Laminated film, laminate paper container, and container with lid material

Abstract

To provide a laminated film excellent in molding suitability and heat resistance.SOLUTION: The laminated film includes a first surface layer and an adhesive layer as a second surface layer in this order. The first surface layer contains a polyolefin having a density of 0.940 g / cm3 or less and has a thickness of 13 μm or more. The laminated film has a thermal shrinkage rate in a machine direction of 0.1% or more and 8.5% or less when heated under an atmosphere of 150°C and 50% RH for 10 minutes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminated film, a laminated paper container, and a container with a lid. [Background technology]

[0002] In recent years, environmental issues such as marine pollution caused by plastics have become a major social challenge. In the packaging field, from the perspective of environmental considerations, there is a demand to reduce the amount of plastic used in packaging materials, switch from plastic containers to paper containers, and improve recyclability. Paper containers can reduce the volume of waste and are attracting attention as an alternative to plastic containers.

[0003] In order to improve the shelf life of the contents of a paper container, a film with gas barrier properties is laminated to the inner surface of the paper container (see Patent Document 1). By peeling the laminated film from the paper container, the paper container and the film can be separated and disposed of, making it highly recyclable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-146996 Summary of the Invention [Problem to be solved by the invention]

[0005] Containers that integrate a paper container and a film have attracted attention as food packaging containers, and are required to be adaptable to microwave heating when filled with chilled prepared foods or frozen foods. When laminating a film to the inner surface of a paper container, the film is heated to soften it and then adhered to the container using a forming method such as vacuum forming or pressure forming. Conventional films use resins and layer structures with high heat shrinkability to prevent wrinkles or uneven heating during forming. However, when such films are used to heat the contents in a microwave oven, the heat can cause the film to shrink, leading to peeling from the paper container. Therefore, a laminated film that is excellent in formability and has excellent heat resistance, for example, suitable for microwave heating, has not yet been realized.

[0006] An object of the present disclosure is to provide a laminated film that is excellent in formability and heat resistance. [Means for solving the problem]

[0007] The laminated film of the present disclosure comprises a first surface layer and an adhesive layer as a second surface layer in this order, and the first surface layer has a density of 0.940 g / cm 3 The laminated film contains the following polyolefin, has a thickness of 13 μm or more, and has a heat shrinkage rate of 0.1% or more and 8.5% or less in the machine direction when heated in an atmosphere of 150°C and 50% RH for 10 minutes. [Effects of the Invention]

[0008] According to the present disclosure, a laminate film having excellent formability and heat resistance can be provided. The laminate film of the present disclosure can be applied not only to paper containers but also to various adherends. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of one embodiment of a laminated film. [Figure 2] FIG. 2 is a schematic cross-sectional view of one embodiment of the laminated film. [Figure 3]FIG. 3 is a schematic cross-sectional view of one embodiment of the laminated film. [Figure 4] FIG. 4 is a vertical cross-sectional view showing a paper container with a lid according to one embodiment. [Figure 5] FIG. 5 is a perspective view showing a paper container according to one embodiment. [Figure 6] FIG. 6 is a plan view showing a paper container according to one embodiment. [Figure 7] FIG. 7 is a development view showing a blank material for producing a paper container according to one embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a method for manufacturing a paper container according to one embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a method for manufacturing a paper container according to one embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a method for manufacturing a paper container according to one embodiment. [Figure 11] FIG. 11 is a perspective view showing a first modified example of a paper container according to an embodiment. [Figure 12] FIG. 12 is a development view showing a blank material for producing the first modified example. [Figure 13] FIG. 13 is a perspective view showing a second modified example of the paper container of the embodiment. [Figure 14] FIG. 14 is a development view showing a blank material for producing the second modified example. [Figure 15] FIG. 15 is a perspective view showing a third modified example of the paper container of one embodiment. [Figure 16] FIG. 16 is a development view showing a blank material for producing the third modified example. [Figure 17] FIG. 17 is a development view showing another example of a blank for producing the third modified example. [Figure 18] FIG. 18 is a development view showing another example of a blank for producing the third modified example. [Figure 19] FIG. 19 is a vertical cross-sectional view showing a paper container according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present embodiment will be described below with reference to the drawings. The figures shown below are schematic illustrations. Therefore, the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, appropriate modifications can be made within the scope of the technical concept. In the figures shown below, identical parts are designated by the same reference numerals, and some detailed descriptions may be omitted. Furthermore, the numerical values, such as dimensions, and material names of each component described in this specification are merely examples of an embodiment and are not limited thereto. They may be selected and used as appropriate. In this specification, terms specifying shape or geometric conditions, such as parallel, orthogonal, and vertical, are intended to include not only their strict meanings but also substantially the same states. In this specification, "top" and "bottom" may refer to the upper and lower sides of a paper container in an upright position (see FIG. 4), respectively. In this specification, "surface" may refer to the surface facing the contents or the surface facing upward when the paper container is upright.

[0011] In the following description, each of the components (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) may be used either singly or in combination of two or more types.

[0012] [Laminated film] The laminated film of the present disclosure comprises a first surface layer and an adhesive layer as a second surface layer in this order. The first surface layer has a density of 0.940 g / cm 3 It contains the following polyolefin and has a thickness of 13 μm or more. The heat shrinkage rate of the laminated film when heated for 10 minutes in an atmosphere of 150°C and 50% RH is 0.1% or more and 8.5% or less.

[0013] The laminate film of the present disclosure can be molded at a molding temperature of, for example, 140°C or higher and 180°C or lower, with the occurrence of wrinkles and heating unevenness on the film surface suppressed, and has excellent moldability (molding processability). The laminate film of the present disclosure has excellent heat resistance, and is adaptable to, for example, microwave heating, and can suppress peeling from the adherend due to thermal shrinkage and foaming even after microwave heating. Therefore, the laminate film of the present disclosure is suitable as a laminate film for paper containers, and is particularly suitable as a laminate film for paper containers that are adaptable to microwave ovens.

[0014] The laminate film may further include a gas barrier layer that imparts excellent gas barrier properties to the film. The laminate film may further include an intermediate layer that imparts excellent moldability to the film. The laminate film may further include an interlayer adhesion layer that improves adhesion between the intermediate layer and the gas barrier layer, for example.

[0015] 1 to 3 show one embodiment of the laminated film of the present disclosure. 1 includes a first surface layer 110 and an adhesive layer 118 as a second surface layer, in this order. In the laminate film 100, the first surface layer 110 is one of the outermost layers, and the adhesive layer 118 is the other outermost layer. When the laminate film 100 is attached to an adherend such as a paper container, the adhesive layer 118 is the layer that comes into contact with the adherend.

[0016] The laminated film 100 in Fig. 2 includes, in this order, a first surface layer 110, an intermediate layer 112, an interlayer adhesion layer 114, a gas barrier layer 116, and an adhesive layer 118 serving as a second surface layer. The laminated film 100 in Fig. 3 includes, in this order, 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 intermediate layer 112b, and an adhesive layer 118 serving as a second surface layer.

[0017] The laminate film of the present disclosure has a heat shrinkage of 0.1% to 8.5%, where the heat shrinkage refers to the heat shrinkage in the machine direction (MD) of the laminate film when the laminate film is placed in an atmosphere of 150°C and 50% RH and heated for 10 minutes.

[0018] The heat shrinkage rate is measured as follows: First, a laminated film (sample) measuring 100 mm x 100 mm is prepared. The sample is heated in a thermostatic chamber at 150°C and 50% RH for 10 minutes, and the dimensional change rate is calculated using the following formula. Dimensional change rate (%) = 100 × (L o -L) / L o L o is the sample length in the machine direction before testing, and L is the sample length after testing. This dimensional change rate is defined as the thermal shrinkage rate of the laminated film.

[0019] The heat shrinkage rate of the laminate film of the present disclosure is 0.1% or more and 8.5% or less, preferably 0.5% or more and 7.0% or less, and more preferably 0.7% or more and 5.0% or less. A heat shrinkage rate of 0.1% or more allows the laminate film to exhibit excellent moldability. A heat shrinkage rate of 8.5% or less allows the laminate film to exhibit excellent heat resistance suitable for microwave heating, and, for example, can suppress peeling from an adherend due to heat shrinkage even after microwave heating. For example, the heat shrinkage rate can be adjusted by adjusting the content of the highly heat-shrinkable resin in the first layer and the thickness of the first layer.

[0020] <First Surface> The laminated film of the present disclosure includes a first surface layer. In one embodiment, the first surface layer contains a polyolefin. From the viewpoint of moldability such as low-temperature moldability, the polyolefin has a density of 0.940 g / cm. 3 Preferably, the polyolefin has a density of 0.936 g / cm 3 The following polyolefins are more preferred: The density of the polyolefin is measured in accordance with JIS K7112, particularly method B or D (23°C). Polyolefin is a polymer having at least structural units derived from an olefin, and may have only structural units derived from an olefin, or may have structural units derived from an olefin and structural units derived from other monomers.

[0021] Examples of polyolefins include polyethylene and polypropylene. Among these, polyethylene is preferred. In the present disclosure, polyethylene refers to a polymer in which the content of ethylene-derived structural units in all repeating structural units is 50 mol% or more. In this polymer, the content of ethylene-derived structural units is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The content can be measured by NMR.

