Laminate and packaging bag

Abstract

To provide a laminate and a packaging bag that achieve monomaterialization, allow easy detachment of a printing layer, and exhibit enhanced strength against bag breakage and resistance to vibration during transportation.SOLUTION: A laminate according to one aspect of the present disclosure has a laminated structure including, in this order, an outermost layer, a printing layer, a first adhesive layer, an intermediate layer, a second adhesive layer, and a sealant layer, wherein the outermost layer, the intermediate layer, and the sealant layer contain polypropylene, the content of the polypropylene being 90 mass% or more based on the total amount of the laminate, the adhesion strength between the outermost layer and the printing layer being 0.5 to 0.8 N / 15 mm, and the adhesion strength between the first adhesive layer and the intermediate layer being 0.5 to 0.8 N / 15 mm.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Gas barrier laminates are mainly widely used as packaging materials for foods, pharmaceuticals, etc. including heat sterilization such as boiling treatment and retort treatment. With the world's attention on the plastic waste problem, the demand for environmentally friendly packaging materials is increasing more and more in order to realize a recycling-oriented society. Many global companies have set goals for better plastic resource recycling of container packaging and have introduced various measures. In addition, in the United States, a recycling route from the recovery to the reuse of polyethylene-based resins has begun to be established, and the global efforts towards recycling based on monomaterial (single material) are accelerating.

[0003] As such a packaging material, for example, Patent Document 1 discloses a laminate including a biaxially oriented laminated polypropylene film and an unstretched polypropylene film, which includes a base material layer A and a surface layer B.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a packaging material for retort treatment, from the viewpoint of sealant properties, the demand for a packaging material made of polypropylene into a monomaterial is expected. Therefore, the present inventors selected polypropylene as a material to achieve monomaterialization.

[0006] By the way, when the laminate includes a printing layer, directly recycling the laminate may cause a decrease in appearance due to coloring and a decrease in physical properties of the printing layer. Therefore, the printing layer is removed in a removal step. The laminate is required to allow the printing layer to be easily removed.

[0007] In addition, it has been clarified by the study of the inventors that delamination occurs in the laminate in which the printing layer is easily removed, in terms of the bag-breaking strength and the resistance to vibration during transportation.

[0008] The present disclosure provides a laminate and a packaging bag that achieve monomaterialization, allow the printing layer to be easily removed, and are excellent in bag-breaking strength and resistance to vibration during transportation.

Means for Solving the Problems

[0009] One aspect of the present disclosure relates to the following laminate and packaging bag. [1] An outermost layer, a printing layer, a first adhesive layer, an intermediate layer, a second adhesive layer, a sealant layer, A laminate having a laminated structure including these in this order, wherein the outermost layer, the intermediate layer, and the sealant layer contain polypropylene, the content of polypropylene is 90% by mass or more based on the total amount of the laminate, the adhesion strength between the outermost layer and the printing layer is 0.5 to 0.8 N / 15 mm, the adhesion strength between the first adhesive layer and the intermediate layer is 0.5 to 0.8 N / 15 mm. [2] Further including a barrier layer, The laminate according to [1], wherein the barrier layer has a barrier coating layer. [3] The laminate according to [2], wherein the barrier layer has an anchor coating layer, a vapor deposition layer, and a barrier coating layer in this order from the intermediate layer side. [4] The laminate according to [2] or [3], wherein the barrier layer is located between the intermediate layer and the second adhesive layer. [5] The laminate according to [3], wherein the thickness of the vapor deposition layer is 5 nm or more and 80 nm or less. [6] The laminate according to any one of [1] to [5], wherein the thicknesses of the first adhesive layer and the second adhesive layer are 0.5 μm or more and 3.5 μm or less. [7] The laminate according to any one of [1] to [6], wherein the ratio of the thickness of the first adhesive layer to the thickness of the printing layer (thickness of the first adhesive layer / thickness of the printing layer) is less than 3. [8] The laminate according to any one of [1] to [6], wherein the outermost layer and the intermediate layer contain a stretched polypropylene film, and the sealant layer contains an unstretched polypropylene film. [9] The laminate according to any one of [1] to [8], wherein the surface layer on the printing layer side of the outermost layer contains homopolypropylene.

[10] The laminate according to any one of [1] to [9], wherein the intermediate layer has a multilayer structure including a first skin layer, a core layer, and a second skin layer in this order.

[11] A packaging bag containing the laminate according to any one of [1] to

[10] .

Advantages of the Invention

[0010] According to the present disclosure, there are provided a laminate and a packaging bag that achieve monomerization, are easy to peel off the printing layer, and are excellent in bag-breaking strength and resistance to vibration during transportation.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described. The same components are denoted by the same reference numerals, and overlapping descriptions will be omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0013] [Gas barrier laminate] [First Embodiment] Hereinafter, a gas barrier laminate according to the first embodiment will be described. FIG. 1 is a schematic cross-sectional view showing the laminate according to this embodiment. The laminate 1 has a laminated structure including an outermost layer 10, a printing layer 20, a first adhesive layer 30, an intermediate layer 40, a barrier layer 50, a second adhesive layer 60, and a sealant layer 70 in this order. The outermost layer 10, the intermediate layer 40, and the sealant layer 70 contain polypropylene. The content of polypropylene is 90% by mass or more based on the total amount of the laminate 1.

[0014] The adhesion strength between the outermost layer 10 and the printing layer 20 is 0.5 to 0.8 N / 15 mm, and the adhesion strength between the first adhesive layer 30 and the intermediate layer 40 is 0.5 to 0.8 N / 15 mm. Thereby, the laminate 1 can achieve both the ease of peeling of the printing layer and the bag-breaking resistance and vibration resistance while realizing monomaterialization.

[0015] The adhesion strength between the outermost layer 10 and the printing layer 20 may be 0.6 N / 15 mm or more and 0.7 N / 15 mm or less. The adhesion strength can be adjusted by changing the surface (printing layer or intermediate layer) on which the adhesive constituting the first adhesive layer is first applied. Also, the adhesion strength can be adjusted by the type of the adhesive constituting the first adhesive layer and its curing conditions.

[0016] The adhesion strength between the outermost layer 10 and the printing layer 20 is measured as follows. That is, the laminate is cut out into strips with a width of 15 mm to obtain a measurement sample. T-peeling is performed between the outermost layer 10 and the printing layer 20 of the measurement sample. The peeling is performed at a tensile speed of 100 mm / min and a temperature of 23°C. Thereby, the adhesion strength is measured. The adhesion strength may be the average value of the values obtained by performing the peeling test on three measurement samples.

[0017] The adhesion strength between the first adhesive layer 30 and the intermediate layer 40 may be 0.6 N / 15 mm or more and may be 0.7 N / 15 mm or less. The adhesion strength can be adjusted by subjecting the intermediate layer to corona treatment or changing its conditions. Further, the adhesion strength can be adjusted by providing a skin layer on the intermediate layer and changing its material. The adhesion strength between the first adhesive layer 30 and the intermediate layer 40 is measured in the same manner as the adhesion strength between the outermost layer 10 and the printing layer 20.

[0018] (Outermost layer 10) The outermost layer 10 is a plastic member that functions as the outermost layer in the laminate 1. The thickness of the outermost layer 10 is not particularly limited. Depending on the application, the thickness can be 6 to 200 μm, but from the perspective of reducing material for environmental load reduction and obtaining excellent heat resistance, impact resistance, and gas barrier properties, it may be 9 to 50 μm, may be 12 to 38 μm, may be 18 to 30 μm, or may be 15 to 25 μm.

[0019] From the perspective of recyclability of the laminate 1, etc., the outermost layer 10 may contain, for example, a polypropylene film and 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, etc. Also, as the polypropylene, polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-α olefin copolymer, etc. can be used. From the perspective of environmental suitability, the outermost layer 10 may contain a biomass-derived polypropylene resin.

[0020] The content of polypropylene may be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass based on the total amount of the outermost layer 10.

[0021] From the perspective of easy peelability, the surface layer on the printing layer 20 side of the outermost layer 10 preferably contains homopolypropylene which is a homopolymer of propylene. The content of homopolypropylene may be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass based on the total amount of the surface layer on the printing layer 20 side of the outermost layer 10. The thickness of the surface layer on the printing layer 20 side of the outermost layer 10 may be, for example, 0.4 μm or more, 0.5 μm or more, or 0.6 μm or more, and may also be 5.0 μm or less, 3.0 μm or less, or 1.0 μm or less.

