JP2023082843A - Self-standing packaging bag - Google Patents

Abstract

An object of the present invention is to provide a self-supporting packaging bag that is useful for the realization of monomaterials and has sufficient resistance to drop impact. A self-supporting packaging bag of the present disclosure is composed of a first body portion, a second body portion, a third laminated film including a third base layer and a third sealant layer, and It is formed by heat-sealing with a bottom tape having mountain folds. The third sealant layer has an MD elastic modulus of 50 to 150 MPa and a TD elastic modulus of 50 to 150 MPa, and contains a polyethylene resin having a density of 0.90 to 0.92 g/cm3, and a third laminated film The breaking strength per unit cross-sectional area of is 25 N/mm2 or more. [Selection drawing] Fig. 1

Description

The present disclosure relates to self-supporting packaging bags.

The packaging bag is, for example, the property and amount of the contents, the post-treatment for suppressing deterioration of the contents, the form of transporting the package (the contents are contained in the packaging bag), the method of opening the package, In addition, various materials are used in combination depending on the disposal method.

Self-supporting packaging bags such as standing pouches can make products stand out on store shelves, and their range of adoption is expanding. In order to make the whole surface visible without bending the pouch in the middle, the laminated film forming the pouch needs to have a certain degree of rigidity. In addition, if the contents of the pouch are liquid, strength is required so that the bag will not break due to the impact of dropping and the liquid will not leak. In order to meet these functions, laminates in which polyester films, nylon films, polyolefin films, etc. are combined have been used (see Patent Documents 1 and 2).

JP-A-7-237281 JP-A-7-241967

Due to the growing awareness of environmental issues in recent years, there is a demand for resource saving or recycling in the field of packaging bags. For example, from the viewpoint of resource saving, there is a tendency that one refill pouch is filled with refill amounts for multiple times. However, as the capacity of the contents increases, the impact at the time of dropping increases, so the risk of the contents leaking due to the drop increases. As a means of improving drop resistance, it is conceivable to thicken the film (for example, sealant film) constituting the pouch. However, this goes against reducing the amount of plastic used.

A technique is also being studied in which the laminated film that constitutes the packaging material is composed of the same type of material, and the packaging material is reused as an integral material. This is called mono-materialization of the packaging material. As described above, conventional packaging materials have improved required physical properties such as drop resistance by combining various dissimilar materials. However, when the packaging material is made of the same type of material, there is a problem that it is difficult to ensure sufficient drop resistance.

The present disclosure provides a self-supporting packaging bag that is useful for realizing monomaterialization and has sufficient drop resistance.

A self-supporting packaging bag according to one aspect of the present disclosure includes a first main body portion composed of a first laminated film including a first base layer and a first sealant layer, a second base layer and A second main body portion composed of a second laminated film containing a second sealant layer, and a third laminated film containing a third base layer and a third sealant layer, and a mountain fold portion It is formed by heat-sealing with the bottom tape. a third sealant layer having an MD modulus of 50-150 MPa and a TD modulus of 50-150 MPa and comprising a polyethylene resin having a density of 0.85-0.94 g/cm ³ ; The breaking strength per unit cross-sectional area of the film is 25 N/mm ² or more.

The inventor of the present invention aims to make the polyester resin a monomaterial. First, the first, second, and third laminated films have the same structure, and each layer of these laminated films is made of polyethylene film to form a standing pouch. was made. As a result of evaluating drop resistance by sealing 400 cc of water in this standing pouch, the phenomenon of cracks occurring in the mountain fold of the bottom tape occurred frequently (see FIG. 8 showing the results of Comparative Example 1 described later). . In conventional standing pouches made of composite materials, the bottom seal often breaks, and this phenomenon is presumed to be mainly due to the use of polyethylene resin as a monomaterial. In order to increase the breaking strength of the bottom tape, the present 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 mountain folds. As a result of many prototypes and their evaluation, by setting the MD elastic modulus and TD elastic modulus of the third sealant layer to 50 to 150 MPa, the frequency of cracks occurring in the mountain folds is sufficiently low, and sufficient drop It has become possible to stably obtain self-supporting packaging bags having resistance.