[0022] In the present disclosure, the polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of the ethylenically unsaturated monomer other than ethylene include α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene; vinyl monomers, such as vinyl acetate and vinyl propionate; (meth)acrylic acid; and (meth)acrylic acid esters, such as methyl (meth)acrylate and ethyl (meth)acrylate.

[0023] Examples of polyethylene include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and very low density polyethylene.

[0024] In the present disclosure, the density of the polyethylene is as follows: The density of the high density polyethylene is preferably 0.945 g / cm 3The upper limit of the density of high-density polyethylene is, for example, 0.965 g / cm 3 The density of the medium density polyethylene is preferably 0.928 g / cm 3 More than 0.945g / cm 3 The density of the low density polyethylene is preferably less than 0.900 g / cm 3 More than 0.928g / cm 3 The density of the linear low density polyethylene is preferably less than 0.900 g / cm 3 More than 0.928g / cm 3 The density of the very low density polyethylene is preferably less than 0.900 g / cm 3 The lower limit of the density of the ultra-low density polyethylene is, for example, 0.860 g / cm 3 The density of polyethylene is measured in accordance with JIS K7112, particularly method B or D (23°C).

[0025] Low-density polyethylene is typically obtained by polymerizing ethylene using a high-pressure polymerization process (high-pressure low-density polyethylene). Linear low-density polyethylene is typically obtained by polymerizing ethylene and a small amount of α-olefins using a low-pressure polymerization process (e.g., polymerization using a Ziegler-Natta catalyst or metallocene catalyst).

[0026] Polyethylenes with different densities or branches can be obtained by appropriately selecting the polymerization method. For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst, and carry out polymerization in one or more stages by any of gas phase polymerization, slurry polymerization, solution polymerization, and high-pressure ionic polymerization.

[0027] A single-site catalyst is a catalyst capable of forming a uniform active species and is typically prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activating cocatalyst. Single-site catalysts are preferred because, compared to multi-site catalysts, the structure of the active site is uniform, allowing the production of polymers with high molecular weights and highly uniform structures. Metallocene catalysts are preferred as single-site catalysts. Metallocene catalysts are catalysts containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a cocatalyst, an optional organometallic compound, and an optional support. Examples of transition metals in the transition metal compound include zirconium, titanium, and hafnium, with zirconium and hafnium being preferred.

[0028] In the present disclosure, polyethylene may be derived from biomass (hereinafter also referred to as "biomass polyethylene"). That is, biomass-derived ethylene may be used as a raw material for obtaining polyethylene instead of ethylene obtained from fossil fuels. Biomass polyethylene is a carbon-neutral material, and therefore the environmental impact of the laminated film can be reduced. Biomass polyethylene can be produced, for example, by the method described in JP 2013-177531 A. Commercially available biomass polyethylene may also be used. Polyethylene recycled by mechanical recycling or chemical recycling may also be used as the polyethylene. This reduces the environmental impact of the laminated film.

[0029] In one embodiment, the first surface layer is the layer that comes into contact with the contents of the paper container. When laminating a laminated film for paper containers onto a paper container by vacuum forming or pressure forming, the film is heated and softened with a heating element such as a hot plate, then formed and adhered to the paper container. When heating the contents of a paper container, the paper container itself is typically heated in a microwave oven. Therefore, it is preferable that the first surface layer has high heat resistance.

[0030] From the viewpoint of a balance between heat resistance and moldability, the first surface layer preferably contains linear low-density polyethylene, and more preferably contains linear low-density polyethylene and low-density polyethylene. This, for example, improves the heat resistance of the laminated film, allowing for the production of a laminated paper container that can withstand heating in a microwave oven. Furthermore, for example, the first surface layer can be heat-sealed to a lid material described below.

[0031] The density of the linear low-density polyethylene contained in the first surface layer is preferably 0.900 g / cm 3 More than 0.928g / cm 3 less than 0.915 g / cm 3 More than 0.928g / cm 3 is less than.

[0032] From the viewpoint of film-forming and processability, the melt flow rate (MFR) of the polyethylene constituting the first surface layer is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.3 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. The MFR of polyethylene is measured by Method A in accordance with JIS K7210:1999 at a temperature of 190°C and a load of 2.16 kg.

[0033] For example, when producing a laminated film by an 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 viewpoints of film-forming and processability. For example, when producing a laminated film by a T-die method, the MFR of the polyethylene constituting the first surface layer is preferably 3.0 g / 10 min or more and 20 g / 10 min or less from the viewpoints of film-forming and processability.

[0034] From the viewpoint of heat resistance, the melting point (Tm) of the linear low-density polyethylene that may constitute the first surface layer is preferably 100° C. or higher and 140° C. or lower, more preferably 110° C. or higher and 140° C. or lower, and even more preferably 115° C. or higher and 140° C. or lower. The Tm of polyethylene is the melting peak temperature obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0035] The melting point (Tm) of the low-density polyethylene that can constitute the first surface layer is preferably 100°C or higher and 140°C or lower, more preferably 10°C or higher and 130°C or lower, and even more preferably 100°C or higher and 120°C or lower, from the viewpoint of a balance between heat resistance and moldability.

[0036] The first surface layer preferably contains a polyolefin such as polyethylene as a main component, i.e., more than 50% by mass of the polyolefin such as polyethylene. The content of the polyolefin such as polyethylene in the first surface layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total mass of the first surface layer. This can improve, for example, the heat resistance and moldability of the laminate film.

[0037] In one embodiment, the content of the linear low-density polyethylene in the first surface layer is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more or 90% by mass or more, relative to the total mass of the first surface layer, which can, for example, further improve the balance between heat resistance and moldability of the laminate film.

[0038] When the first surface layer further contains low-density polyethylene, the content of the linear low-density polyethylene in the first surface layer is preferably 40% by mass to 80% by mass, more preferably 45% by mass to 75% by mass, and even more preferably 50% by mass to 70% by mass, relative to the total mass of the first surface layer, which can further improve the balance between heat resistance and moldability of the laminate film, for example.

[0039] The content of low-density polyethylene in the first surface layer is preferably 20% by mass to 60% by mass, more preferably 25% by mass to 55% by mass, and even more preferably 30% by mass to 50% by mass, relative to the total mass of the first surface layer. This can, for example, further improve the balance between heat resistance and moldability of the laminate film. Increasing the content of low-density polyethylene in the first surface layer tends to increase the heat shrinkage rate of the laminate film.

[0040] The first surface layer may contain additives such as crosslinkers, antiblocking agents, lubricants, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

[0041] The thickness of the first surface layer is 13 μm or more, preferably 13 μm to 50 μm, more preferably 15 μm to 40 μm, and even more preferably 18 μm to 30 μm. This, for example, improves the balance between heat resistance and rigidity of the laminated film. When the thickness of the first surface layer is equal to or greater than the lower limit, for example, foaming due to heating in a microwave oven can be suppressed, and sufficient seal strength can be obtained when a lid material is heat-sealed to a laminated paper container.

[0042] The ratio of the thickness of the first surface layer to the total thickness of the laminated film is preferably 5% to 40%, more preferably 10% to 35%, and even more preferably 15% to 30%. When the thickness ratio is equal to or greater than the lower limit, for example, foaming due to heating in a microwave oven can be suppressed, and sufficient seal strength can be obtained when a lid is heat-sealed to a laminated paper container.

[0043] In one embodiment, the first surface layer constitutes one of the outermost layers of the laminate film of the present disclosure. In one embodiment, when the laminate film of the present disclosure is tightly attached to the surface of a paper container, the first surface layer is the layer that comes into contact with the contents contained in the paper container.

[0044] The first surface layer may be irradiated with electron beams. This can, for example, improve the crosslink density of the first surface layer, thereby improving the heat resistance of the laminated film and enabling thermal lamination at higher temperatures in a shorter time. The absorbed dose of electron beam irradiation is, for example, 20 kGy or more and 130 kGy or less.

[0045] <Middle class> In one embodiment, the laminate film of the present disclosure includes an intermediate layer. In one embodiment, the intermediate layer is a layer that imparts excellent moldability (e.g., ability to conform to the shape of a container) to the laminate film. Hereinafter, the intermediate layer will also be referred to as a "moldable layer."

[0046] The molding layer preferably contains a resin that can be molded at low temperatures (hereinafter also referred to as "low-temperature moldable resin"). This can improve the moldability of the laminated film, for example, at temperatures below 200°C, and can improve the ability of the laminated film to conform to the shape of a container (for example, deep-draw formability). Examples of low-temperature moldable resins include ionomer resins, ethylene-(meth)acrylic acid copolymers, and ethylene-vinyl acetate copolymers. Among these, ionomer resins are preferred.

[0047] An example of the ionomer resin is a resin in which the molecules of an ethylene-(meth)acrylic acid copolymer are ionically crosslinked by forming a salt between the acid moiety of the copolymer and a metal ion. Examples of metal cations that crosslink the molecular chains of the ionomer resin include Na + , Zn 2+ Examples include:

[0048] From the viewpoint of film-forming ability and processability, the MFR of the ionomer resin is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.3 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. The MFR of the ionomer resin is measured by Method A in accordance with JIS K7210:1999, at a temperature of 190°C and a load of 2.16 kg.

[0049] From the viewpoint of low-temperature moldability, 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, and even more preferably 80° C. or higher and 110° C. Tm is the melting peak temperature obtained by DSC in accordance with JIS K7121.

[0050] The content of the low-temperature formable resin in the moldable layer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, relative to the total mass of the moldable layer, which can improve, for example, the moldability of the laminated film.

