Packaging film, packaging container, and packaged product

Abstract

To provide a packaging film, a packaging bag, and a packaged product capable of having excellent gas barrier properties while suppressing a decrease in the ratio of polyolefin-based resin in the entire packaging film.SOLUTION: A packaging film includes a gas barrier film, an adhesive layer, and a sealant layer in this order. The gas barrier film includes a base material layer, an anchor coat layer, and a vapor deposition layer in this order. The base material layer includes a polyolefin-based base material layer containing a polyolefin-based resin. The anchor coat layer contains a polyurethane resin and has a thickness of 0.02 μm or more. The adhesive layer is obtained by bonding an adhesive resin composition containing a polyolefin-based adhesive resin to the gas barrier film by melt extrusion. The sealant layer contains a polyolefin-based resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to packaging films, packaging containers, and packaged products. [Background technology]

[0002] In recent years, packaging films have been increasingly made of monomaterials to facilitate material recycling, but packaging films are also required to maintain functionality such as gas barrier properties. In contrast to this, a packaging film can be considered in which a gas barrier film, which is formed by providing a gas barrier layer by vapor deposition on a polyolefin base layer containing a polyolefin resin, and a polyolefin sealant layer containing a polyolefin resin are bonded together by dry lamination using an adhesive capable of forming a non-polyolefin resin. However, such packaging films use adhesives that can form non-polyolefin-based resins, which reduces the quality of the recycled resin obtained by material recycling of the packaging films. Therefore, in order to prevent the quality of recycled resin from deteriorating, a laminate is known that uses an adhesive resin composition containing a polyolefin adhesive resin such as maleic anhydride graft-polymerized polypropylene as an adhesive layer, instead of an adhesive that can form a non-polyolefin resin (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-049679 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although the laminate described in Patent Document 1 can increase the proportion of polyolefin resin in the entire laminate, there is still room for improvement in terms of gas barrier properties.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a packaging film, a packaging container, and a packaging product that can have excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin-based resin in the entire packaging film. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one aspect of the present disclosure provides a packaging film comprising a gas barrier film, an adhesive layer, and a sealant layer in this order, the gas barrier film having a base layer, an anchor coat layer, and a vapor deposition layer in this order, the base layer having a polyolefin-based base layer containing a polyolefin-based resin, the anchor coat layer containing a polyurethane resin, the anchor coat layer having a thickness of 0.02 μm or more, the adhesive layer being obtained by laminating an adhesive resin composition containing a polyolefin-based adhesive resin to the gas barrier film by melt extrusion, and the sealant layer containing a polyolefin-based resin. The packaging film can have excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin resin in the entire packaging film.

[0007] The inventors of the present disclosure speculate that the reason why the above effects are obtained is as follows. That is, when an adhesive resin composition containing a polyolefin adhesive resin is laminated to a gas barrier film by melt extrusion, the heat of the adhesive resin composition is transferred to the substrate layer through the vapor deposition layer. The polyolefin adhesive resin composition is at a high temperature when it contacts the gas barrier film, but is then cooled by a cooling roll to a low temperature. Accordingly, even if the polyolefin substrate layer expands and then shrinks, the anchor coat layer containing a polyurethane resin effectively relieves the expansion stress and contraction stress transferred from the substrate layer to the vapor deposition layer, thereby preventing the fragile vapor deposition layer from expanding or contracting. As a result, the packaging film can have excellent gas barrier properties. Furthermore, by having a thickness of 0.02 μm or more, the anchor coat layer can effectively suppress the expansion and contraction of the polyolefin-based base layer even though it is thin, thereby preventing a decrease in the proportion of polyolefin-based resin in the entire packaging film.

[0008] In the packaging film, the anchor coat layer preferably has a thickness of 2.0 μm or less. In this case, a decrease in the proportion of polyolefin resin in the entire packaging film can be further suppressed.

[0009] In the packaging film, the polyolefin-based substrate layer is preferably a stretched film. In this case, the crystallinity of the polyolefin-based base material layer contained in the base material layer is improved, and the melting point can be increased, thereby increasing the difference in melting point between the sealant layer and the base material layer, making it easier to prevent the base material layer from melting when the packaging film is heat-sealed.

[0010] In the packaging film, it is preferable that the gas barrier film further includes a coating layer between the vapor deposition layer and the adhesive layer, the coating layer covering the vapor deposition layer. In this case, after the adhesive resin composition is bonded to the gas barrier film by melt extrusion, when the adhesive resin composition expands and contracts, the expansion stress and contraction stress are not transmitted directly to the vapor deposition layer but are transmitted indirectly via the coating layer, thereby suppressing contraction of the vapor deposition layer.

[0011] The anchor coat layer preferably has a thickness of 0.2 μm or more. When the anchor coat layer has a thickness of 0.2 μm or more, the deterioration of the gas barrier properties can be more effectively suppressed even after moist heat treatment such as retort treatment or boiling treatment, compared to when the anchor coat layer has a thickness of less than 0.2 μm.

[0012] The anchor coat layer preferably has a thickness of less than 2.5 μm. When the anchor coat layer has a thickness of less than 2.5 μm, the decrease in the proportion of polyolefin resin in the entire packaging film can be suppressed compared to when the thickness of the anchor coat layer is 2.5 μm or more, and the decrease in gas barrier properties can also be further suppressed even after moist heat treatment such as retort treatment or boiling treatment.

[0013] Another aspect of the present disclosure provides a packaging container including the packaging film described above. The packaging container may be a packaging bag. The packaging container includes the packaging film described above, and the packaging film makes it possible to have excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin-based resin in the entire packaging film. Therefore, the packaging container makes it possible to have excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin-based resin in the entire packaging container.

[0014] Yet another aspect of the present disclosure provides a packaging product including the packaging container described above and a content contained in the packaging container. The packaging product includes the packaging container described above, and the packaging container can have excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin resin in the entire packaging container. Therefore, the packaging product can be easily recycled after opening and can also suppress deterioration of the quality of the contents.

[0015] In this specification, polyolefin resins are also referred to as polyolefin resins, polyethylene resins are also referred to as polyethylene resins, and polypropylene resins are also referred to as polypropylene resins. [Effects of the Invention]

[0016] According to the present disclosure, a packaging film, a packaging container, and a packaged product are provided that can have excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin resin in the entire packaging film. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view showing one embodiment of a packaging film of the present disclosure. [Figure 2] 1 is a cross-sectional view illustrating one embodiment of a packaging product of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described in detail, but the present invention is not limited to the following embodiments.

[0019] <Packaging film> First, an embodiment of the packaging film of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing one embodiment of the packaging film of the present disclosure.

[0020] 1 comprises, in this order, a gas barrier film 10, an adhesive layer 60, and a sealant layer 70. The gas barrier film 10 comprises, in this order, a substrate layer 20, an anchor coat layer 30, and a vapor deposition layer 40. The substrate layer 20 comprises a polyolefin substrate layer 21 containing a polyolefin resin. The adhesive layer 60 is obtained by laminating an adhesive resin composition containing a polyolefin-based adhesive resin to the gas barrier film 10 by melt extrusion. The sealant layer 70 includes a polyolefin resin. The base layer 20 may further include a heat-resistant layer 22. The heat-resistant layer 22 contains a high-melting-point resin having a melting point of 180° C. or higher. The packaging film 100 may further include a coating layer 50 between the vapor-deposited layer 40 and the adhesive layer 60, which coats the vapor-deposited layer 40.

