Laminate and packaging material

Abstract

Provided is a laminate including a base material layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded via the adhesive layer, the base material layer and the sealant layer include a polypropylene resin, the content of the polypropylene resin in terms of the total amount of the laminate is 90 mass% or more, and the tensile elastic modulus of the sealant layer at 23°C as calculated under the conditions indicated below is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction. (Conditions) A tensile test is performed under conditions in which the sample width is 20 mm, the distance between the gauge points is 250 mm, and the tensile speed is 5 mm / min, and the tensile elastic modulus is calculated from the value of the stress when the sample is stretched by 0.05%-0.25%.

Description

Laminates and packaging materials

[0001] The present disclosure relates to laminates and packaging materials.

[0002] In recent years, there has been a growing need for environmentally friendly, sustainable packaging materials, and progress has been made in the development of packaging materials (mono-material packaging materials) that are highly recyclable and consist of laminates of layers containing the same material.

[0003] As an example of such a monomaterial packaging material, Patent Document 1 discloses a polypropylene-based packaging material comprising a biaxially oriented polypropylene film as a substrate, an intermediate layer comprising a biaxially oriented polypropylene film and a vapor-deposited film, and a heat-seal layer comprising an unoriented polypropylene film.

[0004] JP 2022-132355 A

[0005] Meanwhile, there is also a need to reduce the amount of resin film used in packaging materials in order to make them more sustainable. For the packaging material described in Patent Document 1, for example, it is conceivable to produce a laminate having a substantially two-layer structure by removing the biaxially oriented polypropylene film from either the base material or the intermediate layer. However, when a packaging bag formed using such a laminate is subjected to a moist heat treatment such as a retort treatment at a high temperature, the barrier properties of the packaging bag may not be maintained.

[0006] The present disclosure has been made in view of the above circumstances, and aims to provide a laminate that has a more sustainable configuration and can maintain good barrier properties even after high-temperature moist heat treatment. Another aim of the present disclosure is to provide a packaging material obtained using the laminate.

[0007] One aspect of the present disclosure provides a laminate comprising a base layer, a barrier layer, an adhesive layer, and a sealant layer, the barrier layer and the sealant layer being bonded via the adhesive layer, the base layer and the sealant layer containing a polypropylene-based resin, the content of the polypropylene-based resin being 90 mass% or more based on the total weight of the laminate, and the sealant layer having a tensile modulus at 23°C of 800 MPa or more in the MD direction and 650 MPa or more in the TD direction, as calculated under the following conditions: (Conditions) A tensile test is conducted under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample is elongated by 0.05 to 0.25%.

[0008] The laminate has a more sustainable structure and can maintain good barrier properties even after a moist heat treatment at a high temperature.

[0009] In one embodiment, the barrier layer may include an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order from the substrate layer side, thereby maintaining good barrier properties at a higher level.

[0010] In one embodiment, the thickness of the deposited layer may be from 5 to 80 nm.

[0011] In one embodiment, the adhesive layer may have a thickness of 0.5 to 10 μm.

[0012] In one embodiment, the substrate layer may be an oriented polypropylene film and the sealant layer may be an unoriented polypropylene film.

[0013] In one embodiment, the overcoat layer may include a cured product of a composition containing a water-soluble polymer and a metal alkoxide or a hydrolyzate thereof.

[0014] In one embodiment, the sealant layer may include at least a sealant substrate and a heat seal layer in this order from the substrate layer side.

[0015] In one embodiment, the sealant base may comprise a propylene-ethylene block copolymer.

[0016] In one embodiment, the heat seal layer may comprise a propylene-ethylene random copolymer.

[0017] In one embodiment, the sealant base material may contain an elastomer component in an amount of more than 0% by mass and up to 35% by mass based on the total amount of the sealant base material.

[0018] In one embodiment, the tensile modulus of the base layer at 23° C. calculated under the above conditions may be 1.5 to 3.0 GPa in the MD direction and 2.0 to 5.0 GPa in the TD direction.

[0019] In one embodiment, the ratio of the tensile modulus of the substrate layer to the tensile modulus of the sealant layer may be 1.5 to 5.0 in the MD direction and 4.0 to 10 in the TD direction.

[0020] In one embodiment, the laminate may be for use in a moist heat treatment.

[0021] One aspect of the present disclosure provides a laminate comprising a substrate layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded via the adhesive layer; the substrate layer and the sealant layer contain a polypropylene-based resin, and the content of the polypropylene-based resin based on the total amount of the laminate is 90 mass% or more; the tensile modulus of the sealant layer at 23°C, calculated under the following conditions, is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction, and the tensile modulus of the substrate layer at 23°C is 1.5 to 3.0 GPa in the MD direction and 2.0 to 5.0 GPa in the TD direction; the ratio of the tensile modulus of the substrate layer to the tensile modulus of the sealant layer is 1.5 to 5.0 in the MD direction and 4.0 to 10 in the TD direction; the barrier layer comprises, from the substrate layer side, an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order; the substrate layer is a stretched polypropylene film, and the sealant layer is a non-stretched polypropylene film; The present invention provides a laminate in which the sealant layer comprises, from the substrate layer side, a laminate layer, a sealant substrate, and a heat seal layer, the sealant substrate containing a propylene-ethylene block copolymer, the heat seal layer containing a propylene-ethylene random copolymer, and the sealant substrate containing an elastomer component in an amount of more than 0% by mass and not more than 35% by mass based on the total amount of the sealant substrate. (Conditions) A tensile test is conducted under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample is elongated by 0.05 to 0.25%.

[0022] One aspect of the present disclosure provides a packaging material including the laminate, wherein the resin film constituting the packaging material is only a substrate layer and a sealant layer.

[0023] The packaging material has the same characteristics as the laminate, that is, it has a more sustainable structure and can maintain good barrier properties even after moist heat treatment at high temperatures.

[0024] According to the present disclosure, a laminate that has a more sustainable configuration and can maintain good barrier properties even after high-temperature moist heat treatment is provided. Also, according to the present disclosure, a packaging material obtained using the laminate is provided.

[0025] Fig. 1 is a cross-sectional view schematically showing an embodiment of a laminate according to the present disclosure. Fig. 2 is a cross-sectional view schematically showing an embodiment of a package according to the present disclosure.

[0026] Hereinafter, embodiments of the present disclosure will be described. Note that the same components are denoted by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional ratios in the drawings are not limited to those shown in the drawings.

