Packaging film, packaging bag, and packaged product

Abstract

To provide a packaging film capable of suppressing the peeling and discoloration of an ink layer even if retort treatment is performed, a packaging bag and a packaged product.SOLUTION: A packaging film comprising an ink layer, a paper substrate and a sealant layer in this order, wherein the ink layer is covered with a covering layer, the covering layer is obtained by using a resin composition for a covering layer comprising a polyurethane resin and a curing agent, and the ink layer is obtained by using an ink comprising a polyurethane resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, the environmental pollution caused by microplastics, as seen in the problem of marine plastic waste, has become a serious issue. As a result, there has been a growing trend to eliminate plastic and reduce the use of plastic products, and demand for packaging films containing paper substrates is increasing. In such packaging films, an ink layer displaying letters, pictures, etc. may be provided on the paper substrate. For example, Patent Document 1 below discloses a sheet used for a storage container, which comprises a varnish layer, an ink layer, a paper substrate, and a heat seal layer in this order, the varnish layer and the ink layer containing nitrocellulose and a synthetic resin, and the ink layer further containing a pigment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-120374 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the sheet described in Patent Document 1 still has room for improvement in terms of preventing peeling and discoloration of the ink layer when subjected to 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 and discoloration of an ink layer even when subjected to retort treatment. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present disclosure provides a packaging film comprising, in this order, a coating layer, an ink layer, a paper base material, and a sealant layer, wherein the coating layer is obtained using a resin composition for the coating layer containing a polyurethane resin and a curing agent, and the ink layer is obtained using an ink containing a polyurethane resin. The packaging film can prevent peeling and discoloration of the ink layer even when subjected to retort treatment.

[0007] The inventors of the present disclosure speculate that the reason why the above effects are obtained is as follows. That is, by including a polyurethane resin in the resin composition for the coating layer and the ink, both the coating layer and the ink layer can have high hot water resistance. In particular, by including a curing agent in the resin composition for the coating layer in addition to the polyurethane resin, when the resin composition for the coating layer is used to obtain a coating layer, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the urethane resin and enabling the coating layer to have high heat resistance. Therefore, even when the packaging film is retorted, the coating layer is less susceptible to heat degradation, 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 paper substrate is suppressed, and peeling of the ink layer is suppressed. Furthermore, because polyurethane resins have relatively low hydrophilicity, the ink layer is protected from hot water by the highly heat-resistant coating layer, thereby suppressing penetration of hot water into the ink layer and suppressing deterioration of the ink layer, thereby suppressing discoloration of the ink layer. The inventors of the present disclosure speculate that the above effects are achieved for the above reasons.

[0008] In the packaging film, it is preferable that the ink further contains a curing agent. In this case, when an ink layer is obtained using ink, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the urethane 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, deterioration of the exposed portion of the ink layer is suppressed after retorting the packaging film. As a result, peeling of the ink layer from the paper substrate can be further suppressed.

[0009] In the packaging film, the curing agent contained in the resin composition for the covering layer may include an isocyanate-based curing agent. 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 paper substrate is effectively suppressed, and peeling of the ink layer is effectively suppressed.

[0010] In the packaging film, the curing agent contained in the ink preferably includes an isocyanate-based curing agent. In this case, the cohesive force of the ink layer can be effectively increased, and therefore, even if the ink layer is exposed at the end face of the packaging film, deterioration of the exposed part of the ink layer is effectively suppressed after the packaging film is retorted, and peeling of the ink layer from the paper substrate can be more effectively suppressed.

[0011] The packaging film preferably further comprises a gas barrier layer between the adhesive layer and the paper substrate. In this case, the gas barrier properties of the packaging film are further improved.

[0012] In the packaging film, it is preferable that the total thickness of the coating layer and the ink layer is 10 μm or less. In this case, the unevenness of the surface of the paper substrate also creates an uneven surface for the coating layer, compared to when the total thickness of the coating layer and ink layer exceeds 10 μm. As a result, the texture of the paper substrate remains in the packaging film, and blocking between the coating layer and other packaging films is less likely to occur when the packaging film is wound up.

[0013] In the packaging film, it is preferable that the coating layer has a thickness of 0.5 to 5 μm, and the ink layer has a thickness of 0.5 to 5 μm. In this case, the hot water resistance of the coating layer and the ink layer can be improved, and the recyclability can also be improved.

[0014] In the packaging film, it is preferable that the ink contains a pigment, and the content of the pigment in the coating layer is lower than the content of the pigment in the ink layer. In this case, the mechanical strength of the coating layer is further improved, and the transparency of the coating layer is higher than that of the ink layer, improving the visibility of the ink layer.

