Sealant film for laminate, laminate, and packaging container

Abstract

Provided is a sealant film for a laminate excellent in heat resistance, low-temperature sealability and impact resistance, the sealant film used for a laminate having a polypropylene content of 80 mass% or more and comprising at least a first layer positioned on one surface of the laminate and a second layer in contact with the first layer. The first layer contains 51 mass%-90 mass% inclusive of a first matrix resin component and a first dispersion component, and has a sea-island structure in which the first dispersion component is dispersed in the first matrix resin component, the second layer contains 51 mass%-85 mass% inclusive of a second matrix resin component and a second dispersion component, and has a sea-island structure in which the second dispersion component is dispersed in the second matrix resin component, the first matrix resin component comprises a propylene-ethylene random copolymer, the first dispersion component contains 5 mass% or more of polyethylene, the second matrix resin component comprises a block polypropylene, and the second dispersion component contains 5 mass% or more of polyethylene.

Description

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

[0001] This application claims priority based on Japanese Patent Application No. 2023-139319, filed in Japan on August 29, 2023, the entire disclosures of which are incorporated herein by reference.

[0002] The present disclosure relates to a sealant film for a laminate, a laminate, and a packaging container.

[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] Incidentally, when a laminate is made into a packaging container such as a retort pouch, the laminate used for the packaging container is required to have heat resistance to withstand heat sterilization treatment. Furthermore, since the laminate is heat-sealed to form the packaging container, the laminate is required to be suitable for bag making, and the sealant film is required to have low-temperature sealing properties. Furthermore, the laminate used for a packaging container such as a retort pouch is required to have drop impact resistance (impact resistance) to withstand the impact of the pouch being dropped. However, the reality is that a laminate made of a single material such as polypropylene has not been sufficiently studied to satisfy these required properties.

[0007] One of the problems to be solved by the present disclosure is to provide a sealant film for laminates that has excellent heat resistance, low-temperature sealing properties, and impact resistance, and is suitable for laminates made of a single material such as polypropylene.

[0008] A sealant film for laminates according to the present disclosure is a sealant film for use in a laminate in which the polypropylene content relative to the total amount of resin material is 80% by mass or more, and when used in the laminate, the sealant film 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, wherein the first layer comprises a first matrix resin component and a first dispersed component in an amount of 51% by mass or more and 90% by mass or less, relative to the total amount of the first layer, and has a sea-island structure in which the first dispersed component is dispersed in the first matrix resin component, the second layer comprises a second matrix resin component and a second dispersed component in an amount of 51% by mass or more and 85% by mass or less, relative to the total amount of the second layer, and has a sea-island structure in which the second dispersed component is dispersed in the second matrix resin component, the first matrix resin component comprising a propylene-ethylene random copolymer, the first dispersed component comprising at least 5% by mass or more of polyethylene, relative to the total amount of the first layer, the second matrix resin component comprising a block polypropylene, and the second dispersed component comprising at least 5% by mass or more of polyethylene, relative to the total amount of the second layer.

[0009] According to the present disclosure, it is possible to provide a sealant film for laminates that has excellent heat resistance, low-temperature sealing properties, and impact resistance, 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.

[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 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.

[0014] [Laminate sealant film] The laminate sealant film of the present disclosure includes a first layer and a second layer. In one embodiment, the laminate sealant film may further include a third layer. The laminate sealant film of the present disclosure is a multilayer film having at least two layers. The laminate sealant film of the present disclosure is suitably used for a laminate in which the polypropylene content relative to the total amount of resin materials is 80% by mass or more.

[0015] 1 and 2 are schematic cross-sectional views showing one embodiment of a sealant film for laminates. The sealant film for laminates 30 shown in Fig. 1 has a two-layer structure, including a first layer 31 as a sealing layer and a second layer 32 as a core layer, in that 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.

[0016] 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.

[0017] (First Layer) The first layer includes a first matrix resin component and a first dispersed component. In one embodiment, the first layer has a so-called sea-island structure in which the first matrix resin component forms a sea component and the first dispersed component forms island components, with the island components dispersed in the sea component. The first layer constitutes a seal layer of the laminate sealant film of the present disclosure.

[0018] The first matrix resin component is made of a propylene-ethylene random copolymer, which is a random copolymer of 51% by mass or more and 90% by mass or less of propylene units as a 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.

[0019] The ethylene content of the propylene-ethylene random copolymer is preferably 1.0% by mass or more, more preferably 2.0% by mass or more. The ethylene content of the propylene-ethylene random copolymer 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 laminate 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 laminate sealant film of the present disclosure. The ethylene content of the propylene-ethylene random copolymer 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.

[0020] The melting point of the propylene-ethylene random copolymer is preferably 145°C or lower, more preferably 135°C or lower. When the melting point is equal to or lower than the upper limit, the low-temperature sealability of a laminate using the sealant film for laminates of the present disclosure is good, thereby improving the suitability for bag formation. The lower limit of the melting point of the propylene-ethylene random copolymer is preferably 120°C or higher. When the melting point is equal to or higher than the lower limit, when a laminate using the sealant film for laminates 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 temperatures 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).

[0021] The melt flow rate (MFR) of the propylene-ethylene random 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, and is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0022] Examples of methods for producing propylene-ethylene random copolymers include polymerizing raw materials such as propylene and ethylene using a catalyst, such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0023] The first dispersed component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the laminate sealant film of the present disclosure. The first layer has a sea-island structure in which polyethylene, the first dispersed component (island component), is dispersed in a propylene-ethylene random copolymer, the first matrix resin component (sea component), and therefore the drop impact resistance of a laminate using the laminate sealant film of the present disclosure can be improved.

[0024] 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 propylene-ethylene random copolymer, which is the sea component described above, and can enhance the impact resistance of the first layer. This makes it possible to suppress peeling between the first and second layers of the laminate sealant film due to discontinuity in impact resistance.

[0025] 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.

[0026] The density of the linear low density polyethylene is preferably 900 kg / m ３ More than 925kg / m ３or 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.

[0027] As the polyethylene, from the viewpoint of reducing the environmental load, biomass-derived polyethylene or mechanically recycled or chemically recycled polyethylene may be used.

[0028] 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.

[0029] 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.

[0030] 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 propylene-ethylene random copolymer, which is the first matrix resin component (sea component), can be further improved. This can further enhance the drop impact resistance of a laminate using the laminate sealant film of the present disclosure.

[0031] 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 propylene-ethylene random copolymer. Examples of the first elastomer include a propylene-ethylene copolymer (propylene-ethylene elastomer) and an ethylene-α-olefin copolymer (ethylene-α-olefin elastomer).

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] In the first layer, the content of the first matrix resin component is 51% by mass or more, preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 85% 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.

[0037] 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. When the content of the first dispersion component in the first layer is equal to or greater than the lower limit, for example, the impact resistance of a laminate using the laminate 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, for example, the low-temperature sealability of a laminate using the laminate sealant film of the present disclosure can be further improved.

