Laminate and packaging bag

Abstract

To provide a laminate that can suppress a decrease in gas barrier property after retort processing when used in a packaging bag for a retort pouch or the like.SOLUTION: Provided is a laminate comprising at least: a barrier film in which a substrate, an inorganic oxide layer, and a coating layer with a barrier property are layered in this order; an adhesive agent layer; and a sealant layer, wherein the substrate comprises a stretched substrate that includes polypropylene as the primary component thereof, the sealant layer includes polypropylene as the primary component thereof, the barrier film is positioned such that the coating layer faces the adhesive agent layer side, the elastic modulus of a cross-section of the adhesive agent layer in the laminate is 100.0 MPa or less as measured using an atomic force microscope (AFM), and the indentation hardness from a cross-section of the coating layer in the laminate is 0.9 GPa to 1.7 GPa as measured using a nano-indentation method.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a laminate and a packaging bag. [Background technology]

[0002] Polyester films are excellent in mechanical properties, chemical stability, heat resistance, and transparency, and are inexpensive. Therefore, polyester films have been conventionally used as substrates constituting laminates used to produce packaging bags. Depending on the contents filled in the packaging bag, the packaging bag is required to have gas barrier properties such as oxygen barrier properties. To meet this requirement, an inorganic oxide layer containing alumina or silica is formed on the surface of the polyester film (see, for example, Patent Document 1). In recent years, substrates to replace polyester films have been sought. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-053223 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have considered using a stretched substrate containing polypropylene as a main component as a substrate constituting a laminate, instead of a conventional polyester film. Specifically, from the viewpoint of recyclability and gas barrier property, the present inventors have considered using a laminate comprising a barrier substrate comprising the stretched substrate and an inorganic oxide layer, and a sealant layer containing polypropylene as a main component. As a result of the consideration, the present inventors have found that a packaging bag produced using such a laminate may not have sufficient gas barrier property after retort treatment.

[0005] One of the problems to be solved by the present disclosure is to provide a laminate capable of suppressing deterioration of gas barrier properties after retort treatment when used in a packaging bag such as a retort pouch. [Means for solving the problem]

[0006] The laminate of the present disclosure is a laminate comprising at least a barrier film in which a substrate, an inorganic oxide layer, and a coating layer having barrier properties are laminated in this order, an adhesive layer, and a sealant layer, in which the substrate comprises an oriented substrate containing polypropylene as a main component, the sealant layer contains polypropylene as a main component, and the barrier film is disposed so that the coating layer faces the adhesive layer, the elastic modulus of the cross section of the adhesive layer in the laminate measured using an atomic force microscope (AFM) is 100.0 MPa or less, and the indentation hardness of the cross section of the coating layer in the laminate measured by nanoindentation method is 0.9 GPa or more and 1.7 GPa or less. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a laminate that, when used in a packaging bag such as a retort pouch, can suppress deterioration in gas barrier properties after retort treatment. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of a laminate. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing one embodiment of a laminate. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 4] FIG. 4 is a schematic cross-sectional view showing one embodiment of a laminate. [Diagram 5] FIG. 5 is a front view showing one embodiment of a packaging bag. [Figure 6] FIG. 6 is a perspective view showing an embodiment of a packaging bag. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In this specification, when multiple upper limit candidates and multiple lower limit candidates are given for a certain parameter, the numerical range of the parameter may be configured by combining any one of the upper limit candidates and any one of the lower limit candidates. As an example, the description "parameter B is preferably A1 or more, more preferably A2 or more, even more preferably A3 or more, and also preferably A4 or less, more preferably A5 or less, and even more preferably A6 or less." will be explained. In this example, the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[0010] Hereinafter, the embodiments of the present disclosure will be described in detail. The present disclosure can be implemented in many different forms, and is not to be interpreted as being limited to the description of the embodiments exemplified below. In the drawings, the width, thickness, shape, etc. of each layer may be shown diagrammatically in order to make the explanation clearer, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each figure, elements similar to those already explained with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0011] In this specification, the "main component" of a layer or substrate refers to a component whose content in the layer or substrate is more than 50% by mass, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0012] In the following description, each of the components (for example, polypropylene, α-olefin, resin material, additive, gas barrier resin, adhesive resin, inorganic oxide) may be used alone or in combination of two or more kinds.

[0013] [Laminate] The laminate of the present disclosure comprises, in a thickness direction, at least a barrier film, an adhesive layer, and a sealant layer. The barrier film is formed by laminating a substrate, an inorganic oxide layer, and a coating layer having barrier properties in this order. The substrate comprises an oriented substrate containing polypropylene as a major component. The sealant layer contains polypropylene as a main component.

[0014] The laminate of the present disclosure may include two or more substrates. The laminate of the present disclosure may include two or more adhesive layers.

[0015] The first substrate comprises an oriented substrate containing polypropylene as a major component. The second substrate comprises an oriented substrate containing polypropylene as a major component. The stretched substrate of the first substrate and the stretched substrate of the second substrate may be the same or different. At least one selected from the first substrate and the second substrate functions as a substrate constituting the barrier film (barrier substrate). In the following description, the stretched substrate containing polypropylene as a main component is also referred to as "stretched polypropylene substrate."

[0016] In one embodiment, the laminate of the present disclosure has a two-layer structure and includes a barrier film, an adhesive layer, and a sealant layer in this order in the thickness direction (hereinafter, simply referred to as "in this order"). In this embodiment, the barrier film is preferably arranged so that the coating layer faces the adhesive layer. With such an arrangement (i.e., the coating layer and the inorganic oxide layer are located between the substrate and the sealant layer, and the coating layer and the adhesive layer are adjacent to each other), for example, deterioration of the coating layer and the inorganic oxide layer can be further suppressed.

[0017] In one embodiment, the laminate of the present disclosure has a three-layer structure and includes a first substrate, a second substrate, an adhesive layer, and a sealant layer in this order. In this embodiment, the second substrate is a barrier substrate constituting a barrier film, and the barrier film is preferably arranged so that the coating layer faces the adhesive layer. This arrangement (i.e., the coating layer and the inorganic oxide layer are located between the second substrate and the sealant layer, and the coating layer and the adhesive layer are adjacent to each other) can, for example, further suppress deterioration of the coating layer and the inorganic oxide layer.

[0018] In one embodiment, the laminate of the present disclosure has a three-layer structure and includes, in this order, a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer. In this embodiment, it is preferable that the second substrate is a barrier substrate constituting a barrier film, and the barrier film is arranged so that the coating layer faces the first adhesive layer. With such an arrangement (i.e., an arrangement in which the coating layer and the inorganic oxide layer are located between the first substrate and the second substrate, and the coating layer and the first adhesive layer are adjacent to each other), for example, deterioration of the coating layer and the inorganic oxide layer can be further suppressed.

[0019] In one embodiment, the laminate of the present disclosure has a three-layer structure and includes, in this order, a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer. In this embodiment, it is preferable that the first substrate is a barrier substrate constituting a barrier film, and the barrier film is arranged so that the coating layer faces the first adhesive layer. With such an arrangement (i.e., an arrangement in which the coating layer and the inorganic oxide layer are located between the first substrate and the second substrate, and the coating layer and the first adhesive layer are adjacent to each other), for example, deterioration of the coating layer and the inorganic oxide layer can be further suppressed.

[0020] The laminate of the present disclosure exhibits excellent gas barrier properties (e.g., oxygen barrier properties and water vapor barrier properties, particularly oxygen barrier properties). A packaging bag made using the laminate of the present disclosure can suppress the deterioration of gas barrier properties even after heat sterilization treatment such as retort treatment and boiling treatment. From the viewpoint that the coating layer and the inorganic oxide layer are more appropriately protected when subjected to heat treatment and the gas barrier properties are stable, a laminate having a three-layer structure in which the coating layer and the inorganic oxide layer are located between the first substrate and the second substrate, and the coating layer and the first adhesive layer are adjacent to each other is preferred.

[0021] 1 to 4 are schematic cross-sectional views showing one embodiment of a laminate according to the present disclosure. The laminate 1 shown in FIG. 1 is an example of a two-layer structure. 1 includes, in this order, a barrier film 20, an adhesive layer 40, and a sealant layer 30. The barrier film 20 includes, in this order, a substrate (barrier substrate) 21, a surface coating layer 22, an inorganic oxide layer 23, and a covering layer 24. In this example, the barrier film 20 is disposed such that the inorganic oxide layer 24 faces the adhesive layer 40 and the substrate 21 is the outermost layer.

[0022] The laminate 1 shown in FIGS. 2 to 4 shows an example of a three-layer structure. 2 includes, in this order, a first substrate (stretched polypropylene substrate) 11, a first adhesive layer 40A, a barrier film 20, a second adhesive layer 40B, and a sealant layer 30. The barrier film 20 includes, in this order, a second substrate (barrier substrate) 21, a surface coating layer 22, an inorganic oxide layer 23, and a coating layer 24. In this example, the barrier film 20 is disposed so that the inorganic oxide layer 24 faces the second adhesive layer 40B, and the second substrate 21 faces the first adhesive layer 40A.

[0023] 3 includes, in this order, a first substrate (stretched polypropylene substrate) 11, a first adhesive layer 40A, a barrier film 20, a second adhesive layer 40B, and a sealant layer 30. The barrier film 20 includes, in this order, a second substrate (barrier substrate) 21, a surface coating layer 22, an inorganic oxide layer 23, and a coating layer 24. In this example, the barrier film 20 is disposed so that the inorganic oxide layer 24 faces the first adhesive layer 40A, and the second substrate 21 faces the second adhesive layer 40B.

[0024] 4 includes, in this order, a barrier film 20, a first adhesive layer 40A, a second substrate (stretched polypropylene substrate) 21, a second adhesive layer 40B, and a sealant layer 30. The barrier film 20 includes, in this order, a first substrate (barrier substrate) 11, a surface coating layer 22, an inorganic oxide layer 23, and a covering layer 24. In this example, the barrier film 20 is disposed such that the inorganic oxide layer 24 faces the first adhesive layer 40A and the first substrate 11 is the outermost layer.

[0025] 1 to 4 show an example of the structure of the laminate 1, and the laminate 1 is not limited thereto. For example, the laminate 1 may be configured without the surface coat layer 22, or may be configured with an optional layer (e.g., a printed layer, etc.) not shown between any of the above-mentioned layers.

[0026] The content of polypropylene in the total amount of resin materials contained in the laminate of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 88% by mass or more. The upper limit of the polypropylene content relative to the total amount of resin material contained in the laminate of the present disclosure is not particularly limited, and may be, for example, 99% by mass, 98% by mass, 97% by mass, 96% by mass, 95% by mass, or 94% by mass.

[0027] In this disclosure, the mono-material ratio refers to the ratio of a single polypropylene-based material to the total mass of the resin materials contained in the laminate. However, when a layer contains polypropylene as the main component (i.e., more than 50 mass%), the mono-material ratio is calculated assuming that polypropylene constitutes 100 mass% of the layer.

[0028] <Polypropylene oriented base material> The oriented polypropylene substrate contains polypropylene as a major component. The polypropylene may be any of a homopolymer, a random copolymer, and a block copolymer, and may be a mixture of two or more selected from these. As the polypropylene, biomass-derived polypropylene and / or recycled polypropylene may be used. A propylene homopolymer is a polymer of only propylene. A propylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene. A propylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of at least an α-olefin other than propylene. The polymer block of at least an α-olefin other than propylene may be a polymer block of propylene and an α-olefin other than propylene.

[0029] Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms other than propylene, specifically, ethylene, 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.

