JP2023064639A - Small bag - Google Patents

Abstract

To provide a small bag that is at least partially composed of a laminate having a base material composed of polyethylene and a heat seal layer, which can provide sufficient heat seal strength when being heat-sealed at low temperatures.SOLUTION: A small bag is at least partially composed of a laminate having a base material composed of polyethylene, and a heat seal layer, wherein the heat seal layer has a polyethylene resin layer (1) having density of 0.920 g/cm3 or less, and a resin layer (2) containing linear low density polyethylene and low density polyethylene, and the polyethylene resin layer (1) is positioned on the innermost layer of the small bag.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to pouches.

Conventionally, a resin film made of polyester such as polyethylene terephthalate (hereinafter also referred to as "polyester film") has excellent mechanical properties, chemical stability, heat resistance and transparency, and is inexpensive. It is used as a material (see, for example, Patent Document 1).

A polyester film is laminated, for example, with a polyethylene film that functions as a heat-seal layer. A packaging container such as a sachet is produced using a packaging material comprising a laminate thus obtained. However, it is generally difficult to separate a packaging container comprising a polyester film and a polyethylene film into the respective films. Therefore, the current situation is that such packaging containers are not suitable for recycling after use and are not actively recycled.

In view of such a situation, production of a monomaterial packaging container is being studied for the purpose of improving the recyclability of the packaging container. For example, in place of the polyester film, the laminate is provided with a stretched polyethylene film (hereinafter also referred to as "stretched polyethylene film") as a base material, and a polyethylene film made of the same type of resin material as a heat seal layer. Packaging materials are being considered.

JP-A-2005-053223

When an oriented polyethylene film is used as the base material of the packaging material instead of a film with excellent heat resistance such as a polyester film, heat sealing should be performed at a low temperature from the viewpoint of suppressing thermal deterioration of the base material during heat sealing. is desirable. Conventionally, a polyethylene film is used that functions as a heat-seal layer. However, with conventional heat-sealing layers, sufficient heat-sealing strength cannot be obtained when heat-sealing is performed at a low temperature.

The problem to be solved by the present disclosure is a small bag at least partially composed of a laminate including a base material made of polyethylene and a heat-sealing layer, and when heat-sealed at a low temperature, it is sufficiently To provide a sachet capable of obtaining an excellent heat-sealing strength.

The sachet of the present disclosure is a sachet at least partially composed of a laminate comprising a base material made of polyethylene and a heat-sealing layer, wherein the heat-sealing layer has a density of 0.920 g/cm ³ or less. and a resin layer (2) containing linear low-density polyethylene and low-density polyethylene, the polyethylene resin layer (1) being the innermost layer of the pouch.

According to the present disclosure, a small pouch at least partially composed of a laminate including a base material made of polyethylene and a heat-sealing layer, and having sufficient heat-sealing strength when heat-sealed at a low temperature can provide a sachet that yields

FIG. 1 is a schematic cross-sectional view of one embodiment of a laminate comprising a pouch of the present disclosure. FIG. 2 is a schematic cross-sectional view of one embodiment of a laminate comprising a pouch of the present disclosure; FIG. 3 is a schematic cross-sectional view of one embodiment of a laminate comprising a pouch of the present disclosure; FIG. 4 is a schematic cross-sectional view of one embodiment of a laminate comprising a pouch of the present disclosure;

Hereinafter, the details of the laminate and the like constituting at least a part of the pouch of the present disclosure will be described, and then the pouch of the present disclosure will be described.

[Laminate]
The laminate includes a substrate made of polyethylene and a heat seal layer. The heat seal layer comprises a polyethylene resin layer (1) having a density of 0.920 g/cm ³ or less and a resin layer (2) containing linear low density polyethylene and low density polyethylene. A surface layer on one side of the laminate is a polyethylene resin layer (1). Hereinafter, the polyethylene resin layer (1) is also simply referred to as "resin layer (1)".
In one embodiment, the resin layer (1) is a surface layer on one side of the heat seal layer and the resin layer (2) is a surface layer on the other side of the heat seal layer. In one embodiment, when a small bag is produced using the packaging material comprising the laminate, the resin layer (1) is located in the innermost layer of the small bag, i.e., the layer facing the content contained in the small bag. is.

In one embodiment of the laminate, the substrate and the heat seal layer are made of polyethylene, which is the same type of resin material. That is, in one embodiment, the base material is made of polyethylene, and the heat seal layer is made of polyethylene, which is the same type of resin material as the resin material that makes up the base material. By using a laminate having such a configuration, for example, a small bag with excellent recyclability can be produced.

In the present disclosure, the description “AAA composed of polyethylene” means that the main component of the AAA is polyethylene, but the AAA is not limited to a configuration composed only of polyethylene. The AAA may contain components other than polyethylene. Specifically, the content of polyethylene in the AAA is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more.

For example, polyethylene includes high-density polyethylene and linear low-density polyethylene, which are classified into the same type of resin material. On the other hand, for example, polyethylene and polyester are not classified as the same type of resin material.

The content of polyethylene in the entire laminate is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more. Since such a laminate uses polyethylene, which is a resin material of the same kind, it can be classified as a so-called mono-material material, and can be suitably used, for example, for producing a mono-material packaging container.

FIG. 1 shows one embodiment of the laminate. The laminate 1 includes a heat seal layer 2, an optional adhesive layer 32, and a substrate 30 in this order in the thickness direction. The heat seal layer 2 includes a resin layer (1) 10 and a resin layer (2) 12 in this order in the thickness direction. In one embodiment, the laminate 1 further includes a printed layer (not shown) on the substrate 30 . The printed layer is usually formed on the surface of the substrate 30 on the side of the heat seal layer 2 .

FIG. 2 shows one embodiment of the laminate. The laminate 1 includes a heat seal layer 2, a metal deposition film 20, an adhesive layer 32 provided as necessary, and a substrate 30 in this order in the thickness direction. The heat seal layer 2 includes a resin layer (1) 10 and a resin layer (2) 12 in this order in the thickness direction.

FIG. 3 shows an embodiment of the laminate. 3, except that the heat seal layer 2 includes a resin layer (1) 10, an intermediate layer 11, and a resin layer (2) 12 in this order in the thickness direction. It is the same as the laminate shown.

FIG. 4 shows an embodiment of the laminate. The laminate 1 shown in FIG. 4 is similar to that shown in FIG. It is the same as the laminate shown.

In one embodiment, the laminate contains polyethylene as a resin material forming each layer. In the present disclosure, polyethylene refers to a polymer containing 50 mol % or more of ethylene-derived structural units in all repeating structural units. In this polymer, the content of ethylene-derived structural units is preferably 70 mol % or more, more preferably 80 mol % or more, still more preferably 90 mol % or more, and particularly preferably 95 mol % or more. The content ratio can be measured by the NMR method.

In the present disclosure, polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of ethylenically unsaturated monomers other than ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. , 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene and 6-methyl-1-heptene, α-olefins having 2 to 20 carbon atoms; vinyls such as vinyl acetate and vinyl propionate monomers; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

In the present disclosure, polyethylene preferably includes high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene and ultra low density polyethylene.

In the present disclosure, the density of the polyethylene is as follows.
The density of high density polyethylene is preferably above 0.945 g/ ^cm3 . The upper limit of the density of high density polyethylene is, for example, 0.965 g/cm ³ .
The density of medium density polyethylene is preferably greater than 0.930 g/cm ³ and less than or equal to 0.945 g/cm ³ .

The density of the low density polyethylene is preferably greater than 0.900 g/cm ³ and less than or equal to 0.930 g/cm ³ . Low-density polyethylene is usually polyethylene obtained by polymerizing ethylene by a high-pressure polymerization method.

The density of the linear low-density polyethylene is preferably greater than 0.900 g/cm ³ and less than or equal to 0.930 g/cm ³ . Linear low-density polyethylene is usually polyethylene obtained by polymerizing ethylene and a small amount of α-olefin by a low-pressure polymerization method (eg, polymerization method using a Ziegler-Natta catalyst or metallocene catalyst).

The density of the ultra-low density polyethylene is preferably 0.900 g/cm ³ or less. The lower limit of the density of ultra-low density polyethylene is, for example, 0.860 g/cm ³ .
The density of polyethylene is measured according to JIS K7112, particularly D method (density gradient tube method, 23°C).

In the present disclosure, the melt flow rate (MFR) of polyethylene is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.3 g, from the viewpoint of film formability, processability of the laminate, and the like. /10 min or more and 30 g/10 min or less, more preferably 0.5 g/10 min or more and 10 g/10 min or less, particularly preferably 0.7 g/10 min or more and 5.0 g/10 min or less. The MFR of polyethylene is measured by A method in accordance with JIS K7210 under conditions of a temperature of 190° C. and a load of 2.16 kg.

In the present disclosure, the melting point (Tm) of polyethylene is preferably 100° C. or higher and 140° C. or lower, more preferably 105° C. or higher and 130° C. or lower, and still more preferably 110° C. or higher, from the viewpoint of the balance between heat resistance and heat sealability. 125°C or less. Tm is obtained by differential scanning calorimetry (DSC) according to JIS K7121.

Polyethylenes with different densities or branches can be obtained by appropriately selecting the polymerization method. For example, using a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as a polymerization catalyst, one-stage polymerization is performed by any of gas phase polymerization, slurry polymerization, solution polymerization and high-pressure ion polymerization. Alternatively, it is preferable to carry out the polymerization in two or more stages.

