Packaging film, packaging bag, and packaged product

Abstract

A packaging film according to the present invention comprises an ink layer, a base material layer, an adhesive layer, and a sealant layer in the stated order. The ink layer is coated with a coating layer, and the coating layer is obtained using a coating layer resin composition containing a polyurethane resin and a curing agent, or a coating layer resin composition containing a polyamide-imide resin. The ink layer is obtained using an ink containing a polyurethane resin.

Description

Packaging films, packaging bags and packaging products

[0001] The present disclosure relates to packaging films, packaging bags, and packaging products.

[0002] A packaging film generally comprises a base layer, an adhesive layer, and a sealant layer in this order. When an ink layer for displaying letters, pictures, etc. is provided in such a packaging film, the ink layer is generally provided on the sealant layer side (back side) of the base layer from the viewpoint of water resistance. For example, Patent Document 1 listed below discloses a packaging body made of a laminated film including a base layer, a printing layer (ink layer), and a sealant layer.

[0003] Japanese Patent Application Laid-Open No. 2019-182536

[0004] However, although the packaging material described in Patent Document 1 can prevent the ink layer from peeling even when subjected to retort treatment, there is room for improvement in terms of preventing delamination when performing retort treatment.

[0005] An object of the present disclosure is to provide a packaging film, a packaging bag, and a packaging product that can suppress peeling of an ink layer and also suppress delamination even when subjected to retort treatment.

[0006] To solve the above-mentioned problems, one aspect of the present disclosure provides a packaging film comprising an ink layer, a substrate layer, an adhesive layer, and a sealant layer in this order, the ink layer being coated with a coating layer, the coating layer being obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent, or a resin composition for a coating layer containing a polyamideimide resin, and the ink layer being obtained using an ink containing a polyurethane resin. Here, the coating layer may be a cured product of the resin composition for a coating layer containing a polyurethane resin and a curing agent, or a cured product of the resin composition for a coating layer containing a polyamideimide resin. Alternatively, the coating layer may contain a reaction product of a polyurethane resin and a curing agent, or a cured product of a polyamideimide resin. Furthermore, the ink layer may contain an ink containing a polyurethane resin, or a cured product of an ink containing a polyurethane resin. Alternatively, the ink layer may contain a polyurethane resin, or a cured product of a polyurethane resin. The packaging film can prevent peeling of the ink layer and delamination even when subjected to retort treatment.

[0007] The inventors of the present disclosure speculate that the reason for the above-mentioned effects is as follows. Specifically, when the resin composition for the coating layer contains a polyurethane resin or a polyamideimide resin, or when the ink contains a polyurethane resin, both the coating layer and the ink layer can have high hot water resistance. Furthermore, when the resin composition for the coating layer contains a polyurethane resin and a curing agent, or when the resin composition contains a polyamideimide resin, the coating layer can have high heat resistance. In particular, when the resin composition for the coating layer contains a polyurethane resin and a curing agent, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the polyurethane resin. As a result, the coating layer is more likely to have high heat resistance. Therefore, even when the packaging film is retorted, the coating layer is less likely to deteriorate due to heat, and the ink layer is sufficiently protected from hot water by the coating layer, thereby suppressing deterioration of the ink layer. As a result, a decrease in adhesion of the ink layer to the substrate layer is suppressed, and peeling of the ink layer is suppressed. Furthermore, the inventors of the present disclosure speculate that if the ink layer and adhesive layer are in contact on the sealant layer side of the base layer, the heat generated during retort treatment will absorb components of the adhesive layer into the ink layer, reducing the cohesive strength of the ink layer and, as a result, making the packaging film more susceptible to delamination. In contrast, the packaging film of the present disclosure has an ink layer on the opposite side of the base layer from the sealant layer, and the ink layer and adhesive layer are separated, so that even when retort treatment is performed, a decrease in adhesion between the adhesive layer and the base layer is suppressed. Therefore, even when retort treatment is performed, delamination in the packaging film is suppressed. The inventors of the present disclosure speculate that the above-mentioned effects are achieved for the above reasons.

[0008] In the packaging film, the coating layer may be obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent. In the packaging film, the ink preferably further contains a curing agent. Here, the ink contains a polyurethane resin and a curing agent, and the ink layer contains a cured product of the ink containing the polyurethane resin and the curing agent. The ink layer may contain a reaction product of the polyurethane resin and the curing agent. In this case, when obtaining the ink layer using the ink, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the polyurethane resin. As a result, the cohesive strength of the ink layer itself can be increased, making the ink layer less susceptible to destruction. Furthermore, the crosslinking reaction (high molecular weight) of the polyurethane resin also improves the heat resistance of the ink layer itself. Therefore, even if the ink layer is exposed at the edge of the packaging film (the exposed surface along the thickness direction of the packaging film), deterioration of the exposed portion of the ink layer, and even deterioration of the ink layer itself, is suppressed after retort processing of the packaging film. As a result, peeling of the ink layer from the base layer can be further suppressed.

[0009] In the packaging film, the curing agent contained in the resin composition for the coating layer may include an isocyanate-based curing agent. Here, an isocyanate-based curing agent refers to a curing agent having an isocyanate group. In this case, the coating layer can effectively have high heat resistance. Therefore, even when the packaging film is retorted, the coating layer is less likely to deteriorate due to heat, and the ink layer is effectively protected from hot water by the coating layer, effectively suppressing deterioration of the ink layer. As a result, a decrease in adhesion of the ink layer to the base layer is effectively suppressed, and peeling of the ink layer is effectively suppressed. In the packaging film, the resin composition for the coating layer may further include a wax. In the packaging film, the wax preferably includes a polyamide wax and a polyolefin wax. In this case, peeling of the ink layer can be further suppressed even when retorted.

[0010] In the packaging film, the curing agent contained in the ink preferably includes an isocyanate-based curing agent. In this case, the cohesive strength of the ink layer can be effectively increased. Therefore, even if the ink layer is exposed at the edge of the packaging film (the exposed surface along the thickness direction of the packaging film), deterioration of the exposed portion of the ink layer, and even deterioration of the ink layer itself, is effectively suppressed after retorting the packaging film, thereby more effectively suppressing peeling of the ink layer from the base layer. In the packaging film, the coating layer may be obtained using a resin composition for the coating layer containing a polyurethane resin and a curing agent, the curing agent contained in the resin composition for the coating layer may include an isocyanate-based curing agent, the resin composition for the coating layer may further include a wax, the ink may further include a curing agent, and the curing agent contained in the ink may include an isocyanate-based curing agent. With the packaging film, peeling of the ink layer and delamination can be effectively suppressed even after retorting. In the packaging film, the wax may include a polyamide wax and a polyolefin wax. The packaging film can more effectively prevent the ink layer from peeling even when subjected to retort treatment.

[0011] The packaging film preferably further comprises a gas barrier layer between the adhesive layer and the base layer, which further improves the gas barrier properties of the packaging film.

[0012] In the packaging film, the base material layer and the sealant layer may contain a polyolefin resin. In this case, since the base material layer and the sealant layer contain a polyolefin resin, it is not necessary to separate the base material layer and the sealant layer, and recycling can be easily carried out.

