JP2023111767A - Laminated film, laminated paper container and container with lid material - Google Patents

Abstract

To provide a laminated film that has excellent gas barrier properties and also has high moldability (followability) to a shape of an adherend such as a paper container at low temperatures.SOLUTION: A laminated film includes a first surface layer, a gas barrier layer, and an adhesion layer as a second surface layer in this order, wherein the gas barrier layer includes a gas barrier resin with a melting point of 175°C or lower and with the content of ethylene- derived constitutional units being 35 mol% or more.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to laminated films, laminated paper containers, and containers with lids.

In recent years, environmental problems such as marine pollution caused by plastics have become a major social issue. In the packaging field, from the viewpoint of environmental consideration, reduction of the amount of plastic used in packaging materials, change from plastic containers to paper containers, improvement of recyclability, etc. are required. Paper containers are attracting attention as an alternative to plastic containers because they can reduce the volume of waste.

In order to improve the preservability of the contents of a paper container, a film having gas barrier properties is laminated on the inner surface of the paper container (see Patent Document 1). By peeling the laminated film from the paper container, it is possible to dispose of the paper container and the film separately, resulting in excellent recyclability.

JP 2020-146996 A

When a film is laminated on the inner surface of a paper container, the film is heated and softened, and then adhered to the container by a forming technique such as vacuum forming or pressure forming. A conventional film is provided with a gas barrier layer containing a high melting point gas barrier resin such as ethylene-vinyl alcohol copolymer and nylon in order to impart gas barrier properties. In this case, it is necessary to heat and soften the gas barrier resin with a high melting point from the viewpoint of conformability to the shape of the container or adhesion to the container, and the film is formed at a temperature of, for example, over 200°C. However, if the film is molded at a high temperature, problems such as adhesion of the film to the heating member and generation of pinholes may occur. From this point of view, the present inventors have studied molding at low temperature, but in this case, the molding processability (followability) of the film was not sufficient.

An object of the present disclosure is to provide a laminated film that has excellent gas barrier properties and excellent low-temperature moldability (followability) to the shape of an adherend such as a paper container.

The laminated film of the present disclosure includes a first surface layer, a gas barrier layer, and an adhesive layer as a second surface layer in this order, and the gas barrier layer has a melting point of 175° C. or less and contains ethylene-derived structural units. It contains a gas barrier resin with a ratio of 35 mol % or more.

According to the present disclosure, it is possible to provide a laminated film that has excellent gas barrier properties and excellent low-temperature moldability (followability) to the shape of an adherend such as a paper container. The laminated film of the present disclosure can be applied not only to paper containers but also to various adherends.

FIG. 1 is a schematic cross-sectional view of one embodiment of a laminated film. FIG. 2 is a schematic cross-sectional view of one embodiment of the laminated film. FIG. 3 is a schematic cross-sectional view of one embodiment of the laminated film. FIG. 4 is a vertical sectional view showing a paper container with lid according to one embodiment. FIG. 5 is a perspective view showing a paper container of one embodiment. FIG. 6 is a plan view showing a paper container of one embodiment. FIG. 7 is an exploded view showing a blank material for producing a paper container according to one embodiment. FIG. 8 is a cross-sectional view showing a method for manufacturing a paper container according to one embodiment. FIG. 9 is a cross-sectional view showing a method for manufacturing a paper container according to one embodiment. FIG. 10 is a cross-sectional view showing a method for manufacturing a paper container according to one embodiment. FIG. 11 is a perspective view showing a first modification of the paper container of one embodiment. FIG. 12 is a developed view showing a blank material for producing the first modified example. FIG. 13 is a perspective view showing a second modification of the paper container of one embodiment. FIG. 14 is a developed view showing a blank material for producing the second modified example. FIG. 15 is a perspective view showing a third modification of the paper container of one embodiment. FIG. 16 is an exploded view showing a blank material for producing the third modified example. FIG. 17 is an exploded view showing another example of a blank material for producing the third modified example. FIG. 18 is a developed view showing another example of a blank material for producing the third modified example. FIG. 19 is a vertical sectional view showing a paper container of one embodiment.

Hereinafter, this embodiment will be described with reference to the drawings. Each figure shown below is shown typically. Therefore, the size and shape of each part are appropriately exaggerated for easy understanding. In addition, it is possible to modify and implement as appropriate without departing from the technical idea. In addition, in each figure shown below, the same code|symbol is attached|subjected to the same part and detailed description may be partially abbreviate|omitted. In addition, numerical values such as dimensions and material names of each member described in this specification are examples as an embodiment, and are not limited to these, and can be appropriately selected and used. In this specification, terms specifying shapes and geometrical conditions, such as parallel, orthogonal, perpendicular, etc., not only have strict meanings but also include substantially the same states. In this specification, the terms "upper" and "lower" may refer to the upper and lower sides of the paper container in an upright position (FIG. 4). In this specification, the term "surface" may refer to the side facing the contents or the side facing upward when the paper container is erected.

In the following description, each component that appears (for example, polyolefins such as polyethylene and polypropylene, α-olefins, various resins such as low temperature moldable resins, adhesive resins and gas barrier resins, antiblocking agents, and additives) are One type of each may be used, or two or more types may be used.

[Laminated film]
The laminated film of the present disclosure includes a first surface layer, a gas barrier layer, and an adhesive layer as a second surface layer in this order. The gas barrier layer contains a gas barrier resin having a melting point of 175° C. or less and a content ratio of ethylene-derived structural units of 35 mol % or more.

The laminated film may further comprise an intermediate layer that imparts excellent moldability to the film. The laminated film may further include an interlayer adhesion layer that improves adhesion between the intermediate layer and the gas barrier layer, for example.

1-3 show one embodiment of the laminated film of the present disclosure.
The laminated film 100 of FIG. 1 includes a first surface layer 110, a gas barrier layer 116, and an adhesive layer 118 as a second surface layer in this order. In the laminated film 100, the first surface layer 110 is one of the outermost layers, and the adhesive layer 118 is the other outermost layer. The adhesive layer 118 is a layer that comes into contact with an adherend such as a paper container when the laminated film 100 is adhered to the adherend.

The laminated film 100 of FIG. 2 includes a first surface layer 110, an intermediate layer 112, an interlayer adhesion layer 114, a gas barrier layer 116, and an adhesive layer 118 as a second surface layer in this order. The laminated film 100 of FIG. 3 includes a first surface layer 110, a first intermediate layer 112a, a first interlayer adhesion layer 114a, a gas barrier layer 116, a second interlayer adhesion layer 114b, a second interlayer A layer 112b and an adhesive layer 118 as a second surface layer are provided in this order.

<First surface layer>
A laminated film of the present disclosure comprises a first surface layer.
The first surface layer, in one embodiment, contains polyolefin.
A polyolefin is a polymer having at least olefin-derived structural units, and may have only olefin-derived structural units, or may have olefin-derived structural units and other monomer-derived structural units. good too.

Polyolefins include, for example, polyethylene and polypropylene. Among these, polyethylene is preferred. 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 3 to 20 carbon atoms; vinyls such as vinyl acetate and vinyl propionate monomers; (meth)acrylic acid; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

Polyethylene includes, for example, 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 0.945 g/cm ³ or higher. The upper density limit of high-density polyethylene is, for example, 0.965 g/cm ³ . The density of medium density polyethylene is preferably 0.928 g/cm ³ or more and less than 0.945 g/cm ³ . The density of the low-density polyethylene is preferably 0.900 g/cm ³ or more and less than 0.928 g/cm ³ . The linear low-density polyethylene preferably has a density of 0.900 g/cm ³ or more and less than 0.928 g/cm ³ . The density of ultra-low density polyethylene is preferably less than 0.900 g/ ^cm3 . 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 B method or D method (23° C.).

Low-density polyethylene is usually polyethylene obtained by polymerizing ethylene by a high-pressure polymerization method (high-pressure low-density polyethylene). 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, a polymerization method using a Ziegler-Natta catalyst or a metallocene catalyst).

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 multiple stages of 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. A 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 promoter, an organic metal compound if necessary, and a support if necessary. Transition metals in transition metal compounds include, for example, zirconium, titanium and hafnium, with zirconium and hafnium being preferred.

In the present disclosure, polyethylene derived from biomass (hereinafter also referred to as “biomass polyethylene”) may be used as polyethylene. 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 polyethylene is a carbon-neutral material, it can reduce the environmental impact of the laminated film. Biomass polyethylene can be produced, for example, by the method described in JP-A-2013-177531. Commercially available biomass polyethylene may be used. As polyethylene, polyethylene recycled by mechanical recycling or chemical recycling may be used. As a result, the environmental load caused by the laminated film can be reduced.

The first surface layer, in one embodiment, is the layer that contacts the contents of the paper container.
When laminating a laminated film for a paper container on a paper container by, for example, vacuum forming or pressure forming, the film is softened by heating with a heating member such as a hot plate, and then shaped to adhere to the paper container. In addition, when heating the contents of a paper container, it has become mainstream to heat the paper container together with a microwave oven. Therefore, it is preferable that the heat resistance of the first surface layer is high.

The first surface layer preferably contains linear low-density polyethylene, more preferably linear low-density polyethylene and low-density polyethylene, from the viewpoint of a balance between heat resistance and moldability. As a result, for example, the heat resistance of the laminated film can be improved, and for example, a laminated paper container that can withstand heating in a microwave oven can be favorably produced. In addition, for example, the first surface layer and the lid material described later can be heat-sealed well.

The density of the linear low-density polyethylene contained in the first surface layer is preferably 0.900 g/cm ³ or more and less than 0.928 g/cm ³ , more preferably 0.915 g/cm ³ or more and 0.928 g/cm ³ . is less than

The melt flow rate (MFR) of the polyethylene that constitutes the first surface layer is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.2 g/10 min, from the viewpoint of film formability and workability. minutes or more and 30 g/10 minutes or less, more preferably 0.3 g/10 minutes or more and 10 g/10 minutes or less, and particularly preferably 0.5 g/10 minutes or more and 5.0 g/10 minutes or less. The MFR of polyethylene is measured according to JIS K7210:1999 by method A under the conditions of a temperature of 190° C. and a load of 2.16 kg.

