Stand-up pouches

Abstract

To provide a self-standing packaging bag which is useful for realizing mono-materialization and has sufficient resistance to drop impact.SOLUTION: A self-standing packaging bag is formed by heat-sealing a first body part, a second body part, and a bottom tape which is constituted by a third laminated film containing a third base material layer and a third sealant layer and has a ridge-folding part. The third sealant layer contains a polyethylene resin having an MD elastic modulus of 50-150 MPa and having a TD elastic modulus of 50-150 MPa, and further having a density of 0.90-0.92 g / cm3. A breaking strength per unit cross-sectional area of the third laminated film is 25 N / mm2 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to self-standing packaging bags. [Background technology]

[0002] Packaging bags are made from a variety of materials, depending on factors such as the nature and quantity of the contents, post-processing to prevent deterioration of the contents, the form in which the package (the bag containing the contents) is transported, the method of opening the package, and the method of disposal.

[0003] Self-standing packaging bags, such as standing pouches, are gaining popularity because they allow products to stand out on store shelves. For the pouch to remain fully visible without bending, the laminated film constituting the pouch needs to have a certain degree of rigidity. Furthermore, if the pouch contains a liquid, it must be strong enough to prevent rupture and leakage upon impact from a fall. To address these requirements, laminates combining polyester film, nylon film, polyolefin film, and other materials have been used (see Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-237281 [Patent Document 2] Japanese Patent Application Publication No. 7-241967 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, with the growing awareness of environmental issues, resource conservation and reuse are being demanded in the field of packaging bags. For example, from a resource conservation perspective, there is a trend to fill a single refill pouch with enough contents for multiple refills. However, if the volume of contents is large, the impact when dropped will be greater, increasing the risk of leakage when dropped. One way to improve drop resistance is to make the film that makes up the pouch (for example, sealant film) thicker. However, this goes against the goal of reducing the amount of plastic used.

[0006] A technology is also being considered in which the laminated film constituting the packaging material is made of materials of the same type, thereby reusing the packaging material as a single integrated material. This is called monomaterialization of packaging materials. As mentioned above, conventional packaging materials have improved required physical properties, such as drop resistance, by combining various dissimilar materials. However, when packaging materials are made of materials of the same type, there is a challenge in ensuring sufficient drop resistance.

[0007] This disclosure provides a self-standing packaging bag that is useful for realizing monomaterialization and has sufficient drop resistance. [Means for solving the problem]

[0008] A self-standing packaging bag relating to one aspect of this disclosure is formed by heat-sealing a first body portion composed of a first laminated film including a first base layer and a first sealant layer, a second body portion composed of a second laminated film including a second base layer and a second sealant layer, and a bottom tape composed of a third laminated film including a third base layer and a third sealant layer and having a mountain fold portion. The third sealant layer has an MD modulus of 50 to 150 MPa and a TD modulus of 50 to 150 MPa, and a density of 0.85 to 0.94 g / cm³. 3 It contains polyethylene resin, and the third laminated film has a breaking strength of 25 N / mm² per unit cross-sectional area. 2 That's all.

[0009] The inventors of this invention, polyethyleneAiming for monomaterialization using resin, a standing pouch was first fabricated using polyethylene film in each layer of the first, second, and third laminated films, all with the same configuration. When 400cc of water was sealed in this standing pouch and its drop resistance was evaluated, cracks frequently occurred in the folded portion of the bottom tape (see Figure 8, which shows the results of Comparative Example 1 described later). In conventional standing pouches made of composite materials, rupture often occurs in the bottom seal portion, and it is presumed that this phenomenon is mainly due to monomaterialization using polyethylene resin. To increase the breaking strength of the bottom tape, the inventor focused on the third sealant layer of the bottom tape and set its elastic modulus relatively low. It was thought that this would make cracks less likely to occur in the folded portion. As a result of many prototypes and evaluations, by setting both the MD elastic modulus and TD elastic modulus of the third sealant layer to 50-150 MPa, the frequency of cracks occurring in the folded portion was sufficiently reduced, making it possible to stably obtain a self-standing packaging bag with sufficient drop resistance.

