JP2022191722A - Laminate and packaging bag using the same - Google Patents

Abstract

To provide a laminate that has excellent material recyclability and suitability for bag-making.SOLUTION: A laminate comprising at least a substrate layer and a sealant layer is characterized in that the substrate layer is polyolefin having an MD heat shrinkage of less than 20.0% when heat-treated at 150°C, the sealant layer is made of polyolefin, a melting point of the sealant layer is lower than that of the substrate layer by 10°C or more, and a polyolefin content in the laminate is 90 mass% or more.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laminate for packaging and a packaging bag using the same.

There are various types of packages depending on the nature of the contents to be packaged, the amount of contents, post-treatment to protect the contents from deterioration, the mode of transportation of the package, the method of opening the package, and the method of disposal. Materials are used in combination.

For example, standing pouches can make products stand out on store shelves, and the scope of their adoption is expanding. In order for the standing pouch to be able to see the entire surface without bending in the middle, the laminate constituting the pouch is required to have rigidity. Moreover, if the content is liquid, strength is required so that the bag will not break when dropped. In order to meet these functions, laminates in which polyester films, nylon films, polyolefin films, etc. are combined have been used.

However, due to recent heightened awareness of environmental issues, various products are required to have functions such as resource saving and reuse.

One method of reusing a laminate in which various materials are combined is to reseparate each material. It is necessary to perform various physical and mechanical actions. In addition, in order to separate the separated materials, it is necessary to use a physical action based on specific gravity or a spectroscopic method that differs depending on the material. It was not as efficient as spending more energy.

Another method is to construct the original laminate from the same type of material and reuse the laminate as an integrated material. In particular, thermoplastic resins include various types of materials such as polyolefin, polyester, and polyamide. Each of them can impart various properties depending on the molecular weight, molecular weight distribution, heat treatment, orientation, stretching state, and treatment. In particular, polyolefin-based materials are easy to use because they have low melting points and are easy to process, and various materials are produced from copolymers. Therefore, various methods have been proposed so far.

Patent Document 1 discloses a laminate for a packaging material comprising at least a substrate, an intermediate layer, and a heat-sealing layer, wherein the substrate, the intermediate layer, and the heat-sealing layer are made of the same material. A laminate for packaging materials is disclosed, characterized in that the base material and the intermediate layer are stretched, and the same material is polyolefin. In this invention, the polyolefin substrate is stretched in order to give strength and heat resistance to the laminate. The laminate is distorted during heat sealing, resulting in defects.

JP 2020-157715 A

The problem to be solved by the present invention is to provide a laminate having excellent material recyclability and bag-making aptitude.

A first aspect for solving the above problems is a laminate including at least a base material layer and a sealant layer, wherein the base material layer has an MD heat shrinkage rate of 10.0% when heat-treated at 150 ° C. The following polyolefin, the sealant layer is polyolefin, the melting point of the base material layer is higher than that of the sealant layer by 10 ° C. or more, and the polyolefin content in the laminate is 90% by mass or more. It is a laminate that

According to the first aspect, it is possible to obtain a packaging bag in which the laminated body is not distorted by heat during bag making, and the dimensions do not vary even when the bag is made at high speed.
In addition, since the polyolefin content in the laminate is 90% by mass or more, it can be recycled as a polyolefin resin and has high material recycling aptitude.

Furthermore, by providing a gas barrier layer between the base material layer and the sealant layer, a laminate having gas barrier properties can be obtained.

A second aspect of the present invention is a packaging bag provided by heat-sealing the sealant layer forming surfaces of the laminate. According to this aspect, it is possible to obtain a packaging bag that does not cause the laminated body to be distorted by heat and that does not have dimensional deviations even when the bag is made at high speed.

A third aspect of the present invention is the packaging bag according to the second aspect, further comprising a polyolefin member sandwiched between the sealant layer forming surfaces, and the polyolefin member and the sealant layer are made of the same resin. A packaging bag characterized by:

According to the third aspect, it is possible to obtain a package in which the vicinity of the heat-sealed portion of the polyolefin member is also bonded with sufficient strength to hold the contents and airtightness without the laminate being distorted by heat. can.

The laminate of the present invention has high material recycling suitability and high bag-making suitability.