For example, when a laminated film is produced by the inflation method, the MFR of the polyethylene constituting the first surface layer is preferably 0.5 g/10 min or more and 5.0 g/10 min or less from the viewpoint of film formability and workability. be. For example, when a laminated film is produced by the T-die method, the MFR of polyethylene constituting the first surface layer is preferably 3.0 g/10 min or more and 20 g/10 min or less from the viewpoint of film formability and workability. .

From the viewpoint of heat resistance, the melting point (Tm) of polyethylene constituting the first surface layer is preferably 100° C. or higher and 140° C. or lower, more preferably 105° C. or higher and 140° C. or lower, further preferably 108° C. or higher and 140° C. or lower. be. The Tm of polyethylene is the melting peak temperature obtained by differential scanning calorimetry (DSC) according to JIS K7121.

The first surface layer preferably contains polyolefin such as polyethylene as a main component, that is, contains polyolefin such as polyethylene in a proportion of more than 50% by mass. The content of polyolefin such as polyethylene in the first surface layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more, relative to the total mass of the first surface layer. Thereby, for example, the heat resistance and moldability of the laminated film can be improved.

In one embodiment, the content of linear low-density polyethylene in the first surface layer is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more, or 90% by mass or more. Thereby, for example, the balance between heat resistance and moldability of the laminated film can be further improved.

When the first surface layer further contains low-density polyethylene, the content of linear low-density polyethylene in the first surface layer is preferably 40% by mass or more and 80% by mass with respect to the total mass of the first surface layer. % or less, more preferably 45 mass % or more and 75 mass % or less, still more preferably 50 mass % or more and 70 mass % or less. Thereby, for example, the balance between heat resistance and moldability of the laminated film can be further improved.

The content of low-density polyethylene in the first surface layer is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 55% by mass or less, still more preferably It is 30 mass % or more and 50 mass % or less. Thereby, for example, the balance between heat resistance and moldability of the laminated film can be further improved.

The first surface layer may contain additives. Additives include, for example, crosslinkers, antiblocking agents, lubricants, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins.

The thickness of the first surface layer is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, and still more preferably 15 μm or more and 30 μm or less. Thereby, for example, the balance between heat resistance and rigidity of the laminated film can be improved. When the thickness of the first surface layer is at least the lower limit, for example, sufficient sealing strength can be obtained when the lid member is heat-sealed to a laminated paper container.

The ratio of the thickness of the first surface layer to the total thickness of the laminated film is preferably 5% or more and 40% or less, more preferably 10% or more and 35% or less, still more preferably 15% or more and 30% or less. When the thickness ratio is equal to or higher than the lower limit, for example, sufficient sealing strength can be obtained when the lid member is heat-sealed to a laminated paper container.

In one embodiment, the first surface layer constitutes one outermost layer of the laminated film of the present disclosure. In one embodiment, when the laminated film of the present disclosure is closely-molded on the surface of a paper container, the first surface layer is a layer that comes into contact with the contents contained in the paper container.

The first surface layer may be electron beam irradiated. Thereby, for example, the cross-linking density of the first surface layer can be improved, and as a result, the heat resistance of the laminated film is improved, and heat lamination can be performed at a higher temperature in a shorter time. The absorption dose of electron beam irradiation is, for example, 20 kGy or more and 130 kGy or less.

<Middle layer>
A laminated film of the present disclosure, in one embodiment, comprises an intermediate layer. The intermediate layer, in one embodiment, is a layer that imparts excellent moldability (for example, conformability to the shape of a container) to the laminated film. Hereinafter, the intermediate layer is also referred to as "molding layer".

The molding layer preferably contains a resin that can be molded at a low temperature (hereinafter also referred to as a "low temperature moldable resin"). Thereby, for example, it is possible to improve the moldability of the laminated film at, for example, 200° C. or less, and to improve, for example, the followability of the laminated film to the container shape (for example, deep drawability). Low temperature moldable resins include, for example, ionomer resins, ethylene-(meth)acrylic acid copolymers and ethylene-vinyl acetate copolymers. Among these, ionomer resins are preferred.

Ionomer resins include, for example, resins in which intermolecular ethylene-(meth)acrylic acid copolymers are ionically crosslinked by salt formation between the acid moieties of the copolymer and metal ions. Examples of metal cations that bridge the molecular chains of the ionomer resin include Na ⁺ and Zn ²⁺ .

The MFR of the ionomer resin is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.2 g/10 min or more and 30 g/10 min or less, and still more preferably 0.3 g/10 min or more and 10 g/10 min or less, particularly preferably 0.5 g/10 min or more and 5.0 g/10 min or less. The MFR of the ionomer resin is measured according to JIS K7210:1999 by method A under conditions of a temperature of 190° C. and a load of 2.16 kg.

The melting point (Tm) of the ionomer resin is preferably 80° C. or higher and 120° C. or lower, more preferably 80° C. or higher and 115° C. or lower, still more preferably 80° C. or higher and 110° C. or lower, from the viewpoint of low-temperature moldability. Tm is the melting peak temperature obtained by DSC according to JIS K7121.

The content of the low-temperature moldable resin in the molding layer is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass, relative to the total mass of the molding layer. That's it. Thereby, for example, the moldability of the laminated film can be improved.

The molding layer may contain the above additives.

The molding layer may be one layer or a plurality of layers of two or more layers.

The thickness of the molding layer is preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 50 μm or less, still more preferably 15 μm or more and 40 μm. Thereby, for example, the moldability of the laminated film can be improved. When the molding layer has multiple layers, the total thickness of the multiple layers is the thickness of the molding layer.

The ratio of the thickness of the molding layer to the thickness of the entire laminated film is preferably 10% or more and 50% or less, more preferably 15% or more and 45% or less, and still more preferably 20% or more and 40% or less.
<Interlayer adhesion layer>
The laminated film of the present disclosure may further include an interlayer adhesion layer between arbitrary layers such as between the gas barrier layer and the molding layer. Thereby, the adhesion between arbitrary layers, for example, the adhesion between the gas barrier layer and the molding layer can be improved.

The interlayer adhesion layer contains, for example, an adhesive resin. Adhesive resins include, for example, modified polyolefins, vinyl resins, polyethers, polyesters, polyamides, polyurethanes, silicone resins, epoxy resins and phenolic resins. Among these, from the viewpoint of adhesion and recyclability, modified polyolefins such as modified polyethylene and modified polypropylene are preferred, acid-modified polyolefins such as acid-modified polyethylene and acid-modified polypropylene are more preferred, and acid-modified polyethylene is even more preferred.

Modified polyolefins include, for example, modified polyolefins (specifically, graft-modified products) with unsaturated carboxylic acids or their acid anhydrides, esters or metal salts. Unsaturated carboxylic acids include, for example, maleic acid and fumaric acid, and anhydrides of unsaturated carboxylic acids include, for example, maleic anhydride. Specific examples of modified polyoleins include maleic anhydride-modified polyethylene such as maleic anhydride-graft-modified polyethylene.

Modified polyolefins also include ethylene-(meth)acrylic acid ester copolymers such as ethylene-vinyl acetate copolymer, ethylene-methyl(meth)acrylate copolymer and ethylene-ethyl(meth)acrylate copolymer. coalescence, as well as ethylene-(meth)acrylic acid copolymers.

From the viewpoint of film formability and processability, the MFR of the modified polyolefin is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.2 g/10 min or more and 30 g/10 min or less, and still more preferably 0.3 g/10 min or more and 10 g/10 min or less, particularly preferably 0.5 g/10 min or more and 5.0 g/10 min or less. The MFR of the modified polyolefin, for example, in the case of modified polyethylene, is measured according to JIS K7210: 1999 under conditions of a temperature of 190°C and a load of 2.16 kg by Method A. The measurement temperature depends on the melting point of the modified polyolefin. You can change it.

The content of the adhesive resin in the interlayer adhesion layer is preferably 50% by mass or more, more preferably 75% by mass or more, and still more preferably 80% by mass or more, 85% by mass or more, relative to the total mass of the interlayer adhesion layer. Or it is 90% by mass or more. Thereby, for example, the adhesion between each layer can be improved.

The interlayer adhesion layer may contain the above additives.

The interlayer adhesion layer may be one layer or a plurality of layers of two or more layers.

The thickness of the interlayer adhesion layer is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, still more preferably 15 μm or more and 30 μm or less. As a result, for example, the balance between adhesion between layers, heat resistance and rigidity can be further improved. When the interlayer adhesion layer has a plurality of layers, the total thickness of the plurality of layers is the thickness of the interlayer adhesion layer.

The ratio of the thickness of the interlayer adhesion layer to the total thickness of the laminated film is preferably 5% or more and 40% or less, more preferably 10% or more and 35% or less, still more preferably 15% or more and 30% or less.

<Gas barrier layer>
The laminated film of the present disclosure comprises a gas barrier layer. Thereby, for example, gas barrier properties such as oxygen barrier properties of the laminated film can be improved. The gas barrier layer contains a gas barrier resin. Hereinafter, the gas barrier layer is also simply referred to as "barrier layer".

Gas barrier resins include, for example, ethylene-vinyl alcohol copolymers, polyamides, polyvinyl alcohol, polyacrylonitrile, polyesters, polyurethanes, and (meth)acrylic resins. Among these, ethylene-vinyl alcohol copolymer (hereinafter also referred to as "EVOH") is preferable from the viewpoint of oxygen barrier properties and/or water vapor barrier properties.

