JP2024015769A - Laminated film for packaging bags and bottom tapes - Google Patents

Abstract

[Problem] To provide a packaging bag that is made of monomaterial, has a bottom tape that is difficult to fuse, and has excellent resistance to falling bags. A packaging bag according to one aspect of the present disclosure includes a pair of main bodies each including a first base layer and a first sealant layer, and a second base layer and a second sealant layer. and a bottom tape having a mountain fold, the second base material layer comprising a first resin layer, a first resin layer and a second sealant. the first resin layer is a polyethylene film with a density of 0.93 g/cm or more and 0.97 g/cm or less, and the second resin layer is It is a polyethylene film with a density of 0.87 g/cm3 or more and 0.91 g/cm3 or less, the first resin layer is thinner than the second resin layer, and the polyethylene content in the packaging bag is It is 90% by mass or more based on the total amount of the packaging bag. [Selection diagram] Figure 1

Description

The present disclosure relates to a laminated film for packaging bags and bottom tapes.

There are various types of packaging, depending on the nature of the contents to be packaged, the amount of contents, post-treatment to protect the contents from deterioration, the form in which the packaging is transported, the method of opening the packaging, and the method of disposal. Materials are used in combination.

For example, standing pouches can make products stand out on store shelves, and are being widely adopted. In order for a standing pouch to be able to see its entire surface without bending in the middle, the laminate that makes up the pouch must have rigidity. Furthermore, if the contents are liquid, the bag must be strong enough to not break when dropped. In order to meet these functions, laminates combining polyester films, nylon films, polyolefin films, etc. have been used.

However, as awareness of environmental issues has increased in recent years, functions such as resource saving and reuse have become required for various products, and similar functions are also required for laminates used in packaging.

One way to reuse a laminate made of composite materials is to re-separate it into each material, but thermal or chemical methods are required to separate the laminate that has been given a certain strength as a packaging. , it is necessary to perform various mechanical actions. In addition, in order to separate the separated materials, it is necessary to use physical effects based on specific gravity and spectroscopic techniques that differ depending on the material. It was not efficient as it required more energy.

Another approach is to construct the original laminate with materials of the same type and reuse the laminate as a single piece of material. In particular, thermoplastic resins include various types of materials such as polyolefin, polyester, and polyamide. Each material can have various properties depending on its molecular weight, molecular weight distribution, heat treatment, orientation, stretching, and other conditions and treatments. In particular, polyolefin materials are easy to use because they have a low melting point and are easy to process, and various materials are manufactured from copolymers and the like. Therefore, various methods have been proposed so far.

For example, Patent Document 1 discloses a laminate consisting of a uniaxially stretched polyolefin resin film and a polyolefin heat seal layer. Further, Patent Document 2 discloses a polyethylene laminate for packaging materials, which comprises at least a stretched polyethylene film and a heat-sealable polyethylene layer, and an image is formed on at least one surface of the stretched polyethylene film. The body is revealed.

Patent No. 5197952 JP2019-166810A

The main focus of the invention disclosed in Patent Document 1 is a laminate made of a uniaxially stretched film that is easily tearable, but the result is a laminate made of the same type of resin. However, there are no regulations regarding the strength of the packaging, and it is possible to laminate films such as biaxially oriented nylon or polyester as needed, so this does not address environmental issues. do not have.

The present inventors selected polyethylene resin as a material for realizing monomaterial packaging material. Under the restriction that various resin materials cannot be used in combination, a laminate including a base material layer and a sealant layer was produced, and this was used to repeatedly produce a prototype of a standing pouch having a pair of main body parts and a bottom tape. As a result, they discovered that when standing pouches were made from polyethylene resin, the bottom tape was fused, making it difficult to make bags.

Furthermore, studies by the present inventors have revealed that when the invention disclosed in Patent Document 2 is used as a bottom tape of a standing pouch, the folded portion of the bottom tape is torn. In other words, the present inventors discovered that a standing pouch using polyethylene resin as a material has room for improvement in terms of resistance to falling bags.

The present disclosure provides a packaging bag that is made of monomaterial, has a bottom tape that is difficult to fuse, and has excellent resistance to falling bags. Further, the present disclosure provides a laminated film for a bottom tape that is a monomaterial, is difficult to fuse, and the resulting packaging bag has excellent resistance to falling bags.

One aspect of the present disclosure is a bottom tape including a pair of main body parts each including a first base layer and a first sealant layer, and a bottom tape including a second base layer and a second sealant layer and having a mountain fold part. A packaging bag formed by heat-sealing and, wherein a second base material layer is provided between the first resin layer and the first resin layer and the second sealant layer. The first resin layer is a polyethylene film having a density of 0.93 g/cm ^{3 or more and 0.97 g/cm 3 or} less, and the second resin layer has a density of 0.87 g/cm 3 or less. ³ or more and 0.91 g/cm ³ or less, the first resin layer is thinner than the second resin layer, and the polyethylene content in the packaging bag is less than or equal to the total amount of the packaging bag. It relates to a packaging bag having a content of 90% by mass or more based on .