[0030] Among polypropylenes, random copolymers are preferred from the viewpoint of transparency, homopolymers are preferred when emphasis is placed on the rigidity and heat resistance of the packaging bag, and block copolymers are preferred when emphasis is placed on the impact resistance of the packaging bag.

[0031] From the viewpoint of film-forming property and processability, the melt flow rate (MFR) of polypropylene is preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, and also preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, for example, 0.1 g / 10 min or more and 50 g / 10 min or less. The MFR of polypropylene is measured in accordance with JIS K7210-1:2014, Method A, under conditions of a temperature of 230° C. and a load of 2.16 kg.

[0032] The polypropylene content in the polypropylene oriented base material is preferably greater than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.

[0033] The oriented polypropylene substrate may contain a resin material other than polypropylene, such as, for example, a polyolefin other than polypropylene, such as polyethylene, an acrylic resin, a vinyl resin, a cellulose resin, a polyamide, a polyester, or an ionomer resin. The stretched polypropylene substrate may contain additives, such as crosslinkers, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0034] The stretched polypropylene substrate is a polypropylene substrate that has been subjected to a stretching treatment. A laminate including the stretched polypropylene substrate is excellent in, for example, heat resistance, impact resistance, water resistance, and dimensional stability, and is suitable as a packaging material for forming a packaging bag that is to be subjected to, for example, a retort treatment or a boiling treatment. The stretching process may be uniaxial stretching or biaxial stretching. The stretching ratio in the case of stretching in the machine direction (flow direction of the substrate, MD direction) is preferably 2 times or more, more preferably 3 times or more, even more preferably 3.5 times or more, and also preferably 15 times or less, more preferably 8 times or less, and even more preferably 7 times or less. The stretching ratio in the case of stretching in the width direction (direction perpendicular to the MD direction, TD direction) is preferably 4 times or more, more preferably 5 times or more, even more preferably 6 times or more, and also preferably 20 times or less, more preferably 17 times or less, and even more preferably 15 times or less. By setting the stretching ratio at a certain level or more, the strength and heat resistance of the substrate can be improved, and the printability of the substrate can be improved. From the viewpoint of the breaking limit of the substrate, the stretching ratio is preferably a certain level or less. In addition, the stretching ratio in the MD direction is preferably smaller than the stretching ratio in the TD direction. The oriented polypropylene substrate is, for example, a biaxially oriented substrate.

[0035] The oriented polypropylene substrate may be surface-treated. This can improve the adhesion between the oriented polypropylene substrate and other layers, for example. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the stretched polypropylene substrate.

[0036] The oriented polypropylene substrate may have a single layer structure or a multi-layer structure. The thickness of the stretched polypropylene substrate is preferably 10 μm or more, more preferably 15 μm or more, and also preferably 100 μm or less, more preferably 50 μm or less, for example, 10 μm or more and 100 μm or less. A laminate having a stretched substrate with a thickness equal to or greater than the lower limit has, for example, excellent strength and heat resistance. A laminate having a stretched substrate with a thickness equal to or less than the upper limit has, for example, excellent processability.

[0037] In this specification, the thickness of the substrate and each layer is measured as follows. A block is prepared by embedding the laminate in an embedding resin, and the block is cut using a commercially available rotary microtome at room temperature (25°C) to prepare a cross section of the laminate. The cross section is obtained by cutting the laminate in the thickness direction perpendicular to the main surface. Finishing is performed with a diamond knife. The thickness of the substrate and each layer is the arithmetic average value of the thicknesses at five points measured by observing the cross section using a scanning electron microscope (SEM, Hitachi, Ltd., SU8000).

[0038] <Barrier film> The barrier film comprises an inorganic oxide layer provided on one surface of a substrate (barrier substrate). The barrier film further comprises a coating layer on the inorganic oxide layer. The barrier film may comprise a surface coating layer between the substrate (barrier substrate) and the inorganic oxide layer. The barrier film may be transparent.

[0039] (Polypropylene oriented base material) The substrate (barrier substrate) of the barrier film may be the oriented polypropylene substrate described in the section <oriented polypropylene substrate>. The oriented polypropylene substrate of the first substrate and the oriented polypropylene substrate of the second substrate may be the same or different.

[0040] The stretched polypropylene substrate of the barrier film may be, for example, a stretched substrate of another embodiment having a polypropylene layer, an optional adhesive resin layer, and a surface resin layer described later in this order. In this embodiment, the barrier film has a stretched substrate of another embodiment, an inorganic oxide layer provided on the surface resin layer of the stretched substrate, and a coating layer. In this embodiment, the barrier film has a polypropylene layer, an optional adhesive resin layer, a surface resin layer, an inorganic oxide layer, and a coating layer in this order. In one embodiment, the stretched substrate of another embodiment is a coextruded stretched resin film. The coextruded stretched resin film can be produced, for example, by forming a laminated film using a T-die method or an inflation method, and then stretching the laminated film.

[0041] In other embodiments, the stretching treatment of the stretched substrate may be uniaxial stretching or biaxial stretching. The stretching ratio in the MD direction is preferably 2 times or more, more preferably 3 times or more, and even more preferably 3.5 times or more, and is preferably 15 times or less, more preferably 8 times or less, and even more preferably 7 times or less. The stretching ratio in the TD direction is preferably 4 times or more, more preferably 5 times or more, and even more preferably 6 times or more, and is preferably 20 times or less, more preferably 17 times or less, and even more preferably 15 times or less. The stretching ratio in the MD direction is preferably smaller than the stretching ratio in the TD direction.

[0042] (Surface coating layer) The barrier film may have a surface coating layer containing a resin material having a polar group between the stretched polypropylene substrate and the inorganic oxide layer. Such a barrier film has excellent adhesion to the inorganic oxide layer and also has excellent gas barrier properties. Such a barrier substrate has a stretched polypropylene substrate, a surface coating layer, an inorganic oxide layer, and a coating layer in this order.

[0043] The polar group refers to a group containing one or more heteroatoms, and examples thereof include ester group, epoxy group, hydroxyl group, amino group, amide group, urethane group, carboxyl group, carbonyl group, carboxylic anhydride group, sulfo group, thiol group, and halogen group. Among these, carboxyl group, carbonyl group, ester group, hydroxyl group, amino group, amide group, and urethane group are preferred, and carboxyl group, hydroxyl group, amide group, and urethane group are more preferred.

[0044] Examples of resin materials having a polar group include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl-containing acrylic resin, polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon, and polyurethane. Among these, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, hydroxyl-containing acrylic resin, polyamide, and polyurethane are more preferred.

[0045] The surface coating layer can be formed, for example, using a water-based emulsion or a solvent-based emulsion. Examples of the water-based emulsion include a polyamide-based emulsion, a polyethylene-based emulsion, and a polyurethane-based emulsion. Examples of the solvent-based emulsion include an acrylic resin-based emulsion and a polyester-based emulsion.

[0046] The content of the resin material having a polar group in the surface coat layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The surface coating layer may contain the above-mentioned resin materials other than the resin material having a polar group. The surface coating layer may contain the above-mentioned additives.

[0047] The ratio of the thickness of the surface coat layer to the total thickness of the polypropylene stretched substrate and the surface coat layer is preferably 0.08% or more, more preferably 0.2% or more, even more preferably 1% or more, and also preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 5% or less, for example, 0.08% or more and 20% or less. The thickness of the surface coat layer is preferably 0.02 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, even more preferably 0.2 μm or more, and also preferably 10 μm or less, more preferably 5 μm or less, for example, 0.02 μm or more and 10 μm or less. When the ratio or thickness is equal to or more than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the deterioration of the gas barrier property can be suppressed, and the laminate strength of the laminate can be improved. When the ratio or thickness is equal to or less than the upper limit, for example, the processability of the barrier film and the recyclability of the laminate can be improved.

[0048] For example, polypropylene or a resin composition containing polypropylene is formed into a film using a T-die method, an inflation method, or the like to obtain a polypropylene substrate, and then the substrate is stretched. A coating liquid for forming a surface coating layer is applied to the obtained stretched substrate, and the substrate is dried, thereby producing a resin substrate having a polypropylene stretched substrate and a surface coating layer.

[0049] (Polypropylene layer, surface resin layer and adhesive resin layer) In another embodiment of the stretched substrate, the polypropylene layer contains polypropylene as a main component. The details of polypropylene are as described above, and will not be described in this section. The content of polypropylene in the polypropylene layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.

[0050] The polypropylene layer may contain the above-mentioned resin materials other than polypropylene. The polypropylene layer may contain the additives described above.

[0051] The polypropylene layer may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene layer is preferably 10 μm or more, more preferably 15 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less, for example, 10 μm or more and 100 μm or less.

[0052] The surface resin layer contains a resin material having a melting point of 180° C. or higher (hereinafter also referred to as a “high melting point resin material”). By providing a surface resin layer containing a high melting point resin material between a polypropylene layer and an inorganic oxide layer, for example, it is possible to improve the adhesion of the inorganic oxide layer formed on the surface resin layer and also to suppress a decrease in gas barrier properties.

[0053] The melting point of the high melting point resin material is preferably 185°C or higher, more preferably 190°C or higher, and even more preferably 205°C or higher. When the melting point is equal to or higher than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the deterioration of the gas barrier property can be suppressed, and the laminate strength of the laminate can be improved. The melting point of the high melting point resin material is preferably 265°C or lower, more preferably 260°C or lower, and even more preferably 250°C or lower. This can improve, for example, the film formability of the stretched substrate.

[0054] In this specification, the melting point of the high melting point resin material and the like is measured in accordance with JIS K7121:2012 (Method of measuring transition temperature of plastics). Specifically, a differential scanning calorimetry (DSC) device is used to measure a DSC curve at a heating rate of 10°C / min, and the melting peak temperature is determined as the melting point.

[0055] The high melting point resin material preferably has a polar group. The polar group refers to a group containing one or more heteroatoms, and examples thereof include ester groups, epoxy groups, hydroxyl groups, amino groups, amide groups, urethane groups, carboxy groups, carbonyl groups, carboxylic anhydride groups, sulfo groups, thiol groups, and halogen groups. Among these, hydroxyl groups, ester groups, amino groups, amide groups, carboxy groups, and carbonyl groups are preferred, and amide groups are more preferred.

[0056] The high melting point resin material may have a melting point of 180° C. or higher, and examples of the high melting point resin material include polyolefin, vinyl resin, acrylic resin, polyamide, polyimide, polyester, cellulose resin, and ionomer resin. For example, a resin material having a melting point of 180° C. or higher and a polar group is preferable, and ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyester, and polyamide such as nylon 6 and nylon 6,6 are more preferable.

[0057] The content of the high melting point resin material in the surface resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more.

[0058] The surface resin layer may contain the above-mentioned resin materials other than the high melting point resin material. The surface resin layer may contain the above-mentioned additives. The surface resin layer may be subjected to the above-mentioned surface treatment.

[0059] The ratio of the thickness of the surface resin layer to the total thickness of the stretched substrate of another embodiment having a polypropylene layer and a surface resin layer is preferably 1% or more, more preferably 1.5% or more, and also preferably 10% or less, more preferably 5% or less, for example 1% or more and 10% or less. The thickness of the surface resin layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and also preferably 5 μm or less, more preferably 4 μm or less, for example 0.1 μm or more and 5 μm or less. When the above ratio or thickness is equal to or more than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the deterioration of the gas barrier property can be suppressed, and the laminate strength of the laminate can be improved. When the above ratio or thickness is equal to or less than the upper limit, for example, the film-forming property and processability of the stretched substrate of another embodiment, and the recyclability of the laminate can be improved.