[0013] Another aspect of the present disclosure provides a packaging bag including the packaging film described above. The packaging bag includes the packaging film described above, and the packaging film can suppress peeling of the ink layer and delamination even when subjected to retort treatment. Therefore, the packaging bag can suppress peeling of the ink layer and delamination even when subjected to retort treatment.

[0014] Yet another aspect of the present disclosure provides a packaging product including the packaging bag described above and contents accommodated in the packaging bag. The packaging product includes the packaging bag described above, and the packaging bag can suppress peeling of the ink layer and delamination even when subjected to retort treatment. Therefore, the packaging product can suppress peeling of the ink layer and delamination even when subjected to retort treatment. This enables the packaging product to have a longer life.

[0015] According to the present disclosure, a packaging film, a packaging bag, and a packaging product are provided that can suppress peeling of the ink layer and also suppress delamination even when subjected to retort treatment.

[0016] 1A and 1B are cross-sectional views of an embodiment of a packaging film of the present disclosure and an embodiment of a packaged product of the present disclosure.

[0017] Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

[0018] <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.

[0019] The packaging film 100 shown in FIG. 1 includes an ink layer 20, a substrate layer 30, an adhesive layer 60, and a sealant layer 70, in this order, and the ink layer 20 is coated with a coating layer 10. That is, the packaging film 100 includes the coating layer 10, the ink layer 20, the substrate layer 30, the adhesive layer 60, and the sealant layer 70, in this order. The coating layer 10 is obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent, or a resin composition for a coating layer containing a polyamideimide resin. The ink layer 20 is obtained using an ink containing a polyurethane resin. The packaging film 100 may include an anchor coat layer 40 and a gas barrier layer 50, in this order, between the substrate layer 30 and the adhesive layer 60. Here, the packaging film 100 does not necessarily include the anchor coat layer 40. The packaging film 100 may further include an intermediate layer (not shown) between the substrate layer 30 and the adhesive layer 60. According to the packaging film 100, even when a retort treatment is performed, peeling of the ink layer 20 can be suppressed, and delamination can also be suppressed.

[0020] The coating layer 10, the ink layer 20, the substrate layer 30, the anchor coat layer 40, the gas barrier layer 50, the adhesive layer 60, the sealant layer 70 and the intermediate layer will be described in detail below.

[0021] (1) Coating Layer The coating layer 10 is a layer that coats the ink layer 20. The coating layer 10 is provided on the side of the ink layer 20 opposite the sealant layer 70. The coating layer 10 may be provided only on a portion of the surface of the ink layer 20 opposite the sealant layer 70, or may be provided on the entire surface. The coating layer 10 is obtained using a resin composition for a coating layer containing a polyurethane resin as a binder resin and a curing agent or a polyamide-imide resin. Examples of polyurethane resins include dispersions such as the Takelac W and WS series manufactured by Mitsui Chemicals, Inc., the ETERNACOLL series manufactured by Ube Industries, Ltd., the Hydran series manufactured by DIC Corporation, and the Adeka Bontiter HUX series manufactured by ADEKA Corporation, as well as polyurethane resins in solvent-based coating solutions such as the Takelac E series manufactured by Mitsui Chemicals, Inc. and the Burnock series manufactured by DIC Corporation. Examples of polyamide-imide resins include polyamide-imide resins such as the Viromax series manufactured by Toyobo Co., Ltd.

[0022] The content of polyurethane resin in the solid content contained in the resin composition for the coating layer is not particularly limited, and may be, for example, 50% by mass or more, 70% by mass or more, or 90% by mass or more. The content of polyamideimide resin in the solid content contained in the resin composition for the coating layer is not particularly limited. The contents of both polyurethane resin and polyamideimide resin in the solid content contained in the resin composition for the coating layer may be 99% by mass or less, taking into account the use of additives.

[0023] The curing agent is consumed by a crosslinking reaction with the polyurethane resin during the process of forming the coating layer 10. An isocyanate-based curing agent is preferable as the curing agent. In this case, the coating layer 10 can effectively have high heat resistance. Therefore, even when the packaging film 100 is retorted, the coating layer 10 is less likely to deteriorate due to heat, and the ink layer 20 is effectively protected from hot water by the coating layer 10, effectively suppressing deterioration of the ink layer 20. As a result, a decrease in adhesion of the ink layer 20 to the substrate layer 30 is effectively suppressed, and peeling of the ink layer 20 is effectively suppressed.

[0024] Examples of the isocyanate curing agent include hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), which may be used alone or in combination.

[0025] The content of the curing agent in the resin composition for the covering layer is not particularly limited and may be, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. The content of the curing agent in the resin composition for the covering layer may be 10% by mass or less.

[0026] The resin composition for the coating layer may further contain a wax. In this case, the adhesion of the coating layer 10 to the ink layer 20 is further improved. Examples of waxes include polyamide wax and polyolefin wax. These may be used alone or in combination. The wax preferably contains polyamide wax and polyolefin wax. In this case, peeling of the ink layer 20 can be further suppressed even when retort treatment is performed.

[0027] The wax content in the solid content contained in the resin composition for the coating layer is not particularly limited, and may be, for example, 0% by mass, 1% by mass or more, 3% by mass or more, or 5% by mass or more. The wax content in the solid content contained in the resin composition for the coating layer may be 10% by mass or less. The wax content in the solid content contained in the resin composition for the coating layer may be 1% by mass or more and 10% by mass or less, 3% by mass or more and 10% by mass or less, or 5% by mass or more and 10% by mass or less.

[0028] The pigment content in the solid content contained in the resin composition for the covering layer is preferably lower than the pigment content in the ink used to obtain the ink layer 20. In this case, the mechanical strength of the covering layer 10 is further improved. In addition, the transparency of the covering layer 10 is higher than that of the ink layer 20, improving the visibility of the ink layer 20. Examples of pigments contained in the resin composition for the covering layer include inorganic pigments such as titanium oxide and iron oxide, and organic pigments such as isoindolinone, disazo, polyazo, diketopyrrolopyrrole, quinacridone, and phthalocyanine. These may be used alone or in combination.

[0029] The ratio R1 of the pigment content in the solid content contained in the resin composition for the coating layer to the pigment content in the solid content contained in the ink used to obtain the ink layer 20 may be, for example, less than 1, and may be 0.5 or less, 0.3 or less, or 0.1 or less. The ratio R1 may be 0 or more. The ratio R1 is preferably 0.1 or more and less than 1, more preferably 0.1 or more and 0.5 or less, and particularly preferably 0.1 or more and 0.3 or less.

[0030] The resin composition for the coating layer contains a solvent, such as ethyl acetate.

[0031] The resin composition for the coating layer may contain, as necessary, a plasticizer, a drying agent, a matting agent, a stabilizer, etc. Here, the matting agent is different from the pigment in the ink used to obtain the ink layer 20, and is a particle used to suppress the gloss of the coating layer 10.

[0032] The thickness of the coating layer 10 is not particularly limited and may be adjusted as needed, but from the viewpoint of improving the hot water resistance of the ink layer 20, it is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 1 μm or more. From the viewpoint of recyclability, the thickness of the coating layer 10 is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less. The thickness of the coating layer 10 is preferably 0.1 μm or more and 5 μm or less, more preferably 0.5 μm or more and 4 μm or less, and particularly preferably 0.5 μm or more and 3 μm or less.

