Food packaging bags

Abstract

To provide a food packaging bag that is hard to tear and highly reusable.SOLUTION: A food packaging bag 1A is formed of a film. The food packaging bag has: a pair of main surface portions 11, 12 arranged opposite each other in a flat bag state; a pair of fusing seal portions 13, 14 formed at both ends in a width direction of the pair of main surface portions 11, 12; and a pair of reinforcement seal portions 15A, 16A formed inside the pair of fusing seal portions 13, 14 with respect to the width direction of the pair of main surface portions 11, 12 to reinforce the pair of fusing seal portions 13, 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bag for food packaging, a method for manufacturing the bag for food packaging, and a method for reinforcing the bag for food packaging.

Background Art

[0002] Conventional food packaging bags such as those for bread and confectionery bread are sold in a bundled state tied with a fastener for fixing by twisting the opening, that is, a plastic plate about 2 cm square with a slit, tape, string, etc. Even if there are multiple contents or a single large content, it can be opened and closed many times with a reusable fastener, so it is highly convenient and widely used.

[0003] However, since the packaging with such a fastener is simple, there is a gap in the binding part of the packaging bag, and there is a drawback that foreign matter cannot be prevented from entering. Therefore, the present applicants have proposed a laminated film for an easy-open food packaging bag having a surface layer (A) containing a propylene resin, an intermediate layer (C) containing a propylene resin, and a heat-sealing layer (B) containing a 1-butene copolymer (b1) having 1-butene and propylene as essential components and a copolymer (b2) having propylene and ethylene as essential components (Patent Document 1). When producing a bread bag or the like using the above laminated film for an easy-open food packaging bag, usually, the heat-sealing layer of the above three layers is processed into a bottom gusset bag by a bag-making machine so that it is on the inside of the bag. At this time, the fusion seal temperature and the bag-making speed are adjusted so that the fusion seal strength of the side part and the bottom gusset part (bottom folding part) of the bottom gusset bag is within a predetermined range.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, with the promotion of recycling and the introduction of charges for garbage bags, the need for alternatives to garbage bags has been increasing in households and other settings. Among the bags used in households, bread bags, for example, are easily available to users after shopping bags (plastic bags), and are highly convenient because they are bottom-gusseted bags that stand upright. However, depending on the weight of the garbage contained in the bread bag, stress may be placed on the heat-sealed part on the side of the bottom-gusseted bag, causing the bread bag to tear. In addition, in order to contain moisture-containing items such as food waste, users may add several drainage holes to the bottom gusset or nearby, but in this case, stress may also be placed on the heat-sealed part, causing the bread bag to tear unintentionally.

[0006] The present invention aims to provide a food packaging bag that is tear-resistant and highly reusable, a method for manufacturing a food packaging bag, and a method for reinforcing a food packaging bag. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides the following means. [1] A food packaging bag made of film, In a flat bag state, a pair of main surfaces are arranged opposite each other, A pair of heat-sealing portions formed at both ends in the width direction of the pair of main surfaces, A pair of reinforcing seal portions are formed on the inside of the pair of heat-seal portions with respect to the width direction of the pair of main surfaces, and reinforce at least a portion of the pair of heat-seal portions. A food packaging bag having [a certain feature].

[0008] [2] A bottom gusset is provided on the opposite side of the openings of the pair of main surfaces and extends across the entire width of the pair of main surfaces, The pair of heat-sealing portions extend from the opening to the bottom gusset, The food packaging bag according to [1] above, wherein the pair of reinforcing seal portions are formed adjacent to the pair of heat-seal portions.

[0009] [3] The food packaging bag according to [2] above, wherein, when the food packaging bag is opened, the triangular vertex at the intersection of the two widthwise folded ends of the bottom gusset and the heat-sealed portion is reinforced by the reinforcing seal portion.

[0010] [4] The food packaging bag according to [1] above, wherein the reinforcing seal portion extends along the direction of extension of the heat-sealed seal portion and over the entire heat-sealed seal portion.

[0011] [5] The food packaging bag according to any one of [1] to [4] above, wherein the reinforcing seal portion is a heat-sealed portion in which a pair of main surfaces are heat-sealed to each other.

[0012] [6] The food packaging bag according to any one of [1] to [5] above, wherein the film is a laminated film obtained by laminating a plurality of films made of one or more materials selected from olefin resins, biomass resins, and biodegradable resins.

[0013] [7] The food packaging bag according to [6] above, wherein the film is a laminated film made by laminating a plurality of films made of one or two of an unstretched olefin resin and a biodegradable resin.

[0014] [8] The laminated film is A surface layer (A) containing a propylene resin, An intermediate layer (C) containing a propylene resin, A heat-seal layer (B) having a thickness of 1 to 8 μm contains a 1-butene copolymer (b1) having 1-butene and propylene as essential components, and a copolymer (b2) having propylene and ethylene as essential components, A food packaging bag as described in [6] or [7] above, having the following:

[0015] [9] A method for manufacturing a food packaging bag made of film, A step of forming a pair of reinforcing seal portions at least in part of a portion where a pair of fusing seal portions are formed, on both sides in the width direction of a pair of opposed main surface portions; A step of forming a pair of fusing seal portions at both ends in the width direction of the pair of main surface portions; A method for manufacturing a food packaging bag, comprising these steps.