[0060] The stretched substrate of another embodiment may have an adhesive resin layer between the polypropylene layer and the surface resin layer. This can improve the adhesion between these layers. The thickness of the adhesive resin layer is, for example, 1 μm or more and 15 μm or less. The adhesive resin layer can be formed, for example, from an adhesive resin. Examples of adhesive resins include polyether, polyester, polyurethane, silicone resin, epoxy resin, vinyl resin, phenolic resin, polyolefin, and acid-modified polyolefin. Among these, polyolefin and its acid-modified polyolefin are preferred from the viewpoint of recyclability of the laminate, and polypropylene and its acid-modified polyolefin are more preferred.

[0061] (Inorganic oxide layer) The barrier film comprises an inorganic oxide layer on one side of a barrier substrate. The inorganic oxide layer comprises one or more inorganic oxides, for example, a vapor-deposited film of an inorganic oxide. A laminate comprising a barrier film has excellent gas barrier properties, specifically, oxygen barrier properties and water vapor barrier properties. A packaging bag produced using such a laminate can suppress oxidation deterioration of the contents filled in the packaging bag, and suppress the mass loss of the contents. The barrier film may, for example, comprise an inorganic oxide layer on a surface coat layer, or may comprise an inorganic oxide layer on a surface resin layer.

[0062] Examples of inorganic oxides include aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide). Among these, silica, silicon carbide oxide, and alumina are preferred.

[0063] In one embodiment, silica is more preferable as the inorganic oxide since no aging treatment is required after the formation of the inorganic oxide layer.In one embodiment, carbon-containing silicon oxide is more preferable as the inorganic oxide since the deterioration of the gas barrier property can be suppressed even when the laminate is bent.

[0064] The thickness of the inorganic oxide layer is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and is preferably 150 nm or less, more preferably 60 nm or less, even more preferably 40 nm or less, for example, 1 nm or more and 150 nm or less. A laminate having an inorganic oxide layer whose thickness is equal to or greater than the lower limit has, for example, excellent oxygen barrier properties and water vapor barrier properties. A laminate having an inorganic oxide layer whose thickness is equal to or less than the upper limit can, for example, suppress the occurrence of cracks in the inorganic oxide layer and has excellent recyclability.

[0065] The surface of the inorganic oxide layer may be subjected to the above-mentioned surface treatment.

[0066] Methods for forming inorganic oxide layers, particularly inorganic oxide vapor deposition films, include, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0067] The inorganic oxide layer may be a single layer formed by one deposition process, or may be a multilayer formed by multiple deposition processes. When the inorganic oxide layer is a multilayer, each layer may be composed of the same inorganic oxide or different inorganic oxides. Each layer may be formed by the same method or different methods.

[0068] The inorganic oxide layer is preferably a vapor-deposited film formed by a CVD method, and more preferably a carbon-containing silicon oxide vapor-deposited film formed by a CVD method. A laminate including such an inorganic oxide layer has, for example, excellent bending resistance.

[0069] The carbon-containing silicon oxide vapor deposition film contains silicon, oxygen and carbon. In one embodiment of the carbon-containing silicon oxide vapor deposition film, the carbon ratio C is preferably 3% or more, more preferably 5% or more, even more preferably 10% or more, and is preferably 50% or less, more preferably 40% or less, even more preferably 35% or less, for example, 3% or more and 50% or less, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the carbon ratio C in the above range, for example, even if the laminate is bent, the deterioration of the gas barrier property can be suppressed. In this specification, the ratio of each element is on a molar basis.

[0070] In one embodiment of the carbon-containing silicon oxide vapor deposition film, the silicon ratio Si is preferably 1% or more, more preferably 3% or more, even more preferably 8% or more, and is preferably 45% or less, more preferably 38% or less, even more preferably 33% or less, for example 1% or more and 45% or less, relative to the total of the three elements silicon, oxygen and carbon 100%. The oxygen ratio O is preferably 10% or more, more preferably 20% or more, even more preferably 25% or more, and is preferably 70% or less, more preferably 65% ​​or less, even more preferably 60% or less, for example 10% or more and 70% or less, relative to the total of the three elements silicon, oxygen and carbon 100%. By setting the silicon ratio Si and the oxygen ratio O in the above ranges, for example, even if the laminate is bent, the deterioration of the gas barrier property can be further suppressed.

[0071] In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the oxygen ratio O is preferably higher than the carbon ratio C, and the silicon ratio Si is preferably lower than the carbon ratio C. The oxygen ratio O is preferably higher than the silicon ratio Si, that is, the ratios are preferably in the order of O, C, and Si. This makes it possible to further suppress the deterioration of the gas barrier properties even when the laminate is bent, for example.

[0072] The proportions C, Si, and O in the carbon-containing silicon oxide vapor-deposited film are measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the following measurement conditions.

[0073] (Measurement conditions) Equipment used: "ESCA-3400" (manufactured by Kratos) [1] Spectral collection conditions Incident X-ray: MgKα (monochromatic X-ray, hν=1253.6eV) X-ray output: 150W (10kV 15mA) X-ray scanning area (measurement area): Approx. 6 mm φ Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar+ Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Etching range: 10mmφ Ion sputtering time: 30 seconds, spectrum collected

[0074] (covering layer) The barrier film further comprises a coating layer on the inorganic oxide layer provided on one side of the barrier substrate. That is, the barrier film further comprises a coating layer on the side of the inorganic oxide layer opposite to the side facing the stretched polypropylene substrate. A laminate including such a barrier film has, for example, excellent oxygen barrier properties and water vapor barrier properties.

[0075] The coating layer of the barrier film is preferably close to the first adhesive layer or the second adhesive layer, and more preferably adjacent to it. Here, the coating layer and the adhesive layer (the first adhesive layer or the second adhesive layer) being close to each other means that an arbitrary layer having a thickness that does not impair the effect of the present invention is located between the coating layer and the adhesive layer, and the coating layer and the adhesive layer are arranged so as to face each other through this arbitrary layer. Moreover, the coating layer and the adhesive layer being adjacent to each other means that no other layer exists between the coating layer and the adhesive layer, and the coating layer and the adhesive layer are arranged so as to be in contact with each other.

[0076] In one embodiment, the coating layer contains a resin component. Examples of the resin component include polyolefins such as polyethylene, polypropylene, polybutene, and polymethylpentene, vinyl resins, acrylic resins, polyesters, urethane resins, melamine resins, and epoxy resins. The content of the resin component in the coating layer is preferably more than 50% by mass, more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, for example, more than 50% by mass and 95% by mass or less. The coating layer may contain the above-mentioned additives.

[0077] The thickness of the coating layer is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 5 μm or less, more preferably 3 μm or less, even more preferably 1 μm or less, for example, 0.01 μm or more and 5 μm or less. Such a coating layer has, for example, excellent scratch resistance.

[0078] The coating layer can be formed, for example, by applying a coating liquid for the coating layer to the surface of the inorganic oxide layer and drying it. The coating liquid for the coating layer can be prepared, for example, by mixing the above-mentioned resin component and, if necessary, an additive and a solvent. Details of these components are as described above. Examples of the coating method for the coating liquid for the coating layer include known coating methods. Examples of the drying method for the applied coating liquid for the coating layer include methods that apply heat, such as hot air drying, hot roll drying, and infrared irradiation. The drying temperature may be 50°C or higher, or 150°C or lower.

[0079] In one embodiment, the coating layer may be a barrier coat layer containing a gas barrier resin. Examples of the gas barrier resin include ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyamide such as nylon 6, nylon 6,6 and polymetaxylylene adipamide, polyurethane, and acrylic resin. The content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Such a barrier coat layer has, for example, excellent gas barrier properties. The barrier coat layer may contain the above-mentioned additives.

[0080] The thickness of the barrier coat layer containing the gas barrier resin is preferably 0.01 μm or more, more preferably 0.1 μm or more, and also preferably 10 μm or less, more preferably 5 μm or less, for example, 0.01 μm or more and 10 μm or less. A barrier substrate having a barrier coat layer whose thickness is equal to or greater than the lower limit has, for example, excellent gas barrier properties. A barrier film having a barrier coat layer whose thickness is equal to or less than the upper limit can improve, for example, the processability and recyclability of the laminate.

[0081] The barrier coat layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent, applying the resulting coating liquid to the surface of the inorganic oxide layer, and drying it. The barrier coat layer can also be formed, for example, by applying a commercially available barrier coating agent and drying it.

[0082] In one embodiment, the coating layer may be a gas barrier coating film formed by polycondensation treatment of a composition containing a metal alkoxide and a water-soluble polymer by a sol-gel method in the presence of a sol-gel catalyst, water, an organic solvent, etc. A barrier film having a gas barrier coating film on an inorganic oxide layer has, for example, excellent gas barrier properties. The gas barrier coating film contains a hydrolysis polycondensate obtained by hydrolyzing and polycondensing the above-mentioned metal alkoxide, etc. by a sol-gel method. By providing such a gas barrier coating film on the inorganic oxide layer, for example, the occurrence of cracks in the inorganic oxide layer can be effectively suppressed.

[0083] The metal alkoxide is represented, for example, by the formula (A). R 1 n M(OR 2 ) m (A) In formula (A), R 1 and R 2 each independently represents an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the atomic valence of M. 1 and R 2In the above, examples of the organic group include alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, and n-octyl. The metal atom M is, for example, silicon, zirconium, titanium, or aluminum. Examples of the metal alkoxide include alkoxysilanes, such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0084] Examples of the water-soluble polymer include hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination, depending on the desired physical properties such as oxygen barrier property, water vapor barrier property, water resistance, and weather resistance. Also, a gas barrier coating film obtained using polyvinyl alcohol and a gas barrier coating film obtained using ethylene-vinyl alcohol copolymer may be laminated. The amount of the water-soluble polymer used is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 500 parts by mass or less, based on 100 parts by mass of the metal alkoxide.

[0085] A silane coupling agent may be used together with the metal alkoxide. As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and an organoalkoxysilane having an epoxy group is preferable, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane can be mentioned. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the metal alkoxide.

[0086] The gas barrier composition may contain water in a ratio of preferably 0.1 mol or more, more preferably 0.5 mol or more, and preferably 100 mol or less, more preferably 60 mol or less, per mol of metal alkoxide. By making the water content equal to or greater than the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved. By making the water content equal to or less than the upper limit, for example, the hydrolysis reaction can be carried out quickly.

[0087] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butyl alcohol.

[0088] The sol-gel catalyst is preferably an acid or an amine compound. Examples of the acid include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less per mol of the total amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

[0089] As the amine compound, the tertiary amine that is substantially insoluble in water and soluble in organic solvent is suitable, for example, N,N-dimethylbenzylamine, tripropylamine, tributylamine and tripentylamine can be mentioned.The amount of the amine compound used is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and also preferably 1.0 parts by mass or less, more preferably 0.3 parts by mass or less, based on 100 parts by mass of the total amount of metal alkoxide and silane coupling agent.

[0090] Examples of methods for applying the gas barrier composition include application means such as roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

[0091] Hereinafter, one embodiment of the method for forming a gas barrier coating film will be described. A gas barrier composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent. A polycondensation reaction gradually proceeds in the composition. The composition is applied on an inorganic oxide layer by a conventional method and dried. This drying causes further polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains a silane coupling agent) to form a composite polymer layer. The above operation may be repeated to laminate a plurality of composite polymer layers. For example, the applied composition is heated at a temperature of preferably 20° C. or higher, more preferably 50° C. or higher, and even more preferably 70° C. or higher, and also at a temperature of preferably 150° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower for 1 second to 10 minutes. This allows the formation of a gas barrier coating film.