[0033] Examples of methods for forming the coating layer 10 include conventionally known printing methods, such as printing methods that require a plate, such as gravure printing, offset printing, and flexographic printing, and printing methods that do not require a plate, such as ink jet printing.

[0034] (2) Ink Layer The ink layer 20 is a layer that displays characters, pictures, symbols, and combinations thereof. The ink layer 20 is provided on the substrate layer 30 opposite the sealant layer 70, between the substrate layer 30 and the coating layer 10. By providing the ink layer 20 on the substrate layer 30 opposite the sealant layer 70, the ink layer 20 and the adhesive layer 60 are separated, and even when retort processing is performed, a decrease in adhesion between the adhesive layer 60 and the substrate layer 30 is suppressed. This suppresses delamination in the packaging film 100 even when retort processing is performed. Furthermore, even when the packaging film 100 is retort processed, the components of the adhesive layer 60 are not absorbed by the ink layer 20. Therefore, when obtaining the adhesive layer 60, it is not necessary to use more adhesive than necessary to account for the components of the adhesive layer 60 absorbed by the ink layer 20, thereby reducing the environmental impact. The ink layer 20 is obtained using an ink containing a polyurethane resin as a binder resin.

[0035] The content of polyurethane resin in the solid content of the ink is not particularly limited, and may be, for example, 20% by mass or more, 30% by mass or more, or 40% by mass or more. The content of polyurethane resin in the solid content of the ink may be 80% by mass or less, 70% by mass or less, or 60% by mass or less. The content of polyurethane resin in the solid content of the ink may be 20% by mass or more and 80% by mass or less, 30% by mass or more and 70% by mass or less, or 40% by mass or more and 60% by mass or less.

[0036] The ink layer 20 may or may not further contain a curing agent, but preferably does. In this case, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the polyurethane resin. As a result, the cohesive strength of the ink layer 20 itself can be increased, making the ink layer 20 less susceptible to destruction. Furthermore, the crosslinking reaction (high molecular weight) of the polyurethane resin also improves the heat resistance of the ink layer 20 itself. Therefore, even if the ink layer 20 is exposed at the end surface of the packaging film 100 (the exposed surface along the thickness direction of the packaging film 100), deterioration of the exposed portion of the ink layer 20, and even deterioration of the exposed portion of the ink layer 20, is suppressed after retorting the packaging film 100. As a result, peeling of the ink layer 20 from the substrate layer 30 can be further suppressed. An isocyanate-based curing agent is preferred as the curing agent. In this case, the cohesive strength of the ink layer 20 can be effectively increased. Therefore, even if the ink layer 20 is exposed at the end surface of the packaging film 100 (the exposed surface along the thickness direction of the packaging film 100), deterioration of the exposed portion of the ink layer 20, and further deterioration of the exposed portion of the ink layer 20, is effectively suppressed after retort processing of the packaging film 100, so peeling of the ink layer 20 from the base layer 30 can be more effectively suppressed.

[0037] Examples of the isocyanate curing agent include hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), which may be used alone or in combination.

[0038] The content of the curing agent in the ink is not particularly limited, and may be, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. The content of the curing agent in the ink may be 10% by mass or less, or 8% by mass or less. The content of the curing agent in the ink may be 1% by mass or more and 10% by mass or less, or 3% by mass or more and 8% by mass or less.

[0039] The ink may further contain wax. In this case, the adhesion of the coating layer 10 to the ink layer 20 is further improved. Examples of wax include polyamide wax and polyolefin wax. These may be used alone or in combination.

[0040] The wax content in the solid content of the ink is not particularly limited, and may be, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. The wax content in the solid content of the ink may be 10% by mass or less. The wax content in the solid content of the ink may be 1% by mass or more and 10% by mass or less, or 3% by mass or more and 10% by mass or less.

[0041] The ink contains a pigment. Examples of pigments include inorganic pigments such as titanium oxide and iron oxide, and organic pigments such as isoindolinone, disazo, polyazo, diketopyrrolopyrrole, quinacridone, and phthalocyanine. These may be used alone or in combination. The pigment content in the solid content of the ink is not particularly limited and may be, for example, 30% by mass or more, 40% by mass or more, or 50% by mass or more. The pigment content in the solid content of the ink may be 90% by mass or less. The pigment content in the solid content of the ink may be 30% by mass or more and 90% by mass or less, 40% by mass or more and 90% by mass or less, or 50% by mass or more and 90% by mass or less.

[0042] The ink contains a solvent. The solvent may be an aqueous solvent or an oil-based solvent, but an aqueous solvent is preferred. When the solvent is an aqueous solvent, the environmental load can be further reduced. Examples of the aqueous solvent include water and alcohol.

[0043] The ink may contain plasticizers, desiccants, stabilizers, and the like as needed. The ink may or may not further contain a biomass component. However, from the perspective of reducing environmental impact, it is preferable for the ink to further contain a biomass component. Here, biomass components refer to components obtained from biological resources (biomass), such as cotton, pulp, rice bran, vegetable oil, and angiosperm seeds. The ink layer 20 may be composed of a single layer or multiple layers. When monochromatic printing is performed on the substrate layer 30, the ink layer 20 is composed of a single layer. When multicolor printing is performed on the substrate layer 30, the ink layer 20 is composed of multiple layers. In this case, for example, a first ink layer may be formed by printing a solid white ink over the entire surface of the substrate layer 30, and a second ink layer containing letters, pictures, etc. may be formed on the first ink layer. Furthermore, a layer of ink containing a black pigment such as black carbon or a metal powder may be provided for light blocking. The ink layer 20 may be provided only on a portion of the surface of the base material layer 30 , or may be provided on the entire surface of the base material layer 30 .

[0044] The thickness of the ink layer 20 is not particularly limited and may be adjusted as needed, but from the viewpoint of concealing the color of the contents, it is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 1 μm or more. From the viewpoint of recyclability, the thickness of the ink layer 20 is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less. The thickness of the ink layer 20 may be 0.1 μm or more and 5 μm or less, 0.5 μm or more and 5 μm or less, or 1 μm or more and 5 μm or less.

[0045] Examples of methods for forming the ink layer 20 include conventionally known printing methods, such as printing methods requiring a plate, such as gravure printing, offset printing, and flexographic printing, and printing methods not requiring a plate, such as ink jet printing.

[0046] (3) Substrate Layer The substrate layer 30 can be a film substrate or a paper substrate made of a resin material. Examples of the resin material include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene and polypropylene, polyamide resins such as polystyrene and nylon 66, polycarbonate resin, polyacrylonitrile resin, and polyimide resin. The resin material is processed into a film and used as the film substrate. Preferred resin materials are polyolefin resins such as polyethylene and polypropylene. Examples of polyethylene include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (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 copolymer. Examples of α-olefins include ethylene and 1-butene. Among polyolefin resins, polypropylene is preferred from the perspective of heat resistance. Among polypropylenes, when emphasis is placed on the rigidity and heat resistance of the packaging bag obtained using the packaging film 100, it is preferable to use homopolypropylene.