[0010] In this disclosure, MD modulus refers to the modulus of elasticity in the MD (Machine Direction) of the third sealant layer, and TD refers to the modulus of elasticity in the TD (Transverse Direction) of the third sealant layer. The modulus of elasticity and breaking strength refer to values ​​measured in accordance with the method described in JIS K7161. The measurement is performed on a sample measuring 15 mm in width and 60 mm in length, with a chuck distance of 50 mm and a tensile speed of 200 mm / min. The breaking strength per unit cross-sectional area is obtained by dividing the measured breaking strength (N / 15 mm) by the cross-sectional area of ​​the sample (sample thickness × 15 mm). The breaking strength of the bottom tape is 25 N / mm for both MD and TD. 2 It is preferable that the above conditions are met. [Effects of the Invention]

[0011] According to this disclosure, a self-standing packaging bag is provided that is useful for realizing monomaterialization and has sufficient drop resistance. [Brief explanation of the drawing]

[0012] [Figure 1] FIG. 1 is a front view schematically showing a self-standing packaging bag according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically showing the configuration of the self-standing packaging bag shown in FIG. 1. [Figure 3] FIG. 3 is a perspective view schematically showing a pair of main body parts and a bottom tape constituting the self-standing packaging bag shown in FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view schematically showing an example of a bottom tape provided with a sealant layer having a multilayer structure. [Figure 5] FIG. 5 is a diagram showing the results of Example 1. [Figure 6] FIG. 6 is a diagram showing the results of Example 2. <00照00106>FIG. 7 is a diagram showing the results of Example 3. [Figure 8] FIG. 8 is a diagram showing the results of Comparative Example 1. [[ID=2参7]]

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described in detail. Here, a standing pouch in which monomerization is realized will be described as an example. The standing pouch is used as a refill pouch for shampoo, hand soap, detergent, etc., or a pouch for soup, seasoning, etc. Note that the present invention is not limited to the following embodiments.

[0014] <00照00117><Standing Pouch> Figure 1 is a schematic front view showing a standing pouch (self-standing packaging bag) according to this embodiment. Figure 2 is a schematic cross-sectional view showing the structure of the standing pouch. The standing pouch 10 shown in these figures is formed by heat-sealing a pair of main body parts 1 and 2 (first and second main body parts) and a bottom tape 3. Each of the pair of main body parts 1 and 2 is composed of a laminated film 1F that includes at least a base material layer L1 (first and second base material layers) and a sealant layer L2 (first and second sealant layers). The bottom tape 3 is composed of a laminated film 3F that includes at least a base material layer L3 (third base material layer) and a sealant layer L4 (third sealant layer). The formation of the standing pouch by heat sealing can be carried out in the same way as conventional methods.

[0015] From the viewpoint of recyclability, the pair of main body parts 1 and 2 and the bottom tape 3 are all made of a polyethylene resin composition. The polyethylene content of the standing pouch 10 is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more.

[0016] (Bottom tape) The bottom tape 3 has a single mountain-fold portion 3a. That is, when the standing pouch 10 is upright, the bottom tape 3 is arranged in an inverted V shape (see Figures 2 and 3). As described above, measures have been taken to prevent cracks from forming in the mountain-fold portion 3a of the bottom tape 3 even if the standing pouch 10 is subjected to impact from a fall. The sealant layer L4 and the base material layer L3 that constitute the bottom tape 3 will be described below.

[0017] The sealant layer L4 is composed of a material with a relatively low modulus of elasticity. The MD modulus of the sealant layer L4 is 50 to 150 MPa, preferably 70 to 150 MPa, and more preferably 90 to 150 MPa. A value of 50 MPa or higher provides sufficient rigidity to the bottom tape 3, while a value of 150 MPa or lower allows the sealant layer L4 to absorb the impact of a fall and provides the bottom tape 3 with sufficient bending resistance. The TD modulus of the sealant layer L4 is 50 to 150 MPa, preferably 70 to 130 MPa, and more preferably 90 to 130 MPa. A value of 50 MPa or higher provides sufficient rigidity to the bottom tape 3, while a value of 150 MPa or lower allows the sealant layer L4 to absorb the impact of a fall and provides the bottom tape 3 with sufficient bending resistance. Note that in Figure 1, arrow M indicates MD and arrow T indicates TD.

