Gas barrier laminate and packaging

Abstract

This gas barrier laminate comprises: a barrier layer having a substrate on which a barrier coat is disposed; a sealant layer overlying a first major surface of the barrier layer; a support layer overlying a second major surface of the barrier layer; a first adhesive layer that bonds the barrier layer and the sealant layer; and a second adhesive layer that bonds the barrier layer and the support layer. The first adhesive layer contains a two-component curable urethane adhesive. The substrate contains a polyolefin. After the gas barrier laminate is subjected to a retort treatment, the elastic modulus of the first adhesive layer is 5 MPa or more and less than 53 MPa as measured by a scanning probe microscope.

Description

Gas barrier laminate and packaging bag

[0001] The present disclosure relates to a gas barrier laminate and a packaging bag.

[0002] Conventionally, laminates (gas barrier laminates) provided with gas barrier properties such as oxygen barrier properties and water vapor barrier properties have been used from the viewpoint of protecting contents wrapped in packaging materials, etc. For example, Patent Document 1 listed below discloses a gas barrier laminate film including a resin substrate, a gas barrier vapor deposition layer provided on the resin substrate and containing mainly inorganic compounds, and a gas barrier coating layer provided on the gas barrier vapor deposition layer.

[0003] Patent No. 4200972

[0004] When the gas barrier laminate described above is subjected to a retort treatment, there is a problem that the gas barrier properties are likely to deteriorate.

[0005] An object according to one aspect of the present disclosure is to provide a gas barrier laminate and a packaging bag that are capable of exhibiting good gas barrier properties even after retort treatment.

[0006] A gas barrier laminate according to one aspect of the present disclosure comprises a barrier layer having a substrate on which a barrier coat is provided, a sealant layer overlying a first main surface of the barrier layer, a support layer overlying a second main surface of the barrier layer, a first adhesive layer bonding the barrier layer and the sealant layer together, and a second adhesive layer bonding the barrier layer and the support layer together, wherein the first adhesive layer comprises a two-component curing urethane adhesive, the substrate comprises a polyolefin, and after retorting the gas barrier laminate, the modulus of elasticity of the first adhesive layer measured with a scanning probe microscope is 5 MPa or more and less than 53 MPa.

[0007] According to this gas barrier laminate, the elastic modulus of the first adhesive layer measured with a scanning probe microscope (SPM) is 5 MPa or more and less than 53 MPa. In this case, even if expansion and contraction of the base material occurs due to retort treatment, the first adhesive layer can follow suit well. Therefore, damage to the barrier coat due to cracks occurring in the first adhesive layer can be suppressed. Therefore, it is possible to provide a gas barrier laminate that can exhibit good gas barrier properties even after retort treatment.

[0008] The second adhesive layer may contain a two-component curing urethane adhesive, and the modulus of elasticity of the second adhesive layer measured with a scanning probe microscope after retort treatment may be 5 MPa or more and less than 53 MPa. In this case, even if expansion and contraction of the substrate and support layer occurs due to retort treatment, the second adhesive layer can follow well. Therefore, damage to the barrier coat due to cracks occurring in the second adhesive layer can also be suppressed.

[0009] The barrier layer may further include an anchor coat layer and a vapor deposition layer located between the substrate and the barrier coat, and the anchor coat layer may be located between the substrate and the vapor deposition layer. In this case, the gas barrier properties of the gas barrier laminate can be improved.

[0010] The thickness of the vapor-deposited layer may be 5 nm or more and 80 nm or less, which can improve the gas barrier properties while preventing cracks in the vapor-deposited layer.

[0011] Before the retort treatment, the first adhesive layer may have an elastic modulus of 55 MPa or more as measured by a scanning probe microscope.

[0012] The thickness of each of the first adhesive layer and the second adhesive layer may be 0.5 μm or more and 10 μm or less, which makes it possible to easily form a mono-material gas barrier laminate while effectively suppressing peeling between the barrier layer and the sealant layer.

[0013] The elastic modulus of the sealant may be 600 MPa or more and 1400 MPa or less, which may improve the formability of the gas barrier laminate.

[0014] The substrate and the sealant layer may each be a polyolefin film, and the total mass ratio of polyolefin in the gas barrier laminate may be 90 mass % or more. In this case, a mono-material structure is realized.

[0015] The substrate may be a stretched polypropylene film and the sealant layer may be a non-stretched polypropylene film, in which case the laminate has excellent heat resistance against retort treatment and the like.

[0016] One aspect of the present disclosure may provide a packaging bag that is a bag made from the gas barrier laminate.

[0017] According to the present disclosure, it is possible to provide a gas barrier laminate and a packaging bag that can exhibit good gas barrier properties even after retort treatment.

[0018] Fig. 1 is a schematic plan view of a laminate according to one embodiment. Fig. 2 is a schematic cross-sectional view of a laminate according to one embodiment. Fig. 3 is a schematic front view of an example of a packaging bag. Fig. 4 is a schematic view showing a method for measuring the thermal shrinkage rate during oven heating.

[0019] Preferred embodiments of the present disclosure will be described in detail below, with reference to the drawings where appropriate. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0020] <Laminate> Fig. 1 is a schematic plan view of a laminate according to one embodiment. Fig. 2 is a schematic cross-sectional view showing a laminate according to one embodiment. The laminate 1 shown in Figs. 1 and 2 is a sheet-like member (gas barrier laminate) having gas barrier properties, and is, for example, a sheet-like packaging material used in the manufacture of packaging bags and the like. The laminate 1 can be suitably used in applications that require heat treatment, such as retort treatment or boiling treatment.

[0021] Retort processing is a method of pressure sterilization of microorganisms such as mold, yeast, and bacteria, typically for the preservation of food, pharmaceuticals, etc. Typically, packaging bags containing food, etc., are pressure sterilized at 105-140°C and 0.15-0.30 MPa for 10-120 minutes. Retort devices are available in two types: steam type, which uses heated steam, and hot water type, which uses pressurized heated water. The appropriate method is used depending on the sterilization conditions of the food, etc. contained within. Boiling is a moist heat sterilization method for preserving food, pharmaceuticals, etc. Typically, packaging bags containing food, etc., are moist heat sterilized at 60-100°C and atmospheric pressure for 10-120 minutes, depending on the contents. Boiling is typically performed in a hot water bath at temperatures below 100°C. Methods include a batch method, in which the food is immersed in a hot water bath at a constant temperature for a set period of time and then removed, and a continuous method, in which the food is passed through a tunnel-type hot water bath for processing.

[0022] The laminate 1 has a barrier layer 10, a sealant layer 20, a first adhesive layer 30, a support layer 40, and a second adhesive layer 50. In the laminate 1, the sealant layer 20, the first adhesive layer 30, the barrier layer 10, the second adhesive layer 50, and the support layer 40 are laminated in this order. Hereinafter, as shown in Fig. 1 , the direction MD is defined as the machine direction (longitudinal direction) of the laminate 1, and the direction TD is defined as the width direction (short direction) of the laminate 1. Furthermore, the direction perpendicular to both the directions MD and TD is defined as the stacking direction of the members included in the laminate 1.

[0023] [Barrier Layer 10] The barrier layer 10 functions as an intermediate layer in the laminate 1 and exhibits gas barrier properties against gases such as water vapor and oxygen. As shown in FIG. 2 , the barrier layer 10 includes a substrate 11, an adhesion layer 12, a vapor deposition layer 13, and a barrier coat 14. In the barrier layer 10, the substrate 11, the adhesion layer 12, the vapor deposition layer 13, and the barrier coat 14 are laminated in this order. Therefore, the adhesion layer 12 and the vapor deposition layer 13 are located between the substrate 11 and the barrier coat 14 in the stacking direction, and the adhesion layer 12 is located between the substrate 11 and the vapor deposition layer 13. In this embodiment, the substrate 11 of the barrier layer 10 is closest to the first adhesive layer 30 in the stacking direction and forms the first main surface 10b of the barrier layer 10. Therefore, the barrier coat 14 of the barrier layer 10 is farthest from the first adhesive layer 30 in the stacking direction and forms the second main surface 10a of the barrier layer 10.

[0024] [Substrate 11] The substrate 11 is a plastic member that functions as a support layer in the laminate 1. The thickness of the substrate 11 is not particularly limited. Depending on the application, the thickness can be set to 6 to 200 μm, but from the viewpoint of reducing materials to reduce the environmental load and from the viewpoint of obtaining excellent heat resistance, impact resistance, and excellent gas barrier properties, the thickness may be 9 to 50 μm, 12 to 38 μm, or 18 to 30 μm.

[0025] From the viewpoint of the recyclability of the laminate 1, the substrate 11 is, for example, a polyolefin film. In this embodiment, the substrate 11 may include a polypropylene film or may be made of a polypropylene film. The polypropylene film may be an acid-modified polypropylene film obtained by graft-modifying polypropylene with an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like. Furthermore, as the polypropylene, polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer can be used.

[0026] The polypropylene film constituting the substrate 11 may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent.

[0027] The polypropylene film constituting the substrate 11 may be a stretched film or a non-stretched film. From the viewpoints of impact resistance, heat resistance, water resistance, dimensional stability, etc., the polypropylene film may be a stretched polypropylene film. This can prevent the substrate 11 from being thermally fused during the heat sealing process during bag production. The laminate 1 may also be used in applications where heat treatment such as retort treatment or boiling treatment is performed. The stretching method is not particularly limited, and any method may be used as long as it can provide a dimensionally stable film, such as inflation stretching, uniaxial stretching, or biaxial stretching.

[0028] The substrate 11 may be subjected to various pretreatments such as corona treatment, plasma treatment, and flame treatment, or may be provided with a coating layer such as an easy-adhesion layer, as long as the pretreatment does not impair the barrier performance. The pretreatment surface may be the surface that forms the first main surface 10b of the barrier layer 10.