[0027] [Laminate] An embodiment of a laminate according to the present disclosure will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view schematically illustrating one embodiment of a laminate according to the present disclosure.

[0028] As shown in Figure 1, the laminate 100 includes at least a substrate layer 10 having a barrier layer 11, an adhesive layer 20, and a sealant layer 30. The surface of the sealant layer 30 opposite the substrate layer 10 is a sealing surface 30a. The surface of the substrate layer 10 facing the barrier layer 11 and the sealant layer 30 are bonded via the adhesive layer 20. The substrate layer 10 and the sealant layer 30 contain a polypropylene-based resin. The tensile modulus of elasticity of the sealant layer 30 at 23°C is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction.

[0029] The laminate 100 can be produced by bonding, with an adhesive, the base material layer 10 on which the barrier layer 11 is formed and the sealant layer 30. This results in the laminate 100 comprising the base material layer 10, the barrier layer 11, the adhesive layer 20, and the sealant layer 30, with the barrier layer 11 and the sealant layer 30 bonded together via the adhesive layer 20.

[0030] The laminate 100, which has a more sustainable configuration than conventional laminates, does not include an intermediate layer containing a polypropylene-based resin between the base layer 10 and the sealant layer 30. In other words, the laminate 100 can be said to be a polypropylene-based laminate having a substantially two-layer configuration (consisting of two resin films), which does not include any resin films other than the resin film (resin layer) that constitutes the base layer 10 and the resin film that constitutes the sealant layer 30. The laminate 100 may further include a printed layer, if necessary.

[0031] The laminate 100 has a more sustainable structure than conventional laminates, yet can maintain good barrier properties even after a moist heat treatment at high temperatures. Specifically, when a packaging bag formed using the laminate 100 is subjected to a moist heat treatment at high temperatures, the barrier properties of the packaging bag can be maintained better than when a laminate is used that does not include a sealant layer 30 having a tensile modulus of 800 MPa or more in the MD direction and 650 MPa or more in the TD direction. In other words, the laminate 100 can be suitably used as a laminate for moist heat treatment. The inventors speculate that the reason for this is that the sealant layer 30, which has a high tensile modulus, suppresses shrinkage of the base layer 10 during moist heat treatment, thereby suppressing deterioration in the barrier properties of the barrier layer 11.

[0032] Examples of moist heat treatment include retort treatment and boiling treatment, and the laminate 100 of the present disclosure is particularly suitable for retort treatment. Retort treatment is a pressure and heat treatment under conditions of, for example, 0.33 MPa, 121 to 130°C, and 15 to 50 minutes.

[0033] The laminate 100, the substrate layer 10, the barrier layer 11, the adhesive layer 20, the sealant layer 30, and the printing layer will be described in detail below.

[0034] (Laminate) The content of the polypropylene-based resin based on the total amount (whole) of the laminate 100 is 90% by mass or more from the viewpoint of recyclability. From the same viewpoint, the content of the polypropylene-based resin in the laminate 100 is more preferably 92% by mass or more, and more preferably 95% by mass or more. The upper limit of the content is not particularly limited, but may be, for example, 99% by mass or less, or 98% by mass or less, as long as the amount of adhesive component and the like is subtracted from the total amount of the laminate 100.

[0035] The laminate 100 has a barrier property, and therefore can also be called a gas barrier laminate. Here, the barrier property means an oxygen barrier property and a water vapor barrier property, and mainly means an oxygen barrier property.

[0036] (Base Layer) The base layer 10 is a layer on which the barrier layer 11 is formed and which supports the sealant layer 30, and contains a polypropylene-based resin. The base layer 10 can also be called a gas barrier film.

[0037] The polypropylene-based resin contained in the base layer 10 is composed of a resin containing propylene as a structural unit. Examples of polypropylene-based resins include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with an α-olefin such as ethylene or butene, and ethylene-propylene rubber. These can be used alone or in combination of two or more. Examples of propylene copolymers include propylene-ethylene random copolymers, propylene-ethylene block copolymers, and propylene-ethylene terpolymers. The polypropylene-based resin may also be a block polypropylene, which is a mixture of homopolypropylene and ethylene-propylene rubber.

[0038] The substrate layer 10 may be a non-stretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. The substrate layer 10 may also be a laminate containing a stretched film and a non-stretched film. The substrate layer 10 preferably has a stretched film, and more preferably is a stretched film (stretched polypropylene film). In this case, the mechanical strength and dimensional stability of the laminate 100 can be improved.

[0039] When the base layer 10 is an oriented polypropylene film (OPP), the OPP can be one that exhibits a shrinkage rate of 1.0 to 5.0% in the MD direction and 0.5 to 3.0% in the TD direction before and after heat treatment when retorted at 128°C for 15 minutes (shower type). MD heat shrinkage rate (%) = (MD length before heating - MD length after heating) / MD length before heating x 100 TD heat shrinkage rate (%) = (TD length before heating - TD length after heating) / TD length before heating x 100

[0040] The tensile modulus of the base material layer 10 is preferably 1.5 to 3.0 GPa in the MD direction and 2.0 to 5.5 GPa in the TD direction. When the tensile modulus of the base material layer 10 is within this range, the heat resistance is superior and the packaging body is more likely to maintain its rigidity even after retort treatment. From the above viewpoints, the tensile modulus of the base material layer 10 in the MD direction is preferably 1.5 to 3.0 GPa, more preferably 1.8 to 2.7 GPa, and even more preferably 2.0 to 2.5 GPa. The tensile modulus of the base material layer 10 in the TD direction is preferably 2.0 to 5.5 GPa, more preferably 2.5 to 4.8 GPa, and even more preferably 3.0 to 4.6 GPa. The tensile modulus is measured under the following conditions in an environment of 23°C. (Conditions) A tensile test is carried out under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample is elongated by 0.05 to 0.25%.

[0041] The surface of the base material layer 10 facing the sealant layer 30 may be subjected to various pretreatments such as corona treatment, plasma treatment, ozone treatment, and flame treatment, or may be provided with a coating layer such as an easy-adhesion layer. The base material layer 10 may contain a resin other than a polypropylene-based resin. Examples of such resins include polyolefin-based resins such as polyethylene-based resins. The base material layer 10 may optionally contain at least one additive selected from a filler, an antistatic agent, a plasticizer, a lubricant, an antioxidant, and the like.

[0042] The thickness of the base layer 10 may be appropriately set depending on the intended use of the laminate 100, and may be 15 to 30 μm, or 20 to 25 μm.