[0015] 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 and discoloration of the ink layer even when subjected to retort treatment. Therefore, the packaging bag can suppress peeling and discoloration of the ink layer even when subjected to retort treatment.

[0016] Yet another aspect of the present disclosure provides a packaging product including the packaging bag described above and contents contained within the packaging bag. The packaged product includes the above-described packaging film, and the packaging bag can suppress peeling and discoloration of the ink layer even when subjected to retort treatment. Therefore, the packaged product can suppress peeling and discoloration of the ink layer even when subjected to retort treatment. Therefore, the life of the packaged product can be extended. [Effects of the Invention]

[0017] According to the present disclosure, a packaging film, a packaging bag, and a packaged product are provided that can suppress peeling and discoloration of the ink layer even when subjected to retort treatment. [Brief explanation of the drawings]

[0018] [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

[0019] Hereinafter, embodiments of the present disclosure will be described in detail, but the present invention is not limited to the following embodiments.

[0020] <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.

[0021] The packaging film 100 shown in FIG. 1 comprises a coating layer 10, an ink layer 20, a paper substrate 30, an adhesive layer 60, and a sealant layer 70 in this order. The covering layer 10 is obtained using a resin composition for the covering layer that contains a polyurethane resin and a curing agent. 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 from the paper substrate 30 side between the paper substrate 30 and the sealant layer 70. The packaging film 100 may also include an intermediate layer (not shown) between the paper substrate 30 and the sealant layer 70. The adhesive layer 60 may also be omitted. The packaging film 100 can prevent the ink layer 20 from peeling and discoloring even when subjected to retort treatment.

[0022] The coating layer 10, ink layer 20, paper substrate 30, anchor coat layer 40, gas barrier layer 50, adhesive layer 60, sealant layer 70 and intermediate layer will be described in detail below.

[0023] (1) Covering layer The coating layer 10 is a layer that coats the ink layer 20. The coating layer 10 is provided on the ink layer 20 on the side opposite to the sealant layer 70. The covering layer 10 is obtained using a resin composition for a covering layer that contains a polyurethane resin as a binder resin and a curing agent.

[0024] The content of the polyurethane resin in the solid content contained in the resin composition for the covering 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 polyurethane resin in the solid content contained in the resin composition for the covering layer may be 99 mass % or less, taking into consideration the use of additives.

[0025] By including a curing agent in the resin composition for the coating layer, when a coating layer is obtained using the resin composition for the coating layer, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the urethane resin and enabling the coating layer 10 to 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 sufficiently protected from hot water by the coating layer 10, thereby suppressing deterioration of the ink layer 20. Furthermore, because the coating layer 10 can have high heat resistance, when the packaging film 100 is used and heat-sealed at a high temperature of 200°C or higher using a seal bar to form a bag, melting of the ink layer 20 can be suppressed, and it is also possible to suppress peeling of at least a portion of the ink layer 20 by the seal bar (ink removal). Examples of the curing agent include an isocyanate-based curing agent. Among these, an isocyanate-based curing agent is preferable. 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 paper substrate 30 is effectively suppressed, and peeling of the ink layer 20 is effectively suppressed. Examples of isocyanate-based curing agents include materials containing hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), which may be used alone or in combination.

[0026] 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.

[0027] The resin composition for the coating layer may further contain 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.

[0028] The wax content in the solid content contained in the resin composition for the covering layer is not particularly limited, and may be, for example, 0 mass % or more, 1 mass % or more, 3 mass % or more, or 5 mass % or more. The wax content in the solid content contained in the resin composition for the covering layer may be 10% by mass or less.

[0029] The pigment content in the solid content contained in the resin composition for the coating layer is preferably smaller than the pigment content in the ink used to obtain the ink layer 20. In this case, the mechanical strength of the coating layer 10 is further improved. In addition, the transparency of the coating layer 10 is higher than that of the ink layer 20, and the visibility of the ink layer 20 is improved. Examples of pigments contained in the resin composition for the coating 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.

[0030] 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 greater.

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

[0033] Examples of methods for forming the coating layer 10 include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing.

[0034] The thickness of the coating layer 10 is not particularly limited and may be adjusted as needed, but 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 improving the hot water resistance of the ink layer 20. Furthermore, 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 surface roughness of the coating layer 10 is not particularly limited, but is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less. The surface roughness of the ink layer 20 may be 5 μm or less, 4 μm or less, or 3 μm or less. The surface roughness of the coating layer 10 refers to the arithmetic mean roughness (Ra) and is measured in accordance with JIS B 0601:2013. The amount of the resin composition for the coating layer that forms the coating layer 10 is not particularly limited. However, in order to make the surface roughness of the coating layer 10 5 μm or less, the amount of the resin composition for the coating layer 10 that is applied is, for example, 0.1 g / m 2 It is sufficient to set the value to 0.3 g / m or more. 2 or more than 0.5g / m 2 It may be more than that. The coating amount of the resin composition for the coating layer that forms the coating layer 10 is, for example, 7 g / m 2 in order to make the surface roughness of the coating layer 10 0.1 μm or more. 2 It is sufficient to set it to 5g / m 2 Less than or equal to 4g / m 2 It may be the following:

[0035] (2) Ink layer The ink layer 20 is a layer that displays letters, pictures, symbols, and combinations thereof. The ink layer 20 is provided on the side of the paper substrate 30 opposite the sealant layer 70, between the paper substrate 30 and the coating layer 10. By providing the ink layer 20 on the side of the paper substrate 30 opposite the sealant layer 70, the ink layer 20 is not positioned adjacent to the adhesive layer 60, and absorption of the components in the adhesive layer 60 by the ink layer 20 is suppressed, so that the amount of adhesive, etc. used when obtaining the adhesive layer 60 can be reduced, thereby reducing the environmental impact. The ink layer 20 is obtained by using an ink containing a polyurethane resin as a binder resin.

[0036] The content of polyurethane resin in the solid content contained in 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 contained in the ink may be 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0037] The ink layer 20 may or may not further contain a curing agent, but preferably does. In this case, the curing agent promotes the crosslinking reaction (high molecular weight) of the polyurethane resin, increasing the molecular weight of the urethane resin. As a result, the cohesive force of the ink layer 20 itself can be increased, making the ink layer 20 less likely to be destroyed. 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 edge surface of the packaging film 100, deterioration of the exposed portion of the ink layer 20 is suppressed after retort processing of the packaging film 100. As a result, peeling of the ink layer 20 from the paper substrate 30 can be further suppressed. The curing agent is preferably an isocyanate-based curing agent, which can effectively increase the cohesive force of the ink layer 20. Therefore, even if the ink layer 20 is exposed at the end surface of the packaging film 100, deterioration of the exposed portion of the ink layer 20 is effectively suppressed after the packaging film 100 is retorted, and peeling of the ink layer 20 from the paper substrate 30 can be more effectively suppressed. Examples of isocyanate-based curing agents include materials containing hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), which may be used alone or in combination. 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.

[0038] The ink may further contain wax, which further improves adhesion of the coating layer 10 to the ink layer 20. Examples of waxes include polyamide wax and polyolefin wax. These may be used alone or in combination. The wax content in the solid content of the ink is not particularly limited, and may be, for example, 0 mass %, 1 mass % or more, 3 mass % or more, or 5 mass % or more. The wax content in the solid content of the ink may be 10% by mass or less.

[0039] The ink contains a pigment. Examples of the pigment 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 content of the pigment 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 content of the pigment in the solid content of the ink may be 90% by mass or less.

[0040] The ink may contain a plasticizer, a drying agent, a stabilizer, and the like, as required.

[0041] The ink contains a solvent. The solvent may be, for example, 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.

[0042] The ink may or may not further contain a biomass component, but from the viewpoint of reducing the environmental impact, it is preferable that the ink further contains a biomass component. Here, the biomass component refers to a component 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 base layer 30, the ink layer 20 is composed of a single layer. When multicolor printing is performed on the base layer 30, the ink layer 20 is composed of multiple layers. In this case, for example, a first ink layer may be formed by performing solid white printing on the entire surface of the base layer 30, and a second ink layer comprising letters, pictures, etc. may be formed on the first ink layer. In addition, a layer of ink containing a black pigment such as black carbon or metal powder may be provided for light blocking. The ink layer 20 may be provided only on a part of the surface of the base material layer 30, or may be provided on the entire surface of the base material layer 30.

[0043] The ink layer 20 can be formed by a conventionally known printing method such as gravure printing, offset printing, or flexographic printing.

[0044] The thickness of the ink layer 20 is not particularly limited and may be adjusted as needed, but 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 concealing the color of the paper substrate 30. Furthermore, 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 amount of ink to be applied to form the ink layer 20 is not particularly limited. When forming the ink layer 20, the amount of ink to be applied is, for example, 0.1 g / m 2 It is sufficient to set the value to 0.3 g / m or more. 2 or more than 0.5g / m 2 The ink application amount may be 7 g / m or more. 2 Less than 5 g / m 2 Less than 4g / m, more preferably 2 The following is the result. The total thickness T of the coating layer 10 and the ink layer 20 is not particularly limited, but is preferably 10 μm or less, more preferably 8 μm or less, and particularly preferably 6 μm or less. When the total thickness T is 10 μm or less, the unevenness of the surface of the paper base material 30 also creates unevenness on the surface of the covering layer 10, compared to when the total thickness T exceeds 10 μm. As a result, the texture of the paper base material 30 remains in the packaging film 100, and blocking between the covering layer 10 and other packaging films is less likely to occur when the packaging film 100 is wound up. From the viewpoint of concealing the color of the paper substrate 30, the total thickness T is preferably 0.5 μm or more, more preferably 0.8 μm or more, and particularly preferably 1 μm or more.