In the packaging bag according to one aspect of the present disclosure, the bottom tape is less likely to be fused and has excellent resistance to falling bags. The inventors of the present invention conjecture the reason why such an effect is produced as follows. That is, the second base material layer of the bottom tape of the packaging bag includes a combination of a first resin layer and a second resin layer having a specific density. Since the second base material layer includes the first resin layer having the above-mentioned specific density on the outer layer side, the bottom tape is less likely to be fused during bag making. Furthermore, since the second base material layer includes the second resin layer having the above-described specific density on the inner layer side, the hard and brittle properties of the first resin layer can be suppressed by the second resin layer. It can be supplemented. As a result, the bottom tape of the packaging bag is less likely to be fused during bag manufacturing and has excellent resistance to falling bags. Moreover, the packaging bag according to one aspect of the present disclosure tends to have sufficient self-reliance.

In one embodiment, the bottom tape may further include a barrier layer between the base layer and the sealant layer. In one embodiment, the barrier layer may have a structure in which a barrier base material layer containing polyethylene, a subbing layer, an inorganic oxide layer, and a gas barrier adhesive layer are laminated in this order. .

In one embodiment, the oxygen permeability of the gas barrier adhesive layer may be 100 cc/m ² ·day · atm or less. In one embodiment, the gas barrier adhesive layer may be a layer formed using an epoxy adhesive. In one embodiment, the inorganic oxide layer may include silicon oxide.

Another aspect of the present disclosure is a laminated film for a bottom tape including a base layer and a sealant layer, wherein the base layer is between a first resin layer and the first resin layer and the sealant layer. The first resin layer is a polyethylene film having a density of 0.93 g/cm 3 or more and 0.97 g/cm ³ or less, and the second resin layer has a density of 0.93 g/cm ³ or more and 0.97 g/cm 3 or less. It is a polyethylene film of 87 g/cm ³ or more and 0.91 g/cm ³ or less, the first resin layer is thinner than the second resin layer, and the content of polyethylene in the laminated film is lower than that of the laminated film. The present invention relates to a laminated film for a bottom tape that is 90% by mass or more based on the total amount of the film.

According to the present disclosure, there is provided a packaging bag that is made of monomaterial, has a bottom tape that is difficult to fuse, and has excellent resistance to falling bags. Further, according to the present disclosure, there is provided a laminated film for a bottom tape that is a monomaterial, is difficult to fuse, and the resulting packaging bag has excellent resistance to falling bags.

FIG. 1 is a front view schematically showing a self-supporting packaging bag according to an embodiment of the present disclosure. FIG. 2 is a sectional view schematically showing the structure of the self-supporting packaging bag shown in FIG. FIG. 3 is a perspective view schematically showing a pair of main body parts and a bottom tape constituting the self-supporting packaging bag shown in FIG. 1. FIG. 4 is a cross-sectional view schematically showing an example of the bottom tape. FIG. 5 is a sectional view schematically showing another example of the bottom tape.

<Standing pouch>
Hereinafter, the packaging bag according to this embodiment will be explained in detail. Here, we will explain a standing pouch that has been made into a monomaterial as an example.

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 the standing pouch. A standing pouch 10 shown in these figures is formed by heat-sealing a pair of main body parts 1 and 2 and a bottom tape 3. Both of the pair of main bodies 1 and 2 are composed of a laminated film 1F that includes at least a base material layer L1 (first base material layer) and a sealant layer L2 (first sealant layer). The bottom tape 3 is composed of a laminated film 3F that includes at least a base layer L3 (second base layer) and a sealant layer L4 (second sealant layer). Formation of standing pouches by heat sealing can be performed similarly to conventional methods.

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

(bottom tape)
The bottom tape 3 has one mountain fold portion 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 shown in FIG. 4, the laminated film 3F constituting the bottom tape 3 includes a sealant layer L4 and a base layer L3. Hereinafter, the sealant layer L4 and the base material layer L3 will be explained.

[Base material layer L3]
The base material layer L3 includes a first resin layer L3a, a second resin layer L3b, and a third resin layer L3c in this order. The first resin layer L3a is arranged on the outer layer side of the base material layer L3. Thereby, the base material layer L3 has improved heat resistance, and the bottom tape 3 is less likely to be fused during bag making. The second resin layer L3b is provided between the first resin layer L3a and the second sealant layer L4. The standing pouch 10 has improved bag drop resistance because the base layer L3 includes the second resin layer L3b. Moreover, although the second resin layer L3b has a low density and is soft, the base material layer L3 includes the third resin layer L3c, making it easier to form the bottom tape 3.

The first resin layer L3a is a polyethylene film having a density of 0.93 g/cm ³ or more and 0.97 g/cm ³ or less. The density of such polyethylene films may be 0.97 g/cm ³ or less, 0.96 g/cm ³ or less or 0.95 g/cm ³ or less.