In the present disclosure, the MD elastic modulus means the MD (Machine Direction) elastic modulus of the third sealant layer, and the TD (Transverse Direction) elastic modulus of the third sealant layer. Elastic modulus and breaking strength mean values measured according to the method described in JIS K7161. The measurement is performed on a sample having a width of 15 mm and a length of 60 mm, a distance between chucks of 50 mm, and a tensile speed of 200 mm/min. Breaking strength per unit cross-sectional area is obtained by dividing the value of the measured breaking strength (N/15 mm) by the cross-sectional area of the sample (thickness of the sample x 15 mm). The breaking strength of the bottom tape is preferably 25 N/mm ² or more in both MD and TD.

According to the present disclosure, there is provided a self-supporting packaging bag that is useful for realizing monomaterialization and has sufficient drop resistance.

FIG. 1 is a front view schematically showing a self-supporting packaging bag according to one embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically showing the configuration of the self-supporting packaging bag shown in FIG. 1. FIG. 3 is a perspective view schematically showing a pair of main body portions and a bottom tape that constitute the self-supporting packaging bag shown in FIG. 1. FIG. FIG. 4 is a cross-sectional view schematically showing an example of a bottom tape having a sealant layer with a multilayer structure. 5 is a diagram showing the results of Example 1. FIG. 6 is a diagram showing the results of Example 2. FIG. 7 is a diagram showing the results of Example 3. FIG. 8 is a diagram showing the results of Comparative Example 1. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail. Here, a stand-up pouch made of a monomaterial will be described as an example. Standing pouches are used as refill pouches for shampoos, hand soaps, detergents, and the like, and pouches for soups, seasonings, and the like. In addition, this invention is not limited to the following embodiment.

<Standing pouch>
FIG. 1 is a front view schematically showing a standing pouch (self-supporting packaging bag) according to this embodiment. FIG. 2 is a cross-sectional view schematically showing the structure of a standing pouch. The standing pouch 10 shown in these figures is formed by heat-sealing a pair of body parts 1 and 2 (first and second body parts) and a bottom tape 3 . Both of the pair of body portions 1 and 2 are composed of a laminated film 1F including at least a base layer L1 (first and second base layers) and a sealant layer L2 (first and second sealant layers). It is The bottom tape 3 is composed of a laminated film 3F including at least a base layer L3 (third base layer) and a sealant layer L4 (third sealant layer). Formation of standing pouches by heat sealing can be carried out in the same manner as in conventional methods.

From the viewpoint of recyclability, the pair of main body parts 1 and 2 and the bottom tape 3 are both made of a polyethylene-based 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 still more preferably 95% by mass or more.

(bottom tape)
The bottom tape 3 has one mountain fold 3a. That is, when the standing pouch 10 stands on its own, the bottom tape 3 is arranged in an inverted V shape (see FIGS. 2 and 3). As described above, even if the standing pouch 10 receives an impact from being dropped, it is devised so that the mountain-folded portion 3a of the bottom tape 3 is not cracked. The sealant layer L4 and the base material layer L3 that constitute the bottom tape 3 will be described below.

Sealant layer L4 is composed of a material having a relatively low modulus of elasticity. The MD elastic modulus of the sealant layer L4 is 50-150 MPa, preferably 70-150 MPa, more preferably 90-150 MPa. When this value is 50 MPa or more, sufficient rigidity can be imparted to the bottom tape 3. On the other hand, when it is 150 MPa or less, the sealant layer L4 can absorb the impact of a drop, and the bottom tape 3 has sufficient bending resistance. can be given. The TD elastic modulus of the sealant layer L4 is 50-150 MPa, preferably 70-130 MPa, more preferably 90-130 MPa. When this value is 50 MPa or more, sufficient rigidity can be imparted to the bottom tape 3. On the other hand, when it is 150 MPa or less, the sealant layer L4 can absorb the impact of a drop, and the bottom tape 3 has sufficient bending resistance. can be given. Note that the arrow M in FIG. 1 indicates MD, and the arrow T indicates TD.

From the viewpoint that the sealant layer L4 satisfies the above elastic modulus condition, the sealant layer L4 preferably 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), of which more preferred α-olefins include hexene (C6), heptene (C7) and octene (C8). 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.

The melt flow rate (hereinafter referred to as "MFR") of the polyethylene resin contained in the sealant layer L4 is preferably 5 g/10 minutes or less, more preferably 0.5 to 4.5 g/10 minutes, and further It is preferably 1 to 4 g/10 minutes. Polyethylene resins having this value of 5 g/10 minutes or less include resins having relatively high molecular weights, and tend to exhibit high strength against impact after being formed into a film. On the other hand, when this value is 0.5 g/10 minutes or more, the load on the processing machine for film formation by extrusion is low, making it easy to process, and the tensile strength of the resin film tends to increase while maintaining a low elastic modulus. Note that MFR in the present disclosure means a value measured under conditions of a load of 2.16 kg and a temperature of 190° C. according to the method described in JIS K7210.

