Laminate for packaging material, lid material and packaging container

Abstract

To enhance drop impact resistance in a laminate for a packaging material including a stretched base material containing polypropylene and a sealant layer containing polypropylene.SOLUTION: A laminate for a packaging material comprising a substrate and a sealant layer, wherein the substrate comprises a polypropylene resin layer subjected to a stretching treatment, the sealant layer comprises a propylene-ethylene block copolymer as a main component, a thermoplastic elastomer and polyethylene, and the sealant layer has a melting peak temperature observed in a range of 100 °C or more and less than 120 °C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a laminate for packaging materials, a lid material, and a packaging container. [Background technology]

[0002] Resin films have traditionally been used as packaging materials. For example, resin films made of polyolefins are widely used as sealant films because they are flexible, transparent, and have excellent heat-sealing properties. Resin films made of polyolefins usually cannot be used as substrates due to their lack of strength and heat resistance, and are therefore used in combination with polyester or nylon films. For this reason, typical packaging containers are made of laminated films in which the substrate and sealant film are made of different resin materials (see, for example, Patent Document 1).

[0003] In recent years, with the growing demand for the creation of a recycling-oriented society, there has been a demand for packaging containers with high recyclability. However, conventional packaging containers are made up of different resin materials, and because it is difficult to separate the resin materials, they are not currently recycled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-202519 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have investigated the use of a single polypropylene material from the perspective of using a single material (mono-material) that is easy to recycle. Specifically, the present inventors have investigated using a stretched substrate containing polypropylene as the substrate instead of a polyester film or nylon film, and combining it with a sealant film containing polypropylene. With this configuration, the substrate and sealant film are both made of polypropylene, which can improve the recyclability of the packaging container.

[0006] Packaging containers such as retort pouches desirably have heat resistance sufficient to withstand heat treatment and drop impact resistance sufficient to withstand the impact of dropping the pouch. For example, nylon film has excellent drop impact resistance and has been suitable as a substrate for packaging containers that require drop impact resistance. However, the present inventors have found that a packaging container formed of a laminate including a stretched substrate containing polypropylene and a sealant layer containing polypropylene does not have sufficient drop impact resistance.

[0007] One of the problems to be solved by the present disclosure is to improve the drop impact resistance of a laminate for a packaging material that includes a stretched substrate containing polypropylene and a sealant layer containing polypropylene. [Means for solving the problem]

[0008] The laminate for packaging materials of the present disclosure comprises a substrate and a sealant layer, wherein the substrate comprises a polypropylene resin layer that has been subjected to a stretching treatment, the sealant layer contains a propylene-ethylene block copolymer, a thermoplastic elastomer, and polyethylene as main components, and the sealant layer has a peak melting temperature observed in the range of 100°C or higher and lower than 120°C. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to improve the drop impact resistance of a laminate for a packaging material that includes a stretched substrate containing polypropylene and a sealant layer containing polypropylene. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of a laminate. [Figure 2] FIG. 2 is a schematic cross-sectional view showing one embodiment of the laminate. [Figure 3] FIG. 3 is a schematic cross-sectional view showing one embodiment of the laminate. [Figure 4] FIG. 4 is a schematic cross-sectional view showing one embodiment of the laminate. [Figure 5] FIG. 5 is a schematic cross-sectional view showing one embodiment of the 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 graph illustrating the peak melting temperature of the sealant film. [Figure 11] FIG. 11 is a front view showing one embodiment of a packaging container. [Figure 12] FIG. 12 is a perspective view showing one embodiment of a packaging container. DETAILED DESCRIPTION OF THE INVENTION

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

[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 alone or in combination of two or more types.

[0013] [Laminates for packaging materials] The laminate of the present disclosure comprises a 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-deposited film. The barrier substrate may further include a layer described below. In one embodiment, the substrate is made of a polypropylene resin layer that has been subjected to a stretching treatment. That is, in one embodiment, the substrate is a polypropylene resin substrate that has been subjected to a stretching treatment.

[0014] In the following description, the terms "polypropylene resin layer" and "polypropylene resin substrate" mean "a polypropylene resin layer that has been subjected to a stretching treatment" and "a polypropylene resin substrate that has been subjected to a stretching treatment," respectively, except when describing the stretching treatment. The laminate of the present disclosure is suitable for use as a packaging material.

[0015] The laminate of the present disclosure may include two or more substrates. The laminate of the present disclosure preferably comprises a first substrate, a second substrate, and a sealant layer in this order in the thickness direction, wherein the first substrate and the second substrate are each independently a barrier substrate or a polypropylene resin substrate.

[0016] 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.

[0017] 1 to 9 are schematic cross-sectional views showing an embodiment of a laminate. 1 includes a barrier substrate 20 as a base material, an adhesive layer 40, and a sealant layer 30, in this order in the thickness direction. The barrier substrate 20 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.

[0018] FIG. 2 is the same as FIG. 1 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 .

[0019] 3 is the same as FIG. 1 except that the barrier substrate 20 includes, in this order in the thickness direction, 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 example, the barrier coating layer 25 contacts the adhesive layer 40.

[0020] 4 includes, in this order in the thickness direction, a polypropylene resin substrate 10 as a first substrate, an adhesive layer 40A, a barrier substrate 20 as a second substrate, an adhesive layer 40B, and a sealant layer 30. The barrier substrate 20 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.

[0021] FIG. 5 is the same as FIG. 4 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 .

[0022] 6 is the same as FIG. 4 except that the barrier substrate 20 includes, in this order in the thickness direction, 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 example, the barrier coating layer 25 contacts the adhesive layer 40A.

[0023] 7 includes, in the thickness direction, a barrier substrate 20 as a first substrate, an adhesive layer 40A, a polypropylene resin substrate 10 as a second substrate, an adhesive layer 40B, and a sealant layer 30. The barrier substrate 20 includes a polypropylene resin layer 22 and a vapor-deposited film 24. In this example, the 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.

[0024] FIG. 8 is the same as FIG. 7 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 .

[0025] 9 is the same as FIG. 7 except that the barrier substrate 20 includes, in this order in the thickness direction, 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 example, the barrier coating layer 25 contacts the adhesive layer 40A.

[0026] Specific examples of the layer 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

[0027] 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 gas barrier properties (particularly oxygen barrier properties and water vapor barrier properties).

[0028] When the first substrate is a barrier substrate, in one embodiment, the first substrate is arranged so that the vapor-deposited film faces the sealant layer side and the polypropylene resin layer faces the side opposite to the sealant layer.

[0029] 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, when the second substrate is a barrier substrate, from the viewpoint of further suppressing deterioration of the vapor-deposited film, it is preferable that the second substrate is arranged so that the vapor-deposited film faces the first substrate and the polypropylene resin layer faces the sealant layer.

[0030] 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. 4 to 6). 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 even higher gas barrier properties. Furthermore, the laminate of the above embodiment has a smaller heat shrinkage rate when subjected to heat treatment, and therefore has even better suitability for bag formation.

[0031] The proportion of a single polypropylene-based material in the laminate of the present disclosure (hereinafter also referred to as the "mono-material ratio") is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and particularly preferably 90% by mass or more. This allows, for example, the laminate to be used to produce a mono-material packaging container, thereby improving the recyclability of the packaging container. The higher the mono-material ratio, the better, but the upper limit may be, for example, 99% by mass or 98% by mass.