The content ratio of ethylene-derived structural units (ethylene copolymerization ratio) in gas barrier resins such as EVOH is preferably 35 mol% or more, more preferably 35 mol% or more and 50 mol% or less, and still more preferably 37 mol% or more and 47%. mol% or less. When the ethylene copolymerization ratio is at least the lower limit, for example, it is possible to improve the moldability of the laminated film, specifically, the conformability during low-temperature molding, and to improve the gas barrier properties. When the ethylene copolymerization ratio is equal to or less than the upper limit, for example, the gas barrier properties of the laminated film can be improved, and for example, it may be 42 mol% or less. The ethylene copolymerization ratio is measured by the NMR method.

The melting point (Tm) of the gas barrier resin such as EVOH is preferably 175°C or lower, more preferably 130°C or higher and 173°C or lower, still more preferably 140°C or higher and 170°C or lower, and particularly preferably 150°C or higher and 168°C or lower. . When Tm is equal to or less than the upper limit, for example, it is possible to improve the moldability of the laminated film, specifically, the conformability during low-temperature molding, and to improve the gas barrier properties. Tm is the melting peak temperature obtained by DSC according to JIS K7121.

The crystallization temperature (Tc) of the gas barrier resin such as EVOH is preferably 152°C or lower, more preferably 110°C or higher and 148°C or lower, still more preferably 115°C or higher and 140°C or lower. When Tc is equal to or less than the upper limit, for example, the moldability of the laminated film, specifically the followability during low-temperature molding, can be improved. Tc is the crystallization peak temperature obtained by DSC (cooling rate: 5°C/min) according to JIS K7121.

By using a gas barrier resin (especially EVOH) having an ethylene copolymerization ratio of 35 mol% or more and a Tm of 175°C or less, the gas barrier property of the laminated film can be improved and, for example, during molding at 200°C or less, It is possible to improve moldability (for example, conformability to container shape).

The MFR of the gas barrier resin such as EVOH is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.2 g/10 min or more and 30 g/10 min or less, from the viewpoint of film formability and workability. , more preferably 0.3 g/10 min or more and 10 g/10 min or less, and particularly preferably 0.5 g/10 min or more and 5.0 g/10 min or less. The MFR of the gas barrier resin is measured according to JIS K7210:1999 by method A under the conditions of a temperature of 190° C. and a load of 2.16 kg.

The content of the gas barrier resin in the gas barrier resin layer is preferably 50% by mass or more, more preferably 75% by mass or more, and still more preferably 80% by mass or more and 85% by mass with respect to the total mass of the gas barrier resin layer. or more, or 90% by mass or more. Thereby, for example, the gas barrier properties of the laminated film can be improved.

The barrier layer may contain the above additives.

The barrier layer may be one layer or a plurality of layers of two or more layers.

The thickness of the barrier layer is preferably 1 μm or more and 30 μm or less, more preferably 3 μm or more and 20 μm or less, and still more preferably 5 μm or more and 15 μm or less. When the thickness is at least the lower limit, for example, the effect of the barrier layer can be improved. When the thickness is equal to or less than the upper limit, for example, deterioration of followability during lamination of the laminated film to the adherend can be suppressed. When the barrier layer has multiple layers, the total thickness of the multiple layers is the thickness of the barrier layer.

The ratio of the thickness of the barrier layer to the total thickness of the laminated film is preferably 1% or more and 30% or less, more preferably 3% or more and 20% or less, and still more preferably 5% or more and 15% or less.

<Adhesive layer>
The laminated film of the present disclosure comprises an adhesive layer. The adhesive layer is a layer that comes into contact with an adherend such as a paper container when the laminated film is attached to the adherend, and in one embodiment, has adhesiveness to paper, plastic, metal, ceramic, wood, or the like. .

The adhesive layer contains, for example, an adhesive resin. Adhesive resins include, for example, modified polyolefins, vinyl resins, polyethers, polyesters, polyamides, polyurethanes, silicone resins, epoxy resins and phenolic resins. Among these, from the viewpoint of adhesion and recyclability, modified polyolefins such as modified polyethylene and modified polypropylene are preferred, acid-modified polyolefins such as acid-modified polyethylene and acid-modified polypropylene are more preferred, and acid-modified polyethylene is even more preferred.

Modified polyolefins include, for example, modified polyolefins (specifically, graft-modified products) with unsaturated carboxylic acids or their acid anhydrides, esters or metal salts. Unsaturated carboxylic acids include, for example, maleic acid and fumaric acid, and anhydrides of unsaturated carboxylic acids include, for example, maleic anhydride. Specific examples of modified polyoleins include maleic anhydride-modified polyethylene such as maleic anhydride-graft-modified polyethylene.

Modified polyolefins also include ethylene-(meth)acrylic acid ester copolymers such as ethylene-vinyl acetate copolymer, ethylene-methyl(meth)acrylate copolymer and ethylene-ethyl(meth)acrylate copolymer. coalescence, as well as ethylene-(meth)acrylic acid copolymers.

From the viewpoint of film formability and processability, the MFR of the modified polyolefin is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.2 g/10 min or more and 30 g/10 min or less, and still more preferably 0.3 g/10 min or more and 10 g/10 min or less, particularly preferably 0.5 g/10 min or more and 5.0 g/10 min or less. The MFR of the modified polyolefin, for example, in the case of modified polyethylene, is measured according to JIS K7210: 1999 under conditions of a temperature of 190°C and a load of 2.16 kg by Method A. The measurement temperature depends on the melting point of the modified polyolefin. You can change it.

The content of the adhesive resin in the adhesive layer is preferably 50% by mass or more, more preferably 75% by mass or more, and still more preferably 80% by mass or more, 85% by mass or more, or 90% by mass, relative to the total mass of the adhesive layer. % by mass or more. Thereby, for example, the adhesiveness between the laminated film and the adherend can be improved.

The adhesive layer may further contain an antiblocking agent. As a result, for example, the adhesive strength between the laminated film and the adherend can be adjusted, and the peelability of the laminated film from the adherend (specifically, when the laminated film is molded and adhered to the adherend at high temperature peelability) can be improved, and therefore the recyclability of the laminated paper container can be improved. In addition, blocking between laminated films can be suppressed.

Antiblocking agents include, for example, inorganic compound antiblocking agents and resin particle antiblocking agents. Specific examples of inorganic compound antiblocking agents include oxides such as silica, aluminum oxide, magnesium oxide, calcium oxide, titanium oxide and zinc oxide, and water such as aluminum hydroxide, magnesium hydroxide and calcium hydroxide. Oxides, carbonates such as magnesium carbonate and calcium carbonate, sulfates such as calcium sulfate and barium sulfate, silicates, zeolites, kaolin, talc and diatomaceous earth. Specific examples of the resin particles include (meth)acrylic resins such as polymethyl methacrylate (PMMA), polystyrene, methyl methacrylate-styrene copolymers, polyesters, polyamides, polytetrafluoroethylene, silicone resins, epoxy resins, Examples thereof include resin particles composed of resin components such as urea resin and phenol resin. The resin particles may be crosslinked or non-crosslinked.

The average particle size of the antiblocking agent is preferably 1.0 μm or more and 15.0 μm or less, more preferably 2.0 μm or more and 12.5 μm or less, and still more preferably 3.0 μm or more and 10.0 μm or less. When the average particle size is at least the lower limit, for example, the peelability of the laminate film from the adherend can be improved. When the average particle size is equal to or less than the upper limit, for example, the antiblocking agent can be prevented from falling off from the adhesive layer.

In the present disclosure, the average particle size is the average particle size measured for non-aggregates of 100 randomly selected particles ( mean diameter).

The content of the antiblocking agent in the adhesive layer is preferably 0.1% by mass or more and 30.0% by mass or less, more preferably 0.15% by mass or more and 20.0% by mass or less, relative to the total mass of the adhesive layer. , more preferably 0.2% by mass or more and 10.0% by mass or less, and particularly preferably 0.2% by mass or more and 2.5% by mass or less. When the content is at least the lower limit, for example, the peelability of the laminated film from the adherend (specifically, the peelability when the laminated film is molded at high temperature and adhered to the adherend) can be improved. . When the content is equal to or less than the upper limit, for example, the antiblocking agent can be prevented from falling off from the adhesive layer.

In order to increase the dispersibility of the antiblocking agent in the resin composition forming the adhesive layer, a masterbatch containing the antiblocking agent and a thermoplastic resin may be used. Thermoplastic resins include, for example, polyolefins such as polyethylene and polypropylene. The content of the antiblocking agent in the masterbatch is preferably 1% by mass or more and 70% by mass or less, more preferably 2% by mass or more and 65% by mass or less, and still more preferably 3% by mass or more and 60% by mass or less.

The adhesive layer may further contain at least one selected from linear low-density polyethylene and low-density polyethylene. As a result, for example, the adhesive strength between the laminated film and the adherend can be adjusted, and the peelability of the laminated film from the adherend (specifically, when the laminated film is molded and adhered to the adherend at high temperature peelability) can be improved, and therefore the recyclability of the laminated paper container can be improved.

The range described as the MFR of the polyethylene forming the first surface layer can be applied to the linear low-density polyethylene and the MFR of the low-density polyethylene. The melting point (Tm) of linear low-density polyethylene and low-density polyethylene is preferably 100° C. or higher and 140° C. or lower, more preferably 100° C. or higher and 130° C. or lower, still more preferably 100° C. or higher and 120° C. or lower.

The total content of linear low-density polyethylene and low-density polyethylene in the adhesive layer in the above embodiment is preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass, relative to the total mass of the adhesive layer. 35% by mass or more, more preferably 10% by mass or more and 30% by mass or less. When the content is at least the lower limit, for example, the peelability of the laminated film from the adherend (specifically, the peelability when the laminated film is molded at high temperature and adhered to the adherend) can be improved. .

The adhesive layer may further contain an ethylene-(meth)acrylic acid ester copolymer such as an ethylene-methyl(meth)acrylate copolymer. Such copolymers have low melting points. As a result, for example, the adhesion between the adherend and the laminated film (specifically, the adhesion when the laminated film is molded to the adherend at a low temperature and brought into close contact) can be improved. Ethylene-methyl acrylate copolymer is particularly preferred.

