Laminates and packaging materials

Abstract

A laminate comprising a base layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded together via the adhesive layer, the base layer and the sealant layer contain a polypropylene resin, the polypropylene resin content relative to the total amount of the laminate is 90% by mass or more, 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 performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

Description

[Technical Field]

[0001] This disclosure relates to laminates and packaging materials. [Background technology]

[0002] In recent years, there has been a growing need for environmentally friendly and sustainable packaging materials, and the development of packaging materials (monomaterial packaging) composed of laminated layers containing the same material with good recyclability is progressing.

[0003] As an example of such a monomaterial packaging material, Patent Document 1 discloses a polypropylene-based packaging material comprising a base material which is a biaxially oriented polypropylene film, an intermediate layer which comprises a biaxially oriented polypropylene film and a vapor-deposited film, and a heat-seal layer which is an unoriented polypropylene film. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-132355 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in order to make packaging materials more sustainable, there is also a need to reduce the amount of resin film itself used in packaging materials. In the case of the packaging material described in Patent Document 1, for example, it is conceivable to create a laminate with a substantially two-layer structure by removing either the biaxially oriented polypropylene film of the base material or the intermediate layer. However, if a packaging bag formed using such a laminate is subjected to moist heat treatment such as high-temperature retort treatment, 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 an object thereof is to provide a laminate that has a more sustainable configuration and can maintain good barrier properties even after heat and humidity treatment at high temperatures. Another object of the present disclosure is to provide a packaging material obtained using the laminate. **Means for Solving the Problems**

[0007] One aspect of the present disclosure includes a base material layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are adhered via the adhesive layer, the base material 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% by mass or more. The present disclosure provides a laminate in which the tensile modulus of elasticity 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. (Condition) A tensile test is performed 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 of elasticity is calculated from the stress value when the sample is stretched by 0.05 to 0.25%.

[0008] The above laminate has a more sustainable configuration and can maintain good barrier properties even after heat and humidity treatment at high temperatures.

[0009] In one aspect, the barrier layer may include an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order from the base material layer side. Thereby, good barrier properties can be maintained at a higher level.

[0010] In one aspect, the thickness of the vapor deposition layer may be 5 to 80 nm.

[0011] In one aspect, the thickness of the adhesive layer may be 0.5 to 10 μm.

[0012] In one aspect, the base material layer may be a stretched polypropylene film, and the sealant layer may be an unstretched polypropylene film.

[0013] In one aspect, 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 aspect, the sealant layer may include at least a sealant base material and a heat-seal layer in this order from the base material layer side.

[0015] In one aspect, the sealant base material may include a propylene-ethylene block copolymer.

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

[0017] In one aspect, the sealant base material may contain 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.

[0018] In one aspect, the tensile modulus of the base material layer calculated under the above conditions at 23°C 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 aspect, the ratio of the tensile modulus of the base material 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 aspect, the laminate may be for hydrothermal treatment.

[0021] One aspect of the present disclosure includes a base material layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are adhered via the adhesive layer. The base material 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% by mass or more. The tensile modulus of the sealant layer at 23°C, calculated under the following conditions, is 800 MPa or higher in the MD direction and 650 MPa or higher in the TD direction, and the tensile modulus of the base 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 base layer is a stretched polypropylene film, and the sealant layer is an unstretched polypropylene film. The sealant layer comprises a laminate layer, a sealant substrate, and a heat seal layer from the substrate layer side. The sealant base material contains a propylene-ethylene block copolymer, and the heat seal layer contains a propylene-ethylene random copolymer. The present invention provides a laminate in which the sealant substrate contains elastomer components in an amount of more than 0% by mass and up to 35% by mass, based on the total amount of the sealant substrate. (Conditions) A tensile test is performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

[0022] One aspect of this disclosure is to provide a packaging material comprising the above-mentioned laminate, wherein the resin film constituting the packaging material consists only of a base layer and a sealant layer.

[0023] The above packaging material has a more sustainable structure than the above laminate, while maintaining good barrier properties even after high-temperature moist heat treatment. [Effects of the Invention]

[0024] This disclosure provides a laminate that has a more sustainable structure while maintaining good barrier properties even after high-temperature moist heat treatment. Furthermore, this disclosure provides a packaging material obtained using this laminate. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 is a schematic cross-sectional view showing one embodiment of the laminate of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view showing one embodiment of the packaging of the present disclosure. [Modes for carrying out the invention]

[0026] Embodiments of this disclosure are described below. The same reference numerals are used for identical components, and redundant descriptions are omitted. Furthermore, the dimensional ratios in the drawings are not limited to those shown.

[0027] [Laminated structure] Embodiments of the laminate of this disclosure will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view showing one embodiment of the laminate of this disclosure.

