Easy-openable packaging bag and manufacturing method of 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 having excellent tear-openability, which is sealed by heat-sealing a laminated film, and a method for producing the same. [Background technology]

[0002] It is a widely used technique to form an easy-open line on a soft packaging bag in order to make it easier to open the bag by breaking the film. However, when cutting is applied to the outermost layer of the laminated film that constitutes the packaging material, a reduction in barrier performance becomes a problem. To solve this problem, Patent Document 1 proposes a multi-layered packaging bag that includes a light-shielding layer for controlling the laser processing, a support layer for protecting the barrier layer, a barrier layer, and a thermoplastic resin layer on the inner side. However, the multi-layered structure increases the cost, and the inclusion of the light-shielding layer causes problems such as low transparency.

[0003] On the other hand, as disclosed in Patent Document 2, when a cutting line is formed at the tearing location of the intermediate layer film of a packaging bag made of a laminated film having an intermediate layer between the barrier layer and the inner layer, deterioration of the barrier properties can be suppressed. However, when the intermediate layer film is cut into single layers and then laminated, if the cut peripheral portions of the intermediate layer overlap one another during lamination, a backbone-like undulation is formed when the film is wound up, resulting in poor appearance. This poses problems in formability, such as the need to adjust the slack for each roll of raw material.

[0004] Patent Document 3 discloses a pouch in which a laminated film using a barrier film with an opening-inducing defect in the middle layer is covered with a barrier ink. This method ensures the barrier properties, but increases the number of steps, resulting in low productivity and high costs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-150772 A [Patent Document 2] Japanese Patent Application Publication No. 4-311466 [Patent Document 3] JP 2020-44819 A Summary of the Invention [Problem to be solved by the invention]

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

[0007] According to the present invention, there is provided an easy-open packaging bag which is sealed by heat sealing a laminated film, characterized in that the laminated film comprises an inner layer film, a middle layer film having an opening-inducing defect having a width of 0 μm or more and 20 μm or less, and an outer layer film.

[0008] The easy-open packaging body preferably has an opening-induced flaw width of 0 μm or more and less than 10 μm.

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

[0010] The easy-open packaging body preferably has a plurality of opening-inducing defects formed thereon.

[0011] In the easy-open packaging body, it is preferable that the intermediate layer film has a barrier property.

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

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

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

[0015] The easy-open packaging body preferably has a steam release mechanism.

[0016] Furthermore, according to the present invention, there is provided a method for producing an easy-open packaging bag, which is sealed by heat-sealing a laminated film, the laminated film comprising an inner layer film, at least one intermediate layer film, and an outer layer film, the method including a first lamination step of bonding the intermediate layer film and the inner layer film together, a step of applying an opening-inducing defect treatment having a width of 0 μm or more and 20 μm or less from the intermediate layer side of the bonded films, and a second lamination step of bonding the film that has been subjected to the opening-inducing defect treatment together with the outer layer film.

[0017] Furthermore, according to the present invention, there is provided a method for manufacturing an easy-open packaging bag, which is sealed by heat-sealing a laminated film, the laminated film comprising an inner layer film, at least one intermediate layer film, and an outer layer film, the method including a first lamination step of bonding the intermediate layer film and the outer layer film together, a step of applying an opening-inducing defect treatment having a width of 0 μm or more and 20 μm or less from the intermediate layer side of the bonded film, and a second lamination step of bonding the film that has been subjected to the opening-inducing defect treatment to the inner layer film.

[0018] The method for producing an easy-open packaging pouch preferably includes a heat treatment step in any of the steps subsequent to the second lamination step.

[0019] In the method for producing an easy-open packaging bag, the width of the opening-induced defect is preferably 0 μm or more and less than 10 μm.

[0020] In the method for producing an easily openable packaging bag, a plurality of opening-inducing defects are preferably formed.

[0021] In the method for producing an easy-open packaging bag, it is preferable that the intermediate layer film has a barrier property.

[0022] In the method for producing an easy-open packaging bag, the intermediate layer film is preferably made of polyamide or polyester.

[0023] In the method for producing an easy-open packaging bag, the outer layer film is preferably a biaxially oriented film having a molecular orientation angle of less than 49 degrees.

[0024] In the method for producing the easy-open packaging bag, the outer layer film is preferably made of polyamide or polyester. Effect of the Invention

[0025] The present invention can provide an easy-open container that is excellent in tearability, barrier properties, productivity, and appearance, and can also provide a method for producing an easy-open container with good moldability.