[0029] [Heat Shrinkage of Substrate 11] After the substrate 11 is exposed to 120°C for 15 minutes (hereinafter simply referred to as "after heating"), the heat shrinkage of the substrate 11 in the MD direction calculated by the following formula (1) is 1% or more. For example, after the substrate 11 or the barrier layer 10 including the substrate 11 is heated in an oven at 120°C for 15 minutes, the heat shrinkage of the substrate 11 in the MD direction calculated by the following formula (1) is 1% or more. From the viewpoints of reducing deformation during bag formation and suppressing peeling between the barrier layer 10 and the sealant layer 20, the heat shrinkage in the MD direction is, for example, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, etc. In one example, the heat shrinkage in the MD direction is 1.2% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, etc. The heat shrinkage rate in the MD direction is, for example, 1% to 7%, 1% to 6.7%, 1.5% to 4%, or 2% to 3.7%. For example, a biaxially oriented polypropylene film has a heat shrinkage rate of 1%, while a PET film has a heat shrinkage rate of less than 1%. Heat shrinkage rate in the MD direction (%) = (MD length before heating - MD length after heating) / MD length before heating × 100 ... (1)

[0030] After the heating, the heat shrinkage rate in the TD direction of the substrate 11 calculated by the following formula (2) is not particularly limited, but is, for example, 1% or more and less than the heat shrinkage rate in the MD direction of the substrate 11. From the viewpoints of reducing deformation during bag formation and suppressing peeling between the barrier layer 10 and the sealant layer 20, the heat shrinkage rate in the TD direction is, for example, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, etc. In one example, the heat shrinkage rate in the TD direction is 1.2% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, etc. The heat shrinkage rate in the TD direction is, for example, 1% or more and 7% or less, 1% or more and 6.7% or less, 1.5% or more and 4% or less, 2% or more and 3.7% or less, etc. Heat shrinkage rate in the TD direction (%) = (TD length before heating - TD length after heating) / TD length before heating × 100 ... (2)

[0031] Generally, in a stretched film such as a biaxially stretched film, the heat shrinkage in the MD direction is greater than the heat shrinkage in the TD direction.

[0032] [Adhesion Layer] The adhesion layer 12 functions as a layer (anchor coat layer) that can improve the adhesion performance of the vapor-deposited layer 13 on the substrate 11, and is provided directly on the substrate 11. Therefore, the adhesion layer 12 is located between the substrate 11 and the vapor-deposited layer 13. By providing the adhesion layer 12, the smoothness of the surface of the barrier layer 10 on which the vapor-deposited layer 13 is provided can be improved. Note that improved smoothness makes it easier to form the vapor-deposited layer 13 uniformly without defects, and makes it easier to exhibit high barrier properties. The adhesion layer 12 can be formed using, for example, an anchor coat agent.

[0033] Examples of the anchor coating agent include polyester-based polyurethane resins, polyether-based polyurethane resins, etc. As the anchor coating agent, polyester-based polyurethane resins may be used from the viewpoints of heat resistance and interlayer adhesive strength.

[0034] The thickness of the adhesive layer 12 is not particularly limited, and may be in the range of 0.01 to 5 μm, 0.03 to 3 μm, or 0.05 to 2 μm. When the thickness of the adhesive layer 12 is equal to or greater than the lower limit, more sufficient interlayer adhesive strength tends to be obtained, while when the thickness is equal to or less than the upper limit, desired gas barrier properties tend to be easily exhibited.

[0035] The method for applying the adhesive layer 12 onto the substrate 11 can be any known application method without any particular limitation, and examples thereof include a dipping method, a spray method, a method using a coater, a printing machine, a brush, etc. In addition, examples of the types of coaters and printing machines used in these methods and the application methods thereof include gravure coaters such as direct gravure, reverse gravure, kiss reverse gravure, and offset gravure, reverse roll coaters, microgravure coaters, coaters with chamber doctor, air knife coaters, dip coaters, bar coaters, comma coaters, and die coaters.

[0036] The amount of the adhesive layer 12 applied is 1 m after the anchor coating agent is applied and dried. ２ Mass per unit is 0.01 to 5 g / m ２ or 0.03 to 3 g / m ２After applying and drying the anchor coating agent, ２ When the mass per unit area is equal to or greater than the lower limit, film formation tends to be sufficient, whereas when the mass per unit area is equal to or less than the upper limit, the film tends to be sufficiently dried and the solvent tends not to remain.

[0037] The method for drying the adhesion layer 12 is not particularly limited, but examples thereof include a method of natural drying, a method of drying in an oven set at a predetermined temperature, and a method using a dryer attached to the coater, such as an arch dryer, a floating dryer, a drum dryer, an infrared dryer, etc. Furthermore, the drying conditions can be appropriately selected depending on the drying method, and for example, in a method of drying in an oven, drying may be performed at a temperature of 60 to 100°C for about 1 second to 2 minutes.

[0038] A polyvinyl alcohol resin can be used instead of the polyurethane resin for the adhesion layer 12. The polyvinyl alcohol resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit, and examples thereof include polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH).

[0039] Examples of PVA include resins obtained by homopolymerizing vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate, followed by saponification. The PVA may also be a modified PVA that has been copolymerized or post-modified. The modified PVA can be obtained, for example, by copolymerizing a vinyl ester with an unsaturated monomer copolymerizable with the vinyl ester, followed by saponification. Examples of unsaturated monomers copolymerizable with vinyl esters include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-pentyn-1-ol, and 5-hexen-1-ol; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and undecylenic acid; nitriles such as acrylonitrile and methacrylonitrile; diacetone acrylamide, acrylic acid, and the like. olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid; vinyl compounds such as alkyl vinyl ethers, dimethyl allyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxane, glycerin monoallyl ether, and 3,4-diacetoxy-1-butene; vinylidene chloride, 1,4-diacetoxy-2-butene, and vinylene carbonate.

[0040] The degree of polymerization of PVA is, for example, 300 to 3000. If the degree of polymerization is less than 300, the barrier properties tend to decrease, and if it exceeds 3000, the viscosity becomes too high and the coatability tends to decrease. The saponification degree of PVA may be 90 mol% or more, 95 mol% or more, or 99 mol% or more. The saponification degree of PVA may be 100 mol% or less, or 99.9 mol% or less. The polymerization degree and saponification degree of PVA can be measured in accordance with the method described in JIS K 6726 (1994).

[0041] EVOH is generally obtained by saponifying a copolymer of ethylene and a vinyl ester such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, or vinyl versatate.

[0042] The degree of polymerization of EVOH is, for example, 300 to 3000. If the degree of polymerization is less than 300, the barrier properties tend to decrease, while if it exceeds 3000, the viscosity becomes too high and the coatability tends to decrease. The degree of saponification of the vinyl ester component of EVOH may be 90 mol% or more, 95 mol% or more, or 99 mol% or more. The degree of saponification of EVOH may be 100 mol% or less, or 99.9 mol% or less. The degree of saponification of EVOH is determined by nuclear magnetic resonance (1H-NMR) measurement, from the peak area of ​​hydrogen atoms contained in the vinyl ester structure and the peak area of ​​hydrogen atoms contained in the vinyl alcohol structure.

[0043] The ethylene unit content of EVOH is 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and particularly preferably 25 mol% or more. The ethylene unit content of EVOH is preferably 65 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. When the ethylene unit content is 10 mol% or more, good gas barrier properties or dimensional stability can be maintained under high humidity conditions. On the other hand, when the ethylene unit content is 65 mol% or less, good gas barrier properties can be achieved. The ethylene unit content of EVOH can be determined by NMR.

[0044] When a polyvinyl alcohol resin is used as the adhesive layer 12, the adhesive layer 12 can be formed by coating a polyvinyl alcohol resin solution, multi-layer extrusion, or the like.

[0045] [Vapor-Deposited Layer 13] The vapor-deposited layer 13 is a layer (gas barrier layer) that exhibits gas barrier properties against water vapor and oxygen and contains at least one of a metal and an inorganic oxide. The vapor-deposited layer 13 is provided directly on the adhesive layer 12. The vapor-deposited layer 13 may have a single-layer structure or a laminated structure. Therefore, the vapor-deposited layer 13 contains at least one of a metal vapor-deposited layer and an inorganic oxide layer. When the vapor-deposited layer 13 includes a metal vapor-deposited layer, examples of the metal contained in the metal vapor-deposited layer include aluminum and stainless steel. When the vapor-deposited layer 13 includes an inorganic oxide layer, examples of the inorganic oxide contained in the inorganic oxide layer include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoints of transparency and barrier properties, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. Furthermore, from the viewpoint of excellent tensile stretchability during processing, the inorganic oxide layer may contain a layer using silicon oxide. By using an inorganic oxide layer, high barrier properties can be obtained with a very thin layer that does not affect the recyclability of the laminate 1.

[0046] When the vapor-deposited layer 13 is an inorganic oxide layer using silicon oxide, the O / Si ratio of the inorganic oxide layer is desirably 1.7 or more. An O / Si ratio of 1.7 or more suppresses the content of metallic Si, making it easier to achieve good transparency. Furthermore, the O / Si ratio is preferably 2.0 or less. An O / Si ratio of 2.0 or less increases the crystallinity of SiO, preventing the inorganic oxide layer from becoming too hard and providing good tensile strength. This prevents cracks from occurring in the inorganic oxide layer when the barrier coat 14 is laminated. Even after forming into a packaging bag, the substrate 11 may shrink due to heat during boiling or retort treatment. However, an O / Si ratio of 2.0 or less allows the inorganic oxide layer to easily adapt to this shrinkage, thereby preventing a decrease in barrier properties. To more fully achieve these effects, the O / Si ratio of the inorganic oxide layer is preferably 1.75 to 1.9, more preferably 1.8 to 1.85.