[0045] (3)Paper base material The paper substrate 30 is a substrate containing paper, and paper refers to a material containing plant-derived pulp as a main component, where the main component refers to a component containing plant-derived pulp at 50% by mass or more. By including the paper substrate 30 in the packaging film 100, it is possible to contribute to reducing the amount of plastic material used. Specific examples of the paper substrate 30 include fine paper, special fine paper, coated paper, art paper, cast coated paper, construction paper, kraft paper, and glassine paper. The paper substrate 30 may or may not further have a coating layer at least on the side of the paper facing the sealant layer 70. If the paper substrate 30 further has a coating layer, it can prevent the anchor coat layer 40 from penetrating into the paper and also serve 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 contain a binder resin and, if necessary, a filler. Examples of the binder resin include various copolymers such as styrene-butadiene copolymer, styrene-acrylic copolymer, and ethylene-vinyl acetate copolymer, polyvinyl alcohol resin, and cellulose resin. Examples of the filler include kaolin, calcium carbonate, talc, and mica. If the paper substrate does not have a coating layer, discoloration of the paper due to retort treatment of the packaging film 100 will be less likely to occur. The paper substrate 30 may be made up of a single layer or multiple layers.

[0046] The thickness of the paper substrate 30 is not particularly limited. From the viewpoint of reducing materials to reduce environmental impact and obtaining excellent heat resistance, impact resistance, and gas barrier properties, the thickness of the paper substrate 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 reducing environmental impact, the thickness of the paper substrate 30 may be 100 μm or less, 60 μm or less, or 50 μm or less. There are no particular restrictions on the basis weight of the paper substrate 30. From the viewpoint of reducing materials to reduce the environmental impact and from the viewpoint of obtaining excellent heat resistance, impact resistance, and gas barrier properties, the basis weight of the paper substrate 30 is set to 40 g / m 2More than 60g / m 2 or more than 80g / m 2 The basis weight of the paper substrate 30 is 160 g / m from the viewpoint of reducing the amount of plastic used and reducing the environmental load. 2 Below 140g / m 2 or less, or 120 g / m 2 The following is fine. There are no particular limitations on the thickness of the paper substrate 30. From the viewpoint of reducing materials to reduce environmental impact and obtaining excellent heat resistance, impact resistance, and gas barrier properties, the thickness of the paper substrate 30 may be 50 μm or more, 75 μm or more, or 100 μm or more. Furthermore, from the viewpoint of reducing the amount of plastic used and thereby reducing environmental impact, the thickness of the paper substrate 30 may be 200 μm or less, 170 μm or less, or 150 μm or less.

[0047] (4) Anchor coat layer The anchor coat layer 40 is a layer for further improving the adhesion between the paper substrate 30 and the gas barrier layer 50 , and is provided between the paper substrate 30 and the gas barrier layer 50 .

[0048] The material constituting the anchor coat layer 40 is not particularly limited as long as it can improve the adhesion between the paper substrate 30 and the gas barrier layer 50, but it is preferable that it contains a polyurethane resin. 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.

[0049] The thickness of the anchor coat layer 40 is not particularly limited, but from the viewpoint of improving adhesion between the paper substrate 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 exceeds 2000 nm. Furthermore, from the viewpoint of recyclability, the thickness of the anchor coat layer 40 is more preferably 1000 nm or less.

[0050] (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.

[0051] The gas barrier layer 50 includes a vapor-deposited layer. The gas barrier layer 50 may further include a gas barrier coating layer on the vapor-deposited layer.

[0052] (deposited layer) The vapor-deposited layer is, for example, a vapor-deposited layer of a metal or a vapor-deposited layer of a metal oxide. The metal constituting the metal vapor deposition layer or metal oxide vapor deposition layer can be at least one metal selected from the group consisting of Si, Al, Mg, Sn, Ti, and In. The metal oxide is preferably silicon oxide (SiOx), aluminum oxide (AlOx), or a mixture 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.

[0053] 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.

[0054] The thickness of the vapor-deposited layer is preferably 300 nm or less. In this case, the deterioration of the gas barrier property can be more effectively suppressed even after retort treatment of the packaging film 100, 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.

[0055] (Gas barrier coating layer) The gas barrier coating layer is a layer that covers the vapor deposition layer, improving the gas barrier properties of the packaging film 100. Furthermore, the gas barrier coating layer can prevent the gas barrier properties of the packaging film 100 from decreasing even if the vapor deposition layer is damaged, such as by cracks.