[0032] In this disclosure, the mono-material ratio refers to the proportion of a single polypropylene-based material relative to the total mass of the laminate. However, if a layer contains polypropylene as the main component (i.e., more than 50% by mass), the mono-material ratio is calculated assuming that polypropylene constitutes 100% by mass of the layer. For example, in the case of a sealant layer composed of 80% by mass of polypropylene, 5% by mass of thermoplastic elastomer, and 15% by mass of polyethylene, the mono-material ratio is calculated assuming that the sealant layer is composed of 100% by mass of polypropylene.

[0033] <Barrier substrate> The barrier substrate comprises a polypropylene resin layer and a vapor-deposited film. In one embodiment, the barrier substrate comprises a polypropylene resin layer and a vapor-deposited film provided on one surface of the resin layer. The polypropylene resin layer is a layer that has been subjected to a stretching treatment. The barrier substrate may comprise a surface coating layer or a surface resin layer between the polypropylene resin layer and the vapor-deposited film. The barrier substrate may comprise a barrier coating layer on the vapor-deposited film.

[0034] (Polypropylene resin layer) The polypropylene resin layer contains polypropylene as a main component, i.e., contains more than 50% by mass of polypropylene. By providing the barrier substrate with the polypropylene resin layer, for example, it is possible to improve the oil resistance of a packaging container produced using the barrier substrate.

[0035] The polypropylene may be any of a propylene homopolymer, a propylene random copolymer, and a propylene block copolymer, or may be a mixture of two or more selected from these.

[0036] A propylene homopolymer is a polymer of propylene only. A propylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene. A propylene block copolymer is a copolymer having a polymer block 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.

[0037] Examples of α-olefins include α-olefins having 2 or more and 20 or less carbon atoms, and specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.

[0038] 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.

[0039] In one embodiment, the melt flow rate (MFR) of the polypropylene may be 0.1 g / 10 min or more and 50 g / 10 min or less, or 0.3 g / 10 min or more and 30 g / 10 min or less, from the viewpoint of film-forming ability and processability. The MFR of the polypropylene is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0040] As the polypropylene, from the viewpoint of reducing the environmental load, biomass-derived polypropylene or mechanically recycled or chemically recycled polypropylene may be used.

[0041] The content of polypropylene 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.

[0042] 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.

[0043] 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.

[0044] The polypropylene resin layer is a layer that has been subjected to a stretching treatment. This can improve, for example, the heat resistance, drop impact resistance, water resistance, and dimensional stability of the laminate. A laminate having such a resin layer is suitable, for example, as a packaging material for constituting a packaging container that is subjected to a boiling treatment or a retort treatment. The stretching treatment may be uniaxial stretching or biaxial stretching.

[0045] When stretching in the machine direction (machine direction, MD, of the substrate), the stretching ratio is preferably 2 to 15, more preferably 5 to 13. When stretching in the transverse direction (direction perpendicular to the MD, TD), the stretching ratio is preferably 2 to 15, more preferably 5 to 13. By setting the stretching ratio to 2 or more, the strength and heat resistance of the polypropylene resin layer can be further improved, and the printability of the polypropylene resin layer can be improved. From the viewpoint of the breaking limit of the polypropylene resin layer, the stretching ratio is preferably 15 or less.

[0046] In one embodiment, the polypropylene resin layer may be subjected to a surface treatment. This can improve, for example, the adhesion between the polypropylene resin layer and other layers. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, and glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals. An easy-adhesion layer may be provided on the surface of the polypropylene resin layer.

[0047] The polypropylene resin layer may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin layer is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved.

[0048] (surface coating layer) In one embodiment, the barrier substrate includes a surface coating layer containing a resin material having a polar group between the polypropylene resin layer and the vapor-deposited film. By providing the surface coating layer containing a resin material having a polar group, it is possible to improve the adhesion of the vapor-deposited film formed on the surface coating layer and also improve the gas barrier properties.

[0049] 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. This barrier substrate comprises the polypropylene resin layer, the surface coating layer, and the vapor-deposited film in this order in the thickness direction.

[0050] The polar group refers to a group containing one or more heteroatoms, and examples thereof include an ester group, an epoxy group, a hydroxyl group, an amino group, an amide group, a urethane group, a carboxyl group, a carbonyl group, a carboxylic anhydride group, a sulfo group, a thiol group, and a halogen group. Among these, from the viewpoint of lamination properties of the packaging container, the carboxyl group, the carbonyl group, the ester group, the hydroxyl group, the amino group, the amide group, and the urethane group are preferred, and the carboxyl group, the hydroxyl group, the amide group, and the urethane group are more preferred.

[0051] 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.

[0052] The surface coating layer can be formed using, for example, an aqueous emulsion or a solvent-based emulsion. Examples of aqueous emulsions include polyamide-based emulsions, polyethylene-based emulsions, and polyurethane-based emulsions. Examples of solvent-based emulsions include (meth)acrylic resin-based emulsions and polyester-based emulsions.

[0053] The content of the resin material having a polar group in the surface coating layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The surface coating layer may contain a resin material other than the resin material having a polar group. The surface coating layer may contain the above-mentioned additives.

[0054] 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% to 20%, more preferably 0.2% to 15%, even more preferably 1% to 10%, and even more preferably 1% to 5%. When this ratio is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When this ratio is equal to or less than the upper limit, for example, the processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0055] The thickness of the surface coating layer is preferably 0.02 μm to 10 μm, more preferably 0.05 μm to 10 μm, even more preferably 0.1 μm to 10 μm, and even more preferably 0.2 μm to 5 μm. When the thickness is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0056] For example, a resin film is obtained by forming polypropylene or a resin composition containing polypropylene into a film using a T-die method, an inflation method, or the like, and then the resin film is stretched. A coating liquid for forming a surface coating layer is applied to the stretched resin film and dried, thereby producing a resin substrate having a polypropylene resin layer and a surface coating layer.

[0057] (Surface resin layer) In one embodiment, the barrier substrate has a surface resin layer between the polypropylene resin layer and the vapor-deposited film, the surface resin layer containing a resin material having a melting point of 180° C. or higher (hereinafter also referred to as a "high-melting-point resin material") By providing a surface resin layer containing a high-melting-point resin material, it is possible to improve the adhesion of the vapor-deposited film formed on the surface resin layer and also improve the gas barrier properties.

[0058] 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 polypropylene resin layer, the surface resin layer, and the vapor-deposited film being arranged in this order in the thickness direction.

[0059] The melting point of the high-melting-point resin material is preferably 185° C. or higher, more preferably 190° C. or higher, and even more preferably 205° C. or higher. When the melting point is equal to or higher than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved.

[0060] The melting point of the high-melting-point resin material is preferably 265° C. or lower, more preferably 260° C. or lower, and even more preferably 250° C. or lower, which can improve, for example, the film-forming properties of the resin substrate.

[0061] In this specification, the melting point can be measured in accordance with JIS K7121:2012 (Method for measuring transition temperature of plastics). Specifically, the melting point can be determined by measuring a DSC curve using differential scanning calorimetry (DSC) at a temperature rise rate of 10°C / min.

[0062] 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 this difference is the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When this difference is the upper limit or less, for example, the film-forming properties of the resin substrate can be further improved.

[0063] 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.

[0064] The high-melting-point resin material may have a melting point of 180°C or higher, and examples thereof 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 preferred, and more preferred are ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyester, and polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon.

[0065] The content of the high-melting-point resin material in the surface resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0066] 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.