[0051] The molding layer may contain the above-mentioned additives.

[0052] The molding layer may be one layer or two or more layers.

[0053] The thickness of the molded layer is preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 50 μm or less, and even more preferably 15 μm or more and 40 μm or less. This can improve, for example, the moldability of the laminated film. When the molded layer is made up of multiple layers, the total thickness of the multiple layers is defined as the thickness of the molded layer.

[0054] The ratio of the thickness of the molded 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 even more preferably 20% or more and 40% or less. <Interlayer adhesion layer> The laminate film of the present disclosure may further include an interlayer adhesion layer between any layers, for example, between the gas barrier layer and the molded layer, thereby improving the adhesion between any layers, for example, between the gas barrier layer and the molded layer.

[0055] The interlayer adhesive layer contains, for example, an adhesive resin. Examples of adhesive resins include modified polyolefins, vinyl resins, polyethers, polyesters, polyamides, polyurethanes, silicone resins, epoxy resins, and phenolic resins. Among these, from the viewpoints of adhesiveness 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.

[0056] The modified polyolefins include, for example, polyolefins modified with unsaturated carboxylic acids or their acid anhydrides, esters, or metal salts (specifically, graft-modified polyolefins).The unsaturated carboxylic acids include, for example, maleic acid and fumaric acid, and the anhydrides of unsaturated carboxylic acids include, for example, maleic anhydride.The modified polyoleins include, for example, maleic anhydride-modified polyethylenes, such as maleic anhydride-graft-modified polyethylenes.

[0057] Other examples of modified polyolefins include ethylene-(meth)acrylic acid ester copolymers such as ethylene-vinyl acetate copolymers, ethylene-methyl(meth)acrylate copolymers and ethylene-ethyl(meth)acrylate copolymers, and ethylene-(meth)acrylic acid copolymers.

[0058] From the viewpoint of film-forming ability and processability, the MFR of the modified polyolefin is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.3 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. In the case of modified polyethylene, for example, the MFR of the modified polyolefin 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, although the measurement temperature may be changed depending on the melting point of the modified polyolefin.

[0059] 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 even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more, based on the total mass of the interlayer adhesion layer, which can improve the adhesion between the layers, for example.

[0060] The interlayer adhesion layer may contain the above-mentioned additives.

[0061] The interlayer adhesion layer may be one layer or two or more layers.

[0062] 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, and even more preferably 15 μm or more and 30 μm or less. This can, for example, further improve the balance of adhesion between the layers, heat resistance, and rigidity. When the interlayer adhesion layer is made up of multiple layers, the total thickness of the multiple layers is defined as the thickness of the interlayer adhesion layer.

[0063] The ratio of the thickness of the interlayer adhesive layer to the thickness of the entire laminated film is preferably 5% or more and 40% or less, more preferably 10% or more and 35% or less, and even more preferably 15% or more and 30% or less.

[0064] <Gas barrier layer> In one embodiment, the laminate film of the present disclosure includes a gas barrier layer. This can improve the gas barrier properties, such as oxygen barrier properties, of the laminate film. The gas barrier layer contains a gas barrier resin. Hereinafter, the gas barrier layer may also be simply referred to as a "barrier layer."

[0065] Examples of gas barrier resins include ethylene-vinyl alcohol copolymers, polyamides, polyvinyl alcohols, polyacrylonitriles, polyesters, polyurethanes, and (meth)acrylic resins. Among these, ethylene-vinyl alcohol copolymers (hereinafter also referred to as "EVOH") are preferred from the viewpoint of oxygen barrier properties and / or water vapor barrier properties.

[0066] In gas barrier resins such as EVOH, the content of ethylene-derived structural units (ethylene copolymerization ratio) is, for example, 25 mol% or more, preferably 35 mol% or more, more preferably 35 mol% to 50 mol%, and even more preferably 37 mol% to 47 mol%. When the ethylene copolymerization ratio is equal to or greater than the lower limit, for example, the molding processability of the laminate film, specifically its conformability during low-temperature molding, can be improved, and the gas barrier properties can also be improved. When the ethylene copolymerization ratio is equal to or less than the upper limit, for example, the gas barrier properties of the laminate film can be improved, and the ethylene copolymerization ratio may be, for example, 42 mol% or less. The ethylene copolymerization ratio is measured by NMR.

[0067] The melting point (Tm) of the gas barrier resin such as EVOH is, for example, 190°C or lower, preferably 175°C or lower, more preferably 130°C to 173°C, even more preferably 140°C to 170°C, and particularly preferably 150°C to 168°C. When Tm is equal to or lower than the upper limit, for example, the molding processability of the laminate film, specifically, its conformability during low-temperature molding, can be improved, and the gas barrier properties can also be improved. Tm is the melting peak temperature obtained by DSC in accordance with JIS K7121.

[0068] The crystallization temperature (Tc) of gas barrier resins such as EVOH is, for example, 170°C or lower, preferably 152°C or lower, more preferably 110°C or higher and 148°C or lower, and even more preferably 115°C or higher and 140°C or lower. When Tc is equal to or lower than the upper limit, for example, the molding processability of the laminated film, specifically, its conformability during low-temperature molding, can be improved. Tc is the crystallization peak temperature obtained by DSC (cooling rate: 5°C / min) in accordance with JIS K7121.

[0069] By using a gas barrier resin (particularly EVOH) having an ethylene copolymerization ratio of 35 mol% or more and a Tm of 175°C or less, the gas barrier properties of the laminated film can be further improved, and the molding processability (e.g., ability to conform to the shape of a container) during molding at 200°C or less can be further improved.

[0070] From the viewpoint of film-forming and processability, the MFR of gas barrier resins such as EVOH is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.3 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. The MFR of gas barrier resins is measured by Method A in accordance with JIS K7210:1999, at a temperature of 190°C and a load of 2.16 kg.

[0071] 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 even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more, relative to the total mass of the gas barrier resin layer, which can improve the gas barrier properties of the laminate film, for example.

[0072] The barrier layer may contain the above-mentioned additives.

[0073] The barrier layer may be a single layer or a multi-layer structure of two or more layers.

[0074] 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 even more preferably 5 μm or more and 15 μm or less. When the thickness is equal to or greater than 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, a decrease in the followability when laminating the laminated film to an adherend can be suppressed. When the barrier layer is made up of multiple layers, the total thickness of the multiple layers is taken as the thickness of the barrier layer.

[0075] The ratio of the thickness of the barrier layer to the thickness of the entire laminate film is preferably 1% or more and 30% or less, more preferably 3% or more and 20% or less, and even more preferably 5% or more and 15% or less.

[0076] <Adhesive layer> The laminate film of the present disclosure includes an adhesive layer. The adhesive layer is a layer that comes into contact with an adherend when the laminate film is attached to the adherend, such as a paper container, and in one embodiment, has adhesive properties to paper, plastic, metal, ceramic, wood, or the like.

[0077] The adhesive layer contains, for example, an adhesive resin. Examples of adhesive resins include modified polyolefins, vinyl resins, polyethers, polyesters, polyamides, polyurethanes, silicone resins, epoxy resins, and phenolic resins. Among these, from the viewpoints of adhesiveness 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.

[0078] The modified polyolefins include, for example, polyolefins modified with unsaturated carboxylic acids or their acid anhydrides, esters, or metal salts (specifically, graft-modified polyolefins).The unsaturated carboxylic acids include, for example, maleic acid and fumaric acid, and the anhydrides of unsaturated carboxylic acids include, for example, maleic anhydride.The modified polyoleins include, for example, maleic anhydride-modified polyethylenes, such as maleic anhydride-graft-modified polyethylenes.

[0079] Other examples of modified polyolefins include ethylene-(meth)acrylic acid ester copolymers such as ethylene-vinyl acetate copolymers, ethylene-methyl(meth)acrylate copolymers and ethylene-ethyl(meth)acrylate copolymers, and ethylene-(meth)acrylic acid copolymers.

[0080] From the viewpoint of film-forming ability and processability, the MFR of the modified polyolefin is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.3 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. In the case of modified polyethylene, for example, the MFR of the modified polyolefin 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, although the measurement temperature may be changed depending on the melting point of the modified polyolefin.

[0081] The adhesive resin content in the adhesive layer is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more, based on the total mass of the adhesive layer, which can improve the adhesion between the laminated film and the adherend, for example.

[0082] The adhesive layer may further contain an anti-blocking agent. This, for example, can adjust the adhesive strength between the laminate film and the adherend, improve the peelability of the laminate film from the adherend (specifically, the peelability when the laminate film is molded at high temperature and adhered to the adherend), and therefore improve the recyclability of the laminated paper container. It can also suppress blocking between laminate films.

[0083] Examples of antiblocking agents include inorganic compound-based antiblocking agents and resin particle-based antiblocking agents. Specific examples of inorganic compound-based antiblocking agents include oxides such as silica, aluminum oxide, magnesium oxide, calcium oxide, titanium oxide, and zinc oxide; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; 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 resin particles composed of resin components such as (meth)acrylic resins such as polymethyl methacrylate (PMMA), polystyrene, methyl methacrylate-styrene copolymers, polyesters, polyamides, polytetrafluoroethylene, silicone resins, epoxy resins, urea resins, and phenolic resins. The resin particles may be crosslinked or non-crosslinked.

