Packaging materials, packaging containers and lids

Abstract

To provide a packaging material having a designability of high level based on metallic gloss without using a metal layer.SOLUTION: A packaging material has a configuration in which at least a plastic film, a glossy printed layer, and a sealant layer are laminated in this order from an outer layer side, and the glossy printed layer includes a binder resin and metal scales, and the metal scales have an average thickness of 0.02 to 1.00 μm, and an aspect ratio defined by [Average length / Average thickness] of 5 to 75.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a packaging material, a packaging container, and a lid. [Background technology]

[0002] Packaging materials are sometimes decorated with a high-luminance metallic luster in order to give the packaged items a high-class or luxurious appearance and to create a beautiful appearance. As such a decorative means, for example, a metal layer such as a metal vapor deposition film or a metal foil is generally formed.

[0003] However, packaging materials using metal layers have problems such as increased costs, metal vapor deposition films among metal layers have problems of poor production efficiency because they cannot be produced in-line with other layers constituting the packaging material, and metal foils among metal layers have problems of being difficult to handle. Furthermore, when packaging material using a metal layer is heated in a microwave oven, the microwaves inside the microwave oven are reflected off the surface of the metal layer, creating the risk of sparks causing the microwave oven to break down or cause an accident, and there is also the problem that the contents inside the packaging container cannot be heated sufficiently.

[0004] For this reason, for example, Patent Document 1 proposes a packaging material in which a glossy layer is formed from an ink agent containing a high-brightness aluminum paste of a predetermined concentration, instead of a metal layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-81589 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, packaging materials in which a glossy layer is formed using aluminum paste as in Patent Document 1 often lack the metallic luster, and cannot necessarily be said to have a high level of design.

[0007] The present invention has been made to solve the above-mentioned technical problems, and aims to provide a packaging material that has a high level of design due to its metallic luster without using a metal layer, as well as a packaging container and a lid body that use the packaging material. [Means for solving the problem]

[0008] That is, the present invention provides the following [1] to [3]. [1] A packaging material having a configuration in which at least a plastic film, a glossy printing layer, and a sealant layer are laminated in this order from the outer layer side, the glossy printing layer contains a binder resin and metal flakes, and the metal flakes have an average thickness of 0.02 to 1.00 μm and an aspect ratio defined as [average length / average thickness] of 5 to 75. [2] A packaging container, at least a portion of which is formed from the packaging material described in [1] above. [3] A lid body formed from the packaging material described in [1] above. Effect of the Invention

[0009] According to the present invention, it is possible to provide a packaging material, a packaging container, and a lid that have a high level of designability due to metallic luster without using a metal layer. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a layered structure of a packaging material of the present invention. [Diagram 2] FIG. 1 is a schematic cross-sectional view showing an example of a layered structure of a packaging material of the present invention. [Diagram 3] FIG. 1 is a schematic cross-sectional view showing an example of a layered structure of a packaging material of the present invention. [Figure 4] 2 is an image diagram of a cross section of a glossy printing layer 3a in Example 1. FIG. [Diagram 5] 1 is an image diagram of a cross section of a glossy printed layer 3a of Comparative Example 1. FIG. [Figure 6] FIG. 2 is a cross-sectional view showing an example of a pouch for use in a microwave oven among the packaging containers of the present invention. [Figure 7] FIG. 2 is a top view showing an example of a lidded container among the packaging containers of the present invention. [Figure 8] 8 is a cross-sectional view taken along line IV-IV of FIG. 7. [Figure 9] FIG. 2 is a schematic cross-sectional view showing another example of the layered structure of the packaging material of the present invention. [Figure 10] 1 is a schematic plan view showing another example of a microwave pouch among the packaging containers of the present invention. FIG. [Figure 11] 11 is a cross-sectional view taken along the line XI-XI of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The packaging material of the present invention, and the packaging container and lid using the packaging material will be described in detail below. In this specification, the expression "AA to BB" as a numerical range means "AA or more and BB or less."

[0012] [Packaging material] The packaging material of the present invention is a packaging material having a configuration in which at least a plastic film, a glossy printing layer, and a sealant layer are laminated in this order from the outer layer side, and the glossy printing layer contains a binder resin and metal flakes, and the metal flakes have an average thickness of 0.02 to 1.00 μm and an aspect ratio defined as [average length / average thickness] of 5 to 75.