[0016]

[10] A method for reinforcing a food packaging bag formed of a film, having a pair of fusing seal portions on both sides in the width direction of a pair of main surface portions opposed in a flat bag state, the method comprising reinforcing at least part of the fusing seal portion with a reinforcing seal. [Advantages of the Invention]

[0017] According to the present invention, there are provided a food packaging bag that is difficult to break and highly reusable, a method for manufacturing the food packaging bag, and a method for reinforcing the food packaging bag. [Brief Description of the Drawings]

[0018] [Figure 1] FIG. 1 is a perspective view schematically showing a flat bag state of an example of a food packaging bag according to an embodiment of the present invention. [Figure 2] FIG. 2(A) is a plan view of the food packaging bag of FIG. 1, and FIG. 2(B) is a cross-sectional view taken along line segment A - A. [Figure 3] FIG. 3 is a perspective view showing a state where the food packaging bag of FIG. 1 is opened. [Figure 4] FIG. 4(A) is a view schematically showing a range where a fusing seal portion is formed in a side view of the food packaging bag of FIG. 3, and FIG. 4(B) is a view schematically showing a range where a reinforcing seal portion is formed. [Figure 5] FIG. 5 is a cross-sectional view showing an example of a laminated structure of a laminated film constituting the food packaging bag of FIG. 1. [Figure 6] FIGS. 6(A) to 6(C) are schematic views showing an example of a method for manufacturing a food packaging bag according to the present embodiment. [Figure 7]Figures 7(A) and 7(B) are schematic diagrams showing modified examples of the areas where the fused seal portion in Figure 4(A) and the reinforcing seal portion in Figure 4(B) are formed. [Figure 8] Figures 8(A) and 8(B) are schematic diagrams showing other modified examples of the areas where the fused seal portion of Figure 4(A) and the reinforcing seal portion of Figure 4(B) are formed. [Figure 9] Figures 9(A) and 9(B) are schematic diagrams showing other modified examples of the areas in which the fused seal portion of Figure 4(A) and the reinforcing seal portion of Figure 4(B) are formed. [Figure 10] Figure 10 is a plan view showing a modified example of the food packaging bag shown in Figure 2(A). [Modes for carrying out the invention]

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, the dimensional scale may differ depending on the component to make it easier to see, and the dimensional ratios of each component may not necessarily be the same as in reality. Furthermore, the structures, materials, etc. exemplified in the following description are examples only, and the present invention is not necessarily limited to them. It can be implemented with appropriate modifications without changing the essence of the invention.

[0020] <Composition of food packaging bags> Figure 1 is a schematic perspective view showing a flat bag in the form of an example of a food packaging bag according to an embodiment of the present invention, Figure 2(A) is a plan view of the food packaging bag of Figure 1, and Figure 2(B) is a cross-sectional view along line segment AA. In Figures 1 and 2, a bottom gusset bag is used as an example of a food packaging bag for explanation. As shown in Figure 1, the food packaging bag 1A is a food packaging bag formed from film, and has a pair of main surfaces 11, 12 arranged opposite each other in a flat bag state, a pair of heat-sealed portions 13, 14 formed at both ends in the width direction of the pair of main surfaces 11, 12, and a pair of reinforcing seal portions 15A, 16A formed inside the pair of heat-sealed portions 13, 14 with respect to the width direction of the pair of main surfaces 11, 12, and reinforcing the pair of heat-sealed portions 13, 14.

[0021] The food packaging bag 1A has a bottom gusset 18 that is located on the opposite side of the opening 17 of the pair of main surfaces 11 and 12 and extends across the entire width of the pair of main surfaces 11 and 12. In this embodiment, a pair of heat-sealed portions 13 and 13 extend from the opening 17 to the bottom gusset 18. In addition, a pair of reinforcing seal portions 15A and 16A are formed adjacent to the pair of heat-sealed portions 13 and 14.

[0022] In this embodiment, the main surface portion 11 is composed of a laminated film made by laminating three films. Similarly, the main surface portions 12 are not limited to three films, but may be composed of a laminated film made by laminating multiple films, or they may be single-layer films. The main surface portions 11 and 12 have a rectangular shape in a plan view, for example, when the bag is flat. The specific configuration of the laminated film will be described later.

[0023] The pair of heat-sealed portions 13 and 14 are formed by heat-sealing both ends in the width direction of the pair of main surfaces 11 and 12 while the two laminated films constituting the pair of main surfaces 11 and 12 are arranged facing each other (Figure 2(B)). The heat-sealed portion 13 is formed at one end in the width direction of the pair of main surfaces 11 and 12, and the heat-sealed portion 14 is formed at the other end in the width direction of the pair of main surfaces 11 and 12. The pair of heat-sealed portions 13 and 14 are formed linearly, for example, on the outer edges of both ends in the width direction of the pair of main surfaces 11 and 12. In this embodiment, the pair of heat-sealed portions 13 and 14 are formed over the entire pair of main surfaces 11 and 12 with respect to a direction perpendicular to the width direction of the pair of main surfaces 11 and 12 (the direction from the opening 17 toward the bottom gusset 18).