[0092] The thickness of the gas barrier coating film is preferably 0.01 μm or more, more preferably 0.1 μm or more, and is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less, for example, 0.01 μm or more and 2 μm or less, which can, for example, prevent deterioration of gas barrier properties, prevent cracks from occurring in the inorganic oxide layer, and improve the recyclability of the packaging bag.

[0093] <Print layer> The laminate of the present disclosure may include a printed layer on the surface of a substrate such as a first substrate and a second substrate, or between any layers. The image formed on the printed layer is not particularly limited, and may be a character, a pattern, a symbol, or a combination thereof. The printed layer may be formed using an ink derived from biomass. This can further reduce the environmental load.

[0094] Examples of methods for forming the printed layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of reducing the environmental load. The thickness of the printed layer is, for example, not less than 0.5 μm and not more than 3 μm.

[0095] <Sealant layer> The laminate of the present disclosure includes a sealant layer. The sealant layer contains polypropylene as a main component. The sealant layer contains the same type of resin material as the oriented polypropylene substrate, i.e., polypropylene as a main component. This allows the laminate to be made into a mono-material. In other words, after collecting used packaging bags, there is no need to separate the substrate and the sealant layer, improving the recyclability of the packaging bags.

[0096] The content of polypropylene in the sealant layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more. A laminate having such a sealant layer has, for example, excellent recyclability.

[0097] Examples of polypropylene include propylene homopolymers, propylene random copolymers such as propylene-α-olefin random copolymers, and propylene block copolymers such as propylene-α-olefin block copolymers. The details of the α-olefins are as described above. From the viewpoint of heat sealability, the density of the polypropylene is, for example, 0.88 g / cm3 or more and 0.92 g / cm3 or less. The density is measured in accordance with JIS K7112:1999 D method (density gradient tube method, 23°C). From the viewpoint of reducing the environmental load, biomass-derived polypropylene and / or recycled polypropylene may be used. The sealant layer may contain the above-mentioned additives.

[0098] The sealant layer may have a single-layer structure or a multi-layer structure. The thickness of the sealant layer is preferably 10 μm or more, more preferably 20 μm or more, and also preferably 200 μm or less, more preferably 150 μm or less, for example, 10 μm or more and 200 μm or less. A laminate having a sealant layer whose thickness is equal to or greater than the lower limit has, for example, excellent seal strength. A laminate having a sealant layer whose thickness is equal to or less than the upper limit has, for example, excellent processability. When a pouch (particularly a retort pouch) is produced from the laminate, the thickness of the sealant layer is preferably 30 μm or more, and also preferably 100 μm or less.

[0099] From the viewpoint of heat sealability, the sealant layer is preferably an unstretched polypropylene film, and the unstretched polypropylene film can be produced by utilizing, for example, a cast method, a T-die method, an inflation method, or the like. The sealant layer may be subjected to the above-mentioned surface treatment.

[0100] <Adhesive layer> In one embodiment, the laminate of the present disclosure comprises an adhesive layer between the barrier film and the sealant layer. In one embodiment, the laminate of the present disclosure comprises a first adhesive layer between the first substrate and the second substrate. In one embodiment, the laminate of the present disclosure comprises a second adhesive layer between the second substrate and the sealant layer. Such a laminate has excellent lamination strength, for example, between the barrier film / sealant layer, between the first substrate / second substrate, and between the second substrate / sealant layer.

[0101] (First adhesive layer) The elastic modulus of the cross section of the first adhesive layer measured using an atomic force microscope (AFM) is 100.0 MPa or less, preferably 50.0 MPa or less, more preferably 40.0 MPa or less, even more preferably 35.0 MPa or less, and particularly preferably 30.0 MPa or less. A packaging bag produced using a laminate having a first adhesive layer with an elastic modulus of the upper limit or less can suppress a decrease in gas barrier properties (e.g., oxygen barrier properties and water vapor barrier properties, especially oxygen barrier properties) even after heat treatment such as retort treatment, and tends to have excellent appearance. When a printing layer is provided on the surface of the first substrate facing the first adhesive layer, the first adhesive layer with an elastic modulus of the upper limit or less tends to have excellent adhesion to the printing layer.

[0102] The elastic modulus of the cross section of the first adhesive layer measured using AFM is preferably 5.0 MPa or more, more preferably 10.0 MPa or more, even more preferably 15.0 MPa or more, even more preferably 16.0 MPa or more, and particularly preferably 18.0 MPa or more. A packaging bag produced using a laminate including a first adhesive layer having an elastic modulus equal to or greater than the lower limit can suppress deterioration of gas barrier properties even after heat treatment such as retort treatment, and tends to have excellent appearance. The elastic modulus of the first adhesive layer is, for example, not less than 5.0 MPa and not more than 100.0 MPa. Details of the conditions for measuring the elastic modulus by AFM are described in the Examples section.

[0103] The first adhesive layer having the above elastic modulus can be formed, for example, by using a solvent-based adhesive as described below, and by appropriately changing the type and molecular weight of the polymer component contained in the base agent, the type of curing agent, the molar ratio (NCO / OH), and the aging conditions, as described below.

[0104] The thickness of the first adhesive layer is preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 2.0 μm or more, particularly preferably 2.5 μm or more, and also preferably 10.0 μm or less, more preferably 8.0 μm or less, even more preferably 6.0 μm or less, particularly preferably 5.0 μm or less, for example, 1.0 μm or more and 10.0 μm or less. When a printed layer is provided on the surface of the first substrate facing the first adhesive layer, the first adhesive layer having a thickness of the lower limit or more can well cover the step caused by the printed layer, and tends to be able to obtain a packaging bag with a good appearance. A laminate having a first adhesive layer having a thickness of the lower limit or more tends to have excellent lamination strength even after heat treatment.

[0105] The thickness of the first adhesive layer relative to the total thickness of the laminate is preferably 1.0% or more, more preferably 1.5% or more, even more preferably 2.0% or more, and particularly preferably 2.5% or more, and is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 6.0% or less, and particularly preferably 5.0% or less, for example, 1.0% or more and 10.0% or less.

[0106] (Second adhesive layer) The thickness of the second adhesive layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.0 μm or more, particularly preferably 3.0 μm or more, and is preferably 10.0 μm or less, more preferably 8.0 μm or less, even more preferably 6.0 μm or less, particularly preferably 5.0 μm or less, for example, 0.5 μm or more and 10.0 μm or less. A laminate having a second adhesive layer whose thickness is equal to or more than the lower limit can suppress elongation of the sealant layer when cut.

[0107] In one embodiment (A), the elastic modulus measured by AFM for the cross section of the second adhesive layer is preferably 35.0 MPa or less, more preferably 33.0 MPa or less, even more preferably 30.0 MPa or less, even more preferably 28.0 MPa or less, particularly preferably 26.0 MPa or less, and also preferably 5.0 MPa or more, more preferably 10.0 MPa or more, even more preferably 15.0 MPa or more, even more preferably 16.0 MPa or more, particularly preferably 18.0 MPa or more, for example, 5.0 MPa or more and 35.0 MPa or less. A packaging bag produced using a laminate having a second adhesive layer having such an elastic modulus tends to be able to suppress the deterioration of gas barrier properties even after heat treatment such as retort treatment. The second adhesive layer having such an elastic modulus can be formed, for example, by using a solvent-based adhesive described later, and by appropriately changing the type and molecular weight of the polymer component contained in the main agent, the type of curing agent, the molar ratio (NCO / OH), and the aging conditions described later.

[0108] When the second adhesive layer has the modulus of elasticity of one embodiment (A), in one embodiment, the modulus of elasticity of the second adhesive layer is smaller than that of the first adhesive layer. A packaging bag made using a laminate of this type tends to have better impact resistance, and therefore better resistance to bag breakage due to dropping, as well as better seal strength. This is presumably because the smaller modulus of elasticity of the second adhesive layer can prevent the surface layer of the second substrate from peeling off, and therefore prevent a decrease in the laminate strength between the second substrate and the sealant layer.

[0109] When the second adhesive layer has the elastic modulus of embodiment (A), in one embodiment, the elastic modulus of the second adhesive layer is greater than the elastic modulus of the first adhesive layer. A packaging bag made using a laminate of this type tends to have excellent tearability, and therefore excellent openability.

[0110] When the second adhesive layer has the elastic modulus of one embodiment (A), the thickness of the second adhesive layer is, in one embodiment, preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 2.0 μm or more, particularly preferably 2.5 μm or more, and also preferably 10.0 μm or less, more preferably 8.0 μm or less, even more preferably 6.0 μm or less, particularly preferably 5.0 μm or less, for example, 1.0 μm or more and 10.0 μm or less. In this embodiment, the thickness of the second adhesive layer relative to the thickness of the entire laminate is preferably 1.0% or more, more preferably 1.5% or more, even more preferably 2.0% or more, particularly preferably 2.5% or more, and also preferably 10.0% or less, more preferably 8.0% or less, even more preferably 6.0% or less, particularly preferably 4.0% or less. A laminate having such a second adhesive layer tends to have excellent laminate strength even after heat treatment.

[0111] When the second adhesive layer has the elastic modulus of one embodiment (A), the thickness of the first adhesive layer is greater than the thickness of the second adhesive layer in one embodiment. When a printed layer is provided on the surface of the first substrate facing the first adhesive layer, the first adhesive layer can well cover the step caused by the printed layer, and there is a tendency that a packaging bag with a good appearance can be obtained. The ratio of the thickness 1 of the first adhesive layer to the thickness 2 of the second adhesive layer (thickness 1 / thickness 2) may be, for example, 0.4 or more, 0.6 or more, or 0.8 or more. When the thickness of the first adhesive layer is greater than the thickness of the second adhesive layer, it may be more than 1.0, and may be 2.5 or less, 1.8 or less, or 1.2 or less.

[0112] In one embodiment (B), the elastic modulus measured by AFM on the cross section of the second adhesive layer is 100 MPa or less, more preferably 90 MPa or less, even more preferably 80.0 MPa or less, 70.0 MPa or less, 60.0 MPa or less, or 50.0 MPa or less, and is preferably more than 35.0 MPa, for example, more than 35.0 MPa and 100 MPa or less. A laminate having a second adhesive layer with an elastic modulus of less than the upper limit tends to have excellent lamination strength. A second adhesive layer having such an elastic modulus can be formed, for example, by using a solvent-free adhesive described later, and by appropriately changing the type and molecular weight of the polymer component contained in the base agent, the type of curing agent, the molar ratio (NCO / OH), and the aging conditions described later.

[0113] When the second adhesive layer has the elastic modulus of one embodiment (B), the thickness of the second adhesive layer is, in one embodiment, preferably 3.0 μm or less, more preferably 2.5 μm or less, even more preferably 2.0 μm or less, even more preferably 1.5 μm or less, and also preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.0 μm or more, for example 0.5 μm or more and 3.0 μm or less. In this embodiment, the thickness of the second adhesive layer relative to the thickness of the entire laminate is preferably 0.5% or more, more preferably 0.8% or more, even more preferably 1.0% or more, and also preferably 3.0% or less, more preferably 2.5% or less, even more preferably 2.0% or less, even more preferably 1.5% or less, for example 0.5% or more and 3.0% or less. In one embodiment, the thickness of the second adhesive layer is smaller than the thickness of the first adhesive layer. A packaging bag made using such a laminate having a second adhesive layer tends to have excellent impact resistance, and therefore excellent resistance to dropping and breaking, as well as excellent tearability, and therefore excellent openability. In addition, the packaging bag has excellent recyclability, for example.

