Barrier film, laminate, packaging bag, and method for manufacturing barrier film

Abstract

Provided is a barrier film comprising a vapor deposition film formed on an OPP film substrate, the barrier film being capable of lowering barrier properties after heat sterilization treatment and achieving both Gelbo flex resistance and adhesion.　There is provided a barrier film in which a polypropylene substrate comprising a base layer as an outermost surface layer, and a silicon oxide vapor deposition film formed on the base layer, are laminated in the stated order, wherein the base layer preferably contains a polyamide resin, and the silicon oxide vapor deposition film has an intensity ratio P1 (defined below) of 0.37-0.78 when X-ray absorption fine structure analysis is performed from a surface side opposite from the polypropylene-substrate side of the barrier film.　P1 = (maximum value of intensity of 1843.8-1845.2 eV) / (maximum value of intensity of 1847.0-1849.4 eV)

Description

Barrier film, laminate and packaging bag, and method for manufacturing barrier film

[0001] The present invention relates to a barrier film, a laminate and a packaging bag, and a method for producing a barrier film.

[0002] Conventionally, laminated films having a film formed on a substrate such as a long film or sheet of plastic have been used for various applications. For example, a barrier film has been developed that has a barrier layer made of a thin film of aluminum oxide or the like on a plastic film, thereby providing a barrier function against oxygen and water vapor.

[0003] As a method for producing a barrier film having an aluminum oxide thin film, for example, Patent Document 1 discloses a method for producing a barrier film in which a PET film surface is subjected to a plasma treatment and then aluminum oxide is vapor-deposited.

[0004] On the other hand, in recent years, from the viewpoint of environmental consideration, mono-material packaging materials have been studied for the purpose of improving the recyclability of packaging materials. For example, laminates have been studied as mono-material packaging materials in which a polyolefin film such as a biaxially oriented polypropylene film (OPP film) is used as a substrate instead of the conventionally widely used polyester film (PET film), and a polyolefin film such as a non-oriented polypropylene film (CPP film) is used as a sealant layer to be laminated thereto (see Patent Document 2).

[0005] Patent No. 7355957 Patent No. 6902231

[0006] Patent Document 2 discloses a barrier laminate comprising an OPP film substrate, a vapor-deposited film, and a barrier coating layer provided on the vapor-deposited film, and by controlling the barrier coating layer, it is possible to produce a barrier film that has excellent transparency and barrier properties after boiling treatment or retort treatment, even when an OPP film substrate is used.

[0007] However, in addition to this, resistance to bending tests (Gelbo flex tests) and adhesion are also required, and further improvements were needed so that the above physical properties could be obtained without providing a barrier coating layer, which requires high equipment costs.

[0008] As a result of intensive research to solve the above problems, the present inventors have discovered a barrier film that uses an OPP film substrate and that has excellent barrier properties after boiling treatment and retort treatment, as well as excellent resistance and adhesion in the Gelbo flex test, even without providing a barrier coating layer, and have thereby completed the present invention. Specifically, the present invention provides the following.

[0009] (1) A barrier film comprising a polypropylene substrate having an underlayer as the outermost layer, and a silicon oxide vapor-deposited film formed on the underlayer, laminated in this order, wherein the silicon oxide vapor-deposited film has an intensity ratio P1 of 0.37 or more and 0.78 or less when X-ray absorption fine structure analysis is performed on the surface of the barrier film opposite the polypropylene substrate side, as defined below: P1 = (maximum intensity between 1843.8 and 1845.2 eV) / (maximum intensity between 1847.0 and 1849.4 eV).

[0010] (2) A barrier film comprising a polypropylene substrate having an underlayer as the outermost layer, and a silicon oxide vapor-deposited film formed on the underlayer, laminated in this order, wherein the silicon oxide vapor-deposited film has an intensity ratio P2 of 0.45 or more and 0.88 or less when X-ray absorption fine structure analysis is performed on the surface of the barrier film opposite the polypropylene substrate side, as defined below: P2 = (maximum intensity between 1845.4 and 1846.4 eV) / (maximum intensity between 1847.0 and 1849.4 eV).

[0011] (3) The barrier film according to claim 1 or 2, wherein the underlayer contains a polyamide resin.

[0012] (4) The barrier film according to (1) or (2), wherein the polypropylene substrate comprises at least the underlayer and a first layer in this order, and the first layer contains homopolypropylene.

[0013] (5) The barrier film according to (1) or (2), wherein the polypropylene substrate comprises at least the underlayer, a first layer, and a second layer in this order, the first layer containing modified polypropylene, and the second layer containing homopolypropylene.

[0014] (6) The barrier film according to (5), wherein the polypropylene substrate comprises at least the underlayer, a first layer, a second layer, and a third layer in this order, the first layer containing modified polypropylene, the second layer containing homopolypropylene, and the third layer containing a copolymer of propylene and an olefin other than propylene.

[0015] (7) The barrier film according to (3), wherein the polyamide resin comprises an amorphous aromatic polyamide alone, or a mixture of 50% by mass or more and less than 100% by mass of an amorphous aromatic polyamide and more than 0% by mass and less than 50% by mass of a crystalline aromatic polyamide.

[0016] (8) The barrier film according to (1) or (2), wherein a coating layer is laminated on the silicon oxide vapor-deposited film.

[0017] (9) A laminate comprising the barrier film according to any one of (1) or (2) and a sealant layer.

[0018] (10) A packaging bag comprising the laminate according to (9).

[0019] (11) A method for producing a barrier film, comprising: a polypropylene substrate having an underlayer as an outermost layer; and a silicon oxide vapor-deposited film formed on the underlayer, laminated in this order; wherein the silicon oxide vapor-deposited film has an intensity ratio P1 of 0.37 to 0.78 or an intensity ratio P2 of 0.45 to 0.88, as defined below, when X-ray absorption fine structure analysis is performed on the surface of the barrier film opposite the polypropylene substrate, wherein the silicon oxide vapor-deposited film is a vapor-deposited film formed by physical vapor deposition (PVD), where P1 = (maximum intensity between 1843.8 and 1845.2 eV) / (maximum intensity between 1847.0 and 1849.4 eV) P2 = (maximum intensity between 1845.4 and 1846.4 eV) / (maximum intensity between 1847.0 and 1849.4 eV).

[0020] The barrier film of the present invention uses an OPP film substrate and, even without a barrier coating layer, has excellent barrier properties after heat sterilization treatments such as boiling treatment and retort treatment, as well as excellent resistance and adhesion in the Gelbo flex test.

[0021] FIG. 1 is a cross-sectional view showing an example of a barrier film according to the present embodiment; FIG. 2 is a cross-sectional view showing an example of a laminate using the barrier film of the present invention; FIG. 3 is a cross-sectional view showing another example of a laminate using the barrier film of the present invention; FIG. 4 is a diagram showing superimposed normalized XAFS spectra of Examples and Comparative Examples; FIG. 5 is a diagram showing a normalized XAFS spectrum of the barrier film of Example 1; FIG. 6 is a diagram showing a normalized XAFS spectrum of the barrier film of Example 3; FIG. 7 is a diagram showing a normalized XAFS spectrum of the barrier film of Example 7; FIG. 8 is a diagram showing a normalized XAFS spectrum of the barrier film of Example 8; FIG. 9 is a diagram showing a normalized XAFS spectrum of the barrier film of Example 10; FIG. 10 is a diagram showing a normalized XAFS spectrum of the barrier film of Comparative Example 1;

[0022] Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be practiced with appropriate modifications within the scope of the object of the present invention. Furthermore, in this specification, the expression "X to Y" (X and Y are arbitrary numerical values) means "at least X and at most Y."

[0023] FIG. 1 is a cross-sectional view showing an example of a barrier film according to the present embodiment. The barrier film 100A of this embodiment includes a substrate 100, which corresponds to the polypropylene substrate of the present invention, and a vapor-deposited film 120. The substrate 100 is composed of two or more layers, including at least a polypropylene layer 110 and an underlayer 115. If necessary, a coating layer 130 (not shown) may be provided on the vapor-deposited film 120. In the example shown in FIG. 1, the underlayer 115 is located on one side of the polypropylene layer 110. In the example shown in FIG. 1, the barrier film 100A is formed by laminating the polypropylene layer 110, the underlayer 115, and the vapor-deposited film 120 in this order, with the vapor-deposited film 120 located on the surface of the barrier film. The vapor-deposited film 120 constitutes a barrier layer. When the coating layer 130 is provided, the vapor-deposited film 120 and the coating layer 130 together constitute the barrier layer.

[0024] In this specification, "laminated in this order" means that the polypropylene base material, the underlayer, and the silicon oxide vapor deposition film are laminated in this order, and further layers such as the anchor coat layer described below may be laminated between these layers.

[0025] Each layer constituting the barrier film 100A will be described below.

[0026] [Polypropylene Layer] The polypropylene layer 110 is made of at least polypropylene. The polypropylene may be any of a propylene homopolymer, a propylene random copolymer, and a propylene block copolymer, or may be a mixture of two or more selected from these.