A single-site catalyst is a catalyst capable of forming uniform active species, and is usually prepared by contacting a metallocene-based transition metal compound or a non-metallocene-based transition metal compound with an activating cocatalyst. A single-site catalyst has a more uniform structure of active sites than a multi-site catalyst, and is therefore preferable because a polymer having a high molecular weight and a highly uniform structure can be obtained.

A metallocene catalyst is preferred as the single-site catalyst. The metallocene catalyst is a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, optionally an organometallic compound, and optionally a carrier.

Examples of transition metals in transition metal compounds include zirconium, titanium and hafnium, with zirconium and hafnium being preferred.

The cyclopentadienyl skeleton in the transition metal compound is a cyclopentadienyl group or a substituted cyclopentadienyl group. Substituted cyclopentadienyl groups include, for example, hydrocarbon groups having 1 to 30 carbon atoms, silyl groups, silyl-substituted alkyl groups, silyl-substituted aryl groups, cyano groups, cyanoalkyl groups, cyanoaryl groups, halogen groups, and haloalkyl groups. , and halosilyl groups. A substituted cyclopentadienyl group has one or more substituents, and the substituents are bonded to each other to form a ring, an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenation product thereof. may be formed. A ring formed by combining substituents with each other may further have a substituent.

A transition metal compound usually has two ligands having a cyclopentadienyl skeleton. Each ligand having a cyclopentadienyl skeleton is preferably linked to each other by a bridging group. Examples of the cross-linking group include an alkylene group having 1 to 4 carbon atoms, a silylene group, a substituted silylene group such as a dialkylsilylene group and a diarylsilylene group, and a substituted germylene group such as a dialkylgermylene group and a diarylgermylene group. . Among these, substituted silylene groups are preferred.

A co-catalyst is a component that allows a transition metal compound of group IV of the periodic table to function effectively as a polymerization catalyst, or a component that balances ionic charges in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes, benzene-insoluble organoaluminumoxy compounds, ion-exchange layered silicates, boron compounds, and ions composed of cations containing or not containing active hydrogen groups and non-coordinating anions. lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

Optional organometallic compounds include, for example, organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Among these, organoaluminum compounds are preferred.

The transition metal compound may be supported on an inorganic or organic compound carrier before use. As the carrier, porous oxides _of inorganic or organic compounds are preferred, and specific examples include ion-exchange layered silicates such as montmorillonite, _SiO2 , _Al2O3 , MgO, _ZrO2 , _TiO2 , and _B2O . ₃ , CaO, ZnO, BaO, _ThO2 , or mixtures thereof.

As polyethylene, biomass-derived polyethylene may be used. That is, as a raw material for obtaining polyethylene, ethylene derived from biomass may be used instead of ethylene derived from fossil fuel. Since biomass-derived polyethylene is a carbon neutral material, it can reduce the environmental impact of laminates or packaging materials. Biomass-derived polyethylene can be produced, for example, by the method described in JP-A-2013-177531. Commercially available biomass-derived polyethylene (eg, Green PE available from Braskem) may be used.

As polyethylene, polyethylene recycled by mechanical recycling or chemical recycling may be used. As a result, the environmental impact of the laminate or packaging material can be reduced. Mechanical recycling generally involves pulverizing collected polyethylene film, washing with alkali to remove dirt and foreign matter from the surface of the film, and then drying it for a certain period of time under high temperature and reduced pressure until it remains inside the film. This is a method of decontaminating by diffusing contaminants, removing dirt from the film, and returning it to polyethylene again. Chemical recycling is generally a method of decomposing a recovered polyethylene film or the like down to the level of monomers and polymerizing the monomers again to obtain polyethylene.
The description of polyethylene above is applicable to polyethylene in the description below.

<Heat seal layer>
The content of polyethylene in the entire heat seal layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, it is possible to improve the recyclability of the packaging material composed of the laminate.

The heat seal layer is preferably an unstretched film from the viewpoint of heat sealability. An unstretched film is a film that has not been stretched, for example, an extruded film that has not been stretched. The details of the stretching process will be described later in the description of the base material.

In one embodiment, the number of layers of the heat seal layer is 2 or more and 7 or less, for example, 3 or more and 7 or less, or 3 or more and 5 or less. The number of layers of the heat seal layer is odd in one embodiment, for example 3 layers, 5 layers or 7 layers. With such a configuration, for example, the symmetry of the laminated structure of the heat seal layer is enhanced, and the occurrence of curling in the heat seal layer can be suppressed.

In any two layers adjacent in the thickness direction in the heat seal layer, the absolute value of the difference between the density of one layer and the density of the other layer is preferably 0.040 g / cm ³ or less, more preferably 0 .035 g/cm ³ or less. When any two adjacent layers have a density difference within the above range, for example, it is possible to effectively suppress the occurrence of delamination at the interface between the layers constituting the heat seal layer.

In the present disclosure, the density of each layer may be measured according to JIS K7112 above, or calculated from the density of the components constituting the layer. For example, if one layer contains a plurality of components (e.g., polyethylene) with different densities (n types; n is an integer of 2 or more), the average density D _av calculated according to the following formula (f1) is It may be the density of the layer.

D _av =ΣW _i ×D _i (f1)
In formula (f1), Σ means taking the sum of W _i ×D _i from 1 to n for i, n is an integer of 2 or more, and W _i is the mass fraction of the i-th component. and D _i indicates the density (g/cm ³ ) of the i-th component.

In one embodiment, the heat seal layer is a coextruded resin film, and each layer constituting the heat seal layer is a coextruded resin layer. A co-extruded resin film can be produced by forming a film using, for example, an inflation method or a T-die method.

The total thickness of the heat seal layer is preferably 10 μm or more and 300 μm or less, more preferably 15 μm or more and 250 μm or less. From the viewpoint of the strength and workability of the heat seal layer, it is preferable to change the total thickness of the heat seal layer as appropriate according to the mass of the contents contained in the small bag described later.

The total thickness of the heat seal layer is particularly preferably 20 µm or more and 60 µm or less. In this case, for example, 1 g or more and 200 g or less of contents can be well accommodated in the small bag. The heat-seal layer is suitable as a heat-seal layer for small bags.

Each layer included in the heat seal layer will be described below.

(Resin layer (1))
The resin layer (1) contains one or more polyethylenes.
Details of the polyethylene are as described above.

The density of the resin layer (1) is 0.920 g/cm ³ or less, preferably 0.860 g/cm ³ or more and 0.920 g/cm ³ or less, more preferably 0.900 g/cm ³ or more and 0.918 g/cm 3 or more. cm ³ or less.

In one embodiment, when a small bag is produced using the packaging material comprising the laminate, the resin layer (1) is a layer that faces the content contained in the small bag. Since the resin layer (1) has a density of 0.920 g/cm ³ or less, sufficient heat sealing strength can be obtained even when heat sealing is performed at a low temperature (for example, about 140° C.).

The resin layer (1) preferably contains linear low-density polyethylene. A linear low-density polyethylene having a density in the above range of the resin layer (1) is preferable, and a linear low-density polyethylene having a density exceeding 0.900 g/cm ³ and not more than 0.920 g/cm ³ is more preferable.

The content of linear low-density polyethylene in the resin layer (1) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. With such a configuration, for example, the low temperature heat sealability of the heat seal layer can be improved.

The resin layer (1) contains low density polyethylene in one embodiment. With such a configuration, for example, the film formability and cuttability of the heat seal layer can be improved.

The content of low-density polyethylene in the resin layer (1) is, for example, 0.5% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 10% by mass or less. be. With such a configuration, for example, the film formability and cuttability of the heat seal layer can be improved.

The resin layer (1) may contain one or more resin materials other than polyethylene. Examples of the resin material include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of recyclability of the laminate, it is particularly preferable that the resin layer (1) does not contain any resin material other than polyethylene.

In one embodiment, the resin layer (1) further contains an antiblocking agent. With such a configuration, for example, the antiblocking property of the heat seal layer can be improved.

Antiblocking agents include, for example, inorganic antiblocking agents and organic antiblocking agents.

Examples of inorganic anti-blocking agents include oxides such as silica, aluminum oxide, magnesium oxide, calcium oxide, titanium oxide and zinc oxide; hydroxides such as aluminum hydroxide, magnesium hydroxide and calcium hydroxide; magnesium carbonate. and carbonates such as calcium carbonate; sulfates such as calcium sulfate and barium sulfate; silicates such as magnesium silicate, aluminum silicate, calcium silicate and aluminosilicate; kaolin, talc, zeolite (synthetic zeolite or natural zeolite) and diatomaceous earth.

Examples of organic anti-blocking agents include (meth)acrylic resin particles such as polymethyl methacrylate (PMMA) resin particles, styrene resin particles, and melamine resin particles.

The average particle size of the antiblocking agent is, for example, 1 μm or more and 10 μm or less. The average particle size is the number average particle size measured using a laser diffraction particle size distribution analyzer (SALD-2000J, manufactured by Shimadzu Corporation) or an equivalent device.

When forming the resin layer (1), a masterbatch containing an antiblocking agent and polyethylene may be used. The content of the antiblocking agent in the masterbatch is preferably from 1% by mass to 45% by mass, more preferably from 5% by mass to 40% by mass, and even more preferably from 10% by mass to 35% by mass. Specific examples of polyethylene include those mentioned above. The preferred physical properties (density, melting point, MFR, etc.) satisfied by polyethylene are also as described above.

The resin layer (1) can contain one or more antiblocking agents.
In one embodiment, the content of the antiblocking agent in the resin layer (1) is preferably 0.1% by mass or more and 15% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less. With such a configuration, for example, the antiblocking property of the heat seal layer can be improved.

