Laminate sealant film, laminate, and packaging container

Abstract

To provide a laminate sealant film excellent in heat resistance, low-temperature sealability, and shock resistance.SOLUTION: There is provided a laminate sealant film which is a sealant film to be used for a laminate in which a content ratio of polypropylene is more than or equal to 80 mass %, at least including: a first layer located on one of surfaces of the laminate; and a second layer in contact with the first layer. The first layer contains a first matrix resin component of more than or equal to 51 mass % and less than or equal to 90 mass % and a first dispersion component and has a sea-island structure in which the first dispersion component is dispersed in the first matrix resin component. The second layer contains a second matrix resin component of more than or equal to 51 mass % and less than or equal to 85 mass % and a second dispersion component and has a sea-island structure in which the second dispersion component is dispersed in the second matrix resin component. The first matrix resin component is formed of a propylene-ethylene random copolymer. The first dispersion component contains polyethylene of more than or equal to 5 mass %. The second matrix resin component is formed of block polypropylene. The second dispersion component contains polyethylene of more than or equal to 5 mass %.SELECTED DRAWING: Figure 1

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 to make a packaging container such as a retort pouch, the laminate used in the packaging container is required to have heat resistance to withstand heat sterilization treatment. In addition, since the laminate is heat-sealed to make a packaging container, the laminate is required to be suitable for bag making, and the sealant film is required to have low-temperature sealing properties. Furthermore, the laminate used in a packaging container such as a retort pouch is required to have drop impact resistance (impact resistance) to withstand the impact of the pouch being dropped. However, the reality is that there has been insufficient consideration given to satisfying these required properties for a laminate made of a single material of polypropylene.

[0006] One of the problems to be solved by the present disclosure is to provide a sealant film for laminates that has excellent heat resistance, low-temperature sealability and impact resistance, and is suitable for laminates made of a single material such as polypropylene. [Means for solving the problem]

[0007] A sealant film for laminates according to the present disclosure is a sealant film for use in a laminate in which a polypropylene content ratio relative to a total amount of resin material is 80% by mass or more, and when used in the laminate, the sealant film at least comprises a first layer located on one of the surfaces of the laminate and a second layer in contact with the first layer, the first layer comprising a first matrix resin component and a first dispersed component in an amount of 51% by mass or more and 90% by mass or less relative to the total amount of the first layer, and having an islands-in-a-sea structure in which the first dispersed component is dispersed in the first matrix resin component, the second layer comprising a second matrix resin component and a second dispersed component in an amount of 51% by mass or more and 85% by mass or less relative to the total amount of the second layer, and having an islands-in-a-sea structure in which the second dispersed component is dispersed in the second matrix resin component, the first matrix resin component comprising a propylene-ethylene random copolymer, the first dispersed component comprising at least 5% by mass or more of polyethylene relative to the total amount of the first layer, the second matrix resin component comprising a block polypropylene, and the second dispersed component comprising at least 5% by mass or more of polyethylene relative to the total amount of the second layer. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a sealant film for laminates that has excellent heat resistance, low-temperature sealability and impact resistance, 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 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.

[0013] [Sealant film for laminates] The sealant film for laminates of the present disclosure comprises a first layer and a second layer. In one embodiment, the sealant film for laminates may further include a third layer. The sealant film for laminates of the present disclosure is a multilayer film having at least two layers. 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.

[0014] 1 and 2 are schematic cross-sectional views showing one embodiment of the sealant film for laminates. 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.

[0015] 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.

[0016] (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 sealant film for laminates of the present disclosure.

[0017] The first matrix resin component is made of a propylene-ethylene random copolymer. Propylene-ethylene random copolymer (propylene random copolymer) is a random copolymer of 51% by mass or more and 90% by mass or less of propylene units as the main component and ethylene units as a copolymerization monomer, and has excellent transparency and impact strength compared to propylene homopolymer (homopolypropylene), and its melting point is 20 to 30°C lower.

[0018] The ethylene content of the propylene-ethylene random copolymer is preferably 1.0% by mass or more, more preferably 2.0% by mass or more. The ethylene content of the propylene-ethylene random copolymer is preferably 20% by mass or less, more preferably 10% by mass or less. When the ethylene content is at least the lower limit, low-temperature sealability can be ensured when the laminate sealant film of the present disclosure is used to form a laminate. When the ethylene content is at most the upper limit, excessive deterioration of heat resistance can be suppressed when the laminate sealant film of the present disclosure is used to form a laminate. The ethylene content of propylene-ethylene random copolymers can be measured by the quantitative method for ethylene content (IR method) described on pages 412-413 of the Polymer Analysis Handbook (May 10, 2013, 3rd printing) edited by the Polymer Analysis Roundtable of the Japan Analytical Society.

[0019] The melting point of the propylene-ethylene random copolymer is preferably 145°C or lower, more preferably 135°C or lower. When the melting point is the upper limit or lower, the low-temperature sealability of the laminate using the sealant film for laminates of the present disclosure is good, and the suitability for bag making can be improved. The lower limit of the melting point of the propylene-ethylene random copolymer is preferably 120 or higher. When the melting point is the lower limit or higher, when the laminate using the sealant film for laminates 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).

[0020] The melt flow rate (MFR) of the propylene-ethylene random 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 random copolymer is measured in accordance with JIS K7210 at a temperature of 230° C. and a load of 2.16 kg.

[0021] Examples of methods for producing propylene-ethylene random 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.

[0022] The first dispersion component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the sealant film for laminates of the present disclosure. The first layer has a sea-island structure in which polyethylene, the first dispersion component (island component), is dispersed in a propylene-ethylene random copolymer, the first matrix resin component (sea component), and therefore the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure can be improved.

[0023] 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 propylene-ethylene random copolymer, 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 sealant film for laminates.

[0024] 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 3More 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.

[0025] 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.

[0026] As the polyethylene, from the viewpoint of reducing the environmental load, biomass-derived polyethylene or mechanically recycled or chemically recycled polyethylene may be used.

[0027] 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.

[0028] 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.

[0029] The first dispersion component may further contain a first elastomer. When the first dispersion component contains the first elastomer, the dispersion state of the polyethylene, which is the first dispersion component (island component), in the propylene-ethylene random copolymer, which is the first matrix resin component (sea component), can be further improved. This can further improve the drop impact resistance of the laminate using the sealant film for laminates of the present disclosure.

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

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

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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 is equal to or more than the lower limit in the first layer, the impact resistance of the laminate using the sealant film for laminates of the present disclosure can be further improved. When the content of the first dispersion component is equal to or less than the upper limit, the low-temperature sealability of the laminate using the sealant film for laminates of the present disclosure can be further improved.