The melting point of the sealant layer L4 is preferably 110°C or less, more preferably 95 to 110°C. From the viewpoint of low-temperature sealability, the sealant layer L4 preferably contains a polyethylene resin having a melting point of 110° C. or less. Melting points in this disclosure refer to values measured using a differential scanning calorimeter (DSC).

The thickness of the sealant layer L4 is, for example, 40-150 μm, and may be 60-140 μm or 80-120 μm. One or more types of polyethylene resins may be contained in the sealant layer L4. The sealant layer L4 may be a single layer or multiple layers. The sealant layer L4 can achieve both high elasticity and high flex resistance to a high degree by containing a relatively low-density polyethylene resin. The density of polyethylene resin is, for example, 0.85 to 0.94 g/cm ³ , preferably 0.90 to 0.92 g/cm ³ , even 0.85 to 0.915 g/cm ³ good.

The dispersion degree (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. A value of 7.0 or more means that the molecular weight distribution of the polyethylene resin is relatively broad, that is, the polyethylene resin contains low molecular weight components to high molecular weight components. It is speculated that the high molecular weight component contributes to the improvement of breaking strength, while the low molecular weight component imparts low-temperature sealability, lowers resin viscosity to impart flexibility, and improves workability. . It is presumed that such a polyethylene resin has the effect of imparting sufficient flex resistance to the bottom tape 3 and also contributes to the low elasticity of the sealant layer L4. Polyethylene resin dispersity (Mw/Mn) can be measured using gel permeation chromatography (GPC).

When the sealant layer L4 is a single layer, the content of the polyethylene resin in the sealant layer L4 is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, based on the mass of the sealant layer L4. , more preferably 70 to 95% by mass. When this value is 50% by mass or more, the above effect is sufficiently exhibited, and there is a tendency that a high degree of monomaterialization can be realized.

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

The base material layer L3 is preferably composed of an unstretched or stretched polyethylene resin film. Since the base material layer L1 is unstretched, the resin has almost no orientation, and is easily stretched against external stresses such as pulling and shearing, and is difficult to break. On the other hand, since the base material layer L1 is drawn, it is easy to achieve high resistance to puncture and bending while maintaining a certain hardness. The thickness of the base layer L3 is, for example, 5-200 μm, and may be 5-100 μm or 10-50 μm. The base material layer L3 preferably has a melting point higher than that of the sealant layer L4 by 20° C. or more, more preferably 25° C. or more. The melting point of the base material layer L3 can be suppressed in the heat-sealing process due to the difference in melting point between the two.

The melting point of the base material layer L3 is preferably 120° C. or higher, more preferably 125° C. or higher. Examples of polyethylene constituting the base material layer L3 include high density polyethylene (HDPE) and medium density polyethylene (MDPE). Among these, HDPE and MDPE having a density of 0.925 g/cm ³ or more are preferably used from the viewpoint of heat resistance. In particular, it is preferable to use high-density polyethylene having a density in the range of 0.93-0.98 g/cm ³ .

The breaking strength per unit cross-sectional area of the laminated film 3F is 25 N/mm ² or more, preferably 25 to 100 N/mm ² , and may be 25 to 80 N/mm ² or 25 to 50 N/mm ² . When this value is 25 N/mm ² or more ^, the effect of suppressing breakage against tensile stress is exhibited. Even if the laminated film 3F receives an impact due to the rupture, the unbroken portion (for example, the sealant layer L4) is stretched, so that complete breakage can be suppressed. In the present disclosure, breaking strength means a value measured according to the method described in JIS K7161. The measurement is performed on a sample having a width of 15 mm and a length of 30 mm, a distance between chucks of 20 mm, and a tensile speed of 5 mm/min. Breaking strength per unit cross-sectional area is obtained by dividing the value of the measured breaking strength (N/15 mm) by the cross-sectional area of the sample (thickness of the sample x 15 mm).