[0026] In the present invention, by using a laminated film in which an opening-inducing defect with a small defect width is formed in an intermediate layer film, an easily openable packaging bag excellent in tearability, barrier properties and appearance can be obtained. In addition, since the opening-inducing defects reach the inside of the inner layer film or the outer layer film, a packaging bag with better tearability can be obtained. Furthermore, by providing a plurality of opening-inducing defects, a packaging bag with excellent productivity can be obtained.

[0027] In a configuration in which a barrier film is used as the intermediate layer film, it is possible to obtain the advantage of maintaining the barrier properties by controlling the width of the opening-induced flaw. Furthermore, by using polyamide or polyester for the intermediate layer film, it is possible to provide the packaging bag with the strength, barrier properties, and impact resistance required.

[0028] By using a biaxially oriented film with a molecular orientation angle of less than 49 degrees for the outer layer film and a film with opening-inducing defects formed for the middle layer, a packaging bag with good tearability can be obtained. Furthermore, by using polyamide or polyester for the outer layer film, it is possible to provide the packaging bag with the necessary strength, barrier properties, and impact resistance.

[0029] Furthermore, by providing a steam release mechanism, the bag can be heated easily in a microwave oven without breaking, and the heated contents can be easily removed.

[0030] After the intermediate layer film and the inner layer film are bonded together, opening induced defects are created from the intermediate layer film side, and then the film is bonded to the outer layer film, making it possible to stably form induced defects with small defect widths and multiple induced defects. Furthermore, by carrying out a heat treatment process after laminating the intermediate layer film and the outer layer film, the width of the induced flaws can be narrowed, and induced flaws with smaller widths can be formed more stably.

[0031] In addition, after the intermediate layer film and the outer layer film are bonded together, opening induced defects are created from the intermediate layer film side, and then the film is bonded to the inner layer film, thereby making it possible to stably form induced defects with small defect widths and multiple induced defects. Furthermore, by carrying out a heat treatment process after laminating the intermediate layer film and the inner layer film, the width of the induced flaws can be narrowed, and induced flaws with smaller flaw widths can be formed more stably. [Brief description of the drawings]

[0032] [Figure 1] FIG. 2 is a diagram showing one embodiment of a laminated film having an opening-induced defect formed thereon, used in the present invention. [Diagram 2] 3A and 3B are cross-sectional photographs of an example of a laminated film used in the packaging bag of the present invention, where (A) is a cross-sectional photograph of a laminated film on which an opening-induced defect measuring 10 μm in width has been formed, and (B) is a cross-sectional photograph of a laminated film on which an opening-induced defect measuring 0 μm in width has been formed. [Diagram 3] FIG. 2 is a schematic diagram showing a part of a manufacturing process of a laminated film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] (packaging bag) <Inner layer film> The inner layer film, which is the innermost layer of the packaging bag of the present invention, can be made of various known materials, for example, polyolefins having heat sealability. Examples of such polyolefins include low-density, medium-density, or high-density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, ethylene-propylene copolymers, polybutene-1, poly4-methyl-1-pentene, ethylene-butene-1 copolymers, propylene-butene-1 copolymers, ethylene-propylene-butene-1 copolymers, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers), and ethylene-acrylic acid ester copolymers. These can be used alone or as a blend of two or more kinds. In particular, from the viewpoint of heat resistance, propylene-based polymers are suitable, and homopolypropylene, 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 layer film and the outer layer film. As the intermediate layer film, various known materials can be used, such as polyamide and polyester. Examples of polyamide include nylon 6, nylon 66, nylon 46, nylon 69, nylon 610, nylon 612, nylon 11, nylon 12, and nylon MXD6. From the viewpoint of ease of handling, nylon 6 or nylon 66 is preferred. As the polyester, preferred are condensation polymers obtained by polymerization of monomers having aromatic dicarboxylic acid or aliphatic dicarboxylic acid and diol as constituent components, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. Among these, it is particularly preferred to use polybutylene terephthalate (PBT) or polyethylene terephthalate (PET), which has low hygroscopicity, or blends thereof.