1 is a cross-sectional view showing one mode of a laminate of the present invention; FIG. FIG. 4 is a cross-sectional view showing another aspect of the laminate of the present invention; FIG. 4 is a cross-sectional view showing another aspect of the laminate of the present invention; FIG. 4 is a cross-sectional view showing another aspect of the laminate of the present invention; 1 is a schematic diagram of a gusseted pouch with a spout, which is one aspect of the self-supporting packaging bag of the present invention. FIG. 1 is a schematic diagram of a standing pouch with a spout, which is one aspect of the self-supporting packaging bag of the present invention. FIG.

FIG. 1 is a cross-sectional view of a three-layer laminate 10, which is one embodiment of the laminate of the present invention. A three-layer laminate laminate 10 includes a substrate 1 , a gas barrier film layer 3 and a sealant layer 5 . A substrate 1, a gas barrier film layer 3, and a sealant layer 5 are bonded together via adhesive layers 2 and 4, respectively. The gas barrier film layer 3 comprises a gas barrier film substrate 3-b and a gas barrier layer 3-a. In the three-layer laminate 10, the gas barrier layer 3-a is positioned on the base material 1 side, and the gas barrier base material 3-b is positioned on the sealant layer 5 side.

FIG. 2 is a cross-sectional view of a three-layer laminate 20, which is another embodiment of the laminate of the present invention. A three-layer laminate laminate 20 includes a substrate 1 , a gas barrier film layer 3 and a sealant layer 5 . The gas barrier film layer 3 comprises a gas barrier film substrate 3-b and a gas barrier layer 3-a. The difference from the three-layer laminate 10 is that the gas barrier substrate 3-b is located on the substrate 1 side and the gas barrier layer 3-a is located on the sealant layer 5 side.

FIG. 3 is a cross-sectional view of a three-layer laminate 30, which is another embodiment of the laminate of the present invention. A three-layer laminate laminate 30 includes a substrate 1 , a gas barrier film layer 3 and a sealant layer 5 . The gas barrier film layer 3 comprises a gas barrier film substrate 3-b and a gas barrier layer 3-a. The difference from the three-layer laminate laminate 20 is that the positional relationship between the substrate 1 side and the gas barrier film layer 3 is reversed.

When the laminate of the present invention is a three-layer laminate laminate, either substrate 1 or gas barrier substrate 3b, or both, is polypropylene. When either or both of the base material 1 and the gas barrier base material 3b are made of polypropylene, the material can be selected within the range of polypropylene from the materials described later.
Moreover, in the three-layer laminate laminate, the adhesive layer 2 and the adhesive layer 4 are optional structures, and can be omitted when the base material 1 or the sealant layer 5 is formed in the directly adjacent layer.

FIG. 4 is a cross-sectional view of a two-layer laminate 40, which is another embodiment of the laminate of the present invention. A two-layer laminate laminate 40 comprises a gas barrier film layer 3 and a sealant layer 5 . The gas barrier film layer 3 comprises a gas barrier film substrate 3-b and a gas barrier layer 3-a. In the two-layer laminate 40, the gas barrier layer 3-a is positioned on the sealant layer 5 side.

When the laminate of the present invention is a two-layer laminate laminate, the gas barrier substrate 3b is polypropylene. When polypropylene is used as the gas barrier substrate 3b, it can be selected within the range of polypropylene from the gas barrier substrate materials described later.
In addition, in the two-layer laminate laminate, the adhesive layer 4 is optional and can be omitted when the sealant layer 5 is formed directly on the gas barrier film layer.

[Base material layer]
The substrate layer of the present invention is a polyolefin having a MD heat shrinkage of 10.0% or less when heat-treated at 150°C. Polyolefins include polyethylene, polypropylene and the like.

High-density polyethylene (HDPE) is exemplified as the polyethylene constituting the base material layer in consideration of vapor deposition processing, printing processing, bag-making processing, filling suitability, and the like. In addition, in order to improve physical properties such as flexibility, for example, high-density polyethylene (HDPE)/medium-density polyethylene (MDPE)/low-density polyethylene (LDPE)/medium-density polyethylene (MDPE) formed by co-extrusion / A multi-layer construction film such as high density polyethylene (HDPE) may be used as the substrate layer.