[0047] The resin material may be a non-recycled resin, a recycled resin, or a mixture thereof. When using recycled resin for the base layer 30 because it does not come into contact with the contents, a material-recycled resin (material recycled resin) may be used, but from the viewpoints of hygiene and quality, a chemically recycled resin (chemically recycled resin) is preferred. The non-recycled resin may be a petroleum-derived resin obtained using petroleum-derived raw material monomers, a biomass-derived resin obtained using biomass-derived raw material monomers, or a mixture thereof. However, from the viewpoint of reducing the environmental load, a biomass-derived resin is preferred. The chemically recycled resin may be composed of a single chemically recycled resin or a mixture of multiple types of chemically recycled resins. The material-recycled resin may be composed of a single material-recycled resin or a mixture of multiple types of material-recycled resins.

[0048] The paper substrate is a substrate containing paper, and paper refers to a material containing plant-derived pulp as a primary component, where "primary component" refers to a component containing plant-derived pulp at 50% by mass or more. The packaging film 100 includes a paper substrate, contributing to a reduction in the amount of plastic material used. Specific examples of paper substrates include fine paper, special fine paper, coated paper, art paper, cast-coated paper, construction paper, kraft paper, and glassine paper. The paper substrate may or may not further include a coating layer at least on the sealant layer 70 side of the paper. The inclusion of a coating layer on the paper substrate prevents the anchor coat layer 40 from penetrating into the paper and also serves as a sealant to fill in unevenness in the paper, allowing the anchor coat layer 40 to be formed uniformly without defects. The coating layer may further include a binder resin and, if necessary, a filler. Examples of binder resins include various copolymers such as styrene-butadiene copolymer, styrene-acrylic copolymer, and ethylene-vinyl acetate copolymer, as well as polyvinyl alcohol-based resins and cellulose-based resins. Examples of fillers include kaolin, calcium carbonate, talc, mica, etc. When the paper substrate does not have a coating layer, discoloration of the paper due to retort treatment of the packaging film 100 is less likely to occur.

[0049] The base layer 30 may be composed of a single layer or multiple layers.

[0050] The substrate layer 30 may further contain additives such as fillers, antistatic agents, plasticizers, lubricants, light-shielding pigments, and antioxidants, as necessary. The substrate layer 30 may be colored. When the substrate layer 30 is white, the print can appear clearer. When the substrate layer 30 contains a light-shielding pigment, the substrate layer 30 can function as a light-shielding layer.

[0051] The content of the resin material in the base layer 30 is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0052] When the base material layer 30 is a film base material made of a resin material, it may be a non-stretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. When the base material layer 30 is a uniaxially stretched film, it is possible to improve the tearability and heat resistance of the packaging film 100. When the base material layer 30 is a biaxially stretched film, it is possible to improve the mechanical strength and dimensional stability of the packaging film 100.

[0053] When an adhesive layer 60 is provided on the surface of the base material layer 30, in order to enhance adhesion to the adhesive layer 60, various pretreatments such as corona treatment, plasma treatment, ozone treatment, and flame treatment may be performed on the surface on the adhesive layer 60 side, or a coating layer such as an easy-adhesion layer may be provided.

[0054] The thickness of the substrate layer 30 is not particularly limited. From the viewpoint of reducing materials to reduce environmental impact and from the viewpoint of obtaining excellent heat resistance, impact resistance, and gas barrier properties, the thickness of the substrate layer 30 may be 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, or 40 μm or more. Furthermore, from the viewpoint of reducing the amount of plastic used and thereby reducing environmental impact, the thickness of the substrate layer 30 may be 100 μm or less, 60 μm or less, or 50 μm or less. The thickness of the substrate layer 30 may be 10 μm or more to 100 μm or less, 10 μm or more to 60 μm or less, 10 μm or more to 50 μm or less, 15 μm or more to 100 μm or less, 15 μm or more to 60 μm or less, or 15 μm or more to 50 μm or less.

[0055] (4) Anchor Coat Layer The anchor coat layer 40 is a layer for further improving the adhesion between the base layer 30 and the gas barrier layer 50, and may be provided between the base layer 30 and the gas barrier layer 50.

[0056] The material constituting the anchor coat layer 40 is not particularly limited as long as it can improve the adhesion between the substrate layer 30 and the gas barrier layer 50, but preferably contains a polyurethane resin. Such a polyurethane resin is 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 need only 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 crosslinker or curing agent. The polyol compound and the isocyanate compound may be either a monomer or a polymer.

[0057] The thickness of the anchor coat layer 40 is not particularly limited, but from the viewpoint of improving the adhesion between the base layer 30 and the gas barrier layer 50, it is preferably 20 nm or more, more preferably 50 nm or more, and particularly preferably 100 nm or more. The thickness of the anchor coat layer 40 is preferably 2000 nm or less. When the thickness of the anchor coat layer 40 is 2000 nm or less, the deterioration of the gas barrier property can be more effectively suppressed even after retort treatment compared to when the thickness of the anchor coat layer 40 exceeds 2000 nm. Furthermore, from the viewpoint of recyclability, the thickness of the anchor coat layer 40 is more preferably 1000 nm or less. The thickness of the anchor coat layer 40 may be 20 nm or more to 2000 nm or less, 50 nm or more to 2000 nm or less, or 100 nm or more to 2000 nm or less.

[0058] (5) Gas Barrier Layer The gas barrier layer 50 is a layer that improves the gas barrier properties of the packaging film 100. The gas barrier properties are barrier properties against gases such as water vapor or oxygen.

[0059] The gas barrier layer 50 includes a vapor-deposited layer or a metal foil. The gas barrier layer 50 may further include a gas barrier coating layer on the vapor-deposited layer or the metal foil. (Vapor-deposited Layer) The vapor-deposited layer is, for example, composed of a vapor-deposited layer of metal or a vapor-deposited layer of metal oxide. Examples of metals constituting the vapor-deposited layer of metal or the vapor-deposited layer of metal oxide include at least one metal selected from the group consisting of Si, Al, Mg, Sn, Ti, and In. Preferred metal oxides are silicon oxide (SiOx), aluminum oxide (AlOx), or mixtures thereof. 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 vapor-deposited layer may be composed of a single layer or multiple layers.

[0060] The thickness of the vapor-deposited layer is not particularly limited, but is preferably 5 nm or more. In this case, the deterioration of the gas barrier property of the packaging film 100 can be more sufficiently suppressed even after retort treatment, compared to when the thickness of the vapor-deposited layer is less than 5 nm. The thickness of the vapor-deposited layer is more preferably 8 nm or more, and particularly preferably 10 nm or more. The thickness of the vapor-deposited layer is preferably 300 nm or less. In this case, the deterioration of the gas barrier property of the packaging film 100 can be more effectively suppressed even after retort treatment, compared to when the thickness of the vapor-deposited layer exceeds 300 nm, and the recyclability of the packaging film 100 can also be improved. The thickness of the vapor-deposited layer is more preferably 200 nm or less, and particularly preferably 100 nm or less. The thickness of the vapor-deposited layer may be 5 nm or more to 300 nm or less, 8 nm or more to 200 nm or less, or 10 nm or more to 100 nm or less. (Metal Foil) Examples of metal foils include aluminum foil, stainless steel foil, and copper foil. Among these, aluminum foil is preferred because of its light weight and flexibility.

[0061] (Gas barrier coating layer) The gas barrier coating layer has gas barrier properties and is a layer that coats the vapor deposition layer or the metal foil. In this case, the gas barrier properties of the packaging film 100 are improved. Furthermore, the gas barrier coating layer can suppress a decrease in the gas barrier properties of the packaging film 100 even if damage such as cracks occurs in the vapor deposition layer or the metal foil.