[0024] The pair of reinforcing seal portions 15A and 16A are formed, for example, by heat-welding the two laminated films constituting a pair of main surface portions 11 and 12 inside the pair of heat-sealed seal portions 13 and 14 in the width direction of the pair of main surface portions 11 and 12, with the two laminated films facing each other (Figure 2(B). That is, the pair of reinforcing seal portions 15A and 16A can be heat-sealed portions in which the pair of main surface portions 11 and 12 are heat-sealed to each other. The pair of reinforcing seal portions 15A and 16A are formed, for example, in a linear or strip shape along the shape of the pair of heat-sealed seal portions 13 and 14.

[0025] In this embodiment, the reinforcing seal portion 15A extends along the direction of extension of the heat-seal portion 13, and covers the entire heat-seal portion 13. Similarly, the reinforcing seal portion 16A extends along the direction of extension of the heat-seal portion 14, and covers the entire heat-seal portion 14.

[0026] The bottom gusset 18 is provided at the bottom of the food packaging bag 1A and is folded inward when the bag is flat. The bottom gusset 18 is usually folded once and appears as a valley fold when viewed from the outside (bottom side) of the food packaging bag 1A.

[0027] The food packaging bag 1A may have a printed area 19 near the opening 17, printed along the width direction of a pair of main surfaces 11 and 12. The shape of the printed area 19 is not particularly limited, but for example, it may be strip-shaped. The number of printed areas 19 may be multiple or one.

[0028] Furthermore, the food packaging bag 1A may have, for example, a heat-sealed portion (not shown) formed along the width direction of a pair of main surfaces 11 and 12 on the side opposite to the opening 17 of the printed portion 19. The shape of the heat-sealed portion is not particularly limited, but for example, it may be strip-shaped. The number of heat-sealed portions may be multiple or one.

[0029] Figure 3 is a perspective view showing the food packaging bag 1A of Figure 1 in an open state. Figure 4(A) is a schematic diagram showing the area where the heat-sealed portion 13 is formed in a side view of the food packaging bag 1A of Figure 3, and Figure 4(B) is a schematic diagram showing the area where the reinforcing seal portion 15A is formed. As shown in Figure 3, when the opening 17 of the food packaging bag 1A is opened and air or the like is sent inside, the bottom gusset 18 opens, forming a square bottom, which allows the food packaging bag 1A to stand on its own. Food items such as sliced ​​bread can be filled into the food packaging bag 1A.

[0030] When the food packaging bag 1A is opened, it has a bottom surface 21, first side surfaces 22 and second side surfaces 23 extending toward the opening 17 from two opposing sides of the bottom surface 21, and third side surfaces 24 and fourth side surfaces 25 extending toward the opening 17 from the remaining two opposing sides. The first side surfaces 22 and second side surfaces 23 are formed from a part of the main surface 11, a part of the main surface 12, and a part of the bottom gusset 18. The first side surface 22 also has a heat-sealed portion 13 and a reinforcing seal portion 15A, and the second side surface 23 has a heat-sealed portion 14 and a reinforcing seal portion 16A. The third side surface 24 is formed from a part of the main surface 11, and the fourth side surface 25 is formed from a part of the main surface 12.

[0031] On the first side surface 22, the triangular vertex 26, which is the intersection point between the two widthwise folded ends 18a and 18b of the bottom gusset 18 and the heat-sealed portion 13, is heat-sealed by the heat-sealed portion 13 and further reinforced by the reinforcing seal portion 15A. The triangular vertex 26 is a part that is easily subjected to load due to the weight of the contents when the food packaging bag 1A is filled with food, and by reinforcing this triangular vertex 26 with the reinforcing seal portion 15A, the strength of the food packaging bag 1A is further improved.

[0032] In this embodiment, the reinforcing seal portion 15A extends along the direction of extension of the heat-sealed seal portion 13 and over the entire heat-sealed seal portion 13. By having the reinforcing seal portion 15A extend along the direction of extension of the heat-sealed seal portion 13 and over the entire heat-sealed seal portion 13 as in this embodiment, the strength of the food packaging bag 1A can be further improved by reinforcing the triangular vertex portion 26 while also reinforcing the other heat-sealed seal portions.

[0033] [Film composition] The film constituting the food packaging bag 1A is preferably a laminated film formed by laminating multiple films made of one or more materials selected from olefin resins, biomass resins, and biodegradable resins. The multiple films constituting the laminated film may be made of different materials or the same materials.

[0034] When the laminated film is made of olefin resin, it becomes possible to re-sheet it, and for example, after putting garbage or other items inside the bag, the opening can be sealed by heat welding, making it possible to reuse it as a sealed bag. If the laminated film is made of biomass-based resin, it can contribute to reducing CO2 emissions when disposing of the bags. If the laminated film is made of biodegradable resin, for example, after putting garbage or other waste into the bag, the opening can be sealed as needed and the film can be used as fertilizer as is.