[0038] The polyethylene content in the first layer is 5% by mass or more, preferably 8% by mass or more, and more preferably 13% by mass or more, relative to the total amount of the first layer. The polyethylene content in the first layer is, for example, 15% 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 laminate sealant film of the present disclosure can be further improved. When the polyethylene content is equal to or less than the upper limit, the low-temperature sealability of a laminate using the laminate sealant film of the present disclosure can be further improved.

[0039] 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, 12% 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 sealant film for laminates 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 low-temperature sealability of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0040] 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 sealant film for laminates of the present disclosure can be further improved.

[0041] 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 sealant film for laminates 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 sealant film for laminates of the present disclosure can be further improved.

[0042] (Second Layer) The second layer includes a second matrix resin component and a second dispersed component. In one embodiment, the second layer has a so-called sea-island structure in which the second matrix resin component forms a sea component and the second dispersed component forms island components, with the island components dispersed in the sea component. The second layer constitutes the core layer of the laminate sealant film of the present disclosure.

[0043] The second matrix resin component is made of block polypropylene (block PP). Block polypropylene (propylene block copolymer) is a copolymer containing at least a propylene homopolymer (homopolypropylene) and a block elastomer. Examples of block polypropylene include propylene-ethylene block copolymers.

[0044] 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. In one embodiment, the propylene-ethylene block copolymer includes a sea portion made of a propylene polymer and an island portion made of polyethylene and an ethylene-propylene copolymer rubber component. The polymer portion (a) and the sea portion 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 portion 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 portion to the island portion.

[0045] 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.

[0046] 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 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.

[0047] 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.

[0048] 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%.

[0049] 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%.

[0050] 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.

[0051] 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.

[0052] The second dispersed component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the laminate sealant film of the present disclosure. The second layer 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, the second layer has a sea-island structure in which a polymer component (b) made of an ethylene-propylene copolymer rubber component and polyethylene that is the second dispersed component are dispersed in a polymer component (a) made of a propylene polymer, and therefore the drop impact resistance of a laminate using the laminate sealant film of the present disclosure can be further improved.

[0053] The polyethylene may be the same as the first dispersion component of the first layer.

[0054] 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 improve the drop impact resistance of a laminate using the laminate sealant film of the present disclosure.

[0055] The second elastomer may be the same thermoplastic elastomer as the first dispersed component of the first layer.

[0056] In the second layer, the content of the second matrix resin component is 51% by mass or more, preferably 70% by mass or more, and more preferably 75% 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 85% by mass or less, based on the total amount of the second layer.

[0057] In the second layer, the content of the second dispersion component is preferably 15% by mass or more, more preferably 20% 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 45% 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, for example, the impact resistance of a laminate using the laminate 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, for example, the heat resistance of a laminate using the laminate sealant film of the present disclosure can be further improved.

[0058] The polyethylene content in the second layer is 5% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more, relative to the total amount of the second layer. The polyethylene content in the second layer is, for example, 30% 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 laminate 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 laminate sealant film of the present disclosure can be further improved.

[0059] In the second layer, the content of the second elastomer is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% 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, 20% 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 sealant film for laminates 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 sealant film for laminates of the present disclosure can be further improved.

[0060] 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 sealant film for laminates of the present disclosure can be further improved.

[0061] 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 laminate 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 laminate sealant film of the present disclosure can be further improved.

[0062] (Third Layer) The third layer includes a third matrix resin component and a third dispersed component. In one embodiment, the third layer 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 a surface layer of the laminate sealant film of the present disclosure.

[0063] The third matrix resin component is made of block polypropylene (block PP). As the block polypropylene, the same block polypropylene as the second matrix resin component of the second layer can be used.

[0064] The third dispersed component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the laminate 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), and therefore the drop impact resistance of a laminate using the laminate sealant film of the present disclosure can be improved.

[0065] As the polyethylene, the same polyethylene as that used for the first and second layers can be used.

[0066] The third dispersion component may further contain a third elastomer. By including the third elastomer in the third dispersion component, 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 improve the drop impact resistance of a laminate using the laminate sealant film of the present disclosure.

[0067] The third elastomer may be the same thermoplastic elastomer as that used for the first and second layers.

[0068] 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.

[0069] 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.

[0070] 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 sealant film for laminates 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 sealant film for laminates of the present disclosure can be further improved.

[0071] (Sealant Film) In the sealant film for laminates of the present disclosure, the polyethylenes used in the first, second, and third layers may all be the same type of polyethylene, or different types of polyethylene may be used for each. Similarly, in the sealant film, the first, second, and third layers may all be the same type of thermoplastic elastomer, or different types of thermoplastic elastomer may be used for each.

[0072] In the laminate 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 laminate 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.

[0073] In the laminate 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 laminate sealant film satisfying the above relationship, the heat resistance and impact resistance attributable to the second layer can be further improved.

[0074] In the laminate sealant film of the present disclosure, the content of the polyethylene and the first to third elastomers (thermoplastic elastomers) relative to the total amount of the sealant film is preferably 15% by mass or more, more preferably 20% by mass or more. The content is preferably 40% by mass or less, more preferably 30% by mass or less. When the content is within the above range, for example, the impact resistance of a laminate using the laminate sealant film of the present disclosure can be further improved.

[0075] The thickness of the sealant film for laminates of the present disclosure is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more. Furthermore, the thickness of the sealant film for laminates 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 the laminate 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.

[0076] The sealant film for laminates of the present disclosure can be produced, for example, by 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 performed 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, and the extruded film is rapidly cooled and solidified on a rotating cooling drum or the like, thereby forming a sealant film.

[0077] 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.

[0078] From the viewpoint of heat sealing properties, the sealant film for laminates of the present disclosure is preferably an unstretched resin film. The resin film can be produced by, for example, a casting method, a T-die method, or an inflation method.

[0079] [Laminate] The laminate of the present disclosure comprises a substrate (first substrate) and a sealant layer. The substrate comprises a polypropylene resin layer that has been subjected to a stretching treatment. In one embodiment, the substrate is a barrier substrate comprising a polypropylene resin layer that has been subjected to a stretching treatment and a vapor-deposited film. The barrier substrate may further comprise a layer described below. In one embodiment, the substrate is made of a polypropylene resin layer that has been subjected to a stretching treatment. That is, in one embodiment, the substrate is a polypropylene resin substrate that has been subjected to a stretching treatment.

[0080] In the following description, the terms "polypropylene resin layer" and "polypropylene resin substrate" mean "a polypropylene resin layer that has been subjected to a stretching treatment" and "a polypropylene resin substrate that has been subjected to a stretching treatment", respectively, except when describing a stretching treatment. The laminate of the present disclosure is suitable for use as a packaging material.

[0081] The laminate of the present disclosure may include 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. The first substrate and the second substrate are each independently a barrier substrate or a polypropylene resin substrate.

