Packaging laminate and packaging bag

Abstract

To provide a laminate that is primarily composed of polypropylene but resists thermal deformation during bag making and also resists curling due to high retort processing.SOLUTION: Provided is a packaging laminate 100A composed of at least 90 mass% polypropylene, the packaging laminate 100A comprising at least a substrate layer 11 that includes a first polypropylene film and a sealant layer 12 that includes a second polypropylene film, wherein: the first polypropylene film is an oriented polypropylene film; the first polypropylene film and the second polypropylene film are positioned such that the respective MDs thereof substantially match; the thermal shrinkage RMD1 in the MD of the first polypropylene film is not more than 10%; the thermal shrinkage RTD1 in the TD of the first polypropylene film is not more than 12%; and the thermal shrinkage RTD2 in the TD of the second polypropylene film is less than the thermal shrinkage RTD1 but not less than 0.5%.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] As the issue of plastic waste receives worldwide attention, the demand for environmentally friendly packaging materials is increasing in order to realize a circular society. With regard to packaging materials, many global companies have set goals for better plastic resource circulation and have put forward various measures. In the United States, recycling routes from collection to reuse of polyethylene are beginning to be established. In this way, recycling efforts based on mono-materials (single material) are accelerating worldwide, and there is also a growing demand for mono-material packaging laminates, which have traditionally been achieved by combining various different materials to achieve high performance.

[0003] When changing the packaging material for retort pouches from the conventional multi-material packaging material to a mono-material packaging material made essentially of a single material, it is considered to use a laminate mainly composed of polypropylene (PP mono-material laminate) from the viewpoint of sealant properties. For example, Patent Document 1 below proposes a mono-material packaging material using polypropylene. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-040257 A Summary of the Invention [Problem to be solved by the invention]

[0005] When a PP mono-material laminate is used as a mono-material packaging material, a stretched polypropylene film is used for the base layer, which is the part that comes into direct contact with or is close to the seal bar during bag making (heat sealing), in order to provide heat resistance that does not allow it to be thermally fused to the seal bar. However, when a stretched polypropylene film is used for the base layer, the laminate may be deformed by heat, resulting in poor appearance such as curling and waviness. Such deformation (distortion) may cause failure to grip the bag or poor opening in the subsequent content filling process, and may cause a decrease in conveyability.

[0006] Furthermore, there is a demand for mono-material packaging materials in so-called high retort treatment applications in which retort treatment is performed at temperatures higher than normal retort treatment. However, as a result of the inventors' investigations, PP mono-material laminates (e.g., the laminate in Patent Document 1) tend to curl during high retort treatment at 125°C or higher.

[0007] In view of the above, an object of one aspect of the present disclosure is to provide a laminate that is mainly composed of polypropylene and is unlikely to deform due to heat during bag making and is unlikely to curl due to high-temperature retort treatment.An object of another aspect of the present disclosure is to provide a package obtained by making a bag from the above laminate. [Means for solving the problem]

[0008] Some aspects of the present disclosure provide the following [1] to

[15] .

[0009] [1] A laminate for packaging, the total amount of which is 90% by mass or more of polypropylene, A substrate layer comprising a first polypropylene film; a sealant layer comprising a second polypropylene film; the first polypropylene film is a stretched polypropylene film, The first polypropylene film and the second polypropylene film are arranged so that their MD directions are approximately aligned, When the heat shrinkage rate of a film in a predetermined direction is defined by the following formula (1), The heat shrinkage rate R in the MD direction of the first polypropylene film MD1 is 10.0% or less, The thermal shrinkage rate R in the TD direction of the first polypropylene film TD1 is 12.0% or less, The heat shrinkage rate R in the TD direction of the second polypropylene film TD2 However, the heat shrinkage rate R TD1 The laminate is smaller than 0.5%. Heat shrinkage rate in a given direction (%) = ([length in a given direction before heating] - [length in a given direction after heating at 150 ° C for 15 minutes]) / [length in a given direction before heating] × 100 ... (1)

[0010] [2] The laminate according to [1], wherein the crystallinity of the first polypropylene film measured by oblique incidence X-ray diffraction method is 80% or more in both MD and TD.

[0011] [3] The laminate according to [2], wherein the crystallinity of the first polypropylene film, as measured by oblique incidence X-ray diffraction, is 86% or more in one of the MD direction and the TD direction, and 80% or more in the other direction.

[0012] [4] The laminate according to any one of [1] to [3], wherein when the first polypropylene film is subjected to a heat treatment under the following condition (i) and then subjected to differential scanning calorimetry under the following condition (ii), at least one melting peak is observed at less than 163°C. (i) The temperature was increased from 25°C to 230°C at a rate of 10°C / min, held at 230°C for 2 minutes, then decreased from 230°C to 25°C at a rate of 10°C / min, and held at 25°C for 5 minutes. (ii) The temperature was increased from 25°C to 230°C at a rate of 10°C / min and held at 230°C for 5 minutes.

[0013] [5] The laminate according to any one of [1] to [4], wherein when the first polypropylene film is subjected to differential scanning calorimetry under the following condition (iii), at least one melting peak is observed at 167°C or higher: (iii) The temperature was increased from 25°C to 230°C at a rate of 10°C / min and held at 230°C for 2 minutes.

[0014] [6] The heat shrinkage rate R of the first polypropylene film MD1 and the heat shrinkage rate R TD1 The laminate according to any one of [1] to [5], wherein each of the above properties is 7.0% or less.

[0015] [7] a third intermediate layer including a polypropylene film is provided between the base layer and the sealant layer; The first polypropylene film, the second polypropylene film, and the third polypropylene film are arranged so that their MD directions are approximately aligned, When the heat shrinkage rate of the film in a predetermined direction is defined by the above formula (1), The thermal shrinkage rate R in the TD direction of the third polypropylene film TD3 However, the heat shrinkage rate R TD2 The laminate according to any one of [1] to [6], wherein the difference is greater than or equal to 12.0%.

[0016] [8] The laminate according to [7], wherein at least one of the base layer and the intermediate layer includes an inorganic oxide layer and a gas barrier coating layer coating the inorganic oxide layer.

[0017] [9] The first polypropylene film and the third polypropylene film each have a thickness of 18 to 30 μm; The laminate according to [7] or [8], wherein the second polypropylene film has a thickness of 50 to 100 μm.

[0018]

[10] The laminate according to any one of [7] to [9], wherein the base layer and the intermediate layer are bonded to each other with an adhesive layer having a thickness of 0.5 to 4 μm.

[0019]

[11] The laminate according to any one of [7] to

[10] , wherein the intermediate layer and the sealant layer are attached to each other with an adhesive layer having a thickness of 0.5 to 4 μm.

[0020]

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

[11] , wherein the first polypropylene film is a biaxially oriented polypropylene film.

[0021]

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

[12] , wherein the second polypropylene film is a non-oriented polypropylene film.

[0022]

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

[13] , which is for a retort pouch.

[0023]

[15] A packaging bag produced by forming the laminate according to any one of [1] to

[14] . Effect of the Invention

[0024] According to the present disclosure, it is possible to provide a laminate that is mainly composed of polypropylene and is unlikely to deform due to heat during bag making and is unlikely to curl due to high-temperature retort treatment. Another aspect of the present disclosure has an object to provide a package obtained by making a bag from the above laminate. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a laminate according to one embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing a laminate according to another embodiment. [Diagram 3]FIG. 3 is a schematic diagram showing a method for measuring the thermal shrinkage rate during heating in an oven. [Figure 4] FIG. 4 is a partially enlarged view of the laminate of FIG. [Diagram 5] FIG. 5(a) to (c) are cross-sectional views of the sealed portion of the pouch, and are schematic diagrams showing the state of distortion of the pouch after heat sealing. [Figure 6] FIG. 6 is a schematic diagram showing a method for measuring the amount of curl during high retort treatment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In this specification, a numerical range indicated using "~" indicates a range including the numerical values ​​described before and after "~" as the minimum and maximum values, respectively. In addition, unless specifically stated otherwise, the units of the numerical values ​​described before and after "~" are the same. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a certain numerical range may be replaced with the upper limit or lower limit of a numerical range of another stage. In addition, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples. In addition, the upper limit and lower limit values ​​described individually can be combined arbitrarily.

[0027] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings as needed. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted. In addition, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0028] <Laminate> 1 includes a base material layer 11 and a sealant layer 12. The base material layer 11 and the sealant layer 12 are bonded to each other by an adhesive layer S.

[0029] The base layer 11 and the sealant layer 12 each contain a polypropylene film. In this specification, a "polypropylene film" refers to a film composed mainly of polypropylene resin, and contains, for example, 90% by mass or more of polypropylene resin as a total amount of the film. Hereinafter, the polypropylene film contained in the base layer 11 is referred to as a "first polypropylene film," and the polypropylene film contained in the sealant layer 12 is referred to as a "second polypropylene film."