[0062] 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.

[0063] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. Among these, polyvinyl alcohol (PVA) is particularly preferred because it can easily improve the oxygen barrier properties of the gas barrier coating layer.

[0064] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC ２ H ５ ) ４ ], triisopropoxyaluminum [Al(O-2'-C ３ H ７ ) ３ Tetraethoxysilane (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, R ３ is an alkyl group or -C ２ H ４ OCH ３In this case, it is possible to improve the adhesion between the gas barrier coating layer and the vapor deposition layer, and it is possible to suppress delamination between layers in the packaging film 100. ２ and R ３ may be the same or different. ３ R may be the same or different. ２ Examples of the monovalent organic group represented by R 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 by curing, and can impart greater lamination strength to the packaging film 100 even after retort treatment. ３ Examples of the alkyl group represented by the formula (I) include a methyl group and an ethyl group. Among these, a methyl group is preferred. In this case, hydrolysis occurs rapidly. n represents an integer of 1 or more. When n is 1, the silane coupling agent represents a monomer, whereas when n is 2 or more, 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 retort 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] The gas barrier coating layer can be formed by coating a composition for forming a gas barrier coating layer on a vapor deposition layer or a metal foil, followed by heating and drying. The composition for forming a gas barrier coating layer can be prepared by dissolving a water-soluble polymer in an aqueous solvent (water, a mixed solvent of water and alcohol, etc.) 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.

[0068] The thickness of the gas barrier coating layer may be 20 nm or more, 40 nm or more, 60 nm or more, 80 nm or more, 90 nm or more, or 100 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 retort 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 suppress deterioration of gas barrier properties due to cracking of the gas barrier coating layer during coating. From this perspective, the thickness of the gas barrier coating layer may be 80 to 1000 nm. The thickness of the gas barrier coating layer may be 20 nm or more to 1000 nm or less, 20 nm or more to 700 nm or less, 40 nm or more to 500 nm or less, or 40 nm or more to 400 nm or less.

[0069] (6) Adhesive Layer Examples of the adhesive layer 60 include an adhesive layer formed using an adhesive agent and an adhesive layer containing an adhesive resin (hereinafter also referred to as an "adhesive resin layer").

[0070] Examples of adhesives include known adhesives such as urethane adhesives, polyester adhesives, polyamide adhesives, epoxy adhesives, and isocyanate adhesives.

[0071] The adhesive may or may not contain a biomass-derived component, but preferably contains a biomass-derived component from the viewpoint of reducing the environmental impact. Specific examples of adhesives containing a biomass-derived component include the "DIC Dry BM Series" manufactured by DIC Corporation and the "ECOAD Series" manufactured by Toyo Ink Co., Ltd.

[0072] The adhesive may be a solvent-containing adhesive or a solvent-free adhesive (solvent-free adhesive), but is preferably a solvent-free adhesive from the viewpoint of reducing the environmental impact. The adhesive may or may not have gas barrier properties, but is preferably gas barrier properties from the viewpoint of improving the gas barrier properties of the packaging film 100.

[0073] The adhesive resin is a heat-fusible adhesive thermoplastic resin that can be melted by heat and fused to each other. For example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (linear) low-density polyethylene, polypropylene, ethylene-propylene copolymer, methylpentene polymer, polyolefin resins such as polyethylene or polypropylene (also referred to as "polyolefin resins") modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and the like, and other resins can be used.

[0074] The thickness of the adhesive layer 60 is not particularly limited and may be, for example, 1 μm or more. By making the thickness of the adhesive layer 60 1 μm or more, sufficient adhesive strength can be obtained. The thickness of the adhesive layer 60 may be 2 μm or more. From the viewpoint of recyclability, the thickness of the adhesive layer 60 may be 50 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, or 3 μm or less. The thickness of the adhesive layer 60 may be 1 μm or more and 50 μm or less, 1 μm or more and 20 μm or less, 1 μm or more and 10 μm or more, or 1 μm or more and 5 μm or less.

[0075] (7) Sealant Layer As the sealant layer 70, a polyolefin resin film, a polyester resin film, or the like can be used.

[0076] Polyolefin resin films are suitable for use in terms of sealability (or sealability), and include polyolefin resins. Examples of polyolefin resins include polyethylene and polypropylene. Examples of polyethylene include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-(meth)acrylic acid copolymer. Examples of polypropylene include homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymer. Examples of α-olefins include ethylene and 1-butene. Among polyolefin resins, polypropylene is preferred from the viewpoint of heat resistance. Among polypropylenes, homopolypropylene is preferred when the rigidity and heat resistance of the packaging bag obtained using the packaging film 100 are important.

[0077] Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0078] The polyolefin resin and polyester resin may be a biomass-derived resin or a mechanically recycled or chemically recycled resin.

[0079] The sealant layer 70 may contain additives as needed. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins. The sealant layer 70 may be colored. When the sealant layer 70 is white, the print can appear clearer. When the sealant layer 70 contains a light-blocking pigment, the sealant layer 70 can function as a light-blocking layer.

[0080] The sealant layer 70 may be configured as a single layer or as multiple layers.

[0081] When the base layer 30 contains a polyolefin resin, it is preferable that the sealant layer 70 also contains a polyolefin resin. For example, when the base layer 30 contains polypropylene, it is preferable that the sealant layer 70 also contains polypropylene, and when the base layer 30 contains polyethylene, it is preferable that the sealant layer 70 also contains polyethylene. In this case, the proportion of a single material (polyolefin resin) contained in the packaging film 100 can be further increased, and the recyclability of the packaging film 100 is further improved.

[0082] The sealant layer 70 may be a stretched film or a non-stretched film, but is preferably a non-stretched film. In this case, the melting point of the sealant layer 70 can be made lower than the melting point of the base material layer 30, making it easier to prevent the base material layer 30 from melting when the packaging film 100 is heat-sealed. The sealant layer 70 may or may not be a peelable sealant.

[0083] The thickness of the sealant layer 70 is not particularly limited, but is preferably 40 μm or more, more preferably 50 μm or more, from the viewpoint of improving heat sealing properties. The thickness of the sealant layer 70 is preferably 100 μm or less, more preferably 80 μm or less, from the viewpoint of improving the flexibility of the packaging film 100. The thickness of the sealant layer 70 may be 40 μm or more and 100 μm or less, 50 μm or more and 100 μm or less, or 50 μm or more and 80 μm or less.

[0084] (8) Intermediate Layer The intermediate layer is a layer disposed between the base layer 30 and the adhesive layer 60. When the packaging film 100 further includes a gas barrier layer 50, the intermediate layer may be disposed between the gas barrier layer 50 and the adhesive layer 60, or between the gas barrier layer 50 and the base layer 30. The intermediate layer may be a film substrate or a paper substrate made of a resin material. Examples of the resin material include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (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 copolymer. Examples of α-olefins include ethylene and 1-butene. Among polyolefin resins, polypropylene is preferred from the viewpoint of heat resistance. Among polypropylenes, homopolypropylene is preferred when the rigidity and heat resistance of the packaging bag obtained using the packaging film 100 are important.

