Sealant film for laminate, laminate, packaging container, and heat sterilization pouch

Abstract

Provided is a sealant film for a laminate excellent in impact resistance after retort treatment and suitable for a laminate made of monomaterial, polypropylene. There is provided a sealant film used for a laminate having a content ratio of polypropylene relative to the total amount of a resin material of 80 mass% or more, wherein the sealant film contains a polypropylene, a polyethylene, and an ethylene-propylene rubber, the content ratio of the polypropylene to the total amount of the sealant film is 40 mass% or more, and the sealant film has a complex elastic modulus measured by the nanoindentation method of 500-900 MPa inclusive.

Description

Sealant film for laminates, laminates, packaging containers, and heat sterilization pouches CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority based on Japanese Patent Application No. 2023-166474 filed in Japan on September 27, 2023, Japanese Patent Application No. 2023-167754 filed in Japan on September 28, 2023, and Japanese Patent Application No. 2023-186013 filed in Japan on October 30, 2023, the entire disclosures of which are incorporated herein by reference.

[0002] The present invention relates to a sealant film for laminates, a laminate, a packaging container, and a heat sterilization pouch.

[0003] Conventionally, packaging containers have been constructed from laminates using a base material such as a polyester film, which has excellent strength and heat resistance, or a nylon film, which has excellent impact resistance, and a sealant film such as a polyolefin film, which has excellent heat-sealing properties. However, with the growing demand for building a recycling-oriented society in recent years, there has been a demand for packaging containers with high recyclability. However, with conventional packaging containers constructed from different resin materials, it has been difficult to separate each resin material.

[0004] Therefore, from the viewpoint of using a single material (mono-material) that is easy to recycle, the use of a single material made of polypropylene has been studied (for example, Patent Document 1). Patent Document 1 discloses a laminate for use in packaging materials such as packaging containers, in which a stretched substrate containing polypropylene is used as the substrate instead of a polyester film or a nylon film, and is combined with a sealant film containing polypropylene. In this laminate, both the substrate and the sealant film are made of polypropylene, thereby improving recyclability.

[0005] Japanese Patent Application Laid-Open No. 2021-020391

[0006] When a laminate is used to make a packaging container such as a retort pouch, it is required that the laminate have drop impact resistance (impact resistance) that can withstand the impact when the pouch is dropped after retort treatment, and hand tearability (easy openability) that allows the laminate to be easily torn by hand after retort treatment. However, a laminate made of a single material such as polypropylene has sometimes been insufficient in impact resistance and openability after retort treatment.

[0007] One of the problems to be solved by the present disclosure is to provide a sealant film for laminates that has excellent impact resistance and openability after retort treatment and is suitable for laminates made of a single material such as polypropylene.

[0008] The sealant film for laminates of the present disclosure is a sealant film for use in a laminate in which the polypropylene content ratio relative to the total amount of resin material is 80% by mass or more, the sealant film containing polypropylene, polyethylene, and ethylene-propylene rubber, the polypropylene content ratio relative to the total amount of the sealant film being 40% by mass or more, and the sealant film having a composite elastic modulus of 500 MPa or more and 900 MPa or less as measured by a nanoindentation method.

[0009] According to the present disclosure, it is possible to provide a sealant film for laminates that has excellent impact resistance and openability after retort treatment and is suitable for laminates made of a single material such as polypropylene.

[0010] FIG. 1 is a cross-sectional view schematically illustrating one embodiment of a sealant film for laminates. FIG. 2 is a cross-sectional view schematically illustrating one embodiment of a sealant film for laminates. FIG. 3 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 4 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 5 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 6 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 7 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 8 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 9 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 10 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 11 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 12 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 13 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 14 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 15 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 16 is a cross-sectional view schematically illustrating one embodiment of a laminate. FIG. 17 is a cross-sectional view schematically illustrating one embodiment of a laminate. Fig. 18 is a schematic cross-sectional view showing one embodiment of a laminate. Fig. 19 is a schematic cross-sectional view showing one embodiment of a laminate. Fig. 20 is a schematic cross-sectional view showing one embodiment of a laminate. Fig. 21 is a front view showing one embodiment of a packaging container. Fig. 22 is a perspective view showing one embodiment of a packaging container. Fig. 23 shows the results of composition analysis of the sealant film of the example.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail. The present disclosure can be implemented in many different forms, and should not be construed as being limited to the description of the following exemplary embodiments. For clarity of explanation, the drawings may show the width, thickness, shape, etc. of each layer more schematically than in the embodiments, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each drawing, elements similar to those already described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0012] In the present disclosure, when multiple upper limit candidates and multiple lower limit candidates are listed for a certain parameter, the numerical range of the parameter may be constructed by combining any one upper limit candidate with any one lower limit candidate. Examples of the parameters include physical properties, component content ratios, and layer thicknesses. As an example, the following statement will be explained: "Parameter B is preferably A1 or greater, more preferably A2 or greater, and even more preferably A3 or greater. Parameter B is preferably A4 or less, more preferably A5 or less, and even more preferably A6 or less." In this example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, or A3 or greater and A6 or less.

[0013] In this specification, the term "main component" in 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.

[0014] In the following description, each of the components (for example, polypropylene, α-olefin, resin material, additive, adhesive resin, inorganic oxide, gas barrier resin, propylene-ethylene block copolymer, thermoplastic elastomer, and polyethylene) that appear may be used alone or in combination of two or more.

[0015] [Laminate sealant film] The laminate sealant film of the present disclosure contains polypropylene, polyethylene, and ethylene-propylene rubber in an amount of 40% by mass or more, based on the total amount of the sealant film. A laminate including such a laminate sealant film as a sealant layer has excellent drop impact resistance (impact resistance), which allows the pouch to withstand impact when dropped after retort treatment, and excellent hand-tearability (openability), which allows the pouch to be easily torn by hand after retort treatment.

[0016] The laminate sealant film may have a single-layer structure or a multi-layer structure. In one embodiment, the laminate sealant film of the present disclosure has a single-layer structure. In one embodiment, the laminate sealant film of the present disclosure has a two-layer structure consisting of a first layer that forms a sealing surface when used in a laminate, and a second layer that forms a core layer. In one embodiment, the laminate sealant film of the present disclosure has a three-layer structure consisting of a first layer that forms a sealing layer when used in a laminate, a second layer that forms a core layer, and a third layer that forms a surface layer located on the adhesive layer side. The laminate sealant film of the present disclosure is suitable for use in a laminate in which the polypropylene content relative to the total amount of resin materials is 80% by mass or more.

[0017] <Single-Layer Structure> The single-layer sealant film for laminates of the present disclosure (hereinafter also simply referred to as a "single-layer sealant film") contains polypropylene as a matrix resin component. The polypropylene contained in the single-layer sealant film may be any of homopolypropylene, random polypropylene, and block polypropylene, or a mixture of two or more selected from these. Biomass-derived polypropylene and / or recycled polypropylene may be used as the polypropylene. Homopolypropylene is a polymer composed only of propylene. Random polypropylene is a random polypropylene composed of propylene and an α-olefin other than propylene. Block polypropylene is a polypropylene having a polymer block composed of propylene and a polymer block composed of at least an α-olefin other than propylene. The polymer block composed of at least an α-olefin other than propylene may be a polymer block composed of propylene and an α-olefin other than propylene.

[0018] Examples of the α-olefin include α-olefins other than propylene having from 2 to 20 carbon atoms. Specific examples of the α-olefin include 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.

[0019] Among polypropylenes, random polypropylene is preferred from the viewpoint of heat sealability, homopolypropylene is preferred when the rigidity and heat resistance of the packaging container are important, and block polypropylene is preferred when the impact resistance of the packaging container is important. In the single-layer sealant film of the present disclosure, among these polypropylenes, homopolypropylene and block polypropylene are preferred from the viewpoint of impact resistance, and block polypropylene is more preferred.

[0020] From the viewpoint of heat sealing property, the density of polypropylene is, for example, 0.88 g / cm ３ 0.92g / cm or more ３ The density is measured in accordance with Method D (density gradient tube method, 23°C) of JIS K7112:1999. From the viewpoint of reducing the environmental load, biomass-derived polypropylene and / or recycled polypropylene may be used.

[0021] The monolayer sealant film of the present disclosure contains one or more polyethylenes as a dispersed component in a matrix resin component. The polyethylene can contribute to improving the impact resistance of the monolayer sealant film of the present disclosure. The monolayer sealant film of the present disclosure preferably has a sea-island structure in which polyethylene, a dispersed component (island component), is dispersed in polypropylene, a matrix resin component (sea component). This can improve the drop impact resistance of a laminate using the laminate sealant film of the present disclosure.

[0022] Examples of polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). Among these, low-density polyethylene and linear low-density polyethylene are preferred, and linear low-density polyethylene is more preferred. Linear low-density polyethylene has good dispersibility in polypropylene, which is the sea component, and can improve the impact resistance of a single-layer sealant film.

[0023] The density of the low density polyethylene is preferably 900 kg / m ３ More than 925kg / m ３ or less, more preferably 910 kg / m ３ More than 925kg / m ３ The density is measured in accordance with JIS K7112, particularly Method D (density gradient tube method, 23°C). Low-density polyethylene is obtained, for example, by polymerizing ethylene at a high pressure of 1000 atmospheres or more but less than 2000 atmospheres. Low-density polyethylene is also called high-pressure low-density polyethylene.

[0024] The density of the linear low density polyethylene is preferably 900 kg / m ３ More than 925kg / m ３ or less, more preferably 915 kg / m ３ More than 925kg / m ３ Linear low-density polyethylene can be obtained, for example, by copolymerizing ethylene and an α-olefin under medium or low pressure to introduce short-chain branches derived from the α-olefin. Examples of the α-olefin include α-olefins having from 4 to 10 carbon atoms, such as 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0025] As the polyethylene, from the viewpoint of reducing the environmental load, biomass-derived polyethylene or mechanically recycled or chemically recycled polyethylene may be used.

[0026] The melting point (Tm) of the polyethylene may be 100° C. or higher and 120° C. or lower, or 105° C. or higher and 120° C. or lower. The Tm of the polyethylene is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0027] The MFR of the polyethylene may be 1 g / 10 min or more and 20 g / 10 min or less, or 2 g / 10 min or more and 10 g / 10 min or less. The MFR of the polyethylene is measured in accordance with JIS K7210 at a temperature of 190°C and a load of 2.16 kg.

[0028] The single-layer sealant film of the present disclosure contains one or more ethylene-propylene rubbers (EPRs) as a dispersed component in a matrix resin component. By including an ethylene-propylene rubber as a dispersed component, the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure can be improved. The ethylene-propylene rubber is not particularly limited as long as it is an ethylene-propylene elastomer that can exist in a dispersed state in polypropylene. Examples of ethylene-propylene rubbers include block elastomers contained in block polypropylene, as described below.

[0029] The single-layer sealant film of the present disclosure may contain one or more elastomers as a component that improves the dispersion state of the dispersion component in the matrix resin component. By including an elastomer as a dispersion component, the dispersion state of the polyethylene and ethylene-propylene rubber, which are the dispersion components (island components), in the polypropylene, which is the matrix resin component (sea component), can be further improved. This can further improve the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure.

[0030] The elastomer is not particularly limited as long as it is a thermoplastic elastomer that can improve the dispersion state of polyethylene and ethylene-propylene rubber in polypropylene. Examples of the elastomer include a propylene-ethylene copolymer (propylene-ethylene elastomer) and an ethylene-α-olefin copolymer (ethylene-α-olefin elastomer).

[0031] The propylene-ethylene elastomer is a low-crystalline or amorphous copolymer elastomer, which is a random copolymer of 50% by mass or more and 90% by mass or less of propylene units as a main component and ethylene units as a copolymerization monomer. As the propylene-ethylene elastomer, an elastomer produced using a metallocene catalyst is preferred.

[0032] The ethylene-α-olefin elastomer is a low-crystalline or amorphous copolymer elastomer, which is a random copolymer of ethylene units as a main component in an amount of 50% by mass to 90% by mass and α-olefin units as a copolymerization monomer. As the ethylene-α-olefin elastomer, an elastomer produced using a metallocene catalyst is preferred.

[0033] Examples of the α-olefin include α-olefins having from 3 to 10 carbon atoms, specifically propylene, 1-butene, 1-hexene, and 1-octene. Examples of the ethylene-α-olefin elastomer include ethylene-propylene random copolymer, ethylene-1-butene random copolymer, and ethylene-1-octene random copolymer.

[0034] The MFR of the elastomer is preferably 0.1 g / 10 min or more and 10 g / 10 min or less, more preferably 0.2 g / 10 min or more and 5 g / 10 min or less. The MFR of the elastomer is measured in accordance with JIS K7210 at a temperature of 230°C or 190°C under a load of 2.16 kg.

[0035] The single-layer sealant film of the present disclosure may contain additives, such as crosslinkers, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0036] The thickness of the single-layer sealant film of the present disclosure is preferably 10 μm or more, more preferably 20 μm or more, and 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 in which the single-layer sealant film has a thickness equal to or greater than the lower limit has, for example, excellent seal strength. A laminate having a sealant layer in which the single-layer sealant film has a thickness 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 preferably 100 μm or less.

[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 using a diamond knife. The thickness of the substrate and each layer is the arithmetic average of the thicknesses measured at five locations by observing the cross-section using a scanning electron microscope (SEM, Hitachi, Ltd., SU8000).

[0038] 1 and 2 are schematic cross-sectional views showing one embodiment of a sealant film for laminates having a multilayer structure (hereinafter also simply referred to as a "multilayer sealant film"). The sealant film for laminates 30 shown in Fig. 1 has a two-layer structure, and includes a first layer 31 as a sealing layer and a second layer 32 as a core layer, in this order in the thickness direction. In this example, when the sealant film for laminates 30 is used in a laminate, the first layer 31 is located as the outermost layer of the laminate, and the second layer 32 is located on the inner layer side of the laminate.

[0039] 2 has a three-layer structure, including a first layer 31 as a sealing layer, a second layer 32 as a core layer, and a third layer 33 as a surface layer, in that order in the thickness direction. In this example, when the laminate sealant film 30 is used in a laminate, the first layer 31 is located as the outermost layer of the laminate and constitutes one of the surfaces of the laminate, and the third layer 33 is located on the inner layer side of the laminate.

[0040] (First Layer) The first layer preferably contains a first matrix resin component and a first dispersed component. In one embodiment, the first layer preferably has a so-called sea-island structure in which the first matrix resin component constitutes a sea component and the first dispersed component constitutes island components, with the island components dispersed in the sea component. The first layer constitutes the seal layer of the multilayer sealant film of the present disclosure.