[0027] A propylene homopolymer is a polymer of propylene only. A propylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene. A propylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of at least an α-olefin other than propylene. The latter polymer block may be a polymer block of propylene and an α-olefin other than propylene.

[0028] Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms, and specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.

[0029] Among polypropylenes, it is preferable to use a random copolymer from the viewpoint of transparency. When the rigidity and heat resistance of the laminate are important, it is preferable to use a homopolymer. When the impact resistance of the laminate is important, it is preferable to use a block copolymer.

[0030] In one embodiment, from the viewpoint of film-forming properties and processability, the melt flow rate (MFR) of the polypropylene may be 0.1 g / 10 min or more and 50 g / 10 min or less, or 0.3 g / 10 min or more and 30 g / 10 min or less. The lower limit of the melt flow rate (MFR) of the polypropylene may be 0.1 g / 10 min or more and 0.3 g / 10 min or more. The upper limit of the melt flow rate (MFR) of the polypropylene may be 50 g / 10 min or less and 30 g / 10 min or less. The MFR of the polypropylene is measured in accordance with ASTM D1238 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0031] As the polypropylene, biomass-derived polypropylene or mechanically recycled or chemically recycled polypropylene may be used.

[0032] The polypropylene content in the polypropylene layer 110 is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0033] The polypropylene layer 110 may contain a resin material other than polypropylene, such as polyolefins such as polyethylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins.

[0034] The polypropylene layer 110 may contain additives such as crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, lubricants, antistatic agents, pigments, and modifying resins.

[0035] The polypropylene layer 110 may be a multilayer film including at least a first layer and a second layer. The first layer is a layer on one side of the polypropylene substrate (the side on which a barrier layer such as a vapor-deposited film is formed), and the second layer is a layer on the other side of the polypropylene substrate.

[0036] The first layer and the second layer may each be a propylene random copolymer, which is a random copolymer of propylene and an α-olefin other than propylene. When the first layer and the second layer are made of a random copolymer, the adhesion between the layer and other layers in contact with the layer can be improved. Examples of α-olefins include ethylene, 1-butene, and 1-hexene.

[0037] The first layer may be a modified polypropylene, such as an acid-modified polypropylene having a polar group such as maleic acid, as exemplified by Admer (registered trademark). When the underlayer described below is made of a polyamide resin, the adhesion to the polyamide resin is improved.

[0038] The polypropylene layer 110 may include a third intermediate layer between the first and second layers. The intermediate layer preferably contains a polypropylene homopolymer. The intermediate layer may have a single-layer structure or a multi-layer structure.

[0039] (Example of Layer Structure of Barrier Film) An example of a specific layer structure of the barrier film 100A using a single polypropylene layer 110 is, from the side on which the vapor-deposited film is formed, vapor-deposited film / underlayer / propylene homopolymer (first layer).

[0040] Another example of a specific layer configuration of the barrier film 100A using two polypropylene layers 110 is, from the side on which the vapor-deposited film is formed, vapor-deposited film / underlayer / modified polypropylene (first layer) / propylene homopolymer (second layer).

[0041] Another example of a specific layer configuration of the barrier film 100A using three polypropylene layers 110 is, from the side on which the vapor-deposited film is formed, vapor-deposited film / underlayer / propylene random copolymer (first layer) / propylene homopolymer (third layer) / propylene random copolymer (second layer). In this case, when the underlayer described below is an anchor coat layer, the first layer being a propylene random copolymer improves adhesion to the anchor coat layer. Furthermore, the second layer being a propylene random copolymer improves adhesion to the first adhesive layer 161 for laminating the sealant layer 150, for example, when forming the laminate shown in FIG. 7 described below.

[0042] Another example of a specific layer configuration of the barrier film 100A using three polypropylene layers 110 includes, from the side on which the vapor-deposited film is formed, a vapor-deposited film / underlayer / modified polypropylene (first layer) / propylene homopolymer (third layer) / propylene random copolymer (second layer). In this case, when the first layer is modified polypropylene, adhesion to the polyamide resin of the underlayer, which will be described later, is improved. Furthermore, when the third layer is propylene random copolymer, adhesion to the first adhesive layer 161 for laminating the sealant layer 150 is improved, for example, when forming the laminate shown in FIG. 2, which will be described later.

[0043] [Underlayer] An underlayer 150 is formed on the surface of the substrate 100 on which the vapor-deposited film 120 is formed. When the underlayer is a highly heat-resistant surface resin layer made of a high-melting point resin material or a material with a high glass transition point (described below), the improved vapor deposition resistance promotes migration of the vapor-deposited material, resulting in a vapor-deposited film consisting of a dense, narrow, and highly flexible continuous layer. Furthermore, the high heat-resistant material of the underlayer also improves resistance to heat sterilization treatment. When the underlayer is an anchor coat layer formed by coating (described below), the substrate surface is made smoother, promoting migration of the vapor-deposited material and increasing the adhesion strength between the polypropylene substrate and the vapor-deposited film, resulting in a vapor-deposited film consisting of a dense, narrow, and highly flexible continuous layer. These features result in high gas barrier properties and can suppress breakage of the vapor-deposited film and coating layer due to deformation or bending of the film, as well as the resulting deterioration of gas barrier properties. This also results in a barrier film with excellent heat resistance that can withstand heat sterilization treatment.

[0044] When the underlayer is a surface resin layer, the surface resin layer contains a polyamide resin. Polyamide resins are resin materials with a melting point of 180°C or higher or a glass transition point of 90°C or higher and containing polar groups. Specifically, polyamides such as nylon 6 (hereinafter referred to as "nylon" as a registered trademark), nylon 6,6, aromatic-containing nylon, and amorphous nylon (amorphous polyamide) are more preferred. The use of such resin materials can effectively improve the gas barrier properties of the vapor-deposited film formed on the surface resin layer.

[0045] Furthermore, by using polyamide as a highly heat-resistant material, deterioration of gas barrier properties can be suppressed even when the barrier laminate is heated. As the highly heat-resistant material, polyamide containing a benzene ring (aromatic) is preferred from the viewpoint of mechanical strength and gas barrier properties. Polyamide containing a benzene ring can be combined with other materials and co-extrusion molded. Examples of polyamide containing a benzene ring include nylon MXD6 manufactured by Mitsubishi Gas Chemical Company.

[0046] The benzene ring-containing polyamide is a polyamide containing a benzene ring in either or both of the diamine-derived structural units and the dicarboxylic acid-derived structural units. It may be a copolymer of one or more diamines and one or more dicarboxylic acids. It may also be a mixture of two or more copolymers. Examples of the copolymer include a copolymer of a benzene ring-containing diamine and an aliphatic dicarboxylic acid, a copolymer of an aliphatic diamine and a benzene ring-containing dicarboxylic acid, a copolymer of a benzene ring-containing diamine, a benzene ring-containing dicarboxylic acid, and an aliphatic dicarboxylic acid, and a copolymer of an aliphatic diamine, a benzene ring-containing diamine, and a benzene ring-containing dicarboxylic acid.

[0047] The surface resin layer may contain a polyamide that does not contain a benzene ring, or may contain polyester, acrylic resin, ionomer resin, or the like, as long as it does not affect processability and physical properties.

[0048] The diamine containing a benzene ring is metaxylenediamine, paraxylenediamine, metaphenylenediamine, paraphenylenediamine, etc. One or more of these may be used.

[0049] The dicarboxylic acid containing a benzene ring is an aromatic dicarboxylic acid such as terephthalic acid (TPA) or isophthalic acid (IPA), or a naphthalenedicarboxylic acid such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, or 2,7-naphthalenedicarboxylic acid. At least one of these is used.

[0050] Aliphatic diamines include linear aliphatic diamines such as 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine (hexamethylenediamine), 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine (NDA), 1,10-decanediamine (DDA), 1,11-undecanediamine, and 1,12-dodecanediamine; 2-methyl-1,8-octanediamine (MODA); 4- Branched-chain aliphatic diamines such as methyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, 2,2,4- / 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 2-methyl-1,6-hexanediamine, and 2-methyl-1,7-heptanediamine; alicyclic diamines such as isophoronediamine, norbornanedimethylamine, and tricyclodecanedimethylamine; and the like. At least one of these can be used.

[0051] The aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid having 2 to 20 carbon atoms. In consideration of polymerization suitability and processability, adipic acid is most preferable, but other dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, eicosanedioic acid, eicosadienedioic acid, and 2,2,4-trimethyladipic acid. One or more of these are used.

[0052] Polyamides that do not contain a benzene ring include polyamides 6, 7, 10, 11, 12, 410, 56, 66, 69, 610, 611, 612, and 1010. The surface resin layer may contain one or more of these.

[0053] The surface resin layer preferably contains 20% by mass or more of a benzene ring-containing polyamide relative to the entire surface resin layer, more preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more. By containing 20% ​​by mass or more of a benzene ring-containing polyamide, moist heat swelling can be suppressed, thereby improving adhesion to the vapor-deposited film and reducing the deterioration of the barrier performance of the vapor-deposited film during heat sterilization by boiling or retort. If the content is less than 20% by mass, poor adhesion to the vapor-deposited film and a deterioration of the barrier performance during heat sterilization may occur.