The MFR of the ethylene-(meth)acrylic acid ester copolymer is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.2 g/10 min or more, from the viewpoint of film formability and workability. It is 30 g/10 minutes or less, more preferably 0.3 g/10 minutes or more and 10 g/10 minutes or less, and particularly preferably 0.5 g/10 minutes or more and 5.0 g/10 minutes or less. The MFR of an ethylene-(meth)acrylic acid ester copolymer is measured by method A in accordance with JIS K7210:1999 under conditions of a temperature of 190° C. and a load of 2.16 kg.

The melting point (Tm) of the ethylene-(meth)acrylic acid ester copolymer is preferably 60° C. or higher and 100° C. or lower, more preferably 60° C. or higher and 90° C. or lower, still more preferably, from the viewpoint of moldability and adhesiveness. It is 60°C or higher and 80°C or lower. Tm is the melting peak temperature obtained by DSC according to JIS K7121.

In the ethylene-(meth)acrylic acid ester copolymer, the content of structural units derived from (meth)acrylic acid ester is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, More preferably, it is 15% by mass or more and 30% by mass or less. The content ratio is measured by the NMR method.

The content of the ethylene-(meth)acrylic acid ester copolymer in the adhesive layer in the above embodiment is preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass, relative to the total mass of the adhesive layer. 35% by mass or more, more preferably 10% by mass or more and 30% by mass or less. When the content is at least the lower limit, for example, the adhesion of the laminated film to the adherend (specifically, the adhesion when the laminated film is molded to the adherend at a low temperature and brought into close contact) can be improved.

The adhesive layer may contain the above additives.

The adhesive layer may be surface-treated. Thereby, for example, the adhesive strength between the adhesive layer and an adherend such as a paper container 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. Among these, corona discharge treatment is preferred.

The wet tension on the adhesive layer surface of the laminated film of the present disclosure is preferably 40 mN/m or more, more preferably 43 mN/m or more and 65 mN/m or less, and even more preferably 45 mN/m or more and 60 mN/m or less. When the wetting tension is equal to or higher than the lower limit, for example, the adhesion between the adherend and the laminated film (specifically, the adhesion when the laminated film is molded and adhered to the adherend at a low temperature) can be improved. . Wetting tension can be adjusted, for example, by the surface treatment described above.

Wetting tension is measured by a method conforming to JIS K6768:1999. Wetting tension is measured in an environment of 23° C. temperature and 50% relative humidity. Specifically, the measurement is performed using a tension checker (TC-B-48.0) manufactured by Pacific Chemical Co., Ltd. The reagent is applied in the width direction of the surface of the adhesive layer, and after 2 seconds, it is visually judged whether or not the liquid film is broken.

As an adhesive layer, for example,
- An adhesive layer containing an acid-modified polyethylene and at least one selected from an anti-blocking agent, a linear low-density polyethylene and a low-density polyethylene, and having a wet tension of 40 mN/m or more;
- An adhesive layer containing an acid-modified polyethylene, at least one selected from an anti-blocking agent, a linear low-density polyethylene and a low-density polyethylene, and an ethylene-(meth)acrylic acid ester copolymer,
-Contains an acid-modified polyethylene, at least one selected from an anti-blocking agent, a linear low-density polyethylene and a low-density polyethylene, and an ethylene-(meth)acrylic acid ester copolymer, and has a wet tension of 40 mN/ an adhesive layer that is greater than or equal to m,
is mentioned.

A laminated film having such an adhesive layer has excellent adhesion to an adherend such as a paper container even when molded at a low temperature, and can be easily removed from the adherend even when molded at a high temperature. Excellent releasability.

The thickness of the adhesive layer is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, and still more preferably 15 μm or more and 30 μm or less. Thereby, for example, it is possible to further improve the balance of adhesiveness to the adherend, releasability and rigidity.

The ratio of the thickness of the adhesive layer to the total thickness of the laminated film is preferably 5% or more and 40% or less, more preferably 10% or more and 35% or less, and still more preferably 15% or more and 30% or less.

[Layer structure of laminated film]
In one embodiment, the laminated film of the present disclosure includes a first surface layer, a molding layer, an interlayer adhesion layer, a barrier layer, and an adhesive layer as a second surface layer in this order. The adhesive layer is laminated with an adherend such as a paper container, for example.

In one embodiment, the laminated film of the present disclosure includes a first surface layer, a first molding layer, a first interlayer adhesion layer, a barrier layer, a second interlayer adhesion layer, and a second molding layer. and an adhesive layer as a second surface layer in this order.

The thickness of the entire laminated film of the present disclosure is preferably 30 μm or more, more preferably 40 μm or more and 300 μm or less, and even more preferably 50 μm or more and 200 μm or less. When the thickness of the entire laminated film is at least the lower limit, the strength can be improved.

The laminated film of the present disclosure may be electron beam irradiated. Thereby, for example, the cross-linking density of the laminated film can be improved, and as a result, the heat resistance of the laminated film is improved, and heat lamination can be performed at a higher temperature in a short time. The absorption dose of electron beam irradiation is, for example, 20 kGy or more and 130 kGy or less.

The laminated film of the present disclosure has excellent gas barrier properties and also excellent moldability at low temperatures. The laminated film of the present disclosure, for example, at a molding temperature of 140 ° C. or higher and 200 ° C. or lower, has excellent followability to the shape of an adherend such as a paper container, and also adheres to an adherend such as a paper container. Are better. Therefore, the laminated film of the present disclosure is suitable as a laminated film for paper containers.

The laminated film of the present disclosure has an oxygen permeability under conditions of 23° C. and 65% RH that is preferably 20 cc/m ² ·day·atm or less, more preferably 15 cc/m ² ·day·atm or less, even more preferably is 10 cc/m ² ·day·atm or less. Details of the conditions for measuring the oxygen permeability are described in Examples.

The laminated film of the present disclosure can be applied not only to paper containers but also to various adherends. Examples of adherends include paper containers, plastic containers, and various members (eg, containers) made of metal, ceramic, wood, or the like. Examples of adherends include electronic members such as capacitors, semiconductor integrated circuits, wafers, and light-emitting elements.

[Method for producing laminated film]
In one embodiment, the laminated film of the present disclosure is a coextruded resin film, and each layer constituting the film is a coextruded resin layer. A co-extruded resin film can be produced by, for example, film-forming the materials constituting each layer by an inflation method or a T-die method. The laminated film is composed of, for example, a material that forms the first surface layer, a material that forms the molding layer, a material that forms the interlayer adhesion layer, a material that forms the barrier layer, and a material that forms the adhesive layer, It can be obtained by co-extrusion film formation by a conventionally known method such as an inflation method and a T-die method.

The laminated film of the present disclosure is obtained by coating the surface of another layer for constituting the laminated film with a material for forming one of the layers therein and drying it as necessary. It can also be manufactured by forming a laminated structure and, if necessary, further laminating layers other than these so as to obtain a desired arrangement form.

In the laminated film of the present disclosure, two or more films for constituting two or more layers of any of them are separately prepared in advance, and these films are laminated using an adhesive by dry lamination, extrusion lamination, Laminating and laminating by either hot melt lamination method or wet lamination method, or laminating and laminating by thermal (heat) lamination method or the like without using an adhesive, and if necessary, layers other than these It can also be manufactured by further laminating so as to obtain the desired arrangement form. At this time, an adhesive resin capable of forming an interlayer adhesion layer may be used as the adhesive.

[Laminated paper container]
A laminated paper container of the present disclosure includes a paper container and a formed film laminated on the surface of the paper container. The formed film is formed from the laminated film of the present disclosure, and the adhesive layer of the laminated film is in contact with the surface of the paper container. The laminated paper container of the present disclosure can be used as a container in a wide range of fields, for example, beverages such as milk drinks, fruit drinks, and alcohol, and foods such as rice, side dishes, meat, and dairy products. The laminated paper container may be a container for chilled foods or frozen foods, or can be used as a take-out container.
A laminated paper container may be hereinafter also referred to as a “paper container”.

A laminated paper container can be produced by heating and softening a laminated film and adhering it to a paper container by a forming technique such as vacuum forming or pressure forming. The heating temperature is, for example, 140° C. or higher and 200° C. or lower, may be 140° C. or higher and 190° C. or lower, or may be 140° C. or higher and 180° C. or lower.

[Paper container with lid]
An embodiment in which the laminated film of the present disclosure is applied to the production of a paper container will be described below.
As shown in FIG. 4, the lid-equipped paper container 1 according to the present embodiment includes a paper container 10 and a lid 50 for sealing the paper container 10 . Here, first, the paper container 10 will be described.

<Paper container>
As shown in FIGS. 4 to 6, the paper container 10 includes a paper container 20 and a formed film 40 laminated on the surface of the paper container 20. As shown in FIGS. The formed film 40 is formed from the laminated film of the present disclosure, and the adhesive layer of the laminated film is in contact with the surface of the paper container 20 . Of these, the paper container 20 can be produced, for example, by assembling blank materials 30 to be described later.

(paper container)
The paper container 20 includes, for example, a bottom portion 21, a plurality of side portions 23 connected to the bottom portion 21 via folding lines (first folding lines) 22, and each side portion 23 having folding lines (second folding lines) 24 therebetween. and a plurality of flange pieces 25 connected together.

The depth of the paper container 20 is not particularly limited, but may be, for example, 1 cm or more, 1.5 cm or more, 2 cm or more, 10 cm or less, 8 cm or less, 6 cm or less, or 4 cm or less.

Among them, the bottom portion 21 has, for example, a substantially rectangular shape in plan view. Note that the bottom portion 21 may have a polygonal shape such as an octagonal shape in plan view.

A fold line (first fold line) 22 that connects the bottom portion 21 and the side portion 23 may be formed in a perforated line or a half-cut line. Thereby, the side portion 23 can be easily bent with respect to the bottom portion 21 . When the folding line 22 is formed in a perforation, the formed film 40 is pressed against the paper container 20 near the folding line 22 by sucking air from the suction holes 61 of the cavity-side mold 60, which will be described later. Thereby, the adhesion between the formed film 40 and the paper container 20 can be improved.