[0035] Furthermore, it is more preferable that the laminated film is made by laminating multiple films made of one or two types of unoriented olefin resin and biodegradable resin. When the films constituting the laminated film are made of one or two types of unoriented olefin resin and biodegradable resin, the laminated film is less likely to tear, and when a hole is made in the laminated film by piercing it with chopsticks or the like, the hole does not widen, and the hole does not widen even when external force is applied afterward. Therefore, moisture-containing materials such as food waste can be placed in the bag and the moisture can be removed by squeezing the bag.

[0036] As unstretched olefin resins, for example, propylene-based resins such as propylene homopolymers, propylene-α-olefin random copolymers, and propylene-α-olefin block copolymers can be used. On the other hand, polyethylene resins include polyethylene resins such as linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), linear high-density polyethylene (LHDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), as well as ethylene copolymers such as ethylene-butene-rubber copolymer (EBR), ethylene-propylene-rubber copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); and further, ionomers of ethylene-acrylic acid copolymers and ionomers of ethylene-methacrylic acid copolymers, which may be used individually or in mixtures of two or more types.

[0037] Examples of biomass-based resins include plant-derived biomass polyethylene. This resin is a polyethylene-based resin produced from plant-derived ethylene using sugarcane, corn, beets, etc., as starting materials. Examples of biomass polyethylene include linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), linear high-density polyethylene (LHDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), which may be used individually or in mixtures of two or more types. Other examples include biomass polypropylene and biomass polyethylene made from tall oil (a by-product of pulp production) and waste cooking oil (recycled).

[0038] Examples of biodegradable resins include polyethylene succinate (PES), polybutylene succinate (PBS), polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxybutyrate (PHB), polycaprolactone (PCL), mixtures or copolymers of polycaprolactone and polybutylene succinate (PCL / PBS), copolymers of polyhydroxybutyrate and polyhydroxyvalate (PHB / PHV), mixtures or copolymers of polybutylene succinate and polybutylene adipate (PBS / PBA), copolymers of polyethylene terephthalate and polyethylene succinate (PET / PES), and copolymers of polybutylene terephthalate and polybutylene adipate (PBT / PBA). Each of the above resins may be used individually or in mixtures of two or more.

[0039] The film constituting the food packaging bag 1A may be a single layer. When the film constituting the food packaging bag 1A is a single layer, the film is preferably made of a material selected from olefin resins, biomass resins, and biodegradable resins, and more preferably made of either an unstretched olefin resin or a biodegradable resin.

[0040] Figure 5 is a cross-sectional view showing an example of the laminated structure of the laminated film constituting the food packaging bag 1A in Figure 1. As shown in Figure 5, the laminated film (I) has a surface layer (A) containing a propylene resin, an intermediate layer (C) containing a propylene resin, and a heat-seal layer (B) with a thickness of 1 μm to 8 μm that contains a 1-butene copolymer (b1) in which 1-butene and propylene are essential components, and a copolymer (b2) in which propylene and ethylene are essential components. As described above, the laminated film (I) constitutes a pair of main surfaces 11 and 12 (see Figure 2(B)). By constructing the pair of main surfaces 11 and 12 from a laminated film (I), the heat sealability is improved, the strength of the pair of reinforcing seal portions 15A and 16A is enhanced, and the heat-sealed seal portions 13 and 14 can be reinforced more firmly.

[0041] The surface layer (A) may be a resin layer that mainly consists of one or more propylene-based resins, preferably containing 75% by weight or more, such as a propylene homopolymer; a random copolymer of propylene and ethylene; a block copolymer of propylene and ethylene; or a copolymer of propylene and α-olefins other than ethylene; and optionally mixed with other thermoplastic resins such as ethylene-1-butene copolymer and linear low-density polyethylene, or various additives.

[0042] The intermediate layer (C) may be a resin layer mainly composed of one or more propylene-based resins, such as a propylene homopolymer, a random copolymer of propylene and ethylene, a block copolymer of propylene and ethylene, or a copolymer of propylene and an α-olefin other than ethylene, preferably containing 70% by weight or more. Optionally, other thermoplastic resins such as ethylene-1-butene copolymer or linear low-density polyethylene, or recovered materials generated during the production of this laminated film may be mixed in. Alternatively, the intermediate layer (C) may be a resin layer having the same composition as the surface layer (A).

[0043] Furthermore, the above intermediate layer (C) can be divided into two or more layers, and the overall layer structure may consist of three or more layers.

[0044] The heat seal layer (B) may be any resin layer containing a 1-butene copolymer consisting of 1-butene and other α-olefins. However, it is preferable to use a 1-butene copolymer (b1) in which 1-butene and propylene are essential components. In particular, it is preferable to use a resin layer in which the 1-butene copolymer (b1) and a copolymer (b2) in which propylene and ethylene are essential components are used in combination in a weight ratio (b1) / (b2) of 25 / 75 to 75 / 25, as this allows for easy adjustment of the heat seal temperature and strength during easy opening seals at low temperatures, provides a wide heat seal temperature range, and easily obtains appropriate heat seal strength for easy opening seals. Furthermore, it is especially preferable that the 1-butene copolymer (b1) used here has a 1-butene-derived component content of 50 to 99 mol%.