Polypropylene includes oriented polypropylene. In general, polypropylene is broadly classified into homopolymer, random copolymer, block copolymer, and terpolymer, and the polymer type is selected according to the application and required performance. Polymer polypropylene is preferred. Polypropylene base material with homopolymer on the outermost surface or heat-resistant resin such as nylon on the outermost surface is used, and the heat-resistant surface is placed on the outermost layer to improve heat resistance. It can reduce the problem of insufficient seal strength due to pseudo-adhesion and insufficient temperature. In addition, for the purpose of imparting easy adhesion and sealing properties, a multi-layered film in which a copolymer or terpolymer is formed as a skin layer by coextrusion on a homopolymer core layer may be used as the substrate layer. .

The polyolefin film that constitutes the base layer may be a stretched film or a non-stretched film. However, from the viewpoint of impact resistance, heat resistance, water resistance, dimensional stability, etc., the polyolefin film may be a stretched film. As a result, the laminate can be more suitably used for hot filling and retort/boiling treatments. The stretching method is not particularly limited, and any method such as inflation stretching, uniaxial stretching, or biaxial stretching may be used as long as a film with stable dimensions can be supplied.

Among them, it is preferable to use biaxially oriented polypropylene with high rigidity and high heat resistance, and as such, the MD heat shrinkage rate when heat treated at 150 ° C. is less than 20%, preferably 15% or less, more preferably 10 % or less can be used.

The melting point of the polypropylene film should be higher than that of the sealant layer, preferably 10° C. or higher, preferably 20° C. or higher. The melting point of the base material layer is preferably 150° C. or higher, more preferably 160° C. or higher. The melting point of the substrate layer can be measured using a differential scanning calorimeter (DSC). By satisfying both the MD heat shrinkage rate and the melting point, it is possible to obtain a packaging bag that has good bag-making aptitude and little deviation in size and pitch.

The thickness of the polyolefin film is not particularly limited. Depending on the application, the thickness can be 6 μm or more, preferably 9 μm or more, more preferably 12 μm or more. Also, the thickness can be 200 μm or less, preferably 50 μm or less, more preferably 38 μm or less. Within this range, excellent impact resistance and excellent gas barrier properties can be obtained.

The resin constituting the base material layer is not limited to petroleum-derived resins, and part or all of it may be a bio-derived resin material (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 base material may include commercially available biomass polyethylene (Green PE manufactured by Braskem, etc.), or mechanically recycled polyolefin made from used polyolefin products or resins (so-called burrs) generated in the manufacturing process of polyolefin products. It's okay.

The base material layer may contain components other than the polyolefin resin. Such components include, for example, polyamide, polyethylene terephthalate, polyvinyl alcohol, biodegradable resin materials (e.g., polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, etc.). is mentioned. The substrate layer may contain additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, and colorants. The amount of components other than the polyolefin resin in the substrate layer is preferably 15% by mass or less, more preferably 10% by mass or less, based on the total amount of the substrate layer.

The base material layer described above can be preferably used as a base material in a three-layer laminate in which a base material is arranged in the outermost layer. A three-layer laminate or a two-layer laminate in which a gas barrier base material of a gas barrier film layer is disposed as the outermost layer can be preferably used as a gas barrier base material.

[Sealant layer]
The sealant layer is a layer that imparts sealing properties by heat sealing in the laminate, and contains polyolefin. Also, the content of polyolefin in the sealant layer is, for example, above 40% by mass and is 70% by mass or more. The upper limit may be 100% by mass or 90% by mass. When the polyolefin content of the sealant layer is 70% by mass or more, the polyolefin content of the laminate (based on the total amount of the laminate) can be easily made 90% by mass or more, and a monomaterial can be easily realized.

A polyethylene resin or a polypropylene resin can be used as a resin material that constitutes the sealant layer. If the sealant layer is polyethylene, linear low density polyethylene (LLDPE) can be used. In addition, for the purpose of imparting rigidity, the gas barrier layer 3 is made of high-density polyethylene (HDPE) or medium-density polyethylene (MDPE), and the content side is made of low-density polyethylene (LDPE). film can also be used. Furthermore, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), linear low density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α olefin copolymer, ethylene- Ethylene-based resins such as (meth)acrylic acid copolymers, blended resins of polyethylene and polybutene, homopolypropylene resins (PP), propylene-ethylene random copolymers, propylene-ethylene block copolymers, propylene-α-olefins Polypropylene-based resins such as copolymers can be used alone, or they can be laminated by blending or co-extrusion. The thickness of the sealant layer is, for example, 40 μm or more and 150 μm or less. As the sealant layer, biomass-derived polyolefin may be used. For example, a sealant film partially or wholly containing biomass polyethylene using ethylene as a raw material may be used. Such a sealant film is disclosed, for example, in JP-A-2013-177531. The sealant layer may also contain mechanically recycled polyolefin made from used polyolefin products or resins (so-called burrs) generated during the manufacturing process of polyolefin products.