[0037] 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 sealant film for laminates 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 low-temperature sealability of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0038] 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 sealant film for laminates of the present disclosure can be further improved. When the content of the first elastomer is equal to or less than the upper limit, for example, the low-temperature sealability of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0039] In the first dispersion component, the ratio of the content of the first elastomer to the content of the polyethylene is preferably 0.5 or more and less than 1.0. When the ratio of the content of the first elastomer to the content of the polyethylene in the first dispersion component is within the above range, for example, the impact resistance of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0040] The thickness of the first layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 12 μm or more. The thickness of the first layer is preferably 20 μm or less, more preferably 15 μm or less. When the thickness is equal to or greater than the lower limit, for example, the low-temperature sealability and impact resistance of a packaging container including a laminate using the sealant film for laminates of the present disclosure can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0041] (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 laminate sealant film of the present disclosure.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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%.

[0048] 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%.

[0049] 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.

[0050] 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.

[0051] 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 sealant film for laminates of the present disclosure can be further improved.

[0052] The polyethylene may be the same as that used for the first dispersion component of the first layer.

[0053] 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 improve the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure.

[0054] The second elastomer may be the same thermoplastic elastomer as the first dispersion component of the first layer.

[0055] 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.

[0056] 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 sealant film for laminates of the present disclosure can be further improved. When the content of the second dispersion component is equal to or less than the upper limit, the heat resistance of the laminate using the sealant film for laminates of the present disclosure can be further improved.

[0057] 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 sealant film for laminates 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 sealant film for laminates of the present disclosure can be further improved.

[0058] 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, for example, the impact resistance of a laminate using the sealant film for laminates of the present disclosure can be further improved. When the content of the second elastomer is equal to or less than the upper limit, for example, the heat resistance of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0059] In the second dispersion component, the ratio of the content of the second elastomer to the content of the polyethylene is preferably 0.5 or more and less than 1.0. When the ratio of the content of the second elastomer to the content of the polyethylene in the second dispersion component is within the above range, for example, the impact resistance of a laminate using the sealant film for laminates of the present disclosure can be further improved.

[0060] 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 the lower limit or more, for example, the heat resistance and impact resistance of a packaging container including a laminate using the laminate sealant film of the present disclosure can be further improved. When the thickness is the upper limit or less, for example, the processability of a laminate using the laminate sealant film of the present disclosure can be further improved.

[0061] (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 surface layer of the sealant film for laminates of the present disclosure.

[0062] 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.

[0063] The third dispersion component includes polyethylene. The polyethylene can contribute to improving the impact resistance of the sealant film for laminates 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 a laminate using the sealant film for laminates of the present disclosure can be improved.

[0064] As the polyethylene, the same polyethylene as that used for the first and second layers can be used.

[0065] The third dispersion component may further contain a third elastomer. When the third dispersion component contains the third elastomer, the dispersion state of the polyethylene, which is the third dispersion component (island component), in the propylene-ethylene block copolymer, which is the third matrix resin component (sea component), can be further improved. This can further increase the drop impact resistance of a laminate using the sealant film for laminates of the present disclosure.

[0066] As the third elastomer, the same thermoplastic elastomer as that used for the first and second layers can be used.

[0067] 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.

[0068] 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.

[0069] 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 sealant film for laminates 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 sealant film for laminates of the present disclosure can be improved.

[0070] (Sealant film) In the sealant film for laminates of the present disclosure, the polyethylenes 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 elastomers may be used.

[0071] In the sealant film for laminates of the present disclosure, the content ratio of the first dispersion component to the total amount of the first layer, which is the sealing 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 sealant film for laminates 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 attributable to the first layer.

[0072] In the laminate sealant film of the present disclosure, the ratio of the thickness of the second layer to the thickness of the first layer is preferably 3.0 or more. According to the laminate sealant film satisfying the above relationship, the heat resistance and impact resistance attributable to the second layer can be further improved.

[0073] In the sealant film for laminates 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 sealant film for laminates of the present disclosure can be further improved.

[0074] The thickness of the sealant film for laminates of the present disclosure is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more. The thickness of the sealant film for laminates is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. When the thickness is equal to or more than the lower limit, for example, the time required for heat sealing of a packaging container including the laminate can be shortened. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved. When a pouch (particularly a retort pouch) is produced from the laminate, the thickness of the sealant layer is preferably 30 μm or more and 200 μm or less, more preferably 40 μm or more and 100 μm or less, and even more preferably 50 μm or more and 80 μm or less.

[0075] The sealant film for laminates of the present disclosure can be produced, for example, by a conventionally known method. The sealant film is 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.

[0076] 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.

[0077] From the viewpoint of heat sealability, the sealant film for laminates of the present disclosure is preferably an unstretched resin film. The resin film can be produced, for example, by using a casting method, a T-die method, an inflation method, or the like.

[0078] [Laminate] The laminate of the present disclosure comprises a substrate (first substrate) and a sealant layer. The substrate includes a polypropylene resin layer that has been subjected to a stretching treatment. In one embodiment, the substrate is a barrier substrate including a polypropylene resin layer that has been subjected to a stretching treatment and a vapor deposition film. The barrier substrate may further include a layer described later. In one embodiment, the substrate is made of a polypropylene resin layer that has been subjected to a stretching treatment, that is, in one embodiment, the substrate is a polypropylene resin substrate that has been subjected to a stretching treatment.

[0079] In the following description, except when describing the stretching treatment, the terms "polypropylene resin layer" and "polypropylene resin substrate" mean "a polypropylene resin layer that has been subjected to a stretching treatment" and "a polypropylene resin substrate that has been subjected to a stretching treatment", respectively. The laminate of the present disclosure is suitable for packaging material applications.

[0080] 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. The first substrate and the second substrate are each independently a barrier substrate or a polypropylene resin substrate.

[0081] In one embodiment, one of the first substrate and the second substrate is a barrier substrate, and the other of the first substrate and the second substrate is a polypropylene resin substrate. In another embodiment, both the first substrate and the second substrate may be a barrier substrate, or both the first substrate and the second substrate may be a polypropylene resin substrate.

[0082] 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 a polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the polypropylene resin layer 22 constitutes the outermost layer of the laminate 1, and the vapor-deposited film 24 is in contact with the adhesive layer 40.

[0083] FIG. 4 is similar to FIG. 3, except that the barrier substrate 20 has a surface coating layer or surface resin layer 23 between the polypropylene resin layer 22 and the vapor-deposited film 24 .

[0084] 5 is the same as FIG. 3 except that the barrier substrate 20 includes a polypropylene resin layer 22, a surface coating layer or surface resin layer 23, a vapor deposition film 24, and a barrier coating layer 25 in this order in the thickness direction. In this example, the barrier coating layer 25 contacts the adhesive layer 40.