[0084] 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 even more preferably 3.0 μm or more and 10.0 μm or less. When the average particle size is equal to or greater than the lower limit, for example, peelability of the laminated film from the adherend can be improved. When the average particle size is equal to or less than the upper limit, for example, detachment of the antiblocking agent from the adhesive layer can be suppressed.

[0085] In the present disclosure, the average particle size refers to the average particle size (arithmetic mean diameter) measured for 100 randomly selected non-aggregated particles when a cross section of each layer in the thickness direction is observed with a scanning electron microscope (SEM).

[0086] The content of the antiblocking agent in the adhesive layer is preferably 0.1% by mass to 30.0% by mass, more preferably 0.15% by mass to 20.0% by mass, even more preferably 0.2% by mass to 10.0% by mass, and particularly preferably 0.2% by mass to 2.5% by mass, based on the total mass of the adhesive layer. When the content is equal to or greater than 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, separation of the antiblocking agent from the adhesive layer can be suppressed.

[0087] To improve 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. Examples of the thermoplastic resin include 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 even more preferably 3% by mass or more and 60% by mass or less.

[0088] The adhesive layer may further contain at least one selected from linear low-density polyethylene and low-density polyethylene, which, for example, can adjust the adhesive strength between the laminate film and the adherend, improve the peelability of the laminate film from the adherend (specifically, the peelability when the laminate film is molded at high temperature and adhered to the adherend), and therefore improve the recyclability of the laminated paper container.

[0089] The MFR of the linear low-density polyethylene and the low-density polyethylene can be within the range described for the MFR of the polyethylene constituting the first surface layer. The melting point (Tm) of the linear low-density polyethylene and the 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, and even more preferably 100°C or higher and 120°C or lower.

[0090] In the above embodiment, the total content of the linear low-density polyethylene and the low-density polyethylene in the adhesive layer is preferably 1% by mass to 40% by mass, more preferably 5% by mass to 35% by mass, and even more preferably 10% by mass to 30% by mass, relative to the total mass of the adhesive layer. When the content is equal to or greater than 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.

[0091] The adhesive layer may further contain an ethylene-(meth)acrylic acid ester copolymer such as an ethylene-methyl(meth)acrylate copolymer. Such copolymers have a low melting point. This can improve, for example, the adhesion between the adherend and the laminated film (specifically, the adhesion when the laminated film is molded at a low temperature and adhered to the adherend). Ethylene-methyl acrylate copolymer is particularly preferred.

[0092] From the viewpoint of film-forming ability and processability, the MFR of the ethylene-(meth)acrylic acid ester copolymer is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.3 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. The MFR of the ethylene-(meth)acrylic acid ester copolymer is measured by Method A in accordance with JIS K7210:1999, at a temperature of 190°C and a load of 2.16 kg.

[0093] From the viewpoints of moldability and adhesiveness, the melting point (Tm) of the ethylene-(meth)acrylic acid ester copolymer is preferably from 60° C. to 100° C., more preferably from 60° C. to 90° C., and even more preferably from 60° C. to 80° C. Tm is the melting peak temperature obtained by DSC in accordance with JIS K7121.

[0094] 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, and even more preferably 15% by mass or more and 30% by mass or less. The content is measured by NMR.

[0095] In the above embodiment, the content of the ethylene-(meth)acrylic acid ester copolymer in the adhesive layer is preferably 1% by mass to 40% by mass, more preferably 5% by mass to 35% by mass, and even more preferably 10% by mass to 30% by mass, relative to the total mass of the adhesive layer. When the content is equal to or greater than the lower limit, for example, the adhesion of the laminated film to the adherend (specifically, the adhesion when the laminated film is molded at low temperature and adhered to the adherend) can be improved.

[0096] The adhesive layer may contain the above-mentioned additives.

[0097] The adhesive layer may be subjected to a surface treatment. This can improve the adhesive strength between the adhesive layer and an adherend such as a paper container. 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, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. Among these, corona discharge treatment is preferred.

[0098] The wet tension of the adhesive layer surface of the laminate film of the present disclosure is preferably 40 mN / m or more, more preferably 43 mN / m to 65 mN / m, and even more preferably 45 mN / m to 60 mN / m. When the wet tension is equal to or greater than the lower limit, for example, the adhesion between the adherend and the laminate film (specifically, the adhesion when the laminate film is molded at low temperature and adhered to the adherend) can be improved. The wet tension can be adjusted, for example, by the above-mentioned surface treatment.

[0099] Wet tension is measured according to a method in accordance with JIS K6768:1999. Wet tension is measured in an environment with a temperature of 23°C and a relative humidity of 50%. Specifically, the measurement is performed using a tension checker (TC-B-48.0) manufactured by Pacific Chemical Co., Ltd. A reagent is applied to the adhesive layer surface in the width direction, and whether or not the liquid film breaks after 2 seconds is visually determined. The wet tension when no breakage occurs is regarded as the wet tension of the surface.

[0100] The adhesive layer may be, for example, an adhesive layer containing an acid-modified polyethylene and at least one selected from an antiblocking agent, a linear low-density polyethylene, and a low-density polyethylene, and having a wetting tension of 40 mN / m or more; an adhesive layer containing an acid-modified polyethylene, an antiblocking agent, at least one selected from linear low-density polyethylene and low-density polyethylene, and an ethylene-(meth)acrylic acid ester copolymer; an adhesive layer containing an acid-modified polyethylene, an antiblocking agent, at least one selected from linear low-density polyethylene and low-density polyethylene, and an ethylene-(meth)acrylic acid ester copolymer, and having a wetting tension of 40 mN / m or more; Examples include:

[0101] A laminated film having such an adhesive layer has excellent adhesion to an adherend, such as a paper container, even when formed at low temperatures, and has excellent releasability from the adherend even when formed at high temperatures.

[0102] The thickness of the adhesive layer is preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 30 μm, which can improve the balance between adhesion to the adherend, releasability, and rigidity, for example.

[0103] The ratio of the thickness of the adhesive layer to the thickness of the entire laminated film is preferably 5% or more and 40% or less, more preferably 10% or more and 35% or less, and even more preferably 15% or more and 30% or less.

[0104] [Layer structure of laminated film] In one embodiment, the laminated film of the present disclosure comprises, in this order, a first surface layer, a molding layer, an interlayer adhesion layer, a barrier layer, and an adhesive layer as a second surface layer. The adhesive layer is laminated to an adherend such as a paper container.

[0105] In one embodiment, the laminated film of the present disclosure comprises, in this order, a first surface layer, a first molding layer, a first interlayer adhesion layer, a barrier layer, a second interlayer adhesion layer, a second molding layer, and an adhesive layer as the second surface layer.

[0106] The total thickness of the laminate 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 total thickness of the laminate film is the lower limit or more, the strength of the laminate film can be improved.

[0107] The laminate film of the present disclosure may be irradiated with electron beams. This can, for example, improve the crosslink density of the laminate film, thereby improving the heat resistance of the laminate film and enabling thermal lamination at higher temperatures in a shorter time. The absorbed dose of electron beam irradiation is, for example, 20 kGy or more and 130 kGy or less.

[0108] The oxygen permeability of the laminated film of the present disclosure under conditions of 23°C and 65% RH is preferably 20 cc / m 2 ·day·atm or less, preferably 15cc / m 2 ·day·atm or less, more preferably 10cc / m 2 The oxygen permeability can be measured in accordance with JIS K7126-2 using an oxygen permeability measuring device, with the adhesive layer of the laminated film set to be the oxygen supply side.

[0109] The laminated film of the present disclosure can be applied not only to paper containers but also to various adherends. Examples of the adherends include paper containers, plastic containers, and various components (e.g., containers) made of metal, ceramic, wood, etc. Examples of the adherends include electronic components such as capacitors, semiconductor integrated circuits, wafers, and light-emitting elements.

[0110] [Laminated film manufacturing method] In one embodiment, the laminate film of the present disclosure is a coextruded resin film, and each layer constituting the film is a coextruded resin layer. The coextruded resin film can be produced by, for example, forming the materials constituting the layers by an inflation method or a T-die method. The laminate film can be obtained, for example, by coextrusion forming the material constituting the first surface layer, the material constituting the molding layer, the material constituting the interlayer adhesion layer, the material constituting the barrier layer, and the material constituting the adhesive layer by a conventionally known method such as an inflation method or a T-die method.

[0111] The laminate film of the present disclosure can also be produced by coating the forming material of one of the layers on the surface of another layer that will constitute the laminate film, and drying it as necessary to form a laminate structure in the laminate film, and then, as necessary, further laminating other layers so as to achieve the desired arrangement.

[0112] The laminated film of the present disclosure can also be produced by first separately preparing two or more films for constituting any two or more of the layers, and then laminating these films together using an adhesive by any of dry lamination, extrusion lamination, hot melt lamination, and wet lamination, or by thermal lamination without using an adhesive, and then laminating other layers as needed to form the desired arrangement. In this case, an adhesive resin capable of forming an interlayer adhesive layer may be used as the adhesive.

[0113] [Laminated paper container] The laminated paper container of the present disclosure comprises 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 for a wide range of purposes, including beverages such as milk drinks, fruit drinks, and alcohol, as well as foods such as rice, prepared foods, meat, and dairy products. The laminated paper container can also be used as a container for chilled or frozen foods, or as a takeout container. Laminated paper containers may also be referred to as "paper containers" hereinafter.