Each side portion 23 extends upward from the bottom portion 21 respectively. In the illustrated example, the paper container 20 has four side portions 23, and the side portions 23 are formed in the shape of an inverted truncated square pyramid as a whole. However, it is not limited to this, and the side portion 23 may be formed in a polygonal truncated pyramid shape such as an inverted octagonal truncated pyramid shape as a whole.

The multiple side portions 23 are adjacent to each other without being continuous with each other. That is, the side portions 23 are adjacent to each other without overlapping. Thereby, the adhesiveness between the side portion 23 and the formed film 40 can be improved over the entire circumference of the paper container 20 . In addition, since the side portions 23 are adjacent to each other without overlapping each other, it is possible to suppress the occurrence of pinholes or the like in the formed film 40 when the formed film 40 is adhered to the paper container 20. there is Between the side portions 23, minute gaps are formed through which air can pass, and by sucking air from suction holes 61 of the cavity-side mold 60, which will be described later, the molded film 40 is pulled into the paper container 20. configured to be pressed against

A fold line (second fold line) 24 that connects the side portion 23 and the flange piece 25 may be formed like a perforation, or may be a half-cut line, like the fold line 22 . Thereby, the flange piece 25 can be easily bent with respect to the side portion 23 . When the folding line 24 is formed in a perforation, the formed film 40 is pressed against the paper container 20 in the vicinity of the folding line 24 by sucking air from the suction holes 61 of the cavity-side mold 60, which will be described later. Thereby, the adhesion between the formed film 40 and the paper container 20 can be improved.

Each flange piece 25, for example, protrudes horizontally from the upper end of the side portion 23 toward the side. In the illustrated example, the paper container 20 has four flange pieces 25, and the flange pieces 25 are formed in an annular shape as a whole.

The plurality of flange pieces 25 are, for example, adjacent to each other without being continuous. That is, the flange pieces 25 are adjacent to each other without overlapping each other. Thereby, the adhesion between the flange piece 25 and the formed film 40 can be improved over the entire circumference of the paper container 20 . In addition, since the flange pieces 25 are adjacent to each other without overlapping each other, it is possible to suppress the occurrence of pinholes or the like in the formed film 40 when the formed film 40 is adhered to the paper container 20. there is Furthermore, since the flange pieces 25 are adjacent to each other without overlapping each other, when sealing the lid material 50 in the area corresponding to the flange piece 25 of the formed film 40 of the paper container 10, the formed film Adhesion between 40 and lid member 50 can be improved. As a result, it is possible to suppress the occurrence of sealing failure of the lid member 50 . In this specification, the term "adjacent" refers to the case where mutually adjacent members (for example, the flange pieces 25) are in contact with each other over the entire area without gaps, and the case where the following (1) or (2) applies. Also includes
(1) The one member and the other member are adjacent to each other with only a part of the one member in contact with the other member.
(2) When the one member and the other member are adjacent to each other while the one member and the other member are not in contact with each other, the gap between the one member and the other member At least a part of the gap should be such that the formed film 40 (later-described laminated film 40a) cannot enter when the formed film 40 is adhered to one member and another member.

Next, an example of adhesive strength between the paper container 20 and the formed film 40 will be described.

The adhesive strength between the bottom portion 21 and the forming film 40 and the adhesive strength between the side portion 23 and the forming film 40 may be, for example, 0.05 N/15 mm or more and 0.4 N/15 mm or less. When the adhesive strength of these is 0.05 N/15 mm or more, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20 . In particular, when the lid member 50 is removed from the paper container 10 of the paper container 1 with lid member, it is possible to prevent the formed film 40 from unintentionally peeling off from the bottom portion 21 or the side portion 23 of the paper container 20 . In addition, when the paper container 20 is recycled, the paper container 20 and the formed film 40 can be easily separated from each other when the adhesive strength of these is 0.4 N/15 mm or less. Note that the adhesive strength between the bottom portion 21 and the molding film 40 and the adhesive strength between the side portion 23 and the molding film 40 may be different from each other. For example, the adhesive strength between side portion 23 and forming film 40 may be greater than the adhesive strength between bottom portion 21 and forming film 40 . In addition, the adhesive strength was measured in accordance with JIS Z 0238: 1998, using a tensile tester (for example, Orientec Co., Ltd., Tensilon universal material tester: RTC1310A) for a sample cut into a strip with a width of 15 mm. can be measured by performing a 90° peeling test at a peeling speed of 50 mm/min.

The adhesive strength between the flange piece 25 and the forming film 40 may be, for example, 1.0 N/15 mm or more. As a result, when the lid member 50 is removed from the paper container 10 , it is possible to prevent the formed film 40 from peeling off from the flange pieces 25 . For this reason, it is possible to suppress the deterioration of the openability of the lid member 50 .

Also, the adhesive strength between the flange piece 25 and the forming film 40 may be, for example, 5.0 N/15 mm or less. As a result, it is possible to prevent difficulty in peeling off the formed film 40 from the paper container 20 when recycling the paper container 20 . In this case, the paper container 20 from which the molded film 40 has been peeled off may have paper peeling (partial peeling of the paper container).

Here, a heat sealing agent may be applied to at least part of the surface of the paper container 20 (the surface of the blank material 30 to be described later). Thereby, the adhesion strength between the paper container 20 and the formed film 40 can be easily adjusted. Therefore, desired adhesive strength can be easily obtained. In this embodiment, a heat seal layer H is provided on the flange piece 25 (a flange piece panel 35 to be described later). The heat seal layer H is formed by applying a heat sealing agent on the flange piece 25 (flange piece panel 35 to be described later). The heat sealant may be ink. As the heat sealing agent, those containing ethylene-vinyl acetate copolymer (EVA), ionomer, polyethylene (PE) or polypropylene (PP) can be used. Examples of heat sealing agents include vinyl, acrylic, polyamide, polyester, polyether, polyurethane, epoxy, chlorinated EVA, chlorinated PP, vinyl chloride, polyol, and polyethyleneimine. , starch-based, nitrocellulose-based, rubber-based resins, and the like. Furthermore, the heat sealing agent may be applied onto the flange piece 25 (a flange piece panel 35 described later) by gravure printing, flexographic printing, offset printing, or the like. In addition, in FIG. 5 etc., the area|region in which the heat-seal layer H was provided is shown by hatching.

The weight per unit area of the heat seal layer H (that is, the amount of the heat sealant applied on the flange piece 25 (flange piece panel 35 described later)) is 0.1 g/m2 or ^more and 10.0 g/m2. It can be ² or less. Desired adhesive strength between the flange piece 25 and the forming film 40 is achieved by setting the application amount of the heat sealing agent applied on the flange piece 25 (flange piece panel 35 to be described later) to 0.1 g/m ² or more. can be easily increased to a strength of Therefore, when the lid member 50 is removed from the paper container 10 , it is possible to prevent the formed film 40 from peeling off from the flange piece 25 , thereby suppressing deterioration in the ease of opening the lid member 50 . In addition, the adhesive strength between the flange piece 25 and the formed film 40 is increased by setting the amount of the heat sealing agent applied on the flange piece 25 (flange piece panel 35 described later) to 10.0 g/m ² or less. can be suppressed from becoming too large. Therefore, it is possible to prevent difficulty in peeling off the formed film 40 from the paper container 20 when recycling the paper container 20 .

(blank material)
Next, an example of the blank material 30 for producing the paper container 20 will be described. As shown in FIG. 7 , the blank 30 includes, for example, a bottom panel 31 , a plurality of side panels 33 connected to the bottom panel 31 via first fold lines 32 , and each side panel 33 having a first fold. and a plurality of flange piece panels 35 connected via two fold lines 34 . In the illustrated example, the blank 30 includes four side panels 33 and four flange strip panels 35 . The bottom panel 31, the first folding line 32, the side panel 33, the second folding line 34 and the flange piece panel 35 of the blank material 30 correspond to the bottom part 21 of the paper container 20, the folding line (first folding line) 22, the side part 23 and the folding line, respectively. It corresponds to (second polygonal line) 24 and flange piece 25 .

The bottom panel 31, the side panels 33 and the flange piece panels 35 of the blank 30 are integrally formed. Such a blank material 30 can be produced by subjecting a paper material constituting the blank material 30 to punching or the like.

A gap 36 is formed between the side panels 33 . In this case, each side panel 33 is formed in a trapezoidal shape. Each side panel 33 also has a pair of side edges 33a extending from the bottom panel 31 respectively. A gap 36 is formed between the side edges 33 a of the side panel 33 . As a result, in the paper container 10 described above, the side portions 23 do not overlap and are adjacent to each other (see FIGS. 5 and 6). In the illustrated example, the pair of side edges 33a of each side panel 33 extend away from each other from the first folding line 32 side toward the second folding line 34 side.

As the paper material that constitutes the blank material 30, for example, processed paper such as various paperboards, coated paper, card paper, ivory paper, milk carton base paper, cup base paper, and coated board can be used. The basis weight of the paper material is, for example, 150 g/m ² or more and 600 g/m ² or less.

(molding film)
Next, the molded film 40 will be described with reference to FIGS. 4 to 6. FIG. This molded film 40 serves to protect the paper container 20 . The molded film 40 has a container shape and covers the entire surface of the paper container 20 . This prevents the content filled in the paper container 10 from leaking out of the paper container 10 . The molded film 40 is adhered to the paper container 20 by, for example, heat sealing (thermal welding).
Formed film 40 is formed from laminated film 40a of the present disclosure.

(lid material)
Next, the lid member 50 will be described. The lid member 50 is sealed over the entire periphery of the formed film 40 of the paper container 10 , for example, in a region corresponding to the flange piece 25 .