[0067] The ratio of the thickness of the surface resin layer to the total thickness of the resin substrate having the polypropylene resin layer and the surface resin layer is preferably 1% to 10%, more preferably 1% to 5%. When this ratio is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When this ratio is equal to or less than the upper limit, for example, the film-forming ability and processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0068] 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-deposited film can be further improved, the gas barrier properties can be further improved, and the laminate strength of the packaging container can be further improved. When the thickness is equal to or less than the upper limit, for example, the film-forming property and processability of the resin substrate and the recyclability of the packaging container can be further improved.

[0069] In one embodiment, the resin substrate may include an adhesive resin layer between the polypropylene resin layer and the surface resin layer, thereby improving adhesion between these layers.

[0070] The adhesive resin layer can be formed, for example, from an adhesive resin. Examples of adhesive resins include polyether, polyester, polyurethane, silicone resin, epoxy resin, vinyl resin, phenolic resin, polyolefin, and acid-modified polyolefin. Among these, from the viewpoint of the recyclability of the packaging container, polyolefin and acid-modified polyolefin are preferred, and polypropylene and acid-modified polyolefin are more preferred.

[0071] 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.

[0072] In one embodiment, the resin substrate having a polypropylene resin layer and, if necessary, an adhesive resin layer and a surface resin layer is a coextruded stretched resin film. The coextruded stretched resin film can be produced, for example, by forming a laminated film using a T-die method or an inflation method, and then stretching the laminated film. By forming the film using the inflation method, the laminated film may be stretched simultaneously.

[0073] The stretching treatment 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.

[0074] (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 coating layer or the surface resin layer. This can improve the gas barrier properties of the laminate, specifically the oxygen barrier properties and water vapor barrier properties. A packaging container made using the laminate can suppress weight loss of the contents filled in the packaging container.

[0075] 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.

[0076] In one embodiment, silica is more preferable as the inorganic oxide because it does not require aging treatment after forming the vapor-deposited film. In one embodiment, carbon-containing silicon oxide is more preferable as the inorganic oxide because it can suppress deterioration in gas barrier properties even when the laminate is bent.

[0077] The thickness of the vapor-deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less. When the thickness is equal to or greater than the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the occurrence of cracks in the vapor-deposited film can be suppressed, and the recyclability of the packaging container can be improved.

[0078] The surface of the vapor-deposited film is preferably subjected to the above-mentioned surface treatment, which can improve the adhesion between the vapor-deposited film and the adjacent layer.

[0079] Examples of methods for forming a vapor-deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0080] The vapor-deposited film may be a single layer formed by a single vapor deposition process, or may be a multilayer formed by multiple vapor deposition processes. When the vapor-deposited film is a multilayer film, each layer may be composed of the same inorganic oxide or different inorganic oxides. Each layer may be formed by the same method or different methods.

[0081] The vapor-deposited film in the barrier substrate is preferably a vapor-deposited film formed by a CVD method, and more preferably a carbon-containing silicon oxide vapor-deposited film formed by a CVD method, which can prevent a decrease in gas barrier properties even when the laminate is bent.

[0082] The carbon-containing silicon oxide vapor-deposited film contains silicon, oxygen, and carbon. In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the carbon content C is preferably 3% to 50%, more preferably 5% to 40%, and even more preferably 10% to 35%, relative to the total of the three elements silicon, oxygen, and carbon (100%). By setting the carbon content C within the above range, for example, deterioration in gas barrier properties can be suppressed even when the laminate is bent. In this specification, the proportion of each element is on a molar basis.

[0083] In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the silicon content Si is preferably 1% to 45%, more preferably 3% to 38%, and even more preferably 8% to 33%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. The oxygen content O is preferably 10% to 70%, more preferably 20% to 65%, and even more preferably 25% to 60%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the silicon content Si and the oxygen content O within the above ranges, for example, deterioration of the gas barrier property can be further suppressed even when the laminate is bent.

[0084] In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the oxygen ratio O is preferably higher than the carbon ratio C, and the silicon ratio Si is preferably lower than the carbon ratio C. The oxygen ratio O is preferably higher than the silicon ratio Si, that is, the ratios preferably decrease in the order of ratio O, ratio C, and ratio Si. This makes it possible to further suppress a decrease in gas barrier properties, for example, even when the laminate is bent.

[0085] 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.

[0086] (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 diameter 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, and the spectrum was collected.

[0087] (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.

[0088] In one embodiment, the barrier coat layer contains a gas barrier resin, such as an ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, polyurethane, or (meth)acrylic resin.

[0089] The content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Such a configuration can improve, for example, the gas barrier properties of the barrier coat layer. The barrier coat layer may contain the above-mentioned additives.

[0090] 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.

[0091] The barrier coat layer can be formed, for example, by applying and drying a coating liquid obtained by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent.

[0092] In another embodiment, the barrier coat layer is a gas barrier coating film formed by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, and optionally adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, which is then applied to a vapor-deposited film and dried. The gas barrier coating film contains a hydrolysis polycondensate obtained by hydrolyzing and polycondensing the metal alkoxide or the like by a sol-gel method. By providing such a barrier coat layer on the vapor-deposited film, the occurrence of cracks in the vapor-deposited film can be effectively suppressed.

[0093] The metal alkoxide is represented by, for example, 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 valence of M.

[0094] 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.

[0095] Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0096] Examples of water-soluble polymers include hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties, such as oxygen barrier property, water vapor barrier property, water resistance, and weather resistance, either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Alternatively, a gas barrier coating film obtained using polyvinyl alcohol and a gas barrier coating film obtained using an ethylene-vinyl alcohol copolymer may be laminated. The amount of water-soluble polymer used is preferably 3 to 500 parts by mass per 100 parts by mass of the metal alkoxide.

[0097] As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and an organoalkoxysilane having an epoxy group is preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the metal alkoxide.

[0098] The gas barrier composition may contain water in a proportion of preferably 0.1 to 100 moles, more preferably 0.5 to 60 moles, per mole of metal alkoxide. By setting the water content at or above the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved. By setting the water content at or below the upper limit, for example, the hydrolysis reaction can be carried out quickly.

[0099] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol.

[0100] The sol-gel catalyst is preferably an acid or an amine compound. Examples of the acid include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less per mol of the total molar amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

[0101] The amine compound is preferably a tertiary amine that is substantially insoluble in water and soluble in an organic solvent, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of the amine compound used is preferably 0.01 to 1.0 parts by mass, more preferably 0.03 to 0.3 parts by mass, relative to 100 parts by mass of the total amount of the metal alkoxide and the silane coupling agent.

[0102] Examples of methods for applying the gas barrier composition include roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

[0103] 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 progresses within the composition. The composition is then coated onto the vapor-deposited film by a conventional method and dried. This drying process further promotes polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above process. For example, the coated 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 process allows the formation of a gas barrier coating film.

[0104] 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-deposited film, and improve the recyclability of the packaging container, for example.

[0105] <Polypropylene resin base material> The polypropylene resin substrate is composed of the above-described polypropylene resin layer. The polypropylene resin substrate is a substrate that has been subjected to a stretching treatment. The details of the polypropylene resin layer and the stretching treatment are as described above, and a detailed description thereof will be omitted here.

[0106] The polypropylene resin substrate may have a single-layer structure or a multi-layer structure. The thickness of the polypropylene resin substrate is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved.

[0107] (Printing layer) The laminate of the present disclosure may have a printed layer on the surface of a substrate such as a barrier substrate or a polypropylene resin substrate. The image formed on the printed layer is not particularly limited, and may represent letters, patterns, symbols, or combinations thereof. The printed layer may also be formed using ink derived from biomass. This can further reduce the environmental impact.