[0114] Laminated paper containers can be produced by heating and softening a laminated film and then adhering it to a paper container using a forming method such as vacuum forming or pressure forming. The heating temperature is, for example, 140°C or higher and 200°C or lower, or may be 140°C or higher and 190°C or lower, or 140°C or higher and 180°C or lower.

[0115] [Paper container with lid] Hereinafter, an embodiment in which the laminated film of the present disclosure is applied to the production of a paper container will be described. As shown in Figure 4, the paper container with lid 1 according to this embodiment comprises a paper container 10 and a lid 50 that seals the paper container 10. First, the paper container 10 will be described.

[0116] <Paper containers> As shown in Figures 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. 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 blanks 30, which will be described later.

[0117] (Paper container) The paper container 20 has, for example, a bottom 21, a plurality of side portions 23 connected to the bottom 21 via fold lines (first fold lines) 22, and a plurality of flange pieces 25 connected to each of the side portions 23 via fold lines (second fold lines) 24.

[0118] 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.

[0119] The bottom 21 has, for example, a generally rectangular shape in plan view. The bottom 21 may have a polygonal shape such as an octagonal shape in plan view.

[0120] The fold line (first fold line) 22 connecting the bottom portion 21 and the side portion 23 may be formed in a perforated shape or a half-cut line. This makes it easier to fold the side portion 23 relative to the bottom portion 21. When the fold line 22 is formed in a perforated shape, the formed film 40 is pressed against the paper container 20 in the vicinity of the fold line 22 by sucking air through suction holes 61 of the cavity-side mold 60, which will be described later. This improves the adhesion between the formed film 40 and the paper container 20.

[0121] Each side portion 23 extends upward from the bottom portion 21. In the illustrated example, the paper container 20 has four side portions 23, and the side portions 23 are formed as a whole in the shape of an inverted quadrangular pyramid. However, this is not limited thereto, and the side portions 23 may be formed as a whole in the shape of a polygonal pyramid, such as an inverted octagonal pyramid.

[0122] 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. This improves the adhesion between the side portions 23 and the formed film 40 around the entire circumference of the paper container 20. Furthermore, because the side portions 23 are adjacent to each other without overlapping, it is possible to prevent pinholes and the like from occurring in the formed film 40 when the formed film 40 is bonded to the paper container 20. Note that small gaps are formed between the side portions 23 to allow air to pass through, and the formed film 40 is configured to be pressed against the paper container 20 by sucking air through suction holes 61 of the cavity-side mold 60, which will be described later.

[0123] The fold line (second fold line) 24 connecting the side portion 23 and the flange piece 25 may be formed in a perforated shape, similar to the fold line 22, or may be a half-cut line. This makes it easier to fold the flange piece 25 relative to the side portion 23. When the fold line 24 is formed in a perforated shape, the formed film 40 is pressed against the paper container 20 in the vicinity of the fold line 24 by sucking air through suction holes 61 of the cavity-side mold 60, which will be described later. This improves the adhesion between the formed film 40 and the paper container 20.

[0124] Each flange piece 25, for example, protrudes horizontally laterally from the upper end of each side portion 23. 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.

[0125] The flange pieces 25 are adjacent to each other without being contiguous. That is, the flange pieces 25 are adjacent to each other without overlapping. This improves the adhesion between the flange pieces 25 and the molded film 40 around the entire circumference of the paper container 20. Furthermore, since the flange pieces 25 are adjacent to each other without overlapping, it is possible to prevent pinholes and the like from occurring in the molded film 40 when adhering the molded film 40 to the paper container 20. Furthermore, since the flange pieces 25 are adjacent to each other without overlapping, it is possible to improve the adhesion between the molded film 40 and the lid material 50 when sealing the lid material 50 in the area of ​​the molded film 40 of the paper container 10 corresponding to the flange pieces 25. This prevents poor sealing of the lid material 50. In this specification, "adjacent" refers not only to the case where adjacent members (e.g., flange pieces 25) are in contact with each other without any gaps throughout, but also to the case where either (1) or (2) below applies. (1) A member and another member are adjacent to each other with only a portion of the member in contact with the other member. (2) When one component and another component are adjacent to each other without being in contact with each other, at least a portion of the gap between the one component and the other component is large enough that the molded film 40 (laminated film 40a described later) cannot penetrate when the molded film 40 is adhered to the one component and the other component.

[0126] Next, an example of the adhesive strength between the paper container 20 and the formed film 40 will be described.

[0127] The adhesive strength between the bottom 21 and the formed film 40 and the adhesive strength between the side portions 23 and the formed film 40 may be, for example, 0.05 N / 15 mm or more and 0.4 N / 15 mm or less, respectively. Having these adhesive strengths of 0.05 N / 15 mm or more can prevent the formed film 40 from unintentionally peeling off from the paper container 20. In particular, when removing the lid material 50 from the paper container 10 of the lid-equipped paper container 1, it can prevent the formed film 40 from unintentionally peeling off from the bottom 21 or side portions 23 of the paper container 20. Furthermore, having these adhesive strengths of 0.4 N / 15 mm or less can easily separate the paper container 20 and the formed film 40 when recycling the paper container 20. The adhesive strength between the bottom 21 and the formed film 40 and the adhesive strength between the side portions 23 and the formed film 40 may be different from each other. For example, the adhesive strength between the side portion 23 and the molded film 40 may be greater than the adhesive strength between the bottom portion 21 and the molded film 40. The adhesive strength can be measured in accordance with JIS Z 0238:1998 by performing a 90° peel test on a sample cut into a 15 mm wide strip using a tensile tester (for example, Tensilon universal testing machine: RTC1310A, manufactured by Orientec Co., Ltd.) at a peel rate of 50 mm / min.

[0128] The adhesive strength between the flange piece 25 and the molded film 40 may be, for example, 1.0 N / 15 mm or more. This prevents the molded film 40 from peeling off from the flange piece 25 when the lid material 50 is removed from the paper container 10. This prevents the ease of opening the lid material 50 from decreasing.

[0129] Furthermore, the adhesive strength between the flange piece 25 and the molded film 40 may be, for example, 5.0 N / 15 mm or less. This prevents the molded film 40 from becoming difficult to peel from the paper container 20 when recycling the paper container 20. In this case, peeling (part of the paper container being peeled off) may occur on the paper container 20 from which the molded film 40 has been peeled.

[0130] Here, a heat-sealing agent may be applied to at least a portion of the surface of the paper container 20 (the surface of the blank 30, described later). This allows for easy adjustment of the adhesive strength between the paper container 20 and the formed film 40. Therefore, the desired adhesive strength can be easily obtained. In this embodiment, a heat-sealing layer H is provided on the flange piece 25 (the flange piece panel 35, described later). This heat-sealing layer H is formed by applying a heat-sealing agent to the flange piece 25 (the flange piece panel 35, described later). The heat-sealing agent may be ink. Heat-sealing agents that contain ethylene-vinyl acetate copolymer (EVA), ionomer, polyethylene (PE), or polypropylene (PP) can be used. Furthermore, the heat-sealing agent may contain vinyl-based, acrylic-based, polyamide-based, polyester-based, polyether-based, polyurethane-based, epoxy-based, chlorinated EVA-based, chlorinated PP-based, vinyl chloride-vinyl acetate-based, polyol-based, polyethyleneimine-based, starch-based, soluble nitrocellulose-based, rubber-based resin, etc. Furthermore, the heat-sealing agent may be applied onto the flange piece 25 (the flange piece panel 35 described later) by gravure printing, flexographic printing, offset printing, etc. In Figure 5 and other figures, the area where the heat-sealing layer H is provided is shown shaded.

[0131] The weight per unit area of ​​the heat seal layer H (i.e., the amount of heat sealant applied to the flange piece 25 (the flange piece panel 35 described later)) is 0.1 g / m 2 More than 10.0g / m 2 The amount of heat sealing agent applied to the flange piece 25 (the flange piece panel 35 described later) may be 0.1 g / m or less. 2 As a result, the adhesive strength between the flange piece 25 and the molded film 40 can be easily increased to a desired strength. Therefore, when removing the lid material 50 from the paper container 10, the molded film 40 can be prevented from peeling off from the flange piece 25, and the ease of opening the lid material 50 can be prevented from decreasing. In addition, the amount of heat sealing agent applied to the flange piece 25 (the flange piece panel 35 described later) is 10.0 g / m2 By satisfying the condition below, it is possible to prevent the adhesive strength between the flange piece 25 and the molded film 40 from becoming too large. This prevents the molded film 40 from becoming difficult to peel from the paper container 20 when recycling the paper container 20.

[0132] (Blank material) Next, an example of a blank 30 for producing a 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 a plurality of flange piece panels 35 connected to each of the side panels 33 via second fold lines 34. In the illustrated example, the blank 30 includes four side panels 33 and four flange piece panels 35. The bottom panels 31, first fold lines 32, side panels 33, second fold lines 34, and flange piece panels 35 of the blank 30 correspond to the bottom 21, fold line (first fold line) 22, side portions 23, fold line (second fold line) 24, and flange pieces 25 of the paper container 20, respectively.

[0133] The bottom panel 31, the side panels 33, and the flange piece panel 35 of the blank 30 are integrally formed. Such a blank 30 can be produced by subjecting the paper material that constitutes the blank 30 to a punching process or the like.

