Sealant film for laminate, laminate and packaging container

Abstract

To provide a sealant film for a laminate which is excellent in impact resistance after retort treatment, and is suitable for a laminate formed into a single material made of polypropylene.SOLUTION: A sealant film is used in a laminate having a content ratio of polypropylene with respect to the total amount of a resin material of 80 mass% or more, wherein the sealant film contains 40 mass% or more of polypropylene with respect to the total amount of the sealant film, and the sealant film has a composite elastic modulus measured by a nanoindentation method of 500 MPa or more and 900 MPa or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sealant film for a laminate, a laminate, and a packaging container. [Background technology]

[0002] Conventionally, packaging containers have been made of laminates using a polyester film excellent in strength and heat resistance, a nylon film excellent in impact resistance, or the like as a base material, and a polyolefin film excellent in heat sealability as a sealant film. However, with the growing demand for the construction of a recycling-oriented society in recent years, packaging containers with high recyclability are in demand, but it was difficult to separate the conventional packaging containers made of different resin materials into individual resin materials.

[0003] 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. With this laminate, both the substrate and the sealant film are made of polypropylene, improving recyclability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-020391 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when a laminate is used for a packaging container such as a retort pouch, it is required that the laminate has drop impact resistance (impact resistance) that can withstand the impact when the pouch is dropped after retort treatment, and hand tearability (easy opening) that allows the laminate to be easily torn by hand after retort treatment. However, a laminate made of a single material such as polypropylene may not have sufficient impact resistance and opening ability after retort treatment.

[0006] One of the problems to be solved by the present disclosure is to provide a sealant film for laminates that has excellent impact resistance and openability after retort treatment and is suitable for laminates made of a single material made of polypropylene. [Means for solving the problem]

[0007] The sealant film for laminates disclosed herein is a sealant film for use in laminates having a polypropylene content of 80 mass% or more relative to the total amount of resin material, the sealant film containing 40 mass% or more of polypropylene relative to the total amount of the sealant film, and the sealant film has a composite elastic modulus of 500 MPa or more and 900 MPa or less, measured by a nanoindentation method. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a sealant film for laminates that has excellent impact resistance and openability after retort treatment and is suitable for laminates made of a single material such as polypropylene. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of a sealant film for laminates. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing one embodiment of the sealant film for laminates. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 4] FIG. 4 is a schematic cross-sectional view showing one embodiment of a laminate. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 6] FIG. 6 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 7] FIG. 7 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 8] FIG. 8 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 9] FIG. 9 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 10] FIG. 10 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 11] FIG. 11 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 12] FIG. 12 is a front view showing one embodiment of a packaging container. [Figure 13] FIG. 13 is a perspective view showing one embodiment of a packaging container. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] 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 configured by combining any one upper limit candidate and any one lower limit candidate. Examples of the above parameters include physical property values, component content ratios, and layer thicknesses. As an example, the description "Parameter B is preferably A1 or more, more preferably A2 or more, and even more preferably A3 or more. Parameter B is preferably A4 or less, more preferably A5 or less, and even more preferably A6 or less." will be explained. In this example, the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[0012] In this specification, the "main component" of a layer or substrate refers to a component whose content in the layer or substrate is more than 50% by mass, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0013] In the following description, each of the components (e.g., polypropylene, α-olefin, resin material, additive, adhesive resin, inorganic oxide, gas barrier resin, propylene-ethylene block copolymer, thermoplastic elastomer, and polyethylene) may be used either alone or in combination of two or more kinds.

[0014] [Sealant film for laminates] The sealant film for laminates of the present disclosure contains 40% by mass or more of polypropylene based on the total amount of the sealant film. A laminate having such a sealant film for laminates as a sealant layer has excellent drop impact resistance (impact resistance) that can withstand the impact when the pouch is dropped after retort treatment, and excellent hand tearability (openability) that allows easy tearing by hand after retort treatment.

[0015] The sealant film for laminates may have a single-layer structure or a multi-layer structure. In one embodiment, the sealant film for laminates of the present disclosure has a single-layer structure. In one embodiment, the sealant film for laminates of the present disclosure has a two-layer structure, including a first layer that serves as a sealing surface when used in a laminate, and a second layer that serves as a core layer. In one embodiment, the sealant film for laminates of the present disclosure has a three-layer structure including a first layer that becomes a sealing layer when used in a laminate, a second layer that becomes a core layer, and a third layer that becomes a surface layer located on the adhesive layer side. The sealant film for laminates of the present disclosure is suitably used for laminates in which the content of polypropylene relative to the total amount of resin materials is 80 mass % or more.

[0016] <Single layer structure> The polypropylene content in the single-layer sealant film for laminates of the present disclosure (hereinafter also simply referred to as "single-layer sealant film") is 40 mass% or more, preferably more than 50 mass%, more preferably 60 mass% or more, even more preferably 70 mass% or more, still more preferably 80 mass% or more, particularly preferably 85 mass% or more, 90 mass% or more, or 95 mass% or more.

[0017] The polypropylene may be any one of homopolypropylene, random polypropylene and block polypropylene, or may be a mixture of two or more selected from these. As the polypropylene, biomass-derived polypropylene and / or recycled polypropylene may be used. Homopolypropylene is a polymer of only propylene. Random polypropylene is a random polypropylene of propylene and α-olefins other than propylene. Block polypropylene is a polypropylene having a polymer block of propylene and a polymer block of at least α-olefins other than propylene. The polymer block of at least α-olefins other than propylene may be a polymer block of propylene and α-olefins other than propylene.

[0018] Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms other than propylene, specifically, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.

[0019] Among polypropylenes, random polypropylenes are preferred from the viewpoint of heat sealability, homopolypropylenes are preferred when the rigidity and heat resistance of the packaging bag are important, and block polypropylenes are preferred when the impact resistance of the packaging bag is important. In the monolayer sealant film of the present disclosure, among these polypropylenes, random polypropylenes are more preferred from the viewpoint of heat sealability.

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

[0021] The monolayer sealant film of the present disclosure may contain polyethylene as a dispersed component. Polyethylene can contribute to increasing the impact resistance of the monolayer sealant film of the present disclosure. The monolayer sealant film of the present disclosure preferably has a sea-island structure in which polyethylene, a dispersed component (island component), is dispersed in random polypropylene, a matrix resin component (sea component). This can increase the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure.

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

[0023] The density of the low density polyethylene is preferably 900 kg / m 3 More than 925kg / m 3 Less than or equal to 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 atm or more and less than 2000 atm. Low-density polyethylene is also called high-pressure low-density polyethylene.

[0024] The density of the linear low density polyethylene is preferably 900 kg / m 3 More than 925kg / m 3 Less than or equal to 915 kg / m 3 More than 925kg / m 3 The 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 4 to 10 carbon atoms, such as 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

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

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

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

[0028] The single-layer sealant film of the present disclosure may contain an elastomer as a dispersed component. By containing an elastomer as a dispersed component, the dispersed state of polyethylene, which is a dispersed component (island component), in the random polypropylene, which is a matrix resin component (sea component), can be further improved. This can further improve the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure.

[0029] The elastomer is not particularly limited as long as it is a thermoplastic elastomer that can improve the dispersion state of polyethylene in the random polypropylene. Examples of the elastomer include a propylene-ethylene copolymer (propylene-ethylene elastomer) and an ethylene-α-olefin copolymer (ethylene-α-olefin elastomer).

[0030] 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 by a metallocene catalyst is preferable.

[0031] The ethylene-α-olefin 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 ethylene units as a main component and α-olefin units as a copolymerization monomer. As the ethylene-α-olefin elastomer, an elastomer produced by a metallocene catalyst is preferable.

[0032] Examples of the α-olefin include α-olefins having 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 copolymers, ethylene-1-butene random copolymers, and ethylene-1-octene random copolymers.

[0033] The MFR of the elastomer is preferably 0.1 g / 10 min to 10 g / 10 min, more preferably 0.2 g / 10 min to 5 g / 10 min. The MFR of the elastomer is measured in accordance with JIS K7210 at a temperature of 230° C. or 190° C. and a load of 2.16 kg.

[0034] In the monolayer sealant film of the present disclosure, the content ratio of the dispersion component to the total amount of the monolayer sealant film is preferably 10% by mass or more, more preferably 15% by mass or more, and also preferably 49% by mass or less, more preferably 30% by mass or less. In the monolayer sealant film, when the content ratio of the dispersion component is equal to or more than the lower limit, for example, the impact resistance of the laminate using the monolayer sealant film of the present disclosure can be further improved. When the content ratio of the dispersion component is equal to or less than the upper limit, for example, the seal strength of the laminate using the monolayer sealant film of the present disclosure can be further improved.

[0035] In the monolayer sealant film of the present disclosure, the content of polyethylene relative to the total amount of the monolayer sealant film is preferably 5% by mass or more, more preferably 8% by mass or more, even more preferably 13% by mass or more, and is preferably 49% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less. When the content of polyethylene is equal to or more than the lower limit, for example, the impact resistance of the laminate using the monolayer sealant film of the present disclosure can be further improved. When the content of polyethylene is equal to or less than the upper limit, for example, the seal strength of the laminate using the monolayer sealant film of the present disclosure can be further improved.

[0036] In the monolayer sealant film of the present disclosure, the content ratio of the elastomer relative to the total amount of the monolayer sealant film is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less. When the content ratio of the elastomer is equal to or more than the lower limit, for example, the impact resistance of a laminate using the monolayer sealant film of the present disclosure can be further improved. When the content ratio of the elastomer is equal to or less than the upper limit, for example, the seal strength of a laminate using the monolayer sealant film of the present disclosure can be further improved.

[0037] The single-layer sealant film of the present disclosure may contain additives, such as crosslinkers, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0038] The thickness of the monolayer sealant film of the present disclosure is preferably 10 μm or more, more preferably 20 μm or more, and also preferably 200 μm or less, more preferably 150 μm or less, for example, 10 μm or more and 200 μm or less. A laminate having a monolayer sealant film having a thickness of the lower limit or more as a sealant layer has, for example, excellent seal strength. A laminate having a monolayer sealant film having a thickness of the upper limit or less as a sealant layer has, for example, excellent processability. When a pouch (particularly a retort pouch) is produced from the laminate, the thickness of the sealant layer is preferably 30 μm or more, and preferably 100 μm or less.

[0039] In this specification, the thickness of the substrate and each layer is measured as follows. A block is prepared by embedding the laminate in an embedding resin, and the block is cut using a commercially available rotary microtome at room temperature (25°C) to prepare a cross section of the laminate. The cross section is obtained by cutting the laminate in the thickness direction perpendicular to the main surface. Finishing is performed with a diamond knife. The thickness of the substrate and each layer is the arithmetic average value of the thicknesses at five points measured by observing the cross section using a scanning electron microscope (SEM, Hitachi, Ltd., SU8000).

[0040] <Multilayer structure> 1 and 2 are schematic cross-sectional views showing one embodiment of a sealant film for laminates having a multi-layer structure (hereinafter, also simply referred to as a "multi-layer sealant film"). 1 has a two-layer structure, and includes a first layer 31 as a seal layer and a second layer 32 as a core layer in this 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 in the outermost layer of the laminate, and the second layer 32 is located on the inner layer side of the laminate.

[0041] 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 in 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.

[0042] (1st 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 is a sea component, the first dispersed component is an island component, and the island components are dispersed in the sea component. The first layer constitutes the sealing layer of the multi-layer sealant film of the present disclosure.

[0043] The first matrix resin component is made of a propylene-ethylene random copolymer. Propylene-ethylene random copolymer (random polypropylene) is a random copolymer of 51% by mass or more and 90% by mass or less of propylene units as the main component and ethylene units as a copolymerization monomer, and has superior transparency and impact strength compared to propylene homopolymer (homopolypropylene), and its melting point is 20 to 30°C lower.

[0044] The ethylene content of the random polypropylene is preferably 1.0% by mass or more, more preferably 2.0% by mass or more. The ethylene content of the random polypropylene is preferably 20% by mass or less, more preferably 10% by mass or less. When the ethylene content is the lower limit or more, low-temperature sealability can be ensured when the multilayer sealant film of the present disclosure is used to form a laminate. When the ethylene content is the upper limit or less, excessive deterioration of heat resistance can be suppressed when the multilayer sealant film of the present disclosure is used to form a laminate. The ethylene content of random polypropylene can be measured by the ethylene content determination method (IR method) described on pages 412-413 of "Polymer Analysis Handbook (May 10, 2013, 3rd printing)" edited by the Polymer Analysis Discussion Group of the Japan Analytical Society.