[0013] <Layer structure> 1 to 3 show schematic diagrams of the layered structure in the thickness direction of the packaging material 1 of the present invention. In Fig. 1 to 3, the upper side is the outer layer side and the lower side is the inner layer side. The packaging material 1 has at least a plastic film 2, a glossy print layer 3a, and a sealant layer 4 laminated in this order from the outer layer side, and may include other layers as constituent layers. For example, as shown in Figures 1 to 3, an intermediate base material layer 5 may be laminated on both sides between a glossy printing layer 3a and a sealant layer 4 via an adhesive layer 6. As shown in Figure 2, a picture printing layer 3b may be provided on the outer layer side of the glossy printing layer 3a, or as shown in Figure 3, a picture printing layer 3b may be provided in parallel with the glossy printing layer 3a. As shown in Figure 3, a solid printing layer 3d may be provided on the inner layer side of the glossy printing layer 3a.

[0014] Furthermore, the packaging material 1 may have a gas barrier layer (not shown) formed between the plastic film 2 and the glossy print layer 3a, or between the glossy print layer 3a and the sealant layer 4. Specifically, the packaging material of the present invention can have the following laminated structure, starting from the outer layer side: In addition, " / " indicates the boundary between each layer. (1) Plastic film / glossy printing layer / intermediate substrate layer / sealant layer (2) Plastic film / gas barrier layer / glossy printing layer / sealant layer (3) Plastic film / gas barrier layer / glossy printing layer / intermediate substrate layer / sealant layer (4) Plastic film / glossy printing layer / gas barrier layer / intermediate substrate layer / sealant layer In order to make the glossy print layer 3 visible from the outside, the layers formed on the outer side of the glossy print layer 3a are optically transparent.

[0015] <Plastic film> The plastic film 2 serves as a base material on the outer layer side of the packaging material 1, and is made of a light-transmitting material so that the glossy print layer 3a can be visually recognized from the outside. Specifically, polyolefin resins such as polyethylene (PE) and polypropylene (PP), cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymer (AS) resins, acrylonitrile-butadiene-styrene copolymer (ABS) resins, poly(meth)acrylic resins, polycarbonate resins, polyvinyl alcohol resins, ethylene-vinyl alcohol copolymer (EVOH), saponified ethylene-vinyl ester copolymers, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyamide resins such as various nylons (Ny), polyurethane resins, acetal resins, cellulose resins, and polyvinylidene chloride resins (PVDC). The plastic film may be uniaxially or biaxially stretched. It may also be a composite film in which two or more of the above resin films are laminated. These plastic films may be formed by an inflation method or a melt extrusion coating method.

[0016] From the viewpoint of heating in a microwave oven or retort treatment, the plastic film is preferably one having excellent heat resistance. Examples of resins constituting the plastic film having excellent heat resistance include polyester resins and polyamide resins. Specific examples of plastic films having excellent heat resistance include polyester films alone, polyamide films alone such as nylon, and composite films containing at least one of polyester films and polyamide films. Examples of the composite film include co-extrusion stretched films having a structure of PET / Ny / PET and PET / Ny from the outer layer side. In addition, it is also preferable to combine at least one of polyester films and polyamide films with at least one of ethylene-vinyl alcohol copolymer films and polyvinylidene chloride films as the composite film.

[0017] The thickness of the plastic film is not particularly limited and can be appropriately set depending on the application of the packaging material, but is usually preferably about 5 to 50 μm, more preferably 10 to 40 μm, and even more preferably 12 to 25 μm.

[0018] The plastic film preferably has a total light transmittance of 85% or more, more preferably 90% or more, as measured by JIS K7361-1:1997, and preferably has a haze of 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less, as measured by JIS K7136:2000.

[0019] The arithmetic mean roughness Ra of both surfaces of the plastic film is preferably 0.1 μm or less, more preferably 0.05 μm or less, at a cutoff value of 0.8 mm, measured according to JIS B0601: 1994. By setting Ra of both surfaces of the plastic film within the above-mentioned range, the design can be improved.