[0043] (Barrier Layer) Providing the barrier layer 11 in the laminate 100 makes it possible to effectively suppress deterioration of the contents due to gases such as oxygen when a packaging bag is produced using the laminate 100 and contents are placed in the packaging bag to produce a package. The barrier layer 11 is provided on the surface of the base layer 10 on the sealant layer 30 side. This allows the barrier layer 11 to be protected by the sealant layer 30, which has a high tensile modulus, and therefore prevents damage to the barrier layer 11 during the laminate processing step, bag making step, filling step, or transportation of the packaging bag.

[0044] (Vapor-deposited layer) The barrier layer 11 may include a vapor-deposited layer made of an inorganic compound. Examples of the inorganic compound constituting the vapor-deposited layer include SiO. Ｘ and AlO Ｘ The barrier layer 11 may be made of, for example, SiO Ｘ When using a vapor deposition layer, the barrier layer 11 becomes transparent, so that the contents can be seen from the outside of the packaging bag. Ｘ and AlO Ｘ The thickness of the deposited layer may be, for example, 5 to 80 nm, or may be 20 to 40 nm.

[0045] (Overcoat Layer) The barrier layer 11 has barrier properties even when it is composed of only a vapor-deposited layer, but it is preferably composed of a composite layer formed by further laminating an overcoat layer on a vapor-deposited layer.

[0046] When the barrier layer 11 is constructed as a composite layer, a reaction layer between the vapor deposition layer and the overcoat layer occurs at the interface between the two layers, or the overcoat layer fills or reinforces defects or micropores such as pinholes, cracks, and grain boundaries that occur in the vapor deposition layer, thereby forming a dense structure. Therefore, the barrier layer 11 constructed as a composite layer combining the overcoat layer and the vapor deposition layer achieves higher barrier properties, moisture resistance, and water resistance, and has flexibility that can withstand deformation due to external forces, thereby imparting suitability to the laminate 100 as a packaging material.

[0047] The overcoat layer can be formed by a coating method in which an overcoat agent (coating agent) is applied to the vapor deposition layer and then dried by heating. In other words, the overcoat layer can be said to contain a cured product of the overcoat agent.

[0048] The overcoating agent may be based on an aqueous solution or a water / alcohol mixed aqueous solution containing a water-soluble polymer and at least one of metal alkoxides, their hydrolysates, and tin chloride. The overcoating agent is preferably a composition containing a water-soluble polymer and a metal alkoxide or its hydrolysates. The overcoating agent may further contain a silane coupling agent. In this case, the adhesion between the overcoat layer and the vapor deposition layer can be improved.

[0049] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. In particular, when polyvinyl alcohol (PVA) is contained in the overcoat agent, the gas barrier property tends to be more excellent.

[0050] Examples of metal alkoxides include compounds represented by the following general formula: M(OR １ ) ｍ (R ２ ) ｎ－ｍ In the above formula, R １ is a monovalent organic group having 1 to 8 carbon atoms, and is an alkyl group such as a methyl group or an ethyl group (OR １ R may be a hydrolyzable group. ２ is a monovalent organic group having 1 to 8 carbon atoms, and may be an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, or Zr. m is an integer from 1 to n. １ and R ２ If there are multiple １ Comrades or R ２ They may be the same or different.

[0051] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC ２ H ５ ) ４ ], triisopropoxyaluminum [Al(O-2'-C ３ H ７ ) ３Tetraethoxysilane (TEOS) and triisopropoxyaluminum tend to be relatively stable in aqueous solvents after hydrolysis.

[0052] Examples of the silane coupling agent include compounds represented by the following general formula: Si(OR ２１ ) ｐ (R ２２ ) ３－ｐ R ２３ In the above formula, R ２１ represents an alkyl group such as a methyl group or an ethyl group, and R ２２ represents a monovalent organic group such as an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkyl group substituted with an acryloxy group, or an alkyl group substituted with a methacryloxy group, and R ２３ represents a monovalent organic functional group, and p represents an integer of 1 to 3. ２１ or R ２２ If there are multiple ２１ Comrades or R ２２ R may be the same or different. ２３ Examples of the monovalent organic functional group represented by the formula (I) include a monovalent organic functional group containing a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or an isocyanate group. Polymers such as dimers and trimers of these compounds may also be used as silane coupling agents.

[0053] Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and 1,3,5-tris(3-methoxysilylpropyl)isocyanurate.

[0054] When PVA is contained as the water-soluble polymer, the amount of PVA in the composition (overcoat agent) may be 20% by mass or more, 25% by mass or more, or 30% by mass or more based on the total solid content of the composition, from the viewpoint of maintaining the flexibility of the overcoat layer and facilitating the formation of the overcoat layer. When PVA is contained as the water-soluble polymer, the amount of PVA in the composition is preferably 65% ​​by mass or less, 60% by mass or less, or 55% by mass or less based on the total solid content of the composition, from the viewpoint of facilitating maintaining low oxygen permeability even after heat sterilization treatment.

[0055] When TEOS (tetraethoxysilane) is contained as the metal alkoxide, the amount of TEOS in the composition is preferably 30% by mass or more, 33% by mass or more, or 35% by mass or more based on the total solid content of the composition, from the viewpoint of easily maintaining low oxygen permeability even after heat sterilization treatment. When TEOS is contained as the metal alkoxide, the amount of TEOS in the composition is preferably 85% by mass or less, 80% by mass or less, or 75% by mass or less based on the total solid content of the composition, from the viewpoint of maintaining the flexibility of the overcoat layer and making it easy to form the overcoat layer. In this specification, the amount of TEOS is defined as SiO ２ This means the value converted into

[0056] When isocyanurate silane is contained as a silane coupling agent, the amount of isocyanurate silane in the composition is preferably 1% by mass or more, 3% by mass or more, or 5% by mass or more based on the total solid content of the composition, from the viewpoints of easily realizing hot water resistance and easily realizing excellent adhesion even after heat sterilization treatment. When isocyanurate silane is contained as a silane coupling agent, the amount of isocyanurate silane in the composition is preferably 20% by mass or less, 15% by mass or less, or 10% by mass or less based on the total solid content of the composition, from the viewpoints of easily maintaining low oxygen permeability even after heat sterilization treatment without making the amounts of other components in the composition too small.

