Gas barrier film, laminate and packaging bag

Abstract

To provide a gas barrier film which is excellent in all of light-shielding property, gas barrier property, adhesion to other resin film, and blocking resistance.SOLUTION: A gas barrier film includes a base material film containing polypropylene, ad a metal deposition layer, wherein the base material film has a multilayer structure including two layers of at least a core layer and a first skin layer, the first skin layer is one outermost surface layer of the base material film, the first skin layer contains a copolymer of propylene and α-olefin, an arithmetic average height Sa1 of the surface on the first skin layer side of the base material film is 30 nm or more and 80 nm or less, an arithmetic average height Sa2 of the surface on a side opposite to the first skin layer is 40 nm or more and 120 nm or less, and the metal deposition layer is arranged on the surface on the first skin layer side of the base material film.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas barrier film, a laminate, and a packaging bag. [Background technology]

[0002] Gas barrier films are widely used as packaging materials for foods, medical drugs, etc. When packaging these contents, it has been particularly important to reduce oxygen permeability. Gas barrier films used in such packaging materials generally use polyethylene terephthalate film, which has high heat resistance, as the base film.

[0003] However, in recent years, with growing awareness of environmental issues, there has been growing interest in packaging materials made from a single material, so-called monomaterial packaging, in order to make packaging materials recyclable. Since olefin-based films such as polypropylene are generally used as sealant layers for packaging materials, in order to produce monomaterial packaging using such sealant layers, it is necessary to use polypropylene as the base film for the gas barrier film as well. For example, Patent Documents 1 and 2 listed below propose monomaterial packaging materials using polypropylene. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-40257 [Patent Document 2] Patent Publication No. 2021-20391 Summary of the Invention [Problem to be solved by the invention]

[0005]

[0003] Gas barrier films are produced by forming at least a gas barrier vapor-deposited layer on a substrate film, but there is a problem in that blocking is likely to occur when the substrate film on which the vapor-deposited layer has been formed is wound into a roll. One method for suppressing this blocking is to use a substrate film having an uneven surface, but gas barrier films using such a substrate film have a problem in that the gas barrier properties are likely to deteriorate.

[0006] In addition, gas barrier films are laminated with other resin films containing polypropylene, such as a sealant layer, and used as packaging materials. Therefore, gas barrier films are required to have good adhesion to other resin films. In addition, gas barrier films are required to have light-blocking properties depending on the application.

[0007] Therefore, an object of the present invention is to provide a gas barrier film that has good light-blocking properties, gas barrier properties, adhesion to other resin films, and blocking resistance, as well as a laminate and a packaging bag using the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following gas barrier film, laminate, and packaging bag. [1] A gas barrier film comprising a base film containing polypropylene and a metal vapor deposition layer, wherein the base film has a multilayer structure including at least two layers, a core layer and a first skin layer, the first skin layer being one of the outermost layers of the base film, and the first skin layer containing a copolymer of propylene and an α-olefin, the arithmetic mean height Sa1 of the surface of the base film facing the first skin layer being 30 nm or more and 80 nm or less, and the arithmetic mean height Sa2 of the surface opposite to the first skin layer being 40 nm or more and 120 nm or less, and the metal vapor deposition layer being disposed on the surface of the base film facing the first skin layer. [2] The gas barrier film according to the above [1], wherein the value of Sa1+Sa2 is 80 nm or more and 150 nm or less. [3] The gas barrier film according to [1] or [2] above, wherein the first skin layer contains an antiblocking agent. [4] The gas barrier film according to any one of the above [1] to [3], further comprising a second skin layer which is the outermost layer on the opposite side of the base film from the first skin layer. [5] The gas barrier film according to any one of the above [1] to [4], wherein the metal vapor deposition layer is an aluminum vapor deposition layer. [6] The gas barrier film according to any one of the above [1] to [5], further comprising a gas barrier coating layer disposed on the surface of the metal vapor deposition layer opposite to the substrate film. [7] The gas barrier film according to any one of the above [1] to [6], further comprising an anchor coat layer disposed between the base film and the metal vapor deposition layer. [8] A laminate comprising the gas barrier film according to any one of the above [1] to [7] and a resin film containing polypropylene arranged on at least one surface of the gas barrier film. [9] A packaging bag comprising the laminate described in [8] above. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a gas barrier film that has good light-blocking properties, gas barrier properties, adhesion to other resin films, and blocking resistance, as well as a laminate and a packaging bag using the same. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing a substrate film according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing a gas barrier film according to one embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional view showing a laminate according to one embodiment of the present invention. [Figure 4] 1 is a schematic cross-sectional view showing a laminate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings where necessary, but the present invention is not limited to the following embodiments.

[0012] The gas barrier film according to this embodiment comprises a polypropylene-containing substrate film and a metal vapor deposition layer. The substrate film has a multilayer structure including at least two layers: a core layer and a first skin layer. The first skin layer is one of the outermost layers of the substrate film, and the first skin layer contains a copolymer of propylene and an α-olefin. The arithmetic mean height Sa1 of the surface of the substrate film facing the first skin layer is 30 nm to 80 nm, and the arithmetic mean height Sa2 of the surface opposite the first skin layer is 40 nm to 120 nm. The metal vapor deposition layer is disposed on the surface of the substrate film facing the first skin layer. The gas barrier film having the above-described configuration can exhibit excellent light-blocking properties, gas barrier properties, adhesion to other resin films, and blocking resistance. Details are described below.