[0045] The melting point of the random polypropylene is preferably 145°C or less, more preferably 135°C or less. When the melting point is the upper limit or less, the low-temperature sealability of the laminate using the multilayer sealant film of the present disclosure is good, and the suitability for bag making can be improved. The lower limit of the melting point of the random polypropylene is preferably 120 or more. When the melting point is the lower limit or more, when the laminate using the multilayer sealant film of the present disclosure is used for a retort pouch or the like, the heat seal strength can be ensured under semi-retort temperature conditions. In this specification, the melting point can be measured in accordance with JIS K7121:2012 (Method for measuring transition temperature of plastics). Specifically, the melting point can be determined by measuring a DSC curve at a temperature rise rate of 10° C. / min by differential scanning calorimetry (DSC).

[0046] The melt flow rate (MFR) of the random polypropylene is preferably 0.5 g / 10 min to 10 g / 10 min, more preferably 1 g / 10 min to 5 g / 10 min. The MFR of the propylene-ethylene random copolymer is measured in accordance with JIS K7210 at a temperature of 230° C. and a load of 2.16 kg.

[0047] A method for producing random polypropylene includes, for example, polymerizing raw materials such as propylene and ethylene using a catalyst. Examples of the catalyst include Ziegler-Natta catalysts and metallocene catalysts.

[0048] The first dispersion component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the multi-layer sealant film of the present disclosure. The first layer has a sea-island structure in which the first dispersion component (island component) polyethylene is dispersed in the random polypropylene that is the first matrix resin component (sea component), and therefore the drop impact resistance of the laminate using the multi-layer sealant film of the present disclosure can be improved.

[0049] As mentioned above, examples of polyethylene include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE). Among these, low density polyethylene and linear low density polyethylene are preferred, and linear low density polyethylene is more preferred. Linear low density polyethylene has good dispersibility in random polypropylene, which is the above-mentioned sea component, and can increase the impact resistance of the first layer. Therefore, peeling caused by discontinuity in impact resistance can be suppressed between the first layer and the second layer of the laminate sealant film.

[0050] The first dispersion component may further contain a first elastomer. By containing the first dispersion component, the dispersion state of the polyethylene, which is the first dispersion component (island component), in the random polypropylene, which is the first matrix resin component (sea component), can be further improved. This can further improve the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0051] The first elastomer is not particularly limited as long as it is a thermoplastic elastomer that can improve the dispersion state of polyethylene in the random polypropylene. As described above, examples of the first elastomer include propylene-ethylene copolymer (propylene-ethylene elastomer) and ethylene-α-olefin copolymer (ethylene-α-olefin elastomer).

[0052] The MFR of the first elastomer is preferably 0.1 g / 10 min to 10 g / 10 min, more preferably 0.2 g / 10 min to 5 g / 10 min, and is measured in accordance with JIS K7210 at a temperature of 230° C. or 190° C. and a load of 2.16 kg.

[0053] 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.

[0054] 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, based on 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, based on the total amount of the first layer. When the content of the first dispersion component in the first layer is equal to or more than the lower limit, the impact resistance of the laminate using the multi-layer sealant film of the present disclosure can be improved. When the content of the first dispersion component is equal to or less than the upper limit, the seal strength of the laminate using the multi-layer sealant film of the present disclosure can be improved.

[0055] In the first layer, the content of polyethylene is 5% by mass or more, preferably 8% by mass or more, more preferably 13% by mass or more, based on the total amount of the first layer. In the first layer, the content of polyethylene is, for example, 15% by mass or less, based on the total amount of the first layer. When the content of polyethylene is equal to or more than the lower limit, for example, the impact resistance of a laminate using the multi-layer sealant film of the present disclosure can be further improved. When the content of polyethylene is equal to or less than the upper limit, for example, the seal strength of a laminate using the multi-layer sealant film of the present disclosure can be further improved.

[0056] In the first layer, the content of the first elastomer is preferably 4% by mass or more, more preferably 7% by mass or more, based on 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, based on the total amount of the first layer. When the content of the first elastomer is equal to or more than the lower limit, for example, the impact resistance of a laminate using the multi-layer sealant film of the present disclosure can be further improved. When the content of the first elastomer is equal to or less than the upper limit, for example, the seal strength of a laminate using the multi-layer sealant film of the present disclosure can be further improved.

[0057] In the first dispersion component, the ratio of the content of the first elastomer to the content of the polyethylene is preferably 0.5 or more and less than 1.0. When the ratio of the content of the first elastomer to the content of the polyethylene in the first dispersion component is within the above range, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0058] 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, the low-temperature sealability and impact resistance of a packaging container including a laminate using the multi-layer sealant film of the present disclosure can be improved. When the thickness is equal to or less than the upper limit, the processability of a laminate using the multi-layer sealant film of the present disclosure can be improved.

[0059] (2nd 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 is a sea component, the second dispersed component is an island component, and the island components are dispersed in the sea component. The second layer constitutes the core layer of the multi-layer sealant film of the present disclosure.

[0060] The second matrix resin component is made of block polypropylene (block PP). A block polypropylene (propylene block copolymer) is a copolymer containing at least a propylene homopolymer (homopolypropylene) and a block elastomer. An example of the block polypropylene is a propylene-ethylene block copolymer.

[0061] In one embodiment, the propylene-ethylene block copolymer includes a polymer part (a) made of a propylene polymer and a polymer part (b) made of a polyethylene and an ethylene-propylene copolymer rubber component. In one embodiment, the propylene-ethylene block copolymer includes a sea component made of a propylene polymer and an island component made of a polyethylene and an ethylene-propylene copolymer rubber component. The polymer part (a) and the sea component can contribute to improving the heat resistance, rigidity, blocking resistance, and seal strength of the propylene-ethylene block copolymer. The polymer part (b) and the island component 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 part (a) to the polymer part (b) and the ratio of the sea component to the island component.

[0062] In one embodiment, the propylene polymer of the polymer part (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 the melting point is 160° C. or higher. Examples of the α-olefin include ethylene, 1-butene, 1-hexene, and 1-octene.

[0063] In the polymer part (b), for example, in the polyethylene and ethylene-propylene copolymer rubber components, the content ratio of the ethylene-derived structural unit is preferably 10% by mass or more, more preferably 20% by mass or more. Moreover, the content ratio is preferably 50% by mass or less, more preferably 40% by mass or less. By being within the above preferred range, for example, the drop impact resistance can be further improved. In the present disclosure, the content ratio of the structural unit can be measured, for example, by a temperature gradient method (TGIC: Thermal Gradient Interaction Chromatography). In the polymer part (b), the ethylene-propylene copolymer rubber component corresponds to a block elastomer.

[0064] 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.

[0065] In the propylene-ethylene block copolymer, the mass ratio of the polymer part (a) made of a propylene polymer or the sea component is preferably 51 mass% or more, more preferably 60 mass% or more, and further preferably 70 mass% or more. The upper limit of the mass ratio of the polymer part (a) made of a propylene polymer or the sea component is, for example, 90 mass%.

[0066] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (b) consisting of polyethylene and ethylene-propylene copolymer rubber components or the island component is preferably 49 mass% or less, more preferably 40 mass% or less, and further 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 the island component is, for example, 10 mass%.

[0067] The melt flow rate (MFR) of the propylene-ethylene block copolymer is preferably 0.5 g / 10 min to 10 g / 10 min, more preferably 1 g / 10 min to 5 g / 10 min. 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.

[0068] Examples of methods for producing propylene-ethylene block copolymers include a method of polymerizing raw materials such as propylene and ethylene using a catalyst. Examples of the catalyst include Ziegler-Natta catalysts and metallocene catalysts.

[0069] The second dispersion component includes polyethylene. Polyethylene can contribute to improving the impact resistance of the sealant film for laminates of the present disclosure. The second layer has an island-in-sea structure in which polyethylene is dispersed as the second dispersion component in block polypropylene (propylene-ethylene block copolymer) which is the second matrix resin component. That is, since it has an island-in-sea structure in which polymer part (a) made of propylene polymer is dispersed with polymer part (b) made of ethylene-propylene copolymer rubber component and polyethylene which is the second dispersion component, the drop impact resistance of the laminate using the multi-layer sealant film of the present disclosure can be further improved.

[0070] The polyethylene may be the same as that used for the first dispersion component of the first layer.

[0071] The second dispersion component may further contain a second elastomer. By containing the second dispersion component, 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 increase the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0072] The second elastomer may be the same thermoplastic elastomer as the first dispersion component of the first layer.

[0073] 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.

[0074] 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, based on 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, based on the total amount of the second layer. When the content of the second dispersion component in the second layer is equal to or more than the lower limit, the impact resistance of the laminate using the multi-layer sealant film of the present disclosure can be improved. When the content of the second dispersion component is equal to or less than the upper limit, the heat resistance of the laminate using the multi-layer sealant film of the present disclosure can be improved.

[0075] In the second layer, the content of polyethylene is 5% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, based on the total amount of the second layer. In the second layer, the content of polyethylene is, for example, 30% by mass or less, based on the total amount of the second layer. When the content of polyethylene is equal to or more than the lower limit, for example, the impact resistance of a laminate using the multi-layer sealant film of the present disclosure can be further improved. When the content of polyethylene is equal to or less than the upper limit, for example, the heat resistance of a laminate using the multi-layer sealant film of the present disclosure can be further improved.

[0076] 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, based on 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, based on the total amount of the second layer. When the content of the second elastomer is equal to or more than the lower limit, the impact resistance of, for example, a laminate using the multi-layer sealant film of the present disclosure can be further improved. When the content of the second elastomer is equal to or less than the upper limit, the heat resistance of, for example, a laminate using the multi-layer sealant film of the present disclosure can be further improved.

[0077] In the second dispersion component, the ratio of the content of the second elastomer to the content of the polyethylene is preferably 0.5 or more and less than 1.0. When the ratio of the content of the second elastomer to the content of the polyethylene in the second dispersion component is within the above range, for example, the impact resistance of a laminate using the multilayer sealant film of the present disclosure can be further improved.

[0078] 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, the heat resistance and impact resistance of a packaging container including a laminate using the multilayer sealant film of the present disclosure can be improved. When the thickness is equal to or less than the upper limit, the processability of a laminate using the multilayer sealant film of the present disclosure can be improved.

[0079] (3rd 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 is a sea component, the third dispersed component is an island component, and the island components are dispersed in the sea component. The third layer constitutes the top layer of the multi-layer sealant film of the present disclosure.

[0080] 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.

[0081] The third dispersion component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the multi-layer sealant film of the present disclosure. The third layer has a sea-island structure in which polyethylene, the third dispersion component (island component), is dispersed in block polypropylene, the third matrix resin component (sea component), and therefore the drop impact resistance of the laminate using the multi-layer sealant film of the present disclosure can be improved.

[0082] As the polyethylene, the same polyethylene as that used for the first and second layers can be used.

[0083] The third dispersion component may further contain a third elastomer. By containing 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 increase the drop impact resistance of a laminate using the multilayer sealant film of the present disclosure.

[0084] As the third elastomer, the same thermoplastic elastomer as that used for the first and second layers can be used.

[0085] 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.

[0086] In the third layer, the content ratio of the polyethylene and the content ratio of the third elastomer can be the same as in the second layer.

[0087] 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, the heat resistance and impact resistance of a packaging container including a laminate using the multi-layer sealant film of the present disclosure can be improved. When the thickness is equal to or less than the upper limit, the processability of a laminate using the multi-layer sealant film of the present disclosure can be improved.

[0088] In the multi-layer sealant film of the present disclosure, the polyethylene used in the first layer, the second layer, and the third layer may all be the same type of polyethylene, or different types of polyethylene may be used. Similarly, in the sealant film, the first layer, the second layer, and the third layer may all be the same type of thermoplastic elastomer, or different types of thermoplastic elastomer may be used.