[0028] As shown in Figure 1, the laminate 100 comprises at least a base layer 10 having a barrier layer 11, an adhesive layer 20, and a sealant layer 30. The side of the sealant layer 30 opposite to the base layer 10 is the sealing surface 30a. The side of the base layer 10 facing the barrier layer 11 and the sealant layer 30 are bonded together via the adhesive layer 20. The base layer 10 and the sealant layer 30 contain a polypropylene resin. The tensile modulus 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 manufactured by bonding a base layer 10 on which a barrier layer 11 is formed and a sealant layer 30 with an adhesive. This results in a laminate 100 comprising a base layer 10, a barrier layer 11, an adhesive layer 20, and a sealant layer 30, in which the barrier layer 11 and the sealant layer 30 are bonded together via the adhesive layer 20.

[0030] The laminate 100, which has a more sustainable structure compared to conventional designs, does not have an intermediate layer containing polypropylene resin between the base layer 10 and the sealant layer 30. In other words, the laminate 100 can be described as a polypropylene laminate with a substantially two-layer structure (consisting of two layers of resin film), as it does not have 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 printed layers as needed.

[0031] The laminate 100 has a more sustainable structure compared to conventional laminates, while maintaining good barrier properties even after high-temperature moist heat treatment. Specifically, when a packaging bag formed using the laminate 100 is subjected to high-temperature moist heat treatment, the barrier properties of the packaging bag can be maintained more effectively compared to when a laminate without 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 is used. In other words, the laminate 100 can be suitably used as a laminate for moist heat treatment. The inventors surmise that this is because the sealant layer 30 with a high tensile modulus suppresses the shrinkage of the base layer 10 during moist heat treatment, thereby suppressing the deterioration of the barrier properties of the barrier layer 11.

[0032] Examples of moist heat treatments include retort treatment and boiling treatment, and the laminate 100 of this disclosure is particularly suitable for retort treatment applications. Retort treatment is, for example, pressurized and heated at 0.33 MPa, 121-130°C, for 15-50 minutes.

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

[0034] (Laminated structure) From the viewpoint of recyclability, the polypropylene resin content in the entire laminate 100 is 90% by mass or more. From the same viewpoint, it is more preferable that the polypropylene resin content in the laminate 100 be 92% by mass or more, and more preferably 95% by mass or more. There is no particular upper limit on the amount of this content, but it is sufficient to subtract the amount of adhesive components, etc., from the total amount of the laminate 100, for example, it may be 99% by mass or less, or 98% by mass or less.

[0035] Since the laminate 100 has barrier properties, it can also be called a gas barrier laminate. Here, barrier properties refer to oxygen barrier properties and water vapor barrier properties, but mainly to oxygen barrier properties.

[0036] (base material 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 resin. The base layer 10 can also be called a gas barrier film.

[0037] The polypropylene resin contained in the base layer 10 is composed of a resin containing propylene as a constituent unit. Examples of polypropylene resins include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with α-olefins such as ethylene or butene, and ethylenepropylene rubber. These can be used individually 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 resin may also be block polypropylene, which is a mixture of homopolypropylene and ethylene propylene rubber.

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

[0039] If the base layer 10 is a stretched polypropylene film (OPP), the OPP used may have a shrinkage rate before and after heat treatment when retorted at 128°C for 15 minutes (shower type) of 1.0-5.0% in the MD direction and 0.5-3.0% in the TD direction. MD heat shrinkage rate (%) = (MD length before heating - MD length after heating) / MD length before heating × 100 TD thermal shrinkage rate (%) = (TD length before heating - TD length after heating) / TD length before heating × 100

[0040] The tensile modulus of the base layer 10 is preferably 1.5 to 3.0 GPa in the MD direction and preferably 2.0 to 5.5 GPa in the TD direction. When the tensile modulus of the base layer 10 is within this range, the heat resistance is better, and the stiffness of the packaging is more easily maintained even after retort processing. From the above viewpoint, the tensile modulus 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 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 performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

[0041] The surface of the substrate layer 10 on the side facing the sealant layer 30 may be subjected to various pretreatments such as corona treatment, plasma treatment, ozone treatment, or flame treatment, or a coating layer such as an easy-adhesion layer may be provided. The base layer 10 may contain resins other than polypropylene resins. Examples of such resins include polyolefin resins such as polyethylene resins. The base layer 10 may optionally contain at least one additive selected from fillers, antistatic agents, plasticizers, lubricants, and antioxidants.

