Packaging film, packaging bag, and packaging product

Abstract

This packaging film is provided with an ink layer, a paper substrate, and a sealant layer, in this order. The ink layer is coated by a coating layer. The coating layer is obtained using a resin composition for a coating layer. This resin composition contains a polyurethane resin and a curing agent. 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] In recent years, the impact of microplastics on environmental pollution, as seen in the problem of marine plastic waste, has become a concern. Accordingly, a movement to eliminate plastic and a trend to refrain from using plastic products have gained momentum, leading to an increased demand for packaging films containing a paper substrate. 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 storage containers, which comprises, in this order, a varnish layer, an ink layer, a paper substrate, and a heat seal layer, wherein the varnish layer and the ink layer contain nitrocellulose and a synthetic resin, and the ink layer further contains a pigment.

[0003] Japanese Patent Application Laid-Open No. 2022-120374

[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.

[0006] In order to solve the above problems, one aspect of the present disclosure provides a packaging film comprising a coating layer, an ink layer, a paper substrate, and a sealant layer in this order, 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 the polyurethane resin. Herein, the coating layer may be a cured product of the resin composition for the coating layer containing the polyurethane resin and a curing agent. Alternatively, the coating layer may contain a reaction product of the polyurethane resin and the curing agent. Hereinafter, "polyurethane resin" may also be referred to as "urethane resin." Furthermore, the ink layer may contain an ink containing the polyurethane resin or a cured product of the ink containing the polyurethane resin. Alternatively, the ink layer may contain a polyurethane resin or a cured product of the polyurethane resin. With this packaging film, peeling and discoloration of the ink layer can be suppressed even when retorting is performed.

[0007] The inventors of the present disclosure speculate that the reason for the above-mentioned effects is as follows. Specifically, the inclusion of a polyurethane resin in the resin composition for the coating layer and the ink allows both the coating layer and the ink layer to have high hot water resistance. In particular, the resin composition for the coating layer further includes a curing agent 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 deterioration 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 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, 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 also 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 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 (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 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 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 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 strength of the ink layer can be effectively increased. Therefore, even if the ink layer is exposed at the end surface of the packaging film, deterioration of the exposed portion of the ink layer is effectively suppressed after retort treatment of the packaging film, 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, which further improves the gas barrier properties of the packaging film.

[0012] In the packaging film, the total thickness of the coating layer and the ink layer is preferably 10 μm or less. In this case, the surface of the coating layer is uneven due to the unevenness of the surface of the paper substrate, compared to when the total thickness of the coating layer and the 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, which can improve the hot water resistance of the coating layer and the ink layer while also improving recyclability.

[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. In addition, the coating layer has higher transparency than 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 accommodated in the packaging bag. The packaging product includes the packaging film described above, and the packaging bag can suppress peeling and discoloration of the ink layer even when subjected to retort treatment. Therefore, the packaging product can suppress peeling and discoloration of the ink layer even when subjected to retort treatment. This allows for a longer life of the packaging product.

[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.

[0018] 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.

[0019] Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure 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 includes 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 coating layer 10 is obtained using a resin composition for a coating layer, which 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, between the paper substrate 30 and the sealant layer 70, from the paper substrate 30 side. 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 paper substrate 30 and the sealant layer 70. The adhesive layer 60 may also be omitted. The packaging film 100 can suppress peeling and discoloration of the ink layer 20 even when subjected to retort treatment.

[0022] The coating layer 10, the ink layer 20, the paper substrate 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.

[0023] (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 that contains a polyurethane resin as a binder resin and a curing agent. 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 liquids such as the Takelac E series manufactured by Mitsui Chemicals, Inc. and the Burnock series manufactured by DIC Corporation.

[0024] 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. Taking into account the use of additives, the content of polyurethane resin in the solid content contained in the resin composition for the coating layer may be 99% by mass or less or 90% by mass or less. The content of polyurethane resin in the solid content contained in the resin composition for the coating layer may be, for example, 50% by mass or more and 99% by mass or less, 50% by mass or more and 90% by mass or less, or 70% by mass or more and 90% by mass or less.