[0134] 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 has a pair of side edges 33a extending from the bottom panel 31. A gap 36 is formed between the side edges 33a of the side panels 33. As a result, in the paper container 10 described above, the side portions 23 do not overlap each other but are adjacent to each other (see FIGS. 5 and 6). In the illustrated example, in each side panel 33, the pair of side edges 33a extend in directions that move away from each other from the first fold line 32 side toward the second fold line 34 side.

[0135] The paper material constituting such a blank 30 may be, for example, various types of paperboard, coated paper, card paper, ivory paper, milk carton base paper, cup base paper, coated cardboard, or other processed paper. The basis weight of the paper material may be, for example, 150 g / m 2 More than 600g / m 2 The following is the result.

[0136] (molded film) Next, the formed film 40 will be described with reference to Figures 4 to 6. This formed film 40 serves to protect the paper container 20. In addition, the formed film 40 has a container shape and covers the entire surface of the paper container 20. This prevents the contents filled in the paper container 10 from leaking out of the paper container 10. The formed 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.

[0137] (lid material) Next, a description will be given of the lid member 50. The lid member 50 is sealed over the entire periphery of the formed film 40 of the paper container 10 in an area corresponding to the flange piece 25, for example.

[0138] The lid material 50 can be, for example, a laminate having a layer structure such as PET / sealant, oriented nylon (ONY) / sealant, PET / oriented nylon (ONY) / sealant, PET / PE / sealant, or K-coated oriented nylon (KONY) / PE / sealant. The laminate constituting the lid material 50 may also be, for example, a laminate in which a gas barrier material such as ethylene-vinyl alcohol copolymer (EVOH) is laminated on a molding layer. The lid material 50 can be, for example, a laminate having a layer structure such as PET / PE / ethylene-vinyl alcohol copolymer (EVOH) / PE / sealant.

[0139] The lid member 50 may be made from a laminate having the following layer configuration, for example. (Outside) Polyethylene terephthalate film with transparent vapor deposition layer (12 μm) / Nylon film (15 μm) / Polyethylene film (40 μm) (Inside)

[0140] It is preferable to use a resin material that can exhibit so-called easy peel properties for the laminate that constitutes the lid member 50. Furthermore, each of the above layers is formed according to a conventional method, such as dry lamination, extrusion lamination, extrusion coating, or other coating method.

[0141] In the paper container with lid 1 configured as described above, first, the contents are filled into the paper container 10. Next, the lid 50 is sealed to the area of ​​the forming film 40 of the paper container 10 that corresponds to the flange piece 25. This results in a paper container with lid 1 filled with the contents. The paper container with lid 1 may be a container for chilled foods or frozen foods, or may be used as a take-out container. The contents may also be food such as prepared dishes, meat, or dairy products.

[0142] Next, the operation of this embodiment configured as described above will be explained. Here, a method for manufacturing the paper container 10 and a method for manufacturing the paper container with lid 1 will be explained with reference to Figs.

[0143] (Paper container manufacturing method) First, the blank material 30 is prepared. In this process, a paper material is first prepared, and a heat-sealing agent is applied to a predetermined position on the paper material. The heat-sealing agent may be applied by gravure printing, flexographic printing, offset printing, or the like. In this way, a heat-sealing layer H is provided in a predetermined position on the paper material. Next, the paper material is punched out using a laser or the like to obtain the blank material 30.

[0144] Next, as shown in Figure 8, the blank 30 is attached to the cavity-side mold 60. Suction holes 61 are formed in this cavity-side mold 60, and the blank 30 is attached to the cavity-side mold 60 by sucking air through the suction holes 61. At this time, the side panels 33 of the blank 30 are folded relative to the bottom panel 31 along the first fold line 32. Similarly, the flange piece panels 35 of the blank 30 are folded relative to the side panels 33 along the second fold line 34. This results in a paper container 20 attached to the cavity-side mold 60.

[0145] Next, the molded 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 that constitutes the molded film 40 is placed above the paper container 20. Next, the laminated film 40a is heated by the core side mold 62 (see FIG. 10). Then, after the laminated film 40a has been 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. At this time, the core side mold 62 also presses the laminated film 40a against the paper container 20. As a result, the laminated film 40a is in close contact with the paper container 20.

[0146] The laminated film 40a is then cut into a desired shape by a cutting mechanism 63 provided in the core-side mold 62. This results in a formed film 40 laminated on a paper container 20, as shown in Figure 10. In this way, a paper container 10 is obtained.

[0147] In addition, the lid material 50 is prepared in parallel with the production of the paper container 10. At this time, a predetermined laminate is produced by a dry lamination method or the like. Then, the laminate is punched into a predetermined shape with a blade or the like to produce the lid material 50.

[0148] Next, the paper container 10 is filled with the contents, and the paper container 10 is sealed with the lid member 50. At this time, first, the contents (not shown) are filled into the paper container 10. Next, the lid member 50 is placed on the forming film 40 at a position corresponding to the flange piece 25.

[0149] Next, the lid material 50 is sealed to the formed film 40 by a sealing hot plate (not shown) or the like. At this time, the air inside the paper container 10 may be replaced with nitrogen gas or the like.

[0150] In this way, a paper container with lid 1 is obtained, which comprises the paper container 10 and the lid 50 that seals the paper container 10.

[0151] As described above, according to this embodiment, the adhesive strength between the flange piece 25 and the formed film 40 may be, for example, 1.0 N / 15 mm or more. This prevents the formed film 40 from peeling off from the flange piece 25 when the lid material 50 is removed from the paper container 10 of the lid-equipped paper container 1. This prevents a decrease in the ease of opening the lid material 50. Furthermore, because a decrease in the ease of opening the lid material 50 can be prevented, deformation of the paper container 10 can be prevented when the lid material 50 is removed from the paper container 10. This improves the practicality of the lid-equipped paper container 1.

[0152] Furthermore, according to this embodiment, the adhesive strength between the bottom 21 and the formed film 40 and the adhesive strength between the side 23 and the formed film 40 may be, for example, 0.05 N / 15 mm or more and 0.4 N / 15 mm or less, respectively. This prevents the formed film 40 from unintentionally peeling off from the paper container 20. In particular, this prevents the formed film 40 from unintentionally peeling off from the bottom 21 or side 23 of the paper container 20 when removing the lid material 50 from the paper container 10. Furthermore, the paper container 20 and the formed film 40 can be easily separated when recycling the paper container 20.

[0153] Furthermore, the formed film 40 can be prevented from unintentionally peeling off from the paper container 20, thereby improving the airtightness of the paper container 1 with a lid member. That is, if the formed film 40 is unintentionally peeled off from the paper container 20, the paper container 20 may not be able to maintain its shape as a container, and the paper container 20 may buckle. In this case, unintentional force may be applied to the lid member 50 and the formed film 40, which may result in the lid member 50 being unintentionally removed from the paper container 10. In contrast, in this embodiment, the formed film 40 can be prevented from unintentionally peeling off from the paper container 20, thereby preventing the lid member 50 from being unintentionally removed from the paper container 10. This improves the airtightness of the paper container 1 with a lid member. As a result, the barrier properties of the paper container 1 with a lid member can be improved, and the life of the contents can be extended. This reduces food waste.

[0154] Furthermore, according to this embodiment, the adhesive strength between the flange piece 25 and the molded film 40 may be, for example, 5.0 N / 15 mm or less. This makes it possible to prevent the molded film 40 from becoming difficult to peel from the paper container 20 when recycling the paper container 20.

[0155] Furthermore, according to this embodiment, a heat seal layer H is provided on the flange piece 25. This makes it possible to easily adjust the adhesive strength between the flange piece 25 and the molded film 40. Therefore, a desired adhesive strength can be easily obtained.

[0156] <Modified paper container> Next, modified examples of the paper container 10 according to this embodiment will be described with reference to Figures 11 to 18. In Figures 11 to 18, the same parts as those in the embodiment shown in Figures 4 to 10 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0157] (First modified example of paper container) In the above-described embodiment, an example in which a heat seal layer H is provided on the flange piece 25 (flange piece panel 35) has been described, but this is not limiting. For example, as shown in FIG. 11 , the heat seal layer H may be provided along the periphery of the bottom portion 21 (i.e., fold line 22). That is, a heat seal agent may be applied to the bottom portion 21 along the periphery of the bottom portion 21 (i.e., fold line 22). In this case, as shown in FIG. 12 , in the blank piece 30, the heat seal layer H may be provided along the periphery of the bottom panel 31 (i.e., first fold line 32). That is, in the blank piece 30, a heat seal agent may be applied to the bottom panel 31 along the periphery of the bottom panel 31 (i.e., first fold line 32).

[0158] Here, a gap is likely to form between the paper container 20 and the forming film 40 near the peripheral edge of the bottom 21. For this reason, there is a possibility that the forming film 40 may unintentionally peel off from the paper container 20, starting from the vicinity of the peripheral edge of the bottom 21.

[0159] In contrast, by applying a heat sealing agent to the bottom 21 along the periphery of the bottom 21, it is possible to increase the adhesive strength between the paper container 20 and the forming film 40 near the periphery of the bottom 21. This makes it possible to prevent the forming film 40 from unintentionally peeling off from the paper container 20.