[0082] 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 a polypropylene resin 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 a polypropylene resin substrate.

[0083] 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 a polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the barrier substrate 20 is arranged such that the polypropylene resin layer 22 constitutes the outermost layer of the laminate 1, and the vapor-deposited film 24 faces the adhesive layer 40. Here, the vapor-deposited film 24 and the adhesive layer 40 may be in contact with each other.

[0084] 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 polypropylene resin layer 22 and the vapor-deposited film 24 .

[0085] FIG. 5 is similar to FIG. 3 except that the barrier substrate 20 includes a polypropylene resin layer 22, a surface coating layer 23 or a surface resin layer 26, a vapor-deposited film 24, and a barrier coating layer 25 in this order in the thickness direction. In this example, the barrier substrate 20 is disposed so that the barrier coating layer 25 faces the adhesive layer 40. The barrier coating layer 25 and the adhesive layer 40 may be in contact with each other. FIG. 6 is similar to 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 similar to FIG. 5 except that the barrier substrate 20 includes a polypropylene resin layer 22, a vapor-deposited film 24, and a barrier coating layer 25 in this order in the thickness direction. FIG. 8 is similar to 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.

[0086] The laminate 1 shown in Fig. 9 comprises, in this order in the thickness direction, a polypropylene resin 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 polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the barrier substrate 20 is arranged so that the polypropylene resin layer 22 is in contact with the adhesive layer 40B and the vapor-deposited film 24 faces the adhesive layer 40A. The vapor-deposited film 24 and the adhesive layer 40A may be in contact with each other.

[0087] 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 polypropylene resin layer 22 and the vapor-deposited film 24 .

[0088] FIG. 11 is similar to FIG. 9 except that the barrier substrate 20 includes a polypropylene resin layer 22, a surface coating layer 23 or a surface resin layer 26, a vapor-deposited film 24, and a barrier coating layer 25 in this order in the thickness direction. In this example, the barrier substrate 20 is disposed so that the barrier coating layer 25 faces the adhesive layer 40A. The barrier 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, a vapor-deposited film 24, and a barrier 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.

[0089] 15 includes, in this order in the thickness direction, a barrier substrate 20 as a first substrate, an adhesive layer 40A, a polypropylene resin substrate 10 as a second substrate, an adhesive layer 40B, and a sealant layer 30. The barrier substrate 20 includes a polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the barrier substrate 20 is arranged such that the polypropylene resin layer 22 constitutes the outermost layer of the laminate 1, and the vapor-deposited film 24 faces the adhesive layer 40A. The vapor-deposited film 24 and the adhesive layer 40A may be in contact with each other.

[0090] 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 polypropylene resin layer 22 and the vapor-deposited film 24 .

[0091] FIG. 17 is similar to FIG. 15 , except that the barrier substrate 20 includes a polypropylene resin layer 22, a surface coating layer 23 or a surface resin layer 26, a vapor-deposited film 24, and a barrier coating layer 25 in this order in the thickness direction. In this example, the barrier substrate 20 is disposed so that the barrier coating layer 25 faces the adhesive layer 40A. The barrier coating layer 25 and the adhesive layer 40A 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, a vapor-deposited film 24, and a barrier 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.

[0092] 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 polypropylene resin substrate that has been subjected to a stretching treatment. (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

[0093] 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, which can further improve gas barrier properties (particularly oxygen barrier properties and water vapor barrier properties).

[0094] When the first substrate is a barrier substrate, in one embodiment, the first substrate is arranged so that the vapor-deposited film faces the sealant layer side and the polypropylene resin layer faces the side opposite to the sealant layer.

[0095] When the second substrate is a barrier substrate, in one embodiment, the second substrate is arranged so that the vapor-deposited film faces the first substrate side and the polypropylene resin layer faces the sealant layer side, or the second substrate is arranged so that the vapor-deposited film faces the sealant layer side and the polypropylene resin layer faces the first substrate side. Among these, when the second substrate is a barrier substrate, from the viewpoint of further suppressing deterioration of the vapor-deposited film, it is preferable that the second substrate is arranged so that the vapor-deposited film faces the first substrate side and the polypropylene resin layer faces the sealant layer side.

[0096] In one embodiment of the laminate of the present disclosure, the first substrate is a polypropylene resin substrate, and the second substrate is a barrier substrate (see Figures 9 to 14). In this embodiment, the laminate comprises a polypropylene resin substrate, a barrier substrate, and a sealant layer, in this order in the thickness direction. A laminate with such a configuration adequately protects the vapor-deposited film 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.

[0097] 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.

[0098] 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.

[0099] <Barrier Substrate> The barrier substrate comprises a polypropylene resin layer and a vapor-deposited film. In one embodiment, the barrier substrate comprises a polypropylene resin layer and a vapor-deposited film provided on one surface of the resin layer. The polypropylene resin layer is a layer that has been subjected to a stretching treatment. The barrier substrate may comprise a surface coating layer or a surface resin layer between the polypropylene resin layer and the vapor-deposited film. The barrier substrate may comprise a barrier coating layer on the vapor-deposited film.

[0100] (Polypropylene Resin Layer) The polypropylene resin layer contains polypropylene as a main component, i.e., more than 50 mass % of polypropylene. By providing the barrier substrate with the polypropylene resin layer, for example, it is possible to improve the oil resistance of a packaging container produced using the barrier substrate.

[0101] The polypropylene may be any of a propylene homopolymer, a propylene random copolymer, and a propylene block copolymer, or may be a mixture of two or more selected from these.

[0102] A propylene homopolymer is a polymer of propylene only. A propylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene. A propylene block copolymer is a copolymer having a polymer block made of propylene and a polymer block made of at least an α-olefin other than propylene. The polymer block made of at least an α-olefin other than propylene may be a polymer block made of propylene and an α-olefin other than propylene.

[0103] Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms, and specific examples 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.

[0104] Among polypropylenes, it is preferable to use a random copolymer from the viewpoint of transparency. When the rigidity and heat resistance of the packaging container are important, it is preferable to use a homopolymer. When the drop impact resistance of the packaging container is important, it is preferable to use a block copolymer.

[0105] In one embodiment, the melt flow rate (MFR) of the polypropylene may be 0.1 g / 10 min or more and 50 g / 10 min or less, or 0.3 g / 10 min or more and 30 g / 10 min or less, from the viewpoint of film-forming ability and processability. The MFR of the polypropylene is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0106] As the polypropylene, from the viewpoint of reducing the environmental load, biomass-derived polypropylene or mechanically recycled or chemically recycled polypropylene may be used.

[0107] The polypropylene content in the polypropylene resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0108] The polypropylene resin layer may contain a resin material other than polypropylene, such as polyolefins such as polyethylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins.