[0054] The surface resin layer preferably contains 20% by mass or more of crystalline polyamide, more preferably 30% by mass or more, and even more preferably 40% by mass or more. By containing 20% ​​by mass or more of crystalline polyamide, gas barrier properties can be improved and moist heat swelling can be suppressed. Examples of crystalline polyamide include a copolymer of metaxylenediamine and adipic acid, a copolymer of hexamethylenediamine and terephthalic acid, and polyamide 6.

[0055] The surface resin layer preferably contains 90% by mass or less of crystalline polyamide, more preferably 80% by mass or less, and even more preferably 70% by mass or less, which allows the blending of amorphous polyamide, which will be described later.

[0056] The surface resin layer preferably contains 25% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more of amorphous polyamide. By containing 25% by mass or more of amorphous polyamide, extrusion suitability and stretchability are improved, facilitating the production of the base film 10. Examples of amorphous polyamide include a copolymer of hexamethylenediamine and isophthalic acid, a copolymer of metaxylenediamine and isophthalic acid, a copolymer of hexamethylenediamine and a dicarboxylic acid in which the molar ratio of isophthalic acid / terephthalic acid is 7 / 3, and a copolymer of metaxylenediamine and a dicarboxylic acid in which the molar ratio of adipic acid / isophthalic acid is 1 / 1.

[0057] The surface resin layer preferably contains 100% by mass or less of amorphous polyamide, more preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, which allows mixing of crystalline polyamide.

[0058] The surface resin layer is preferably made of amorphous aromatic polyamide alone or a mixture of 50% by mass or more but less than 100% by mass of amorphous aromatic polyamide and more than 0% by mass but less than 50% by mass of crystalline aromatic polyamide. This improves the oxygen barrier property after high retort treatment. More specifically, the oxygen permeability after high retort treatment described later is 1.0 cc / m or less. ２ ・This is preferable because it will be less than 1 day.

[0059] The thickness of the surface resin layer is preferably more than 0.1 μm and less than 5 μm, more preferably 0.3 μm or more and 2 μm or less, even more preferably 0.4 μm or more and 1.5 μm or less, and particularly preferably 0.6 μm or more and 1 μm or less. The lower limit of the thickness of the surface resin layer is preferably more than 0.1 μm, more preferably 0.3 μm or more, even more preferably 0.4 μm or more, and particularly preferably 0.6 μm or more. The upper limit of the thickness of the surface resin layer is preferably less than 5 μm, more preferably 2 μm or less, even more preferably 1.5 μm or less, and particularly preferably 1 μm or less. If it is 0.1 μm or less, film formation is difficult, and if it is 5 μm or more, curling is likely to occur. Furthermore, by making the thickness of the surface resin layer more than 0.1 μm, the density of the vapor-deposited film can be further improved, and the gas barrier properties can be further improved. By making it less than 5 μm, film-formability and processability can be further improved.

[0060] [Substrate] The surface resin layer can be formed by melt extrusion. The surface resin layer may be extruded onto a biaxially oriented polypropylene film to form the polypropylene substrate of the present invention, or may be co-extruded with polypropylene to form a multilayer structure, followed by stretching to form the polypropylene substrate of the present invention.

[0061] The substrate 100, which corresponds to the polypropylene substrate of the present invention, is composed of two or more layers including at least a polypropylene layer 110 and a base layer 115, and can be stretched biaxially as a whole. This can improve, for example, the heat resistance, impact resistance, water resistance, and dimensional stability of the barrier substrate. A laminate including such a barrier substrate is suitable, for example, as a packaging material that is subjected to boiling or retort treatment.

[0062] The stretching ratio when stretching in the machine direction (machine direction, MD of the substrate) is preferably 2 to 15 times, more preferably 5 to 13 times. The lower limit of the stretching ratio when stretching in the machine direction (machine direction, MD of the substrate) is preferably 2 to 15 times, more preferably 5 to 13 times. The lower limit of the stretching ratio when stretching in the machine direction (machine direction, MD of the substrate) is preferably 2 to 15 times, more preferably 5 to 13 times. The lower limit of the stretching ratio when stretching in the machine direction (machine direction, MD of the substrate) is preferably 2 to 15 times, more preferably 5 to 13 times. The upper limit of the stretching ratio when stretching in the machine direction (machine direction, MD of the substrate) is preferably 15 times or less, more preferably 13 times or less. The stretching ratio when stretching in the transverse direction (direction perpendicular to the MD direction, TD) is preferably 2 to 15 times, more preferably 5 to 13 times. The lower limit of the stretching ratio when stretching in the transverse direction (direction perpendicular to the MD direction, TD direction) is preferably 2 times or more, more preferably 5 times or more. The upper limit of the stretching ratio when stretching in the transverse direction (direction perpendicular to the MD direction, TD direction) is preferably 15 times or less, more preferably 13 times or less. By setting the stretching ratio to 2 times or more, the strength and heat resistance of the polypropylene layer can be further improved, and when the polypropylene layer is used as the outermost layer, the printability of the polypropylene layer can be improved. From the viewpoint of the breaking limit of the polypropylene layer, the stretching ratio is preferably 15 times or less.

[0063] The thickness of the substrate 100 is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less, and even more preferably 15 μm or more and 25 μm or less. The lower limit of the thickness of the substrate 100 is preferably 10 μm or more, more preferably 15 μm or more. The upper limit of the thickness of the substrate 100 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 25 μm or less. When the thickness is equal to or more than the lower limit, for example, the strength and heat resistance of the barrier substrate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the barrier substrate can be further improved.

[0064] The substrate 100 may be a coextruded stretched film. It can be produced by forming a laminated film using a conventionally known T-die method or inflation method, and then stretching the laminated film. When forming the film by the inflation method, the laminated film may be stretched at the same time.

[0065] The substrate 100 may be subjected to a surface treatment. This can improve adhesion to other layers, for example. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using one or more gases selected from oxygen gas, argon gas, nitrogen gas, etc., and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. In addition, an easy-adhesion layer may be provided on the surface of the substrate.

[0066] When the substrate 100 is used as the outermost layer of the laminate, a printed layer may be provided on the second layer. The image formed on the printed layer is not particularly limited, and examples thereof include letters, patterns, symbols, and combinations thereof. The printed layer may also be formed using ink derived from biomass. This further reduces the environmental impact.

[0067] Examples of methods for forming the printed layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of reducing environmental impact.

[0068] The substrate 100 is preferably transparent. Specifically, it preferably has a high total light transmittance as measured in accordance with JIS K 7361-1:1997. Specifically, it preferably has a total light transmittance of 70% or more, more preferably 80% or more, and particularly preferably 90% or more.

[0069] In the present invention, the underlayer containing a polyamide resin may be an anchor coat layer. The thickness of the anchor coat layer is preferably 0.02 μm or more and 5 μm or less, more preferably 0.05 μm or more and 2 μm or less, even more preferably 0.1 μm or more and 1 μm or less, and even more preferably 0.2 μm or more and 0.5 μm or less. The lower limit of the thickness of the anchor coat layer is preferably 0.02 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. The upper limit of the thickness of the anchor coat layer is preferably 5 μm or less, more preferably 2 μm or less, even more preferably 1 μm or less, and even more preferably 0.5 μm or less. By making the thickness of the anchor coat layer 0.02 μm or more, smoothness can be further improved, and gas barrier properties after deposition can be further improved. By making the thickness of the anchor coat layer 5 μm or less, processability and productivity can be further improved.

[0070] The anchor coat layer may be formed by coating (applying, coating) on ​​a biaxially stretched polypropylene substrate, or may be formed by coating on a polypropylene film and then biaxially stretched.

[0071] [Vapor-deposited Film] Next, the vapor-deposited film 120 will be described. The vapor-deposited film contains silicon oxide, an inorganic oxide. Silicon oxide is represented by SiOx. The vapor-deposited film may further contain metal oxides such as aluminum oxide, silicon nitride, silicon oxynitride, silicon carbide, magnesium oxide, titanium oxide, tin oxide, indium oxide, zinc oxide, and zirconium oxide, or nitrides or carbides of these metals, as long as the effects of the present invention are not impaired. Furthermore, for example, a mixture of silicon oxide (SiO) and silicon dioxide (SiO2) may be used as the vapor deposition material. In this case, the silicon oxide (SiO) content is preferably 50% by mass or more, and more preferably 60% by mass or more. This improves the water vapor barrier property after high-temperature retort treatment. More specifically, the vapor permeability after high-temperature retort treatment described below is 1.0 cc / m or less. ２ ・This is preferable because it will be less than 1 day.

[0072] The thickness of the vapor-deposited film is preferably 10 nm or more and 150 nm or less, more preferably 20 nm or more and 100 nm or less, and even more preferably 30 nm or more and 70 nm or less. The lower limit of the thickness of the vapor-deposited film is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. The upper limit is preferably 150 nm or less, more preferably 100 nm or less, and particularly preferably 70 nm or less.

