Packaging film, packaging container, and packaging product

Abstract

To provide a packaging film, a packaging container, and a packaging product which have light shielding properties, can be easily recycled, and can have excellent shape retention even in a high temperature environment.SOLUTION: A packaging film comprises a base material layer and a sealant layer. The packaging film comprises a light shielding layer. The light shielding layer contains a light shielding pigment. The absorbance of the light shielding pigment is lower than the absorbance of the absorption peak of the resin contained in the base material layer and the sealant layer in a near infrared wavelength region where the absorption peak appears.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In packaging containers such as packaging bags for packaging contents such as food, light-shielding properties are required to protect the contents from external light. For example, the packaging material described in the following Patent Document 1 is known as a packaging film used in such packaging containers having light-shielding properties. This packaging material includes a first base layer, a picture-printed layer, a first shielding layer, a second base layer, a light-shielding layer, a second shielding layer, and a seal layer, which are laminated in this order, and the light-shielding layer is a resin containing at least a black light-shielding agent, and carbon black is used as the black light-shielding agent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7095366 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, due to the growing environmental awareness caused by the problem of marine plastic waste, etc., there has been a demand for more efficient separation and recovery of plastics and recycling of packaging films, and near-infrared spectroscopy has come to be used to more easily separate and recover plastics. Since many plastics have characteristic peaks in the near-infrared wavelength region, the plastics contained in the packaging film can be easily identified by performing near-infrared spectroscopy on the packaging film. In recent years, hot showcases have been installed in supermarkets and convenience stores. Hot showcases keep products warm at a temperature of 70 to 90°C, and from the viewpoint of hygiene, there is a demand to keep products warm by placing them in packaging containers.

[0005] However, the packaging material described in Patent Document 1 has the following problems. In other words, the above-mentioned packaging material has sufficient light-blocking properties because the light-blocking layer is composed of a resin that contains at least a black light-blocking agent, but the carbon black used as the light-blocking agent completely absorbs near-infrared light. Therefore, when near-infrared spectroscopic analysis is performed on the packaging material, the absorption peak specific to plastics cannot be confirmed, making it impossible to separate the plastics and making recycling difficult. In addition, when the packaging material is used as a packaging container for keeping products warm in a hot case or the like, it can soften and deform. Therefore, there is a demand for the packaging material to be able to maintain its shape, i.e., have shape retention, even in a high-temperature environment.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a packaging film, a packaging container, and a packaging product that have light-blocking properties, can be easily recycled, and have excellent shape retention even in high-temperature environments. [Means for solving the problem]

[0007] In order to solve the above problems, the present disclosure provides a packaging film comprising a base layer and a sealant layer, the packaging film further comprising a light-shielding layer, the light-shielding layer containing a light-shielding pigment, the light-shielding pigment having an absorbance lower than the absorbance of the absorption peak in the near-infrared wavelength region in which the absorption peak of a resin contained in the base layer and the sealant layer appears. According to this packaging film, since the light-shielding layer contains a light-shielding pigment, it is possible to have light-shielding properties. Furthermore, the absorbance of the light-shielding pigment contained in the light-shielding layer is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and the sealant layer appears. Therefore, when near-infrared spectroscopy is performed on the packaging film, the absorption peak of the resin can be confirmed in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and the sealant layer appears, and the resin contained in the base layer and the sealant layer can be easily identified. As a result, the packaging film of the present disclosure can be easily recycled. Furthermore, since the absorbance of the light-shielding pigment contained in the light-shielding layer is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and the sealant layer appears, the absorption of the near-infrared rays is suppressed, and the thermal load on the packaging film in a high-temperature environment is reduced. As a result, the packaging film of the present disclosure can have excellent shape retention even in a high-temperature environment.

[0008] In the packaging film, the resin contained in the base layer and the sealant layer may be a polyolefin resin, and the near-infrared wavelength region may be 1600 to 1800 nm.

[0009] The packaging film may further comprise a barrier layer between the substrate layer and the sealant layer. Providing a barrier layer in the packaging film allows the packaging film to have barrier properties against gases such as oxygen and water vapor.

[0010] The packaging film may further include a printing layer, and the printing layer may have the light-shielding layer. Since the printing layer usually contains a colorant, if a light-shielding pigment is contained as a colorant, deterioration of the properties of the printing layer can be reduced. In addition, when the light-shielding pigment is contained in the printing layer, it is not necessary to contain the light-shielding pigment in the base layer and the sealant layer, so deterioration of the performance of the base layer and the sealant layer can be suppressed.

[0011] In the packaging film, the sealant layer may have the light-shielding layer.

[0012] In the packaging film, the light-blocking pigment may include a black pigment. Since black pigments have high absorbency for ultraviolet and visible light, they can effectively block ultraviolet and visible light, and can suppress deterioration and fading of the contents contained in a packaging container obtained using the packaging film.

[0013] The black pigment may include at least one selected from the group consisting of an azo pigment, an azomethine pigment, a melanin pigment, and an isoindoline pigment. These black pigments have high transmittance to near-infrared rays and low absorbance in the near-infrared wavelength region, so when near-infrared spectroscopic analysis is performed on the packaging film, the absorption peak of the resin contained in the packaging film in the near-infrared wavelength region can be more easily confirmed, and the resin contained in the packaging film can be more easily identified.