[0041] The first matrix resin component contains polypropylene. The polypropylene may be any of homopolypropylene, random polypropylene, and block polypropylene, or a mixture of two or more selected from these. Among these, the polypropylene is preferably a propylene-ethylene random copolymer. A propylene-ethylene random copolymer (random polypropylene) is a random copolymer of 51% by mass or more and 90% by mass or less of propylene units as the main component and ethylene units as a copolymerization monomer, and has excellent transparency and impact strength compared to a propylene homopolymer (homopolypropylene), and a melting point 20 to 30°C lower.

[0042] The ethylene content of the random polypropylene is preferably 1.0% by mass or more, more preferably 2.0% by mass or more. The ethylene content of the random polypropylene is preferably 20% by mass or less, more preferably 10% by mass or less. When the ethylene content is equal to or greater than the lower limit, low-temperature sealability can be ensured when a laminate is formed using the multilayer sealant film of the present disclosure. When the ethylene content is equal to or less than the upper limit, excessive deterioration in heat resistance can be suppressed when a laminate is formed using the multilayer sealant film of the present disclosure. The ethylene content of the random polypropylene can be measured by the ethylene content quantification method (IR method) described on pages 412-413 of "Polymer Analysis Handbook (May 10, 2013, 3rd edition)" edited by the Polymer Analysis Discussion Group of the Japan Analytical Society.

[0043] The melting point of the random polypropylene is preferably 145°C or lower, more preferably 135°C or lower. When the melting point is below the upper limit, the low-temperature sealability of a laminate using the multilayer sealant film of the present disclosure is good, and bag-making suitability can be improved. The lower limit of the melting point of the random polypropylene is preferably 120°C or higher. When the melting point is above the lower limit, when a laminate using the multilayer sealant film of the present disclosure is used in a retort pouch or the like, heat seal strength can be ensured under semi-retort temperature conditions. In this specification, the melting point can be measured in accordance with JIS K7121:2012 (Method for measuring transition temperature of plastics). Specifically, the melting point can be determined by measuring a DSC curve at a heating rate of 10°C / min using differential scanning calorimetry (DSC) at a heating rate of 10°C / min.

[0044] The melt flow rate (MFR) of the random polypropylene is preferably 0.5 g / 10 min or more and 10 g / 10 min or less, more preferably 1 g / 10 min or more and 5 g / 10 min or less. The MFR of the propylene-ethylene random copolymer is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0045] Examples of methods for producing random polypropylene include polymerizing raw materials such as propylene and ethylene using a catalyst, such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0046] The first dispersed component preferably contains polyethylene. Polyethylene can contribute to improving the impact resistance of the multilayer sealant film of the present disclosure. The first layer preferably has a sea-island structure in which polyethylene, the first dispersed component (island component), is dispersed in random polypropylene, the first matrix resin component (sea component). This structure can improve the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0047] As described above, examples of polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). Among these, low-density polyethylene and linear low-density polyethylene are preferred, with linear low-density polyethylene being more preferred. Linear low-density polyethylene has good dispersibility in the random polypropylene, which is the sea component, and can enhance the impact resistance of the first layer. Therefore, peeling between the first and second layers of the laminate sealant film due to discontinuity in impact resistance can be suppressed.

[0048] The first dispersion component may further contain a first elastomer. By including the first dispersion component in the first elastomer, the dispersion state of the polyethylene, which is the first dispersion component (island component), in the random polypropylene, which is the first matrix resin component (sea component), can be further improved. This can further improve the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0049] The first elastomer is not particularly limited as long as it is a thermoplastic elastomer that can improve the dispersion state of polyethylene in the random polypropylene. As described above, examples of the first elastomer include a propylene-ethylene copolymer (propylene-ethylene elastomer) and an ethylene-α-olefin copolymer (ethylene-α-olefin elastomer).

[0050] The MFR of the first elastomer is preferably 0.1 g / 10 min or more and 10 g / 10 min or less, more preferably 0.2 g / 10 min or more and 5 g / 10 min or less, and is measured in accordance with JIS K7210 at a temperature of 230°C or 190°C under a load of 2.16 kg.

[0051] In the first layer, the content of the first matrix resin component is 30% by mass or more, preferably 35% by mass or more, and more preferably 40% by mass or more, based on the total amount of the first layer. In the first layer, the content of the first matrix resin component is 90% by mass or less, based on the total amount of the first layer. For example, the content of the first matrix resin component is 30% by mass or more and 90% by mass or less.

[0052] In the first layer, the content of the first dispersion component is preferably 10% by mass or more, more preferably 15% by mass or more, relative to the total amount of the first layer. In the first layer, the content of the first dispersion component is preferably 49% by mass or less, more preferably 30% by mass or less, relative to the total amount of the first layer. For example, in the first layer, the content of the first dispersion component is 10% by mass or more and 49% by mass or less, relative to the total amount of the first layer. When the content of the first dispersion component in the first layer is equal to or greater than the lower limit, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the content of the first dispersion component is equal to or less than the upper limit, the seal strength of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0053] The polyethylene content in the first layer is 1% by mass or more, preferably 2% by mass or more, relative to the total amount of the first layer. The polyethylene content in the first layer is, for example, 50% by mass or less, relative to the total amount of the first layer. For example, the polyethylene content in the first layer is 1% by mass or more and 50% by mass or less, relative to the total amount of the first layer. When the polyethylene content is equal to or greater than the lower limit, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the polyethylene content is equal to or less than the upper limit, the seal strength of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0054] In the first layer, the content of the first elastomer is preferably 4% by mass or more, more preferably 7% by mass or more, relative to the total amount of the first layer. In the first layer, the content of the first elastomer is, for example, 15% by mass or less, relative to the total amount of the first layer. For example, in the first layer, the content of the first elastomer is 4% by mass or more and 15% by mass or less, relative to the total amount of the first layer. When the content of the first elastomer is equal to or greater than the lower limit, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the content of the first elastomer is equal to or less than the upper limit, for example, the seal strength of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0055] In the first dispersion component, the ratio of the content of the first elastomer to the content of the polyethylene is preferably 0.5 or more and less than 1.0. When the ratio of the content of the first elastomer to the content of the polyethylene in the first dispersion component is within the above range, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0056] The thickness of the first layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 12 μm or more. The thickness of the first layer is preferably 20 μm or less, more preferably 15 μm or less. When the thickness is equal to or greater than the lower limit, for example, the low-temperature sealability and impact resistance of a packaging container including a laminate using the multilayer sealant film of the present disclosure can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0057] (Second Layer) The second layer preferably contains a second matrix resin component and a second dispersed component. In one embodiment, the second layer preferably has a so-called sea-island structure in which the second matrix resin component constitutes a sea component and the second dispersed component constitutes island components, with the island components dispersed in the sea component. The second layer constitutes the core layer of the multilayer sealant film of the present disclosure.

[0058] The second matrix resin component contains polypropylene. The polypropylene may be any of homopolypropylene, random polypropylene, and block polypropylene, or a mixture of two or more selected from these. Among these, the polypropylene is preferably block polypropylene (block PP). Block polypropylene (propylene block copolymer) is a copolymer containing at least a propylene homopolymer (homopolypropylene) and a block elastomer. An example of the block polypropylene is a propylene-ethylene block copolymer.

[0059] In one embodiment, the propylene-ethylene block copolymer includes a polymer portion (a) made of a propylene polymer and a polymer portion (b) made of polyethylene and an ethylene-propylene copolymer rubber component (ethylene-propylene rubber). In one embodiment, the propylene-ethylene block copolymer includes a sea component made of a propylene polymer and island component portions made of polyethylene and an ethylene-propylene copolymer rubber component. The polymer portion (a) and the sea component can contribute to improving the heat resistance, rigidity, blocking resistance, and seal strength of the propylene-ethylene block copolymer. The polymer portion (b) and the island component portions can contribute to improving the impact resistance of the propylene-ethylene block copolymer. Therefore, the mechanical properties of the second layer containing the propylene-ethylene block copolymer can be adjusted by adjusting the ratio of the polymer portion (a) to the polymer portion (b) and the ratio of the sea component to the island component portions.

[0060] In one embodiment, the propylene polymer of the polymer portion (a) is a propylene homopolymer having a melting point of 160° C. or higher. The propylene polymer may be a copolymer of propylene and a small amount (for example, 5 mol % or less) of an α-olefin, so long as it has a melting point of 160° C. or higher. Examples of α-olefins include ethylene, 1-butene, 1-hexene, and 1-octene.

[0061] In the polymer portion (b), for example, in the polyethylene and ethylene-propylene copolymer rubber components, the content of ethylene-derived structural units is preferably 10% by mass or more, more preferably 20% by mass or more. Furthermore, the content is preferably 50% by mass or less, more preferably 40% by mass or less. By being within the above preferred range, for example, drop impact resistance can be further improved. In the present disclosure, the content of the block polypropylene structural units can be measured, for example, by thermal gradient interaction chromatography (TGIC). In the polymer portion (b), the ethylene-propylene copolymer rubber component corresponds to the block elastomer.

[0062] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (a) consisting of a propylene polymer or the sea component is preferably higher than the mass ratio of the polymer portion (b) consisting of polyethylene and an ethylene-propylene copolymer rubber component or the island component.

[0063] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (a) consisting of a propylene polymer or the sea component is preferably 51 mass% or more, more preferably 60 mass% or more, and even more preferably 70 mass% or more. The upper limit of the mass ratio of the polymer portion (a) consisting of a propylene polymer or the sea component is, for example, 90 mass%.

[0064] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (b) consisting of polyethylene and ethylene-propylene copolymer rubber components or island component is preferably 49 mass% or less, more preferably 40 mass% or less, and even more preferably 30 mass% or less. The lower limit of the mass ratio of the polymer portion (b) consisting of polyethylene and ethylene-propylene copolymer rubber components or island component is, for example, 10 mass%.

[0065] The melt flow rate (MFR) of the propylene-ethylene block copolymer is preferably 0.5 g / 10 min or more and 10 g / 10 min or less, more preferably 1 g / 10 min or more and 5 g / 10 min or less. The MFR of the propylene-ethylene block copolymer is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0066] Examples of methods for producing propylene-ethylene block copolymers include polymerizing raw materials such as propylene and ethylene using a catalyst, such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0067] The second dispersed component preferably contains polyethylene. Polyethylene can contribute to improving the impact resistance of the laminate sealant film of the present disclosure. The second layer preferably has a sea-island structure in which polyethylene is dispersed as the second dispersed component in a block polypropylene (propylene-ethylene block copolymer) that is the second matrix resin component. That is, by having a sea-island structure in which a polymer component (b) made of an ethylene-propylene copolymer rubber component and polyethylene as the second dispersed component are dispersed in a polymer component (a) made of a propylene polymer, the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0068] The polyethylene may be the same as the first dispersion component of the first layer.

[0069] The second dispersion component may further contain a second elastomer. By including the second dispersion component in the second elastomer, the dispersion state of the polyethylene, which is the second dispersion component (island component), in the propylene-ethylene block copolymer, which is the second matrix resin component (sea component), can be further improved. This can further enhance the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0070] The second elastomer may be the same thermoplastic elastomer as the first dispersed component of the first layer.

[0071] In the second layer, the content of the second matrix resin component is 30% by mass or more, preferably 35% by mass or more, based on the total amount of the second layer. In the second layer, the content of the second matrix resin component is 90% by mass or less, based on the total amount of the second layer. For example, in the second layer, the content of the second matrix resin component is 30% by mass or more and 90% by mass or less, based on the total amount of the second layer.

[0072] In the second layer, the content of the second dispersion component is preferably 10% by mass or more, more preferably 15% by mass or more, relative to the total amount of the second layer. In the second layer, the content of the second dispersion component is preferably 49% by mass or less, more preferably 30% by mass or less, relative to the total amount of the second layer. For example, in the second layer, the content of the second dispersion component is 10% by mass or more and 49% by mass or less, relative to the total amount of the second layer. When the content of the second dispersion component in the second layer is equal to or greater than the lower limit, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the content of the second dispersion component is equal to or less than the upper limit, the heat resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0073] The polyethylene content in the second layer is 5%, preferably 1% by mass or more, more preferably 2% by mass or more, relative to the total amount of the second layer. The polyethylene content in the second layer is, for example, 50% by mass or less, relative to the total amount of the second layer. For example, the polyethylene content in the second layer is 1% by mass or more and 50% by mass or less, relative to the total amount of the second layer. When the polyethylene content is equal to or greater than the lower limit, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the polyethylene content is equal to or less than the upper limit, the heat resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0074] In the second layer, the content of the second elastomer is preferably 4% by mass or more, more preferably 7% by mass or more, relative to the total amount of the second layer. In the second layer, the content of the second elastomer is, for example, 15% by mass or less, relative to the total amount of the second layer. For example, in the second layer, the content of the second elastomer is 4% by mass or more and 15% by mass or less, relative to the total amount of the second layer. When the content of the second elastomer is equal to or greater than the lower limit, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the content of the second elastomer is equal to or less than the upper limit, for example, the heat resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0075] In the second dispersion component, the ratio of the content of the second elastomer to the content of the polyethylene is preferably 0.5 or more and less than 1.0. When the ratio of the content of the second elastomer to the content of the polyethylene in the second dispersion component is within the above range, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0076] The thickness of the second layer is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more. The thickness of the second layer is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. When the thickness is equal to or greater than the lower limit, for example, the heat resistance and impact resistance of a packaging container including a laminate using the multilayer sealant film of the present disclosure can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0077] (Third Layer) The third layer preferably contains a third matrix resin component and a third dispersed component. In one embodiment, the third layer preferably has a so-called sea-island structure in which the third matrix resin component serves as a sea component and the third dispersed component serves as island components, with the island components dispersed in the sea component. The third layer constitutes the surface layer of the multilayer sealant film of the present disclosure.

[0078] The third matrix resin component includes polypropylene. The polypropylene may be any of homopolypropylene, random polypropylene, and block polypropylene, or a mixture of two or more selected from these. Among these, block polypropylene (block PP) is preferred. The block polypropylene may be the same block polypropylene as the second matrix resin component of the second layer.

[0079] The third dispersed component preferably contains polyethylene. Polyethylene can contribute to improving the impact resistance of the multilayer sealant film of the present disclosure. The third layer has a sea-island structure in which polyethylene, the third dispersed component (island component), is dispersed in block polypropylene, the third matrix resin component (sea component), thereby improving the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0080] As the polyethylene, the same polyethylene as that used for the first and second layers can be used.

[0081] The third dispersion component may further contain a third elastomer. By including the third dispersion component in the third elastomer, the dispersion state of the polyethylene, which is the third dispersion component (island component), in the propylene-ethylene block copolymer, which is the third matrix resin component (sea component), can be further improved. This can further enhance the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0082] The third elastomer may be the same thermoplastic elastomer as that used for the first and second layers.