[0021] According to the packaging film 100, it is possible to suppress a decrease in the proportion of polyolefin resin in the entire packaging film 100, while at the same time providing excellent gas barrier properties.

[0022] The gas barrier film 10, adhesive layer 60, and sealant layer 70 will be described in detail below.

[0023] (1) Gas barrier film The gas barrier film 10 has a substrate layer 20 and a vapor deposition layer 40. The substrate layer 20 has a polyolefin substrate layer 21 containing a polyolefin resin. The substrate layer 20 may further have an adhesive layer (hereinafter also referred to as a "substrate adhesive layer") between the polyolefin substrate layer 21 and the heat-resistant layer 22, as needed. The gas barrier film 10 may also have a printed layer, as needed.

[0024] (Polyolefin-based base layer) The polyolefin-based substrate layer 21 is a substrate layer containing a polyolefin-based resin. Specific examples of polyolefin-based resins include polyethylene-based resins and polypropylene-based resins. Examples of polyethylene resins include low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-(meth)acrylic acid copolymer. Examples of polypropylene resins include homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymers, etc. Examples of α-olefins include ethylene, 1-butene, etc. Among these, polypropylene resins are preferred from the viewpoint of heat resistance. Among polypropylene-based resins, when emphasis is placed on the rigidity and heat resistance of the packaging container obtained using the packaging film 100, it is preferable to use a homopolymer. The polyolefin resin may be a biomass-derived polyolefin resin or a mechanically recycled or chemically recycled polyolefin resin.

[0025] The polyolefin-based substrate layer 21 may have a single-layer structure or a multi-layer structure. By providing the base material layer 20 with the polyolefin-based base material layer 21, the heat resistance and oil resistance of the packaging film 100 produced using the base material layer 20 can be improved.

[0026] The polyolefin-based base layer 21 may be a stretched film or a non-stretched film, but is preferably a stretched film from the viewpoint of gas barrier properties. Examples of stretched films include uniaxially stretched films and biaxially stretched films, but a biaxially stretched film is preferred because it improves the heat resistance of the packaging film 100.

[0027] The content of the polyolefin resin in the polyolefin substrate layer 21 is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0028] The polyolefin-based substrate layer 21 may contain additives as needed, such as crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0029] The thickness of the polyolefin-based substrate layer 21 is preferably 5 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more. By making the thickness of the polyolefin-based substrate layer 21 5 μm or more, the strength and heat resistance of the substrate layer 20 can be further improved. The thickness of the polyolefin-based base layer 21 is preferably 40 μm or less, more preferably 30 μm or less, and particularly preferably 20 μm or less. By making the thickness of the polyolefin-based base layer 21 40 μm or less, the processability of the base layer 20 can be further improved, and flexibility can be imparted to the packaging film 100.

[0030] The polyolefin-based substrate layer 21 may be subjected to a surface treatment, which can improve adhesion to the heat-resistant layer 22. The surface treatment method is not particularly limited, and examples thereof include corona discharge treatment, ozone treatment, low-temperature plasma treatment, glow discharge treatment, and oxidation treatment using chemicals.

[0031] (Heat-resistant layer) The heat-resistant layer 22 contains a high-melting-point resin having a melting point of 180° C. or higher. This makes it difficult for the adhesive resin composition to expand or contract, even when the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion and the heat of the adhesive resin composition is transferred to the base material layer 20 via the vapor deposition layer 40 and the base material layer 20 is then cooled. This makes it possible to suppress expansion and contraction of the polyolefin-based base material layer 21 and to prevent the fragile vapor deposition layer 40 from expanding or contracting. As a result, the packaging film 100 can have excellent gas barrier properties. The melting point can be measured using a differential scanning calorimeter (DSC). 1 , the heat-resistant layer 22 may be provided on the vapor deposition layer 40 side of the polyolefin-based substrate layer 21, or on the vapor deposition layer 40 side of the polyolefin-based substrate layer 21, but is preferably provided on the vapor deposition layer 40 side of the polyolefin-based substrate layer 21. In this case, the heat-resistant layer 22 is disposed between the vapor deposition layer 40 and the polyolefin-based substrate layer 21. Therefore, even if the polyolefin-based substrate layer 21 attempts to expand and contract after the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion to form the adhesive layer 60, the expansion and contraction of the heat-resistant layer 22 is sufficiently suppressed, and the expansion and contraction of the fragile vapor deposition layer 40 is further suppressed, allowing the packaging film 100 to have better gas barrier properties.

[0032] The melting point of the high-melting-point resin is more preferably 185°C or higher, even more preferably 190°C or higher, even more preferably 200°C or higher, and particularly preferably 205°C or higher. When the melting point of the high-melting point resin is 185°C or higher, even if the polyolefin-based base layer 21 attempts to expand and contract after the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion, the expansion and contraction of the heat-resistant layer 22 is more sufficiently suppressed, and the expansion and contraction of the fragile vapor deposition layer 40 is further suppressed, enabling the packaging film 100 to have even better gas barrier properties. Furthermore, according to the packaging film 100, since the heat-resistant layer 22 contains a high-melting point resin having a melting point of 185°C or higher, deterioration of the gas barrier properties can be suppressed even after moist heat treatment such as retort treatment or boiling treatment. From the viewpoint of film-forming properties of the heat-resistant layer 22, the melting point of the high-melting point resin is preferably 265°C or less, more preferably 260°C or less, even more preferably 250°C or less, even more preferably 240°C or less, and particularly preferably 230°C or less.

[0033] The high-melting-point resin may be any resin having a melting point of 180° C. or higher, and examples of the high-melting-point resin include vinyl resins, polyamide resins, polyimide resins, polyester resins, and cellulose resins. These may be used alone or in combination of two or more.

[0034] Among these, polyester resin or polyamide resin is preferable. These resins have polar groups, which can significantly improve the adhesion between the heat-resistant layer 22 and the vapor-deposited layer 40, and can effectively improve the gas barrier properties of the vapor-deposited layer 40.

[0035] Examples of vinyl resins include ethylene vinyl alcohol (EVOH), etc. The ethylene content (mol %) in EVOH is preferably low, for example, preferably 35 mol % or less, and more preferably 32 mol % or less.

[0036] Examples of polyester resins include polyethylene terephthalate resin (PET) and polyethylene naphthalate resin (PEN).

[0037] Examples of polyamide resins include nylon 6, nylon 6,6, MXD nylon, and amorphous nylon.

[0038] The high-melting-point resin is preferably a polyamide resin. Because the polyamide resin has a high melting point, even if the polyolefin-based substrate layer 21 attempts to expand and contract after the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion, the expansion and contraction of the heat-resistant layer 22 is more sufficiently suppressed, and the fragile vapor deposition layer 40 is further prevented from expanding and contracting, allowing the packaging film 100 to have even better gas barrier properties. Furthermore, even after the packaging film 100 is bent, the gas barrier properties of the packaging film 100 can be suppressed from decreasing, thereby improving the heat resistance of the packaging film 100. Furthermore, the gas barrier properties of the packaging film 100 can be suppressed from decreasing even after the packaging film 100 is subjected to moist heat treatment such as retort treatment or boiling treatment. As the high melting point resin, nylon 6 is more preferable.