The second resin layer L3b is a polyethylene film having a density of 0.87 g/cm ³ or more and 0.91 g/cm ³ or less. The density of such a polyethylene film may be 0.87 g/cm ³ or more, 0.88 g/cm ³ or more, or 0.89 g/cm ³ or more. The density of such polyethylene films may be 0.91 g/cm ³ or less, 0.905 g/cm ³ or less or 0.90 g/cm ³ or less.

The third resin layer L3c may be a polyethylene film with a density of less than 0.93 g/cm ³ . The density of such polyethylene films may be greater than 0.905 g/cm ³ , greater than or equal to 0.91 g/cm ³ or greater than or equal to 0.92 g/cm ³ . The density of such polyethylene films may be 0.925 g/cm ³ or less, 0.92 g/cm ³ or less or 0.915 g/cm ³ or less.

The base material layer L3 is not limited to one derived from petroleum, and may partially or entirely contain a biologically derived resin material (for example, biomass polyethylene used as a biomass-derived ethylene raw material). A method for producing polyethylene derived from biomass is disclosed, for example, in Japanese Patent Publication No. 2010-511634. Alternatively, commercially available biomass polyethylene (Green PE manufactured by Braskem, etc.) may be used. Further, the base layer L3 may partially contain a biodegradable resin material (for example, polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, etc.). The base layer L3 may contain additives such as an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, and a colorant. Further, the base layer L3 may include mechanically recycled polyethylene made from used polyethylene products or resin (so-called burrs) generated in the manufacturing process of polyethylene products.

The thickness of the base material layer L3 may be, for example, 10 to 80 μm.

The first resin layer L3a is thinner than the second resin layer L3b. The thickness of the first resin layer L3a with respect to the thickness of the second resin layer L3b is less than 100%, and may be 80% or less, 50% or less, or 25% or less, 20% or more, 50% or more Or it may be 80% or more.

The thickness of the first resin layer L3a with respect to the base material layer L3 may be 30% or less, 25% or less, or 15% or less, and may be 10% or more, 15% or more, or 25% or more.

The thickness of the second resin layer L3b with respect to the base material layer L3 may be 70% or less, 50% or less, or 40% or less, and may be 30% or more, 50% or more, or 60% or more.

The base material layer L3 may be formed, for example, by co-extruding the first resin layer L3a, the second resin layer L3b, and the third resin layer L3c.

[Sealant layer L4]
The sealant layer L4 contains polyethylene having a higher melting point than the base layer L3. Examples of such polyethylene include linear low density polyethylene (LLDPE) and very low density polyethylene (VLDPE). Among these, it is preferable to use polyethylene having a density of 0.900 to 0.920 g/cm ³ .

The sealant layer L4 may include biomass polyethylene using biomass-derived ethylene as a raw material. Further, the sealant layer L4 may include mechanically recycled polyethylene made from used polyethylene products or resin (so-called burrs) generated in the manufacturing process of polyethylene products.

The sealant layer L4 may contain resin other than polyethylene. Examples of such resins include polypropylene, ethylene-vinyl acetate copolymer, propylene-ethylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, and ethylene-propylene-butadiene copolymer. Examples include polymers and ethylene-propylene-1-butene copolymers.

The melting point of the resin constituting the sealant layer L4 is preferably in the range of 40 to 160° C. from the viewpoint of heat sealability.

Sealant layer L4 may contain additives. Examples of additives include heat stabilizers, antioxidants, ultraviolet absorbers, antiblocking agents, lubricants, antistatic agents, and the like.

The thickness of the sealant layer L4 may be, for example, 30 to 150 μm. By adjusting the thickness of the sealant layer L4, the bendability and rigidity of the bottom tape 3 can be adjusted.

The sealant layer L4 can be formed by a dry lamination method in which the film-like sealant layer L4 made of the above-mentioned materials is bonded together with an adhesive such as a one-component or two-component urethane adhesive, or a film-like sealant. All known lamination methods include a non-solvent dry lamination method in which the layer L4 is laminated using a solvent-free adhesive, and an extrusion lamination method in which a resin material equivalent to the sealant layer L4 is heated and melted, extruded into a curtain shape, and laminated together. It can be formed by

(Main body)
Both the main bodies 1 and 2 are composed of a laminated film 1F including a base material layer L1 and a sealant layer L2. As the material constituting the base layer L1, for example, high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene can be used. Among these, it is preferable to use high-density polyethylene and medium-density polyethylene from the viewpoint of self-supporting properties. The base layer L1 may be an unstretched or stretched film. When the base material layer L1 is a stretched film, it may be a uniaxially stretched film or a biaxially stretched film. The thickness of the base material layer L1 may be 20 to 100 μm.

As the polyethylene resin constituting the sealant layer L2, for example, high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and very low-density polyethylene can be used. Among these, from the viewpoint of heat sealability, it is preferable to use linear low density polyethylene. The sealant layer L2 may be an unstretched or stretched film. When the sealant layer L2 is a stretched film, it may be a uniaxially stretched film or a biaxially stretched film. The thickness of the sealant layer L2 may be the same as that of the sealant layer L4.