[0083] In the third layer, the content ratio of the third matrix resin component and the content ratio of the third dispersion component can be the same as in the second layer.

[0084] In the third layer, the content ratio of polyethylene and the content ratio of the third elastomer may be the same as those in the second layer.

[0085] The thickness of the third layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 12 μm or more. The thickness of the third layer is preferably 20 μm or less, more preferably 15 μm or less. When the thickness is equal to or greater than the lower limit, for example, the heat resistance and impact resistance of a packaging container including a laminate using the multilayer sealant film of the present disclosure can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0086] In the multilayer sealant film of the present disclosure, the polyethylene used in the first, second, and third layers may all be the same type of polyethylene, or may be polyethylenes of different densities or molecular weights. Similarly, in the sealant film, the first, second, and third elastomers used in the first, second, and third layers may all be the same type of thermoplastic elastomer, or may be different types of thermoplastic elastomers.

[0087] In the multilayer sealant film of the present disclosure, the content ratio of the first dispersion component relative to the total amount of the first layer, which is the seal layer, is preferably lower than the content ratio of the second dispersion component relative to the total amount of the second layer, which is the core layer. A multilayer sealant film that satisfies the above relationship maintains continuity of impact resistance between the first and second layers, thereby increasing the affinity between the two layers and suppressing breakage at the interface between the two layers, and further improving the low-temperature sealability attributable to the first layer.

[0088] In the multilayer sealant film of the present disclosure, the ratio of the thickness of the second layer to the thickness of the first layer is preferably 3.0 or more. According to a sealant film for laminates that satisfies the above relationship, the heat resistance and impact resistance attributable to the second layer can be further improved.

[0089] The thickness of the multilayer sealant film of the present disclosure is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more. The thickness of the multilayer sealant film is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. When the thickness is equal to or greater than the lower limit, for example, the time required for heat sealing of a packaging container including a laminate using the multilayer sealant film of the present disclosure can be shortened. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved. 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 200 μm or less, more preferably 40 μm or more and 100 μm or less, and even more preferably 50 μm or more and 80 μm or less.

[0090] <Content of Each Component> The polypropylene content in the laminate sealant film of the present disclosure (single-layer sealant film and multi-layer sealant film) is 40% by mass or more, relative to the total amount of the sealant film. Furthermore, the polypropylene content in the laminate sealant film of the present disclosure is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 56% by mass or less, relative to the total amount of the sealant film. For example, the polypropylene content in the laminate sealant film of the present disclosure is 40% by mass or more and 80% by mass or less, relative to the total amount of the sealant film. Having the polypropylene content of 40% by mass or more relative to the total amount of the sealant film enhances resistance to heat sterilization. Furthermore, having the content of 80% by mass or less allows the polyethylene and ethylene-propylene rubber contents to be increased, thereby improving the drop impact resistance (impact resistance) of a packaging container using a laminate comprising the sealant film as a sealant layer.

[0091] In the sealant film for laminates of the present disclosure, the polyethylene content relative to the total amount of the sealant film is preferably 25% by mass or more, more preferably 29% by mass or more, and even more preferably 30% by mass or more. Furthermore, the polyethylene content relative to the total amount of the sealant film is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. For example, the polyethylene content relative to the total amount of the sealant film is 25% by mass or more and 50% by mass or less. When the polyethylene content is equal to or greater than the lower limit, for example, the impact resistance of a laminate using the sealant film of the present disclosure can be further improved. When the polyethylene content is equal to or less than the upper limit, for example, the seal strength of a laminate using the sealant film of the present disclosure can be further improved.

[0092] In the sealant film for laminates of the present disclosure, the content of ethylene-propylene rubber (EPR) relative to the total amount of the sealant film is preferably 5.0% by mass or more, more preferably 7.0% by mass or more, even more preferably 9.0% by mass or more, and even more preferably 9.8% by mass or more. Furthermore, the content of ethylene-propylene rubber (EPR) relative to the total amount of the sealant film is preferably 20.0% by mass or less, more preferably 17.5% by mass or less, and even more preferably 15.0% by mass or less. For example, the content of ethylene-propylene rubber (EPR) relative to the total amount of the sealant film is 5.0% by mass or more and 20.0% by mass or less. When the content of ethylene-propylene rubber is equal to or greater than the lower limit, for example, the impact resistance of a laminate using the sealant film of the present disclosure can be further improved. When the content of ethylene-propylene rubber is equal to or less than the upper limit, for example, the seal strength of a laminate using the sealant film of the present disclosure can be further improved.

[0093] In the sealant film for laminates of the present disclosure, the content of all the dispersed components (i.e., the sum of polyethylene and ethylene-propylene rubber) relative to the total amount of the sealant film is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 44% by mass or more. Furthermore, the content of all the dispersed components relative to the total amount of the sealant film is preferably 60% by mass or less, more preferably 57% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less. For example, the content of all the dispersed components relative to the total amount of the sealant film is 30% by mass or more and 60% by mass or less. In the sealant film of the present disclosure, when the content of all the dispersed components exceeds the lower limit, for example, the impact resistance of a laminate using the sealant film of the present disclosure can be further improved. Furthermore, when the content of all the dispersed components is less than the upper limit, for example, the seal strength of a laminate using the sealant film of the present disclosure can be further improved.

[0094] In the monolayer sealant film of the present disclosure, the elastomer content relative to the total amount of the sealant film is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, the elastomer content relative to the total amount of the sealant film is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. For example, the elastomer content relative to the total amount of the sealant film is 3% by mass or more and 30% by mass or less. When the elastomer content relative to the total amount of the sealant film is equal to or greater than the lower limit, the impact resistance of a laminate using the monolayer sealant film of the present disclosure can be further improved. When the elastomer content is equal to or less than the upper limit, the seal strength of a laminate using the monolayer sealant film of the present disclosure can be further improved.

[0095] In the multilayer sealant film of the present disclosure, the total content of the first to third elastomers (thermoplastic elastomers) relative to the total amount of the sealant film is preferably 3% by mass or more, more preferably 5% by mass or more. Furthermore, the total content of the thermoplastic elastomers relative to the total amount of the sealant film is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. For example, the total content of the thermoplastic elastomers relative to the total amount of the sealant film is 3% by mass or more and 30% by mass or less. When the total content of the thermoplastic elastomers relative to the total amount of the sealant film is within the above range, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved. When the elastomer content is equal to or less than the upper limit, for example, the seal strength of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0096] The content ratio of each component constituting the sealant film for laminates of the present disclosure is a value calculated from the results of component analysis of the sealant film. Component analysis of the sealant film includes structural identification of crystalline and amorphous polymers using a nuclear magnetic resonance (NMR) device, and composition distribution analysis by thermal gradient interaction chromatography (TGIC) and crystallization elution fractionation (CEF) using a composition distribution analyzer. The content ratio of each component can be obtained by combining one or more of these. As a specific example of component analysis of a sealant film, when the types and blending ratios of raw materials are unknown, first １３ The structures of the crystalline polymer and amorphous polymer contained in the sealant film are identified by C-NMR. Next, TGIC analysis and CEF analysis are performed using a composition analyzer, and the contents of the previously identified crystalline polymer and amorphous polymer are calculated. Note that if the blending ratios of the raw materials used in producing the sealant film are known, structural identification by NMR may be omitted. The sample preparation methods and measurement conditions for TGIC analysis and CEF analysis are described in detail in the Examples. Furthermore, NMR analysis can be performed, for example, under the following measurement conditions.

[0097] (NMR measurement conditions) Apparatus: AVANCE III cryo-500 nuclear magnetic resonance apparatus manufactured by Bruker Biospin Measurement nuclei: １３ C (125 MHz) Measurement mode: Single pulse proton broadband decoupling Pulse width: 45° (5.00 μsec) Number of points: 64k Observation range: 250 ppm (-55 to 195 ppm) Repetition time: 5.5 seconds Number of accumulations: 128 Measurement solvent: Orthodichlorobenzene / benzene-d ６(4 / 1 v / v) Sample concentration: ca. 60 mg / 0.6 mL Measurement temperature: 120°C Window function: exponential (BF: 1.0 Hz) Chemical shift reference: δδ signal: 29.73 ppm

[0098] <Composite Elastic Modulus> The composite elastic modulus of the sealant film for laminates of the present disclosure is 500 MPa or more, preferably 600 MPa or more, more preferably 650 MPa or more, and 900 MPa or less, preferably 800 MPa or less, more preferably 850 MPa or less, and is 500 MPa or more and 900 MPa or less. Packaging containers produced using a laminate having a sealant film with a composite elastic modulus within the above range as a sealant layer tend to have excellent drop-breakage resistance (impact resistance) and hand-tearability (openability).

[0099] The composite elastic modulus of the sealant film for laminates is measured by nanoindentation. Specifically, the composite elastic modulus is measured using a nanoindenter with the cross section of the sealant layer of a laminate using the sealant film as the sealant layer as the measurement surface.

[0100] The cross section was obtained by folding the laminate into a V shape with the sealant film side facing inward, and heat-sealing the laminate to a width of 130 mm and a height of 165 mm to produce a bag-like pouch, filling the resulting pouch with 100 mL of water through the opening, heat-sealing the opening, and cutting the sealed pouch in the thickness direction after retort sterilization treatment using a hot water method at a retort temperature of 121°C for a retort time of 30 minutes.

[0101] The location where the indenter is pressed is near the center of each layer constituting the sealant layer in the thickness direction of the sealant layer, within the exposed cross section of the sealant layer. Specifically, when the sealant layer has a single-layer structure, the location is near the center of the sealant layer in the thickness direction. When the sealant layer has a multilayer structure, for example, when the sealant layer (sealant film) has a three-layer structure, the locations are three: a position 2 μm inside from the interface with the adhesive layer, near the center, and a position 2 μm inside from the sealing surface. In this case, the position 2 μm inside from the sealing surface corresponds to the first layer (sealing layer), the position near the center corresponds to the second layer (core layer), and the position 2 μm inside from the interface with the adhesive layer corresponds to the third layer (surface layer). When the sealant layer has a four-layer structure or more, the locations are near the center of each layer in the thickness direction of the sealant layer.

[0102] The measurement conditions are as follows: A Berkovich indenter (triangular pyramidal indenter) is used as the indenter of the nanoindenter. The indenter is pressed into the sealant layer from the cross section of the sealant layer up to a load of 30 μN over a period of 3 seconds, and is held in this state for 5 seconds. The load is then removed over a period of 3 seconds, and the maximum load P ｍａｘ , contact projection area A at maximum depth ｐ A load-displacement curve is obtained. From the load-displacement curve obtained, the composite elastic modulus is calculated using the following formula (1).

[0103] In formula (1), A ｐ is the contact projection area, S is the contact stiffness, and E ｒ is the composite modulus of the sealant layer.

[0104] Measurements are performed at room temperature (23°C). Measurements are performed at five or more locations on the same cross section at the same measurement position (the location where the indenter is pressed). The composite modulus is the arithmetic mean value of the five values ​​measured at each measurement position, and is recorded for each layer constituting the sealant layer. Details of the measurement conditions are described in the Examples section.

[0105] When the measured values ​​at three locations in the thickness direction of the sealant layer (sealant film) are the same, the measured values ​​are taken as the composite modulus of the sealant film for laminates. On the other hand, when the sealant film has a multilayer structure and the measured values ​​in the thickness direction are different, the value at the thickest part in the cross section of the sealant layer is taken as the composite modulus of the sealant film for laminates.

[0106] The composite elastic modulus of the laminate sealant film can be adjusted by the content of additives such as polyethylene, elastomer, etc. Specifically, the greater the content of additives, the lower the composite elastic modulus can be, and the smaller the content of additives, the higher the composite elastic modulus can be.

[0107] Furthermore, when the laminate sealant film contains block polypropylene, the composite modulus of elasticity of the laminate sealant film can be adjusted by the content of ethylene-propylene rubber (EPR). Specifically, the composite modulus of elasticity can be reduced as the content of ethylene-propylene rubber (EPR) increases, and the composite modulus of elasticity can be increased as the content of ethylene-propylene rubber (EPR) decreases.

[0108] <Heat Shrinkage Rate> The heat shrinkage rate of the sealant film for laminates of the present disclosure in the machine direction (MD direction) after heating at 120°C for 15 minutes is preferably 0% or more, and preferably 0.5% or less, more preferably 0.4% or less, and even more preferably 0.3% or less, for example, 0% or more and 0.5% or less. Packaging containers produced using a laminate having a sealant film with a heat shrinkage rate within the above range as a sealant layer shrink less during heating, such as retort sterilization, and are less likely to wrinkle. Furthermore, they tend to be easier to tear by hand after retort treatment, and therefore easier to open.

[0109] The heat shrinkage rate of the laminate sealant film can be adjusted by selecting the type of polypropylene and the content of each component. As for the type of polypropylene, block polypropylene has higher heat resistance than random polypropylene, so the heat shrinkage rate can be increased by increasing the content of block polypropylene, and the heat shrinkage rate can be decreased by increasing the content of random polypropylene.

[0110] When the sealant film for laminates contains block polypropylene, a high content of ethylene-propylene rubber (EPR) reduces heat resistance, so the heat shrinkage rate can be increased by increasing the content of ethylene-propylene rubber (EPR), and the heat shrinkage rate can be reduced by decreasing the content.

[0111] Furthermore, when the sealant film for laminates contains block polypropylene, the heat resistance decreases as the content of additives such as polyethylene and elastomer increases. Therefore, the heat shrinkage rate can be increased by increasing the content of additives, and the heat shrinkage rate can be decreased by decreasing the content.

[0112] <Main Melting Peak Temperature> The main melting peak temperature of the sealant film for laminates of the present disclosure, measured in accordance with JIS K7121:2012, is preferably 140°C or higher, more preferably 155°C. When a main melting peak temperature of 140°C or higher is observed in a sealant layer using the sealant film for laminates of the present disclosure, the drop impact resistance of a packaging container produced using the laminate can be improved. Furthermore, when a main melting peak temperature of 155°C or higher is observed in a sealant layer using the sealant film for laminates of the present disclosure, the heat resistance of a packaging container produced using the laminate can be improved.

[0113] The melting peak temperature of the laminate sealant film is obtained by differential scanning calorimetry (DSC). In the present disclosure, the conditions for measuring the melting peak temperature of the laminate sealant film are as follows: First, a standing pouch is prepared from a laminate using the laminate sealant film as a sealant layer. Water is filled into the resulting pouch through the opening, and the opening is heat-sealed to seal the pouch. The sealed pouch is then subjected to a hot water retort treatment at a retort temperature of 121°C and a retort time of 30 minutes. From the standing pouch after the retort treatment, a sealant film corresponding to the sealant layer in the non-heat-sealed portion is separated as a test piece. In accordance with JIS K7121, the separated sealant film is held at 20°C for 1 minute, and then heated from 20°C to 200°C at a heating rate of 10°C / min to measure the melting peak temperature. The nitrogen gas flow rate is 20 ml / min. Details of the above conditions are described in the Examples section. The melting peak temperature here means the peak top temperature of the melting peak in the DSC curve.