[0109] The polypropylene resin layer may contain additives such as crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0110] The polypropylene resin layer is a layer that has been subjected to a stretching treatment. This can improve, for example, the heat resistance, drop impact resistance, water resistance, and dimensional stability of the laminate. A laminate having such a resin layer is suitable, for example, as a packaging material for constituting a packaging container that is subjected to a boiling treatment or a retort treatment. The stretching treatment may be uniaxial or biaxial.

[0111] The stretching ratio when stretching in the machine direction (machine direction, MD direction of the substrate) is preferably 2 to 15, more preferably 5 to 13. The stretching ratio when stretching in the transverse direction (direction perpendicular to the MD, TD direction) is preferably 2 to 15, more preferably 5 to 13. By setting the stretching ratio to 2 or more, the strength and heat resistance of the polypropylene resin layer can be further improved, and the printability of the polypropylene resin layer can be improved. From the viewpoint of the breaking limit of the polypropylene resin layer, the stretching ratio is preferably 15 or less.

[0112] In one embodiment, the polypropylene resin layer may be subjected to a surface treatment. This can improve, for example, the adhesion between the polypropylene resin layer and other layers. 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, as well as chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the polypropylene resin layer.

[0113] The polypropylene resin layer may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin layer is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved.

[0114] (Surface Coating Layer) In one embodiment, the barrier substrate includes a surface coating layer containing a resin material having a polar group between the polypropylene resin layer and the vapor-deposited film. By providing a surface coating layer containing a resin material having a polar group, it is possible to improve the adhesion of the vapor-deposited film formed on the surface coating layer and also improve the gas barrier properties.

[0115] In this embodiment, the barrier substrate comprises a resin substrate having a polypropylene resin layer and a surface coating layer, and a vapor-deposited film provided on the surface coating layer, the polypropylene resin layer, the surface coating layer, and the vapor-deposited film being arranged in this order in the thickness direction of the barrier substrate.

[0116] 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, from the viewpoint of lamination properties of the packaging container, 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.

[0117] Examples of resin materials having a polar group include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl group-containing (meth)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 (meth)acrylic resin, polyamide, and polyurethane are more preferred.

[0118] 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 (meth)acrylic resin-based emulsions and polyester-based emulsions.

[0119] 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 a resin material other than the resin material having a polar group. The surface coating layer may contain the above-mentioned additives.

[0120] The ratio of the thickness of the surface coating layer to the total thickness of the resin substrate having the polypropylene resin layer and the surface coating layer is preferably 0.08% or more and 20% or less, more preferably 0.2% or more and 15% or less, even more preferably 1% or more and 10% or less, and even more preferably 1% or more and 5% or less. When this ratio is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When this ratio is equal to or less than the upper limit, for example, the processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0121] The thickness of the surface coating layer is preferably 0.02 μm to 10 μm, more preferably 0.05 μm to 10 μm, even more preferably 0.1 μm to 10 μm, and even more preferably 0.2 μm to 5 μm. When the thickness is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0122] For example, a resin film is obtained by forming polypropylene or a resin composition containing polypropylene into a film using a T-die method, an inflation method, or the like, and then the resin film is stretched. A coating liquid for forming a surface coating layer is applied to the stretched resin film and dried, thereby producing a resin substrate having a polypropylene resin layer and a surface coating layer.

[0123] (Surface Resin Layer) In one embodiment, the barrier substrate includes a surface resin layer between the polypropylene resin layer and the vapor-deposited film, the surface resin layer containing 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, it is possible to improve the adhesion of the vapor-deposited film formed on the surface resin layer and also improve gas barrier properties. Furthermore, a packaging bag produced using a laminate including the surface resin layer has high lamination strength.

[0124] 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. In this embodiment, the barrier substrate comprises a resin substrate having a polypropylene resin layer and a surface resin layer, and a vapor-deposited film provided on the surface resin layer. This barrier substrate comprises a polypropylene resin layer, a surface resin layer, and a vapor-deposited film, in this order in the thickness direction.

[0125] 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 vapor-deposited film can be further improved, the gas barrier property can be further improved, and the laminate strength of the packaging container can be further improved.

[0126] 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 resin substrate.

[0127] 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 using differential scanning calorimetry (DSC) at a temperature rise rate of 10°C / min.

[0128] 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 bag 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.

[0129] 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 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, from the viewpoint of the gas barrier property and laminate strength of the packaging container, a hydroxyl group, an ester group, an amino group, an amide group, a carboxyl group, and a carbonyl group are preferred, and an amide group is more preferred.

[0130] The high-melting-point resin material may have a melting point of 180°C or higher, and examples thereof include polyolefins, vinyl resins, (meth)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.

[0131] 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.

[0132] 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.

[0133] The surface resin layer may contain a resin material other than the high-melting-point resin material. The surface resin layer may contain the above-mentioned additives. The surface resin layer may be subjected to the above-mentioned surface treatment.

[0134] The ratio of the thickness of the surface resin layer to the total thickness of the resin substrate having the polypropylene resin layer and the surface resin layer is preferably 1% to 10%, more preferably 1% to 5%. When this ratio is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When this ratio is equal to or less than the upper limit, for example, the film-forming ability and processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0135] The thickness of the surface resin layer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.1 μm or more and 4 μm or less. When the thickness is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When the thickness is equal to or less than the upper limit, for example, the film-forming property and processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0136] In one embodiment, the resin substrate may include an adhesive resin layer between the polypropylene resin layer and the surface resin layer, thereby improving adhesion between these layers.

[0137] The adhesive resin layer can be formed, for example, by 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 packaging container, polyolefin and its acid-modified product are preferred, and polypropylene and its acid-modified product are more preferred. As the polypropylene used for the adhesive resin layer, commercially available products can be used, for example, the Admer series manufactured by Mitsui Chemicals, Inc. can be used.

[0138] The thickness of the adhesive resin layer is, for example, 1 μm or more and 15 μm or less. When the thickness is 1 μm or more, for example, the adhesion between the polypropylene resin layer and the surface resin layer can be further improved. When the thickness is 15 μm or less, for example, the processability of the resin substrate can be further improved.

[0139] In one embodiment, the resin substrate having a polypropylene resin layer and, if necessary, an adhesive resin layer and a surface resin layer is a coextruded stretched resin film. The coextruded stretched resin film can be produced, for example, by forming a laminated film using a T-die method or an inflation method, and then stretching the laminated film. By forming the film using the inflation method, the laminated film may be stretched simultaneously.

[0140] The stretching treatment may be uniaxial stretching or biaxial stretching. When stretching in the MD direction, the stretching ratio is preferably 2 to 15 times, more preferably 5 to 13 times. When stretching in the TD direction, the stretching ratio is preferably 2 to 15 times, more preferably 5 to 13 times.

[0141] (Vapor-deposited film) In one embodiment, the barrier substrate has a vapor-deposited film made of an inorganic oxide. In one embodiment, the barrier substrate has a vapor-deposited film on the surface coating layer or the surface resin layer. This can improve the gas barrier properties of the laminate, specifically the oxygen barrier properties and water vapor barrier properties. A packaging container made using the laminate can suppress weight loss of the contents filled in the packaging container.