[0045] Furthermore, it is preferable that the heat seal initiation temperature of the heat seal layer (B), measured in accordance with the heat seal initiation temperature test specified in JIS K-1713, is lower than the heat seal initiation temperature of the surface layer (A), as this facilitates the creation of food packaging bags and easy-open sealing. For this reason, it is preferable that the heat seal initiation temperature difference between the surface layer (A) and the heat seal layer (B) of the laminated film (I) according to the present invention be 30°C or more, and more preferably 35 to 90°C.

[0046] The thickness of the laminated film (I) is usually 20 to 50 μm, but is preferably 25 to 40 μm.

[0047] When the laminated film (I) is a three-layer film formed by laminating (A) / (C) / (B) in that order, the thickness ratio of the surface layer (A) and the intermediate layer (C) to the total thickness varies depending on the resin composition of each layer and is not particularly limited, but the surface layer (A) is usually 10-50%, preferably 15-45%, and the intermediate layer (C) is usually 30-80%, preferably 40-70%.

[0048] The thickness of the heat seal layer (B) depends on the thickness of the laminated film (I), but is preferably 1 μm to 8 μm, and more preferably 2 μm to 7 μm.

[0049] Specific examples of laminated films (I) include the following: (i) A three-layer film (I-1) suitable for bags with a thickness of 25 μm or 30 μm and a gusset at the bottom (hereinafter referred to as a bottom gusset bag), comprising: (i) a surface layer (A1) containing 75% by weight or more of a propylene copolymer in which propylene and ethylene are essential components; an intermediate layer (C1) containing 70% by weight or more of a propylene homopolymer; and a heat-seal layer (B1) containing 25 to 75% by weight of a monobutene copolymer in which 1-butene and propylene are essential components, laminated in the order (A1) / (C1) / (B1) such that the ratio of their average thicknesses is 3:6:1; (ii) A surface layer (A2) containing 90% by weight or more of a propylene homopolymer, and a propylene homopolymer and / or a propylene homopolymer with propylene and ethylene as essential components. A three-layer film (I-2) suitable for pillow packaging bags, having a thickness of 25 μm or 30 μm, is formed by laminating an intermediate layer (C2) containing 90% by weight or more of a polymer-based copolymer and the heat-seal layer (B1) in the order (A2) / (C2) / (B1) such that the ratio of their average thicknesses is 2:7:1; or (iii) A three-layer film (I-3) suitable for bottom gusset bags, having a thickness of 25 μm or 30 μm, comprising: (iii) a surface layer (A3) containing 80% by weight or more of a propylene homopolymer and / or a propylene copolymer having propylene and ethylene as essential components; an intermediate layer (C3) containing a total of 70% by weight or more of a propylene copolymer having linear low-density polyethylene, propylene and ethylene as essential components; and the heat-seal layer (B1), laminated in the order of (A3) / (C3) / (B1) such that the ratio of their average thicknesses is 3:6:1.

[0050] The laminated film (I) may be used as is, but the surface layer (A) may be subjected to corona discharge treatment to enhance the product appeal through printing. In addition, additives such as antioxidants, slip agents, antiblocking agents, antifogging agents, colorants, and silica may be added to each layer of the laminated film (I) as needed, within the scope of the present invention.

[0051] The method for manufacturing the laminated film (I) is not particularly limited, but co-extrusion molding and extrusion lamination are preferred, and co-extrusion molding is particularly preferred.

[0052] <Method for manufacturing and reinforcing food packaging bags> The method for manufacturing a food packaging bag according to this embodiment is a method for manufacturing a food packaging bag formed from a film, comprising the steps of forming a pair of reinforcing seal portions on at least a portion of the portions on both sides in the width direction of a pair of opposing main surfaces where a pair of heat-seal portions are formed, and forming a pair of heat-seal portions at both ends in the width direction of the pair of main surfaces.

[0053] Figures 6(A) to 6(C) are schematic diagrams showing an example of a method for manufacturing a food packaging bag according to this embodiment. In Figures 6(A) to (C), a bottom gusset bag is used as an example of a food packaging bag for explanation. First, a printed area (not shown) is formed by printing patterns, characters, etc., as needed on the main surface 11 and / or main surface 12, which are made of, for example, three layers of laminated film. Then, the main surface 11 and main surface 12 are placed opposite each other so that the heat-seal layer is on the inside of the bag, and the bottom gusset is sandwiched between the pair of main surface 11 and 12 so that it is folded inward into the bag (Figure 6(A)).

[0054] Next, a pair of reinforcing seal portions 15A and 16A are formed on both sides in the width direction of the pair of opposing main surfaces 11 and 12, where the pair of heat-seal portions are formed (Figure 6(B)). In this embodiment, in a later step, the pair of heat-seal portions 13 and 14 are formed over the entire pair of main surfaces 11 and 12 in a direction perpendicular to the width direction of the pair of main surfaces 11 and 12 (the direction from the opening 17 toward the bottom gusset 18). Therefore, in this step, the pair of reinforcing seal portions 15A and 16A are formed over the entire pair of main surfaces 11 and 12 in a direction perpendicular to the width direction of the pair of main surfaces 11 and 12.