[0039] The content of the high melting point resin in the heat-resistant layer 22 is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0040] The thickness of the heat-resistant layer 22 is preferably 1 μm or more, and more preferably 3 μm or more. When the thickness of the heat-resistant layer 22 is 1 μm or more, expansion or contraction of the polyolefin-based base layer 21 can be effectively suppressed when the base layer 20 is heated or cooled. The thickness of the heat-resistant layer 22 is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. By making the thickness of the heat-resistant layer 22 20 μm or less, the proportion of polyolefin resin in the entire packaging film 100 can be increased, and the recyclability of the packaging film 100 can be improved.

[0041] In the above packaging film 100, the ratio of the thickness of the heat-resistant layer 22 to the thickness of the gas barrier film 10 is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, and particularly preferably 25% or less. When the ratio of the thickness of the heat-resistant layer 22 to the thickness of the gas barrier film 10 is 50% or less, the ratio of polyolefin-based resin in the entire packaging film 100 can be increased, thereby improving the recyclability of the packaging film 100. In the packaging film 100, the thickness of the heat-resistant layer 22 may account for 2.5% or more, 3.0% or more, 5.0% or more, or 10% or more of the thickness of the gas barrier film 10. When the thickness of the heat-resistant layer 22 accounts for 5.0% or more of the thickness of the gas barrier film 10, expansion or contraction of the polyolefin-based base layer 21 can be effectively suppressed when the base layer 20 is heated or cooled.

[0042] (Base adhesive layer) The substrate adhesive layer contains a polyolefin adhesive resin. The polyolefin adhesive resin refers to an adhesive resin containing a polyolefin resin. Examples of polyolefin adhesive resins include acid-modified polypropylene resins and acid-modified polyethylene resins.

[0043] An example of the acid-modified polypropylene resin is a maleic acid-modified polypropylene resin. The maleic acid modified polypropylene resin is a resin obtained by modifying a polypropylene resin with maleic acid.

[0044] Examples of polypropylene resins include homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymers, etc. Examples of α-olefins include ethylene, 1-butene, etc.

[0045] The acid-modified polyethylene resin may be, for example, a maleic acid-modified polyethylene resin. Maleic acid modified polyethylene resin is a resin obtained by modifying a polyethylene resin with maleic acid. Examples of polyethylene resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene copolymerized with ethylene and α-olefins, such as ethylene, 1-butene, and 1-hexane.

[0046] The thickness of the substrate adhesive layer is not particularly limited, but is preferably 1 μm or more. The thickness of the substrate adhesive layer may be 3 μm or more, or 5 μm or more. When the thickness of the substrate adhesive layer is 1 μm or more, the adhesion between the polyolefin substrate layer 21 and the heat-resistant layer 22 is effectively improved. The thickness of the substrate adhesive layer may be 10 μm or less, 8 μm or less, 6 μm or less, or 5 μm or less.

[0047] (base material layer) The substrate layer 20 can be obtained by coextrusion or the like.

[0048] The thickness of the base layer 20 is not particularly limited, but is preferably 10 μm or more, and more preferably 20 μm or more. When the thickness of the base layer 20 is 10 μm or more, the adhesion between the gas barrier film 10 and the sealant layer 70 is effectively improved. The thickness of the substrate layer 20 may be 50 μm or less, 40 μm or less, or 30 μm or less.

[0049] (Anchor coat layer) The anchor coat layer 30 is a layer for further improving the adhesion between the base material layer 20 and the vapor deposition layer 40, and is provided between the base material layer 20 and the vapor deposition layer 40.

[0050] The material constituting the anchor coat layer 30 is not particularly limited as long as it can improve the adhesion between the base layer 20 and the vapor deposition layer 40, but it is preferable that it contains a polyurethane resin. In this case, even if the polyolefin-based base layer 21 attempts to expand and contract after the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion, not only is the expansion and contraction of the heat-resistant layer 22 sufficiently suppressed, but the anchor coat layer 30 containing polyurethane resin also tends to alleviate the expansion stress and contraction stress transmitted from the base layer 20 to the vapor deposition layer 40, thereby suppressing the expansion and contraction of the vapor deposition layer 40, which is prone to cracking, and enabling the packaging film 100 to have excellent gas barrier properties. Such polyurethane resins are composed of, for example, a reaction product of an organosilane or organometallic compound, a polyol compound, and an isocyanate compound. The organosilane is, for example, a trifunctional organosilane or a hydrolyzate of a trifunctional organosilane. The organometallic compound is, for example, a metal alkoxide or a hydrolyzate of a metal alkoxide. The metal element contained in the organometallic compound is, for example, Al, Ti, Zr, etc. The organosilane hydrolyzate and the metal alkoxide hydrolyzate each only need to have at least one hydroxyl group. From the viewpoint of transparency, the polyol compound is preferably an acrylic polyol. The isocyanate compound mainly functions as a crosslinking agent or a curing agent. The polyol compound and the isocyanate compound may be a monomer or a polymer.

[0051] The thickness of the anchor coat layer 30 is 0.02 μm or more. When the thickness of the anchor coat layer 30 is 0.02 μm or more, even if the polyolefin-based base layer 21 expands and contracts after the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion, the anchor coat layer 30 containing a polyurethane resin effectively alleviates the expansion stress and contraction stress transmitted from the base layer 20 to the vapor deposition layer 40, thereby further suppressing expansion and contraction of the fragile vapor deposition layer 40, and allowing the packaging film 100 to have better gas barrier properties. The thickness of the anchor coat layer 30 is preferably 0.05 μm or more. The thickness of the anchor coat layer 30 may be 0.1 μm or more, 0.2 μm or more, 0.4 μm or more, 0.5 μm or more, 0.7 μm or more, or 1.0 μm or more. When the thickness of the anchor coat layer 30 is 0.2 μm or more, the expansion and contraction of the easily cracked vapor deposition layer 40 is further suppressed compared to when the thickness of the anchor coat layer 30 is less than 0.2 μm, and the packaging film 100 can have better gas barrier properties. The thickness of the anchor coat layer 30 is preferably 5 μm or less from the viewpoint of suppressing a decrease in the proportion of polyolefin resin in the entire packaging film 100. In this case, the decrease in gas barrier properties can be further suppressed even after moist heat treatment such as retort treatment or boiling treatment, compared to when the thickness of the anchor coat layer 30 exceeds 5 μm. From the viewpoint of preventing a decrease in the proportion of polyolefin resin in the entire packaging film 100, the thickness of the anchor coat layer 30 is preferably less than 2.5 μm. From the viewpoint of preventing a decrease in the proportion of polyolefin resin in the entire packaging film 100, the thickness of the anchor coat layer 30 is more preferably 2.0 μm or less. The thickness of the anchor coat layer 30 is more preferably 1.5 μm or less or 1.0 μm or less from the viewpoint of suppressing a decrease in the proportion of polyolefin-based resin in the entire packaging film 100. The thickness of the anchor coat layer 30 may be 0.8 μm or less or 0.5 μm or less from the viewpoint of suppressing a decrease in the proportion of polyolefin-based resin in the entire packaging film 100. The thickness of the anchor coat layer 30 is preferably 0.5 μm or more but less than 2.5 μm, 0.5 μm or more but 2.0 μm or less, or 0.7 μm or more but 1.5 μm or less, in order to further suppress deterioration of gas barrier properties even after moist heat treatment such as retort treatment or boiling treatment.