[0085] 6 includes a polypropylene resin substrate 10 as a first substrate, an adhesive layer 40A, a barrier substrate 20 as a second substrate, an adhesive layer 40B, and a sealant layer 30, in that order in the thickness direction. The barrier substrate 20 includes a polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the polypropylene resin layer 22 is in contact with the adhesive layer 40B, and the vapor-deposited film 24 is in contact with the adhesive layer 40A.

[0086] FIG. 7 is similar to FIG. 6, except that the barrier substrate 20 has a surface coating layer or surface resin layer 23 between the polypropylene resin layer 22 and the vapor-deposited film 24 .

[0087] 8 is the same as FIG. 6, except that the barrier substrate 20 includes a polypropylene resin layer 22, a surface coating layer or surface resin layer 23, a vapor deposition film 24, and a barrier coating layer 25 in this order in the thickness direction. In this example, the barrier coating layer 25 contacts the adhesive layer 40A.

[0088] 9 includes a barrier substrate 20 as a first substrate, an adhesive layer 40A, a polypropylene resin substrate 10 as a second substrate, an adhesive layer 40B, and a sealant layer 30, in that order in the thickness direction. The barrier substrate 20 includes a polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the polypropylene resin layer 22 constitutes the outermost layer of the laminate 1, and the vapor-deposited film 24 is in contact with the adhesive layer 40A.

[0089] FIG. 10 is similar to FIG. 9, except that the barrier substrate 20 has a surface coating layer or surface resin layer 23 between the polypropylene resin layer 22 and the vapor-deposited film 24 .

[0090] 11 is the same as FIG. 9, except that the barrier substrate 20 includes a polypropylene resin layer 22, a surface coating layer or surface resin layer 23, a vapor deposition film 24, and a barrier coating layer 25 in this order in the thickness direction. In this example, the barrier coating layer 25 contacts the adhesive layer 40A.

[0091] 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 polypropylene resin substrate that has been subjected to a stretching treatment. (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

[0092] In one embodiment, the laminate of the present disclosure comprises at least three elements: a polypropylene resin 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).

[0093] When the first substrate is a barrier substrate, in one embodiment, the first substrate is disposed so that the vapor-deposited film faces the sealant layer side and the polypropylene resin layer faces the side opposite the sealant layer.

[0094] When the second substrate is a barrier substrate, in one embodiment, the second substrate is arranged so that the vapor-deposited film faces the first substrate and the polypropylene resin layer faces the sealant layer, or the second substrate is arranged so that the vapor-deposited film faces the sealant layer and the polypropylene resin layer faces the first substrate. Among these, from the viewpoint of further suppressing deterioration of the vapor-deposited film, when the second substrate is a barrier substrate, it is preferable that the second substrate is arranged so that the vapor-deposited film faces the first substrate and the polypropylene resin layer faces the sealant layer.

[0095] In one embodiment of the laminate of the present disclosure, the first substrate is a polypropylene resin substrate, and the second substrate is a barrier substrate (see Figs. 6 to 8). In this embodiment, the laminate comprises a polypropylene resin substrate, a barrier substrate, and a sealant layer in this order in the thickness direction. A laminate having such a configuration adequately protects the vapor-deposited film 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 is therefore further superior in suitability for bag making.

[0096] 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.

[0097] 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.

[0098] <Barrier substrate> The barrier substrate comprises a polypropylene resin layer and a vapor-deposited film. In one embodiment, the barrier substrate comprises a polypropylene resin layer and a vapor-deposited film provided on one surface of the resin layer. The polypropylene resin layer is a layer that has been subjected to a stretching treatment. The barrier substrate may comprise a surface coat layer or a surface resin layer between the polypropylene resin layer and the vapor-deposited film. The barrier substrate may comprise a barrier coat layer on the vapor-deposited film.

[0099] (Polypropylene resin layer) The polypropylene resin layer contains polypropylene as a main component, i.e., polypropylene in an amount of more than 50 mass %. By providing the barrier substrate with the polypropylene resin layer, for example, the oil resistance of a packaging container produced using the barrier substrate can be improved.

[0100] The polypropylene may be any one of a propylene homopolymer, a propylene random copolymer, and a propylene block copolymer, and may be a mixture of two or more selected from these.

[0101] A propylene homopolymer is a polymer of propylene alone. A propylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene. A propylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of at least an α-olefin other than propylene. The polymer block of at least an α-olefin other than propylene may be a polymer block of propylene and an α-olefin other than propylene.

[0102] Examples of the α-olefins include α-olefins having 2 to 20 carbon atoms, 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.

[0103] Among polypropylenes, it is preferable to use a random copolymer from the viewpoint of transparency. When the rigidity and heat resistance of the packaging container are important, it is preferable to use a homopolymer. When the drop impact resistance of the packaging container is important, it is preferable to use a block copolymer.

[0104] In one embodiment, the melt flow rate (MFR) of polypropylene may be 0.1 g / 10 min or more and 50 g / 10 min or less, or 0.3 g / 10 min or more and 30 g / 10 min or less, from the viewpoint of film-forming property and processability. The MFR of polypropylene is measured in accordance with JIS K7210 under conditions of a temperature of 230° C. and a load of 2.16 kg.

[0105] As the polypropylene, from the viewpoint of reducing the environmental load, biomass-derived polypropylene or mechanically recycled or chemically recycled polypropylene may be used.

[0106] The polypropylene content in the polypropylene resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0107] The polypropylene resin layer may contain a resin material other than polypropylene, such as polyolefins such as polyethylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins.

[0108] The polypropylene resin layer may contain additives, such as crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0109] The polypropylene resin layer is a layer that has been subjected to a stretching treatment. This can improve, for example, the heat resistance, drop impact resistance, water resistance, and dimensional stability of the laminate. A laminate having such a resin layer is suitable, for example, as a packaging material for constituting a packaging container that is subjected to a boiling treatment or a retort treatment. The stretching process may be uniaxial stretching or biaxial stretching.

[0110] The stretching ratio when stretching in the machine direction (flow direction of the base material, MD direction) is preferably 2 to 15 times, more preferably 5 to 13 times. The stretching ratio when stretching in the transverse direction (direction perpendicular to the MD direction, TD direction) is preferably 2 to 15 times, more preferably 5 to 13 times. By setting the stretching ratio at 2 times or more, the strength and heat resistance of the polypropylene resin layer can be further improved, and the printability of the polypropylene resin layer can be improved. From the viewpoint of the breaking limit of the polypropylene resin layer, the stretching ratio is preferably 15 times or less.

[0111] In one embodiment, the polypropylene resin layer may be subjected to a surface treatment. This can improve, for example, the adhesion between the polypropylene resin layer and other layers. Examples of the surface treatment method 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 polypropylene resin layer.