[0142] 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.

[0143] In one embodiment, silica is more preferable as the inorganic oxide because it does not require aging treatment after forming the vapor-deposited film. In one embodiment, carbon-containing silicon oxide is more preferable as the inorganic oxide because it can suppress deterioration in gas barrier properties even when the laminate is bent.

[0144] The thickness of the vapor-deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less. When the thickness is equal to or greater than the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the occurrence of cracks in the vapor-deposited film can be suppressed and the recyclability of the packaging container can be improved.

[0145] The surface of the vapor-deposited film is preferably subjected to the above-mentioned surface treatment, which can improve the adhesion between the vapor-deposited film and the adjacent layer.

[0146] Examples of methods for forming a vapor-deposited 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.

[0147] The vapor-deposited film 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 vapor-deposited film is a multilayer film, 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.

[0148] The vapor-deposited film in the barrier substrate 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, which can prevent a decrease in gas barrier properties even when the laminate is bent.

[0149] 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 content C is preferably 3% or more and 50% or less, more preferably 5% or more and 40% or less, and even more preferably 10% or more and 35% or less, relative to the total of the three elements silicon, oxygen, and carbon (100%). By setting the carbon content 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 content of each element is on a molar basis.

[0150] In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the silicon ratio Si is preferably 1% to 45%, more preferably 3% to 38%, and even more preferably 8% to 33%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. The oxygen ratio O is preferably 10% to 70%, more preferably 20% to 65%, and even more preferably 25% to 60%, 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 in gas barrier properties can be further suppressed even when the laminate is bent.

[0151] 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.

[0152] The proportions C, Si, and O in the carbon-containing silicon oxide vapor-deposited film can be measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the following measurement conditions.

[0153] (Measurement conditions) Equipment 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): approx. 6 mmφ Photoelectron capture 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, and the spectrum was collected.

[0154] (Barrier Coat Layer) In one embodiment, the barrier substrate may further include a barrier coat layer on the vapor-deposited film. That is, the barrier substrate may further include a barrier coat layer on the surface of the vapor-deposited film opposite to the surface on the polypropylene resin layer side. This can improve, for example, the oxygen barrier property and water vapor barrier property of the laminate.

[0155] In one embodiment, the barrier coat layer contains a gas barrier resin. Examples of gas barrier resins include ethylene-vinyl alcohol copolymers, polyvinyl alcohol, polyacrylonitrile, polyesters, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, polyurethanes, and (meth)acrylic resins. Among these, polyvinyl alcohol is preferred from the viewpoints 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 vapor-deposited film can be effectively prevented.

[0156] 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 configuration can improve the gas barrier properties of the barrier coat layer, for example. The barrier coat layer may contain the above-mentioned additives.

[0157] The thickness of the barrier coat layer containing the gas barrier resin is preferably 0.01 μm or more and 10 μm or less, more preferably 0.1 μm or more and 5 μm or less. By making the thickness of the barrier coat layer 0.01 μm or more, for example, the gas barrier property can be further improved. By making the thickness of the barrier coat layer 10 μm or less, for example, the processability of the laminate and the recyclability of the packaging container can be improved. Furthermore, as long as the thickness of the barrier coat layer is within the above range, recyclability is not impaired even if the gas barrier resin is a resin material other than polypropylene.

[0158] The barrier coat layer can be formed, for example, by applying and drying a coating liquid obtained by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent.

[0159] In another embodiment, the barrier coat layer is a gas barrier coating film formed by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, and optionally adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, which is then applied to a vapor-deposited film and dried. 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 barrier coat layer on the vapor-deposited film, the occurrence of cracks in the vapor-deposited film can be effectively suppressed.

[0160] 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 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.

[0161] R １ and R ２ Examples 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.

[0162] Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0163] 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 and 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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

[0168] 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.

[0169] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butyl alcohol.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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 a vapor-deposited film 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.

[0174] 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 vapor-deposited film, and improve the recyclability of the packaging container, for example.

[0175] <Polypropylene resin substrate> The polypropylene resin substrate is composed of the above-described polypropylene resin layer. The polypropylene resin substrate is a substrate that has been subjected to a stretching treatment. Details of the polypropylene resin layer and the stretching treatment are as described above, and detailed description thereof will be omitted here.

[0176] The polypropylene resin substrate may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin substrate is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved.

[0177] (Printed Layer) The laminate of the present disclosure may have a printed layer on the surface of a substrate such as a barrier substrate or a polypropylene resin substrate. The image formed on the printed layer is not particularly limited, and may represent letters, patterns, symbols, or combinations thereof. The printed layer may also be formed using ink derived from biomass. This can further reduce the environmental impact.

[0178] 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.

[0179] The thickness of the printing layer is, for example, 0.5 μm or more and 3 μm or less.

[0180] <Sealant Layer> The laminate of the present disclosure includes the above-described sealant film for laminates of the present disclosure as a sealant layer, which can improve, for example, the heat resistance, low-temperature sealability, and impact resistance of the laminate.

[0181] The sealant layer (sealant film for laminates) contains a propylene-ethylene random copolymer in a first layer at 51% by mass or more, and a block polypropylene (propylene-ethylene block copolymer) in each of the second and third layers at 51% by mass or more.

[0182] By using a propylene-ethylene random copolymer in the first layer, for example, the low-temperature sealability of the sealant layer, and therefore the laminate, can be improved. Furthermore, by using a block polypropylene (propylene-ethylene block copolymer) in the second and third layers, for example, the heat resistance and impact resistance (drop impact resistance) of the sealant layer, and therefore the laminate, can be improved. This improves the bag-making suitability when producing a packaging container using the laminate, and also reduces damage to the packaging container due to impact when dropped.

[0183] By including a propylene-ethylene random copolymer and a propylene-ethylene block copolymer as the main components in the sealant layer (sealant film for laminates), it is possible to achieve, for example, a mono-material packaging container. The propylene-ethylene random copolymer and the propylene-ethylene block copolymer are considered to be polypropylene in the calculation of the mono-material content rate. This eliminates the need to separate the substrates (first substrate, second substrate) and the sealant layer after collecting used packaging containers, thereby improving the recyclability of the packaging containers.

[0184] The sealant layer may contain the above-mentioned additives, and may be subjected to the above-mentioned surface treatment.

[0185] <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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] [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.

[0205] A packaging container according to the present disclosure includes the laminate (hereinafter simply referred to as "laminate") according to the present disclosure. Examples of packaging containers include packaging bags, tube containers, and containers with lids. The containers with lids include a container body having a storage section and a lid joined (heat sealed) to the container body so as to seal the storage section.

