Packaging bag

Abstract

To provide a packaging bag resistive to internal pressure and allowed to stably store a content despite being easy to close and open.SOLUTION: A packaging bag comprises a main body that consists of a laminate film having stretched and sealant films and a zipper that is formed on the sealant film in a position closer to an opening of the main body. The zipper has a first zipper formed closer to the opening and a second zipper formed farther from the opening than the first zipper. The first zipper has a strength in opening of 6-12 N / 50 mm and a strength against internal pressure of 6-19 N / 50 mm, and the second zipper has a strength in opening of 3-6 N / 50 mm and a strength against internal pressure of 13-35 N / 50 mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a packaging bag. [Background technology]

[0002] Packaging bags made of film are widely used because they are lightweight and easy to handle. Furthermore, zippers are attached to the packaging bags to facilitate repeated opening and closing (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-24113 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-46156 [Patent Document 3] International Publication No. 2012 / 165453 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when storing food or other contents in a packaging bag, it is desirable for the zipper to be less strong when opened in order to make the zipper easier to open and close. However, it is desirable for the zipper to be strong when opened in order to maintain the closure of the packaging bag even when the weight of the contents acts on the zipper from the inside. To achieve ease of intentional opening and closing while providing resistance to unintentional opening, it was necessary to achieve both of these contradictory goals.

[0005] To provide a packaging bag which is easy to close and open, yet is resistant to internal pressure and allows the contents to be stably stored. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following configuration. [1] A packaging bag comprising a body portion made of a laminated film having a stretched film and a sealant film, and a zipper formed on the sealant film on the opening side of the body portion, the zipper having a first zipper formed on the side closer to the opening and a second zipper formed on the side farther from the opening than the first zipper, the first zipper having a strength when opened of 6 to 12 N / 50 mm and a strength against internal pressure of 6 to 19 N / 50 mm, and the second zipper having a strength when opened of 3 to 6 N / 50 mm and a strength against internal pressure of 13 to 35 N / 50 mm. [2] The packaging bag according to [1], wherein the stretched film is a stretched nylon resin film. [3] The packaging bag according to [1] or [2], wherein the sealant film is a polyethylene resin film. [4] The packaging bag according to any one of [1] to [3], wherein the body is sealed on both sides of the opening in the width direction. [5] The packaging bag according to any one of [1] to [4], wherein the packaging bag is a bag for preserving fruits and vegetables, and the body portion has one or more holes for preserving freshness. [Effects of the Invention]

[0007] According to the present invention, a packaging bag is provided which is easy to close and open, yet is resistant to internal pressure and allows the contents to be stored stably. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view schematically illustrating an example of a packaging bag according to an embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view schematically illustrating an example of a laminated film. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below based on preferred embodiments.

[0010] A packaging bag according to one embodiment of the present invention includes a body portion made of a laminated film and a zipper formed on the opening side of the body portion. The laminated film includes a stretched film and a sealant film. The zipper is formed on the sealant film.

[0011] The zipper has a first zipper formed on the side closer to the opening, and a second zipper formed on the side farther from the opening than the first zipper.

[0012] The strength of the first zipper when it is opened is 6 to 12 N / 50 mm. By setting the strength of the first zipper at the time of opening to 6N / 50mm or more, it is possible to prevent the first zipper from opening unintentionally due to an external force or the like. When the strength of the first zipper when opening is 12N / 50mm or less, only a small force is required to open the first zipper, making it easy to open.

[0013] The strength of the first zipper against internal pressure is 6 to 19 N / 50 mm. By making the strength of the first zipper against internal pressure 6N / 50mm or more, it is possible to prevent the first zipper from opening unintentionally due to internal pressure. Since the strength of the first zipper against internal pressure is 19N / 50mm or less, practical strength can be ensured even if the first zipper uses a relatively inexpensive material such as synthetic resin and a relatively simple structure such as a fitting.

[0014] The strength of the second zipper when opened is 3 to 6 N / 50 mm. By setting the strength of the second zipper at the time of opening to 3N / 50mm or more, it is possible to prevent the first zipper from opening unintentionally due to an external force or the like. When the strength of the second zipper when opening is 6N / 50mm or less, only a small force is required to open the second zipper, making it easy to open.