[0020] <Glossy printing layer> The packaging material of the present invention has a glossy print layer between the plastic film and the sealant layer. The glossy printed layer 3a may be present on the entire surface of the packaging material as shown in Figures 1 and 2, or may be present on only a portion of the packaging material as shown in Figure 3. Also, as shown in Figure 2, a pattern printed layer 3b may be present on a portion of the outer layer side of the glossy printed layer 3a. Also, as shown in Figure 3, the glossy printed layer 3a and the pattern printed layer 3b may be present side by side at the same position in the thickness direction of the packaging material. Furthermore, the glossy print layer 3a may be used to form pictures such as letters, figures, symbols, designs, patterns, and the like.

[0021] In addition, the glossy printed layer of the packaging material of the present invention contains a binder resin and metal flakes, and the metal flakes have an average thickness of 0.02 to 1.00 μm and an aspect ratio defined as [average length / average thickness] of 5 to 75.

[0022] <<Metal scales>> The metal flakes have an average thickness of 0.02 to 1.00 μm and an aspect ratio, defined as [average length / average thickness], of 5 to 75. The packaging material of the present invention uses such metal flakes, and thus has a high level of designability due to the metallic luster.

[0023] Fig. 4 is an image of a cross section of a glossy printed layer 3a containing metal flakes that satisfy the above conditions (cross section of the glossy printed layer 3a of Example 1), and Fig. 5 is an image of a cross section of a glossy printed layer 3a containing metal flakes that do not satisfy the above conditions (cross section of the glossy printed layer 3a of Comparative Example 1). As shown in Fig. 4, the cross section of the glossy printed layer 3a containing metal flakes that satisfy the above conditions has a high proportion of inclined metal flakes y, while as shown in Fig. 5, the cross section of the glossy printed layer 3a containing metal flakes that do not satisfy the above conditions has a low proportion of inclined metal flakes y. Comparing the angular distribution of reflected light when external light is incident on the glossy printed layer 3a in Figures 4 and 5, the angle of reflected light is concentrated in a narrow range near the direction of specular reflection of the incident light in the glossy printed layer 3a in Figure 5, whereas the angular range of reflected light is wider in the glossy printed layer 3a in Figure 4. Note that the solid arrows in Figures 4 and 5 indicate incident light, the dotted arrows indicate specularly reflected light of the incident light, and the dashed-dotted arrows indicate the angular range of reflected light. That is, a glossy printed layer containing metal flakes that do not satisfy the above conditions can be perceived as having a metallic luster when observed in a very narrow range near the direction of specular reflection, but cannot be perceived when observed away from the direction of specular reflection. On the other hand, a glossy printed layer containing metal flakes that satisfy the above conditions can be perceived as having a high level of design based on metallic luster, even when observed away from the direction of specular reflection, because the brightness based on the reflection of the glossy printed layer can be detected. In addition, most environments in which humans observe packaging materials are indoor environments, which often have multiple light sources. In other words, humans observe packaging materials based on reflected light from multiple light sources. However, even if multiple light sources exist and multiple directions of specular reflection exist, the angle range near each specular reflection direction is narrow. Therefore, even if multiple light sources exist, a glossy printing layer containing metal flakes that do not satisfy the above conditions has a narrow angle range in which the metallic luster can be perceived. On the other hand, a glossy printing layer containing metal flakes that satisfy the above conditions allows reflected light to be observed that is away from the vicinity of the specular reflection direction. Therefore, in an environment where multiple light sources are present (i.e., an environment where there are many specular reflection directions), the metallic luster can be perceived even when the packaging material is observed from any angle, thereby achieving an extremely high level of design. In other words, the packaging material of the present invention, which contains metal flakes that satisfy the above conditions, is effective in all environments (such as environments in which luxury goods such as cosmetics are displayed using spot light sources, and indoor environments where multiple light sources are present), but is particularly effective in indoor environments where multiple light sources are present (especially retail stores such as supermarkets, convenience stores, and drugstores).

[0024] In addition, since the packaging material of the present invention has a glossy printed layer formed on the inner layer side of the plastic film, if the surface shape of the plastic film is smooth, the surface shape of the glossy printed layer seen from the viewer's side will be smooth. And, even though the surface shape of the glossy printed layer seen from the viewer's side is smooth, the above-mentioned effects can be obtained. That is, even though the packaging material of the present invention looks nearly smooth to the viewer, the metallic luster can be felt at a wide angle, and a design that cannot be achieved with conventional packaging materials can be realized.