[0030] In the laminate 100A, the first polypropylene film and the second polypropylene film are arranged so that their MD (Machine Direction) directions are approximately the same (i.e., the angle difference is within ±15°.) In other words, in the laminate 100A, the MD direction of the first polypropylene film is approximately the same as the MD direction of the second polypropylene film, and the TD (Transverse Direction) of the first polypropylene film is approximately the same as the TD direction of the second polypropylene film.

[0031] The MD direction of the film can be determined by measuring the orientation angle using, for example, a retardation measuring device (product name: KOBRA, manufactured by Oji Scientific Instruments Co., Ltd.), and the MD direction and the TD direction can be distinguished from the orientation angle. When the film is a stretched polypropylene film, the direction in which the molecular chains are oriented is considered to be the TD direction.

[0032] 2 includes, in this order, a base material layer 11, an intermediate layer 13, and a sealant layer 12. The base material layer 11 and the intermediate layer 13, and the intermediate layer 13 and the sealant layer 12 are bonded together with an adhesive layer S, respectively.

[0033] The intermediate layer 13 includes a polypropylene film. Hereinafter, the polypropylene film included in the intermediate layer 13 is referred to as a "third polypropylene film." The details of the base material layer 11 and the sealant layer 12 are the same as those of the laminate 100A, and each includes a first polypropylene film and a second polypropylene film.

[0034] In the laminate 100B, the first polypropylene film, the second polypropylene film, and the third polypropylene film are arranged so that their MD directions are approximately aligned (i.e., the angle difference is within ±15°.) In other words, the MD direction of the first polypropylene film, the MD direction of the second polypropylene film, and the MD direction of the third polypropylene film are approximately aligned, and the TD direction of the first polypropylene film, the TD direction of the second polypropylene film, and the TD direction of the third polypropylene film are approximately aligned.

[0035] The thickness of the laminate (100A, 100B) may be 90 to 150 μm, or may be 95 to 140 μm, or 100 to 130 μm.

[0036] The laminate (100A, 100B) is a laminate (laminate for packaging) used as a material for packaging bags, and 90% or more of the total amount is polypropylene. Here, "90% of the total amount is polypropylene" is synonymous with the content of polypropylene in the laminate (100A, 100B) being 90% by mass or more based on the total amount of the laminate. Therefore, the laminate has excellent recyclability and is suitably used as a (mono-material) packaging material substantially made of a single material. From the viewpoint of further improving recyclability, the content of polypropylene in the laminate may be 95% by mass or more based on the total amount of the laminate. The upper limit of the polypropylene content is 100% by mass.

[0037] In this specification, the "polypropylene content" means the content of polypropylene resin contained in the laminate. However, when the resin is a copolymer containing a copolymerization monomer other than propylene as a monomer unit, the amount of the monomer unit derived from the copolymerization monomer is not included in the polypropylene content, and the amount of the monomer unit derived from the propylene monomer is defined as the polypropylene content. The polypropylene content can be measured according to Raman spectroscopy.

[0038] When the heat shrinkage rate in a predetermined direction (MD or TD) of a film is defined by the following formula (1), in the laminate 100A shown in FIG. 1, the heat shrinkage rate R MD1 , the thermal shrinkage rate R in the TD direction of the first polypropylene film TD1 , and the thermal shrinkage rate R of the second polypropylene film in the TD direction TD2 satisfies the following condition (I), and in the laminate 100B shown in FIG. MD1 , R TD1 , and R TD2 In addition to satisfying the following condition (I), the thermal shrinkage rate R TD3 satisfies the following condition (II). Heat shrinkage rate in a given direction (%) = ([length in a given direction before heating] - [length in a given direction after heating at 150 ° C for 15 minutes]) / [length in a given direction before heating] × 100 ... (1) Condition 10.0% ≧ R MD1 12.0% ≧ R TD1 >R TD2 ≧0.5% [Condition (II)] 12.0% ≧ R TD3 >R TD2

[0039] Specifically, the heat shrinkage rate is measured according to the following procedure. As shown in FIG. 3(a), a measurement sample 200 is obtained by cutting the film to be measured into a size of 200 mm×200 mm. (b) As shown in FIG. 3, two straight lines L1 and L2, each having a length of 120 mm or more and parallel to the TD direction of the measurement sample 200, are written on the surface of the measurement sample 200 with an interval of 100 mm. (c) As shown in FIG. 3, two straight lines L3 and L4, each having a length of 120 mm or more and parallel to the MD direction of the measurement sample 200, are written on the surface of the measurement sample 200 with an interval of 100 mm. (d) As shown in Fig. 3, markings N1 to N7 are written at seven points at 20 mm intervals on each of the straight lines L1 to L4. At this time, the positions of the marks on the straight lines L1 and L2 are aligned so that when the marks N1 to N7 on the straight line L1 are connected to the marks N1 to N7 on the straight line L2, the lines are parallel to the MD direction. In addition, the positions of the marks on the straight lines L3 and L4 are aligned so that when the marks N1 to N7 on the straight line L3 are connected to the marks N1 to N7 on the straight line L4, the lines are parallel to the TD direction. (e) The measurement sample 200 placed on a Teflon (registered trademark) sheet is placed on a glass plate in an oven heated to 150° C. and heated for 15 minutes. After heating, the measurement sample 200 is removed from the oven and left at room temperature (25° C.) for 30 minutes. (f) The linear distance between the scale N1 (intersection of L1 and N1) of the straight line L1 and the scale N1 (intersection of L2 and N1) of the straight line L2 is measured as the MD length before and after heating, and the heat shrinkage in the MD direction is calculated according to the above formula (1). Similarly, the heat shrinkage in the MD direction at each position of the scales N2 to N7 is calculated, and the average value of the heat shrinkage in the MD direction calculated at each position of N1 to N7 is measured. The heat shrinkage in the MD direction R of sample 200 MD Let us assume that. (g) The linear distance between the scale N1 (intersection of L3 and N1) of the straight line L3 and the scale N1 (intersection of L4 and N1) of the straight line L4 is measured as the TD length before and after heating, and the thermal shrinkage in the TD direction is calculated according to the above formula (1). Similarly, the thermal shrinkage in the TD direction is calculated at each of the positions of the scales N2 to N7, and the average value of the thermal shrinkage in the TD direction calculated at each of the positions of N1 to N7 is measured. The thermal shrinkage in the TD direction R of sample 200 TD Let us assume that.

[0040] Typically, the thermal shrinkage rate of a film does not change substantially during the production process of the laminate, so the laminates 100A and 100B can be obtained by using a film that exhibits the above thermal shrinkage rate when measured alone.

[0041] The base material layer is the part that is in direct contact with or in close proximity to the heat seal bar during bag making (heat sealing), and is the part that is particularly exposed to heat among the layers of the laminate. Therefore, in conventional PP monomaterial laminates, it is believed that the heat shrinkage of the base material layer causes deformation (distortion) such as curling and waviness during bag making (i.e., heat sealing). In particular, packaging materials for retort pouches use a sealant layer that has a high melting point that is high enough not to open under retort conditions, and therefore there is a tendency for higher temperatures to be applied during heat sealing, making it more likely that the above deformations occur. On the other hand, in the laminates (100A, 100B), as described above, the heat shrinkage rate R MD1 and R TD1 Since the heat shrinkage rate (MD direction heat shrinkage rate and TD direction heat shrinkage rate of the first polypropylene film) is sufficiently small, deformation due to heat during bag making is unlikely to occur. In addition, for the above reasons, the laminate (100A, 100B) is also unlikely to wrinkle during bag making. Therefore, with the laminate (100A, 100B), a package with less deformation (distortion) and wrinkles, a good appearance, and excellent transportability and workability during filling of the contents can be easily obtained.

[0042] In addition, in the sealant layer of a conventional PP monomaterial laminate, a material (sealant film) having almost no heat shrinkability is usually used. However, in the laminate (100A, 100B), as described above, the heat shrinkage rate R TD2 Since the heat shrinkage rate in the TD direction of the second polypropylene film is 0.5% or more, curling is unlikely to occur due to retort treatment (high retort treatment) at a high temperature of 125° C. or more. Therefore, the laminate can be suitably used for retort pouch applications.

[0043] Hereinafter, each layer constituting the laminate (100A, 100B) shown in FIG. 1 and FIG. 2 will be described in detail.

[0044] (base material layer) The base layer 11 is one of the layers that constitute the support, and includes a first polypropylene film. The base layer 11 is the layer that constitutes the outermost side (the outermost layer) of the laminate (100A, 100B).

[0045] The polypropylene resin constituting the first polypropylene film may be a homopolymer of propylene or a copolymer of propylene and another copolymerizing monomer. Examples of the copolymer include a propylene-ethylene random copolymer, a propylene-ethylene block copolymer, and a propylene-α-olefin copolymer. The polypropylene resin may be an acid-modified polypropylene 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. The first polypropylene film may further 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.