[0014] The barrier layer may comprise a barrier substrate and an inorganic layer formed on one surface of the barrier substrate. In this case, since the inorganic layer is supported by the barrier substrate, even if stress is applied to the barrier layer, the stress is mitigated by the barrier substrate, making it difficult for cracks to occur in the inorganic layer.

[0015] The present disclosure also provides a packaging container obtained by using the above-mentioned packaging film. According to this packaging container, since the light-shielding layer of the packaging film contains a light-shielding pigment, it is possible to have light-shielding properties. In addition, the absorbance of the light-shielding pigment contained in the light-shielding layer of the packaging film is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and the sealant layer appears. Therefore, when near-infrared spectroscopy is performed on the packaging container, the absorption peak of the resin can be confirmed in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and the sealant layer appears, and the resin contained in the base layer and the sealant layer can be easily identified. As a result, the packaging container of the present disclosure can be easily recycled. Furthermore, since the absorbance of the light-shielding pigment contained in the light-shielding layer of the packaging film is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and the sealant layer appears, the absorption of the near-infrared rays is suppressed, and the thermal load on the packaging container in a high-temperature environment is reduced. As a result, the packaging container of the present disclosure can have excellent shape retention even in a high-temperature environment.

[0016] The present disclosure further provides a packaging product comprising the packaging container described above and contents contained within the packaging container. According to this packaging product, since the light-shielding layer of the packaging film contains a light-shielding pigment, it is possible to have light-shielding properties, and deterioration of the quality of the contents due to light can be suppressed. In addition, the absorbance of the light-shielding pigment contained in the light-shielding layer of the packaging film is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and sealant layer of the packaging film appears. Therefore, when near-infrared spectroscopy is performed on the packaging container left after opening the packaging product and removing the contents, the absorption peak of the resin can be confirmed in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and sealant layer appears, and the resin contained in the base layer and sealant layer can be easily identified. As a result, the packaging product of the present disclosure can easily recycle the packaging container. Furthermore, since the absorbance of the light-shielding pigment contained in the light-shielding layer of the packaging film is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer and sealant layer appears, the absorption of the near-infrared rays is suppressed, and the heat load on the packaging container in a high-temperature environment is reduced. As a result, the packaged product of the present disclosure is able to have excellent shape retention even in high-temperature environments, and deterioration of its appearance is suppressed. Effect of the Invention

[0017] According to the present disclosure, there are provided a packaging film, a packaging container, and a packaged product that have light-blocking properties, can be easily recycled, and have excellent shape retention even in high-temperature environments. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing one embodiment of a packaging film of the present disclosure. [Diagram 2] FIG. 1 is a cross-sectional view illustrating one embodiment of a packaging product of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, embodiments of the present disclosure will be described in detail. However, 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 includes a base layer 10 and a sealant layer 40. The packaging film 100 further includes a light-shielding layer, which contains a light-shielding pigment. The light-shielding pigment has a lower absorbance than the absorbance of the absorption peak of the resin in the near-infrared wavelength region where the absorption peaks of the resins included in the base layer 10 and the sealant layer 40 appear. The packaging film 100 may further include a barrier layer 30 between the base material layer 10 and the sealant layer 40. The packaging film 100 may further include a printed layer 20 between the base material layer 10 and the sealant layer 40, more specifically, between the base material layer 10 and the barrier layer 30.

[0022] According to the packaging film 100, the light-shielding layer contains a light-shielding pigment, so that the film can have light-shielding properties. In addition, the absorbance of the light-shielding pigment contained in the light-shielding layer is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer 10 and the sealant layer 40 appears. Therefore, when the packaging film 100 is subjected to near-infrared spectroscopy, the absorption peak of the resin can be confirmed in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer 10 and the sealant layer 40 appears, and the resin contained in the base layer 10 and the sealant layer 40 can be easily identified. As a result, the packaging film 100 can be easily recycled. Furthermore, the absorbance of the light-shielding pigment contained in the light-shielding layer is lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer 10 and the sealant layer 40 appears, so that the absorption of the near-infrared rays is suppressed, and the thermal load applied to the packaging film 100 in a high-temperature environment is reduced. As a result, the packaging film 100 can have excellent shape retention even in a high-temperature environment.

[0023] The base layer 10, the printed layer 20, the barrier layer 30, the sealant layer 40, the light-shielding layer and the packaging film 100 will be described in detail below.

[0024] (1) Base material layer The base layer 10 serves as a support layer for the packaging film 100 and contains a resin. Examples of the resin contained in the base layer 10 include polyolefin resins, polyester resins, and polyamide resins. Examples of the polyolefin resin include polyethylene resin and polypropylene resin.

[0025] Examples of polyethylene resins include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and very low density polyethylene (VLDPE). These can be used alone or in combination of two or more.

[0026] Examples of polypropylene-based resins include homopolymers, random copolymers, and block copolymers. A homopolymer is a single polymer of propylene, a polypropylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene (e.g., ethylene, 1-butene, 4-methyl-1-pentene, etc.), and a polypropylene block copolymer is a copolymer having a polymer block made of propylene and a polymer block made of the above-mentioned α-olefin other than propylene. Among these, polypropylene-based resins are preferred from the viewpoint of heat resistance.