[0025] The curing agent is consumed by a crosslinking reaction with the polyurethane resin during the formation of the coating layer 10. When the resin composition for the coating layer contains a curing agent, the curing agent promotes a crosslinking reaction (high molecular weight) of the polyurethane resin when the resin composition for the coating layer is used to obtain a coating layer, 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 susceptible to deterioration 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, since 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 at least a portion of the ink layer 20 can be prevented from peeling off (ink removal) by the seal bar. Examples of curing agents include isocyanate-based curing agents. Among these, isocyanate-based curing agents are preferred. 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 coating layer 10 effectively protects the ink layer 20 from hot water, 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). These 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 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.

[0028] 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 or more, 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.

[0029] 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.

[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 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.

[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 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] The thickness of the coating layer 10 is not particularly limited and may be adjusted as needed. However, from the viewpoint of improving the hot water resistance of the ink layer 20, the thickness is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 1 μm or more. 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 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. 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 average 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, for example, 0.1 g / m ２ It is sufficient to use 0.3 g / m or more. ２ or more or 0.5 g / m ２ The coating amount of the resin composition for the coating layer that forms the coating layer 10 may be, for example, 7 g / m 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 5 g / m or less. ２ or less than 4 g / m２ 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. This makes it possible to reduce the amount of adhesive, etc. used when obtaining the adhesive layer 60, thereby reducing the environmental impact. The ink layer 20 is obtained using an ink that contains a polyurethane resin as a binder resin.

[0036] 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.

[0037] 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 urethane 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 edge 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 is suppressed after retorting the packaging film 100. As a result, peeling of the ink layer 20 from the paper substrate 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 peeling of the ink layer 20 from the paper substrate 30 are effectively suppressed after retort treatment of the packaging film 100, thereby more effectively suppressing peeling of the ink layer 20 from the paper substrate 30. Examples of isocyanate-based curing agents include materials containing hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). These 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. The content of the curing agent in the ink may be 1% by mass or more to 10% by mass or less, or 3% by mass or more to 8% by mass or less.

[0038] 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 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% 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 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.

[0039] 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.

[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. 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 paper substrate 30, the ink layer 20 is composed of a single layer. When multicolor printing is performed on the paper substrate 30, the ink layer 20 is composed of multiple layers. In this case, for example, a first ink layer may be formed by solid white printing on the entire surface of the paper substrate 30, and a second ink layer comprising letters, pictures, etc. may be formed on top of the first ink layer. Furthermore, a layer of ink containing a black pigment such as black carbon or metal powder may be provided for light blocking. Furthermore, the ink layer 20 may be provided only on a portion of the surface of the paper substrate 30, or may be provided on the entire surface of the paper substrate 30.

[0043] Examples of methods for forming the ink layer 20 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.