[0085] The resin material may be a non-recycled resin, a recycled resin, or a mixture thereof. When a recycled resin is used for the intermediate layer because it does not come into contact with the contents, a material recycled resin may be used, but from the viewpoints of hygiene and quality, it is preferable to use a chemical recycled resin. The non-recycled resin may be a petroleum-derived resin obtained using a petroleum-derived raw material monomer, a biomass-derived resin obtained using a biomass-derived raw material monomer, or a mixture thereof, but from the viewpoint of reducing the environmental load, a biomass-derived resin is preferable. The chemical recycled resin may be composed of a single chemical recycled resin or a mixture of multiple types of chemical recycled resins. The material recycled resin may be composed of a single material recycled resin or a mixture of multiple types of material recycled resins.

[0086] The paper substrate is a substrate containing paper, and paper refers to a material containing plant-derived pulp as a primary component, where "primary component" refers to a component containing plant-derived pulp at 50% by mass or more. The packaging film 100 includes a paper substrate, contributing to a reduction in the amount of plastic material used. Specific examples of paper substrates include fine paper, special fine paper, coated paper, art paper, cast-coated paper, construction paper, kraft paper, and glassine paper. The paper substrate may or may not further include a coating layer at least on the sealant layer 70 side of the paper. The inclusion of a coating layer on the paper substrate prevents the anchor coat layer 40 from penetrating into the paper and also serves as a sealant to fill in unevenness in the paper, allowing the anchor coat layer 40 to be formed uniformly without defects. The coating layer may further include a binder resin and, if necessary, a filler. Examples of binder resins include various copolymers such as styrene-butadiene copolymer, styrene-acrylic copolymer, and ethylene-vinyl acetate copolymer, as well as polyvinyl alcohol-based resins and cellulose-based resins. Examples of fillers include kaolin, calcium carbonate, talc, mica, etc. When the paper substrate does not have a coating layer, discoloration of the paper due to retort treatment of the packaging film 100 is less likely to occur.

[0087] The intermediate layer may be composed of a single layer or multiple layers.

[0088] The intermediate layer may further contain additives such as a filler, an antistatic agent, a plasticizer, a lubricant, a light-shielding pigment, and an antioxidant, as necessary. When the intermediate layer contains a light-shielding pigment, the intermediate layer can function as a light-shielding layer.

[0089] The content of the resin material in the intermediate layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0090] When the intermediate layer is a film substrate made of a resin material, it may be a non-stretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. When the intermediate layer is a uniaxially stretched film, it is possible to improve the tearability and heat resistance of the packaging film 100. When the intermediate layer is a biaxially stretched film, it is possible to improve the mechanical strength and dimensional stability of the packaging film 100.

[0091] When an adhesive layer is provided on the surface of the intermediate layer, in order to enhance adhesion to the adhesive layer 60, various pretreatments such as corona treatment, plasma treatment, ozone treatment, and flame treatment may be performed on the surface on the adhesive layer 60 side, or a coating layer such as an easy-adhesion layer may be provided.

[0092] The thickness of the intermediate layer is not particularly limited. From the viewpoint of reducing materials to reduce environmental impact and from the viewpoint of obtaining excellent heat resistance, impact resistance, and gas barrier properties, the thickness of the intermediate layer may be 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, or 40 μm or more. Furthermore, from the viewpoint of reducing the amount of plastic used and thereby reducing environmental impact, the thickness of the intermediate layer may be 100 μm or less, 60 μm or less, or 50 μm or less. The thickness of the intermediate layer may be 10 μm or more to 100 μm or less, 15 μm or more to 60 μm or less, or 20 μm or more to 50 μm or less.

[0093] <Packaging Product> 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 duplicated descriptions will be omitted. As shown in FIG. 2, the packaging product 300 includes a packaging bag 200 and contents C contained in the packaging bag 200. The packaging bag 200 shown in FIG. 2 includes a pair of packaging films 100. The packaging bag 200 is obtained by using a pair of packaging films 100 and heat-sealing the peripheral portions of the packaging films 100 with the sealant layers 70 facing each other.

[0094] This packaged product 300 includes a packaging bag 200, which can suppress peeling of the ink layer 20 and delamination even when subjected to a retort treatment. Therefore, the packaged product 300 can suppress peeling of the ink layer 20 and delamination even when subjected to a retort treatment. This allows the packaged product 300 to have a long life.

[0095] The packaging bag 200 may include one packaging film 100. In this case, 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.

[0096] Examples of the packaging bag 200 include a three-sided pouch, a four-sided pouch, a standing pouch, a gusset pouch, a pillow package, etc. The packaging bag 200 may further have a spout or a zipper depending on the application.

[0097] The content C is not particularly limited, and examples of the content C include food, liquid, medicine, electronic components, etc. The present disclosure is not limited to the above embodiment. For example, the packaging film of the present disclosure can be used not only for packaging bags but also for lids, etc.

[0098] <Summary of the Present Disclosure> The summary of the present disclosure is as follows. [1] A packaging film comprising an ink layer, a substrate layer, an adhesive layer, and a sealant layer in this order, wherein the ink layer is coated with a coating layer, wherein the coating layer is obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent, or a resin composition for a coating layer containing a polyamideimide resin, and wherein the ink layer is obtained using an ink containing a polyurethane resin. [2] The packaging film according to [1], wherein the coating layer is obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent. [3] The packaging film according to [1] or [2], wherein the ink further contains a curing agent. [4] The packaging film according to any of [1] to [3], wherein the curing agent contained in the resin composition for a coating layer contains an isocyanate-based curing agent. [5] The packaging film according to any of [1] to [4], wherein the resin composition for a coating layer further contains a wax. [6] The packaging film according to [5], wherein the wax contains a polyamide wax and a polyolefin wax. [7] The packaging film according to [3], wherein the curing agent contained in the ink comprises an isocyanate-based curing agent. [8] The packaging film according to [1], wherein the coating layer is obtained using a resin composition for coating layer comprising a polyurethane resin and a curing agent, wherein the curing agent contained in the resin composition for coating layer comprises an isocyanate-based curing agent, the resin composition for coating layer further comprises a wax, the ink further comprises a curing agent, and the curing agent contained in the ink comprises an isocyanate-based curing agent. [9] The packaging film according to [8], wherein the wax comprises a polyamide wax and a polyolefin wax.

[10] The packaging film according to any one of [1] to [9], further comprising a gas barrier layer between the adhesive layer and the base layer.

[11] The packaging film according to any one of [1] to

[10] , wherein the base layer and the sealant layer comprise a polyolefin resin.

[12] A packaging bag comprising the packaging film according to any one of [1] to

[11] .

[13] A packaged product comprising the packaging bag according to

[12] and a content placed in the packaging bag.

[0099] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0100] In the examples and comparative examples, the following base materials, additives, and adhesives were used. <Base materials of resin compositions for coating layer> Polyurethane medium 1: XGS-922 Medium NT, manufactured by Sakata Inx Corporation Polyurethane medium 2: Riogran R Medium, manufactured by Toyo Ink Co., Ltd. (Polyurethane medium 2 contains 20% by mass of polyurethane resin and 80% by mass of organic solvent (propyl acetate and ethyl acetate)) Polyamideimide resin solution: Coating liquid obtained by diluting Pyromax HR-15ET (manufactured by Toyobo Co., Ltd., melting point 300°C) with a solvent (ethanol / toluene = 1 / 1 (mass ratio)) so that the non-volatile component is 5% by mass.