The specific structure of the standing pouch will be described below. As shown in FIG. 2, the bottom of the standing pouch 10 is composed of a heat-sealed portion 5 and a heat-sealed portion 6. 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 obtained by heat-sealing the bottom portion 2a of the main body portion 2 and the other bottom portion 3c of the bottom tape 3. As shown in FIG. 1, the main bodies 1 and 2 and the bottom tape 3 are heat-sealed so that the bottom of the area for accommodating the contents forms a curved surface and the upper side forms an arc. According to studies conducted by the present inventors, conventional standing pouches often fall with the bottom facing downward when a liquid substance is contained in them, and when the pouch falls in such a state, The bottom of the bag is easy to tear.

The distance L from the bottom side 10a of the standing pouch 10 to the mountain fold 3a depends on the type and amount of contents, but is, for example, 35 to 60 mm, and may be 37 to 50 mm or 40 to 50 mm. When the distance L is 35 mm or more, the falling 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 ensure a sufficient internal capacity 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 to 300 mm, and may be 105 to 295 mm or 110 to 290 mm.

The side portion of the standing pouch 10 is composed of a heat seal portion 7. The width of the heat seal 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, it tends to provide sufficient independence to the standing pouch 10, and on the other hand, when it is 18 mm or less, it tends to be easy to ensure a sufficient internal capacity of the standing pouch 10. be.

As shown in FIG. 1, the standing pouch 10 has 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 bonded to each other through the notch portion 8 provided in the bottom tape 3. As shown in FIG. 3, the cutout portion 8 of the bottom tape 3 is located in a region between the mountain fold portion 3a and the bottom sides 3d, 3d, and is provided on the side of the bottom tape 3. By providing the local joint portions 9 on both sides of the bottom portion 10b, the self-sustainability and resistance to falling bags of the standing pouch 10 can be further improved.

The standing pouch 10 can contain contents such as foods and medicines. The packaging bag can be subjected to heat sterilization treatment such as boiling treatment.

Boiling is a method of sterilizing foods, medicines, etc. with moist heat to preserve them. Usually, a packaging bag containing food or the like is subjected to moist heat sterilization at 60 to 100°C and under atmospheric pressure for 10 to 120 minutes, depending on the contents. The boiling process is usually performed at 100°C or lower using a hot water bath. There are two methods: a batch method, in which the material is immersed in a hot water tank at a constant temperature and treated for a certain period of time, and then taken out, and a continuous method, in which the material is passed through the hot water tank in a tunnel. The packaging bag of this embodiment can also be suitably used for purposes in which it is subjected to boiling treatment.

Furthermore, the standing pouch 10 can contain viscous substances such as hand soap, body soap, shampoo, conditioner, detergent, and fabric softener.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments. For example, in the above embodiment, the two-layered laminated films 1F and 3F are illustrated, but the laminated film may further include layers other than the base layer and the sealant layer. FIG. 5 shows another example of a laminated film. The laminated film 4F shown in FIG. 5 includes an adhesive layer L5, a heat-resistant resin layer L6, and a barrier layer L7 in addition to the base material layer L3 and the sealant layer L4. The barrier layer L7 includes a barrier base material layer L7a, an undercoat layer L7b, an inorganic oxide layer L7c, and a gas barrier adhesive layer L7d. Each layer will be explained in detail below.

[Adhesive layer L5]
Examples of the material constituting the adhesive layer L5 include an adhesive (urethane adhesive) containing a reaction product of a composition containing a polyol and a polyisocyanate. The urethane adhesive contains a reaction product of a composition containing a polyol and a polyisocyanate, that is, a urethane resin. The composition containing a polyol and a polyisocyanate may contain an epoxy resin, a hydroxy acid, etc., if necessary. The polyol may be a polyester polyol, preferably an aliphatic polyester polyol. The polyisocyanate is not particularly limited as long as it is a compound having two or more isocyanate groups in the molecule, and may be either an aliphatic polyisocyanate or an aromatic polyisocyanate. Examples of the urethane adhesive include a reaction product of Takelac A626 (aliphatic polyester polyol, manufactured by Mitsui Chemicals, Inc.) and Takenate A65 (polyisocyanate, manufactured by Mitsui Chemicals, Inc.), and if necessary, An epoxy resin may be used in combination.

The thickness of the adhesive layer L5 may be, for example, 1.0 to 10.0 μm.

[Heat-resistant resin layer L6]
The heat-resistant resin layer L6 is a layer that provides heat resistance to the laminated film 4F. Examples of the material constituting the heat-resistant resin layer L6 include urethane resin and acrylic resin. The thickness of the heat-resistant resin layer L6 may be, for example, 0.1 to 1.0 μm.

[Barrier base material layer L7a]
Barrier base material layer L7a contains polyethylene. As such polyethylene, for example, high density polyethylene, medium density polyethylene, linear low density polyethylene and very low density polyethylene can be used. Among these, it is preferable to use high-density polyethylene from the viewpoint of processability.