[0056] The gas barrier coating layer is formed, for example, from a cured 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.

[0057] 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.

[0058] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], etc. Tetraethoxysilane (TEOS) and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

[0059] 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, 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 retort 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 retort treatment.

[0060] 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.

[0061] The gas barrier coating layer can be formed by coating a composition for forming a gas barrier coating layer onto a vapor deposition 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 (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.

[0062] The thickness of the gas barrier coating layer may be 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.

[0063] (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").

[0064] Examples of adhesives include known adhesives such as urethane adhesives, polyester adhesives, polyamide adhesives, epoxy adhesives, and isocyanate adhesives.

[0065] 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.

[0066] The adhesive may be either an adhesive containing a solvent or an adhesive not containing a solvent (solvent-free adhesive), but from the viewpoint of reducing the environmental load, a solvent-free adhesive is preferred. The adhesive may or may not have gas barrier properties, but from the viewpoint of improving the gas barrier properties of the packaging film 100, it is preferable that the adhesive have gas barrier properties.

[0067] The adhesive resin is a heat-sealable 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 low-density polyethylene, polypropylene, ethylene-propylene copolymer, methylpentene polymer, acid-modified polyolefin resins obtained by modifying polyolefin resins such as polyethylene or polypropylene with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and the like can be used. 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, 5 μm or less, or 3 μm or less.

[0068] (7) Sealant layer The sealant layer 70 may be made of a polyolefin resin film, a polyester resin film, or the like.

[0069] The polyolefin resin film is preferably used in terms of sealing suitability, etc., and contains a polyolefin resin, such as polyethylene or 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, etc. Examples of α-olefin include ethylene, 1-butene, etc. Among the polyolefin resins, polypropylene is preferred from the viewpoint 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.

[0070] Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0071] The polyolefin resin and polyester resin may be a biomass-derived resin or a mechanically recycled or chemically recycled resin.

[0072] 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. The sealant layer 70 may be colored. When the sealant layer 70 is white, the print can be made to look clearer. When the sealant layer 70 contains a light-blocking pigment, the sealant layer 70 can function as a light-blocking layer.

[0073] The sealant layer 70 may be composed of a single layer or multiple layers.

[0074] The sealant layer 70 may be a stretched film or a non-stretched film, but from the viewpoint of heat sealability, a non-stretched film is preferred.

[0075] 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, and more preferably 80 μm or less.

[0076] (8) Middle class The intermediate layer is a layer provided between the paper substrate 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 may be disposed between the gas barrier layer 50 and the paper substrate 30. The intermediate layer can be a film 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 copolymers, etc. Examples of α-olefins include ethylene, 1-butene, etc. Among the polyolefin resins, polypropylene is preferred from the viewpoint 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.

[0077] The resin material may be a non-recycled resin, a recycled resin, or a mixture thereof. When using recycled resin for the intermediate layer, which does not come into contact with the contents, it is acceptable to use material recycled resin (material recycled resin), but it is preferable to use chemically recycled resin (chemically recycled resin) from the standpoints of hygiene and quality. 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, but 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 may be composed of a mixture of multiple types of chemically recycled resins. The material recycled resin may be composed of a single material recycled resin, or may be composed of a mixture of multiple types of material recycled resins.

[0078] The intermediate layer may be composed of a single layer or multiple layers.

[0079] 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 required. When the intermediate layer contains a light-shielding pigment, the intermediate layer can function as a light-shielding layer.

[0080] 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.

[0081] The intermediate layer 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, the tearability and heat resistance of the packaging film 100 can be improved. When the intermediate layer is a biaxially stretched film, the mechanical strength and dimensional stability of the packaging film 100 can be improved.

[0082] 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.

[0083] 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.

[0084] <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 duplicated explanations will be omitted. As shown in Fig. 2, a packaged product 300 includes a packaging bag 200 and a content C contained 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.

[0085] This packaged product 300 includes a packaging bag 200, which can suppress peeling and discoloration of the ink layer 20 even when subjected to retort treatment. Therefore, the packaged product 300 can suppress peeling and discoloration of the ink layer 20 even when subjected to retort treatment. Therefore, the life of the packaged product 300 can be extended.

[0086] 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.

[0087] Examples of the packaging bag 200 include a three-sided pouch, a four-sided pouch, a standing pouch, a gusset pouch, and a pillow package. The packaging bag 200 may further have a spout or a zipper depending on the application.

[0088] The contents C are not particularly limited, and examples of the contents C include food, liquid, medicine, and electronic parts.