[0114] (glue) The first adhesive layer and the second adhesive layer are each composed of an adhesive. The adhesive forming the first adhesive layer and the adhesive forming the second adhesive layer may be the same or different. The adhesive may be any of a one-component curing adhesive, a two-component curing adhesive, and a non-curing adhesive, and a two-component curing adhesive is preferred from the viewpoint of easily adjusting the elastic modulus and softening point to the above-mentioned range.

[0115] A method for obtaining a laminate using an adhesive includes a method in which an adhesive is applied to an object, and then another object is placed on the formed adhesive layer, and the adhesive layer sandwiched between the two is allowed to harden. Examples of the object include a first substrate, a second substrate, and a sealant film. The process of allowing the adhesive layer to harden is also referred to as the "aging process" below.

[0116] The aging conditions of the adhesive are described below. The aging temperature is preferably 25°C or higher, more preferably 30°C or higher, and even more preferably 35°C or higher, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower. The aging time is preferably 5 hours or higher, more preferably 10 hours or higher, and even more preferably 20 hours or higher, and is preferably 150 hours or lower, more preferably 135 hours or lower, and even more preferably 120 hours or lower. By increasing the aging temperature, the elastic modulus of the adhesive layer tends to increase. By increasing the aging time, the elastic modulus of the adhesive layer tends to increase.

[0117] Examples of adhesives include polyurethane adhesives, polyester adhesives, polyether adhesives, rubber adhesives, vinyl adhesives, olefin adhesives, silicone adhesives, epoxy adhesives, and phenol adhesives. Among these, polyurethane adhesives, polyester adhesives, and polyether adhesives are preferred, polyurethane adhesives and polyester adhesives are more preferred, and polyurethane adhesives are even more preferred, with two-liquid hardeners being preferred, from the viewpoint of ease of adjusting the elastic modulus and softening point to the above-mentioned ranges. A curable polyurethane adhesive is particularly preferred.

[0118] The adhesive may be a solvent-based adhesive or a solventless adhesive. A solvent-based adhesive is an adhesive used in a method in which the adhesive is applied to an object, heated in an oven or the like to volatilize the solvent in the adhesive, and then the adhesive is bonded to another object. In the case of a two-liquid curing adhesive, either the base agent or the curing agent, or both, contain a solvent. Examples of the solvent include organic solvents, specifically, hydrocarbon solvents such as toluene, xylene, n-hexane, and methylcyclohexane; ester solvents such as ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate; alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol; and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0119] A solvent-free adhesive is an adhesive that is applied to an object and then bonded to another object without necessarily going through a process of heating in an oven or the like to volatilize the solvent. In the case of a two-component curing adhesive, both the base agent and the curing agent are substantially free of solvent. "Substantially free of solvent" includes cases where the solvent used as a reaction medium during the manufacture of the adhesive's components, or the base agent and / or curing agent in the case of a two-component curing adhesive, is not completely removed, leaving trace amounts of solvent remaining in the adhesive, or the base agent and / or curing agent in the case of a two-component curing adhesive.

[0120] The two-component curing polyurethane adhesive has a base agent and a curing agent. The two-component curing polyurethane adhesive may be a solvent-based adhesive or a solventless adhesive. The two-component curing polyurethane adhesive will be described below.

[0121] The polyurethane adhesive has, for example, a base agent containing a polyol compound and a curing agent containing a polyisocyanate compound. Examples of the cured product (reaction product) formed by mixing such a base agent and a curing agent include polyurethane, specifically polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, and acrylic polyurethane.

[0122] The polyol compound has two or more hydroxyl groups in one molecule. Examples of the polyol compound include polyester polyurethane polyol, polyester polyol, polyether polyol, polycarbonate polyol and acrylic polyol. Among these, polyester polyurethane polyol and polyester polyol are preferred from the viewpoint of easily obtaining an adhesive layer having an elastic modulus in the above-mentioned range, and in the case of a solvent-based adhesive, polyester polyurethane polyol is more preferred, and in the case of a solventless adhesive, polyester polyol is more preferred.

[0123] Polyester polyurethane polyol is a compound having two or more hydroxy groups, ester bonds, and urethane bonds in one molecule, and has, for example, a polyester polyurethane structure as the main skeleton. Polyester polyol is a compound having two or more hydroxy groups and ester bonds in one molecule, and has, for example, a polyester structure as the main skeleton. Polyether polyol is a compound having two or more hydroxy groups and ether bonds in one molecule. Polycarbonate polyol is a compound having two or more hydroxy groups and carbonate bonds in one molecule.

[0124] The weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the base of the two-component curing and solvent-based adhesive is preferably 11,000 or more, more preferably 13,000 or more, even more preferably 15,000 or more, even more preferably 18,000 or more, particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 40,000 or less, from the viewpoint of coating suitability. The smaller the Mw, the higher the elastic modulus of the adhesive layer tends to be, and the larger the Mw, the lower the elastic modulus of the adhesive layer tends to be. In addition, the smaller the Mw, the shorter the molecular chain of the polymer component becomes, and the denser the polymer component becomes, and the higher the softening point of the adhesive layer tends to be. Conversely, the larger the Mw, the longer the molecular chain of the polymer component becomes, and the lower the softening point of the adhesive layer tends to be. The polydispersity (Mw / Mn) of the polymer component (e.g., polyol compound) contained in the base agent is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less, and is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more, where Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent. Each average molecular weight is measured by gel permeation chromatography (GPC) in accordance with JIS K7252-1: 2016, and is expressed as a polystyrene equivalent value. For the GPC measurement, a measuring device HLC-8220GPC (manufactured by Tosoh Corporation) can be used, a column consisting of TSKgel GHMHQ-H and TSK guardcolumn HHQ-H connected in series can be used, and dimethylformamide (DMF) can be used as the eluent.

[0125] From the viewpoint of coatability, the weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the base agent of the two-component curing solventless adhesive is preferably 800 or more, more preferably 1,200 or more, and even more preferably 2,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less, and even more preferably 6,000 or less. The smaller the Mw, the higher the elastic modulus of the adhesive layer tends to be, and the larger the Mw, the lower the elastic modulus of the adhesive layer tends to be. The polydispersity (Mw / Mn) of the polymer component (e.g., polyol compound) contained in the base agent is preferably 2.8 or less, more preferably 2.7 or less, even more preferably 2.6 or less, particularly preferably 2.5 or less, and is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 2.0 or more, where Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent.

[0126] The polyisocyanate compound has two or more isocyanate groups in one molecule. Examples of the polyisocyanate compound include aromatic isocyanates and aliphatic isocyanates. The polyisocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known and conventional appropriate method.

[0127] Examples of polyisocyanate compounds include aliphatic isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), norbornene diisocyanate, and isophorone diisocyanate (IPDI); aromatic isocyanate compounds such as diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate, tolylene diisocyanate (TDI), naphthalene diisocyanate, and α,α,α',α'-tetramethyl-m-xylylene diisocyanate, dimers and trimers (e.g., isocyanurate bodies) derived from these compounds; and adducts, biuret bodies, and allophanate bodies obtained by reacting these compounds with low-molecular-weight active hydrogen compounds or their alkylene oxide adducts, or high-molecular-weight active hydrogen compounds.

[0128] Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexamethylene glycol, 1,8-octamethylene glycol, 1,4-cyclohexanedimethanol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine and metaxylylenediamine, and trimethylolpropane is preferred. Examples of high molecular weight active hydrogen compounds include polyester, polyether polyol and polyamide.

[0129] The base agent containing a polyol compound and the curing agent containing a polyisocyanate compound are preferably used in such an amount ratio that the molar ratio (NCO / OH) between the total isocyanate groups of the polyisocyanate compound and the total hydroxyl groups of the polyol compound is as follows. That is, the molar ratio (NCO / OH) is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.5 or more, and is preferably 8.0 or less, more preferably 6.0, even more preferably 5.0 or less, and in the case of a solventless adhesive, it is even more preferably 4.0 or less, particularly preferably 3.0 or less. The larger the molar ratio (NCO / OH), the higher the elastic modulus of the adhesive layer tends to be, and the smaller the molar ratio (NCO / OH), the lower the elastic modulus of the adhesive layer tends to be.

[0130] [Packaging bag] The laminate of the present disclosure is preferably used as a packaging material. The packaging material is used to produce a packaging bag. The packaging bag of the present disclosure includes the laminate. The laminate of the present disclosure can be used as a packaging material to produce a packaging bag. In one embodiment, the laminate of the present disclosure is folded in half and stacked so that the base material or the first base material is located on the outside and the sealant layer is located on the inside, and the ends or the like are heat-sealed to produce a packaging bag. In another embodiment, a plurality of laminates of the present disclosure are stacked so that the sealant layers face each other, and the ends or the like are heat-sealed to produce a packaging bag. The entire packaging bag may be composed of the laminate, or a part of the packaging bag may be composed of the laminate.

[0131] Examples of packaging bags include packaging bags of various shapes such as standing pouch type, side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, grooving seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, gusset type, etc. Examples of heat sealing methods include bar seal, rotary roll seal, belt seal, impulse seal, high frequency seal, and ultrasonic seal.

[0132] The packaging bag may have an easy-to-open portion. Examples of the easy-to-open portion include a notch portion that serves as a starting point for tearing the packaging bag, and a half-cut line formed by laser processing or a cutter as a path for tearing the packaging bag.

[0133] The packaging bag may include a steam release mechanism. The steam release mechanism is configured to communicate between the inside and outside of the packaging bag when the steam pressure inside the packaging bag reaches or exceeds a predetermined value, to release steam, and to suppress steam from escaping at locations other than the steam release mechanism. The steam release mechanism includes, for example, a steam release seal portion protruding from the side seal portion toward the inside of the packaging bag, and a non-seal portion isolated from the content storage portion by the steam release seal portion. The non-seal portion communicates with the outside of the packaging bag. The packaging bag filled with the content and with the opening heat-sealed is heated using a microwave oven or the like. This increases the internal pressure, causing the steam release seal portion to peel off. Steam passes through the peeled portion of the steam release seal portion and the non-seal portion to escape to the outside of the packaging bag.

[0134] The contents to be contained in the packaging bag include, for example, liquids, solids, powders, and gels. The contents may be food or beverages, or non-food or beverages such as chemicals, cosmetics, medicines, metal parts, and electronic parts. After the contents are contained in the packaging bag, the opening of the packaging bag can be heat-sealed to seal the packaging bag. The contents may be heat-sterilized foods (heat-sterilized foods such as retort foods, boiled foods, and pasteurized beverages). The packaging bag of the present disclosure may be a pouch that contains heat-sterilized foods.

[0135] As specific examples of packaging bags, a small bag and a standing pouch will be described below. A sachet is a small packaging bag used to hold contents of, for example, 1 g to 200 g. Contents that can be held in a sachet include, for example, sauces, soy sauce, dressings, ketchup, syrups, cooking alcohol, and other liquid or viscous seasonings; liquid soups, powdered soups, fruit juices, spices, pet food, liquid beverages, jelly-like beverages, instant foods, and other foods and beverages; and non-food items such as chemicals, cosmetics, pharmaceuticals, metal parts, and electronic parts.

