), are preferred. Among these, polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), or blends thereof, which have low hygroscopicity, are particularly preferred.

[0035] <Outer film> Various known materials can be used as the outer layer film of the present invention, for example, polyamide, polyester, and the like. Examples of polyamides include nylon 6, nylon 66, nylon 46, nylon 69, nylon 610, nylon 612, nylon 11, nylon 12, and nylon MXD6, but nylon 6 or nylon 66 are preferred due to their ease of handling. As polyesters, condensed polymers obtained by polymerization from monomers comprising aromatic dicarboxylic acids or aliphatic dicarboxylic acids and diols, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), are preferred. Among these, PBT and PET are particularly preferred. Furthermore, when using nylon or PBT for the outer layer film, a biaxially oriented film formed by the tubular method is preferred. This is because, in addition to the strength, heat resistance, and transparency that biaxially oriented films possess, they have high isotropy, making it less likely for quality differences to occur depending on the location of the film cut.

[0036] To prevent the packaging bag from bursting when dropped, it is preferable to use highly impact-resistant PBT for at least one of the outer or middle layers. Using it for the outer layer is even more effective in improving the impact resistance of the packaging bag.

[0037] Preferably, a barrier layer is formed in at least one of the outer layer or intermediate layer. The barrier layer is formed by depositing inorganic materials such as silicon oxide, or ceramics such as alumina, or carbon, using chemical vapor deposition (CVD), vacuum deposition, sputtering, ion plating, or the like. Alternatively, a coating layer containing a barrier resin coating agent, such as a polycarboxylic acid polymer, vinylidene chloride, or ethylene vinyl alcohol copolymer, may be formed.

[0038] Conventionally, it has been known that laminated films using biaxially oriented films with a large molecular orientation angle suffer from impaired tear resistance. In biaxially oriented films, the angle at which the molecular orientation direction intersects with the film's flow direction or width direction is called the molecular orientation angle. When the film's flow direction is set to an angle of 0°, the molecular orientation angle generally tends to be smaller in the central part of the film and larger in the outer part. In other words, if only films with a small molecular orientation angle can be used, only the central part will be used, leading to increased costs.

[0039] However, in the present invention, even when a biaxially oriented film is used as the outer layer film, the tear resistance of the film having an opening-inducing defect in the intermediate layer is not easily impaired, and a biaxially oriented film with a molecular orientation angle of less than 49 degrees can be used.

[0040] <Opening-induced flaw> It is preferable to form an opening-inducing defect in the intermediate layer film at the location corresponding to the tear-open point of the packaging bag.

[0041] Figure 1 is a diagram illustrating an opening-inducing defect formed in the intermediate layer of the present invention. One embodiment of the present invention, a laminated film 1, consists of an outer layer film 2, an intermediate layer film 3, and an inner layer film 4, and an opening-inducing defect 5 extending from the outer layer side is formed in the intermediate layer film 3. In this laminated film 1, the width of the opening-inducing defect 5 means the opening width L of the defect at the interface between the outer layer film 2 and the intermediate layer film 3. Figure 2 is a polarized light microscope image of a cross-section of an example of a laminated film used in the packaging bag of the present invention. (A) is a cross-sectional image of a laminated film with a width L of the tamper-evident flaw 5 of 10 μm, and (B) is a cross-sectional image of a laminated film with a width L of the tamper-evident flaw 5 of 0 μm. The opening of an entrenched defect becomes smaller and more closed after film lamination or heat treatment than before lamination. For example, an entrenched defect with a width of 0 μm is completely closed after film lamination or heat treatment.