[0057] The thickness of the overcoat layer may be 0.05 to 0.5 μm. If the thickness of the overcoat layer is 0.05 μm or more, high gas barrier properties are likely to be exhibited. Furthermore, if the thickness of the overcoat layer is 0.5 μm or less, deterioration of gas barrier properties due to cracking of the layer during coating can be suppressed, and since swelling of the layer under high temperature and high humidity conditions is small, even if cracks occur in the vapor deposition layer, their diffusion can be prevented, resulting in suppression of deterioration of barrier performance. From this perspective, the thickness of the overcoat layer may be, for example, 0.07 to 0.45 μm.

[0058] (Anchor Coat Layer) The barrier layer 11 may be provided directly on the substrate layer 10, or may be provided via an anchor coat layer. The anchor coat layer is a layer for further improving the adhesion between the substrate layer 10 and the vapor deposition layer, and is provided between the substrate layer 10 and the vapor deposition layer.

[0059] The anchor coat layer can be formed using an anchor coat agent prepared by dissolving a curable compound such as a polyester polyurethane resin, a polyether polyurethane resin, or an acrylic urethane resin in a solvent. The anchor coat layer can be formed by coating the anchor coat agent onto the substrate layer 10 using a coating method that applies a printing technique such as gravure coating or a commonly known coating method, and then drying the coating.

[0060] The thickness of the anchor coat layer is preferably 30 nm or more. In this case, the surface smoothness of the anchor coat layer can be further improved compared to when the thickness of the anchor coat layer is less than 30 nm. This makes it possible to make the thickness of the vapor deposition layer more uniform and further improve the oxygen barrier property. Furthermore, by making the anchor coat layer thicker, it is easier to suppress a decrease in the water vapor barrier property when an external force such as stretching is applied. From this perspective, the thickness of the anchor coat layer is more preferably 40 nm or more, and even more preferably 50 nm or more.

[0061] The thickness of the anchor coat layer is preferably 2000 nm (2 μm) or less. In this case, the flexibility of the layer is further improved compared to when the thickness of the anchor coat layer exceeds 2000 nm, and the gas barrier properties of the laminate after the abuse test can be further improved. From this viewpoint, the thickness of the anchor coat layer is more preferably 1500 nm (1.5 μm) or less.

[0062] In view of the above, the thickness of the anchor coat layer is preferably 30 to 2000 nm, more preferably 40 to 2000 nm, and even more preferably 50 to 1500 nm.

[0063] In this way, the barrier layer 11 may include an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order from the side of the substrate layer 10. The thickness of the barrier layer 11 varies depending on the layer configuration, but may be, for example, 5 to 2500 nm, 50 to 1000 nm, or 100 to 500 nm.

[0064] (Adhesive Layer) The adhesive layer 20 is a layer containing at least one type of adhesive and is provided between the base material layer 10 and the sealant layer 30 to bond them together. For example, any adhesive, such as a one-component curing or two-component curing urethane adhesive, can be used to form the adhesive layer. In addition, both solvent-based and solventless adhesives can be used to form the adhesive layer. From an environmental perspective, it is preferable that the adhesive be free of GPTMS (3-glycidyloxypropyltrimethoxysilane).

[0065] Examples of solvent-based adhesives include urethane-based adhesives, epoxy-based adhesives, and silicone-based adhesives, but from the viewpoint of impact resistance, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are particularly preferred. The solvent used in the solvent-based adhesive is not particularly limited, but examples thereof include ethyl acetate, methanol, isopropyl alcohol, methyl ethyl ketone, and ethanol.

[0066] The two-component curing urethane adhesive contains a polyol component as a base component and a polyisocyanate component as a curing agent.

[0067] The polyol component may be one or a mixture of two or more selected from the group consisting of polyester polyols, polyether polyols, polyether ester polyols, and polyurethane polyols.

[0068] The polyester polyol may be, for example, an ester reaction product of a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a glycol-based solvent. The polycarboxylic acid may be, for example, succinic acid, glutaric acid, isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, or dimer acid. The glycol-based solvent may be, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, neopentyl glycol, or 1,6-hexanediol.

[0069] The polyether polyol may be, for example, a polymer of an oxirane compound and a low-molecular-weight polyol. The oxirane compound may be, for example, ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran. The low-molecular-weight polyol may be, for example, water, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin.

[0070] The polyetherester polyol may be obtained by reacting, for example, a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a polyether polyol.

[0071] The polyurethane polyol may be, for example, the reaction product of a polyester polyol, a polyether polyol, a polyetherester polyol, and a polyisocyanate monomer.

[0072] The polyisocyanate component may be an aliphatic polyisocyanate, an aromatic polyisocyanate, or a mixture thereof.

[0073] The aliphatic polyisocyanate may be, for example, a polyisocyanate monomer, a polyisocyanate derivative, or a polyisocyanate-terminated prepolymer. The polyisocyanate monomer may be, for example, tetramethylene diisocyanate, isopropylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, or trimethylhexamethylene diisocyanate. The polyisocyanate derivative may be, for example, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, lysine diisocyanate, or isophorone diisocyanate.

[0074] The aromatic polyisocyanate may be, for example, a polyisocyanate monomer, a polyisocyanate derivative, or a polyisocyanate-terminated prepolymer. The polyisocyanate monomer may be, for example, tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, or tetramethylxylylene diisocyanate. The polyisocyanate derivative may be, for example, an isocyanurate derived from the polyisocyanate monomer. The polyisocyanate-terminated prepolymer may be a bifunctional polyisocyanate containing terminal isocyanate groups obtained by reacting a polyisocyanate monomer with a bifunctional polyol compound such as polypropylene glycol. The polyisocyanate-terminated prepolymer may also be a multifunctional polyisocyanate containing terminal isocyanate groups obtained by reacting a polyisocyanate monomer with a trifunctional or higher polyol compound such as trimethylolpropane.

[0075] The adhesive layer 20 may be formed using a solvent-free adhesive. Examples of solvent-free adhesives include urethane-based adhesives, epoxy-based adhesives, and silicone-based adhesives. From the viewpoint of impact resistance, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are particularly preferred.

[0076] The thickness of the adhesive layer 20 may be 0.5 to 10 μm, or may be 2 to 3 μm. When the thickness of the adhesive layer 20 is 0.5 μm or more, the adhesiveness of the adhesive layer 20 can be improved. When the thickness of the adhesive layer 20 is 10 μm or less, the processability of the laminate can be improved.