[0114] The main melting peak temperature means the peak top temperature of the largest melting peak when multiple melting peaks are obtained.

[0115] When the sealant layer contains block polypropylene, the main melting peak temperature of the laminate sealant film can be adjusted by the content of ethylene-propylene rubber (EPR). Specifically, when the laminate sealant film contains block polypropylene, the main melting peak temperature can be shifted to a lower temperature as the content of ethylene-propylene rubber (EPR) increases, and the main melting peak temperature can be shifted to a higher temperature as the content of ethylene-propylene rubber (EPR) decreases.

[0116] The sealant film can be produced by, for example, a conventionally known method. The sealant film can be obtained by mixing the above-mentioned materials by a conventional method and molding the resulting mixture into a film by a conventional method. The sealant film is preferably a film obtained by extrusion molding. The extrusion molding is preferably carried out by a T-die method or an inflation method. Specifically, the materials constituting the sealant film are dried as necessary, and then fed into a melt extruder heated to a temperature equal to or higher than the melting point of the material to melt the material, and extruded into a film form through a die such as a T-die. The extruded film is then rapidly cooled and solidified on a rotating cooling drum or the like, thereby forming a single-layer or multi-layer sealant film.

[0117] As the melt extruder, a single-screw extruder, a twin-screw extruder, a vent extruder, a tandem extruder, etc. can be used depending on the purpose. The temperature of the molten polymer when extruded from the melt extruder may be, for example, 200°C or higher and 300°C or lower, or 220°C or higher and 270°C or lower.

[0118] [Laminate] The laminate of the present disclosure includes a substrate (first substrate) and a sealant layer. The substrate is a stretched substrate containing polypropylene as a main component. The sealant layer contains polypropylene as a main component. The laminate of the present disclosure is suitable for use as a packaging material.

[0119] The laminate of the present disclosure may include one substrate or two or more substrates. Preferably, the laminate of the present disclosure further includes a second substrate between the first substrate and the sealant layer, and includes the first substrate, the second substrate, and the sealant layer in this order in the thickness direction.

[0120] The first substrate is a stretched substrate containing polypropylene as a main component. The second substrate is a stretched substrate containing polypropylene as a main component. The stretched substrate of the first substrate and the stretched substrate of the second substrate may be the same or different. In the following description, the stretched substrate containing polypropylene as a main component is also referred to as an "stretched polypropylene substrate."

[0121] In one embodiment, one of the first substrate and the second substrate is a barrier substrate, and the other of the first substrate and the second substrate is an oriented polypropylene substrate. In another embodiment, both the first substrate and the second substrate may be a barrier substrate, or both the first substrate and the second substrate may be an oriented polypropylene substrate.

[0122] 3 to 20 are schematic cross-sectional views showing one embodiment of a laminate. The laminate 1 shown in Fig. 3 comprises a barrier substrate 20 as a base material, an adhesive layer 40, and a sealant layer 30, in this order in the thickness direction. The barrier substrate 20 comprises an oriented polypropylene substrate 22 and an inorganic oxide layer 24. In this example, the barrier substrate 20 is arranged such that the oriented polypropylene substrate 22 constitutes the outermost layer of the laminate 1, and the inorganic oxide layer 24 faces the adhesive layer 40. Here, the inorganic oxide layer 24 and the adhesive layer 40 may be in contact with each other.

[0123] FIG. 4 is similar to FIG. 3 except that the barrier substrate 20 has a surface coating layer 23 or a surface resin layer 26 between the oriented polypropylene substrate 22 and the inorganic oxide layer 24 .

[0124] Fig. 5 is the same as Fig. 3 except that the barrier substrate 20 includes a stretched polypropylene substrate 22, a surface coating layer 23 or surface resin layer 26, an inorganic oxide layer 24, and a coating layer 25 in this order in the thickness direction. In this example, the barrier substrate 20 is arranged so that the coating layer 25 faces the adhesive layer 40. The coating layer 25 and the adhesive layer 40 may be in contact with each other. Fig. 6 is the same as Fig. 4 except that the barrier substrate 20 includes an adhesive resin layer 27 between the polypropylene resin layer 22 and the surface resin layer 26. Fig. 7 is the same as Fig. 5 except that the barrier substrate 20 includes a polypropylene resin layer 22, an inorganic oxide layer 24, and a coating layer 25 in this order in the thickness direction. Fig. 8 is the same as Fig. 5 except that the barrier substrate 20 includes an adhesive resin layer 27 between the polypropylene resin layer 22 and the surface resin layer 26.

[0125] The laminate 1 shown in Fig. 9 comprises, in this order in the thickness direction, a stretched polypropylene substrate 10 as a first substrate, an adhesive layer 40A, a barrier substrate 20 as a second substrate, an adhesive layer 40B, and a sealant layer 30. The barrier substrate 20 comprises a stretched polypropylene substrate 22 and an inorganic oxide layer 24. In this example, the barrier substrate 20 is arranged so that the stretched polypropylene substrate 22 faces the adhesive layer 40B, and the inorganic oxide layer 24 faces the adhesive layer 40A. The inorganic oxide layer 24 and the adhesive layer 40A may be in contact with each other.

[0126] FIG. 10 is similar to FIG. 9 except that the barrier substrate 20 has a surface coating layer 23 or a surface resin layer 26 between the oriented polypropylene substrate 22 and the inorganic oxide layer 24 .

[0127] Fig. 11 is similar to Fig. 9 except that the barrier substrate 20 includes a stretched polypropylene substrate 22, a surface coating layer 23 or a surface resin layer 26, an inorganic oxide layer 24, and a coating layer 25 in this order in the thickness direction. In this example, the barrier substrate 20 is arranged so that the coating layer 25 faces the adhesive layer 40A. The coating layer 25 and the adhesive layer 40A may be in contact with each other. Fig. 12 is similar to Fig. 10 except that the barrier substrate 20 includes an adhesive resin layer 27 between the polypropylene resin layer 22 and the surface resin layer 26. Fig. 13 is similar to Fig. 10 except that the barrier substrate 20 includes a polypropylene resin layer 22, an inorganic oxide layer 24, and a coating layer 25 in this order in the thickness direction. Fig. 14 is similar to Fig. 11 except that the barrier substrate 20 includes an adhesive resin layer 27 between the polypropylene resin layer 22 and the surface resin layer 26.

[0128] 15 includes, in the thickness direction, a barrier substrate 20 as a first substrate, an adhesive layer 40A, an oriented polypropylene substrate 10 as a second substrate, an adhesive layer 40B, and a sealant layer 30. The barrier substrate 20 includes an oriented polypropylene substrate 22 and an inorganic oxide layer 24. In this example, the barrier substrate 20 is arranged such that the oriented polypropylene substrate 22 is located as the outermost layer of the laminate 1, and the inorganic oxide layer 24 faces the adhesive layer 40A. The inorganic oxide layer 24 and the adhesive layer 40A may be in contact with each other.

[0129] FIG. 16 is similar to FIG. 15 except that the barrier substrate 20 has a surface coating layer 23 or a surface resin layer 26 between the oriented polypropylene substrate 22 and the inorganic oxide layer 24 .

[0130] Fig. 17 is similar to Fig. 15 , except that the barrier substrate 20 includes a stretched polypropylene substrate 22, a surface coating layer 23 or a surface resin layer 26, an inorganic oxide layer 24, and a coating layer 25, in this order in the thickness direction. In this example, the barrier substrate 20 is arranged so that the coating layer 25 faces the adhesive layer 40A. The coating layer 25 and the adhesive layer 40 may be in contact with each other. Fig. 18 is similar to Fig. 16 , except that the barrier substrate 20 includes an adhesive resin layer 27 between the polypropylene resin layer 22 and the surface resin layer 26. Fig. 19 is similar to Fig. 17 , except that the barrier substrate 20 includes a polypropylene resin layer 22, an inorganic oxide layer 24, and a coating layer 25, in this order in the thickness direction. Fig. 20 is similar to Fig. 17 , except that the barrier substrate 20 includes an adhesive resin layer 27 between the polypropylene resin layer 22 and the surface resin layer 26.

[0131] Specific examples of the layer structure of the laminate of the present disclosure are shown below. " / " indicates the boundary between layers. "OPP film" represents a stretched polypropylene substrate. (1) OPP film / printed layer / adhesive layer / sealant layer (2) Barrier substrate / printed layer / adhesive layer / sealant layer (3) OPP film / printed layer / adhesive layer / barrier substrate / adhesive layer / sealant layer (4) Barrier substrate / printed layer / adhesive layer / OPP film / adhesive layer / sealant layer (5) Barrier substrate / printed layer / adhesive layer / barrier substrate / adhesive layer / sealant layer (6) OPP film / printed layer / adhesive layer / OPP film / adhesive layer / sealant layer

[0132] In one embodiment, the laminate of the present disclosure includes at least three elements: a stretched polypropylene substrate, a barrier substrate, and a sealant layer, which can further improve gas barrier properties (particularly oxygen barrier properties and water vapor barrier properties).

[0133] When the first substrate is a barrier substrate, in one embodiment, the first substrate is positioned so that the inorganic oxide layer faces the sealant layer and the oriented polypropylene substrate faces away from the sealant layer.

[0134] When the second substrate is a barrier substrate, in one embodiment, the second substrate is arranged so that the inorganic oxide layer faces the first substrate side and the oriented polypropylene substrate faces the sealant layer side, or the second substrate is arranged so that the inorganic oxide layer faces the sealant layer side and the oriented polypropylene substrate faces the first substrate side. Among these, when the second substrate is a barrier substrate, from the viewpoint of further suppressing deterioration of the inorganic oxide layer, it is preferable that the second substrate is arranged so that the inorganic oxide layer faces the first substrate side and the oriented polypropylene substrate faces the sealant layer side.

[0135] In one embodiment of the laminate of the present disclosure, the first substrate is an oriented polypropylene substrate, and the second substrate is a barrier substrate (see Figures 9 to 14). In this embodiment, the laminate comprises an oriented polypropylene substrate, a barrier substrate, and a sealant layer, in this order in the thickness direction. A laminate with such a configuration adequately protects the inorganic oxide layer when subjected to heat treatment or the like, and exhibits even higher gas barrier properties. Furthermore, the laminate of the above embodiment has a smaller heat shrinkage rate when subjected to heat treatment, and therefore is even more suitable for bag formation.

[0136] The proportion of a single polypropylene-based material in the laminate of the present disclosure (hereinafter also referred to as the "mono-material ratio") is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and particularly preferably 90% by mass or more. This allows, for example, the laminate to be used to produce a mono-material packaging container, thereby improving the recyclability of the packaging container. A higher mono-material ratio is preferable, but the upper limit may be, for example, 99% by mass or 98% by mass.

[0137] In this disclosure, the mono-material ratio refers to the proportion of a single polypropylene-based material relative to the total mass of the laminate. However, if a layer contains polypropylene as the main component (i.e., more than 50% by mass), the mono-material ratio is calculated assuming that polypropylene constitutes 100% by mass of the layer. For example, in the case of a sealant layer composed of 80% by mass of polypropylene, 5% by mass of thermoplastic elastomer, and 15% by mass of polyethylene, the mono-material ratio is calculated assuming that the sealant layer is composed of 100% by mass of polypropylene.

[0138] <Stretched Polypropylene Substrate> The stretched polypropylene substrate contains polypropylene as a main component. The polypropylene may be any of homopolypropylene, random polypropylene, and block polypropylene, or a mixture of two or more selected from these. Biomass-derived polypropylene and / or recycled polypropylene may be used as the polypropylene. Homopolypropylene is a polymer of propylene alone. Random polypropylene is a random polypropylene of propylene and an α-olefin other than propylene. Block polypropylene is a polypropylene 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. Details of the α-olefin are as described above.

[0139] Among polypropylenes, random polypropylene is preferred from the viewpoint of transparency, homopolypropylene is preferred when the rigidity and heat resistance of the packaging container are important, and block polypropylene is preferred when the impact resistance of the packaging container is important. In the present disclosure, among these polypropylenes, homopolypropylene and block polypropylene are more preferred from the viewpoint of heat resistance and impact resistance.

[0140] From the viewpoint of film-forming property and processability, the melt flow rate (MFR) of the polypropylene is preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, and is 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 the 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.

[0141] The polypropylene content in the stretched polypropylene substrate 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.

[0142] The oriented polypropylene substrate may contain a resin material other than polypropylene, such as 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.

[0143] The stretched polypropylene substrate is a polypropylene substrate that has been subjected to a stretching treatment. A laminate including a stretched polypropylene substrate has excellent heat resistance, impact resistance, water resistance, and dimensional stability, and is suitable as a packaging material for constituting a packaging container that undergoes retort or boiling treatment, for example. The stretching treatment may be uniaxial or biaxial. When stretching in the machine direction (the flow direction of the substrate, MD direction), the stretching ratio is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less. When stretching in the width direction (the direction perpendicular to the MD direction, TD direction), the stretching ratio is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less. A stretching ratio of 2 times or more can improve the strength and heat resistance of the substrate and can also improve the printability of the substrate. From the viewpoint of the breaking limit of the substrate, the stretching ratio is preferably 15 times or less. The oriented polypropylene substrate is, for example, a biaxially oriented substrate.

[0144] 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 oriented polypropylene substrate.

[0145] The stretched 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 preferably 100 μm or less, more preferably 50 μm or less, for example, 10 μm or more and 100 μm or less. A laminate including a stretched substrate having a thickness equal to or greater than the lower limit has, for example, excellent strength and heat resistance. A laminate including a stretched substrate having a thickness equal to or less than the upper limit has, for example, excellent processability.

[0146] <Barrier Substrate> The barrier substrate comprises an oriented polypropylene substrate and an inorganic oxide layer. The barrier substrate comprises, for example, an oriented polypropylene substrate and an inorganic oxide layer provided on one surface of the oriented substrate. The barrier substrate may comprise a surface coating layer between the oriented polypropylene substrate and the inorganic oxide layer. The barrier substrate may comprise a covering layer on the inorganic oxide layer. The barrier substrate may be transparent.

[0147] (Stretched polypropylene substrate) Examples of the stretched polypropylene substrate included in the barrier substrate include the stretched polypropylene substrates described in the section <Stretched polypropylene substrate>. The stretched polypropylene substrate of the first substrate and the stretched polypropylene substrate of the second substrate may be the same or different.