[0073] The deposition film 120 can be formed using a conventionally known method. Examples of methods for forming the deposition film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Among these, the vacuum deposition method, which is a PVD method, is preferred. This improves the water vapor barrier properties after high retort treatment. More specifically, the water vapor permeability after high retort treatment described below is 1.0 cc / m ２ In the CVD method, carbon atoms (C) in the raw material enter the deposited film, which tends to reduce the barrier properties, particularly the water vapor permeability.

[0074] The deposited film 120 may be a single layer formed by a single deposition process or a multilayer formed by multiple deposition processes. In the case of a multilayer film, each layer may be made of the same material or different materials. Furthermore, each layer may be formed by the same method or different methods.

[0075] A vapor-deposited film 120 may be formed, and a layer containing an organic substance, such as the coating layer 130 described below, may be provided on the outer surface of the vapor-deposited film 120. This provides high barrier properties. Alternatively, a vapor-deposited film may be provided on the surface of the layer containing an organic substance, and another layer containing an organic substance may be provided on the outer surface of the vapor-deposited film, thereby repeatedly laminating vapor-deposited films and layers containing an organic substance.

[0076] A plasma-assisted vacuum deposition apparatus can be used as an apparatus for forming a vapor-deposited film by the PVD method. Details of this deposition method are disclosed in Japanese Patent Application Laid-Open No. 2011-214089.

[0077] A continuous vapor deposition film formation apparatus equipped with a plasma pretreatment chamber and a film formation chamber can be used as the apparatus used in the method for forming the vapor deposition film 120. In the plasma pretreatment chamber, plasma is irradiated onto the base layer 115 of the substrate 100 from a plasma supply nozzle. Next, in the film formation chamber, the vapor deposition film 120 is formed on the plasma-treated base layer 115. Details of this formation method are disclosed in International Publication No. 2019 / 087960.

[0078] The surface of the vapor-deposited film 120 may be subjected to plasma treatment, which can improve adhesion when a covering layer 130 is provided on the surface of the vapor-deposited film 120, as described below.

[0079] (XAFS Spectroscopic Analysis) XAFS analysis is an X-ray Absorption Fine Structure (XAFS) spectrum, in which X-rays are irradiated from the vapor-deposited surface side of the barrier film (or the coating layer side if a coating layer is present) and the amount of absorbed X-rays is measured. Detailed measurement conditions and analysis conditions are described in the Examples.

[0080] In particular, XAFS spectrum analysis using soft X-rays with synchrotron radiation can provide bulk information on the entire deposited film, rather than just a portion of the surface side of the deposited film, and can provide information on the amounts of oxygen and carbon in the silicon oxide deposited film. Furthermore, if the surface of the deposited film has a coating layer that does not contain silicon atoms, irradiating the deposited film from the surface side of the coating layer through the coating layer can also provide information on the deposited film in the presence of the coating layer. Furthermore, measurements can be made from the surface side of the silicon oxide deposited film before the coating layer is formed.

[0081] 4 shows the results of normalizing the XAFS measurement of the barrier films of the examples and comparative examples described below, in which the vertical axis represents absorption intensity (a.u) and the horizontal axis represents energy (eV).

[0082] The barrier film of the present invention has an intensity ratio P1, defined as follows: P1 = (maximum intensity between 1843.8 and 1845.2 eV) / (maximum intensity between 1847.0 and 1849.4 eV) = 0.37 to 0.78.

[0083] Here, the numerator (maximum intensity between 1843.8 and 1845.2 eV) is the intensity derived from intermediate silicon oxide (SiOx, x<2) (see A in FIG. 4 and the following figures), and the denominator (maximum intensity between 1847.0 and 1849.4 eV) is the intensity derived from high silicon oxide (SiOx, x=2) (see B in FIG. 4 and the following figures). Therefore, the intensity ratio P1 is a value that reflects the oxidation degree of silicon oxide.

[0084] The intensity ratio P1 is preferably 0.37 or more and 0.78 or less, more preferably 0.40 or more and 0.76 or less, and even more preferably 0.50 or more and 0.74 or less. The lower limit of the intensity ratio P1 is preferably 0.37 or more, more preferably 0.40 or more, and even more preferably 0.50 or more. The upper limit of the intensity ratio P1 is preferably 0.78 or less, more preferably 0.76 or less, and even more preferably 0.74 or less.

[0085] If the intensity ratio P1 is less than 0.37, the barrier property of the barrier film itself is poor, which is not preferred, and if it exceeds 0.78, the barrier property after high-temperature retort treatment is poor, which is not preferred.

[0086] The intensity ratio P1 in the barrier film can be adjusted by the composition of the material used for silica deposition or by aging treatment after the film formation process.

[0087] In the barrier film of the present invention, the intensity ratio P2 defined below is preferably 0.45 or more and 0.88 or less. The lower limit of the intensity ratio P2 defined below is preferably 0.45 or more. The upper limit of the intensity ratio P2 defined below is preferably 0.88. P2 = (maximum intensity between 1845.4 and 1846.4 eV) / (maximum intensity between 1847.0 and 1849.4 eV)

[0088] Here, the numerator (maximum intensity between 1845.4 and 1846.4 eV) is the intensity derived from SiC (see C in FIG. 4 and the following figures), and the denominator (maximum intensity between 1847.0 and 1849.4 eV) is the intensity derived from high-grade silicon oxide (SiOx, x = 2) (see B in FIG. 4 and the following figures). Therefore, the intensity ratio P2 is a value that reflects the amount of SiC present.

[0089] The intensity ratio P2 is preferably 0.45 or more and 0.88 or less, more preferably 0.49 or more and 0.83 or less. The lower limit of the intensity ratio P2 is preferably 0.45 or more, more preferably 0.49 or more. The upper limit of the intensity ratio P2 is preferably 0.88 or less, more preferably 0.83 or less.

[0090] If the intensity ratio P2 is less than 0.45, the barrier film itself will have poor barrier properties, which is not preferred, and if it exceeds 0.88, the barrier film will have poor barrier properties after high-temperature retort treatment, which is not preferred.

[0091] Since amorphous silicon oxide films are thought to have better flexibility than crystalline films, amorphous silicon oxide films are preferred for use as barrier films. However, it has been difficult to determine whether a film is crystalline or amorphous using conventional X-ray analysis, XRD, except when a clear crystalline peak can be confirmed.

[0092] It is known that sharp absorptions are observed at 1852.5 eV, 1856.0 eV, and 1859.0 eV in the XAFS spectrum of crystalline silicon oxide. In the XAFS spectrum of the present invention, no absorption is observed between 1850.0 eV and 1860.0 eV, which confirms that the silicon oxide film is amorphous.

[0093] The intensity ratio P2 in the barrier film can be adjusted in the same manner as the intensity ratio P1.

[0094] [Coating Layer] The coating layer 130 (not shown) formed on the vapor-deposited film 120 as needed is a coating layer that protects the vapor-deposited film mechanically and chemically and also improves the barrier performance.

[0095] The coating layer is formed by applying a barrier coating agent onto the vapor-deposited film and solidifying it. The barrier coating agent can be formed using a water-based emulsion or a solvent-based emulsion or solution.

[0096] Specific examples of water-based emulsions include polyamide-based emulsions, polyethylene-based emulsions, polyurethane-based emulsions, and water-soluble polymers, and specific examples of solvent-based emulsions include polyester-based emulsions.

[0097] As the polyurethane emulsion, for example, a mixture of a polyurethane emulsion and an emulsion of an oxazoline group-containing polymer is preferably used. The polyurethane emulsion may further contain a silane coupling agent.

[0098] As the water-soluble polymer, a polyvinyl alcohol resin or an ethylene-vinyl alcohol copolymer can be used alone, or a polyvinyl alcohol resin and an ethylene-vinyl alcohol copolymer can be used in combination.

[0099] Generally, polyvinyl alcohol resins obtained by saponifying polyvinyl acetate can be used. The polyvinyl alcohol resin may be a partially saponified polyvinyl alcohol resin in which several tens of percent of acetate groups remain, a fully saponified polyvinyl alcohol in which no acetate groups remain, or a modified polyvinyl alcohol resin in which OH groups have been modified. Regarding the degree of saponification of the polyvinyl alcohol resin, it is necessary to use at least one that undergoes crystallization to improve the film hardness of the gas barrier coating film, and preferably has a degree of saponification of 70% or more. Furthermore, polyvinyl alcohol resins with a degree of polymerization of approximately 100 to 5,000 can be used. Examples of such polyvinyl alcohol resins include RS-110 (saponification degree = 99%, polymerization degree = 1,000) manufactured by Kuraray Co., Ltd., and Gohsenol NM-14 (saponification degree = 99%, polymerization degree = 1,400) manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

[0100] The ethylene-vinyl alcohol copolymer may be a saponified copolymer of ethylene and vinyl acetate, i.e., a copolymer obtained by saponifying an ethylene-vinyl acetate random copolymer. For example, it may range from a partially saponified product in which several tens of mole percent of acetate groups remain to a completely saponified product in which only a few mole percent of acetate groups remain, or no acetate groups remain, and is not particularly limited. However, from the viewpoint of barrier properties, the lower limit of the degree of saponification is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. The upper limit is 100% or less.