[0047] When the vapor-deposited layer 13 is an inorganic oxide layer using silicon oxide, the O / Si ratio of the inorganic oxide layer can be determined by X-ray photoelectron spectroscopy (XPS). For example, the measurement can be performed using an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., product name: JPS-90MXV) with a non-monochromated MgKα (1253.6 eV) X-ray source and an X-ray output of 100 W (10 kV-10 mA). For quantitative analysis to determine the O / Si ratio, relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used.

[0048] The thickness of the vapor-deposited layer 13 is, for example, 5 nm or more and 80 nm or less. When the thickness of the vapor-deposited layer 13 is 5 nm or more, sufficient water vapor barrier properties can be obtained. Furthermore, when the thickness of the vapor-deposited layer 13 is 80 nm or less, the occurrence of cracks due to deformation caused by internal stress in the thin film can be suppressed, and a decrease in water vapor barrier properties can be suppressed. Note that a thickness of the vapor-deposited layer 13 exceeding 80 nm is undesirable from an economic standpoint, as costs tend to increase due to an increase in the amount of material used and a longer film formation time. From the same viewpoint as above, the thickness of the vapor-deposited layer 13 may be 20 nm or more and 40 nm or less.

[0049] The deposition layer 13 can be formed by, for example, vacuum film formation. In vacuum film formation, physical vapor deposition or chemical vapor deposition can be used. Examples of physical vapor deposition include, but are not limited to, vacuum deposition, sputtering, and ion plating. Examples of chemical vapor deposition include, but are not limited to, thermal CVD, plasma CVD, and photo CVD.

[0050] In the vacuum film formation, resistance heating vacuum deposition, EB (Electron Beam) heating vacuum deposition, induction heating vacuum deposition, sputtering, reactive sputtering, dual magnetron sputtering, plasma enhanced chemical vapor deposition (PECVD), and the like are particularly preferably used. However, in terms of productivity, vacuum deposition is currently the most superior. As a heating means for vacuum deposition, any of electron beam heating, resistance heating, and induction heating may be used.

[0051] [Barrier Coat 14] The barrier coat 14 is a coating layer having gas barrier properties (gas barrier coating layer) and is provided on the substrate 11. The barrier coat 14 is a layer formed using a composition for forming a gas barrier coating layer (hereinafter also referred to as a coating agent) containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and hydrolysates thereof, for example.

[0052] From the viewpoint of more adequately maintaining gas barrier properties after hot water treatment such as retort treatment, the coating agent preferably contains at least a silane coupling agent or a hydrolyzate thereof, more preferably contains at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, and their hydrolyzates, and a silane coupling agent or a hydrolyzate thereof, and even more preferably contains a hydroxyl group-containing polymer compound or a hydrolyzate thereof, a metal alkoxide or a hydrolyzate thereof, and a silane coupling agent or a hydrolyzate thereof. The coating agent can be prepared, for example, by mixing a metal alkoxide and a silane coupling agent directly, or after having been previously treated by hydrolysis, with a solution obtained by dissolving a hydroxyl group-containing polymer compound, which is a water-soluble polymer, in an aqueous solvent (water or a water / alcohol mixture).

[0053] The following describes in detail each component contained in the coating agent for forming the barrier coat 14. Examples of hydroxyl group-containing polymer compounds used in the coating agent include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate. Among these, polyvinyl alcohol (PVA) is preferred when used in the coating agent for the barrier coat 14 because it has particularly excellent gas barrier properties.

[0054] From the viewpoint of obtaining excellent gas barrier properties, the barrier coat 14 is preferably formed from a composition containing at least one selected from the group consisting of metal alkoxides represented by the following general formula (I) and hydrolysates thereof: M(OR １ ) ｍ (R２ ) ｎ－ｍ ...(I) In the above general formula (I), R １ and R ２ are each independently a monovalent organic group having 1 to 8 carbon atoms, and are preferably 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 or R ２ If there are multiple １ Comrades or R ２ They may be the same or different.

[0055] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC ２ H ５ ) ４ ], triisopropoxyaluminum [Al(O-2'-C ３ H ７ ) ３ Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

[0056] Examples of the silane coupling agent include compounds represented by the following general formula (II): Si(OR １１ ) ｐ (R １２ ) ３－ｐ R １３ ... (II) In the above general formula (II), R １１ represents an alkyl group such as a methyl group or an ethyl group, and R １２ 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 １３ represents a monovalent organic functional group, and p represents an integer of 1 to 3. １１ or R １２ If there are multiple １１ Comrades or R １２ R may be the same or different. １３Examples 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.

[0057] Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0058] The silane coupling agent may also be a polymer formed by polymerization of the compound represented by the general formula (II). A trimer is preferred as the polymer, and 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate is more preferred. This is a condensation polymer of 3-isocyanatoalkylalkoxysilane. It is known that 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate loses chemical reactivity in the isocyanate moiety, but the reactivity is ensured by the polarity of the nurate moiety. It is generally added to adhesives, similar to 3-isocyanatoalkylalkoxysilane, and is known as an adhesion improver. Therefore, adding 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate to a hydroxyl group-containing polymer compound can improve the water resistance of a gas barrier coating layer through hydrogen bonding. While 3-isocyanate alkyl alkoxysilanes have high reactivity and low liquid stability, 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurates are not water-soluble due to the polarity of the nurate moiety, but are easily dispersed in aqueous solutions and can maintain stable liquid viscosity. Furthermore, the water resistance of 3-isocyanate alkyl alkoxysilanes and 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurates is equivalent.

[0059] Some 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurates are produced by thermal condensation of 3-isocyanatepropylalkoxysilane, and may contain the raw material 3-isocyanatepropylalkoxysilane, but this does not pose any particular problems. 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate is more preferred, and 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is even more preferred. 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is practically advantageous because the methoxy group has a fast hydrolysis rate and those containing a propyl group are available relatively inexpensively.

[0060] Furthermore, known additives such as an isocyanate compound, a dispersant, a stabilizer, a viscosity adjuster, and a colorant can be added to the coating agent as needed, provided that the gas barrier properties are not impaired.

[0061] The thickness of the barrier coat 14 may be 50 to 1000 nm, or 100 to 500 nm. If the thickness of the barrier coat 14 is 50 nm or more, more sufficient gas barrier properties tend to be obtained, and if it is 1000 nm or less, sufficient flexibility tends to be maintained.

[0062] The coating liquid for forming the barrier coat 14 can be applied by, for example, dipping, roll coating, gravure coating, reverse gravure coating, air knife coating, comma coating, die coating, screen printing, spray coating, gravure offset, etc. The coating film obtained by applying this coating liquid can be dried by, for example, hot air drying, hot roll drying, high frequency irradiation, infrared irradiation, UV irradiation, or a combination thereof.

[0063] The temperature at which the coating film is dried may be, for example, 50 to 150° C. or 70 to 100° C. By setting the drying temperature within the above range, the occurrence of cracks in the vapor deposition layer 13 and the barrier coat 14 can be further suppressed, and excellent barrier properties can be exhibited.

[0064] The barrier coat 14 may be formed using a coating agent containing a polyvinyl alcohol resin and a silane compound. If necessary, an acid catalyst, an alkali catalyst, a photopolymerization initiator, etc. may be added to the coating agent.

[0065] The polyvinyl alcohol resin is as described above. Examples of the silane compound include a silane coupling agent, polysilazane, and siloxane, and specific examples thereof include tetramethoxysilane, tetraethoxysilane, glycidoxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, and hexamethyldisilazane.

[0066] [Printed Layer] The laminate 1 may include a printed layer. The printed layer can be provided, for example, on at least one surface of the substrate 11. The printed layer is provided in a position visible from the outside of the laminate 1 for the purpose of displaying information about the contents, identifying the contents, improving concealment, or improving the design of the packaging bag. The printing method and printing ink are not particularly limited, and are appropriately selected from known printing methods and printing inks taking into consideration printability on the film, design such as color tone, adhesion, safety as a food container, and the like. 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 resolution of the image.

[0067] To improve the adhesion of the printed layer, the surface of the layer on which the printed layer is to be formed may be subjected to various pretreatments such as corona treatment, plasma treatment, and flame treatment, or a coating layer such as an easy-adhesion layer may be formed.

[0068] [Sealant layer 20] The sealant layer 20 is a layer that provides heat-sealing properties to the laminate 1, and overlaps the first main surface 10b of the barrier layer 10. From the viewpoint of the recyclability of the laminate 1, the sealant layer 20 is a polyolefin film, similar to the substrate 11. In this embodiment, the sealant layer 20 has a single-layer structure and is a resin layer containing polypropylene as the main material, but is not limited to this. The sealant layer 20 may have a laminate structure. The sealant layer 20 may include a polypropylene film or may be made of a polypropylene film.

[0069] The polypropylene film may be an acid-modified polypropylene film obtained by graft-modifying polypropylene with an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like. Furthermore, polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer (random PP), propylene-ethylene block copolymer (block PP), and propylene-α-olefin copolymer can be used as the polypropylene. For example, when the sealant layer 20 has a laminated structure, the sealant layer 20 has at least one of a layer containing a homopropylene resin, a layer containing random PP, a layer containing block PP, and a layer containing a propylene-α-olefin copolymer. From the viewpoint of the shape stability of the sealant layer 20, a layer containing block PP may be used as an intermediate layer of the sealant layer 20. In this case, an elastomer may be added to the intermediate layer. From the viewpoint of the elastic modulus of the sealant layer 20 described below, the amount of elastomer added is, for example, 10% by mass or more and 30% by mass or less. From the viewpoint of the sealing function of the sealant layer 20 , a layer containing random PP may constitute the front and back surfaces of the sealant layer 20 .