[0089] In the multi-layer sealant film of the present disclosure, the content ratio of the first dispersion component 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 to the total amount of the second layer, which is the core layer. According to the multi-layer sealant film that satisfies the above relationship, the continuity of impact resistance is maintained in the first and second layers, thereby increasing the affinity between the two layers, suppressing the occurrence of breakage at the interface between the two layers, and further improving the low-temperature sealability caused by the first layer.

[0090] In the multilayer sealant film of the present disclosure, the ratio of the thickness of the second layer to the thickness of the first layer is preferably 3.0 or more. According to the sealant film for laminates that satisfies the above relationship, the heat resistance and impact resistance attributable to the second layer can be further improved.

[0091] In the multi-layer sealant film of the present disclosure, the content ratio 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 above content ratio is preferably 40% by mass or less, more preferably 30% by mass or less. When the content ratio is within the above range, for example, the impact resistance of a laminate using the multi-layer sealant film of the present disclosure can be further improved.

[0092] The thickness of the multi-layer sealant film of the present disclosure is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more. The thickness of the multi-layer sealant film is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. When the thickness is equal to or more than the lower limit, for example, the time required for heat sealing of a packaging container including a laminate using the multi-layer sealant film of the present disclosure can be shortened. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved. When a pouch (particularly a retort pouch) is produced from the laminate, the thickness of the sealant layer is preferably 30 μm or more and 200 μm or less, more preferably 40 μm or more and 100 μm or less, and even more preferably 50 μm or more and 80 μm or less.

[0093] <Composite Elastic Modulus> The composite elastic modulus of the sealant film for laminates of the present disclosure is 500 MPa or more, preferably 600 MPa or more, more preferably 650 MPa or more, and 900 MPa or less, preferably 800 MPa or less, more preferably 850 MPa or less, and is 500 MPa or more and 900 MPa or less. A packaging bag produced using a laminate having a sealant film with a composite elastic modulus within the above range as a sealant layer tends to be excellent in drop-break resistance (impact resistance) and hand-tearability (openability).

[0094] The composite elastic modulus of the sealant film for laminates is measured by a nanoindentation method. Specifically, the composite elastic modulus is measured using a nanoindenter with a cross section of the sealant layer of a laminate using the sealant film as a sealant layer as a measurement surface.

[0095] The above cross section was obtained by folding the laminate into a V shape with the sealant film side on the inside, heat sealing it to a width of 130 mm and a height of 165 mm to produce a bag-like pouch, filling the resulting pouch with 100 mL of water from the opening, heat sealing the opening, and cutting the sealed pouch in the thickness direction after retort sterilization treatment using a hot water method at a retort temperature of 121°C for a retort time of 30 minutes.

[0096] The indenter is pressed into the exposed cross section of the sealant layer, near the center of each layer constituting the sealant layer in the thickness direction of the sealant layer. Specifically, when the sealant layer has a single-layer structure, the location is near the center in the thickness direction of the sealant layer. When the sealant layer has a multi-layer structure, for example, when the sealant layer (sealant film) has a three-layer structure, the locations are three: a position 2 μm inside from the interface with the adhesive layer, near the center, and a position 2 μm inside from the seal surface. In this case, the position 2 μm inside from the seal surface corresponds to the first layer (seal layer), the position near the center corresponds to the second layer (core layer), and the position 2 μm inside from the interface with the adhesive layer corresponds to the third layer (surface layer). Moreover, when the sealant layer has a four-layer structure or more, the vicinity of the center of each layer in the thickness direction of the sealant layer is specified.

[0097] The measurement conditions are as follows. A Berkovich indenter (triangular pyramid indenter) is used as the indenter of the nanoindenter. The indenter is pressed into the sealant layer from the cross section of the sealant layer up to a load of 30 μN over a period of 3 seconds, and is held in that state for 5 seconds. The load is then removed over a period of 3 seconds, and the maximum load P max , contact projection area A at maximum depth pA load-displacement curve is obtained. From the load-displacement curve obtained, the composite elastic modulus is calculated according to the following formula (1).

[0098]

number

[0099] The measurements are performed in a room temperature (23°C) environment. Measurements are performed at five or more points at the same measurement position (the point where the indenter is pressed) on the same cross section. The composite elastic modulus is the arithmetic average of the values ​​measured at the five measurement positions, and is recorded for each layer constituting the sealant layer. Details of the measurement conditions are described in the Examples section.

[0100] When the measured values ​​at three locations in the thickness direction of the sealant layer (sealant film) are the same, the measured value is regarded as the composite elastic modulus of the sealant film for laminates. On the other hand, when the sealant film has a multi-layer structure and the measured values ​​vary in the thickness direction, the value at the thickest part in the cross section of the sealant layer is taken as the composite elastic modulus of the laminate sealant film.

[0101] The composite elastic modulus of the laminate sealant film can be adjusted by the content of additives such as polyethylene, elastomer, etc. Specifically, the greater the content of the additives, the lower the composite elastic modulus can be, and the smaller the content of the additives, the higher the composite elastic modulus can be.

[0102] In addition, when the laminate sealant film contains block polypropylene, the composite elastic modulus of the laminate sealant film can be adjusted by the content of ethylene-propylene rubber (EPR). Specifically, the higher the content of ethylene-propylene rubber (EPR), the lower the composite elastic modulus can be, and the lower the content of ethylene-propylene rubber (EPR), the higher the composite elastic modulus can be.

[0103] <Heat shrinkage rate> The sealant film for laminates of the present disclosure has a heat shrinkage rate in the machine direction (MD direction) after heating at 120°C for 15 minutes of preferably 0% or more, and also preferably 0.5% or less, more preferably 0.4% or less, and even more preferably 0.3% or less, for example 0% or more and 0.5% or less. A packaging bag made using a laminate having a sealant film with a heat shrinkage rate within the above range as a sealant layer shrinks less during heating such as retort sterilization, and is less likely to wrinkle. Furthermore, it tends to be easier to tear by hand after retort treatment, and therefore easier to open.

[0104] The heat shrinkage rate of the laminate sealant film can be adjusted by selecting the type of polypropylene and the content of each component. Regarding the type of polypropylene, block polypropylene has higher heat resistance than random polypropylene, so the heat shrinkage rate can be increased by increasing the content of block polypropylene, and the heat shrinkage rate can be decreased by increasing the content of random polypropylene.

[0105] When the laminate sealant film contains block polypropylene, a high ethylene-propylene rubber (EPR) content reduces heat resistance, so the heat shrinkage rate can be increased by increasing the ethylene-propylene rubber (EPR) content, and the heat shrinkage rate can be decreased by decreasing the EPR content.

[0106] Furthermore, when the sealant film for laminates contains block polypropylene, the heat resistance decreases as the content of additives such as polyethylene and elastomer increases. Therefore, the heat shrinkage rate can be increased by increasing the content of additives, and the heat shrinkage rate can be decreased by decreasing the content.

[0107] <Main melting peak temperature> The main melting peak temperature of the sealant film for laminates of the present disclosure, measured in accordance with JIS K7121:2012, is preferably 140° C. or higher, more preferably 155° C. In a sealant layer using the sealant film for laminates of the present disclosure, the main melting peak temperature is observed to be 140° C. or higher, thereby improving the drop impact resistance of a packaging bag produced using the laminate. In addition, in a sealant layer using the sealant film for laminates of the present disclosure, the main melting peak temperature is observed to be in the range of 155° C. or higher, thereby improving the heat resistance of a packaging bag produced using the laminate.

[0108] The melting peak temperature of the sealant film for laminates is obtained by differential scanning calorimetry (DSC). In the present disclosure, the conditions for measuring the melting peak temperature of the sealant film for laminates are as follows. First, a standing pouch is prepared from a laminate using the sealant film for laminates as a sealant layer, water is filled into the obtained pouch from the opening, the opening is heat-sealed to seal, and then the sealed pouch is subjected to a hot water retort treatment at a retort temperature of 121°C and a retort time of 30 minutes. From the standing pouch after the retort treatment, a sealant film corresponding to the sealant layer in the non-heat-sealed portion is separated as a test piece. In accordance with JIS K7121, the separated sealant film is held at 20°C for 1 minute, and then heated from 20°C to 200°C at a heating rate of 10°C / min to measure the melting peak temperature. At this time, the flow rate of nitrogen gas is 20ml / min. Details of the above conditions are described in the Examples section. The melting peak temperature here means the peak top temperature of the melting peak in a DSC curve.

[0109] The main melting peak temperature means the peak top temperature of the largest melting peak when multiple melting peaks are obtained.

[0110] The main melting peak temperature of the laminate sealant film can be adjusted by the content of ethylene-propylene rubber (EPR) when the sealant layer contains block polypropylene. Specifically, when the laminate sealant film contains block polypropylene, the higher the ethylene-propylene rubber (EPR) content, the more the temperature can be shifted toward the lower temperature side, and the lower the EPR content, the more the temperature can be shifted toward the higher temperature side.

[0111] The sealant film can be produced, for example, by a conventional method. The sealant film can be obtained by mixing the above-mentioned materials by a normal method and forming the resulting mixture into a film by a normal 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 material constituting the sealant film is dried as necessary, and then fed to 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 shape from a die such as a T-die, and the extruded film-like material is rapidly cooled and solidified by a rotating cooling drum or the like, thereby forming a sealant film.

[0112] 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 more and 300°C or less, or 220°C or more and 270°C or less.

[0113] [Laminate] The laminate of the present disclosure comprises a substrate (first substrate) and a sealant layer. The substrate comprises an oriented substrate containing polypropylene as a major component. The sealant layer contains polypropylene as a main component. The laminate of the present disclosure is suitable for packaging material applications.

[0114] The laminate of the present disclosure may include two or more substrates. The laminate of the present disclosure preferably further comprises a second substrate between the first substrate and the sealant layer, and comprises the first substrate, the second substrate, and the sealant layer in this order in the thickness direction.

[0115] The first substrate comprises an oriented substrate containing polypropylene as a major component. The second substrate comprises an oriented substrate containing polypropylene as a major component. The stretched substrate of the first substrate and the stretched substrate of the second substrate may be the same or different. In the following description, the stretched substrate containing polypropylene as a main component is also referred to as "stretched polypropylene substrate."

[0116] In one embodiment, one of the first substrate and the second substrate is a barrier substrate and the other of the first substrate and the second substrate is an oriented polypropylene substrate. In another embodiment, both the first substrate and the second substrate may be a barrier substrate, and both the first substrate and the second substrate may be an oriented polypropylene substrate.

[0117] 3 to 11 are schematic cross-sectional views showing an embodiment of the laminate. 3 includes a barrier substrate 20 as a substrate, an adhesive layer 40, and a sealant layer 30 in this order in the thickness direction. The barrier substrate 20 includes an oriented polypropylene substrate 22 and an inorganic oxide layer 24. In this example, the oriented polypropylene substrate 22 constitutes the outermost layer of the laminate 1, and the inorganic oxide layer 24 is in contact with the adhesive layer 40.

[0118] FIG. 4 is similar to FIG. 3, except that the barrier substrate 20 includes a surface coat layer or surface resin layer 23 between the oriented polypropylene substrate 22 and the inorganic oxide layer 24 .

[0119] 5 is the same as FIG. 3 except that the barrier substrate 20 includes a stretched polypropylene substrate 22, a surface coating layer or surface resin layer 23, an inorganic oxide layer 24, and a covering layer 25 in this order in the thickness direction. In this example, the covering layer 25 contacts the adhesive layer 40.

[0120] 6 includes a stretched polypropylene substrate 10 as a first substrate, an adhesive layer 40A, a barrier substrate 20 as a second substrate, an adhesive layer 40B, and a sealant layer 30, in that order in the thickness direction. The barrier substrate 20 includes a stretched polypropylene substrate 22 and an inorganic oxide layer 24. In this example, the stretched polypropylene substrate 22 is in contact with the adhesive layer 40B, and the inorganic oxide layer 24 is in contact with the adhesive layer 40A.

[0121] FIG. 7 is similar to FIG. 6, except that the barrier substrate 20 includes a surface coat layer or surface resin layer 23 between the oriented polypropylene substrate 22 and the inorganic oxide layer 24 .