[0101] 1, a vapor-deposited film 120 is formed, preferably by a PVD method, on the surface of a polypropylene substrate (substrate 100) provided with the above-described underlayer 115. The conveying speed of the substrate 100 in the vapor deposition step is preferably 180 m / min or more, and more preferably 300 m / min or more and 1000 m / min or less.

[0102] (Plasma Pretreatment Step) The plasma raw material gas supplied in the plasma pretreatment step before film formation is an inert gas alone, oxygen alone, or a mixed gas of oxygen gas and an inert gas, which is supplied from a gas reservoir through a flow rate controller while the gas flow rate is measured. The inert gas may be one or a mixed gas of two or more selected from the group consisting of argon, helium, and nitrogen.

[0103] For the plasma treatment, it is preferable to use an inert gas alone. As the other gas, a mixed gas of oxygen gas and the inert gas may be used. In this case, the mixing ratio of oxygen gas / inert gas is preferably 6 / 1 to 1 / 1, and more preferably 5 / 2 to 3 / 2.5.

[0104] (Film Forming Process) The deposition material in the film forming process is SiO and / or SiO ２ is preferably used.

[0105] In the film formation process, the deposition material is preferably heated by an electron beam (EB) heating method or an induction heating method, more preferably by an EB heating method. Furthermore, when the deposition material is heated by an induction heating method, a method in which plasma is supplied between the surface of the substrate 100 and the evaporation mechanism by a plasma supply mechanism, that is, plasma assistance during deposition, may be performed, as necessary.

[0106] The barrier film roll that has undergone the above-described film-forming process may be subjected to aging treatment (heating treatment) for a predetermined period of time. Specifically, conditions such as a temperature of 80°C and 168 hours can be exemplified. This has the effect of improving transmittance, and is effective when transparency is required for packaging containers.

[0107] (Coating Layer Forming Step) If necessary, the coating layer 130 may be formed on the vapor-deposited film 120. After the coating layer 130 is formed, an aging treatment may be further carried out.

[0108] (Laminate) Fig. 2 is a cross-sectional view showing an example of a laminate using a barrier film according to this embodiment. This laminate 200 is a laminate using the barrier film 100A of Fig. 1. That is, the barrier film 100A is composed of a polypropylene layer 110, an underlayer 115, and a vapor-deposited film 120. One surface of the barrier film facing the first polypropylene substrate 110 is laminated to the sealant layer 150 via a first adhesive layer 161, and the other surface of the barrier film facing the vapor-deposited film 120 is laminated to the second polypropylene substrate 140 via an adhesive layer 162. That is, the laminate has a three-layer film configuration of the second polypropylene substrate 140 / second adhesive layer 162 / barrier film / first adhesive layer 161 / sealant layer 150, with the barrier film serving as an intermediate layer. The following describes the configuration other than that of the barrier film 100A.

[0109] [Adhesive Layer] The surface of the barrier film facing the polypropylene layer 110 is laminated to the sealant layer 150 via a first adhesive layer 161, and the surface of the barrier film facing the coating layer 130 is laminated to the second polypropylene base material 140 via an adhesive layer 162. This improves the adhesion between the barrier film and the sealant layer, and between the first polypropylene base material and the second base material, and prevents the deterioration of barrier properties during heat sterilization treatment such as retort or boiling.

[0110] The first adhesive layer 161 and the second adhesive layer 162 may be a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive. The adhesive may be a solventless adhesive or a solvent-based adhesive suitable for dry lamination.

[0111] Examples of solvent-free adhesives, i.e., non-solvent lamination adhesives, include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives. Among these, urethane adhesives are preferred, and two-component curing urethane adhesives are more preferred.

[0112] Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and urethane-based adhesives. Among these, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are more preferred.

[0113] The thickness of the adhesive layer is preferably 0.1 μm or more and 10 μm or less, more preferably 1 μm or more and 7 μm or less, and even more preferably 3 μm or more and 5 μm or less. The lower limit of the thickness of the adhesive layer is, for example, preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more. The upper limit of the thickness of the adhesive layer is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less.

[0114] [Second Polypropylene Base Material] The second polypropylene base material 140 is laminated to the surface of the barrier film facing the coating layer 30 via a second adhesive layer 162. Here, a conventionally known biaxially oriented polypropylene film (OPP film) can be used as the second polypropylene base material.

[0115] In the case of a three-layer structure as shown in Figure 2, the printed layer (not shown) may be formed on the surface of the outermost layer of the second polypropylene base material 140, or on the surface of the second polypropylene base material 140 on the second adhesive layer 162 side.

[0116] [Sealant Layer] The sealant layer 150 contains a resin material that can be fused to each other by heat. Examples of the resin material that can be fused to each other by heat include polyolefins, and specific examples include polyethylenes such as low-density polyethylene, linear low-density polyethylene, and medium-density polyethylene, polypropylene, polybutene, methylpentene polymers, and cyclic olefin copolymers.

[0117] The sealant layer is preferably made of polypropylene. This allows the three-layer film to be made entirely of polypropylene, making it possible to achieve a mono-material packaging material. After collecting used packaging materials, there is no need to separate the substrate and the sealant layer, improving the recyclability of the packaging material. By making the sealant layer of polypropylene, oil resistance can also be improved, and the sealant layer can be made to withstand heat sterilization treatment.

[0118] The polypropylene content in the sealant layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, which can improve the recyclability of the packaging material, for example.

[0119] When the sealant layer is made of polypropylene, the content of polypropylene relative to the total amount of resin materials contained in the laminate is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and particularly preferably 90% by mass or more. This allows, for example, the laminate to be used to produce a mono-material packaging material, thereby improving the recyclability of the packaging material.

[0120] Examples of polypropylene include propylene homopolymers, propylene random copolymers such as propylene-α-olefin random copolymers, and propylene block copolymers such as propylene-α-olefin block copolymers. Details of α-olefins are as described above. From the viewpoint of heat sealability, the density of polypropylene is, for example, 0.88 g / cm ３ 0.92g / cm or more ３ The density is measured in accordance with JIS K7112, particularly Method D (density gradient tube method, 23°C). From the viewpoint of reducing the environmental load, biomass-derived polypropylene and / or recycled polypropylene may be used.

[0121] The sealant layer may contain additives. Examples of additives include crosslinkers, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, lubricants, antistatic agents, pigments, and modifying resins. For example, the sealant layer may contain an antistatic agent. This can suppress the generation of static electricity on the surface of the laminate, thereby suppressing adhesion between laminates, for example.

[0122] The sealant layer may have a single-layer structure or a multi-layer structure. The thickness of the sealant layer is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less. The lower limit of the thickness of the sealant layer is preferably 10 μm or more and more preferably 20 μm or more. The upper limit of the thickness of the sealant layer is preferably 200 μm or less and more preferably 150 μm or less. When the thickness is equal to or greater than the lower limit, for example, the lamination strength of a packaging material including the laminate can be further improved. When the thickness is equal to or less than the upper limit, for example, the processability of the laminate can be further improved. When a pouch (particularly a retort pouch) is produced from the laminate, the thickness of the sealant layer is more preferably 30 μm or more and 100 μm or less. When a pouch (particularly a retort pouch) is produced from the laminate, the lower limit of the thickness of the sealant layer is more preferably 30 μm or more. When a pouch (particularly a retort pouch) is produced from the laminate, the upper limit of the thickness of the sealant layer is more preferably 100 μm or less.

[0123] From the viewpoint of heat sealing properties, the sealant layer is preferably an unstretched resin film, more preferably an unstretched polyolefin film, such as an unstretched polypropylene film. The resin film can be produced by, for example, a casting method, a T-die method, or an inflation method. The sealant layer may be laminated via an adhesive layer as in this embodiment, or may be formed by melt-extruding a resin material that can be fused to the barrier film by heat onto the barrier film.

[0124] 3 is an example in which the vapor-deposited film 120 of the barrier film A is laminated to the sealant layer 150 via the first adhesive layer 161. As described above, in the present invention, the laminate is not limited to a three-layer film structure, and may also have a two-layer structure.

[0125] [Packaging Product] The above laminate can be used as a packaging product such as a packaging bag for containing contents such as food by forming the laminate into a bag shape with the sealant layer on the inside. The laminate of the present invention is a heat-sterilized laminate used for a packaging bag for containing retort foods or boiled foods.

[0126] The term "heat sterilization treatment" includes not only retort treatment but also boiling treatment, which refers to heat sterilization at 60 to 100°C for 10 to 60 minutes, for example.

[0127] Retort processing refers to a heat-pressure sterilization process at 100 to 140°C. The F value, which represents the integrated value of the heat load, is 4 or more, more specifically, a heat-pressure sterilization process at 121°C for 3 minutes or more, or 120°C for 4 minutes or more as defined by the Food Sanitation Act, is preferred. More specifically, 120 to 130°C and 15 to 60 minutes are common, but processing conditions of 105 to 120°C and 15 to 60 minutes, or 130 to 140°C and 15 to 60 minutes are also acceptable. In the present application, processing conditions of 130 to 140°C and 15 to 60 minutes are referred to as high retort processing.