[0025] If the average thickness of the metal flakes is less than 0.02 μm, the metal flakes will be difficult to tilt within the glossy printed layer, making it difficult to impart a high level of design. If the average thickness of the metal flakes is more than 1.00 μm, the metal flakes will be excessively tilted within the glossy printed layer, causing the angle range of the reflected light to become too wide, reducing the brightness of the reflected light and making it difficult to impart a high level of design. Preventing the metal flakes from tilting excessively within the glossy printed layer also leads to improved suitability for use in microwave ovens. The average thickness of the metal flakes is preferably 0.05 to 0.75 μm, and more preferably 0.10 to 0.50 μm.

[0026] If the aspect ratio of the metal flakes is less than 5, the metal flakes will be tilted excessively in the glossy printed layer, causing the angle range of the reflected light to become too wide, reducing the brightness of the reflected light and making it difficult to impart a high level of design. Suppressing the metal flakes from tilting excessively in the glossy printed layer also leads to improved suitability for use in microwave ovens. In addition, if the aspect ratio of the metal flakes is more than 75, it will be difficult for the metal flakes to tilt in the glossy printed layer, making it difficult to impart a high level of design. The aspect ratio of the metal flakes is preferably 10-45, and more preferably 15-30.

[0027] The average length of the metal flakes is not particularly limited as long as the average thickness and aspect ratio satisfy the above ranges, but is preferably 0.2 to 50 μm, more preferably 1 to 20 μm, and even more preferably 2 to 10 μm. By making the average length 0.5 μm or more, aggregation can be easily suppressed, and by making the average length 50 μm or less, the metal flakes are less likely to come into contact with other metal flakes when tilted in the glossy printing layer, making it easier to improve suitability for use in a microwave oven.

[0028] The average length of the metal flakes is determined as the average length of any 20 metal flakes observed from the planar direction of the packaging material using an optical microscope or an electron microscope. The length of one metal flake means the maximum length of one metal flake in the planar direction. The average thickness of the metal flakes is determined as the average thickness of any 20 metal flakes observed by observing the cross section of the packaging material with an optical microscope or an electron microscope. The thickness of one metal flake is determined by dividing the cross section of one metal flake into five regions of equal length in the longitudinal direction, measuring the thickness of the center of each region (t1, t2, t3, t4, t5), and averaging t1 to t5.

[0029] Examples of materials for the metal flakes include metals and alloys such as aluminum, gold, silver, brass, titanium, chromium, nickel, nickel chromium, and stainless steel. The metal flakes can be obtained, for example, by (i) peeling off a thin metal film formed by vacuum-depositing the above-mentioned metal or alloy onto a plastic film from the plastic film, and crushing and stirring the peeled thin metal film, or (ii) mixing a powder of the above-mentioned metal or alloy with a solvent, and spreading and / or grinding the powder using a media stirring mill, ball mill, attritor, or the like.

[0030] In the case of the above method (i), the thickness, length and aspect ratio of the metal flakes can be adjusted by the thickness of the thin metal film, as well as the time and strength of the grinding and stirring, etc. In the case of the above method (ii), the thickness, length and aspect ratio can be adjusted by the particle size of the raw metal powder, the size of the bearing balls, the time and strength of the spreading and / or grinding, etc.

[0031] The metal flakes are preferably non-leafing type metal flakes. In the case of non-leafing type metal flakes, the metal flakes are uniformly dispersed in the glossy printed layer during the formation process, so that even if the metal flakes are tilted in the glossy printed layer, the spacing between the metal flakes is prevented from narrowing to the extent that sparks or overheating occurs, thereby preventing deterioration of the packaging material when used in a microwave oven. Non-leafing type metal flakes are metal flakes that have not been surface-treated with stearic acid, and examples of such metal flakes include metal flakes that have been surface-treated with a surface treatment agent other than stearic acid, such as oleic acid, and metal flakes that have not been surface-treated.

[0032] The metal flakes are preferably surface-coated with a resin, which prevents the spacing between the metal flakes from narrowing to such an extent that sparks or overheating may occur even if the metal flakes are tilted in the glossy printed layer, thereby preventing the packaging material from deteriorating when used in a microwave oven. In addition, when a packaging container that has been subjected to high-temperature treatment at 130°C or higher (so-called "high retort treatment") is heated in a microwave oven, holes may appear in the part with the glossy printed layer. This is thought to be because the coating film is softened by the high-temperature treatment at 130°C or higher, causing the metal flakes to flow in the coating film, resulting in areas where the distance between the metal flakes narrows, and sparks and overheating occur in these areas when heated in a microwave oven. However, metal flakes with a resin-coated surface and non-leafing type metal flakes (especially resin-coated metal flakes) are preferable in that they are more likely to prevent sparks and overheating in the glossy printed layer and deterioration of the packaging material when heated in a microwave oven after high retort treatment.