(main body)
Both of the body portions 1 and 2 are composed of a laminated film 1F including a base layer L1 and a sealant layer L2. The material forming the base layer L1 may be the same as that of the base layer L3. On the other hand, the material forming the sealant layer L2 may be the same as or different from the material forming the sealant layer L4. From the standpoint of the self-standing of the standing pouch 10, it is preferable that the material constituting the sealant layer L2 be able to exhibit stronger stiffness 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. Among these, polyethylene having a density of 0.90 to 0.92 g/cm ³ is preferably used. The melting point of the resin constituting the sealant layer L2 is preferably 110° C. or less, more preferably 95 to 110° C., from the viewpoint of heat sealability.

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

The polyethylene resin contained in the base material layer and the sealant layer in the present disclosure is not limited to petroleum-derived ones, and some or all of them are bio-derived resin materials (e.g., 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 (Green PE manufactured by Braskem, etc.), and may include mechanically recycled polyethylene made from used polyethylene products and resins (so-called burrs) generated in the manufacturing process of polyethylene products. It's okay.

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

A specific configuration of the standing pouch will be described below. The bottom of the standing pouch 10 is composed of a heat-sealed portion 5 and a heat-sealed portion 6, as shown in FIG. The heat-sealed portion 5 is a portion where the bottom portion 1a of the main body portion 1 and one bottom portion 3b of the bottom tape 3 are heat-sealed. The heat-sealed portion 6 is a portion where the bottom portion 2a of the main body portion 2 and the other bottom portion 3c of the bottom tape 3 are heat-sealed. As shown in FIG. 1, the body parts 1 and 2 and the bottom tape 3 are heat-sealed so that the bottom part of the area for storing the contents has a curved surface and the upper part has an arc shape. According to studies by the present inventors, conventional standing pouches often fall with the bottom facing downward when a liquid is contained, and when dropped in such a state, The bottom part is easy to break.

The distance L from the bottom side 10a of the standing pouch 10 to the mountain-folded portion 3a depends on the type and amount of contents, but is, for example, 35-60 mm, and may be 37-50 mm or 40-50 mm. When the distance L is 35 mm or more, the drop resistance of the standing pouch 10 tends to be further improved. On the other hand, when the distance L is 60 mm or less, it tends to be easy to secure a sufficient content of the standing pouch 10 . The width W of the standing pouch 10 also depends on the type and amount of contents, but is, for example, 100-140 mm, and may be 105-135 mm or 110-130 mm.

A side portion of the standing pouch 10 is configured with a heat-sealed portion 7 . The width of the heat-sealed portion 7 is, for example, 3 to 18 mm, and may be 7 to 15 mm. When the width of the heat-sealed portion 7 is 3 mm or more, the standing pouch 10 tends to be sufficiently self-sustaining. be.

As shown in FIG. 1, the standing pouch 10 has respective local joints 9 on both sides of the bottom 10b. A local joint 9 joins the main body 1 and the main body 2 . That is, the local joint portion 9 is a portion where the sealant layers L2 of the main body portions 1 and 2 are locally adhered to each other through the notch portion 8 provided in the bottom tape 3 . As shown in FIG. 3, the notch 8 of the bottom tape 3 is provided on the side of the bottom tape 3 in the area between the mountain fold 3a and the bottom sides 3d, 3d. By providing the local joints 9 on both sides of the bottom portion 10b, the standing pouch 10 can be further improved in self-sustainability and drop resistance.

Although the embodiments of the present disclosure have been described above in detail, the present invention is not limited to the above embodiments. For example, although a mode in which the standing pouch 10 is made of polyethylene as a mono-material is exemplified, it may be made of polyolefin as a mono-material by using polyethylene resin and polypropylene resin together. 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.

Although the laminated films 1F and 3F having a two-layer structure are illustrated in the above embodiments, the laminated films 1F and 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 and 3F may further include a gas barrier layer. The gas barrier layer may be provided between the base material layer and the sealant layer, or may be provided on the surface of the base material layer opposite to the sealant layer. The water vapor permeation amount of the laminated film is, for example, 5 g/m ² ·day, and may be 1 g/m ² ·day or less or 0.5 g/m ² ·day or less. The oxygen permeation amount of the laminated film is, for example, 1 cc/m ² ·atm·day, and may be 0.5 g/m ² ·atm·day or less, or 0.2 g/m ² ·atm·day or less. By including a gas barrier layer in the laminate, the contents are protected from deterioration due to water vapor and oxygen, and the quality can be easily maintained for a long period of time.