[0070] The polypropylene film constituting the sealant layer 20 may be a non-oriented polypropylene film from the viewpoint of improving the sealing property by heat sealing.

[0071] The polypropylene film constituting the sealant layer 20 may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent.

[0072] The thickness of the sealant layer 20 is determined depending on the mass of the contents, the shape of the packaging bag, etc., but may be approximately 30 to 150 μm, or may be 50 to 80 μm.

[0073] From the viewpoint of the openability of a packaging bag or the like when the laminate 1 is used to form the packaging bag, the elastic modulus of the sealant layer is, for example, 600 MPa or more, 700 MPa or more, 850 MPa or more, etc. The elastic modulus of the sealant layer 20 along the MD direction of the substrate 11 and the elastic modulus of the sealant layer 20 along the TD direction of the substrate 11 are each, for example, 600 MPa or more. In one example, the elastic modulus of the sealant layer 20 along the MD direction of the substrate 11 is 850 MPa or more, and the elastic modulus of the sealant layer 20 along the TD direction of the substrate 11 is 700 MPa or more. From the viewpoint of the adhesion between the sealant layers 20, the elastic modulus of the sealant layer is, for example, 1400 MPa or less, 1100 MPa or less, 1000 MPa or less, etc. The elastic modulus of the sealant layer 20 along the MD direction of the substrate 11 is 1100 MPa or less, and the elastic modulus of the sealant layer 20 along the TD direction of the substrate 11 is 1000 MPa or less. In one example, the elastic modulus of the sealant layer is 600 MPa or more and 1400 MPa or less. In this embodiment, the elastic modulus of the sealant layer 20 is calculated from the stress measured when a 20 mm square sample of the sealant layer 20 is stretched by 0.05% to 0.25% under conditions of a gauge length of 250 mm and a tensile speed of 5 m / min. The openability of the packaging bag corresponds to the ease with which the bag can be opened. Good openability of the packaging bag reduces the likelihood of failure when filling the contents into the packaging bag.

[0074] The sealant layer 20 can be formed by any of the known lamination methods, such as a dry lamination method in which a film-like sealant layer made of the above-mentioned polypropylene is bonded with an adhesive such as a one-component curing or two-component curing urethane adhesive, a non-solvent dry lamination method in which a film-like sealant layer is bonded with a solvent-free adhesive, and an extrusion lamination method in which the above-mentioned polypropylene is heated and melted, extruded into a curtain shape, and bonded together.

[0075] Among the above-mentioned forming methods, the dry lamination method is preferred because it has high resistance to retort treatment, particularly high-temperature hot water treatment at 120° C. or higher. On the other hand, if the packaging bag is used for an application in which it will be treated at a temperature of 85° C. or lower, the lamination method is not particularly limited.

[0076] [First Adhesive Layer 30] The first adhesive layer 30 is a layered member that bonds the barrier layer 10 and the sealant layer 20. Examples of materials that can be used for the adhesive contained in the first adhesive layer 30 include polyester-isocyanate resins, urethane resins, and polyether resins. Considering the use of the packaging bag in retort pouch applications, the first adhesive layer 30 may be made of a retort-resistant urethane resin (e.g., a two-component curing urethane adhesive). From an environmental perspective, the adhesive may not contain 3-glycidyloxypropyltrimethoxysilane (GPTMS). The first adhesive layer 30 may not contain chlorine. In this case, the adhesive forming the first adhesive layer 30 can suppress discoloration of recycled resins and odors due to heat treatment after recycling. From an environmental perspective, the first adhesive layer 30 may be made of a biomass material and may not contain a solvent.

[0077] When a two-component curing urethane adhesive is used as the first adhesive layer 30, the urethane adhesive is formed from a base agent and a curing agent. Examples of the base agent include polyester polyol and polyester polyurethane polyol. Polyester polyol is obtained, for example, by polymerizing a diol and a dicarboxylic acid. Polyester polyurethane polyol is obtained, for example, by polymerizing a diol, a dicarboxylic acid, and a diisocyanate. Examples of diols include ethylene glycol, neopentyl glycol, 1,6-hexanediol, and 2,4-hexylene glycol. Examples of dicarboxylic acids include adipic acid, sebacic acid, isophthalic acid, and terephthalic acid. Examples of diisocyanates include isophorone diisocyanate (hereinafter referred to as IPDI). Examples of the curing agent include an adduct of IPDI with trimethylolpropane (hereinafter referred to as TMP), a TMP adduct of xylylene diisocyanate (hereinafter referred to as XDI), a mixture of a TMP adduct of IPDI and a TMP adduct of XDI, a biuret of hexamethylene diisocyanate (hereinafter referred to as HDI), etc. The weight average molecular weight (Mw) of the urethane adhesive is not particularly limited, but is, for example, about 10,000 to 50,000.

[0078] The thickness of the first adhesive layer 30 is 0.5 μm or more and 10 μm or less. When the thickness of the first adhesive layer 30 is 0.5 μm or more, peeling between the barrier layer 10 and the sealant layer 20 can be effectively suppressed. When the thickness of the first adhesive layer 30 is 10 μm or less, the laminate 1 can be easily made into a mono-material (details will be described later). The thickness of the first adhesive layer 30 may be 1 μm or more, 2 μm or more, 8 μm or less, 6 μm or less, or 5 μm or less.

[0079] [Elastic Modulus of First Adhesive Layer 30] In the present embodiment, after the retort treatment is performed on the laminate 1, the elastic modulus of the first adhesive layer 30 is 5 MPa or more and less than 53 MPa. In this case, the first adhesive layer 30 can well follow the expansion and contraction of the substrate 11 that accompanies a heat treatment such as a retort treatment or a boiling treatment. Therefore, even if the heat treatment is performed on a laminate 1 including a substrate 11 having the above-described thermal shrinkage rate, peeling between the barrier layer 10 and the sealant layer 20 is unlikely to occur. In addition, cracking of the first adhesive layer 30 during cooling after the heat treatment and damage to the barrier layer 10 (at least one of the adhesion layer 12, the vapor deposition layer 13, and the barrier coat 14) that accompanies the cracking are suppressed. The elastic modulus of the first adhesive layer 30 after the retort treatment may be, for example, 9 MPa or more, 15 MPa or more, 20 MPa or more, 50 MPa or less, 47 MPa or less, or 42 MPa or less. The elastic modulus of the first adhesive layer 30 before the retort treatment of the laminate 1 is not particularly limited, but is, for example, 55 MPa or more or 60 MPa or more.

[0080] The elastic modulus of the first adhesive layer 30 in the laminate 1 can be obtained, for example, by measuring the elastic modulus of a cross section of the portion (exposed portion) exposed from the sealant layer 20. The elastic modulus of the cross section can be obtained, for example, by measurement using a scanning probe microscope (SPM). In this case, the elastic modulus of the first adhesive layer 30 represents the elastic modulus calculated from a force curve measured using a scanning probe microscope (SPM). The elastic modulus of the first adhesive layer 30 can be obtained, for example, by the method described in the following examples. The elastic modulus of a first adhesive layer 30 that has not been subjected to retort treatment can also be obtained by the method described in the following examples.

[0081] The hardness of the adhesive layer can be controlled by the adhesive material, the amount of curing agent, the aging time, etc. The narrower the distance between the molecular chains of the adhesive, the harder the adhesive layer tends to be. The bulkier the adhesive, the softer the adhesive layer tends to be. The hardness of an aliphatic adhesive layer tends to be softer than that of an alicyclic or aromatic adhesive layer. The hardness of an alicyclic adhesive layer tends to be harder than that of an aromatic adhesive layer. The greater the amount of curing agent contained in the adhesive layer, the harder the adhesive layer tends to be. The longer the aging time, the harder the adhesive layer tends to be. The harder the adhesive layer, the higher the elastic modulus of the adhesive layer.

[0082] [Support Layer 40] The support layer 40 is a sheet-like plastic member that functions as a support for the laminate 1. The support layer 40 may have the same function and performance as the substrate 11. The thickness of the support layer 40 may be approximately the same as the thickness of the substrate 11. From the viewpoint of the recyclability of the laminate 1, the support layer 40 is, for example, a polyolefin film. From the viewpoint of heat resistance, the support layer 40 may include or be made of a polypropylene film. The polypropylene film constituting the support layer 40 may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent. The polypropylene film constituting the support layer 40 may be a stretched film or a non-stretched film.

[0083] In this embodiment, after the support layer 40 is exposed to 120°C for 15 minutes, the heat shrinkage rate in the MD direction of the support layer 40 calculated by the above formula (1) is 1% or more. For example, after the support layer 40 or a laminate of the support layer 40 and the barrier layer 10 is heated in an oven at 120°C for 15 minutes, the heat shrinkage rate in the MD direction of the support layer 40 calculated by the above formula (1) is 1% or more. The heat shrinkage rate in the MD direction is, for example, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, or 7% or less. In one example, the heat shrinkage rate in the MD direction is 1.2% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, etc. The heat shrinkage rate in the MD direction is, for example, 1% or more to 7% or less, 1% or more to 6.7% or less, 1.5% or more to 4% or less, or 2% or more to 3.7% or less.

[0084] After the heating, the thermal shrinkage rate of the support layer 40 in the TD direction calculated by the formula (2) is not particularly limited, but is, for example, 1% to 12%. In one example, the thermal shrinkage rate in the TD direction is 1.2% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, etc. The thermal shrinkage rate in the TD direction is, for example, 1% to 7%, 1% to 6.7%, 1.5% to 4%, or 2% to 3.7%.