[0033] The type of resin constituting the resin coat is not particularly limited as long as it is a resin having insulating properties, and a general-purpose resin can be used. From the viewpoint of heat resistance, the resin constituting the resin coat is preferably a cured product of a curable resin composition.

[0034] The curable resin composition preferably contains a monomer and / or oligomer having two or more polymerizable double bonds in the molecule. For the purpose of adjusting the viscosity, the curable resin composition may contain a monomer and / or oligomer having one polymerizable double bond in the molecule, such as a radically polymerizable unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, itaconic acid, or fumaric acid, an ester of the unsaturated carboxylic acid, or a nitrile of the unsaturated carboxylic acid. The curable composition preferably contains a general-purpose thermal polymerization initiator or photopolymerization initiator.

[0035] Examples of monomers and oligomers having two or more polymerizable double bonds in the molecule include divinylbenzene, allylbenzene, diallylbenzene, epoxidized 1,2 polybutadiene, ethylene glycol di(meth)acrylate, 1,3 butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, (meth)acrylic modified polyester, (meth)acrylic modified polyether, (meth)acrylic modified urethane, (meth)acrylic modified epoxy, trimethylolpropane tri(meth)acrylate, tetramethylolpropane tri(meth)acrylate, tetramethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate.

[0036] In the metal flakes having a resin-coated surface, the amount of resin coating is preferably 3 to 40 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of the metal flakes. By setting the amount of the resin coat to 3 parts by mass or more, it is possible to easily improve microwave resistance, and by setting the amount of the resin coat to 40 parts by mass or less, it is possible to prevent a decrease in metallic gloss.

[0037] Resin-coated metal flakes can be produced, for example, by the methods described in JP-A-62-253668, JP-A-64-40566, JP-A-2003-213157, and JP-A-2012-241039.

[0038] The content of metal flakes in the glossy printing layer is preferably 3 to 50 mass% of the total solids content of the glossy printing layer, more preferably 5 to 40 mass%, and even more preferably 10 to 30 mass%, in order to strike a balance between enhancing the aesthetic appearance through metallic luster and suppressing the occurrence of sparks and localized overheating when heating in a microwave oven. The packaging material of the present invention is advantageous in that it can provide a high level of design even if the content of metal flakes is relatively small.

[0039] The glossy print layer may contain a colorant to enhance the design. As the colorant, general-purpose dyes and pigments (for example, inorganic pigments such as yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, and cobalt blue, and organic pigments or dyes such as quinacridone red, isoindolinone yellow, and phthalocyanine blue) can be used. Note that it is preferable not to use colorants with low insulating properties such as carbon black.

[0040] The content of the colorant is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, and even more preferably 30 to 50 parts by mass, relative to 100 parts by mass of the metal flakes.

[0041] The glossy print layer preferably contains inorganic particles having an average primary particle diameter of 1 to 100 nm (hereinafter, sometimes referred to as "inorganic fine particles"). By containing inorganic fine particles in the glossy printing layer, the metal flakes are prevented from sinking below the glossy printing layer and tend to be uniformly arranged within the glossy printing layer. Therefore, even if the metal flakes are tilted in the glossy printing layer, the spacing between the metal flakes is prevented from becoming so narrow that it would cause sparks or overheating, thereby preventing deterioration of the packaging material when used in a microwave oven. The average primary particle diameter of the inorganic fine particles is more preferably 2 to 50 nm, and further preferably 5 to 30 nm. The average primary particle diameter of the inorganic fine particles is determined as the mass average value d50 in particle size distribution measurement by laser light diffraction method.

[0042] The content of the inorganic fine particles in the glossy print layer is preferably 10 to 70 parts by mass, more preferably 15 to 50 parts by mass, and even more preferably 20 to 35 parts by mass, relative to 100 parts by mass of the metal flakes.