[0027] Examples of polyester resins include polyethylene terephthalate resin (PET) and polyethylene naphthalate resin (PEN).

[0028] Examples of polyamide resins include nylon 6, nylon 6,6, MXD nylon, and amorphous nylon.

[0029] The resin contained in the base layer 10 may be a biomass-derived resin or a mechanically recycled or chemically recycled resin.

[0030] The base layer 10 may have a single-layer structure or a multi-layer structure. When the base layer 10 has a multi-layer structure, each layer may be laminated by dry lamination or extruder lamination.

[0031] The base layer 10 may be a stretched film or a non-stretched film, but is preferably a stretched film from the viewpoint of gas barrier properties. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferred from the viewpoint of improving the heat resistance of the packaging film 100.

[0032] The resin content in the base layer 10 is preferably 80% by mass or more, and more preferably 85% by mass or more.

[0033] The base layer 10 may further contain additives as necessary. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, flame retardants, reinforcing agents, antistatic agents, inorganic fillers, organic fillers, dyes, and pigments.

[0034] The thickness of the base layer 10 may be 15 μm or more, or may be 20 μm or more. The thickness of the base layer 10 may be 200 μm or less, 150 μm or less, or 100 μm or less. The thickness of the base material layer 10 is preferably 15 to 200 μm, which makes it easy to perform processes such as printing and lamination on the base material layer 10.

[0035] The substrate layer 10 may be subjected to a surface treatment. The method of surface treatment is not particularly limited, and examples thereof include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals.

[0036] (2) Printing layer The printed layer 20 includes an image including characters, patterns, symbols, and combinations thereof. The printed layer 20 can be formed using ink. The ink contains a colorant. The ink may further contain a resin. Furthermore, the ink may further contain a plasticizer, a drying agent, a stabilizer, and the like, as necessary.

[0037] The ink may be either water-based or oil-based, but is preferably water-based. Water-based inks use water or alcohol as a solvent, and therefore can reduce the environmental impact. The ink may be either biomass ink or not, but is preferably biomass ink from the viewpoint of reducing the environmental impact. Here, biomass ink refers to ink containing components obtained from biological resources (biomass) such as cotton, pulp, rice bran, vegetable oil, and angiosperm seeds. The method for forming the printed layer 20 is not particularly limited, and examples of the method for forming the printed layer 20 include printing methods such as gravure printing, offset printing, and flexographic printing. Although the printed layer 20 is provided on only one surface of the base layer 10 in FIG. 1, it may be provided on both surfaces of the base layer 10 instead of only one surface. The printing layer 20 may have a single-layer structure or a multi-layer structure.

[0038] (3) Barrier layer The barrier layer 30 can be composed of a laminate including a barrier substrate and an inorganic layer. In this case, since the inorganic layer is supported by the barrier substrate, even if stress is applied to the barrier layer 30, the stress is mitigated by the barrier substrate, and cracks are unlikely to occur in the inorganic layer. The laminate may further include at least one of an anchor coat layer and an overcoat layer. By including the barrier layer 30 in the packaging film 100, the packaging film 100 can have a barrier property against gases such as oxygen and water vapor.

[0039] (Barrier substrate) The barrier substrate may contain a resin similar to the resin contained in the substrate layer 10. Specifically, the barrier substrate may contain a resin such as a polyolefin-based resin or a polyester-based resin. Examples of the polyolefin resin include polyethylene resin and polypropylene resin.

[0040] Examples of polyester resins include polyethylene terephthalate resin (PET) and polyethylene naphthalate resin (PEN). The surface of the barrier substrate on the inorganic layer side may be subjected to a plasma treatment or the like.

[0041] (Inorganic layer) The inorganic layer contains an inorganic substance, such as an inorganic oxide. When the inorganic material is composed of an inorganic oxide, the inorganic material layer further suppresses the transmission of oxygen and water vapor, so that the storage stability of the contents in a packaging container formed using the packaging film 100 is further improved.

[0042] Inorganic oxides include aluminum oxide and silicon oxide.

[0043] The inorganic layer may be a vapor deposited layer. The deposition layer can be formed on the surface of the barrier substrate by a deposition method such as physical vapor deposition or chemical vapor deposition.

[0044] The thickness of the inorganic layer may be 5 nm or more, or 10 nm or more. When the thickness of the inorganic layer is 5 nm or more, the packaging film 100 tends to exhibit sufficient barrier properties. The thickness of the inorganic layer may be 100 nm or less, or may be 30 nm or less. When the thickness of the inorganic layer is 100 nm or less, deterioration of the barrier property due to cracks in the inorganic layer is easily suppressed.

[0045] (Anchor coat layer) The anchor coat layer is a layer for further improving the adhesion between the barrier substrate and the inorganic layer, and is provided between the barrier substrate and the inorganic layer.

[0046] The material constituting the anchor coat layer may include a polyurethane resin. The polyurethane resin is formed, for example, by reacting an organosilane or organometallic compound with a polyol compound and an isocyanate compound.

[0047] (Overcoat layer) The overcoat layer is composed of a gas barrier coating film formed using a resin composition containing a metal alkoxide and a water-soluble polymer. The resin composition may further contain a silane coupling agent in addition to the metal alkoxide and the water-soluble polymer. The overcoat layer can be formed by applying the above-mentioned resin composition onto the inorganic layer by a coating method such as roll coating, gravure roll coating, or kiss coating, or a printing method such as gravure printing, offset printing, or transfer printing.