[0077] The weight per unit area of ​​the adhesive layer 20 after curing is 0.5 to 3.5 g / m ２ is preferred, and 1.0 to 3.0 g / m ２ It is more preferable that the weight per unit area of ​​the adhesive layer 20 after curing is 0.5 g / m ２ If the weight per unit area of ​​the adhesive layer after curing is 3.5 g / m or more, the effect of suppressing delamination between layers can be enhanced. ２ If the thickness is equal to or less than this, it is possible to prevent the occurrence of winding misalignment during processing of the laminate, and it is possible to improve the appearance quality of the laminate, and in addition, appropriate lamination strength is obtained.

[0078] The adhesive layer 20 can be formed by various known methods such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fountain coating, and transfer roll coating.

[0079] (Sealant Layer) The sealant layer 30 is a layer that imparts heat-sealing properties to the laminate 100 and contains a polypropylene-based resin. The polypropylene-based resin contains a resin containing propylene as a constituent unit. Examples of polypropylene-based resins include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with an α-olefin such as ethylene or butene, and ethylene-propylene rubber. These can be used alone or in combination of two or more. Examples of propylene copolymers include propylene-ethylene random copolymers, propylene-ethylene block copolymers, and propylene-ethylene terpolymers. The polypropylene-based resin may also be a block polypropylene, which is a mixture of homopolypropylene and ethylene-propylene rubber.

[0080] The sealant layer 30 may be a non-stretched film or a stretched film, but from the viewpoint of lowering the heat sealing temperature and improving the sealability by heat sealing, a non-stretched film (non-stretched polypropylene film) is preferred.

[0081] The sealant layer 30 may be formed of a laminate of multiple layers from the viewpoint of achieving a desired tensile modulus and from the viewpoint of achieving both sealant suitability and rigidity. For example, the sealant layer 30 may have, in order from the substrate layer 10 side, a two-layer structure of a sealant substrate / heat seal layer, or a three-layer structure of a laminate layer / sealant substrate (core layer) / heat seal layer.

[0082] The sealant substrate may contain a block copolymer such as a propylene-ethylene block copolymer from the viewpoint of impact strength, and the laminate layer and the heat seal layer may contain a random copolymer such as a propylene-ethylene random copolymer from the viewpoint of achieving both sealability and impact strength.

[0083] For example, the tensile modulus of each layer can be adjusted by adding a homopolymer or ethylene propylene rubber (elastomer) to each layer. Adding a homopolymer to a random copolymer tends to increase the tensile modulus. Adding ethylene propylene rubber to a block copolymer tends to decrease the tensile modulus. Based on this knowledge, a person skilled in the art can adjust the tensile modulus of the sealant layer 30.

[0084] From the viewpoints of further improving bag drop resistance and adjusting the tensile modulus of elasticity, the amount of the elastomer component is preferably more than 0% by mass and not more than 35% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the layer containing the elastomer. From the above viewpoints, the sealant base material preferably contains more than 0% by mass and not more than 35% by mass of the elastomer component, based on the total amount of the sealant base material.

[0085] The thickness of the sealant layer 30 may be, for example, 50 to 80 μm, or 60 to 70 μm. When the thickness of the sealant layer 30 is 50 μm or more, the protective function of the vapor-deposited layer is more easily exhibited than when the thickness is less than 50 μm, and it is easier to obtain a laminate that can maintain good barrier properties even after moist heat treatment at high temperatures. On the other hand, when the thickness of the sealant layer 30 is 80 μm or less, it is easier to achieve resource conservation and to obtain a more sustainable laminate 100 than when the thickness is more than 80 μm.

[0086] The tensile modulus of the sealant layer 30 at 23°C, calculated under the following conditions, is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction. (Conditions) A tensile test is conducted under the conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%. For the test, for example, a bench-top precision universal testing machine (product name "Autograph AGS-X", manufactured by Shimadzu Corporation) can be used.

[0087] When the MD tensile modulus of the sealant layer 30 is 800 MPa or more, not only can good barrier properties be maintained even after moist heat treatment compared to when the modulus is less than 800 MPa, but the stiffness of the laminate is also increased, resulting in excellent filling suitability (the open state is more easily maintained during filling processing). From this perspective, the tensile modulus is preferably 850 MPa or more, more preferably 900 MPa or more, and even more preferably 1000 MPa or more. There is no particular upper limit to the tensile modulus, but from the viewpoint of bag drop resistance, it is preferably 1300 MPa.

[0088] When the sealant layer 30 has a TD tensile modulus of 650 MPa or more, not only can it maintain good barrier properties even after moist heat treatment, but also the tensile strength of the laminate can be increased, resulting in excellent filling suitability, compared to when the modulus is less than 650 MPa. From this perspective, the tensile modulus is preferably 700 MPa or more, more preferably 800 MPa or more, and even more preferably 900 MPa or more. There is no particular upper limit to the tensile modulus, but from the viewpoint of bag drop resistance, it is preferably 1000 MPa.

[0089] To maintain good barrier properties even after high-temperature moist heat treatment and achieve excellent openability, the ratio of the tensile modulus of the base layer to the tensile modulus of the sealant layer is preferably 1.5 or more in the MD direction and 4.0 or more in the TD direction. The packaging material can be provided with a trigger portion for opening (such as a notch or cut). When force is applied to the trigger portion for opening, stress concentrates in the base layer, which has a high elastic modulus, making it more likely for a crack to occur before the sealant layer. On the other hand, a sealant layer, which has a low elastic modulus, absorbs and disperses the stress applied to the tip of the crack, suppressing crack progression and making the direction of progression unstable. By appropriately differentiating the elastic moduli of the base layer and the sealant layer, a crack can be efficiently generated in the base layer from the trigger portion upon opening, and the crack can propagate smoothly and in the intended direction without being hindered by the sealant layer, thereby achieving good openability. Openability can be evaluated by the "slipping rate" when the packaging material is torn, as shown in the examples, for example.

[0090] On the other hand, from the viewpoint of processing stability, the ratio of the tensile modulus of the substrate layer to the tensile modulus of the sealant layer is preferably 5.0 or less in the MD direction and 10 or less in the TD direction.

[0091] From the above viewpoints, the ratio of the tensile modulus of the base layer to the tensile modulus of the sealant layer in the MD direction is preferably 1.5 to 5.0, more preferably 2.0 to 3.4, and in the TD direction is preferably 4.0 to 10, more preferably 5.0 to 7.5.

[0092] (Printed Layer) As already described, the laminate 100 may include a printed layer. The printed layer can be provided between the barrier layer 11 of the base material layer 10 and the adhesive layer 20. The printed layer is provided at a position visible from the outside of the laminate 100 for the purpose of displaying information about the contents, identifying the contents, improving concealment, or improving the design of the packaging bag.