[0043] Examples of inorganic fine particles include silica, alumina, zirconia, and titania. Among these, silica, which has excellent transparency, is preferable. In addition, silica and alumina are also preferable in that they have excellent insulating properties and can improve microwave oven resistance.

[0044] From the viewpoint of being able to sufficiently impress with metallic gloss, the thickness of the glossy print layer is preferably 0.5 to 10.0 μm, more preferably 0.8 to 7.0 μm, and even more preferably 1.0 to 5.0 μm.

[0045] The glossy print layer may contain a pearl pigment to enhance metallic gloss. Examples of the pearl pigment include white pearl pigments, interference pearl pigments, and colored pearl pigments.

[0046] The glossy printing layer 3a, as well as the picture printing layer 3b and solid printing layer 3d described below (hereinafter, these may be collectively referred to as the "printed layers"), can be formed, for example, on a plastic film 2, a sealant layer 4, etc., by a known printing method such as gravure printing, offset printing, letterpress printing, silk screen printing, etc., using known inks. The printed layer is preferably formed by reverse printing on the inner surface of the plastic film 2 or the gas barrier layer. Alternatively, the printed layer may be formed by performing front printing on the outer surface of the intermediate base material layer 5 or the sealant layer 4, and then laminating the intermediate base material layer 5 or the sealant layer 4 to the plastic film 2 or the gas barrier layer via an adhesive layer. Printing may be performed over the entire surface of the packaging material 1, or may be performed partially.

[0047] The ink for forming the printing layer is usually made of a vehicle consisting of a binder resin and a solvent as the main component, to which a colorant such as a dye or pigment is added and mixed (the glossy printing layer 3a contains metal flakes as an essential component). The colorant for the printing layer may be used alone or in combination of two or more types.

[0048] Examples of binder resins include polyolefin resins such as polyethylene resins and chlorinated polypropylene resins, poly(meth)acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate copolymers, polystyrene resins, styrene-butadiene copolymers, vinylidene fluoride resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyvinyl butyral resins, polybutadiene resins, polyester resins, polyamide resins, alkyd resins, epoxy resins, unsaturated polyester resins, thermosetting poly(meth)acrylic resins, melamine resins, urea resins, polyurethane resins, phenolic resins, xylene resins, maleic acid resins, cellulose resins such as nitrocellulose, ethyl cellulose, acetylbutyl cellulose, and ethyloxyethyl cellulose, rubber resins such as chlorinated rubber and cyclized rubber, petroleum resins, and natural resins such as rosin and casein.

[0049] In addition, the binder resin of the glossy print layer preferably has a melting point of 130° C. or higher in order to prevent the metal flakes from flowing within the glossy print layer during high retort. The melting point of the binder resin in the glossy print layer is more preferably 140° C. or higher, and even more preferably 150° C. or higher. In this specification, a resin having a melting point of AA°C or higher includes not only resins whose melting points are observed at AA°C or higher, but also resins whose melting points are not observed below AA°C or at AA°C or higher.

[0050] The binder resin of the glossy print layer is preferably a non-hydrophilic resin. By using a non-hydrophilic resin as the binder resin for the glossy print layer, it is possible to more easily prevent sparks and localized overheating when heated in a microwave oven. The non-hydrophilic resin means a resin that, when a coating film is formed using only the resin, has a contact angle of 90 degrees or more with pure water. The contact angle of the non-hydrophilic resin is preferably 110 degrees or more, more preferably 130 degrees or more, and even more preferably 150 degrees or more.

[0051] The printing layer forming ink may further contain, as necessary, any additives such as fillers, stabilizers, plasticizers, antioxidants, light stabilizers such as ultraviolet absorbers, dispersants, thickeners, drying agents, lubricants, antistatic agents, crosslinking agents, etc.

[0052] The solvent contained in the ink of the printing layer may be any solvent used in ordinary pigment inks, and examples of such solvents include alcohol-based solvents such as methanol, ethanol, normal propanol, isopropanol, and propylene glycol monomethyl ether, ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester-based solvents such as methyl acetate, ethyl acetate, and normal propyl acetate, aliphatic hydrocarbon-based solvents such as normal hexane, normal heptane, and normal octane, alicyclic hydrocarbon-based solvents such as cyclohexane, methylcyclohexane, and cycloheptane, aromatic solvents such as toluene and xylene, mineral spirits, etc. These may be used alone or in combination of two or more.