[0048] (4) Sealant layer The sealant layer 40 is a surface substrate layer having heat-sealability and contains a resin. When the packaging film 100 contains the sealant layer 40, the packaging film 100 can be laminated with the sealant layer 40 of another packaging film 100 and heat-sealed to form a packaging container.

[0049] The resin contained in the sealant layer 40 may be a polyolefin resin. Examples of the polyolefin resin include polyethylene resin and polypropylene resin. Examples of polyethylene resins include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and very low density polyethylene (VLDPE). These can be used alone or in combination of two or more. Polypropylene-based resins include homopolymers, random copolymers and block copolymers. The resin contained in the sealant layer 40 may be a biomass-derived resin or a mechanically recycled or chemically recycled resin.

[0050] The sealant layer 40 may have a single-layer structure or a multi-layer structure. When the sealant layer 40 has a multi-layer structure, each layer may be laminated by dry lamination or extruder lamination.

[0051] The sealant layer 40 may further contain additives as necessary, such as crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, flame retardants, reinforcing agents, antistatic agents, inorganic fillers, organic fillers, dyes, and pigments.

[0052] The sealant layer 40 may be a stretched film or a non-stretched film, but is preferably a non-stretched film from the viewpoint of heat sealability. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film.

[0053] The resin content in the sealant layer 40 is preferably 85% by mass or more, and more preferably 95% by mass or more. The melting point of the sealant layer 40 is preferably lower than the melting point of the base layer 10. In this case, the packaging film 100 can be easily processed into a packaging container.

[0054] The thickness of the sealant layer 40 may be 50 μm or more, or may be 100 μm or more. When the thickness of the sealant layer 40 is 50 μm or more, when the packaging films 100 are bonded together with the sealant layer 40 to produce a packaging container, the packaging container can easily obtain sufficient seal strength and excellent self-supporting property. The thickness of the sealant layer 40 may be 180 μm or less, 150 μm or less, or 100 μm or less.

[0055] (5) Adhesive layer In the packaging film 100, the base material layer 10, the barrier layer 30, and the sealant layer 40 are laminated by a dry lamination method, an extrusion lamination method, or the like. That is, the base material layer 10, the barrier layer 30, and the sealant layer 40 are bonded together by an adhesive layer.

[0056] When the adhesive layer is formed by the dry lamination method, it can be formed by using an adhesive. Specifically, the adhesive layer is formed by applying an adhesive by a coating method such as roll coating, gravure roll coating, kiss coating, or a printing method such as gravure printing, offset printing, or transfer printing, and then drying the adhesive. The amount of adhesive used (mass per unit area of ​​adhesive layer) is not particularly limited, but is preferably 0.1 to 10 g / m in dry state. 2 and may be 1 to 5 g / m 2 may be also possible. It is preferable to use a polyurethane adhesive as the adhesive. In this case, excellent flexibility and bendability can be imparted to the adhesive layer. In addition, by using a polyurethane adhesive, the processability such as lamination and printing can be easily improved. As the polyurethane-based adhesive, for example, an adhesive containing a polyether polyurethane-based resin, a polyester polyurethane-based resin, or a polyacrylate polyurethane-based resin as a main component can be used.

[0057] The adhesive may be of any of the following types: water-based, solution-based, emulsion-based, dispersion-based, two-component curing, and solventless types. The adhesive may be in any form, such as a film, a sheet, a powder, or a solid. The reaction mechanism of the adhesive is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat welding type, a heat compression type, and the like. From the viewpoint of reducing the environmental impact, the adhesive is preferably a biomass adhesive. Here, the biomass adhesive refers to an adhesive containing components obtained from biological resources (biomass) such as cotton, pulp, rice bran, vegetable oil, and angiosperm seeds.

[0058] As the adhesive, an adhesive that imparts barrier properties to the adhesive layer (barrier adhesive) may be used.

[0059] When the adhesive layer is formed by the extrusion lamination method, it is formed by using an adhesive resin. The adhesive resin is a heat-sealable adhesive thermoplastic resin, and may be any resin that can be melted by heat and fused to each other, and may be, for example, an acid-modified polyolefin resin obtained by modifying a polyolefin resin such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (linear) low-density polyethylene, polypropylene, ethylene-propylene copolymer, methylpentene polymer, polyethylene or polypropylene with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, or the like, or the like.

[0060] The thickness of the adhesive layer can be appropriately determined depending on the purpose, but may be within the range of 1 to 100 μm.

[0061] (6) Light shielding layer The light-shielding layer contains a light-shielding pigment. The absorbance of the light-shielding pigment is lower than the absorbance of the absorption peak of the resin in the near-infrared wavelength region where the absorption peak of the resin contained in the base layer 10 and the sealant layer 40 appears. When both the resins contained in the base layer 10 and the sealant layer 40 are polyolefin resins, the near-infrared wavelength region may be 1600 to 1800 nm. When the polyolefin resin is a polyethylene resin or a polypropylene resin, the near-infrared wavelength region may be 1700 to 1800 nm.

[0062] The light-blocking pigment may be either a black pigment or a non-black pigment, but is preferably a black pigment. Since the black pigment has high absorbency for ultraviolet and visible light, it can effectively block ultraviolet and visible light, and can suppress deterioration and fading of the contents contained in the packaging container obtained by using the packaging film 100.