[0112] The polypropylene resin layer may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin layer is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the laminate can be improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be improved.

[0113] (Surface coating layer) In one embodiment, the barrier substrate has a surface coating layer containing a resin material having a polar group between the polypropylene resin layer and the vapor-deposited film. By providing the surface coating layer containing a resin material having a polar group, the adhesion of the vapor-deposited film formed on the surface coating layer can be improved, and the gas barrier property can also be improved.

[0114] In this embodiment, the barrier substrate comprises a resin substrate having a polypropylene resin layer and a surface coating layer, and a vapor-deposited film provided on the surface coating layer. The barrier substrate comprises the polypropylene resin layer, the surface coating layer, and the vapor-deposited film in this order in the thickness direction.

[0115] 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, from the viewpoint of lamination properties of packaging containers, carboxy groups, carbonyl groups, ester groups, hydroxyl groups, amino groups, amide groups, and urethane groups are preferred, and carboxy groups, hydroxyl groups, amide groups, and urethane groups are more preferred.

[0116] Examples of resin materials having a polar group include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl group-containing (meth)acrylic resin, polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon, and polyurethane. Among these, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, hydroxyl group-containing (meth)acrylic resin, polyamide, and polyurethane are more preferred.

[0117] The surface coating layer can be formed, for example, using an aqueous emulsion or a solvent-based emulsion. Examples of the aqueous emulsion include a polyamide-based emulsion, a polyethylene-based emulsion, and a polyurethane-based emulsion. Examples of the solvent-based emulsion include a (meth)acrylic resin-based emulsion and a polyester-based emulsion.

[0118] 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 a resin material other than the resin material having a polar group. The surface coating layer may contain the above-mentioned additives.

[0119] The ratio of the thickness of the surface coating layer to the total thickness of the resin substrate having the polypropylene resin layer and the surface coating layer is preferably 0.08% or more and 20% or less, more preferably 0.2% or more and 15% or less, even more preferably 1% or more and 10% or less, and even more preferably 1% or more and 5% or less. When the ratio is equal to or more than the lower limit, for example, the adhesion of the vapor deposition film can be improved, the gas barrier property can be improved, and the laminate strength of the packaging container can be improved. When the ratio is equal to or less than the upper limit, for example, the processability of the resin substrate and the recyclability of the packaging container can be improved.

[0120] The thickness of the surface coating layer is preferably 0.02 μm to 10 μm, more preferably 0.05 μm to 10 μm, even more preferably 0.1 μm to 10 μm, and even more preferably 0.2 μm to 5 μm. If the thickness is equal to or greater than the lower limit, the adhesion of the vapor deposition film can be improved, the gas barrier properties can be improved, and the laminate strength of the packaging container can be improved. If the thickness is equal to or less than the upper limit, the processability of the resin substrate and the recyclability of the packaging container can be improved.

[0121] 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 resin film, and then the resin film is stretched. A coating liquid for forming a surface coating layer is applied to the stretched resin film and dried, thereby producing a resin substrate having a polypropylene resin layer and a surface coating layer.

[0122] (Surface resin layer) In one embodiment, the barrier substrate includes a surface resin layer between the polypropylene resin layer and the vapor-deposited film, the surface resin layer containing a resin material having a melting point of 180° C. or higher (hereinafter also referred to as a "high melting point resin material") By providing the surface resin layer containing a high melting point resin material, the adhesion of the vapor-deposited film formed on the surface resin layer can be improved, and the gas barrier property can also be improved.

[0123] In this embodiment, the barrier substrate comprises a resin substrate having a polypropylene resin layer and a surface resin layer, and a vapor-deposited film provided on the surface resin layer. The barrier substrate comprises the polypropylene resin layer, the surface resin layer, and the vapor-deposited film in this order in the thickness direction.

[0124] The melting point of the high-melting-point resin material is preferably 185° C. or higher, more preferably 190° C. or higher, and even more preferably 205° C. or higher. When the melting point is equal to or higher than the lower limit, for example, the adhesion of the vapor-deposited film can be improved, the gas barrier property can be improved, and the laminate strength of the packaging container can be improved.

[0125] The melting point of the high melting point resin material is preferably 265° C. or lower, more preferably 260° C. or lower, and further preferably 250° C. or lower. This can improve, for example, the film-forming properties of the resin substrate.

[0126] 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).

[0127] The difference between the melting point of the high melting point resin material contained in the surface resin layer and the melting point of the polypropylene contained in the polypropylene resin layer is preferably 20° C. or more and 80° C. or less, more preferably 20° C. or more and 60° C. or less. When the difference is the lower limit, for example, the adhesion of the vapor deposition film can be further improved, the gas barrier property can be further improved, and the laminate strength of the packaging container can be further improved. When the difference is equal to or less than the upper limit, for example, the film formability of the resin substrate can be further improved.

[0128] 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, from the viewpoint of the gas barrier properties and laminate strength of the packaging container, hydroxyl groups, ester groups, amino groups, amide groups, carboxy groups, and carbonyl groups are preferred, and amide groups are more preferred.

[0129] 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, (meth)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 more preferable are ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyester, and polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon.

[0130] The content of the high melting point resin material in the surface resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more.

[0131] The surface resin layer may contain a resin material other than the high melting point resin material. The surface resin layer may contain the above-mentioned additives. The surface resin layer may be subjected to the above-mentioned surface treatment.

[0132] The ratio of the thickness of the surface resin layer to the total thickness of the resin substrate having the polypropylene resin layer and the surface resin layer is preferably 1% to 10%, more preferably 1% to 5%. When the ratio is equal to or greater than the lower limit, the adhesion of the vapor deposition film can be improved, the gas barrier properties can be improved, and the laminate strength of the packaging container can be improved. When the ratio is equal to or less than the upper limit, the film-forming property and processing suitability of the resin substrate and the recycling suitability of the packaging container can be improved.

[0133] The thickness of the surface resin layer is preferably 0.1 μm to 5 μm, more preferably 0.1 μm to 4 μm. When the thickness is equal to or greater than the lower limit, for example, the adhesion of the vapor deposition film can be improved, the gas barrier property can be improved, and the laminate strength of the packaging container can be improved. When the thickness is equal to or less than the upper limit, for example, the film-forming property and processing suitability of the resin substrate and the recycling suitability of the packaging container can be improved.

[0134] In one embodiment, the resin substrate may include an adhesive resin layer between the polypropylene resin layer and the surface resin layer, thereby improving the adhesion between these layers.