[0042] The width of the opening-inducing defect is preferably 0 μm or more and 80 μm or less, and particularly preferably 0 μm or more and 20 μm or less. More preferably, it is 0 μm or more and less than 10 μm. When an opening-inducing defect with a defect width of 0 μm to 20 μm is provided, even when a barrier film is used in the intermediate layer, it is possible to provide easy opening while suppressing a decrease in barrier performance. When the defect width is 0 μm to less than 10 μm, particularly high barrier performance can be maintained. Furthermore, laminated films with open-tear-inducing defects having a defect width of 0 μm to 20 μm have excellent appearance, and in particular, laminated films with defects having a defect width of 0 μm to less than 10 μm are indistinguishable from processed films by the naked eye, making it possible to obtain highly aesthetically pleasing packaging bags. In other words, by controlling the width of the defects, it is possible to provide packaging bags with excellent barrier properties, appearance, and ease of opening.

[0043] In one embodiment of the present invention, a packaging bag can be obtained that is easy to open and has an excellent appearance, even when an opening-inducing defect of 0 μm to 20 μm is provided in the barrier film of the vapor-deposited PET, without reducing the barrier properties, by using PBT for the outer layer film, a vapor-deposited PET intermediate layer film, and polypropylene for the inner layer film.

[0044] Furthermore, considering barrier performance, it is preferable that the tamper-evident flaw be between 0 μm and 20 μm. However, it is also possible to process the film with a flaw between 20 μm and 80 μm and use a barrier film on the outer layer to enhance barrier performance. For example, a film configuration using vapor-deposited PBT for the outer layer, vapor-deposited PET with tamper-evident flaws for the intermediate layer, and polypropylene for the inner layer can be used.

[0045] In the present invention, it is preferable that there be multiple opening-inducing defects. In conventional packaging bags with a single cut line formed in the intended opening area, easy opening is not achieved unless the cut lines on the front and back perfectly align. Furthermore, if an opening assist notch is provided in the heat-sealed area, the notch must also be aligned. These adjustments are time-consuming and likely to increase the waste rate, thus reducing productivity. However, in the packaging bag with multiple opening-inducing defects according to the present invention, the bag is opened by either of the multiple defects and the nearest defect on the opposite side, making position adjustment easy, resulting in fewer defects and higher productivity. In other words, it is possible to provide packaging bags that offer excellent productivity and ease of opening.

[0046] In the present invention, the number of opening-inducing defects can be any number and is not particularly limited, but if there are too few, the objective of facilitating position adjustment cannot be achieved, and if there are too many, the barrier performance may be impaired, so 3 to 5 defects are preferred. Furthermore, while the distance between each opening-inducing defect can be determined arbitrarily, if the distance is too large, the ability to open will be impaired, so a distance of 2 mm or less is preferable.

[0047] The cross-sectional shape of the induced defect may be V-shaped or square, and is not limited to these. Furthermore, the tear line caused by the induced defect may be straight, curved, or arc-shaped, and is not limited to these. In addition, the tear line caused by the induced defect may be formed continuously or intermittently. When formed intermittently, in order to avoid tearing in an unintended direction from the area where the defect is missing, the processing gap between the defects is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0048] (Manufacturing method for packaging bags) In one embodiment of the present invention, a packaging bag is manufactured by a manufacturing process that includes a first lamination step of laminating an intermediate layer film and an inner layer film, a step of applying an opening-inducing defect with a width of 0 μm to 20 μm from the intermediate layer side of the laminated film, and a second lamination step of laminating the film with the opening-inducing defect to an outer layer film, thereby creating a laminated film having an opening-inducing defect, and then heat-sealing it. In another embodiment, a laminated film having an opening-inducing defect is created by a manufacturing process that includes a first lamination step of laminating an intermediate layer film and an outer layer film, a step of applying an opening-inducing defect with a width of 0 μm to 20 μm from the intermediate layer side of the laminated film, and a second lamination step of laminating the film with the opening-inducing defect to an inner layer film, and a packaging bag is manufactured by heat sealing this laminated film. Figure 3 illustrates an example of a method for manufacturing a laminated film having an open-tear defect used in the packaging bag of the present invention. An intermediate layer film 3 unwound from an intermediate layer film unwinding roll 10 and an inner layer film 4 unwound from an inner layer film unwinding roll 11 are bonded together by laminating rolls 12a and 12b. Then, the cutter blade 13a of a cutter 13 is moved from the intermediate layer side along the roll 13b to form an open-tear defect 5. Next, the outer layer film 2 unwound from an unwinding roll 14 is bonded to the side with the open-tear defect 5 formed by laminating rolls 15a and 15b, and then wound onto a winding roll 16.