[0136] The stand-up pouch is used to store contents of, for example, 50 g to 2000 g. Examples of contents that can be stored in the stand-up pouch include shampoo, rinse, conditioner, hand soap, body soap, air freshener, deodorant, insect repellent, detergent, dressing, edible oil, mayonnaise, other liquid or viscous seasonings, liquid beverages, jelly-like beverages, instant foods, other foods and beverages, pet foods, creams, metal parts, and electronic parts.

[0137] In one embodiment, the contents of the packaging bag is pet food.

[0138] In one embodiment, the packaging bag of the present disclosure is suitable as a heat sterilization pouch or a microwave compatible packaging bag because the deterioration of the gas barrier property can be suppressed even when the packaging bag is subjected to heat treatment. The packaging bag of the present disclosure is also suitable as a boil or retort pouch for microwave ovens. Here, the microwave compatible packaging bag means a packaging bag that can be heated using a microwave oven.

[0139] Examples of heat sterilization pouches include pouches that have been retorted (hereinafter also referred to as "retort pouches"), pouches that have been boiled (hereinafter also referred to as "boiled pouches"), and pouches that have been pasteurized (hereinafter "pasteurization pouches"). A retort pouch is a packaging bag that has been filled with contents such as food or drink and sealed, and then heat sterilized (retort treatment) with water or steam at a temperature exceeding 100°C under pressure. A boiled pouch or pasteurization pouch is a packaging bag that has been filled with contents such as food or drink and sealed, and then boiled at a temperature of 100°C or less.

[0140] In one embodiment, the packaging bag of the present disclosure is a retort pouch. There are various conditions for the retort treatment, but any pouch that has undergone general retort treatment is included in the retort pouch. Among the retort treatments, for example, a treatment temperature of 105°C or higher and 115°C or lower may be called semi-retort treatment, a treatment temperature of more than 115°C and 121°C or lower may be called retort treatment, and a treatment temperature of more than 121°C and 140°C or lower may be called high retort treatment. The retort treatment time is, for example, from 5 minutes to 60 minutes, and preferably from 15 minutes to 40 minutes.

[0141] In one embodiment, the packaging bag of the present disclosure is a retort pouch. The oxygen permeability (unit: cc / m 2 In one embodiment, the oxygen permeability (day atm) is preferably 2.0 or less, more preferably 1.5 or less, further preferably 1.3 or less, and particularly preferably 1.0 or less. The oxygen permeability is measured in accordance with JIS K7126-2:2006 at a temperature of 23°C and a relative humidity of 90%. The lower limit of the oxygen permeability is preferably as low as possible, but may be, for example, 0.1.

[0142] 5 shows a packaging bag 50 obtained by bonding two laminates together. The shaded areas indicate the heat-sealed areas. The packaging bag 50 may have an easy-to-open part 51. Examples of the easy-to-open part 51 include a notch part 52 that serves as a starting point for tearing, and a half-cut line 53 formed by laser processing or a cutter as a path for tearing.

[0143] FIG. 6 shows a simplified example of the configuration of a standing pouch. The shaded areas indicate the heat-sealed areas. In one embodiment, the standing pouch 60 comprises a body portion (side sheets) 61 and a bottom portion (bottom sheet) 62. The side sheets 61 and the bottom sheet 62 may be made of the same material or different materials. The bottom sheet 62 retains the shape of the side sheets 61, thereby imparting self-supporting properties to the pouch, and the pouch can be made into a standing pouch. A storage space for storing contents is formed within the area surrounded by the side sheets 61 and the bottom sheet 62.

[0144] The standing pouch 60 may include a steam release mechanism 63. The steam release mechanism 63 includes a steam release seal portion 63a protruding from the side seal portion toward the inside of the packaging bag, and a non-sealed portion 63b isolated from the content storage portion by the steam release seal portion 63a. The non-sealed portion 63b communicates with the outside of the packaging bag.

[0145] In the stand-up pouch, only the body portion may be made of the laminate of the present disclosure, only the bottom portion may be made of the laminate, or both the body portion and the bottom portion may be made of the laminate.

[0146] In one embodiment, the side sheet can be formed by making a bag so that the sealant layer of the laminate of the present disclosure is the innermost layer. In one embodiment, the side sheet can be formed by preparing two sheets of the laminate of the present disclosure, overlapping them so that the sealant layers face each other, and heat-sealing the side edges on both sides to make a bag.

[0147] In another embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, inserting two laminates folded in a V-shape with the sealant layers facing outward between the laminates at the side edges on both sides of the overlapped laminates, and heat sealing them. According to this production method, a standing pouch having a body with side gussets can be obtained.

[0148] In one embodiment, the bottom sheet can be formed by inserting the laminate between the lower parts of the side sheets that have been made into a bag, and heat sealing the laminate. More specifically, the bottom sheet can be formed by inserting the laminate folded into a V shape with the sealant layer facing outward between the lower parts of the side sheets that have been made into a bag, and heat sealing the laminate.

[0149] In one embodiment, two laminates are prepared, and these are stacked with the sealant layers facing each other. Next, another laminate is folded in a V shape with the sealant layer facing outward, and this is sandwiched under the laminates that have been stacked, and heat sealed to form a bottom. Next, two sides adjacent to the bottom are heat sealed to form a body. In this manner, a standing pouch of one embodiment can be formed.

[0150] (Laminate) "Indentation hardness of coating layer" The laminate of the present disclosure has an indentation hardness of 0.9 GPa or more and 1.7 GPa or less, measured by a nanoindentation method from the coating layer of the cross section of the laminate after the above-mentioned heat sterilization treatment and after the production of a packaging bag as a packaging material. When the indentation hardness is in the above range, the gas barrier property of the laminate of the present disclosure can be suppressed from deteriorating after the retort treatment.

[0151] The indentation hardness of the coating layer is preferably 1.0 GPa or more, more preferably 1.1 GPa or more, and is preferably 1.6 GPa or less, more preferably 1.5 GPa or less. Specifically, a more preferred range is 1.1 GPa or more and 1.5 GPa or less.

[0152] The indentation hardness of the coating layer is calculated by the following formula (1). Indentation hardness = Pmax / A (1)

[0153] Where: Pmax: Maximum load (unit: μN) A: Contact projection area at maximum depth (unit: μm 2 ) It is.

[0154] The indentation hardness of the coating layer of the laminate after heat sterilization is measured by embedding the laminate after heat sterilization in epoxy resin or the like, and processing it with a microtome to expose the cross section of the coating layer. This allows measurement by nanoindentation from the "cross section" of the coating layer of the laminate. According to this method, the indentation hardness of the coating layer can be measured without peeling the laminate to expose the coating layer. The cross section is obtained by cutting in the thickness direction perpendicular to the main surface of the film. The cross section can be prepared by preparing a block in which the film is embedded in an embedding resin, and cutting the block using a commercially available rotary microtome under room temperature (23°C) environment. Finishing can be performed with a diamond knife.

[0155] The indentation hardness of the cross section of the coating layer is measured by the nanoindentation method. First, the indenter is placed on the cross section of the coating layer, and the indenter is pressed from the cross section to a load of 15 μN over 10 seconds, and the indenter is held in that state for 5 seconds. The indenter is pressed into the vicinity of the center in the thickness direction of the coating layer among the exposed cross sections of the coating layer. Then, the load is removed over 10 seconds. This provides the maximum load Pmax, the contact projected area A at the maximum depth, and the load-displacement curve. The measurement is performed under an environment of 50% relative humidity and 23°C unless otherwise specified. The measurement is performed at five or more points on the same cross section, and the indentation hardness is described as the arithmetic average value of the values ​​of the five points measured with good reproducibility. Further detailed measurement conditions are those described in the examples.

[0156] The indentation hardness of the coating layer can be adjusted, for example, by the composition of the coating layer or the drying temperature during the formation of the coating layer.

[0157] "Composite elastic modulus of coating layer" The laminate of the present disclosure has a composite elastic modulus measured by nanoindentation from the coating layer of the cross section of the laminate after the laminate is made into a packaging bag as a packaging material and after the above-mentioned heat sterilization treatment, of preferably 5.0 GPa or more, more preferably 6.0 GPa or more, and preferably 9.5 GPa or less, more preferably 9.0 GPa or less. Specifically, the preferred range is 5.0 GPa or more and 9.5 GPa or less, and the more preferred range is 6.0 GPa or more and 9.0 GPa or less.

[0158] The composite elastic modulus of the coating layer is calculated by the following formula (2).

number

[0159] Where: Pmax: Maximum load (unit: μN) A: Contact projection area at maximum depth (unit: μm 2 ) S: Contact stiffness It is.

[0160] The composite modulus of the coating layer of the laminate after heat sterilization is measured by embedding the laminate after heat sterilization in epoxy resin or the like, and processing it with a microtome to expose the cross section of the coating layer. This allows measurement by nanoindentation from the "cross section" of the coating layer of the laminate. According to this method, the composite modulus of the coating layer can be measured without peeling the laminate to expose the coating layer. The cross section is obtained by cutting in the thickness direction perpendicular to the main surface of the film. The cross section can be prepared by preparing a block in which the film is embedded in an embedding resin, and cutting the block using a commercially available rotary microtome under room temperature (23°C) environment. Finishing can be performed with a diamond knife.

[0161] The composite modulus of the cross section of the coating layer is measured by the nanoindentation method. First, the indenter is placed on the cross section of the coating layer, and the indenter is pressed from the cross section to a load of 15 μN over 10 seconds, and the state is maintained for 5 seconds. The indenter is pressed into the vicinity of the center in the thickness direction of the coating layer among the exposed cross sections of the coating layer. Then, the load is removed over 10 seconds. This provides the maximum load Pmax, the contact projected area A at the maximum depth, and the load-displacement curve. The measurement is performed under an environment of 50% relative humidity and 23°C unless otherwise specified. The measurement is performed at five or more points on the same cross section, and the composite modulus is described as the arithmetic average value of the values ​​of the five points measured with good reproducibility. Further detailed measurement conditions are described in the examples.

[0162] The composite elastic modulus of the coating layer can be adjusted, for example, by the composition of the coating layer or the drying temperature during the formation of the coating layer.

[0163] "Elastic modulus of adhesive layer" In the laminate of the present disclosure, the elastic modulus measured by atomic force microscopy (AFM) on a cross section of the adhesive layer adjacent (or close to) the coating layer constituting the barrier film is 100.0 MPa or less, preferably 50.0 MPa or less, more preferably 40.0 MPa or less, even more preferably 35.0 MPa or less, and particularly preferably 30.0 MPa or less.

[0164] Specifically, when the laminate of the present disclosure has a two-layer structure in which a barrier film, an adhesive layer, and a sealant layer are laminated in this order, and the barrier film is arranged so that the coating layer that constitutes the barrier film faces the adhesive layer, the above-mentioned elastic modulus of the adhesive layer adjacent to the coating layer is 100.0 MPa or less.

[0165] Furthermore, when the laminate of the present disclosure has a three-layer structure in which a first substrate, a first adhesive layer, a barrier film including a second substrate, a second adhesive layer, and a sealant layer are laminated in this order, and the barrier film is arranged so that the coating layer constituting the barrier film faces the second adhesive layer, the above-mentioned elastic modulus of the second adhesive layer adjacent to the coating layer is 100.0 MPa or less.

[0166] Furthermore, when the laminate of the present disclosure has a three-layer structure in which a first substrate, a first adhesive layer, a barrier film including a second substrate, a second adhesive layer, and a sealant layer are laminated in this order, and the barrier film is arranged so that the coating layer constituting the barrier film faces the first adhesive layer, the above-mentioned elastic modulus of the first adhesive layer adjacent to the coating layer is 100.0 MPa or less.