[0108] Examples of methods for forming the printed layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of reducing environmental impact.

[0109] The thickness of the printing layer is, for example, 0.5 μm or more and 3 μm or less.

[0110] <Sealant layer> The laminate of the present disclosure includes a sealant layer. The sealant layer contains a propylene-ethylene block copolymer as a main component, a thermoplastic elastomer, and polyethylene, which can improve the drop impact resistance of the laminate, for example.

[0111] The sealant layer contains a propylene-ethylene block copolymer as a main component, that is, the propylene-ethylene block copolymer is contained in an amount of more than 50 mass %.

[0112] The use of the propylene-ethylene block copolymer can improve the drop impact resistance of the sealant layer, and therefore the laminate, for example, which can prevent damage to a packaging container caused by the impact of being dropped when the laminate is used to produce the packaging container.

[0113] By including a propylene-ethylene block copolymer as the main component in the sealant layer, it is possible to achieve, for example, a mono-material packaging container. The propylene-ethylene block copolymer corresponds to polypropylene in the calculation of the mono-material content rate. This eliminates the need to separate the base material and the sealant layer after collecting used packaging containers, improving the recyclability of the packaging containers.

[0114] In one embodiment, the propylene-ethylene block copolymer includes a polymer portion (a) made of a propylene polymer and a polymer portion (b) made of polyethylene and an ethylene-propylene copolymer rubber component. In one embodiment, the propylene-ethylene block copolymer includes a sea portion made of a propylene polymer and an island portion made of polyethylene and an ethylene-propylene copolymer rubber component. The polymer portion (a) and the sea portion can contribute to improving the blocking resistance, heat resistance, rigidity, and seal strength of the propylene-ethylene block copolymer. The polymer portion (b) and the island portion can contribute to improving the impact resistance of the propylene-ethylene block copolymer. Therefore, by adjusting the ratio of the polymer portion (a) to the polymer portion (b) and the ratio of the sea portion to the island portion, the mechanical properties of a sealant layer containing the propylene-ethylene block copolymer can be adjusted.

[0115] In one embodiment, the propylene polymer of the polymer portion (a) is a propylene homopolymer having a melting point of 160° C. or higher. The propylene polymer may be a copolymer of propylene and a small amount (for example, 5 mol % or less) of an α-olefin, so long as it has a melting point of 160° C. or higher. Examples of α-olefins include ethylene, 1-butene, 1-hexene, and 1-octene.

[0116] In the polymer portion (b), for example, in the polyethylene and ethylene-propylene copolymer rubber components, the content of ethylene-derived structural units may be 20% by mass or more and 50% by mass or less. This can further improve, for example, drop impact resistance. In the present disclosure, the content of structural units can be measured, for example, by NMR.

[0117] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (a) or sea portion consisting of a propylene polymer is preferably higher than the mass ratio of the polymer portion (b) or island portion consisting of polyethylene and an ethylene-propylene copolymer rubber component.

[0118] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (a) consisting of a propylene polymer or the sea component is preferably 51 mass% or more, more preferably 60 mass% or more, and even more preferably 70 mass% or more. The upper limit of the mass ratio of the polymer portion (a) consisting of a propylene polymer or the sea component is, for example, 90 mass%.

[0119] In the propylene-ethylene block copolymer, the mass ratio of the polymer portion (b) consisting of polyethylene and ethylene-propylene copolymer rubber components or island components is preferably 49 mass% or less, more preferably 40 mass% or less, and even more preferably 30 mass% or less. The lower limit of the mass ratio of the polymer portion (b) consisting of polyethylene and ethylene-propylene copolymer rubber components or island components is, for example, 10 mass%.

[0120] The melt flow rate (MFR) of the propylene-ethylene block copolymer is preferably 0.5 g / 10 min or more and 10 g / 10 min or less, more preferably 1 g / 10 min or more and 5 g / 10 min or less, and is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0121] Propylene-ethylene block copolymers can be produced, for example, by polymerizing raw materials such as propylene and ethylene using a catalyst, such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0122] The sealant layer further contains a thermoplastic elastomer. By using the thermoplastic elastomer, for example, the drop impact resistance of the laminate can be further improved.

[0123] Examples of the thermoplastic elastomer include hydrogenated styrene-based thermoplastic elastomers and ethylene-α-olefin elastomers, with hydrogenated styrene-based thermoplastic elastomers being preferred.

[0124] The hydrogenated styrene-based thermoplastic elastomer has a polymer block A mainly composed of structural units derived from a vinyl aromatic compound, and a hydrogenated polymer block B mainly composed of structural units derived from a conjugated diene compound. The hydrogenated styrene-based thermoplastic elastomer has at least one polymer block A and at least one polymer block B. Examples of the block structure include ABA, BABA, and BABAB. In one embodiment, the hydrogenated styrene-based thermoplastic elastomer may have structural units derived from a vinyl aromatic compound in a range of 10% by mass to 40% by mass.

[0125] Examples of vinyl aromatic compounds constituting polymer block A include styrene and α-methylstyrene, with styrene being preferred. Examples of conjugated diene compounds constituting polymer block B include butadiene, isoprene, and 1,3-pentadiene, with butadiene and isoprene being preferred.

[0126] Polymer block B is a hydrogenated polymer block mainly composed of structural units derived from a conjugated diene compound, and in one embodiment, is an olefin-based compound polymer block. In the hydrogenated styrene-based thermoplastic elastomer, preferably 80 mol % or more, more preferably 90 mol % or more of the aliphatic double bonds derived from the conjugated diene compound are hydrogenated.

[0127] Examples of hydrogenated styrene-based thermoplastic elastomers include styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / propylene-styrene block copolymer (SEPS), with SEBS being preferred. SEBS can be obtained, for example, by adding hydrogen to the aliphatic double bonds of a styrene-butadiene-styrene block copolymer. SEPS can be obtained, for example, by adding hydrogen to the aliphatic double bonds of a styrene-isoprene-styrene block copolymer.

[0128] Ethylene-α-olefin elastomers are low-crystalline or amorphous copolymer elastomers, which are random copolymers of ethylene units (main component) at 50% to 90% by mass and α-olefin units (comonomers). Ethylene-α-olefin elastomers are preferably produced using a metallocene catalyst.

[0129] Examples of α-olefins include α-olefins having 3 to 10 carbon atoms, specifically propylene, 1-butene, 1-hexene, and 1-octene. Examples of ethylene-α-olefin elastomers include ethylene-propylene random copolymers, ethylene-1-butene random copolymers, and ethylene-1-octene random copolymers.

[0130] The MFR of the thermoplastic elastomer is preferably 0.1 g / 10 min or more and 10 g / 10 min or less, more preferably 0.2 g / 10 min or more and 5 g / 10 min or less. The MFR of the thermoplastic elastomer is measured in accordance with JIS K7210 at a temperature of 230°C or 190°C under a load of 2.16 kg.

[0131] The sealant layer further contains polyethylene. By using polyethylene, for example, the drop impact resistance of the laminate can be further improved. As the polyethylene, for example, 3 Polyethylene, preferably with a density of 900 kg / m or less 3 More than 925kg / m 3 Examples of polyethylene include the following: The density is measured in accordance with JIS K7112, particularly Method D (density gradient tube method, 23°C).