The resin layer (1) may contain one or more additives. Examples of additives include cross-linking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins.

In the heat seal layer, the difference (D2-D1) between the density D2 of the resin layer (2) and the density D1 of the resin layer (1) is preferably 0.020 g/cm ³ or less, more preferably 0.015 g/cm3. cm ³ or less, more preferably 0.010 g/cm ³ or less. With such a configuration, the symmetry of the laminated structure of the heat-sealing layer is enhanced, and, for example, curling of the heat-sealing layer can be suppressed.

The ratio of the thickness of the resin layer (1) to the total thickness of the heat seal layer is preferably 2% or more and 30% or less, more preferably 5% or more and 25% or less, and still more preferably 10% or more and 25% or less. .

(Resin layer (2))
The resin layer (2) contains linear low density polyethylene and low density polyethylene.

The content of low-density polyethylene in the resin layer (2) is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 18% by mass or less, and still more preferably 5% by mass or more and 15% by mass or less. . With such a configuration, for example, a metal deposition film having excellent glossiness (luminance) can be formed on the resin layer (2). The reason for this is not clear, but it is presumed that the resin layer (2) contains low-density polyethylene to improve the surface smoothness of the layer. By using a packaging material in which a metal deposition film is provided on the resin layer (2) of the heat-seal layer, a small bag having an excellent appearance such as metallic luster can be produced.

The content of the linear low-density polyethylene in the resin layer (2) is preferably 80% by mass or more and 99% by mass or less, more preferably 82% by mass or more and 97% by mass or less, and still more preferably 85% by mass or more and 95% by mass. It is below. With such a configuration, for example, the manufacturability of the heat seal layer can be improved, and the recyclability of the laminate can be improved.

The resin layer (2) may contain one or more resin materials other than polyethylene. Examples of the resin material include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of recyclability of the laminate, it is particularly preferable that the resin layer (2) does not contain any resin material other than polyethylene.

The resin layer (2) may contain one or more additives. Examples of additives include cross-linking agents, anti-blocking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins. is mentioned.

The density of the resin layer (2) is preferably over 0.900 g/cm ³ and 0.930 g/cm ³ or less, more preferably 0.905 g/cm ³ or more and 0.928 g/cm ³ or less, still more preferably is 0.915 g/cm ³ or more and 0.926 g/cm ³ or less. With such a configuration, for example, the symmetry of the density in the layer direction of the heat-sealing layer is increased, and the occurrence of curling in the heat-sealing layer can be suppressed.

The ratio of the thickness of the resin layer (2) to the total thickness of the heat seal layer is preferably 2% or more and 30% or less, more preferably 5% or more and 25% or less, and still more preferably 10% or more and 25% or less. .

A surface treatment may be applied to the surface of the resin layer (2). With such a configuration, for example, the adhesion between the resin layer (2) and the metal deposition film can be improved. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen gas and nitrogen gas, glow discharge treatment; and oxidation treatment using chemicals. Chemical treatment can be mentioned.

(middle layer)
Preferably, the heat seal layer further comprises an intermediate layer containing polyethylene between the resin layer (1) and the resin layer (2). The number of layers of the intermediate layer may be one layer, two layers or more, and may be, for example, three layers or more and five layers or less.

The intermediate layer can contain one or more polyethylenes.
Details of the polyethylene are as described above.
The content of polyethylene in the intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The heat-sealing layer preferably further comprises a layer containing polyethylene and having a density of more than 0.920 g/cm ³ (hereinafter also referred to as "intermediate layer (a)") as an intermediate layer. With such a configuration, for example, excellent rigidity can be imparted to the heat seal layer.

The density of the intermediate layer (a) is greater than 0.920 g/cm ³ , preferably 0.925 g/cm ³ or more and 0.965 g/cm ³ or less, more preferably 0.930 g/cm ³ or more and 0.960 g/cm 3 or more. cm ³ or less. The density of the intermediate layer (a) is preferably higher than that of the resin layer (2). With such a configuration, for example, excellent rigidity can be imparted to the heat seal layer.

The intermediate layer (a), in one embodiment, contains at least one selected from high density polyethylene and medium density polyethylene. The total content of high-density polyethylene and medium-density polyethylene in the intermediate layer (a) is preferably 70% by mass or more, more preferably 75% by mass or more, and still more preferably 80% by mass or more. With such a configuration, for example, excellent rigidity can be imparted to the heat seal layer.

The intermediate layer (a) contains high density polyethylene in one embodiment. With such a configuration, for example, excellent rigidity can be imparted to the heat seal layer. A heat-sealing layer having such an intermediate layer is suitable, for example, as a heat-sealing layer for small bags.

The intermediate layer (a), in one embodiment, contains high density polyethylene and medium density polyethylene. The mass ratio of high-density polyethylene to medium-density polyethylene (high-density polyethylene/medium-density polyethylene) in the intermediate layer (a) is, for example, 0.3 or more and 5.0 or less, preferably 1.0 or more and 3.0 or less, It is more preferably 1.3 or more and 2.6 or less.

The intermediate layer (a), in one embodiment, further contains low density polyethylene. With such a configuration, for example, the film formability and cuttability of the heat seal layer can be improved.

The content of the low-density polyethylene in the intermediate layer (a) is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, and still more preferably 5% by mass or more and 20% by mass or less. . With such a configuration, for example, the film formability and cuttability of the heat seal layer can be improved.

The intermediate layer may contain one or more resin materials other than polyethylene. Examples of the resin material include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of recyclability of the laminate, it is particularly preferable that the intermediate layer does not contain any resin material other than polyethylene.

The intermediate layer may contain one or more additives. Examples of additives include cross-linking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins.

The ratio of the thickness of the intermediate layer to the total thickness of the heat seal layer is preferably 40% or more and 96% or less, more preferably 50% or more and 90% or less, still more preferably 50% or more and 80% or less.

Since the laminate has the effects described above, it can be suitably used as a packaging material for producing a small bag, and in particular, can be suitably used as a packaging material for producing a mono-material small bag.

<Metal deposition film>
In one embodiment, the laminate includes a metal deposition film provided on the resin layer (2) of the heat seal layer. More specifically, the vapor-deposited metal film is provided on the surface of the resin layer (2) opposite to the surface of the resin layer (1). In the following description, the heat-sealing layer on which the metal deposition film is formed is also referred to as "deposition heat-sealing layer". With such a configuration, for example, it is possible to impart an excellent glossiness to the packaging material and improve the gas barrier properties of the packaging material, specifically, the oxygen barrier properties and the water vapor barrier properties. Moreover, by providing a metal deposition film, the light-shielding property and fragrance-retaining property of the packaging material can be improved.

Metal deposition films are composed of metals such as aluminum, chromium, tin, nickel, copper, silver, gold and platinum. Among these, an aluminum deposition film is preferable.

The thickness of the metal deposition film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and still more preferably 10 nm or more and 40 nm or less. By setting the thickness of the vapor-deposited metal film to 1 nm or more, for example, it is possible to improve the feeling of metallic luster, light-shielding properties, and aroma-retaining properties of the packaging material. By setting the thickness of the vapor-deposited metal film to 150 nm or less, for example, the generation of cracks in the vapor-deposited metal film can be suppressed, and the recyclability of the packaging material can be improved.
The details of the method for forming the metal deposition film will be described later.

The surface of the vapor-deposited metal film may be subjected to the surface treatment described above. With such a configuration, for example, the adhesion between the metal vapor deposition film and the layer adjacent to the metal vapor deposition film can be improved.

<Base material>
The substrate is composed of polyethylene. The resin material constituting the base material is polyethylene, which is the same type of resin material as the resin material constituting the heat seal layer, so that the laminate having such a configuration can be used as a laminate for producing a monomaterial packaging container. It can be suitably used as a body.

Polyethylene includes, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene and ultra low density polyethylene. High-density polyethylene and medium-density polyethylene are preferred from the viewpoint of the strength and heat resistance of the substrate, and medium-density polyethylene is preferred from the viewpoint of stretchability.

The substrate can contain one or more polyethylenes.
Details of the polyethylene are as described above.
The polyethylene content in the substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The content of polyethylene in each layer constituting the substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The substrate may contain one or more resin materials other than polyethylene. Examples of the resin material include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of recyclability, it is particularly preferable that the base material does not contain resin materials other than polyethylene.

The substrate may contain one or more additives. Examples of additives include cross-linking agents, anti-blocking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins. is mentioned. When the substrate is the following multilayer substrate, each layer constituting the multilayer substrate can independently contain the additive.

At least one layer selected from the layers constituting the multilayer substrate may contain a slip agent. Thereby, for example, the workability of the multilayer base material can be improved. For example, in the stretched multilayer base material of the fifth embodiment described later, the third layer may contain a slip agent, and all of the first to fifth layers may contain a slip agent.

Slip agents include, for example, amide lubricants, fatty acid esters such as glycerin fatty acid esters, hydrocarbon waxes, higher fatty acid waxes, metallic soaps, hydrophilic silicones, silicone-modified (meth)acrylic resins, silicone-modified epoxy resins, and silicones. modified polyethers, silicone-modified polyesters, block-type silicone (meth)acrylic copolymers, polyglycerol-modified silicones and paraffins. Among slip agents, amide-based lubricants are preferred. Examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides and aromatic bisamides. Among these, unsaturated fatty acid amides are preferred, and erucic acid amides are more preferred.

In the multilayer base material, the content of the slip agent in the layer containing the slip agent may be, for example, 0.01% by mass or more and 3% by mass or less, or may be 0.03% by mass or more and 1% by mass or less. Thereby, the workability of the multilayer base material can be further improved.