[0167] Furthermore, when the laminate of the present disclosure has a three-layer structure in which a first barrier film, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer are laminated in this order, and the barrier film is arranged so that the coating layer constituting the barrier film faces the first adhesive layer, the above-mentioned elastic modulus of the first adhesive layer adjacent to the coating layer is 100.0 MPa or less.

[0168] According to the laminate of the present disclosure, by using an adhesive layer having an elastic modulus of 100.0 MPa or less as the adhesive layer in contact with the coating layer having an indentation hardness of 0.9 GPa or more and 1.7 GPa or less, damage to the coating layer during heat sterilization treatment such as retort treatment can be reduced, thereby suppressing deterioration of gas barrier properties after heat sterilization treatment such as retort treatment.

[0169] Furthermore, according to the laminate of the present disclosure, by using an adhesive layer having an elastic modulus of 35.0 MPa or less, damage to the coating layer during heat sterilization such as retort treatment can be further reduced, and thus deterioration of the gas barrier property after heat sterilization such as retort treatment can be further suppressed.

[0170] Furthermore, according to the laminate of the present disclosure, by using a coating layer having a nanoindentation hardness of 1.1 GPa or more and 1.5 GPa or less and a composite elastic modulus of 6.0 GPa or more and 9.0 GPa or less, damage to the coating layer during heat sterilization treatment such as retort treatment can be further reduced, and thus deterioration of gas barrier properties after heat sterilization treatment such as retort treatment can be further suppressed.

[0171] According to the laminate of the present disclosure, the oxygen transmission rate of the laminate after retort treatment at 23°C and 90% RH according to JIS K 7126-2 is 2.0 cc / m 2 ·day·atm or less. Furthermore, according to a preferred embodiment, an oxygen permeability of 1.0 cc / m 2 ·day·atm or less can be achieved.

[0172] In addition, according to the laminate of the present disclosure, the oxygen permeability of the coating layer after high retort treatment at 23°C and 90% RH in accordance with JIS K 7126-2 is 3.0 cc / m 2 ·day·atm or less, and further, according to a preferred embodiment, an oxygen permeability of 2.0 cc / m 2 ·day·atm or less can be achieved.

[0173] <Mechanism of action> As described above, the laminate of the present disclosure comprises a substrate (barrier substrate) having a stretched polypropylene substrate, an inorganic oxide layer provided on one side of the substrate, and a barrier film including a coating layer provided on the inorganic oxide layer, and the indentation hardness of the coating layer constituting the barrier film is 0.9 GPa or more, and the above-mentioned elastic modulus of the adhesive layer adjacent (or close to) the coating layer is 100.0 MPa or less. In this way, by providing a soft adhesive layer adjacent to the hard coating layer, a buffer effect is obtained by the soft adhesive layer during heat sterilization treatment such as retort treatment, so that damage to the coating layer can be reduced. As a result, according to the laminate of the present disclosure, even after heat sterilization treatment such as retort treatment, the barrier functions of the coating layer and the inorganic oxide layer function without being impaired, so that the deterioration of gas barrier properties can be suppressed.

[0174] The present disclosure relates to, for example, the following [1] to

[11] . [1] A barrier film including a substrate, an inorganic oxide layer, and a coating layer having a barrier property laminated in this order; An adhesive layer; A laminate comprising at least a sealant layer, The substrate comprises a stretched substrate containing polypropylene as a main component, The sealant layer contains polypropylene as a main component, The barrier film is disposed such that the covering layer faces the adhesive layer, The elastic modulus of the cross section of the adhesive layer in the laminate is measured using an atomic force microscope (AFM) of 100.0 MPa or less; The laminate has an indentation hardness of 0.9 GPa or more and 1.7 GPa or less, as measured by a nanoindentation method from a cross section of the coating layer in the laminate. [2] The laminate according to [1], wherein the elastic modulus is 35.0 MPa or less. [3] The laminate according to [1] or [2], wherein the composite elastic modulus of the coating layer in the laminate, as measured by a nanoindentation method from a cross section thereof, is 5.0 GPa or more and 9.5 GPa or less. [4] The laminate according to any one of [1] to [3], wherein the laminate comprises the barrier film, the adhesive layer, and the sealant layer in this order in a thickness direction. [5] The laminate includes a first substrate, a second substrate, the adhesive layer, and the sealant layer in this order in a thickness direction, The first substrate and the second substrate comprise a stretched substrate containing polypropylene as a main component, The laminate according to any one of [1] to [3], wherein the barrier film includes the second substrate as the substrate. [6] The laminate includes a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and the sealant layer in this order in a thickness direction; The first substrate and the second substrate comprise a stretched substrate containing polypropylene as a main component, The barrier film includes the first substrate or the second substrate as the substrate, the barrier film is disposed such that the covering layer faces the first adhesive layer; The laminate according to any one of [1] to [3], wherein the elastic modulus of a cross section of the first adhesive layer in the laminate, as measured with an atomic force microscope (AFM), is 100.0 MPa or less. [7] The laminate described in [6], wherein the barrier film includes the second substrate as the substrate. [8] The laminate according to any one of [1] to [7], wherein the content of polypropylene in the total amount of resin materials contained in the laminate is 80 mass % or more. [9] The laminate according to [8], which is a packaging material.

[10] A packaging bag comprising the laminate described in [9].

[11] The packaging bag according to

[10] , which is a pouch for containing heat-sterilized food. EXAMPLES

[0175] The laminate and packaging bag of the present disclosure will be specifically described below based on specific examples.

[0176] [Barrier film] (Barrier film A) A hydroxyl-containing acrylic resin (number average molecular weight: 25,000, glass transition temperature: 99°C, hydroxyl value: 80mgKOH / g) was diluted with a mixed solvent of methyl ethyl ketone and ethyl acetate (mixing ratio 1:1) until the solid content concentration was 10% by mass to prepare a base material. An ethyl acetate solution containing tolylene diisocyanate (solid content 75% by mass) was added to the base material as a curing agent to obtain a solution for forming a surface coating layer. The amount of the curing agent used was 10 parts by mass relative to 100 parts by mass of the base material.

[0177] A biaxially stretched polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) having a thickness of 20 μm and having one side subjected to corona treatment was prepared. The above-mentioned solution for forming a surface coating layer was applied to the corona-treated surface of the film and dried to form a surface coating layer having a thickness of 0.2 μm. In this manner, a resin substrate was obtained.

[0178] Using a real low-temperature plasma chemical vapor deposition apparatus, a 10 nm thick aluminum oxide (AlOx) vapor deposition film (inorganic oxide layer) was formed on the surface coating layer of the resin substrate by roll-to-roll motion while applying tension to the resin substrate (PVD method).

[0179] Polyvinyl alcohol (PVA) with a saponification degree of 99% or more and a polymerization degree of 2400 was mixed with water and isopropyl alcohol in a ratio of 95 / 5 to obtain solution A with a solid content of 4%. Water, isopropyl alcohol and 1N hydrochloric acid were mixed in a ratio of 65 / 34 / 1 to obtain a prepared solution B. Tetraethoxysilane was used as a metal alkoxide to prepare solution C. A liquid obtained by mixing solutions B and C with an adjusted ratio was used as solution D, and a liquid obtained by mixing solutions A and D with an adjusted ratio was used as barrier coating agent (VC) 1. The solid content of barrier coating agent 1 after mixing was 7%, and the ratio of solutions B and C, and the ratio of solutions A and D were adjusted so that the mass of tetraethoxysilane converted to SiO2 was 2.25 relative to the solid content of PVA.

[0180] The above prepared barrier coating agent 1 was applied onto the above vapor deposition film (inorganic oxide layer) by a direct gravure method, and then dried at 100° C. to form a barrier coating layer (coating layer) with a dry thickness of 300 nm.

[0181] After that, the film was aged at 40°C for 7 days to obtain barrier film A having, in that order, a 20 μm-thick biaxially oriented polyethylene film, a 0.2 μm-thick surface coating layer, a 10 nm-thick aluminum oxide vapor deposition film, and a 300 nm-thick barrier coating layer.

[0182] (Barrier film B) Barrier film B was obtained in the same manner as barrier film A above, except that barrier coating agent 2 was used as the barrier coating agent for forming the barrier coating layer (coating layer), which was a mixture of solution B and solution C, and solution A and solution D, and the ratio of solution B to solution C and solution A to solution D was adjusted so that the solid content was 7% and the mass of tetraethoxysilane in terms of SiO2 was 2.75 relative to the solid content of PVA.

[0183] (Barrier film C) When forming the inorganic oxide layer, instead of aluminum oxide by the PVD method, silica (SiOx) was formed to a thickness of 30 nm by the CVD method, and as a barrier coating agent for forming the barrier coat layer (coating layer), when mixing solutions B and C, 5% glycidoxypropyltrimethoxysilane was added relative to the weight of tetraethoxysilane, and the ratio of solutions B and C and the ratio of solutions A and D were adjusted so that the solid content was 7% and the mass of tetraethoxysilane converted to SiO2 relative to the solid content of PVA was 3.5, to obtain barrier film C in the same manner as barrier film A above, except that barrier film C was used.

[0184] (Barrier film D) Barrier film D was obtained in the same manner as barrier film A above, except that when solutions B and C were mixed, 5% glycidoxypropyltrimethoxysilane was added relative to the weight of tetraethoxysilane to form a barrier coating layer (coating layer), and barrier coating agent 4 was used, which was prepared by adjusting the ratios of solutions B and C and solutions A and D so that the solid content was 7% and the SiO2 equivalent mass of tetraethoxysilane was 1.5 relative to the solid content of PVA.

[0185] (Barrier Film E) When forming the inorganic oxide layer, instead of aluminum oxide by the PVD method, silica (SiOx) was formed to a thickness of 30 nm by the CVD method, and as a barrier coating agent for forming the barrier coat layer (coating layer), when mixing solutions B and C, 5% glycidoxypropyltrimethoxysilane was added relative to the weight of tetraethoxysilane, and as a coating layer, barrier coating agent 5 was used, which was prepared by adjusting the ratio of solutions B and C and the ratio of solutions A and D so that the solid content was 7% and the mass of tetraethoxysilane converted to SiO2 relative to the solid content of PVA was 4.0. A barrier film E was obtained in the same manner as the barrier film A.

[0186] [glue] The following two-component curing adhesive was used, which is composed of a base agent and a curing agent. Adhesive A Base: Polyester polymer (Mw: 22,000) Hardener: A mixture of hexamethylene diisocyanate (HDI) biuret and HDI nurate. Molar ratio of base agent to hardener (NCO / OH): 2 Adhesive A contains ethyl acetate as a solvent. Adhesive B Base: Polyester polyurethane polymer (Mw: 30,000) Hardener: A mixture of isophorone diisocyanate (IPDI) trimer and xylylene diisocyanate (XDI) trimethylolpropane (TMP) adduct. Molar ratio of base agent to hardener (NCO / OH): 4 Adhesive B contains ethyl acetate as a solvent. Adhesive C Base: Polyester polymer (Mw: 4,000) Hardener: Mixture of HDI and XDI Molar ratio of base agent to hardener (NCO / OH): 2 Adhesive C is substantially free of solvent. Adhesive D Base: Polyester polymer (Mw: 3,500) Hardener: Mixture of IPDI and HDI (higher HDI content than IPDI) Molar ratio of base agent to hardener (NCO / OH): 2 Adhesive D is substantially free of solvent.