[0018] From the viewpoint that the sealant layer L4 satisfies the above-mentioned elastic modulus conditions, it is preferable that the sealant layer L4 contains at least one of linear low-density polyethylene (L-LDPE) and very low-density polyethylene (VLDPE). Linear low-density polyethylene is a copolymer of ethylene and α-olefin, and from the above viewpoint, suitable α-olefins include propylene (C3), butene (C4), pentene (C5), hexene (C6), heptene (C7), and octene (C8), and among these, hexene (C6), heptene (C7), and octene (C8) are more suitable α-olefins. Hexene-based linear low-density polyethylene is a copolymer of ethylene and hexene. Heptene-based linear low-density polyethylene is a copolymer of ethylene and heptene. Octene-based linear low-density polyethylene is a copolymer of ethylene and octene.

[0019] The melt flow rate (hereinafter referred to as "MFR") of the polyethylene resin contained in the sealant layer L4 is preferably 5 g / 10 min or less, more preferably 0.5 to 4.5 g / 10 min, and even more preferably 1 to 4 g / 10 min. Polyethylene resins with a value of 5 g / 10 min or less contain constituent resins with relatively high molecular weights and tend to exhibit high strength against impact after film formation. On the other hand, a value of 0.5 g / 10 min or more results in a lower processing load on the extrusion process for film formation, making it easier to process, and tends to increase the tensile strength of the resin film while maintaining a low modulus of elasticity. In this disclosure, MFR refers to the value measured under conditions of a load of 2.16 kg and a temperature of 190°C, in accordance with the method described in JIS K7210.

[0020] The melting point of the sealant layer L4 is preferably 110°C or lower, and more preferably 95 to 110°C. From the viewpoint of low-temperature sealing performance, it is preferable that the sealant layer L4 contains a polyethylene resin with a melting point of 110°C or lower. In this disclosure, the melting point refers to a value measured using a differential scanning calorimetry (DSC).

[0021] The thickness of the sealant layer L4 is, for example, 40 to 150 μm, and may be 60 to 140 μm or 80 to 120 μm. The polyethylene resin contained in the sealant layer L4 may be one type or multiple types. The sealant layer L4 may be a single layer or a multilayer layer. By containing a relatively low-density polyethylene resin, the sealant layer L4 can achieve both high elasticity and high flexural resistance to a high degree. The density of the polyethylene resin is, for example, 0.85 to 0.94 g / cm³. 3 The concentration is preferably 0.90 to 0.92 g / cm³. 3 Therefore, 0.85~0.915 g / cm³ 3 That's fine.

[0022] The degree of dispersion (Mw / Mn) of the polyethylene resin contained in the sealant layer L4 is preferably 7.0 or more, and may be 7.5 to 15.0. The fact that this value is 7.0 or more means that the molecular weight distribution of the polyethylene resin is relatively broad, that is, it means that the polyethylene resin contains components from low molecular weight components to high molecular weight components. The high molecular weight components contribute to the improvement of the breaking strength. On the other hand, the low molecular weight components are presumed to have the effects of imparting low temperature sealability, reducing the resin viscosity to impart flexibility, and improving the processability. Such a polyethylene resin is presumed to have the effect of imparting sufficient flex resistance to the base tape 3 and also contribute to the reduction of the elasticity of the sealant layer L4. The degree of dispersion (Mw / Mn) of the polyethylene resin can be measured using gel permeation chromatography (GPC).

[0023] When the sealant layer L4 is a single layer, the content of the above polyethylene resin in the sealant layer L4 is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and still more preferably 70 to 95% by mass based on the mass of the sealant layer L4. When this value is 50% by mass or more, the above effects are sufficiently achieved, and there is a tendency to highly realize monomaterialization.