[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 paper substrate 30, 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. The amount of ink applied to form the ink layer 20 is not particularly limited, but when forming the ink layer 20, it is preferably 0.1 g / m, for example. ２ It is sufficient to use 0.3 g / m or more. ２ or more or 0.5 g / m ２ The amount of ink applied may be 7 g / m or more. ２ Preferably 5 g / m or less ２ Less than 4 g / m, more preferably２ or less. 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 substrate 30 will result in unevenness on the surface of the coating layer 10, compared to when the total thickness T exceeds 10 μm. As a result, the texture of the paper substrate 30 remains in the packaging film 100, and blocking between the coating 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 Substrate The paper substrate 30 is a substrate containing paper, which refers to a material containing plant-derived pulp as a primary component, where the term "primary component" refers to a component containing plant-derived pulp at 50% by mass or more. The inclusion of the paper substrate 30 in the packaging film 100 contributes 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 include a coating layer at least on the sealant layer 70 side of the paper. If the paper substrate 30 further includes a coating layer, this can prevent the anchor coating layer 40 from penetrating into the paper and also serve as a sealant to fill in unevenness in the paper, allowing the anchor coating layer 40 to be formed uniformly and 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 resins and cellulose resins. Examples of fillers include kaolin, calcium carbonate, talc, and mica. When the paper substrate does not have a coating layer, discoloration of the paper due to the retort treatment of the packaging film 100 is less likely to occur. When the paper substrate 30 does not have a coating layer, that is, when the paper substrate 30 is made of paper only, the paper substrate 30 and the anchor coat layer 40 are in direct contact. The paper substrate 30 may be composed 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 the environmental load, and from the viewpoint of 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 thereby reducing the environmental load, the thickness of the paper substrate 30 may be 100 μm or less, 60 μm or less, or 50 μm or less. The basis weight of the paper substrate 30 is not particularly limited. From the viewpoint of reducing materials to reduce the environmental load, and from the viewpoint of obtaining excellent heat resistance, impact resistance, and gas barrier properties, the basis weight of the paper substrate 30 may be 40 g / m ２ Above, 60g / m２ or more or 80 g / m ２ Furthermore, from the viewpoint of reducing the amount of plastic used and reducing the environmental load, the basis weight of the paper base material 30 is set to 160 g / m ２ Below, 140g / m ２ or less than 120 g / m ２ The thickness of the paper substrate 30 is not particularly limited. 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 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 the environmental impact, the thickness of the paper substrate 30 may be 200 μm or less, 170 μm or less, or 150 μm or less. The thickness of the paper substrate 30 may be 50 μm or more and 200 μm or less, 75 μm or more and 170 μm or less, or 100 μm or more and 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. Examples of such materials include polyurethane resins and polyvinyl alcohol resins. The material constituting the anchor coat layer 40 preferably contains a polyurethane resin. Such a polyurethane resin is composed of, for example, a reaction product of an organosilane or an 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 primarily functions as a crosslinker or curing agent. The polyol compound and the isocyanate compound may be either a monomer or a polymer. Examples of polyvinyl alcohol-based resins include fully saponified polyvinyl alcohol resins, partially saponified polyvinyl alcohol resins, modified polyvinyl alcohol resins, and ethylene-vinyl alcohol copolymer resins. The degree of polymerization of the polyvinyl alcohol-based resin is preferably 300 or more and 1700 or less. A degree of polymerization of 300 or more improves the gas barrier properties and flex resistance of the packaging film 100, while a degree of polymerization of 1700 or less reduces the viscosity of a coating liquid containing the polyvinyl alcohol-based resin, improving its applicability. When the anchor coat layer 40 contains a polyvinyl alcohol-based resin, it exhibits excellent flexibility and can suppress cracking of the gas barrier layer (described later) after bending (folding), thereby suppressing deterioration of the gas barrier properties and improving adhesion between the gas barrier layer and the anchor coat layer 40. The total content of the polyvinyl alcohol-based resin in the anchor coat layer 40 may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0049] The thickness of the anchor coat layer 40 is not particularly limited, but from the viewpoint of improving the 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 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.

[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 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.

[0052] (Vapor-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. Examples of metals constituting the vapor-deposited layer of a metal or a vapor-deposited layer of a 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 therefore 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] Furthermore, 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. The thickness of the vapor-deposited layer may be 5 nm or more and 300 nm or less, 8 nm or more and 200 nm or less, or 10 nm or more and 100 nm or less.

[0055] (Gas barrier coating layer) The gas barrier coating layer is a layer that coats the vapor deposition layer or the metal foil. In this case, the gas barrier property of the packaging film 100 is improved. Furthermore, the gas barrier coating layer can suppress a decrease in the gas barrier property of the packaging film 100 even if damage such as cracks occurs in the vapor deposition layer or the metal foil.

[0056] 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 a hydrolyzate thereof, and the composition may further contain at least one of a silane coupling agent and a hydrolyzate thereof.

[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(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.

[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, R ３ is an alkyl group or -C ２ H ４ OCH ３ In 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. ３Examples 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.

[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 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.

[0062] 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.

[0063] (6) Adhesive Layer The packaging film 100 may further include an adhesive layer 60 between the paper substrate 30 and the sealant layer. Examples of the adhesive layer 60 include an adhesive layer formed using an adhesive 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 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.

[0067] The adhesive resin is a heat-sealable adhesive thermoplastic resin that can be melted and bonded to each other by heat. Examples of the adhesive resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, methylpentene polymer, and acid-modified polyolefin resins obtained by modifying polyolefin resins (also referred to as "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. 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 less, or 1 μm or more and 5 μm or less.

[0068] (7) Sealant Layer As the sealant layer 70, a polyolefin resin film, a polyester resin film, or the like can be used.

[0069] Polyolefin resin films are suitable for use in terms of sealing suitability, etc., 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.

[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. 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. For example, if the sealant layer 70 is white, the print can appear clearer. If 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 is preferably a non-stretched film from the viewpoint of heat sealing properties. The sealant layer 70 may be a peelable sealant or may not be a peelable sealant.

[0075] 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.

[0076] (8) Intermediate Layer The intermediate layer is a layer disposed 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 between the gas barrier layer 50 and the paper substrate 30. The intermediate layer may 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, ethylene-(meth)acrylic acid copolymer, and polypropylene resin (also referred to as "polypropylene"). 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.