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

[0043] (Barrier layer) Since the laminate 100 is equipped with a barrier layer 11, when a packaging bag is made using the laminate 100 and contents are placed inside the packaging bag to create a package, the deterioration of the contents due to gases such as oxygen can be effectively suppressed. The barrier layer 11 is provided on the surface of the base layer 10 that faces the sealant layer 30. As a result, the barrier layer 11 is protected by the sealant layer 30, which has a high tensile modulus, thus preventing damage to the barrier layer 11 during lamination processing, bag making, filling, or transportation of the packaged bags.

[0044] (deposited layer) The barrier layer 11 may include a vapor-deposited layer composed of an inorganic compound. The inorganic compound constituting the vapor-deposited layer may be SiO X and AlO X Examples include the barrier layer 11, for example, SiO X When this method is used, the barrier layer 11 becomes transparent, making it possible to see the contents from the outside of the packaging bag. The vapor-deposited layer is SiO X or AlO X Inorganic compounds such as these can be formed using vacuum deposition. The thickness of the deposited layer may be, for example, 5 to 80 nm or 20 to 40 nm.

[0045] (Overcoat layer) The barrier layer 11 has barrier properties even if it is composed only of a vapor-deposited layer, but it is preferable that it be composed of a composite layer formed by further layering an overcoat layer on top of the vapor-deposited layer.

[0046] Because the barrier layer 11 is composed of a composite layer, a reaction layer is formed between the two layers at the interface between the vapor-deposited layer and the overcoat layer in the barrier layer 11, or a dense structure is formed by the overcoat layer filling or reinforcing defects or micropores such as pinholes, cracks, grain boundaries that occur in the vapor-deposited layer. Therefore, the barrier layer 11, which is composed of a composite layer formed by combining the overcoat layer and the vapor-deposited layer, achieves higher barrier properties, moisture resistance and water resistance, and also has flexibility that can withstand deformation due to external forces, thus providing the laminate 100 with suitability as a packaging material.

[0047] The overcoat layer can be formed, for example, by a coating method in which an overcoat agent (coating agent) is applied to the vapor-deposited layer and then heated and dried. In other words, the overcoat layer can be said to include a cured body of the overcoat agent.

[0048] The overcoat agent may primarily consist of an aqueous solution or water / alcohol aqueous solution containing a water-soluble polymer and at least one of the following: a metal alkoxide, its hydrolysate, or tin chloride. Preferably, the overcoat agent is a composition containing a water-soluble polymer and a metal alkoxide or its hydrolysate. The overcoat agent may further contain a silane coupling agent. In this case, the adhesion between the overcoat layer and the vapor-deposited layer can be improved.

[0049] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, and sodium alginate. In particular, when polyvinyl alcohol (PVA) is included in the overcoat agent, the gas barrier properties tend to be superior.

[0050] Examples of the metal alkoxide 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 may be an alkyl group such as a methyl group or an ethyl group (OR 1 is a hydrolyzable group). R 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. When there are a plurality of R 1 and R 2 , R 1 may be the same or different from each other, and R 2 may also be the same or different from each other.

[0051] Specific examples of the metal alkoxide include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2’-C3H7)3], etc. Tetraethoxysilane (TEOS) and triisopropoxyaluminum tend to be relatively stable in an aqueous solvent 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, 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, R 23 represents a monovalent organic functional group, and p represents an integer from 1 to 3. When there are a plurality of R 21 or R 22 , R 21 may be the same or different from each other, and R 22They may be the same or different. 23 Examples of monovalent organic functional groups include glycidyloxy groups, epoxy groups, mercapto groups, hydroxyl groups, amino groups, alkyl groups substituted with halogen atoms, or monovalent organic functional groups containing isocyanate groups. Dimers, trimers, and other polymers of these compounds may also be used as silane coupling agents.

[0053] Specific examples of silane coupling agents 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 included as a 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 included as a 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 easily maintaining a low oxygen permeability even after heat sterilization treatment.

[0055] When TEOS (tetraethoxysilane) is included as a 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 a low oxygen permeability even after heat sterilization treatment. When TEOS is included as a 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 facilitating the formation of the overcoat layer. In this specification, the amount of TEOS refers to the value converted to SiO2.

[0056] When an isocyanurate silane is included 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 viewpoint of easily achieving resistance to hot water and easily achieving excellent adhesion even after heat sterilization treatment. When an isocyanurate silane is included 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 viewpoint of not reducing the amount of other components in the composition too much and making it easy to maintain a low oxygen permeability even after heat sterilization treatment.