[0022] Various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be added to the polypropylene film constituting the outermost layer 10.

[0023] The polypropylene film constituting the outermost layer 10 may be a stretched film or an unstretched film. However, from the perspectives of impact resistance, heat resistance, water resistance, dimensional stability, etc., the polypropylene film is preferably a stretched polypropylene film. Thereby, it is possible to suppress the outermost layer 10 from thermally fusing in the heat sealing process during bag making. In addition, the laminate 1 can be more suitably used for applications that are subjected to heat treatments such as retort processing and boiling processing. The stretching method is not particularly limited, and any method may be used as long as a film with stable dimensions, such as stretching by inflation, uniaxial stretching, or biaxial stretching, can be supplied.

[0024] When the outermost layer is heated in an oven under the conditions of 150 °C for 15 minutes, it is preferable that the heat shrinkage rate of MD obtained by the following formula (1) is 7% or less, and the heat shrinkage rate of TD obtained by the following formula (2) is 5% or less. When the heat shrinkage rate is within the above range, the oxygen barrier property after retort processing tends to be further improved. From the same viewpoint, the heat shrinkage rate of the above MD is more preferably 5% or less, and still more preferably 4% or less. From the same viewpoint, the heat shrinkage rate of the above TD is more preferably 4% or less. The heat shrinkage rate of the above MD may be, for example, 1% or more. The heat shrinkage rate of the above TD may be, for example, 0.4% or more.

[0025] MD heat shrinkage rate (%) = (MD length before heating - MD length after heating) / MD length before heating × 100 …(1) TD heat shrinkage rate (%) = (TD length before heating - TD length after heating) / TD length before heating × 100 …(2)

[0026] In this specification, MD is the machine direction of the outermost layer 10, the intermediate layer 40, and the sealant layer 70, and TD is the transverse direction perpendicular thereto. For example, the film can be used to measure the orientation angle using a retardation measuring device (trade name: KOBRA, manufactured by Oji Scientific Instruments Co., Ltd.), and MD and TD can be distinguished from the orientation angle. When the film is a stretched polypropylene film, it can be considered that the direction in which the molecular chains are oriented is TD.

[0027] The outermost layer 10 may be subjected to various pretreatment such as corona treatment, plasma treatment, and flame treatment on its laminated surface, or a coating layer such as an easy-adhesion layer may be provided.

[0028] The wettability of the laminated surface of the outermost layer 10 may be 31 dyne or more and 35 dyne or less, preferably 32 dyne or more and 34 dyne or less. When it is 31 dyne or more, the bag-breaking resistance and vibration resistance of the packaging bag are excellent, and when it is 35 dyne or less, the first adhesive layer is more likely to peel off.

[0029] (Printing layer 20) The printing layer is provided at 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 appropriately selected from known printing methods and printing inks in consideration of printability on the film, design properties such as color tone, adhesion, and safety as a food container. As the printing method, for example, a gravure printing method, an offset printing method, a gravure offset printing method, a flexographic printing method, an inkjet printing method, etc. can be used. Among them, the gravure printing method can be preferably used from the viewpoints of productivity and high definition of the pattern. Examples of the resin constituting the printing layer include urethane resins, copolymer resins of vinyl chloride and vinyl acetate, and acrylic resins. Among them, urethane resins can be preferably used from the viewpoint of resistance to high-temperature treatments such as autoclave sterilization and retort sterilization.

[0030] As the printing ink, biomass ink containing biomass-derived materials can also be preferably used. The biomass ink preferably contains a urethane resin and a colorant from the viewpoint of resistance to high-temperature treatments such as autoclave sterilization and retort sterilization. The polyester polyol, which is a reaction raw material of the polyurethane resin, is obtained by reacting a polycarboxylic acid having two or more carboxyl groups with a polyol having two or more hydroxyl groups.

[0031] The polycarboxylic acid preferably contains a plant-derived raw material. By using a plant-derived polycarboxylic acid, the biomass degree can be increased. Specifically, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, malic acid, etc. can be mentioned.

[0032] As the polyol, it is preferable to contain a plant-derived raw material. By using a plant-derived polyol, the biomass content can be increased. Specifically, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, isosorbide, etc. can be mentioned.

[0033] The above polyester polyol is preferably contained in the range of 30 to 95% by mass, more preferably 40 to 90% by mass, and most preferably 45 to 85% by mass based on the total amount of the above polyurethane resin.

[0034] The number average molecular weight of the above polyester polyol is preferably in the range of 400 to 10,000, more preferably in the range of 500 to 7,000, still more preferably in the range of 800 to 6,000, more preferably in the range of 1,000 to 6,000, and still more preferably in the range of 1,500 to 5,500. The number average molecular weight is measured by the gel permeation chromatography (GPC) method.

[0035] The printing layer may have a single-layer structure or a multilayer structure.

[0036] The thickness of the printing layer is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm.

[0037] In order to improve the adhesion of the printing layer, various pretreatment such as corona treatment, plasma treatment, and frame treatment may be performed on the surface of the layer provided with the printing layer, or a coating layer such as an easy-adhesion layer may be provided.

[0038] The discharge amount of the corona treatment may be, for example, 2 W·min / m 2 or more, and may be 10 W·min / m 2 or less.

[0039] (First adhesive layer 30 and second adhesive layer 60) The first adhesive layer 30 is a layered member that adheres the printing layer 20 and the intermediate layer 40. The second adhesive layer 60 is a layered member that adheres the barrier layer 50 and the sealant layer 70. As the material of the adhesive contained in the first adhesive layer 30 and the second adhesive layer 60, for example, polyester-isocyanate resin, urethane resin, polyether resin, etc. can be used. When using the packaging bag for retort applications, a two-component curable urethane-based adhesive with retort resistance can preferably be used. When the adhesive is a urethane-based adhesive, the second adhesive layer 60 tends to have a higher adhesion to the barrier layer 50 having a highly polar surface. As a result, the obtained packaging bag tends to be more excellent in burst strength. Incidentally, from the viewpoint of environmental consideration, the adhesive may not contain 3-glycidoxypropyltrimethoxysilane (GPTMS). The first adhesive layer 30 and the second adhesive layer 60 may not contain chlorine. In this case, the first adhesive layer 30 and the second adhesive layer 60 can suppress the coloring of recycled resin and the like after recycling and the generation of odor due to heat treatment. The first adhesive layer 30 and the second adhesive layer 60 may be formed of biomass materials and may not contain solvents from the viewpoint of environmental consideration.

[0040] When the adhesive contained in the first adhesive layer 30 and the second adhesive layer 60 is formed of biomass materials, it is preferable to contain a urethane-based resin and a colorant from the viewpoint of resistance to high-temperature treatments such as boiling sterilization treatment and retort sterilization treatment. The polyester polyol, which is a reaction raw material of the polyurethane resin, is obtained by reacting a polycarboxylic acid having two or more carboxyl groups with a polyol having two or more hydroxyl groups.

[0041] As the polycarboxylic acid, it is preferable to contain a plant-derived raw material. By using a plant-derived polycarboxylic acid, the biomass degree can be increased. Specifically, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, malic acid, etc. can be mentioned.

[0042] As the polyol, it is preferable to contain a plant-derived raw material. By using a plant-derived polyol, the biomass content can be increased. Specifically, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, isosorbide, etc. can be mentioned.

[0043] The above polyester polyol is preferably contained in the range of 30 to 95% by mass, more preferably 40 to 90% by mass, and most preferably 45 to 85% by mass based on the total amount of the above polyurethane resin.

[0044] The number average molecular weight of the above polyester polyol is preferably in the range of 400 to 10,000, more preferably in the range of 500 to 7,000, still more preferably in the range of 800 to 6,000, still more preferably in the range of 1,000 to 6,000, and still more preferably in the range of 1,500 to 5,500. The number average molecular weight is measured by the gel permeation chromatography (GPC) method.

[0045] The urethane-based adhesive contains a polyol and a polyisocyanate. When using a urethane-based adhesive, the first adhesive layer 30 and the second adhesive layer 60 may contain the polyurethane obtained by curing them, or may contain the uncured product of the urethane-based adhesive.

[0046] The polyol has two or more hydroxyl groups in one molecule. The polyisocyanate has two or more isocyanate groups in one molecule. The polyol and the polyisocyanate may react as the main agent and the curing agent, respectively, to produce polyurethane.

[0047] The polyol may contain at least one selected from the group consisting of polyester polyol and polyether polyol.

[0048] The polyisocyanate may be used alone or in combination of two or more. Examples of the polyisocyanate include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, and aromatic polyisocyanate compounds.