[0085] [Second adhesive layer 50] The second adhesive layer 50 is a layer member that bonds the barrier layer 10 and the support layer 40. The material of the adhesive contained in the second adhesive layer 50 is the same as the material of the adhesive contained in the first adhesive layer 30. From the viewpoint of using the packaging bag for retort purposes, a retort-resistant urethane resin (for example, a two-component curing urethane adhesive) may be used as the second adhesive layer 50. The thickness of the second adhesive layer 50 is the same as the thickness of the first adhesive layer 30, and is 0.5 μm or more and 10 μm or less.

[0086] [Elastic Modulus of Second Adhesive Layer 50] In this embodiment, after the retort treatment is performed on the laminate 1, the elastic modulus of the second adhesive layer 50 is 5 MPa or more and less than 53 MPa. In this case, the second adhesive layer 50 can well follow the expansion and contraction of the substrate 11 and the support layer 40 that accompany heat treatments such as retort treatment and boiling treatment. Therefore, even if the heat treatment is performed on the laminate 1 including the substrate 11 and the support layer 40 having the above-mentioned thermal shrinkage rate, peeling between the barrier layer 10 and the support layer 40 is unlikely to occur. In addition, cracking of the second adhesive layer 50 during cooling after the heat treatment, etc., and damage to the barrier layer 10 (at least one of the adhesion layer 12, the vapor deposition layer 13, and the barrier coat 14) that accompanies the cracking are suppressed. The elastic modulus of the second adhesive layer 50 after retort treatment may be, for example, 9 MPa or more, 15 MPa or more, 20 MPa or more, 50 MPa or less, 47 MPa or less, or 42 MPa or less. The elastic modulus of the second adhesive layer 50 before retort treatment is not particularly limited, but is, for example, 55 MPa or more or 60 MPa or more. The elastic modulus of the second adhesive layer 50 before retort treatment can also be obtained by the method described in the following examples.

[0087] The hardness of the adhesive layer can be controlled by the adhesive material, the amount of curing agent, the aging time, etc. The narrower the distance between the molecular chains of the adhesive, the harder the adhesive layer tends to be. The bulkier the adhesive, the softer the adhesive layer tends to be. The hardness of an aliphatic adhesive layer tends to be softer than that of an alicyclic or aromatic adhesive layer. The hardness of an alicyclic adhesive layer tends to be harder than that of an aromatic adhesive layer. The greater the amount of curing agent contained in the adhesive layer, the harder the adhesive layer tends to be. The longer the aging time, the harder the adhesive layer tends to be. The harder the adhesive layer, the higher the elastic modulus of the adhesive layer.

[0088] [Polyolefin Content] The total mass ratio of polyolefin (in this embodiment, polypropylene) in the laminate 1 is 90 mass% or more. As a result, the laminate 1 can be said to be a packaging material made of a single material (monomaterial), and has excellent recyclability. From the viewpoint of further improving recyclability, the polyolefin content in the laminate 1 may be 92.5 mass% or more, or may be 95 mass% or more, based on the total amount of the laminate 1.

[0089] <Packaging Bag> An example of a packaging bag, which is a bag product made from the laminate 1, will be described below with reference to Fig. 3. Fig. 3 is a schematic plan view of an example of a packaging bag. The packaging bag 100 shown in Fig. 3 is formed into a bag shape by, for example, folding the laminate 1 in half so as to sandwich the contents therebetween and sealing the ends.

[0090] The packaging bag 100 is a three-sided bag having a main body 101 for accommodating the contents, a sealed portion 102 located at an end of the main body 101, and a folded portion 103 formed by folding the laminate 1. The shape of the main body 101 is not particularly limited and may be, for example, rectangular when viewed from a predetermined direction. At least a portion of the outer surface of the main body 101 may be printed. The main body 101 may contain, for example, a specific gas such as nitrogen in addition to the contents. The sealed portion 102 is a portion where one portion of the sealant layer 20 of the laminate 1 is bonded to another portion. In the sealed portion 102, the one portion of the sealant layer 20 of the laminate 1 is in close contact with the other portion. The sealed portion 102 is formed, for example, by heating and compressing (i.e., heat-sealing) the one portion of the sealant layer 20 of the laminate 1 to the other portion, but is not limited thereto. For example, the sealed portion 102 may be formed by cold sealing or the like. In the packaging bag 100, the folded portion 103 forms one side of the main body portion 101, and the sealed portion 102 forms the remaining three sides of the main body portion 101. Both ends of the folded portion 103 and the sealed portion 102 overlap with each other.

[0091] After the laminate 1 according to the present embodiment described above is subjected to retort treatment, the elastic modulus of the first adhesive layer 30 measured with a scanning probe microscope (SPM) is 5 MPa or more and less than 53 MPa. This allows the first adhesive layer 30 to follow suit even if the substrate 11 expands or contracts due to the retort treatment. Therefore, even if the laminate 1 includes a substrate 11 with a thermal shrinkage rate of 1% or more in the MD direction, damage to the barrier coat 14 due to cracks occurring in the first adhesive layer 30 can be suppressed. Therefore, it is possible to provide a laminate 1 that can exhibit good gas barrier properties (particularly oxygen permeation prevention performance) even after retort treatment.

[0092] In this embodiment, the second adhesive layer 50 contains a two-component curing urethane adhesive, and after the laminate 1 is subjected to retort treatment, the modulus of elasticity of the second adhesive layer 50 measured with a scanning probe microscope is 5 MPa or more and less than 53 MPa. In this case, even if the substrate 11 and the support layer 40 expand and contract due to the retort treatment, not only the first adhesive layer 30 but also the second adhesive layer 50 will follow suit well. Therefore, damage to the barrier coat 14 due to cracks occurring in the second adhesive layer 50 can also be suppressed.

[0093] In this embodiment, the barrier layer 10 has an adhesion layer 12 and a vapor deposition layer 13 located between the substrate 11 and the barrier coat 14, and the adhesion layer 12 is located between the substrate 11 and the vapor deposition layer 13. Therefore, the gas barrier properties of the laminate 1 can be improved compared to when the barrier layer has only the substrate 11 and the barrier coat 14.

[0094] In this embodiment, the thickness of the vapor-deposited layer 13 may be 5 nm or more and 80 nm or less. In this case, cracking of the vapor-deposited layer 13 can be prevented and the gas barrier properties can be improved.

[0095] In this embodiment, the thickness of the first adhesive layer 30 may be 0.5 μm or more and 10 μm or less. In this case, peeling between the barrier layer 10 and the sealant layer 20 can be effectively suppressed, and the laminate 1 can be easily made into a mono-material.

[0096] In this embodiment, the substrate 11 and the sealant layer 20 are each a polyolefin film, and the total mass ratio of polyolefin in the laminate 1 may be 90 mass % or more. In this case, a mono-material structure is realized.

[0097] In this embodiment, the substrate 11 may be a stretched polypropylene film, and the sealant layer 20 may be a non-stretched polypropylene film. In this case, the laminate 1 has excellent heat resistance against retort treatment and the like.

[0098] A gas barrier laminate and a packaging bag therefor according to one aspect of the present disclosure are as described in the following [1] to

[10] , and have been described in detail based on the above-mentioned embodiments and modified examples. [1] A gas barrier laminate comprising: a barrier layer having a substrate on which a barrier coat is provided, a sealant layer overlying a first main surface of the barrier layer, a support layer overlying a second main surface of the barrier layer, a first adhesive layer bonding the barrier layer and the sealant layer together, and a second adhesive layer bonding the barrier layer and the support layer together, wherein the first adhesive layer comprises a two-component curing urethane adhesive, the substrate comprises a polyolefin, and the modulus of elasticity of the first adhesive layer measured by a scanning probe microscope after retorting the gas barrier laminate is 5 MPa or more and less than 53 MPa. [2] The gas barrier laminate according to [1], wherein the second adhesive layer contains a two-component curing urethane adhesive, and wherein the elastic modulus of the second adhesive layer measured with a scanning probe microscope after the retort treatment is 5 MPa or more and less than 53 MPa. [3] The gas barrier laminate according to [1] or [2], wherein the barrier layer further includes an anchor coat layer and a vapor deposition layer located between the substrate and the barrier coat, and the anchor coat layer is located between the substrate and the vapor deposition layer. [4] The gas barrier laminate according to [3], wherein the vapor deposition layer has a thickness of 5 nm or more and 80 nm or less. [5] The gas barrier laminate according to any one of [1] to [4], wherein the elastic modulus of the first adhesive layer measured with a scanning probe microscope before the retort treatment is 55 MPa or more. [6] The gas barrier laminate according to any one of [1] to [5], wherein the thickness of the first adhesive layer and the thickness of the second adhesive layer are each 0.5 μm or more and 10 μm or less. [7] The gas barrier laminate according to any one of [1] to [6], wherein the elastic modulus of the sealant layer is 600 MPa or more and 1400 MPa or less. [8] The gas barrier laminate according to any one of [1] to [7], wherein the base material and the sealant layer are each a polyolefin film, and the proportion by mass of the total polyolefin in the gas barrier laminate is 90 mass% or more.[9] The gas barrier laminate according to [8], wherein the substrate is a stretched polypropylene film, and the sealant layer is a non-stretched polypropylene film.

[10] A packaging bag made from the gas barrier laminate according to any one of [1] to [9].

[0099] However, one aspect of the present disclosure is not limited to the above-described embodiment, the above-described modified example, and the above-described items [1] to

[10] . One aspect of the present disclosure can be further modified within the scope of the gist thereof.

[0100] In the above embodiment and the above modification, the total mass ratio of polypropylene in the laminate may be 90 mass% or more. Therefore, for example, in the laminate according to the modification, the mass ratio of polypropylene in one of the substrate and the support layer may be less than 90 mass%. Alternatively, in the laminate, the mass ratio of polypropylene in the barrier layer may be less than 90 mass%.