[0015] The second zipper has an internal pressure strength of 13 to 35 N / 50 mm. By making the strength of the second zipper against internal pressure 13N / 50mm or more, it is possible to prevent the second zipper from opening unintentionally due to internal pressure. Since the strength of the second zipper against internal pressure is 35N / 50mm or less, practical strength can be ensured even if the second zipper uses a relatively inexpensive material such as synthetic resin and a relatively simple structure such as a fitting.

[0016] The strength when opening and the strength against internal pressure both indicate the amount of force required to open the zipper per 50 mm of zipper length along the width direction of the packaging bag. When a zipper closes by fitting a convex portion and a concave portion together, the fitting strength is the strength required to separate the convex portion and the concave portion from their fitted state and pull the convex portion out of the concave portion.

[0017] For example, the interlocking strength can be measured by cutting out a piece of laminated film having a zipper along the first side of a rectangle, with one of the short and long sides designated as the first side and the other as the second side, and attaching the end of the piece along the second side to a gripping tool and setting it in a tensile tester. The interlocking strength can be measured from the tensile force required to release the zipper. If the laminated film has a zipper convex portion and a zipper concave portion between the first and second sides, the tensile force can be measured by pulling the first and second sides apart to separate the zipper convex portion and the zipper concave portion. As an example, the following measurement conditions are given. Measurement surface: One side fixed with SUS plate Tensile speed: 50 mm / min Measurement temperature: room temperature Peeling angle: 180° Sample width: 50mm Number of measurements: n = 1 location x 3 times

[0018] When a user opens the packaging bag, an external force is applied to the first zipper closer to the opening before the second zipper further from the opening. Because the strength of the second zipper when opening is equal to or less than the strength of the first zipper when opening, the second zipper opens naturally with the remaining strength when the first zipper is opened. Because the multiple zippers open naturally without the user having to consciously try to open them one after the other, the feeling that the zippers are difficult to open is reduced.

[0019] When the weight of the contents acts on the zipper, internal pressure is applied to the second zipper closer to the contents before the first zipper, which is farther from the contents. By preventing the second zipper from opening, it is possible to reduce the chance of internal pressure being applied to the first zipper. Furthermore, even if the second zipper opens, it is possible to reduce the internal pressure applied to the first zipper.

[0020] If the strength of the second zipper against internal pressure is equal to or greater than the strength of the first zipper against internal pressure, the second zipper is prevented from opening, thereby reducing the chance of internal pressure being applied to the first zipper. For example, if the strength of the first zipper against internal pressure is 6 to 19 N / 50 mm, the strength of the second zipper against internal pressure may be 19 to 35 N / 50 mm. Alternatively, if the strength of the first zipper against internal pressure is 6 to 13 N / 50 mm, the strength of the second zipper against internal pressure may be 13 to 35 N / 50 mm.

[0021] If the strength of the first zipper against internal pressure and the strength of the second zipper against internal pressure are approximately the same, the zippers cooperate to resist the internal pressure, thereby preventing a situation in which all of the zippers open due to the internal pressure. For example, the strength of the first zipper against internal pressure and the strength of the second zipper against internal pressure may both be 13 to 19 N / 50 mm.

[0022] <Laminated film> The laminated film used for the body of the packaging bag includes a stretched film and a sealant film.

[0023] The stretched film is not particularly limited, but examples thereof include a stretched polyester resin film, a stretched polyolefin resin film, and a stretched nylon resin film. Examples of polyesters used for the stretched polyester resin film include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN). Examples of polyolefins used in stretched polyolefin resin films include polypropylene (PP) and polyethylene (PE).

[0024] The stretched film is preferably a stretched nylon resin film. The nylon used for the stretched nylon resin film is a polyamide having no aromatic ring (non-aromatic polyamide), and is obtained by, for example, polymerization or copolymerization of a cyclic lactam (a lactam having three or more ring members), an amino acid, or a nylon salt (a salt of a diamine and a dicarboxylic acid).

[0025] Examples of the cyclic lactam include ε-caprolactam, ω-enantholactam, ω-laurolactam, α-pyrrolidone, and α-piperidone. Examples of the amino acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0026] Examples of the diamine include aliphatic amines such as tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; and alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, isophoronediamine, piperazine, bis(4-aminocyclohexyl)methane, and 2,2-bis-(4-aminocyclohexyl)propane.