[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, it is easier to achieve high gas barrier properties. Furthermore, if the thickness of the overcoat layer is 0.5 μm or less, the decrease in gas barrier properties due to crack formation in the layer during coating can be suppressed, and because the swelling of the layer under high temperature and high humidity conditions is small, even if cracks occur in the vapor-deposited layer, their diffusion can be prevented, and as a result, the decrease in barrier performance can be suppressed. From this viewpoint, 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 it may be provided via an anchor coat layer. The anchor coat layer is a layer that further improves the adhesion between the substrate layer 10 and the vapor-deposited layer, and is provided between the substrate layer 10 and the vapor-deposited layer.

[0059] The anchor coat layer can be formed using an anchor coat agent, which is a curable compound such as polyester polyurethane resin, polyether polyurethane resin, or acrylic urethane resin dissolved in a solvent. The anchor coat layer can be formed by coating the substrate layer 10 with the anchor coat agent using a coating method that applies printing techniques such as gravure coating or a generally known coating method, and then drying it.

[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-deposited layer more uniform and to further improve the oxygen barrier properties. In addition, by making the anchor coat layer thicker, it is easier to suppress the decrease in water vapor barrier properties when external forces such as stretching are applied. From this viewpoint, 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 improved compared to when the thickness of the anchor coat layer exceeds 2000 nm, and the gas barrier properties of the laminate after abuse testing 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] Based on 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] Thus, the barrier layer 11 may comprise an anchor coat layer, a vapor-deposited layer, and an overcoat layer in this order from the substrate layer 10 side. The thickness of the barrier layer 11 depends 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 substrate layer 10 and the sealant layer 30 to bond them together. For example, any adhesive, such as a one-component curing type or a two-component curing type urethane adhesive, can be used to form the adhesive layer. In addition, both solvent-based adhesives and solvent-free adhesives can be used to form the adhesive layer. From an environmental perspective, it is preferable that the adhesive be GPTMS (3-glycidyloxypropyltrimethoxysilane) free.

[0065] Examples of solvent-based adhesives include urethane-based adhesives, epoxy-based adhesives, and silicone-based adhesives. However, from the viewpoint of impact resistance, urethane-based adhesives are preferred, and two-component curing type urethane-based adhesives are particularly preferred. There are no particular restrictions on the solvent used in solvent-based adhesives, but examples include ethyl acetate, methanol, isopropyl alcohol, methyl ethyl ketone, and ethanol.

[0066] Two-component urethane adhesives contain a polyol component as the main agent and a polyisocyanate component as the curing agent.

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

[0068] Polyester polyols may be, for example, esterification products of polycarboxylic acids, dialkyl esters of polycarboxylic acids, and mixtures thereof with glycol-based solvents. Polycarboxylic acids may be, for example, succinic acid, glutaric acid, isophthalic acid, terephthalic acid, adipic acid, pimelic acid, corticic acid, azelaic acid, sebatic acid, dodecanedioic acid, and dimer acids. Glycol-based solvents may be, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, neopentyl glycol, and 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 water, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin.

[0070] Polyether ester polyols may be obtained, for example, by the reaction of a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a polyether polyol.

[0071] Polyurethane polyols may be, for example, reaction products of polyester polyols, polyether polyols, or polyether ester polyols with polyisocyanate monomers.

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

[0073] Aliphatic polyisocyanates may be, for example, polyisocyanate monomers, polyisocyanate derivatives, or polyisocyanate-terminated prepolymers. Polyisocyanate monomers may be, for example, tetramethylene diisocyanate, isopropyl diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, or trimethylhexamethylene diisocyanate. Polyisocyanate derivatives may be 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, lysine diisocyanate, or isophorone diisocyanate.

[0074] Aromatic polyisocyanates may be, for example, polyisocyanate monomers, polyisocyanate derivatives, or polyisocyanate-terminated prepolymers. Polyisocyanate monomers may be, for example, tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, or tetramethylxylylene diisocyanate. Polyisocyanate derivatives may be, for example, isocyanurates derived from polyisocyanate monomers. Polyisocyanate-terminated prepolymers may be difunctional polyisocyanates containing terminal isocyanate groups obtained by reacting polyisocyanate monomers with a difunctional polyol compound such as polypropylene glycol. Alternatively, polyisocyanate-terminated prepolymers may be polyfunctional polyisocyanates containing terminal isocyanate groups obtained by reacting polyisocyanate monomers with a polyol compound with three or more functions, 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, but from the viewpoint of impact resistance, urethane-based adhesives are preferred, and two-component curing type urethane-based adhesives are particularly preferred.

[0076] The thickness of the adhesive layer 20 may be 0.5 to 10 μm, or 2 to 3 μm. A thickness of 0.5 μm or more improves the adhesion of the adhesive layer 20. A thickness of 10 μm or less improves the processability of the laminate.