[0135] The adhesive resin layer can be formed, for example, from an adhesive resin. Examples of the adhesive resin include polyether, polyester, polyurethane, silicone resin, epoxy resin, vinyl resin, phenol resin, polyolefin, and acid-modified polyolefin. Among these, polyolefin and its acid-modified product are preferred, and polypropylene and its acid-modified product are more preferred, from the viewpoint of the recyclability of the packaging container.

[0136] The thickness of the adhesive resin layer is, for example, 1 μm or more and 15 μm or less. When the thickness is 1 μm or more, for example, the adhesion between the polypropylene resin layer and the surface resin layer can be further improved. When the thickness is 15 μm or less, for example, the processability of the resin substrate can be further improved.

[0137] In one embodiment, the resin substrate having a polypropylene resin layer, and optionally an adhesive resin layer and a surface resin layer is a coextrusion stretched resin film. The coextrusion stretched resin film can be produced, for example, by forming a laminated film using a T-die method or an inflation method, and then stretching the laminated film. By forming a film using the inflation method, the laminated film may be stretched at the same time.

[0138] The stretching process may be uniaxial stretching or biaxial stretching. The stretching ratio in the MD direction is preferably 2 to 15 times, more preferably 5 to 13 times. The stretching ratio in the TD direction is preferably 2 to 15 times, more preferably 5 to 13 times.

[0139] (evaporated film) In one embodiment, the barrier substrate has a vapor-deposited film made of an inorganic oxide. In one embodiment, the barrier substrate has a vapor-deposited film on the surface coat layer or the surface resin layer. This can improve the gas barrier properties of the laminate, specifically, the oxygen barrier properties and water vapor barrier properties. A packaging container made using the laminate can suppress the weight loss of the contents filled in the packaging container.

[0140] 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.

[0141] In one embodiment, the inorganic oxide is more preferably silica since no aging treatment is required after the deposition film is formed.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.

[0142] The thickness of the vapor-deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less. When the thickness is equal to or more than the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the occurrence of cracks in the vapor-deposited film can be suppressed, and the recyclability of the packaging container can be improved.

[0143] The surface of the deposited film is preferably subjected to the above-mentioned surface treatment, which can improve the adhesion between the deposited film and an adjacent layer.

[0144] Examples of methods for forming a vapor-deposited film include physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0145] The vapor-deposited film may be a single layer formed by one vapor deposition process, or may be a multilayer formed by multiple vapor deposition processes. When the vapor-deposited film is a multilayer film, each layer may be composed of the same inorganic oxide or different inorganic oxides. Each layer may be formed by the same method or different methods.

[0146] The vapor-deposited film in the barrier substrate is preferably a vapor-deposited film formed by a CVD method, and more preferably a carbon-containing silicon oxide vapor-deposited film formed by a CVD method, which can suppress deterioration of the gas barrier properties even when the laminate is bent.

[0147] The carbon-containing silicon oxide vapor deposition film contains silicon, oxygen and carbon. In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the carbon ratio C is preferably 3% to 50%, more preferably 5% to 40%, and even more preferably 10% to 35%, relative to 100% in total of the three elements silicon, oxygen, and carbon. By setting the carbon ratio C within 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.

[0148] In one embodiment of the carbon-containing silicon oxide vapor deposition film, the silicon ratio Si is preferably 1% to 45%, more preferably 3% to 38%, and even more preferably 8% to 33%, based on the total of the three elements silicon, oxygen, and carbon (100%). The oxygen ratio O is preferably 10% to 70%, more preferably 20% to 65%, and even more preferably 25% to 60%, based on 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, the deterioration of the gas barrier property can be further suppressed even when the laminate is bent.

[0149] 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.

[0150] The proportions C, Si, and O in the carbon-containing silicon oxide vapor-deposited film can be measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the following measurement conditions.

[0151] (Measurement conditions) Equipment used: "ESCA-3400" (manufactured by Kratos) [1] Spectral collection conditions Incident X-ray: MgKα (monochromatic X-ray, hν=1253.6eV) X-ray output: 150W (10kV 15mA) X-ray scanning area (measurement area): Approx. 6 mm φ Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar + Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Etching range: 10mmφ Ion sputtering time: 30 seconds, spectrum collected

[0152] (Barrier coat layer) In one embodiment, the barrier substrate may further include a barrier coat layer on the vapor-deposited film. That is, the barrier substrate may further include a barrier coat layer on the surface of the vapor-deposited film opposite to the surface on the polypropylene resin layer side. This can improve, for example, the oxygen barrier property and water vapor barrier property of the laminate.

[0153] In one embodiment, the barrier coat layer contains a gas barrier resin, such as an ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyamide such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, polyurethane, or (meth)acrylic resin.

[0154] 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 further preferably 70% by mass or more. With such a configuration, for example, the gas barrier property of the barrier coat layer can be improved. The barrier coat layer may contain the above-mentioned additives.

[0155] The thickness of the barrier coat layer containing the gas barrier resin is preferably 0.01 μm to 10 μm, more preferably 0.1 μm to 5 μm. By making the thickness of the barrier coat layer 0.01 μm or more, for example, the gas barrier property can be further improved. By making the thickness of the barrier coat layer 10 μm or less, for example, the processability of the laminate and the recyclability of the packaging container can be improved.

[0156] The barrier coat layer can be formed, for example, by coating and drying a coating liquid obtained by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent.

[0157] In another embodiment, the barrier coat layer is a gas barrier coating film formed by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, and adding water, an organic solvent, and a sol-gel catalyst as required to obtain a gas barrier composition, which is then coated on a vapor deposition film and dried. The gas barrier coating film contains a hydrolysis polycondensate obtained by hydrolyzing and polycondensing the above-mentioned metal alkoxide by the sol-gel method. By providing such a barrier coat layer on the vapor deposition film, the occurrence of cracks in the vapor deposition film can be effectively suppressed.

[0158] 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.

[0159] R 1 and R 2 Examples of the organic group include alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-hexyl group, and an n-octyl group. The metal atom M is, for example, silicon, zirconium, titanium or aluminum.

[0160] Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0161] 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 and 500 parts by mass or less, based on 100 parts by mass of the metal alkoxide.

[0162] As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and an organoalkoxysilane having an epoxy group is preferred, 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 relative to 100 parts by mass of the metal alkoxide.

[0163] The gas barrier composition may contain water in a ratio of preferably 0.1 to 100 moles, more preferably 0.5 to 60 moles, per mole 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.

[0164] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butyl alcohol.

[0165] 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, tartaric acid, etc. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less per 1 mol of the total molar amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

[0166] As the amine compound, a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is suitable, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of the amine compound used is preferably 0.01 parts by mass or more and 1.0 parts by mass or less, more preferably 0.03 parts by mass or more and 0.3 parts by mass or less, based on 100 parts by mass of the total amount of the metal alkoxide and the silane coupling agent.