[0024] When the sealant layer L4 is a multilayer, the sealant layer L4 may include an A layer composed of a polyethylene resin (hereinafter referred to as "polyethylene resin A") having a density of 0.85 g / cm 3 or more and less than 0.910 g / cm 3 and a B layer composed of a polyethylene resin (hereinafter referred to as "polyethylene resin B") having a density of 0.910 g / cm 3 or more and less than 0.925 g / cm 3 (see FIG. 4). By including the A layer in the sealant layer L4, excellent flex resistance can be achieved to a higher degree. The ratio (Tb / Ta) of the thickness Tb of the B layer to the thickness Ta of the A layer is preferably 1 to 10, more preferably 1.75 to 10, and still more preferably 2 to 10. It is preferable that the A layer constitutes the heat seal surface.

[0025] The base layer L3 is preferably composed of an unstretched or stretched polyethylene resin film. If the base layer L1 is unstretched, the resin has almost no orientation, making it easily stretchable and less prone to breakage under external stresses such as tension and shear. On the other hand, if the base layer L1 is stretched, it is easier to achieve high resistance to punctures and bending while maintaining a certain hardness. The thickness of the base layer L3 is, for example, 5 to 200 μm, and may be 5 to 100 μm or 10 to 50 μm. The base layer L3 preferably has a melting point 20°C or more high, and more preferably 25°C or more high, than the sealant layer L4. The difference in their melting points suppresses the melting of the base layer L3 during the heat sealing process.

[0026] The melting point of the base layer L3 is preferably 120°C or higher, and more preferably 125°C or higher. Examples of polyethylene constituting the base layer L3 include high-density polyethylene (HDPE) and medium-density polyethylene (MDPE). Of these, HDPE and MDPE with a density of 0.925 g / cm³ are preferred from the viewpoint of heat resistance. 3 It is preferable to use the above materials. In particular, materials with a density of 0.93 to 0.98 g / cm³ are preferred. 3 It is preferable to use high-density polyethylene within the specified range.

[0027] The breaking strength per unit cross-sectional area of ​​laminated film 3F is 25 N / mm². 2 The above is the standard, preferably 25-100 N / mm². 2 The power is 25-80 N / mm². 2 Or 25-50 N / mm 2 This may also be the case. This value is 25 N / mm 2 This provides a fracture-preventing effect against tensile stress, while 100 N / mm 2The following conditions are met, which have the effect of suppressing complete fracture even if the laminated film 3F is subjected to an impact caused by the fracture of a part of the laminated film 3F (e.g., the base layer L3), by stretching the unbroken part (e.g., the sealant layer L4). In this disclosure, the fracture strength refers to the value measured in accordance with the method described in JIS K7161. The measurement is performed on a sample with a width of 15 mm and a length of 30 mm, under the conditions of a chuck distance of 20 mm and a tensile speed of 5 mm / min. The fracture strength per unit cross-sectional area is obtained by dividing the measured fracture strength (N / 15 mm) by the cross-sectional area of ​​the sample (sample thickness × 15 mm).

[0028] (Main body) Both main body sections 1 and 2 are composed of a laminated film 1F including a base layer L1 and a sealant layer L2. The material constituting the base layer L1 may be the same as that of the base layer L3. On the other hand, the material constituting the sealant layer L2 may be the same as or different from the material constituting the sealant layer L4. From the viewpoint of the self-supporting nature of the standing pouch 10, it is preferable that the material constituting the sealant layer L2 exhibits greater rigidity than the material constituting the sealant layer L4. As the polyethylene resin constituting the sealant layer L2, for example, linear low-density polyethylene (LLDPE) and very low-density polyethylene (VLDPE) can be used. Of these, 0.90 to 0.92 g / cm³ can be used. 3 It is preferable to use polyethylene having a density of . From the viewpoint of heat sealability, the melting point of the resin constituting the sealant layer L2 is preferably 110°C or lower, and more preferably 95 to 110°C.

[0029] The thickness of the sealant layer L2 is, for example, 30 to 150 μm, or it may be 60 to 150 μm. By adjusting the thickness of the sealant layer L2, the bendability and rigidity of the laminated film 1F can be adjusted.