[0027] Examples of the carboxylic acid include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sepatic acid, undecanedioic acid, and dodecanedioic acid; and alicyclic carboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid.

[0028] More specifically, the polyamide may be, for example, 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon, 612-nylon, 6T-nylon, 6I nylon, a copolymer of 6-nylon and 66-nylon (nylon 6 / 66), a copolymer of 6-nylon and 610-nylon, a copolymer of 6-nylon and 611-nylon, a copolymer of 6-nylon and 12-nylon (nylon 6 / 12), or a copolymer of 6-nylon and 612 nylon. , copolymers of 6-nylon and 6T-nylon, copolymers of 6-nylon and 6I-nylon, copolymers of 6-nylon, 66-nylon and 610-nylon, copolymers of 6-nylon, 66-nylon and 12-nylon (nylon 6 / 66 / 12), copolymers of 6-nylon, 66-nylon and 612-nylon, copolymers of 66-nylon and 6T-nylon, copolymers of 66-nylon and 6I-nylon, copolymers of 6T-nylon and 6I-nylon, copolymers of 66-nylon, 6T-nylon and 6I-nylon, and copolymers of 66-nylon, 6T-nylon and 6I-nylon.

[0029] The stretched film may consist of one layer (single layer) or two or more layers. When the stretched film consists of multiple layers, the materials and / or thicknesses of these multiple layers may be the same or different from one another, and the combination of these multiple layers is not particularly limited.

[0030] The sealant film is not particularly limited, but any resin material commonly used as a sealant can be appropriately selected and used as long as it has adhesive properties and does not adversely affect the contents (non-adsorbing properties, etc.) when used as a package. Specific examples of such resin materials include polyolefin resins such as polyethylene resins and polypropylene resins. The resin material used for the sealant film may be a non-stretched resin film.

[0031] The polyethylene-based resin is not particularly limited, and examples thereof include polyethylenes such as high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), and low-density polyethylene (LDPE). The polyethylene-based resin may be a copolymer of ethylene and a polar monomer. Examples of such copolymers include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate (EEA), ethylene-methyl acrylate (EMA), ethylene-methacrylic acid (EMAA), ionomer (ION), and ethylene-acrylic acid copolymer (EAA). Examples of the ionomer include a resin in which a copolymer of ethylene and acrylic acid or methacrylic acid is crosslinked with a metal ion. The polyethylene-based resin may also be an elastomer such as ethylene-propylene rubber (EPR), ethylene-propylene diene terpolymer (EPDM), or chlorinated polyethylene. These polyethylene-based resins may be used alone or in combination. The sealant film is preferably a polyethylene resin film.

[0032] Examples of the polypropylene resin include homopolypropylene, propylene-ethylene random copolymer, propylene-ethylene block copolymer, etc. These polypropylene resins may be used alone or in combination.

[0033] The sealant film may consist of one layer (single layer) or two or more layers. When the sealant film consists of multiple layers, the materials and / or thicknesses of these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited.

[0034] The thickness of the laminate film is not particularly limited, but is preferably 15 to 150 μm. When the thickness of the laminate film is equal to or greater than the lower limit, the strength of the laminate film is further improved. When the thickness of the laminate film is equal to or less than the upper limit, flexibility can be ensured.

[0035] The laminated film used in the body of the packaging bag may be a laminate consisting of only a stretched film and a sealant film, or may have other layers in addition to the stretched film and the sealant film. Examples of other layers include a barrier layer such as a metal foil, a printed layer, etc. Barrier layers include an oxygen barrier layer and a water vapor barrier layer, and are suitable for storing contents such as pharmaceuticals that should be protected from external oxygen and moisture.

[0036] The method for producing the laminated film is not particularly limited, but examples thereof include dry lamination, thermal lamination, extrusion lamination, and multilayer inflation. When the laminated film has other layers, the method may include a process corresponding to the other layers. Examples of the process corresponding to the other layers include, but are not limited to, a coating process, a printing process, a vapor deposition process, and a lamination process.

[0037] Specific examples of the laminated film include those having a structure such as ONY / PE, OPET / PE, OPP / PE, OPP / CPP, OPET / ONY / PE, and ONY / AL / PE. Here, ONY stands for oriented nylon, OPET stands for oriented polyethylene terephthalate, OPP stands for oriented polypropylene, PE stands for polyethylene, CPP stands for unoriented polypropylene, and AL stands for aluminum foil.