[0148] The stretched polypropylene substrate included in the barrier substrate may be, for example, a stretched substrate of another embodiment that includes, in this order, a polypropylene layer, an optional adhesive resin layer, and a surface resin layer described below. In this embodiment, the barrier substrate includes a stretched substrate of another embodiment and an inorganic oxide layer provided on the surface resin layer of the stretched substrate. In this embodiment, the barrier substrate includes, in this order, a polypropylene layer, an optional adhesive resin layer, a surface resin layer, and an inorganic oxide layer. 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, an inflation method, or the like, and then stretching the laminated film.

[0149] The stretching treatment of the stretched substrate in another embodiment may be uniaxial stretching or biaxial stretching. When stretching in the MD direction, the stretching ratio is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less. When stretching in the TD direction, the stretching ratio is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less.

[0150] (Surface Coating Layer) The barrier substrate 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 substrate has excellent adhesion to the inorganic oxide layer and also excellent gas barrier properties. Such a barrier substrate has, in this order, the stretched polypropylene substrate, the surface coating layer, and the inorganic oxide layer.

[0151] The polar group refers to a group containing one or more heteroatoms, and examples thereof include an ester group, an epoxy group, a hydroxyl group, an amino group, an amide group, a urethane group, a carboxyl group, a carbonyl group, a carboxylic anhydride group, a sulfo group, a thiol group, and a halogen group. Among these, the carboxyl group, the carbonyl group, the ester group, the hydroxyl group, the amino group, the amide group, and the urethane group are preferred, and the carboxyl group, the hydroxyl group, the amide group, and the urethane group are more preferred.

[0152] Examples of resin materials having a polar group include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl group-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 group-containing acrylic resin, polyamide, and polyurethane are more preferred.

[0153] The surface coating layer can be formed using, for example, an aqueous emulsion or a solvent-based emulsion. Examples of aqueous emulsions include polyamide-based emulsions, polyethylene-based emulsions, and polyurethane-based emulsions. Examples of solvent-based emulsions include acrylic resin-based emulsions and polyester-based emulsions.

[0154] The content of the resin material having a polar group in the surface coating 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 material other than the resin material having a polar group. The surface coating layer may also contain the above-mentioned additive.

[0155] The ratio of the thickness of the surface coating layer to the total thickness of the polypropylene oriented substrate and the surface coating layer is preferably 0.08% or more, more preferably 0.2% or more, even more preferably 1% or more, and preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less, for example, 0.08% or more and 20% or less. The thickness of the surface coating 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 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 greater than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the gas barrier properties can be improved, 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 substrate and the recyclability of the laminate can be improved.

[0156] For example, a 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, followed by drying, thereby producing a resin substrate having a stretched polypropylene substrate and a surface coating layer.

[0157] (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. Details of the polypropylene are as described above, and will not be described again here. The polypropylene content 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.

[0158] The polypropylene layer may contain the above-mentioned resin material other than polypropylene. The polypropylene layer may contain the above-mentioned additive.

[0159] 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.

[0160] In a first embodiment, 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 the polypropylene layer and the 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 improve gas barrier properties. Furthermore, packaging containers produced using a laminate having this surface resin layer have high lamination strength.

[0161] In one embodiment, the surface resin layer may be provided on the polypropylene resin layer. That is, the surface resin layer may be adjacent to the polypropylene resin layer. In one embodiment, when an adhesive resin layer is provided between the polypropylene resin layer and the surface resin layer, the adhesive resin layer may be provided on the polypropylene resin layer, and the surface resin layer may be provided on the adhesive resin layer. That is, the adhesive resin layer may be adjacent to the polypropylene resin layer, and the surface resin layer may be adjacent to the adhesive resin layer.

[0162] 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 gas barrier properties can be improved, 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-forming properties of the stretched substrate.

[0163] In this specification, the melting point of a high-melting-point resin material or the like can be measured in accordance with JIS K7121:2012 (Method for measuring transition temperature of plastics). Specifically, a differential scanning calorimetry (DSC) curve can be measured at a temperature rise rate of 10°C / min using a DSC device, and the melting peak temperature can be determined as the melting point.

[0164] The difference between the melting point TA of the high-melting point resin material contained in the surface resin layer and the melting point TB of the polypropylene contained in the polypropylene resin layer is preferably 20°C or more. The difference between the melting point TA and the melting point TB is preferably 80°C or less, and more preferably 60°C or less. When the difference between the melting point TA and the melting point TB is equal to or greater than the lower limit, the adhesion between the surface resin layer and the vapor-deposited film can be further improved, and the gas barrier property can be further improved. In addition, the laminate strength of the packaging container can be further improved. In addition, when the difference between the melting point TA and the melting point TB is equal to or less than the upper limit, the film-forming property of the polypropylene resin substrate can be further improved.

[0165] 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, carboxyl groups, carbonyl groups, carboxylic anhydride groups, sulfo groups, thiol groups, and halogen groups. Among these, hydroxyl groups, ester groups, amino groups, amide groups, carboxyl groups, and carbonyl groups are preferred, and amide groups are more preferred.

[0166] The high-melting-point resin material may have a melting point of 180°C or higher, and examples thereof include polyolefins, vinyl resins, acrylic resins, polyamides, polyimides, polyesters, cellulose resins, and ionomer resins. For example, resin materials having a melting point of 180°C or higher and containing polar groups are preferred, and ethylene-vinyl alcohol copolymers, polyvinyl alcohol, polyesters, and polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon are more preferred. The use of such resin materials can significantly improve the adhesion of the vapor-deposited film formed on the surface resin layer, and can effectively prevent a decrease in gas barrier properties.

[0167] In one embodiment, the high-melting-point resin material is preferably polyamide. By using polyamide as the high-melting-point resin material, it is possible to suppress the deterioration of gas barrier properties even after bending the laminate, and to improve the heat resistance of the laminate. In addition, it is possible to suppress the deterioration of gas barrier properties even after the laminate is subjected to a retort treatment and a boiling treatment, which will be described later. It is more preferable that the high-melting-point resin material be nylon 6.

[0168] In the first embodiment, 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 even more preferably 90% by mass or more.

[0169] In a second embodiment, the surface resin layer contains a random polypropylene of propylene and an α-olefin other than propylene. By providing a surface resin layer containing the random polypropylene between the polypropylene layer and the adhesive layer or the second adhesive layer, it is possible to improve the adhesive strength between the sealant layer and the oriented polypropylene substrate (i.e., the barrier substrate) and also improve the impact resistance of the laminate.

[0170] Examples of the random polypropylene include propylene-ethylene random polypropylene and propylene-ethylene-butene random polypropylene, and any one of these or a mixture of two or more thereof can be used as the random polypropylene.

[0171] In the propylene-ethylene random polypropylene, the content of ethylene-derived structural units is preferably 2% by mass or more, more preferably 4% by mass or more. Furthermore, the content is preferably 50% by mass or less, more preferably 40% by mass or less. By having the content within the above preferred range, for example, drop impact resistance can be further improved. In the present disclosure, the content of structural units can be measured, for example, by thermal gradient interaction chromatography (TGIC).

[0172] In the propylene-ethylene-butene random polypropylene, the content of ethylene-derived structural units and butene-derived structural units is preferably 2% by mass or more, more preferably 4% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less.

[0173] In a second aspect, the content of the random polypropylene in the surface resin layer is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount of the surface resin layer. By containing 50% by mass or more of the random polypropylene, the surface resin layer exhibits sufficient adhesive strength.

[0174] The surface resin layer may contain the high-melting point resin material and the above-mentioned resin material other than the random polypropylene of propylene and an α-olefin other than propylene. The surface resin layer may contain the above-mentioned additive. The surface resin layer may be subjected to the above-mentioned surface treatment.

[0175] The ratio of the thickness of the surface resin layer to the total thickness of another embodiment of the stretched substrate 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 greater than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the gas barrier properties can be improved, 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 and processability of the stretched substrate of another embodiment and the recyclability of the laminate can be improved.

[0176] Another embodiment of the stretched substrate may include 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, from the viewpoint of the recyclability of the laminate, polyolefin and its acid-modified product are preferred, and polypropylene and its acid-modified product are more preferred. Commercially available polypropylene can be used as the adhesive resin layer, for example, the Admer series manufactured by Mitsui Chemicals, Inc.

[0177] (Inorganic oxide layer) The barrier substrate comprises an inorganic oxide layer. The inorganic oxide layer contains one or more inorganic oxides, for example, a vapor-deposited film of an inorganic oxide. A laminate comprising the barrier substrate has excellent gas barrier properties, specifically, oxygen barrier properties and water vapor barrier properties. A packaging container produced using such a laminate can suppress oxidative deterioration of the contents filled in the packaging container and suppress weight loss of the contents. The barrier substrate may, for example, comprise an inorganic oxide layer on a surface coating layer, or an inorganic oxide layer on a surface resin layer.

[0178] 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.

[0179] In one embodiment, silica is more preferable as the inorganic oxide because it does not require aging treatment after forming the inorganic oxide layer. In one embodiment, carbon-containing silicon oxide is more preferable as the inorganic oxide because it can suppress deterioration of gas barrier properties even when the laminate is bent.

[0180] 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 excellent oxygen barrier properties and water vapor barrier properties, for example. A laminate having an inorganic oxide layer whose thickness is equal to or less than the upper limit can suppress the occurrence of cracks in the inorganic oxide layer and has excellent recyclability, for example.

[0181] The surface of the inorganic oxide layer may be subjected to the above-mentioned surface treatment.

[0182] Examples of methods for forming an inorganic oxide layer, particularly an inorganic oxide vapor deposition film, include physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (CVD methods) such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0183] The inorganic oxide layer may be a single layer formed by a single vapor deposition process, or may be a multilayer formed by multiple vapor 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.

[0184] 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 flex resistance.

[0185] The carbon-containing silicon oxide vapor-deposited film contains silicon, oxygen, and carbon. In one embodiment of the carbon-containing silicon oxide vapor-deposited 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, relative to 100% of the total of the three elements silicon, oxygen, and carbon, for example, 3% or more and 50% or less. By setting the carbon ratio C within the above range, for example, deterioration of the gas barrier property can be suppressed even when the laminate is bent. In this specification, the ratio of each element is based on a molar basis.

[0186] In one embodiment of the carbon-containing silicon oxide vapor-deposited 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 100% of the total of the three elements silicon, oxygen, and carbon. 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 100% of the total of the three elements silicon, oxygen, and carbon. By setting the silicon ratio Si and the oxygen ratio O within the above ranges, for example, deterioration of the gas barrier property can be further suppressed even when the laminate is bent.

[0187] 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 preferably decrease in the order of ratio O, ratio C, and ratio Si. This makes it possible to further suppress a decrease in gas barrier properties, for example, even when the laminate is bent.

[0188] 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.

[0189] (Measurement conditions) Equipment used: "ESCA-3400" (Kratos) [1] Spectrum collection conditions Incident X-ray: MgKα (non-monochromated X-ray, hν=1253.6 eV) X-ray output: 150 W (10 kV, 15 mA) Measurement area: approx. 6 mmφ Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar+ Ar gas introduction pressure: 2.0 × 10 －２ Pa Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Ion sputtering time: 30 seconds, and the spectrum was collected.

[0190] (Coating Layer) The barrier substrate may further include a coating layer on the inorganic oxide layer. That is, the barrier substrate may further include a coating layer on the surface of the inorganic oxide layer opposite to the surface facing the stretched polypropylene substrate. A laminate including such a barrier substrate has, for example, excellent oxygen barrier properties and water vapor barrier properties.

[0191] 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 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.

[0192] 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.

[0193] 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 with, if necessary, additives and a solvent. Details of these components are as described above. Known coating methods can be used to apply the coating liquid for the coating layer. Methods for drying the applied coating liquid for the coating layer include, for example, hot air drying, heat roll drying, and methods that apply heat, such as infrared irradiation. The drying temperature can be 50°C or higher and 150°C or lower.

[0194] In one embodiment, the coating layer may be a barrier coat layer containing a gas barrier resin. Examples of gas barrier resins include ethylene-vinyl alcohol copolymers, polyvinyl alcohol, polyacrylonitrile, polyester, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, polyurethanes, and (meth)acrylic resins. Among these, polyvinyl alcohol is preferred from the viewpoint of oxygen barrier properties and water vapor barrier properties. Furthermore, by including polyvinyl alcohol in the barrier coat layer, the occurrence of cracks in the inorganic oxide layer can be effectively prevented.

[0195] 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, even more preferably 70% by mass or more, and even more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, for example, 50% by mass or more and 90% by mass or less. Such a barrier coat layer has, for example, excellent gas barrier properties. The barrier coat layer may contain the above-mentioned additives.

[0196] 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 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 with a thickness equal to or greater than the lower limit exhibits, for example, excellent gas barrier properties. A barrier substrate having a barrier coat layer with a thickness equal to or less than the upper limit can improve, for example, the processability and recyclability of the laminate. Furthermore, as long as the thickness of the barrier coat layer is within the above range, recycling suitability is not impaired even if the gas barrier resin is a resin material other than polypropylene.

[0197] 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.

[0198] 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 substrate 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 metal alkoxide or the like by a sol-gel method. By providing such a gas barrier coating film on the inorganic oxide layer, for example, it is possible to effectively suppress the occurrence of cracks in the inorganic oxide layer.

[0199] The metal alkoxide is represented by, for example, formula (1): １ ｎ M (OR ２ ) ｍ (1) In formula (1), R １ and R ２ R 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 valence of M. １ and R ２Examples of the organic group in the formula (I) 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.

[0200] Examples of water-soluble polymers include hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties, such as oxygen barrier property, water vapor barrier property, water resistance, and weather resistance, either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Alternatively, a gas barrier coating film obtained using polyvinyl alcohol and a gas barrier coating film obtained using an ethylene-vinyl alcohol copolymer may be laminated. The amount of 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, per 100 parts by mass of the metal alkoxide. By ensuring that the content of the water-soluble polymer in the gas barrier coating film is equal to or greater than the lower limit, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. Furthermore, by ensuring that the content of the water-soluble polymer in the gas barrier coating film is equal to or less than the upper limit, the film formability of the gas barrier coating film can be improved.

[0201] 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 preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the metal alkoxide.

[0202] In the gas barrier coating film, the ratio of the metal alkoxide to the water-soluble polymer (metal alkoxide / water-soluble polymer) is, by mass, preferably 4.5 or less, more preferably 3.5 or less, and also preferably 1.0 or more, more preferably 1.7 or more, for example, 1.0 or more and 4.5 or less. By setting the ratio of the metal alkoxide to the water-soluble polymer to the upper limit or less, it is possible to suppress a decrease in gas barrier properties even after bending the laminate. By setting the ratio of the metal alkoxide to the water-soluble polymer to the lower limit or more, it is possible to improve the heat resistance of the laminate. Furthermore, it is possible to suppress a decrease in gas barrier properties even after the laminate is subjected to retort treatment and boiling treatment. Note that the above ratio is a solid content ratio.