[0122] 8 is the same as FIG. 6, except that the barrier substrate 20 includes a stretched polypropylene substrate 22, a surface coating layer or surface resin layer 23, an inorganic oxide layer 24, and a coating layer 25 in this order in the thickness direction. In this example, the coating layer 25 is in contact with the adhesive layer 40A.

[0123] 9 includes a barrier substrate 20 as a first substrate, an adhesive layer 40A, a stretched polypropylene substrate 10 as a second substrate, an adhesive layer 40B, and a sealant layer 30, in that order in the thickness direction. The barrier substrate 20 includes a stretched polypropylene substrate 22 and an inorganic oxide layer 24. In this example, the stretched polypropylene substrate 22 constitutes the outermost layer of the laminate 1, and the inorganic oxide layer 24 is in contact with the adhesive layer 40A.

[0124] FIG. 10 is similar to FIG. 9, except that the barrier substrate 20 includes a surface coat layer or surface resin layer 23 between the stretched polypropylene substrate 22 and the inorganic oxide layer 24 .

[0125] 11 is the same as FIG. 9, except that the barrier substrate 20 includes a stretched polypropylene substrate 22, a surface coating layer or surface resin layer 23, an inorganic oxide layer 24, and a covering layer 25 in this order in the thickness direction. In this example, the covering layer 25 is in contact with the adhesive layer 40A.

[0126] Specific examples of the laminate structure of the laminate of the present disclosure are shown below. " / " indicates the boundary between layers. "OPP film" refers to a stretched polypropylene substrate. (1) OPP film / printing layer / adhesive layer / sealant layer (2) Barrier substrate / printing layer / adhesive layer / sealant layer (3) OPP film / printing layer / adhesive layer / barrier substrate / adhesive layer / sealant layer (4) Barrier substrate / printing layer / adhesive layer / OPP film / adhesive layer / sealant layer (5) Barrier substrate / printing layer / adhesive layer / barrier substrate / adhesive layer / sealant layer (6) OPP film / printing layer / adhesive layer / OPP film / adhesive layer / sealant layer

[0127] In one embodiment, the laminate of the present disclosure comprises at least three elements: a stretched polypropylene substrate, a barrier substrate, and a sealant layer, which can further improve the gas barrier properties (particularly the oxygen barrier properties and water vapor barrier properties).

[0128] When the first substrate is a barrier substrate, in one embodiment, the first substrate is positioned such that the inorganic oxide layer faces the sealant layer and the oriented polypropylene substrate faces away from the sealant layer.

[0129] In one embodiment, when the second substrate is a barrier substrate, the second substrate is arranged so that the inorganic oxide layer faces the first substrate and the stretched polypropylene substrate faces the sealant layer, or the inorganic oxide layer faces the sealant layer and the stretched polypropylene substrate faces the first substrate. Among these, from the viewpoint of further suppressing deterioration of the inorganic oxide layer, when the second substrate is a barrier substrate, it is preferable that the second substrate is arranged so that the inorganic oxide layer faces the first substrate and the stretched polypropylene substrate faces the sealant layer.

[0130] In one embodiment of the laminate of the present disclosure, the first substrate is an oriented polypropylene substrate, and the second substrate is a barrier substrate (see Figs. 6 to 8). In this embodiment, the laminate comprises an oriented polypropylene substrate, a barrier substrate, and a sealant layer in this order in the thickness direction. A laminate having such a configuration has an inorganic oxide layer that is appropriately protected when subjected to heat treatment or the like, and exhibits further high gas barrier properties. Furthermore, the laminate of the above embodiment has a smaller heat shrinkage rate when subjected to heat treatment, and therefore has further excellent suitability for bag formation.

[0131] The proportion of a single polypropylene-based material in the laminate of the present disclosure (hereinafter also referred to as "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, which can improve the recyclability of the packaging container. The higher the mono-material ratio, the more preferable it is, but the upper limit may be, for example, 99% by mass or 98% by mass.

[0132] In this disclosure, the mono-material ratio refers to the ratio of a single polypropylene-based material to the total mass of the laminate. However, when 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.

[0133] <Polypropylene oriented base material> The oriented polypropylene substrate contains polypropylene as a major component. The polypropylene may be any one of homopolypropylene, random polypropylene and block polypropylene, or may be a mixture of two or more selected from these. As the polypropylene, biomass-derived polypropylene and / or recycled polypropylene may be used. The homopolypropylene is a polymer of only propylene. The random polypropylene is a random polypropylene of propylene and α-olefins other than propylene. The block polypropylene is a polypropylene having a polymer block of propylene and a polymer block of at least α-olefins other than propylene. The polymer block of at least α-olefins other than propylene may be a polymer block of propylene and α-olefins other than propylene. The details of the α-olefins are as described above.

[0134] Among polypropylenes, random polypropylene is preferred from the viewpoint of transparency, homopolypropylene is preferred when the rigidity and heat resistance of the packaging bag are important, and block polypropylene is preferred when the impact resistance of the packaging bag is important. In the present disclosure, among these polypropylenes, homopolypropylene and block polypropylene are more preferred from the viewpoint of heat resistance and impact resistance.

[0135] From the viewpoint of film-forming property and processability, the melt flow rate (MFR) of polypropylene is preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, and also preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, for example, 0.1 g / 10 min or more and 50 g / 10 min or less. The MFR of polypropylene is measured in accordance with JIS K7210-1:2014, Method A, under conditions of a temperature of 230° C. and a load of 2.16 kg.

[0136] The polypropylene content in the polypropylene oriented base material is preferably greater than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.

[0137] The oriented polypropylene substrate may contain a resin material other than polypropylene, such as, for example, a polyolefin other than polypropylene, such as polyethylene, an acrylic resin, a vinyl resin, a cellulose resin, a polyamide, a polyester, or an ionomer resin.

[0138] The stretched polypropylene substrate is a polypropylene substrate that has been subjected to a stretching treatment. A laminate including the stretched polypropylene substrate is excellent in, for example, heat resistance, impact resistance, water resistance, and dimensional stability, and is suitable as a packaging material for forming a packaging bag that is to be subjected to, for example, a retort treatment or a boiling treatment. The stretching process may be uniaxial stretching or biaxial stretching. When stretching in the machine direction (flow direction of the substrate, MD direction), the stretching ratio is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less. When stretching in the width direction (direction perpendicular to the MD direction, TD direction), the stretching ratio is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less. By setting the stretching ratio at 2 times or more, the strength and heat resistance of the substrate can be improved, and the printability of the substrate can be improved. From the viewpoint of the breaking limit of the substrate, the stretching ratio is preferably 15 times or less. The oriented polypropylene substrate is, for example, a biaxially oriented substrate.

[0139] The oriented polypropylene substrate may be surface-treated. This can improve the adhesion between the oriented polypropylene substrate and other layers, for example. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the stretched polypropylene substrate.

[0140] The oriented polypropylene substrate may have a single layer structure or a multi-layer structure. The thickness of the stretched polypropylene substrate is preferably 10 μm or more, more preferably 15 μm or more, and also preferably 100 μm or less, more preferably 50 μm or less, for example, 10 μm or more and 100 μm or less. A laminate having a stretched substrate with a thickness equal to or greater than the lower limit has, for example, excellent strength and heat resistance. A laminate having a stretched substrate with a thickness equal to or less than the upper limit has, for example, excellent processability.

[0141] <Barrier substrate> The barrier substrate comprises a stretched polypropylene substrate and an inorganic oxide layer. The barrier substrate comprises, for example, a stretched polypropylene substrate and an inorganic oxide layer provided on one surface of the stretched substrate. The barrier substrate may comprise a surface coating layer between the stretched polypropylene substrate and the inorganic oxide layer. The barrier substrate may comprise a coating layer on the inorganic oxide layer. The barrier substrate may have transparency.

[0142] (Polypropylene oriented base material) The oriented polypropylene substrate in the barrier substrate may be the oriented polypropylene substrate described in the section <oriented polypropylene substrate>. The oriented polypropylene substrate in the first substrate and the oriented polypropylene substrate in the second substrate may be the same or different.

[0143] The stretched polypropylene substrate provided in the barrier substrate may be, for example, a stretched substrate of another embodiment that includes a polypropylene layer, an optional adhesive resin layer, and a surface resin layer described later in this order. In this embodiment, the barrier substrate includes a stretched substrate of another embodiment and an inorganic oxide layer provided on the surface resin layer of the stretched substrate. In this embodiment, the barrier substrate includes a polypropylene layer, an optional adhesive resin layer, a surface resin layer, and an inorganic oxide layer in this order. In one embodiment, the stretched substrate of another embodiment is a coextruded stretched resin film. The coextruded stretched resin film can be produced, for example, by forming a laminated film using a T-die method or an inflation method, and then stretching the laminated film.

[0144] In other embodiments, the stretching treatment of the stretched substrate may be uniaxial stretching or biaxial stretching. The stretching ratio in the MD direction is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less. The stretching ratio in the TD direction is preferably 2 times or more, more preferably 5 times or more, and preferably 15 times or less, more preferably 13 times or less.

[0145] (Surface coating layer) The barrier substrate may include a surface coating layer containing a resin material having a polar group between the stretched polypropylene substrate and the inorganic oxide layer. Such a barrier substrate has excellent adhesion to the inorganic oxide layer and also has excellent gas barrier properties. Such a barrier substrate includes, in this order, a stretched polypropylene substrate, a surface coating layer, and an inorganic oxide layer.

[0146] The polar group refers to a group containing one or more heteroatoms, and examples thereof include ester group, epoxy group, hydroxyl group, amino group, amide group, urethane group, carboxyl group, carbonyl group, carboxylic anhydride group, sulfo group, thiol group, and halogen group. Among these, carboxyl group, carbonyl group, ester group, hydroxyl group, amino group, amide group, and urethane group are preferred, and carboxyl group, hydroxyl group, amide group, and urethane group are more preferred.

[0147] Examples of resin materials having a polar group include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl-containing acrylic resin, polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon, and polyurethane. Among these, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, hydroxyl-containing acrylic resin, polyamide, and polyurethane are more preferred.

[0148] The surface coating layer can be formed, for example, using a water-based emulsion or a solvent-based emulsion. Examples of the water-based emulsion include a polyamide-based emulsion, a polyethylene-based emulsion, and a polyurethane-based emulsion. Examples of the solvent-based emulsion include an acrylic resin-based emulsion and a polyester-based emulsion.

[0149] The content of the resin material having a polar group in the surface coat layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The surface coating layer may contain the above-mentioned resin materials other than the resin material having a polar group. The surface coating layer may contain the above-mentioned additives.

[0150] The ratio of the thickness of the surface coat layer to the total thickness of the polypropylene stretched substrate and the surface coat layer is preferably 0.08% or more, more preferably 0.2% or more, even more preferably 1% or more, and also preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 5% or less, for example, 0.08% or more and 20% or less. The thickness of the surface coat layer is preferably 0.02 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, even more preferably 0.2 μm or more, and also preferably 10 μm or less, more preferably 5 μm or less, for example, 0.02 μm or more and 10 μm or less. When the ratio or thickness is the lower limit or more, for example, the adhesion of the inorganic oxide layer can be improved, the gas barrier property can be improved, and the laminate strength of the laminate can be improved. When the ratio or thickness is the upper limit or less, for example, the processability of the barrier substrate and the recyclability of the laminate can be improved.

[0151] For example, polypropylene or a resin composition containing polypropylene is formed into a film using a T-die method, an inflation method, or the like to obtain a polypropylene substrate, and then the substrate is stretched. A coating liquid for forming a surface coating layer is applied to the obtained stretched substrate, and the substrate is dried, thereby producing a resin substrate having a polypropylene stretched substrate and a surface coating layer.

[0152] (Polypropylene layer, surface resin layer and adhesive resin layer) In another embodiment of the stretched substrate, the polypropylene layer contains polypropylene as a main component. The details of polypropylene are as described above, and will not be described in this section. The content of polypropylene in the polypropylene layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.

[0153] The polypropylene layer may contain the above-mentioned resin materials other than polypropylene. The polypropylene layer may contain the additives described above.

[0154] The polypropylene layer may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene layer is preferably 10 μm or more, more preferably 15 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less, for example, 10 μm or more and 100 μm or less.