[0077] The weight per unit area of ​​the adhesive layer 20 after curing is 0.5 to 3.5 g / m². 2 Preferably, 1.0 to 3.0 g / m 2 This is more preferable. The weight per unit area of ​​the adhesive layer 20 after curing is 0.5 g / m². 2 If the above is achieved, the effect of suppressing delamination between layers can be enhanced. The weight per unit area of ​​the adhesive layer after curing is 3.5 g / m². 2 The following conditions can suppress winding misalignment during the processing of the laminate, improve the appearance quality of the laminate, and, in addition, achieve appropriate laminate strength.

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

[0079] (Sealant layer) The sealant layer 30 is a layer that provides heat-sealing properties to the laminate 100 and contains a polypropylene resin. The polypropylene resin contains a resin that includes propylene as a constituent unit. Examples of polypropylene resins include homopolypropylene, propylene copolymers obtained by copolymerizing propylene with α-olefins such as ethylene or butene, and ethylenepropylene rubber. These can be used individually 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 resin may also be block polypropylene, which is a mixture of homopolypropylene and ethylene propylene rubber.

[0080] The sealant layer 30 may be an unoriented film or an oriented film, but from the viewpoint of lowering the heat seal temperature and improving the sealing performance by heat sealing, it is preferable to use an unoriented film (unoriented polypropylene film).

[0081] The sealant layer 30 may be composed of a laminate of multiple layers, from the viewpoint of achieving a desired tensile modulus of elasticity and balancing sealant suitability and rigidity. For example, the sealant layer 30 can have a two-layer configuration of sealant substrate / heat seal layer or a three-layer configuration of laminate layer / sealant substrate (core layer) / heat seal layer, starting from the substrate layer 10 side.

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

[0083] For example, the tensile modulus of each layer can be adjusted by adding homopolymers or ethylene propylene rubber (elastomer) to each layer. Adding homopolymers to random copolymers tends to increase the tensile modulus. Adding ethylene propylene rubber to block copolymers 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 viewpoint of further improving bag drop resistance and adjusting the tensile modulus, the amount of elastomer component is preferably greater than 0% by mass and less 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 elastomer. From the above viewpoint, it is preferable that the sealant substrate contains elastomer component in an amount greater than 0% by mass and less than 35% by mass, based on the total amount of the sealant substrate.

[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, it is easier to exhibit the protective function of the vapor-deposited layer compared to when it is less than 50 μm, and it is easier to create a laminate that can maintain good barrier properties even after high-temperature moist heat treatment. On the other hand, when the thickness of the sealant layer 30 is 80 μm or less, it is easier to achieve resource conservation compared to when it is greater than 80 μm, and it is easier to create a more sustainable laminate 100.

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

[0087] When the tensile modulus of the sealant layer 30 in the MD direction is 800 MPa or higher, it is possible to maintain good barrier properties even after moist heat treatment, compared to when it is less than 800 MPa. In addition, the stiffness of the laminate is increased, resulting in excellent filling suitability (the open state is easily maintained during filling). From this viewpoint, the tensile modulus is preferably 850 MPa or higher, more preferably 900 MPa or higher, and even more preferably 1000 MPa or higher. There is no particular upper limit to the tensile modulus, but it is preferably 1300 MPa from the viewpoint of resistance to bag drop.

[0088] When the tensile modulus of the sealant layer 30 in the TD direction is 650 MPa or higher, it is possible to maintain good barrier properties even after moist heat treatment, compared to when it is less than 650 MPa, and the stiffness of the laminate is increased, resulting in excellent filling suitability. From this viewpoint, the tensile modulus is preferably 700 MPa or higher, more preferably 800 MPa or higher, and even more preferably 900 MPa or higher. There is no particular upper limit to the tensile modulus, but it is preferably 1000 MPa from the viewpoint of resistance to bag drop.

[0089] From the viewpoint of maintaining good barrier properties even after moist heat treatment at high temperatures and achieving excellent openability, it is preferable that the ratio of the tensile modulus of the base layer to the tensile modulus of the sealant layer is 1.5 or higher in the MD direction and 4.0 or higher in the TD direction. Packaging materials can be provided with a starting point (such as a notch or cut) for opening. When force is applied to the starting point for opening, stress concentrates in the base layer with a high modulus of elasticity, making it more likely for cracks to form before those in the sealant layer. On the other hand, the sealant layer with a low modulus of elasticity absorbs and disperses the stress on the tip of the crack, suppressing crack propagation and making its direction of propagation unstable. By providing an appropriate difference in the modulus of elasticity between the base layer and the sealant layer, it becomes possible to efficiently generate cracks in the base layer from the starting point during opening, and for those cracks to propagate smoothly and in the intended direction without being hindered by the sealant layer, thereby achieving good openability. Openability can be evaluated by the "shear rate" when the packaging material is torn, as shown in the examples.