[0203] The silicon atom to carbon atom ratio (Si / C) on the surface of the gas barrier coating film, as measured by X-ray photoelectron spectroscopy (XPS), is preferably 1.60 or less, more preferably 1.35 or less, and also preferably 0.50 or more, more preferably 0.90 or more. By setting the silicon atom to carbon atom ratio to the upper limit or less, it is possible to suppress a decrease in gas barrier properties even after bending the laminate. By setting the silicon atom to carbon atom ratio to the lower limit or more, it is possible to improve the heat resistance of the laminate. Furthermore, it is possible to suppress a decrease in gas barrier properties even after retort treatment and boiling treatment of the laminate. The above range of the silicon atom to carbon atom ratio can be achieved by appropriately adjusting the ratio of metal alkoxide to water-soluble polymer. Note that in this specification, the silicon atom to carbon atom ratio is based on molar basis.

[0204] The ratio of silicon atoms to carbon atoms by X-ray photoelectron spectroscopy (XPS) can be measured by narrow scan analysis under the following measurement conditions. (Measurement conditions) Instrument used: "ESCA-3400" (Kratos) [1] Spectrum collection conditions Incident X-ray: MgKα (monochromated X-ray, hν=1253.6 eV) X-ray output: 150 W (10 kV, 15 mA) X-ray scanning area (measurement area): approximately 6 mmφ Photoelectron acceptance angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar ＋Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Etch range: 10 mmφ Ion sputtering time: 30 seconds + 30 seconds + 60 seconds (total 120 seconds) and collect the spectrum

[0205] The gas barrier composition may contain water in an amount of preferably 0.1 mol or more, more preferably 0.5 mol or more, even more preferably 0.8 mol or more, and preferably 100 mol or less, more preferably 60 mol or less, even more preferably 2 mol or less, per mol of metal alkoxide. By setting the water content to the lower limit or more, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved. By setting the water content to the upper limit or less, for example, the hydrolysis reaction can be carried out quickly.

[0206] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butyl alcohol.

[0207] The sol-gel catalyst is preferably an acid or an amine compound. Examples of acids 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 acid used is preferably 0.001 mol or more and 0.05 mol or less per mol of the total molar amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent. By using an amount of acid equal to or greater than the lower limit, the catalytic effect can be improved. By using an amount of acid equal to or less than the upper limit, the thickness of the formed gas barrier coating film can be made uniform.

[0208] Suitable amine compounds are tertiary amines that are substantially insoluble in water and soluble in organic solvents, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. Among these, N,N-dimethylbenzylamine is preferred. 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 preferably 1.0 part by mass or less, more preferably 0.3 part by mass or less, per 100 parts by mass of the total amount of the metal alkoxide and the silane coupling agent. By using an amount of the amine compound that is equal to or greater than the lower limit, the catalytic effect can be improved. By using an amount of the amine compound that is equal to or less than the upper limit, the thickness of the gas barrier coating film formed can be made uniform.

[0209] Examples of methods for applying the gas barrier composition include roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

[0210] One embodiment of a method for forming a gas barrier coating film is described below. 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 progresses within the composition. The composition is applied to an inorganic oxide layer by a conventional method and dried. This drying further promotes polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above procedure. 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 preferably 250°C or lower, more preferably 220°C or lower, even more preferably 150°C or lower, even more preferably 120°C or lower, and particularly preferably 100°C or lower, for 1 second to 10 minutes. This allows the formation of a gas barrier coating film.

[0211] 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 100 μm or less, more preferably 10 μm or less, even more preferably 2 μm or less, still more preferably 1 μm or less, and particularly preferably 0.5 μm or less, for example, from 0.01 μm to 100 μm. This can improve the gas barrier properties, suppress the occurrence of cracks in the inorganic oxide layer, and improve the recyclability of the packaging container, for example.

[0212] <Printed 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, and between any layers. The image formed on the printed layer is not particularly limited, and may include letters, patterns, symbols, and combinations thereof. The printed layer may also be formed using ink derived from biomass. This can further reduce the environmental impact.

[0213] 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 environmental impact. The thickness of the printed layer is, for example, 0.5 μm or more and 3 μm or less.

[0214] <Adhesive Layer> In one embodiment, the laminate of the present disclosure includes an adhesive layer between the substrate and the sealant layer. In one embodiment, the laminate of the present disclosure includes a first adhesive layer between the first substrate and the second substrate. In one embodiment, the laminate of the present disclosure includes a second adhesive layer between the second substrate and the sealant layer. Such a laminate has excellent lamination strength, for example, between the substrate and the sealant layer, between the first substrate and the second substrate, and between the second substrate and the sealant layer.

[0215] (Adhesive) The adhesive layer, 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 a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive, with a two-component curing adhesive being preferred from the viewpoint of making it easier to adjust the elastic modulus of the adhesive layer to the required range.

[0216] A method for obtaining a laminate using an adhesive includes applying the adhesive to an object, then superimposing another object on the formed adhesive layer and allowing the adhesive layer sandwiched between them 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 hereinafter also referred to as the "aging process."

[0217] The aging conditions for 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.

[0218] 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, from the viewpoint of easily adjusting the elastic modulus within the above-mentioned range, polyurethane adhesives, polyester adhesives, and polyether adhesives are preferred, polyurethane adhesives and polyester adhesives are more preferred, polyurethane adhesives are even more preferred, and two-component curing polyurethane adhesives are particularly preferred.

[0219] The adhesive may be a solvent-based adhesive or a solventless adhesive. A solvent-based adhesive is an adhesive that is applied to an object, heated in an oven or the like to volatilize the solvent in the adhesive, and then bonded to another object. In the case of a two-component 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.

[0220] A solvent-free adhesive is an adhesive that is applied to an object and then bonded to another object without necessarily undergoing 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" includes cases where the solvent used as a reaction medium during the production 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.

[0221] 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 or solventless type. The two-component curing polyurethane adhesive will be described below.

[0222] A polyurethane adhesive, for example, has 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 curing agent include polyurethane, specifically polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, and acrylic polyurethane.

[0223] The polyol compound has two or more hydroxy 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 that an adhesive layer having an elastic modulus in the above-mentioned range can be easily obtained, 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.

[0224] Polyester polyurethane polyols are compounds having two or more hydroxy groups, two or more ester bonds, and two or more urethane bonds in one molecule, and have, for example, a polyester polyurethane structure as the main backbone. Polyester polyols are compounds having two or more hydroxy groups and two or more ester bonds in one molecule, and have, for example, a polyester structure as the main backbone. Polyether polyols are compounds having two or more hydroxy groups and two or more ether bonds in one molecule. Polycarbonate polyols are compounds having two or more hydroxy groups and two or more carbonate bonds in one molecule.

[0225] The weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the base agent of the two-component curing 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, and particularly preferably 20,000 or more, from the viewpoint of coatability, and is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 40,000 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 5.0 or less, more preferably 4.5 or less, even more preferably 4.0 or less, and preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more. Here, 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 a value converted into polystyrene.

[0226] 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, even more preferably 2,000 or more, from the viewpoint of coatability, and is preferably 10,000 or less, more preferably 8,000 or less, 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 preferably 1.2 or more, more preferably 1.5 or more, even more preferably 2.0 or more. Here, Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent.

[0227] 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, conventional, appropriate method.

[0228] 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., isocyanurates) derived from these compounds; and adducts, biuret compounds, and allophanate compounds obtained by reacting these compounds with low-molecular-weight active hydrogen compounds or alkylene oxide adducts thereof, or high-molecular-weight active hydrogen compounds.

[0229] 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, with trimethylolpropane being preferred. Examples of high molecular weight active hydrogen compounds include polyesters, polyether polyols, and polyamides.

[0230] The base agent containing a polyol compound and the curing agent containing a polyisocyanate compound are preferably used in an amount ratio such that the molar ratio (NCO / OH) of all isocyanate groups in the polyisocyanate compound to all hydroxy groups in 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 preferably 8.0 or less, more preferably 6.0, even more preferably 5.0 or less, and in the case of a solventless adhesive, 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.

[0231] <Sealant layer> The laminate of the present disclosure includes the above-described sealant film for laminates of the present disclosure as a sealant layer. This allows the laminate using the sealant film for laminates of the present disclosure as a sealant layer to have improved impact resistance after retort treatment.

[0232] By including random polypropylene and block polypropylene in the sealant layer (sealant film for laminates), it is possible to achieve, for example, a mono-material packaging container. Random polypropylene and block polypropylene are considered polypropylene in the calculation of the mono-material content rate. This eliminates the need to separate the substrate (first substrate, second substrate) and the sealant layer after collecting used packaging containers, improving the recyclability of the packaging containers.

[0233] The sealant layer may contain the above-mentioned additives, and may be subjected to the above-mentioned surface treatment.

[0234] <Adhesive Layer> In one embodiment, the laminate includes an adhesive layer between the substrate (first substrate) and the sealant layer. In one embodiment, the laminate includes a first adhesive layer between the first substrate and the second substrate. In one embodiment, the laminate includes a second adhesive layer between the second substrate and the sealant layer. This can improve the adhesion between the substrate and the sealant layer, the adhesion between the first substrate and the second substrate, and the adhesion between the second substrate and the sealant layer.

[0235] The adhesive layer is composed of an adhesive. The adhesive may be any of a one-component curing adhesive, a two-component curing adhesive, and a non-curing adhesive. The adhesive may be a solventless adhesive or a solvent-based adhesive. In one embodiment, the laminate of the present disclosure includes at least three elements: a polypropylene resin substrate, a barrier substrate, and a sealant layer. This allows the laminate to be produced using an adhesive without directly applying an adhesive onto the vapor-deposited film, and deterioration of the vapor-deposited film can be suppressed.

[0236] Examples of solvent-free adhesives, i.e., non-solvent laminate adhesives, include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and polyurethane adhesives. Among these, polyurethane adhesives are preferred, and two-component curing polyurethane adhesives are more preferred.

[0237] In one embodiment, the solventless adhesive is a two-component curing adhesive having a base agent and a curing agent. From the viewpoint of coatability, the weight average molecular weight (Mw) of the polymer component contained in the base agent is preferably 800 or more and 10,000 or less, more preferably 1,200 or more and 4,000 or less. The polydispersity (Mw / Mn) of the polymer component contained in the base agent is preferably 2.8 or less, more preferably 1.2 or more and 2.7 or less, even more preferably 1.5 or more and 2.6 or less, and particularly preferably 2.0 or more and 2.5 or less. Here, Mn is the number average molecular weight of the polymer component contained in the base agent. Each average molecular weight is measured by gel permeation chromatography (GPC) in accordance with JIS K7252-1 (2008) and is a value converted into polystyrene.

[0238] Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and polyurethane-based adhesives. Among these, polyurethane-based adhesives are preferred, and two-component curing polyurethane-based adhesives are more preferred.

[0239] In one embodiment, forming an adhesive layer using a solvent-free adhesive can further reduce, for example, the amount of residual solvent in the laminate, specifically the amount of residual organic solvent. The laminate of the present disclosure includes a polypropylene resin layer. Therefore, when producing a laminate of the present disclosure using a solvent-based adhesive, the drying temperature must be lowered compared to polyester-based laminates to prevent deterioration and thermal shrinkage of the laminate. In this case, the solvent in the adhesive may not be sufficiently volatilized and remain in the laminate, resulting in an odor due to the residual solvent. By using a solvent-free adhesive, the amount of residual solvent can be further reduced.

[0240] Examples of the organic solvent include 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.

[0241] In one embodiment, the use of a solvent-free adhesive allows, for example, a thinner adhesive layer than when a solvent-based adhesive is used. This allows for a higher polypropylene content in the entire laminate. Such a laminate is suitable for producing a mono-material packaging container.

[0242] The thickness of the adhesive layer is, for example, 0.1 μm to 10 μm, preferably 0.2 μm to 8 μm, and more preferably 0.5 μm to 6 μm. The thickness of the adhesive layer may be 2 μm or less.

[0243] The method for producing the laminate of the present disclosure is not particularly limited, and it can be produced using a conventionally known method such as a dry lamination method, a melt extrusion lamination method, a sand lamination method, etc. For example, in one embodiment, the laminate of the present disclosure may be produced by bonding a substrate and a sealant film, or a first substrate, a second substrate, and a sealant film, by a non-solvent lamination method using a solvent-free adhesive, or by a dry lamination method using a solvent-based adhesive.

[0244] A two-component curing polyurethane adhesive will be described below. A preferred polyurethane adhesive has a base agent containing a polyol compound such as polyester polyol and a curing agent containing an isocyanate compound. Examples of polyol compounds include polyester polyol, polyether polyol, polycarbonate polyol, and (meth)acrylic polyol. Among these, polyester polyol is preferred.

[0245] The polyester polyol has two or more hydroxyl groups per molecule. The polyester polyol has, for example, a polyester structure or a polyester polyurethane structure as a main skeleton. The polyester polyol can be obtained, for example, by a dehydration condensation reaction, transesterification, or ring-opening reaction between a polyhydric alcohol component and a polycarboxylic acid component.

[0246] Examples of the polyhydric alcohol component include diols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and cyclohexanedimethanol; and tri- or higher functional polyols such as glycerin, triethylolpropane, trimethylolpropane, pentaerythritol, and sorbitol.

[0247] Examples of polycarboxylic acid components include aliphatic polycarboxylic acids, alicyclic polycarboxylic acids, and aromatic polycarboxylic acids, as well as ester derivatives and acid anhydrides thereof. Examples of aliphatic polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, and dimer acid. Examples of alicyclic polycarboxylic acids include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Examples of aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid.

[0248] The polyester polyol may be pre-chain-lengthened with a polyisocyanate, if necessary. Examples of the polyisocyanate include diisocyanates such as 1,6-hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, m-xylylene diisocyanate, α,α,α'α'-tetramethyl-m-xylylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, and diphenylmethane diisocyanate; and biuret, nurate, or trimethylolpropane adducts of diisocyanates.

[0249] From the viewpoint of coatability, the weight average molecular weight (Mw) of the polyol compound such as polyester polyol is preferably 800 or more and 10,000 or less, more preferably 1,200 or more and 4,000 or less. The polydispersity (Mw / Mn) of the polyol compound such as polyester polyol is preferably 2.8 or less, more preferably 1.2 or more and 2.7 or less, even more preferably 1.5 or more and 2.6 or less, and particularly preferably 2.0 or more and 2.5 or less. Here, Mn is the number average molecular weight of the polyol compound. Each average molecular weight is measured by gel permeation chromatography (GPC) in accordance with JIS K7252-1 (2008) and is a value converted into polystyrene.