[0155] In the first embodiment, the surface resin layer contains a resin material having a melting point of 180° C. or higher (hereinafter also referred to as a “high melting point resin material”). By providing a surface resin layer containing a high melting point resin material between the polypropylene layer and the inorganic oxide layer, for example, the adhesion of the inorganic oxide layer formed on the surface resin layer can be improved, and the gas barrier property can also be improved.

[0156] The melting point of the high melting point resin material is preferably 185°C or higher, more preferably 190°C or higher, and even more preferably 205°C or higher. When the melting point is equal to or higher than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the gas barrier property can be improved, and the laminate strength of the laminate can be improved. The melting point of the high melting point resin material is preferably 265°C or lower, more preferably 260°C or lower, and even more preferably 250°C or lower. This can improve, for example, the film formability of the stretched substrate.

[0157] In this specification, the melting point of the high melting point resin material and the like is measured in accordance with JIS K7121:2012 (Method of measuring transition temperature of plastics). Specifically, a differential scanning calorimetry (DSC) device is used to measure a DSC curve at a heating rate of 10°C / min, and the melting peak temperature is determined as the melting point.

[0158] The high melting point resin material preferably has a polar group. The polar group refers to a group containing one or more heteroatoms, and examples thereof include ester groups, epoxy groups, hydroxyl groups, amino groups, amide groups, urethane groups, carboxy groups, carbonyl groups, carboxylic anhydride groups, sulfo groups, thiol groups, and halogen groups. Among these, hydroxyl groups, ester groups, amino groups, amide groups, carboxy groups, and carbonyl groups are preferred, and amide groups are more preferred.

[0159] The high melting point resin material may have a melting point of 180° C. or higher, and examples of the high melting point resin material include polyolefin, vinyl resin, acrylic resin, polyamide, polyimide, polyester, cellulose resin, and ionomer resin. For example, a resin material having a melting point of 180° C. or higher and a polar group is preferable, and ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyester, and polyamide such as nylon 6 and nylon 6,6 are more preferable.

[0160] In the first embodiment, the content of the high melting point resin material in the surface resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0161] In the second embodiment, the surface resin layer contains a random polypropylene of propylene and an α-olefin other than propylene. By providing a surface resin layer containing the random polypropylene between the polypropylene layer and the adhesive layer or the second adhesive layer, the adhesive strength between the sealant layer and the stretched polypropylene substrate (i.e., the barrier substrate) can be improved, and the impact resistance of the laminate can also be improved.

[0162] Examples of the random polypropylene include propylene-ethylene random polypropylene and propylene-ethylene-butene random polypropylene. Of these, any one or a mixture of two or more can be used as the random polypropylene.

[0163] In the propylene-ethylene random polypropylene, the content of the ethylene-derived structural unit is preferably 2% by mass or more, more preferably 4% by mass or more. 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, the drop impact resistance can be further improved. In the present disclosure, the content of the structural unit can be measured, for example, by a temperature gradient method (TGIC: Thermal Gradient Interaction Chromatography).

[0164] In the propylene-ethylene-butene random polypropylene, the content of ethylene-derived structural units and butene-derived structural units is preferably 2% by mass or more, more preferably 4% by mass or more. The content is preferably 50% by mass or less, more preferably 40% by mass or less.

[0165] In the second aspect, the content of the random polypropylene in the surface resin layer is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount of the surface resin layer. By containing 50% by mass or more of the random polypropylene, the surface resin layer exhibits sufficient adhesion strength.

[0166] The surface resin layer may contain the above-mentioned resin materials other than the high melting point resin material and the random polypropylene of propylene and an α-olefin other than propylene. The surface resin layer may contain the above-mentioned additives. The surface resin layer may be subjected to the above-mentioned surface treatment.

[0167] The ratio of the thickness of the surface resin layer to the total thickness of the stretched substrate of another embodiment having a polypropylene layer and a surface resin layer is preferably 1% or more, more preferably 1.5% or more, and also preferably 10% or less, more preferably 5% or less, for example 1% or more and 10% or less. The thickness of the surface resin layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and also preferably 5 μm or less, more preferably 4 μm or less, for example 0.1 μm or more and 5 μm or less. When the above ratio or thickness is the lower limit or more, for example, the adhesion of the inorganic oxide layer can be improved, the gas barrier property can be improved, and the laminate strength of the laminate can be improved. When the above ratio or thickness is the upper limit or less, for example, the film formability and processability of the stretched substrate of another embodiment, and the recyclability of the laminate can be improved.

[0168] The stretched substrate of another embodiment may have an adhesive resin layer between the polypropylene layer and the surface resin layer. This can improve the adhesion between these layers. The thickness of the adhesive resin layer is, for example, 1 μm or more and 15 μm or less. The adhesive resin layer can be formed, for example, from an adhesive resin. Examples of adhesive resins include polyether, polyester, polyurethane, silicone resin, epoxy resin, vinyl resin, phenolic resin, polyolefin, and acid-modified polyolefin. Among these, polyolefin and its acid-modified polyolefin are preferred from the viewpoint of recyclability of the laminate, and polypropylene and its acid-modified polyolefin are more preferred.

[0169] (Inorganic oxide layer) The barrier substrate comprises an inorganic oxide layer. The inorganic oxide layer contains one or more inorganic oxides, for example, a vapor-deposited film of an inorganic oxide. A laminate comprising a barrier substrate has excellent gas barrier properties, specifically, oxygen barrier properties and water vapor barrier properties. A packaging bag produced using such a laminate can suppress oxidation deterioration of the contents filled in the packaging bag, and suppress the mass loss of the contents. The barrier substrate may, for example, comprise an inorganic oxide layer on a surface coat layer, or may comprise an inorganic oxide layer on a surface resin layer.

[0170] 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.

[0171] In one embodiment, the inorganic oxide is more preferably silica since no aging treatment is required after the formation of the inorganic oxide layer.In one embodiment, the inorganic oxide is more preferably carbon-containing silicon oxide since the deterioration of the gas barrier property can be suppressed even when the laminate is bent.

[0172] The thickness of the inorganic oxide layer is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and is preferably 150 nm or less, more preferably 60 nm or less, even more preferably 40 nm or less, for example, 1 nm or more and 150 nm or less. A laminate having an inorganic oxide layer whose thickness is equal to or greater than the lower limit has, for example, excellent oxygen barrier properties and water vapor barrier properties. A laminate having an inorganic oxide layer whose thickness is equal to or less than the upper limit can, for example, suppress the occurrence of cracks in the inorganic oxide layer and has excellent recyclability.

[0173] The surface of the inorganic oxide layer may be subjected to the above-mentioned surface treatment.

[0174] Methods for forming inorganic oxide layers, particularly inorganic oxide vapor deposition films, include, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0175] The inorganic oxide layer may be a single layer formed by one deposition process, or may be a multilayer formed by multiple deposition processes. When the inorganic oxide layer is a multilayer, each layer may be composed of the same inorganic oxide or different inorganic oxides. Each layer may be formed by the same method or different methods.

[0176] The inorganic oxide layer is preferably a vapor-deposited film formed by a CVD method, and more preferably a carbon-containing silicon oxide vapor-deposited film formed by a CVD method. A laminate including such an inorganic oxide layer has, for example, excellent bending resistance.

[0177] The carbon-containing silicon oxide vapor deposition film contains silicon, oxygen and carbon. In one embodiment of the carbon-containing silicon oxide vapor deposition film, the carbon ratio C is preferably 3% or more, more preferably 5% or more, even more preferably 10% or more, and is preferably 50% or less, more preferably 40% or less, even more preferably 35% or less, for example, 3% or more and 50% or less, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the carbon ratio C in the above range, for example, even if the laminate is bent, the deterioration of the gas barrier property can be suppressed. In this specification, the ratio of each element is on a molar basis.

[0178] In one embodiment of the carbon-containing silicon oxide vapor deposition film, the silicon ratio Si is preferably 1% or more, more preferably 3% or more, even more preferably 8% or more, and is preferably 45% or less, more preferably 38% or less, even more preferably 33% or less, for example 1% or more and 45% or less, relative to the total of the three elements silicon, oxygen and carbon 100%. The oxygen ratio O is preferably 10% or more, more preferably 20% or more, even more preferably 25% or more, and is preferably 70% or less, more preferably 65% ​​or less, even more preferably 60% or less, for example 10% or more and 70% or less, relative to the total of the three elements silicon, oxygen and carbon 100%. By setting the silicon ratio Si and the oxygen ratio O in the above ranges, for example, even if the laminate is bent, the deterioration of the gas barrier property can be further suppressed.

[0179] In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the oxygen ratio O is preferably higher than the carbon ratio C, and the silicon ratio Si is preferably lower than the carbon ratio C. The oxygen ratio O is preferably higher than the silicon ratio Si, that is, the ratios are preferably in the order of O, C, and Si. This makes it possible to further suppress the deterioration of the gas barrier properties even when the laminate is bent, for example.

[0180] The proportions C, Si, and O in the carbon-containing silicon oxide vapor-deposited film are measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the following measurement conditions.

[0181] (Measurement conditions) Equipment used: "ESCA-3400" (manufactured by Kratos) [1] Spectral collection conditions Incident X-ray: MgKα (non-monochromatic X-ray, hν=1253.6eV) X-ray output: 150W (10kV 15mA) Measurement area: approx. 6mmφ Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar+ Ar gas introduction pressure: 2.0×10-2 Pa Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Ion sputtering time: 30 seconds, spectrum collected

[0182] (covering layer) The barrier substrate may further include a coating layer on the inorganic oxide layer. That is, the barrier substrate may further include a coating layer on the surface of the inorganic oxide layer opposite to the surface facing the stretched polypropylene substrate. A laminate including such a barrier substrate has, for example, excellent oxygen barrier properties and water vapor barrier properties.

[0183] In one embodiment, the coating layer contains a resin component. Examples of the resin component include polyolefins such as polyethylene, polypropylene, polybutene, and polymethylpentene, vinyl resins, acrylic resins, polyesters, urethane resins, melamine resins, and epoxy resins. The content of the resin component in the coating layer is preferably more than 50% by mass, more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, for example, more than 50% by mass and 95% by mass or less. The coating layer may contain the above-mentioned additives.

[0184] The thickness of the coating layer is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 5 μm or less, more preferably 3 μm or less, even more preferably 1 μm or less, for example, 0.01 μm or more and 5 μm or less. Such a coating layer has, for example, excellent scratch resistance.

[0185] The coating layer can be formed, for example, by applying a coating liquid for the coating layer to the surface of the inorganic oxide layer and drying it. The coating liquid for the coating layer can be prepared, for example, by mixing the above-mentioned resin component and, if necessary, an additive and a solvent. Details of these components are as described above. Examples of the coating method for the coating liquid for the coating layer include known coating methods. Examples of the drying method for the applied coating liquid for the coating layer include methods that apply heat, such as hot air drying, hot roll drying, and infrared irradiation. The drying temperature may be 50°C or higher, or 150°C or lower.

[0186] In one embodiment, the coating layer may be a barrier coat layer containing a gas barrier resin. Examples of the gas barrier resin include ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyamide such as nylon 6, nylon 6,6 and polymetaxylylene adipamide, polyurethane, and acrylic resin. The content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Such a barrier coat layer has, for example, excellent gas barrier properties. The barrier coat layer may contain the above-mentioned additives.

[0187] The thickness of the barrier coat layer containing the gas barrier resin is preferably 0.01 μm or more, more preferably 0.1 μm or more, and also preferably 10 μm or less, more preferably 5 μm or less, for example, 0.01 μm or more and 10 μm or less. A barrier substrate having a barrier coat layer whose thickness is equal to or greater than the lower limit has, for example, excellent gas barrier properties. A barrier substrate having a barrier coat layer whose thickness is equal to or less than the upper limit can improve, for example, the processability and recyclability of the laminate.

[0188] The barrier coat layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent, applying the resulting coating liquid to the surface of the inorganic oxide layer, and drying it. The barrier coat layer can also be formed, for example, by applying a commercially available barrier coating agent and drying it.