[0046] The first polypropylene film is a stretched polypropylene film. Since a stretched polypropylene film has excellent heat resistance, by using a stretched polypropylene film as the first polypropylene film, it is possible to prevent the base layer from being thermally fused to a heat seal bar. The stretched polypropylene film may be a film obtained by stretching using a known method such as stretching by inflation, uniaxial stretching, or biaxial stretching. The stretched polypropylene film has a thermal shrinkage rate (R MD1 and R TD1 In terms of the ease with which the above-mentioned film can be obtained, a biaxially oriented polypropylene film may be used.

[0047] The surface of the first polypropylene film may be subjected to various pretreatments such as corona treatment, plasma treatment, and flame treatment.

[0048] The thickness of the first polypropylene film is not particularly limited. Depending on the application, the thickness can be 6 to 200 μm, but from the viewpoint of reducing materials for reducing environmental load and from the viewpoint of obtaining excellent heat resistance, impact resistance and excellent gas barrier properties, it may be 9 to 60 μm, 18 to 60 μm or 9 to 50 μm. The thinner the thickness of the base layer, the easier the laminate is to shrink during heat sealing, but in the laminate according to the present embodiment, since a base layer that satisfies specific conditions is used, the shrinkage of the laminate can be suppressed even if the thickness of the base layer is thin. Therefore, the thickness of the first polypropylene film may be less than 25 μm or 20 μm or less.

[0049] The thickness of the first polypropylene film in the laminate 100A may be 36 to 60 μm, 38 to 55 μm, or 40 to 50 μm from the viewpoint of reducing the material for reducing the environmental load and obtaining excellent heat resistance, excellent impact resistance, and excellent gas barrier properties. The thickness of the first polypropylene film in the laminate 100B may be 12 to 38 μm, 18 to 30 μm, or 20 to 25 μm from the viewpoint of reducing the material for reducing the environmental load and obtaining excellent heat resistance, excellent impact resistance, and excellent gas barrier properties.

[0050] The thickness of the first polypropylene film may be 10 to 50% of the total thickness of the laminate. The thickness of the first polypropylene film in the laminate 100A may be 20 to 60%, 23 to 50%, or 25 to 40% of the total thickness of the laminate from the viewpoint of reducing the material for reducing the environmental load and from the viewpoint of obtaining excellent heat resistance, excellent impact resistance, and excellent gas barrier properties. The thickness of the first polypropylene film in the laminate 100B may be 10 to 50%, 13 to 45%, or 15 to 40% of the total thickness of the laminate from the viewpoint of reducing the material for reducing the environmental load and from the viewpoint of obtaining excellent heat resistance, excellent impact resistance, and excellent gas barrier properties.

[0051] The thickness of the first polypropylene film may be 90% or more of the thickness of the base layer 11, and the base layer 11 may consist of only the first polypropylene film.

[0052] Heat shrinkage rate R in the MD direction of the first polypropylene film MD1 The heat shrinkage ratio R is 10.0% or less, and from the viewpoint of further suppressing deformation due to heat during bag making and curling due to high retort treatment, it may be 8.0% or less, 7.0% or less, or 5.0% or less. MD1 is the thermal shrinkage rate R of the second polypropylene film in the MD direction MD2 The larger the better. Since the first polypropylene film will be the outermost layer after the bag is made, it is also required to have mechanical properties (flexibility, tensile strength, printability) and optical properties (transparency, glossiness). In order to improve these properties, it is effective to stretch the entangled polymer chains and align the crystals, that is, to cause molecular orientation, and stretching (particularly biaxial stretching) is a useful means for achieving this. When stretching is performed, heat shrinkage is unavoidable, and the heat shrinkage rate R MD1 For example, the thermal shrinkage rate R MD1 may be 1.0 to 10.0%, or may be 3.0 to 10.0%.

[0053] Heat shrinkage rate R in the TD direction of the first polypropylene film TD1 From the viewpoint of further suppressing deformation due to heat during bag making and curling due to high-speed retort treatment, the heat shrinkage ratio R may be 10.0% or less, 8.0% or less, or 7.0% or less. TD1 For example, the thermal shrinkage rate R TD1 may be 1.0 to 12.0%, or may be 3.0 to 12.0%.

[0054] In order to further suppress deformation due to heat during bag making and curling due to high retort processing, the heat shrinkage rate R MD1 and heat shrinkage rate R TD1 However, each of them may be 7.0% or less.

[0055] Heat shrinkage rate R within the above range MD1 and R TD1 The first polypropylene film having the above-mentioned properties can be obtained by molding through stretching (particularly biaxial stretching) or by using a high melting point resin as the polypropylene resin constituting the film.

[0056] The crystallinity of the first polypropylene film measured by grazing incidence X-ray diffraction may be 80% or more in both the MD and TD directions. The crystallinity may be 86% or more in one of the MD and TD directions and 80% or more in the other. The crystallinity of the first polypropylene film in the MD and TD directions can be measured by grazing incidence X-ray diffraction under the following conditions. Here, when measuring the crystallinity in the MD direction, the X-ray irradiation device and the detector are arranged so as to be aligned in a direction perpendicular to the MD direction, and when measuring the crystallinity in the TD direction, the X-ray irradiation device and the detector are arranged so as to be aligned in a direction perpendicular to the TD direction, and the measurement is performed. (Measurement conditions) Measurement equipment: X-ray diffraction equipment (Rigaku Corporation, product name: RINT TTR III) Optical system: Parallel method (detector: scintillation counter, purpose: small angle, target: sample surface) Scanning axis: 2θ / θ Measurement method: Continuous Counting unit: cps Starting angle: 3° (approximate) End angle: 35° Sampling width: 0.02° Scan speed: 4° / min Voltage: 50kV Current: 300mA Divergence vertical slit: 10mm Scattering slit: open Receiving slit: open Crystallinity calculation method: Peak separation method Analysis software: MDI JADE PRO / Version 8.6 In the diffraction pattern obtained by X-ray diffraction, the background, amorphous components, and crystalline components are separated using a profile fitting method. The crystallinity is calculated from the area under the curve (integral intensity) of the diffraction curves of the amorphous and crystalline components separated from the total scattering curve using the following formula. Xc = Ic / (Ic + Ia) × 100 Xc: Crystallinity Ic: Crystalline scattering intensity Ia: Amorphous scattering intensity

[0057] When the crystallinity of the first polypropylene film in the MD direction and the TD direction is 80% or more, the shrinkage of the laminate can be further suppressed in the heat sealing process when the laminate is made into a bag. As a result, the deformation and wrinkles of the packaging bag, as well as the pattern misalignment of the packaging bag and the deterioration of physical properties such as lamination strength can be further suppressed. Furthermore, when one of the crystallinity of the first polypropylene film in the MD direction and the TD direction is 86% or more and the other is 80% or more, the occurrence of whitening in the heat sealing process when the laminate is made into a bag can be suppressed. Therefore, the appearance and performance of the obtained packaging bag can be prevented, and troubles during transportation and filling of contents can be prevented. From the viewpoint of obtaining the above effect at a higher level, one of the crystallinity of the first polypropylene film in the MD direction and the TD direction may be 90% or more and the other may be 84% or more. In addition, the crystallinity of the first polypropylene film in the MD direction may be 80% or more, 84% or more, or 86% or more, and the crystallinity of the first polypropylene film in the TD direction may be 80% or more or 84% or more. The upper limit of the crystallinity is not particularly limited in either the MD or TD direction, and may be, for example, 95% or less. The crystallinity of the first polypropylene film in the MD and TD directions can be adjusted, for example, by the stretching conditions, molecular weight, cooling temperature, blending of a crystal nucleating agent, etc.

[0058] In addition, by using the first polypropylene film having a crystallinity of 80% or more in the MD and TD directions, the following effects can be achieved in the laminate manufacturing process. The laminate manufacturing process (lamination process) involves many processes in which heat is applied, such as corona treatment and oven processes, and the base layer may shrink during processing, which may cause misalignment of patterns and variations in laminate strength. In contrast, when a first polypropylene film having a crystallinity of 80% or more in the MD and TD directions is used, the high crystallinity suppresses the shrinkage of the base layer, and the occurrence of misalignment of patterns and variations in laminate strength can be suppressed. In addition, when a first polypropylene film having a crystallinity of 80% or more in the MD and TD directions is used, for example, the oven temperature after printing or adhesive coating can be set high, which reduces residual solvent and enables the work to be performed at a high speed, thereby improving the productivity of the laminate.