The substrate may have a single layer structure or a multilayer structure. Hereinafter, a base material having a multilayer structure is also referred to as a "multilayer base material". A multilayer base material is preferable from the viewpoint that its strength, heat resistance and stretchability can be improved.

In the multilayer base material, the density of polyethylene constituting each layer may be the same or different. For example, a multilayer substrate may have a gradient in the density of each layer (density gradient). By providing a density gradient in the multilayer base material, for example, its strength, heat resistance and stretchability can be improved.

In a multilayer substrate having a density gradient, it is preferred that the absolute value of the density difference between any two adjacent layers is small. The absolute value of the density difference is preferably 0.040 g/cm ³ or less, more preferably 0.030 g/cm ³ or less, still more preferably 0.020 g/cm ³ or less. With such a configuration, for example, it is possible to effectively suppress the occurrence of delamination at the interface of each layer.

The substrate is preferably stretched, and hereinafter, such a substrate is also referred to as a “stretched substrate”. More preferably, the base material is a multi-layer base material that has been stretched. Hereinafter, such a substrate is also referred to as a "stretched multilayer substrate". The stretching treatment can improve the heat resistance and strength of the substrate, for example. Such a stretched base material, particularly a stretched multilayer base material, can satisfy the physical properties required for outer layers of packaging materials, for example.

The stretching may be uniaxial stretching or biaxial stretching. In one embodiment, the draw ratio in the longitudinal direction (MD) of the stretched base material is preferably 2 times or more and 10 times or less, more preferably 3 times or more and 7 times or less. In one embodiment, the draw ratio in the transverse direction (TD) of the stretched base material is preferably 2 times or more and 10 times or less, more preferably 3 times or more and 7 times or less.

When the draw ratio is 2 times or more, for example, the rigidity, strength and heat resistance of the substrate can be improved, the printability of the substrate can be improved, and the transparency of the substrate can be improved. If the draw ratio is 10 times or less, for example, the film can be stretched satisfactorily without causing breakage or the like.

The stretched substrate, in one embodiment, is a uniaxially stretched film, more specifically a uniaxially stretched film that has been stretched in the machine direction (MD).

A stretched multilayer substrate has a multilayer structure of two or more layers. In one embodiment, the number of layers of the stretched multilayer substrate is 2 or more and 7 or less, for example, 3 or more and 7 or less, or 3 or more and 5 or less. The number of layers of the stretched multilayer substrate is preferably an odd number, for example 3, 5 or 7 layers. When the stretched multilayer base material has a multilayer structure, the balance of rigidity, strength, heat resistance, printability and stretchability of the base material can be improved. Each layer of the stretched multilayer substrate is also preferably composed of polyethylene.

The difference (D3-D1) between the density D3 of the surface resin layer on the heat-seal layer side of the stretched multilayer substrate and the density D1 of the resin layer (1) on the heat-seal layer is, for example, 0.022 g/cm ³ or more and 0 0.025 g/cm ³ or more, or 0.030 g/cm ³ or more.

The haze value of the substrate such as a stretched multilayer substrate is preferably 25% or less, more preferably 15% or less, and even more preferably 10% or less. A smaller haze value is more preferable, but in one embodiment, the lower limit may be 0.1% or 1%. The haze value of the substrate is measured according to JIS K7136.

The thickness of the substrate such as the stretched multilayer substrate is preferably 10 μm or more and 60 μm or less, more preferably 15 μm or more and 50 μm or less. When the thickness of the substrate is 10 μm or more, the rigidity and strength of the laminate can be improved. When the thickness of the substrate is 60 μm or less, the workability of the laminate can be improved. In the range in which the above effects can be obtained, it is preferable from the viewpoint of cost reduction, for example, that the thickness of the multilayer base material is small.

A substrate such as a stretched multilayer substrate may be subjected to the surface treatment described above. Thereby, for example, the adhesion between the substrate and the layer laminated on the substrate can be improved. A conventionally known anchor coating agent may be used to form an anchor coat layer on the surface of a base material such as a stretched multilayer base material.

A stretched multilayer base material can be produced, for example, by film-forming a plurality of resin materials or resin compositions by an inflation method or a T-die method to form a laminate, and stretching the obtained laminate. The stretching treatment can improve the transparency, rigidity, strength and heat resistance of the base material, and the base material can be suitably used as, for example, a base material for packaging materials.

In one embodiment, the stretched multilayer substrate is obtained by stretching a laminate (precursor) having a multilayer structure. Specifically, the resin materials constituting each layer can be co-extruded into a tubular shape to form a film, thereby producing a laminate. Alternatively, a laminate can be produced by co-extrusion of the resin materials constituting each layer into a tubular shape, and then pressing the opposing layers together with a rubber roll or the like. By manufacturing a laminate by such a method, the number of defective products can be significantly reduced, and production efficiency can be improved.

For example, when the stretched multilayer base material is made of polyethylene and the multilayer base material is produced by the T-die method, the melt flow rate (MFR) of the polyethylene constituting each layer of the multilayer base material depends on the film formability, And from the viewpoint of processability of the multilayer base material, it is preferably 3 g/10 minutes or more and 20 g/10 minutes or less.

For example, when the stretched multilayer base material is made of polyethylene and the multilayer base material is produced by the inflation method, the MFR of the polyethylene constituting each layer of the multilayer base material depends on the film formability and the processing of the multilayer base material. From the viewpoint of suitability, it is preferably 0.2 g/10 minutes or more and 5 g/10 minutes or less.

A stretched multilayer base material is obtained, for example, by stretching the laminate described above. Preferred draw ratios are as described above. In addition, in the inflation film forming machine, the laminate can also be stretched. As a result, a stretched multilayer base material can be produced, and production efficiency can be further improved.

Several examples of embodiments of the stretched multilayer substrate are described below. Hereinafter, a layer having a polyethylene content of 80% by mass or more is referred to as a "polyethylene layer". For example, a layer containing 80% by mass or more of high-density polyethylene is referred to as a "high-density polyethylene layer".

The stretched multilayer substrate of the first embodiment includes a medium density polyethylene layer, a high density polyethylene layer, a blend layer of medium density polyethylene and high density polyethylene, a high density polyethylene layer, and a medium density polyethylene layer. Prepare in this order in the vertical direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

In the blend layer of medium density polyethylene and high density polyethylene, the mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4. 2.4 or less.

The stretched multilayer substrate of the second embodiment includes a medium density polyethylene layer, a medium density polyethylene layer, a blend layer of medium density polyethylene and linear low density polyethylene, a medium density polyethylene layer, and a medium density polyethylene layer. are provided in this order in the thickness direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

In the blend layer of medium density polyethylene and linear low density polyethylene, the mass ratio of medium density polyethylene to linear low density polyethylene (medium density polyethylene/linear low density polyethylene) is preferably 0.25 or more. 4 or less, more preferably 0.4 or more and 2.4 or less.

The stretched multi-layer substrate of the third embodiment includes a blend layer of medium density polyethylene and high density polyethylene, a blend layer of medium density polyethylene and linear low density polyethylene, a linear low density polyethylene layer, and a medium density A blend layer of polyethylene and linear low density polyethylene and a blend layer of medium density polyethylene and high density polyethylene are provided in this order in the thickness direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

In the blend layer of medium density polyethylene and high density polyethylene, the mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) is independently preferably 0.25 or more and 4 or less, more preferably is 0.4 or more and 2.4 or less.

In the blend layer of medium density polyethylene and linear low density polyethylene, the mass ratio of medium density polyethylene to linear low density polyethylene (medium density polyethylene/linear low density polyethylene) is preferably 0.25 or more. 4 or less, more preferably 0.4 or more and 2.4 or less.

The stretched multilayer substrate of the fourth embodiment includes a blend layer of high-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, a blend layer of linear low-density polyethylene and medium-density polyethylene, and a medium-density polyethylene layer. , a blend layer of high density polyethylene and medium density polyethylene in this order in the thickness direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

The mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) in the blend layer of high density polyethylene and medium density polyethylene is independently preferably 0.25 or more and 4 or less, more preferably is 0.4 or more and 2.4 or less.

The mass ratio of linear low density polyethylene to medium density polyethylene (linear low density polyethylene/medium density polyethylene) in the blend layer of linear low density polyethylene and medium density polyethylene is preferably 0.25 or more. Below, it is more preferably 0.4 or more and 2.4 or less.

The stretched multilayer substrate of the fifth embodiment comprises a first layer containing medium density polyethylene and high density polyethylene, a second layer containing high density polyethylene, and a second layer containing linear low density polyethylene. 3 layers, a fourth layer containing high density polyethylene, and a fifth layer containing medium density polyethylene and high density polyethylene are provided in this order in the thickness direction.

When printing an image on a base material, the base material may be subjected to surface treatment such as corona discharge treatment as a pretreatment. A layer containing medium-density polyethylene tends to have higher durability to surface treatment than a layer containing only high-density polyethylene as polyethylene. Therefore, the layer containing medium-density polyethylene has excellent ink adhesion during printing after surface treatment. Layers containing medium density polyethylene and high density polyethylene also have the necessary heat resistance during printing and heat sealing. In addition, the layer containing medium-density polyethylene contributes to improving the stretchability of the laminate, which is the precursor of the multilayer base material.

The mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) in the first layer and the fifth layer is preferably 1.1 or more and 5 or less, more preferably 1. 0.5 or more and 3 or less. This can further improve the balance between ink adhesion and heat resistance.