[0035] <Outer film> For the outer layer film of the present invention, various known materials can be used, such as polyamide and polyester. Examples of polyamide include nylon 6, nylon 66, nylon 46, nylon 69, nylon 610, nylon 612, nylon 11, nylon 12, and nylon MXD6. From the viewpoint of ease of handling, nylon 6 or nylon 66 is preferred. As the polyester, preferred are condensation polymers obtained by polymerization of monomers having aromatic dicarboxylic acid or aliphatic dicarboxylic acid and diol as constituent components, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Among these, PBT and PET are particularly preferred. Furthermore, when nylon or PBT is used for the outer layer film, a biaxially oriented film formed by the tubular method is preferable, because in addition to the strength, heat resistance, and transparency that biaxially oriented films have, they also have high isotropy, and there is little difference in quality depending on the position where the film is taken.

[0036] In order to prevent the packaging bag from being dropped and broken, it is preferable to use PBT, which has high impact resistance, in at least one of the outer layer or intermediate layer. When used in the outer layer, it is more effective in improving the impact resistance of the packaging bag.

[0037] It is preferable that at least one of the outer layer and the intermediate layer is provided with a barrier layer. The barrier layer is formed by depositing an inorganic material such as silicon oxide, a ceramic material such as alumina, carbon, etc., by chemical vapor deposition (CVD), vacuum deposition, sputtering, ion plating, etc. Alternatively, a coating layer containing a barrier resin coating agent made of a polycarboxylic acid polymer, vinylidene chloride, an ethylene-vinyl alcohol copolymer, etc. may be formed.

[0038] It has been known that laminated films using biaxially stretched films with a large molecular orientation angle have poor tearability. In biaxially stretched films, the cross angle between the molecular orientation direction and the film's machine direction or width direction is called the molecular orientation angle. When the machine direction of the film is set as an angle of 0°, the molecular orientation angle generally tends to be small in the center of the film and large in the outermost parts. In other words, if only films with small molecular orientation angles could be used, only the central part would be used, leading to increased costs.

[0039] However, in the present invention, the film having an opening-inducing defect in the intermediate layer is less likely to lose its tearability even when a biaxially oriented film is used as the outer layer film, and a biaxially oriented film with a molecular orientation angle of less than 49 degrees can be used.

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

[0041] 1 is a diagram for explaining an opening induced defect formed in an intermediate layer of the present invention. A laminated film 1 according to one embodiment of the present invention is composed of an outer layer film 2, an intermediate layer film 3, and an inner layer film 4, and an opening induced 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 induced 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. 2 is a polarizing microscope photograph of a cross section of an example of a laminate film used in the packaging bag of the present invention. (A) is a cross-sectional photograph of a laminate film in which the width L of the opening-induced defect 5 is 10 μm, and (B) is a cross-sectional photograph of a laminate film in which the width L of the opening-induced defect 5 is 0 μm. The opening of the opening induced defect is smaller and closed after the film is laminated or heat treated than before lamination. For example, an opening induced defect with a defect width of 0 μm is in a state where the defect is completely closed by laminating the film or heat treatment.

[0042] The width of the opening induced flaw is preferably 0 μm or more and 80 μm or less, particularly preferably 0 μm or more and 20 μm or less, and further preferably 0 μm or more and less than 10 μm. When an opening-inducing defect having a width of 0 μm or more and 20 μm or less is provided, even when a barrier film is used in the intermediate layer, it is possible to impart easy opening while suppressing a decrease in barrier performance. When the width of the defect is 0 μm or more and less than 10 μm, it is possible to maintain particularly high barrier properties. Furthermore, a laminated film having opening-inducing defects with a defect width of 0 μm or more and 20 μm or less has an excellent appearance, and in particular, a laminated film having defects with a defect width of 0 μm or more and less than 10 μm is unable to visually determine whether processing has been performed or not, and a highly attractive packaging bag can be obtained. In other words, by controlling the width of the defects, it is possible to provide a packaging bag that has excellent barrier properties, appearance, and ease of opening.

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

[0044] In consideration of the barrier performance, it is preferable that the opening induced flaw is 0 μm or more and 20 μm or less, but it is also possible to process the flaw to 20 μm or more and 80 μm or less and use a barrier film for the outer layer to complement the barrier performance. For example, a film configuration using vapor-deposited PBT for the outer layer, vapor-deposited PET with opening induced flaw processing for the middle layer, and polypropylene for the inner layer can be mentioned.

[0045] In the present invention, it is preferable that the number of opening induced defects is plural. Conventional packaging bags with a single cut line formed in the intended opening area cannot be easily opened unless the cut lines on the front and back are perfectly aligned. Furthermore, if an opening-assist notch is provided in the heat-sealed area, the notch must also be aligned. These adjustments take time and are thought to increase the failure rate, reducing productivity. However, in the packaging bag of the present invention, which has multiple opening-guiding defects, the bag is opened at any one of the multiple defects and the closest defect on the opposite side, making it easy to adjust the position, resulting in fewer defects and higher productivity. In other words, a packaging bag with excellent productivity and easy-openability can be provided.