[0030] The polyethylene resin contained in the base layer and sealant layer in this disclosure is not limited to petroleum-derived materials, and may be partially or entirely bio-derived resin materials (for example, biomass polyethylene using biomass-derived ethylene as a raw material). A method for producing biomass-derived polyethylene is disclosed, for example, in Japanese Patent Publication No. 2010-511634. The polyethylene resin may include commercially available biomass polyethylene (such as Green PE manufactured by Braschem), or it may include mechanically recycled polyethylene made from used polyethylene products or resin (so-called burrs) generated during the manufacturing process of polyethylene products.

[0031] The base layer and sealant layer in this disclosure may contain components other than polyethylene resin. Examples of such components include polyamide, polyethylene terephthalate, polypropylene, polyvinyl alcohol, and biodegradable resin materials (e.g., polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, etc.). The base layer and sealant layer may also contain additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, and colorants. The amount of components other than polyethylene resin in the standing pouch 10 is preferably 10% by mass or less, and more preferably 5% by mass or less, based on the mass of the standing pouch 10.

[0032] The specific structure of the standing pouch is described below. As shown in Figure 2, the bottom of the standing pouch 10 is composed of a heat-sealed section 5 and a heat-sealed section 6. The heat-sealed section 5 is the part where the bottom 1a of the main body section 1 and one bottom 3b of the bottom tape 3 are heat-sealed. The heat-sealed section 6 is the part where the bottom 2a of the main body section 2 and the other bottom 3c of the bottom tape 3 are heat-sealed. As shown in Figure 1, the main body sections 1 and 2 and the bottom tape 3 are heat-sealed so that the bottom of the area that contains the contents is curved and the upper side is arc-shaped. In addition, according to the inventors' studies, conventional standing pouches, when containing liquids, often fall with the bottom facing downwards, and when they fall in this state, the bottom is prone to tearing.

[0033] The distance L from the bottom edge 10a of the standing pouch 10 to the folded portion 3a depends on the type and volume of contents, but is, for example, 35 to 60 mm, and may also be 37 to 50 mm or 40 to 50 mm. A distance L of 35 mm or more tends to further improve the drop resistance of the standing pouch 10. On the other hand, a distance L of 60 mm or less tends to make it easier to ensure a sufficient volume of contents in the standing pouch 10. The width W of the standing pouch 10 also depends on the type and volume of contents, but is, for example, 100 to 140 mm, and may also be 105 to 135 mm or 110 to 130 mm.

[0034] The sides of the standing pouch 10 are composed of heat-sealed sections 7. The width of the heat-sealed section 7 is, for example, 3 to 18 mm, or it may be 7 to 15 mm. A width of 3 mm or more for the heat-sealed section 7 tends to give the standing pouch 10 sufficient self-standing ability, while a width of 18 mm or less tends to make it easier to ensure a sufficient volume of contents in the standing pouch 10.

[0035] As shown in Figure 1, the standing pouch 10 has local joints 9 on both sides of the bottom 10b. The local joints 9 join the main body 1 and the main body 2. That is, the local joints 9 are the points where the sealant layers L2 of the main body 1 and 2 are locally bonded to each other through the notches 8 provided in the bottom tape 3. As shown in Figure 3, the notches 8 of the bottom tape 3 are located in the area between the mountain fold 3a and the bottom edges 3d, 3d, and are provided on the sides of the bottom tape 3. By providing local joints 9 on both sides of the bottom 10b, the self-supporting ability and drop resistance of the standing pouch 10 can be further improved.

[0036] Although embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, an embodiment in which the standing pouch 10 is made of polyethylene monomaterial has been illustrated, but for example, the monomaterialization of polyolefin may be achieved by using polyethylene resin and polypropylene resin in combination. In this case, the polyolefin content of the standing pouch is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more.

[0037] In the above embodiment, a two-layer laminated film 1F, 3F was exemplified, but the laminated films 1F, 3F may further include other layers. For example, from the viewpoint of improving gas barrier properties against water vapor and oxygen, the laminated films 1F, 3F may further include a gas barrier layer. The gas barrier layer may be provided between the substrate layer and the sealant layer, or on the side of the substrate layer opposite to the sealant layer. The water vapor permeability of the laminated film is, for example, 5 g / m². 2 • day, 1 g / m 2 ·day or less or 0.5g / m 2 It may be less than 1 day. The oxygen permeability of the laminated film is, for example, 1 cc / m². 2 It is 0.5g / m³ per day. 2 ·atm·day or less or 0.2g / m 2It may be less than or equal to atm·day. The inclusion of a gas barrier layer in the laminate protects the contents from degradation by water vapor and oxygen, making it easier to maintain quality over the long term.