[0013] <Base film> The substrate film is a film (base film) that serves as a support in the gas barrier film and contains polypropylene. The substrate film has a multilayer structure including at least two layers: a core layer and a first skin layer. The first skin layer is one of the outermost layers of the substrate film and contains a copolymer of propylene and an α-olefin. The substrate film has an arithmetic mean height Sa1 of 30 nm or more and 80 nm or less on the surface facing the first skin layer, and an arithmetic mean height Sa2 of 40 nm or more and 120 nm or less on the surface opposite the first skin layer.

[0014] The substrate film includes a first skin layer as one of its outermost layers, which contains a copolymer of propylene and an α-olefin and has an arithmetic mean height Sa1 of 30 to 80 nm. When a gas barrier film is produced by forming a metal vapor deposition layer on the first skin layer, the adhesion between the first skin layer and the metal vapor deposition layer is good, and defects such as cracks in the metal vapor deposition layer can be suppressed, resulting in good gas barrier properties. Furthermore, the substrate film has an arithmetic mean height Sa2 of 40 to 120 nm on the surface opposite the first skin layer, which can suppress blocking when the metal vapor deposition layer is formed on the first skin layer and then wound into a roll. Furthermore, when the arithmetic mean heights Sa1 and Sa2 of both surfaces of the substrate film are within the above ranges, a gas barrier film can be produced and laminated with other resin films, resulting in good adhesion to the other resin films.

[0015] Fig. 1 is a schematic cross-sectional view showing a substrate film according to one embodiment. The substrate film 1 shown in Fig. 1 has a three-layer structure consisting of a first skin layer 11, a core layer 12, and a second skin layer 13. The substrate film may have a two-layer structure consisting of the first skin layer 11 and the core layer 12, or may have a multi-layer structure of four or more layers that further includes layers other than the first skin layer 11, the core layer 12, and the second skin layer 13.

[0016] The base film 1 may be prepared by forming the materials of each layer into a sheet and stretching the sheet by conventional means to form a uniaxially or biaxially oriented film. Stretching may also be performed on a multilayer film. Known additives, such as organic additives including antioxidants, stabilizers, lubricants such as calcium stearate, fatty acid amides, and erucic acid amide, and antistatic agents, and inorganic additives including particulate lubricants such as silica, zeolite, syloid, hydrotalcite, and silicon particles, may be added to the base film 1 depending on the purpose.

[0017] The thickness (total thickness) of the base film 1 is not particularly limited, but may be, for example, 3 μm or more and 200 μm or less, or 6 μm or more and 50 μm or less.

[0018] The substrate film 1 has an arithmetic mean height Sa1 of 30 nm or more and 80 nm or less on the surface on the first skin layer 11 side, and an arithmetic mean height Sa2 of 40 nm or more and 120 nm or less on the surface opposite the first skin layer 11, i.e., the surface on the second skin layer 13 side.

[0019] The value of Sa1 must be 30 nm or more and 80 nm or less, but may be 40 nm or more and 80 nm or less from the viewpoint that when a gas barrier film is produced, the gas barrier properties and adhesion to other resin films are further improved, and blocking resistance is further improved.

[0020] The value of Sa2 must be 40 nm or more and 120 nm or less, but may be 45 nm or more and 110 nm or less from the viewpoint that when a gas barrier film is produced, the gas barrier properties and adhesion to other resin films are further improved, and blocking resistance is further improved.

[0021] The total value of Sa1 and Sa2 (Sa1+Sa2) is not particularly limited, but may be 80 nm or more and 150 nm or less, or 85 nm or more and 145 nm or less, from the viewpoint of further improving the gas barrier properties and adhesion to other resin films, and further improving the blocking resistance, when a gas barrier film is produced.

[0022] Here, the arithmetic mean height (Sa) is a parameter indicating the surface roughness of the base film 1, and means the average height of the irregularities on the surface of the base film 1. The arithmetic mean heights Sa1 and Sa2 of both surfaces of the base film 1 can be measured using a three-dimensional non-contact surface shape measurement system under the condition of a measurement area of ​​210 μm square.

[0023] The arithmetic mean heights Sa1 and Sa2 of the base film 1 can be adjusted by changing the type of resin used in the first skin layer 11 and the second skin layer 13; when multiple resins are used, the blending ratio and melting point of those resins; the addition and amount of an antiblocking agent; the roll surface condition during extrusion; and conditions for stretching after film formation. Homopolymers are used as resins because they are highly crystalline and therefore hard, and are less likely to block even when the surface is smooth, but tend to have poor adhesion. On the other hand, copolymers are softer resins, which tend to improve adhesion, but are more likely to block even when the surface is poorly smooth. When the base film does not have a second skin layer 13 and the core layer 12 forms the surface of the base film 1 opposite the first skin layer, the arithmetic mean height Sa2 can be adjusted by changing the conditions of the core layer 12 as described above.

[0024] The core layer 12 may contain polypropylene. From the viewpoint of enhancing the heat resistance of the base film 1, the polypropylene used in the core layer 12 may be crystalline polypropylene, or from the viewpoint of further improving the heat resistance, it may be homopolypropylene, which is a homopolymer of propylene. However, as long as the effects of the present invention are not significantly impaired, a random copolymer of propylene and an α-olefin, or a mixture of such a copolymer with homopolypropylene, may also be used.