[0049] Examples of the aliphatic polyisocyanate compound include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), etc. Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate (IPDI), etc. Examples of the aromatic polyisocyanate compound include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), etc. As the polyisocyanate compound, polymers (for example, trimers) of these compounds can also be used, and specifically, adducts, biurets, isocyanurates, etc. can be used. Since the obtained packaging bag tends to have more excellent oxygen barrier properties after retort treatment, polymers of hexamethylene diisocyanate are preferred.

[0050] The mass ratio of the polyol to the polyisocyanate (polyol: polyisocyanate) is preferably 5:1 to 15:1, and more preferably 6:1 to 8:1.

[0051] The temperature for curing the urethane-based adhesive is preferably 40 to 60°C, and more preferably 40 to 50°C.

[0052] The time for curing the urethane-based adhesive is preferably 72 to 168 hours, and more preferably 72 to 120 hours.

[0053] The first adhesive layer may be produced by the following steps (1) to (4). (1) Apply the adhesive to the surface of the intermediate layer to form a coating film. (2) Dry the coating film. (3) Bond the intermediate layer and the printing layer through the dried coating film and apply pressure. (4) Cure the dried coating film to form the first adhesive layer. Regarding the above (1), when applying the adhesive to the printing layer, there is a possibility that the adhesive penetrates through the printing layer to the outermost layer, increasing the adhesion strength between the outermost layer and the printing layer. Therefore, it is preferable to apply the adhesive to the intermediate layer.

[0054] Examples of the method for applying the adhesive include coating methods such as roll coating, gravure roll coating, kiss coating, and printing methods such as gravure printing, offset printing, and transfer printing.

[0055] The drying time of the coating film may be 30 to 120 seconds. The drying temperature of the coating film may be 60 to 90 °C.

[0056] The thickness of the first adhesive layer 30 is, for example, 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 printing layer 20 and the intermediate layer 40 can be favorably suppressed. When the thickness of the first adhesive layer 30 is 10 μm or less, the laminate 1 can be easily made into a single 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, 5 μm or less, or 3.5 μm or less.

[0057] From the viewpoints of the adhesion strength between the outermost layer and the printing layer, the bag-breaking resistance, and the vibration resistance, the ratio of the thickness of the first adhesive layer to the thickness of the printing layer (thickness of the first adhesive layer / thickness of the printing layer) is preferably less than 3. The ratio (thickness of the first adhesive layer / thickness of the printing layer) is more preferably 2.7 or less, and even more preferably 2.5 or less.

[0058] The thickness of the second adhesive layer 60 is, for example, 0.5 μm or more and 10 μm or less. When the thickness of the second adhesive layer 60 is 0.5 μm or more, peeling between the barrier layer 50 and the sealant layer 70 can be suppressed well. When the thickness of the second adhesive layer 60 is 10 μm or less, the laminate 1 can be easily made into a single 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, 5 μm or less, or 3.5 μm or less.

[0059] (Intermediate layer 40) The thickness of the intermediate layer 40 may be the same as that of the outermost layer 10. From the viewpoint of recyclability of the laminate 1, etc., the intermediate layer 40 may contain, for example, a polypropylene film and may be made of a polypropylene film. As the polypropylene film, the same one as the outermost layer 10 can be used. Various additives similar to those in the outermost layer 10 may be added to the polypropylene film. Various pretreatment similar to those in the outermost layer 10 may be performed on the intermediate layer 40, or a coating layer may be provided. From the viewpoint of environmental suitability, the intermediate layer 40 may contain a biomass-derived polypropylene resin.

[0060] When the intermediate layer is oven-heated under the conditions of 150 °C for 15 minutes, it is preferable that the heat shrinkage rate of MD obtained by the above formula (1) is 10% or less, and the heat shrinkage rate of TD obtained by the above formula (2) is 12% or less. When the shrinkage rate is within the above range, the oxygen barrier property after retort treatment tends to be further excellent. From the same viewpoint, the heat shrinkage rate of the above MD is more preferably 7% or less, and even more preferably 6% or less. From the same viewpoint, the heat shrinkage rate of the above TD is more preferably 10% or less, and even more preferably 9% or less. The heat shrinkage rate of the above MD may be, for example, 1% or more. The heat shrinkage rate of the above TD may be, for example, 0.4% or more.

[0061] The content of polypropylene may be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass based on the total amount of the intermediate layer 40.

[0062] The surface of the intermediate layer 40 on the side of the first adhesive layer 30 may be subjected to corona treatment. The discharge amount of the corona treatment may be, for example, 2 W·min / m 2 or more, and may be 10 W·min / m 2 or less. The corona treatment may be carried out so that the wettability of the surface of the intermediate layer 40 falls within the range described later. The surface of the intermediate layer 40 on the side of the barrier layer 50 may also be subjected to corona treatment.

[0063] The wettability of the surface of the intermediate layer 40 on the side of the first adhesive layer 30 is preferably 29 dyne or more, and more preferably 30 dyne or more. Thereby, the bag breakage resistance and vibration resistance tend to be further improved. The wettability of the surface of the intermediate layer 40 on the side of the first adhesive layer 30 is preferably 32 dyne or less, and more preferably 31 dyne or less. Thereby, the printing layer tends to be more easily peeled off.

[0064] The wettability is measured in accordance with JIS K6768:1999.

[0065] (Barrier layer 50) The barrier layer 50 exhibits gas barrier properties against gases such as water vapor and oxygen. The barrier layer 50 has, in this order from the intermediate layer 40 side, an anchor coat layer 50a, a vapor deposition layer 50b, and a barrier coat layer 50c.

[0066] <Anchor coat layer 50a> The anchor coat layer 50a functions as a layer that can improve the adhesion performance of the vapor deposition layer 50b on the intermediate layer 40, and is provided directly above the intermediate layer 40. For this reason, the anchor coat layer 50a is located between the intermediate layer 40 and the vapor deposition layer 50b. By providing the anchor coat layer 50a, the smoothness of the surface of the intermediate layer 40 where the vapor deposition layer 50b is provided can be improved. Note that by improving the smoothness, it becomes easier to form the vapor deposition layer 50b uniformly without defects, and it is easy to exhibit high barrier properties. The anchor coat layer 50a can be formed using, for example, an anchor coating agent.

[0067] Examples of the anchor coat agent include polyester-based polyurethane resins, polyether-based polyurethane resins, and the like. From the viewpoints of heat resistance and interlayer adhesion strength, polyester-based polyurethane resins are preferred as the anchor coat agent.

[0068] The thickness of the anchor coat layer 50a is not particularly limited, but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.03 to 3 μm, and particularly preferably in the range of 0.05 to 2 μm. When the thickness of the anchor coat layer 50a is equal to or greater than the above lower limit value, sufficient interlayer adhesion strength tends to be obtained. On the other hand, when it is equal to or less than the above upper limit value, the desired gas barrier property tends to be easily exhibited.

[0069] As a method for coating the anchor coat layer 50a on the intermediate layer 40, known coating methods can be used without particular limitation, including dipping methods; methods using sprayers, coaters, printing machines, brushes, etc. In addition, as for the types of coaters and printing machines used in these methods and their coating methods, there are gravure coaters such as direct gravure method, reverse gravure method, kiss reverse gravure method, offset gravure method, reverse roll coater, micro gravure coater, chamber doctor combined coater, air knife coater, dip coater, bar coater, comma coater, die coater, etc.

[0070] The coating amount of the anchor coat layer 50a is such that the mass per 1 m 2 after coating and drying the anchor coat agent is preferably 0.01 to 5 g / m 2 and more preferably 0.03 to 3 g / m 2 After coating and drying the anchor coat agent, when the mass per 1 m 2 is equal to or greater than the above lower limit, film formation tends to be sufficient. On the other hand, when it is equal to or less than the above upper limit, it tends to dry sufficiently and it is difficult for solvents to remain.

[0071] Although the method for drying the anchor coat layer 50a is not particularly limited, 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. Further, the drying conditions can be appropriately selected depending on the drying method. For example, in the method of drying in an oven, it is preferable to dry at a temperature of 60 to 100°C for about 1 second to 2 minutes.

[0072] As the anchor coat layer 50a, a polyvinyl alcohol-based resin can be used instead of the above polyurethane resin. The polyvinyl alcohol-based resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit. Examples thereof include polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH).