[0132] The polyethylene may be, for example, linear low-density polyethylene or low-density polyethylene. The polyethylene is preferably linear low-density polyethylene. Linear low-density polyethylene has good adhesion to the propylene polymer, which is the polymer portion (a) or the sea component of the propylene-ethylene block copolymer described above. Therefore, when the polyethylene is linear low-density polyethylene, peeling between the resins of the sealant layer can be suppressed. Polyethylene can contribute to improving the impact resistance of the sealant layer.

[0133] 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 Linear low-density polyethylene can be obtained, for example, by copolymerizing ethylene and an α-olefin under medium or low pressure to introduce short-chain branches derived from the α-olefin. Examples of the α-olefin include α-olefins having from 4 to 10 carbon atoms, such as 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0134] The density of the low density polyethylene is preferably 900 kg / m 3 More than 925kg / m 3 Less than or equal to 910 kg / m 3 More than 925kg / m 3 Low-density polyethylene is obtained by polymerizing ethylene at a high pressure of, for example, 1000 atmospheres or more but less than 2000 atmospheres. Low-density polyethylene is also called high-pressure low-density polyethylene.

[0135] As the polyethylene, from the viewpoint of reducing the environmental load, biomass-derived polyethylene or mechanically recycled or chemically recycled polyethylene may be used.

[0136] The melting point (Tm) of the polyethylene may be 100° C. or higher and 120° C. or lower, or 105° C. or higher and 120° C. or lower. The Tm of the polyethylene is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0137] The MFR of 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 polyethylene is measured in accordance with JIS K7210 at a temperature of 190°C and a load of 2.16 kg.

[0138] In the sealant layer, it is preferable that the content of polyethylene is greater than that of the thermoplastic elastomer, and the content of propylene-ethylene block copolymer is greater than that of polyethylene, on a mass basis, which can further improve, for example, drop impact resistance.

[0139] The content of the propylene-ethylene block copolymer in the sealant layer is preferably 51% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The content of the propylene-ethylene block copolymer in the sealant layer is, for example, 94% by mass or less.

[0140] The polyethylene content in the sealant layer is preferably 5% by mass or more, more preferably 10% by mass or more. The polyethylene content in the sealant layer is, for example, 30% by mass or less. When the polyethylene content is equal to or greater than the lower limit, for example, drop impact resistance can be further improved. When the polyethylene content is equal to or less than the upper limit, for example, blocking resistance can be further improved.

[0141] The content of the thermoplastic elastomer in the sealant layer is preferably 1% by mass or more, more preferably 3% by mass or more, and is, for example, 15% by mass or less.

[0142] The sealant layer may contain the above-mentioned additives.

[0143] The sealant layer may have a single-layer structure or a multi-layer structure. The thickness of the sealant layer is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less. When the thickness is equal to or more than the lower limit, for example, the laminate strength of a packaging container including the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved. 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 100 μm or less, more preferably 40 μm or more and 100 μm or less, and even more preferably 60 μm or more and 100 μm or less.

[0144] The sealant layer has a melting peak temperature observed in the range of 100°C or higher and lower than 120°C (hereinafter also referred to as the "first melting peak temperature P1"). The sealant layer may further have a melting peak temperature observed in the range of 120°C or higher and lower than 135°C (hereinafter also referred to as the "second melting peak temperature P2"). The sealant layer may further have a melting peak temperature observed in the range of 160°C or higher (hereinafter also referred to as the "third melting peak temperature P3").

[0145] In the sealant layer, P1 is observed in the range of 100°C or higher and lower than 120°C, and preferably P2 is observed in the range of 120°C or higher and lower than 135°C, thereby improving the drop impact resistance of packaging containers produced using the laminate. In the sealant layer, P3 is observed in the range of 160°C or higher, thereby improving the heat resistance of packaging containers produced using the laminate.

[0146] The melting peak temperature of each sealant layer is obtained by differential scanning calorimetry (DSC). In the present disclosure, the conditions for measuring the melting peak temperature of the sealant layer are as follows: First, a standing pouch is prepared from the laminate, water is filled into the resulting pouch through the opening, and the opening is heat-sealed to seal. The sealed pouch is then subjected to a hot water retort treatment at a retort temperature of 121°C for 30 minutes. From the standing pouch after the retort treatment, a sealant film corresponding to the sealant layer in the non-heat-sealed portion is separated as a test piece. In accordance with JIS K7121, the separated sealant film is held at 20°C for 1 minute, and then heated from 20°C to 200°C at a heating rate of 10°C / min to measure the melting peak temperature. The nitrogen gas flow rate is 20 ml / min. Details of the above conditions are described in the Examples section. Here, the melting peak temperature refers to the peak-top temperature of the melting peak in the DSC curve. An example of the DSC measurement results of a sealant layer having P1, P2 and P3 is shown in FIG.

[0147] The sealant film can be produced by, for example, a conventionally known method. The sealant film can be obtained by mixing the above-mentioned materials by a conventional method and molding the resulting mixture into a film by a conventional method. The sealant film is preferably a film obtained by extrusion molding. The extrusion molding is preferably carried out by a T-die method or an inflation method. Specifically, the materials constituting the sealant film are dried as necessary, and then fed into a melt extruder heated to a temperature equal to or higher than the melting point of the material to melt the material, and extruded into a film form through a die such as a T-die, and the extruded film-like material is rapidly cooled and solidified on a rotating cooling drum or the like, thereby forming a sealant film.

[0148] As the melt extruder, a single-screw extruder, a twin-screw extruder, a vent extruder, a tandem extruder, etc. can be used depending on the purpose. The temperature of the molten polymer when extruded from the melt extruder may be, for example, 200°C or higher and 300°C or lower, or 220°C or higher and 270°C or lower.

[0149] From the viewpoint of heat sealing properties, the sealant layer is preferably an unstretched resin film. The resin film can be produced by, for example, a casting method, a T-die method, or an inflation method. The sealant layer may be subjected to the above-mentioned surface treatment.

[0150] <Adhesive layer> In one embodiment, the laminate includes an adhesive layer between the substrate and the sealant layer. In one embodiment, the laminate includes a first adhesive layer between the first substrate and the second substrate. In one embodiment, the laminate includes a second adhesive layer between the second substrate and the sealant layer. This can improve the adhesion between the substrate and the sealant layer, the adhesion between the first substrate and the second substrate, and the adhesion between the second substrate and the sealant layer.

[0151] The adhesive layer is composed of an adhesive. The adhesive may be a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive. The adhesive may be a solventless adhesive or a solvent-based adhesive. In one embodiment, the laminate of the present disclosure includes at least three elements: a polypropylene resin substrate, a barrier substrate, and a sealant layer. This allows the laminate to be produced using an adhesive without directly applying an adhesive onto the vapor-deposited film, and deterioration of the vapor-deposited film can be suppressed.

[0152] 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.

[0153] In one embodiment, the solventless adhesive is a two-component curing adhesive having a base agent and a curing agent. From the viewpoint of coatability, the weight-average molecular weight (Mw) of the polymer component contained in the base agent is preferably 800 or more and 10,000 or less, more preferably 1,200 or more and 4,000 or less. The polydispersity index (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.

[0154] Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and polyurethane-based adhesives. Among these, polyurethane-based adhesives are preferred, and two-component curing polyurethane-based adhesives are more preferred.

[0155] In one embodiment, forming an adhesive layer using a solvent-free adhesive can further reduce, for example, the amount of residual solvent in the laminate, specifically the amount of residual organic solvent. The laminate of the present disclosure includes a polypropylene resin layer. Therefore, when producing a laminate of the present disclosure using a solvent-based adhesive, the drying temperature must be lowered compared to polyester-based laminates to prevent deterioration and thermal shrinkage of the laminate. In this case, the solvent in the adhesive may not be sufficiently volatilized and remain in the laminate, resulting in an odor due to the residual solvent. By using a solvent-free adhesive, the amount of residual solvent can be further reduced.