[0063] Examples of black pigments include azo pigments, azomethine pigments, melanin pigments, and isoindoline pigments. These can be used alone or in combination of two or more. These black pigments have high transmittance to near-infrared rays and low absorbance in the near-infrared wavelength region, so that when near-infrared spectroscopic analysis is performed on the packaging film 100, the absorption peak of the resin contained in the packaging film 100 in the near-infrared wavelength region can be more easily confirmed, and the resin contained in the packaging film 100 can be more easily identified. An azo pigment is a pigment having an azo group in the molecule, and may further have an azomethine group.

[0064] The content of the light-shielding pigment in the light-shielding layer may be 1% by mass or more, 5% by mass or more, or 10% by mass or more.

[0065] In the packaging film 100, at least one of the base layer 10, the printed layer 20, the barrier layer 30, and the sealant layer 40 may include a light-shielding layer. When at least one of the base layer 10, the printed layer 20, the barrier layer 30, and the sealant layer 40 includes a layer containing a light-shielding pigment, that layer functions as a light-shielding layer.

[0066] Among these, it is preferable that the printed layer 20 includes a light-shielding layer. Since the printed layer 20 usually includes a colorant, if the printed layer 20 includes a light-shielding pigment as a colorant, deterioration of the properties of the printed layer 20 can be reduced. Furthermore, when the printed layer 20 includes a light-shielding pigment, it is not necessary to include a light-shielding pigment in the base layer 10, the barrier layer 30, and the sealant layer 40, so that deterioration of the performance of the base layer 10, the barrier layer 30, and the sealant layer 40 can be suppressed. Furthermore, since the printed layer 20 is disposed at a position far from the sealant layer 40, which is the innermost surface of the packaging container, when the printed layer 20 includes a light-shielding pigment, the effect of the light-shielding pigment on the contents in the packaged product is reduced. In addition, when the printed layer 20 includes a light-shielding layer, the printed layer 20 may be composed of only a light-shielding layer, or may be composed of a laminate including a light-shielding layer and a non-light-shielding layer. An example of the non-light-shielding layer is a white ink layer including a white pigment.

[0067] The light-shielding layer may be included in the sealant layer 40. Here, when the sealant layer 40 is composed of a laminate including an inner layer, an intermediate layer, and an outer layer in this order from the substrate layer 10 side, it is preferable that the outer layer is not a light-shielding layer. That is, it is preferable that at least one of the inner layer and the intermediate layer is a light-shielding layer. In this case, since the outer layer does not contain a light-shielding pigment, it is possible to reduce the influence of the light-shielding pigment bleeding out from the outer layer and being mixed into the contents in the packaged product. In addition, since the outer layer does not contain a light-shielding pigment, it is possible to suppress the deterioration of the heat sealability of the sealant layer 40, and it is also possible to maintain the seal strength of the packaging container. In particular, it is preferable that only the intermediate layer be the light-shielding layer, in which case the laminate strength becomes more stable when the sealant layer 40 is laminated to another film such as the barrier layer 30.

[0068] (7) Packaging film In the packaging film 100, the resins contained in the base material layer 10, the barrier base material, and the sealant layer 40 are preferably all polyolefin-based resins. In this case, the recyclability of the packaging film 100 is further improved.

[0069] The content of the polyolefin resin is preferably 80% by mass or more, and more preferably 85% by mass or more, based on the total mass of the packaging film 100. The upper limit of the polyolefin resin content is not particularly limited, but from the viewpoint of recyclability, it can be set to 98% by mass. The polyolefin resin may be a polyethylene resin or a polypropylene resin.

[0070] The thickness of the packaging film 100 is not particularly limited and may be 50 to 500 μm.

[0071] <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 given the same reference numerals, and duplicated explanations will be omitted. As shown in Fig. 2, the packaged product 400 includes a packaging container 300 and a content C contained in the packaging container 300. The packaging container 300 shown in Fig. 2 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 40 facing each other.

[0072] Since the light-shielding layer of the packaging film 100 contains a light-shielding pigment, the packaged product 400 can have light-shielding properties and can suppress deterioration of the quality of the contents C due to light. In addition, in the near-infrared wavelength region where the absorption peaks of the resins contained in the base layer 10 and the sealant layer 40 of the packaging film 100 appear, the absorbance of the light-shielding pigment is lower than the absorbance of the absorption peak. Therefore, when near-infrared spectroscopy is performed on the packaging container 300 left after opening the packaging product 400 and removing the contents C, the absorption peak of the resin can be confirmed in the near-infrared wavelength region where the absorption peaks of the resins contained in the base layer 10 and the sealant layer 40 appear, and the resins contained in the base layer 10 and the sealant layer 40 can be easily identified. As a result, the packaging product 400 can be easily recycled relative to the packaging container 300. Furthermore, in the near-infrared wavelength region where the absorption peaks of the resins contained in the base layer 10 and the sealant layer 40 appear, the absorbance of the light-shielding pigment is lower than the absorbance of the absorption peaks, so that the absorption of the near-infrared light is suppressed, the thermal load on the packaging container 300 in a high-temperature environment is reduced, and excellent shape retention is achieved, thereby suppressing deterioration of the appearance of the packaged product 400.