[0206] In one embodiment, the packaging container of the present disclosure maintains gas barrier properties even when subjected to high-temperature treatment and exhibits minimal deformation, making it suitable as a microwave oven container or a boiling or retort container. The packaging container of the present disclosure is also suitable as a microwave boiling or retort container. The packaging container of the present disclosure is particularly suitable as a boiling or retort pouch.

[0207] Examples of heat sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0208] Examples of packaging bags include packaging bags 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] In one embodiment, a packaging bag can be produced by folding the laminate of the present disclosure in half and overlapping them 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 bag 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 bag may be made of the above-mentioned laminate, or only a portion of the packaging bag may be made of the above-mentioned laminate.

[0213] 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.

[0214] The contents to be contained in the packaging container include, 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 opening of the packaging container can be heat-sealed to seal the packaging container.

[0215] As specific examples of packaging bags, sachets and stand-up pouches will be described below. Sachets are small packaging bags used to hold contents of, for example, 1 g to 200 g. Examples of contents that can be held in sachets include sauces, soy sauce, dressings, ketchup, syrup, 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.

[0216] 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.

[0217] 21 shows a packaging bag 50 obtained by bonding two laminates together. The hatched areas indicate the heat-sealed areas. The packaging bag 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.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] [Mechanism of Action] In a laminate (hereinafter referred to as a propylene-based laminate) containing 80% or more of a single polypropylene-based material, the first substrate is a stretched polypropylene resin substrate, which has poorer heat resistance than a substrate using PET. For example, the first substrate of the propylene-based laminate is easily deformed in response to temperature changes. For example, the first substrate of the propylene-based laminate is easily stretched during transport and easily shrinks when heated.

[0226] When the 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 first substrate and sealant layer constituting the propylene-based laminate are required to have heat resistance.

[0227] The laminate sealant film of the present disclosure used as a sealant layer includes a second layer (core layer). The second layer includes 51% by mass or more and 85% by mass or less of a second matrix resin component. The second matrix resin component is made of block propylene. Block propylene has a sea-island structure in which an ethylene-propylene copolymer elastomer is dispersed in a propylene homopolymer (homoPP), and therefore has excellent heat resistance. Therefore, a propylene-based laminate using the laminate sealant film of the present disclosure has improved heat resistance.

[0228] On the other hand, block propylene has a high melting point. Therefore, when the entire propylene-based sealant film is composed of block propylene, the heat-sealing temperature of the packaging material made of a propylene-based laminate using the propylene-based sealant film becomes high. If the heat-sealing temperature becomes high, there is a risk of deformation of the first base material layer due to the small difference in melting point between the first base material and the propylene-based laminate.

[0229] Taking this into consideration, the laminate sealant film of the present disclosure includes a first layer (sealing layer) that contacts the second layer and is located on the outermost surface of the laminate when used in a laminate. The first layer includes 51% by mass or more and 90% by mass or less of a first matrix resin component. The first matrix resin component is made of a propylene-ethylene random copolymer. The melting point of the propylene-ethylene random copolymer is lower than the melting point of block propylene. Therefore, the heat sealing temperature of a packaging material made of a propylene laminate using the laminate sealant film can be lowered compared to when the entire propylene sealant film is composed of block propylene. Thus, the laminate sealant film of the present disclosure has both heat resistance and low-temperature sealability by including a first layer and a second layer composed primarily of different polypropylenes.

[0230] The second layer (core layer) has a sea-island structure in which at least a portion of the second dispersion component is dispersed in the second matrix resin component. The second dispersion component contains at least 5% by mass of polyethylene in the second layer. According to the laminate sealant film of the present disclosure, the impact resistance of the second layer is improved by dispersing the second dispersion component in the second matrix resin component. For example, a packaging material made of a propylene laminate using the laminate sealant film can be used to prevent a container made of the packaging material from bursting when dropped.

[0231] Furthermore, the first layer (sealing layer) also has a sea-island structure in which at least a portion of the first dispersed component is dispersed in the first matrix resin component. The first dispersed component contains at least 5% by mass of polyethylene in the first layer. According to the laminate sealant film of the present disclosure, the impact resistance of the first layer is improved by dispersing the first dispersed component in the first matrix resin component, thereby further improving the impact resistance of the propylene-based sealant film. Furthermore, since both the first layer and the second layer have a sea-island structure, the affinity between the structure of the first layer and the structure of the second layer is enhanced. Therefore, fracture at the interface between the first layer and the second layer can be suppressed. The affinity between the structure of the first layer and the structure of the second layer also contributes to improving the impact resistance of the laminate sealant film of the present disclosure.

[0232] The present disclosure relates to, for example, the following items [1] to

[22] : [1] 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 material, the sealant film comprising at least a first layer located on one surface of the laminate when used in the laminate, and a second layer in contact with the first layer, wherein the first layer contains a first matrix resin component and a first dispersed component in an amount of 51% by mass or more and 90% by mass or less relative to the total amount of the first layer, and has a sea-island structure in which the first dispersed component is dispersed in the first matrix resin component, the second layer contains a second matrix resin component and a second dispersed component in an amount of 51% by mass or more and 85% by mass or less relative to the total amount of the second layer, and has a sea-island structure in which the second dispersed component is dispersed in the second matrix resin component, the first matrix resin component comprising a propylene-ethylene random copolymer, the first dispersed component comprising at least 5% by mass or more of polyethylene relative to the total amount of the first layer, and the second matrix resin component comprising a block polypropylene,

[0013]

[0014] A laminate sealant film, wherein the second dispersed component comprises at least 5% by mass of polyethylene relative to the total amount of the second layer. [2] The laminate sealant film according to [1], wherein the block polypropylene comprises at least a propylene homopolymer and a block elastomer, and has a sea-island structure in which the block elastomer is dispersed in the propylene homopolymer. [3] The laminate sealant film according to [2], wherein the block elastomer is an ethylene-propylene elastomer. [4] The laminate sealant film according to any one of [1] to [3], wherein the content of the second dispersed component relative to the total amount of the second layer is 15% by mass or more and 49% by mass or less. [5] The laminate sealant film according to any one of [1] to [4], wherein the content of the first dispersed component relative to the total amount of the first layer is 10% by mass or more and 49% by mass or less. [6] The sealant film for laminates according to any one of [1] to [5], wherein the content ratio of the first dispersion component relative to the total amount of the first layer is less than the content ratio of the second dispersion component relative to the total amount of the second layer.[7] The laminate sealant film according to any one of [1] to [6], wherein the second dispersion component further comprises a second elastomer. [8] The laminate sealant film according to [7], wherein the second elastomer comprises a propylene-ethylene elastomer or an ethylene-α-olefin elastomer. [9] The laminate sealant film according to [7] or [8], wherein the ratio of the content of the second elastomer to the content of the polyethylene in the second dispersion component is 0.5 or more and less than 1.0.

[10] The laminate sealant film according to [1] to [9], wherein the first dispersion component further comprises a first elastomer.