[0025] In the base film 1, a first skin layer 11 is provided on one surface of the core layer 12, and a second skin layer 13 is provided on the other surface. Both surfaces of the base film 1 may be formed by the first skin layer 11 and the second skin layer 13. A layer other than the core layer 12 and the first skin layer 11 may be provided between them, or the core layer 12 and the first skin layer 11 may be in contact with each other without an intervening layer. A layer other than the core layer 12 and the second skin layer 13 may be provided between them, or the core layer 12 and the second skin layer 13 may be in contact with each other without an intervening layer.

[0026] The first skin layer 11 contains a copolymer of propylene and an α-olefin. This improves the adhesion between the first skin layer 11 and the core layer 12, and between the first skin layer 11 and the metal vapor deposition layer. Examples of the α-olefin include ethylene, 1-butene, and 1-hexene. The α-olefin may be used alone or in combination of two or more. The copolymer may be a random copolymer. The melting point of the resin used in the first skin layer 11 may be 130 to 150°C.

[0027] The second skin layer 13 may contain homopolypropylene or a copolymer of propylene and an α-olefin. However, from the viewpoint of improving adhesion to the core layer 12, it may contain a copolymer of propylene and an α-olefin. Examples of α-olefins include ethylene, 1-butene, and 1-hexene. The α-olefins may be used alone or in combination of two or more. The copolymer may be a random copolymer. The melting point of the resin used in the second skin layer 13 may be 130 to 150°C.

[0028] First skin layer 11 may contain an antiblocking agent. Second skin layer 13 may also contain an antiblocking agent. The antiblocking agent may be organic particles or inorganic particles. Examples of organic particles include acrylic resin particles, polymethyl methacrylate particles, polystyrene particles, and polyamide particles. Examples of inorganic particles include silica particles, zeolite, talc, kaolinite, and feldspar. The silica particles may be amorphous silica particles. These antiblocking agents may be used alone or in combination of two or more.

[0029] The average particle size of the antiblocking agent is not particularly limited, but is preferably 0.1 to 5 μm from the viewpoint of easily controlling the arithmetic mean heights Sa1 and Sa2 of the base film 1 within the above-mentioned ranges. The average particle size of the antiblocking agent is the weight average diameter measured by the Coulter method.

[0030] The content of the antiblocking agent in the first skin layer 11 is not particularly limited, but from the viewpoint of easily controlling the arithmetic mean height Sa1 within the above-mentioned range, it may be 100 to 3000 mass ppm, 200 to 2000 mass ppm, or 300 to 1500 mass ppm based on the total amount of the first skin layer 11.

[0031] The content of the antiblocking agent in the second skin layer 13 is not particularly limited, but from the viewpoint of easily controlling the arithmetic mean height Sa2 within the above-mentioned range, it may be 100 to 4000 mass ppm, 500 to 3500 mass ppm, or 1000 to 3000 mass ppm based on the total amount of the second skin layer 13.

[0032] In order to obtain the effects of the present invention more fully, the content of the antiblocking agent in the second skin layer 13 may be 1.0 times or more, or 1.2 times or more, the content of the antiblocking agent in the first skin layer 11.

[0033] The thickness of each of the first skin layer 11 and the second skin layer 13 may be 0.1 μm or more. If this thickness is 0.1 μm or more, the first skin layer 11, the core layer 12, and the second skin layer 13 can be uniformly laminated, and thickness variations in the first skin layer 11 and the second skin layer 13 can be reduced. It is also believed that defects in the metal vapor deposition layer can be further reduced, and deterioration of the barrier properties can be suppressed. From this perspective, the thickness of the first skin layer 11 and the second skin layer 13 is preferably 0.3 μm or more, and more preferably 0.5 μm or more. On the other hand, there is no particular upper limit to the thickness of the first skin layer 11 and the second skin layer 13, but from the perspective of more sufficiently ensuring the heat resistance of the entire substrate film 1, it is preferably 2.0 μm or less, and more preferably 1.8 μm or less.

[0034] The ratio of the thickness of first skin layer 11 to the thickness of core layer 12 (thickness of first skin layer 11 / thickness of core layer 12) may be 1 / 100 to 1 / 5, or 1 / 70 to 1 / 10. When the thickness ratio is within the above range, the heat resistance of the entire base film 1 can be more sufficiently ensured, and the adhesion between the layers in the gas barrier film and the laminate can be further improved.

[0035] The ratio of the thickness of second skin layer 13 to the thickness of core layer 12 (thickness of second skin layer 13 / thickness of core layer 12) may be 1 / 100 to 1 / 5, or 1 / 70 to 1 / 10. When the thickness ratio is within the above range, the heat resistance of the entire base film 1 can be more sufficiently ensured, and the adhesion between the layers in the gas barrier film and the laminate can be further improved.

[0036] The thickness of the first skin layer 11 and the thickness of the second skin layer 13 may be the same or different. The thickness of the first skin layer 11 may be equal to or less than the thickness of the second skin layer 13. The ratio of the thickness of the first skin layer 11 to the thickness of the second skin layer 13 (thickness of the first skin layer 11 / thickness of the second skin layer 13) may be 1 / 5 to 1 / 0.5, or 1 / 3 to 1 / 1. When the thickness ratio is within the above range, the heat resistance of the entire base film 1 can be more sufficiently ensured, and the adhesion between the layers in the gas barrier film and the laminate can be further improved.