[0128] (Water-Peel Strength) In the laminate of the present disclosure, after retorting at 128°C for 16 minutes, the water-peel strength when a film containing a polypropylene base film is peeled from a film containing a barrier film and a heat sealant film in accordance with JIS K 6854-2:1999 is preferably 0.3 N / 15 mm or more, more preferably 0.5 N / 15 mm or more, even more preferably 1.0 N / 15 mm or more, still more preferably 2.0 N / 15 mm or more, particularly preferably 2.1 N / 15 mm or more, and most preferably 3.0 N / 15 mm or more. By having a water-peel strength equal to or greater than the lower limit, when the laminate of the present disclosure is used for heat sterilization purposes, it is possible to suppress interlayer peeling or intralayer cohesive peeling of the laminate. A specific method for measuring the water-peel strength is described below.

[0129] Examples of films containing a polypropylene base film include a film consisting of only a polypropylene base film, a printed film in which a printed layer is formed on one side of a polypropylene base film, etc. Examples of films containing a barrier film and a heat sealant film include a film in which a barrier film and a heat sealant film are laminated via an adhesive layer.

[0130] A Tensilon universal material testing machine manufactured by Orientec Co., Ltd. was used as the tensile tester. First, the laminate of the present disclosure was cut into an A4 size, folded in half along the long side, with the heat sealant film facing the laminate, and three sides, including the fold, were heat-sealed to a width of 7 mm to produce a three-sided sealed packaging bag. 200 mL of tap water was filled into this packaging bag, and the remaining side was heat-sealed to seal the bag, resulting in a retort packaging bag filled with the contents. The retort packaging bag was subjected to a retort treatment at 128°C for 16 minutes using steam. Next, the laminate was cut from the packaging bag after the retort treatment so that the long side direction of the test piece coincided with the longitudinal direction (MD direction) of the polymer film 10 to produce a rectangular test piece with a short side of 15 mm. The film containing the polypropylene base film of the laminate and the film containing the barrier film and heat sealant film were peeled off 15 mm in the long side direction of the test piece. The film containing the polypropylene base film and the film containing the barrier film and heat sealant film are then gripped with a pair of gripping tools of the measuring instrument at the portions where the film containing the polypropylene base film and the film containing the barrier film and heat sealant film have already been peeled off. Water is dropped with a dropper onto the boundary between the portion where the film containing the polypropylene base film and the film containing the barrier film and heat sealant film remain bonded and the portion where the film containing the polypropylene base film and the film containing the barrier film and heat sealant film have been peeled off, as viewed along the longitudinal direction of the test piece. The pair of gripping tools are pulled in opposite directions (180° peel) perpendicular to the plane direction of the portion where the film containing the polypropylene base film and the film containing the barrier film and heat sealant film are still laminated, at a speed of 50 mm / min, and the average tensile stress in the stable region is measured. The distance S between the gripping tools is 30 mm when pulling begins, and 60 mm when pulling ends. The change in tensile stress with respect to the distance S passes through a first region and then enters a second region (stable region) where the rate of change is smaller than that in the first region. The average value of the tensile stress in the stable region is measured.Furthermore, rectangular test pieces with short sides of 15 mm were prepared by cutting the laminate from the packaging bag after the retort treatment so that the long side direction of the test piece coincided with the transverse direction (TD) of the polymer film 10. For each test piece, the film containing the polypropylene base film of the laminate and the film containing the barrier film and heat sealant film were peeled off by 15 mm in the long side direction. Thereafter, the average value of the tensile stress in the stable region was measured in the same manner as above. Of the smaller and larger measured values ​​obtained above, the smaller measured value was designated as the water-welded peel strength when the film containing the polypropylene base film of the laminate was peeled off from the film containing the barrier film and heat sealant film.

[0131] In the laminate of the present disclosure, the water-peeling strength basically corresponds to the adhesion strength between the underlayer and the vapor-deposited film. However, if the adhesion strength between the underlayer and the vapor-deposited film becomes too strong, cohesive failure of the adhesive layer between the polypropylene base film and the barrier film or peeling between the polypropylene base film and the printed layer may occur. In such cases, the cohesive failure strength or the peel strength between the polypropylene base film and the printed layer corresponds to the water-peeling strength. The peeled interface can be confirmed by evaluating the peeled portion of the test piece after measuring the water-peeling strength using FT-IR (ATR method) and XPS.

[0132] When measuring the water-exposed peel strength of a commercially available heat-sterilized food pouch, the laminate constituting the packaging bag can be cut to prepare a test piece so that the long side of the test piece coincides with the width direction of the packaging bag. Alternatively, the laminate constituting the packaging bag can be cut to prepare a test piece so that the long side of the test piece coincides with the direction perpendicular to the width direction of the packaging bag. The water-exposed peel strength of two test pieces is then measured using a tensile tester, and the smaller measured value is used as the water-exposed peel strength. The specific method for measuring the water-exposed peel strength of the test piece is the same as described above.

[0133] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way. First, barrier films according to Examples 1 to 18 and Comparative Examples 1 to 5 were produced using a conventionally known vacuum deposition apparatus based on the PVD method, except for Comparative Example 1 (Comparative Example 1 was produced using a CVD apparatus). The pretreatment conditions, deposition conditions, etc. are summarized in Table 1.

[0134] Example 1 The underlayer was made of 100% by mass of a copolymer of hexamethylenediamine and a dicarboxylic acid having a molar ratio of isophthalic acid / terephthalic acid of 7 / 3 (referred to as PA1 in Table 1), which is an amorphous aromatic polyamide. The polypropylene base layer was made of an acid-modified polypropylene random copolymer as the first layer, homopolypropylene as the second layer, and a layer of a copolymer of propylene, ethylene, and 1-butene as the third layer. These were co-extruded in the order of underlayer / first layer / second layer / third layer, and then stretched 5 times in the machine direction (MD direction) and 10 times in the transverse direction (TD direction) using a sequential biaxial stretching device to produce a 20 μm thick base film (substrate 100) (referred to as OPP in Table 1)) comprising a underlayer (0.7 μm), a first layer (1.5 μm), a second layer (17.1 μm), and a third layer (0.7 μm).

[0135] Before the film formation process, the following in-line pretreatment process was carried out. <Pretreatment Process> Using a plasma pretreatment mechanism, plasma pretreatment was carried out on the surface of the substrate 100 (surface of the underlayer 115) under the following conditions. <Pretreatment Conditions> Substrate conveying speed: 360 m / min Electrode: Ti target Power source: DC power source Power output: 10 kW Introduced gas type: Ar Introduced gas amount: 2000 sccm Pretreatment compartment pressure: 2.0 x 10 －１ Pa

[0136] Next, in the film formation process, a vapor deposition film containing silicon oxide was formed by vacuum deposition using an EB (electron beam) heating evaporation mechanism. Silicon oxide (SiO) was used as the vapor deposition material (referred to as Si1 in Table 1), and the film was formed at a conveying speed of 360 m / min and a transmittance of 70%. However, the transmittance was measured at a wavelength of 365 nm, and the transmittance when only the substrate was passed through was set to 100%. By setting the conveying speed and transmittance, the EB output was changed in conjunction. For example, the faster the conveying speed, the higher the EB output, and the lower the transmittance, the higher the EB output. The thickness of the vapor deposition film was 34 nm. The pressure during vapor deposition was 0.2 Pa.

[0137] Example 2 A barrier film of Example 2 was produced in the same manner as in Example 1, except that the conveying speed in the pretreatment step and the film-forming step was 300 m / min, the film was formed so that the transmittance was 66%, and the thickness of the vapor-deposited film was 43 nm.

[0138] Example 3 A barrier film of Example 3 was produced in the same manner as in Example 1, except that the conveying speed in the pretreatment step and the film-forming step was 360 m / min, the film was formed so that the transmittance was 86%, and the thickness of the vapor-deposited film was 17 nm.

[0139] Example 4 A barrier film of Example 4 was produced in the same manner as in Example 1, except that the conveying speed in the pretreatment step and the film-forming step was 360 m / min, the film was formed so that the transmittance was 73%, and the thickness of the vapor-deposited film was 30 nm.

[0140] Example 5 A barrier film of Example 5 was produced in the same manner as in Example 1, except that the conveying speed in the pretreatment step and the film-forming step was 200 m / min, the film was formed so that the transmittance was 62%, and the thickness of the vapor-deposited film was 61 nm.

[0141] Example 6 A barrier film of Example 6 was produced in the same manner as in Example 1, except that the pretreatment step was not carried out.

[0142] (Example 7) As a deposition material, 80 mass % of silicon oxide (SiO) and silicon dioxide (SiO ２A barrier film of Example 7 was produced in the same manner as in Example 1, except that a 20% by mass mixture of 20% by mass of 2-methyl-2-propanol (Si2) and 20% by mass of 2-methyl-2-propanol (Si2) was used (referred to as Si2 in Table 1), the conveying speed was 240 m / min, the transmittance of the deposited film was 71%, the thickness of the deposited film was 45 nm, and aging treatment was performed at 80°C for 168 hours after deposition.

[0143] (Example 8) As a deposition material, 60 mass % of silicon oxide (SiO) and silicon dioxide (SiO ２ A barrier film of Example 8 was produced in the same manner as in Example 7, except that a 40 mass% mixture of 1,2-dimethyl-2,3-trimethylsilyl 2,4 ...