[0077] 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 (material recycled resin) may be used, but from the viewpoints of hygiene and quality, it is preferable to use a chemically recycled resin (chemically recycled resin). 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 preferable. 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.

[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 necessary. 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. 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.

[0084] <Packaging Product> Next, an embodiment of a 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 a 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 description will be omitted. As shown in FIG. 2, a 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.

[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 a retort treatment. Therefore, the packaged product 300 can suppress peeling and discoloration of the ink layer 20 even when subjected to a 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, a pillow package, etc. The packaging bag 200 may further have a spout or a zipper depending on the application.

[0088] 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.

[0089] <Summary of the Present Disclosure> The summary of the present disclosure is as follows. [1] A packaging film comprising an ink layer, a paper base material, 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, 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 a cured product of the resin composition for a coating layer, and the ink layer contains the ink or a cured product of the ink. [3] The packaging film according to [1] or [2], wherein the content of the curing agent in the resin composition for a coating layer is 1% by mass or more and 10% by mass or less. [4] The packaging film according to any of [1] to [3], wherein the ink further contains a curing agent. [5] The packaging film according to any of [1] to [4], wherein the curing agent contained in the resin composition for a coating layer includes an isocyanate-based curing agent. [6] The packaging film according to [5], wherein the isocyanate-based curing agent contains at least one selected from the group consisting of hexamethylene diisocyanate and isophorone diisocyanate. [7] The coating amount of the resin composition for the coating layer is 0.1 g / m ２ 7g / m or more ２[8] The packaging film according to any one of [1] to [6], wherein the content of the curing agent in the ink is 1% by mass or more and 10% by mass or less. [9] The packaging film according to [4] or [8], wherein the curing agent contained in the ink comprises an isocyanate-based curing agent.

[10] The packaging film according to [9], wherein the isocyanate-based curing agent comprises at least one selected from the group consisting of hexamethylene diisocyanate and isophorone diisocyanate.

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

[10] , further comprising a gas barrier layer between the sealant layer and the paper substrate.

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

[11] , wherein the total thickness of the coating layer and the ink layer is 10 μm or less.

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

[12] , wherein the thickness of the coating layer is 0.5 to 5 μm and the thickness of the ink layer is 0.5 to 5 μm.

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

[13] , wherein the ink further contains a pigment, and wherein the content of the pigment in the coating layer is lower than the content of the pigment in the ink layer.

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

[14] , wherein the paper base material does not have a coating layer.

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

[15] , further comprising an adhesive layer between the paper base material and the sealant layer.

[17] The packaging film according to

[11] , further comprising an anchor coat layer between the paper base material and the gas barrier layer.

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

[17] , wherein the content of polyurethane resin in the solid content contained in the resin composition for the coating layer is 50 to 90 mass%. Packaging film.

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

[18] , wherein the content of polyurethane resin in the solid content contained in the ink is 20 to 80 mass%.

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

[19] .

[21] A packaging product comprising the packaging bag according to

[20] and contents contained in the packaging bag.

[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. <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. (In polyurethane medium 2, polyurethane resin is 20% by mass, and organic solvent (propyl acetate and ethyl acetate) is 80% by mass) Nitrocellulose medium: Ecocolor HR OP Varnish, manufactured by Toyo Ink Co., Ltd.

[0092] <Ink base ingredients> Polyurethane ink 1: XGS-922 Crimson 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 (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 (silica 25% by mass, synthetic resin 15% by mass, organic solvent (ethyl acetate and isopropyl alcohol) 60% by mass), manufactured by Toyo Ink Co., Ltd. Wax dispersion 1: 280 additive (dispersion of polyamide (PA) wax (polyamide (PA) wax 25% by mass, organic solvent (ethyl acetate) 75% by mass), 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)), manufactured by Toyo Ink Co., Ltd.)