[0187] [Example 1] As the first substrate, a biaxially stretched polypropylene film having a thickness of 20 μm and having one surface corona-treated (manufactured by Toyobo Co., Ltd., P2171, hereinafter also referred to as "BOPP film") was prepared. The above-mentioned barrier film A was prepared. As the sealant layer, a non-stretched polypropylene film having a thickness of 60 μm and having one surface corona-treated (manufactured by Okamoto Co., Ltd., ET-20, hereinafter also referred to as "CPP film") was prepared.

[0188] Adhesive A was applied onto the corona-treated surface of the first substrate by gravure roll coating, and the adhesive layer surface formed on the first substrate was bonded to the covering layer (barrier coat layer) surface of the barrier film, followed by aging for 72 hours at 40° C. Furthermore, a corona treatment was performed on the non-barrier coat layer surface of the barrier film, and adhesive A was applied by gravure roll coating, and the adhesive layer surface formed on the barrier film was bonded to the corona-treated surface of the CPP film, followed by aging for 72 hours at 40° C. The thickness of each adhesive layer formed was 3.15 μm.

[0189] In this manner, the laminate of Example 1 was obtained. The obtained laminate had a layer structure of BOPP film (20 μm) / adhesive layer (3.15 μm) / barrier film A (20.51 μm) / adhesive layer (3.15 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0190] [Example 2] A laminate of Example 2 was obtained in the same manner as in Example 1, except that Barrier Film B was used. The resulting laminate had the following layer structure: BOPP film (20 μm) / adhesive layer (3.15 μm) / barrier film B (20.51 μm) / adhesive layer (3.15 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0191] [Example 3] A laminate of Example 3 was obtained in the same manner as in Example 1, except that barrier film C was used and adhesive B was used to bond the corona-treated surface of the first substrate to the coated layer side of barrier film C, and to bond the non-coated layer surface of barrier film C to the corona-treated surface of the CPP film. The resulting laminate had the following layer structure: BOPP film (20 μm) / adhesive layer (3.15 μm) / barrier film C (20.51 μm) / adhesive layer (3.15 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0192] [Example 4] A laminate of Example 4 was obtained in the same manner as in Example 3, except that adhesive C was used and the thickness of each adhesive layer was 1.35 μm. The resulting laminate had the following layer structure: BOPP film (20 μm) / adhesive layer (1.35 μm) / barrier film C (20.51 μm) / adhesive layer (1.35 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0193] [Example 5] A laminate of Example 5 was obtained in the same manner as in Example 3, except that adhesive D was used and the thickness of each adhesive layer was 1.35 μm. The resulting laminate had the following layer structure: BOPP film (20 μm) / adhesive layer (1.35 μm) / barrier film C (20.51 μm) / adhesive layer (1.35 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0194] [Comparative Example 1] A laminate of Comparative Example 1 was obtained in the same manner as in Example 1, except that Barrier Film D was used. The resulting laminate had the following layer structure: BOPP film (20 μm) / adhesive layer (3.15 μm) / barrier film D (20.51 μm) / adhesive layer (3.15 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0195] [Comparative Example 2] A laminate of Comparative Example 2 was obtained in the same manner as in Example 1, except that Barrier Film E was used. The resulting laminate had the following layer structure: BOPP film (20 μm) / adhesive layer (3.15 μm) / barrier film E (20.51 μm) / adhesive layer (3.15 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0196] [Example 6] The covering layer (barrier coat layer) surface of the above barrier film B was subjected to a corona treatment, and adhesive A was applied by gravure roll coating, and the adhesive layer surface formed on barrier film B and the corona-treated surface of the CPP film were bonded together, followed by aging for 72 hours at 40° C. The thickness of each adhesive layer formed was 3.15 μm.

[0197] In this manner, a laminate of Example 6 was obtained. The obtained laminate had a layer structure of barrier film B (20.51 μm) / adhesive layer (3.15 μm) / CPP film (60 μm). The numbers in parentheses indicate the thickness of each layer.

[0198] [Measurement of elastic modulus] For the laminates obtained in the above Examples 1 to 6 and Comparative Examples 1 and 2, force curve measurements were performed using an atomic force microscope (AFM), and the elastic modulus of the cross section of the adhesive layer was determined from the obtained force curves. The specific measurement procedure is as follows. The laminate obtained in the above example was embedded in an embedding resin to prepare a block, and the block was cut at room temperature (25°C) using a commercially available rotary microtome to prepare a cross section of the laminate. The cross section was obtained by cutting the laminate in the thickness direction perpendicular to the main surface. Finishing was performed with a diamond knife. Using an atomic force microscope (AFM), mapping measurements were performed on the above cross section at a 2.5 μm square including the cross section of the adhesive layer. For the cross section of the adhesive layer, 20 force curves that provided an appropriate force curve shape were selected. The elastic modulus was calculated by fitting each force curve according to the JKR (Johnson-Kendall-Roberts) theory, and the arithmetic mean value (hereinafter also referred to as the "first arithmetic mean value") of the obtained 20 elastic moduli was calculated. Here, the selected part of the force curve was the vicinity of the center in the thickness direction of the adhesive layer among the parts where the cross section of the adhesive layer was exposed. From the above 20 elastic moduli, three elastic moduli close to the first arithmetic mean value were selected, and the arithmetic mean value (hereinafter also referred to as the "second arithmetic mean value") of the three elastic moduli was calculated. The obtained second arithmetic mean value was taken as the elastic modulus of the cross section of the adhesive layer. The results are shown in Tables 1 and 2.

[0199] The details of the AFM measurement conditions are shown below. (AFM elastic modulus measurement) Device name: SPM-9700HT (Shimadzu Corporation) Measurement atmosphere: At room temperature (25℃) Measurement mode: Contact mode Calibration method: Measure the cantilever sensitivity using glass ·Number of measurement points: 64 x 64 points (4096 points in total) Field of view: 2.5μm square Cantilever type: CONTR (manufactured by Nanoworld) Cantilever tip radius: <8nm Cantilever spring constant: 0.2N / m Contact pressure: 0.5V Scan speed: 3Hz Elastic modulus calculation model: JKR (Johnson-Kendall-Roberts) theory Poisson's ratio of sample: 0.4 Analysis software: Nano 3D Mapping (Shimadzu Corporation)

[0200] [Measurement of indentation hardness and composite elastic modulus (after retort treatment)] Two sheets of the laminate obtained in the above Examples 1 to 6 and Comparative Examples 1 to 2 were prepared, and these were overlapped with the faces of the sealant layer (CPP film) facing each other, and three sides were heat-sealed under the conditions of 180°C, 0.1 MPa, and 1 second to prepare a flat pouch of B5 size (182 mm x 257 mm). 100 mL of water was filled into the obtained pouch from the opening, and the opening was heat-sealed under the above conditions to seal the pouch. The obtained pouch was subjected to retort sterilization under retort conditions of 121°C, 30 minutes, and 0.21 MPa, or retort sterilization under high retort conditions of 135°C, 30 minutes, and 0.35 MPa. After each retort sterilization, the laminate was cut out from the pouch to obtain a test piece. Using this test piece, the indentation hardness (GPa) and composite modulus (GPa) of the coating layer were measured by the following method. The results are shown in Tables 1 and 2.

[0201] Measurement device: HYSITRON TI-950 Tripoint Tender Measurement location: From the cross-section side of the coating layer Measurement mode: Indentation Indenter: cubecorner indenter, TI-0037 Measurement Profile 0~10sec: 0→15μN 10~15sec: 15μN 15~25sec: 15→0μN

[0202] [Gas barrier evaluation (after retort processing)] Two sheets of the laminate obtained in the above Examples 1 to 6 and Comparative Examples 1 to 2 were prepared, and these were overlapped with the faces of the sealant layers (CPP film) facing each other, and three sides were heat-sealed under conditions of 180°C, 0.1 MPa, and 1 second to prepare a flat pouch of B5 size (182 mm x 257 mm). 100 mL of water was filled into the obtained pouch from the opening, and the opening was heat-sealed under the above conditions to seal the pouch. The obtained pouch was subjected to retort sterilization under retort conditions of 121°C, 30 minutes, and 0.21 MPa, or retort sterilization under high retort conditions of 135°C, 30 minutes, and 0.35 MPa. After each retort sterilization, the laminate was cut out from the pouch to obtain a test piece. Using this test piece, the oxygen permeability (cc / m2·day·atm) was measured by the following method. The results are shown in Tables 1 and 2.

[0203] Using an oxygen permeability measuring device (MOCON, OX-TRAN2 / 20), the test piece was set so that the first substrate side was the oxygen supply side, and the oxygen permeability was measured in an environment of temperature 23°C and relative humidity 90% RH in accordance with JIS K7126-2: 2006. The results are shown in Tables 1 and 2.

[0204] [Table 1]

[0205] [Table 2] [Explanation of symbols]

[0206] 1: laminate, 11: first substrate, 20: barrier film, 21: second substrate (substrate), 22: surface coating layer, 23: inorganic oxide layer, 24: coating layer, 30: sealant layer, 40: adhesive layer, 40A: first adhesive layer, 40B: second adhesive layer 50: packaging bag, 51: easy-to-open portion, 52: notch portion, 53: half-cut line, 60: standing pouch, 61: body (side sheet), 62: bottom (bottom sheet), 63: steam release mechanism, 63a: steam release seal part, 63b: non-seal part, 100: test piece, 110: gripping tool

Claims

1. a barrier film in which a substrate, an inorganic oxide layer, and a coating layer having a barrier property are laminated in this order; An adhesive layer; A laminate comprising at least a sealant layer, The substrate comprises a stretched substrate containing polypropylene as a main component, The sealant layer contains polypropylene as a main component, The barrier film is disposed such that the covering layer faces the adhesive layer, The elastic modulus of the cross section of the adhesive layer in the laminate, as measured using an atomic force microscope (AFM), is 100.0 MPa or less; The laminate, wherein an indentation hardness of the coating layer in the laminate, as measured by a nanoindentation method from a cross section thereof, is 0.9 GPa or more and 1.7 GPa or less.

2. The laminate according to claim 1 , wherein the elastic modulus is 35.0 MPa or less.

3. 2. The laminate according to claim 1, wherein the composite elastic modulus of the coating layer in the laminate, as measured by a nanoindentation method from a cross section thereof, is 5.0 GPa or more and 9.5 GPa or less.

4. The laminate according to claim 1 , comprising the barrier film, the adhesive layer, and the sealant layer in this order in a thickness direction.

5. the laminate includes a first substrate, a second substrate, the adhesive layer, and the sealant layer in this order in a thickness direction; The first substrate and the second substrate each include a stretched substrate containing polypropylene as a main component, The laminate according to claim 1 , wherein the barrier film includes the second substrate as the substrate.

6. the laminate includes a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and the sealant layer in this order in a thickness direction; The first substrate and the second substrate each include a stretched substrate containing polypropylene as a main component, The barrier film includes the first substrate or the second substrate as the substrate, the barrier film is disposed such that the covering layer faces the first adhesive layer; The laminate according to claim 1 , wherein the elastic modulus of a cross section of the first adhesive layer in the laminate, as measured with an atomic force microscope (AFM), is 100.0 MPa or less.

7. The laminate according to claim 6 , wherein the barrier film includes the second substrate as the substrate.

8. The laminate according to any one of claims 1 to 7, wherein a content ratio of polypropylene to a total amount of resin materials contained in the laminate is 80 mass% or more.

9. The laminate of claim 8 which is a packaging material.

10. A packaging bag comprising the laminate according to claim 9.

11. The packaging bag according to claim 10, which is a pouch for containing heat-sterilized food.

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