[0093] The printing ink is not particularly limited and is appropriately selected from known printing inks taking into consideration the printability on other layers in the laminate 100, design such as color tone, adhesion, safety as a food container, etc. For example, a urethane-based resin can be used as the printing ink.

[0094] The printing method is not particularly limited and may be appropriately selected from known printing methods. Examples of printing methods that can be used include gravure printing, offset printing, gravure offset printing, flexographic printing, and inkjet printing. Among these, gravure printing is preferably used from the viewpoints of productivity and high definition of the image.

[0095] [Packaging Material] The packaging material includes the laminate 100 described above. The only resin films that constitute the packaging material are the base material layer and the sealant layer. The packaging material obtained using the laminate 100, which has a more sustainable configuration than conventional ones, is also a sustainable packaging material (packaging film) that does not include any resin films other than the resin film that constitutes the base material layer 10 and the resin film that constitutes the sealant layer 30. Furthermore, the packaging material also has the property of the laminate 100, that is, it can maintain good barrier properties even after moist heat treatment at high temperatures.

[0096] In addition to the laminate 100, the packaging material may include layers such as a concealing layer for making the contents less visible from the outside, a coloring layer for coloring the packaging material, a heat-resistant coating layer for increasing the heat resistance of the packaging material, an easily peelable layer for facilitating peeling between specific layers of the packaging material, an adsorption layer for adsorbing specific substances in the contents, a release layer for releasing specific substances into the contents, and an uneven layer for enhancing the design of the outermost surface of the packaging material.

[0097] [Package] Fig. 2 is a cross-sectional view schematically illustrating one embodiment of a package according to the present disclosure. As shown in Fig. 2, the package 500 includes a packaging bag 400 and a content C contained within the packaging bag 400. The packaging bag 400 is formed using the laminate 100 as a packaging material, and the sealing surface 30a forms the inner surface of the packaging bag 400. For simplicity, the barrier layer 11 is not shown. Specifically, the packaging bag 400 is formed by overlapping two laminates 100 with their sealing surfaces 30a facing each other and heat-sealing the peripheral edges of the sealing surfaces 30a. Thus, the packaging bag 400 includes a main body portion 401 containing the content C and a sealing portion 402 surrounding the main body portion 401.

[0098] (Contents) The contents C are not particularly limited, but examples of the contents C include food and medicine.

[0099] (Packaging Bag) The packaging bag 400 obtained from the laminate 100 has a more sustainable structure and can maintain good barrier properties even after high-temperature moist heat treatment. The two laminates 100 constituting the packaging bag 400 may be made of different materials and may have different thicknesses, shapes, etc. The packaging bag 400 is not particularly limited to the four-sided pouch shown in FIG. 2 and can be appropriately selected depending on the application of the packaging bag. The packaging bag 400 may be, for example, a three-sided pouch, a pillow bag, a standing pouch, a gusset bag, a bag with a spout, etc.

[0100] The packaging bag 400 may be configured with three or more laminates 100. In this case, the plurality of laminates 100 constituting the packaging bag 400 may be configured with different materials and may have different thicknesses, shapes, etc.

[0101] The packaging bag 400 may be subjected to a high-temperature moist heat treatment such as a retort treatment or a boiling treatment.

[0102] Examples of the present disclosure will be specifically described below, but the present disclosure is not limited to the following examples.

[0103] Example 1 A 20 μm-thick biaxially oriented polypropylene film (OPP film, manufactured by Toyobo Co., Ltd., product name: P2171) was prepared as the base layer. This film was retorted at 128°C for 15 minutes (shower type), and the shrinkage before and after the heat treatment was 2.5% in the MD direction and 0.7% in the TD direction. The tensile modulus of this film at 23°C was calculated under the following conditions: 2.9 GPa in the MD direction and 5.1 GPa in the TD direction. Conditions: A tensile test was performed using a benchtop precision universal testing machine (product name "Autograph AGS-X", manufactured by Shimadzu Corporation) under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min. The tensile modulus was calculated from the stress value when the sample was elongated by 0.05 to 0.25%.

[0104] The anchor coating agent described below was applied to one surface of this substrate layer by gravure coating and then dried at 50°C. This formed an anchor coating layer with a thickness of 0.2 μm. (Anchor Coating Agent) Acrylic polyol and tolylene diisocyanate were mixed so that the number of NCO groups in tolylene diisocyanate was equal to the number of OH groups in the acrylic polyol, and then diluted with ethyl acetate so that the total solids content (total amount of acrylic polyol and tolylene diisocyanate) was 5% by mass. To the diluted mixture, 5 parts by mass of β-(3,4-epoxycyclohexyl)trimethoxysilane was added per 100 parts by mass of the total amount of acrylic polyol and tolylene diisocyanate, and the resulting mixture was mixed to prepare an anchor coating agent.

[0105] A 30 nm thick silicon oxide (SiO Ｘ A vapor deposition layer consisting of SiO 2 was formed.

[0106] The following overcoat agent was applied onto the vapor deposition layer using a bar coater and then dried at 60°C for 1 minute. This formed an overcoat layer with a thickness of 300 nm. (Overcoat Agent) The following solutions A, B, and C were mixed together, with solution A being polyvinyl alcohol (PVA) and solution B being SiO ２An overcoat agent was prepared by mixing the above with a silane coupling agent (SC agent) in solution C at a mass ratio of 25:70:5. Solution A: An aqueous solution prepared so that PVA (manufactured by Kuraray Co., Ltd., product name: Kuraray Poval 60-98) was 5 mass%. Solution B: Tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE04), methanol (manufactured by Kanto Chemical Co., Ltd.), and 0.1N hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) were mixed at a mass ratio of 17:10:73 to obtain a solution containing 5 mass% solids (SiO ２ Solution C: 1,3,5-tris(3-methoxysilylpropyl)isocyanurate was dissolved in a solution of water and IPA (isopropyl alcohol) at a mass ratio of 1:1 to a solid content of 5 mass % (R ２ Si(OH) ３ Hydrolysis solution adjusted to give a concentration of 1000 ppm (equivalent to 1000 ppm).

[0107] By the above procedure, a gas barrier film having a barrier layer provided on a substrate layer was obtained.