[11] The laminate sealant film according to

[10] , wherein the ratio of the content of the first elastomer to the content of the polyethylene in the first dispersion component is 0.5 or more and less than 1.0.

[12] The laminate sealant film according to [1] to

[11] , wherein the ratio of the thickness of the second layer to the thickness of the first layer is 3.0 or more.

[13] The laminate sealant film according to any one of [1] to

[12] , wherein the second layer has a thickness of 50 μm or more.

[14] The laminate sealant film according to any one of [1] to

[13] , wherein the polyethylene of the second dispersed component comprises linear low-density polyethylene (LLDPE) or low-density polyethylene (LDPE).

[15] The laminate sealant film according to any one of [1] to

[14] , wherein the polyethylene of the second dispersed component consists of linear low-density polyethylene (LLDPE).

[16] The laminate sealant film according to any one of [2] to

[15] , further comprising a third layer in contact with the second layer, wherein the third layer contains a third matrix resin component in an amount of 51% by mass to 85% by mass, relative to the total amount of the third layer, and a third dispersed component, and has a sea-island structure in which the third dispersed component is dispersed in the third matrix resin component, and the third matrix resin component consists of the block polypropylene.

[17] The sealant film for laminates according to

[16] , wherein the third dispersion component comprises either one or both of polyethylene and a third elastomer.

[18] The sealant film for laminates according to any one of [1] to

[17] , having a thickness of 30 μm or more and 200 μm or less.

[19] A laminate for use in packaging materials, comprising at least a first substrate and a sealant layer, wherein the sealant layer is made of the sealant film for laminates according to any one of [1] to

[18] , and wherein the polypropylene content relative to the total amount of resin materials is 80 mass% or more.

[20] The laminate according to

[19] , further comprising a second substrate between the first substrate and the sealant layer.

[21] A packaging container comprising the laminate according to

[19] or

[20] .

[22] The packaging container according to

[21] , which is a boil-proof or retort pouch.

[0233] Example 1 Preparation of Sealant Film for Laminates A resin composition 1 for a first layer containing 75% by mass of random PP1, 13% by mass of PE1, and 12% by mass of elastomer 1, a resin composition 2 for a second layer containing 55% by mass of block PP1, 27% by mass of PE1, and 18% by mass of elastomer 1, and a resin composition 3 for a third layer containing 55% by mass of block PP1, 27% by mass of PE1, and 18% by mass of elastomer 1 were simultaneously extruded through a multilayer die to prepare an unstretched multilayer film having first, second, and third layer thicknesses of 10 μm, 40 μm, and 10 μm (hereinafter also referred to as “sealant film (Example 1)”).

[0234] [Propylene homopolymer] HomoPP1: Propylene homopolymer (MFR: 2.5 g / 10 min, density: 900 kg / m ３ ) [Block polypropylene] Block PP1: 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) [Propylene-ethylene random copolymer] Random PP1: propylene-ethylene random copolymer (MFR: 6 g / 10 min, density: 0.890 g / cm ３ ) [Polyethylene] PE1: Linear low-density polyethylene (MFR: 2.0 g / 10 min, density: 0.919 g / cm ３ ) PE2: low-density polyethylene (MFR: 7.0 g / 10 min, density: 0.920 g / cm ３) PE3: High density polyethylene (MFR: 16.0 g / 10 min, density: 0.960 g / cm ３ ) [Thermoplastic elastomers] Elastomer 1: Propylene-α-olefin copolymer (melting point: 98°C, MFR (190°C): 3.0 g / 10 min, MFR (230°C): 7.0 g / 10 min) Elastomer 2: Ethylene-α-olefin copolymer (melting point: 66°C, MFR (190°C / 2.16 kg): 3.6 g / 10 min, MFR (230°C / 2.16 kg): 6.7 g / 10 min)

[0235] <Preparation of Transparent 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.

[0236] 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.

[0237] 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:

[0238] (Forming conditions) Hexamethyldisiloxane: oxygen gas: helium = 1:10:10 (unit: slm) Power supplied to cooling / electrode drum: 22 kW Line speed: 100 m / min

[0239] 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.

[0240] 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 way, a transparent barrier substrate was obtained.

[0241] <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 transparent barrier substrate was dry-laminated so that the barrier coat layer surface of the substrate was in contact with the adhesive layer surface.

[0242] The non-barrier coat layer surface of a transparent barrier substrate used as a second substrate (intermediate substrate) was subjected to corona treatment, and then coated with a two-component curing polyurethane adhesive (RU-004 / H-1, manufactured by Rock Paint Co., Ltd.) using a gravure roll coating method to a coating thickness of 3.5 μm (when dried), and then a sealant film (Example 1) was dry laminated onto the adhesive layer surface with the third layer facing the adhesive layer surface.

[0243] In this way, a laminate with a thickness of approximately 109 μm was obtained. The laminate consisted of a biaxially oriented polypropylene film (20 μm) / a printed layer (1 μm) / a solvent-based adhesive layer (4 μm) / a transparent barrier substrate (approximately 20 μm) / a solvent-based adhesive layer (3.5 μm) / a sealant film (Example 1) (60 μm). The mono-material content of the laminate was approximately 91% by mass.

[0244] Examples 2 to 16 A laminate with a thickness of approximately 109 μm was obtained in the same manner as in Example 1, except that sealant films (Examples 2 to 16) prepared with the formulations shown in Tables 1 and 2 below were used instead of the sealant film (Example 1). The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Examples 2 to 16) (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0245] [Example 17] <Preparation of sealant film for laminate> A resin composition 1 for a first layer containing 85% by mass of random PP1, 8% by mass of PE1, and 7% by mass of elastomer 1, and a resin composition 2 for a second layer containing 70% by mass of block PP1, 20% by mass of PE1, and 10% by mass of elastomer 1, were simultaneously extruded through a multilayer die to prepare an unstretched multilayer film (hereinafter also referred to as "sealant film (Example 17)") having first layer / second layer / third layer thicknesses of 10 μm / 50 μm / 0 μm. <Preparation of laminate> The same procedure as in Example 1 was carried out, except that the prepared sealant film (Example 17) was used instead of the sealant film (Example 1), to obtain a laminate with a thickness of approximately 109 μm. The laminate consisted of a biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Examples 2 to 16) (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0246] Comparative Examples 1 to 7 A laminate having a thickness of approximately 109 μm was obtained in the same manner as in Example 1, except that sealant films (Comparative Examples 1 to 7) prepared according to the formulations shown in Table 3 below were used instead of the sealant film (Example 1). The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (approximately 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Comparative Examples 1 to 7) (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0247] [Evaluation of Heat Resistance] 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 a bag-shaped pouch. 100 mL of water was filled into the resulting pouch through the opening, and the opening was heat-sealed to seal. The sealed pouch was subjected to a hot water retort sterilization treatment at a retort temperature of 135°C for a retort time of 30 minutes, and the heat resistance of the laminate was evaluated by checking for changes in appearance and the presence or absence of temporary inner surface adhesion. The results are shown in Tables 1 to 3. <Evaluation Criteria> A: No change in appearance B: Wrinkles on the exterior, but no temporary inner surface adhesion C: Wrinkles on the exterior, with slight temporary adhesion near the seal edge D: Wrinkles and temporary inner surface adhesion occurred, and the pouch shape was not maintained