[0052] (deposited layer) The vapor-deposited layer 40 is a layer formed by vapor deposition and is made of an inorganic material, such as a metal or a metal oxide.

[0053] The metal constituting the metal or metal oxide may be at least one metal selected from the group consisting of Si, Al, Mg, Sn, Ti, and In. Silicon oxide (SiOx), aluminum oxide (AlOx), or a mixture thereof is preferred as the metal oxide. Both SiOx and AlOx have excellent water vapor barrier properties, and can improve the water vapor barrier properties of the packaging film 100. Of these, SiOx is preferred as the metal oxide. In this case, the packaging film 100 can have even better water vapor barrier properties. The deposition layer 40 may be composed of a single layer or multiple layers.

[0054] The thickness of the vapor-deposited layer 40 is not particularly limited, but is preferably 5 nm or more. In this case, deterioration of the gas barrier properties of the packaging film 100 can be more sufficiently suppressed even after moist heat treatment such as retort treatment or boiling treatment, compared to when the thickness of the vapor-deposited layer 40 is less than 5 nm. The thickness of the vapor-deposited layer 40 is more preferably 8 nm or more, even more preferably 10 nm or more, and particularly preferably 12 nm or more.

[0055] Furthermore, the thickness of the vapor-deposited layer 40 is preferably 300 nm or less. In this case, deterioration of the gas barrier property of the packaging film 100 can be more effectively suppressed even after the packaging film 100 is subjected to moist heat treatment such as retort treatment or boiling treatment, compared to when the thickness of the vapor-deposited layer 40 exceeds 300 nm. Furthermore, the proportion of polyolefin resin in the entire packaging film 100 can be increased, and the recyclability of the packaging film 100 can also be improved. The thickness of the vapor-deposited layer 40 is more preferably 200 nm or less, even more preferably 100 nm or less, and particularly preferably 50 nm or less.

[0056] (covering layer) The coating layer 50 is a layer that coats the vapor-deposited layer 40. When the gas barrier film 10 has the coating layer 50, after the adhesive resin composition is bonded to the gas barrier film 10 by melt extrusion, when the adhesive resin composition expands and contracts, the expansion stress and contraction stress are not transmitted directly to the vapor-deposited layer 40 but are transmitted indirectly via the coating layer 50, thereby suppressing the expansion and contraction of the vapor-deposited layer 40.

[0057] The hardness of the cross section of the coating layer 50 measured by nanoindentation is not particularly limited, but is preferably 1.15 GPa or less. In this case, when the adhesive resin composition expands and contracts after being bonded to the gas barrier film 10 by melt extrusion, the expansion stress and contraction stress are effectively alleviated by the coating layer 50, and the expansion and contraction of the fragile vapor deposition layer 40 is further suppressed. The cross-sectional hardness of the coating layer 50 is more preferably 1.10 GPa or less, 1.0 GPa or less, 0.9 GPa or less, 0.8 GPa or less, or 0.7 GPa or less. In particular, when the hardness of the coating layer 50 is 0.8 GPa or less, deterioration of the gas barrier property due to retort treatment can be more effectively suppressed than when the hardness of the coating layer 50 is greater than 0.8 GPa.

[0058] The hardness of the cross section of the coating layer 50 may be 0.15 GPa or more, 0.20 GPa or more, 0.30 GPa or more, 0.40 GPa or more, 0.50 GPa or more, 0.60 GPa or more, or 0.70 GPa or more. A coating layer having a hardness of 0.15 GPa or more has the advantages of providing higher gas barrier properties and excellent protective function for the vapor deposition layer during the production of packaging containers, compared to a case where the hardness is less than 0.15 GPa.

[0059] The hardness of the cross section of the coating layer 50 is measured by nanoindentation, which is a measurement method in which a quasi-static indentation test is performed on a target measurement object to obtain the mechanical properties of the sample. A measurement sample is prepared and the hardness of the cross section of the coating layer 50 is measured for this measurement sample. The measurement sample (cross section sample) is prepared as follows. That is, after corona treatment is performed on both sides of the packaging film 100, it is embedded in a visible light curable resin (Aronix LCR D-800, manufactured by Toagosei Co., Ltd.). Then, using an ultramicrotome Leica EM UC7 and a diamond knife Microstar LH, the packaging film 100 is cut perpendicular to the lamination direction. The resulting cross section is subjected to a finishing process under conditions of a cutting thickness Feed of 100 nm and a cutting speed Speed ​​of 1 mm / s to obtain a measurement sample. For the measurement, a Hysitron TI-Premier (trade name) manufactured by Bruker Japan Co., Ltd. is used as the measuring device, and a Berkovich type diamond indenter manufactured by Bruker Japan Co., Ltd. is used as the indenter. The measurement conditions are as follows. ·Temperature: Normal temperature (25℃) Mode: Load control mode · Indentation and unloading: Indent the specimen up to a load of 15μN at a pressing speed of 1.5μN / sec, then hold the specimen at the maximum load for 5 seconds, and then unload at a speed of 1.5μN / sec. Measurement points: A topographic image of the sample surface is obtained using the shape measurement function of the measuring device, which scans the sample surface with an indenter, and 20 points are specified on the sample surface at intervals of 1 μm or more from the topographic image. When calculating hardness, the relationship between the contact depth and the contact projected area between the indenter and the sample is calibrated in advance using fused quartz as a standard sample.Then, the unloading curve in the 60-95% range of the maximum load at the time of unloading is analyzed using the Oliver-Pharr method to calculate the hardness.

[0060] The coating layer 50 may be a gas barrier coating layer. In this case, the gas barrier properties of the packaging film 100 are improved. Furthermore, even if damage such as cracks occurs in the vapor deposition layer 40, the gas barrier properties of the packaging film 100 can be prevented from decreasing.

[0061] The gas barrier coating layer is formed, for example, from a cured product of a composition containing a water-soluble polymer and at least one of a metal alkoxide and its hydrolysate, and the composition may further contain at least one of a silane coupling agent and its hydrolysate.

[0062] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. Among these, polyvinyl alcohol (hereinafter also referred to as "PVA") is particularly preferred because it can easily improve the oxygen barrier properties of the gas barrier film.

[0063] 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 (1), R 11 is a monovalent organic group having 1 to 8 carbon atoms, and is an alkyl group such as a methyl group or an ethyl group (OR 11 R may be a hydrolyzable group. 12 is a monovalent organic group having 1 to 8 carbon atoms, and may be 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.