[0073] As the PVA, for example, there are resins obtained by polymerizing vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprylate, vinyl laurate, vinyl stearate, vinyl pivalate, vinyl versatate, etc. alone and then saponifying them. The PVA may be a modified PVA that has been copolymerization-modified 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 and then saponifying. Examples of the unsaturated monomer copolymerizable with the vinyl ester include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-pentyn-1-ol, 5-hexen-1-ol; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid; nitriles such as acrylonitrile, methacrylonitrile; amides such as diacetoneacrylamide, acrylamide, methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid; vinyl compounds such as alkyl vinyl ether, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerin monoallyl ether, 3,4-diacetoxy-1-butene; vinylidene chloride, 1,4-diacetoxy-2-butene, vinylene carbonate, etc.

[0074] The degree of polymerization of PVA is preferably 300 to 3000. If the degree of polymerization is less than 300, the barrier property is likely to decrease, and if it exceeds 3000, the viscosity is too high and the coating suitability is likely to decrease. The saponification degree of PVA is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. Also, the saponification degree of PVA may be 100 mol% or less, or 99.9 mol% or less. The degree of polymerization and saponification degree of PVA can be measured in accordance with the method described in JIS K 6726 (1994).

[0075] 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 caprylate, vinyl laurate, vinyl stearate, vinyl pivalate, vinyl versatate, etc.

[0076] The degree of polymerization of EVOH is preferably 300 to 3000. When the degree of polymerization is less than 300, the barrier property is likely to decrease, and when it exceeds 3000, the viscosity is too high and the coating suitability is likely to decrease. The saponification degree of the vinyl ester component of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 99 mol% or more. Also, the saponification degree of EVOH may be 100 mol% or less, or 99.9 mol% or less. The saponification degree of EVOH is determined from the peak area of the hydrogen atoms contained in the vinyl ester structure and the peak area of the hydrogen atoms contained in the vinyl alcohol structure by performing nuclear magnetic resonance (1H-NMR) measurement.

[0077] 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. Also, 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, the gas barrier property or dimensional stability under high humidity can be maintained well. On the other hand, when the ethylene unit content is 65 mol% or less, the gas barrier property can be enhanced. The ethylene unit content of EVOH can be determined by the NMR method.

[0078] When using a polyvinyl alcohol-based resin as the anchor coat layer 50a, examples of the method for forming the anchor coat layer 50a include coating using a polyvinyl alcohol-based resin solution, multilayer extrusion, etc.

[0079] <Vapor deposition layer 50b> The vapor deposition layer 50b 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 deposition layer 50b is provided directly above the anchor coat layer 50a. The vapor deposition layer 50b may have a single-layer structure or a laminated structure. Therefore, the vapor deposition layer 50b contains at least one of a metal vapor deposition layer and an inorganic oxide layer. When the vapor deposition layer 50b includes a metal vapor deposition layer, examples of the metal contained in the metal vapor deposition layer include aluminum and stainless steel. When the vapor deposition layer 50b includes an inorganic oxide layer, examples of the inorganic oxide contained in the inorganic oxide layer include aluminum oxide, silicon oxide, magnesium oxide, tin oxide, etc. 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. Also, from the viewpoint of excellent tensile stretchability during processing, the inorganic oxide layer is preferably a layer using silicon oxide. By using the inorganic oxide layer, a very thin layer within a range that does not affect the recyclability of the laminate 1 can provide high barrier properties.

[0080] When the vapor deposition layer 50b is an inorganic oxide layer using silicon oxide, it is desirable that the O / Si ratio of the inorganic oxide layer is 1.7 or more. When the O / Si ratio is 1.7 or more, the content ratio of metallic Si is suppressed and good transparency is easily obtained. Also, the O / Si ratio is preferably 2.0 or less. When the O / Si ratio is 2.0 or less, the crystallinity of SiO becomes high and it is possible to prevent the inorganic oxide layer from becoming too hard, and good tensile resistance can be obtained. Thereby, it is possible to suppress the occurrence of cracks in the inorganic oxide layer when laminating the barrier coat layer 50c. Also, although the outermost layer 10 may shrink due to heat during boiling or retort processing even after being formed into a packaging bag, when the O / Si ratio is 2.0 or less, the inorganic oxide layer easily follows the above shrinkage, and it is possible to suppress a decrease in barrier properties. From the viewpoint of obtaining these effects more sufficiently, the O / Si ratio of the inorganic oxide layer is preferably 1.75 or more and 1.9 or less, and more preferably 1.8 or more and 1.85 or less.

[0081] When the vapor deposition layer 50b 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 measuring apparatus can be an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., trade name: JPS-90MXV), the X-ray source can use non-monochromatized MgKα (1253.6 eV), and the measurement can be performed with an X-ray output of 100 W (10 kV - 10 mA). For quantitative analysis to obtain the O / Si ratio, relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used.

[0082] The thickness of the vapor deposition layer 50b is, for example, 5 nm or more and 80 nm or less. When the thickness of the vapor deposition layer 50b is 5 nm or more, sufficient water vapor barrier properties can be obtained. Also, when the thickness of the vapor deposition layer 50b is 80 nm or less, cracking due to deformation caused by internal stress of the thin film can be suppressed, and a decrease in water vapor barrier properties can be suppressed. Note that when the thickness of the vapor deposition layer 50b exceeds 80 nm, the cost tends to increase due to an increase in the amount of material used and a longer film formation time, etc., so it is not preferable from an economic perspective. From the same perspective as above, the thickness of the vapor deposition layer 50b may be 20 nm or more and 40 nm or less.

[0083] The vapor deposition layer 50b can be formed, for example, by vacuum film formation. In vacuum film formation, a physical vapor deposition method or a chemical vapor deposition method can be used. Examples of the physical vapor deposition method include, but are not limited to, vacuum evaporation, sputtering, ion plating, etc. Examples of the chemical vapor deposition method include, but are not limited to, thermal CVD, plasma CVD, photo CVD, etc.

[0084] In the above-mentioned vacuum film formation, a resistance heating type vacuum evaporation method, an EB (Electron Beam) heating type vacuum evaporation method, an induction heating type vacuum evaporation method, a sputtering method, a reactive sputtering method, a dual magnetron sputtering method, a plasma chemical vapor deposition method (PECVD method), etc. are particularly preferably used. However, considering productivity, at present, the vacuum evaporation method is the most excellent. As the heating means of the vacuum evaporation method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method.

[0085] <Barrier coating layer 50c> The barrier coating layer 50c is a coating layer (gas barrier coating layer) having gas barrier properties and is provided on the vapor deposition layer 50b. When the barrier layer 50 has the barrier coating layer 50c, the adhesiveness between the sealant layer 70 and the intermediate layer 40 via the second adhesive layer 60 tends to be high. As a result, the internal pressure applied to the sealant layer 70 is dispersed throughout the entire laminate 1. As a result, the packaging bag obtained from the laminate 1 is less likely to be broken due to the pressure from the inside of the packaging bag. The barrier coating layer 50c is, for example, a layer formed using a gas barrier coating composition (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 their hydrolyzates.

[0086] From the viewpoint of more sufficiently maintaining the gas barrier property after heat water treatment such as retort treatment, the coating agent preferably contains at least a silane coupling agent or its hydrolyzate, 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 still more preferably contains a hydroxyl group-containing polymer compound or its hydrolyzate, a metal alkoxide or its hydrolyzate, and a silane coupling agent or its hydrolyzate. The coating agent can be prepared by mixing, for example, a solution in which a hydroxyl group-containing polymer compound, which is a water-soluble polymer, is dissolved in an aqueous (water or water / alcohol mixture) solvent, with a metal alkoxide and a silane coupling agent that have been directly or pre-hydrolyzed.

[0087] Each component contained in the coating agent for forming the barrier coat layer 50c will be described in detail. Examples of the hydroxyl group-containing polymer compound used in the coating agent include polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, and the like. Among these, when polyvinyl alcohol (PVA) is used in the coating agent of the barrier coat layer 50c, it is preferable because the gas barrier property is particularly excellent.

[0088] From the viewpoint of obtaining excellent gas barrier property, the barrier coat layer 50c is preferably formed from a composition containing at least one selected from the group consisting of a metal alkoxide represented by the following general formula (I) and its hydrolyzate. M(OR 1 ) m (R 2 ) 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, 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, Zr. m is an integer of 1 to n. Note that R 1 or R2 When there are a plurality of R's 1 among themselves or R 2 among themselves may be the same or different.

[0089] Specific examples of the metal alkoxide include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], and the like. Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in an aqueous solvent after hydrolysis.