The total content of medium-density polyethylene and high-density polyethylene in the first layer and the fifth layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. is. This can further improve the ink adhesion and heat resistance of the substrate.

The second layer and the fourth layer each contribute to improving the heat resistance of the substrate. That is, the heat resistance of the substrate can be further improved by including high-density polyethylene in the second layer and the fourth layer in addition to the first layer and the fifth layer.

The second layer and the fourth layer may each independently further contain low density polyethylene. As a result, the balance of heat resistance, rigidity and workability of the base material can be further improved.

The mass ratio of high-density polyethylene to low-density polyethylene (high-density polyethylene/low-density polyethylene) in the second layer and the fourth layer is preferably 1 or more and 4 or less, more preferably 1.5. 3 or less. As a result, the balance of heat resistance, rigidity and workability of the base material can be further improved.

The content of high-density polyethylene in the second layer and the fourth layer is preferably more than 50% by mass, more preferably 55% by mass or more, and still more preferably 60% by mass or more. Thereby, the heat resistance of the substrate can be further improved.

The total content of high-density polyethylene and low-density polyethylene in the second layer and the fourth layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. is. As a result, the balance of heat resistance, rigidity and workability of the base material can be further improved.

The thickness of each of the second layer and the fourth layer is preferably 0.5 μm or more and 15 μm or less, more preferably 1 μm or more and 10 μm or less, and still more preferably 1 μm or more and 8 μm or less. Thereby, the heat resistance of the substrate can be further improved.

The third layer contributes to improving the stretchability of the laminate, which is the precursor of the multilayer substrate.
The third layer may further contain low density polyethylene.

The content of linear low-density polyethylene in the third layer is preferably more than 50% by mass, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, 90% by mass % or more, or 95% by mass or more. This can further improve the balance between heat resistance, rigidity and stretchability.

When the third layer contains low-density polyethylene, the content of low-density polyethylene is preferably less than 50% by mass, more preferably 5% to 40% by mass, and still more preferably 10% to 30% by mass. It is below.

The thickness of the third layer is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm or less, and still more preferably 5 μm or more and 30 μm or less. This can further improve the balance between heat resistance, rigidity and stretchability.

The ratio of the total thickness of the second layer and the fourth layer to the thickness of the third layer (total thickness of the second layer and the fourth layer/thickness of the third layer) is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 5 or less, and still more preferably 0.5 or more and 2 or less. Thereby, the rigidity, strength and heat resistance of the substrate can be further improved.

In the stretched multilayer substrates of the first to fifth embodiments, the thickness of each of the two surface resin layers is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 8 μm or less, and even more preferably. is 1 μm or more and 5 μm or less. Thereby, for example, the heat resistance and printability of the substrate can be further improved. For the stretched multilayer substrate of the fifth embodiment, the two surface resin layers are the first layer and the fifth layer in one embodiment.

In the stretched multilayer substrates of the first to fifth embodiments, the thickness of each of the two surface resin layers is preferably smaller than the total thickness of the inner three layers (multilayer intermediate layer). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layer (surface resin layer/multilayer intermediate layer) is preferably from 0.05 to 0.8, more preferably from 0.1 to 0. 0.7 or less, more preferably 0.1 or more and 0.4 or less. Thereby, for example, the rigidity, strength and heat resistance of the substrate can be further improved. For the stretched multilayer substrate of the fifth embodiment, the multilayer interlayers are the second through fourth layers in one embodiment.

The stretched multilayer substrate of the sixth embodiment comprises a high-density polyethylene layer and a medium-density polyethylene layer in this order in the thickness direction. By using a high-density polyethylene layer as the surface resin layer of the substrate, for example, the strength and heat resistance of the substrate can be improved. By including the medium-density polyethylene layer in the base material, for example, the stretching aptitude of the pre-stretching laminate can be improved.

The stretched multilayer base material of the seventh embodiment comprises a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction. With such a configuration, for example, the strength and heat resistance of the base material can be improved, the occurrence of curling in the base material can be suppressed, and the stretching aptitude of the unstretched laminate can be improved.

In the stretched multilayer substrates of the sixth and seventh embodiments, the thickness of the high-density polyethylene layer is preferably equal to or less than the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

The stretched multilayer substrate of the eighth embodiment includes a high density polyethylene layer, a medium density polyethylene layer, a low density polyethylene layer, a linear low density polyethylene layer or an ultra low density polyethylene layer (for simplicity of description, these The three layers are collectively described as "a low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer are provided in this order in the thickness direction. With such a configuration, for example, the stretching aptitude of the laminate before stretching can be improved, the strength and heat resistance of the substrate can be improved, and the occurrence of curling in the substrate can be suppressed.

In the stretched multilayer base material of the eighth embodiment, the thickness of the high-density polyethylene layer is preferably equal to or less than the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

In the stretched multilayer base material of the eighth embodiment, the thickness of the high-density polyethylene layer is preferably equal to or greater than the thickness of the low-density polyethylene layer and the like. The ratio of the thickness of the high density polyethylene layer to the thickness of the low density polyethylene layer is preferably 1 or more and 4 or less, more preferably 1 or more and 2 or less.

As a stretched multilayer substrate of another embodiment, a high-density polyethylene layer, a high-density polyethylene layer, a blend layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and a high-density polyethylene are arranged in the thickness direction. A substrate provided in this order in the thickness direction; a medium density polyethylene layer, a high density polyethylene layer, a linear low density polyethylene layer, a high density polyethylene layer, and a medium density polyethylene layer in this order in the thickness direction is also mentioned.

In addition, a high-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, a low-density polyethylene layer, etc., a blend layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer are arranged in the thickness direction. Substrates provided in this order are also included.

<Barrier layer>
The laminate, in one embodiment, comprises a barrier layer between the substrate and the heat-sealing layer or vapor-deposited heat-sealing layer. Thereby, for example, the gas barrier property of the laminate, specifically, the oxygen barrier property and the water vapor barrier property can be improved.

A barrier layer is formed on the surface of a base material, for example.
A barrier layer may be provided between the substrate and the heat-seal layer or vapor-deposited heat-seal layer via an adhesive or the like. For example, a barrier film comprising a second base material and a barrier layer formed on the second base material is placed between the base material and the heat-sealing layer or vapor-deposited heat-sealing layer via an adhesive or the like. may be provided. In this aspect, from the viewpoint of recyclability, the second substrate in the barrier film is preferably made of polyethylene, which is the same type of resin material as the resin material forming the substrate. The content of polyethylene in the second substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Thereby, the recyclability of the laminate can be improved.

In one embodiment, the barrier layer is a deposited film. Deposited films include, for example, metals such as aluminum, chromium, tin, nickel, copper, silver, gold, and platinum; or aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, and hafnium oxide. and inorganic oxides such as barium oxide. Among these, an aluminum vapor deposition film, an aluminum oxide (alumina) vapor deposition film, or a silicon oxide (silica) vapor deposition film is preferable.

The thickness of the deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and still more preferably 10 nm or more and 40 nm or less. By setting the thickness of the deposited film to 1 nm or more, for example, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. By setting the thickness of the deposited film to 150 nm or less, for example, it is possible to suppress the occurrence of cracks in the deposited film and improve the recyclability of the laminate.

Examples of methods for forming a deposited film include physical vapor deposition (PVD) such as vacuum deposition, sputtering and ion plating; plasma chemical vapor deposition, thermal chemical vapor deposition and photochemical vapor deposition. A chemical vapor deposition method (CVD method) such as a phase growth method can be used. The deposited film may be a composite film including two or more layers of deposited films of different kinds of inorganic oxides, which is formed using both physical vapor deposition and chemical vapor deposition.

The degree of vacuum in the vapor deposition chamber is preferably about 10 ^-2 to 10 ^-8 mbar before introducing oxygen, and about 10 ^-1 to 10 ^-6 mbar after introducing oxygen. The amount of oxygen to be introduced varies depending on the size of the vapor deposition machine. Inert gases such as argon gas, helium gas and nitrogen gas may be used as a carrier gas for oxygen to be introduced as long as there is no problem. The conveying speed of the target film on which the vapor deposition film is formed is, for example, 10 m/min or more and 800 m/min or less.

The surface of the deposited film may be subjected to the surface treatment described above. Thereby, for example, the adhesion between the deposited film and the layer adjacent to the deposited film can be improved.

For example, when the deposited film is composed of inorganic oxides such as aluminum oxide and silicon oxide, a barrier coat layer may be provided on the surface of the deposited film. In this case, the barrier layer comprises a deposited film and a barrier coat layer. In one embodiment, the laminate includes a substrate, a vapor deposition film, a barrier coat layer, and a heat seal layer or a vapor deposition heat seal layer in this order in the thickness direction. With such a configuration, for example, the gas barrier properties of the laminate can be improved, and the occurrence of cracks in the deposited film can be effectively suppressed.

In one embodiment, the barrier coat layer is composed of a gas barrier resin. Gas barrier resins include, for example, ethylene-vinyl alcohol copolymer; polyvinyl alcohol; polyacrylonitrile; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as; polyurethanes; and polyvinylidene chloride.

The content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. With such a configuration, for example, the gas barrier properties of the barrier coat layer can be improved.

The thickness of the barrier coat layer is preferably 0.01 μm or more and 10 μm or less, more preferably 0.1 μm or more and 5 μm or less. By setting the thickness of the barrier coat layer to 0.01 μm or more, for example, gas barrier properties can be further improved.

The barrier coat layer can be formed by, for example, dissolving or dispersing a material such as a gas barrier resin in water or a suitable organic solvent, applying the obtained coating liquid, and drying.