[0064] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], etc. Tetraethoxysilane (hereinafter also referred to as "TEOS") and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

[0065] Examples of the silane coupling agent include compounds represented by the following general formula (2). (R 2 Si(OR 3 )3) n ······(2) In the above general formula (2), R 2 represents a monovalent organic group, and R 3 represents an alkyl group or -C2H4OCH3. In this case, it is possible to improve the adhesion between the gas barrier coating layer and the vapor deposition layer 40, and delamination between layers in the packaging film 100 can be suppressed. In addition, R 2 and R 3 may be the same or different. 3 They may be the same or different from each other. R 2 Examples of the monovalent organic group represented by the formula (I) include a monovalent organic functional group containing a vinyl group, an epoxy group, a mercapto group, an amino group, or an isocyanate group. Among these, an isocyanate group is preferred as the monovalent organic functional group. In this case, the composition can have better hot water resistance upon curing, and can impart greater lamination strength to the packaging film 100 even after moist heat treatment such as retort treatment or boiling treatment. R 3 Examples of the alkyl group represented by the formula include a methyl group and an ethyl group. Among these, a methyl group is preferred. In this case, hydrolysis is rapid. n represents an integer of 1 or greater. When n is 1, the silane coupling agent represents a monomer, whereas when n is 2 or greater, the silane coupling agent represents a polymer. n is preferably 3. In this case, the hot water resistance of the gas barrier coating layer can be further improved, and it becomes possible to impart greater laminate strength to the gas barrier coating layer even after moist heat treatment such as retort treatment or boiling treatment.

[0066] Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and 1,3,5-tris(3-methoxysilylpropyl)isocyanurate.

[0067] When the composition contains PVA as the water-soluble polymer, the amount of PVA in the composition may be 15% by mass or more, 20% by mass or more, or 25% by mass or more based on the total solid content of the composition, from the viewpoint of maintaining the flexibility of the gas barrier coating layer and facilitating the formation of the gas barrier coating layer. When the composition contains PVA as the water-soluble polymer, the amount of PVA in the composition may be 70% by mass or less, 60% by mass or less, or 50% by mass or less based on the total solid content of the composition, from the viewpoint of easily maintaining low oxygen permeability even after heat sterilization treatment.

[0068] When the composition contains TEOS as the metal alkoxide, the amount of TEOS in the composition may be 30% by mass or more, 35% by mass or more, or 40% by mass or more based on the total solid content of the composition, from the viewpoint of easily maintaining low oxygen permeability even after heat sterilization. When the composition contains TEOS as the metal alkoxide, the amount of TEOS in the composition may be 80% by mass or less, 75% by mass or less, or 70% by mass or less based on the total solid content of the composition, from the viewpoint of maintaining the flexibility of the gas barrier coating layer and making it easier to form the gas barrier coating layer. In this specification, the amount of TEOS means a value calculated as SiO2.

[0069] When the composition contains isocyanurate silane as a silane coupling agent, the amount of isocyanurate silane in the composition may be 1% by mass or more, 3% by mass or more, or 5% by mass or more based on the total solid content of the composition, from the viewpoints of easily realizing hot water resistance and easily realizing excellent adhesion even after heat sterilization treatment. When the composition contains isocyanurate silane as a silane coupling agent, the amount of isocyanurate silane in the composition may be 20% by mass or less, 15% by mass or less, or 10% by mass or less based on the total solid content of the composition, from the viewpoints of easily maintaining low oxygen permeability even after heat sterilization treatment without reducing the amounts of other components in the composition too much.

[0070] The gas barrier coating layer can be formed by coating the vapor deposition layer 40 with a composition for forming a gas barrier coating layer and then heating and drying it. The composition for forming a gas barrier coating layer can be prepared by dissolving a water-soluble polymer in an aqueous solvent (such as water or a mixed solvent of water and alcohol) and mixing it with at least one of a metal alkoxide and a silane coupling agent, or a pre-hydrolyzed version of either. This composition (mixed solution) can also contain known additives such as an isocyanate compound, a dispersant, a stabilizer, a viscosity modifier, and a colorant.

[0071] The drying temperature when forming the gas barrier coating layer may be, for example, 40°C or higher, 60°C or higher, or 90°C or higher, or 140°C or lower, 130°C or lower, or 120°C or lower.

[0072] The thickness of the gas barrier coating layer may be 80 nm or more, 90 nm or more, 100 nm or more, 150 nm, 200 nm, or 300 nm or more. If the thickness of the gas barrier coating layer is 80 nm or more, it is easy to maintain low oxygen permeability even after heat sterilization treatment. The thickness of the gas barrier coating layer may be 1000 nm or less, 700 nm or less, 500 nm or less, or 400 nm or less. If the thickness of the gas barrier coating layer is 1000 nm or less, it is possible to prevent deterioration of gas barrier properties due to cracking in the gas barrier coating layer during coating. From the viewpoint of easily maintaining low oxygen permeability even after heat sterilization treatment and preventing deterioration of gas barrier properties due to cracking in the gas barrier coating layer during coating, the thickness of the gas barrier coating layer may be 80 to 1000 nm.

[0073] (Printing layer) As described above, the gas barrier film 10 may further include a printed layer, if necessary. The printed layer can be provided on at least one of the base layer 20 and the cover layer 50. The printed layer is a layer formed using ink made by adding various pigments, plasticizers, drying agents, stabilizers, etc. to a binder resin such as a urethane, acrylic, nitrocellulose, or rubber-based resin. This printed layer can display letters, patterns, symbols, and combinations thereof.

[0074] The ink may be either a water-based ink or an oil-based ink, but is preferably a water-based ink. A water-based ink uses water or alcohol as a solvent, which can further reduce the environmental impact. The ink may be a biomass ink or not, but from the perspective of reducing the environmental impact, a biomass ink is preferred. Here, biomass ink refers to an ink containing components obtained from biological resources (biomass), such as cotton, pulp, rice bran, vegetable oil, and angiosperm seeds. Examples of methods for forming the printed layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing.

[0075] (2) Adhesive layer The adhesive layer 60 is a layer obtained by laminating, by melt extrusion, an adhesive resin composition containing a polyolefin-based adhesive resin to the gas barrier film 10. The polyolefin-based adhesive resin refers to an adhesive resin containing a polyolefin resin. Examples of polyolefin adhesive resins include acid-modified polypropylene resins and acid-modified polyethylene resins.

[0076] An example of the acid-modified polypropylene resin is a maleic anhydride graft-modified polypropylene resin. The maleic anhydride graft-modified polypropylene resin is a resin obtained by graft-modifying a polypropylene resin with maleic anhydride. The graft ratio of maleic anhydride is preferably 0.1 to 1% by mass. When the graft ratio of maleic anhydride is 0.1% by mass or more, the adhesiveness of the adhesive layer 60 is further improved. When the graft ratio of maleic anhydride is 1% by mass or less, moisture adsorption becomes difficult, and foaming is less likely to occur. In addition, the processability of the adhesive resin composition is improved.

[0077] Examples of polypropylene resins include homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymers, etc. Examples of α-olefins include ethylene, 1-butene, etc.