[0108] The sealant layer used had a three-layer structure of laminate layer / core layer (sealant substrate) / heat seal layer. Specifically, the sealant layer was prepared as follows. For the laminate layer, a resin mixture was prepared by mixing, in pellet form, 70% by mass of a propylene homopolymer (referred to as h-PP in Table 1) having a melting point of 162°C and a melting rate of 3.0 g / 10 min, and 30% by mass of a propylene-ethylene random copolymer (referred to as r-PP in Table 1) having a melting point of 144°C. For the core layer, a propylene-ethylene block copolymer (referred to as b-PP in Table 1) with a melting point of 162°C and a melting rate of 2.0 g / 10 min was added with an elastomer component, a block copolymer of polypropylene and ethylene-α-olefin copolymer rubber (the polypropylene component is random polypropylene) with a melting point of 145°C and a melting rate of 0.6 g / 10 min. The amount of the elastomer component was 10% by mass based on the total weight of the core layer. For the heat-seal layer, the same resin mixture as for the laminate layer was prepared. The respective raw materials were fed into an extruder controlled at 250°C, kneaded in the molten state, and extruded and laminated using a T-die extruder equipped with a feed block to produce the unstretched polypropylene film of Example 1. The laminate layer had a thickness of 10 μm, the core layer had a thickness of 40 μm, and the heat-seal layer had a thickness of 10 μm.

[0109] Next, a polyurethane adhesive, which utilizes an addition reaction between polyisocyanate and polyol, was applied to the barrier layer side of the gas barrier film. The gas barrier film was then bonded to a 60 μm-thick unstretched polypropylene film serving as a sealant layer via an adhesive layer (3.0 μm thick) formed from the adhesive. A laminate (substrate layer / barrier layer / adhesive layer / sealant layer) was thus produced.

[0110] The polyisocyanate in the polyurethane adhesive mainly contained isophorone diisocyanate, and the mass ratio of the base agent (polyol) to the curing agent (polyisocyanate) was 7.4: 1. The curing conditions after application of the adhesive were 40°C for 120 hours.

[0111] Other Examples and Comparative Examples Laminates were produced in the same manner as in Example 1, except that the layer structure of the sealant layer was changed as shown in Table 1. The h-PP, r-PP, b-PP, and elastomer in Table 1 are as described in Example 1. In the laminates of each example, the content of the polypropylene resin based on the total amount of the laminate was 90 mass % or more.

[0112] (Tensile Modulus of Sealant Layer) The tensile modulus of the sealant layer at 23°C was calculated under the following conditions. Conditions: A tensile test was performed using a bench-top precision universal testing machine (product name "Autograph AGS-X", manufactured by Shimadzu Corporation) under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus was calculated from the stress value when the sample was elongated by 0.05 to 0.25%. The results are shown in Table 1.

[0113] (Oxygen Transmission Rate Measurement) Two films measuring 95 mm (MD) x 140 mm (TD) were prepared from the laminate obtained in each example. The sealing surfaces of these films were placed face to face, and three sides were heat-sealed to produce a packaging bag with an opening. 70 g of water was filled into the packaging bag through the opening, and the bag was heat-sealed to close the opening, thereby producing a package. The produced package was subjected to retort treatment at 128°C for 15 minutes (shower type). The oxygen transmission rate (OTR, unit: cc / m) of the package (laminate) after retort treatment was measured. ２ The oxygen permeability (per 1000 kJ / day atm) was measured using an oxygen permeability measuring device (product name "OX-TRAN2 / 20", manufactured by MOCON Corporation). The measurement was carried out in accordance with JIS K-7126-2 under the measurement conditions of a temperature of 30°C and a relative humidity of 70%. The results are shown in Table 1.

[0114] (Evaluation of filling suitability) Packaging bags with openings were prepared in the same manner as in the oxygen permeability measurement. The packaging bags were fed into a bag feeding and packaging machine and the filling suitability (openability) was evaluated according to the following criteria. The results are shown in Table 1. Good product rate at opening: 98% or more: ◯ Good product rate at opening: 95% or more but less than 98%: △ Good product rate at opening: less than 95%: ×

[0115] (Evaluation of Drop Resistance) In the same manner as in the oxygen permeability measurement, 100 water-filled packages were prepared for each example. The prepared packages were held horizontally on the floor and dropped repeatedly 100 times from a height of 1 m above the floor. Based on the percentage of packaging bags that did not break (survival rate), the drop resistance was evaluated according to the following criteria. The results are shown in Table 1. Survival rate 100%: ◯ Survival rate 95% or more but less than 100%: △ Survival rate less than 95%: ×

[0116] (Evaluation of Openability) A packaging bag with an opening was prepared in the same manner as in the oxygen permeability measurement. A 5 mm long slit was made in the MD direction on one side of the packaging bag in the TD direction, and the packaging bag was manually torn in the MD direction starting from this slit. The state of the torn packaging bag was observed, and the openability was evaluated according to the following criteria. The results are shown in Table 1. The tear crack propagated in the MD direction and reached the side opposite the TD direction (slippage rate less than 20%): ◯ The tear crack propagated in the MD direction and reached the side opposite the TD direction (slippage rate 20% or more): △ The tear crack propagated in a direction different from the MD direction halfway through and did not reach the side opposite the TD direction: × The slippage rate is a value calculated based on the amount of slippage as follows: Misalignment amount [mm] = | (position reached to one side of the front side of the packaging bag opposite in the TD direction) - (position reached to one side of the back side of the packaging bag opposite in the TD direction) | Misalignment rate [%] = (misalignment amount) / (length of packaging bag in the TD direction) × 100

[0117]

[0118] The present disclosure is outlined as follows. [1] A laminate comprising a substrate layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded via the adhesive layer, the substrate layer and the sealant layer contain a polypropylene-based resin, and the content of the polypropylene-based resin based on the total weight of the laminate is 90 mass% or more, and the sealant layer has a tensile modulus at 23°C of 800 MPa or more in the machine direction and 650 MPa or more in the transverse direction, as calculated under the following conditions: (Conditions) A tensile test is conducted under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%. [2] The laminate according to [1], wherein the barrier layer comprises, from the substrate layer side, an anchor coat layer, a vapor deposition layer, and an overcoat layer, in this order. [3] The laminate according to [2], wherein the vapor deposition layer has a thickness of 5 to 80 nm. [4] The laminate according to any one of [1] to [3], wherein the adhesive layer has a thickness of 0.5 to 10 μm. [5] The laminate according to any one of [1] to [4], wherein the substrate layer is a stretched polypropylene film and the sealant layer is an unstretched polypropylene film. [6] The laminate according to any one of [1] to [5], wherein the overcoat layer comprises a cured product of a composition containing a water-soluble polymer and a metal alkoxide or a hydrolyzate thereof. [7] The laminate according to any one of [1] to [6], wherein the sealant layer comprises at least a sealant substrate and a heat seal layer, in this order, from the substrate layer side. [8] The laminate according to [7], wherein the sealant substrate comprises a propylene-ethylene block copolymer. [9] The laminate according to [7] or [8], wherein the heat seal layer comprises a propylene-ethylene random copolymer.