[0101] <Ink base> Polyurethane ink 1: XGS-922 Red NT (manufactured by Sakata Inx Corporation) Polyurethane ink 2: Riogran F121 Red (manufactured by Toyo Ink Co., Ltd.) (pigment 10% by mass, polyurethane resin 20% by mass, organic solvent (propyl acetate and ethyl acetate) 70% by mass)

[0102] <Additives> Isocyanate-based curing agent 1: Lamiol R curing agent (1 mass% of a mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)), 34 mass% of synthetic resin, and 65 mass% of an organic solvent (ethyl acetate)), manufactured by Sakata Inx Corporation. Isocyanate-based curing agent 2: SP curing agent (1 mass% of hexamethylene diisocyanate (HDI), 49 mass% of a synthetic resin, and 50 mass% of an organic solvent (ethyl acetate)), manufactured by Toyo Ink Co., Ltd. Isocyanate-based curing agent 3: VM hardener (1 mass% of an isocyanate compound, 74 mass% of a synthetic resin, and 25 mass% of an organic solvent (ethyl acetate)), manufactured by Toyo Ink Co., Ltd. Antiblocking agent (B inhibitor): silica dispersion (25 mass% of silica, 15 mass% of a synthetic resin, and 60 mass% of an organic solvent (ethyl acetate and isopropyl alcohol), manufactured by Toyo Ink Co., Ltd. Wax dispersion 1: 280 additive (dispersion of polyamide (PA) wax (25% by mass of polyamide (PA) wax, 75% by mass of organic solvent (ethyl acetate)), manufactured by Toyo Ink Co., Ltd.) Wax dispersion 2: 240 additive (dispersion of PA wax and polyethylene (PE) wax (25% by mass of PA wax and PE wax, 75% by mass of organic solvent (ethyl acetate and methylcyclohexane)), manufactured by Toyo Ink Co., Ltd.)

[0103] <Adhesives> Dry laminating adhesive 1: An adhesive obtained by blending A-626 (manufactured by Mitsui Chemicals, Inc.) as the base agent, A-50 (manufactured by Mitsui Chemicals, Inc.) as the curing agent, and an organic solvent (ethyl acetate) in a mass ratio of 8:1:9.5, with the compositions of A-626 and A-50 being as follows: (A-626) 60% by mass of urethane resin precursor, 40% by mass of organic solvent (ethyl acetate) (A-50) 75% by mass of urethane resin precursor, 25% by mass of organic solvent (ethyl acetate) Dry laminating adhesive 2: An adhesive obtained by blending A-525 (manufactured by Mitsui Chemicals, Inc.) as the base agent, A-52 (manufactured by Mitsui Chemicals, Inc.) as the curing agent, and an organic solvent (ethyl acetate) in a mass ratio of 9:1:7.5, with the compositions of A-525 and A-52 being as follows: (A-525) 50% by mass of urethane resin precursor, 50% by mass of organic solvent (ethyl acetate) (A-52) 75% by mass of urethane resin precursor, 25% by mass of organic solvent (ethyl acetate) Solvent-free adhesive: aliphatic ester adhesive (product name: DIC Dry (a 2:1 blend of 2K-SF-900A and HA-930B), manufactured by DIC Graphics Corporation) Barrier adhesive: Maxieve C93T, M-100 (manufactured by Mitsubishi Gas Chemical Company, Inc.)

[0104] <Preparation of Packaging Film> (Example 1) First, a 20 μm thick oriented polypropylene (OPP) film was prepared as a substrate layer. Next, a 50 nm thick SiO ｘA film was formed as a gas barrier layer. Meanwhile, a resin composition for a coating layer (OP varnish) was prepared by adding an isocyanate-based curing agent 1 as an additive and ethyl acetate as an organic solvent to a polyurethane-based medium 1 as a base material. The polyurethane-based medium 1, the isocyanate-based curing agent 1, and the ethyl acetate were blended in a mass ratio of 100:3:35. An ink was also prepared by adding an isocyanate-based curing agent 1 as an additive and ethyl acetate as an organic solvent to a polyurethane-based ink 1 as a base material. The polyurethane-based ink 1, the isocyanate-based curing agent 1, and the ethyl acetate were blended in a mass ratio of 100:3:35. The ink was then applied to the surface of the substrate layer (the surface of the substrate layer opposite the sealant layer) and dried to form a 3 μm-thick ink layer. Subsequently, the resin composition for a coating layer was applied to the surface of the ink layer and dried to form a 1 μm-thick coating layer. Next, the dry laminating adhesive 1 was applied onto the gas barrier layer, and a 70 μm thick non-oriented polypropylene (CPP) film was attached thereto, and then the dry laminating adhesive 1 was dried. In this manner, a packaging film was obtained.

[0105] Comparative Example 1 A packaging film was obtained in the same manner as in Example 1, except that no additives were added when preparing the resin composition for the coating layer and the ink.

[0106] Example 2 A packaging film was obtained in the same manner as in Example 1, except that when preparing the resin composition for the coating layer, Polyurethane Medium 2 was used as the main ingredient instead of Polyurethane Medium 1, and Isocyanate Curing Agent 2, Wax Dispersion 1, and Wax Dispersion 2 were used as additives instead of Isocyanate Curing Agent 1, and when preparing the ink, Polyurethane Ink 2 was used as the main ingredient instead of Polyurethane Ink 1, and Isocyanate Curing Agent 2, Wax Dispersion 1, and Wax Dispersion 2 were used as additives instead of Isocyanate Curing Agent 1. For the resin composition for the coating layer, Polyurethane Medium 2, Isocyanate Curing Agent 2, Wax Dispersion 1, Wax Dispersion 2, and ethyl acetate as the organic solvent were blended in a mass ratio of 100:3:3:3:35. For the ink, polyurethane ink 2, isocyanate curing agent 2, wax dispersion 1, wax dispersion 2, and ethyl acetate as an organic solvent were blended in a mass ratio of 100:3:3:3:35.

[0107] Example 3 A packaging film was obtained in the same manner as in Example 2, except that when preparing the resin composition for the coating layer, isocyanate-based curing agent 3 was used as an additive instead of isocyanate-based curing agent 2. In this case, for the resin composition for the coating layer, polyurethane-based medium 2, isocyanate-based curing agent 3, wax dispersion 1, wax dispersion 2, and ethyl acetate as an organic solvent were blended in a mass ratio of 100:3:3:3:35.

[0108] Example 4 A packaging film was obtained in the same manner as in Example 2, except that an antiblocking agent (B inhibitor) was used instead of wax dispersion 1 as an additive when preparing the resin composition for the covering layer, and no additive was added when preparing the ink. For the resin composition for the covering layer, polyurethane medium 2, isocyanate curing agent 2, B inhibitor, wax dispersion 2, and ethyl acetate as an organic solvent were blended in a mass ratio of 100:3:3:3:35. For the ink, polyurethane ink 2 and ethyl acetate as an organic solvent were blended in a mass ratio of 100:35.