[0094] <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)

[0095] <Preparation of packaging film> (Example 1) First, a paper substrate having a basis weight of 70 g / m ２A hot-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-based curing agent 1 as additive 1 and ethyl acetate as an organic solvent to a polyurethane-based medium 1 as the base material. The polyurethane-based medium 1, additive 1, and 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 additive 1 and ethyl acetate as an organic solvent to a polyurethane-based ink 1 as the base material. The polyurethane-based ink 1, additive 1, and ethyl acetate were blended in a mass ratio of 100:3:35. The ink was then applied to the surface of the paper substrate and dried to form a 3 μm-thick ink layer. The resin composition for a coating layer was then applied to the surface of the ink layer and dried to form a 1 μm-thick coating layer. A 12 μm-thick alumina-deposited PET film was also prepared. Next, dry laminating adhesive 1 was applied to the back surface of the paper substrate (the surface on which no ink layer was formed), and an alumina-deposited PET film was attached to the dry laminating adhesive 1. Next, dry laminating adhesive 1 was applied to the alumina side of the alumina-deposited PET film, and a 70 μm-thick unstretched polypropylene (CPP) film was attached to the dry laminating adhesive 1, and then the dry laminating adhesive 1 was dried. In this manner, 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 component 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 component 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 for this.

[0098] Example 2: A packaging film was obtained in the same manner as in Example 1, except that the resin composition for the coating layer was prepared using Polyurethane Medium 2 instead of Polyurethane Medium 1 as the main component, Additive 1 (Isocyanate Curing Agent 2), Additive 2 (Antiblocking Agent), and Additive 3 (Wax Dispersion 2) instead of Additive 1 (Isocyanate Curing Agent 1), and the ink was prepared using Polyurethane Ink 2 instead of Polyurethane Ink 1 as the main component, Additive 1 (Isocyanate Curing Agent 2), Additive 2 (B-inhibitor), and Additive 3 (Wax Dispersion 2) instead of Additive 1 (Isocyanate Curing Agent 1). The Polyurethane Medium 2, Additive 1, Additive 2, Additive 3, and ethyl acetate were blended in a mass ratio of 100:3:3:3:35 for the resin composition for the coating layer. As for the ink, polyurethane ink 2, additive 1, additive 2, additive 3 and ethyl acetate were blended 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 the resin composition for the coating layer was prepared using Polyurethane Medium 2 instead of Polyurethane Medium 1 as the main ingredient, Additive 1 (Isocyanate-Based Curing Agent 2), Additive 2 (Wax Dispersion 1), and Additive 3 (Wax Dispersion 2) instead of Additive 1 (Isocyanate-Based Curing Agent 1) as the additives, and the ink was prepared using Polyurethane Ink 2 instead of Polyurethane Ink 1 as the main ingredient, Additive 1 (Isocyanate-Based Curing Agent 2), Additive 2 (Wax Dispersion 1), and Additive 3 (Wax Dispersion 2) 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 blended in a mass ratio of 100:3:3:3:35. As for the ink, polyurethane ink 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 the resin composition for the coating layer was prepared using Polyurethane Medium 2 instead of Polyurethane Medium 1 as the base component, Additive 1 (Isocyanate-Based Curing Agent 3), Additive 2 (Wax Dispersion 1), and Additive 3 (Wax Dispersion 2) instead of Additive 1 (Isocyanate-Based Curing Agent 1) as the additives, and the ink was prepared using Polyurethane Ink 2 instead of Polyurethane Ink 1 as the base component, Additive 1 (Isocyanate-Based Curing Agent 2), Additive 2 (Wax Dispersion 1), and Additive 3 (Wax Dispersion 2) instead of Additive 1 (Isocyanate-Based Curing Agent 1) as the additives. The Polyurethane Medium 2, Additive 1, Additive 2, Additive 3, and ethyl acetate were blended in a mass ratio of 100:3:3:3:35 for the resin composition for the coating layer. As for the ink, polyurethane ink 2, additive 1, additive 2, additive 3 and ethyl acetate were blended 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 these test pieces were immersed in hot water in a hot water storage retort device and subjected to retort treatment at 121°C for 30 minutes. At this time, the presence or absence of ink elution into the hot water was visually confirmed as an index of water resistance, and the evaluation was 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: (Criteria) ◯: No elution of ink into hot water was observed. ×: Elution of ink into hot water was observed.