Such a lid material 50 includes, for example, PET/sealant, oriented nylon (ONY)/sealant, PET/oriented nylon (ONY)/sealant, PET/PE/sealant, K-coated oriented nylon (KONY)/PE/sealant, A laminate having a layer structure such as the following can be used. Also, the laminate constituting the lid member 50 may be, for example, a laminate obtained by laminating a gas barrier material such as ethylene-vinyl alcohol copolymer (EVOH) on a molding layer. For the lid member 50, for example, a laminate having a layer structure such as PET/PE/ethylene-vinyl alcohol copolymer (EVOH)/PE/sealant can be used.

The lid member 50 may be made of, for example, a laminate having the following layer structure.
(Outside) Polyethylene terephthalate film with transparent vapor deposition layer (12 μm)/Nylon film (15 μm)/Polyethylene film (40 μm) (Inside)

It should be noted that it is preferable to use a resin material capable of exhibiting so-called easy-peel properties for the laminate constituting the lid member 50 . Each of the above layers is formed by a dry lamination method, an extrusion lamination method, an extrusion coating method, or other coating method according to a conventional method.

In the lid-equipped paper container 1 having such a configuration, the contents are first filled into the paper container 10 . Next, the cover material 50 is sealed to the area corresponding to the flange piece 25 in the formed film 40 of the paper container 10 . As a result, the lid-attached paper container 1 filled with the contents is obtained. Note that the paper container 1 with a lid may be a container for chilled foods or frozen foods, or may be used as a take-out container. Also, the contents may be foods such as side dishes, meat, and dairy products.

Next, the operation of this embodiment having such a configuration will be described. Here, a method for manufacturing the paper container 10 and a method for manufacturing the lid-attached paper container 1 will be described with reference to FIGS. 8 to 10. FIG.

(Manufacturing method of paper container)
First, a blank material 30 is prepared. At this time, first, a paper material is prepared, and a heat sealing agent is applied to predetermined positions of the paper material. The heat sealing agent may be applied by a gravure printing method, a flexographic printing method, an offset printing method, or the like. In this manner, the heat seal layer H is provided at a predetermined position on the paper material. Next, the blank material 30 is obtained by punching out the paper material with a laser or the like.

Next, as shown in FIG. 8, the blank material 30 is attached to the cavity-side mold 60 . A suction hole 61 is formed in the cavity side mold 60 , and the blank material 30 is attached to the cavity side mold 60 by sucking air from the suction hole 61 . At this time, the side panel 33 of the blank 30 is folded against the bottom panel 31 along the first folding line 32 . Similarly, flange strip panel 35 of blank 30 is folded against side panel 33 along second fold line 34 . As a result, the paper container 20 attached to the cavity side mold 60 is obtained.

Next, the formed film 40 is laminated on the surface of the paper container 20 . At this time, first, as shown in FIG. 9, the laminated film 40a constituting the molded film 40 is arranged above the paper container 20. Then, as shown in FIG. Next, the laminated film 40a is heated by the core-side mold 62 (see FIG. 10). After the laminated film 40 a is sufficiently heated by the core-side mold 62 , air is sucked through the suction holes 61 . As a result, the laminated film 40a is sucked onto the paper container 20. As shown in FIG. Also, at this time, the core-side mold 62 presses the laminated film 40 a against the paper container 20 . As a result, the laminated film 40 a adheres to the paper container 20 .

After that, the laminated film 40a is cut into a desired shape by a cutting mechanism 63 provided on the core-side mold 62 . Thereby, as shown in FIG. 10, the molded film 40 laminated on the paper container 20 is obtained. Thus, the paper container 10 is obtained.

In parallel with the production of the paper container 10, the lid member 50 is prepared. At this time, a predetermined laminate is produced by a dry lamination method or the like. After that, the lid member 50 is manufactured by punching out the laminate into a predetermined shape with a knife or the like.

Next, the paper container 10 is filled with contents, and the paper container 10 is sealed with the lid member 50 . At this time, first, the paper container 10 is filled with contents (not shown). Next, the lid member 50 is placed on the molded film 40 at a position corresponding to the flange piece 25 .

Next, the lid member 50 is sealed to the forming film 40 by a hot sealing plate or the like (not shown). At this time, the air in the paper container 10 may be replaced with, for example, nitrogen gas.

In this way, the paper container 1 with a lid, which includes the paper container 10 and the lid 50 that seals the paper container 10, is obtained.

As described above, according to the present embodiment, the adhesive strength between the flange piece 25 and the forming film 40 may be, for example, 1.0 N/15 mm or more. As a result, when the lid member 50 is removed from the paper container 10 of the paper container 1 with lid member, it is possible to prevent the formed film 40 from peeling off from the flange piece 25 . For this reason, it is possible to suppress the deterioration of the openability of the lid member 50 . In addition, since it is possible to suppress deterioration in the openability of the lid member 50 , it is possible to suppress deformation of the paper container 10 when the lid member 50 is removed from the paper container 10 . Therefore, the practicality of the lid-equipped paper container 1 can be improved.

Moreover, according to the present embodiment, the adhesive strength between the bottom portion 21 and the molding film 40 and the adhesive strength between the side portion 23 and the molding film 40 are, for example, 0.05 N/15 mm or more and 0.05 N/15 mm or more, respectively. It may be 4N/15mm or less. As a result, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20 . In particular, when removing the lid member 50 from the paper container 10 , it is possible to prevent the molded film 40 from unintentionally peeling off from the bottom portion 21 or the side portion 23 of the paper container 20 . Moreover, when recycling the paper container 20, the paper container 20 and the formed film 40 can be easily separated.

Moreover, since it can suppress that the molded film 40 peels from the paper container 20 unintentionally, the airtightness of the paper container 1 with a cover material can be improved. That is, if the molded film 40 is unintentionally peeled off from the paper container 20, the paper container 20 may not be able to retain its shape as a container, and the paper container 20 may buckle. In this case, an unintended force may be applied to the lid member 50 and the formed film 40 , and the lid member 50 may be unintentionally removed from the paper container 10 . On the other hand, in the present embodiment, it is possible to prevent the molded film 40 from being unintentionally peeled off from the paper container 20, so that it is possible to prevent the lid member 50 from being unintentionally removed from the paper container 10. can. Therefore, it is possible to improve the airtightness of the lid-equipped paper container 1 . As a result, the barrier property of the lid-equipped paper container 1 can be improved, and the life of the contents can be extended. Therefore, food loss can be reduced.

Moreover, according to the present embodiment, the adhesive strength between the flange piece 25 and the forming film 40 may be, for example, 5.0 N/15 mm or less. As a result, it is possible to prevent difficulty in peeling off the formed film 40 from the paper container 20 when recycling the paper container 20 .

Furthermore, according to this embodiment, the heat seal layer H is provided on the flange piece 25 . Thereby, the adhesive strength between the flange piece 25 and the forming film 40 can be easily adjusted. Therefore, desired adhesive strength can be easily obtained.

<Modified example of paper container>
Next, modified examples of the paper container 10 according to the present embodiment will be described with reference to FIGS. 11 to 18. FIG. 11 to 18, the same parts as in the embodiment shown in FIGS. 4 to 10 are denoted by the same reference numerals, and detailed description thereof will be omitted.

(First modification of paper container)
In the embodiment described above, an example in which the heat seal layer H is provided on the flange piece 25 (flange piece panel 35) has been described, but the present invention is not limited to this. For example, as shown in FIG. 11, the heat seal layer H may be provided along the periphery of the bottom portion 21 (that is, along the fold line 22). That is, the heat sealing agent may be applied onto the bottom portion 21 along the periphery of the bottom portion 21 (that is, the fold line 22). In this case, as shown in FIG. 12, in the blank material 30, the heat seal layer H may be provided along the periphery of the bottom panel 31 (that is, the first folding line 32). That is, in the blank 30 , the heat sealing agent may be applied onto the bottom panel 31 along the periphery of the bottom panel 31 (that is, the first folding line 32 ).

Here, a gap is likely to be formed between the paper container 20 and the formed film 40 near the periphery of the bottom portion 21 . Therefore, there is a possibility that the formed film 40 may be unintentionally separated from the paper container 20 triggered by the vicinity of the periphery of the bottom portion 21 .

On the other hand, since the heat sealing agent is applied on the bottom portion 21 along the periphery of the bottom portion 21, the adhesive strength between the paper container 20 and the formed film 40 is increased in the vicinity of the periphery of the bottom portion 21. be able to. Therefore, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20 .

In this case, the application amount of the heat sealing agent applied on the bottom portion 21 (bottom panel 31) may be 0.1 g/m ² or more and 10.0 g/m ² or less. Since the coating amount of the heat sealing agent applied to the bottom part 21 (bottom panel 31) is 0.1 g/m ² or more, the adhesive strength between the bottom part 21 and the forming film 40 can be easily increased to a desired level. You can make it bigger. Therefore, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20 . In addition, when the amount of the heat sealing agent applied to the bottom portion 21 (bottom panel 31) is 10.0 g/m ² or less, the adhesive strength between the bottom portion 21 and the forming film 40 becomes too large. can be suppressed. Therefore, it is possible to prevent difficulty in peeling off the formed film 40 from the paper container 20 when recycling the paper container 20 .

(Second modification of paper container)
Further, as shown in FIG. 13 , the heat seal layer H may be provided on the bottom portion 21 and the side portions 23 so as to straddle the fold line 22 . That is, the heat sealing agent may be applied on the bottom portion 21 and the side portions 23 so as to straddle the fold line 22 . In this case, as shown in FIG. 14 , in the blank material 30 , the heat seal layer H may be provided on the bottom panel 31 and the side panels 33 so as to straddle the first folding line 32 . That is, in the blank material 30 , the heat sealing agent may be applied on the bottom panel 31 and the side panels 33 so as to straddle the first folding line 32 . Also in this case, the adhesion strength between the paper container 20 and the formed film 40 can be increased in the vicinity of the periphery of the bottom portion 21 (that is, the folding line 22). Therefore, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20 .