In another embodiment, the barrier coat layer has gas barrier properties obtained by mixing an alkoxide, a water-soluble polymer, and optionally a silane coupling agent, and adding water, an organic solvent, and a sol-gel catalyst. It is a gas-barrier coating layer formed by coating the composition on a deposited film and drying it. The gas barrier coating layer contains a hydrolyzed polycondensate obtained by hydrolyzing and polycondensing the alkoxide or the like by a sol-gel method. Each of the above components can be used alone or in combination of two or more.

An alkoxide is represented by Formula (1), for example.
^{R1nM (} _OR2 ) _m (1)
In formula (1), R ¹ and R ² each independently represent an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, and m is an integer of 1 or more. and n+m represents the valence of M.

Examples of organic groups for R ¹ and R ² include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, n-hexyl group and Examples thereof include alkyl groups having 1 to 8 carbon atoms such as n-octyl group.
Metal atoms M are, for example, silicon, zirconium, titanium or aluminum.

Examples of the alkoxide represented by formula (1) include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane.

Examples of water-soluble polymers include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Either one of polyvinyl alcohol and ethylene-vinyl alcohol copolymer may be used, or both may be used in combination, depending on desired physical properties such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance. Alternatively, a gas barrier coating layer obtained using polyvinyl alcohol and a gas barrier coating layer obtained using an ethylene-vinyl alcohol copolymer may be laminated. The amount of the water-soluble polymer used is preferably 5 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the alkoxide represented by formula (1).

As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used, and organoalkoxysilanes having an epoxy group are preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propylmethyldiethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are included. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the alkoxide represented by formula (1).

Examples of organic solvents used for preparing gas barrier compositions include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol and n-butyl alcohol.

As the sol-gel process catalyst, an acid or amine compound is preferable.
Acids include, for example, mineral acids such as sulfuric acid, hydrochloric acid and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of acid used is preferably 0.001 mol or more and 0.05 mol or less per 1 mol of the total molar amount of the alkoxide represented by formula (1) and the silane coupling agent.

Amine compounds include, for example, N,N-dimethylbenzylamine, tripropylamine, tributylamine and tripentylamine. The amount of the amine compound used is preferably 0.01 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the total amount of the alkoxide represented by formula (1) and the silane coupling agent.

Examples of the method of applying the gas barrier composition include application means such as roll coating such as gravure roll coater, spray coating, spin coating, dipping, brush, bar coating and applicator.

An embodiment of the method for forming the gas barrier coating layer will be described below.
A gas barrier composition is prepared by mixing an alkoxide, a water-soluble polymer, a sol-gel process catalyst, water, an organic solvent, and optionally a silane coupling agent. A polycondensation reaction proceeds gradually in the composition. The above composition is applied onto the deposited film by a conventional method and dried. This drying further promotes polycondensation of the alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains a silane coupling agent) to form a composite polymer layer. The above operation may be repeated to laminate a plurality of composite polymer layers. Finally, the composition is heated at a temperature of preferably 20° C. to 250° C., more preferably 50° C. to 220° C., for example 50° C. to 120° C., for 1 second to 10 minutes. Thereby, a gas barrier coating layer can be formed.

The thickness of the gas barrier coating layer formed from the gas barrier composition using an alkoxide is preferably 0.01 μm or more and 100 μm or less, more preferably 0.1 μm or more and 50 μm or less. Thereby, for example, the gas barrier property can be improved, and the occurrence of cracks in the deposited film can be suppressed.

<Print layer>
In one embodiment, the laminate further includes a printed layer formed on the substrate described above. In one embodiment, the laminate preferably has a printed layer on the heat-seal layer-side surface of the base material because it can suppress deterioration of the image over time. When the laminate has a barrier layer on the substrate, for example, a printed layer may be provided on the barrier layer. In this case, the laminate includes, for example, a substrate, a barrier layer, a printed layer, and a heat-sealing layer or vapor-deposited heat-sealing layer in this order in the thickness direction.

The print layer includes, for example, an image. Images include, for example, characters, graphics, symbols, and combinations thereof. Examples of methods for forming the printed layer include gravure printing, offset printing, and flexographic printing. In one embodiment, the flexographic printing method is preferred from the viewpoint of reducing environmental load. Moreover, from the viewpoint of reducing the environmental burden, a print layer may be formed on the surface of the substrate using ink derived from biomass.

<Adhesive layer>
In one embodiment, the laminate is between the substrate and the heat-sealing layer or the vapor-deposited heat-sealing layer, between the substrate and the barrier film, between the barrier film and the heat-sealing layer or the vapor-depositing heat-sealing layer, and the like. An adhesive layer is provided between any layers of This makes it possible to improve the adhesion between the substrate and the heat-seal layer or vapor-deposited heat-seal layer and the adhesion between other layers.

For example, the laminate can be produced by laminating the base material described above and a sealant film corresponding to the heat-sealing layer, or a vapor-deposited film including the heat-sealing layer and the vapor-deposited metal film via an adhesive layer.

The adhesive layer contains one or more adhesives. Examples of adhesives include one-component curing adhesives, two-component curing adhesives, and non-curing adhesives.

The adhesive may be a solvent-free adhesive or a solvent-based adhesive. Examples of adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, urethane-based adhesives, rubber-based adhesives, vinyl-based adhesives, phenol-based adhesives, and olefin-based adhesives. Adhesives are included. Among these, a two-liquid curing type urethane-based adhesive is preferable.

The adhesive layer may contain one or more additives. Additives include, for example, pigments, dyes, lubricants, colorants, wetting agents, thickeners, coagulants, gelling agents, anti-settling agents, softeners, hardening agents, plasticizers, leveling agents, antioxidants, UV absorbers, light stabilizers and flame retardants are included.

The thickness of the adhesive layer is preferably 0.5 μm or more and 6 μm or less, more preferably 0.8 μm or more and 5 μm or less, and still more preferably 1 μm or more and 4.5 μm or less. When the thickness of the adhesive layer is at least the lower limit, for example, the adhesion between layers can be improved. When the thickness of the adhesive layer is equal to or less than the upper limit, for example, it is possible to improve the recyclability of the sachets produced using the laminate.

The adhesive layer is formed by, for example, direct gravure roll coating method, gravure roll coating method, kiss coating method, reverse roll coating method, fonten method and transfer roll coating method. It can be formed by drying.

In one embodiment of the above laminate, the stretched multilayer base material satisfies the rigidity, strength and heat resistance required as the outer layer of the pouch, and the heat seal layer enables packaging at low temperatures. Further, the stretched multilayer substrate and the heat seal layer are each composed of polyethylene. Therefore, the laminate is suitable as a packaging material that requires recyclability.

[Sachet]
The sachet of the present disclosure comprises the laminate and is at least partially composed of the laminate. In the pouch of the present disclosure, the resin layer (1) is positioned as the innermost layer of the pouch. A sachet is a small packaging bag, and is used to contain, for example, 1 g or more and 200 g or less of contents.

Methods of heat sealing include, for example, bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing and ultrasonic sealing.

Examples of small bags include side seal type, two side seal type, three side seal type, four side seal type, envelope seal type, palm seal type (pillow seal type), pleated seal type, flat bottom seal type, and square bottom seal type. There are various forms of packaging bags such as mold and gusset type.

The sachet may have an easy-open portion. The easy-to-open portion includes, for example, a notch portion that serves as a starting point for tearing the small bag, and a half-cut line formed by laser processing, a cutter, or the like as a path for tearing the small bag.

In one embodiment, the laminate can be folded in two so that the base material is positioned outside and the heat-seal layer is positioned inside, and the edges and the like are heat-sealed to produce a small bag. In another embodiment, a small bag can be produced by stacking a plurality of the laminates so that the heat-seal layers face each other, and heat-sealing the edges and the like. The entire pouch may be composed of the laminate, or a portion of the pouch may be composed of the laminate.

Contents contained in the sachet include, for example, liquids, solids, powders and gels. The contents may be food or drink, or may be non-food or drink such as chemicals, cosmetics, and pharmaceuticals. After the contents are placed in the pouch, the pouch can be sealed by heat sealing the opening of the pouch.

Specific contents contained in the sachet include sauces, soy sauce, dressings, ketchup, syrups, cooking liquors, other liquid or viscous seasonings; liquid soups, powdered soups, fruit juices; Spices; liquid beverages, jelly-like beverages, instant foods, and other foods and drinks.