[0059] In the first polypropylene film, the difference between the crystallinity in the MD direction and the crystallinity in the TD direction measured by oblique incidence X-ray diffraction may be 4% or more, or may be 10% or less. The smaller the difference between the crystallinity in the MD direction and the crystallinity in the TD direction, the more uniformly the crystals in the base layer are oriented, and the more durable the film is. Therefore, by using a first polypropylene film in which the difference between the crystallinity in the MD direction and the crystallinity in the TD direction is 10% or less, it is possible to suppress the occurrence of deformation, whitening, and wrinkles in the packaging bag, as well as the occurrence of misalignment of the pattern of the packaging bag, deterioration of physical properties such as lamination strength, and deformation of the packaging bag. From the viewpoint of obtaining the above effect at a higher level, the difference between the crystallinity in the MD direction and the crystallinity in the TD direction may be 8% or less.

[0060] When the base layer includes a layer other than the first polypropylene film, the above-mentioned "degree of crystallinity in the MD and TD of the first polypropylene film" may be read as "degree of crystallinity in the MD and TD of the base layer." When the degree of crystallinity in the MD and TD of the base layer is within the above range, the above-mentioned effect tends to be more pronounced.

[0061] The first polypropylene film may have at least one melting peak observed below 163°C when heat-treated under the following condition (i) and then subjected to differential scanning calorimetry under the following condition (ii). When a plurality of melting peaks are observed, it is sufficient that at least one of the melting peaks is observed below 163°C, and the other melting peaks may be observed at 163°C or higher, or all of the melting peaks may be observed below 163°C. When a plurality of melting peaks are observed, it is preferable that the temperature at which 30% or more of the entire first polypropylene film melts is below 163°C. Whether or not 30% or more of the entire first polypropylene film has melted can be determined by comparing the melting peak areas. In addition, only one melting peak may be observed, and no melting peak may be observed at 163°C or higher. (i) The temperature was increased from 25°C to 230°C at a rate of 10°C / min, held at 230°C for 2 minutes, then decreased from 230°C to 25°C at a rate of 10°C / min, and held at 25°C for 5 minutes. (ii) The temperature was increased from 25°C to 230°C at a rate of 10°C / min and held at 230°C for 5 minutes.

[0062] The melting peak temperature measured under the above conditions indicates the melting point of the first polypropylene film material itself from which the effects of stretching and the like have been removed by heat treatment (hereinafter also referred to as the "melting point after heat treatment"). In the present disclosure, by increasing the crystallinity of the first polypropylene film without increasing the melting point of the first polypropylene film material itself, it is also possible to suppress the occurrence of distortion, whitening, and wrinkles during bag making of the laminate. From the viewpoint of making such effects more easily obtainable, the base layer may have a melting point after heat treatment measured under the above conditions of less than 163°C.

[0063] The first polypropylene film may be one in which at least one melting peak is observed at 167° C. or higher when differential scanning calorimetry is performed under the following condition (iii). The first polypropylene film may be one in which a plurality of melting peaks are observed, at least one of which is observed at 167° C. or higher and at least one other melting peak is observed below 167° C. (iii) The temperature was increased from 25°C to 230°C at a rate of 10°C / min and held at 230°C for 2 minutes.

[0064] The melting peak temperature measured under the above conditions indicates the melting point of the first polypropylene film after the influence of stretching, etc. (hereinafter, also referred to as the "melting point before heat treatment"). When the melting point of the first polypropylene film before heat treatment is 167°C or higher, the heat resistance of the first polypropylene film before heat treatment is improved, and the occurrence of distortion, whitening, and wrinkles during bag making of the laminate can be further suppressed. From the viewpoint of more easily obtaining such effects, the base layer may have a melting point before heat treatment measured under the above conditions of less than 163°C.

[0065] The melting point after the heat treatment can be adjusted, for example, by the molecular weight, stereoregularity (isotactic mesopentad fraction), blending of a crystal nucleating agent, etc. The melting point before the heat treatment can be adjusted, for example, by the stretching conditions, cooling temperature, blending of a crystal nucleating agent, etc.

[0066] The thickness of the base layer 11 may be within the range exemplified above as the thickness of the first polypropylene film.

[0067] (Sealant layer) The sealant layer 12 is a layer that imparts heat-sealing sealability to the laminate, and includes a second polypropylene film. The polypropylene resin constituting the second polypropylene film may be a homopolymer of propylene, or may be a copolymer of propylene and another copolymerization monomer. Examples of the copolymer include a propylene-ethylene random copolymer, a propylene-ethylene block copolymer, and a propylene-α-olefin copolymer. The polypropylene resin may be an acid-modified polypropylene 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. The second polypropylene film may further include various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent.

[0068] The second polypropylene film may be a stretched polypropylene film, but is preferably a non-stretched polypropylene film from the viewpoint of improving the sealability by heat sealing.

[0069] The thickness of the second polypropylene film is determined depending on the mass of the contents, the shape of the packaging bag, etc. From the viewpoint of improving the heat sealability and impact resistance in a well-balanced manner, the thickness of the second polypropylene film may be 30 to 150 μm, or may be 40 to 100 μm, 50 to 100 μm, 40 to 90 μm, 30 to 80 μm, or 50 to 80 μm.

[0070] The thickness of the second polypropylene film may be 35 to 75%, 40 to 70%, or 45 to 65% of the total thickness of the laminate, from the viewpoint of improving the heat sealability and impact resistance in a well-balanced manner.

[0071] The thickness of the second polypropylene film may be 90% or more of the thickness of the sealant layer 12, and the sealant layer 12 may consist of only the second polypropylene film.

[0072] The thermal shrinkage rate R of the second polypropylene film in the MD direction MD2 From the viewpoint of further suppressing curling due to high-temperature retort treatment, the heat shrinkage ratio R is preferably 0.5% or more. MD2 is the thermal shrinkage rate R of the first polypropylene film in the MD direction MD1 It may be smaller, for example 5.0% or less.

[0073] Thermal shrinkage rate R of the second polypropylene film in the TD direction TD2 The thermal shrinkage rate R is 0.5% or more. TD2 is the thermal shrinkage rate R of the first polypropylene film in the TD direction TD1 It may be smaller, for example 5.0% or less.

[0074] Heat shrinkage rate R within the above range MD2 and R TD2 The second polypropylene film having the above formula (I) can be obtained by molding without stretching.

[0075] In order to further suppress curling caused by high retort processing, the heat shrinkage rate R MD1 and heat shrinkage rate R MD2 The difference between MD1 -R MD2 ) is preferably smaller, and the thermal shrinkage rate R TD1 and heat shrinkage rate R TD2 The difference between TD1 -R TD2 From this perspective, the smaller the difference (R MD1 -R MD2 ) is preferably 8% or less (for example, 1% to 8%), and the difference (R TD1 -R TD2 ) is preferably 8% or less (for example, 1% to 8%).

[0076] The thickness of the sealant layer 12 may be in the range exemplified above as the thickness of the second polypropylene film.

[0077] The sealant layer 12 can be laminated on other layers by any of the known lamination methods, such as a dry lamination method in which the second polypropylene film is laminated to other layers with an adhesive (e.g., a urethane adhesive such as a one-component curing type or two-component curing type), a non-solvent dry lamination method in which the second polypropylene film is laminated to other layers with a solvent-free adhesive, and an extrusion lamination method in which the constituent material of the second polypropylene film is heated and melted, extruded into a curtain shape, and laminated. Among the above formation methods, the dry lamination method is preferred because it has high resistance to high retort treatment. On the other hand, if the packaging bag is used for an application in which it is treated at a temperature of 85°C or less, the lamination method is not particularly limited.

[0078] (Middle class) The intermediate layer 13 is located between the base material layer 11 and the sealant layer 12. Compared to the laminate 100A that does not include the intermediate layer 13, the laminate 100B is less likely to deform during bag formation.

[0079] The intermediate layer 13 includes a third polypropylene film. The third polypropylene film may be a non-stretched polypropylene film or a stretched polypropylene film. Examples of the stretched polypropylene film and the non-stretched polypropylene film include the polypropylene films exemplified in the above-mentioned first polypropylene film and the second polypropylene film. From the viewpoints of impact resistance, heat resistance, water resistance, dimensional stability, and the like, it is preferable that the third polypropylene film is a stretched film.

[0080] The thickness of the third polypropylene film may be 18 to 30 μm from the viewpoint of reducing the amount of materials used to reduce the environmental load, and from the viewpoint of obtaining excellent heat resistance, excellent impact resistance, and excellent gas barrier properties.

[0081] The thickness of the third polypropylene film may be 5 to 30% of the total thickness of the laminate from the viewpoint of reducing materials to reduce environmental impact and from the viewpoint of obtaining excellent heat resistance, excellent impact resistance, and excellent gas barrier properties.

[0082] The thickness of the third polypropylene film may be 90% or more of the thickness of the intermediate layer 13, and the intermediate layer 13 may consist of only the third polypropylene film.

[0083] The sum of the thickness of the third polypropylene film and the thickness of the first polypropylene film may be 36 to 60 μm. The sum of the thickness of the base layer 11 and the thickness of the intermediate layer 13 may be in the above range.