[0049] <Processing of opening-induced defects> Methods for processing the opening-inducing defects include groove processing with a rotary cutter, perforation processing, and laser processing, but in the present invention, groove processing with a cutter is preferred. Laser processing can cause molten film around the cut area to protrude, potentially creating gaps in the laminate and forming spine-like ridges during winding. Furthermore, safety concerns arise when using organic solvents. Therefore, it is preferable to use a cutter that can easily form opening guide marks of the desired opening width without causing such problems.

[0050] For processing the opening-inducing defect, it is preferable to perform a half-cut process from the intermediate layer side after bonding the intermediate layer and the inner or outer layer. The tip of the defect may remain within the intermediate layer or reach the inner or outer layer, but it is preferable that it reaches the inner or outer layer to obtain higher tear resistance. Furthermore, when the intermediate layer consists of two or more laminated layers, it is preferable that the tip reaches the layer of the intermediate layer closest to the inner or outer layer, and more preferably that it reaches the inner or outer layer.

[0051] When processing is performed after laminating the intermediate layer with the inner or outer layer, the film has thickness, allowing for the stable formation of consistent-shaped defects in a rigid film. Furthermore, since a portion of the film is not completely cut in the half-cut process, the film is less likely to meander, resulting in good transportability. Therefore, when laminating the processed film with the outer layer, unlike when the intermediate layer alone is cut, the area around the cut does not overlap, preventing the formation of a spine-like undulation during winding. This allows for the stable formation of a laminated film with consistent-shaped opening-inducing defects.

[0052] When the inner layer is thicker than the outer layer, or when a highly flexible material such as polyolefin is used for the inner layer, performing the tamper-evident repair process after bonding the intermediate layer and the inner layer results in more stable molding. Furthermore, when forming tamper-evident repairs on a laminated film formed by bonding the outer layer and the intermediate layer, it is necessary to adjust the depth of the cut so as not to impair the barrier properties, impact resistance, and other performance characteristics required of the outer layer. Therefore, performing the tamper-evident repair process on a laminated film formed by bonding the intermediate layer and the inner layer is preferable from a productivity standpoint.

[0053] Conventional manufacturing methods, which have poor moldability, cannot process opening-inducing defects with narrow defect widths or process multiple opening-inducing defects stably at regular intervals. However, in the manufacturing method of the present invention, by making simple adjustments to the type of cutter blade and the clearance between the roll and the blade, defects of the same size can be processed stably, and the width of the defects after bonding does not deviate from the dimensions. In other words, it is possible to provide a manufacturing method for producing laminated films with good moldability, including an intermediate layer processed with a narrow opening-inducing defect and multiple opening-inducing defects.

[0054] <Heat treatment process> In the manufacturing method according to the present invention, it is preferable to perform heat treatment after laminating the intermediate layer and the inner layer, applying an open-cut induced flaw treatment, and laminating with the outer layer film, or after laminating the intermediate layer and the outer layer, applying an open-cut induced flaw treatment, and laminating with the inner layer film. This makes it possible to narrow the flaw width. For example, by applying heat treatment to a laminated film that had a flaw width of 10 μm when the outer layer film was attached, the flaw width can be narrowed to 0 μm. By adding this process, it becomes easier to control the width of defects, and packaging bags with high barrier properties and a good appearance can be formed stably.

[0055] Various heat treatment conditions can be applied in this invention, such as 35°C for 5 days, 50°C for 2 days, or 90°C for 1 minute. Furthermore, this process can be made more efficient if it is carried out in conjunction with processes such as curing, which is usually performed during film molding, or sterilization of the pouch. The heat treatment process can be performed immediately after the laminated film is formed, or after the laminated film has been stored for a certain period of time. It can also be performed after the packaging bags have been made.