[0109] Comparative Example 2 A packaging film was obtained in the same manner as in Example 2, except that no additives were added when preparing the resin composition for the coating layer and the ink. For the resin composition for the coating layer, Polyurethane Medium 2 and ethyl acetate as the organic solvent were blended in a mass ratio of 100:35. For the ink, Polyurethane Ink 2 and ethyl acetate as the organic solvent were blended in a mass ratio of 100:35.

[0110] Comparative Example 3 A packaging film was obtained in the same manner as in Example 2, except that an ink layer was formed on the back side (sealant layer side) of the base layer using ink, a coating layer was formed on the ink layer using a resin composition for coating layer, and then a gas barrier layer was formed on the coating layer. For the resin composition for coating layer, polyurethane medium 2, isocyanate curing agent 2, wax dispersion 1, wax dispersion 2, and ethyl acetate as an organic solvent were blended in a mass ratio of 100:3:3:3:35. For the ink, polyurethane ink 2, isocyanate curing agent 2, wax dispersion 1, wax dispersion 2, and ethyl acetate as an organic solvent were blended in a mass ratio of 100:3:3:3:35.

[0111] (Example 5) A packaging film was obtained in the same manner as in Example 2, except that when preparing the resin composition for the coating layer, a polyamideimide resin solution was used as the main agent instead of polyurethane medium 2, no additives were added, and the thickness of the coating layer was changed from 1 μm to 0.5 μm.

[0112] Example 6 A packaging film was obtained in the same manner as in Example 2, except that the dry laminating adhesive 2 was used instead of the dry laminating adhesive 1 as the material for forming the adhesive layer.

[0113] (Example 7) A packaging film was obtained in the same manner as in Example 2, except that a CPP film containing a white pigment (white CPP) (FCMK-VW, manufactured by Futamura Chemical Co., Ltd.) was used as the material for forming the sealant layer instead of the unstretched polypropylene (CPP) film.

[0114] Example 8 A packaging film was obtained in the same manner as in Example 2, except that a solventless adhesive was used instead of the dry laminating adhesive 1 as the material for forming the adhesive layer.

[0115] Example 9 A packaging film was obtained in the same manner as in Example 2, except that a barrier adhesive was used instead of the dry laminating adhesive 1 as the material for forming the adhesive layer.

[0116] Example 10 A packaging film was obtained in the same manner as in Example 2, except that the gas barrier layer was changed from SiOx to aluminum (Al).

[0117] Example 11 A packaging film was obtained in the same manner as in Example 2, except that a 12 μm thick PET film was used as the base layer instead of the 20 μm thick OPP film.

[0118] (Example 12) A packaging film was obtained in the same manner as in Example 2, except that a 12 μm thick PET film was used as the base layer instead of the 20 μm thick OPP film, dry laminating adhesive 1 was applied onto the gas barrier layer to attach a PET film (12 μm thick) as an intermediate layer, and then dry laminating adhesive 1 was applied onto the intermediate layer to attach a CPP film as a sealant layer.

[0119] <Evaluation of Packaging Film> (1) Ink Adhesion Packaging films of Examples 1 to 12 and Comparative Examples 1 and 2 were prepared as test specimens. Then, for each test specimen before and after retort treatment (121°C, 30 minutes) using a hot water storage retort device, a 15 mm wide, 100 mm long piece of Cellotape (registered trademark) was attached to the surface of the coating layer. After 10 seconds, the Cellotape was peeled off and the total area of ​​the deposits (ink) on the Cellotape surface was determined. Then, based on the following criteria, the ink adhesion was evaluated according to the total area of ​​the deposits on the Cellotape surface. The results are shown in Tables 1 to 3. Note that ink adhesion is an index of the degree of suppression of peeling of the ink layer. (Criteria) ⊚: Total area of ​​deposits is 150 mm ２ Less than ○: The total area of ​​the deposits is 150 mm ２ More than 300 mm ２Less than ×...total area of ​​deposits is 300 mm ２ End

[0120] (2) Lamination Strength: Strip-shaped test pieces measuring 15 mm wide and 100 mm long were cut from the packaging films of Examples 1 to 12 and Comparative Examples 1 to 3. The laminate strength of the test pieces was measured in accordance with JIS Z-1707 before and after retort treatment (121°C, 30 minutes) using a hot water storage retort apparatus. Specifically, the CPP film and the remaining portion of the test piece were each peeled in opposite directions at a rate of 300 mm / min using a Tensilon tensile tester (product name "Tensilon RTC-1250," manufactured by Orientec Co., Ltd.), and the strength required for peeling (unit: N / 15 mm) was measured as the laminate strength. Evaluation was then performed according to the following criteria according to the laminate strength. This evaluation evaluated the degree of delamination suppression of the packaging film. The results are shown in Tables 1 to 3. (Criteria) 〇: Laminate strength is 2N / 15mm or more ×: Laminate strength is less than 2N / 15mm

[0121]

[0122]

[0123]

[0124] From the results shown in Tables 1 to 3, all of the packaging films of the Examples had ink adhesion of "◎" or "◯" and lamination strength of "◯" even after retort treatment. In contrast, the packaging films of the Comparative Examples had ink adhesion of "×" or lamination strength of "×" after retort treatment. From the above, it was confirmed that the packaging film of the present disclosure can suppress peeling and delamination of the ink layer even after retort treatment.

[0125] 10...coating layer, 20...ink layer, 30...substrate layer, 40...anchor coat layer, 50...gas barrier layer, 60...adhesive layer, 70...sealant layer, 100...packaging film, 200...packaging bag, 300...packaged product, C...contents

Claims

1. A packaging film comprising an ink layer, a substrate layer, an adhesive layer, and a sealant layer in this order, the ink layer being coated with a coating layer, the coating layer being obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent, or a resin composition for a coating layer containing a polyamideimide resin, and the ink layer being obtained using an ink containing a polyurethane resin.

2. The packaging film according to claim 1, wherein the coating layer is obtained using a resin composition for the coating layer, which comprises a polyurethane resin and a curing agent.

3. The packaging film of claim 1, wherein the ink further comprises a curing agent.

4. The packaging film according to claim 1, wherein the curing agent contained in the resin composition for the coating layer includes an isocyanate-based curing agent.

5. The packaging film according to claim 4, wherein the resin composition for the coating layer further contains a wax.

6. The packaging film of claim 5, wherein the waxes include polyamide waxes and polyolefin waxes.

7. The packaging film according to claim 3, wherein the curing agent contained in the ink includes an isocyanate-based curing agent.

8. The packaging film according to claim 1, wherein the coating layer is obtained using a resin composition for a coating layer comprising a polyurethane resin and a curing agent, the curing agent contained in the resin composition for a coating layer comprises an isocyanate-based curing agent, the resin composition for a coating layer further comprises a wax, the ink further comprises a curing agent, and the curing agent contained in the ink comprises an isocyanate-based curing agent.

9. The packaging film of claim 8, wherein the waxes include polyamide waxes and polyolefin waxes.

10. The packaging film according to claim 1, further comprising a gas barrier layer between the adhesive layer and the substrate layer.

11. The packaging film of claim 1, wherein the substrate layer and the sealant layer comprise a polyolefin resin.

12. A packaging bag comprising the packaging film according to any one of claims 1 to 11.

13. A packaging product comprising the packaging bag according to claim 12 and contents contained within the packaging bag.

Images