[0038] <Example of packaging bag> Fig. 1 is a perspective view schematically showing an example of a packaging bag according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view schematically showing an example of a laminated film. The packaging bag 10 shown here comprises a body portion 11 made of a laminated film 30 having a stretched film 31 and a sealant film 32, and zippers 21, 22 formed on the sealant film 32 on the opening 20 side of the body portion 11. The zippers 21, 22 comprise a first zipper 21 formed on the side closer to the opening 20 and a second zipper 22 formed on the side farther from the opening 20 than the first zipper 21.

[0039] FIG. 1 shows the packaging bag 10 with the opening 20 slightly open, the first surface 30a and the second surface 30b spaced apart, and the upper portion of the storage section 12 slightly inflated. When the opening 20 is closed using zippers 21 and 22, the packaging bag 10 can be made substantially flat. A number of substantially flat packaging bags 10 can be stacked and bundled. The packaging bag 10 is flexible and can be rolled up in the height direction.

[0040] Body 11 has storage section 12, in which contents are stored, on the side farther from opening 20 than second zipper 22. Body 11 also has outer edge 23 between storage section 12 and opening 20. Outer edge 23 of body 11 can be used as a handle when opening zippers 21 and 22.

[0041] Although not particularly shown, it is preferable to form irregularities such as embossments on the inner surface of the outer edge portion 23 from the viewpoint of preventing slippage and sticking. The shape of the irregularities is not particularly limited, but examples include stripes, waves, and a grid pattern.

[0042] The shape of the upper end 24 of the body 11 is not particularly limited, but when the packaging bag 10 is in an open state, the upper end 24 of the body 11 may be annular so as to surround the opening 20. When the packaging bag 10 is in a closed, flat state, the shape of the upper end 24 is not particularly limited, but examples thereof include a straight shape, a curved shape, and a wavy shape.

[0043] Body 11 has side portions 13 on both sides of opening 20 in the width direction. Side portions 13 may be sealed. Both sides of opening 20 in the width direction refer to both sides in the direction in which zippers 21 and 22 extend. Zippers 21 and 22 are preferably structured to be able to seal storage section 12 from one side portion 13 to the other side portion 13.

[0044] Body 11 has bottom 14 on the opposite side to upper end 24. Bottom 14 may be sealed, or may be formed by folding laminate film 30 in half. When packaging bag 10 is in a closed, flat state, the shape of bottom 14 is not particularly limited, but examples include a straight shape and a curved shape.

[0045] The first surface 30a and the second surface 30b of the opening 20 are formed from a laminate film 30. The laminate film 30 on the first surface 30a and the laminate film 30 on the second surface 30b may be the same laminate film 30, or may be different laminate films 30. When the first surface 30a and the second surface 30b are made of the same laminate film 30, the continuous laminate film 30 may be folded in at the side portion 13 or the bottom portion 14.

[0046] <Zipper> The zippers 21, 22 are preferably formed from a zipper projection and a zipper recess that can fit together. This makes it easy to create a structure that can withstand repeated opening and closing, even if the zippers 21, 22 are made from a relatively inexpensive material such as synthetic resin. The first zipper 21 has a first zipper projection 21a and a first zipper recess 21b. The second zipper 22 has a second zipper projection 22a and a second zipper recess 22b.

[0047] Examples of materials used for zippers 21 and 22 include polyolefin resins such as polyethylene resins and polypropylene resins. The polyolefin resin used for zippers 21 and 22 may be the same as or different from the polyolefin resin used for the sealant film of body portion 11.

[0048] The method for forming the zippers 21, 22 is not particularly limited, but the zipper protrusions 21a, 22a and zipper recesses 21b, 22b may be bonded by extrusion molding or the like onto the sealant film of the body portion 11. Alternatively, a zipper tape having zipper protrusions or zipper recesses formed on a strip-shaped tape that is narrower than the body portion 11 may be produced, and the zipper tape may be bonded to the sealant film by heat sealing or the like.