[0101] In the above embodiment and modified example, an anchor coat layer and a vapor deposition layer are provided on the substrate, but this is not limited thereto. For example, a vapor deposition layer may be provided on the sealant layer. In this case, the anchor coat layer may be provided between the sealant layer and the vapor deposition layer. In this case, the sealant layer and the anchor coat layer may be co-extruded layers. Alternatively, an anchor coat layer and a vapor deposition layer may be included on the substrate, and a vapor deposition layer may be provided on the sealant layer.

[0102] The present disclosure will be explained in more detail by the following examples, but the present disclosure is not limited to these examples.

[0103] <Substrate, Support Layer, and Sealant Layer> As one combination of substrate and support layer (first combination), a biaxially oriented polypropylene (OPP) film (manufactured by Mitsui Chemicals Tocello Co., Ltd., product name: ME-1, MD heat shrinkage: 2.0%, thickness: 20 μm) was prepared. As another combination of substrate and support layer (second combination), a biaxially oriented polypropylene (OPP) film (MD heat shrinkage: 3.7%, thickness: 20 μm) was prepared. As yet another combination of substrate and support layer (third combination), a biaxially oriented polypropylene (OPP) film (MD heat shrinkage: 6.7%, thickness: 20 μm) was prepared. In addition, the following five types of sealant layers were prepared as sealant layers. First sealant layer: non-oriented polypropylene (CPP) film (manufactured by Toray Advanced Film Co., Ltd., product name: Torayfan ZK93KM, thickness: 60 μm) Second sealant layer: polypropylene laminate film (1) (thickness: 60 μm) Third sealant layer: polypropylene laminate film (2) (thickness: 60 μm) Fourth sealant layer: polypropylene laminate film (3) (thickness: 60 μm) Fifth sealant layer: polypropylene laminate film (4) (thickness: 60 μm)

[0104] Each of the polypropylene laminate films (1) to (4) has a three-layer structure consisting of a surface layer (10 μm), an intermediate layer (40 μm), and a back layer (10 μm). The surface and back layers of the polypropylene laminate film (1) are each formed from a mixture of homopolypropylene resin (h-PP) and propylene-ethylene random copolymer (r-PP) (h-PP:r-PP=7:3). The surface and back layers of the polypropylene laminate films (2) to (3) are each formed from r-PP. The intermediate layer of the polypropylene laminate films (1) to (4) is formed from a propylene-ethylene block copolymer (b-PP). The amount of elastomer (Tafmer PN-3560, manufactured by Mitsui Chemicals, Inc.) added to the intermediate layer of the polypropylene laminate film (1) is 31% by mass. No elastomer is added to the intermediate layer of the polypropylene laminate film (2). The amount of elastomer (Tafmer PN-3560, manufactured by Mitsui Chemicals, Inc.) added to the intermediate layer of the polypropylene laminate film (3) is 31% by mass. The amount of elastomer (Tafmer PN-3560, manufactured by Mitsui Chemicals, Inc.) added to the intermediate layer of the polypropylene laminate film (4) is 55% by mass.

[0105] <Preparation of Adhesion Layer-Forming Composition> A mixed solution was prepared by mixing and stirring γ-isocyanate propyltrimethoxysilane and acrylic polyol at a ratio of 1:5. Subsequently, tolylene diisocyanate (TDI) was added to the mixed solution so that the number of NCO groups in tolylene diisocyanate was equal to the number of OH groups in the acrylic polyol. The mixed solution was then diluted with ethyl acetate to a concentration of 2% by mass. This resulted in the preparation of an adhesion layer-forming composition (anchor coating agent).

[0106] <Preparation of Coating Liquid α for Barrier Coat> 10 g each of the following liquids A, B, and C were prepared and mixed to prepare coating liquid α. Liquid A: Tetraethoxysilane (Si(OC ２ H ５ ) ４72.1 g of 0.1N hydrochloric acid was added to 17.9 g of SiO 2 and 10 g of methanol, and the mixture was stirred for 30 minutes to obtain a hydrolyzed solids content of 5% by mass (SiO ２ Solution B: A 5% by mass water / methanol solution of polyvinyl alcohol (mass ratio of water:methanol is 95:5). Solution C: A hydrolysis solution obtained by diluting 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate with a water / isopropyl alcohol mixed solution (mass ratio of water:isopropyl alcohol is 1:1) to a solids content of 5% by mass.

[0107] <Preparation of Barrier Coating Solution β> First, TEOS, methanol, and 0.1N hydrochloric acid were mixed in a mass ratio of 45 / 15 / 40 to obtain a TEOS hydrolyzed solution. This solution, a 5 mass% aqueous solution of polyvinyl alcohol (hereinafter referred to as "PVA"), and a silane coupling agent, 1,3,5-tris(3-methoxysilylpropyl)isocyanurate, in a water / IPA (isopropyl alcohol) = 1 / 1 solution to a solid content of 5 mass% (R ２ Si(OH) ３ The coating solution β was prepared by mixing the three solutions. ２ Solid content (converted value) and R of isocyanurate silane ２ Si(OH) ３ The liquid was prepared so that the mass ratio of the solid content (converted value) to the PVA solid content was 40 / 5 / 55.

[0108] <Preparation of Coating Solution γ for Barrier Coat> Coating Solution γ was prepared by blending 40 to 75% by mass of an "aqueous polyurethane resin," 10 to 40% by mass of a "water-soluble polymer," and 5 to 20% by mass of a "silane coupling agent." Aqueous polyurethane resin: an aqueous dispersion of an aqueous polyurethane resin containing an acid group-containing polyurethane resin and a polyamine compound, "Takelac (registered trademark) WPB-341," an aqueous polyurethane dispersion manufactured by Mitsui Chemicals, Inc., with a solids content of 30%. Water-soluble polymer: polyvinyl alcohol with a saponification degree of 98 to 99% and a polymerization degree of 500 (trade name: Poval PVA-105, manufactured by Kuraray Co., Ltd.). Silane coupling agent: 3-glycidoxypropyltriethoxysilane (trade name: KBE-403, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0109] <Preparation of two-component curing urethane adhesives (a) to (k)> First, the following two types of polyols were prepared as base agents. Both base agents contained ethyl acetate as a solvent. Base agent A: A polyester polyol (molecular weight (Mw): 28,000) obtained by polymerizing equal amounts of ethylene glycol and neopentyl glycol as diols and adipic acid as dicarboxylic acid so that the molar ratio of diol to dicarboxylic acid was 1:1. Base agent B: A polyester polyurethane polyol (molecular weight (Mw): 27,000) obtained by polymerizing equal amounts of ethylene glycol and 1,6-hexanediol as diols and terephthalic acid as dicarboxylic acid so that the molar ratio of diol to dicarboxylic acid was 1:1.

[0110] A mixture (molar ratio 1:1) of an adduct of isophorone diisocyanate (hereinafter referred to as IPDI) with trimethylolpropane (hereinafter referred to as TMP) and an adduct of xylylene diisocyanate (hereinafter referred to as XDI) with TMP was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.5, thereby obtaining a two-component curing urethane adhesive (a).

[0111] A mixture of a TMP adduct of IPDI and a TMP adduct of XDI (molar ratio 1:1) was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.8, thereby obtaining a two-component curing urethane adhesive (b).

[0112] A mixture of a TMP adduct of IPDI and a TMP adduct of XDI (molar ratio 2:1) was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.5, thereby obtaining a two-component curing urethane adhesive (c).

[0113] A mixture of a TMP adduct of IPDI and a TMP adduct of XDI (molar ratio 3:1) was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.5, thereby obtaining a two-component curing urethane adhesive (d).

[0114] A mixture of a TMP adduct of IPDI and a TMP adduct of XDI (molar ratio 3:1) was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.8, thereby obtaining a two-component curing urethane adhesive (e).

[0115] A mixture of a TMP adduct of IPDI and a TMP adduct of XDI (molar ratio 3:1) was prepared as the curing agent. Next, the main component B and the curing agent were mixed so that the NOC / OH ratio was 1.8, thereby obtaining a two-component curing urethane adhesive (f).

[0116] A burette of hexamethylene diisocyanate (hereinafter referred to as HDI) was prepared as the curing agent. Next, the base component A and the curing agent were mixed so that the NOC / OH ratio was 1.5, thereby obtaining a two-component curing urethane adhesive (g).

[0117] A burette of HDI was prepared as the curing agent. Next, the base component A and the curing agent were mixed so that the NOC / OH ratio was 1.8, thereby obtaining a two-component curing urethane adhesive (h).

[0118] An IPDI-TMP adduct was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.5, thereby obtaining a two-component curing urethane adhesive (i).

[0119] An IPDI TMP adduct was prepared as the curing agent. Next, the main component A and the curing agent were mixed so that the NOC / OH ratio was 1.8, thereby obtaining a two-component curing urethane adhesive (j).

[0120] An IPDI TMP adduct was prepared as the curing agent. Next, the base component B and the curing agent were mixed so that the NOC / OH ratio was 1.8, thereby obtaining a two-component curing urethane adhesive (k).

[0121] Example 1 An adhesion layer-forming composition was applied to a substrate using a bar coater, and the adhesion layer-forming composition was dried at 50°C. This formed an adhesion layer (anchor coat layer) with a thickness of 0.2 µm. Next, a transparent vapor deposition layer (silica vapor deposition layer) made of silicon oxide with a thickness of 40 nm was formed using a vacuum deposition apparatus using an electron beam heating system.

[0122] Next, the coating liquid α was applied onto the vapor-deposited layer using a bar coater, and the coating liquid α was dried at 60°C for 1 minute. As a result, a barrier coat having a thickness of 300 nm was formed on the vapor-deposited layer. In this way, a barrier layer having a substrate, an adhesion layer, a vapor-deposited layer, and a barrier coat was formed.