[0037] The polypropylene (including copolymers of propylene and α-olefin) used in the base film 1 may be a recycled resin, or a resin obtained by polymerizing raw materials derived from biomass such as plants. When using these resins, they may be used alone or in combination with resins polymerized from ordinary fossil fuels.

[0038] <Gas barrier film> Fig. 2 is a schematic cross-sectional view showing a gas barrier film according to one embodiment. As shown in Fig. 2, the gas barrier film 10 according to this embodiment includes, in this order, a base film 1, a metal vapor deposition layer 2, and a gas barrier coating layer 3. The metal vapor deposition layer 2 is disposed on the surface of the base film 1 facing the first skin layer 11.

[0039] (Metal deposited layer) The metal vapor deposition layer is provided on the substrate film from the viewpoint of improving gas barrier properties against water vapor and oxygen, and from the viewpoint of light blocking properties. The metal vapor deposition layer is a vapor deposition layer containing a metal. From the viewpoint of gas barrier properties and light blocking properties, aluminum is preferred as the metal. The metal vapor deposition layer is preferably an aluminum vapor deposition layer formed by vapor-depositing aluminum.

[0040] The thickness of the metal vapor deposition layer may be 5 to 300 nm. When the thickness of the metal vapor deposition layer is 5 nm or more, a uniform and sufficiently thick film is easily obtained, allowing the film to fully function as a gas barrier film and more easily achieving better light blocking properties. Furthermore, when the thickness of the metal vapor deposition layer is 300 nm or less, flexibility can be imparted to the metal vapor deposition layer, making it less likely to crack even when subjected to external factors such as bending or pulling after film formation. From this perspective, the thickness of the metal vapor deposition layer is preferably 6 nm or more, preferably 150 nm or less, and more preferably 100 nm or less.

[0041] The metal vapor deposition layer can be formed by a conventional vacuum deposition method. Other thin film formation methods, such as sputtering, ion plating, and plasma vapor deposition (CVD), can also be used. However, considering productivity, vacuum deposition is currently the most advantageous method. The heating method used in vacuum deposition is preferably one of electron beam heating, resistance heating, and induction heating, but electron beam heating is more preferable considering the wide range of evaporation material options. Furthermore, to improve the adhesion between the metal vapor deposition layer and the substrate film and the density of the metal vapor deposition layer, deposition can also be performed using a plasma-assisted method or an ion beam-assisted method. Furthermore, to increase the transparency of the vapor deposition film, reactive deposition, in which various gases such as oxygen are blown in during deposition, is also acceptable.

[0042] To improve the adhesion between the substrate film and the metal vapor deposition layer, the substrate film may be subjected to a surface treatment such as plasma treatment or corona treatment on the surface of the substrate film facing the metal vapor deposition layer, and an anchor coat layer may be provided between the substrate film and the metal vapor deposition layer. By providing an anchor coat layer, adhesion and barrier properties can be further improved. Examples of coating agents for providing the anchor coat layer include acrylic resins, epoxy resins, acrylic urethane resins, polyester polyurethane resins, and polyether polyurethane resins. Among these coating agents, acrylic urethane resins and polyester polyurethane resins are preferred from the viewpoints of heat resistance and interlayer adhesive strength. The anchor coat layer will be described in more detail below.

[0043] The anchor coat layer is a layer containing an organic polymer as a main component and is sometimes called a primer layer. The provision of the anchor coat layer can improve the film-forming properties and adhesion strength of the metal vapor deposition layer or gas barrier coating layer.

[0044] The content of the organic polymer in the anchor coat layer may be, for example, 70% by mass or more, or 80% by mass or more, based on the total amount of the anchor coat layer. Examples of organic polymers include polyacrylic resins, polyester resins, polycarbonate resins, polyurethane resins, polyamide resins, polyolefin resins, polyimide resins, melamine resins, and phenolic resins. Considering the hot water resistance of the adhesive strength between the substrate film and the metal vapor deposition layer or gas barrier coating layer, it is preferable to include at least one of polyacrylic resins, polyol resins, polyurethane resins, polyamide resins, or reaction products of these organic polymers. The anchor coat layer may also include a silane coupling agent, an organic titanate, or a modified silicone oil.

[0045] More preferred examples of the organic polymer include an organic polymer having a urethane bond formed by the reaction of a polyol having two or more hydroxyl groups at the polymer terminal with an isocyanate compound, and / or an organic polymer containing a reaction product of a polyol having two or more hydroxyl groups at the polymer terminal with an organic silane compound such as a silane coupling agent or a hydrolyzate thereof.

[0046] Examples of polyols include at least one selected from acrylic polyol, polyvinyl acetal, polystyrene polyol, and polyurethane polyol. The acrylic polyol may be obtained by polymerizing an acrylic acid derivative monomer, or may be obtained by copolymerizing an acrylic acid derivative monomer with another monomer. Examples of the acrylic acid derivative monomer include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of the monomer copolymerized with the acrylic acid derivative monomer include styrene.

[0047] The isocyanate compound reacts with the polyol to form a urethane bond, thereby enhancing the adhesion between the substrate film and the metal deposition layer or gas barrier coating layer. That is, the isocyanate compound functions as a crosslinking agent or curing agent. Examples of isocyanate compounds include aromatic monomers such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic monomers such as xylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), and isophorone diisocyanate (IPDI), as well as polymers and derivatives thereof. The above-mentioned isocyanate compounds may be used alone or in combination of two or more.