A packaging bag can be produced by arranging the laminate so that the sealant layers face each other and heat-sealing at least a part of the peripheral portion thereof. Examples of packaging bags include pillow bags, standing pouches, gusset pouches, three-sided seal bags, four-sided seal bags, pouches with spouts (standing pouches, gusset pouches, three-sided seal bags, etc.). At this time, by using a heat-resistant base material, pseudo-adhesion during bag making (a defect in which parts that should not be adhered stick to each other) and a sufficient bonding temperature are achieved because the difference in melting point between the base material and the sealant is small. It is possible to prevent insufficient sealing strength due to lack of time. A polyolefin film is preferable as a substrate having high heat resistance, and a film having a nylon layer or a homopolypropylene layer on the surface of the substrate, which is the outermost layer of the laminate, is particularly preferable.

The melting point difference between the sealant layer and the substrate is preferably 10 degrees or more, more preferably 20°C or more, and even more preferably 50°C or more. The melting point of the sealant layer itself is preferably 140° C. or lower, more preferably 120° C. or lower.
In addition to packaging bags, laminates are applied to various uses such as packaging products such as containers, decorative sheets, sheet molded products such as trays, optical films, resin plates, various label materials, lid materials, and laminated tubes. can do.

The laminate of the present invention may have an adhesive layer between the substrate and the gas barrier film layer and between the gas barrier film layer and the sealant layer.
The adhesive constituting the adhesive layer can be selected according to the bonding method, and for example, urethane-based adhesives, polyester-based adhesives, epoxy-based adhesives, and the like can be used. By providing an adhesive layer, the interlayer adhesion between the base material and the sealant layer, or between the gas barrier film layer and the base material, or between the gas barrier film layer and the sealant layer is increased, making it difficult for delamination to occur. can retain their sexuality. For example, a dry lamination method that uses adhesives such as one-component curing or two-component curing urethane adhesives, a non-solvent dry lamination method that uses non-solvent adhesives, and heats polyolefin resins such as polyethylene and polypropylene. Examples include an extrusion lamination method in which the material is melted, extruded in the form of a curtain, and laminated.

Preferably, the adhesive layer does not contain chlorine. Since the adhesive layer does not contain chlorine, it is possible to prevent the adhesive and the regenerated resin from being colored and the generation of odor due to heat treatment. Using an adhesive containing a biomass material as the adhesive layer is preferable from the viewpoint of environmental friendliness. From the viewpoint of environmental consideration, it is preferable to use a method that does not use a solvent for adhesion.

[Gas barrier film layer]
The gas barrier film layer includes at least a gas barrier substrate and a gas barrier layer. The gas barrier film layer includes, for example, a polyolefin film as a gas barrier base material and a vapor-deposited or coated gas barrier layer.

Examples of gas barrier layers include gas barrier coatings containing polyvinyl alcohol and the like, and vapor deposition layers of inorganic oxides or metals. Examples of inorganic oxides include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. Examples of metals include aluminum. The deposited layer can be formed by, for example, physical vapor deposition, chemical vapor deposition, or the like.

Materials described as the substrate layer can be used for the gas barrier substrate. The thickness of the gas barrier base material is, for example, 5 μm or more and 10 μm or more. Moreover, it is 800 μm or less, and may be 500 μm or less or 100 μm or less. The melting point of the gas barrier substrate can be measured using a differential scanning calorimeter (DSC). When the laminate is a three-layer laminate laminate, the gas barrier substrate preferably exhibits a melting point similar to that of the substrate. On the other hand, the gas barrier base material preferably has a melting point higher than that of the sealant layer by 20°C or more, more preferably 25°C or more. The melting point of the gas barrier substrate is preferably 120°C or higher, more preferably 125°C or higher.