[0089] <Summary of this disclosure> The outline of the present disclosure is as follows. [1] An ink layer, a paper substrate, and a sealant layer in this order; the ink layer is coated with a coating layer, the coating layer is obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent, A packaging film, wherein the ink layer is obtained using an ink containing a polyurethane resin. [2] The packaging film according to [1], wherein the ink further contains a curing agent. [3] The packaging film according to [1] or [2], wherein the curing agent contained in the resin composition for the coating layer includes an isocyanate-based curing agent. [4] The packaging film according to [2], wherein the curing agent contained in the ink includes an isocyanate-based curing agent. [5] The packaging film according to any one of [1] to [4], further comprising a gas barrier layer between the sealant layer and the paper substrate. [6] The packaging film according to any one of [1] to [5], wherein the total thickness of the coating layer and the ink layer is 10 μm or less. [7] The packaging film according to any one of [1] to [6], wherein the coating layer has a thickness of 0.5 to 5 μm, and the ink layer has a thickness of 0.5 to 5 μm. [8] The ink contains a pigment, The packaging film according to any one of [1] to [7], wherein the content of the pigment in the coating layer is lower than the content of the pigment in the ink layer. [9] A packaging bag comprising the packaging film according to any one of [1] to [8].

[10] A packaging product comprising the packaging bag described in [9] and contents contained in the packaging bag. [Example]

[0090] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0091] In the examples and comparative examples, the following base materials and additives were used. <Main component of resin composition 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: 20% by mass of polyurethane resin, 80% by mass of organic solvent (propyl acetate and ethyl acetate)) Nitrocellulose medium: Ecocolor HR OP Varnish, manufactured by Toyo Ink Co., Ltd.

[0092] <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) Nitrocellulose ink: Ecocolor HR 170 Red, manufactured by Toyo Ink Co., Ltd.

[0093] <Additives> Isocyanate-based curing agent 1: Lamiol R curing agent (a mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)) 1% by mass, synthetic resin 34% by mass, organic solvent (ethyl acetate) 65% by mass), manufactured by Sakata Inx Corporation Isocyanate-based curing agent 2: SP curing agent (hexamethylene diisocyanate (HDI) 1% by mass, synthetic resin 49% by mass, organic solvent (ethyl acetate) 50% by mass), manufactured by Toyo Ink Co., Ltd. Anti-blocking agent (B inhibitor): Silica dispersion (25% by weight of silica, 15% by weight of synthetic resin, 60% by weight of organic solvent (ethyl acetate and isopropyl alcohol), manufactured by Toyo Ink Co., Ltd.) Wax dispersion 1:280 additive (polyamide (PA) wax dispersion (25% by weight of polyamide (PA) wax, 75% by weight of organic solvent (ethyl acetate)), manufactured by Toyo Ink Co., Ltd.) Wax Dispersion 2:240 Additive (PA wax and polyethylene (PE) wax dispersion (PA wax and PE wax 25% by mass, organic solvent (ethyl acetate) 75% by mass), manufactured by Toyo Ink Co., Ltd.)

[0094] <Adhesive> Dry laminating adhesive 1: This adhesive is made 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. The compositions of A-626 and A-50 are 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: This adhesive is made 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. The compositions of A-525 and A-52 are 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)

[0095] <Production of packaging film> Example 1 First, as the paper base material, a basis weight of 70 g / m 2 Heat-resistant water-resistant paper (MEP-P, manufactured by KJ Specialty Paper Co., Ltd.) was prepared. Next, a resin composition for a coating layer (OP varnish) was prepared by adding an isocyanate curing agent 1 as an additive 1 and ethyl acetate as an organic solvent to a polyurethane medium 1 as a base resin. At this time, the polyurethane medium 1, additive 1, and ethyl acetate were mixed in a mass ratio of 100:3:35. In addition, ink was prepared by adding isocyanate-based curing agent 1 as additive 1 and ethyl acetate as organic solvent to polyurethane-based ink 1 as the base material. At this time, polyurethane-based medium 1, additive 1, and ethyl acetate were mixed in a mass ratio of 100:3:35. The ink was then applied to the surface of the paper substrate and dried to form an ink layer with a thickness of 3 μm. Subsequently, a resin composition for a coating layer was applied to the surface of the ink layer and dried to form a coating layer having a thickness of 1 μm. On the other hand, an alumina-deposited PET film with a thickness of 12 μm was prepared. Next, the adhesive 1 for dry lamination was applied to the back surface of the paper substrate (the surface on which no ink layer was formed), and the PET film of the alumina vapor-deposited PET film was attached to the adhesive 1 for dry lamination. Next, the adhesive 1 for dry lamination was applied to the surface of the alumina side of the alumina-deposited PET film, and a 70 μm-thick unstretched polypropylene (CPP) film was attached to the adhesive 1 for dry lamination. In this way, a packaging film was obtained.