[0123] Next, a two-component curing urethane adhesive (a) was applied onto the barrier coat of the barrier layer to form a 3 μm-thick adhesive layer (second adhesive layer). Next, a support layer was laminated via the adhesive layer by dry lamination. Next, a two-component curing urethane adhesive (a) was applied onto the substrate of the barrier layer to form a 3 μm-thick adhesive layer (first adhesive layer). Next, the first sealant layer was laminated via the adhesive layer by dry lamination. This produced a laminate (gas barrier laminate) having a laminated structure of the support layer, second adhesive layer, barrier coat, vapor deposition layer, adhesion layer, substrate, first adhesive layer, and first sealant layer. The polypropylene content of the resulting laminate was 90% by mass or more.

[0124] Examples 2 to 8 Laminates of Examples 2 to 8 were produced in the same manner as in Example 1, except that two-component curing urethane adhesives (b) to (h) were used instead of the adhesive (a).

[0125] Examples 9 to 16 Laminates of Examples 9 to 16 were produced in the same manner as in Examples 1 to 8, except that the coating liquid β was used instead of the coating liquid α.

[0126] Examples 17 to 24 Laminates of Examples 17 to 24 were produced in the same manner as in Examples 1 to 8, except that the coating liquid γ was used instead of the coating liquid α.

[0127] (Examples 25 to 32) Laminates of Examples 25 to 32 were produced in the same manner as in Examples 1 to 8, except that the combination of the substrate and the support layer was the second combination, and that the coating liquid β was used instead of the coating liquid α.

[0128] (Examples 33 to 40) Laminates of Examples 33 to 40 were produced in the same manner as in Examples 1 to 8, except that the combination of the substrate and the support layer was the third combination and that the coating liquid β was used instead of the coating liquid α.

[0129] (Examples 41 to 48) Laminates of Examples 41 to 48 were produced in the same manner as in Examples 1 to 8, except that a second sealant layer was used as the sealant layer and that coating liquid β was used instead of coating liquid α.

[0130] (Examples 49 to 56) Laminates of Examples 49 to 56 were produced in the same manner as in Examples 1 to 8, except that a third sealant layer was used as the sealant layer and that coating liquid β was used instead of coating liquid α.

[0131] (Examples 57 to 64) Laminates of Examples 57 to 64 were produced in the same manner as in Examples 1 to 8, except that a fourth sealant layer was used as the sealant layer and that coating liquid β was used instead of coating liquid α.

[0132] (Examples 65 to 72) Laminates of Examples 65 to 72 were produced in the same manner as in Examples 1 to 8, except that a fifth sealant layer was used as the sealant layer and that coating liquid β was used instead of coating liquid α.

[0133] (Examples 73 to 80) The laminates of Examples 73 to 80 were produced in the same manner as in Examples 9 to 16, except that the order of lamination was the support layer, the second adhesive layer, the substrate, the adhesion layer, the vapor deposition layer, the barrier coat, the first adhesive layer, and the first sealant layer.

[0134] Comparative Examples 1 to 3 Laminates of Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0135] Comparative Examples 4 to 6 Laminates of Comparative Examples 4 to 6 were produced in the same manner as in Example 9, except that two-component curing urethane adhesives (i) to (k) were used instead of the adhesive (a).

[0136] Comparative Examples 7 to 9 Laminates of Comparative Examples 7 to 9 were produced in the same manner as in Example 17, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0137] Comparative Examples 10 to 12 Laminates of Comparative Examples 10 to 12 were produced in the same manner as in Example 25, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0138] Comparative Examples 13 to 15 Laminates of Comparative Examples 13 to 15 were produced in the same manner as in Example 33, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0139] Comparative Examples 16 to 18 Laminates of Comparative Examples 16 to 18 were produced in the same manner as in Example 41, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0140] Comparative Examples 19 to 21 Laminates of Comparative Examples 19 to 21 were produced in the same manner as in Example 49, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0141] Comparative Examples 22 to 24 Laminates of Comparative Examples 22 to 24 were produced in the same manner as in Example 57, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0142] Comparative Examples 25 to 27 Laminates of Comparative Examples 25 to 27 were produced in the same manner as in Example 65, except that two-component curing urethane adhesives (i) to (k) were used instead of adhesive (a).

[0143] (Comparative Examples 28 to 30) The laminates of Comparative Examples 28 to 30 were produced in the same manner as in Comparative Examples 4 to 6, except that the order of lamination was the support layer, second adhesive layer, substrate, adhesion layer, vapor deposition layer, barrier coat, first adhesive layer, and the first sealant layer.

[0144] <Method for Measuring Heat Shrinkage of Substrate> The heat shrinkage of the substrate included in the barrier layer was measured according to the following procedure. The measurement results of the heat shrinkage of the substrate in Examples 1 to 8 and Comparative Examples 1 to 3 are shown in Table 1 below. The measurement results of the heat shrinkage of the substrate in Examples 9 to 16 and Comparative Examples 4 to 6 are shown in Table 2 below. The measurement results of the heat shrinkage of the substrate in Examples 17 to 24 and Comparative Examples 7 to 9 are shown in Table 3 below. The measurement results of the heat shrinkage of the substrate in Examples 25 to 32 and Comparative Examples 10 to 12 are shown in Table 4 below. The measurement results of the heat shrinkage of the substrate in Examples 33 to 40 and Comparative Examples 13 to 15 are shown in Table 5 below. The measurement results of the heat shrinkage of the substrate in Examples 41 to 48 and Comparative Examples 16 to 18 are shown in Table 6 below. The measurement results of the heat shrinkage of the substrate in Examples 49 to 56 and Comparative Examples 19 to 21 are shown in Table 7 below. The measurement results of the heat shrinkage of the substrate in Examples 57 to 64 and Comparative Examples 22 to 24 are shown in Table 8 below. The measurement results of the heat shrinkage rates of the substrates in Examples 65 to 72 and Comparative Examples 25 to 27 are shown in Table 9 below. The measurement results of the heat shrinkage rates of the substrates in Examples 73 to 80 and Comparative Examples 28 to 30 are shown in Table 10 below.

[0145] (a) As shown in FIG. 4, a measurement sample 500 was prepared by cutting a single substrate to a size of 200 mm x 200 mm. (b) As shown in FIG. 4, two straight lines L1 and L2, each 120 mm or longer, parallel to the TD direction of the measurement sample 500 were drawn with a 100 mm gap between them. (c) As shown in FIG. 4, two straight lines L3 and L4, each 120 mm or longer, parallel to the MD direction of the measurement sample 500 were drawn with a 100 mm gap between them. (d) As shown in FIG. 4, seven scales N1 to N7 were drawn on the line L1 at 20 mm intervals. Similar scales were drawn on the lines L2 to L4. The scales on the lines L1 and L2 were aligned so that when each of the scales N1 to N7 on the line L1 was connected to each of the scales N1 to N7 on the line L2, the lines would be parallel to the MD direction. Furthermore, the scales of lines L3 and L4 were aligned so that if a straight line were drawn connecting each of the scales N1 to N7 on line L3 with each of the scales N1 to N7 on line L4, the line would be parallel to the TD direction. (e) The measurement sample 500, placed on a Teflon (registered trademark) sheet, was placed on a glass plate in an oven heated to a predetermined temperature (150°C or 160°C) and heated for 15 minutes. After heating, the measurement sample 500 was removed from the oven and left at room temperature (25°C) for 30 minutes. (f) The linear distance between the scale N1 on line L1 (the intersection of L1 and N1) and the scale N1 on line L2 (the intersection of L2 and N1) was measured as the MD length before and after heating, and the MD heat shrinkage was calculated using the following formula (1). Similarly, the MD heat shrinkage rate was determined at each of the positions of the scales N1 to N7, and the average value thereof was defined as the MD heat shrinkage rate of the measurement sample 500. MD heat shrinkage rate (%) = (MD length before heating - MD length after heating) / MD length before heating × 100 ... (1)

[0146] <Retort Treatment> Packaging bags with four sealed sides were produced using the laminates produced in each Example and Comparative Example. The packaging bags were filled with water as the content. Then, retort sterilization was performed at 130°C for 60 minutes.

[0147] <Measurement of Elastic Modulus of First Adhesive Layer> In each of Examples 1 to 80 and Comparative Examples 1 to 30, a laminate that was a part of the packaging bag after retort treatment was cut out. Then, a cross-sectional sample in which a cross section of the first adhesive layer was exposed from the cut-out laminate was produced by the following method.

[0148] <Cross-Section Sample Preparation> First, the front and back surfaces of the cut laminate were subjected to corona treatment. The laminate was then cut into 2 mm x 3 mm strips with a razor, and the cut film pieces were embedded in resin. A visible light-curable resin (Aronix LCR D-800, manufactured by Toagosei Co., Ltd.) was used. The film pieces were embedded in the resin and then cured by light irradiation. After the resin cured, the embedded film pieces were fixed in an SPM sample holder insert. The fixed film pieces were then trimmed and cross-sectioned at room temperature (25°C) using a glass knife. The cross-section was then cut with a diamond knife at a cutting speed of 3 mm / s and a cutting thickness of 500 nm until a mirror finish was obtained. An ultramicrotome (EM UC7, manufactured by Leica Microsystems) was used as the cross-section cutting device. The cutting direction was horizontal to the interfaces of the layers contained in the film pieces. Measurement of the shape and elastic modulus of the sample with the exposed cross section (cross-section sample) was carried out while the sample was fixed in an insert for the SPM sample holder.