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

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

[0092] (Printing layer) The laminate 100 may include a printed layer, as previously mentioned. The printing layer can be provided between the barrier layer 11 of the base material layer 10 and the adhesive layer 20. The printing layer is provided in 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 factors such as printability on other layers in the laminate 100, design properties such as color tone, adhesion, and safety as a food container. For example, a urethane resin can be used as the printing ink.

[0094] The printing method is not particularly restricted and can be appropriately selected from known printing methods. Examples of printing methods include gravure printing, offset printing, gravure-offset printing, flexographic printing, and inkjet printing. Among these, gravure printing is preferred from the viewpoint of productivity and high image resolution.

[0095] [Packaging materials] The packaging material includes the laminate 100 described above. The resin films constituting the packaging material consist only of the base layer and the sealant layer. The packaging material obtained using the laminate 100, which has a more sustainable structure than conventional materials, is also a sustainable packaging material (packaging film) that does not contain any resin films other than the resin film constituting the base layer 10 and the resin film constituting the sealant layer 30. Furthermore, this packaging material also possesses the characteristic of the laminate 100, which is that it can maintain good barrier properties even after high-temperature moist heat treatment.

[0096] In addition to the laminate 100 described above, the packaging material may include layers such as a concealing layer to make the contents less visible from the outside, a coloring layer to color the packaging material, a heat-resistant coating layer to improve the heat resistance of the packaging material, an easy-peel layer to facilitate peeling between specific layers of the packaging material, an adsorption layer to adsorb specific substances from the contents, a release layer to release specific substances into the contents, and an uneven layer to improve the aesthetic appearance of the outermost surface of the packaging material.

[0097] [Packaging] Figure 2 is a schematic cross-sectional view showing one embodiment of the packaging of the present disclosure. As shown in Figure 2, the packaging 500 comprises a packaging bag 400 and contents C contained within the packaging bag 400. The packaging bag 400 is formed using a laminate 100 as the packaging material, and the sealing surface 30a constitutes the inner surface of the packaging bag 400. For simplicity, the display of the barrier layer 11 is omitted. 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. Therefore, the packaging bag 400 comprises a main body 401 containing the contents C and a sealing portion 402 surrounding the main body 401.

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

[0099] (packaging bag) The packaging bag 400 obtained from the above laminate 100 has a more sustainable structure while maintaining good barrier properties even after high-temperature moist heat treatment. The two laminated bodies 100 that make up the packaging bag 400 may be made of different materials, and may also differ in thickness, shape, etc. The packaging bag 400 is not particularly limited to the four-sided pouch shown in Figure 2, and can be appropriately selected according to the intended use of the packaging bag. The packaging bag 400 may be, for example, a three-sided pouch, a pillow bag, a standing pouch, a gusseted bag, a spouted bag, etc.

[0100] The packaging bag 400 may be composed of three or more laminated structures 100. In this case, the multiple laminated structures 100 constituting the packaging bag 400 may be made of different materials, and may have different thicknesses, shapes, etc.

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

[0102] The embodiments of this disclosure will be described in detail below. However, the forms of this disclosure are not limited to the embodiments described below.

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

[0104] The following anchor coating agent was applied to one side of the substrate layer using gravure coating, and then dried at 50°C. This formed an anchor coating layer with a thickness of 0.2 μm. (Anchor coating agent) An acrylic polyol and tolylene diisocyanate were mixed so that the number of NCO groups in the tolylene diisocyanate was equal to the number of OH groups in the acrylic polyol. The mixture was 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 for every 100 parts by mass of the total amount of acrylic polyol and tolylene diisocyanate, and these were mixed to prepare an anchor coating agent.

[0105] Using an electron beam heating vacuum deposition system, a 30 nm thick layer of silicon dioxide (SiO₂) is deposited onto the anchor coat layer. X A vapor-deposited layer consisting of ) was formed.

[0106] The following overcoat agent was applied to the vapor-deposited layer by bar coating, 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 in a mass ratio of 25:70:5 between polyvinyl alcohol (PVA) in solution A, SiO2 in solution B, and silane coupling agent (SC agent) in solution C to prepare an overcoat agent. Solution A: An aqueous solution prepared to contain 5% by mass of PVA (manufactured by Kuraray Co., Ltd., product name: Kuraray Poval 60-98). Solution B: A hydrolysis solution prepared by mixing 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.) in a mass ratio of 17:10:73, and adjusting the solid content to 5% by mass (on an SiO2 basis). Solution C: 1,3,5-Tris(3-methoxysilylpropyl) isocyanurate in a solution with water and IPA (isopropyl alcohol) in a mass ratio of 1:1, with a solid content of 5% by mass (R 2 A hydrolysis solution adjusted to have a Si(OH)3 equivalent.