The thickness of the barrier base material layer L7a may be, for example, 10 to 50 μm.

[Sublayer L7b]
An undercoat layer (anchor coat layer) L7b is provided on the surface of the barrier base material layer L7a on which the inorganic oxide layer L7c is laminated. The undercoat layer L7b is an inorganic oxide layer that improves the adhesion between the barrier base layer L7a and the inorganic oxide layer L7c, improves the smoothness of the surface of the barrier base layer L7a, and causes the barrier base layer L7a to elongate. It is possible to achieve the effect of suppressing the occurrence of cracks in L7c. In addition, by improving the smoothness, it becomes easier to form the inorganic oxide layer L7c uniformly without defects, and it becomes easier to exhibit high barrier properties. The undercoat layer L7b can be formed using a composition for forming an undercoat layer (anchor coating agent).

Examples of the resin used in the anchor coating agent include acrylic resin, epoxy resin, acrylic urethane resin, polyester polyurethane resin, and polyether polyurethane resin. As the resin used for the anchor coating agent, acrylic urethane resins and polyester polyurethane resins are preferable from the viewpoints of heat resistance and interlayer adhesive strength. The undercoat layer L7b can be formed using these resins or an anchor coating agent containing a component that reacts to form these resins.

The thickness of the undercoat layer L7b is not particularly limited, but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.03 to 3 μm, and preferably in the range of 0.05 to 2 μm. is particularly preferred. When the thickness of the undercoat layer L7b is equal to or greater than the above lower limit, more sufficient interlayer adhesive strength tends to be obtained, while when it is equal to or less than the above upper limit, desired gas barrier properties tend to be easily exhibited.

[Inorganic oxide layer L7c]
Examples of constituent materials of the inorganic oxide layer L7c include inorganic oxides such as 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. Moreover, from the viewpoint of excellent tensile stretchability during processing, it is preferable that the inorganic oxide layer L7c is a layer using silicon oxide. By using the inorganic oxide layer L7c, high barrier properties can be obtained with a very thin layer that does not affect the recyclability of the laminated film.

The thickness of the inorganic oxide layer L7c is preferably 10 nm or more and 50 nm or less. When the film thickness is 10 nm or more, sufficient gas barrier properties can be obtained.

[Gas barrier adhesive layer L7d]
Examples of materials constituting the gas barrier adhesive layer include epoxy adhesives. Since epoxy resin is easy to form a dense film due to its molecular structure, the gas barrier adhesive layer L7d formed using an epoxy adhesive tends to exhibit higher gas barrier properties.

The oxygen permeability of the gas barrier adhesive layer L7d may be 100 cc/m ² ·day · atm or less. Thereby, the gas barrier properties of the laminated film 4F can be further improved, and the deterioration of the gas barrier properties after bending can be further suppressed. In addition, when slight cracks occur in the inorganic oxide layer L7c due to bending, etc., and the gas barrier adhesive layer enters the gap to compensate, the oxygen permeability of the gas barrier adhesive layer L7d must be within the above range. Therefore, deterioration in gas barrier properties can be further suppressed.

The thickness of the gas barrier adhesive layer L7d may be, for example, 1.0 to 10.0 μm.

The laminated film may include layers other than the layers described above. Examples of other layers include a printed layer. When a printing layer is provided, it is preferable to use a printing ink that does not contain chlorine, from the viewpoint of preventing the printing layer from being colored or producing an odor during remelting. Furthermore, it is preferable from the viewpoint of environmental consideration to use biomass materials as the compounds contained in the printing ink.

Further, in the embodiment described above, the base material layer L3 includes the third resin layer L3c, but the base material layer does not need to include the third resin layer L3c. Moreover, the base material layer may be four or more layers. Further, in the above embodiment, the case where the base material layer L1 is a single layer is illustrated, but the base material layer of the main body portion may be two or more layers. In this case, the base material layer of the main body may have a two-layer structure, a three-layer structure, or a four-layer structure or more. When the base material layer of the main body part has a two-layer configuration, the material and thickness of the base material layer of the main body part are the same as those of the first resin layer L3a and the second resin layer L3b of the base material layer L3. good. When the base material layer of the main body part has a three-layer structure, the material and thickness of the base material layer of the main body part are the first resin layer L3a, the second resin layer L3b, and the third resin layer of the base material layer L3. It may be similar to layer L3c.

Further, the standing pouch may have creases (embossed) extending in the vertical direction on its sides in order to improve its self-supporting nature. Additionally, the standing pouch may be provided with an air enclosing portion extending in the vertical direction on its side in order to improve its self-supporting nature.