[0073] The packaging container 300 can also be obtained by folding one packaging film 100 and heat-sealing the periphery of the packaging film 100 with the sealant layers 40 facing each other.

[0074] The packaging container 300 shown in FIG. 2 is a four-sided pouch, but the packaging container of the present disclosure is not limited to four-sided pouches and can be used for various pouches such as three-sided pouches, standing pouches, gusset pouches, standing pouches, pouches with stoppers, gusset pouches, and retort pouches, as well as packaging containers such as sachets and gussets, and tubes such as laminated tubes.

[0075] The content C is not particularly limited, and examples of the content C include food, liquid, medicine, and electronic parts.

[0076] <Summary of this Disclosure> The outline of this disclosure is as follows. [1] A packaging film comprising a base layer and a sealant layer, the packaging film further comprising a light-shielding layer, the light-shielding layer containing a light-shielding pigment, the light-shielding pigment having an absorbance lower than an absorbance of an absorption peak in a near-infrared wavelength region in which an absorption peak of a resin contained in the base layer and the sealant layer appears. [2] The packaging film according to [1], wherein the resins contained in the base layer and the sealant layer are polyolefin resins, and the near-infrared wavelength region is 1600 to 1800 nm. [3] The packaging film described in [1] or [2], further comprising a barrier layer between the base layer and the sealant layer. [4] The packaging film described in [3], wherein the barrier layer comprises a barrier substrate and an inorganic layer formed on one side of the barrier substrate. [5] The packaging film according to any one of [1] to [4], further comprising a printed layer, the printed layer having the light-shielding layer. [6] The packaging film according to any one of [1] to [5], wherein the sealant layer has the light-shielding layer. [7] The packaging film according to any one of [1] to [6], wherein the light-blocking pigment comprises a black pigment. [8] The packaging film according to [6], wherein the black pigment comprises at least one selected from the group consisting of an azo pigment, an azomethine pigment, a melanin pigment, and an isoindoline pigment. [9] A packaging container obtained by using the packaging film according to any one of [1] to [8].

[10] [9] A packaging container according to the present invention; and a content contained within the packaging container. EXAMPLES

[0077] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to these examples.

[0078] Example 1 First, a 20 μm-thick biaxially oriented polypropylene film (hereinafter also referred to as "OPP film"; product name "U-1"; manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was prepared as a barrier substrate, and a 30 nm-thick vapor-deposited layer of silicon oxide was formed as an inorganic layer on this OPP film to obtain a barrier layer.

[0079] On the other hand, a 20 μm thick OPP film (product name "U-1", manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was prepared as a base layer, and a dry lamination adhesive was applied to one side of the base layer and dried to a thickness of 3 μm to form a first adhesive layer, thereby obtaining a first laminate (base layer (OPP) / first adhesive layer). A two-component reactive polyester polyurethane resin (product name "A626", manufactured by Mitsui Chemicals Co., Ltd.) was used as the dry lamination adhesive.

[0080] Then, the barrier substrate of the barrier layer and the first adhesive layer of the first laminate were bonded together to obtain a second laminate (substrate layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer)).

[0081] Next, a dry lamination adhesive was applied to the surface of the deposition layer of the second laminate and dried to a thickness of 3 μm to form a second adhesive layer, thereby obtaining a third laminate (base layer (OPP) / first adhesive layer / barrier layer (OPP / deposition layer) / second adhesive layer). A two-component reactive polyester polyurethane resin (product name "A626", manufactured by Mitsui Chemicals, Inc.) was used as the dry lamination adhesive.

[0082] Then, a multilayer body consisting of a 20 μm thick white polyethylene (PE) layer containing LLDPE and titanium oxide as a sealant layer, a 20 μm thick black polyethylene (PE) layer (light-shielding layer) containing LLDPE and a black pigment (product name "Chromofine Black A1103", manufactured by Dainichiseika Chemicals Mfg. Co., Ltd., an azo pigment having an azo group and an azomethine group) as a light-shielding pigment, and a 20 μm thick white PE layer containing LLDPE and titanium oxide was co-extruded and attached to the surface of the second adhesive layer of the third laminate by a film-forming machine. At this time, in the black PE layer as the light-shielding layer, the black pigment was mixed in a ratio of 5 parts by mass to 100 parts by mass of LLDPE.

[0083] In this way, a packaging film (base layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (white PE layer / black PE layer (light-shielding layer) / white PE layer)) was obtained.

[0084] Example 2 A third laminate (substrate layer (OPP) / white ink layer / printed layer (white ink layer / light-shielding layer) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer) was produced in the same manner as in Example 1, except that a white ink layer containing a white pigment (titanium oxide) and a light-shielding layer containing a resin made of a vinyl chloride-vinyl acetate copolymer were sequentially formed between an OPP film (product name "U-1", manufactured by Mitsui Chemicals Tohcello Co., Ltd.) as a substrate layer and the first adhesive layer, in that order from the substrate layer side. At this time, the black pigment was mixed in a ratio of 20 parts by mass with respect to 100 parts by mass of the resin in the light-shielding layer. Then, a 100 μm-thick LLDPE layer made of LLDPE (product name "TCX", manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was attached as a sealant layer to the surface of the second adhesive layer of the third laminate. In this way, a packaging film (substrate layer (OPP) / printed layer (white ink layer / light-shielding layer) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (LLDPE)) was obtained.