[0160] In this case, the amount of heat sealing agent applied to the bottom 21 (bottom panel 31) is 0.1 g / m 2 More than 10.0g / m 2 The amount of heat sealing agent applied to the bottom 21 (bottom panel 31) may be 0.1 g / m or less. 2 As a result, the adhesive strength between the bottom 21 and the molded film 40 can be easily increased to a desired strength. This makes it possible to prevent the molded film 40 from unintentionally peeling off from the paper container 20. In addition, the amount of heat sealing agent applied to the bottom 21 (bottom panel 31) is 10.0 g / m 2or less, it is possible to prevent the adhesive strength between the bottom 21 and the molded film 40 from becoming too large. This makes it possible to prevent the molded film 40 from becoming difficult to peel from the paper container 20 when recycling the paper container 20.

[0161] (Second modified example of paper container) 13, a heat seal layer H may be provided on the bottom 21 and the side 23 so as to straddle the fold line 22. That is, a heat seal agent may be applied to the bottom 21 and the side 23 so as to straddle the fold line 22. In this case, as shown in FIG. 14, in the blank 30, a heat seal layer H may be provided on the bottom panel 31 and the side panel 33 so as to straddle the first fold line 32. That is, in the blank 30, a heat seal agent may be applied to the bottom panel 31 and the side panel 33 so as to straddle the first fold line 32. In this case, too, the adhesive strength between the paper container 20 and the forming film 40 can be increased near the peripheral edge of the bottom 21 (i.e., the fold line 22). This prevents the forming film 40 from unintentionally peeling off from the paper container 20.

[0162] In this case, the amount of heat sealing agent applied to the bottom 21 (bottom panel 31) and / or the side 23 (side panel 33) is 0.1 g / m 2 More than 10.0g / m 2 The amount of heat sealing agent applied to the bottom 21 (bottom panel 31) and / or the side 23 (side panel 33) may be 0.1 g / m or less. 2 By satisfying the above, the adhesive strength between the bottom 21 and / or side 23 and the formed film 40 can be easily increased to a desired strength. This makes it possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20. In addition, the amount of heat sealing agent applied to the bottom 21 (bottom panel 31) and / or side 23 (side panel 33) is 10.0 g / m 2By satisfying the condition below, it is possible to prevent the adhesive strength between the bottom portion 21 and / or the side portion 23 and the formed film 40 from becoming too high. This prevents the formed film 40 from becoming difficult to separate from the paper container 20 when recycling the paper container 20.

[0163] (Third modified example of paper container) Furthermore, as shown in FIG. 15 , a heat seal layer H may be provided on the bottom 21, the side 23, and the flange piece 25. That is, a heat seal agent may be applied to the bottom 21, the side 23, and the flange piece 25. In the illustrated example, the heat seal agent is applied to the entire surface of the paper container 20. Furthermore, the weight per unit area of ​​the heat seal layer H provided on the flange piece 25 may be greater than the weight per unit area of ​​the heat seal layer H provided on the side 23. That is, the amount of heat seal agent applied to the flange piece 25 may be greater than the amount of heat seal agent applied to the side 23. Furthermore, the weight per unit area of ​​the heat seal layer H provided on the side 23 may be greater than the weight per unit area of ​​the heat seal layer H provided on the bottom 21. That is, the amount of heat seal agent applied to the side 23 may be greater than the amount of heat seal agent applied to the bottom 21.

[0164] In this case, as shown in FIG. 16 , in the blank 30, the heat-sealing agent may be applied to the bottom panel 31, the side panel 33, and the flange piece panel 35. In the illustrated example, the heat-sealing agent is applied to the entire surface of the blank 30. The weight per unit area of ​​the heat-sealing layer H provided on the flange piece panel 35 may be greater than the weight per unit area of ​​the heat-sealing layer H provided on the side panel 33. That is, the amount of heat-sealing agent applied to the flange piece panel 35 may be greater than the amount of heat-sealing agent applied to the side panel 33. The weight per unit area of ​​the heat-sealing layer H provided on the side panel 33 may be greater than the weight per unit area of ​​the heat-sealing layer H provided on the bottom panel 31. That is, the amount of heat-sealing agent applied to the side panel 33 may be greater than the amount of heat-sealing agent applied to the bottom panel 31.

[0165] According to this modification, the adhesive strength between the paper container 20 and the forming film 40 in the paper container 10 can be easily adjusted. Therefore, the desired adhesive strength can be easily obtained.

[0166] Here, in order to improve the ease of opening the lid material 50, it is preferable to increase the adhesive strength between the flange piece 25 and the formed film 40. On the other hand, in order to improve the recyclability of the paper container 20, it is preferable to decrease 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. However, if 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 decreased, there is a possibility that the formed film 40 will unintentionally peel off from the bottom portion 21 or the side portion 23 of the paper container 20 when removing the lid material 50 from the paper container 10. In particular, if the adhesive strength between the side portion 23 and the formed film 40 is decreased, the formed film 40 will be more likely to peel off from the paper container 20 at the portion of the formed film 40 that is adhered to the side portion 23 when removing the lid material 50 from the paper container 10. Therefore, in order to improve the recyclability of the paper container 20 while improving the openability of the lid material 50, it is preferable to make the adhesive strength between the flange piece 25 and the molded film 40 greater than the adhesive strength between the side portion 23 and the molded film 40, and to make the adhesive strength between the side portion 23 and the molded film 40 greater than the adhesive strength between the bottom 21 and the molded film 40 so that the adhesive strength between the side portion 23 and the molded film 40 has a predetermined adhesive strength.

[0167] In this modification, the amount of heat-sealing agent applied to the flange piece 25 is greater than the amount of heat-sealing agent applied to the side portion 23, and the amount of heat-sealing agent applied to the side portion 23 is greater than the amount of heat-sealing agent applied to the bottom portion 21. As a result, the adhesive strength between the flange piece 25 and the forming film 40 can be greater than the adhesive strength between the side portion 23 and the forming film 40, and the adhesive strength between the side portion 23 and the forming film 40 can be greater than the adhesive strength between the bottom portion 21 and the forming film 40. This prevents the forming film 40 from peeling off from the flange piece 25, side portion 23, and bottom portion 21 of the paper container 20 when removing the lid material 50 from the paper container 10. Furthermore, the paper container 20 and the forming film 40 can be easily separated when recycling the paper container 20. This prevents the ease of opening the lid material 50 from decreasing, and allows the paper container 20 and the forming film 40 to be easily separated when recycling the paper container 20.

[0168] As shown in FIGS. 17 and 18, the heat-sealing agent may be applied to the entire surface of the blank sheet 30 in a predetermined pattern. For example, as shown in FIG. 17, the heat-sealing agent may be applied to the surface of the blank sheet 30 so as to form a polka dot pattern. As shown in FIG. 18, the heat-sealing agent may be applied to the surface of the blank sheet 30 in a striped pattern. The pattern shape of the heat-sealing agent is not particularly limited. Although not shown, the heat-sealing agent may be applied to the surface of the blank sheet 30 so that the areas where the heat-sealing agent is not applied form a polka dot pattern. The heat-sealing agent may also be applied to the surface of the blank sheet 30 to form another pattern, such as a checkerboard pattern, or may be applied to the surface of the blank sheet 30 in a grid pattern. In this case, although not shown, the heat-sealing agent is also applied to the entire surface of the paper container 20 produced from the blank sheet 30 in a predetermined pattern. The heat-sealing agent may also be applied to only a portion of the surface of the blank sheet 30 in a predetermined pattern.

[0169] (Fourth modified example of paper container) Furthermore, in the above-described embodiment, an example has been described in which the adhesive strength between the paper container 20 and the forming film 40 is adjusted by providing a heat seal layer H (applying a heat seal agent) on the surface of the paper container 20, but this is not limiting. For example, the adhesive strength may be adjusted by changing the temperature at which the forming film 40 is heated. That is, if it is desired to increase the adhesive strength, the heating temperature of the forming film 40 may be increased. On the other hand, if it is desired to decrease the adhesive strength, the heating temperature of the forming film 40 may be decreased. Even in this case, the adhesive strength between the paper container 20 and the forming film 40 can be easily adjusted. Note that the adhesive strength between the paper container 20 and the forming film 40 may be adjusted by changing the pressure or time when the core-side die 62 presses the laminated film 40a against the paper container 20.

[0170] The present disclosure is not limited to the above-described embodiments and modifications, and the components can be modified and embodied in practice without departing from the spirit of the present disclosure. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments and modifications. Some components may be omitted from all the components shown in the embodiments and modifications.

[0171] The present disclosure relates to, for example, the following [1] to

[12] . [1] A laminated film having a first surface layer and an adhesive layer as a second surface layer in this order, wherein the first surface layer has a density of 0.940 g / cm 3 A laminated film containing the following polyolefin, having a thickness of 13 μm or more, and having a heat shrinkage rate of 0.1% or more and 8.5% or less in the machine direction when heated in an atmosphere of 150°C and 50% RH for 10 minutes. [2] The laminated film according to [1] above, wherein the polyolefin comprises linear low-density polyethylene. [3] The laminated film according to the above [2], wherein the content of the linear low-density polyethylene in the first surface layer is 60 mass % or more relative to the total mass of the first surface layer. [4] The laminated film according to [1] or [2] above, wherein the polyolefin comprises linear low-density polyethylene and high-pressure low-density polyethylene. [5] The laminated film according to [4] above, wherein the content of linear low-density polyethylene in the first surface layer is 40% by mass or more and 80% by mass or less, and the content of high-pressure low-density polyethylene is 20% by mass or more and 60% by mass or less. [6] The laminated film according to any one of the above [1] to [5], wherein the adhesive layer contains a modified polyolefin. [7] The laminated film according to any one of the above [1] to [6], further comprising a gas barrier layer. [8] The laminated film according to [7] above, further comprising an intermediate layer between the first surface layer and the gas barrier layer, the intermediate layer containing at least one resin selected from an ionomer resin, an ethylene-(meth)acrylic acid copolymer, and an ethylene-vinyl acetate copolymer. [9] The laminated film according to the above [8], further comprising an interlayer adhesion layer containing a modified polyolefin between the intermediate layer and the gas barrier layer.