[0084] The ratio of the thickness of the third polypropylene film to the thickness of the first polypropylene film (thickness of the first polypropylene film / thickness of the third polypropylene film) may be 1.00 or more, may be greater than 1.00, 1.25 or more, or 1.50 or more. By making the first polypropylene film in the base layer thicker than the third polypropylene film in the intermediate layer, the thermal shrinkage of the base layer during bag making (heat sealing) and the deformation of the laminate due to this can be further suppressed. The above ratio may be, for example, 4.0 or less. From the same viewpoint, the ratio of the thickness of the intermediate layer to the thickness of the base layer may also be within the above range.

[0085] The thermal shrinkage rate R of the third polypropylene film in the MD direction MD3 From the viewpoint of further suppressing deformation due to heat during bag making and curling due to high-speed retort treatment, the heat shrinkage rate R in the MD direction of the third polypropylene film is preferably 10.0% or less, and may be 8.0% or less, 7.0% or less, or 5.0% or less. MD3 The thermal shrinkage ratio R may be 12.0% or less or 14.0% or less. MD3 is the thermal shrinkage rate R of the second polypropylene film in the MD direction MD2 The heat shrinkage ratio R of the third polypropylene film may be larger than the heat shrinkage ratio R of the third polypropylene film, for example, 1.0% or more. MD3 The thermal shrinkage rate R may be, for example, 1.0 to 10.0%. MD3 may be 3.0% or more. stomach.

[0086] Thermal shrinkage rate R of the third polypropylene film in the TD direction TD3 From the viewpoint of further suppressing deformation due to heat during bag making and curling due to high-speed retort treatment, the heat shrinkage ratio R may be 10.0% or less, 8.0% or less, or 7.0% or less. TD3 is the thermal shrinkage rate R of the second polypropylene film in the TD direction TD2 The thermal shrinkage ratio R may be larger than 1.0%, for example, 3.0% or more. TD3 may be 1.0 to 12.0%, or may be 3.0 to 12.0%.

[0087] In order to further suppress curling caused by high retort processing, the heat shrinkage rate R MD3 and heat shrinkage rate R MD2 The difference between MD3 -R MD2 ) is preferably smaller, and the thermal shrinkage rate R TD3 and heat shrinkage rate R TD2 The difference between TD3 -R TD2 From this perspective, the smaller the difference (R MD3 -R MD2 ) is preferably 8.0% or less (for example, 1.0% to 8.0%), and the difference (R TD3 -R TD2 ) is preferably 8.0% or less (for example, 1.0% to 8.0%).

[0088] The thickness of the intermediate layer 13 may be within the range exemplified above as the thickness of the third polypropylene film.

[0089] (adhesive layer) Examples of adhesive materials constituting the adhesive layer S include polyester-isocyanate resins, urethane resins, polyether resins, and the like. To use the laminate for retort pouch applications, it is preferable to use a two-component curing urethane adhesive that is resistant to retort. That is, it is preferable that the adhesive layer S is a layer made of a cured product of a two-component curing urethane adhesive. From the viewpoint of environmental consideration, the adhesive does not need to contain 3-glycidyloxypropyltrimethoxysilane (GPTMS).

[0090] The thickness of the adhesive layer S is not particularly limited, but may be, for example, 0.5 to 5 μm, or 2 to 3 μm. When the thickness of the adhesive layer S is 0.5 μm or more, the adhesion between the base layer and the intermediate layer is easily improved, and when it is 5 μm or less, the barrier property and recyclability of the laminate are easily improved. The thickness of the adhesive layer S may be 0.5 to 4 μm from the viewpoint of ensuring sufficient adhesion while making the polypropylene content in the laminate 90 mass % or more.

[0091] The substrate layer, the sealant layer, the intermediate layer, and the adhesive layer have been described above, but the configuration of each layer is not limited to the above, and the substrate layer, the sealant layer, and the intermediate layer may include layers other than the layers made of polypropylene films (first polypropylene film, second polypropylene film, third polypropylene film). Examples of layers other than the layers made of polypropylene films include coating layers such as easy-adhesion layers, inorganic oxide layers, gas barrier coating layers, and printed layers. As an example, a partial enlarged view of the laminate 100B is shown in FIG. 4. In the laminate 100B, the coating layer 16, the inorganic oxide layer 17, and the gas barrier coating layer 18 are laminated in this order on the third polypropylene film 15, and the intermediate layer 13 made of the third polypropylene film 15, the coating layer 16, the inorganic oxide layer 17, and the gas barrier coating layer 18 and the substrate layer 11 made of the first polypropylene film 14 are laminated via the adhesive layer S. The layer other than the layer made of the above polypropylene film may be provided on at least one surface of the first polypropylene film and / or on at least one surface of the third polypropylene film, but from the viewpoint of being less susceptible to the effects of heat during heat sealing, it is preferable that the layer be provided so as to be located between the first polypropylene film and the third polypropylene film, as shown in Figure 4.

[0092] The coating layer, inorganic oxide layer, gas barrier coating layer and printed layer that may be included in the base layer 11 and / or intermediate layer 13 will be described below.

[0093] [Coat layer] The coating layer may be an anchor coating layer (also called an "adhesive layer") provided between the polypropylene film and the inorganic oxide layer in order to improve the adhesion between the polypropylene film and the inorganic oxide layer. By providing the anchor coating layer between the polypropylene film and the inorganic oxide layer, two effects can be obtained: improving the adhesion performance between the polypropylene film and the inorganic oxide layer, and improving the smoothness of the polypropylene film surface. In addition, the improved smoothness makes it easier to form the inorganic oxide layer uniformly without defects, and makes it easier to exhibit high barrier properties. The anchor coating layer can be formed using an anchor coating agent.

[0094] Examples of the anchor coating agent include acrylic polyurethane resin, polyester polyurethane resin, polyether polyurethane resin, polyurethane resin formed from acid group-containing polyurethane and polyamine, etc. As the anchor coating agent, from the viewpoints of heat resistance and interlayer adhesive strength, acrylic polyurethane resin and polyester polyurethane resin are preferred.

[0095] The thickness of the coating layer 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. If the thickness of the coating layer is equal to or greater than the lower limit, more sufficient interlayer adhesive strength tends to be obtained, whereas if the thickness is equal to or less than the upper limit, desired gas barrier properties tend to be easily exhibited.

[0096] The method for applying the coating layer onto the polypropylene film can be any known coating method without any particular limitation, and examples of such methods include immersion (dipping) methods, and methods using a spray, coater, printer, brush, etc. In addition, examples of the types of coaters and printers used in these methods and the coating methods thereof include gravure coaters such as direct gravure method, reverse gravure method, kiss reverse gravure method, and offset gravure method, reverse roll coaters, microgravure coaters, coaters combined with chamber doctor, air knife coaters, dip coaters, bar coaters, comma coaters, die coaters, etc.

[0097] The coating amount of the coating layer is 1 m after applying and drying the anchor coating agent. 2 Mass per unit is 0.01 to 5 g / m 2 is preferably 0.03 to 3 g / m 2 It is more preferable that the thickness of the anchor coating agent is 1m after it is applied and dried. 2 When the mass per unit area is equal to or greater than the lower limit, the film tends to be sufficiently formed, 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 is unlikely to remain.

[0098] The method for drying the coating layer 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, it is preferable to dry at a temperature of 60 to 100°C for about 1 second to 2 minutes.

[0099] As the coating layer, a polyvinyl alcohol resin can be used instead of the polyurethane resin. The polyvinyl alcohol resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit, such as polyvinyl alcohol (PVA) or ethylene-vinyl alcohol copolymer (EVOH). When a polyvinyl alcohol resin is used as the coating layer, the coating layer can be formed by coating a polyvinyl alcohol resin solution or by multilayer extrusion.

[0100] [Inorganic oxide layer] The inorganic oxide layer contributes to improving the gas barrier property. Examples of inorganic oxides contained in the inorganic oxide layer include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoint of transparency and barrier property, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. In addition, from the viewpoint of excellent tensile elongation during processing, it is preferable that the inorganic oxide layer is a layer using silicon oxide. By using the inorganic oxide layer, high barrier property can be obtained with a very thin layer within a range that does not affect the recyclability of the laminate.

[0101] The O / Si ratio of the inorganic oxide layer is preferably 1.7 or more. When the O / Si ratio is 1.7 or more, the content ratio of metal Si is suppressed, and good transparency is easily obtained. In addition, the O / Si ratio is preferably 2.0 or less. When the O / Si ratio is 2.0 or less, the crystallinity of SiO is high, and the inorganic oxide layer can be prevented from becoming too hard, and good tensile resistance can be obtained. This makes it possible to suppress the occurrence of cracks in the inorganic oxide layer when laminating a gas barrier coating layer. In addition, even after forming into a packaging bag, the base material layer or intermediate layer may shrink due to heat during boiling or retort treatment, but when the O / Si ratio is 2.0 or less, the inorganic oxide layer easily follows the above shrinkage, and the deterioration of the barrier property can be suppressed. From the viewpoint of obtaining these effects more fully, the O / Si ratio of the inorganic oxide layer is preferably 1.75 to 1.9, and more preferably 1.8 to 1.85.