<Laminated film for bottom tape>
Hereinafter, the laminated film for bottom tape according to this embodiment will be explained. The laminated film for bottom tape according to the present embodiment is a laminated film for bottom tape that includes a base material layer and a sealant layer, and the base material layer includes a first resin layer, a first resin layer, and a sealant layer. The first resin layer is a polyethylene film having a density of 0.93 g/cm ³ or more and 0.97 g/cm ³ or less, and the second resin layer is It is a polyethylene film with a density of 0.87 g/cm ³ or more and 0.91 g/cm ³ or less, the first resin layer is thinner than the second resin layer, and the polyethylene content in the laminated film is , based on the total amount of the laminated film, is 90% by mass or more.

The material and thickness of the base layer of the laminated film for bottom tape according to this embodiment may be the same as those of the bottom tape 3 forming the standing pouch 10 according to the above embodiment.

The polyethylene content of the laminated film for bottom tape according to the present embodiment is 90% by mass or more, preferably 92% by mass or more, and more preferably 95% by mass or more.

EXAMPLES Hereinafter, the present disclosure will be explained in more detail with reference to examples, but the present disclosure is not limited to these examples.

<Preparation of laminated film>
(Laminated film A)
An unstretched HDPE film (base layer, thickness: 35 μm, density: 0.95 g/cm ³ ) and an LLDPE film (sealant layer, thickness: 100 μm, density: 0.913 g/cm ³ ) were bonded together with an adhesive ( A laminate film A (laminated structure: base material layer/adhesive layer/sealant layer) was obtained by bonding through an adhesive layer (manufactured by Mitsui Chemicals, trade name: A626/A50).

(Laminated film B)
Acrylic polyol and tolylene diisocyanate are mixed so that the number of NCO groups in tolylene diisocyanate is equal to the number of OH groups in acrylic polyol, and the total solid content (total amount of acrylic polyol and tolylene diisocyanate) is ) was diluted with ethyl acetate to 5% by mass. Further, β-(3,4-epoxycyclohexyl)trimethoxysilane was added to the diluted mixed solution in an amount of 5 parts by mass based on 100 parts by mass of the total amount of the acrylic polyol and tolylene diisocyanate. By mixing, a composition for forming an undercoat layer (anchor coating agent) was prepared. The composition for forming an undercoat layer was applied to unstretched HDPE (barrier base layer, thickness: 32 μm) using a wire bar to form a coating film. The coating film was dried and cured at 60° C. to form an undercoat layer (coating amount of acrylic urethane resin: 0.1 g/m ² ). A transparent inorganic oxide layer (silica vapor deposited film, thickness: 30 nm) made of silicon oxide was formed on the undercoat layer using a vacuum evaporation device using an electron beam heating method. Mix 16 parts by mass of Maxive C93T manufactured by Mitsubishi Gas Chemical Co., Ltd. and 5 parts by mass of Maxive M-100 manufactured by Mitsubishi Gas Chemical Company in 23 parts by mass of a solvent that is a mixture of ethyl acetate and methanol at a mass ratio of 1:1. Adhesive A, which is an epoxy adhesive, was prepared. Adhesive A was applied onto the inorganic oxide layer using a wire bar to form a coating film. The coating film was dried at 60° C. to form a gas barrier adhesive layer (thickness: 3 μm). A laminate was obtained by bonding an unstretched LLDPE film (thickness: 100 μm) as a sealant layer to the gas barrier adhesive layer. The obtained laminate was aged at 40° C. for 4 days. Thereby, a gas barrier laminate (laminated structure: barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

An unstretched HDPE film (base layer, thickness: 35 μm, density: 0.95 g/cm ³ ) and a gas barrier laminate are bonded via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50). A laminated film B (laminated structure: base material layer/adhesive layer/barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

(Laminated film C)
MDPE (first resin layer, thickness: 15 μm, density: 0.930 g/cm ³ ), VLDPE (second resin layer, thickness: 30 μm, density: 0.905 g/cm ³ ), and LLDPE ( A first multilayer polyethylene film (thickness: 60 μm) including a third resin layer (thickness: 15 μm, density: 0.920 g/cm ³ ) in this order was prepared as a base material layer. The first multilayer polyethylene film and the LLDPE film (sealant layer, thickness: 100 μm, density: 0.913 g/cm ³ ) are bonded via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, trade name: A626/A50). A laminated film C (laminated structure: first resin layer/second resin layer/third resin layer/adhesive layer/sealant layer) was obtained.

(Laminated film D)
A gas barrier laminate was obtained in the same manner as laminate film B. A first multilayer polyethylene film (thickness: 60 μm) was prepared as a base layer in the same manner as Laminated Film C. The gas barrier laminate and the first multilayer polyethylene film are bonded together via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50) to form a laminate film D (laminated structure: first resin layer/ A second resin layer/third resin layer/adhesive layer/barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

(Laminated film E)
Nylon film (thickness: 15 μm) and aluminum vapor-deposited PET film (VM-PET, thickness: 12 μm) are bonded together via adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50). A first laminate was obtained. The first laminate and the LLDPE film (thickness: 100 μm) are bonded together via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50) to form a laminate film E (laminate structure: base material). layer/adhesive layer/barrier substrate layer/inorganic oxide layer/adhesive layer/sealant layer) were prepared.