[0049] The shape of the zipper projections 21a, 22a is not particularly limited, but is preferably such that, in a cross section perpendicular to the direction in which the zippers 21, 22 extend, the tip on the side farther from the sealant film is larger than the base on the side closer to the sealant film. The base may be positioned downward, and the tip may not protrude to either the left or right of the base, but may protrude only upward, forming a roughly I-shape. The tip may protrude from both sides of the base in a roughly T-shape, or may protrude from one side of the base in a roughly Γ-shape.

[0050] The shape of the zipper recesses 21b, 22b is not particularly limited, but preferably has a shape in which, in a cross section perpendicular to the direction in which the zippers 21, 22 extend, the dimensions increase from the base closer to the sealant film toward the middle farther from the sealant film and decrease from the middle toward the tip farther from the sealant film. Furthermore, it is preferable that a cavity is formed inside the zipper recesses 21b, 22b to accommodate the tips of the zipper protrusions 21a, 22a. It is also preferable that the tips of the zipper recesses 21b, 22b have a gap through which the tips of the zipper protrusions 21a, 22a pass. For example, the zippers 21, 22 may be formed into a substantially C-shape or a substantially U-shape in a cross section perpendicular to the direction in which the zippers 21, 22 extend.

[0051] When closing the zippers 21, 22, outer edge 23 of body 11 is pressed from the outside to bring first surface 30a and second surface 30b closer together, and the tips of zipper protrusions 21a, 22a fit into the hollows of zipper recesses 21b, 22b. When opening the zippers 21, 22, outer edge 23 of body 11 is pulled to separate first surface 30a and second surface 30b from each other, and the tips of zipper protrusions 21a, 22a are separated from the hollows of zipper recesses 21b, 22b.

[0052] The strength of zippers 21, 22 when they are opened and their strength against internal pressure can be adjusted by appropriately designing the shapes of zipper protrusions 21a, 22a and zipper recesses 21b, 22b.

[0053] For example, in a cross section perpendicular to the direction in which the zippers 21, 22 extend, the strength at the time of opening and the strength against internal pressure can be increased by increasing the dimensions of the tips of the zipper protrusions 21a, 22a relative to the dimensions of the gaps between the zipper recesses 21b, 22b. The strength at the time of opening and the strength against internal pressure can also be increased by thickening the middle parts of the zipper recesses 21b, 22b. The strength at the time of opening and the strength against internal pressure can also be increased by having the tips of the zipper recesses 21b, 22b embrace the tips of the zipper protrusions 21a, 22a at a deeper angle.

[0054] To create a difference between the strength of the zippers 21, 22 when they are opened and the strength against internal pressure, the shape of at least one of the zipper protrusions 21a, 22a and zipper recesses 21b, 22b may be asymmetric between the storage section 12 side and the opening 20 side.

[0055] When zippers 21, 22 are opened, outer edge 23 is pulled away from opening 20, so the distance between opposing outer edge portions 23 across opening 20 tends to be greater on the opening 20 side than on the storage section 12 side. Conversely, when internal pressure acts on zippers 21, 22, the contents approach from the storage section 12 side or the inside of storage section 12 expands, so the distance between opposing outer edge portions 23 across opening 20 tends to be greater on the storage section 12 side than on the opening 20 side.

[0056] For example, when zipper projections 21a, 22a have a tip on the opening 20 side and a tip on the storage section 12 side, the tip on the opening 20 side may be smaller than the tip on the storage section 12 side. This makes it possible to make the resistance force exerted when zipper projections 21a, 22a slip out of zipper recesses 21b, 22b toward opening 20 smaller than the resistance force exerted when zipper projections 21a, 22a slip out of zipper recesses 21b, 22b toward storage section 12.

[0057] Furthermore, the intermediate portions of zipper recesses 21b, 22b on the storage compartment 12 side may be thicker than the intermediate portions on the opening 20 side. This makes it possible to increase the resistance force exerted when zipper protrusions 21a, 22a slip out of zipper recesses 21b, 22b toward storage compartment 12 compared to the resistance force exerted when zipper protrusions 21a, 22a slip out of zipper recesses 21b, 22b toward opening 20.

[0058] Furthermore, the tip ends of zipper recesses 21b, 22b on the storage compartment 12 side may be bent at a deeper angle than the tip ends on the opening 20 side. By fitting the tip ends of zipper protrusions 21a, 22a into these deeply bent portions, the resistance force exerted when zipper protrusions 21a, 22a slip out of zipper recesses 21b, 22b toward storage compartment 12 can be made greater than the resistance force exerted when zipper protrusions 21a, 22a slip out of zipper recesses 21b, 22b toward opening 20.