[0102] The O / Si ratio of the inorganic oxide layer can be determined by X-ray photoelectron spectroscopy (XPS). For example, the measurement device is an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., product name: JPS-90MXV), the X-ray source is non-monochromated 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 determine the O / Si ratio, relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used.

[0103] The thickness of the inorganic oxide layer is preferably 10 nm or more and 50 nm or less. When the thickness is 10 nm or more, sufficient water vapor barrier properties can be obtained. Also, when the thickness is 50 nm or less, cracks caused by deformation due to internal stress of the thin film can be suppressed, and the deterioration of water vapor barrier properties can be suppressed. Note that, when the thickness exceeds 50 nm, the cost is likely to increase due to an increase in the amount of material used and a prolonged film formation time, and is therefore not preferable from an economical point of view. From the same viewpoint as above, the thickness of the inorganic oxide layer is more preferably 20 nm or more and 40 nm or less.

[0104] The inorganic oxide layer can be formed, for example, by vacuum film formation. In the 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.

[0105] 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), etc. are particularly preferably used. However, in terms of productivity, the vacuum deposition is currently the most superior. As a heating means for the vacuum deposition, it is preferable to use any of the electron beam heating method, resistance heating method, and induction heating method.

[0106] [Gas barrier coating layer] The gas barrier coating layer protects the inorganic oxide layer, contributes to improving the gas barrier property, and exerts high gas barrier property by a synergistic effect with the inorganic oxide layer. The gas barrier coating layer may be a layer formed using a composition for forming a gas barrier coating layer containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof.

[0107] The gas barrier coating layer can be formed using a composition for forming a gas barrier coating layer (hereinafter also referred to as a coating agent) containing as a main component an aqueous solution or a water / alcohol mixed solution containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof. From the viewpoint of more adequately maintaining the gas barrier property 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 a hydrolyzate thereof, and a silane coupling agent or a hydrolyzate thereof, and further 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 a treatment such as hydrolysis in advance with 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 mixed) solvent.

[0108] Examples of hydroxyl-containing polymer compounds used in the coating agent include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. Among these, polyvinyl alcohol (PVA) is preferably used in the coating agent for the gas barrier coating layer because it has particularly excellent gas barrier properties.

[0109] Examples of metal alkoxides include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], etc. Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

[0110] Examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, etc. The silane coupling agent may be a polymer thereof.

[0111] The coating agent may contain known additives such as an isocyanate compound, a dispersant, a stabilizer, a viscosity modifier, a colorant, etc., as necessary, within the range that does not impair the gas barrier property. The coating agent may contain an acid catalyst, an alkali catalyst, a photopolymerization initiator, etc., as necessary.

[0112] The thickness of the gas barrier coating layer is preferably 0.5 to 4 μm, more preferably 0.5 to 3 μm, and even more preferably 1 μm or more and 3 μm or less, from the viewpoint of obtaining excellent gas barrier properties while making the polypropylene content in the laminate 90% by mass or more. The thickness of the gas barrier coating layer may be 50 to 1000 nm or 100 to 500 nm. If the thickness of the gas barrier coating layer is 50 nm or more, more sufficient gas barrier properties tend to be obtained, and if the thickness of the gas barrier coating layer is 1000 nm or less, sufficient flexibility tends to be maintained.

[0113] The coating agent for forming the gas barrier coating layer 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 agent can be dried by, for example, hot air drying, hot roll drying, high frequency irradiation, infrared irradiation, UV irradiation, or a combination thereof.

[0114] The temperature at which the coating film is dried can be, for example, 50 to 150° C., and is preferably 70 to 100° C. By keeping the drying temperature within the above range, the occurrence of cracks in the inorganic oxide layer and the gas barrier coating layer can be further suppressed, and excellent barrier properties can be exhibited.

[0115] [Print layer] The printing layer may be provided at a position visible from the outside of the laminate 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 in consideration of printability on the film, design such as color tone, adhesion, safety as a food container, etc. Examples of printing methods that can be used include gravure printing, offset printing, gravure offset printing, flexographic printing, and inkjet printing. Among them, gravure printing can be preferably used from the viewpoints of productivity and high definition of the pattern.

[0116] In order to enhance the adhesion of the printed layer, the surface of the layer on which the printed layer is to be provided may be subjected to various pretreatments such as corona treatment, plasma treatment, and frame treatment, and a coating layer such as an easy-adhesion layer may be provided. The surface of the layer on which the printed layer is to be provided may be the surface of a polypropylene film (the first polypropylene film or the third polypropylene film) or the surface of a gas barrier coating layer. The thickness of the printed layer may be 0.1 to 5 μm.

[0117] The laminates (100A, 100B) according to preferred embodiments of the present disclosure have been described above, but the laminates of the present disclosure are not limited to the above embodiments. For example, in the laminates (100A, 100B) described above, each layer is bonded with an adhesive layer S, but the laminates may not have the adhesive layer S. For example, the base material layer 11 and the sealant layer 12 of the laminate 100A may be directly bonded to each other, and the base material layer 11 and the intermediate layer 13 of the laminate 100B, and / or the intermediate layer 13 and the sealant layer 12 may be directly bonded to each other. However, from the viewpoint of high adhesive strength, it is preferable that the base material layer and the intermediate layer are bonded to each other with an adhesive layer having a thickness of 0.5 to 4 μm. From the same viewpoint, it is preferable that the intermediate layer and the sealant layer are bonded to each other with an adhesive layer having a thickness of 0.5 to 4 μm.

[0118] <Package> The packaging bag is made by making the above-mentioned laminate. There is no particular restriction on the shape of the packaging body, but the packaging body may be, for example, a bag shape obtained by folding one laminate in half so that the sealant layers face each other, and then heat sealing three sides, or a bag shape obtained by stacking two laminates so that the sealant layers face each other, and then heat sealing four sides, or a self-supporting standing pouch obtained by stacking two laminates so that the sealant layers face each other and sealing the base material between them. The packaging bag can accommodate food, medicine, and other contents, and can be subjected to heat sterilization treatment such as retort treatment or boiling treatment.

[0119] Retort processing is a method of sterilizing microorganisms such as mold, yeast, and bacteria under pressure, generally for the preservation of food, medicine, etc. Usually, packaging bags containing food, etc. are pressure sterilized at 105-140°C, 0.15-0.30 MPa, and 10-120 minutes. There are two types of retort equipment: steam type, which uses heated steam, and hot water type, which uses pressurized heated water, and they are used appropriately depending on the sterilization conditions of the food, etc. to be contained.

[0120] Boiling is a method of moist heat sterilization for preserving food, medicine, etc. Boiling is usually performed at 100°C or less using a hot water bath. More specifically, depending on the contents, packaging bags containing food, etc. are subjected to moist heat sterilization at 60-100°C, atmospheric pressure, and for 10-120 minutes. Methods include a batch method in which the product is immersed in a hot water bath at a constant temperature and treated for a certain period of time before being removed, and a continuous method in which the product is passed through a tunnel in the hot water bath for treatment.

[0121] The packaging bag is particularly suitable for use in applications involving high retort treatment, since it is unlikely to curl during retort treatment at high temperatures of 125° C. or higher (high retort treatment). In addition, the packaging bag has a good appearance and is excellent in transportability and workability when filling the bag with contents, since it is less susceptible to deformation (distortion) and wrinkles due to heat during bag production. EXAMPLES

[0122] The present disclosure will be described in more detail with reference to the following examples, but the present disclosure is not limited to these examples.

[0123] <Preparation of base layer, intermediate layer and sealant layer> As materials for the base layer and intermediate layer, biaxially oriented polypropylene films (OPP-1 to OPP-8) having a thickness of 20 μm and a heat shrinkage rate shown in Table 1 below were prepared. As the sealant layer, non-oriented polypropylene films (CPP-1 to CPP-3) having a heat shrinkage rate and thickness shown in Table 2 below were prepared. MD indicates the thermal shrinkage rate in the MD direction of the film, and R TD R indicates the thermal shrinkage rate in the TD direction of the film. MD and R TD was measured according to the procedures (a) to (g) described in the above embodiment.