[0056] When shrinking the width of a defect by heat treatment, it is preferable to use a film with an appropriate heat shrinkage rate as the outer layer film to achieve the desired result. Examples include, but are not limited to, biaxially oriented PBT film.

[0057] <Lamination of film> The laminated film used in this invention can be obtained by a conventional dry lamination method. The adhesive can be one commonly used in the manufacture of film packaging; for example, a polyurethane-based adhesive can be used. The process of creating an opening-inducing flaw in a film with an inner layer and an intermediate layer, and then laminating it with an outer layer film, or the process of creating an opening-inducing flaw in a film with an outer layer and an intermediate layer, and then laminating it with an inner layer film, can be done in-line, or the films can be stored after the flawing process and then laminated at a later date. Lamination may be carried out by known co-extrusion lamination methods, such as lamination of an inner layer film and an intermediate layer film, or lamination of multiple intermediate layer films.

[0058] <Forming of packaging bags> The packaging bag according to the present invention can be formed by using the laminated film and overlapping the inner layer films so that they face each other, then heat-sealing them. Examples of pouch forms include, but are not limited to, four-sided sealed pouches and standing pouches.

[0059] The packaging bag according to the present invention may have a steam release mechanism. This releases the internal pressure inside the packaging bag during microwave heating, preventing the bag from bursting. When removing the contents after heating, using a packaging bag with excellent tear resistance allows the bag to be opened without the contents adhering to the opening area scattering and soiling the surroundings.

[0060] Additionally, an opening assist notch may be provided in the heat-sealed portion. The notch shape can be an I-notch, U-notch, multi-notch, or any other shape commonly used in film packaging. [Examples]

[0061] The present invention will now be specifically described with reference to examples, but these examples represent only one aspect of the present invention and are not limited thereto.

[0062] <Examples 1-4, Comparative Example 1> Five types of packaging bags were prepared, each having three open-tear-inducing scratches ranging from 0 μm to 30 μm at 1 mm intervals in the intermediate layer. These bags were then sealed with 180 mL of water, heated in a water bath, and evaluated for their openability and measured for oxygen permeability. Oxygen permeability detection tests were also performed on the pouches from Example 2 and Example 4.

[0063] [Pouch preparation] In the first lamination process, a 12 μm thick aluminum oxide vapor-deposited biaxially oriented polyethylene terephthalate film was used as the intermediate layer film, and a 70 μm thick polypropylene film was used as the inner layer film. These were laminated using a polyurethane-based adhesive on the polyethylene terephthalate film side of the intermediate layer film by dry lamination. A half-cut opening-inducing defect was formed on the vapor-deposited biaxially oriented polyethylene terephthalate film side of the laminated film created in the first lamination process using a rotary cutter. In the second lamination process, a 15 μm polybutylene terephthalate film coated with a polyurethane-based adhesive was laminated onto the vapor-deposited biaxially oriented polyethylene terephthalate film surface of the laminated film with tamper-evident defects using a dry lamination method to produce laminated films with various tamper-evident defect widths. By heat-sealing the laminated film created in the second lamination process described above, a flat pouch with a height of 170 mm and a width of 130 mm was produced.

[0064] [Heating the pouch by boiling water] The pouch was placed in a Yamato high-temperature water bath (BF600) set to 100°C and heated for 20 minutes.

[0065] [Evaluation of delamination upon opening the pouch] Each pouch, warmed in a hot water bath, was visually evaluated by tearing open the portion. A circle (○) was used to indicate that the pouch was opened along the opening guideline, a triangle (△) was used if a portion of the outer film had detached from the guideline, and an X (×) was used if the outer film had completely detached from the guideline.