The present disclosure relates to, for example, the following [1] to [18].
[1] A pouch at least partially composed of a laminate comprising a base material made of polyethylene and a heat-sealing layer, wherein the heat-sealing layer is a polyethylene resin having a density of 0.920 g/cm ³ or less. A sachet comprising a layer (1) and a resin layer (2) containing linear low density polyethylene and low density polyethylene, wherein the polyethylene resin layer (1) is located in the innermost layer of the sachet.
[2] The content of linear low-density polyethylene in the resin layer (2) is 80% by mass or more and 99% by mass or less, and the content of low-density polyethylene is 1% by mass or more and 20% by mass or less. The pouch according to [1] above.
[3] [1] or [ 2].
[4] The pouch according to any one of [1] to [3] above, wherein the resin layer (1) further contains an antiblocking agent.
[5] Any of the above [1] to [4], wherein the difference (D2-D1) between the density D2 of the resin layer (2) and the density D1 of the resin layer (1) is 0.020 g/cm ³ or less. A sachet as described in any of the above.
[6] The above [1]-, wherein the heat seal layer further comprises an intermediate layer containing polyethylene and having a density of more than 0.920 g/cm ³ between the resin layer (1) and the resin layer (2). The pouch according to any one of [5].
[7] The pouch according to [6] above, wherein the intermediate layer contains at least one selected from high-density polyethylene and medium-density polyethylene.
[8] The pouch according to [7] above, wherein the total content of high-density polyethylene and medium-density polyethylene in the intermediate layer is 70% by mass or more.
[9] The pouch according to [7] or [8] above, wherein the intermediate layer further contains low-density polyethylene, and the content of low-density polyethylene in the intermediate layer is 1% by mass or more and 30% by mass or less.
[10] The pouch according to any one of [1] to [9] above, wherein the absolute value of the density difference between any two adjacent layers in the heat seal layer is 0.040 g/cm ³ or less.
[11] The pouch according to any one of [1] to [10] above, wherein the heat seal layer is an unstretched film.
[12] The pouch according to any one of [1] to [11] above, wherein each layer constituting the heat seal layer is a coextruded resin layer.
[13] The pouch according to any one of [1] to [12] above, wherein the content of polyethylene in the entire heat seal layer is 90% by mass or more.
[14] The pouch according to any one of [1] to [13] above, wherein the substrate is a stretched substrate.
[15] The pouch according to any one of [1] to [14] above, wherein the substrate is a stretched multilayer substrate.
[16] The difference (D3-D1) between the density D3 of the surface resin layer on the heat-seal layer side of the stretched multilayer substrate and the density D1 of the resin layer (1) in the heat-seal layer is 0.022 g/cm ³ or more. The pouch according to [15] above.
[17] The pouch according to any one of [1] to [16] above, further comprising a metal deposition film on the resin layer (2).
[18] The pouch according to any one of [1] to [17] above, wherein the laminate further comprises a printed layer on the substrate.

The pouch of the present disclosure will be described in more detail based on examples, but the pouch of the present disclosure is not limited by the examples. Hereinafter, "mass part" is simply described as "part".

In the following description, high density polyethylene is also referred to as "HDPE", medium density polyethylene as "MDPE", low density polyethylene as "LDPE", and linear low density polyethylene as "LLDPE".

[Preparation of base material]
The polyethylene used in making the substrate is described.
・Medium density polyethylene:
Product name: Elite 5538G (hereinafter also referred to as “MDPE (1)”)
Density: 0.941 g/cm ³ Melting point: 129°C MFR: 1.3 g/10 minutes
Medium density polyethylene manufactured by Dowchemical:
Product name: Enable4002MC (hereinafter also referred to as “MDPE (2)”)
Density: 0.940 g/cm ³ Melting point: 128°C MFR: 0.25 g/10 minutes
High-density polyethylene manufactured by ExxonMobil:
Product name: Elite 5960G (hereinafter also referred to as “HDPE (1)”)
Density: 0.960 g/cm ³ Melting point: 134°C MFR: 0.8 g/10 minutes
High-density polyethylene manufactured by Dowchemical:
Product name: H619F (hereinafter also referred to as “HDPE (2)”)
Density: 0.965 g/cm ³ Melting point: 135°C MFR: 0.7 g/10 minutes
Linear low-density polyethylene manufactured by SCG:
Product name: Elite 5400G (hereinafter also referred to as “LLDPE (1)”)
Density: 0.916 g/cm ³ Melting point: 123° C. MFR: 1.3 g/10 minutes
Linear low-density polyethylene manufactured by Dowchemical:
Product name: Exceed XP8656ML (hereinafter also referred to as “LLDPE (2)”)
Density: 0.916 g/cm ³ Melting point: 121°C MFR: 0.5 g/10 minutes
Low-density polyethylene manufactured by ExxonMobil:
Product name: LD2420F (hereinafter also referred to as “LDPE (1)”)
Density: 0.922 g/cm ³ Melting point: 112°C MFR: 0.75 g/10 minutes
MB containing slip agent manufactured by PTT:
Product name: SLIP61 10061-K
Density: 0.910 g/cm ³ , MFR: 10 g/10 minutes,
Polyethylene base, containing 5% by mass of erucamide-based slip agent,
Made by Ampacet

・Blended polyethylene (A)
50 parts of MDPE (1) and 50 parts of HDPE (1) were kneaded to obtain a blended polyethylene (hereinafter also referred to as "blended PE (A)") having a density of 0.951 g/cm ³ .

・Blended polyethylene (B)
50 parts of MDPE (1) and 50 parts of LLDPE (1) were kneaded to obtain a blended polyethylene (hereinafter also referred to as "blended PE (B)") having a density of 0.929 g/cm ³ .

・Blended polyethylene (B1)
70 parts of MDPE (1) and 30 parts of LLDPE (1) were kneaded to obtain a blended polyethylene (hereinafter also referred to as “blended PE (B1)”) having a density of 0.934 g/cm ³ .

・Blend polyethylene (C)
70 parts of MDPE (1) and 30 parts of HDPE (1) were mixed to obtain a blended polyethylene (hereinafter also referred to as "blended PE (C)") having a density of 0.947 g/cm ³ .

・Blended polyethylene (D)
30 parts of MDPE (1) and 70 parts of HDPE (1) were mixed to obtain a blended polyethylene (hereinafter also referred to as "blended PE (D)") having a density of 0.954 g/cm ³ .

・Blended polyethylene (A1)
70 parts of MDPE (2) and 30 parts of HDPE (1) were mixed to obtain a blended polyethylene (hereinafter also referred to as “blended PE (A1)”) having a density of 0.948 g/cm ³ .
・Blended polyethylene (B2)
70 parts of HDPE (2) and 30 parts of LDPE (1) were mixed to obtain a blended polyethylene (hereinafter also referred to as "blended PE (B2)") having a density of 0.950 g/cm ³ .
・Blended polyethylene (C1)
98 parts of LLDPE (2) and 2 parts of slip agent-containing MB were mixed to obtain a blended polyethylene (hereinafter also referred to as "blended PE (C1)") having a density of 0.916 g/cm ³ .

・Blended polyethylene (A2)
69 parts of MDPE (2), 30 parts of HDPE (1), and 1 part of MB containing a slip agent were mixed to form a blended polyethylene having a density of 0.948 g/cm ³ (hereinafter "blended PE (A2)" ) was obtained.
・Blended polyethylene (B3)
69 parts of HDPE (2), 30 parts of LDPE (1), and 1 part of MB containing a slip agent were mixed to form a blended polyethylene having a density of 0.949 g/cm ³ (hereinafter "blend PE (B3)" ) was obtained.
・Blended polyethylene (C2)
99 parts of LLDPE (2) and 1 part of slip agent-containing MB were mixed to obtain a blended polyethylene (hereinafter also referred to as “blended PE (C2)”) having a density of 0.916 g/cm ³ .

・Blended polyethylene (C3)
68 parts of LLDPE (2), 30 parts of LDPE (1), and 2 parts of MB containing a slip agent were mixed to form a blended polyethylene having a density of 0.918 g/cm ³ (hereinafter "blended PE (C3)" ) was obtained.

[Production Example 1]
MDPE (1), HDPE (1) and blended PE (A) were formed into MDPE (1) layer (15 μm)/HDPE (1) layer (22.5 μm)/blended PE (A) layer (50 μm) by inflation molding. )/HDPE (1) layer (22.5 μm)/MDPE (1) layer (15 μm) layer thickness ratio, 5-layer co-extrusion film formation was carried out to obtain a polyethylene film with a total thickness of 125 μm. Numbers in parentheses indicate layer thicknesses.

The polyethylene film prepared above was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched multilayer substrate (1) having a thickness of 25 μm.

[Production Examples 2 to 8]
Stretched multilayer substrates (2) to (8) were obtained in the same manner as in Production Example 1, except that the layer structure of the stretched multilayer substrate was changed as shown in Tables 1 and 2. In Table 2, the slip agent-containing MB is simply described as "MB."

[Production Example 9]
Blend PE (A1), blend PE (B2) and blend PE (C1) were formed into a blend PE (A1) layer (12 μm)/blend PE (B2) layer (18 μm)/blend PE (C1) layer by inflation molding. Five layers were co-extruded at a layer thickness ratio of (40 μm)/blended PE (B2) layer (18 μm)/blended PE (A1) layer (12 μm) to obtain a polyethylene film with a total thickness of 100 μm. Numbers in parentheses indicate layer thicknesses.

The polyethylene film prepared above was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched multilayer substrate (9) having a thickness of 20 μm.

[Production Examples 10-11]
Stretched multilayer substrates (10) to (11) were obtained in the same manner as in Production Example 9, except that the layer structure of the stretched multilayer substrate was changed as shown in Table 2. In Table 2, the slip agent-containing MB is simply described as "MB."

[Haze evaluation]
The haze value of the stretched multilayer substrate prepared above was measured according to JIS K7136.

[Rigidity evaluation]
The stretched multilayer base material prepared above was cut into a test piece having a width of 10 mm, and the rigidity of the test piece was measured using a loop stiffness measurement tester (manufactured by Toyo Seiki Seisakusho, trade name: Loop Stiffness Tester). The loop length was 60 mm.

[Strength evaluation]
A dumbbell-shaped test piece with a width of 10 mm was cut out from the stretched multilayer substrate prepared above. Using a tensile tester (RTC-1310A manufactured by Orientec Co., Ltd.), the tensile strength of the dumbbell-shaped test piece in the MD direction was measured. The chuck-to-chuck distance was 10 mm, and the tensile speed was 300 mm/min.
[Printability evaluation]
An image was formed on the stretched multilayer substrate prepared above by gravure printing using an oil-based gravure ink (manufactured by DIC Graphics, trade name: Finart). The formed image was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
AA: Good dimensional stability during printing,
It was possible to form a good image free from rubbing, blurring, and the like.
BB: expansion and contraction of the film occurs during printing,
The formed image was rubbed and smudged.