[0167] 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.

[0168] 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 the deposition film 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 multiple composite polymer layers. For example, the applied composition is heated at a temperature of preferably 20°C to 150°C, more preferably 50°C to 120°C, and even more preferably 70°C to 100°C, for 1 second to 10 minutes. This allows the formation of a gas barrier coating film.

[0169] The thickness of the gas barrier coating film is preferably 0.01 μm to 100 μm, more preferably 0.1 μm to 50 μm, and even more preferably 0.1 μm to 5 μm, which can improve the gas barrier properties, suppress the occurrence of cracks in the vapor deposition film, and improve the recyclability of the packaging container.

[0170] <Polypropylene resin base material> The polypropylene resin substrate is made of the polypropylene resin layer described above. The polypropylene resin substrate is a substrate that has been subjected to a stretching treatment. The details of the polypropylene resin layer and the stretching treatment are as described above, and a detailed description thereof will be omitted in this section.

[0171] The polypropylene resin substrate may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin substrate is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the laminate can be improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be improved.

[0172] (Printing layer) The laminate of the present disclosure may have a printed layer on the surface of a substrate such as a barrier substrate and a polypropylene resin substrate. 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.

[0173] 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.

[0174] The thickness of the printed layer is, for example, not less than 0.5 μm and not more than 3 μm.

[0175] <Sealant layer> The laminate of the present disclosure includes the above-mentioned sealant film for laminates of the present disclosure as a sealant layer, which can improve, for example, the heat resistance, low-temperature sealability, and impact resistance of the laminate.

[0176] The sealant layer (sealant film for laminates) contains 51% by mass or more of a propylene-ethylene random copolymer in the first layer, and 51% by mass or more of a block polypropylene (propylene-ethylene block copolymer) in the second and third layers.

[0177] By using a propylene-ethylene random copolymer in the first layer, for example, the low-temperature sealability of the sealant layer, and therefore the laminate, can be improved. In addition, by using a block polypropylene (propylene-ethylene block copolymer) in the second and third layers, for example, the heat resistance and impact resistance (drop impact resistance) of the sealant layer, and therefore the laminate, can be improved. This improves the bag-making suitability when producing a packaging container using the laminate, and also prevents the packaging container from being damaged by impact when dropped.

[0178] By containing a propylene-ethylene random copolymer and a propylene-ethylene block copolymer as the main components in the sealant layer (sealant film for laminates), for example, it is possible to make the packaging container mono-material. The propylene-ethylene random copolymer and the propylene-ethylene block copolymer are classified as polypropylene in the calculation of the mono-material ratio. This eliminates the need 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.

[0179] The sealant layer may contain the above-mentioned additives. The sealant layer may be subjected to the above-mentioned surface treatment.

[0180] <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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] [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.

[0200] 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.

[0201] In one embodiment, the packaging container of the present disclosure maintains gas barrier properties even when subjected to high-temperature treatment and is less deformed, and is therefore suitable as a microwave oven container, or a boiling or retort container. The packaging container of the present disclosure is also suitable as a microwave oven boiling or retort container. The packaging container of the present disclosure is particularly suitable as a boiling or retort pouch.

[0202] Examples of heat sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0203] Examples of packaging bags include packaging bags of various shapes, such as standing pouch type, side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, grommet seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] 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.

[0208] 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.

[0209] 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.

[0210] As specific examples of packaging bags, a small bag and a standing pouch will be described below. A sachet is a small packaging bag used to hold contents of, for example, 1 g to 200 g. 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] [Mechanism of action] In a laminate containing 80% or more by mass of a polypropylene-based single material (hereinafter referred to as a propylene-based laminate), the first substrate is a polypropylene resin substrate that has been subjected to a stretching treatment, and is inferior in heat resistance to substrates using PET. For example, the first substrate of the propylene-based laminate is easily deformed in response to changes in temperature. For example, the first substrate of the propylene-based laminate is easily stretched during transportation and easily shrinks when heated.

[0221] When the propylene-based laminate is used as a packaging material, the propylene-based laminate is subjected to a heat sterilization treatment such as a retort treatment, a boiling treatment, etc. Therefore, the first base material and the sealant layer constituting the propylene-based laminate are required to have heat resistance.

[0222] The sealant film for laminates of the present disclosure used as a sealant layer includes a second layer (core layer). The second layer includes a second matrix resin component of 51% by mass or more and 85% by mass or less. The second matrix resin component is made of block propylene. Block propylene has an island-sea structure in which an ethylene-propylene copolymer elastomer is dispersed in a propylene homopolymer (homo PP), and therefore has excellent heat resistance. Therefore, a propylene-based laminate using the sealant film for laminates of the present disclosure has improved heat resistance.

[0223] On the other hand, block propylene has a high melting point. Therefore, when the entire propylene-based sealant film is composed of block propylene, the heat-sealing temperature of the packaging material made of the propylene-based laminate using the propylene-based sealant film becomes high. If the heat-sealing temperature becomes high, there is a risk that the first base material layer will be deformed because the difference in melting point between the first base material and the propylene-based laminate is small.

[0224] In consideration of this point, the sealant film for laminates of the present disclosure includes a first layer (sealing layer) that is in contact with the second layer and is located on the outermost surface of the laminate when used in the laminate. The first layer includes a first matrix resin component of 51% by mass or more and 90% by mass or less. The first matrix resin component is made of a propylene-ethylene random copolymer. The melting point of the propylene-ethylene random copolymer is lower than the melting point of block propylene. Therefore, the heat seal temperature of the packaging material made of a propylene laminate using the sealant film for laminates can be lowered compared to when the entire propylene-based sealant film is made of block propylene. Thus, the sealant film for laminates of the present disclosure includes a first layer and a second layer mainly composed of different polypropylenes, and thus has both heat resistance and low-temperature sealability.

[0225] The second layer (core layer) has an island-in-sea structure in which at least a part of the second dispersion component is dispersed in the second matrix resin component. The second dispersion component contains at least 5% by mass or more of polyethylene in the second layer. According to the sealant film for laminates of the present disclosure, the impact resistance of the second layer is improved by dispersing the second dispersion component in the second matrix resin component. For example, when the sealant film for laminates is used as a packaging material made of a propylene laminate, the container made of the packaging material can be prevented from bursting when dropped.

[0226] Furthermore, the first layer (sealing layer) also has a sea-island structure in which at least a part of the first dispersion component is dispersed in the first matrix resin component. The first dispersion component contains at least 5% by mass or more of polyethylene in the first layer. According to the sealant film for laminates of the present disclosure, the impact resistance of the first layer is improved by dispersing the first dispersion component in the first matrix resin component, and thus the impact resistance of the propylene-based sealant film is further improved. In addition, since both the first layer and the second layer have a sea-island structure, the affinity between the structure of the first layer and the structure of the second layer is enhanced. Therefore, it is possible to suppress the occurrence of breakage at the interface between the first layer and the second layer. The affinity between the structure of the first layer and the structure of the second layer also contributes to the improvement of the impact resistance of the sealant film for laminates of the present disclosure.