[0055] In this case, it is preferable to heat-seal the pair of main surfaces 11 and 12 to form a pair of reinforcing seal portions 15A and 16A as a pair of heat-sealed portions. Furthermore, heat sealing can be performed under conditions where the heat seal strength is 10 to 20 N / 15 mm, preferably 12 to 18 N / 15 mm. The pair of reinforcing seal portions 15A and 16A can be formed, for example, by installing a known heat-sealing unit in a bag-making machine.

[0056] In this process, it is preferable to form a reinforcing seal portion 15A at the portion 26' corresponding to the triangular vertex portion 26, which is the intersection point between the two widthwise folded ends 18a and 18b of the bottom gusset 18 and the heat-sealed portion 13 formed in a later process. Similarly, it is preferable to form a reinforcing seal portion 16A at the portion 27' corresponding to the triangular vertex portion 27 on the heat-sealed portion 14 side.

[0057] Subsequently, a pair of heat-sealed portions 13 and 14 are formed at both ends in the width direction of the pair of main surfaces 11 and 12 (Figure 6(C)). In this embodiment, as described above, the pair of heat-sealed portions 13 and 14 are formed over the entire pair of main surfaces 11 and 12 in a direction perpendicular to the width direction of the pair of main surfaces 11 and 12. At this time, the heat-sealing temperature and bag-making speed can be adjusted so that the heat-sealing strength at the width direction ends of the pair of main surfaces 11 and 12 and the width direction ends of the bottom gusset 18 is 7.5 to 30 N / 15 mm, preferably 12 to 30 N / 15 mm. The pair of heat-sealed portions 13 and 14 can be formed, for example, by a bag-making machine. Through the above process, a bottom gusset bag for food packaging bag 1A is formed.

[0058] As a post-molding step for the bottom gusset bag, the bottom gusset bag can be supplied to a filling machine corresponding to the filling to be placed inside. For example, when filling a bottom gusset bag with bread, the bottom gusset bag is supplied to an automatic bread filling machine, and after the bread is filled into the bottom gusset bag, it is heat-sealed to become a bread packaging bag. At this time, the heat sealing can be performed under conditions that make it easy to open and have a heat seal strength of 0.1 to 5 N / 15 mm, preferably 0.2 to 3.5 N / 15 mm. After that, if necessary, the top of the bag, preferably the top of the bread, is secured using fasteners such as plastic plates, tape, or string at the easy-open seal portion (heat-sealed portion) or near the top or bottom of it.

[0059] In this embodiment, the process of forming a pair of reinforcing seal portions is performed after the process of forming a pair of heat-sealed seal portions. However, the process is not limited to this, and the process of forming a pair of reinforcing seal portions and the process of forming a pair of heat-sealed seal portions may be performed together.

[0060] As described above, according to this embodiment, the food packaging bag 1A has a pair of reinforcing seal portions 15A and 16A formed inside the pair of heat-sealed portions 13 and 14 in the width direction of the pair of main surfaces 11 and 12, and reinforcing seal portions 15A and 16A that reinforce the pair of heat-sealed portions 13 and 14. As a result, the load on the pair of heat-sealed portions 13 and 14 is reduced by the pair of reinforcing seal portions 15A and 16A, making the food packaging bag 1A less likely to tear and enabling high reusability.

[0061] Furthermore, if the food packaging bag 1A is a bottom gusset bag with a bottom gusset 18, the opening 17 is large, making it easy to dispose of waste when reusing it as a garbage bag. Also, if the food packaging bag 1A is a bread bag, it has high deodorizing and moisture-proofing effects, making it less likely for odors to be released when garbage is placed inside. Moreover, the deodorizing effect can be further enhanced by sealing the opening 17 with a heat-sealed section using a household heat sealer. Therefore, it is useful as a substitute for garbage bags, and as a result, it is possible to promote reuse.

[0062] Furthermore, since food packaging bag 1A has higher strength than conventional food packaging bags, it is less likely to tear even after being washed or otherwise treated. Therefore, used food packaging bag 1A can be collected, thoroughly washed and sterilized, and then reused as food packaging bags.

[0063] Furthermore, when the food packaging bag 1A is opened, the triangular vertices 26 and 27, which are the intersections of the two widthwise folded ends of the bottom gusset 18 and the heat-sealed portions 13 and 14, are reinforced by the reinforcing seal portions 15A and 16A. By reinforcing the triangular vertices 26 and 27, which are subjected to the greatest load when an object is placed inside the bottom gusset bag, the strength of the food packaging bag 1A can be further improved.

[0064] Furthermore, according to this embodiment, a pair of reinforcing seal portions 15A and 16A are formed on at least a portion of the widthwise sides of the pair of opposing main surfaces 11 and 12 where the pair of heat-seal portions 13 and 14 are formed, and then a pair of heat-seal portions 13 and 14 are formed at both widthwise ends of the pair of main surfaces 11 and 12. As a result, a tear-resistant food packaging bag 1A can be easily manufactured without significantly changing the conventional method of manufacturing food packaging bags.