[0144] Example 9 The barrier film of Example 9 was produced in the same manner as in Example 1, except that a liquid mixture of acrylic polyol and tolylene diisocyanate was coated on the vapor-deposited film and dried at 100°C for 10 seconds to form a urethane-based coating layer with a thickness of 0.6 µm.

[0145] Example 10 A barrier film of Example 10 was produced in the same manner as in Example 1, except that after deposition, an aging treatment was carried out at 55° C. for 168 hours.

[0146] Example 11 A barrier film of Example 11 was produced in the same manner as in Example 1, except that after deposition, an aging treatment was carried out at 80° C. for 168 hours.

[0147] Example 12 The barrier film of Example 12 was produced in the same manner as in Example 4, except that a mixture (shown as PA2 in Table 1) of 50% by mass of a copolymer of hexamethylenediamine and a dicarboxylic acid, which is a non-crystalline aromatic polyamide, and which has a molar ratio of isophthalic acid / terephthalic acid of 7 / 3, and 50% by mass of a copolymer of metaxylenediamine and adipic acid, which is a crystalline aromatic polyamide, was used as the underlayer.

[0148] Example 13 The barrier film of Example 13 was produced in the same manner as in Example 4, except that a mixture (referred to as PA3 in Table 1) of 80% by mass of a copolymer of hexamethylenediamine and a dicarboxylic acid, which is a non-crystalline aromatic polyamide, and which has a molar ratio of isophthalic acid / terephthalic acid of 7 / 3, and 20% by mass of a copolymer of metaxylenediamine and adipic acid, which is a crystalline aromatic polyamide, was used as the underlayer.

[0149] Example 14 A barrier film of Example 14 was produced in the same manner as in Example 4, except that a mixture (shown as PA4 in Table 1) consisting of 86 mass % of a copolymer of hexamethylenediamine and a dicarboxylic acid, which is a non-crystalline aromatic polyamide and has a molar ratio of isophthalic acid / terephthalic acid of 7 / 3, and 14 mass % of a homopolymer of 6-aminohexanoic acid units synthesized by ring-opening polymerization of ε-caprolactam, which is a crystalline aliphatic polyamide, was used as the underlayer.

[0150] Example 15 A barrier film of Example 15 was produced in the same manner as in Example 4, except that a mixture (shown as PA5 in Table 1) consisting of 90% by mass of a copolymer of hexamethylenediamine and a dicarboxylic acid, which is an amorphous aromatic polyamide and has a molar ratio of isophthalic acid / terephthalic acid of 7 / 3, and 10% by mass of a homopolymer of 6-aminohexanoic acid units synthesized by ring-opening polymerization of ε-caprolactam, was used as the underlayer.

[0151] Example 16 A barrier film of Example 16 was produced in the same manner as in Example 1, except that the thickness of the underlayer was set to 0.4 μm. The thickness of the substrate film of Example 16 was 19.7 μm.

[0152] Example 17 A barrier film of Example 17 was produced in the same manner as in Example 1, except that the thickness of the underlayer was 1.5 μm. The thickness of the substrate film of Example 17 was 20.8 μm.

[0153] Example 18 A barrier coating agent was prepared by the following procedure to form a barrier coating layer on the surface of the vapor-deposited film of Example 1. 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5 N hydrochloric acid were mixed to prepare a solution with a pH of 2.2. 175 g of tetraethoxysilane (metal alkoxide) was added to this solution while cooling to 10°C to obtain Solution A. 14.7 g of polyvinyl alcohol (water-soluble polymer) with a saponification degree of 99% or more and a degree of polymerization of 2400, 324 g of water, and 17 g of isopropyl alcohol were mixed to obtain Solution B. Solution A and Solution B were mixed in a mass ratio of 5.5:4.5 to obtain a barrier coating agent. The barrier coating agent was coated on the surface of the vapor-deposited film and dried at 100°C for 10 seconds. The thickness of the barrier coating layer formed by drying the barrier coating agent was 300 nm. In this manner, the barrier film of Example 18 was produced.

[0154] (Comparative Example 1) A barrier film of Comparative Example 1 was produced in the same manner as in Example 1, except that in the film formation process, no pretreatment step was performed and a 35 nm thick carbon-containing silicon oxide vapor deposition film (referred to as Si4 in Table 1) was formed using a plasma chemical vapor deposition apparatus (plasma CVD apparatus) under the following conditions: (Formation conditions) Hexamethyldisiloxane: oxygen gas: helium = 1:10:10 (unit: slm) Power supplied to electrode drum: 22 kW Line speed: 40 m / min deposition

[0155] Comparative Example 2 A barrier film of Comparative Example 2 was produced in the same manner as in Example 7, except that a mixture of 40 mass % silicon oxide (SiO) and 60 mass % silicon dioxide (SiO) (shown as Si5 in Table 1) was used as the vapor deposition material, a film was formed so as to have a transmittance of 82%, and the thickness of the vapor-deposited film was 60 nm.

[0156] Comparative Example 3 A barrier film of Comparative Example 3 was produced in the same manner as in Example 4, except that the conditions in the film formation step were changed to a conveying speed of 120 m / min and a pressure of 0.8 Pa during deposition.

[0157] Comparative Example 4 The barrier film of Comparative Example 4 was produced in the same manner as in Example 1, except that in the film formation step, plasma pretreatment was performed using a mixed gas of argon and oxygen at a volume ratio of 1:1, and in a continuously transported film formation section, a resistance heating method was used as a means for heating aluminum on the plasma-treated surface, and aluminum was vapor-deposited while introducing oxygen, thereby forming an aluminum oxide (alumina) vapor-deposited film having a thickness of 8 nm by a PVD method (shown as alumina in Table 1).

[0158] Comparative Example 5 A barrier film of Comparative Example 5 was produced in the same manner as in Example 1, except that a liquid mixture of acrylic polyol and tolylene diisocyanate was coated as the underlayer, and dried at 100°C for 10 seconds to form a urethane-based coating layer (labeled as AC in Table 1) with a thickness of 0.2 µm.

[0159] (Comparative Example 6) A substrate film of Comparative Example 6 was produced in the same manner as in Example 1, except that the thickness of the underlayer was set to 0.1 μm. However, since resin breakage occurred in the underlayer due to stretching, making film formation difficult, no further evaluation was performed.

[0160] (Comparative Example 7) A substrate film of Comparative Example 7 was produced in the same manner as in Example 1, except that the thickness of the undercoat layer was set to 5 μm. However, since the substrate film exhibited severe curling, subsequent evaluation was not performed.

[0161]

[0162] [Acquisition and analysis of XAFS spectra] For the barrier films of Examples 1 to 18 and Comparative Examples 1 to 3, XAFS spectra were obtained from the surface side of the barrier film (measured from the surface side of the vapor-deposited film or the surface side of the coating layer; for Example 18, measurement was made from the surface side of the vapor-deposited film before the formation of the coating layer) under the measurement conditions below. Of these, the results for Examples 1, 3, and 7 to 10 are shown in Figures 5 to 10, and the results for Comparative Examples 1 and 3 are shown in Figures 11 and 12. In the figures, the vertical axis represents the intensity of the emitted fluorescent X-rays (shown as absorption intensity (a.u) in the figures), and the horizontal axis represents the light (or X-ray) energy (eV). Note that for Comparative Example 5, the oxygen permeability of the barrier film alone was high, so XAFS measurement was not performed.

[0163] <XAFS spectrum acquisition> ・Line: Aichi Synchrotron Light Center BL6N1 ・Acceleration energy: 1.2 GeV ・Spectrometer type: Double crystal spectrometer ・Spectroscopic crystal: InSb(111) ・Beam size: Horizontal 2.0 mm x Vertical 1.0 mm ・Angle of incidence to sample: 45° ・Upstream slit size: Horizontal 10 mm x Vertical 3.0 mm ・Measurement method: Partial fluorescence yield method ・Light intensity monitor (I0): Au mesh ・Energy range (Si K-edge): 1820-1890 eV ・Energy step: 1820-1837 eV: 1.0 eV / step 1837-1860 eV: 0.2 eV / step 1860-1890 eV: 0.5 eV / step (Accumulation time: All 4 s / point)・Vacuum level in measurement tank (without sample): 1.0 x 10 －６ Pa or less: Energy calibration: The peak position at the S-K edge of K2SO4 is calibrated to 2481.70 eV

[0164] <XAFS Spectral Analysis> Intensity values ​​were normalized so that the absorption spectrum intensity value at the absorption X-ray energy value of 1828 to 1833 eV was 0 and the absorption spectrum intensity value at the absorption X-ray energy value of 1883.5 to 1888.5 eV was 1.