[0053] <Pattern printing layer> The packaging material of the present invention may have a pattern printed layer 3b between the plastic film 2 and the sealant layer 4. The pattern printed layer 3b may be formed, for example, on the outer layer side of the glossy printed layer 3a (FIG. 2), or may be formed so as to be parallel to the glossy printed layer 3a at the same position in the thickness direction of the packaging material (FIG. 3).

[0054] The picture-printed layer 3b may be any printed layer formed with a color that can be distinguished from the glossy printed layer 3a, and is a broad concept including characters, figures, symbols, designs, patterns, solid printing, etc. The colorant for the picture-printed layer 3b may be a general-purpose dye or pigment (for example, inorganic pigments such as yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, cobalt blue, etc., or organic pigments or dyes such as quinacridone red, isoindolinone yellow, phthalocyanine blue, etc.). The thickness of the picture print layer is not particularly limited, but is preferably about 1.0 to 5 μm, and more preferably 1.0 to 3 μm.

[0055] <Solid print layer> As shown in FIG. 3, the packaging material of the present invention preferably has a solid print layer 3d on the inner layer side of the glossy print layer 3a. By forming a solid print layer, depending on the type of packaged item, the appearance of the packaged item can be improved. The color of the solid print layer is not particularly limited, but it is preferably a white color that does not impair the color of the glossy print layer and has excellent concealing properties. In other words, the solid print layer is preferably a white solid print layer. In addition, the white solid print layer may contain a small amount of dyes and pigments other than the white pigment as a colorant to adjust the color.

[0056] The solid print layer may be formed on only a portion of the surface of the packaging material, but from the viewpoint of easily achieving the above-mentioned effects, it is preferable to form it on the entire surface of the packaging material, as shown in FIG. The colorant for the solid print layer can be a general-purpose colorant. In the case of a white solid print layer, it is preferable to use one or more types of colorant selected from white pigments such as titanium dioxide, barium sulfate, magnesium oxide, calcium carbonate, zinc oxide, and white lead. The thickness of the solid print layer is not particularly limited, but is preferably about 1.0 to 5 μm, and more preferably 1.0 to 3 μm.

[0057] <Sealant layer> The inner surface of the sealant layer 4 comes into direct contact with the packaged product, and serves to protect the packaged product. In particular, when the packaging material 1 is used to form a package container for liquid products, the sealant layer 4 is preferably made of a material that is impermeable to the liquid product. In addition, the innermost layer of the sealant layer 4 preferably has heat sealability in order to form a pouch.

[0058] Examples of materials constituting the sealant layer 4 include polyolefin resins such as low-density PE (LDPE), linear low-density PE (LLDPE), medium-density PE (MDPE), high-density PE (HDPE), ethylene-vinyl acetate copolymer, propylene homopolymer, ethylene-propylene block copolymer, and ethylene-propylene random copolymer, and one or more of these resins can be used. The sealant layer 4 may be composed of a single layer or may be composed of two or more layers. Note that the sealant layer is preferably a non-stretched film made of the above-mentioned resin in order to suppress shrinkage during heat sealing.

[0059] From the viewpoint of heating in a microwave oven or retort processing, in order to enhance heat resistance, it is preferable that the sealant layer is composed of a resin having excellent heat resistance. Specifically, propylene-based resins such as propylene homopolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer, and HDPE are preferred. In addition, it is preferable to use the above propylene-based resins according to the purpose. Specifically, when cold resistance is important (for example, packaging material for frozen foods), ethylene-propylene block copolymers are preferable, when transparency is important, ethylene-propylene random copolymers are preferable, and when heat resistance is important, propylene homopolymers are preferable. In addition, in the case of containers equipped with an automatic steaming mechanism, ethylene-propylene block copolymers are preferable from the viewpoint that the seal strength decreases at high temperatures, making it easier to release steam.