When the laminate is a two-layer laminate, the gas barrier substrate should be made of polyolefin having a MD heat shrinkage of less than 20%, preferably 15% or less, more preferably 10% or less when heat-treated at 150°C. can be done. In addition, the melting point of the gas barrier base material in this case should be higher than that of the sealant layer, preferably 10° C. or higher, preferably 20° C. or higher. The melting point of the base material layer is preferably 150° C. or higher, more preferably 160° C. or higher. By satisfying both the MD heat shrinkage rate and the melting point, it is possible to obtain a packaging bag that has good bag-making aptitude and little deviation in size and pitch. A polyolefin film is preferable as a gas barrier substrate having high heat resistance, and a film having a nylon layer or a homopolypropylene layer on the surface without a gas barrier layer, which is the outermost layer of the laminate, is particularly preferable. As the polyolefin having such physical properties, specifically, biaxially oriented polypropylene having high rigidity and high heat resistance can be used.

Materials for the gas barrier base material include polyethylene resins and polypropylene resins, as with the base material. Also, similar to the base material, a biomass-derived resin or a mechanically recycled resin may be used. In addition, like the base material, components and additives other than the polyolefin resin can be included within a range that does not hinder the recyclability of the laminated film. The gas barrier substrate may be subjected to surface treatment such as corona treatment, ozone treatment, flame treatment, etc. on the surface on which the vapor deposition layer is formed. From the viewpoint of heat resistance, it is preferable to use a stretched base material as the gas barrier base material. When uniaxially oriented polyolefin is used, it is preferable to align the orientation direction with that of the substrate layer in order to maintain the easy tearability.

The laminate according to the present disclosure may include an anchor coat layer (not shown) between the substrate and the gas barrier layer, between the gas barrier layer and the sealant layer, and between the substrate and the sealant layer. The anchor coat layer may be a very thin layer that does not affect the recyclability of the laminate, 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.

Although the thickness of the anchor coat layer is not particularly limited, it is preferably in the range of 0.05 μm or more and 2 μm or less. When the thickness is more than 0.05 μm, an improvement in the adhesive strength between layers can be expected. When the thickness is less than 2 μm, the proportion of polyolefin in the laminate is increased, and the recyclability of the laminate is improved.

The laminate according to the present disclosure may further include, for example, a printing layer (not shown) for text information, patterns, etc., and gravure printing, flexographic printing, and the like are possible. The print layer may be provided between the substrate and the gas barrier film layer in the case of a three-layer laminate laminate. In the case of a two-layer laminate laminate, it may be provided between the gas barrier film layer and the sealant layer. It may be provided on the surface opposite to the gas barrier layer forming surface of the gas barrier substrate. 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 ink components from being colored or odorous during remelting in mechanical recycling. Moreover, it is preferable to use a biomass material for the binder component contained in the printing ink from the viewpoint of environmental friendliness. Further, the printing ink is preferably water-based ink using water or alcohol as a solvent, and it is preferable to apply water-based flexographic printing that does not use an organic solvent from the viewpoint of environmental consideration.

One aspect of the self-supporting packaging bag in the form of packaging according to the present invention is a gusset pouch. FIG. 5 is a schematic diagram of a gusseted pouch with a spout, which is one aspect of the self-supporting packaging bag of the present invention. As shown in FIG. 5, the gusseted pouch 100 with a spout consists of two side wall laminates 140 and two side wall laminates 150 folded in two, and the peripheral edges of the side wall laminates 140 and side wall laminates 150 are Sealed. A spout-equipped gusset pouch 100 can be obtained by providing a spout consisting of a spout 104 and a cap 104a on the upper side of the pouch body of such a gusset pouch.

Another aspect of the self-supporting packaging bag in the form of packaging according to the present invention is a standing pouch. FIG. 6 is a schematic diagram of a standing pouch with a spout, which is another embodiment of the self-supporting packaging bag of the present invention. A standing pouch with spout 200 is a packaging bag composed of two side wall laminated bodies 201 and one bottom laminated body 202 folded in half, as shown in FIG. 6, and having its periphery sealed. A standing pouch 200 with a spout can be obtained by providing a spout 203 consisting of a spout and a cap on the upper side of the pouch body of such a standing pouch.

The side wall laminate 201 and the bottom laminate 202 of the standing pouch 200 with a spout may have the same laminate structure or different laminate structures. It can be adjusted according to the type and weight of the contents.