[0048] Examples of silane coupling agents include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. The organic silane compound may be a hydrolyzate of these silane coupling agents. The organic silane compound may contain one of the above-mentioned silane coupling agents and their hydrolyzates, or two or more of them in combination.

[0049] The anchor coat layer can be formed by mixing the above-mentioned components in an organic solvent in any ratio to prepare a mixture, and then applying the mixture to one side of the substrate film. The mixture may contain, for example, a curing accelerator such as a tertiary amine, an imidazole derivative, a metal salt compound of a carboxylic acid, a quaternary ammonium salt, or a quaternary phosphonium salt; an antioxidant such as a phenol, sulfur, or phosphite; a leveling agent; a flow adjuster; a catalyst; a crosslinking reaction accelerator; a filler, etc.

[0050] The mixed solution can be coated onto the substrate film using a known printing method such as offset printing, gravure printing, or silk screen printing, or a known application method such as roll coating, knife edge coating, or gravure coating. After coating, the coated film can be heated to, for example, 50 to 200°C, and dried and / or cured to form an anchor coat layer.

[0051] The thickness of the anchor coat layer is not particularly limited and may be, for example, 0.005 to 5 μm. The thickness may be adjusted depending on the application or desired properties. The thickness of the anchor coat layer is preferably 0.01 to 1 μm, more preferably 0.01 to 0.5 μm. When the thickness of the anchor coat layer is 0.01 μm or more, sufficient adhesive strength is obtained between the substrate film and the metal deposition layer or gas barrier coating layer, and oxygen barrier properties are also good. When the thickness of the anchor coat layer is 1 μm or less, it is easy to form a uniform coated surface, and drying load and production costs can be reduced.

[0052] (Gas barrier coating layer) The gas barrier coating layer is provided as needed to protect the metal vapor deposition layer and complement its barrier properties. The gas barrier coating layer may be formed from a coating liquid containing a silicon compound or a hydrolyzate thereof and a water-soluble polymer having a hydroxyl group. Alternatively, the gas barrier coating layer may be formed from a coating liquid containing a water-soluble polymer having a hydroxyl group and at least one selected from the group consisting of a metal alkoxide, a silane coupling agent, and hydrolyzates thereof.

[0053] Examples of water-soluble polymers having hydroxyl groups include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. In particular, when polyvinyl alcohol (PVA) is used as a coating agent, it is preferred because it provides better gas barrier properties.

[0054] Examples of silicon compounds include Si(OR 1)4 and R 2 Si(OR 3 )3(OR 1 and OR 3 are each independently a hydrolyzable group, and R 2 is an organic functional group. It is preferable that the group is at least one selected from Si(OR 1 As R, it is preferable to use tetraethoxysilane [Si(OC2H5)4]. Tetraethoxysilane is preferably used because it is relatively stable in aqueous solvents after hydrolysis. 2 Si(OR 3 )R in 3 2 is preferably selected from the group consisting of a vinyl group, an epoxy group, a methacryloxy group, a ureido group, and an isocyanate group.

[0055] Examples of metal alkoxides include compounds represented by the following general formula (1). M(OR 11 ) m (R 12 ) n-m …(1) In the above formula, R 11 and R 12 are each independently a monovalent organic group having 1 to 8 carbon atoms, and are preferably an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, or Zr. m is an integer from 1 to n. 11 and R 12 If there are multiple 11 Comrades or R 12 They may be the same or different.

[0056] Specific 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.

[0057] The silane coupling agent includes a compound represented by the following general formula (2). Si(OR 21 ) p (R 22 ) 3-p R 23 …(2) In the above formula, R 21 represents an alkyl group such as a methyl group or an ethyl group, and R 22 represents a monovalent organic group such as an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkyl group substituted with an acryloxy group, or an alkyl group substituted with a methacryloxy group, and R 23 represents a monovalent organic functional group, and p represents an integer of 1 to 3. 21 or R 22 If there are multiple 21 Comrades or R 22 R may be the same or different. 23 Examples of the monovalent organic functional group represented by the formula (I) include a monovalent organic functional group containing a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or an isocyanate group. Compounds obtained by converting these silane coupling agents into polymers such as dimers and trimers may also be used.

[0058] Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0059] The gas barrier coating layer can be formed by mixing a water-soluble polymer dissolved in water or a water / alcohol mixed solvent with a silicon compound, a metal alkoxide, a silane coupling agent, etc., either directly or after being pre-treated by hydrolysis, and then coating the resulting solution on the metal vapor deposition layer and drying by heating. Known additives such as an isocyanate compound, a dispersant, a stabilizer, a viscosity modifier, and a colorant can also be added to the solution as needed, provided that the gas barrier properties are not impaired.

[0060] When PVA is used as the water-soluble polymer, the proportion of PVA in the mixed solution is preferably 20% by mass or more and 50% by mass or less, and more preferably 25% by mass or more and 40% by mass or less, based on the total solid content of the mixed solution. When the proportion of PVA is 20% by mass or more, the flexibility of the film is maintained, and it becomes easier to form a gas barrier coating layer. On the other hand, when the proportion of PVA is 50% by mass or less, the gas barrier film can be provided with sufficient gas barrier properties.