[0189] In one embodiment, the coating layer may be a gas barrier coating film formed by polycondensing a composition containing a metal alkoxide and a water-soluble polymer by a sol-gel method in the presence of a sol-gel catalyst, water, an organic solvent, and the like. A barrier substrate having a gas barrier coating film on an inorganic oxide layer has, for example, excellent gas barrier properties. The gas barrier coating film includes a hydrolysis polycondensate obtained by hydrolyzing and polycondensing the metal alkoxide or the like by a sol-gel method. By providing such a gas barrier coating film on an inorganic oxide layer, for example, the occurrence of cracks in the inorganic oxide layer can be effectively suppressed.

[0190] The metal alkoxide is represented, for example, by the formula (1). R 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 atomic valence of M. 1 and R 2 In the above, examples of the organic group include alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, and n-octyl. The metal atom M is, for example, silicon, zirconium, titanium, or aluminum. Examples of the metal alkoxide include alkoxysilanes, such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0191] Examples of the water-soluble polymer include hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination, depending on the desired physical properties such as oxygen barrier property, water vapor barrier property, water resistance, and weather resistance. Also, a gas barrier coating film obtained using polyvinyl alcohol and a gas barrier coating film obtained using ethylene-vinyl alcohol copolymer may be laminated. The amount of the water-soluble polymer used is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 500 parts by mass or less, based on 100 parts by mass of the metal alkoxide.

[0192] A silane coupling agent may be used together with the metal alkoxide. As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and an organoalkoxysilane having an epoxy group is preferable, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane can be mentioned. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the metal alkoxide.

[0193] The gas barrier composition may contain water in a ratio of preferably 0.1 mol or more, more preferably 0.5 mol or more, and preferably 100 mol or less, more preferably 60 mol or less, per mol of metal alkoxide. By making the water content equal to or greater than the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved. By making the water content equal to or less than the upper limit, for example, the hydrolysis reaction can be carried out quickly.

[0194] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butyl alcohol.

[0195] The sol-gel catalyst is preferably an acid or an amine compound. Examples of the acid include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less per mol of the total amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

[0196] As the amine compound, the tertiary amine that is substantially insoluble in water and soluble in organic solvent is suitable, for example, N,N-dimethylbenzylamine, tripropylamine, tributylamine and tripentylamine can be mentioned.The amount of the amine compound used is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and also preferably 1.0 parts by mass or less, more preferably 0.3 parts by mass or less, based on 100 parts by mass of the total amount of metal alkoxide and silane coupling agent.

[0197] Examples of methods for applying the gas barrier composition include application means such as roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

[0198] Hereinafter, one embodiment of the method for forming a gas barrier coating film will be described. A gas barrier composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent. A polycondensation reaction gradually proceeds in the composition. The composition is applied on an inorganic oxide layer by a conventional method and dried. This drying causes further polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains a silane coupling agent) to form a composite polymer layer. The above operation may be repeated to laminate a plurality of composite polymer layers. For example, the applied composition is heated at a temperature of preferably 20° C. or higher, more preferably 50° C. or higher, and even more preferably 70° C. or higher, and also at a temperature of preferably 150° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower for 1 second to 10 minutes. This allows the formation of a gas barrier coating film.

[0199] The thickness of the gas barrier coating film is preferably 0.01 μm or more, more preferably 0.1 μm or more, and is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less, for example, 0.01 μm or more and 2 μm or less, which can improve the gas barrier property, suppress the occurrence of cracks in the inorganic oxide layer, and improve the recyclability of the packaging bag.

[0200] <Print layer> The laminate of the present disclosure may include a printed layer on the surface of a substrate such as a first substrate and a second substrate, and between any layers. The image formed on the printed layer is not particularly limited, and may be a character, a pattern, a symbol, or a combination thereof. The printed layer may be formed using an ink derived from biomass. This can further reduce the environmental load.

[0201] Examples of methods for forming the printed layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of reducing the environmental load. The thickness of the printed layer is, for example, not less than 0.5 μm and not more than 3 μm.

[0202] <Adhesive layer> In one embodiment, the laminate of the present disclosure comprises an adhesive layer between the substrate and the sealant layer. In one embodiment, the laminate of the present disclosure comprises a first adhesive layer between the first substrate and the second substrate. In one embodiment, the laminate of the present disclosure comprises a second adhesive layer between the second substrate and the sealant layer. Such a laminate has excellent lamination strength, for example, between the substrate / sealant layer, between the first substrate / second substrate, and between the second substrate / sealant layer.

[0203] (glue) The adhesive layer, the first adhesive layer, and the second adhesive layer are each composed of an adhesive. The adhesive forming the first adhesive layer and the adhesive forming the second adhesive layer may be the same or different. The adhesive may be any of a one-component curing adhesive, a two-component curing adhesive, and a non-curing adhesive, and a two-component curing adhesive is preferred from the viewpoint of easily adjusting the elastic modulus of the adhesive layer to a required range.

[0204] A method for obtaining a laminate using an adhesive includes a method in which an adhesive is applied to an object, and then another object is placed on the formed adhesive layer, and the adhesive layer sandwiched between the two is allowed to harden. Examples of the object include a first substrate, a second substrate, and a sealant film. The process of allowing the adhesive layer to harden is also referred to as the "aging process" below.

[0205] The aging conditions of the adhesive are described below. The aging temperature is preferably 25°C or higher, more preferably 30°C or higher, and even more preferably 35°C or higher, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower. The aging time is preferably 5 hours or higher, more preferably 10 hours or higher, and even more preferably 20 hours or higher, and is preferably 150 hours or lower, more preferably 135 hours or lower, and even more preferably 120 hours or lower. By increasing the aging temperature, the elastic modulus of the adhesive layer tends to increase. By increasing the aging time, the elastic modulus of the adhesive layer tends to increase.

[0206] Examples of adhesives include polyurethane adhesives, polyester adhesives, polyether adhesives, rubber adhesives, vinyl adhesives, olefin adhesives, silicone adhesives, epoxy adhesives, and phenol adhesives. Among these, from the viewpoint of easily adjusting the elastic modulus to the above-mentioned range, polyurethane adhesives, polyester adhesives, and polyether adhesives are preferred, polyurethane adhesives and polyester adhesives are more preferred, polyurethane adhesives are even more preferred, and two-liquid curing polyurethane adhesives are particularly preferred.

[0207] The adhesive may be a solvent-based adhesive or a solventless adhesive. A solvent-based adhesive is an adhesive used in a method in which the adhesive is applied to an object, heated in an oven or the like to volatilize the solvent in the adhesive, and then the adhesive is bonded to another object. In the case of a two-liquid curing adhesive, either the base agent or the curing agent, or both, contain a solvent. Examples of the solvent include organic solvents, specifically, hydrocarbon solvents such as toluene, xylene, n-hexane, and methylcyclohexane; ester solvents such as ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate; alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol; and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0208] A solvent-free adhesive is an adhesive that is applied to an object and then bonded to another object without necessarily going through a process of heating in an oven or the like to volatilize the solvent. In the case of a two-component curing adhesive, both the base agent and the curing agent are substantially free of solvent. "Substantially free of solvent" includes cases where the solvent used as a reaction medium during the manufacture of the adhesive's components, or the base agent and / or curing agent in the case of a two-component curing adhesive, is not completely removed, leaving trace amounts of solvent remaining in the adhesive, or the base agent and / or curing agent in the case of a two-component curing adhesive.

[0209] The two-component curing polyurethane adhesive has a base agent and a curing agent. The two-component curing polyurethane adhesive may be a solvent-based adhesive or a solventless adhesive. The two-component curing polyurethane adhesive will be described below.

[0210] The polyurethane adhesive has, for example, a base agent containing a polyol compound and a curing agent containing a polyisocyanate compound. Examples of the cured product (reaction product) formed by mixing such a base agent and a curing agent include polyurethane, specifically polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, and acrylic polyurethane.

[0211] The polyol compound has two or more hydroxyl groups in one molecule. Examples of the polyol compound include polyester polyurethane polyol, polyester polyol, polyether polyol, polycarbonate polyol and acrylic polyol. Among these, polyester polyurethane polyol and polyester polyol are preferred from the viewpoint of easily obtaining an adhesive layer having an elastic modulus in the above-mentioned range, and in the case of a solvent-based adhesive, polyester polyurethane polyol is more preferred, and in the case of a solventless adhesive, polyester polyol is more preferred.

[0212] Polyester polyurethane polyol is a compound having two or more hydroxy groups, ester bonds, and urethane bonds in one molecule, and has, for example, a polyester polyurethane structure as the main skeleton. Polyester polyol is a compound having two or more hydroxy groups and ester bonds in one molecule, and has, for example, a polyester structure as the main skeleton. Polyether polyol is a compound having two or more hydroxy groups and ether bonds in one molecule. Polycarbonate polyol is a compound having two or more hydroxy groups and carbonate bonds in one molecule.

[0213] The weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the base of the two-component curing and solvent-based adhesive is, from the viewpoint of coatability, preferably 11,000 or more, more preferably 13,000 or more, even more preferably 15,000 or more, even more preferably 18,000 or more, particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 40,000 or less. The smaller the Mw, the higher the elastic modulus of the adhesive layer tends to be, and the larger the Mw, the lower the elastic modulus of the adhesive layer tends to be. The polydispersity (Mw / Mn) of the polymer component (e.g., polyol compound) contained in the base material is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less, and is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more. Here, Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base material. Each average molecular weight is measured by gel permeation chromatography (GPC) in accordance with JIS K7252-1:2016 and is a value converted into polystyrene.

[0214] From the viewpoint of coatability, the weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the base agent of the two-component curing solventless adhesive is preferably 800 or more, more preferably 1,200 or more, and even more preferably 2,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less, and even more preferably 6,000 or less. The smaller the Mw, the higher the elastic modulus of the adhesive layer tends to be, and the larger the Mw, the lower the elastic modulus of the adhesive layer tends to be. The polydispersity (Mw / Mn) of the polymer component (e.g., polyol compound) contained in the base agent is preferably 2.8 or less, more preferably 2.7 or less, even more preferably 2.6 or less, particularly preferably 2.5 or less, and is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 2.0 or more, where Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent.

[0215] The polyisocyanate compound has two or more isocyanate groups in one molecule. Examples of the polyisocyanate compound include aromatic isocyanates and aliphatic isocyanates. The polyisocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known and conventional appropriate method.

[0216] Examples of polyisocyanate compounds include aliphatic isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), norbornene diisocyanate, and isophorone diisocyanate (IPDI); aromatic isocyanate compounds such as diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate, tolylene diisocyanate (TDI), naphthalene diisocyanate, and α,α,α',α'-tetramethyl-m-xylylene diisocyanate, dimers and trimers (e.g., isocyanurate bodies) derived from these compounds; and adducts, biuret bodies, and allophanate bodies obtained by reacting these compounds with low-molecular-weight active hydrogen compounds or their alkylene oxide adducts, or high-molecular-weight active hydrogen compounds.

[0217] Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexamethylene glycol, 1,8-octamethylene glycol, 1,4-cyclohexanedimethanol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine and metaxylylenediamine, and trimethylolpropane is preferred. Examples of high molecular weight active hydrogen compounds include polyester, polyether polyol and polyamide.

[0218] The base agent containing a polyol compound and the curing agent containing a polyisocyanate compound are preferably used in such an amount ratio that the molar ratio (NCO / OH) between the total isocyanate groups of the polyisocyanate compound and the total hydroxyl groups of the polyol compound is as follows. That is, the molar ratio (NCO / OH) is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.5 or more, and is preferably 8.0 or less, more preferably 6.0, even more preferably 5.0 or less, and in the case of a solventless adhesive, it is even more preferably 4.0 or less, particularly preferably 3.0 or less. The larger the molar ratio (NCO / OH), the higher the elastic modulus of the adhesive layer tends to be, and the smaller the molar ratio (NCO / OH), the lower the elastic modulus of the adhesive layer tends to be.

[0219] <Sealant layer> The laminate of the present disclosure includes the above-mentioned sealant film for laminates of the present disclosure as a sealant layer. This makes it possible to improve the impact resistance after retort treatment in a laminate using the sealant film for laminates of the present disclosure as a sealant layer.