[0078] An example of the acid-modified polyethylene resin is a maleic anhydride graft-modified polyethylene resin. The maleic anhydride graft-modified polyethylene resin is a resin obtained by graft-modifying a polyethylene resin with maleic anhydride. The graft ratio of maleic anhydride is preferably 0.1 to 1% by mass. When the graft ratio of maleic anhydride is 0.1% by mass or more, the adhesiveness of the adhesive layer 60 is further improved. When the graft ratio of maleic anhydride is 1% by mass or less, moisture adsorption becomes difficult, and foaming is less likely to occur. In addition, the processability of the adhesive resin composition is improved. Examples of polyethylene resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene copolymerized with ethylene and α-olefins, such as ethylene, 1-butene, and 1-hexane.

[0079] The adhesive layer 60 is obtained by laminating an adhesive resin composition to the gas barrier film 10 by melt extrusion. After the adhesive resin composition has been brought into contact with the coating layer 50 of the gas barrier film 10, it is cooled by a cooling roll.

[0080] The thickness of the adhesive layer 60 is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. When the thickness of the adhesive layer 60 is 1 μm or more, the adhesion between the gas barrier film 10 and the sealant layer 70 is effectively improved. The thickness of adhesive layer 60 may be 40 μm or less, 30 μm or less, 20 μm or less, or 15 μm or less.

[0081] The adhesive layer 60 is preferably obtained by heat-treating an adhesive resin composition. In this case, the adhesive strength of the adhesive layer 60 can be improved, and the heat sealability, impact resistance, and resistance to moist heat treatments such as retort treatment, boiling treatment, and humidity conditioning treatment of the packaging film 100 can be improved. The heat treatment can be carried out by forming a layer made of the adhesive resin composition and applying heat to this layer through a heater roll or oven. This heat treatment can be carried out, for example, in a state where the gas barrier film 10 and the sealant layer 70 are bonded together via the adhesive resin composition.

[0082] (3) Sealant layer The sealant layer 70 includes a polyolefin resin. Examples of polyolefin resins include polyethylene resins and polypropylene resins. Examples of polyethylene resins include low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-(meth)acrylic acid copolymer. Examples of polypropylene resins include homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymers. Examples of α-olefins include ethylene and 1-butene. Among these, polypropylene resins are preferred from the viewpoint of heat resistance. Furthermore, among polypropylene-based resins, when emphasis is placed on the rigidity and heat resistance of the packaging container obtained using the packaging film 100, it is preferable to use homopolypropylene. The polyolefin resin may be a biomass-derived polyolefin resin or a mechanically recycled or chemically recycled polyolefin resin. The sealant layer 70 may have a single layer structure or a multi-layer structure.

[0083] The sealant layer 70 may contain additives as needed, such as crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0084] When the polyolefin resin contained in the polyolefin base layer 21 of the base layer 20 and the polyolefin adhesive resin contained in the adhesive layer 60 are polypropylene resins, the polyolefin resin contained in the sealant layer 70 is preferably a polypropylene resin. In this case, the proportion of a single material (polypropylene resin) contained in the packaging film 100 can be further increased, and the recyclability of the packaging film 100 is further improved. Alternatively, when the polyolefin resin contained in the polyolefin base layer 21 of the base layer 20 and the polyolefin adhesive resin contained in the adhesive layer 60 are polyethylene resins, the polyolefin resin contained in the sealant layer 70 is preferably polyethylene resin. In this case, the proportion of a single material (polyethylene resin) contained in the packaging film 100 can be further increased, and the recyclability of the packaging film 100 is further improved.

[0085] The polyolefin resin contained in the sealant layer 70 may be a stretched film or a non-stretched film, but a non-stretched film (e.g., CPP) is preferred. In this case, the melting point of the sealant layer 70 can be lowered, making it easier to prevent the base material layer 20 from melting when the packaging film 100 is heat-sealed.

[0086] The thickness of the sealant layer 70 is not particularly limited, but from the viewpoint of improving the heat sealability, it is preferably 40 μm or more, and more preferably 50 μm or more. From the viewpoint of improving the flexibility of the packaging film 100, the thickness of the sealant layer 70 is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and particularly preferably 60 μm or less.

[0087] The sealant layer 70 can be formed by being attached to the adhesive layer 60 by melt extrusion. In this case, the sealant layer 70 may be formed by melt extruding a sealant layer-forming resin composition that forms the sealant layer 70 and attaching it to the adhesive layer 60, or by co-extruding an adhesive resin composition and a sealant layer-forming resin composition that forms the sealant layer 70 and attaching the adhesive resin composition to the adhesive layer 60 with the adhesive resin composition facing the adhesive layer 60. Alternatively, the sealant layer 70 may be formed simultaneously with the adhesive layer 60 by co-extruding the adhesive resin composition that forms the adhesive layer 60 and the sealant layer-forming resin composition that forms the sealant layer 70.

[0088] <Packaging products> Next, an embodiment of the packaging product of the present disclosure will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view showing one embodiment of the packaging product of the present disclosure. In Fig. 2, the same components as those in Fig. 1 are designated by the same reference numerals, and redundant description will be omitted. As shown in Fig. 2, a packaged product 300 includes a packaging bag 200 as a packaging container and a content C accommodated in the packaging bag 200. The packaging bag 200 shown in Fig. 2 is obtained by using a pair of packaging films 100 and heat-sealing the peripheral edges of the packaging films 100 with the sealant layers 70 facing each other.

[0089] This packaging product 300 includes a packaging bag 200, which makes it possible to provide excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin resin in the entire packaging bag 200. Therefore, the packaging product 300 can be easily recycled after opening, and can also suppress deterioration in the quality of the contents C.

[0090] The packaging bag 200 can also be obtained by folding one packaging film 100 and heat-sealing the peripheral edge of the packaging film 100 with the sealant layers 70 facing each other.

[0091] Examples of the packaging bag 200 include a three-sided pouch, a four-sided pouch, a standing pouch, a gusset pouch, a pillow packaging bag, etc. The packaging bag 200 may further have a spout or a zipper depending on the application.

[0092] The contents C are not particularly limited, and examples of the contents C include food, liquid, medicine, and electronic parts. In the above embodiment, the packaging container is configured as a packaging bag, but the packaging container of the present disclosure may be configured as a paper container for liquids or a laminated tube instead of a packaging bag. When the packaging container is configured as a paper container for liquids, the paper container for liquids is obtained using a packaging film, and the packaging film further includes a paper substrate. The paper substrate may be arranged on the opposite side of the gas barrier film from the sealant layer. The laminated tube further includes a cylindrical laminated tube body, an outlet for discharging the contents of the laminated tube, and a shoulder connecting the body and the outlet. The laminated tube body is obtained using a packaging film, and the packaging film further includes a second sealant layer arranged on the opposite side of the gas barrier film from the sealant layer.