[0038] An example of a gas barrier layer is a vapor-deposited inorganic oxide layer. By using a vapor-deposited inorganic oxide layer, high barrier properties can be obtained with a very thin layer that does not affect the recyclability of the laminated film. Examples of inorganic oxides include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoint of transparency and barrier properties, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. The thickness of the vapor-deposited inorganic oxide layer can be, for example, 5 to 100 nm, or 10 to 50 nm. A thickness of 5 nm or more tends to exhibit good barrier properties, while a thickness of 100 nm or less tends to maintain the flexibility of the laminated film. The vapor-deposited layer can be formed by, for example, physical vapor deposition or chemical vapor deposition.

[0039] The laminated film may include a metal layer (metal foil) in place of, or in addition to, the inorganic oxide vapor deposition layer. Various metal foils made of aluminum, stainless steel, etc., can be used as the metal layer, and among these, aluminum foil is preferred in terms of moisture resistance, processability such as ductility, and cost. As the aluminum foil, general soft aluminum foil can be used. Among these, aluminum foil containing iron is preferred in terms of excellent pinhole resistance and ductility during molding. When a metal layer is provided, its thickness may be 7 to 50 μm or 9 to 15 μm in terms of barrier properties, pinhole resistance, processability, etc.

[0040] The laminated film may have an anchor coat layer between the substrate layer and the sealant layer. The anchor coat layer can be a very thin layer that does not affect the recyclability of the laminated film, and can be formed using an anchor coat agent. Examples of anchor coat agents include acrylic resin, epoxy resin, acrylic urethane resin, polyester polyurethane resin, polyether polyurethane resin, and polyvinyl alcohol resin. From the viewpoint of heat resistance and interlayer adhesion strength, acrylic urethane resin and polyester polyurethane resin are preferred as anchor coat agents.

[0041] The laminated film may further include, for example, a printed layer. The printed layer may be provided between the substrate layer and the sealant layer, or on the side of the substrate layer opposite to the sealant layer. When a printed layer is provided, it is preferable to use a printing ink that does not contain chlorine to prevent discoloration or odor generation when the printed layer is remelted. Furthermore, it is preferable from an environmental perspective to use biomass materials for the compounds contained in the printing ink. [Examples]

[0042] The present disclosure will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0043] The following materials were prepared to create the standing pouches for the examples and comparative examples. <Main body> • Substrate layer: Unstretched HDPE film (thickness: 35 μm, density: 0.948 g / cm³) 3 (Melting point: 135℃) • Sealant layer: Low-temperature sealing LLDPE film (density: 0.916 g / cm³) 3 (MFR: 4.0g / 10 min, melting point: 102℃) <Bottom tape> • Substrate layer: Unstretched HDPE film (thickness: 35 μm, density: 0.948 g / cm³) 3 (Melting point: 135℃) • Polyethylene resin A for sealant layer…Hexene-based VLLDPE (density: 0.909 g / cm³) 3 (MFR: 1.9g / 10min, Melting point: 97℃) • Polyethylene resin B for sealant layer…Hexene-based LLDPE (Density: 0.913 g / cm³) 3 MFR: 2.4g / 10min, Melting point: 113℃, 126℃) • Polyethylene resin C for sealant layer…Hexene-based VLLDPE (Density: 0.880 g / cm³) 3 (MFR: 2.2g / 10 min, melting point: 100℃) • Polyethylene resin D for sealant layer…Hexene-based LLDPE (Density: 0.913 g / cm³) 3 MFR: 8.0g / 10 min, Melting point: 110℃, 123℃) • Polyethylene resin E for sealant layer…Butene-based LLDPE (density: 0.916 g / cm³) 3 (MFR: 4.0g / 10 min, melting point: 104℃)

[0044] <Example 1> (Preparation of laminated film for bottom tape) Polyethylene resin A and polyethylene resin B were used in an inflation extruder to obtain a two-layer sealant layer in the ratio of layer A (thickness: 20 μm) / layer B (thickness: 80 μm). The laminated film according to Example 1 was obtained by bonding the B layer side of the sealant layer to the base material layer for the bottom tape via an adhesive layer (thickness: 1-2 μm).