[0227] The present disclosure relates to, for example, the following [1] to

[22] . [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, When used in the laminate, the laminate at least comprises a first layer located on one surface of the laminate and a second layer in contact with the first layer, the first layer includes a first matrix resin component in an amount of 51% by mass or more and 90% by mass or less with respect to a total amount of the first layer, and a first dispersed component, and has a sea-island structure in which the first dispersed component is dispersed in the first matrix resin component, the second layer includes a second matrix resin component in an amount of 51% by mass or more and 85% by mass or less with respect to a total amount of the second layer, and a second dispersed component, and has a sea-island structure in which the second dispersed component is dispersed in the second matrix resin component, the first matrix resin component comprises a propylene-ethylene random copolymer; the first dispersion component comprises at least 5% by mass or more of polyethylene based on the total amount of the first layer; the second matrix resin component comprises block polypropylene; A sealant film for laminates, wherein the second dispersion component comprises at least 5% by mass or more of polyethylene relative to the total amount of the second layer. [2] The sealant film for laminates according to [1], wherein the block polypropylene contains at least a propylene homopolymer and a block elastomer and has an islands-in-a-sea structure in which the block elastomer is dispersed in the propylene homopolymer. [3] The sealant film for laminates according to [2], wherein the block elastomer is made of an ethylene-propylene elastomer. [4] The sealant film for laminates according to any one of [1] to [3], wherein the content of the second dispersion component relative to the total amount of the second layer is 15 mass % or more and 49 mass % or less. [5] The sealant film for laminates according to any one of [1] to [4], wherein the content of the first dispersion component relative to the total amount of the first layer is 10 mass % or more and 49 mass % or less. [6] The sealant film for laminates according to any one of [1] to [5], wherein the content ratio of the first dispersion component relative to the total amount of the first layer is lower than the content ratio of the second dispersion component relative to the total amount of the second layer. [7] The sealant film for laminates according to any one of [1] to [6], wherein the second dispersion component further contains a second elastomer. [8] The sealant film for laminates described in [7], wherein the second elastomer is a propylene-ethylene elastomer or an ethylene-α-olefin elastomer. [9] The sealant film for laminates described in [7] or [8], wherein in the second dispersion component, the ratio of the content of the second elastomer to the content of the polyethylene is 0.5 or more and less than 1.0.

[10] The sealant film for laminates according to any one of [1] to [9], wherein the first dispersion component further contains a first elastomer.

[11] The sealant film for laminates described in

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

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

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

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

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

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

[13] , wherein the polyethylene of the second dispersion component includes linear low density polyethylene (LLDPE) or low density polyethylene (LDPE).

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

[14] , wherein the polyethylene of the second dispersion component is made of linear low density polyethylene (LLDPE).

[16] Further comprising a third layer in contact with the second layer, the third layer includes a third matrix resin component in an amount of 51% by mass or more and 85% by mass or less with respect to a total amount of the third layer, and a third dispersed component, and has a sea-island structure in which the third dispersed component is dispersed in the third matrix resin component, The sealant film for laminates according to any one of [2] to

[15] , wherein the third matrix resin component comprises the block polypropylene.

[17] The sealant film for laminates described in

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

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

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

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

[18] , A laminate, the content of polypropylene being 80 mass% or more relative to the total amount of resin materials.

[20] The laminate according to

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

[21] A packaging container comprising the laminate described in

[19] or

[20] .

[22] The packaging container according to

[21] , which is a boilable or retort pouch. EXAMPLES

[0228] [Example 1] <Preparation of sealant film for laminate> Resin composition 1 for the first layer containing 75% by mass of random PP1, 13% by mass of PE1, and 12% by mass of elastomer 1, resin composition 2 for the second layer containing 55% by mass of block PP1, 27% by mass of PE1, and 18% by mass of elastomer 1, and resin composition 3 for the third layer containing 55% by mass of block PP1, 27% by mass of PE1, and 18% by mass of elastomer 1 were simultaneously extruded from a multi-layer die to produce an unstretched multi-layer film (hereinafter also referred to as "sealant film (Example 1)") having first, second, and third layer thicknesses of 10 μm, 40 μm, and 10 μm.

[0229] [Propylene homopolymer] Homo PP1: Propylene homopolymer (MFR: 2.5g / 10min, density: 900kg / m 3 ) [Block polypropylene] Block PP1: 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) [Propylene-ethylene random copolymer] Random PP1: Propylene-ethylene random copolymer (MFR: 6g / 10min, density: 0.890g / cm 3 ) [polyethylene] PE1: Linear low-density polyethylene (MFR: 2.0 g / 10 min, density: 0.919 g / cm 3 ) PE2: Low density polyethylene (MFR: 7.0g / 10min, density: 0.920g / cm 3 ) PE3: High density polyethylene (MFR: 16.0g / 10min, density: 0.960g / cm 3 ) [Thermoplastic elastomer] Elastomer 1: Propylene-α-olefin copolymer (melting point: 98°C, MFR (190°C): 3.0g / 10min, MFR (230°C): 7.0g / 10min) Elastomer 2: Ethylene-α-olefin copolymer (melting point: 66°C, MFR (190°C / 2.16kg): 3.6g / 10min, MFR (230°C / 2.16kg): 6.7g / 10min)

[0230] <Preparation of transparent barrier substrate> A hydroxyl group-containing (meth)acrylic resin (number average molecular weight: 25,000, glass transition temperature: 99°C, hydroxyl value: 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.

[0231] 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.

[0232] 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:

[0233] (Formation conditions) Hexamethyldisiloxane:oxygen gas:helium=1:10:10 (unit: slm) Cooling / electrode drum power supply: 22kW Line speed: 100m / min

[0234] 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.

[0235] 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 transparent barrier substrate was obtained.

[0236] <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 transparent barrier substrate was dry-laminated so that the barrier coat layer surface of the substrate was in contact with the adhesive layer surface.

[0237] The non-barrier coat layer surface of the transparent barrier substrate used as the second substrate (intermediate substrate) was subjected to corona treatment, and then coated with a two-component curing polyurethane adhesive (RU-004 / H-1, manufactured by Rock Paint Co., Ltd.) using a gravure roll coating method to a coating thickness of 3.5 μm (when dry), and then a sealant film (Example 1) was dry laminated with the third layer facing the adhesive layer surface.