[0220] By containing random polypropylene and block polypropylene as the main components of the sealant layer (sealant film for laminates), for example, it is possible to make the packaging container mono-material. Random polypropylene and block polypropylene are considered to be polypropylene in the calculation of the mono-material ratio. This makes it unnecessary to separate the base material (first base material, second base material) and the sealant layer after collecting used packaging containers, improving the recyclability of the packaging containers.

[0221] The sealant layer may contain the above-mentioned additives. The sealant layer may be subjected to the above-mentioned surface treatment.

[0222] <Adhesive layer> In one embodiment, the laminate comprises an adhesive layer between the substrate (first substrate) and the sealant layer. In one embodiment, the laminate comprises a first adhesive layer between the first substrate and the second substrate. In one embodiment, the laminate comprises 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.

[0223] 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. Thereby, when the laminate is manufactured using an adhesive, the laminate can be manufactured without directly applying the adhesive onto the vapor-deposited film, and deterioration of the vapor-deposited film can be suppressed.

[0224] 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.

[0225] In one embodiment, the solvent-free adhesive is a two-component curing adhesive having a base agent and a curing agent. 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, from the viewpoint of coating suitability. 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.

[0226] 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-liquid curing polyurethane-based adhesives are more preferred.

[0227] In one embodiment, by forming an adhesive layer using a solvent-free adhesive, for example, the amount of residual solvent in the laminate, specifically the amount of residual organic solvent, can be further reduced. The laminate of the present disclosure includes a polypropylene resin layer. Therefore, when the laminate of the present disclosure is produced using a solvent-based adhesive, it is necessary to lower the temperature during drying in order to prevent deterioration and thermal shrinkage of the laminate, compared to polyester-based laminates. In this case, the solvent in the adhesive may not be sufficiently volatilized and removed, remaining in the laminate, and an odor due to the residual solvent may remain. By using a solvent-free adhesive, the amount of residual solvent can be further reduced.

[0228] 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.

[0229] 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 the polypropylene content in the entire laminate to be further increased. Such a laminate is suitable for producing a mono-material packaging container.

[0230] 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.

[0231] The method for producing the laminate of the present disclosure is not particularly limited, and the laminate 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.

[0232] The two-component curing polyurethane adhesive will be described below. As the polyurethane adhesive, for example, an adhesive having a base agent containing a polyol compound such as polyester polyol and a curing agent containing an isocyanate compound is preferable. Examples of the polyol compound include polyester polyol, polyether polyol, polycarbonate polyol, and (meth)acrylic polyol. Among these, polyester polyol is preferred.

[0233] The polyester polyol has two or more hydroxyl groups in one molecule. The polyester polyol has, for example, a polyester structure or a polyester polyurethane structure as a main skeleton. The polyester polyol is obtained, for example, by a dehydration condensation reaction, an ester exchange reaction, or a ring-opening reaction between a polyhydric alcohol component and a polycarboxylic acid component.

[0234] 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.

[0235] Examples of the polycarboxylic acid component include aliphatic polycarboxylic acids, alicyclic polycarboxylic acids, and aromatic polycarboxylic acids, as well as their ester derivatives and acid anhydrides. Examples of the aliphatic polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane dicarboxylic acid, maleic acid, fumaric acid, and dimer acid. Examples of the alicyclic polycarboxylic acids include 1,3-cyclopentane dicarboxylic acid and 1,4-cyclohexane dicarboxylic acid. Examples of the aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, naphthalenedicarboxylic acid, naphthalic acid, biphenyl dicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid.

[0236] 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.

[0237] From the viewpoint of coating suitability, the weight average molecular weight (Mw) of the polyol compound such as polyester polyol is preferably 800 to 10,000, more preferably 1,200 to 4,000. The polydispersity (Mw / Mn) of the polyol compound such as polyester polyol is preferably 2.8 or less, more preferably 1.2 to 2.7, even more preferably 1.5 to 2.6, and particularly preferably 2.0 to 2.5. 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.

[0238] 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 and conventional appropriate method.

[0239] 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.

[0240] 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.

[0241] [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.

[0242] The packaging container of the present disclosure includes the laminate of the present disclosure (hereinafter, simply referred to as "laminate"). Examples of the packaging container include a packaging bag, a tube container, and a container with a lid. The container with a lid includes 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.

[0243] In one embodiment, the packaging container of the present disclosure maintains gas barrier properties even when subjected to high-temperature treatment and is only slightly deformed, and is therefore suitable as a heat sterilization pouch or a microwave-compatible packaging bag. Here, the microwave-compatible packaging bag refers to a packaging container that can be heated using a microwave oven.

[0244] Examples of heat sterilization pouches include pouches that have been retorted (hereinafter also referred to as "retort pouches"), pouches that have been boiled (hereinafter also referred to as "boiled pouches"), and pouches that have been pasteurized (hereinafter "pasteurization pouches"). A retort pouch is a packaging container that has been filled with contents such as food or drink and sealed, and then heat sterilized (retort treatment) with water or steam at a temperature exceeding 100°C under pressure. A boiled pouch or pasteurization pouch is a packaging container that has been filled with contents such as food or drink and sealed, and then boiled at a temperature of 100°C or less.

[0245] In one embodiment, the packaging container of the present disclosure is a retort pouch. There are various conditions for the retort treatment, but any pouch that has undergone general retort treatment is included in the retort pouch. Among the retort treatments, for example, a treatment temperature of 105°C or higher and 115°C or lower may be called semi-retort treatment, a treatment temperature of more than 115°C and 121°C or lower may be called retort treatment, and a treatment temperature of more than 121°C and 140°C or lower may be called high retort treatment. The retort treatment time is, for example, from 5 minutes to 60 minutes, and preferably from 15 minutes to 40 minutes.

[0246] The oxygen permeability (unit: cc / m 2 In one embodiment, the oxygen permeability (day atm) is preferably 2.0 or less, more preferably 1.5 or less, further preferably 1.3 or less, and particularly preferably 1.0 or less. The oxygen permeability is measured in accordance with JIS K7126-2:2006 at a temperature of 23°C and a relative humidity of 90%. The lower limit of the oxygen permeability is preferably as low as possible, but may be, for example, 0.1.

[0247] Examples of heat sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0248] Examples of packaging containers include packaging containers of various types, such as standing pouch type, side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, palm seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.

[0249] 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.

[0250] The packaging container may include a steam release mechanism configured to communicate between the inside and outside of the packaging container when steam pressure inside the packaging container reaches or exceeds a predetermined value, to release steam, and to suppress the steam from escaping at locations other than the steam release mechanism.

[0251] 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 a non-seal portion that is isolated from the content storage portion by the steam release seal portion. The non-seal portion communicates with the outside of the packaging container. The packaging container filled with the content and with the opening heat-sealed is heated using a microwave oven or the like. This increases the internal pressure and causes the steam release seal portion to peel off. Steam passes through the peeled-off portion of the steam release seal portion and the non-seal portion to escape to the outside of the packaging container.

[0252] In one embodiment, a packaging bag can be produced by folding the laminate of the present disclosure in half and stacking them so that the base material is on the outside and the sealant layer is on the inside, and then heat-sealing the ends, etc. In another embodiment, a packaging bag can be produced by stacking multiple laminates of the present disclosure so that the sealant layers face each other, and then heat-sealing the ends, etc. The entire packaging bag may be made of the above-mentioned laminate, or only a part of the packaging bag may be made of the above-mentioned laminate.

[0253] 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.

[0254] The contents 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 medicines. After the contents are contained in the packaging container, the packaging container can be hermetically sealed by heat sealing the opening of the packaging container. The contents may be heat-sterilized foods (heat-sterilized foods such as retort foods, boiled foods, and pasteurized beverages). The packaging bag of the present disclosure may be a pouch that contains heat-sterilized foods.

[0255] As specific examples of packaging containers, a small bag and a standing pouch will be described below. A sachet is a small packaging bag used to hold contents of, for example, 1 g to 200 g. Examples of contents that can be held in a sachet include sauces, soy sauce, dressings, ketchup, syrups, cooking alcohol, other liquid or viscous seasonings, liquid soups, powdered soups, fruit juices, spices, liquid beverages, jelly-like beverages, instant foods, and other foods and beverages.

[0256] The stand-up pouch is used to store contents of, for example, 50 g to 2000 g. Examples of contents that can be stored in the stand-up pouch include shampoo, rinse, conditioner, hand soap, body soap, air freshener, deodorant, insect repellent, detergent, dressing, edible oil, mayonnaise, other liquid or viscous seasonings, liquid beverages, jelly-like beverages, instant foods, other foods and beverages, and creams.

[0257] 12 shows a packaging bag 50 obtained by bonding two laminates together. The shaded areas indicate the heat-sealed areas. The packaging bag 50 may have an easy-to-open part 51. Examples of the easy-to-open part 51 include a notch part 52 that serves as a starting point for tearing, and a half-cut line 53 formed by laser processing or a cutter as a path for tearing.

[0258] FIG. 13 shows a simplified example of the configuration of a standing pouch. The shaded areas indicate the heat-sealed areas. In one embodiment, the standing pouch 60 comprises a body portion (side sheets) 61 and a bottom portion (bottom sheet) 62. The side sheets 61 and the bottom sheet 62 may be made of the same material or different materials. The bottom sheet 62 retains the shape of the side sheets 61, thereby imparting self-supporting properties to the pouch, and the pouch can be made into a standing pouch. A storage space for storing contents is formed within the area surrounded by the side sheets 61 and the bottom sheet 62.

[0259] The standing pouch 60 may include a steam release mechanism 63. The steam release mechanism 63 includes a steam release seal portion 63a protruding from the side seal portion toward the inside of the packaging container, and a non-seal portion 63b isolated from the content-accommodating portion by the steam release seal portion 63a. The non-seal portion 63b communicates with the outside of the packaging container.

[0260] 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.

[0261] In one embodiment, the side sheet can be formed by making a bag so that the sealant layer of the laminate of the present disclosure is the innermost layer. In one embodiment, the side sheet can be formed by preparing two sheets of the laminate of the present disclosure, overlapping them so that the sealant layers face each other, and heat-sealing the side edges on both sides to make a bag.

[0262] In another embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, inserting two laminates folded in a V-shape with the sealant layers facing outward between the laminates at the side edges on both sides of the overlapped laminates, and heat sealing them. According to this production method, a standing pouch having a body with side gussets can be obtained.

[0263] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower parts of the side sheets that have been made into a bag, and heat sealing the laminate. More specifically, the bottom sheet can be formed by inserting the laminate folded in a V-shape with the sealant layer facing outward between the lower parts of the side sheets that have been made into a bag, and heat sealing the laminate.

[0264] In one embodiment, two sheets of the laminate are prepared, and these are stacked so that the sealant layers face each other, and then another sheet of the laminate is folded in a V shape so that the sealant layer faces outward, and this is sandwiched under the laminate that faces each other, and heat-sealed to form a bottom. Next, two sides adjacent to the bottom are heat-sealed to form a body. In this way, a standing pouch of one embodiment can be formed.

[0265] [Mechanism of action] When a laminate containing 80% or more by mass of a single polypropylene material (hereinafter referred to as a propylene-based laminate) is used as a packaging material, the propylene-based laminate is subjected to heat sterilization treatment such as retort treatment, boiling treatment, etc. Therefore, the propylene-based laminate is required to have drop impact resistance (impact resistance) that can withstand the impact of a pouch being dropped after heat treatment such as retort treatment, and hand tearability (openability) that allows easy tearing by hand after retort treatment.

[0266] Therefore, it was found that the elastic modulus of the sealant film can be reduced by keeping the polypropylene content at 40% by mass or more and lowering the polypropylene content by adding polyethylene, elastomer, etc., thereby improving the drop impact resistance. That is, by using a sealant film for laminates that contains 40% by mass or more of polypropylene with respect to the total amount of the sealant film and has a composite elastic modulus of 500 MPa or more and 900 MPa or less as measured by the nanoindentation method as a sealant layer, it contributes to improving the drop impact resistance (impact resistance) and hand tearability (openability) of the laminate.