[Example 1]
<Preparation of sealant film>
70 parts of LLDPE (density: 0.916 g/cm ³ , melting point: 123° C., MFR: 1.3 g/10 min, manufactured by Dowchemical, trade name: Elite 5400G);
25 parts of LLDPE (density: 0.908 g/cm ³ , melting point: 106° C., MFR: 0.85 g/10 min, manufactured by Dowchemical, trade name: Elite AT6202);
5 parts of anti-blocking agent-containing masterbatch (LDPE-based MB, anti-blocking agent content: 20% by mass, density: 1.050 g/cm ³ , manufactured by Ampacet, trade name: 10063) were kneaded to obtain blended polyethylene. (hereinafter also referred to as "blend PE (a)") was obtained.
The density of blend PE(a) was 0.917 g/cm ³ .

60 parts of HDPE (density: 0.961 g/cm ³ , MFR: 0.7 g/10 min, manufactured by ExxonMobil, trade name: HTA 108);
30 parts of MDPE (density: 0.935 g/cm ³ , melting point: 123° C., MFR: 0.5 g/10 min, manufactured by ExxonMobil, trade name: Enable 3505HH);
10 parts of LDPE (density: 0.922 g/cm ³ , melting point: 110° C., MFR: 0.75 g/10 min, manufactured by PTT, trade name: LD2420F) are kneaded to form a blended polyethylene (hereinafter referred to as “blended PE (b)”) was obtained.
The density of blend PE(b) was 0.949 g/cm ³ .

45 parts of LLDPE (density: 0.918 g/cm ³ , melting point: 118° C., MFR: 2.0 g/10 min, manufactured by ExxonMobil, trade name: Exceed 2018HA);
45 parts of LLDPE (density: 0.927 g/cm ³ , melting point: 123° C., MFR: 1.3 g/10 min, manufactured by ExxonMobil, trade name: Exceed 1327CA);
10 parts of LDPE (density: 0.922 g/cm ³ , melting point: 110° C., MFR: 0.75 g/10 min, manufactured by PTT, trade name: LD2420F) were kneaded to form a blended polyethylene (hereinafter referred to as “blended PE (c)”) was obtained.
The density of blend PE(c) was 0.923 g/cm ³ .

The blend PE (c), the blend PE (b), and the blend PE (a) are formed into a multilayer extrusion film by an inflation molding method, and the blend PE (c) layer (8 μm)/blend PE (b) layer (24 μm) )/blend PE(a) layer (8 μm), a 3-layer, unstretched sealant film (1) was prepared. Numbers in parentheses indicate layer thicknesses.

The surface of the blended PE (c) layer of the sealant film (1) was subjected to corona treatment, and then the corona-treated surface of the blended PE (c) layer was coated with an aluminum vapor deposition film (Al vapor deposition film) having a thickness of 20 nm by a PVD method. formed.
Vapor-deposited film (1) was obtained as described above.

<Production of laminate>
The stretched multilayer substrate (1) prepared in Production Example 1 and the vapor-deposited film (1) prepared above were placed in such a manner that the Al vapor-deposited film of the vapor-deposited film (1) faced the stretched multilayer substrate (1). A liquid-curing urethane adhesive (trade name: RU-77T/H-7, manufactured by Rock Paint Co., Ltd.) was laminated to obtain a laminate. The thickness of the adhesive layer formed by the two-liquid curing urethane adhesive was 3.0 μm.

[Examples 2 to 11]
A laminate was obtained in the same manner as in Example 1, except that the stretched multilayer substrates (2) to (11) were used instead of the stretched multilayer substrate (1).

[Comparative Example 1]
<Preparation of sealant film>
Blend PE (c), Blend PE (b), and MDPE (density: 0.935 g/cm ³ , melting point: 123° C., MFR: 0.5 g/10 min, manufactured by ExxonMobil, trade name: Enable 3505HH) A three-layer structure and unstretched sealant film comprising a blended PE (c) layer (8 μm) / blended PE (b) layer (24 μm) / MDPE layer (8 μm) by multilayer extrusion film formation by an inflation molding method. (c1) was produced. Numbers in parentheses indicate layer thicknesses.

The surface of the blended PE (c) layer of the sealant film (c1) was subjected to corona treatment, and subsequently, a 20 nm-thick Al deposition film was formed on the corona-treated surface of the blended PE (c) layer by a PVD method.
As described above, a deposited film (c1) was obtained.

<Production of laminate>
A laminate was produced in the same manner as in Example 1, except that the vapor deposition film (c1) was used instead of the vapor deposition film (1).

[Seal strength evaluation]
The laminates obtained in Examples and Comparative Examples were cut into 10 cm×10 cm pieces to prepare three test pieces each. Each test piece is folded in half so that the sealant film (heat seal layer) side faces inside, and a 1 cm x 10 cm area is measured using a heat seal tester under the conditions of a temperature of 140°C, a pressure of 1 kgf/cm ² , and 1 second. was heat sealed.

Cut the heat-sealed test piece into strips with a width of 15 mm, hold both ends that were not heat-sealed with a tensile tester, and measure the peel strength (N / 15 mm) under the conditions of a speed of 300 mm / min and a load range of 50 N. It was measured. In Comparative Example 1, the heat seal layer was not sufficiently fused due to insufficient heat, and sufficient seal strength was not obtained.

[Appearance evaluation]
The appearance of the laminates obtained in Examples was observed, and sensory evaluation of glossiness (luminance) was performed. As a result, the glossiness (brightness) of the obtained laminates was high.

[Evaluation of liquid sachets]
Using a liquid sachet filling machine, a liquid sachet having a length of 100 mm and a width of 80 mm filled with 80 g of water was prepared from the laminates obtained in Examples and Comparative Examples. As a bag-making method, first, two laminates were superimposed so that the sealant films (heat-seal layers) faced each other, and three sides were heat-sealed with a heat-seal bar at 140° C. while filling 80 g of water. Then, the heat-sealed laminate was cut into a size of 100 mm long by 80 mm wide to prepare a liquid sachet.

The bag-making suitability of the liquid sachets was evaluated based on the following evaluation criteria.
AA: The heat-sealed layers were fused together, and a liquid sachet could be produced with a liquid sachet filling machine.
BB: The heat seal layers were not sufficiently fused together, and water leakage occurred in the liquid pouch.

1: laminate 2: heat seal layer 10: resin layer (1)
11: Intermediate layer 12: Resin layer (2)
20: Metal deposition film 30: Base material 32: Adhesive layer

Claims (18)

a substrate composed of polyethylene;
A sachet at least partially composed of a laminate comprising a heat-sealing layer,
The heat seal layer is
A polyethylene resin layer (1) having a density of 0.920 g/cm ³ or less;
A resin layer (2) containing linear low-density polyethylene and low-density polyethylene,
A sachet, wherein the polyethylene resin layer (1) is located in the innermost layer of the sachet. The content of the linear low-density polyethylene in the resin layer (2) is 80% by mass or more and 99% by mass or less, and the content of the low-density polyethylene is 1% by mass or more and 20% by mass or less. A pouch according to claim 1. Claim 1 or 2, wherein the resin layer (1) contains linear low-density polyethylene, and the content of the linear low-density polyethylene in the resin layer (1) is 80% by mass or more. Sachets as described. The pouch according to any one of claims 1 to 3, wherein said resin layer (1) further contains an anti-blocking agent. 5. The difference (D2-D1) between the density D2 of the resin layer (2) and the density D1 of the resin layer (1) is 0.020 g/cm ³ or less, according to any one of claims 1 to 4. The sachet described in . Claims 1 to 5, wherein the heat seal layer further comprises an intermediate layer containing polyethylene and having a density higher than 0.920 g/cm ³ between the resin layer (1) and the resin layer (2). A pouch according to any one of the preceding paragraphs. 7. The pouch according to claim 6, wherein said intermediate layer contains at least one selected from high density polyethylene and medium density polyethylene. 8. The pouch according to claim 7, wherein a total content of said high density polyethylene and said medium density polyethylene in said intermediate layer is 70% by mass or more. the intermediate layer further comprising low density polyethylene;
The content of the low-density polyethylene in the intermediate layer is 1% by mass or more and 30% by mass or less.
A pouch according to claim 7 or 8. The pouch according to any one of claims 1 to 9, wherein the absolute value of the density difference between any two adjacent layers in the heat seal layer is 0.040 g/cm ³ or less. The pouch according to any one of claims 1 to 10, wherein the heat seal layer is an unstretched film. The pouch according to any one of claims 1 to 11, wherein each layer constituting the heat seal layer is a coextruded resin layer. The pouch according to any one of claims 1 to 12, wherein the content of polyethylene in the entire heat seal layer is 90% by mass or more. A pouch according to any preceding claim, wherein the substrate is a stretched substrate. A pouch according to any preceding claim, wherein the substrate is a stretched multilayer substrate. The difference (D3-D1) between the density D3 of the surface resin layer on the heat-seal layer side of the stretched multilayer substrate and the density D1 of the resin layer (1) in the heat-seal layer is 0.022 g/cm ³ or more. 16. The pouch of claim 15, wherein a. The sachet according to any one of the preceding claims, wherein said sachet further comprises a metallized film on said resin layer (2). A pouch according to any preceding claim, wherein the laminate further comprises a printed layer on the substrate.

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