[0061] <Laminate> The laminate according to the present embodiment includes the gas barrier film 10 described above and a resin film containing polypropylene disposed on at least one surface of the gas barrier film 10. FIGS. 3 and 4 are schematic cross-sectional views showing a laminate according to one embodiment. The laminate 20 shown in FIG. 3 has a structure in which a resin film 22 containing polypropylene is laminated on the gas barrier coating layer 3 of the gas barrier film 10 via an adhesive layer 24, and a resin film 23 containing polypropylene is laminated on the second skin layer 13 of the gas barrier film 10 via the adhesive layer 24. The laminate 30 shown in FIG. 4 has a structure in which a resin film 22 containing polypropylene is laminated on the gas barrier coating layer 3 of the gas barrier film 10 via the adhesive layer 24.

[0062] The laminate preferably includes a sealant layer. In the laminate 20 shown in Fig. 3, it is preferable that at least one of the resin films 22 and 23 is a sealant layer, and it is more preferable that at least the resin film 23 is a sealant layer. On the other hand, in the laminate 30 shown in Fig. 4, it is preferable that the resin film 22 is a sealant layer.

[0063] To make the laminate a mono-material packaging material, polypropylene is used as the material for the resin films 22, 23. The resin film 23 used as the sealant layer in the laminate 20 and the resin film 22 used as the sealant layer in the laminate 30 may be, for example, a stretched or unstretched polypropylene film, and it is preferable to use an unstretched polypropylene film. On the other hand, the resin film 22 used as the second base film in the laminate 20 may be, for example, a film obtained by stretching homopolypropylene to impart heat resistance.

[0064] Polyethylene may be used as the material for the resin films 22 and 23. This allows the entire laminate to be a mono-material packaging material made of polyolefin. The polyethylene may be linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or very low-density polyethylene (VLDPE). Linear low-density polyethylene and low-density polyethylene have a density of 0.93 g / cm 3 less than 0.91 g / cm 3 More than 0.93g / cm 3 less than 0.912 g / cm 3 More than 0.928g / cm 3 or less, more preferably 0.915 g / cm 3 More than 0.925g / cm 3 Ultra-low density polyethylene has a density of 0.91 g / cm 3The polyethylene may be derived from fossil fuels or biomass. The polyethylene may also be recycled polyethylene obtained by mechanical recycling or chemical recycling.

[0065] The thickness of the resin film 22 used as the second base film in the laminate 20 is not particularly limited, but may be, for example, 3 μm or more and 200 μm or less, or 6 μm or more and 50 μm or less.

[0066] The thickness of the resin film 23 used as a sealant layer in the laminate 20 and the resin film 22 used as a sealant layer in the laminate 30 is not particularly limited, but may be, for example, 15 μm or more and 200 μm or less, or 40 μm or more and 100 μm or less.

[0067] The adhesive layer 24 bonds the films together. Examples of adhesives constituting the adhesive layer include polyurethane resins in which a bifunctional or higher isocyanate compound is reacted with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The various polyols may be used singly or in combination of two or more. For the purpose of promoting adhesion, the adhesive layer may contain a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, or the like blended with the polyurethane resin. The amount of adhesive layer to be applied is, for example, 0.5 to 10 g / m2, from the viewpoint of obtaining the desired adhesive strength, followability, processability, and the like. 2 From the viewpoint of environmental consideration, the adhesive layer may be made of a polymer component derived from biomass or biodegradable. Also, an adhesive having barrier properties may be used for the adhesive layer.

[0068] The laminate according to this embodiment may have a sealant layer on both surfaces. The laminate having sealant layers on both surfaces may be, for example, a laminate having a laminate structure of sealant layer / substrate film / metal vapor deposition layer / sealant layer, or a laminate structure of sealant layer / printing substrate / substrate film / metal vapor deposition layer / sealant layer. These laminates may further have a gas barrier coating layer, an anchor coat layer, an adhesive layer, or the like. The laminate having sealant layers on both surfaces may be a laminate 20 in which both resin films 22, 23 are sealant layers. A laminate having sealant layers on both surfaces can be used, for example, as a laminate for a laminate tube.

[0069] <Packaging bag> A packaging bag can be produced using the laminate described above. The packaging bag may be formed into a bag shape by folding one sheet of packaging material in half so that the sealant layers face each other and then heat-sealing three sides, or may be formed into a bag shape by stacking two sheets of packaging material so that the sealant layers face each other and then heat-sealing four sides. The packaging bag can contain contents such as food, medicine, etc. The packaging bag may also have a shape having a bent portion (folded portion) such as a standing pouch. The packaging bag according to this embodiment can maintain high gas barrier properties even in a shape having a bent portion. The packaging bag according to this embodiment has good adhesion between the layers and can maintain high gas barrier properties and light-blocking properties. [Example]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0071] [Examples 1 to 8 and Comparative Examples 1 to 3] <Preparation of base film> As the substrate films, the following substrates 1 to 9 were prepared.

[0072] (Base material 1) The first and second skin layers were made of an ethylene-1-butene-1-propylene random copolymer resin with a melting point of 148°C, and the core layer was made of a homopolypropylene resin. Amorphous silica particles were added to the first and second skin layers as an antiblocking agent (hereinafter referred to as "AB agent") in the amounts shown in Table 1. The resins for each of the above layers were co-extruded and biaxially stretched to produce a substrate 1 with a total thickness of 20 μm and a three-layer structure consisting of a first skin layer, a core layer, and a second skin layer. The thicknesses of the first and second skin layers were both 0.7 μm, and the core layer was 18.6 μm.