[0090] 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. R 13 represents a monovalent organic functional group, and p represents an integer of 1 to 3. When there are a plurality of R's 11 or R 12 among themselves or R 11 among themselves may be the same or different. Examples of the monovalent organic functional group represented by R 12 include a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or a monovalent organic functional group containing an isocyanate group. 13

[0091] Specific examples of the silane coupling agent include silane coupling agents such as vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0092] The silane coupling agent may also be a polymer obtained by polymerizing the compound represented by the general formula (II). As the polymer, a trimer is preferable, and more preferably 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate. This is a polycondensate of 3-isocyanatealkylalkoxysilane. It is known that 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate loses its chemical reactivity at the isocyanate part, but its reactivity is ensured by the polarity of the nurate part. Generally, it is added to adhesives and the like in the same manner as 3-isocyanatealkylalkoxysilane and is known as an adhesion improver. Therefore, by adding 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate to a hydroxyl group-containing polymer compound, the water resistance of the gas barrier coating layer can be improved by hydrogen bonding. 3-Isocyanatealkylalkoxysilane has high reactivity and low liquid stability, while 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate is not water-soluble due to the polarity of the nurate part, but is easily dispersed in an aqueous solution and can keep the liquid viscosity stable. Also, the water resistance performance is equivalent to that of 3-isocyanatealkylalkoxysilane and 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate.

[0093] 1,3,5-Tris(3-trialkoxysilylalkyl)isocyanurate may be produced by thermal condensation of 3-isocyanatopropylalkoxysilane, and may contain 3-isocyanatopropylalkoxysilane as a raw material, but there are no particular problems. More preferably, it is 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate, and even more preferably 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate. This methoxy group has a high hydrolysis rate, and those containing a propyl group can be obtained relatively inexpensively, so 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is practically advantageous.

[0094] In addition, to the coating agent, within a range that does not impair the gas barrier properties, it is also possible to add an isocyanate compound or known additives such as a dispersant, a stabilizer, a viscosity modifier, and a colorant as necessary.

[0095] The thickness of the barrier coating layer 50c is preferably 50 to 1000 nm, and more preferably 100 to 500 nm. When the thickness of the barrier coating layer 50c is 50 nm or more, there is a tendency to obtain more sufficient gas barrier properties, and when it is 1000 nm or less, there is a tendency to maintain sufficient flexibility.

[0096] The coating liquid for forming the barrier coating layer 50c can be applied, for example, by dipping method, roll coating method, gravure coating method, reverse gravure coating method, air knife coating method, comma coating method, die coating method, screen printing method, spray coating method, gravure offset method, etc. The coating film formed by applying this coating liquid can be dried, for example, by hot air drying method, hot roll drying method, high frequency irradiation method, infrared irradiation method, UV irradiation method, or a combination thereof.

[0097] When drying the above coating film, the temperature can be, for example, 50 to 150°C, and preferably 70 to 100°C. By setting the temperature during drying within the above range, the occurrence of cracks in the vapor deposition layer 50b and the barrier coat layer 50c can be further suppressed, and excellent barrier properties can be exhibited.

[0098] The barrier coat layer 50c may be formed using a coating agent containing a polyvinyl alcohol-based resin and a silane compound. Acid catalysts, alkali catalysts, photoinitiators, etc. may be added to the coating agent as necessary.

[0099] The polyvinyl alcohol-based resin is as described above. Examples of the silane compound include silane coupling agents, polysilazanes, siloxanes, etc., and specifically, tetramethoxysilane, tetraethoxysilane, glycidoxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, hexamethyldisilazane, etc. may be mentioned.

[0100] (Sealant layer 70) The sealant layer 70 is a layer that imparts heat-sealing properties in the laminate 1. From the viewpoint of recyclability of the laminate 1, etc., the sealant layer 70 may contain a polypropylene film and may be composed of a polypropylene film.

[0101] The polypropylene film may be an acid-modified polypropylene film obtained by graft-modifying polypropylene using an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, etc. As the polypropylene, polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-α-olefin copolymer, etc. can be used. From the viewpoint of environmental suitability, the polypropylene film may contain a biomass-derived polypropylene resin.

[0102] The content of polypropylene may be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass based on the total amount of the sealant layer 70.

[0103] From the viewpoint of enhancing the sealing property by heat sealing, the polypropylene film constituting the sealant layer 70 is preferably an unstretched polypropylene film.

[0104] Various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent may be added to the polypropylene film constituting the sealant layer 70.

[0105] The thickness of the sealant layer 70 is determined by factors such as the mass of the content and the shape of the packaging bag, but may generally be a thickness of 30 to 150 μm, or may be a thickness of 50 to 80 μm.

[0106] When the sealant layer is oven-heated under the conditions of 150°C for 15 minutes, the heat shrinkage rate of MD obtained by the above formula (1) is preferably 0.9% or less, and more preferably 0.4% or less, because the oxygen barrier property after retort treatment is further improved. When the sealant layer is oven-heated under the conditions of 150°C for 15 minutes, the heat shrinkage rate of TD obtained by the above formula (2) is preferably 0.5% or less because the oxygen barrier property after retort treatment is further improved. The heat shrinkage rate of the above MD may be, for example, 0.1% or more. The heat shrinkage rate of the above TD may be, for example, 0.2% or more.

[0107] As a method for forming the sealant layer 70, 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 curable or two-component curable urethane-based adhesive, a non-solvent dry lamination method in which a film-like sealant layer is bonded using a solventless adhesive, an extrusion lamination method in which the above-mentioned polypropylene is heated and melted, extruded in a curtain shape, and bonded, etc. can all be formed by known lamination methods.

[0108] Among the above forming methods, the dry lamination method is preferable because it has high resistance to retort processing, particularly high-temperature hot water treatment at 120°C or higher. On the other hand, if it is used for applications where the packaging bag is treated at a temperature of 85°C or lower, the lamination method is not particularly limited.

[0109] The proportion of the total mass of polypropylene in the laminate 1 is 90% by mass or more. Thereby, 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 content of polyolefin in the laminate 1 may be 92.5% by mass or more, and may be 95% by mass or more based on the total amount of the laminate 1.

[0110] {Second Embodiment} Hereinafter, the gas barrier laminate according to the second embodiment will be described. FIG. 2 is a schematic cross-sectional view showing the laminate according to this embodiment. As shown in FIG. 2, the laminate 2 is different from the laminate 1 in that the intermediate layer 40 has a multilayer structure including a first skin layer 40a, a core layer 40b, and a second skin layer 40c. Other points may be the same as those of the gas barrier laminate according to the first embodiment.

[0111] From the viewpoint of enhancing the heat resistance of the intermediate layer 40, the polypropylene used for the core layer 40b may be crystalline polypropylene, and from the viewpoint of further improving the heat resistance for heat sterilization treatment, it may be homopolypropylene which is a homopolymer of propylene. However, within a range that does not significantly impair the effects of the present disclosure, a random copolymer of propylene and α-olefin, or a mixture of the copolymer and homopolypropylene may be used.

[0112] A first skin layer 40a is provided on one surface of the core layer 40b, and a second skin layer 40c is provided on the other surface. Both surfaces of the intermediate layer 40 may be formed by the first skin layer 40a and the second skin layer 40c. Other layers may be provided between the core layer 40b and the first skin layer 40a, but the core layer 40b and the first skin layer 40a may be in contact without passing through other layers. Other layers may be provided between the core layer 40b and the second skin layer 40c, but the core layer 40b and the second skin layer 40c may be in contact without passing through other layers.

[0113] The polypropylene used for the first skin layer 40a and the second skin layer 40c may contain a copolymer of propylene and other monomers from the viewpoint of improving the adhesion to the core layer 40b. As the other monomer, for example, α-olefins such as ethylene, 1-butene, and 1-hexene may be used. The copolymer may be a random copolymer. The polypropylene used for the first skin layer 40a and the second skin layer 40c may be homopolypropylene which is a homopolymer of propylene from the viewpoint of easy peelability.

[0114] When the first skin layer 40a contains homopolypropylene, the wettability of the first skin layer 40a is preferably 29 dyne or more. Thereby, the bag breakage resistance and the vibration resistance tend to be further improved. When the first skin layer 40a contains homopolypropylene, the wettability of the first skin layer 40a is preferably 31 dyne or less. Thereby, the peelability of the printing layer tends to be further improved.