Polyolefin can be used for the spout and cap of the self-supporting packaging bag according to the present invention. This provides reusability of the entire package. Also, the spout can be molded by a known molding method such as injection molding or compression molding. From the viewpoint of improving recyclability, polyethylene can be used more preferably.
A more detailed description will be given below based on examples.

Using the laminate according to the present invention, a laminate for the side wall and a laminate for the bottom of a standing pouch as a self-supporting packaging bag were produced as follows. Hereinafter, the present disclosure will be described in more detail based on examples, but the present invention is not limited to the following examples.

(Example 1)
A biaxially oriented polypropylene film A1 (thickness: 20 μm) was used as the base material, and a silicon oxide-deposited biaxially oriented polypropylene film (thickness of the gas barrier base material: 18 μm) was used as the gas barrier film. The gas barrier base material is formed by co-extrusion of an EVOH layer on an OPP film. An acrylic urethane coating is applied to the EVOH layer, and a silicon oxide layer having a thickness of 30 μm is formed using a vacuum deposition apparatus using an electron beam heating method. It is provided with a transparent film.

The base material and the gas barrier film were bonded together via an adhesive (manufactured by Mitsui Chemicals, Inc., brand A626). The thickness of the adhesive layer is 3 μm. At this time, the gas barrier layer was arranged on the side opposite to the substrate. Furthermore, linear low-density polyethylene B1 (thickness: 60 μm) was laminated as a sealant layer via an adhesive (manufactured by Mitsui Chemicals, Inc., brand A626). The thickness of the adhesive layer is 3 μm. The laminate of Example 1 is a three-layer laminate consisting of substrate/adhesive layer/gas barrier film layer/adhesive layer/sealant layer.

(Example 2)
A biaxially oriented polypropylene film A1 (thickness: 20 μm) was used as the substrate, and an aluminum oxide-deposited biaxially oriented polypropylene film (gas barrier substrate thickness: 18 μm) was used as the gas barrier film. The gas barrier layer is obtained by applying an acrylic urethane coating on a gas barrier base material, and then using a vacuum vapor deposition apparatus using an electron beam heating method to form a transparent aluminum oxide film having a thickness of 15 μm.

The base material and the gas barrier film were bonded together via an adhesive (manufactured by Mitsui Chemicals, Inc., brand A626). The thickness of the adhesive layer is 3 μm. At this time, the gas barrier layer was arranged on the side opposite to the substrate. Furthermore, linear low-density polyethylene B1 (thickness: 60 μm) was laminated as a sealant layer via an adhesive (manufactured by Mitsui Chemicals, Inc., brand A626). The thickness of the adhesive layer is 3 μm. The laminate of Example 1 is a three-layer laminate consisting of substrate/adhesive layer/gas barrier film layer/adhesive layer/sealant layer.

(Example 3)
Example 2 was obtained in the same manner as in Example 1, except that an unstretched polyethylene film (thickness of gas barrier substrate: 32 μm) deposited with silicon oxide was used as the gas barrier film layer. The laminate of Example 2 is a three-layer laminate consisting of substrate/adhesive layer/gas barrier film layer/adhesive layer/sealant layer.

(Example 4)
Example 3 was obtained in the same manner as in Example 1, except that an unstretched polypropylene film B2 (thickness: 60 μm) was used as the sealant layer instead of the linear low-density polyethylene B1. The laminate of Example 4 is a three-layer laminate consisting of substrate/adhesive layer/gas barrier film layer/adhesive layer/sealant layer.

(Example 5)
Example 3 was obtained in the same manner as in Example 2, except that an unstretched polypropylene film B2 (thickness: 60 µm) was used as the sealant layer instead of the linear low-density polyethylene B1. The laminate of Example 5 is a three-layer laminate consisting of substrate/adhesive layer/gas barrier film layer/adhesive layer/sealant layer.

(Comparative example 1)
A three-layer laminate laminate of Comparative Example 1 was prepared in the same manner as in Example 1 except that a biaxially oriented polypropylene film A2 (20 μm thick) was used as the base material instead of the biaxially oriented polypropylene film A1 (thickness 20 μm). Obtained.

(Comparative example 2)
A three-layer laminate laminate of Comparative Example 2 was prepared in the same manner as in Example 2 except that a biaxially oriented polypropylene film A2 (20 μm in thickness) was used instead of the biaxially oriented polypropylene film A1 (20 μm in thickness) as the substrate. Obtained.