[0066] [Measurement of oxygen permeability] A sample was cut from each pouch, and the oxygen permeability (cc / m³) was measured using the MOCON method at a temperature of 23°C and a relative humidity of 60%. 2 We measured (day·atm).

[0067] Table 1 shows the results of the evaluation of ease of opening and the measurement of oxygen permeability.

[0068] [Table 1]

[0069] Table 1 shows that in the range where the width of the opening-induced defect is between 0 μm and 20 μm, the oxygen permeability was 0.6 or less, indicating good barrier properties.

[0070] [Oxygen permeability detection test] The pouches prepared using the above method for Examples 2 and 4 were filled with leucomethylene blue solution, sealed, and subjected to retort treatment at 121°C for 30 minutes. After being removed from the sterilizer and left for 24 hours, the inside was observed from the outside.

[0071] As a result, the pouch in Example 2 showed no discoloration around the opening-inducing flaw, demonstrating good barrier properties. On the other hand, the pouch in Example 4 showed very slight discoloration around the opening-inducing flaw, confirming that films with flaw widths of less than 10 μm exhibit higher barrier properties. [Industrial applicability]

[0072] According to the present invention, an easy-open container with excellent tear resistance, barrier properties, productivity, and appearance can be obtained. Furthermore, an easy-open container can be manufactured using a manufacturing method that offers excellent moldability. [Explanation of symbols]

[0073] 1. Laminated film, 2. Outer layer film, 3. Intermediate layer film, 4. Inner layer film, 5. Opening guide, 10. Intermediate layer film unwinding roll, 11. Inner layer film unwinding roll, 12. Laminating roll, 13. Cutter, 14. Outer layer film unwinding roll, 15. Laminating roll, 16. Rewinding roll.

Claims

1. A method for manufacturing a packaging bag that is sealed by heat sealing a laminated film, The laminated film comprises an inner layer film, at least one intermediate layer film, and an outer layer film. A first lamination step involves bonding the intermediate layer film and the inner layer film, The process involves applying an open-tear-inducing defect to the intermediate layer side of the laminated film, This process includes a second lamination step in which the film with the opening-inducing defect processing is bonded to the outer layer film, One of the steps following the second lamination step includes a heat treatment step, The heat treatment step is a method for manufacturing an easy-open packaging bag, wherein the width of the opening-inducing defect is narrowed to a width of 0 μm or more and 20 μm or less.

2. A method for manufacturing a packaging bag that is sealed by heat sealing a laminated film, The laminated film comprises an inner layer film, at least one intermediate layer film, and an outer layer film. A first lamination step involves bonding the intermediate layer film and the outer layer film, The process involves applying an open-tear-inducing defect to the intermediate layer side of the laminated film, This process includes a second lamination step in which the film with the opening-inducing defect processing is bonded to the inner layer film, One of the steps following the second lamination step includes a heat treatment step, The heat treatment step is a method for manufacturing an easy-open packaging bag, wherein the width of the opening-inducing defect is narrowed to a width of 0 μm or more and 20 μm or less.

3. A method for manufacturing an easy-open packaging bag according to claim 1 or 2, comprising an outer layer film that shrinks due to heat treatment.

4. A barrier layer is formed on the aforementioned intermediate film. A method for manufacturing an easy-open packaging bag according to any one of claims 1 to 3, wherein the opening-inducing defect processing reaches the interior of the barrier layer.

5. The method for manufacturing an easy-to-open packaging bag according to claim 1, wherein the heat treatment step is to heat-shrink the outer layer film.

6. The method for manufacturing an easy-open packaging bag according to any one of claims 1 to 5, wherein the heat treatment step is to heat shrink an impact-resistant film.

7. A method for manufacturing an easy-open packaging bag according to any one of claims 1 to 6, wherein the width of the opening-inducing defect is 0 μm or more and less than 10 μm.

8. The method for manufacturing an easy-open packaging bag according to any one of claims 1 to 7, wherein the heat treatment step involves heat shrinking a film containing polybutylene terephthalate.

Images