[0046] In the present invention, the number of opening-inducing defects is not particularly limited as long as it is more than one, but if there are too few, the purpose 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 preferable. In addition, the distance between each opening guide defect can be determined arbitrarily, but if the distance is too far, the openability is impaired, so it is preferable that the distance be 2 mm or less.

[0047] The cross-sectional shape of the induced flaw may be V-shaped or rectangular, but is not limited thereto. The tear line caused by the induced flaw may be linear, arc-shaped, or curved, but is not limited thereto. Furthermore, the tear line caused by the induced flaw may be formed continuously or intermittently. When the tear line is formed intermittently, the processing gap between the flaws is preferably 1 mm or less, more preferably 0.5 mm or less, in order to prevent the sheet from being torn in an unintended direction from the part where the flaw is removed.

[0048] (Manufacturing method of packaging bags) In one embodiment of the manufacturing method for the packaging bag of the present invention, a laminated film having an opening-inducing defect is produced by a manufacturing process including a first lamination step of bonding an intermediate layer film and an inner layer film together, a step of applying an opening-inducing defect processing to the intermediate layer side of the bonded films with a width of 0 μm or more and 20 μm or less, and a second lamination step of bonding the film that has been subjected to the opening-inducing defect processing with an outer layer film, and the laminated film having an opening-inducing defect is heat-sealed to produce a packaging bag. In another aspect, a laminated film having an opening-inducing defect is produced by a manufacturing process including a first lamination step of bonding an intermediate layer film and an outer layer film together, a step of applying an opening-inducing defect treatment having a width of 0 μm or more and 20 μm or less from the intermediate layer side of the bonded films, and a second lamination step of bonding the film having the opening-inducing defect treatment to an inner layer film, and the laminated film having an opening-inducing defect is heat-sealed to produce a packaging bag. 3 is a diagram for explaining an example of a manufacturing method of a laminated film having an opening-inducing 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 laminated together by laminating rolls 12a and 12b, and then an opening-inducing defect 5 is formed by moving a cutter blade 13a of a cutter 13 along a roll 13b from the intermediate layer side. Next, an outer layer film 2 unwound from a unwinding roll 14 is laminated to the side on which the opening-inducing defect 5 is formed by laminating rolls 15a and 15b, and then wound up on a winding roll 16.

[0049] <Processing for opening-induced defects> Methods for forming opening-inducing defects include groove processing using a rotary cutter, perforation processing, laser processing, etc., but in the present invention, groove processing using a cutter is preferred. Laser processing can cause the molten film around the cut area to form protrusions, creating gaps in the laminate and potentially creating spine-like undulations when wound up, and there are also safety concerns when using organic solvents, so it is preferable to use a cutter that can easily create an opening-inducing defect of the desired opening width without causing such problems.

[0050] The opening-inducing flaw is preferably processed by half-cutting from the intermediate layer side after laminating the intermediate layer and the inner layer or the outer layer. The tip of the flaw may remain in the intermediate layer or may reach the inner layer or the outer layer, but it is preferable that the tip reaches the inner layer or the outer layer in order to obtain higher tearability. In addition, when the intermediate layer is a laminate of two or more layers, it is preferable that the tip reaches the layer of the intermediate layer that is closest to the inner layer or the outer layer, and it is more preferable that the tip reaches the inner layer or the outer layer.

[0051] When processing is performed after laminating the intermediate layer and the inner or outer layer, the thickness of the film makes it possible to stably form defects of a certain shape in a stiff film. Furthermore, in half-cut processing, a part of the film is not completely cut, so the film is less likely to meander and has good transportability. Therefore, when laminating the processed film to the outer layer film, unlike when a single intermediate layer is cut, the periphery of the cut part does not overlap and a spine-like undulation does not occur during winding, and a laminated film with a certain shape of opening-induced defects can be stably formed.

[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, more stable molding can be achieved by performing the opening-inducing defect processing after laminating the intermediate layer and the inner layer. In addition, when forming opening-inducing defects in a laminated film in which the outer layer and the intermediate layer are laminated, it is necessary to adjust the incision depth so as not to impair the performance required for the outer layer, such as barrier properties and impact resistance, and it is more preferable from the viewpoint of productivity to perform the opening-inducing defect processing on a laminated film in which the intermediate layer and the inner layer are laminated.