[0059] The dimensions of the area where first zipper 21 and second zipper 22 are formed on each of first surface 30a and second surface 30b are not particularly limited, but it is preferable that the width be narrower than the fingertip so that zippers 21, 22 can be fastened together at once by pressing them with fingers. For example, it is preferable that zippers 21, 22 fit within a range of approximately 3 to 8 mm. Here, the width of the area where first zipper 21 and second zipper 22 are formed is the sum of the width of first zipper 21, the width of second zipper 22, and the width of the gap between them.

[0060] It is preferable that zipper protrusions 21a, 22a have a substantially uniform cross-sectional shape in the length direction of zippers 21, 22, which is along the width direction of packaging bag 10. This makes it easier to separate zipper protrusions 21a, 22a from the mold by extracting the molding material in the length direction of zippers 21, 22 when molding them from a mold using a molding material such as synthetic resin. Similarly, it is preferable that the zipper recesses 21b, 22b have a substantially uniform cross-sectional shape in the length direction of the zippers 21, 22.

[0061] It is preferable that a sound that is noticeable to the user be made when engaging or disengaging zippers 21, 22. To increase the volume of the sound made when engaging or disengaging, notches may be provided in zipper projections 21a, 22a at predetermined intervals along the length of zippers 21, 22. By separating zipper projections 21a, 22a into multiple sections via the notches, a sound is made each time each of the multiple sections is engaged or disengaged.

[0062] A strip-shaped member without an interlocking structure may be provided in the region between the first zipper 21 and the second zipper 22. Such a strip-shaped member may be colored to make the zippers 21, 22 stand out, or to reinforce the laminated film 30. The zippers 21, 22 may be colored to make them stand out. If the laminated film 30 forming the storage section 12 is transparent, the contents can be easily seen. A colored portion may be provided in part or all of the storage section 12.

[0063] <An example of a packaging bag manufacturing method> The method for producing the packaging bag is not particularly limited, but examples thereof include a production method including a step of forming a zipper on a laminated film and a step of making the laminated film into a bag. The production method may further include a step of producing a laminated film.

[0064] The step of forming a zipper on the laminate film may be carried out before the step of making a bag from the laminate film, during the step of making a bag from the laminate film, or after the step of making a bag from the laminate film. Forming the zipper before the step of making a bag from the laminate film is preferable because it makes the formation of the zipper easier.

[0065] The step of forming a zipper on the laminate film can be carried out by the method described above as the zipper forming method. When forming the zipper, the laminate film may be cut to a size approximately equal to the size of one or both sides of the packaging bag, but it is preferable to form the zipper on the laminate film unwound from a film roll having a predetermined width or to join a zipper tape to the laminate film.

[0066] The laminated film unwound from the film roll is transported in the machine direction (MD). The zipper formed on the laminated film may extend in either the MD or the transverse direction (TD). When forming a zipper in the MD, the zipper may be formed continuously across multiple packaging bags. The step of cutting the continuous zipper into individual packaging bags may be carried out simultaneously with the step of cutting the laminated film into individual packaging bags.

[0067] The width of the laminated film in the film roll is not particularly limited, but may be approximately the same as or twice the height or width of the packaging bag.

[0068] When the width of the laminate film in the film roll is approximately the same as the height or width of the packaging bag, the packaging bag may be formed by placing two laminate films, each having one side of a zipper, opposite each other and then joining them at positions that will become the side and bottom of the packaging bag. Here, the "one side of the zipper" refers to either the zipper protrusion or the zipper recess. By placing a laminate film having a zipper protrusion opposite a laminate film having a zipper recess, a zipper having a zipper protrusion and a zipper recess is formed.

[0069] When the width of the laminated film in the film roll is at least twice the width of the packaging bag, the laminated film may be folded in the width direction of the packaging bag to form both sides of the packaging bag. When the width of the laminated film in the film roll is at least twice the height of the packaging bag, the laminated film may be folded in the height direction of the packaging bag to form both sides of the packaging bag. When the laminated film is folded in the width direction or height direction of the packaging bag, the zipper protruding portion and the zipper recessed portion are positioned to face each other with the folding line as the center line.