[0156] 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.

[0157] In one embodiment, the use of a solvent-free adhesive allows, for example, a thinner adhesive layer than when a solvent-based adhesive is used. This allows for a higher polypropylene content in the entire laminate. Such a laminate is suitable for producing a mono-material packaging container.

[0158] 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.

[0159] The method for producing the laminate of the present disclosure is not particularly limited, and it can be produced using a conventionally known method such as a dry lamination method, a melt extrusion lamination method, a sand lamination method, etc. For example, in one embodiment, the laminate of the present disclosure may be produced by bonding a substrate and a sealant film, or a first substrate, a second substrate, and a sealant film, by a non-solvent lamination method using a solvent-free adhesive, or by a dry lamination method using a solvent-based adhesive.

[0160] A two-component curing polyurethane adhesive will be described below. As this 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 polyol compounds include polyester polyols, polyether polyols, polycarbonate polyols, and (meth)acrylic polyols. Among these, polyester polyols are preferred.

[0161] Polyester polyols have two or more hydroxyl groups per molecule. The polyester polyols have, for example, a polyester structure or a polyester polyurethane structure as the main skeleton. The polyester polyols can be obtained, for example, by a dehydration condensation reaction, transesterification, or ring-opening reaction between a polyhydric alcohol component and a polycarboxylic acid component.

[0162] Examples of polyhydric alcohol components 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.

[0163] Examples of polycarboxylic acid components include aliphatic polycarboxylic acids, alicyclic polycarboxylic acids, and aromatic polycarboxylic acids, as well as their ester derivatives and acid anhydrides. Examples of aliphatic polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, and dimer acid. Examples of alicyclic polycarboxylic acids include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Examples of aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid.

[0164] 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.

[0165] From the viewpoint of coatability, the weight-average molecular weight (Mw) of the polyol compound such as polyester polyol is preferably 800 or more and 10,000 or less, more preferably 1,200 or more and 4,000 or less. The polydispersity index (Mw / Mn) of the polyol compound such as polyester polyol is preferably 2.8 or less, more preferably 1.2 or more and 2.7 or less, even more preferably 1.5 or more and 2.6 or less, and particularly preferably 2.0 or more and 2.5 or less. Here, Mn is the number-average molecular weight of the polyol compound. Each average molecular weight is measured by gel permeation chromatography (GPC) in accordance with JIS K7252-1 (2008) and is a value converted into polystyrene.

[0166] The isocyanate compound has two or more isocyanate groups in one molecule. Examples of the isocyanate compound include aromatic isocyanates and aliphatic isocyanates. The isocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known, conventional, appropriate method.

[0167] 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.

[0168] 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.

[0169] [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.

[0170] The packaging container of the present disclosure includes the laminate of the present disclosure (hereinafter also simply referred to as "laminate"). Examples of packaging containers include packaging bags, tube containers, and containers with lids. The containers with lids include a container body having a storage section and a lid material joined (heat sealed) to the container body so as to seal the storage section.

[0171] In one embodiment, the packaging container of the present disclosure maintains gas barrier properties even when subjected to high-temperature treatment and exhibits minimal deformation, making it suitable as a microwave oven container or a boiling or retort container. The packaging container of the present disclosure is also suitable as a microwave boiling or retort container. The packaging container of the present disclosure is particularly suitable as a boiling or retort pouch.

[0172] Examples of heat sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0173] Examples of packaging bags include various types of packaging bags such as a standing pouch type, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a palm seal type (pillow seal type), a pleated seal type, a flat bottom seal type, a square bottom seal type, and a gusset type.

[0174] 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.

[0175] The packaging container may include a steam release mechanism that is configured to connect the inside and outside of the packaging container when the steam pressure inside the packaging container reaches or exceeds a predetermined value, thereby allowing the steam to escape and preventing the steam from escaping at locations other than the steam release mechanism.

[0176] The steam release mechanism includes, for example, a steam release seal portion that protrudes from the side seal portion toward the inside of the packaging container, and an unsealed portion that is isolated from the content storage portion by the steam release seal portion. The unsealed portion is in communication with the outside of the packaging container. The packaging container is filled with content and the opening is heat-sealed, and is heated using a microwave oven or the like. This increases the internal pressure, causing the steam release seal portion to peel. Steam passes through the peeled portion of the steam release seal portion and the unsealed portion and escapes to the outside of the packaging container.

[0177] In one embodiment, a packaging bag can be produced by folding the laminate of the present disclosure in half and overlapping them so that the substrate is on the outside and the sealant layer is on the inside, and then heat-sealing the edges, etc. In another embodiment, a packaging bag can be produced by overlapping multiple laminates of the present disclosure so that the sealant layers face each other, and then heat-sealing the edges, etc. The entire packaging bag may be made of the above-mentioned laminate, or only a portion of the packaging bag may be made of the above-mentioned laminate.

[0178] 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.

[0179] The contents to be contained in the packaging container include, for example, liquids, solids, powders, and gels. The contents may be food or beverages, or non-food or beverages such as chemicals, cosmetics, and pharmaceuticals. After the contents are contained in the packaging container, the opening of the packaging container can be heat-sealed to seal the packaging container.

[0180] As specific examples of packaging bags, small pouches and standing pouches will be described below. A sachet is a small packaging bag used to hold contents of, for example, 1 g to 200 g, such as sauces, soy sauce, dressings, ketchup, syrup, cooking alcohol, other liquid or viscous seasonings, liquid soups, powdered soups, fruit juices, spices, liquid beverages, jelly-like beverages, instant foods, and other foods and beverages.

[0181] Stand-up pouches are used to store contents of, for example, 50 g to 2000 g, including shampoo, rinse, conditioner, hand soap, body soap, air freshener, deodorant, insect repellent, detergent, dressing, cooking oil, mayonnaise, other liquid or viscous seasonings, liquid beverages, jelly-like beverages, instant foods, other foods and beverages, and creams.

[0182] 11 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 portion 51. Examples of the easy-to-open portion 51 include a notch portion 52 that serves as a tearing starting point and a half-cut line 53 formed by laser processing or a cutter as a tearing path.

[0183] FIG. 12 shows a simplified example of the configuration of a stand-up pouch. The shaded areas indicate the heat-sealed areas. In one embodiment, a stand-up pouch 60 comprises a body portion (side sheets) 61 and a bottom portion (bottom sheet) 62. The side sheets 61 and the bottom sheet 62 may be made of the same material, or may be made of different materials. The bottom sheet 62 maintains the shape of the side sheets 61, thereby imparting self-supporting properties to the pouch and enabling it to become a standing pouch. A storage space for storing contents is formed within the area surrounded by the side sheets 61 and the bottom sheet 62.

[0184] The standing pouch 60 may be provided with a steam release mechanism 63. The steam release mechanism 63 includes a steam release seal portion 63a that protrudes from the side seal portion toward the inside of the packaging container, and a non-sealed portion 63b that is isolated from the content-accommodating portion by the steam release seal portion 63a. The non-sealed portion 63b communicates with the outside of the packaging container.

[0185] 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.

[0186] 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 laminates of the present disclosure, overlapping them with the sealant layers facing each other, and heat-sealing both side edges to form a bag.