[0248] [Evaluation of low-temperature sealability] 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 10 mm at 175°C. The presence or absence of leakage and seal retraction was then confirmed using a pressure tester (RTA-1T, manufactured by A&D Co.) to evaluate the low-temperature sealability of the laminate. The results are shown in Tables 1 to 3. <Evaluation criteria> A: Pressure test at 100 kgf for 1 minute, no leakage, no seal retraction B: Pressure test at 100 kgf for 1 minute, no leakage, seal retraction less than 5 mm C: Pressure test at 75 kgf for 1 minute, no leakage, no seal retraction B: Pressure test at 75 kgf for 1 minute, leakage present

[0249] [Evaluation of Impact Resistance] 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 pouch through the opening, and the opening was heat-sealed to seal. The sealed pouch was 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 Tables 1 to 3. <Evaluation Criteria> S: No breakage; A: No breakage, but retraction of the seal position observed; B: No leakage of contents, but retraction of the seal position and lifting observed near the seal edge; C: Two or fewer breakages; D: Three or more breakages.

[0250] [Evaluation of Processability] The produced laminate sealant film was placed on a flat surface and the curl of the sealant film was visually checked to evaluate the processability. The results are shown in Tables 1 to 3. <Evaluation Criteria> S: Curl less than 1 mm A: Curl 1 mm or more but less than 3 mm B: Curl 3 mm or more but less than 5 mm C: Curl 5 mm or more but less than 10 mm D: Curl 10 mm or more

[0251] [Evaluation of seal strength] The seal strength of the laminate was evaluated by measuring the seal strength after the retort sterilization treatment used in the evaluation of heat resistance described above using a tensile tester (Strograph VG1F, manufactured by Toyo Seiki Seisaku-sho, Ltd.). The results are shown in Tables 1 to 3. <Evaluation criteria> A: 50 N or more B: 40 N or more C: 30 N or more D: 29 N or less (transition to interlayer delamination of the laminate sealant film)

[0252]

[0253]

[0254]

[0255] 1: Laminate 10: Polypropylene resin substrate 20: Barrier substrate 22: Polypropylene resin layer 23: Surface coating layer 24: Vapor deposition film 25: Barrier coating layer 26: Surface resin layer 27: Adhesive resin layer 30: Sealant layer (sealant film for laminate) 40, 40A, 40B: Adhesive layer 50: Packaging bag 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 sealed portion 63b: Non-sealed portion

Claims

1. A sealant film for use in a laminate in which the content of polypropylene relative to the total amount of resin material is 80% by mass or more, the sealant film comprising at least a first layer located on one surface of the laminate when used in the laminate, and a second layer in contact with the first layer, the first layer comprising a first matrix resin component and a first dispersed component in an amount of 51% by mass or more and 90% by mass or less relative to the total amount of the first layer, and having an island-in-sea structure in which the first dispersed component is dispersed in the first matrix resin component, the second layer comprising a second matrix resin component and a second dispersed component in an amount of 51% by mass or more and 85% by mass or less relative to the total amount of the second layer, and having an island-in-sea structure in which the second dispersed component is dispersed in the second matrix resin component, the first matrix resin component being made of a propylene-ethylene random copolymer, the first dispersed component being made of at least 5% by mass of polyethylene relative to the total amount of the first layer, and the second matrix resin component being made of a block polypropylene, A sealant film for laminates, wherein the second dispersion component comprises at least 5% by weight or more of polyethylene relative to the total amount of the second layer.

2. The sealant film for laminates according to claim 1, wherein the block polypropylene contains at least a propylene homopolymer and a block elastomer and has an islands-in-a-sea structure in which the block elastomer is dispersed in the propylene homopolymer.

3. The sealant film for laminates according to claim 2, wherein the block elastomer comprises an ethylene-propylene elastomer.

4. A sealant film for laminates as described in claim 1, wherein the content ratio of the second dispersion component to the total amount of the second layer is 15 mass% or more and 49 mass% or less.

5. A sealant film for laminates as described in claim 4, wherein the content ratio of the first dispersion component to the total amount of the first layer is 10 mass% or more and 49 mass% or less.

6. A sealant film for laminates as described in claim 5, wherein the content ratio of the first dispersion component to the total amount of the first layer is lower than the content ratio of the second dispersion component to the total amount of the second layer.

7. The laminate sealant film of claim 1, wherein said second dispersion component further comprises a second elastomer.

8. The sealant film for laminates according to claim 7, wherein the second elastomer comprises a propylene-ethylene elastomer or an ethylene-α-olefin elastomer.

9. A sealant film for laminates as described in claim 7, wherein the ratio of the content of the second elastomer to the content of the polyethylene in the second dispersion component is 0.5 or more and less than 1.

0.

10. The laminate sealant film of claim 1, wherein said first dispersion component further comprises a first elastomer.

11. The sealant film for laminates according to claim 10, wherein in the first dispersion component, the ratio of the content of the first elastomer to the content of the polyethylene is 0.5 or more and less than 1.

0.

12. The sealant film for laminates according to claim 1, wherein the ratio of the thickness of the second layer to the thickness of the first layer is 3.0 or more.

13. The sealant film for laminates according to claim 12, wherein the second layer has a thickness of 50 μm or more.

14. The laminate sealant film of claim 1, wherein the polyethylene of the second dispersion component comprises linear low density polyethylene (LLDPE) or low density polyethylene (LDPE).

15. The laminate sealant film of claim 1, wherein the polyethylene of the second dispersion component comprises linear low density polyethylene (LLDPE).

16. A sealant film for laminates as described in claim 2, further comprising a third layer in contact with the second layer, the third layer containing a third matrix resin component in an amount of 51% by mass or more and 85% by mass or less with respect to the total amount of the third layer, and a third dispersed component, and having a sea-island structure in which the third dispersed component is dispersed in the third matrix resin component, and the third matrix resin component is made of the block polypropylene.

17. The laminate sealant film according to claim 16, wherein the third dispersion component comprises one or both of a polyethylene and a third elastomer.

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

19. A laminate for use in a packaging material, comprising at least a first substrate and a sealant layer, the sealant layer being made of a sealant film for laminates according to any one of claims 1 to 18, and the polypropylene content relative to the total amount of resin material is 80 mass% or more.

20. The laminate of claim 19, further comprising a second substrate between the first substrate and the sealant layer.

21. A packaging container comprising a laminate according to claim 19 or 20.

22. The packaging container according to claim 21, which is a boil or retort pouch.

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