[0053] Conventional manufacturing methods, which have poor formability, are unable to process narrow opening-induced defects or stably process multiple opening-induced defects at regular intervals. In contrast, the manufacturing method of the present invention makes it possible to stably process defects of the same dimensions by simply adjusting the type of cutter blade and the clearance between the roll and the blade, and there is no dimensional deviation in the width of the defects after bonding. That is, it is possible to provide a manufacturing method for manufacturing, with good formability, a laminated film including an opening-inducing defect with a narrow defect width and an intermediate layer processed with a plurality of opening-inducing defects.

[0054] <Heat treatment process> In the manufacturing method according to the present invention, it is preferable to carry out a heat treatment after laminating the intermediate layer and the inner layer, subjecting them to an opening-inducing flaw processing, and laminating them with an outer layer film, or after laminating the intermediate layer and the outer layer, subjecting them to an opening-inducing flaw processing, and laminating them with an inner layer film. This makes it possible to narrow the flaw width. For example, by carrying out a heat treatment on a laminated film that has a flaw width of 10 μm when the outer layer film is attached, it is possible to narrow the flaw width to 0 μm. By adding this step, it becomes easier to control the width of the defects, and it is possible to stably form packaging bags with high barrier properties and good appearance.

[0055] The heat treatment conditions in the present invention can be various conditions such as 5 days at 35° C., 2 days at 50° C., 1 minute at 90° C., etc. This step is more efficient if it is performed together with a curing step usually performed during film molding or a step such as sterilization of the pouch. The heat treatment step can be carried out immediately after the laminated film is formed, or after the laminated film is stored for a certain period of time, or after the packaging bag is made.

[0056] When shrinking the flaw width by heat treatment, it is preferable to use a film having an appropriate heat shrinkage rate for the purpose as the outer layer film, such as, but not limited to, a biaxially oriented PBT film.

[0057] <Film lamination> The laminated film used in the present invention can be obtained by a normal dry lamination method. The adhesive used can be any adhesive commonly used in the manufacture of film packaging, such as a polyurethane adhesive. The processing of the film formed by bonding an inner layer and an intermediate layer to cause opening-inducing defects and laminating it to an outer layer film, or the processing of the film formed by bonding an outer layer and an intermediate layer to cause opening-inducing defects and laminating it to an inner layer film, can be performed in-line, or the film stored after the defect processing can be laminated later. Depending on the types of resins constituting each film, lamination may be performed by known co-extrusion lamination, such as lamination of an inner layer film and an intermediate layer film, or lamination of the intermediate layer films when there are a plurality of intermediate layer films.

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

[0059] The packaging bag according to the present invention may have a steam release mechanism. This makes it possible to release the internal pressure in the packaging bag during microwave heating and prevent the bag from breaking. When removing the contents after heating, by using a packaging bag with excellent tearability, the bag can be opened without the contents adhering to the opening part scattering and soiling the surroundings.

[0060] In addition, an opening-assist notch may be provided in the heat-sealed portion. The notch shape may 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 described in detail with reference to examples. However, the examples are merely embodiments of the present invention and the present invention is not limited thereto.

[0062] <Examples 1 to 4, Comparative Example 1> Five types of packaging bags were made with three opening-inducing defects of 0μm to 30μm at 1mm intervals in the middle layer, and 180mL of water was sealed and heated in a hot water bath, after which the opening property was evaluated and the oxygen transmission rate was measured. In addition, an oxygen transmission detection test was conducted for the pouches of Example 2 and Example 4.

[0063] [Pouch production] In the first lamination step, a 12 μm-thick aluminum oxide-vapor-deposited biaxially oriented polyethylene terephthalate film as an intermediate layer film and a 70 μm-thick polypropylene film as an inner layer film were laminated by dry lamination using a polyurethane-based adhesive on the polyethylene terephthalate film side of the intermediate layer film. A half-cut opening-induced defect was formed using a rotary cutter on the side of the vapor-deposited biaxially stretched polyethylene terephthalate film of the laminated film prepared in the first lamination step. In the second lamination process, a 15 μm polybutylene terephthalate film coated with a polyurethane-based adhesive was laminated by dry lamination to the vapor-deposited biaxially oriented polyethylene terephthalate film surface of the laminated film on which the opening-induced defects were formed, to produce a laminated film having each opening-induced defect width. The laminated film produced in the second lamination step was heat sealed to produce a flat pouch having a height of 170 mm and a width of 130 mm.