(Laminated film F)
An MDPE film (base layer, thickness: 60 μm, density: 0.93 g/cm ³ ) and an LLDPE film (sealant layer, thickness: 100 μm, density: 0.913 g/cm ³ ) were bonded together using an adhesive (adhesive). A laminate film F (laminated structure: base material layer/adhesive layer/sealant layer) was obtained by bonding them together via a layer (manufactured by Mitsui Chemicals, Inc., trade name: A626/A50).

(Laminated film G)
An LLDPE film (base layer, thickness: 60 μm, density: 0.92 g/cm ³ ) and an LLDPE film (sealant layer, thickness: 100 μm; density: 0.913 g/cm ³ ) were bonded together using an adhesive (adhesive layer). , manufactured by Mitsui Chemicals, Inc., trade name: A626/A50) to obtain a laminate film G (laminated structure: base material layer/adhesive layer/sealant layer).

(Laminated film H)
A gas barrier laminate was obtained in the same manner as laminate film B. The MDPE film (base layer, thickness: 60 μm, density: 0.93 g/cm ³ ) and the gas barrier laminate are bonded via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50). By laminating them together, a laminated film H (laminated structure: base material layer/adhesive layer/barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

(Laminated film I)
A gas barrier laminate was obtained in the same manner as laminate film B. The LLDPE film (base layer, thickness: 60 μm, density: 0.92 g/cm ³ ) and the gas barrier laminate are bonded via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50). By laminating them together, a laminated film I (laminated structure: base material layer/adhesive layer/barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

(Laminated film J)
MDPE (first resin layer, thickness: 35 μm, density: 0.930 g/cm ³ ), VLDPED (second resin layer, thickness: 15 μm, density: 0.905 g/cm ³ ), and LLDPE ( A second multilayer polyethylene film (thickness: 60 μm) including a third resin layer (thickness: 10 μm, density: 0.920 g/cm ³ ) in this order was prepared as a base material layer. A second multilayer polyethylene film and an LLDPE film (sealant layer, thickness: 100 μm, density: 0.913 g/cm ³ ) are bonded together using an adhesive (adhesive layer, manufactured by Mitsui Chemicals, trade name: A626/A50). A laminated film J (laminated structure: first resin layer/second resin layer/third resin layer/adhesive layer/sealant layer) was obtained.

(Laminated film K)
A gas barrier laminate was obtained in the same manner as laminate film B. A second multilayer polyethylene film (thickness: 60 μm) was prepared as a base layer in the same manner as Laminated Film J. The second multilayer polyethylene film and the gas barrier laminate are bonded together via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, trade name: A626/A50) to form a laminate film K (laminated structure: first resin layer). /second resin layer/third resin layer/adhesive layer/barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

(Laminated film L)
Medium-density polyethylene (density: 0.941 g/cm3, melting point 129°C, MFR: 1.3 g/10 min, manufactured by Dow Chemical Company, product name: Elite 5538G) was formed by inflation molding to form a polyethylene film with a thickness of 100 μm. Obtained. This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to prepare a stretched polyethylene film (base material layer) having a thickness of 20 μm. A stretched polyethylene film and an LLDPE film (sealant layer, thickness: 100 μm, density: 0.913 g/cm ³ ) were attached via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50). In total, a laminated film L (laminated structure: base material layer/adhesive layer/sealant layer) was obtained.

(Laminated film M)
A gas barrier laminate was obtained in the same manner as laminate film B. A stretched polyethylene film (base layer) having a thickness of 20 μm was prepared in the same manner as the laminated film L. A stretched polyethylene film and a gas barrier laminate are pasted together via an adhesive (adhesive layer, manufactured by Mitsui Chemicals, product name: A626/A50) to form a laminate film L (laminate structure: base material layer/adhesive layer/ A barrier base material layer/subbing layer/inorganic oxide layer/gas barrier adhesive layer/sealant layer) was obtained.

<Preparation of packaging bag>
(Examples 1 to 4 and Comparative Examples 1 to 9)
A packaging bag (standing pouch) with a height of 240 mm, a width of 150 mm, and a bottom material of 40 mm (folded one way) was produced using a laminated film. Laminated films shown in Table 1 were used for the main body and bottom tape, respectively.

<Recyclability evaluation>
(Examples 1 to 4 and Comparative Examples 1 to 9)
The recyclability of the packaging bags of each Example and Comparative Example was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
A: The polyethylene content in the packaging bag was 90% by mass or more.
B: The polyethylene content in the packaging bag was less than 90% by mass.

<Drop test evaluation>
(Examples 1 to 4 and Comparative Examples 1 to 9)
A standing pouch was filled with 600 ml of water and stored at 5°C for 24 hours. After storage, each of the 10 standing pouches was dropped 10 times from a height of 1 m, and the number of broken pouches was counted. The number of broken standing pouches was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
A: The number of broken standing pouches was less than one.
B: The number of broken standing pouches was 1 or more and less than 5.
C: The number of broken standing pouches was 5 or more.