[0187] In another embodiment, the side sheets can be formed by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, inserting two V-shaped laminates with the sealant layers facing outward between the laminates at the side edges on both sides of the overlapped laminates, and heat-sealing the laminates. This production method produces a stand-up pouch having a body with side gussets.

[0188] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower portions of the side sheets of a bag and heat sealing them. More specifically, the bottom sheet can be formed by inserting the laminate folded in a V shape with the sealant layer facing outward between the lower portions of the side sheets of a bag and heat sealing them.

[0189] In one embodiment, two of the above laminates are prepared and stacked together with the sealant layers facing each other. Then, another of the above laminates is folded in a V shape with the sealant layer facing outward, and this is sandwiched between the two laminates and heat-sealed to form a bottom. Next, two sides adjacent to the bottom are heat-sealed to form a body. In this manner, a standing pouch according to one embodiment can be formed.

[0190] The present disclosure relates to, for example, the following [1] to

[17] . [1] A laminate for packaging materials comprising a substrate and a sealant layer, wherein the substrate comprises a polypropylene resin layer that has been subjected to a stretching treatment, the sealant layer contains a propylene-ethylene block copolymer, a thermoplastic elastomer, and polyethylene as main components, and the sealant layer has a peak melting temperature observed in the range of 100°C or higher but lower than 120°C. [2] The laminate for packaging materials according to [1] above, wherein the sealant layer further has a peak melting temperature observed in the range of 120°C or higher but lower than 135°C, and / or a peak melting temperature observed in the range of 160°C or higher. [3] The laminate for packaging materials according to [1] or [2] above, wherein the sealant layer contains a larger proportion of polyethylene than the thermoplastic elastomer, and a larger proportion of propylene-ethylene block copolymer than polyethylene, on a mass basis. [4] Polyethylene has a density of 925 kg / m 3 The laminate for packaging materials according to any one of the above [1] to [3], which is the following linear low-density polyethylene: [5] The laminate for packaging materials according to any one of the above [1] to [4], wherein the substrate is a barrier substrate comprising a polypropylene resin layer and a vapor-deposited film, and the vapor-deposited film is composed of an inorganic oxide. [6] The laminate for packaging materials according to the above [5], wherein the barrier substrate further comprises a surface coating layer between the polypropylene resin layer and the vapor-deposited film, and the surface coating layer contains a resin material having a polar group. [7] The laminate for packaging materials according to [5] above, wherein the barrier substrate further comprises a surface resin layer between the polypropylene resin layer and the vapor-deposited film, and the surface resin layer contains a resin material having a melting point of 180°C or higher. [8] The laminate for packaging materials according to the above [7], wherein the polypropylene resin layer and the surface resin layer in the barrier substrate constitute a co-extruded stretched resin film. [9] The laminate for packaging materials according to any one of the above [5] to [8], further comprising a barrier coat layer on the vapor-deposited film.

[10] The laminate for packaging materials according to any one of the above [5] to [9], wherein the laminate comprises a first substrate, a second substrate, and the sealant layer in this order in the thickness direction, and the first substrate and the second substrate are each independently a barrier substrate or a polypropylene resin substrate that has been subjected to a stretching treatment.

[11] The laminate for packaging materials according to the above

[10] , wherein the first substrate is a polypropylene resin substrate and the second substrate is a barrier substrate.

[12] The laminate for packaging materials according to

[10] or

[11] above, which comprises a first adhesive layer between the first substrate and the second substrate, and a second adhesive layer between the second substrate and the sealant layer.

[13] The laminate for packaging materials according to any one of the above [1] to

[12] , wherein the proportion of the polypropylene-based single material is 80% by mass or more.

[14] A packaging container comprising the laminate for packaging materials according to any one of [1] to

[13] above.

[15] The packaging container according to

[14] above, which is a boilable or retort pouch.

[16] A lid material comprising the laminate for packaging materials according to any one of [1] to

[13] above.

[17] A packaging container comprising a container body having a storage section and the lid material according to

[16] above joined to the container body so as to seal the storage section. [Example]

[0191] The laminate of the present disclosure will be specifically described below based on examples.

[0192] [Example 1] <Preparation of sealant film> The composite consisted of 80% by mass of propylene-ethylene block copolymer, 5% by mass of styrene-ethylene / butylene-styrene block copolymer (SEBS), and fossil fuel-derived linear low-density polyethylene (Prime Polymer Co., Ltd., SP2040, MFR: 3.8 g / 10 min, Tm: 116 °C, density: 918 kg / m 3 A resin composition containing 15% by mass of the above compound was extruded through a T-die to prepare an unstretched film having a thickness of 60 μm (hereinafter also referred to as "sealant film (A)").

[0193] <Preparation of transparent barrier substrate> A hydroxyl group-containing (meth)acrylic resin (number average molecular weight: 25,000, glass transition temperature: 99°C, hydroxyl value: 80 mgKOH / g) was diluted with a mixed solvent of methyl ethyl ketone and ethyl acetate (mixing ratio 1:1) to a solids concentration of 10% by mass to prepare a base resin. An ethyl acetate solution containing tolylene diisocyanate (solids content 75% by mass) was added to the base resin as a curing agent to obtain a solution for forming a surface coating layer. The amount of curing agent used was 10 parts by mass per 100 parts by mass of the base resin.

[0194] A 20 μm-thick biaxially stretched polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was prepared, one side of which was corona-treated. The 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 with a thickness of 0.5 μm, thereby obtaining a resin substrate.

[0195] 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 using a low-temperature plasma chemical vapor deposition apparatus (CVD method) in a roll-to-roll manner while applying tension to the resin substrate. The vapor deposition film formation conditions were as follows:

[0196] (Formation conditions) Hexamethyldisiloxane: oxygen gas: helium = 1:10:10 (unit: slm) Cooling / electrode drum power supply: 22kW Line speed: 100m / min

[0197] 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 added to this solution while cooling to 10°C to obtain Solution A. 14.7g of polyvinyl alcohol with a saponification degree of 99% or more and a degree of polymerization of 2400 as a water-soluble polymer was mixed with 324g of water and 17g of isopropyl alcohol to obtain Solution B.

[0198] A barrier coating agent was obtained by mixing Solution A and Solution B in a mass ratio (Solution A:Solution B) of 6.5:3.5. The barrier coating agent was coated onto a vapor-deposited film formed on a resin substrate by spin coating, and then heated 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.

[0199] <Preparation of laminate> A 20 μm-thick biaxially oriented polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello, Inc.) with one side corona-treated was prepared as the first substrate. A printed layer with 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-40 / H-4, 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.

[0200] The non-barrier coat layer surface of the transparent barrier substrate used as the second substrate (intermediate substrate) was subjected to corona treatment, and a two-component curing polyurethane adhesive (RU-40 / H-4, manufactured by Rock Paint Co., Ltd.) was coated using the gravure roll coating method to a coating thickness of 4 μm (when dry), and a sealant film (A) was dry laminated onto the adhesive layer surface.

[0201] In this way, a laminate with a thickness of approximately 109 μm was obtained. The laminate consisted of a biaxially oriented polypropylene film (20 μm) / a printed layer (1 μm) / a solvent-based adhesive layer (4 μm) / a transparent barrier substrate (approximately 20 μm) / a solvent-based adhesive layer (4 μm) / a sealant film (A) (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0202] [Example 2] The procedure was the same as in Example 1, except that a non-solvent, two-component curing polyurethane adhesive (RN-920 / HN-920, manufactured by Rock Paint Co., Ltd.) was applied as the adhesive layer to a coating thickness of 1.5 μm (when dried) using a roll coating method, resulting in a laminate with a thickness of approximately 104 μm. The laminate consisted of a biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-free adhesive layer (1.5 μm) / transparent barrier substrate (approximately 20 μm) / solvent-free adhesive layer (1.5 μm) / sealant film (A) (60 μm). The mono-material ratio of the laminate was approximately 96% by mass.