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

[0108] The sealant layer used had a three-layer structure: a laminate layer, a core layer (sealant substrate), and a heat-seal layer. Specifically, the sealant layer was fabricated as follows. For the laminate layer, a resin mixture was prepared by mixing 70% by mass of a propylene homopolymer (indicated as h-PP in Table 1) with a melt flow rate of 3.0 g / 10 min and a melting point of 162 °C, and 30% by mass of a propylene-ethylene random copolymer (indicated as r-PP in Table 1) with a melt flow rate of 7.0 g / 10 min and a melting point of 144 °C, in pellet form. For the core layer, a propylene-ethylene block copolymer (indicated as b-PP in Table 1) with a melt flow rate of 2.0 g / 10 min and a melting point of 162 °C was prepared with the addition of an elastomer component, which is a block copolymer of polypropylene and ethylene-α-olefin copolymer rubber (with random polypropylene components), having a melt flow rate of 0.6 g / 10 min and a melting point of 145 °C. The amount of the elastomer component was set to 10% by mass based on the total amount of the core layer. For the heat-seal layer, the same resin mixture as for the laminate layer was prepared. Each raw material was supplied to an extruder heated to 250°C, mixed in a molten state, and then extruded and laminated using a T-die extruder with a feed block to produce the unoriented polypropylene film of Example 1. The thickness of the laminate layer was 10 μm, the thickness of the core layer was 40 μm, and the thickness of the heat-seal layer was 10 μm.

[0109] Next, a polyurethane-based adhesive that adheres using the addition reaction between polyisocyanate and polyol was applied to the barrier layer surface of the gas barrier film. Subsequently, the gas barrier film and a 60 μm thick unoriented polypropylene film, which served as the sealant layer, were bonded together via an adhesive layer (3.0 μm thick) formed from the aforementioned adhesive. In this way, a laminate (base layer / barrier layer / adhesive layer / sealant layer) was fabricated.

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

[0111] (Other examples and comparative examples) The laminate was fabricated in the same manner as in Example 1, except that the layer configuration of the sealant layer was changed as shown in Table 1. Note that the h-PP, r-PP, b-PP, and elastomer in Table 1 are the same as those described in Example 1. In each example of the laminate, the polypropylene resin content, based on the total amount of the laminate, was 90% by 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: Tensile tests were performed using a benchtop precision universal testing machine (product name "Autograph AGS-X", manufactured by Shimadzu Corporation) under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus was calculated from the stress value when the sample elongated by 0.05 to 0.25%. The results are shown in Table 1.

[0113] (Oxygen permeability measurement) From the laminates obtained in each example, two films measuring 95 mm (MD direction) x 140 mm (TD direction) were prepared. By placing the sealing surfaces of these films facing each other and heat-sealing three sides, a packaging bag with an opening was created. 70 g of water was filled into the packaging bag through the opening, and the opening was sealed by heat-sealing to create a package. The prepared packaging was subjected to retort processing at 128°C for 15 minutes (shower type). Oxygen permeability (OTR, unit: cc / m³) of retort-treated packaging (laminated material) 2The oxygen permeability (·day·atm) was measured using an oxygen permeability analyzer (product name "OX-TRAN2 / 20", manufactured by MOCON). The measurement was performed in accordance with JIS K-7126-2, under measurement conditions of 30°C and 70% relative humidity. The results are shown in Table 1.

[0114] (Filling suitability evaluation) A packaging bag with an opening was prepared in the same manner as the oxygen permeability measurement. The filling suitability (opening ability) of this packaging bag when fed into a bag-feeding machine was evaluated according to the following criteria. The results are shown in Table 1. Over 98% of opened products were good: ○ Opened product yield rate: 95% or higher but less than 98%: △ Percentage of good products after opening: less than 95%: ×

[0115] (Evaluation of resistance to bag drop) Similar to the oxygen permeability measurement, 100 water-filled packages were prepared for each example. The prepared packaging was held horizontally to the floor and dropped 100 times from a height of 1 meter. Drop resistance was evaluated based on the percentage of packaging bags that did not break (survival rate) according to the following criteria. The results are shown in Table 1. Survival rate 100%:〇 Survival rate between 95% and 100%: △ Remaining rate less than 95%: ×