[0250] The isocyanate compound has two or more isocyanate groups in one molecule. Examples of the isocyanate compound include aromatic isocyanates and aliphatic isocyanates. The isocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known, conventional, appropriate method.

[0251] Examples of the isocyanate compound include diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, norbornene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, m-xylylene diisocyanate, hydrogenated xylylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, and α,α,α'α'-tetramethyl-m-xylylene diisocyanate; trimers of these diisocyanates; and adducts, biurets, and allophanates obtained by reacting these diisocyanate compounds with low-molecular-weight active hydrogen compounds or alkylene oxide adducts thereof, or high-molecular-weight active hydrogen compounds.

[0252] 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. Examples of high molecular weight active hydrogen compounds include polyesters, polyether polyols, and polyamides.

[0253] [Packaging Container] The laminate of the present disclosure can be suitably used for packaging material applications. The packaging material is used to produce a packaging container. The packaging material comprises the laminate of the present disclosure. The packaging container can be produced by using at least the packaging material comprising the laminate of the present disclosure.

[0254] The packaging container of the present disclosure includes the laminate of the present disclosure (hereinafter also simply referred to as "laminate"). Examples of the packaging container include a packaging container, a tube container, and a container with a lid. The container with a lid includes a container body having a storage portion and a lid material joined (heat sealed) to the container body so as to seal the storage portion.

[0255] In one embodiment, the packaging container of the present disclosure maintains its gas barrier properties and undergoes little deformation even after high-temperature treatment, making it suitable as a heat sterilization pouch or a microwave-safe packaging container. Here, a heat sterilization pouch refers to either a pouch that can be heat sterilized while containing contents, or a pouch that has been heat sterilized while containing contents. Also, a microwave-safe packaging container refers to a packaging container that can be heated using a microwave oven.

[0256] 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 "boil pouches"), and pouches that have been pasteurized (hereinafter "pasteurization pouches"). Retort pouches are packaging containers that have been filled with contents such as food or drink and sealed, and then subjected to heat sterilization treatment (pressure heat sterilization treatment) using water or steam at a temperature exceeding 100°C under pressure. Boil pouches and pasteurization pouches are packaging containers that have been filled with contents such as food or drink and sealed, and then subjected to boiling treatment at a temperature of 100°C or less.

[0257] In one embodiment, the packaging container of the present disclosure is a retort pouch. The conditions for the pressure and heat sterilization treatment can vary, but any pouch that has undergone a general pressure and heat sterilization treatment is included in the retort pouch. Among pressure and heat sterilization treatments, for example, a treatment temperature of 105°C or higher and 115°C or lower may be referred to as semi-retort treatment, a treatment temperature of higher than 115°C but lower than 130°C may be referred to as retort treatment, and a treatment temperature of higher than 135°C but lower than 140°C may be referred to as high-retort treatment. The retort treatment time is, for example, 5 minutes or longer and 60 minutes or shorter, preferably 15 minutes or longer and 40 minutes or shorter.

[0258] The oxygen permeability (unit: cc / m) of the retort pouch of the present disclosure ２ ·day·atm) is measured in accordance with JIS K7126-2:2006 at a temperature of 23°C and a relative humidity of 90% RH. The oxygen transmission rate of the retort pouch is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less. If the oxygen transmission rate of the retort pouch after pressure and heat sterilization is 3.0 or less, it can be suitably used as food packaging for long-term storage. The lower the lower limit of the oxygen transmission rate of the retort pouch, the better, but it may be, for example, 0.1.

[0259] Examples of heat sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0260] Examples of packaging containers include packaging containers of various types, such as a standing pouch type, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a palm seal type (pillow seal type), a pleated seal type, a flat bottom seal type, a square bottom seal type, and a gusset type.

[0261] The packaging container 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 container, and a half-cut line formed by laser processing or a cutter as a path for tearing the packaging container.

[0262] The packaging container may include a steam release mechanism that is configured to connect the inside and outside of the packaging container when the steam pressure inside the packaging container reaches or exceeds a predetermined value, thereby allowing the steam to escape and preventing the steam from escaping at locations other than the steam release mechanism.

[0263] The steam release mechanism includes, for example, a steam release seal portion that protrudes from the side seal portion toward the inside of the packaging container, and an unsealed portion that is isolated from the content storage portion by the steam release seal portion. The unsealed portion is in communication with the outside of the packaging container. The packaging container is filled with content and the opening is heat-sealed, and is heated using a microwave oven or the like. This increases the internal pressure, causing the steam release seal portion to peel. Steam passes through the peeled portion of the steam release seal portion and the unsealed portion and escapes to the outside of the packaging container.

[0264] In one embodiment, a packaging container can be produced by folding the laminate of the present disclosure in half and overlapping it so that the substrate is on the outside and the sealant layer is on the inside, and then heat-sealing the edges, etc. In another embodiment, a packaging container can be produced by overlapping multiple laminates of the present disclosure so that the sealant layers face each other, and then heat-sealing the edges, etc. The entire packaging container may be made of the laminate, or only a portion of the packaging container may be made of the laminate.

[0265] In one embodiment, the laminate of the present disclosure is used as a lid material in a lidded container. The lidded container comprises a container body having a storage section and a lid material joined (heat sealed) to the container body so as to seal the storage section. Here, the lid material, i.e., the sealant layer of the laminate, and the container body are heat sealed. Examples of the shape of the container body include a cup shape and a cylindrical shape with a bottom. The container body is made of, for example, polystyrene, polypropylene, polyethylene, or paper.

[0266] The contents contained in the packaging container may be, for example, liquids, solids, powders, and gels. The contents may be food or beverages, or non-food or beverages such as chemicals, cosmetics, and pharmaceuticals. After the contents are contained in the packaging container, the packaging container can be hermetically sealed by heat-sealing the opening of the packaging container. The contents may also be heat-sterilized foods (heat-sterilized foods such as retort foods, boiled foods, and pasteurized beverages). The packaging container of the present disclosure may be a pouch containing heat-sterilized foods.

[0267] As specific examples of packaging containers, sachets and stand-up pouches will be described below. Sachets are small packaging containers used to store contents, for example, between 1 g and 200 g. Contents that can be stored in sachets include, for example, sauces, soy sauce, dressings, ketchup, syrups, cooking alcohol, other liquid or viscous seasonings; liquid soups, powdered soups, fruit juices; spices; liquid beverages, jelly-like beverages, instant foods, and other foods and beverages.

[0268] 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 a 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; and creams.

[0269] 21 shows a packaging container 50 obtained by bonding two laminates together. The shaded areas indicate the heat-sealed areas. The packaging container 50 may have an easy-to-open portion 51. Examples of the easy-to-open portion 51 include a notch portion 52 that serves as a tearing starting point and a half-cut line 53 formed by laser processing or a cutter as a tearing path.

[0270] Figure 22 shows a simplified example of the configuration of a stand-up pouch. The shaded areas indicate the heat-sealed areas. In one embodiment, the stand-up 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 may be made of different materials. The bottom sheet 62 maintains the shape of the side sheets 61, thereby imparting self-supporting properties to the pouch and enabling it to become 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.

[0271] The standing pouch 60 may include a steam release mechanism 63. The steam release mechanism 63 includes a steam release seal portion 63a that protrudes from the side seal portion toward the inside of the packaging container, and a non-sealed portion 63b that is isolated from the content-accommodating portion by the steam release seal portion 63a. The non-sealed portion 63b communicates with the outside of the packaging container.

[0272] In a 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 of the present disclosure, or both the body portion and the bottom portion may be made of the laminate of the present disclosure.

[0273] In one embodiment, the side sheet can be formed by forming 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 laminates of the present disclosure, overlapping them so that the sealant layers face each other, and heat-sealing both side edges to form a bag.

[0274] In another embodiment, the side sheets can be formed by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, inserting two V-shaped laminates with the sealant layers facing outward between the laminates at the side edges on both sides of the overlapped laminates, and heat-sealing the laminates. This production method provides a stand-up pouch having a body with side gussets.

[0275] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower portions of the side sheets of a bag and heat sealing them. More specifically, the bottom sheet can be formed by inserting the laminate folded in a V shape with the sealant layer facing outward between the lower portions of the side sheets of a bag and heat sealing them.

[0276] In one embodiment, two of the above laminates are prepared and stacked together 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 between the two laminates 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 stand-up pouch of one embodiment can be formed.

[0277] [Mechanism of Action] When a laminate containing 80% by mass or more of a polypropylene-based single material (hereinafter referred to as a propylene-based laminate) is used as a packaging material, the propylene-based laminate is subjected to heat sterilization treatment such as retort treatment, boiling treatment, etc. Therefore, the propylene-based laminate is required to have drop impact resistance (impact resistance) that can withstand the impact when the pouch is dropped after heat treatment such as retort treatment, and hand-tearability (openability) that allows the laminate to be easily torn by hand after retort treatment.

[0278] Therefore, the inventors discovered that by reducing the polypropylene content by incorporating polyethylene and ethylene-propylene rubber while maintaining the polypropylene content at 40% by mass or more in the total amount of the sealant film, the elastic modulus of the sealant film can be reduced, thereby improving drop impact resistance. That is, by using a sealant film for laminates that contains 40% by mass or more of polypropylene, polyethylene, and ethylene-propylene rubber relative to the total amount of the sealant film and has a composite elastic modulus of 500 MPa or more and 900 MPa or less as measured by nanoindentation, the drop impact resistance (impact resistance) and hand tearability (openability) of the laminate can be improved.

[0279] The present disclosure relates to, for example, the following items [1] to

[11] . [1] A sealant film for use in a laminate in which a polypropylene content ratio relative to the total amount of resin materials is 80% by mass or more, the sealant film containing polypropylene, polyethylene, and ethylene-propylene rubber, the polypropylene content ratio relative to the total amount of the sealant film being 40% by mass or more, and the sealant film having a composite modulus of elasticity measured by a nanoindentation method of 500 MPa or more and 900 MPa or less. [2] The sealant film for a laminate according to item [1], in which the polyethylene content ratio relative to the total amount of the sealant film is 25% by mass or more and 40% by mass or less. [3] The sealant film for a laminate according to item [1] or [2], in which the ethylene-propylene rubber content ratio relative to the total amount of the sealant film is 5% by mass or more and 15% by mass or less. [5] The sealant film for laminates according to any one of [1] to [3], wherein the sealant film contains a propylene-ethylene elastomer or an ethylene-α-olefin elastomer. [5] The sealant film for laminates according to any one of [1] to [4], which, when used in the laminate, comprises at least a first layer located on one surface of the laminate and a second layer in contact with the first layer. [6] The sealant film for laminates according to [5], further comprises a third layer in contact with the second layer. [7] The sealant film for laminates according to any one of [1] to [6], having a thickness of 30 μm or more and 200 μm or less. [8] A laminate used in packaging materials, comprising one or more substrates and a sealant layer, wherein the sealant layer comprises the sealant film for laminates according to any one of [1] to [7], and wherein the polypropylene content relative to the total amount of resin materials is 80 mass% or more. [9] A packaging container comprising the laminate according to [8].

[10] The packaging container according to [9], which is a pouch for containing heat-sterilized food.

[11] A heat-sterilization pouch comprising the packaging container according to

[10] and heat-sterilized food contained in the packaging container.

[0280] The present disclosure relates to, as one embodiment, the following items [1A] to [11A]. [1A] A sealant film for use in a laminate having a polypropylene content of 80% by mass or more relative to the total amount of resin materials, wherein the sealant film contains 40% by mass or more of polypropylene relative to the total amount of the sealant film, and wherein the sealant film has a composite modulus of elasticity measured by a nanoindentation method of 500 MPa or more and 900 MPa or less. [2A] The sealant film for a laminate according to item [1A], wherein the sealant film contains polyethylene. [3A] The sealant film for a laminate according to item [1A] or [2A], wherein the sealant film contains an ethylene-propylene elastomer. [4A] The sealant film for a laminate according to any of items [1A] to [3A], wherein the sealant film contains a propylene-ethylene elastomer or an ethylene-α-olefin elastomer. [5A] The laminate sealant film according to any one of [1A] to [4A], which, when used in the laminate, comprises at least a first layer located on one surface of the laminate and a second layer in contact with the first layer. [6A] The laminate sealant film according to [5A], which further comprises a third layer in contact with the second layer. [7A] The laminate sealant film according to any one of [1A] to [6A], which has a thickness of 30 μm or more and 200 μm or less. [8A] A laminate used in packaging materials, which comprises at least a first substrate and a sealant layer, wherein the sealant layer is made of the laminate sealant film according to any one of [1A] to [7A], and wherein the polypropylene content relative to the total amount of resin material is 80 mass% or more. [9A] The laminate according to [8A], which further comprises a second substrate between the first substrate and the sealant layer. [10A] A packaging container comprising the laminate according to [8A] or [9A]. [11A] The packaging container according to [10A], which is a pouch for containing heat-sterilized food.

[0281] [Example 1] <Sealant film for laminate> (Sealant film 1) Resin composition 1 for the first layer containing 100% by mass of random PP, resin composition 2 for the second layer containing 85% by mass of block PP and 15% by mass of PE, and resin composition 3 for the third layer containing 100% by mass of random PP, each having the composition shown below, were simultaneously extruded through a multi-layer die to obtain an unstretched multi-layer film (hereinafter referred to as "sealant film 1") with first layer / second layer / third layer thicknesses of 5 μm / 50 μm / 5 μm.

[0282] [Polypropylene] Block PP: propylene-ethylene block copolymer (polymer part (a) consisting of homo-PP: 80%, polymer part (b) consisting of ethylene propylene rubber (EPR): 20%, MFR: 2.3 g / 10 min) Random PP: propylene-ethylene random copolymer (MFR: 6 g / 10 min, density: 0.890 g / cm ３ ) [Polyethylene] PE: Linear low-density polyethylene (MFR: 2.0 g / 10 min, density: 0.919 g / cm ３ ) [Thermoplastic elastomer] Elastomer: Propylene-α-olefin copolymer (melting point: 98°C, MFR (190°C): 3.0 g / 10 min, MFR (230°C): 7.0 g / 10 min)

[0283] (Sealant film 2) Resin composition 1 for the first layer containing 100% by mass of random PP having the composition shown above, resin composition 2' for the second layer containing 92.2% by mass of block PP and 7.8% by mass of PE, and resin composition 3 for the third layer containing 100% by mass of random PP were simultaneously extruded through a multilayer die to obtain an unstretched multilayer film (hereinafter referred to as "sealant film 2") having first layer / second layer / third layer thicknesses of 5 μm / 50 μm / 5 μm.