(Comparative Example 3)
A three-layer laminate laminate of Comparative Example 3 was prepared in the same manner as in Example 3 except that a biaxially oriented polypropylene film A2 (20 μm in thickness) was used instead of the biaxially oriented polypropylene film A1 (20 μm in thickness) as the substrate. Obtained.

(Comparative Example 4)
A three-layer laminate laminate of Comparative Example 4 was prepared in the same manner as in Example 2 except that a biaxially oriented polypropylene film A2 (20 μm thick) was used as the base material instead of the biaxially oriented polypropylene film A1 (thickness 20 μm). Obtained.

(Comparative Example 5)
A three-layer laminate laminate of Comparative Example 5 was prepared in the same manner as in Example 2 except that a biaxially oriented polypropylene film A2 (20 μm thick) was used as the base material instead of the biaxially oriented polypropylene film A1 (thickness 20 μm). Obtained.

(Comparative Example 6)
A three-layer laminate of Comparative Example 6 was obtained in the same manner as in Example 1, except that an unstretched polypropylene film B3 (thickness: 60 μm) was used as the sealant layer instead of the linear low-density polyethylene B1.

(Comparative Example 7)
A three-layer laminate of Comparative Example 7 was obtained in the same manner as in Example 1, except that an unstretched polypropylene film B3 (thickness: 60 μm) was used as the sealant layer in place of the linear low-density polyethylene B1.

The melting points of the base material and sealant layer were measured using a differential scanning calorimeter (DSC). The melting points and differences between the base material and the sealant layer are listed in Table 1.

Using the laminates of Examples 1 to 3 and Comparative Examples 1 to 4, a standing pouch composed of two side wall laminates and one bottom laminate folded in half and heat-sealed at the periphery was produced. did. The standing pouch has a height of 125 mm, a width of 95 mm, and a folding depth (the depth of the valley fold portion of the bottom laminate) of 28 mm. Table 1 shows the results as to whether or not the bag can be made. ◯ indicates 5% or less, Δ indicates 10% or less, and x indicates 15% or less, relative to the standard value for the seal width of the side surfaces of the side wall laminates.

Using the laminates of Examples 1 to 3 and Comparative Examples 1 to 4, two side wall laminates and one bottom laminate folded in half were heat-sealed at their peripheries, and further a polyethylene spout member was attached. A standing pouch with a spout was prepared by sandwiching and welding. The packaging bags of Examples 1 to 3 were welded with good precision and good appearance.

(MD heat shrinkage)
The thermal shrinkage of the substrate was measured. A mark of 150×150 mm was made at the center of the 250×250 mm film, held in an oven at 150° C. for 5 minutes, taken out, and then measured for the length in the MD direction.

Regarding the laminates of Examples 1 to 5, the oxygen permeability was measured at a temperature of 30° C. and a relative humidity difference of 70% according to JIS K7126-2:2006. The evaluation results are shown in Table 1.

Regarding the laminates of Examples 1 to 5, the water vapor permeability was measured according to JIS K7129B at a temperature of 40° C. and a relative humidity difference of 90%. The evaluation results are shown in Table 1.
Measuring device: Mocon Co., Ltd., water vapor permeation measuring device PERMATRAN-W3/33.

From the results in Table 1, Examples 1 to 5 were able to provide packaging bags that maintained barrier properties.

10, 20, 30... 3-layer laminate 40... 2-layer laminate 1... Base material 2, 4... Adhesive layer 3... Gas barrier film layer 3a... Gas barrier layer 3b... Gas barrier base material 5... Sealant layer 100... Gusset pouch with spout, 104a... Cap, 104... Spout, 130... Seal part, 140... Side wall laminate, 150... Side wall laminate 200... Standing pouch with spout, 201... Side wall laminate , 202... Laminate for bottom, 203... Plug

Claims (3)

A laminate comprising at least a substrate layer and a sealant layer,
The base material layer is a polyolefin having an MD heat shrinkage rate of less than 20.0% when heat-treated at 150 ° C.,
The sealant layer is polyolefin,
The melting point of the sealant layer is lower than that of the base material layer by 10° C. or more,
A laminate, wherein the content of polyolefin in the laminate is 90% by mass or more. 2. The laminate according to claim 1, further comprising a gas barrier layer between the base material layer and the sealant layer. A packaging bag provided by heat-sealing the sealant layer forming surfaces of the laminate according to claim 1 or 2.

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