[0238] 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) / transparent barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Example 1) (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0239] [Examples 2 to 16] A laminate having a thickness of about 109 μm was obtained in the same manner as in Example 1, except that sealant films (Examples 2 to 16) prepared with the compositions shown in Tables 1 and 2 below were used instead of the sealant film (Example 1). The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Examples 2 to 16) (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0240] [Example 17] <Preparation of sealant film for laminate> Resin composition 1 for the first layer containing 85% by mass of random PP1, 8% by mass of PE1, and 7% by mass of elastomer 1, and resin composition 2 for the second layer containing 70% by mass of block PP1, 20% by mass of PE1, and 10% by mass of elastomer 1, were simultaneously extruded from a multi-layer die to produce an unstretched multi-layer film (hereinafter also referred to as "sealant film (Example 17)") having first, second, and third layer thicknesses of 10 μm, 50 μm, and 0 μm. <Preparation of Laminate> A laminate having a thickness of about 109 μm was obtained in the same manner as in Example 1, except that the prepared sealant film (Example 17) was used instead of the sealant film (Example 1). The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Examples 2 to 16) (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0241] [Comparative Examples 1 to 7] A laminate having a thickness of about 109 μm was obtained in the same manner as in Example 1, except that sealant films (Comparative Examples 1 to 7) prepared according to the formulations shown in Table 3 below were used instead of the sealant film (Example 1). The laminate had a structure of biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (about 20 μm) / solvent-based adhesive layer (3.5 μm) / sealant film (Comparative Examples 1 to 7) (60 μm). The mono-material ratio of the laminate was about 91% by mass.

[0242] [Heat resistance evaluation] The laminate obtained above was folded in a V shape so that the surface (first layer) on the sealant film side was on the inside, and the resultant was heat-sealed to a width of 130 mm and a height of 165 mm to produce a bag-shaped pouch. 100 mL of water was poured into the obtained pouch from 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 135°C for a retort time of 30 minutes, and the heat resistance of the laminate was evaluated by checking the appearance change and the presence or absence of temporary adhesion on the inner surface. The results are shown in Tables 1 to 3. <Evaluation criteria> A: No change in appearance B: Wrinkles on the exterior, but no internal adhesion C: Wrinkles appear on the surface, and slight temporary adhesion is observed near the seal edge. D: Wrinkles and temporary adhesion on the inside occur, and the bag shape is not maintained.

[0243] [Evaluation of low temperature sealing properties] The laminate obtained above was folded in a V shape so that the surface (first layer) of the sealant film was on the inside, and a 10 mm wide heat seal was performed at 175°C, after which the presence or absence of leakage and seal recession was checked using a pressure tester (A&D, RTA-1T) to evaluate the low-temperature sealability of the laminate. The results are shown in Tables 1 to 3. <Evaluation criteria> A: Pressure test: 100kgf, pressurized for 1 minute, no leakage, no seal backlash B: Pressure test: 100kgf, pressurized for 1 minute, no leakage, seal retreat less than 5mm C: Pressure test: 75kgf, pressurized for 1 minute, no leakage, no seal backlash B: Pressure test: 75kgf, 1 minute pressure, leaking

[0244] [Impact resistance evaluation] The laminate obtained above was folded in a V shape so that the surface (first layer) of the sealant film was on the inside, and heat-sealed to a width of 130 mm and a height of 165 mm to produce 10 pouches. 150 mL of water was filled into the obtained pouch from the opening, and the opening was heat-sealed to seal it. The sealed 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 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 Tables 1 to 3. <Evaluation criteria> S: No broken bag A: There is no break in the bag, but the seal position has receded. B: The contents are not leaking, but the seal position has receded and there is a gap near the seal edge. C: Two or fewer broken bags D: Three or more broken bags

[0245] [Evaluation of workability] The produced laminate sealant film was placed on a flat surface, and the curling of the sealant film was visually confirmed to evaluate the processability. The results are shown in Tables 1 to 3. <Evaluation criteria> S: Curl less than 1mm A: Curl 1mm or more, less than 3mm B: Curl 3mm or more and less than 5mm C: Curl 5mm or more but less than 10mm D: Curl 10mm or more

[0246] [Seal strength evaluation] The seal strength of the laminate was evaluated by measuring the seal strength after the retort sterilization treatment used in the evaluation of heat resistance described above using a tensile tester (Strograph VG1F, manufactured by Toyo Seiki Seisakusho Co., Ltd.) The results are shown in Tables 1 to 3. <Evaluation criteria> A: 50N or more B: 40N or more C: 30N or more D: 29N or less (transition to interlayer delamination of the sealant film for laminates)

[0247] [Table 1]

[0248] [Table 2]

[0249] [Table 3] [Explanation of symbols]

[0250] 1: laminate, 10: polypropylene resin substrate, 20: barrier substrate, 22: polypropylene resin layer, 23: surface coating layer or surface resin layer, 24: vapor deposition film, 25: barrier 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, When used in the laminate, the laminate at least comprises a first layer located on one surface of the laminate and a second layer in contact with the first layer, the first layer includes a first matrix resin component in an amount of 51% by mass or more and 90% by mass or less with respect to a total amount of the first layer, and a first dispersed component, and has a sea-island structure in which the first dispersed component is dispersed in the first matrix resin component, the second layer includes a second matrix resin component in an amount of 51% by mass or more and 85% by mass or less with respect to a total amount of the second layer, and a second dispersed component, and has a sea-island structure in which the second dispersed component is dispersed in the second matrix resin component, the first matrix resin component comprises a propylene-ethylene random copolymer; the first dispersion component comprises at least 5% by weight or more of polyethylene based on the total weight of the first layer; the second matrix resin component comprises block polypropylene; A sealant film for laminates, wherein the second dispersion component comprises at least 5% by weight or more of polyethylene relative to the total amount of the second layer.

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

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

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

5. The sealant film for laminates according to claim 4 , wherein a content ratio of the first dispersion component to a total amount of the first layer is 10% by mass or more and 49% by mass or less.

6. The sealant film for laminates according to claim 5 , wherein a content ratio of the first dispersion component to a total amount of the first layer is lower than a content ratio of the second dispersion component to a total amount of the second layer.

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

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

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

0.

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

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

0.

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

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

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

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

16. Further comprising a third layer in contact with the second layer; the third layer includes a third matrix resin component in an amount of 51% by mass or more and 85% by mass or less with respect to a total amount of the third layer, and a third dispersed component, and has a sea-island structure in which the third dispersed component is dispersed in the third matrix resin component, The sealant film for laminates according to claim 2 , wherein the third matrix resin component comprises the block polypropylene.

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

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

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

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

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

22. 22. The packaging container of claim 21 which is a boil or retort pouch.

Images