An example of the gas barrier layer is a deposited layer of inorganic oxides. By using a deposited layer of an inorganic oxide, it is possible to obtain a high barrier property with a very thin layer within a range 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 layer of inorganic oxide can be, for example, 5 to 100 nm, and can be 10 to 50 nm. When the thickness is 5 nm or more, the barrier properties are likely to be satisfactorily exhibited, and when the thickness is 100 nm or less, the flexibility of the laminated film is easily maintained. The deposited layer can be formed by, for example, physical vapor deposition, chemical vapor deposition, or the like.

The laminated film may include a metal layer (metal foil) in place of or in addition to the deposited layer of inorganic oxide. Various metal foils made of aluminum, stainless steel, or the like can be used as the metal layer, and among these, aluminum foil is preferable from the viewpoints of workability such as moisture resistance and extensibility, cost, and the like. A general soft aluminum foil can be used as the aluminum foil. Among them, an aluminum foil containing iron is preferable from the viewpoint of excellent pinhole resistance and spreadability during molding. When a metal layer is provided, its thickness may be 7 to 50 μm, or 9 to 15 μm, from the viewpoint of barrier properties, pinhole resistance, workability, and the like.

The laminated film may have an anchor coat layer between the substrate layer and the sealant layer. The anchor coat layer may 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 coating agents include acrylic resins, epoxy resins, acrylic urethane resins, polyester polyurethane resins, polyether polyurethane resins, and polyvinyl alcohol resins. As the anchor coating agent, acrylic urethane resins and polyester polyurethane resins are preferable from the viewpoint of heat resistance and interlayer adhesive strength.

The laminated film may, for example, further include a printed layer. The printed layer may be provided between the base material layer and the sealant layer, or may be provided on the surface of the base material layer opposite to the sealant layer. When a printing layer is provided, it is preferable to use printing ink that does not contain chlorine from the viewpoint of preventing the printing layer from being colored or giving off an odor when it is remelted. Moreover, it is preferable to use a biomass material for the compound contained in the printing ink from the viewpoint of environmental friendliness.

EXAMPLES The present disclosure will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

The following materials were prepared in order to produce standing pouches according to Examples and Comparative Examples.
<Body part>
・Base layer: unstretched HDPE film (thickness: 35 μm, density: 0.948 g/cm ³ , melting point: 135° C.)
・Sealant layer: low-temperature sealing LLDPE film (density: 0.916 g/cm ³ , MFR: 4.0 g/10 minutes, melting point: 102°C)
<bottom tape>
・Base layer: unstretched HDPE film (thickness: 35 μm, density: 0.948 g/cm ³ , melting point: 135° C.)
・Polyethylene resin for sealant layer A: Hexene-based VLLDPE (density: 0.909 g/cm ³ , MFR: 1.9 g/10 minutes, melting point: 97°C)
・Polyethylene resin for sealant layer B: Hexene-based LLDPE (density: 0.913 g/cm ³ , MFR: 2.4 g/10 min, melting point: 113°C, 126°C)
・Polyethylene resin for sealant layer C: hexene-based VLLDPE (density: 0.880 g/cm ³ , MFR: 2.2 g/10 minutes, melting point: 100°C)
・Polyethylene resin for sealant layer D: Hexene-based LLDPE (density: 0.913 g/cm ³ , MFR: 8.0 g/10 minutes, melting point: 110°C, 123°C)
・Polyethylene resin for sealant layer E: butene-based LLDPE (density: 0.916 g/cm ³ , MFR: 4.0 g/10 minutes, melting point: 104°C)

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

(Production of standing pouch)
A laminated film for the main body was obtained by bonding the base material layer for the main body and the sealant layer. Using this laminated film for main body portion and the laminated film for bottom tape, a standing pouch was produced by a bag-making machine manufactured by Totani Giken Kogyo Co., Ltd. The pouch size was as follows.
・Top and bottom: 230mm
・Width: 145mm
・Folding width: 41mm

<Example 2>
A bottom tape and a standing pouch were produced in the same manner as in Example 1, except that the sealant layer for the bottom tape had a single-layer structure instead of a two-layer structure. As the resin for the sealant layer for the bottom tape, a blend of polyethylene resin A and polyethylene resin B at a ratio of 1:4 was used.

<Example 3>
A bottom tape and a standing pouch were produced in the same manner as in Example 1, except that the sealant layer for the bottom tape had a single-layer structure instead of a two-layer structure. As the resin for the sealant layer for the bottom tape, a blend of polyethylene resin B and polyethylene resin C at a ratio of 4:1 was used.