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

[0065] [Delamination evaluation when opening pouch] The cut portion of each pouch that had been torn open after warming in a hot water bath was visually evaluated. Those that had been opened along the opening induced defect were marked with an O, those in which part of the outer film had detached from the opening induced defect were marked with a △, and those in which the outer film had completely detached from the opening induced defect were marked with an X.

[0066] [Oxygen permeability measurement] A test piece was cut out from each pouch and the oxygen permeability (cc / m2) was measured at a temperature of 23°C and a relative humidity of 60% using the MOCON method. 2 ·day·atm) was measured.

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

[0068] [Table 1]

[0069] As can be seen from Table 1, when the width of the opening-induced flaw was in the range of 0 μm or more and 20 μm or less, the oxygen permeability was 0.6 or less, indicating good barrier properties.

[0070] [Oxygen permeation detection test] The pouches of Example 2 and Example 4 prepared by the above method were filled with a leucomethylene blue solution, sealed, and subjected to a retort treatment at 121° C. for 30 minutes. After removing from the sterilizer and leaving for 24 hours, the inside was observed from the outside.

[0071] As a result, the pouch of Example 2 showed no discoloration around the opening-induced flaw and exhibited good barrier properties, whereas the pouch of Example 4 showed very slight discoloration around the opening-induced flaw, confirming that a film with a flaw width of less than 10 μm exhibits higher barrier properties. [Industrial Applicability]

[0072] According to the present invention, an easy-open container excellent in tearability, barrier property, productivity, and appearance can be obtained. In addition, the easy-open container can be produced by a production method excellent in moldability. [Explanation of symbols]

[0073] 1 laminated film, 2 outer layer film, 3 intermediate layer film, 4 inner layer film, 5 opening induced defect, 10 intermediate layer film unwinding roll, 11 inner layer film unwinding roll, 12 laminate roll, 13 cutter, 14 outer layer film unwinding roll, 15 laminate roll, 16 take-up roll.

Claims

1. A method for producing a packaging bag by heat sealing a laminated film, comprising the steps of: The laminated film includes an inner layer film, at least one intermediate layer film, and an outer layer film, a first lamination step of bonding the intermediate layer film and the inner layer film; A step of applying an opening-inducing flaw processing having a width of 0 μm to 20 μm from the intermediate layer side of the laminated film; A second lamination step of laminating the film having the opening-inducing flaw treatment and the outer layer film, Any of the steps subsequent to the second lamination step includes a heat treatment step, The heat treatment step is a method for producing an easy-open packaging bag, the method controlling the width of the opening-induced defect.

2. A method for producing a packaging bag by heat sealing a laminated film, comprising the steps of: The laminated film includes an inner layer film, at least one intermediate layer film, and an outer layer film, a first lamination step of bonding the intermediate layer film and the outer layer film; A step of applying an opening-inducing flaw processing having a width of 0 μm to 20 μm from the intermediate layer side of the laminated film; A second lamination step of laminating the film having the opening-inducing flaw treatment and the inner layer film, Any of the steps subsequent to the second lamination step includes a heat treatment step, The heat treatment step is a method for producing an easy-open packaging bag, the method controlling the width of the opening-induced defect.

3. A method for manufacturing an easily openable packaging bag as described in claim 1 or 2, wherein the outer layer film includes a film that heat shrinks upon heat treatment.

4. The intermediate layer film has a barrier layer formed thereon, The method for producing an easily openable packaging pouch according to any one of claims 1 to 3, wherein the opening-inducing flaw treatment reaches the inside of the barrier layer.

5. A method for manufacturing an easily openable packaging bag described in any one of claims 1 to 4, wherein the heat treatment process comprises heat shrinking a film provided on the opening side of the opening-inducing defect.

6. A method for manufacturing an easily openable packaging bag described in any one of claims 1 to 5, wherein the heat treatment process involves heat shrinking a film located adjacent to the intermediate layer film on which the opening-inducing defect has been formed.

7. A method for manufacturing an easy-open packaging bag described in any one of claims 1 to 6, wherein the heat treatment process involves heat-shrinking an impact-resistant film.

8. A method for manufacturing an easily openable packaging bag described in any one of claims 1 to 7, wherein the width of the opening-induced defect is 0 μm or more and less than 10 μm.

9. A method for manufacturing an easy-open packaging bag described in any one of claims 1 to 8, wherein the heat treatment process involves heat shrinking a film containing polybutylene terephthalate.

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