[0045] (Making a standing pouch) A laminated film for the main body was obtained by bonding a base material layer and a sealant layer for the main body. Using this laminated film for the main body and the laminated film for the bottom tape, standing pouches were manufactured using a pouch-making machine manufactured by Totani Giken Kogyo Co., Ltd. The pouch sizes were as follows. ·Top and bottom: 230mm ·Width: 145mm • Fold width: 41mm

[0046] <Example 2> The bottom tape and standing pouch were prepared in the same manner as in Example 1, except that the sealant layer for the bottom tape was made into a single layer instead of a two-layer structure. A blend of polyethylene resin A and polyethylene resin B in a 1:4 ratio was used as the resin for the sealant layer of the bottom tape.

[0047] <Example 3> The bottom tape and standing pouch were prepared in the same manner as in Example 1, except that the sealant layer for the bottom tape was made into a single layer instead of a two-layer structure. A blend of polyethylene resin B and polyethylene resin C in a 4:1 ratio was used as the resin for the sealant layer of the bottom tape.

[0048] <Comparative Example 1> (Preparation of laminated film for bottom tape) Using polyethylene resin E, an E layer (thickness: 80 μm) was formed on the surface of the support film. By using polyethylene resin D, a D layer (thickness: 20 μm) was formed on the surface of the E layer to obtain a two-layer sealant layer. A two-layer sealant layer was obtained by extruding polyethylene resin D and polyethylene resin E in a ratio of D layer (thickness: 20 μm) / E layer (thickness: 80 μm) using an inflation extruder. A laminated film according to Comparative Example 1 was obtained by laminating the E layer side of the above sealant layer to the base material layer for the bottom tape via an adhesive layer (thickness: 1-2 μm). A standing pouch was prepared in the same manner as in Example 1, except that this laminated film for the bottom tape was used. The dispersion degree (Mw / Mn) of polyethylene resin D was 5.5, and polyethylene resin D had a sharper molecular weight distribution than polyethylene resin A.

[0049] <Measurement of the elastic modulus of the sealant layer for bottom tape> The elastic modulus of the sealant layers for the bottom tapes of the examples and comparative examples was measured according to the method described in JIS K7161. The measurements were taken using a sample measuring 15 mm in width and 60 mm in length, with a chuck distance of 50 mm and a tensile speed of 200 mm / min. Three measurements were taken for both the MD and TD of each example. The average values ​​are shown in Table 1.

[0050] <Measurement of breaking strength of laminated film for bottom tape> The breaking strength of the laminated films for bottom tapes in the examples and comparative examples was measured according to the method described in JIS K7161. The measurement was performed on a sample measuring 15 mm in width and 60 mm in length, with a chuck distance of 50 mm and a tensile speed of 200 mm / min. The breaking strength per unit cross-sectional area was calculated by dividing the measured breaking strength (N / 15 mm) by the cross-sectional area of ​​the sample (sample thickness × 15 mm). Three measurements were performed for both MD and TD in each example. The average values ​​are shown in Table 1.

[0051] [Table 1]

[0052] (Drop test) 400 ml of cold water (5°C) was sealed into standing pouches for both the examples and comparative examples. The sealed pouches were dropped upright from a height of 1 m up to a maximum of 100 times, and the number of drops required for the pouch to rupture was observed. This test was performed 10 times for each example. The results are shown in Table 2. In the table, samples that were dropped 100 times or more do not rupture. Figures 5-8 show the locations where rupture occurred.