In this case, the amount of the heat sealing agent applied on the bottom portion 21 (bottom panel 31) and/or the side portion 23 (side panel 33) is 0.1 g/m ² or more and 10.0 g/m ² or less. may be The application amount of the heat sealing agent applied on the bottom part 21 (bottom panel 31) and/or the side part 23 (side panel 33) is 0.1 g/m ² or more, so that the bottom part 21 and/or the side parts The adhesive strength between the portion 23 and the forming film 40 can be easily increased to a desired strength. Therefore, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20 . In addition, the application amount of the heat sealing agent applied on the bottom portion 21 (bottom panel 31) and/or the side portion 23 (side panel 33) is 10.0 g/m ² or less, so that the bottom portion 21 and/or Alternatively, it is possible to prevent the adhesive strength between the side portion 23 and the molded film 40 from becoming too large. Therefore, it is possible to prevent difficulty in separating the formed film 40 from the paper container 20 when the paper container 20 is recycled.

(Third modification of paper container)
Furthermore, as shown in FIG. 15, a heat seal layer H may be provided on the bottom portion 21, the side portions 23, and the flange piece 25. As shown in FIG. That is, the heat sealing agent may be applied on the bottom portion 21 , the side portions 23 and the flange pieces 25 . In the illustrated example, the heat sealant is applied to the entire surface of the paper container 20 . Further, the weight per unit area of the heat seal layer H provided on the flange piece 25 may be larger than the weight per unit area of the heat seal layer H provided on the side portion 23 . That is, the amount of the heat sealing agent applied onto the flange piece 25 may be greater than the amount of the heat sealing agent applied onto the side portion 23 . Furthermore, the weight per unit area of the heat seal layer H provided on the side portion 23 may be greater than the weight per unit area of the heat seal layer H provided on the bottom portion 21 . That is, the amount of the heat-sealing agent applied onto the side portion 23 may be greater than the amount of the heat-sealing agent applied onto the bottom portion 21 .

In this case, as shown in FIG. 16, in the blank 30, the heat sealing agent may be applied on the bottom panel 31, the side panels 33, and the flange panel 35. FIG. In the illustrated example, the heat sealing agent is applied to the entire surface of the blank 30 . Further, the weight per unit area of the heat seal layer H provided on the flange piece panel 35 may be greater than the weight per unit area of the heat seal layer H provided on the side panel 33. . That is, the amount of heat sealing agent applied onto the flange piece panel 35 may be greater than the amount of heat sealing agent applied onto the side panel 33 . Further, the weight per unit area of the heat seal layer H provided on the side panel 33 may be greater than the weight per unit area of the heat seal layer H provided on the bottom panel 31 . That is, the amount of heat sealing agent applied onto the side panel 33 may be greater than the amount of heat sealing agent applied onto the bottom panel 31 .

According to this modification, in the paper container 10, the adhesive strength between the paper container 20 and the formed film 40 can be easily adjusted. Therefore, desired adhesive strength can be easily obtained.

Here, in order to improve the openability of the lid member 50, it is preferable to increase the adhesive strength between the flange piece 25 and the formed film 40. FIG. On the other hand, in order to improve the recyclability of the paper container 20, it is preferable to reduce the adhesive strength between the side portion 23 and the forming film 40 and the adhesive strength between the bottom portion 21 and the forming film 40. However, when the adhesive strength between the side portion 23 and the formed film 40 and the adhesive strength between the bottom portion 21 and the formed film 40 are reduced, when the lid member 50 is removed from the paper container 10 , the formed film 40 may unintentionally detach from the bottom 21 or side 23 of the paper container 20 . In particular, when the adhesive strength between the side portion 23 and the formed film 40 is reduced, the portion of the formed film 40 that is adhered to the side portion 23 may be used as a trigger when removing the lid member 50 from the paper container 10 . As a result, the formed film 40 can be easily peeled off from the paper container 20 . Therefore, in order to improve the recyclability of the paper container 20 while improving the ease of opening the lid member 50, the adhesive strength between the flange piece 25 and the forming film 40 must be increased to The adhesive strength between the side portion 23 and the forming film 40 is such that the adhesive strength between the side portion 23 and the forming film 40 is greater than the adhesive strength between the It is preferably greater than the adhesive strength between bottom 21 and forming film 40 .

In this modification, the amount of heat sealing agent applied onto the flange piece 25 is greater than the amount of heat sealing agent applied onto the side portion 23, and the amount of heat sealing agent applied onto the side portion 23 is is larger than the amount of the heat sealing agent applied onto the bottom portion 21 . Therefore, the adhesive strength between the flange piece 25 and the forming film 40 can be made greater than the adhesive strength between the side portion 23 and the forming film 40, and the adhesion strength between the side portion 23 and the forming film 40 can be increased. The bond strength can be greater than the bond strength between bottom 21 and forming film 40 . Thereby, when the lid member 50 is removed from the paper container 10 , it is possible to prevent the formed film 40 from peeling off from the flange piece 25 , the side portion 23 and the bottom portion 21 of the paper container 20 . Moreover, when recycling the paper container 20, the paper container 20 and the formed film 40 can be easily separated. For this reason, it is possible to suppress deterioration in the ease of opening the lid member 50 , and to easily separate the paper container 20 and the formed film 40 when recycling the paper container 20 .

In addition, as shown in FIGS. 17 and 18, the heat sealing agent may be applied in a predetermined pattern on the entire surface of the blank material 30 . For example, as shown in FIG. 17, the heat sealing agent may be applied to the surface of the blank material 30 in a polka dot pattern. Further, as shown in FIG. 18, the heat sealing agent may be applied on the surface of the blank material 30 in stripes. In addition, the pattern shape which a heat-sealing agent comprises is not specifically limited. Although not shown, the heat-sealing agent may be applied to the surface of the blank 30 so that the area where the heat-sealing agent is not applied exhibits a polka dot pattern. The heat sealing agent may be applied to the surface of the blank material 30 so as to present another pattern such as a checkerboard pattern, or may be applied to the surface of the blank material 30 in a grid pattern. At this time, although not shown, the paper container 20 made from the blank material 30 is also coated with the heat sealing agent on the entire surface of the paper container 20 in a predetermined pattern. In addition, the heat sealing agent may be applied to a part of the surface of the blank material 30 in a predetermined pattern.

(Fourth modification of paper container)
Further, in the above-described embodiment, an example in which the adhesive strength between the paper container 20 and the formed film 40 is adjusted by providing the heat seal layer H (applying the heat sealant) to the surface of the paper container 20 Illustrated, but not limited to. For example, the adhesive strength may be adjusted by changing the temperature at which the molded film 40 is heated. That is, the heating temperature of the molded film 40 may be increased to increase the adhesive strength. On the other hand, if it is desired to reduce the adhesive strength, the heating temperature of the molded film 40 may be lowered. Also in this case, the adhesion strength between the paper container 20 and the formed film 40 can be easily adjusted. The adhesive strength between the paper container 20 and the molded film 40 may be adjusted by changing the pressure or time when the core-side mold 62 presses the laminated film 40 a against the paper container 20 .

The present disclosure is not limited to the above-described embodiment and modifications as they are, and can be embodied by modifying constituent elements without departing from the gist of the present disclosure at the implementation stage. Also, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiment and modifications. Some components may be deleted from all the components shown in the embodiment and each modification.

The present disclosure relates to, for example, the following [1] to [11].
[1] A first surface layer, a gas barrier layer, and an adhesive layer as a second surface layer are provided in this order, and the gas barrier layer has a melting point of 175° C. or less and contains 35 mol of ethylene-derived structural units. % or more of a gas barrier resin.
[2] The laminated film of [1] above, wherein the gas barrier resin is an ethylene-vinyl alcohol copolymer.
[3] The laminated film according to [1] or [2] above, wherein the content of the gas barrier resin in the gas barrier layer is 80% by mass or more with respect to the total mass of the gas barrier resin layer.
[4] The laminated film according to any one of [1] to [3] above, wherein the first surface layer contains polyolefin.
[5] The laminated film according to any one of [1] to [4] above, wherein the adhesive layer contains a modified polyolefin.
[6] An intermediate layer containing at least one resin selected from ionomer resins, ethylene-(meth)acrylic acid copolymers and ethylene-vinyl acetate copolymers, between the first surface layer and the gas barrier layer. The laminated film according to any one of [1] to [5] above, further comprising:
[7] The laminated film according to [6] above, further comprising an interlayer adhesion layer containing a modified polyolefin between the intermediate layer and the gas barrier layer.
[8] The laminated film according to any one of [1] to [7] above, which has an oxygen permeability of 20 cc/m ² ·day·atm or less under conditions of 23°C and 65% RH.
[9] The laminated film according to any one of [1] to [8] above, which is to be adhered to a paper container.
[10] A paper container and a formed film laminated on the surface of the paper container, wherein the formed film is formed from the laminated film according to any one of [1] to [9] above, and the laminated film A laminated paper container in which an adhesive layer is in contact with the surface of the paper container.
[11] A lidded container comprising the laminated paper container according to [10] above and a lid for sealing the laminated paper container.

The laminated film of the present disclosure will be specifically described below based on Examples, but the laminated film of the present disclosure is not limited by the Examples.

[Preparation of laminated film]
The materials used to prepare the laminated film are described below.