[0149] <Elastic Modulus Measurement> Next, the elastic modulus of the first adhesive layer was measured using a scanning probe microscope (SPM) by the following method. The cross-sectional sample was subjected to shape measurement and elastic modulus measurement using an SPM (scanning probe microscope). The SPM used was a "JupiterXR (trade name)" manufactured by Oxford Instruments. The cantilever (measurement probe) used for the SPM was a "biosphere B30-FM (trade name)" manufactured by nanotools (tip radius: 30 nm, spring constant: 2.8 N / m). In measuring the cross-sectional sample and calculating the elastic modulus of the first adhesive layer, the tip radius of the cantilever was determined by referring to the individual characteristic values ​​of the product, and the cantilever spring constant and optical lever sensitivity were determined using values ​​obtained using the GetReal method, which is a calibration function of the SPM.

[0150] First, the cross-sectional sample was scanned perpendicular to the layer interface using the SPM's AC mode (tapping mode) with a field of view of 1 μm × 1 μm and a scanning speed of 2 Hz. The center of the field of view was set to the center of the film thickness of the cross section of the first adhesive layer. Next, the SPM's contact mode was used to obtain force curves (load-displacement curves) when the cantilever was pressed into and pulled out of the first adhesive layer under conditions of a maximum load of 10 nN and a test speed of 500 nm / s. Force curves were obtained at 10 vertical and 10 horizontal points at 100 nm intervals within the field of view, for a total of 100 points. Force curves with a displacement of 500 nm or more were obtained for both the cantilever press and the cantilever pull. For the cross-sectional sample, two measurements were performed at each sample level, resulting in a total of 200 force curves. The elastic modulus of the cantilever was assumed to be 865 GPa, the Poisson's ratio was assumed to be 0.2, and the Poisson's ratio of the first adhesive layer was assumed to be 0.33.

[0151] The obtained force curve was analyzed using an elastic contact model of the Johnson-Kendall-Roberts (JKR) theory to calculate the elastic modulus of the first adhesive layer. The elastic modulus calculation using the JKR theory was performed using SPM's analysis software, performing fitting analysis using the sample's elastic modulus, displacement origin, and maximum adhesive force as fitting parameters. The analysis range for each point on the force curve was determined as the range starting from the load and displacement when the load first reached "(maximum load - minimum load) x 0.65 + minimum load" during the load change during pullout after reaching the maximum load, and ending with the load and displacement when the minimum load was reached.

[0152] Using the above procedure, the average value of the elastic modulus of 200 force curves obtained for each sample level was calculated. The measurement results of the elastic modulus of the first adhesive layer in each example and comparative example are shown in Tables 1 to 10 below. Note that in each example and comparative example, the elastic modulus of the second adhesive layer can be considered to be the same as the elastic modulus of the corresponding first adhesive layer.

[0153] (Oxygen Transmission Rate Measurement) The oxygen transmission rate (OTR) of the laminate after retort treatment was measured. The measurement was carried out using an oxygen transmission rate measuring device (OX-TRAN (registered trademark) 2 / 20, manufactured by Modern Control) under conditions of a temperature of 30°C and a relative humidity of 70%. The OTR measurement method complies with JIS K-7126, Method B (isobaric method), and ASTM D3985-81, and the measured OTR value is expressed in units of [cc / m ２ The OTR measurement results for each Example and Comparative Example are shown in Tables 1 to 10 below.

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164] As shown in Tables 1 to 3, the oxygen permeability of the examples and comparative examples using coating liquid β or coating liquid γ is lower than that of the examples and comparative examples using coating liquid α.

[0165] As shown in Tables 1 to 3, when the substrate is an OPP film, the oxygen permeability measurement results for the laminate increase as the modulus of elasticity of the first adhesive layer increases beyond 43 MPa. In particular, as shown in Tables 1 to 3, when the modulus of elasticity of the first adhesive layer is 53 MPa or greater, the oxygen permeability tends to increase more rapidly than when the modulus of elasticity of the first adhesive layer is less than 53 MPa. For example, when comparing Example 6 with Comparative Example 1, the oxygen permeability of Comparative Example 1 is 1.6 times or more that of Example 6. Furthermore, when comparing Example 22 with Comparative Example 7, the oxygen permeability of Comparative Example 7 is 1.5 times or more that of Example 22. Furthermore, when the modulus of elasticity of the first adhesive layer is less than 10 MPa, the oxygen permeability is relatively high. This is presumably due to adverse effects caused by the first adhesive layer being too soft. From these results, it can be inferred that by adjusting the modulus of elasticity of the first adhesive layer within an appropriate range, a laminate exhibiting good oxygen permeability can be obtained, regardless of the type of coating liquid.

[0166] <Elastic Modulus of Sealant Layer> A 20 mm square sample was formed from each of the first to fifth sealant layers. Subsequently, using a benchtop precision universal testing machine (AUTOGRAPH AGS-X 5kN, manufactured by Shimadzu Corporation), the elastic modulus (MD modulus and TD modulus) of the first to fifth sealant layers was measured from the tensile stress measured when each sample was elongated by 0.05% to 0.25% under the following conditions: temperature: 30°C, humidity: 70%, gauge length: 250 mm, and tensile speed: 5 m / min. The measurement results of the MD and TD moduli of the first to fifth sealant layers are shown in Table 11 below.

[0167] <Filling Suitability> Using the laminates produced in each Example and Comparative Example, three-sided bags measuring 95 mm x 140 mm were produced, leaving one short side untouched. Subsequently, 70 g of water was filled using a bag feeder and packaging machine, and the opening of the three-sided bag was heat-sealed to produce 1,000 packaging bags. The quality of the packaging bags was then confirmed by checking whether or not there was water leakage from the sealed portion. The filling suitability of each Example and Comparative Example was evaluated based on the following evaluation criteria. The evaluation results for each Example are shown in Table 12 below, and the evaluation results for each Comparative Example are shown in Table 13 below. [Evaluation Criteria] A: Good product rate of 98% or more B: Good product rate of 95% or more but less than 98% C: Good product rate of less than 95%

[0168] <Evaluation of Durability of Packaging Bags> Three-sided bags measuring 95 mm x 140 mm were prepared using the laminates prepared in each Example and Comparative Example. 70 g of water was filled into the three-sided bags, which were then heat-sealed. Test samples were then prepared by retort sterilization at 128°C for 15 minutes. 100 test samples were prepared for each Example and Comparative Example. Next, for each Example and Comparative Example, the 100 test samples were allowed to free-fall horizontally from a position 100 cm above the floor. This free fall was repeated 100 times. The durability of the packaging bags was then evaluated based on the percentage of test samples that did not burst. The durability of the packaging bags in each Example and Comparative Example was evaluated based on the following evaluation criteria. The evaluation results for each Example are shown in Table 12 below, and the evaluation results for each Comparative Example are shown in Table 13 below. [Evaluation criteria] A: Residual rate is 100% B: Residual rate is 95% or more but less than 100%

[0169]

[0170]

[0171]

[0172] As can be seen from Tables 12 and 13 above, the filling suitability of the packaging bags in Examples 57 to 72 and Comparative Examples 22 to 27 was lower than that of Examples 1 to 56 and 73 to 80. In particular, the filling suitability of the packaging bags in Examples 65 to 72 and Comparative Examples 25 to 27, in which a fifth sealant layer was used, was low. This is presumably due in part to the fact that the MD modulus of elasticity of the fourth sealant layer was lower than that of the first sealant layer, and that the fifth sealant layer was too soft. The durability of the packaging bags in Examples 49 to 56 and Comparative Examples 22 to 24, in which a third sealant layer was used, was lower than that of Examples 1 to 48 and 57 to 80. This is presumably due in part to the fact that the third sealant layer was too hard.

[0173] 1...Laminate, 10...Barrier layer, 11...Substrate, 12...Adhesion layer, 13...Vapor deposition layer, 14...Barrier coat, 20...Sealant layer, 30...First adhesive layer, 40...Support layer, 50...Second adhesive layer.

Claims

1. A gas barrier laminate comprising: a barrier layer having a substrate on which a barrier coat is provided; a sealant layer overlying a first main surface of the barrier layer; a support layer overlying a second main surface of the barrier layer; a first adhesive layer bonding the barrier layer and the sealant layer together; and a second adhesive layer bonding the barrier layer and the support layer together, wherein the first adhesive layer comprises a two-component curing urethane adhesive; the substrate comprises a polyolefin; and after retort treatment of the gas barrier laminate, the elastic modulus of the first adhesive layer measured with a scanning probe microscope is 5 MPa or more and less than 53 MPa.

2. The gas barrier laminate described in claim 1, wherein the second adhesive layer contains a two-component curing urethane adhesive, and the elastic modulus of the second adhesive layer measured with a scanning probe microscope after the retort treatment is 5 MPa or more and less than 53 MPa.

3. The gas barrier laminate according to claim 1 or 2, wherein the barrier layer further comprises an anchor coat layer and a deposition layer located between the substrate and the barrier coat, and the anchor coat layer is located between the substrate and the deposition layer.

4. The gas barrier laminate according to claim 3, wherein the thickness of the vapor deposition layer is 5 nm or more and 80 nm or less.

5. A gas barrier laminate as described in claim 1 or 2, wherein the elastic modulus of the first adhesive layer measured by a scanning probe microscope before the retort treatment is 55 MPa or more.

6. A gas barrier laminate according to claim 1 or 2, wherein the thickness of the first adhesive layer and the thickness of the second adhesive layer are each 0.5 μm or more and 10 μm or less.

7. The gas barrier laminate according to claim 1 or 2, wherein the elastic modulus of the sealant layer is 600 MPa or more and 1400 MPa or less.

8. A gas barrier laminate according to claim 1 or 2, wherein each of the substrate and the sealant layer is a polyolefin film, and the total mass ratio of polyolefin in the gas barrier laminate is 90 mass % or more.

9. The gas barrier laminate according to claim 8, wherein the substrate is a stretched polypropylene film, and the sealant layer is a non-stretched polypropylene film.

10. A packaging bag made from the gas barrier laminate according to claim 1 or 2.

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