[0124] [Table 1]

[0125] [Table 2]

[0126] <Example 1> OPP-2 was laminated on OPP-1 by a dry lamination method using a two-liquid adhesive (manufactured by Mitsui Chemicals, Inc., product name: base agent A525 / hardener A52), and then CPP-1 was laminated on OPP-2 in the same manner. At this time, the MD direction of OPP-1, the MD direction of OPP-2, and the MD direction of CPP-1 were made to coincide with each other. This produced a laminate having a laminated structure of OPP-1 (base layer) / S (adhesive layer) / OPP-2 (intermediate layer) / S (adhesive layer) / CPP-1 (sealant layer). The polypropylene content in the obtained laminate was 90% by mass or more, and the thickness of each adhesive layer (S) was 3.1 μm.

[0127] <Example 2> (Preparation of Coating Layer-Forming Composition) Acrylic polyol and tolylene diisocyanate were mixed so that the number of NCO groups of tolylene diisocyanate was equal to the number of OH groups of the acrylic polyol, and diluted with ethyl acetate so that the total solid content (total amount of acrylic polyol and tolylene diisocyanate) was 5 mass%. β-(3,4 epoxycyclohexyl)trimethoxysilane was further added to the diluted mixed solution so that it was 5 mass parts per 100 mass parts of the total amount of acrylic polyol and tolylene diisocyanate, and these were mixed to prepare a composition for forming a coating layer (anchor coating agent).

[0128] (Preparation of composition for forming gas barrier coating layer) A composition for forming a gas barrier coating layer was prepared by mixing the following liquids A, B and C in a mass ratio of 65 / 25 / 10, respectively. Liquid A: A hydrolysis solution with a solid content of 5 mass% (SiO2 equivalent) obtained by adding 72.1 g of 0.1N hydrochloric acid to 17.9 g of tetraethoxysilane (Si(OC2H5)4) and 10 g of methanol and stirring for 30 minutes. Liquid B: 5% by mass solution of polyvinyl alcohol in water / methanol (mass ratio of water:methanol is 95:5). Liquid C: A hydrolysis solution in which 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate was diluted with a mixture of water and isopropyl alcohol (water:isopropyl alcohol mass ratio 1:1) to a solid content of 5 mass%.

[0129] (Preparation of gas barrier film) The above-mentioned composition for forming a coating layer was applied to the corona-treated surface of OPP-2, one side of which had been subjected to corona treatment, by gravure roll coating, and then dried and cured at 60°C to obtain a coating amount of 0.1 g / m 2 A coating layer (C1) made of an acrylic polyurethane resin was formed. Next, a transparent inorganic oxide layer (G1) made of silicon oxide with a thickness of 30 nm was formed by a vacuum deposition apparatus using an electron beam heating method. As the inorganic oxide layer (G1), a silica deposition layer with an O / Si ratio of 1.8 was formed by adjusting the deposition material type. The O / Si ratio was measured with an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., product name: JPS-90MXV) using a non-monochromated MgKα (1253.6 eV) X-ray source at an X-ray output of 100 W (10 kV-10 mA). Quantitative analysis to determine the O / Si ratio was performed using relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p, respectively.

[0130] Next, the composition for forming a gas barrier coating layer was applied onto the inorganic oxide layer (G1) by gravure roll coating, and then heated and dried in an oven under conditions of a tension of 20 N / m and a drying temperature of 120° C. to form a gas barrier coating layer (G2) having a thickness of 0.5 μm. This resulted in the production of a gas barrier film that would become an intermediate layer.

[0131] (Preparation of Laminate) On the gas barrier coating layer (G2) of the gas barrier film, OPP-1, which will be the base layer, was laminated by a dry lamination method via a two-liquid adhesive (manufactured by Mitsui Chemicals, Inc., product name: base agent A525 / curing agent A52), and then CPP-1, which will be the sealant layer, was laminated on the OPP-2 of the gas barrier film in the same manner. At this time, the MD direction of OPP-1, the MD direction of OPP-2, and the MD direction of CPP-1 were made to coincide with each other. As a result, a laminate having a laminated structure of OPP-1 (base layer) / S (adhesive layer) / G2 (gas barrier coating layer) / G1 (inorganic oxide layer) / C1 (coat layer) / OPP-2 / S (adhesive layer) / CPP-1 (sealant layer) was produced. The polypropylene content in the obtained laminate was 90% by mass or more, and the thickness of each adhesive layer (S) was 3.1 μm.

[0132] <Example 3> CPP-1 was laminated on OPP-1 by dry lamination using a two-liquid adhesive (manufactured by Mitsui Chemicals, Inc., product name: base agent A525 / curing agent A52). At this time, the MD direction of OPP-1 was aligned with the MD direction of CPP-1. This produced the laminate of Example 3 (a laminate having a laminate structure shown in Table 3). The polypropylene content in the obtained laminate was 90% by mass or more, and the thickness of the adhesive layer (S) was 3.1 μm.

[0133] <Example 4> A laminate of Example 4 (a laminate having a laminate structure shown in Table 3) was produced in the same manner as in Example 3, except that CPP-3 was used instead of CPP-1.

[0134] <Example 5> (Preparation of Coating Layer-Forming Composition) Takelac WPB-341 (manufactured by Mitsui Chemicals, Inc.) and isocyanate silane KBE-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed at a solid content ratio of 9:1 to prepare a composition for forming a coat layer.

[0135] (Preparation of gas barrier film) The above-mentioned composition for forming a coating layer was applied to the surface of OPP-2 by gravure roll coating, and then dried and cured at 60°C to obtain a coating amount of 1.0 g / m 2 A coating layer (C2) was formed from a polyurethane resin formed from an acid group-containing polyurethane and a polyamine. Next, a transparent inorganic oxide layer (G1) made of silicon oxide and having a thickness of 30 nm was formed on the coating layer (C2) in the same manner as in Example 2. This resulted in a gas barrier film that would become an intermediate layer.

[0136] (Preparation of Laminate) The laminate of Example 5 (a laminate having the laminate structure shown in Table 3) was produced in the same manner as in "Preparation of Laminate" of Example 2, except that the gas barrier film prepared above was used and CPP-3 was used instead of CPP-1.

[0137] <Example 6> A laminate of Example 6 (a laminate having a laminate structure shown in Table 3) was produced in the same manner as in Example 1, except that OPP-1 was used instead of OPP-2.

[0138] <Comparative Example 1> A laminate of Comparative Example 1 (a laminate having a laminate structure shown in Table 3) was produced in the same manner as in Example 1, except that OPP-3 was used instead of OPP-1.

[0139] <Comparative Example 2> A laminate of Comparative Example 2 (a laminate having a laminate structure shown in Table 3) was produced in the same manner as in Example 1, except that CPP-2 was used instead of CPP-1.

[0140] <Examples 7 to 10 and Comparative Examples 3 to 4> The laminates of Examples 7 to 10 and Comparative Examples 3 and 4 (laminates having the laminate structure shown in Table 3) were produced in the same manner as in Example 1, except that the biaxially oriented polypropylene films (OPP-3 to OPP-8) shown in Table 3 were used instead of OPP-1, and the amount of gas barrier coating layer-forming composition applied was changed to form a gas barrier coating layer (G3) having a thickness of 0.3 μm instead of the gas barrier coating layer (G2) having a thickness of 0.5 μm.

[0141] <Analysis 1: Measurement of crystallinity> The laminates obtained in the examples and comparative examples were used as measurement samples, and the crystallinity in the MD and TD directions of the biaxially oriented polypropylene films (OPP1, OPP-3 to OPP-7) constituting the base layer was measured under the following conditions by oblique incidence X-ray diffraction. When measuring the crystallinity in the MD direction, the X-ray irradiation device and detector were arranged so as to be aligned in a direction perpendicular to the MD direction, and when measuring the crystallinity in the TD direction, the X-ray irradiation device and detector were arranged so as to be aligned in a direction perpendicular to the TD direction. The results are shown in Table 3. (Measurement conditions) Measurement equipment: X-ray diffraction equipment (Rigaku Corporation, product name: RINT TTR III) Optical system: Parallel method (detector: scintillation counter, purpose: small angle, target: sample surface) Scan axis: 2θ / θ Measurement method: Continuous Counting unit: cps Starting angle: 3° (approximate) End angle: 35° Sampling width: 0.02° Scan speed: 4° / min Voltage: 50kV Current: 300mA Divergence vertical slit: 10mm Scattering slit: open Receiving slit: open

[0142] <Analysis 2: Melting point measurement> The melting point (melting peak temperature) of the biaxially oriented polypropylene film constituting the base layer was measured by differential scanning calorimetry (DSC) according to the method shown below. First, the biaxially oriented polypropylene film (OPP-1, OPP-3 to OPP-7) which is the base layer was peeled off from the laminate produced in the examples and comparative examples to prepare a measurement sample. Using this measurement sample, heat treatment was performed under the following condition (i), and then differential scanning calorimetry was performed under the following condition (ii) to measure the melting point (melting peak temperature) after heat treatment. In addition, using the above measurement sample, differential scanning calorimetry was performed under the following condition (iii) to measure the melting point (melting peak temperature) before heat treatment. When multiple melting peaks were observed in each measurement, all of the temperatures are shown in Table 3. As the differential scanning calorimeter, DSC7000X (product name) manufactured by Hitachi High-Tech Science Corporation was used. (i) The temperature was increased from 25°C to 230°C at a rate of 10°C / min, held at 230°C for 2 minutes, then decreased from 230°C to 25°C at a rate of 10°C / min, and held at 25°C for 5 minutes. (ii) The temperature was increased from 25°C to 230°C at a rate of 10°C / min and held at 230°C for 5 minutes. (iii) The temperature was increased from 25°C to 230°C at a rate of 10°C / min and held at 230°C for 2 minutes.