[0203] [Example 3] A transparent barrier substrate was used as the first substrate, and the biaxially oriented polypropylene film was positioned as the outermost layer of the laminate. A printed layer was formed on the barrier coat layer. A laminate approximately 85 μm thick was obtained in the same manner as in Example 1, except that a second substrate (intermediate substrate) was not laminated. The laminate consisted of transparent barrier substrate (approximately 20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / sealant film (A) (60 μm). The mono-material ratio of the laminate was approximately 94% by mass.

[0204] [Comparative Example 1] A laminate approximately 109 μm thick was obtained in the same manner as in Example 1, except that a 60 μm thick unstretched polypropylene film (ZK207, manufactured by Toray Advanced Film Co., Ltd.) was used as the sealant layer. "ZK207" is composed of a propylene-ethylene block copolymer and a thermoplastic elastomer (no polyethylene component). The laminate consisted of a biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (approximately 20 μm) / solvent-based adhesive layer (4 μm) / unstretched polypropylene film (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0205] Comparative Example 2 A laminate approximately 109 μm thick was obtained in the same manner as in Example 1, except that a 60 μm thick unstretched polypropylene film (ZK99S, manufactured by Toray Advanced Film Co., Ltd.) was used as the sealant layer. "ZK99S" is composed of a propylene-ethylene block copolymer (thermoplastic elastomer, no polyethylene component). The laminate consisted of a biaxially oriented polypropylene film (20 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / transparent barrier substrate (approximately 20 μm) / solvent-based adhesive layer (4 μm) / unstretched polypropylene film (60 μm). The mono-material ratio of the laminate was approximately 91% by mass.

[0206] Comparative Example 3 A 96-μm-thick laminate was obtained in the same manner as in Example 1, except that a 12-μm-thick silica-deposited PET film (IB-PET-PIR2, manufactured by DNP Corp.) was used as the first substrate, a 15-μm-thick biaxially oriented nylon film (Bonyl-W, manufactured by Kohjin Film & Chemicals Co., Ltd.) was used as the second substrate (intermediate substrate), and a 60-μm-thick unstretched polypropylene film (ZK99S, manufactured by Toray Advanced Film Co., Ltd.) was used as the sealant layer. The laminate consisted of silica-deposited PET film (12 μm) / printed layer (1 μm) / solvent-based adhesive layer (4 μm) / biaxially oriented nylon film (15 μm) / solvent-based adhesive layer (4 μm) / unstretched polypropylene film (60 μm). The mono-material content of the laminate was approximately 62% by mass.

[0207] [Retort test] Two laminates obtained as described above were prepared and stacked with the sealant film (unstretched polypropylene film) facing each other. The other laminate was then folded into a V shape with the sealant film facing outward, and this was sandwiched between the lower part of the opposing laminate and heat-sealed to form a bottom. The two sides adjacent to the bottom were then heat-sealed to form a body. In this way, a standing pouch with a boat-shaped seal at the bottom was produced, measuring 130 mm wide, 170 mm high, and 35 mm deep. The bottom seal width was 5 mm, and the side seal width was 5 mm. 210 g of water was poured into the resulting pouch through the opening, and the opening was heat-sealed to seal the pouch. The sealed pouch was then subjected to a hot water retort treatment at 121°C for 30 minutes.

[0208] [Differential scanning calorimetry (DSC)] The sealant film was separated from the standing pouch after retort processing, and differential scanning calorimetry (DSC) was performed on the separated sealant film. Each melting peak temperature was measured using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name: DSC7000X) in accordance with JIS K7121. The sealant film was held at 20°C for 1 minute, then heated from 20°C to 200°C at a heating rate of 10°C / min, and the melting peak temperature (°C) was measured. The nitrogen gas flow rate was 20 ml / min.

[0209] [Drop test] The standing pouches after retort processing were stored in an environment at 3°C ​​for one week, and then the stored pouches were dropped 10 times horizontally from a height of 120 cm onto the floor (so that the body of the pouch hits the floor) in an environment at room temperature (approximately 23°C), and then dropped another 10 times vertically from a height of 120 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.

[0210] [Table 1]

[0211] [Table 2] [Explanation of symbols]

[0212] 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, 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 laminate for packaging materials comprising a substrate and a sealant layer, the substrate comprises a polypropylene resin layer that has been subjected to a stretching treatment, the sealant layer contains a propylene-ethylene block copolymer, a thermoplastic elastomer, and polyethylene as main components, and has a melting peak temperature observed in the range of 100°C or higher and lower than 120°C; Laminate for packaging materials.

2. 2. The laminate for packaging materials according to claim 1, wherein the sealant layer further has a peak melting temperature observed in the range of 120°C or higher and lower than 135°C and / or a peak melting temperature observed in the range of 160°C or higher.

3. 3. The laminate for packaging materials according to claim 1 or 2, wherein the sealant layer has a larger content of the polyethylene than the thermoplastic elastomer, and a larger content of the propylene-ethylene block copolymer than the polyethylene, on a mass basis.

4. The polyethylene has a density of 925 kg / m ３ The laminate for packaging materials according to any one of claims 1 to 3, which is a linear low-density polyethylene as follows:

5. The laminate for packaging materials according to any one of claims 1 to 4, wherein the substrate is a barrier substrate including the polypropylene resin layer and a vapor-deposited film, and the vapor-deposited film is composed of an inorganic oxide.

6. 6. The laminate for packaging materials according to claim 5, wherein the barrier substrate further comprises a surface coating layer between the polypropylene resin layer and the vapor-deposited film, and the surface coating layer contains a resin material having a polar group.

7. 6. The packaging laminate according to claim 5, wherein the barrier substrate further comprises a surface resin layer between the polypropylene resin layer and the vapor-deposited film, and the surface resin layer contains a resin material having a melting point of 180°C or higher.

8. 8. The laminate for packaging materials according to claim 7, wherein the polypropylene resin layer and the surface resin layer of the barrier substrate constitute a co-extruded stretched resin film.

9. The laminate for packaging materials according to any one of claims 5 to 8, further comprising a barrier coat layer on the vapor-deposited film.

10. The laminate is a first substrate; a second substrate; and the sealant layer; are provided in this order in the thickness direction, the first substrate and the second substrate are each independently the barrier substrate or a polypropylene resin substrate that has been subjected to a stretching treatment; The laminate for packaging materials according to any one of claims 5 to 9.

11. the first substrate is the polypropylene resin substrate, the second substrate is the barrier substrate; The laminate for packaging materials according to claim 10.

12. a first adhesive layer between the first substrate and the second substrate; a second adhesive layer is provided between the second substrate and the sealant layer; The laminate for packaging materials according to claim 10 or 11.

13. The laminate for packaging materials according to any one of claims 1 to 12, wherein the proportion of the polypropylene-based single material is 80% by mass or more.

14. A packaging container comprising the laminate for packaging materials according to any one of claims 1 to 13.

15. 15. The packaging container according to claim 14, which is a boil or retort pouch.

16. A lid material comprising the laminate for packaging materials according to any one of claims 1 to 13.

17. a container body having a storage portion; The lid member according to claim 16, which is joined to the container body so as to seal the storage portion. A packaging container comprising:

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