[0065] Figures 7(A) and 7(B) are schematic diagrams showing modified examples of the areas where the fusible seal portion 13 in Figure 4(A) and the reinforcing seal portion 15A in Figure 4(B) are formed. As shown in Figures 7(A) and 7(B), the heat-sealed portion 13 may be the same as in the above embodiment, and the reinforcing seal portion 15B may be formed on the bottom gusset 18 including the triangular vertex portion 26. By reinforcing the bottom gusset 18, which is prone to load when items are placed inside the bottom gusset bag, the strength of the food packaging bag 1A can be improved while reducing the amount of reinforcement and simplifying the process.

[0066] Furthermore, as another modification, as shown in Figures 8(A) and 8(B), the heat-sealed portion 13 may be the same as in the above embodiment, and the reinforcing seal portion 15C may be formed only on the triangular vertex portion 26. By reinforcing only the triangular vertex portion 26, which is most susceptible to load when an object is placed inside the bottom gusset bag, the amount of reinforcement can be minimized, further simplifying and streamlining the process while improving the strength of the food packaging bag 1A.

[0067] Furthermore, in the above embodiment, the reinforcing seal portion 15A extends along the extending direction of the heat-seal portion 14 and over the entire heat-seal portion 14, but this is not limited to this. As shown in Figures 9(A) and 9(B), the reinforcing seal portions 15D and 16D may be formed discontinuously along the extending direction of the heat-seal portion 13. That is, multiple reinforcing seal portions 15d, 15d, ... may be arranged side by side along the extending direction of the heat-seal portion 13, and multiple reinforcing seal portions 16d, 16d, ... may be arranged side by side along the extending direction of the heat-seal portion 14. In this modified example as well, the strength of the food packaging bag 1A can be improved while simplifying the process by reducing the amount of reinforcement.

[0068] Figure 10 is a plan view showing a modified example of the food packaging bag 1A in Figure 2(A). In Figure 2(A), the food packaging bag 1A is a bottom gusset bag, but it is not limited to this, and the food packaging bag 1B may be a boat-bottom bag. In this case as well, as shown in Figure 10, the food packaging bag 1B may have a pair of reinforcing seal portions 15E, 16E formed inside a pair of heat-sealed portions 13, 14 in the width direction of a pair of main surfaces 11, 12, and reinforcing at least a part of the pair of heat-sealed portions 13, 14. This makes the boat-bottom bag, which is the food packaging bag 1B, less likely to tear, and enables high reusability.

[0069] Although this embodiment has been described above, the present invention is not necessarily limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. [Examples]

[0070] The following describes embodiments of the present invention. The present invention is not limited to the embodiments shown below.

[0071] [Example 1] Resin mixtures were prepared to form each layer, using the following resins as the resin components for the surface layer, intermediate layer, and heat seal layer. These mixtures were supplied to three extruders and co-extruded so that the average thickness of each layer of the laminated film formed by the surface layer, intermediate layer, and heat seal layer was 7 μm, 18 μm, and 5 μm, respectively, to form a laminated film with a thickness of 30 μm. Next, the printed layer of the obtained laminated film was subjected to corona discharge treatment to obtain a laminated film with a surface energy of 35 mN / m. Surface layer: Propylene-ethylene copolymer (ethylene-derived component content: 5.0% by mass, density: 0.90 g / cm³) 3 MFR (measurement temperature 230℃): 7g / 10min) (hereinafter referred to as COPP(1)) 90% by mass, ethylene-butene-rubber copolymer (density: 0.890g / cm³) 3 Melting point 66°C, MFR (measurement temperature: 190°C): 3g / 10 minutes) (hereinafter referred to as EBR(1)) 10% by mass Intermediate layer: COPP(1) 15% by mass, propylene homopolymer (density: 0.90 g / cm³) 3 MFR (measurement temperature: 230℃): 8g / 10min) (hereinafter referred to as HOPP(1)) 75% by mass, linear low-density polyethylene (density: 0.905g / cm³) 3 MFR (measurement temperature 190℃): 4g / 10min) (hereinafter referred to as LLDPE(1)) 10% by mass Heat seal layer: COPP(1) 70% by mass, 1-butene-propylene copolymer (density: 0.90 g / cm³) 3 MFR (measurement temperature 230℃): 4g / 10 minutes) (hereinafter referred to as 1-butene copolymer (1)) 30% by mass

[0072] [Example 2] A laminated film was obtained in the same manner as in Example 1, except that the resin components of the resin mixture used for the intermediate layer were as follows. Intermediate layer: 65 parts by mass of HOPP(1), 10 parts by mass of COPP(2), 10 parts by mass of LLDPE(1), 15 parts by mass of sugarcane-derived linear low-density polyethylene resin (density: 0.916 g / cm³, MFR = 2.3 g / 10 min) (hereinafter referred to as BioPE(1))

[0073] Next, using a high-speed side-weld automatic bag-making machine (manufactured by Totani Giken Kogyo Co., Ltd., machine name "HK-40V"), a bottom-gusseted bag for bread was made from the obtained laminated film under the conditions of a bag-making speed of 140 bags / min, a reinforcement seal temperature of 160°C, and a heat-seal temperature of 300°C. At this time, the laminated film was folded into a predetermined shape so that a bottom gusset would be provided, and then a pair of reinforcement seal sections and a pair of heat-seal sections were formed on both sides of the folded structure.