[0093] <Summary of this disclosure> The outline of the present disclosure is as follows. [1] A packaging film comprising a gas barrier film, an adhesive layer, and a sealant layer in this order, the gas barrier film having a base layer, an anchor coat layer, and a vapor deposition layer in this order, the base layer having a polyolefin base layer containing a polyolefin resin, the anchor coat layer containing a polyurethane resin, the anchor coat layer having a thickness of 0.02 μm or more, the adhesive layer being obtained by laminating an adhesive resin composition containing a polyolefin adhesive resin to the gas barrier film by melt extrusion, and the sealant layer containing a polyolefin resin. [2] The packaging film according to [1], wherein the anchor coat layer has a thickness of 0.2 μm or more. [3] The packaging film according to [1] or [2], wherein the anchor coat layer has a thickness of less than 2.5 μm. [4] The packaging film according to [3], wherein the anchor coat layer has a thickness of 2.0 μm or less. [5] The packaging film according to any one of [1] to [4], wherein the polyolefin-based substrate layer is a stretched film. [6] The packaging film according to any one of [1] to [5], wherein the gas barrier film further comprises a coating layer between the vapor deposition layer and the adhesive layer that covers the vapor deposition layer. [7] A packaging container comprising the packaging film according to any one of [1] to [6]. [8] A packaging product comprising the packaging container described in [7] and contents contained in the packaging container. [Example]

[0094] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0095] <Preparation of coating solution> A coating liquid serving as a gas barrier coating layer-forming composition used in the examples and comparative examples was prepared as follows.

[0096] (coating liquid) The following solutions A to C were mixed to obtain a coating solution. The coating solution contains TEOS (SiO2 equivalent value), PVA, and isocyanurate silane (R) as a silane coupling agent (hereinafter also referred to as "SC agent"), assuming a solid content of 100. 2 The mass ratio of the SiO2 to Si(OH)3 (equivalent value) was adjusted to 47.6 / 47.6 / 4.8. Solution A: TEOS (product name: KBE04, solid content: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.), methanol (manufactured by Kanto Chemical Co., Ltd.), and 0.1 N hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) were mixed in a mass ratio of 17:10:73, and the resulting mixture was stirred for 30 minutes to hydrolyze TEOS (5% by mass (in terms of SiO2) hydrolyzed solution). Solution B: a 5% by mass aqueous solution of PVA (trade name: Kuraray Poval 60-98, manufactured by Kuraray Co., Ltd.). Solution C: 1,3,5-tris(3-methoxysilylpropyl) isocyanurate (product name: X-12-965P, manufactured by Shin-Etsu Chemical Co., Ltd.) as an SC agent was dissolved in a water / IPA mixed solution of 1 / 1 (mass ratio) so that the solid content ratio was 5 mass% (R 2The solution is diluted to obtain Si(OH)3 equivalent.

[0097] <Preparation of anchor coat layer forming composition> The anchor coat layer forming composition was prepared as follows. Acrylic polyol and tolylene diisocyanate were mixed so that the number of NCO groups in tolylene diisocyanate was equal to the number of OH groups in the acrylic polyol, and the mixture was diluted with ethyl acetate to a solids content (total amount of acrylic polyol and tolylene diisocyanate) of 5% by mass. β-(3,4-epoxycyclohexyl)trimethoxysilane was further added to the diluted mixture in an amount of 5 parts by mass per 100 parts by mass of the total amount of acrylic polyol and tolylene diisocyanate, and these were mixed to prepare a composition for forming an anchor coat layer (anchor coating agent).

[0098] <Production of packaging film> Example 1 First, homopolypropylene (hereinafter also referred to as "PP") was used as the polyolefin-based base layer (PO-based base layer). Melting point: 162°C, density: 0.9 g / cm 3 , MFR (230°C, load 2.16 kg): 3.0 g / 10 min), and a maleic acid-modified polypropylene (hereinafter also referred to as "PP1") as a substrate adhesive layer. Melting point: 165°C, density: 0.89 g / cm 3 , MFR (230°C, load 2.16 kg): 6.5 g / 10 min), and nylon 6 (hereinafter also referred to as "Ny") as a heat-resistant layer. Melting point: 225°C, density: 1.1 g / cm 3 , MVR (at 275℃, load 5.0kg): 70cm 3 The substrates were formed by co-extrusion using a co-extrusion film molding machine and biaxially stretching the layers (10 μm, 5 μm, and 5 μm thick, respectively) at a flow rate of 10 μm / 10 min, as shown in Table 1. The temperature at the junction of the layers was set to 260°C. Next, the composition for forming an anchor coat layer prepared as described above was applied by gravure coating onto the heat-resistant layer of this base layer to form a coating film having the thickness shown in Table 1 after drying. The coating film was then heated at 120°C for 10 seconds and dried to form an anchor coat layer containing a polyurethane resin (PU) and having the thickness shown in Table 1. Next, a 0.03 μm thick SiO 2 film was formed on the surface of the base layer using an electron beam heating vacuum deposition device. x The film was formed as a vapor-deposited layer. Next, the coating liquid was applied onto the vapor deposition layer to form a coating film, which was then dried by heating at 80°C for 60 seconds to form a gas barrier coating layer having a thickness of 0.32 µm. Next, a white ink was solid printed on the gas barrier coating layer to a thickness of 1 μm by gravure printing to form a printed layer, thereby obtaining a gas barrier film. Next, a maleic anhydride-modified PP (hereinafter also referred to as "PP2") was applied as an adhesive layer onto the printed layer of the gas barrier film. Melting point: 106°C, density: 0.89 g / cm 3 , MFR (230°C, load 2.16 kg): 12 g / 10 min) was laminated by melt extrusion at a molding temperature of 250°C to the thickness shown in Table 1, and then a CPP film (product name "Torayfan ZK207", manufactured by Toray Advanced Film Co., Ltd., thickness: 40 μm) was laminated on top of the adhesive layer using a T-die casting method to form a sealant layer, thereby obtaining a laminate. Thereafter, the laminate was subjected to heat and pressure bonding using a roll heated to 140° C. for 40 seconds. In this way, a packaging film was obtained.

[0099] (Examples 2 to 3 and Comparative Example 1) A packaging film was obtained in the same manner as in Example 1, except that the anchor coat layer was formed to have the thickness shown in Table 1 or Table 2.

[0100] (Comparative Example 2) A packaging film was obtained in the same manner as in Example 1, except that the substrate layer was formed by performing a corona treatment as a surface treatment on the surface of the substrate, and no anchor coat layer was formed.

[0101] (Examples 4 to 6 and Comparative Example 3) When forming the base layer, polyethylene (melting point: 127°C, density: 0.938 g / cm) was used as the PO-based base layer. 3 , MFR (190°C, load 2.16 kg): 3.8 g / 10 min) was used, and polyethylene (melting point: 120°C, density: 0.91 g / cm) was used as the substrate adhesive layer. 3 A gas barrier film was produced in the same manner as in Example 1, except that an adhesive resin (hereinafter also referred to as "PE1") consisting of 1.2 g / 10 min, MFR (190°C, load 2.16 kg): 2.2 g / 10 min) was used. Next, a modified polyethylene film (melting point: 120°C, density: 0.91 g / cm) was applied as an adhesive layer onto the printed layer of the gas barrier film. 3 An adhesive resin (hereinafter also referred to as "PE2") consisting of a styrene-butadiene rubber (styrene-butadiene rubber) and a MFR (190°C, load 2.16 kg): 2.2 g / 10 min was melt-extruded at a molding temperature of 260°C to form a laminate having the thickness shown in Table 3 or Table 4. Subsequently, an LLDPE film (product name "SE625N", manufactured by Tamapoly Co., Ltd., thickness: 40 μm) was laminated on the adhesive layer as a sealant layer to obtain a laminate. Thereafter, the laminate was subjected to heat and pressure bonding using a roll heated to 140° C. for 40 seconds. In this way, a packaging film was obtained.