[0284] (Sealant Film 3) A resin composition containing 73% block PP and 27% block PE having the composition shown above was extruded to obtain an unstretched monolayer film having a thickness of 60 μm.

[0285] (Sealant Film 4) A resin composition containing 55% block PP, 35% PE, and 10% elastomer having the composition shown above was extruded to obtain an unstretched monolayer film having a thickness of 60 μm.

[0286] (Sealant Film 5) A resin composition containing 53% of block PP, 33% of PE, and 14% of elastomer having the composition shown above was extruded to obtain an unstretched monolayer film having a thickness of 60 μm.

[0287] (Sealant Film 6) A resin composition containing 30% block PP, 50% PE, and 20% elastomer having the composition shown above was extruded to obtain an unstretched monolayer film having a thickness of 60 μm.

[0288] (Sealant film 7) ZK99S (thickness: 60 μm) manufactured by Toray Film Processing Co., Ltd. was used.

[0289] <Barrier substrate> A hydroxyl group-containing (meth)acrylic resin (number average molecular weight: 25,000, glass transition temperature: 99°C, hydroxyl value: 80 mgKOH / g) was diluted with a mixed solvent of methyl ethyl ketone and ethyl acetate (mixing ratio 1:1) to a solids concentration of 10 mass% to prepare a base resin. An ethyl acetate solution containing tolylene diisocyanate (solids content 75 mass%) was added to the base resin as a curing agent to obtain a solution for forming a surface coating layer. The amount of curing agent used was 10 mass parts per 100 mass parts of the base resin.

[0290] A 20 μm thick biaxially stretched polypropylene film (ME-1, manufactured by Mitsui Chemicals Tocello Co., Ltd.) was prepared, one side of which had been corona-treated. The solution for forming the surface coating layer was applied to the corona-treated surface of the film and dried to form a surface coating layer with a thickness of 0.5 μm, thereby obtaining a resin substrate.

[0291] A carbon-containing silicon oxide (silica) vapor deposition film having a thickness of 12 nm was formed on the surface coating layer of the resin substrate by a roll-to-roll method using a low-temperature plasma chemical vapor deposition apparatus (CVD method) while applying tension to the resin substrate. The vapor deposition film formation conditions were as follows:

[0292] (Forming conditions) Hexamethyldisiloxane: oxygen gas: helium = 1:10:10 (unit: slm) Power supplied to cooling / electrode drum: 22 kW Line speed: 100 m / min

[0293] 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5 N hydrochloric acid were mixed to obtain a solution of pH 2.2. 175 g of tetraethoxysilane as a metal alkoxide and 9.2 g of glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed with this solution while cooling to 10 ° C to obtain Solution A. 14.7 g of polyvinyl alcohol with a saponification degree of 99% or more and a polymerization degree of 2400 as a water-soluble polymer, 324 g of water, and 17 g of isopropyl alcohol were mixed to obtain Solution B.

[0294] Solution A and solution B were mixed at a mass ratio (solution A:solution B) of 6.5:3.5 to obtain a barrier coating agent. The barrier coating agent was coated onto the vapor-deposited film formed on the resin substrate by spin coating, and then heat-treated in an oven at 80°C for 60 seconds to form a barrier coating layer with a thickness of 300 nm. In this manner, a barrier substrate was obtained.

[0295] <Preparation of Laminate> A 20 μm thick biaxially oriented polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello, Inc.) with one surface corona-treated was prepared as a first substrate. A printed layer with a coating thickness of 1 μm (when dried) was formed on the corona-treated surface of the first substrate by gravure roll coating. Next, a two-component curing polyurethane adhesive (RU-004 / H-1, manufactured by Rock Paint Co., Ltd.) was coated on the printed layer by gravure roll coating to a coating thickness of 4 μm (when dried), and the barrier substrate was dry-laminated so that the barrier coat layer surface of the barrier substrate was in contact with the adhesive layer surface.

[0296] The non-barrier coat layer surface of the barrier substrate used as the second substrate (intermediate substrate) was subjected to corona treatment, and then a two-component curing polyurethane adhesive (RU-004 / H-1, manufactured by Rock Paint Co., Ltd.) was coated to a coating thickness of 3.5 μm (when dried) using a gravure roll coating method, and sealant film 1 was dry laminated onto the adhesive layer surface with the third layer facing the adhesive layer surface.

[0297] In this way, a laminate with a thickness of approximately 109 μm was obtained. The laminate structure was biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film 1 (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0298] Example 2 A laminate with a thickness of approximately 109 μm was obtained in the same manner as in Example 1, except that Sealant Film 2 was used instead of Sealant Film 1. The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film 2 (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0299] Examples 3 to 5: Laminates with a thickness of approximately 109 μm were obtained in the same manner as in Example 1, except that single-layer sealant films 3 to 5 were used instead of sealant film 1. The laminate structure was biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant films 3 to 5 (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0300] Comparative Examples 1 and 2: A laminate approximately 109 μm thick was obtained in the same manner as in Example 1, except that single-layer sealant films 6 and 7 were used instead of sealant film 1. The laminate consisted of a biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant films 6 and 7 (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0301] [Composition Analysis of Sealant Films] The prepared sealant films 1 to 7 were subjected to CEF analysis and TGIC analysis under the conditions described below using a composition analyzer, and the content of each component was calculated. The analysis results are shown in Table 1. Furthermore, the measurement results for sealant film 4 are shown in Figure 23.

[0302] (Composition analysis equipment) ・Equipment: High-throughput composition distribution analyzer, CEF (Polymer Char) ・Detector (built-in): IR5 MCT infrared detector (Polymer Char) ・Detection wavelength: Methylene sensor CH2 νa 3.42 μm (2,920 cm -1 ) ; concentration Merrill sensor CH3 νa 3.38μm (2,960cm -1 ) composition (CEF analysis) Column: CEF column (Polymer Char), length 150 mm, volume 2.6 mL Mobile phase: o-Dichlorobenzene (ODCB) with BHT added Sample concentration: 16 mg / 8 mL Dissolution conditions: 150°C, 60 min (under N2 atmosphere) Sample filtration: 10 μm in-line filter Injection volume: 0.2 mL Temperature drop conditions: 95 → -17°C, 1.0°C / min, flow rate 0.012 mL / min Temperature rise conditions: -17 → 140°C, 4.0°C / min, flow rate 1.0 mL / min (TGIC analysis) Column: Porous graphite carbon column, Hypercarb high-temperature compatible (Thermo), inner diameter 4.6 mm, length 100 mm, particle size 5 μm Mobile phase: o-Dichlorobenzene (ODCB), BHT added. Sample concentration: 15 mg / 20 mL. Dissolution conditions: 145°C, 120 min. Sample filtration: 1.0 μm sintered filter. Injection volume: 0.2 mL. Temperature drop conditions: 140 → -20°C, 2.0°C / min, flow rate: 0.0 mL / min. Temperature rise conditions: -20 → 165°C, 2.0°C / min, flow rate: 0.5 mL / min.

[0303] [Composite Elastic Modulus of Sealant Film] The composite elastic modulus (E ｒ ) was measured based on the nanoindentation method using a nanoindenter (Bruker's "TI950 TriboIndenter"), with the cross section of the sealant layer as the measurement surface. A Berkovich indenter (triangular pyramid indenter; Berkovich_TI0039) was used as the indenter for the nanoindenter. Measurements were performed at five or more locations at the same measurement position (the location where the indenter was pressed) on the same cross section, and the composite elastic modulus E ｒ is the arithmetic mean value of the values ​​measured at five points, and is recorded for each measurement position.

[0304] The cross section was obtained by folding the prepared laminate into a V-shape with the sealant film side facing inward and heat-sealing it to a width of 130 mm and a height of 165 mm to prepare a bag-like pouch. 100 mL of water was filled into the resulting pouch through the opening, and the opening was heat-sealed. The pouch was then cut in the thickness direction of the laminate after hot water retort sterilization at a retort temperature of 121 ° C and a retort time of 30 minutes. The cross section was prepared by embedding the laminate in an embedding resin to prepare a block, and cutting the block at room temperature (23 ° C) using a commercially available rotary microtome. Finishing was performed with a diamond knife. The indenter was pressed into three locations in the thickness direction of the exposed cross section of the sealant layer: a position 2 μm inside the interface with the adhesive layer (top), near the center (center), and a position 2 μm inside the seal surface (bottom). The measurement conditions were a load control method (indentation load 30 μN, load 3 seconds / hold 5 seconds / unload 3 seconds), specifically as follows: the indenter was pressed into the sealant layer from the cross section of the sealant layer up to an indentation load of 30 μN over 3 seconds, and held in that state for 5 seconds. The load was then released over 3 seconds. This resulted in a maximum load P ｍａｘ , contact projection area A at maximum depth ｐ The load-displacement curves were obtained, and the composite elastic modulus was calculated from the obtained load-displacement curves. The measurements were carried out in a room temperature (23°C) environment. The results are shown in Table 1.

[0305] [Evaluation of Impact Resistance] <Drop Strength> The laminate obtained above was folded into a V shape with the sealant film side (first layer) facing inward, and heat-sealed to a width of 130 mm and a height of 165 mm to produce 10 pouch-like pouches. 150 mL of water was filled into the resulting pouches through the opening, and the opening was heat-sealed to seal. The sealed pouches were subjected to a hot water retort sterilization treatment at a retort temperature of 121°C for 30 minutes. After the retort treatment, the pouches were dropped 10 times horizontally from a height of 80 cm onto the floor (so that the body of the pouch hit the floor), and then dropped 10 times vertically from a height of 80 cm onto the floor (so that the bottom of the pouch hit the floor). The number of pouches that broke out of the 10 pouches was counted to evaluate impact resistance. The results are shown in Table 1.

[0306] <Evaluation criteria> ⊚: No breakage of bags. ○: No breakage of bags, but damage to the seal edge. (Multilayer structure) Breakage of the sealant layer was observed in the damaged area, but not in the core layer. (Single layer structure) Breakage of the sealant layer was not observed in the damaged area, and peeling was observed between the second substrate / sealant layer of the first substrate / second substrate / sealant layer of the laminate. ×: Three or more breakages of bags.

[0307] <Low-Temperature Drop Strength> The laminate obtained above was folded into a V shape with the sealant film side (first layer) facing inward, and heat-sealed to a width of 130 mm and a height of 165 mm to produce 30 bag-shaped pouches. 150 mL of water was filled into the resulting pouches through the opening, and the opening was heat-sealed to seal. The sealed pouches were subjected to a hot water retort sterilization treatment at a retort temperature of 121°C for 30 minutes. The pouches after retort sterilization were placed in a refrigerator at 5°C and stored for 1 day. The pouches removed from the refrigerator were dropped 10 times horizontally from a height of 80 cm onto the floor (so that the body of the pouch hit the floor), and then dropped 10 times vertically from a height of 80 cm onto the floor (so that the bottom of the pouch hit the floor). The number of pouches that broke out of the 30 pouches was counted to evaluate impact resistance. The results are shown in Table 1.

[0308] <Evaluation criteria> ◎: None of the 30 bags were broken. ○: None of the bags were broken, but 15 or more CPP bags were broken (the substrate remained unbroken). △: 1 to 5 bags were broken. ×: 15 or more bags were broken (not only the CPP but also the substrate was broken, causing water leakage).

[0309] [Evaluation of Opening Ease] The laminate obtained above was folded into a V shape with the sealant film side (first layer) facing inward, and heat-sealed to a width of 130 mm and a height of 165 mm to produce 10 bag-shaped pouches. At this time, the direction corresponding to the film flow direction (MD direction) was the 130 mm short side direction. 150 mL of water was filled into the obtained pouch through the opening, and the opening was heat-sealed to seal. The sealed pouches were subjected to a hot water retort sterilization treatment at a retort temperature of 121°C for 30 minutes. The retorted pouches were opened using a notch located 20 mm inside from the end in the direction perpendicular to the film flow direction (TD direction) to evaluate opening ease. The results are shown in Table 1.

[0310] <Evaluation criteria> ⊚: The entire 130 mm could be opened, and there was nothing particularly abnormal about the opened part. ○: The entire 130 mm could be opened, but the sealant film stretched and some wavy parts were observed in the opened part. ×: The CPP stretched, and there were three or more packages where the entire 130 mm could not be opened.

[0311]

[0312] 1: Laminate, 10: Stretched polypropylene substrate, 20: Barrier substrate, 22: Stretched polypropylene layer, 23: Surface coating layer, 24: Inorganic oxide layer, 25: Coating layer, 26: Surface resin layer, 27: Adhesive resin layer, 30: Sealant layer (sealant film for laminate), 40, 40A, 40B: Adhesive layers, 50: Packaging container, 51: Easy-open portion, 52: Notch portion, 53: Half-cut line, 60: Standing pouch, 61: Body portion (side sheet), 62: Bottom portion (bottom sheet), 63: Steam release mechanism, 63a: Steam release seal portion, 63b: Non-seal portion

Claims

1. A sealant film for laminates, the sealant film containing polypropylene in a proportion of 80% by mass or more relative to the total amount of resin material, the sealant film containing polypropylene, polyethylene, and ethylene-propylene rubber, the polypropylene content in the sealant film being 40% by mass or more relative to the total amount of the sealant film, and the sealant film having a composite elastic modulus of 500 MPa or more and 900 MPa or less, as measured by a nanoindentation method.

2. A sealant film for laminates as described in claim 1, wherein the content of said polyethylene in the total amount of said sealant film is 25% by mass or more and 40% by mass or less.

3. The sealant film for laminates according to claim 1, wherein the content of the ethylene-propylene rubber in the total amount of the sealant film is 5% by mass or more and 15% by mass or less.

4. The sealant film for laminates according to claim 1, wherein the sealant film comprises a propylene-ethylene elastomer or an ethylene-α-olefin elastomer.

5. A sealant film for laminates as described in claim 1, which, when used in the laminate, comprises at least a first layer located on one of the surfaces of the laminate, and a second layer in contact with the first layer.

6. The sealant film for laminates according to claim 5, further comprising a third layer in contact with the second layer.

7. The sealant film for laminates according to claim 1, having a thickness of 30 μm or more and 200 μm or less.

8. A laminate for use in packaging materials, comprising one or more substrates and a sealant layer, the sealant layer being made of the sealant film for laminates according to any one of claims 1 to 7, and the content of polypropylene relative to the total amount of resin material is 80 mass% or more.

9. A packaging container comprising the laminate according to claim 8.

10. The packaging container according to claim 9, which is a pouch for containing heat-sterilized food.

11. A heat sterilization pouch comprising the packaging container according to claim 10 and a heat sterilized food contained in the packaging container.

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