[0096] (Comparative Example 1) A packaging film was obtained in the same manner as in Example 1, except that additive 1 was not added to the base resin when preparing the resin composition for the coating layer and the ink.

[0097] (Comparative Example 2) When preparing the resin composition for the coating layer, a nitrocellulose-based medium was used as the main agent instead of the polyurethane-based medium 1, and additive 1 was not added. When preparing the ink, a nitrocellulose-based ink was used as the main agent instead of the polyurethane-based ink 1, and additive 1 was not added. A packaging film was obtained in the same manner as in Example 1, except that

[0098] 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 instead of polyurethane medium 1 as the main ingredient, and additives were added as additives, such as additive 1 (isocyanate-based curing agent 2), additive 2 (anti-blocking agent), and additive 3 (wax dispersion 2), instead of additive 1 (isocyanate-based curing agent 1). When preparing the ink, polyurethane ink 2 was used instead of polyurethane ink 1 as the main ingredient, and additives were added as additives, such as additive 1 (isocyanate-based curing agent 2), additive 2 (B-inhibitor), and additive 3 (wax dispersion 2), instead of additive 1 (isocyanate-based curing agent 1). For the resin composition for the coating layer, polyurethane medium 2, additive 1, additive 2, additive 3, and ethyl acetate were mixed in a mass ratio of 100:3:3:3:35. For the ink, polyurethane medium 2, additive 1, additive 2, additive 3, and ethyl acetate were mixed in a mass ratio of 100:3:3:3:35.

[0099] Example 3 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 instead of polyurethane medium 1 as the main ingredient, and additives 1 (isocyanate-based curing agent 2), additive 2 (wax dispersion 1), and additive 3 (wax dispersion 2) were used instead of additive 1 (isocyanate-based curing agent 1), and when preparing the ink, polyurethane ink 2 was used instead of polyurethane ink 1 as the main ingredient, and additives 1 (isocyanate-based curing agent 2), additive 2 (wax dispersion 1), and additive 3 (wax dispersion 2) were used instead of additive 1 (isocyanate-based curing agent 1). In this case, for the resin composition for the covering layer, polyurethane medium 2, additive 1, additive 2, additive 3, and ethyl acetate were blended in a mass ratio of 100:3:3:3:35. The content of polyurethane medium 2 in the resin composition for the covering layer was 91 mass%, and the contents of isocyanate curing agent 2, wax dispersion 1, and wax dispersion 2 were 3 mass%, 3 mass%, and 3 mass%, respectively. For the ink, polyurethane medium 2, additive 1, additive 2, additive 3, and ethyl acetate were blended in a mass ratio of 100:3:3:3:35.

[0100] Example 4 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 instead of polyurethane medium 1 as the main ingredient, and additive 1 (isocyanate-based curing agent 3), additive 2 (wax dispersion 1), and additive 3 (wax dispersion 2) were used instead of additive 1 (isocyanate-based curing agent 1) as the additives, and when preparing the ink, polyurethane ink 2 was used instead of polyurethane ink 1 as the main ingredient, and additive 1 (isocyanate-based curing agent 2), additive 2 (wax dispersion 1), and additive 3 (wax dispersion 2) were used instead of additive 1 (isocyanate-based curing agent 1) as the additives. For the resin composition for the coating layer, polyurethane medium 2, additive 1, additive 2, additive 3, and ethyl acetate were mixed in a mass ratio of 100:3:3:3:35. For the ink, polyurethane medium 2, additive 1, additive 2, additive 3, and ethyl acetate were mixed in a mass ratio of 100:3:3:3:35.

[0101] Example 5 A packaging film was obtained in the same manner as in Example 1, except that the dry laminating adhesive 1 was replaced with the dry laminating adhesive 2 as the adhesive.

[0102] Example 6 A packaging film was obtained in the same manner as in Example 1, except that a solventless adhesive was used instead of the dry laminating adhesive 1 as the adhesive.