[0073] (Base material 2) Substrate 2 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that an ethylene-propylene random copolymer resin with a melting point of 132°C was used as the material for the first and second skin layers, and acrylic resin particles were added as an AB agent in the amount shown in Table 1.

[0074] (Base material 3) Substrate 3 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that ethylene-1-butene-1-propylene random copolymer resins with melting points of 160°C and 146°C were used as the materials for the first skin layer, and ethylene-propylene random copolymer resin with a melting point of 132°C was used as the material for the second skin layer, and acrylic resin particles were added as an AB agent in the amount shown in Table 1.

[0075] (Base material 4) Substrate 4 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that an ethylene-propylene random copolymer resin with a melting point of 132°C was used as the material for the first skin layer, and ethylene-1-butene-1-propylene random copolymer resins with melting points of 150°C and 135°C were used as the material for the second skin layer, and amorphous silica particles were added as an AB agent in the amounts shown in Table 1.

[0076] (Base material 5) Substrate 5 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that an ethylene-propylene random copolymer resin with a melting point of 146°C was used as the material for the first skin layer, and a homopolypropylene resin with a melting point of 215°C was used as the material for the core layer and second skin layer, and amorphous silica particles as an AB agent were not added to the first skin layer, but were added to the second skin layer in the amount shown in Table 1.

[0077] (Base material 6) The first skin layer was made of an ethylene-propylene random copolymer resin with a melting point of 146°C, and the core layer was made of a homopolypropylene resin with a melting point of 215°C. Amorphous silica particles were added to the first skin layer as an AB agent in the amounts shown in Table 1. The resins for each of the above layers were co-extruded and biaxially stretched to produce a substrate 6 with a two-layer structure (first skin layer / core layer) and a total thickness of 20 μm. The thickness of the first skin layer was 1 μm, and the thickness of the core layer was 19 μm.

[0078] (Base material 7) Substrate 7 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that an ethylene-propylene random copolymer resin with a melting point of 146°C was used as the material for the first and second skin layers, and acrylic resin particles as an AB agent were not added to the first skin layer, but were added to the second skin layer in the amount shown in Table 1.

[0079] (Base material 8) Substrate 8 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that ethylene-1-butene-1-propylene random copolymer resins with melting points of 160°C and 134°C were used as the materials for the first and second skin layers, and amorphous silica particles were added as an AB agent in the amounts shown in Table 1.

[0080] (Base material 9) Substrate 9 having a total thickness of 20 μm was prepared in the same manner as Substrate 1, except that a homopolypropylene resin with a melting point of 215°C was used as the material for the first and second skin layers and the core layer, and acrylic resin particles were added as an AB agent in the amount shown in Table 1.

[0081] <Measurement of arithmetic mean height Sa> The arithmetic mean height Sa1 of the surface on the first skin layer side of substrates 1 to 9 and the arithmetic mean height Sa2 of the surface on the side opposite the first skin layer (the second skin layer side for substrates 1 to 5 and 7 to 9, and the core layer side for substrate 6) were measured using a three-dimensional non-contact surface profile measurement system (VertScan R3300h Lite, manufactured by Ryoka Systems Co., Ltd.) over a measurement area of ​​210 μm square. The results are shown in Table 1.

[0082] [Table 1]

[0083] <Preparation of gas barrier film> An acrylic primer solution was gravure coated onto the first skin layer of the substrate film shown in Table 2, and then dried to form an anchor coat layer with a thickness of 0.1 μm. Next, a thin aluminum film with a thickness of 60 nm was deposited onto the anchor coat layer by reactive deposition using high-frequency excited ion plating in an oxygen atmosphere under reduced pressure, to form a vapor-deposited layer made of aluminum (aluminum vapor-deposited layer).

[0084] Next, tetraethoxysilane (hereinafter referred to as "TEOS"), methanol, and 0.1N hydrochloric acid were mixed in a mass ratio of 45 / 15 / 40 to obtain a TEOS hydrolysis solution. This solution, a 5 mass% aqueous solution of polyvinyl alcohol (hereinafter referred to as "PVA"), and a 1 / 1 solution of 1,3,5-tris(3-methoxysilylpropyl) isocyanurate in water / IPA (isopropyl alcohol) at a solid content of 5 mass% (R 2A coating solution was prepared by mixing these three solutions. The coating solution was prepared so that the mass ratio of the SiO2 solid content (converted value) of TEOS, the R2Si(OH)3 solid content (converted value) of isocyanurate silane, and the PVA solid content was 40 / 5 / 55. This coating solution was applied to the metal vapor deposition layer by gravure coating and then dried at 80°C for 60 seconds to form a gas barrier coating layer with a thickness of 0.3 μm. In this way, a gas barrier film having a laminate structure of gas barrier coating layer / metal vapor deposition layer / anchor coat layer / first skin layer / core layer / second skin layer (Examples 1 to 5, 7 to 8, and Comparative Examples 1 to 3) or gas barrier coating layer / metal vapor deposition layer / anchor coat layer / first skin layer / core layer (Example 6) was obtained.

[0085] <Preparation of Laminates in Examples 1 to 6 and Comparative Examples 1 to 3> The gas barrier coating layer side of the gas barrier films produced in Examples 1 to 6 and Comparative Examples 1 to 3 was bonded to a 20 μm thick biaxially oriented polypropylene film by dry lamination using a two-component curing urethane adhesive. Then, the second skin layer or core layer side of the gas barrier film was bonded to a 60 μm thick unstretched polypropylene film by dry lamination using a two-component curing urethane adhesive to produce a three-layer laminate.