[0115] When the first skin layer 40a contains a copolymer, the wettability of the first skin layer 40a is preferably 30 dyne or more. Thereby, the peelability of the printing layer tends to be further improved. When the first skin layer 40a contains homopolypropylene, the wettability of the first skin layer 40a is preferably 31 dyne or less. Thereby, the peelability of the printing layer tends to be further improved.

[0116] The thicknesses of both the first skin layer 40a and the second skin layer 40c may each be 0.1 μm or more. If this thickness is 0.1 μm or more, the first skin layer 40a, the core layer 40b, and the second skin layer 40c can be laminated uniformly, and variations in the thicknesses of the first skin layer 40a and the second skin layer 40c can be suppressed. Also, it is considered that the stress on the vapor deposition layer during heat sterilization treatment can be sufficiently relaxed, and deterioration of the barrier property can be suppressed. From such a viewpoint, the thicknesses of the first skin layer 40a and the second skin layer 40c are preferably 0.3 μm or more. On the other hand, the upper limit value of the thicknesses of the first skin layer 40a and the second skin layer 40c is not particularly limited, but from the viewpoint of more sufficiently ensuring the heat resistance of the entire intermediate layer 40, it is preferably 2.0 μm or less, more preferably 1.8 μm or less.

[0117] The ratio of the thickness of the first skin layer 40a to the thickness of the core layer 40b (thickness of the first skin layer 40a / thickness of the core layer 40b) may be from 1 / 100 to 1 / 5, or may be from 1 / 70 to 1 / 10. When the ratio of the thicknesses is within the above range, the heat resistance of the entire intermediate layer 40 can be more sufficiently ensured, and the adhesion between the layers in the barrier film and the laminate can be further enhanced.

[0118] The ratio of the thickness of the second skin layer 40c to the thickness of the core layer 40b (thickness of the second skin layer 40c / thickness of the core layer 40b) may be from 1 / 100 to 1 / 5, or may be from 1 / 70 to 1 / 10. When the ratio of the thicknesses is within the above range, the heat resistance of the entire intermediate layer 40 can be more sufficiently ensured, and the adhesion between the layers in the barrier film and the laminate can be further enhanced.

[0119] The thickness of the first skin layer 40a and the thickness of the second skin layer 40c may be the same or different. The thickness of the first skin layer 40a may be less than or equal to the thickness of the second skin layer 40c. The ratio of the thickness of the first skin layer 40a to the thickness of the second skin layer 40c (thickness of the first skin layer 40a / thickness of the second skin layer 40c) may be from 1 / 5 to 1 / 0.5, or may be from 1 / 3 to 1 / 1. When the thickness ratio is within the above range, the heat resistance of the entire intermediate layer 40 can be more sufficiently ensured, and the adhesion between the layers in the barrier film and the laminate can be further enhanced.

[0120] As described above, the gas barrier laminate according to the first and second embodiments has been described. However, the gas barrier laminate of the present disclosure is not limited to the above embodiments. For example, the gas barrier laminate may not include the anchor coat layer 50a. The gas barrier laminate of the present disclosure may not include the vapor deposition layer 50b. The gas barrier laminate of the present disclosure may not include the barrier coat layer 50c. The lamination order of the anchor coat layer 50a, the vapor deposition layer 50b, and the barrier coat layer 50c may be changed. The gas barrier laminate of the present disclosure may have the lamination order of the intermediate layer 40 and the barrier layer 50 changed in any way.

[0121] [Packaging bag] Hereinafter, a packaging bag according to an embodiment will be described. FIG. 3 is a schematic plan view of an example of the packaging bag according to the present embodiment. The packaging bag 100 includes the laminate 1. The packaging bag 100 is formed into a bag shape, for example, by sealing the ends of the folded laminate 1.

[0122] The packaging bag 100 is a three-sided bag having a main body portion 101 for containing the contents, a bent portion 102 where the laminate 1 is bent, and a seal portion 103 located at an end of the main body portion 101. The shape of the main body portion 101 is not particularly limited, and for example, it presents a rectangular shape when viewed from a predetermined direction. At least a part of the outer surface of the main body portion 101 may be printed. In the main body portion 101, for example, in addition to the contents, a specific gas such as nitrogen may be contained. The seal portion 103 is a portion where a part and another part of the sealant layer 70 provided in the laminate 1 are bonded together. In the seal portion 103, a part and another part of the sealant layer 70 provided in the laminate 1 are in close contact with each other. The seal portion 103 is formed, for example, by heating and compressing (i.e., heat-sealing) a part and another part of the sealant layer 70 provided in the laminate 1, but is not limited thereto. For example, the seal portion 103 may be formed by cold sealing or the like. In the packaging bag 100, the bent portion 102 constitutes one side of the main body portion 101, and the seal portion 103 constitutes the remaining three sides of the main body portion 101. Both ends of the bent portion 102 and the seal portion 103 overlap each other.

[0123] The packaging bag 100 may be used for applications that are subjected to a heat treatment at 80°C or higher. Examples of the heat treatment include retort treatment and boiling treatment.

[0124] Retort processing is generally a method of sterilizing microorganisms such as molds, yeasts, and bacteria by heating and pressurizing them to preserve foods, pharmaceuticals, and the like. Usually, the packaging bag containing the food or the like is heated and pressurized under the conditions of 105 to 140 °C and 0.15 to 0.30 MPa for 10 to 120 minutes. Retort apparatuses include a steam type that uses heating steam and a hot water type that uses pressurized heating water, and they are appropriately selected according to the sterilization conditions of the food or the like that is the content. Boiling treatment is a method of wet heat sterilization for preserving foods, pharmaceuticals, and the like. Usually, depending on the content, the packaging bag containing the food or the like is subjected to wet heat sterilization treatment under the conditions of 60 to 100 °C and atmospheric pressure for 10 to 120 minutes. Boiling treatment is usually performed at 100 °C or lower using a hot water tank. As methods, there are a batch type in which it is immersed in a hot water tank at a constant temperature, treated for a certain period of time, and then taken out, and a continuous type in which it is passed through the hot water tank in a tunnel type.

[0125] The height of the packaging bag may be 120 mm or more and may be 160 mm or less. The height of the packaging bag is preferably 140 mm or less, and more preferably 125 mm or less. Thereby, the volume of the content accommodated in the packaging bag is suppressed, and while maintaining the ease of peeling of the printing layer, the bag breakage resistance and vibration resistance tend to be further improved.

[0126] The width of the packaging bag may be 80 mm or more and may be 120 mm or less. The width of the packaging bag is preferably 100 mm or less, and more preferably 90 mm or less. Thereby, the volume of the content accommodated in the packaging bag is suppressed, and while maintaining the ease of peeling of the printing layer, the bag breakage resistance and vibration resistance tend to be further improved.

[0127] The volume of the packaging bag may be, for example, 30 mL or more, 40 mL or more, or 50 mL or more. The volume of the packaging bag is preferably 90 mL or less, more preferably 70 mL or less, and even more preferably 50 mL or less. Thereby, the volume of the content accommodated in the packaging bag is suppressed, and while maintaining the ease of peeling of the printing layer, the bag breakage resistance and vibration resistance tend to be further improved.

[0128] The packaging bag can contain materials derived from biomass in one or more of the outermost layer, the intermediate layer, the printing layer, the adhesive layer, and the sealant layer. The biomass content of the packaging bag is preferably 5% or more, more preferably 10% or more, and even more preferably 20% or more. If the biomass content is within the above range, the amount of petroleum-derived plastics used can be reduced, and the environmental impact can be decreased. The biomass content can be calculated and evaluated by measuring the concentration of radiocarbon (C14) in the carbon derived from biomass. Also, from the perspective of the physical properties of the packaging bag, in order to maintain the mechanical properties of the packaging bag, it is preferably 100% or less, more preferably 80% or less, and even more preferably 60% or less.

[0129] As described above, the packaging bag according to one embodiment has been explained. However, the packaging bag of the present disclosure is not limited to the above embodiment. For example, the packaging bag may be a standing pouch-shaped packaging bag, a two-side bag, a four-side bag, a clasp bag, or a gusset bag. Also, laminate 2 may be used instead of laminate 1.

[0130] [Package] Hereinafter, a package according to one embodiment will be described. The package is obtained by accommodating the contents in the packaging bag 100. That is, the package includes the packaging bag 100 and the contents accommodated in the packaging bag. The package may be one subjected to retort processing.

[0131] Examples of the contents include foods and pharmaceuticals.

Examples

[0132] Hereinafter, the examples of the present disclosure will be specifically described. However, the present disclosure is not limited to the following examples.