[0104] (2) Adhesion The packaging films of Examples 1 to 6 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 apparatus, 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. The adhesion of the ink layer was evaluated according to the total area of ​​the deposits on the Cellotape surface, based on the following criteria. The results are shown in Tables 1 and 2. The ink adhesion serves as an index of the degree of inhibition of peeling of the ink layer. (Criteria) ○: Total area of ​​deposits is 300 mm ２ Less than ×...total area of ​​deposits is 300 mm ２ End

[0105] (3) Abrasion 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. Then, the test pieces before and after retort treatment (121°C, 30 minutes) using a hot water storage retort device were subjected to a Gakushin test with the surface of the coating layer covered with white cloth. Specifically, 100 abrasions were performed while a load of 200 g was applied to the test piece via the white cloth. Then, it was visually observed whether the ink had adhered to the white cloth. The results are shown in Tables 1 and 2. In Tables 1 and 2, "◯" and "×" are based on the following criteria: (Criteria) ◯: The ink did not adhere to the white cloth. ×: The 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. Then, for the test pieces before and after retort treatment (121°C, 30 minutes) using a hot water storage retort device, the surface of the coating layer was scratched 10 times with the top of a nail to check whether the ink adhered to the top of the nail. The results are shown in Tables 1 and 2. In Tables 1 and 2, "○" and "×" are based on the following criteria: (Criteria) ○: The ink did not adhere to the top of the nail. ×: The ink adhered to the top of the nail.

[0107] (5) Heat Resistance Test pieces measuring 30 mm x 50 mm were cut from the packaging films of Examples 1 to 6 and Comparative Examples 1 and 2. The test pieces were then heated for 1 second at a load of 0.2 MPa using a seal bar with a glossy AL surface at 240°C. It was then 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: (Criteria) ◯: Ink did not adhere to the seal bar. ×: Ink adhered to the seal bar.

[0108] (6) Color 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. 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) was a measurement calculated from the measurements of a spectrophotometer (eXact, manufactured by X-rite). Specifically, the color difference (ΔE) was measured using the above-mentioned spectrophotometer to measure the lightness (L ＊ ), 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). The following evaluation was then made according to the color difference (ΔE) value based on the following criteria. The results are shown in Tables 1 and 2. (Criteria) ○: Color difference (ΔE) is less than 1 △: Color difference (ΔE) is 1 or more but less than 5 ×: Color difference (ΔE) is 5 or more

[0109]

[0110]

[0111] From the results shown in Tables 1 and 2, all of the packaging films of the Examples had adhesion of "○" and discoloration resistance of "○" even after retort treatment. In contrast, the packaging films of the Comparative Examples had adhesion and discoloration resistance of "×" after retort treatment. From the above, it was confirmed that the packaging films of the present disclosure can suppress peeling and discoloration of the ink layer even after retort treatment.

[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. A packaging film comprising an ink layer, a paper base material, 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 the coating layer comprising a polyurethane resin and a curing agent, and the ink layer being obtained using an ink comprising a polyurethane resin.

2. The packaging film according to claim 1, wherein the coating layer is a cured product of the resin composition for the coating layer, and the ink layer contains the ink or a cured product of the ink.

3. A packaging film according to claim 1 or 2, wherein the content of the curing agent in the resin composition for the coating layer is 1% by mass or more and 10% by mass or less.

4. The packaging film according to claim 1 or 2, wherein the ink further comprises a curing agent.

5. The packaging film according to claim 1 or 2, wherein the curing agent contained in the resin composition for the coating layer includes an isocyanate-based curing agent.

6. The packaging film according to claim 5, wherein the isocyanate-based curing agent comprises at least one selected from the group consisting of hexamethylene diisocyanate and isophorone diisocyanate.

7. The coating amount of the resin composition for the coating layer is 0.1 g / m ２ 7g / m or more ２ 3. The packaging film according to claim 1 or 2, wherein:

8. The packaging film according to claim 4, wherein the content of the curing agent in the ink is 1% by mass or more and 10% by mass or less.

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

10. The packaging film according to claim 9, wherein the isocyanate-based curing agent includes at least one selected from the group consisting of hexamethylene diisocyanate and isophorone diisocyanate.

11. The packaging film according to claim 1 or 2, further comprising a gas barrier layer between the sealant layer and the paper substrate.

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

13. The packaging film according to claim 1 or 2, 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.

14. The packaging film according to claim 1 or 2, wherein 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.

15. The packaging film according to claim 1 or 2, wherein the paper substrate does not have a coating layer.

16. The packaging film of claim 1 or 2, further comprising an adhesive layer between the paper substrate and the sealant layer.

17. A packaging bag comprising the packaging film according to claim 1 or 2.

18. A packaging product comprising the packaging bag according to claim 17 and contents contained within the packaging bag.

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