[0085] Example 3 A multilayer structure consisting of a 20 μm thick white polypropylene (PP) layer containing unstretched polypropylene CPP (product name "GL-C", manufactured by Mitsui Chemicals Tohcello Co., Ltd.) and titanium oxide, a 20 μm thick black polypropylene (PP) layer (light-shielding layer) containing CPP and a black pigment (product name "Chromofine Black A1103", manufactured by Dainichi Seikagaku Kogyo Co., Ltd.), and a 20 μm thick white PP layer containing CPP and titanium oxide was co-extruded and bonded together, and a packaging film (base layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (white PP layer / black PP layer (light-shielding layer) / white PP layer)) was obtained in the same manner as in Example 1, except that the black pigment was blended in the black PP layer in a ratio of 5 parts by mass per 100 parts by mass of CPP.

[0086] Example 4 A packaging film (base layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (CPP)) was obtained in the same manner as in Example 2, except that unoriented polypropylene CPP (product name "GL-C", manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was used as the sealant layer.

[0087] Example 5 The second laminate (substrate layer (HDPE) / first adhesive layer / barrier layer (HDPE / vapor deposition layer)) was prepared in the same manner as in Example 1, except that a 32 μm thick unstretched high-density polyethylene film (product name "HD", manufactured by Tamapoly Co., Ltd.) was used as the barrier substrate, and a 30 μm thick unstretched polyethylene film (product name "HD", manufactured by Tamapoly Co., Ltd.) was used as the substrate layer. On the other hand, 23 parts by mass of a solvent in which ethyl acetate and methanol were mixed at a mass ratio of 1:1 was mixed with 16 parts by mass of "Maxive C93T" manufactured by Mitsubishi Gas Chemical Co., Ltd. and 5 parts by mass of "Maxive M-100" manufactured by Mitsubishi Gas Chemical Co., Ltd. to prepare adhesive A, which is an epoxy adhesive. Then, this adhesive A was applied to the deposition layer with a wire bar to form a coating film, and the coating film was dried at 60°C to form a barrier adhesive layer (thickness: 3 μm) with a thickness of 3 μm as the second adhesive layer, and a third laminate (base layer (HDPE) / first adhesive layer / barrier layer (HDPE / deposition layer) / second adhesive layer (barrier adhesive layer)) was obtained. Then, a sealant layer was formed on the surface of the second adhesive layer in the same manner as in Example 1. In this way, a packaging film (base layer (HDPE) / first adhesive layer / barrier layer (HDPE / vapor deposition layer) / second adhesive layer (barrier adhesive layer) / sealant layer (white PE layer / black PE layer (light-shielding layer) / white PE layer)) was obtained.

[0088] Example 6 A second laminate (substrate layer (HDPE) / printed layer (white ink layer / light-shielding layer) / first adhesive layer / barrier layer (HDPE / vapor deposition layer)) was produced in the same manner as in Example 2, except that a 32 μm thick unstretched high-density polyethylene film (product name "HD", manufactured by Tamapoly Co., Ltd.) was used as the barrier substrate, and a 30 μm thick unstretched polyethylene film (product name "HD", manufactured by Tamapoly Co., Ltd.) was used as the substrate layer. Then, in the same manner as in Example 5, a barrier adhesive layer was formed as a second adhesive layer on the vapor deposition layer, and in the same manner as in Example 2, an LLDPE layer was formed as a sealant layer on the surface of the second adhesive layer. In this way, a packaging film (base layer (HDPE) / printed layer (white ink layer / light-shielding layer) / first adhesive layer / barrier layer (HDPE / vapor deposition layer) / sealant layer (LLDPE)) was obtained.

[0089] Comparative Example 1 A packaging film (substrate layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (white PE layer / black PE layer (light-shielding layer) / white PE layer)) was prepared in the same manner as in Example 1, except that carbon black was blended as a black pigment into the black polyethylene layer of the sealant layer.

[0090] Comparative Example 2 A packaging film (substrate layer (OPP) / printed layer (white ink layer / light-shielding layer) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (LLDPE)) was prepared in the same manner as in Example 2, except that carbon black was blended as a black pigment in the light-shielding layer of the printed layer.

[0091] Comparative Example 3 A packaging film (substrate layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (white PP layer / black PP layer (light-shielding layer) / white PP layer)) was prepared in the same manner as in Example 3, except that carbon black was blended into the sealant layer as a black pigment.

[0092] Comparative Example 4 A packaging film (substrate layer (OPP) / first adhesive layer / barrier layer (OPP / vapor deposition layer) / second adhesive layer / sealant layer (CPP)) was produced in the same manner as in Example 4, except that carbon black was blended as a black pigment in the light-shielding layer of the printed layer.

[0093] Comparative Example 5 A packaging film (base layer (HDPE) / first adhesive layer / barrier layer (HDPE / vapor deposition layer) / second adhesive layer (barrier adhesive layer) / sealant layer (white PE layer / black PE layer (light-shielding layer) / white PE layer)) was prepared in the same manner as in Example 5, except that carbon black was blended as a black pigment into the black polyethylene layer of the sealant layer.