[0133] [Materials] {Outermost layer and intermediate layer} The following OPP (A) to (C) were prepared as materials for the outermost layer and the intermediate layer. For any of these materials, the heat shrinkage rate determined by formula (1) at 150°C for 15 minutes was 7% or less, and the heat shrinkage rate determined by formula (2) at 150°C for 15 minutes was 5% or less. The method for measuring the heat shrinkage rate will be described later.

[0134] (OPP(A)) Homopolypropylene resin was prepared as the material for the first skin layer and the second skin layer, and homopolypropylene resin was prepared as the material for the core layer. After co-extruding these resins, a film with a total thickness of 20 μm was produced by biaxial stretching. The thicknesses of both the first skin layer and the second skin layer were 0.7 μm, and the thickness of the core layer was 18.6 μm.

[0135] (OPP(B)) A resin containing a copolymer of 97 mol% of polypropylene and 3 mol% of α-olefin (ethylene) was prepared as the material for the first skin layer and the second skin layer, and homopolypropylene resin was prepared as the material for the core layer. After co-extruding these resins, a film with a total thickness of 20 μm was produced by biaxial stretching. The thicknesses of both the first skin layer and the second skin layer were 0.7 μm, and the thickness of the core layer was 18.6 μm.

[0136] (OPP(C)) A biaxially stretched homopolypropylene film (thickness 20 μm) was used.

[0137] {Sealant layer} An unstretched polypropylene film (thickness: 60 μm, heat shrinkage rate determined by formula (1) at 150°C for 15 minutes: 0.4% or less) was used as the sealant layer.

[0138] {First adhesive layer and second adhesive layer} A two-component urethane-based adhesive with a mass ratio of the main agent to the curing agent (main agent: curing agent) = 7.4:1 and the main component of the curing agent being isophorone diisocyanate (IPDI) was used as the material for the first adhesive layer and the second adhesive layer. The main component means a component that occupies more than 50% by mass based on the total amount of the curing agent.

[0139] {Preparation of Composition for Anchor Coat Layer Formation} A mixed solution was produced by mixing γ-isocyanatopropyltrimethoxysilane and acrylic polyol at a ratio of 1:5 and stirring. Subsequently, tolylene diisocyanate (TDI) was added to the above mixed solution such that the number of NCO groups of tolylene diisocyanate was equal to the number of OH groups of acrylic polyol. Then, the mixed solution was diluted with ethyl acetate to a concentration of 2% by mass. Thereby, a composition for anchor coat layer formation (anchor coat agent) was prepared.

[0140] {Preparation of Coating Liquid for Barrier Coat Layer} 10 g each of the following Liquid A, Liquid B, and Liquid C were prepared and mixed to prepare a coating liquid. Liquid A: A hydrolysis solution with a solid content of 5% by mass (in terms of SiO2) obtained by adding 72.1 g of 0.1 N hydrochloric acid to 17.9 g of tetraethoxysilane (Si(OC2H5)4) and 10 g of methanol and stirring for 30 minutes for hydrolysis. Liquid B: A 5% by mass aqueous / methanol solution of polyvinyl alcohol (mass ratio of water:methanol is 95:5). Liquid C: A hydrolysis solution obtained by diluting 1,3,5-tris(3-trialkoxysilylpropyl) isocyanurate with a mixed solution of water / isopropyl alcohol (mass ratio of water:isopropyl alcohol is 1:1) to a solid content of 5% by mass.

[0141] [Manufacture of Laminated Body] (Example 1) Both main surfaces of OPP(A) (intermediate layer) were subjected to corona treatment. The corona treatment was carried out at a discharge amount of 8 W·min / m 2 (strong treatment). The wettability of the surface was 32 dyne. A composition for anchor coat layer formation was applied onto one main surface of OPP(A) (intermediate layer) to form a coating film, and the coating film was dried at 60 °C. Thereby, an anchor coat layer with a coating amount of 0.1 g / m 2 was formed. Next, a transparent vapor deposition layer (silica vapor deposition layer) made of silicon oxide with a thickness of 30 nm was formed by a vacuum vapor deposition apparatus using an electron beam heating method.

[0142] Next, a coating liquid was applied onto the vapor deposition layer using a bar coat to form a coating film. By drying the coating film at 100°C, a barrier coat layer with a thickness of 300 nm was formed on the vapor deposition layer. Thereby, a first laminate (layer structure: intermediate layer, anchor coat layer, vapor deposition layer, and barrier coat layer) was obtained.

[0143] One main surface of OPP(C) (the outermost layer) was subjected to corona treatment. The corona treatment was carried out at a discharge amount of 30 W·min / m 2 The surface wettability was 32 dyne. A printing layer (thickness: 1.1 μm) was formed on the main surface subjected to corona treatment by the gravure printing method using a urethane-based resin ink.

[0144] An adhesive was applied to the surface on the intermediate layer side of the first laminate to form a coating film. The coating film was heated to remove the solvent. Then, the first laminate and the second laminate were bonded together via the adhesive by applying pressure. At this time, they were bonded together so that the intermediate layer and the printing layer faced each other. By curing the adhesive (curing temperature: 40°C, curing time: 120 hours), a first adhesive layer (thickness: 2.7 μm) was formed. Thereby, a third laminate (layer structure: outermost layer, printing layer, first adhesive layer, intermediate layer, anchor coat layer, vapor deposition layer, and barrier coat layer) was obtained.

[0145] The third laminate and the sealant layer were bonded together via an adhesive so that the barrier coat layer and the sealant layer faced each other. By curing the adhesive (curing temperature: 40°C, curing time: 120 hours), a second adhesive layer (thickness: 2.7 μm) was formed. Thereby, a gas barrier laminate (layer structure: outermost layer, printing layer, first adhesive layer, intermediate layer, anchor coat layer, vapor deposition layer, barrier coat layer, second adhesive layer, and sealant layer) was obtained.

[0146] In each of the examples and comparative examples, the wettability of the surfaces of the outermost layer and the intermediate layer and the surface after corona treatment was measured according to JIS K6768 "Plastics - Films and Sheets - Method for Measuring Wetting Tension".

[0147] (Example 2) Discharge amount: 5 W·min / m 2 A gas barrier laminate was obtained in the same manner as in Example 1, except that corona treatment (weak treatment) was performed on OPP(A) (the intermediate layer) at a discharge amount of 5 W·min / m. The wettability of the corona-treated surface was 30 dyne.

[0148] (Example 3) A gas barrier laminate was obtained in the same manner as in Example 2, except that OPP(B) was used as the intermediate layer.

[0149] (Comparative Example 1) A gas barrier laminate was obtained in the same manner as in Example 1, except that OPP(B) was used as the intermediate layer.

[0150] (Comparative Example 2) A gas barrier laminate was obtained in the same manner as in Example 1, except that the method of bonding the first laminate and the second laminate was changed. Specifically, first, an adhesive was applied to the surface of the second laminate on the printing layer side to form a coating film. The coating film was heated to evaporate the solvent. Then, the first laminate and the second laminate were bonded together through the adhesive by applying pressure. At this time, they were bonded so that the intermediate layer and the printing layer faced each other.

[0151] (Comparative Example 3) Discharge amount: 5 W·min / m 2 A gas barrier laminate was obtained in the same manner as in Comparative Example 2, except that corona treatment (weak treatment) was performed on OPP(A) (the intermediate layer) at a discharge amount of 5 W·min / m. The wettability of the corona-treated surface of the intermediate layer was 30 dyne.

[0152] (Comparative Example 4) A gas barrier laminate was obtained in the same manner as in Comparative Example 3, except that OPP(B) was used as the intermediate layer.

[0153] (Comparative Example 5) A gas barrier laminate was obtained in the same manner as in Comparative Example 2, except that OPP(B) was used as the intermediate layer.

[0154] (Comparative Example 6) A gas barrier laminate was obtained in the same manner as in Example 3, except that the corona treatment was not performed on the first laminate. The wettability of the surface of the first laminate was 28 dyne.

[0155] (Comparative Example 7) A gas barrier laminate was obtained in the same manner as in Example 3, except that the corona treatment was not performed on OPP(C) (the outermost layer).

[0156] (Example 4) A gas barrier laminate was obtained in the same manner as in Example 1, except that OPP(B) was used as the outermost layer.

[0157] (Example 5) A gas barrier laminate was obtained in the same manner as in Example 2, except that OPP(B) was used as the outermost layer.

[0158] (Example 6) A gas barrier laminate was obtained in the same manner as in Example 3, except that OPP(B) was used as the outermost layer.