<Comparative Example 1>
(Preparation of laminated film for bottom tape)
A polyethylene resin E was used, and an E layer (thickness: 80 μm) was provided on the surface of the support film. A sealant layer having a two-layer structure was obtained by using polyethylene resin D and providing layer D (thickness: 20 μm) on the surface of layer E. Polyethylene resin D and polyethylene resin E were processed by an inflation extruder to obtain a two-layered sealant layer in a ratio of layer D (thickness: 20 μm)/layer E (thickness: 80 μm). A laminated film according to Comparative Example 1 was obtained by bonding the layer E side of the sealant layer and the bottom tape base layer via an adhesive layer (thickness: 1 to 2 μm). A standing pouch was produced in the same manner as in Example 1, except that this laminated film for bottom tape was used. In addition, the degree of dispersion (Mw/Mn) of polyethylene resin D was 5.5, and polyethylene resin D had a sharper molecular weight distribution than polyethylene resin A.

<Measurement of elastic modulus of bottom tape sealant layer>
The elastic moduli of the bottom tape sealant layers of Examples and Comparative Examples were measured according to the method described in JIS K7161. The measurement was performed on a sample having a width of 15 mm and a length of 60 mm under conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm/min. Three measurements were made for each MD and TD of each example. Table 1 shows the average values.

<Measurement of breaking strength of laminated film for bottom tape>
The breaking strength of the laminated films for bottom tapes of Examples and Comparative Examples was measured according to the method described in JIS K7161. The measurement was performed on a sample having a width of 15 mm and a length of 60 mm under conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm/min. Breaking strength per unit cross-sectional area was obtained by dividing the value of the measured breaking strength (N/15 mm) by the cross-sectional area of the sample (thickness of the sample x 15 mm). Three measurements were made for each MD and TD of each example. Table 1 shows the average values.

(Drop test)
400 ml of cold water (5°C) was sealed in each of the standing pouches of Examples and Comparative Examples. The sealed body was repeatedly dropped from a height of 1 m upright up to 100 times, and it was confirmed how many times the bag was broken. This test was performed 10 times for each example. Table 2 shows the results. In the table, samples that were dropped 100 times or more were not broken. Figures 5 to 8 show the locations where fractures occurred.

DESCRIPTION OF SYMBOLS 1, 2... Main-body part 1a, 2a... Bottom part 1F, 3F... Laminated film 3... Bottom tape 3a... Mountain fold part 3b, 3c... Bottom part 3d... Base side 5, 6, 7... Heat sealing part , 8... Notch part, 9... Local joint part, 10... Standing pouch, 10a... Bottom side, 10b... Bottom part, L... Distance, L1, L3... Base material layer, L2, L4... Sealant layer, W... Width.

Claims (9)

a first body portion composed of a first laminated film including a first substrate 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;
A bottom tape composed of a third laminated film including a third base layer and a third sealant layer and having a mountain fold;
A self-supporting packaging bag formed by heat-sealing a
The third sealant layer has an MD modulus of 50-150 MPa and a TD modulus of 50-150 MPa, and contains a polyethylene resin having a density of 0.85-0.94 g/cm ³ ,
The self-supporting packaging bag, wherein the breaking strength per unit cross-sectional area of the third laminated film is 25 N/mm ² or more. The self-supporting packaging bag according to claim 1, wherein said polyethylene resin has a density of 0.90 to 0.92 g/cm ³ . The self-supporting packaging bag according to claim 1 or 2, wherein said polyethylene resin is hexene-based linear low-density polyethylene. The self-supporting packaging bag according to any one of claims 1 to 3, wherein the third sealant layer contains polyethylene resin having a melting point of 110°C or less. The third sealant layer includes a layer A made of a polyethylene resin A having a density of 0.85 g/cm ³ or more and less than 0.910 g/cm ³ and a density of 0.910 g/cm ³ or more and 0.94 g/cm ³ or less. The self-supporting packaging bag according to any one of claims 1 to 4, comprising a B layer composed of polyethylene resin B of The self-supporting packaging bag according to any one of claims 1 to 5, wherein said first and second base layers are composed of HDPE films. The standing pouch according to any one of claims 1 to 6, wherein the content of polyethylene is 90% by mass or more. The self-supporting packaging bag according to any one of claims 1 to 6, wherein said first and second base layers are made of stretched polypropylene film. The self-supporting packaging bag according to any one of claims 1 to 8, wherein the content of polyolefin is 90% by mass or more.

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