[0116] (Evaluation of ease of opening) A packaging bag with an opening was prepared in the same manner as for oxygen permeability measurement. A 5 mm long cut was made in the MD direction on one side of the packaging bag in the TD direction, and the packaging bag was torn by hand in the MD direction using this cut as a starting point. The state of the torn packaging bag was observed, and the ease of opening 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 opposite side in the TD direction (slip ratio less than 20%): ○ The tear crack propagated in the MD direction and reached the opposite side in the TD direction (slip ratio of 20% or more): △ The tear crack progressed in a direction different from the MD direction midway through and did not reach the opposite side in the TD direction: × The deviation rate is a value calculated based on the amount of deviation, as follows. Displacement [mm] = |(Position reached at the opposite side of the packaging bag in the TD direction on the front side) - (Position reached at the opposite side of the packaging bag in the TD direction on the back side)| Displacement rate [%] = (Amount of displacement) / (Length of the packaging bag in the TD direction) × 100

[0117] [Table 1]

[0118] The summary of this disclosure is as follows: [1] comprising a base layer, a barrier layer, an adhesive layer, and a sealant layer, The barrier layer and the sealant layer are bonded together via the adhesive layer. The base layer and the sealant layer contain a polypropylene resin, and the content of the polypropylene resin based on the total amount of the laminate is 90% by mass or more. A laminate in which 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 performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. 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 an anchor coat layer, a vapor deposition layer, and an overcoat layer in that order from the substrate layer side. [3] The laminate according to [2], wherein the thickness of the vapor-deposited layer is 5 to 80 nm. [4] The laminate according to any one of [1] to [3], wherein the thickness of the adhesive layer is 0.5 to 10 μm. [5] The laminate according to any one of [1] to [4], wherein the base 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 body of a composition comprising a water-soluble polymer and a metal alkoxide or a hydrolysate 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], comprising a sealant substrate 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 contains 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 substrate.

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

[10] , wherein the tensile modulus of the base 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 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] A laminate according to any one of [1] to

[12] , for use in moist heat treatment.

[14] comprising a base layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded together via the adhesive layer, The base layer and the sealant layer contain a polypropylene resin, and the content of the polypropylene resin based on the total amount of the laminate is 90% by 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 base 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 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. 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 base layer is a stretched polypropylene film, and the sealant layer is an unstretched polypropylene film. The sealant layer comprises a laminate layer, a sealant substrate, and a heat seal layer from the substrate layer side. The sealant substrate comprises a propylene-ethylene block copolymer, and the heat seal layer comprises a propylene-ethylene random copolymer. A laminate in which the sealant substrate contains 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 substrate. (Conditions) A tensile test is performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

[15] A packaging material comprising a laminate described in any one of [1] to

[14] , wherein the resin film constituting the packaging material consists only of the base layer and the sealant layer. [Explanation of symbols]

[0119] 10...Base layer, 11...Barrier layer, 20...Adhesive layer, 30...Sealant layer, 30a...Sealing surface, 100...Laminate, 400...Packaging bag, 401...Main body, 402...Sealing part, C...Contents.

Claims

1. The material comprises a base layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded together via the adhesive layer. The base layer and the sealant layer contain a polypropylene resin, and the content of the polypropylene resin, based on the total amount of the laminate, is 90% by mass or more. A laminate in which 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 performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

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

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 base layer is a stretched polypropylene film and the sealant layer is an unstretched polypropylene film.

6. The laminate according to claim 2 or 3, wherein the overcoat layer comprises a cured body of a composition comprising a water-soluble polymer and a metal alkoxide or its hydrolysate.

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

8. The laminate according to claim 7, wherein the sealant substrate comprises a propylene-ethylene block copolymer.

9. The laminate according to claim 7, wherein the heat-seal layer comprises a propylene-ethylene random copolymer.

10. The laminate according to claim 7, wherein the sealant substrate contains 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 substrate.

11. The laminate according to claim 1 or 2, wherein the tensile modulus of the base 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 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 MD direction and 4.0 to 10 in the TD direction.

13. A laminate according to claim 1 or 2, for use in moist heat treatment.

14. The material comprises a base layer, a barrier layer, an adhesive layer, and a sealant layer, wherein the barrier layer and the sealant layer are bonded together via the adhesive layer. The base layer and the sealant layer contain a polypropylene resin, and the content of the polypropylene resin, based on the total amount of the laminate, is 90% by 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 base 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 base 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 base layer is a stretched polypropylene film, and the sealant layer is an unstretched polypropylene film. The sealant layer comprises a laminate layer, a sealant substrate, and a heat seal layer from the substrate layer side. The sealant substrate comprises a propylene-ethylene block copolymer, and the heat seal layer comprises a propylene-ethylene random copolymer. A laminate in which the sealant substrate contains 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 substrate. (Conditions) A tensile test is performed under the conditions of a sample width of 20 mm, gauge length of 250 mm, and tensile speed of 5 mm / min. The tensile modulus is calculated from the stress value when the sample elongates by 0.05 to 0.25%.

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

Images