[0165] <Interpretation of XAFS Spectra> For silicon oxide, a peak is detected near 1848 eV for high oxides (SiOx, x = 2) and near 1845 eV for intermediate oxides (SiOx, x < 2). For silicon carbide, a peak is detected near 1846 eV. Therefore, the respective detected intensities were calculated as follows: Detection intensity near 1848 eV: maximum value from 1847.0 to 1849.4 eV (B in Figure 4 and subsequent figures) Detection intensity near 1845 eV: maximum value from 1843.8 to 1845.2 eV (A in Figure 4 and subsequent figures) Detection intensity near 1846 eV: maximum value from 1845.4 to 1846.4 eV (C in Figure 4 and subsequent figures) Then, P1 = (peak intensity near 1845 eV) / (peak intensity near 1848 eV) was calculated to obtain the degree of oxidation of silicon oxide, and P2 = (peak intensity near 1846 eV) / (peak intensity near 1848 eV) was calculated to obtain an index of the silicon carbide content.

[0166]

[0167] <Preparation of Laminate> For the barrier films of the Examples and Comparative Examples, the surface facing the coating layer 130 or the surface facing the vapor-deposited film 120 was bonded to a second biaxially oriented polypropylene film 140 (thickness: 20 μm) by dry lamination using a polyurethane-based two-component curing solvent-based adhesive, with a second adhesive layer 162 interposed therebetween. Furthermore, the surface of the barrier film opposite the vapor-deposited film 120 was bonded to a sealant layer 150 (unstretched polypropylene film 60 μm) by dry lamination using a two-component curing solvent-based adhesive, with a first adhesive layer 161 interposed therebetween, to prepare laminates of the Examples and Comparative Examples as shown in FIG.

[0168] <High Retort Treatment> The laminates of the examples and comparative examples were subjected to high retort treatment at 130° C. for 60 minutes.

[0169] <Measurement of Barrier Properties of Barrier Films and Laminates> The water vapor permeability and oxygen permeability of the barrier films of Examples and Comparative Examples and the laminates using the same were measured. The results are shown in Table 4.

[0170] Oxygen permeability (cc / (m ２ The oxygen permeability (OTR) was measured in accordance with JIS K 7126-2 using an oxygen transmission rate measuring device (manufactured by Mocon Co., Ltd., product name "OX-TRAN 2 / 20") under the measurement conditions of 23°C and 90% RH.

[0171] Water vapor permeability (g / (m ２ The water vapor transmission rate (day, indicated as "WVTR" in the table) was measured in accordance with JIS K 7129 B method under the measurement conditions of 40°C and 100% RH using a water vapor transmission rate measuring device (manufactured by Mocon, product name "PERMATRAN-W 3 / 31").

[0172] <Measurement of Barrier Properties of Barrier Films and Laminates> The barrier films of the Examples and Comparative Examples and the laminates using them were measured for water vapor permeability and oxygen permeability after a Gelbo Flex test under the following conditions. The results are shown in Table 3.

[0173] <Gelbo Flex Test After Retort Treatment> After retort treatment at 128°C for 16 minutes, the laminates using the barrier films of the Examples and Comparative Examples were subjected to a Gelbo Flex test under the following conditions in accordance with ASTM F392, and the water vapor transmission rate and oxygen transmission rate values ​​after the test were measured. The results are shown in Table 3. Gelbo Flex Test Conditions Testing machine: BE-1005 Gelbo Flex Tester, manufactured by Tester Sangyo Co., Ltd. Sample: A4 size (210 mm x 297 mm) laminate placed in a cylindrical shape on the testing machine Rotation amount: 400° rotation Stroke: 80 mm Number of times: 10

[0174] <Adhesion Test> (Peel Strength) The peel strength of the above laminate was measured as normal strength and water-wet peel strength in accordance with JIS K 6854-2:1999 by 180-degree peeling (unit: N / 15 mm) before and after retort treatment at 128°C for 16 minutes. The results are shown in Table 4. The measuring instrument used was a Tensilon universal material testing machine, product name: STA-1150, manufactured by Orientec Co., Ltd. The peel strength basically corresponds to the adhesion strength between the underlayer and the vapor-deposited film.

[0175] (Normal Peeling after Retort) The laminate was cut into an A4 size, folded in half along the long side, with the heat sealant film facing the other side. Three sides, including the fold, were heat-sealed at a width of 7 mm to produce a three-sided sealed packaging bag. This packaging bag was filled with 200 mL of tap water, and the remaining side was heat-sealed to seal the contents, producing a retort packaging bag. The retort packaging bag was subjected to a retort treatment at 128°C for 16 minutes using steam. Next, the laminate was cut from the packaging bag after retort treatment so that the long side of the test piece aligned with the MD direction to produce a rectangular test piece with a short side of 15 mm. For each test piece, the film containing the second biaxially oriented polypropylene film 140 of the laminate (hereinafter referred to as the A-side film) was peeled 15 mm along the long side from the film containing the barrier film 100A and the sealant layer 150 (hereinafter referred to as the B-side film). The A-side film and the B-side film at the peeled portion were gripped and pulled at a 180° peel angle at a rate of 50 mm / min, and the average tensile stress in the stable region was measured. The distance between the grippers was 30 mm when pulling started and 60 mm when pulling ended.

[0176] (Water-soaked peeling after retort) On the other hand, in the water-soaked peeling, water was dropped with a dropper onto the peel boundary (boundary between the joint and peeled portion) between the A-side film and the B-side film of the test piece that had been peeled 15 mm above, and then the peel strength was measured.

[0177] The normal peeling and water-soaked peeling before retorting were measured in the state of the laminate described above in <Preparation of Laminate>, without filling with tap water or performing retort treatment.

[0178]

[0179]

[0180] From Tables 2 to 4, it can be seen that laminates using barrier films using polypropylene base materials according to the present embodiment, in which the intensity ratio P1 obtained from the XAFS spectrum is from 0.37 to 0.78 or P2 is from 0.45 to 0.88, have high barrier properties after retort treatment and are excellent in Gelbo flex resistance and adhesion, even when a coating layer is not formed.

[0181] REFERENCE SIGNS LIST 100 Substrate (polypropylene substrate in the present invention) 110 Polypropylene layer 115 Undercoat layer 120 Vapor-deposited film 140 Second polypropylene substrate 150 Sealant layer 161 First adhesive layer 162 Second adhesive layer 200, 300 Laminate 100A Barrier film

Claims

1. A barrier film comprising a polypropylene substrate having an underlayer as the outermost layer, and a silicon oxide vapor-deposited film formed on the underlayer, laminated in this order, wherein the silicon oxide vapor-deposited film has an intensity ratio P1 of 0.37 or more and 0.78 or less when X-ray absorption fine structure analysis is performed on the surface of the barrier film opposite the polypropylene substrate: P1 = (maximum intensity between 1843.8 and 1845.2 eV) / (maximum intensity between 1847.0 and 1849.4 eV).

2. A barrier film comprising a polypropylene substrate having an underlayer as the outermost layer, and a silicon oxide vapor-deposited film formed on the underlayer, laminated in this order, wherein the silicon oxide vapor-deposited film has an intensity ratio P2 of 0.45 or more and 0.88 or less when X-ray absorption fine structure analysis is performed on the surface of the barrier film opposite the polypropylene substrate: P2 = (maximum intensity between 1845.4 and 1846.4 eV) / (maximum intensity between 1847.0 and 1849.4 eV).

3. The barrier film according to claim 1 or 2, wherein the underlayer contains a polyamide resin.

4. The barrier film according to claim 1 or 2, wherein the polypropylene substrate comprises at least the underlayer and a first layer in this order, and the first layer contains homopolypropylene.

5. The barrier film according to claim 1 or 2, wherein the polypropylene substrate comprises at least the underlayer, a first layer, and a second layer in this order, the first layer containing modified polypropylene, and the second layer containing homopolypropylene.

6. The barrier film according to claim 5, wherein the polypropylene substrate comprises at least the underlayer, a first layer, a second layer, and a third layer in this order, the first layer containing modified polypropylene, the second layer containing homopolypropylene, and the third layer containing a copolymer of propylene and an olefin other than propylene.

7. The barrier film according to claim 3, wherein the polyamide resin comprises an amorphous aromatic polyamide alone, or a mixture of 50% by mass or more but less than 100% by mass of an amorphous aromatic polyamide and more than 0% by mass but less than 50% by mass of a crystalline aromatic polyamide.

8. The barrier film according to claim 1 or 2, wherein a coating layer is laminated on the silicon oxide vapor-deposited film.

9. A laminate comprising the barrier film according to claim 1 or 2 and a sealant layer.

10. A packaging bag comprising the laminate according to claim 9.

11. A method for producing a barrier film comprising a polypropylene substrate having an underlayer as the outermost layer and a silicon oxide vapor-deposited film formed on the underlayer, laminated in this order, wherein the silicon oxide vapor-deposited film has an intensity ratio P1 of 0.37 to 0.78 or an intensity ratio P2 of 0.45 to 0.88 when X-ray absorption fine structure analysis is performed on the surface of the barrier film opposite the polypropylene substrate, wherein the silicon oxide vapor-deposited film is a vapor-deposited film formed by physical vapor deposition (PVD): P1 = (maximum intensity between 1843.8 and 1845.2 eV) / (maximum intensity between 1847.0 and 1849.4 eV) P2 = (maximum intensity between 1845.4 and 1846.4 eV) / (maximum intensity between 1847.0 and 1849.4 eV)

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