[0070] 1, when the bottom 14 is a fold line and the side 13 is a seal, one of the zipper protrusions 21a, 22a and the zipper recesses 21b, 22b may be formed at opposing positions on the first surface 30a and the second surface 30b, respectively, and after folding the bottom 14 in half, the side 13 may be sealed to separate the individual packaging bags 10. If necessary, a step of trimming the upper end 24 of the body 11 may be provided.

[0071] In the illustrated example of packaging bag 10, first zipper protrusions 21a and second zipper recesses 22b are provided on first surface 30a, and first zipper recesses 21b and second zipper protrusions 22a are provided on second surface 30b. A good balance is achieved when the same number of large zipper recesses 21b, 22b and small zipper protrusions 21a, 22a are arranged on each of first surface 30a and second surface 30b.

[0072] Although not particularly shown, first zipper protrusion 21a and second zipper protrusion 22a may be provided on one surface, and first zipper recess 21b and second zipper recess 22b may be provided on the other surface.

[0073] The contents to be stored in the storage section of the packaging bag are not particularly limited, but examples include food products such as fruits and vegetables, medicines, daily necessities, miscellaneous goods, etc. The contents may be unpackaged goods, goods stored in containers such as bottles, cans, boxes, etc., or goods packaged in film or the like.

[0074] The packaging bag may be used by a manufacturer or seller of the contents to package a product, by a manufacturer or seller to store a product for a purchaser, or by a user such as a consumer to store a desired item. Since the packaging bag can be used repeatedly, it can also be used subsequently for a purpose different from the purpose for which it was first used.

[0075] <Holes to maintain freshness> When the packaging bag is a bag for storing fruits and vegetables, the body may have one or more holes for preserving freshness. Fruits and vegetables may continue to breathe even after being harvested. In this case, it is preferable to provide holes for preserving freshness in order to prevent deterioration of the quality of the fruits and vegetables. The holes for preserving freshness may be used to take in outside air or to expel gas generated inside.

[0076] The number, position, size, etc. of the freshness-preserving holes are not particularly limited, but it is preferable to provide the freshness-preserving holes so that they communicate with the storage section of the package where the contents are stored. When the laminated film has freshness-preserving holes at predetermined intervals, some of the freshness-preserving holes may be located on the outer edge that is closer to the opening than the zipper.

[0077] When the packaging bag does not have holes for preserving freshness, it may have a structure in which the containing section is sealed substantially airtight or liquidtight when the zipper is closed. When the laminated film constituting the body section has a barrier layer, such as for pharmaceutical applications, it is preferable that the packaging bag does not have holes for preserving freshness. [Industrial Applicability]

[0078] The present invention can provide a packaging bag that is easy to close and open, yet is resistant to internal pressure and allows the contents to be stored stably. [Explanation of symbols]

[0079] 10...packaging bag, 11...body portion, 12...storage portion, 13...side portion, 14...bottom portion, 20...opening portion, 21...first zipper, 21a...first zipper convex portion, 21b...first zipper concave portion, 22...second zipper, 22a...second zipper convex portion, 22b...second zipper concave portion, 23...outer edge portion, 24...upper end portion, 30...laminated film, 30a...first surface, 30b...second surface, 31...stretched film, 32...sealant film

Claims

1. a body portion made of a laminated film having a stretched film and a sealant film; a zipper formed on the sealant film on the opening side of the body portion, The zipper has a first zipper formed on a side closer to the opening and a second zipper formed on a side farther from the opening than the first zipper, the first zipper has an opening strength of 6 to 12 N / 50 mm and an internal pressure strength of 6 to 19 N / 50 mm; The second zipper has a strength of 3 to 6 N / 50 mm when opened and a strength against internal pressure of 13 to 35 N / 50 mm.

2. 2. The packaging bag according to claim 1, wherein the stretched film is a stretched nylon resin film.

3. 3. The packaging bag according to claim 1, wherein the sealant film is a polyethylene resin film.

4. The packaging bag according to claim 1 or 2, wherein the body portion is sealed on both sides of the opening in the width direction.

5. 3. The packaging bag according to claim 1, wherein the packaging bag is a bag for preserving fruits and vegetables, and the body portion has one or more holes for preserving freshness.

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