[0102] Comparative Example 4 A packaging film was obtained in the same manner as in Example 4, except that the substrate layer was formed by performing a corona treatment as a surface treatment on the surface of the substrate, and no anchor coat layer was formed.

[0103] Example 7 A packaging film was obtained in the same manner as in Example 1, except that the heat-resistant layer was not formed when the base layer was formed.

[0104] (Examples 8 to 11) A packaging film was obtained in the same manner as in Example 1, except that the anchor coat layer was formed to have the thickness shown in Table 5 or Table 6.

[0105] <Hardness of the coating layer cross section> The hardness of the cross section of the coating layer of the packaging film obtained in the Examples or Comparative Examples was measured by the nanoindentation method as follows. Measurement samples (cross-section samples) were prepared as follows. After corona treatment on both sides of the packaging film, it was embedded in a visible light-curable resin (Aronix LCR D-800, manufactured by Toagosei Co., Ltd.). The packaging film was then cut perpendicular to the lamination direction using a Leica EM UC7 ultramicrotome and a diamond knife Microstar LH. The resulting cross section was then finished at a cutting thickness of 200 nm and a cutting speed of 1 mm / s to prepare the measurement sample. For the measurement, a Hysitron TI-Premier (trade name) manufactured by Bruker Japan Co., Ltd. was used as the measuring device, and a Berkovich type diamond indenter manufactured by Bruker Japan Co., Ltd. was used as the indenter. The measurement conditions were as follows. ·Temperature: Normal temperature (25℃) Mode: Load control mode Indentation and unloading: Indentation was performed at a rate of 1.5 μN / sec up to a load of 15 μN, then the maximum load was maintained for 5 seconds, and the load was then removed at a rate of 1.5 μN / sec. Measurement points: Using the shape measurement function of the measuring device that scans the sample surface with an indenter, a shape image of the coating layer cross section is acquired, and 20 points are specified on the coating layer cross section at intervals of 1 μm or more from the shape image. When calculating the hardness, the relationship between the contact depth and the projected contact area between the indenter and the sample was calibrated in advance using fused quartz as a standard sample. The unloading curve for the 60-95% range relative to the maximum load at the time of unloading was then analyzed using the Oliver-Pharr method, and the hardness of the cross section of the coating layer was calculated. The results are shown in Tables 1 to 6.

[0106] <Evaluation of packaging film> (1) Gas barrier properties (Before retort or boiling) First, test pieces of 100 mm x 100 mm were cut out from the packaging films of Examples 1 to 11 and Comparative Examples 1 to 4, and the oxygen permeability (unit: cc / m) of these test pieces was measured using an oxygen permeability measuring device (product name "OX-TRAN2 / 20", manufactured by MOCON) under conditions of a temperature of 30°C and a relative humidity of 70%. 2 The measurements were carried out in accordance with JIS K-7126-2. The results are shown in Tables 1 to 6.

[0107] (After retort processing) The packaging films of Examples 1 to 3, Examples 7 to 11, and Comparative Examples 1 and 2 were cut into 297 mm x 210 mm pieces, and three-sided pouches with openings were fabricated using the cut packaging films. The three-sided pouches were formed by folding the cut packaging films so that the sealant layers faced each other and heat-sealing the peripheral edges of the sealant layers. Tap water (city water) was then poured into the opening to seal the opening of the three-sided pouch, thereby preparing a sealed pouch. Then, the sealed pouch was subjected to a retort treatment at 130°C for 30 minutes in a hot water storage type retort apparatus. After that, a 100mm x 100mm test piece was cut from the sealed body after retort treatment, and the oxygen permeability (unit: cc / m) of this test piece was measured in the same manner as before retort treatment. 2 The results are shown in Tables 1, 2, 5 and 6.

[0108] (After boiling) The packaging films of Examples 4 to 6 and Comparative Examples 3 and 4 were cut into 297 mm x 210 mm pieces, and three-sided pouches with openings were fabricated using the cut packaging films. The three-sided pouches were formed by folding the cut packaging films so that the sealant layers faced each other and heat-sealing the peripheral edges of the sealant layers. Then, tap water (city water) was poured into the opening to seal the opening of the three-sided pouch, thereby preparing a sealed pouch. Then, the sealed pouch was subjected to a boiling treatment at 95°C for 30 minutes in a boiling treatment device. After that, a 100mm x 100mm test piece was cut out from the sealed body after the boiling treatment, and the oxygen permeability (unit: cc / m) of this test piece was measured in the same manner as before the boiling treatment. 2 The results are shown in Tables 3 and 4.

[0109] (2) Ratio of polyolefin resins in the entire packaging film The proportion (mass %) of polyolefin resin in the entire packaging film was calculated by converting the weight of the packaging film into specific gravity for the packaging films of Examples 1 to 11 and Comparative Examples 1 to 4. The results are shown in Tables 1 to 6.

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3]

[0113] [Table 4]

[0114] [Table 5]

[0115] [Table 6]

[0116] The results shown in Tables 1 to 6 show that the packaging films of the examples all had a high polyolefin resin ratio of 90% by mass or more in the overall packaging film, and had sufficiently low oxygen permeability before retort treatment. Therefore, it was confirmed that the packaging film of the present disclosure has excellent gas barrier properties while suppressing a decrease in the proportion of polyolefin resin in the entire packaging film. [Explanation of symbols]

[0117] 10...gas barrier film, 20...base material layer, 21...polyolefin-based base material layer, 22...heat-resistant layer, 30...anchor coat layer, 40...vapor deposition layer, 50...coating layer, 60...adhesive layer, 70...sealant layer, 100...packaging film, 200...packaging bag (packaging container), 300...packaged product, C...contents

Claims

1. a gas barrier film, an adhesive layer, and a sealant layer in this order; the gas barrier film has a substrate layer, an anchor coat layer, and a vapor deposition layer in this order; the substrate layer has a polyolefin-based substrate layer containing a polyolefin-based resin, the polyolefin-based resin contained in the polyolefin-based substrate layer is a polyethylene-based resin, the anchor coat layer contains a polyurethane resin, The anchor coat layer has a thickness of 0.2 μm or more, the adhesive layer is obtained by laminating an adhesive resin composition containing a polyolefin-based adhesive resin to the gas barrier film by melt extrusion, The packaging film, wherein the sealant layer comprises a polyolefin resin.

2. The packaging film according to claim 1 , wherein the anchor coat layer has a thickness of 2 μm or more.

3. The packaging film according to claim 1 , wherein the anchor coat layer has a thickness of 2.5 μm or less.

4. The packaging film according to claim 1 , wherein the polyolefin-based substrate layer is a stretched film.

5. The packaging film according to claim 1 , wherein the gas barrier film further comprises a coating layer between the vapor deposition layer and the adhesive layer, the coating layer covering the vapor deposition layer.

6. A packaging container comprising the packaging film according to any one of claims 1 to 5.

7. A packaging product comprising the packaging container according to claim 6 and contents accommodated in the packaging container.

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