[0053] [Table 2] [Explanation of symbols]

[0054] 1,2...Main body, 1a,2a...Bottom, 1F,3F...Laminated film, 3...Bottom tape, 3a...Mountain fold section, 3b,3c...Bottom, 3d...Bottom edge, 5,6,7...Heat seal section, 8...Notch section, 9...Local joint section, 10...Standing pouch, 10a...Bottom edge, 10b...Bottom, L...Distance, L1,L3...Base material layer, L2,L4...Sealant layer, W...Width.

Claims

1. A first main body is composed of a first laminated film including a first substrate layer and a first sealant layer, A second main body is composed of a second laminated film including a second base layer and a second sealant layer, A bottom tape comprising a third laminated film including a third base layer and a third sealant layer, and having a mountain-fold portion, A self-standing packaging bag formed by heat sealing, The third sealant layer has an MD modulus of 50 to 150 MPa and a TD modulus of 50 to 150 MPa, and a density of 0.85 to 0.94 g / cm³. ３ It contains polyethylene resin, The breaking strength per unit cross-sectional area of ​​the third laminated film is 25 N / mm². ２ That's all. The third base layer is composed of a polyethylene resin film. A self-standing packaging bag in which the first and second base material layers are made of polyethylene resin film.

2. The density of the polyethylene resin contained in the third sealant layer is 0.90 to 0.92 g / cm³. ３ The self-standing packaging bag according to claim 1.

3. The self-standing packaging bag according to claim 1 or 2, wherein the polyethylene resin is hexene-based linear low-density polyethylene.

4. The self-standing packaging bag according to any one of claims 1 to 3, wherein the third sealant layer comprises a polyethylene resin with a melting point of 110°C or lower.

5. The third sealant layer has a density of 0.85 g / cm³. ３ 0.910g / cm or more ３ Layer A is composed of polyethylene resin A with a density of 0.910 g / cm³. ３ 0.94g / cm or more ３ A self-standing packaging bag according to any one of claims 1 to 4, comprising a B layer composed of the following polyethylene resin B.

6. The self-standing packaging bag according to any one of claims 1 to 5, wherein the first and second base material layers are made of HDPE film.

7. A self-standing packaging bag according to any one of claims 1 to 6, wherein the polyethylene content is 90% by mass or more.

8. The self-standing packaging bag according to any one of claims 1 to 6, wherein the first and second base material layers are made of stretched polypropylene film.

9. A self-standing packaging bag according to any one of claims 1 to 8, wherein the polyolefin content is 90% by mass or more.

10. The first, second, and third substrate layers are composed of HDPE film. The resins constituting the first, second, and third sealant layers are polyethylene resins selected from the group consisting of LLDPE and VLLDPE, and the density of the polyethylene resin is 0.90 to 0.92 g / cm³. ３ A self-standing packaging bag according to any one of claims 1 to 9.

11. The first laminated film further includes a first printed layer, the first printed layer being provided between the first substrate layer and the first sealant layer, or on the surface of the first substrate layer opposite to the surface on which the first sealant layer is laminated. The self-standing packaging bag according to claim 1, wherein the second laminated film further includes a second printed layer, the second printed layer being provided between the second substrate layer and the second sealant layer, or on the surface of the second substrate layer opposite to the surface on which the second sealant layer is laminated.

12. The self-standing packaging bag according to claim 11, wherein the first printed layer and the second printed layer are chlorine-free.

13. The first laminated film further includes a first gas barrier layer, the first gas barrier layer being provided between the first substrate layer and the first sealant layer, or on the surface of the first substrate layer opposite to the surface on which the first sealant layer is laminated. The self-standing packaging bag according to claim 1, wherein the second laminated film further includes a second gas barrier layer, the second gas barrier layer being provided between the second substrate layer and the second sealant layer, or on the surface of the second substrate layer opposite to the surface on which the second sealant layer is laminated.

14. The first gas barrier layer is a vapor-deposited layer of an inorganic oxide selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. The self-standing packaging bag according to claim 13, wherein the second gas barrier layer is a vapor-deposited layer of an inorganic oxide selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, and tin oxide.

15. The self-standing packaging bag according to claim 1, wherein part or all of the polyethylene contained in the self-standing packaging bag is mechanically recycled polyethylene.

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