[0159] (Comparative Example 8) A gas barrier laminate was obtained in the same manner as in Comparative Example 2, except that OPP(B) was used as the outermost layer.

[0160] (Comparative Example 9) A gas barrier laminate was obtained in the same manner as in Comparative Example 3, except that OPP(B) was used as the outermost layer.

[0161] (Comparative Example 10) A gas barrier laminate was obtained in the same manner as in Comparative Example 4, except that OPP(B) was used as the outermost layer.

[0162] [Adhesion Strength Measurement] The gas barrier laminate was cut into strips 15 mm wide to obtain measurement samples. T-peel testing was performed at 23 °C using a tensile testing machine at a peeling rate of 100 mm / min with the measurement location between the outermost layer and the printing layer of the measurement sample. The adhesion strength was measured for three measurement samples. The results are shown in Table 1. The three values shown in Table 1 are the adhesion strengths obtained for each of the three samples.

[0163] The adhesion strength between the first adhesive layer and the intermediate layer was also measured in the same manner as the adhesion strength between the outermost layer and the printing layer. The results are shown in Table 1. When an interface other than the measurement target interface peeled during the measurement of the adhesion strength, an OPP tape was attached to the peeled interface for reinforcement and the measurement was performed.

[0164] [Peelability Evaluation] Measurement samples (1.0 cm × 1.0 cm) were cut out from the laminates of each example and comparative example. The measurement samples were immersed in a 4.0% NaOH aqueous solution heated to 90 °C. The time when the printing layer peeled off by 90% or more based on the area of the main surface of the printing layer from the outermost layer and the intermediate layer was visually confirmed. The results are shown in Table 1. During the immersion of the measurement samples, the aqueous solution was stirred at 2000 rpm.

[0165] [Burst Test] The laminates of each example and comparative example were cut to obtain two measurement samples (130 mm × 90 mm). The measurement samples were overlapped with the heat-seal layer on the inside and heat-sealed on three sides at 155 °C to obtain a packaging bag. The three heat-sealed sides of the packaging bag were cut so that the seal width was 5 mm. The packaging bag was filled with wrinkled ben cotton, and the unsealed side was heat-sealed with a heat sealer. A rubber piece (10 mm × 10 mm) was attached to the main surface of the packaging bag with double-sided tape. The needle of a burst strength tester 305-BP-J was pierced into the packaging bag from above the rubber piece. Air was fed into the packaging bag through the needle at a flow rate of 1.0 mL / min until the packaging bag burst. The state when the packaging bag burst was visually confirmed and evaluated according to the following criteria. The results are shown in Table 1.

[0166] (Criteria) A: The packaging bag tears from the place where the needle is inserted. B: The packaging bag tears from the end of the heat-sealed part.

[0167] [Vibration test] Two measurement samples (130 mm × 90 mm) were obtained by cutting the laminates of each example and comparative example. With the heat-sealing layer on the inside, the measurement samples were overlapped and heat-sealed on three sides at 155 °C to obtain a packaging bag. The three heat-sealed sides of the packaging bag were cut so that the seal width was 5 mm. A wet hood was placed in the packaging bag, and the non-heat-sealed side was heat-sealed with a heat sealer. Thus, a packaged product was obtained. A random vibration test was performed on the packaged product in accordance with JIS Z 0232:2020. The vibration test category was level 2 (equivalent to a transport distance of 2000 km). The state of the packaged product after the test was checked and evaluated according to the following criteria. The results are shown in Table 1.

[0168] (Criteria) A: No delamination is confirmed. B: Delamination is confirmed.

[0169] [Measurement of the heat shrinkage rate of the outermost layer, intermediate layer, and sealant layer] The heat shrinkage rates of OPP (A) to (C) used as the outermost layer and intermediate layer and the non-stretched polypropylene film used as the sealant layer were measured according to the following procedure.

[0170] (a) As shown in Figure 4, the film to be measured was cut out into a 200 mm × 200 mm size to obtain a measurement sample 500. (b) As shown in Figure 4, two straight lines L1 and L2 with a length of 120 mm or more parallel to the TD of the measurement sample 500 were drawn at an interval of 100 mm. (c) As shown in Figure 4, two straight lines L3 and L4 with a length of 120 mm or more parallel to the MD of the measurement sample 500 were drawn at an interval of 100 mm. (d) As shown in Fig. 4, graduations N1 to N7 were written at seven positions on the straight line L1 at intervals of 20 mm. Graduations were similarly written on the straight lines L2 to L4. At this time, when the graduations N1 to N7 on the straight line L1 and the graduations N1 to N7 on the straight line L2 were connected by straight lines respectively, the positions of the graduations on the straight lines L1 and L2 were adjusted so that the straight line would be parallel to MD. Also, when the graduations N1 to N7 on the straight line L3 and the graduations N1 to N7 on the straight line L4 were connected by straight lines respectively, the positions of the graduations on the straight lines L3 and L4 were adjusted so that the straight line would be parallel to TD. (e) On a glass plate in an oven heated to a predetermined temperature (150 °C), 500 measurement samples placed on a Teflon (registered trademark) sheet were placed and heated for 15 minutes. After heating, the measurement samples 500 were taken out of the oven and left at room temperature (25 °C) for 30 minutes. (f) The straight-line distance between the graduation N1 (the intersection of L1 and N1) on the straight line L1 and the graduation N1 (the intersection of L2 and N1) on the straight line L2 was measured as the MD length before and after heating, and the MD thermal shrinkage rate was obtained by the following formula (1). Similarly, the MD thermal shrinkage rates at the positions of the graduations N1 to N7 were obtained, and their average value was taken as the MD thermal shrinkage rate of the measurement sample 500. MD thermal shrinkage rate (%) = (MD length before heating - MD length after heating) / MD length before heating × 100 …(1) (g) The straight-line distance between the graduation N1 (the intersection of L3 and N1) on the straight line L3 and the graduation N1 (the intersection of L4 and N1) on the straight line L4 was measured as the TD length before and after heating, and the TD thermal shrinkage rate was obtained by the following formula (2). Similarly, the TD thermal shrinkage rates at the positions of the graduations N1 to N7 were obtained, and their average value was taken as the TD thermal shrinkage rate of the measurement sample 500. TD thermal shrinkage rate (%) = (TD length before heating - TD length after heating) / TD length before heating × 100 …(2)

[0171]

Table 1

Explanation of symbols

[0172] 1, 2... laminate, 10... outermost layer, 20... printing layer, 30... first adhesive layer, 40... intermediate layer, 40a... first skin layer, 40b... core layer, 40c... second skin layer, 50... barrier layer, 50a... anchor coat layer, 50b... vapor deposition layer, 50c... barrier coat layer, 60... second adhesive layer, 70... sealant layer, 100... packaging bag.

Claims

1. An outermost layer, a printing layer, a first adhesive layer, an intermediate layer, a second adhesive layer, a sealant layer, A laminate having a laminated structure including these in this order, wherein the outermost layer, the intermediate layer, and the sealant layer contain polypropylene, the content of the polypropylene is 90% by mass or more based on the total amount of the laminate, the adhesion strength between the outermost layer and the printing layer is 0.5 to 0.8 N / 15 mm, the adhesion strength between the first adhesive layer and the intermediate layer is 0.5 to 0.8 N / 15 mm. A laminate.

2. Further comprising a barrier layer, The laminate according to claim 1, wherein the barrier layer has a barrier coat layer.

3. The laminate according to claim 2, wherein the barrier layer has an anchor coat layer, a vapor deposition layer, and the barrier coat layer in this order from the intermediate layer side.

4. The laminate according to claim 2, wherein the barrier layer is located between the intermediate layer and the second adhesive layer.

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

6. The laminate according to claim 1, wherein the thicknesses of the first adhesive layer and the second adhesive layer are 0.5 μm or more and 3.5 μm or less.

7. The laminate according to claim 1, wherein the ratio of the thickness of the first adhesive layer to the thickness of the printing layer (thickness of the first adhesive layer / thickness of the printing layer) is less than 3.

8. The laminate according to claim 1, wherein the outermost layer and the intermediate layer contain a stretched polypropylene film, the sealant layer contains an unstretched polypropylene film.

9. The laminate according to claim 1, wherein the surface layer on the printing layer side of the outermost layer contains homopolypropylene.

10. The laminate according to claim 1, wherein the intermediate layer has a multilayer structure including a first skin layer, a core layer, and a second skin layer in this order.

11. A packaging bag containing the laminate according to any one of claims 1 to 10.

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