[0267] The present disclosure relates to, for example, the following [1] to

[11] . [1] A sealant film for use in a laminate in which the content of polypropylene in the total amount of resin material is 80% by mass or more, The sealant film contains 40% by mass or more of polypropylene based on the total amount of the sealant film, The sealant film has a composite elastic modulus of 500 MPa or more and 900 MPa or less as measured by a nanoindentation method. [2] The sealant film for laminates described in [1], wherein the sealant film contains polyethylene. [3] The sealant film for laminates according to [1] or [2], wherein the sealant film contains an ethylene-propylene elastomer. [4] The sealant film for laminates according to any one of [1] to [3], which contains a propylene-ethylene elastomer or an ethylene-α-olefin elastomer. [5] The sealant film for laminates according to any one of [1] to [4], which, when used in the laminate, comprises at least a first layer located on one of the surfaces of the laminate, and a second layer in contact with the first layer. [6] The sealant film for laminates described in [5], further comprising a third layer in contact with the second layer. [7] The sealant film for laminates according to any one of [1] to [6], which has a thickness of 30 μm or more and 200 μm or less. [8] A laminate for use in packaging materials, comprising: At least a first substrate and a sealant layer, The sealant layer is made of the sealant film for laminates according to any one of [1] to [7], A laminate, the content of polypropylene being 80 mass% or more relative to the total amount of resin materials. [9] The laminate described in [8], further comprising a second substrate between the first substrate and the sealant layer.

[10] A packaging container comprising the laminate described in [8] or [9].

[11] The packaging container according to

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

[0268] [Example 1] <Sealant film for laminates> Resin composition 1 for the first layer containing 100% by mass of random PP, resin composition 2 for the second layer containing 85% by mass of block PP and 15% by mass of PE, and resin composition 3 for the third layer containing 100% by mass of random PP, each having the compositions shown below, were simultaneously extruded through a multi-layer die to obtain an unstretched multi-layer film (hereinafter also referred to as "sealant film 1") with first layer / second layer / third layer thicknesses of 5 μm / 50 μm / 5 μm.

[0269] [polypropylene] Block PP: Propylene-ethylene block copolymer (polymer part (a) made of homo-PP: 80%, polymer part (b) made of ethylene propylene rubber (EPR): 20%, MFR: 2.3g / 10min) Random PP: Propylene-ethylene random copolymer (MFR: 6g / 10min, density: 0.890g / cm 3 ) [polyethylene] PE: Linear low-density polyethylene (MFR: 2.0 g / 10 min, density: 0.919 g / cm 3 ) [Thermoplastic elastomer] Elastomer: Propylene-α-olefin copolymer (melting point: 98°C, MFR (190°C): 3.0g / 10min, MFR (230°C): 7.0g / 10min)

[0270] <Barrier substrate> A hydroxyl group-containing (meth)acrylic resin (number average molecular weight: 25,000, glass transition temperature: 99°C, hydroxyl value: 80mgKOH / g) was diluted with a mixed solvent of methyl ethyl ketone and ethyl acetate (mixing ratio 1:1) until the solid content concentration was 10% by mass to prepare a base material. An ethyl acetate solution containing tolylene diisocyanate (solid content 75% by mass) was added to the base material as a curing agent to obtain a solution for forming a surface coating layer. The amount of the curing agent used was 10 parts by mass relative to 100 parts by mass of the base material.

[0271] A biaxially stretched polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) having a thickness of 20 μm and having one surface subjected to a corona treatment was prepared. The above-mentioned solution for forming a surface coating layer was applied to the corona-treated surface of the film and dried to form a surface coating layer having a thickness of 0.5 μm, thereby obtaining a resin substrate.

[0272] A carbon-containing silicon oxide (silica) vapor deposition film with 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 while applying tension to the resin substrate (CVD method). The vapor deposition film formation conditions were as follows:

[0273] (Formation conditions) Hexamethyldisiloxane:oxygen gas:helium=1:10:10 (unit: slm) Cooling / electrode drum power supply: 22kW Line speed: 100m / min

[0274] 385g of water, 67g of isopropyl alcohol, and 9.1g of 0.5N hydrochloric acid were mixed to obtain a solution with a pH of 2.2. 175g of tetraethoxysilane as a metal alkoxide and 9.2g of glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed into this solution while cooling to 10°C to obtain solution A. 14.7g of polyvinyl alcohol with a saponification value of 99% or more and a polymerization degree of 2400 as a water-soluble polymer, 324g of water, and 17g of isopropyl alcohol were mixed to obtain solution B.

[0275] 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 on the deposition film formed on the resin substrate by spin coating, and heat-treated in an oven at 80°C for 60 seconds to form a barrier coating layer with a thickness of 300 nm. In this manner, a barrier substrate was obtained.

[0276] <Preparation of Laminate> As the first substrate, a biaxially oriented polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) having a thickness of 20 μm and having one surface corona-treated was prepared. A printed layer having a coating thickness of 1 μm (when dry) 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 dry), and the substrate was dry laminated so that the barrier coat layer surface of the barrier substrate was in contact with the adhesive layer surface.

[0277] The non-barrier coat layer surface of the barrier substrate used as the second substrate (intermediate substrate) was subjected to corona treatment, and a two-component curing polyurethane adhesive (RU-004 / H-1, manufactured by Rock Paint Co., Ltd.) was coated to a coating thickness of 3.5 μm (when dry) using the gravure roll coating method, and then sealant film 1 was dry laminated with the third layer facing the adhesive layer surface.

[0278] In this way, a laminate with a thickness of about 109 μm was obtained. The laminate was structured as follows: biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film 1 (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0279] [Example 2] Instead of the sealant film 1, a resin composition 1 for the first layer containing 100% by mass of random PP, a resin composition 2' for the second layer containing 92.2% by mass of block PP and 7.8% by mass of PE, and a resin composition 3 for the third layer containing 100% by mass of random PP were extruded simultaneously from a multilayer die to obtain an unstretched multilayer film (hereinafter also referred to as "sealant film 2") with a first layer / second layer / third layer thickness of 5 μm / 50 μm / 5 μm. The laminate was produced in the same manner as in Example 1, except that a laminate with a thickness of about 109 μm was used. The laminate was configured as follows: biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film 2 (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0280] [Examples 3 to 5] A laminate having a thickness of about 109 μm was obtained in the same manner as in Example 1, except that instead of sealant film 1, single-layer sealant films 3 to 5 prepared according to the formulations shown in Table 1 below were used. The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant films 3 to 5 (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0281] [Comparative Examples 1 to 2] A laminate having a thickness of about 109 μm was obtained in the same manner as in Example 1, except that instead of sealant film 1, single-layer sealant films 6 to 7 prepared according to the composition shown in Table 1 below were used. The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant films 6 to 7 (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0282] [Sealant film composite elastic modulus] The composite elastic modulus of the sealant film (sealant layer) (E r) was measured based on the nanoindentation method using a nanoindenter (Bruker's "TI950 TriboIndenter") with the cross section of the sealant layer as the measurement surface. A Berkovich indenter (triangular pyramid indenter; Berkovich_TI0039) was used as the indenter for the nanoindenter. Measurements were performed at five or more points at the same measurement position (the point where the indenter was pressed) on the same cross section, and the composite elastic modulus E r is the arithmetic mean value of the five measured values, and is recorded for each measurement location.

[0283] The above cross section was obtained by folding the laminated body so that the sealant film side was on the inside, and heat-sealing the laminated body to a width of 130 mm and a height of 165 mm to produce a bag-like pouch, filling the resulting pouch with 100 mL of water from the opening, and heat-sealing the opening of the pouch, and cutting the laminated body in the thickness direction after retort sterilization treatment with hot water at a retort temperature of 121°C and a retort time of 30 minutes. The cross section was produced by embedding the laminated body in an embedding resin to produce a block, and cutting the block using a commercially available rotary microtome at room temperature (23°C). Finishing was performed with a diamond knife. The indenter was pressed into three locations on the exposed cross-section of the sealant layer: a position 2 μm inward from the interface with the adhesive layer in the thickness direction of the sealant layer (top), near the center (center), and a position 2 μm inward from the sealing surface (bottom). The measurement conditions were as follows: a load control method (indentation load 30 μN, loading 3 seconds / holding 5 seconds / unloading 3 seconds). The indenter was pressed into the sealant layer from the cross section of the sealant layer to an indentation load of 30 μN over a period of 3 seconds, and the indentation load was held in this state for 5 seconds. The load was then removed over a period of 3 seconds. This resulted in a maximum load P max , contact projection area A at maximum depth p The load-displacement curve was obtained, and the composite elastic modulus was calculated from the load-displacement curve. The measurement was carried out in a room temperature (23°C) environment. The results are shown in Table 1.

[0284] [Impact resistance evaluation] The laminate obtained above was folded into a V shape with the sealant film side (first layer) facing inward, and heat-sealed to a width of 130 mm and a height of 165 mm to produce 10 bag-shaped pouches. The pouch was filled with 150 mL of water through the opening, and the opening was heat-sealed to seal the pouch. The sealed pouch was subjected to a hot water retort sterilization treatment at a retort temperature of 121° C. for 30 minutes. After retort processing, the pouch was dropped 10 times horizontally from a height of 80 cm onto the floor (so that the body of the pouch hits the floor), and then dropped another 10 times vertically from a height of 80 cm onto the floor (so that the bottom of the pouch hits the floor), and the number of pouches that broke out of the 10 pouches was counted to evaluate the impact resistance. The results are shown in Table 1.

[0285] <Evaluation criteria> ◎: No broken bags. ○: The bag was not broken, but damage was observed on the seal edge. (Multi-layer structure) In the damaged area, fracture of the sealant layer was observed, but the core layer was not fractured. (Single layer structure) In the damaged area, no breakage of the sealant layer was observed, but peeling was observed between the second substrate / sealant layer of the first substrate / second substrate / sealant layer of the laminate. ×: 3 or more broken bags.

[0286] [Evaluation of openability] The laminate obtained above was folded into a V shape with the sealant film side (first layer) facing inward, and heat sealed to a width of 130 mm and a height of 165 mm to produce 10 bag-shaped pouches. At this time, the direction corresponding to the machine direction (MD) of the film was the short side direction of 130 mm. The pouch was filled with 150 mL of water through the opening, and the opening was heat-sealed to seal the pouch. The sealed pouch was subjected to a hot water retort sterilization treatment at a retort temperature of 121° C. for 30 minutes. The pouch after retort processing was opened at a notch provided at a position 20 mm inside from the end in the direction perpendicular to the film flow direction (TD), and the openability was evaluated. The results are shown in Table 1.

[0287] <Evaluation criteria> ◎: The entire 130 mm was able to be opened, and there were no particular abnormalities in the opened area. ○: The entire 130 mm was able to be opened, but there were some areas where the sealant film had stretched and the opened area was wavy. ×: The CPP was stretched, and there were three or more packages in which the entire 130 mm could not be opened.

[0288] [Table 1] [Explanation of symbols]

[0289] 1: laminate, 10: oriented polypropylene substrate, 20: barrier substrate, 22: oriented polypropylene layer, 23: surface coating layer or surface resin layer, 24: inorganic oxide layer, 25: coating layer, 30: sealant layer (sealant film for laminate), 40, 40A, 40B: adhesive layers, 50: packaging bag, 51: easy-to-open portion, 52: notch portion, 53: half-cut line, 60: standing pouch, 61: body (side sheet), 62: bottom (bottom sheet), 63: steam release mechanism, 63a: steam release seal part, 63b: non-seal part

Claims

1. A sealant film for use in a laminate in which the content of polypropylene relative to the total amount of resin materials is 80% by mass or more, The sealant film contains 40% by mass or more of polypropylene based on the total amount of the sealant film, The sealant film has a composite elastic modulus of 500 MPa or more and 900 MPa or less as measured by a nanoindentation method.

2. The sealant film for laminates according to claim 1 , wherein the sealant film comprises polyethylene.

3. The sealant film for laminates according to claim 1 , wherein the sealant film comprises an ethylene-propylene elastomer.

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

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

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

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

8. A laminate for use in packaging materials, comprising: At least a first substrate and a sealant layer are provided, The sealant layer is made of the sealant film for laminates according to any one of claims 1 to 7, A laminate, wherein the content of polypropylene relative to the total amount of resin materials is 80 mass % or more.

9. The laminate of claim 8 further comprising a second substrate between the first substrate and the sealant layer.

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

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

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