Linear low density polyethylene (LLDPE)
Density: 0.926 g/cm ³ , MFR: 1.7 g/10 minutes, Melting point: 127° C., manufactured by Japan Polyethylene Co., Ltd., trade name: Harmolex NF384A
High pressure low density polyethylene (LDPE)
Density: 0.919 g/cm ³ , MFR: 2.0 g/10 minutes, Melting point: 108°C, manufactured by Japan Polyethylene Co., Ltd., trade name: Novatec LD LF405

Ionomer Ion type: Na ⁺ , Density: 0.940 g/cm ³ , MFR: 1.3 g/10 min, Melting point: 97°C, Mitsui-Dow Polychemicals Co., Ltd., Trade name: Himilan 1601

Adhesive resin Acid-modified polyethylene (acid-modified PE), density: 0.903 g/cm ³ , MFR: 1.7 g/10 min, manufactured by Mitsui Chemicals, Inc., trade name: Admer NF557

Gas barrier resin Ethylene-vinyl alcohol copolymer, density: 1.140 g/cm ³ , MFR: 2.5 g/10 min, melting point: 165°C, crystallization temperature: 145°C, ethylene copolymerization ratio: 44 mol%, Kuraray Co., Ltd., trade name: EVAL E173B
Gas barrier resin Ethylene-vinyl alcohol copolymer, density: 1.130 g/cm ³ , MFR: 1.9 g/10 min, melting point: 165°C, crystallization temperature: 143°C, ethylene copolymerization ratio: 44 mol%, Kuraray Co., Ltd., trade name: EVAL SP292B
Gas barrier resin Ethylene-vinyl alcohol copolymer, density: 1.16 g/cm ³ , MFR: 2.0 g/10 min, melting point: 160°C, crystallization temperature: 134°C, ethylene copolymerization ratio: 38 mol%, Kuraray Co., Ltd., trade name: EVAL XEP-1393B
Gas barrier resin Ethylene-vinyl alcohol copolymer, density: 1.06 g/cm ³ , MFR: 1.8 g/10 min, melting point: 183°C, crystallization temperature: 158°C, ethylene copolymerization ratio: 32 mol%, Kuraray Co., Ltd., trade name: EVAL FS201B

Masterbatch containing anti-blocking agent (AB agent) containing 4% by mass of silica, density: 0.949 g/cm ³ , MFR: 1.6 g/10 min, manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumikasen A-20

[Preparation of laminated film (A)]
A mixture of 60% by mass of LLDPE (Hermolex NF384A) and 40% by mass of LDPE (Novatec LD LF405) as the first surface layer,
Ionomer (Himilan 1601) as a molding layer,
Adhesive resin (ADMER NF557) as an interlayer adhesion layer,
A gas barrier resin (EVAL E173B) as a barrier layer, and a mixture of 95% by mass of an adhesive resin (ADMER NF557) and 5% by mass of an anti-blocking agent-containing masterbatch (Sumikasen A-20) as an adhesive layer (second surface layer). of,
A laminated film having a thickness of 100 μm and having a first surface layer, a molding layer, an interlayer adhesive layer, a barrier layer and an adhesive layer in this order was obtained by co-extrusion film formation by an inflation molding method. The thickness of the first surface layer is 20 μm, the thickness of the molding layer is 30 μm, the thickness of the interlayer adhesion layer is 20 μm, the thickness of the barrier layer is 10 μm, and the thickness of the adhesive layer is 20 μm. The adhesive layer surface of the laminated film was subjected to corona treatment, and the wet tension was adjusted to 48 mN/m. Thus, a laminated film (A) was obtained.

[Preparation of laminated films (B) to (C) and (E)]
Laminated films (B) to (C) and (E) were produced in the same manner as [Preparation of laminated film (A)] except that the composition of the barrier layer was changed as shown in Table 1.

[Production of laminated film (D)]
A mixture of 60% by mass of LLDPE (Hermolex NF384A) and 40% by mass of LDPE (Novatec LD LF405) as the first surface layer,
Ionomer (Himilan 1601) as molding layer 1,
Adhesive resin (ADMER NF557) as the interlayer adhesion layer 1,
Gas barrier resin (EVAL XEP-1393B) as a barrier layer,
Adhesive resin (ADMER NF557) as the interlayer adhesion layer 2,
An ionomer (Himilan 1601) was used as the molding layer 2, and a mixture of 95% by mass of an adhesive resin (Admer NF557) and 5% by mass of an anti-blocking agent-containing masterbatch (Sumikasen A-20) was used as an adhesive layer (second surface layer). ,
A laminated film having a thickness of 100 μm, which is formed by coextrusion by an inflation molding method and comprises a first surface layer, a molding layer 1, an interlayer adhesion layer 1, a barrier layer, an interlayer adhesion layer 2, a molding layer 2 and an adhesion layer in this order. Obtained. The first surface layer has a thickness of 20 μm, the molding layer 1 has a thickness of 15 μm, the interlayer adhesion layer 1 has a thickness of 10 μm, the barrier layer has a thickness of 10 μm, the interlayer adhesion layer 2 has a thickness of 10 μm, and the molding layer 2 has a thickness of 10 μm. is 15 μm, and the thickness of the adhesive layer is 20 μm. The adhesive layer surface of the laminated film was subjected to corona treatment, and the wet tension was adjusted to 48 mN/m. Thus, a laminated film (D) was obtained.

[Production of laminated film (F)]
A mixture of 60% by mass of LLDPE (Hermolex NF384A) and 40% by mass of LDPE (Novatec LD LF405) as the first surface layer,
LLDPE (Hermolex NF384A) as the polyethylene layer 1,
Ionomer (Himilan 1601) as a molding layer,
LLDPE (Hermolex NF384A) as the polyethylene layer 2, and a mixture of 95% by mass of adhesive resin (Admer NF557) and 5% by mass of antiblocking agent-containing masterbatch (Sumikasen A-20) as the adhesive layer (second surface layer). of,
A laminated film having a thickness of 100 μm was obtained by co-extrusion film formation by an inflation molding method, comprising a first surface layer, a polyethylene layer 1, a molding layer, a polyethylene layer 2 and an adhesive layer in this order. The thickness of the first surface layer is 20 μm, the thickness of the polyethylene layer 1 is 15 μm, the thickness of the molding layer is 30 μm, the thickness of the polyethylene layer 2 is 15 μm, and the thickness of the adhesive layer is 20 μm. The adhesive layer surface of the laminated film was subjected to corona treatment, and the wet tension was adjusted to 48 mN/m. Thus, a laminated film (F) was obtained.

[evaluation]
A laminated film obtained in an example or a comparative example and a paper container (120 mm×160 mm×30 mm (height)) were prepared. The paper container was produced using base paper (N Pearl Card, manufactured by Mitsubishi Paper Mills, Ltd.) with a basis weight of 260 g/m ² . Using a vacuum forming machine, the laminated film was arranged so that the adhesive layer of the laminated film was in contact with the surface of the paper container, and the laminated film was adhered to the paper container. The molding conditions were a heating temperature of 150° C. and a heating time of 3 s. In this way, a laminated paper container including a paper container and a formed film formed in the shape of the paper container as shown in FIG. 19 was produced.

<Followability>
The conformability of the laminated film to the paper container was evaluated based on the appearance. "◯" means that the laminated film adheres well to the shape of the paper container, and has high conformability to the paper container. "X" indicates that the laminated film does not sufficiently follow the shape of the paper container, the laminated film does not adhere to a part of the paper container (such as the corner part), and the conformability to the paper container is low. means

<Gas barrier property>
In order to evaluate the gas barrier property of the container, the oxygen permeability (cc/m ² ·day·atm) was measured under conditions of 23°C and 40% RH by the container method. In order to evaluate the humidity dependence of the gas barrier properties of the laminated film, measurements were carried out under conditions of 23° C. and 65% RH and 23° C. and 90% RH by the film method. Using an oxygen permeation measuring device (OX-TRAN2/20, manufactured by MOCON), the adhesive layer of the laminated film was set to the oxygen supply side, and the measurement was performed according to JIS K7126-2. The container method was also measured according to JIS K7126-2.

A laminated film having a barrier layer containing a gas barrier resin having a melting point of 175°C or less and an ethylene copolymerization ratio of 35 mol% or more has good gas barrier properties and poor followability in low temperature molding (150°C). Excellent (Examples 1-3). Moreover, when the gas barrier resin is used, it does not depend on the number of film layers (Examples 3 and 4). A laminated film having a barrier layer containing a gas barrier resin having a melting point of 183° C. and an ethylene copolymerization ratio of 32 mol % has excellent gas barrier properties, but does not have sufficient conformability in low-temperature molding. (Comparative Example 1). A laminated film without a barrier layer has excellent conformability in low-temperature molding, but does not have gas barrier properties (Comparative Example 2).

REFERENCE SIGNS LIST 10 paper container 20 paper container 21 bottom 22 folding line 23 side 24 folding line 25 flange piece 40 forming film H heat seal layer 100 laminated film 110 first surface layer 112, 112a, 112b intermediate layer (molding layer)
114, 114a, 114b interlayer adhesion layer 116 gas barrier layer 118 adhesion layer (second surface layer)

Claims (11)

A first surface layer, a gas barrier layer, and an adhesive layer as a second surface layer in this order,
The gas barrier layer contains a gas barrier resin having a melting point of 175° C. or less and a content of ethylene-derived structural units of 35 mol % or more.
laminated film. The laminated film according to claim 1, wherein the gas barrier resin is an ethylene-vinyl alcohol copolymer. The laminated film according to claim 1 or 2, wherein the content of the gas barrier resin in the gas barrier layer is 80% by mass or more with respect to the total mass of the gas barrier resin layer. The laminated film according to any one of claims 1 to 3, wherein the first surface layer contains polyolefin. The laminated film according to any one of claims 1 to 4, wherein the adhesive layer contains modified polyolefin. Between the first surface layer and the gas barrier layer,
6. The intermediate layer according to any one of claims 1 to 5, further comprising an intermediate layer containing at least one resin selected from ionomer resins, ethylene-(meth)acrylic acid copolymers and ethylene-vinyl acetate copolymers. Laminated film as described. 7. The laminated film according to claim 6, further comprising an interlayer adhesion layer containing modified polyolefin between said intermediate layer and said gas barrier layer. The laminated film according to any one of claims 1 to 7, which has an oxygen permeability of 20 cc/m ² ·day·atm or less under conditions of 23°C and 65% RH. The laminated film according to any one of claims 1 to 8, which is for adhesion molding to a paper container. a paper container;
A formed film laminated on the surface of the paper container,
The molded film is molded from the laminated film according to any one of claims 1 to 9, and the adhesive layer of the laminated film is in contact with the surface of the paper container.
Laminated paper container. A laminated paper container according to claim 10;
A container with a lid, comprising a lid that seals the laminated paper container.