[0086] <Preparation of Laminates in Examples 7 and 8> The gas barrier coating layer side of the gas barrier film produced in Examples 7 and 8 was bonded to a 60 μm thick unstretched polypropylene film using a two-component curing urethane adhesive by dry lamination to produce a two-layer laminate.

[0087] [evaluation] <Blocking resistance> In the preparation of the gas barrier film described above, an anchor coat layer and a metal-deposited layer were formed on the first skin layer of the substrate film to form a test specimen for evaluating blocking resistance. Two such test specimens were prepared and stacked so that the surface of the metal-deposited layer of one test specimen faced the surface of the other test specimen opposite the metal-deposited layer (the second skin layer or core layer side). A pressure of 1 MPa was applied, and the test specimens were left at 25°C and 65% RH for 24 hours. After the standing time, the stacked test specimens were cut into 150 mm wide x 500 mm long pieces, and the peel strength between the two test specimens was measured. The peel strength was measured using a Tensilon universal material testing machine (RTC-1250, manufactured by A&D Co., Ltd.). This peel strength was used as an index of the blocking resistance of the substrate film and was evaluated according to the following criteria. The results are shown in Table 2. A grade of "A" indicated that the substrate film had excellent blocking resistance. A grade of "B" indicated that the following adhesion strength evaluation was not performed. A: Peel strength is less than 0.5N / 150mm. B: Peel strength is 0.5N / 150mm or more.

[0088] <Oxygen Transmission Rate (OTR)> The oxygen permeability of the laminates produced in the examples and comparative examples was measured. The measurement was carried out using an oxygen permeability measuring device (OXTRAN 2 / 20, manufactured by Modern Control) under conditions of a temperature of 30°C and a relative humidity of 70%. The measurement method complies with JIS K-7126, Method B (constant pressure method) and ASTM D3985-81, and the measurement value is expressed in units of cm 3 (STP) / m 2 The results are shown in Table 2.

[0089] <Water vapor transmission rate (WVTR)> The water vapor permeability of the laminates produced in the examples and comparative examples was measured in an atmosphere of 40°C and 90% RH. The measurement was performed in accordance with JIS K7129 using a water vapor permeability measuring device (manufactured by MOCON, trade name: PERMATRAN 3 / 34G). The measured value is expressed in units of [g / m 2 The results are shown in Table 2.

[0090] <Adhesion strength> The laminates prepared in the examples and comparative examples were cut into a size of 150 mm wide x 500 mm long, and the adhesion strength was measured. When the laminate had a three-layer structure, the adhesion strength between the biaxially oriented polypropylene film (OPP) and the first skin layer, and the adhesion strength between the second skin layer and the unstretched polypropylene film (CPP) were measured. When the laminate had a two-layer structure, the adhesion strength between the first skin layer and the unstretched polypropylene film (CPP) was measured. The results are shown in Table 2.

[0091] <Light blocking property> The central portion of the laminate produced in the examples and comparative examples was cut into a piece approximately 1 cm square, and the optical density (OD value) was measured. The measurement was performed using a black and white transmission densitometer (manufactured by X-Rite, product name: 361T). The results are shown in Table 2. An optical density of 2.00 or higher can be said to have good light-blocking properties.

[0092] [Table 2] [Explanation of symbols]

[0093] 1...base film, 2...metal vapor deposition layer, 3...gas barrier coating layer, 10...gas barrier film, 11...first skin layer, 12...core layer, 13...second skin layer, 20, 30...laminate, 22, 23...resin film, 24...adhesive layer

Claims

1. A gas barrier film comprising a base film containing polypropylene and a metal vapor deposition layer, the substrate film has a multilayer structure including at least two layers, a core layer and a first skin layer; the first skin layer is one outermost layer of the base film, the first skin layer comprises a copolymer of propylene and an α-olefin; an arithmetic mean height Sa1 of the surface of the base film on the first skin layer side is 30 nm or more and 80 nm or less, and an arithmetic mean height Sa2 of the surface opposite to the first skin layer is 40 nm or more and 120 nm or less, The gas barrier film, wherein the metal vapor deposition layer is disposed on the surface of the base film on the side of the first skin layer.

2. 2. The gas barrier film according to claim 1, wherein the value of Sa1+Sa2 is 80 nm or more and 150 nm or less.

3. The gas barrier film of claim 1 , wherein the first skin layer comprises an antiblocking agent.

4. The gas barrier film according to claim 1 , further comprising a second skin layer that is the outermost layer of the substrate film on the side opposite to the first skin layer.

5. The gas barrier film according to claim 1 , wherein the metal vapor deposition layer is an aluminum vapor deposition layer.

6. The gas barrier film according to claim 1 , further comprising a gas barrier coating layer disposed on the surface of the metal vapor deposition layer opposite to the substrate film.

7. The gas barrier film according to claim 1 , further comprising an anchor coat layer disposed between the substrate film and the metal vapor deposition layer.

8. A laminate comprising the gas barrier film according to any one of claims 1 to 7 and a resin film containing polypropylene disposed on at least one surface of the gas barrier film.

9. A packaging bag comprising the laminate according to claim 8.

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