[10] The laminated film according to any one of the above [1] to [9], which is to be tightly molded into a paper container.

[11] A laminated paper container comprising a paper container and a formed film laminated on the surface of the paper container, the formed film being formed from the laminated film described in any one of [1] to

[10] above, and the adhesive layer of the laminated film being in contact with the surface of the paper container.

[12] A container with a lid, comprising the laminated paper container described in

[11] above and a lid that seals the laminated paper container. [Example]

[0172] Hereinafter, the laminate film of the present disclosure will be specifically described based on examples, but the laminate film of the present disclosure is not limited to the examples in any way.

[0173] [Making laminated film] The materials used to prepare the laminated film are listed below.

[0174] Linear low-density polyethylene (LLDPE) Density: 0.916g / cm 3 MFR: 2.3 g / 10 min, melting point: 116°C, manufactured by Prime Polymer Co., Ltd., product name: Evolue SP2020 Linear low-density polyethylene (LLDPE) Density: 0.926g / cm 3 , MFR: 1.7 g / 10 min, melting point: 127°C, manufactured by Japan Polyethylene Co., Ltd., trade name: Harmolex NF384A Linear polyethylene Density: 0.944g / cm 3 , MFR: 4.0 g / 10 min, melting point: 128°C, manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name: Yumerit 4540F High-pressure low-density polyethylene (LDPE) Density: 0.919g / cm 3 , MFR: 2.0 g / 10 min, Melting point: 108°C, Manufactured by Japan Polyethylene Co., Ltd., Trade name: Novatec LD LF405

[0175] Ionomer Ion type: Na + , Density: 0.940g / cm 3 MFR: 1.3 g / 10 min, melting point: 97°C, manufactured by Mitsui Dow Polychemicals Co., Ltd., trade name: Himilan 1601

[0176] adhesive resin Acid-modified polyethylene (acid-modified PE), density: 0.903 g / cm 3 , MFR: 1.7g / 10min, Mitsui Chemicals, Inc., Trade name: Admer NF557

[0177] 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%, manufactured by Kuraray Co., Ltd., trade name: EVAL XEP-1393B

[0178] Masterbatch containing anti-blocking agent (AB agent) Silica content: 4% by mass, density: 0.949 g / cm 3 , MFR: 1.6 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumikasen A-20

[0179] [Preparation of laminated film (A)] The first surface layer is LLDPE (Evolue SP2020), Ionomer (Himilan 1601) as the molding layer, Adhesive resin (Admer NF557) as an interlayer adhesive layer, Gas barrier resin (Eval XEP-1393B) as the barrier layer, and The adhesive layer (second surface layer) is a mixture of 95% by mass of adhesive resin (Admer NF557) and 5% by mass of antiblocking agent-containing masterbatch (Sumikasen A-20), Co-extrusion film formation was performed using inflation molding to obtain a 100 μm thick laminate film comprising a first surface layer, a molded layer, an interlayer adhesive layer, a barrier layer, and an adhesive layer in that order. The thickness of the first surface layer was 20 μm, the molded layer was 30 μm, the interlayer adhesive layer was 20 μm, the barrier layer was 10 μm, and the adhesive layer was 20 μm. The adhesive layer surface of the laminate film was subjected to corona treatment to adjust the wetting tension to 48 mN / m. In this way, laminate film (A) was obtained.

[0180] [Preparation of laminated films (B) to (F)] Laminated films (B) to (F) were prepared in the same manner as in [Preparation of laminated film (A)], except that the composition of the first surface layer and / or the thickness of each layer were changed as shown in Table 1.

[0181] [Laminated film (G)] Commercially available laminated film (Sumitomo Bakelite Co., Ltd., product name: CEL-9830C)

[0182] [Table 1]

[0183] [evaluation] The laminated film obtained in the examples or comparative examples and a paper container (120 mm × 160 mm × 30 mm (height)) were prepared. The paper container had a basis weight of 260 g / m 2 The laminated paper container was made using base paper (N Pearl Card, manufactured by Mitsubishi Paper Mills). Using a vacuum forming machine, the laminated film was placed 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 forming conditions were a heating temperature of 140°C, 150°C, 160°C, or 170°C, and a heating time of 3 seconds. In this way, a laminated paper container was produced, as shown in Figure 19, which included a paper container and a formed film formed into the shape of the paper container.

[0184] <Molding suitability> To evaluate the formability of the laminate film, the formed state of the laminate film at each heating temperature was observed. "Good" means that no wrinkles or uneven heating were observed in the formed film formed into a container shape from the laminate film, and the formability of the laminate film was high. "Good" means that small wrinkles or small uneven heating were observed in the formed film, and the formability of the laminate film was moderate. "Poor" means that large wrinkles or large uneven heating were observed in the formed film, and the formability of the laminate film was low.

[0185] <Microwave compatibility> To evaluate the suitability for microwave ovens, the heat shrinkability, the surface condition when heated in a microwave oven, and the adhesion state of the formed film to the paper container were observed.

[0186] Heat shrinkage was measured in both the machine direction (MD) and the transverse direction (TD) of the sample. Dimensional change rate (%) = 100 × (L o -L) / L o L o is the sample length before the test, and L is the sample length after the test.

[0187] The laminated paper container containing the hamburger steak as the content was heated in a microwave oven at 600 W for 1 minute and 30 seconds. The surface condition of the formed film after heating the laminated paper container in a microwave oven was observed. "Good" means that no significant foaming was observed on the surface of the formed film. "Poor" means that significant foaming was observed on the surface of the formed film. After heating the laminated paper container in a microwave oven, the adhesion state of the formed film to the paper container was observed. "Good" means that no significant peeling of the formed film from the paper container was observed. "Poor" means that significant peeling of the formed film from the paper container was observed.

[0188] [Table 2]

[0189] The first surface layer has a density of 0.940 g / cm 3 A laminated film containing the following polyolefin, having a first surface layer thickness of 15 μm or 20 μm and a thermal shrinkage rate in the MD direction of 0.1% to 8.5% has excellent formability and microwave oven suitability (Example). 3 A laminated film made of linear polyethylene of this type has insufficient formability (Comparative Example 1). A laminated film with a first surface layer having a thickness of 10 μm foams when heated in a microwave oven, causing leakage of the contents, and therefore has insufficient microwave suitability (Comparative Example 2). A laminated film with a MD heat shrinkage rate of 10% peels off when heated in a microwave oven, and therefore has insufficient microwave suitability (Comparative Example 3). [Explanation of symbols]

[0190] 10 Paper containers 20 Paper containers 21 Bottom 22 Line 23 Side 24 Line 25 flange piece 40 Forming Film H Heat seal layer 100 Laminated Film 110 First Surface 112, 112a, 112b Intermediate layer (molding layer) 114, 114a, 114b Interlayer adhesion layer 116 Gas barrier layer 118 Adhesive layer (second surface layer)

Claims

1. A laminated film having a first surface layer and an adhesive layer as a second surface layer in this order, The first surface layer has a density of 0.940 g / cm ３ It contains the following polyethylene and has a thickness of 13 μm or more: The laminated film has a heat shrinkage rate in the machine direction of 0.1% or more and 8.5% or less when heated in an atmosphere of 150°C and 50% RH for 10 minutes. Laminated film.

2. 2. The laminate film of claim 1, wherein the polyethylene comprises linear low density polyethylene.

3. The laminate film according to claim 2 , wherein the content of the linear low-density polyethylene in the first surface layer is 60% by mass or more relative to the total mass of the first surface layer.

4. 3. The laminated film according to claim 1, wherein the polyethylene comprises linear low-density polyethylene and high-pressure low-density polyethylene.

5. 5. The laminate film according to claim 4, wherein the content of the linear low-density polyethylene in the first surface layer is 40% by mass or more and 80% by mass or less, and the content of the high-pressure low-density polyethylene in the first surface layer is 20% by mass or more and 60% by mass or less.

6. The laminated film according to any one of claims 1 to 5, wherein the adhesive layer contains a modified polyolefin.

7. The laminate film according to any one of claims 1 to 6, further comprising a gas barrier layer.

8. between the first surface layer and the gas barrier layer, An intermediate layer containing at least one resin selected from an ionomer resin, an ethylene-(meth)acrylic acid copolymer, and an ethylene-vinyl acetate copolymer. The laminate film according to claim 7, further comprising at least

9. The laminated film according to claim 8 , further comprising at least an interlayer adhesion layer containing a modified polyolefin between the intermediate layer and the gas barrier layer.

10. The laminated film according to any one of claims 1 to 9, which is to be tightly formed into a paper container.

11. Paper containers and a formed film laminated on the surface of the paper container; Equipped with The formed film is formed from the laminated film according to any one of claims 1 to 10, and the adhesive layer of the laminated film is in contact with the surface of the paper container. Laminated paper container.

12. The laminated paper container according to claim 11; a lid material for sealing the laminated paper container; A container with a lid.

Images