[0094] Comparative Example 6 A packaging film (base layer (HDPE) / printed layer (white ink layer / light-shielding layer) / first adhesive layer / barrier layer (HDPE / vapor deposition layer) / sealant layer (LLDPE)) was produced in the same manner as in Example 6, except that carbon black was blended as a black pigment in the light-shielding layer of the printed layer.

[0095] <Results of near-infrared spectroscopy of packaging film> The packaging films of the examples and comparative examples were subjected to near-infrared spectroscopic analysis using a spectrophotometer (product name "UV-3600 Plus", manufactured by Shimadzu Corporation). As a result, in the packaging films of Examples 1 to 6, absorption peaks corresponding to polypropylene and polyethylene were observed in the near-infrared wavelength region of 1600 to 1800 nm. In contrast, in the packaging films of Comparative Examples 1 to 6, no absorption peaks corresponding to polypropylene and polyethylene were observed in the near-infrared wavelength region of 1600 to 1800 nm. Therefore, it was found that in the packaging films of Examples 1 to 6, the absorbance of the black pigment in the light-shielding layer was lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peaks of the resins contained in the base layer and sealant layer appear. In contrast, in the packaging films of Comparative Examples 1 to 6, it was found that the absorbance of the black pigment in the light-shielding layer was lower than the absorbance of the absorption peak in the near-infrared wavelength region where the absorption peaks of the resins contained in the base layer and sealant layer appear.

[0096] <Evaluation> The packaging films of Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated for recyclability and shape retention as follows.

[0097] (1) Recyclability As a result of near-infrared spectroscopy of the packaging film, when absorption peaks corresponding to polypropylene and polyethylene were observed in the near-infrared wavelength region of 1600 to 1800 nm, it was marked as "good" since it was possible to distinguish the resin and recycling could be easily performed, and when absorption peaks corresponding to polypropylene and polyethylene were not observed, it was marked as "bad" since it was difficult to distinguish the resin and recycling could not be easily performed. The results are shown in Table 1.

[0098] (2) Shape retention (Standing pouch production) Using the packaging films of Examples 1 to 6 and Comparative Examples 1 to 6, standing pouches were produced as follows. That is, a rectangular packaging film (front film) measuring 12 cm long by 10 cm wide, a rectangular packaging film (back film) measuring 12 cm long by 10 cm wide, and a rectangular packaging film (bottom film) measuring 10 cm wide by 6 cm deep were prepared. The upper parts of the front film and the back film were overlapped, and the bottom film was folded and sandwiched between the lower parts of the front film and the back film. Next, the sealant layers of the front film and the back film were bonded together at the upper edge, left edge, and right edge of the upper parts of the front film and the back film, and the peripheral parts of the bottom film and the sealant layers were bonded together at the lower edge, left edge, and right edge of the lower parts of the front film and the back film to produce a standing pouch. At this time, the heat seal width was 0.5 cm from the edge.

[0099] (evaluation) The standing pouches prepared as described above were stored in a thermostatic chamber at about 90°C for 30 minutes, and then taken out and evaluated for deformation due to softening. Standing pouches that showed no deformation were rated as having excellent shape retention and were marked as "Good," while standing pouches that showed deformation were marked as "Poor." The results are shown in Table 1.

[0100] [Table 1]

[0101] From the results shown in Table 1, it was found that the packaging films of Examples 1 to 6 have superior recyclability and superior shape retention even in a high temperature environment compared to the packaging films of Comparative Examples 1 to 6. In addition, the packaging films of Examples 1 to 6 and Comparative Examples 1 to 6 contain a black pigment, and therefore can be said to have light blocking properties. From the above, it has been confirmed that the packaging film of the present disclosure has light-blocking properties, can be easily recycled, and has excellent shape retention even in high-temperature environments. [Explanation of symbols]

[0102] 10...base material layer, 20...printed layer, 30...barrier layer, 40...sealant layer, 100...packaging film, 300...packaging container, 400...packaged product, C...contents.

Claims

1. A packaging film comprising a base layer and a sealant layer, the packaging film further comprising a light-shielding layer, the light-shielding layer containing a light-shielding pigment, the light-shielding pigment having an absorbance lower than an absorbance of an absorption peak in a near-infrared wavelength region in which an absorption peak of a resin contained in the base layer and the sealant layer appears.

2. the resin contained in the base layer and the sealant layer is a polyolefin resin, The packaging film according to claim 1, wherein the near-infrared wavelength region is 1600 to 1800 nm.

3. The packaging film of claim 1 , further comprising a barrier layer between the substrate layer and the sealant layer.

4. The packaging film according to claim 3 , wherein the barrier layer comprises a barrier substrate and an inorganic layer formed on one side of the barrier substrate.

5. Further comprising a printing layer, The packaging film according to claim 1 , wherein the printed layer comprises the light-shielding layer.

6. The packaging film of claim 1 , wherein the sealant layer comprises the light-blocking layer.

7. The packaging film of claim 1 , wherein the light-blocking pigment comprises a black pigment.

8. The packaging film according to claim 7 , wherein the black pigment comprises at least one selected from the group consisting of an azo pigment, an azomethine pigment, a melanin pigment, and an isoindoline pigment.

9. A packaging container obtained by using the packaging film according to any one of claims 1 to 8.

10. The packaging container according to claim 9 , and a content contained within the packaging container.

Images