[0074] [Comparative Example 1] A bottom gusset bag was manufactured from a laminated film in the same manner as in Example 1, except that a pair of reinforcing seal sections were not formed on both sides of the folded structure, and only a pair of heat-sealed sections were formed.

[0075] [Evaluation Method] (Bag tear resistance at the heat-sealed portion when the bag is opened) The bottom gusset bags obtained in Example 1, Example 2, and Comparative Example 1 were tested by repeatedly spreading the opening of the bag wide with both hands 50 times, and checking whether tearing occurred in one or both of the heat-sealed sections during this process. The test was repeated 10 times (N=10). The results are shown in Table 1.

[0076] (Break resistance at the triangular vertex) In Example 1, Example 2, and Comparative Example 1, an arm was inserted through the opening of the bottom gusset bag, and the action of pressing a fist firmly against the bottom surface from the inside of the bag was repeated 50 times. The test was performed to see if tearing occurred at one or both of the triangular vertices during this time. The number of tests was 10 (N=10). The results are shown in Table 2.

[0077] [Table 1]

[0078] [Table 2]

[0079] As shown in Table 1, no tears were observed in the heat-sealed portion in Example 1, indicating good tear resistance at the heat-sealed portion. In addition, tears occurred at the triangular vertices in 4 out of 10 tests, and the average number of operations in which tears occurred at the triangular vertices was 44, indicating good tear resistance at the triangular vertices.

[0080] Furthermore, no tears were observed in the heat-sealed portion in Example 2, indicating good tear resistance at the heat-sealed portion. In addition, tears occurred at the triangular apex in 5 out of 10 tests, and the average number of operations required for tears at the triangular apex to occur was 43, indicating good tear resistance at the triangular apex.

[0081] On the other hand, in Comparative Example 1, although no tears were observed in the heat-sealed portion, tears occurred at the triangular apex in 7 out of 10 tests, and the average number of operations in which tears occurred at the triangular apex was 18, indicating poor tear resistance at the triangular apex. [Explanation of Symbols]

[0082] 1A Food packaging bag 1B Food packaging bag 11 Main surface 12 Main surface 13. Fused seal section 14. Fusible sealing section 15A Reinforcement seal section 15B Reinforcement seal section 15C Reinforcement seal section 15d Reinforcement seal section 15D Reinforcement seal section 15E Reinforcement seal section 16A Reinforcement seal section 16d Reinforcement seal section 16D Reinforcement seal section 16E Reinforcement seal section 17 Opening 18 Bottom gusset 18a Width-direction folded edge 18b Width-direction folded edge 19 Printing Department 21 Bottom 22 First aspect 23 Second aspect 24 Third aspect 25 Fourth aspect 26. Triangular vertices 27. Triangular vertices

Claims

1. A food packaging bag made of film, In a flat bag state, a pair of main surfaces are arranged opposite each other, A pair of heat-sealing portions formed at both ends in the width direction of the pair of main surfaces, A pair of reinforcing seal portions are formed on the inside of the pair of heat-seal portions with respect to the width direction of the pair of main surfaces, and reinforce at least a portion of the pair of heat-seal portions. It has, It further has a bottom gusset located on the opposite side of the openings of the pair of main surfaces and extending across the entire width of the pair of main surfaces, The pair of reinforcing seal portions are formed at least at the triangular vertices where the two widthwise folded ends of the bottom gusset intersect with the heat-sealed portion. The aforementioned triangular apex is located at the intersection of the widthwise folded end of the bottom gusset and the heat-sealed portion, and is the part that is most susceptible to stress when items are filled into the bottom gusset bag. Food packaging bags.

2. The food packaging bag according to claim 1, wherein the film is a laminated film having a film containing a material selected from biomass resins and biodegradable resins.

3. The food packaging bag according to claim 1, wherein the reinforcing seal portion extends along the extending direction of the heat-sealed seal portion and over the entire heat-sealed seal portion.

4. The food packaging bag according to any one of claims 1 to 3, wherein the reinforcing seal portion is a heat-sealed portion in which a pair of main surfaces are heat-sealed to each other.

5. The food packaging bag according to any one of claims 1 to 4, wherein the film is a laminated film obtained by laminating a plurality of films made of one or more materials selected from olefin resins, biomass resins, and biodegradable resins.

6. The food packaging bag according to claim 5, wherein the film is a laminated film obtained by laminating a plurality of films made of one or two of an unstretched olefin resin and a biodegradable resin.

7. The laminated film is A surface layer (A) containing a propylene resin, An intermediate layer (C) containing a propylene resin, A heat-seal layer (B) having a thickness of 1 μm or more and 8 μm or less, comprising a 1-butene copolymer (b1) having 1-butene and propylene as essential components and a copolymer (b2) having propylene and ethylene as essential components, A food packaging bag according to claim 5 or 6, having the following features.

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