[10] The laminate according to any one of [7] to [9], wherein the sealant substrate comprises an elastomer component in an amount of more than 0% by mass and not more than 35% by mass, based on the total amount of the sealant substrate.

[11] The laminate according to any one of [1] to

[10] , wherein the tensile modulus of the base material layer at 23°C calculated under the above conditions is 1.5 to 3.0 GPa in the MD direction and 2.0 to 5.5 GPa in the TD direction.

[12] The laminate according to

[11] , wherein the ratio of the tensile modulus of the base material layer to the tensile modulus of the sealant layer is 1.5 to 5.0 in the MD direction and 4.0 to 10 in the TD direction.

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

[12] , which is for use in moist heat treatment.

[14] A laminate comprising a substrate layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded via the adhesive layer, wherein the substrate layer and the sealant layer contain a polypropylene-based resin, and the content of the polypropylene-based resin based on the total amount of the laminate is 90 mass% or more, wherein the tensile modulus of the sealant layer at 23°C, calculated under the following conditions, is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction, and the tensile modulus of the substrate layer at 23°C is 1.5 to 3.0 GPa in the MD direction and 2.0 to 5.5 GPa in the TD direction, wherein the ratio of the tensile modulus of the substrate layer to the tensile modulus of the sealant layer is 1.5 to 5.0 in the MD direction and 4.0 to 10 in the TD direction, and wherein the barrier layer comprises, from the substrate layer side, an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order, A laminate, wherein the base layer is a stretched polypropylene film and the sealant layer is a non-stretched polypropylene film, the sealant layer comprises, from the base layer side, a laminate layer, a sealant base material, and a heat seal layer, the sealant base material contains a propylene-ethylene block copolymer, the heat seal layer contains a propylene-ethylene random copolymer, and the sealant base material contains an elastomer component in an amount of more than 0 mass% to 35 mass% or less based on the total amount of the sealant base material. (Conditions) A tensile test is conducted under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

[15] A packaging material comprising the laminate according to any one of [1] to

[14] , wherein the resin films constituting the packaging material are only the base layer and the sealant layer.

[0119] 10...base material layer, 11...barrier layer, 20...adhesive layer, 30...sealant layer, 30a...sealing surface, 100...laminated body, 400...packaging bag, 401...main body portion, 402...sealing portion, C...contents

Claims

1. A laminate comprising a base layer, a barrier layer, an adhesive layer, and a sealant layer, the barrier layer and the sealant layer being bonded via the adhesive layer, the base layer and the sealant layer containing a polypropylene-based resin, the content of the polypropylene-based resin being 90% by mass or more based on the total weight of the laminate, and the tensile modulus of the sealant layer at 23°C calculated under the following conditions is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction: (Conditions) A tensile test is conducted under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample is elongated by 0.05 to 0.25%.

2. The laminate according to claim 1, wherein the barrier layer comprises an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order from the substrate layer side.

3. The laminate according to claim 2, wherein the thickness of the vapor-deposited layer is 5 to 80 nm.

4. The laminate according to claim 1 or 2, wherein the thickness of the adhesive layer is 0.5 to 10 μm.

5. The laminate according to claim 1 or 2, wherein the substrate layer is an oriented polypropylene film and the sealant layer is an unoriented polypropylene film.

6. The laminate according to claim 2 or 3, wherein the overcoat layer comprises a cured product of a composition containing a water-soluble polymer and a metal alkoxide or a hydrolyzate thereof.

7. The laminate according to claim 1 or 2, wherein the sealant layer comprises at least a sealant substrate and a heat seal layer in this order from the substrate layer side.

8. The laminate of claim 7, wherein the sealant base comprises a propylene-ethylene block copolymer.

9. The laminate of claim 7, wherein said heat seal layer comprises a propylene-ethylene random copolymer.

10. The laminate according to claim 7, wherein the sealant base material contains an elastomer component in an amount of more than 0% by mass and 35% by mass or less, based on the total amount of the sealant base material.

11. The laminate according to claim 1 or 2, wherein the tensile modulus of elasticity of the base layer at 23°C calculated under the above conditions is 1.5 to 3.0 GPa in the machine direction and 2.0 to 5.5 GPa in the transverse direction.

12. The laminate according to claim 11, wherein the ratio of the tensile modulus of the base layer to the tensile modulus of the sealant layer is 1.5 to 5.0 in the machine direction and 4.0 to 10 in the transverse direction.

13. The laminate according to claim 1 or 2, which is for use in a moist heat treatment.

14. A laminate comprising a substrate layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded via the adhesive layer; the substrate layer and the sealant layer contain polypropylene-based resins, and the content of the polypropylene-based resin based on the total amount of the laminate is 90 mass% or more; the tensile modulus of the sealant layer at 23°C, calculated under the following conditions, is 800 MPa or more in the MD direction and 650 MPa or more in the TD direction, and the tensile modulus of the substrate layer at 23°C is 1.5 to 3.0 GPa in the MD direction and 2.0 to 5.5 GPa in the TD direction; the ratio of the tensile modulus of the substrate layer to the tensile modulus of the sealant layer is 1.5 to 5.0 in the MD direction and 4.0 to 10 in the TD direction; and the barrier layer comprises, from the substrate layer side, an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order; A laminate, wherein the substrate layer is a stretched polypropylene film and the sealant layer is a non-stretched polypropylene film, the sealant layer comprises, from the substrate layer side, a laminate layer, a sealant substrate, and a heat seal layer, the sealant substrate contains a propylene-ethylene block copolymer, the heat seal layer contains a propylene-ethylene random copolymer, and the sealant substrate contains an elastomer component in an amount of more than 0 mass% to 35 mass% or less based on the total amount of the sealant substrate. (Conditions) A tensile test is conducted under conditions of a sample width of 20 mm, a gauge length of 250 mm, and a tensile speed of 5 mm / min, and the tensile modulus is calculated from the stress value when the sample is elongated by 0.05 to 0.25%.

15. A packaging material comprising the laminate according to claim 1 or 2, wherein the resin film constituting the packaging material is only the base layer and the sealant layer.

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