[0143] [Table 3]

[0144] <Evaluation 1: Amount of deformation during bag making (quantitative evaluation)> The amount of deformation of the laminates obtained in the Examples and Comparative Examples during bag making (heat sealing) was evaluated according to the following procedure. (a1) The laminate was cut into a square shape of 150 mm × 150 mm to prepare a sample for evaluation testing. Two such samples were prepared. (b1) After two samples were stacked with the sealant layers facing each other, the four sides were heat-sealed by heating them for 0.3 seconds at a surface pressure of 1.0 MPa using a heat seal bar set at a temperature of 160°C. At this time, the seal width (the width perpendicular to one side of the square) was 10 mm. The heat seal bar used had a metal upper side and a silicone lower side. (c1) After heat sealing, the obtained laminated sample (evaluation pouch) was left at room temperature (25°C) for 30 minutes, then placed on a platen, and the height of the four sides of the evaluation pouch rising from the platen was measured using a metal ruler. The maximum value of the four sides' rising height was recorded as the rising height (X) of the evaluation pouch, and the amount of deformation was evaluated according to the following criteria. The results are shown in Table 4. [standard] A: Height (X) is 10mm or less B: Height (X) is greater than 10 mm

[0145] <Evaluation 2: Degree of deformation during bag making (qualitative evaluation)> The degree of deformation during bag making (heat sealing) of the laminates obtained in the Examples and Comparative Examples was evaluated according to the following procedure. (a2) The laminate was cut into a square shape of 60 mm x 60 mm to prepare a sample for evaluation testing. Two such samples were prepared. (b2) After stacking two samples with the sealant layers facing each other, the three sides were heat-sealed using a three-sided pouch making machine at a surface pressure of 1.0 MPa, a temperature of 190°C, and a time of 0.3 seconds, with a seal width (the width perpendicular to one side of the square) of 10 mm. (c2) After heat sealing, the resulting laminated sample (pouch for evaluation) was visually observed for distortion in the sealed area, and the degree of deformation during bag making was evaluated based on the following criteria, using (a) to (c) in Figure 5 as indicators. The results are shown in Table 4. A: No distortion was observed. B: Small distortion is observed. C: Large distortion is observed. In addition, (a) to (c) of Fig. 5 are cross-sectional views of the sealed portion of the pouch, and are schematic diagrams showing the state of distortion of the pouch after heat sealing. The pouch shown in (a) of Fig. 5 is evaluated as having almost no distortion and is evaluated as "A" above. The pouch shown in (b) of Fig. 5 is evaluated as having a small distortion and is evaluated as "B" above. The pouch shown in (c) of Fig. 5 is evaluated as having a large distortion and is evaluated as "C" above. During the evaluation, the pouch 700 is placed on a desk 800.

[0146] <Evaluation 3: Whitening during bag making> The sealed portion of the pouch produced in the above evaluation 2 was visually observed to see whether it had whitened, and was evaluated according to the following criteria. The results are shown in Table 4. A: No bleaching was observed. B: A slight whitening is visible when viewed through a light source. C: Obvious bleaching is observed.

[0147] <Evaluation 4: Wrinkles during bag making> The pouches produced in the above evaluation 2 were visually inspected for the presence or absence of wrinkles in the sealed portions and evaluated according to the following criteria. The results are shown in Table 4. A: No wrinkles were found. B: Shallow wrinkles are observed. C: Deep wrinkles are observed.

[0148] <Evaluation 5: Amount of curl during high retort processing> The curl amount during high-temperature retort treatment of the laminates obtained in the examples and comparative examples was evaluated according to the following procedure. (a) The laminate was cut into a square shape of 250 mm x 250 mm to prepare a sample for evaluation testing. (b) The sample was placed in a retort oven with the substrate layer facing up, and shower retort treatment was performed at 128°C for 16 minutes under a pressure of 0.3 bars. (c) After the shower retort treatment, the sample was allowed to stand at room temperature for 30 minutes, and then a square of 200 mm x 200 mm was cut out from the center of the sample to prepare an evaluation sample. (d) The sample obtained in (c) above was placed on a surface plate, and as shown in FIG. 6(a), if the sample (300 in FIG. 6) was arc-shaped, the height (H) of the sample floating above the surface plate and the width (W') of the arc were measured. As shown in FIG. 6(b), if the sample (300 in FIG. 6) was cylindrical, the inner diameter (W") of the cylinder was measured. A metal ruler was used for the measurements. (e) When the sample was arc-shaped, the radius of curvature (R) was calculated based on the following formula (a), and the amount of curl was evaluated based on the following criteria. When the sample was cylindrical, the inner radius of the cylinder (W" / 2) was taken as the radius of curvature R, and the amount of curl was evaluated based on the following criteria. The results are shown in Table 4. R = ([W' / 2] 2 +[H] 2 ) / (2×[H]) …(a) [standard] A: Radius of curvature R is 50 or more B: Radius of curvature R is less than 50

[0149] [Table 4] [Explanation of symbols]

[0150] Reference Signs List: 11...base material layer, 12...sealant layer, 13...intermediate layer, 14...first polypropylene film, 15...third polypropylene film, 16...coating layer, 17...inorganic oxide layer, 18...gas barrier coating layer, 100A, 100B...laminate, S...adhesive layer.

Claims

1. A laminate for packaging in which 90% or more of the total volume is polypropylene, A substrate layer containing a first polypropylene film, A sealant layer comprising a second polypropylene film, The laminate contains only two films: the first polypropylene film and the second polypropylene film. The first polypropylene film is a stretched polypropylene film. The first polypropylene film and the second polypropylene film are arranged such that their MD directions are substantially the same. When the thermal shrinkage rate of the film in a predetermined direction is defined by the following formula (1), The thermal shrinkage ratio R in the MD direction of the first polypropylene film ＭＤ１ The percentage is 10.0% or less. The thermal shrinkage ratio R in the TD direction of the first polypropylene film ＴＤ１ The percentage is 12.0% or less. The thermal shrinkage ratio R in the TD direction of the second polypropylene film ＴＤ２ However, the thermal shrinkage rate R ＴＤ１ A laminate that is smaller and makes up 0.5% or more of the material. Thermal shrinkage rate in a given direction (%) = ([Length in the given direction before heating] - [Length in the given direction after heating at 150°C for 15 minutes]) / [Length in the given direction before heating] × 100 ... (1)

2. The laminate according to claim 1, wherein the degree of crystallinity of the first polypropylene film, as measured by oblique incidence X-ray diffraction, is 80% or more in both the MD direction and the TD direction.

3. The laminate according to claim 2, wherein the crystallinity of the first polypropylene film, as measured by oblique incidence X-ray diffraction, is 86% or more in one of the MD direction and 80% or more in the other direction.

4. The laminate according to claim 1, wherein, when the first polypropylene film is heat-treated under the conditions (i) below and then differential scanning calorimetry is performed under the conditions (ii) below, at least one melting peak is observed below 163°C. (i) Heat from 25°C to 230°C at a rate of 10°C / min, hold at 230°C for 2 minutes, then cool from 230°C to 25°C at a rate of 10°C / min, hold at 25°C for 5 minutes. (ii) Heat from 25°C to 230°C at a rate of 10°C / min, and hold at 230°C for 5 minutes.

5. The laminate according to claim 1, wherein, when differential scanning calorimetry is performed on the first polypropylene film under the conditions (iii) below, at least one melting peak is observed at 167°C or higher. (iii) Heat from 25°C to 230°C at a rate of 10°C / min, and hold at 230°C for 2 minutes.

6. The heat shrinkage ratio R of the first polypropylene film ＭＤ１ and the thermal shrinkage coefficient R ＴＤ１ The laminate according to claim 1, wherein each of these is 7.0% or less.

7. The laminate according to claim 1, wherein the substrate layer includes an inorganic oxide layer and a gas barrier coating layer covering the inorganic oxide layer.

8. The laminate according to claim 1, wherein the first polypropylene film is a biaxially oriented polypropylene film.

9. The laminate according to claim 1, wherein the second polypropylene film is an unstretched polypropylene film.

10. A laminate according to any one of claims 1 to 9, for use in retort pouches.

11. A packaging bag made by forming a bag from the laminate described in any one of claims 1 to 9.

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