<Bag making suitability evaluation>
(Examples 1 to 4 and Comparative Examples 1 to 9)
When the bottom tape of a standing pouch was folded in and heat-sealed from above at a temperature of 140° C. on a hot plate, the presence or absence of fusion between the bottom tapes was checked and evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
A: No fusion B: With fusion

The gist of the present disclosure resides in [1] to [7] below.
[1] Heat a pair of main body parts each including a first base material layer and a first sealant layer, and a bottom tape including a second base material layer and a second sealant layer and having a mountain fold part. A packaging bag formed by sealing,
The second base layer includes a first resin layer and a second resin layer provided between the first resin layer and the second sealant layer,
The first resin layer is a polyethylene film with a density of 0.93 g/cm ³ or more and 0.97 g/cm ³ or less,
The second resin layer is a polyethylene film with a density of 0.87 g/cm ³ or more and 0.91 g/cm ³ or less,
The first resin layer is thinner than the second resin layer,
A packaging bag in which the content of polyethylene in the packaging bag is 90% by mass or more based on the total amount of the packaging bag.
[2] The packaging bag according to [1], wherein the bottom tape further includes a barrier layer between the second base layer and the second sealant layer.
[3] In [2], the barrier layer has a structure in which a barrier base material layer containing polyethylene, a subbing layer, an inorganic oxide layer, and a gas barrier adhesive layer are laminated in this order. Packaging bag as described.
[4] The packaging bag according to [3], wherein the gas barrier adhesive layer has an oxygen permeability of 100 cc/m ² ·day · atm or less.
[5] The packaging bag according to [3] or [4], wherein the gas barrier adhesive layer is a layer formed using an epoxy adhesive.
[6] The packaging bag according to any one of [3] to [5], wherein the inorganic oxide layer contains silicon oxide.
[7] A laminated film for bottom tape comprising a base layer and a sealant layer,
The base material layer includes a first resin layer and a second resin layer provided between the first resin layer and the sealant layer,
The first resin layer is a polyethylene film with a density of 0.93 g/cm ³ or more and 0.97 g/cm ³ or less,
The second resin layer is a polyethylene film with a density of 0.87 g/cm ³ or more and 0.91 g/cm ³ or less,
The first resin layer is thinner than the second resin layer,
A laminated film for a bottom tape, wherein the laminated film has a polyethylene content of 90% by mass or more based on the total amount of the laminated film.

DESCRIPTION OF SYMBOLS 1, 2... Main body part, 3... Bottom tape, 3a... Mountain fold part, 10... Standing pouch (packaging bag) L1... Base material layer (first base material layer), L2... Sealant layer (first sealant layer) ), L3... Base material layer (second base material layer), L3a, L3b, L3c... Resin layer, L4... Sealant layer (second sealant layer), L7... Barrier layer, L7a... Barrier base material layer, L7b ...Undercoat layer (anchor coat layer), L7c...Inorganic oxide layer, L7d...Gas barrier adhesive layer.

Claims (7)

A pair of main bodies each including a first base layer and a first sealant layer, and a bottom tape including a second base layer and a second sealant layer and having a mountain fold are heat-sealed. A packaging bag formed of
The second base layer includes a first resin layer and a second resin layer provided between the first resin layer and the second sealant layer,
The first resin layer is a polyethylene film having a density of 0.93 g/cm ³ or more and 0.97 g/cm ³ or less,
The second resin layer is a polyethylene film with a density of 0.87 g/cm ³ or more and 0.91 g/cm ³ or less,
The first resin layer is thinner than the second resin layer,
A packaging bag in which the content of polyethylene in the packaging bag is 90% by mass or more based on the total amount of the packaging bag. The packaging bag of claim 1, wherein the bottom tape further includes a barrier layer between the second base layer and the second sealant layer. 3. The barrier layer according to claim 2, wherein the barrier layer has a structure in which a barrier base material layer containing polyethylene, an undercoat layer, an inorganic oxide layer, and a gas barrier adhesive layer are laminated in this order. packaging bag. The packaging bag according to claim 3, wherein the gas barrier adhesive layer has an oxygen permeability of 100 cc/m ² ·day · atm or less. The packaging bag according to claim 3 or 4, wherein the gas barrier adhesive layer is a layer formed using an epoxy adhesive. The packaging bag according to claim 3 or 4, wherein the inorganic oxide layer contains silicon oxide. A laminated film for a bottom tape comprising a base layer and a sealant layer,
The base material layer includes a first resin layer and a second resin layer provided between the first resin layer and the sealant layer,
The first resin layer is a polyethylene film having a density of 0.93 g/cm ³ or more and 0.97 g/cm ³ or less,
The second resin layer is a polyethylene film with a density of 0.87 g/cm ³ or more and 0.91 g/cm ³ or less,
The first resin layer is thinner than the second resin layer,
A laminated film for a bottom tape, wherein the polyethylene content in the laminated film is 90% by mass or more based on the total amount of the laminated film.

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