[0103] <Evaluation of packaging film> (1)Water resistance First, test pieces of 100 mm x 100 mm were cut from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2, and the test pieces were immersed in hot water in a hot water storage retort apparatus and subjected to retort treatment at 121°C for 30 minutes. At this time, the presence or absence of ink elution in hot water was visually confirmed as an index of water resistance and evaluated based on the following criteria. The results are shown in Tables 1 and 2. In Tables 1 and 2, "○" and "×" are based on the following criteria. (standard) ○...No ink elution in hot water was confirmed. × Ink elution in hot water was confirmed

[0104] (2) Adhesion Test pieces were prepared from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2. A 15 mm wide, 100 mm long piece of Scotch tape (registered trademark) was attached to the surface of the coating layer of each test piece before and after retort treatment (121°C, 30 minutes) using a hot water storage retort apparatus, and the Scotch tape was peeled off after 10 seconds, and the total area of ​​the deposit (ink) on the surface of the Scotch tape was determined. The adhesion of the ink layer was then evaluated according to the total area of ​​the material adhering to the surface of the cellophane tape, based on the following criteria. The results are shown in Tables 1 and 2. The ink adhesion is an index of the degree to which the ink layer is prevented from peeling. (standard) ○...The total area of ​​the deposits is 300mm 2 less than ×...The total area of ​​the deposits is 300mm 2 End

[0105] (3) Friction resistance Test pieces measuring 30 mm x 250 mm were cut from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2. The test pieces were then subjected to a Gakushin test with the surface of the coating layer covered with white cloth before and after retort treatment (121°C, 30 minutes) using a hot water storage retort apparatus. Specifically, the test pieces were rubbed 100 times while a load of 200 g was applied to the test pieces via the white cloth. Then, whether the ink was attached to the white cloth was visually observed. The results are shown in Tables 1 and 2. In Tables 1 and 2, "○" and "×" are based on the following criteria. (standard) ○ Ink did not adhere to the white cloth × Ink adhered to the white cloth

[0106] (4) Scratch resistance Test pieces measuring 15 mm x 100 mm were cut from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2. The surface of the coating layer of each test piece was scratched 10 times with the back of a nail before and after retort treatment (121°C, 30 minutes) using a hot water storage retort apparatus to check whether the ink adhered to the back of the nail. The results are shown in Tables 1 and 2. In Tables 1 and 2, "○" and "×" are based on the following criteria. (standard) ○ The ink did not adhere to the nail plate. × Ink got on the nail

[0107] (5) Heat resistance Test pieces of 30 mm x 50 mm were cut out from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2. The test pieces were then heated for 1 second with a 240°C seal bar having an AL glossy surface under a load of 0.2 MPa. Then, it was checked whether ink adhered to the seal bar. The results are shown in Tables 1 and 2. In Tables 1 and 2, "○" and "×" are based on the following criteria. (standard) ○ Ink did not adhere to the seal bar × Ink has adhered to the seal bar

[0108] (6) Discoloration resistance Test pieces measuring 40 mm x 40 mm were cut from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2. Then, the color difference (ΔE) of the test pieces was measured before and after retort treatment (121°C, 30 minutes) using a hot water storage retort device. The color difference (ΔE) is a measurement value calculated from the measurements of a spectrophotometer (eXact, manufactured by X-rite). Specifically, the color difference (ΔE) was measured by measuring the lightness (L) of the surface of the coating layer of the test piece before and after retort treatment using the above-mentioned spectrophotometer. * ), hue and saturation (a * , b * ) was measured, and the difference in brightness before and after retort treatment (ΔL * ), the difference in hue and saturation (Δa * , Δb * ) is a value calculated by the following formula (A).

number

[0109] [Table 1]

[0110] [Table 2]

[0111] From the results shown in Tables 1 and 2, all of the packaging films of the Examples were rated "good" for adhesion and "good" for discoloration resistance even after retort treatment. In contrast, the packaging films of the Comparative Examples were rated "poor" for adhesion and discoloration resistance after retort treatment. From the above, it was confirmed that the packaging film of the present disclosure can suppress peeling and discoloration of the ink layer even when subjected to retort treatment. [Explanation of symbols]

[0112] 10...coating layer, 20...ink layer, 30...paper base material, 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. An ink layer, a paper substrate, and a sealant layer are provided in this order; the ink layer is coated with a coating layer, the coating layer is obtained using a resin composition for a coating layer containing a polyurethane resin and a curing agent, A packaging film, wherein the ink layer is obtained using an ink containing a polyurethane resin.

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

3. 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.

4. The packaging film according to claim 2 , wherein the curing agent contained in the ink includes an isocyanate-based curing agent.

5. The packaging film according to claim 1 , further comprising a gas barrier layer between the sealant layer and the paper substrate.

6. 2. The packaging film according to claim 1, wherein the total thickness of the coating layer and the ink layer is 10 μm or less.

7. 2. The packaging film according to claim 1, wherein the coating layer has a thickness of 0.1 to 5 μm, and the ink layer has a thickness of 0.1 to 5 μm.

8. the ink contains a pigment, The packaging film according to claim 1 , wherein the content of the pigment in the coating layer is lower than the content of the pigment in the ink layer.

9. A packaging bag comprising the packaging film according to any one of claims 1 to 8.

10. A packaging product comprising the packaging bag according to claim 9 and contents contained in the packaging bag.

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