[0060] Furthermore, when the packaging material 1 is used to form a lid for a lidded container, the sealant layer 4 preferably has easy peel properties. Easy peelability refers to the property that, for example, when the sealant layer 4 of the packaging material 1 of the lid of a lidded container is joined to the container body, the lid can be easily peeled off from the container body when the lidded container is opened. A sealant layer having easy peel properties can be formed by mixing two or more resins, one resin (resin with good adhesion to the container body) with another resin (resin with poor adhesion to the container body and incompatible with the one resin). Such resins vary depending on the material of the container, so it is not possible to make a general statement, but when the container is made of PP, the sealant layer can be formed from a resin that is a mixture of one resin (resin with good adhesion to the container body) (PP) and one or more other resins (resins with poor adhesion to the container body and incompatible with the one resin) selected from PE, polybutene, and polystyrene, thereby imparting easy peel properties to the PP container. The sealant layer may have a multi-layer structure, and easy peel properties may be imparted only to the side of the sealant layer that is joined to the container body (the innermost layer in the packaging material).

[0061] The thickness of the sealant layer 4 is not particularly limited and is appropriately set depending on the application of the packaging material 1 and the type and properties of the packaged item, but is usually preferably about 10 to 200 μm. In the case of a pouch (particularly a retort pouch), the thickness of the sealant layer 4 is more preferably 20 to 150 μm, and further preferably 30 to 100 μm. In the case of a container with a lid, the thickness of the sealant layer 4 is more preferably 15 to 80 μm, and further preferably 20 to 60 μm.

[0062] <Gas barrier layer> The gas barrier layer can be provided anywhere between the plastic film 2 and the sealant layer 4, as necessary. The gas barrier layer plays a role in blocking the transmission of oxygen, water vapor, and the like between the item to be packaged in the packaging material 1 and the external environment of the packaging material 1. The gas barrier layer may also be provided with light-shielding properties that block the transmission of visible light, ultraviolet rays, and the like. The gas barrier layer may be composed of only one layer, or may be composed of multiple layers of two or more layers. When the gas barrier layer is formed on the outer layer side of the glossy print layer 3a, like the plastic film 2, it is made of a light-transmitting material so that the glossy print layer 3a can be visually recognized from the outside.

[0063] The gas barrier layer can be formed as a deposition film or a coating film by a known method. The surface on which the gas barrier layer is formed may be subjected to a surface treatment in advance from the viewpoint of improving the adhesion of the gas barrier layer. Examples of the surface treatment include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidizing agent treatment, application of an anchor coat agent, etc.

[0064] [Vapor-deposited film] The vapor deposition film, which is an example of the gas barrier layer, can be formed from inorganic substances such as silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), etc., or oxides of these substances. Among these, when the packaging material is for use in a microwave oven, inorganic oxides such as silicon oxide, aluminum oxide, magnesium oxide, etc. are preferred from the viewpoint of enabling the packaged food or the like to be sufficiently heated by the microwaves of the microwave oven. Examples of methods for forming a vapor-deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0065] The thickness of the vapor-deposited film varies depending on the material used, the required gas barrier performance, etc., but is usually preferably about 5 to 200 nm, more preferably 5 to 150 nm, and even more preferably 10 to 100 nm. In the case of inorganic oxides such as silicon oxide and aluminum oxide, the thickness is preferably about 5 to 100 nm, more preferably 5 to 50 nm, and even more preferably 10 to 30 nm.

[0066] [Gas barrier coating film] As an example of the gas barrier layer, a gas barrier coating film represented by the general formula R 1 n M(OR 2 ) m(In the formula, R 1 , R 2 is an organic group having 1 to 8 carbon atoms, and M is a metal atom. n is an integer of 0 or more, m is an integer of 1 or more, and n+m is the atomic valence of M. The film can be formed by applying a coating liquid obtained by polycondensing at least one alkoxide represented by the formula (I) and a polyvinyl alcohol resin and / or an ethylene-vinyl alcohol copolymer by a sol-gel method in the presence of a sol-gel method catalyst, an acid, water, and an organic solvent, and then heat-treating the film at 50 to 300° C. for 0.05 to 60 minutes. The coating method can be, for example, roll coating such as a gravure roll coater, spray coating, spin coating, dipping, brushing, bar coating, applicator, etc. After one or more coatings, the dry thickness of the coating film is preferably about 0.01 to 30 μm, more preferably 0.05 to 20 μm, and even more preferably 0.1 to 10 μm. From the viewpoint of improving the gas barrier property, the gas barrier coating film is preferably formed on the surface of the vapor-deposited film.

[0067] Considering the specific configuration of the gas barrier layer, the packaging material of the present invention can have the following laminated configurations (1') to (4') in order from the outer layer side, where " / " indicates the boundary between layers. (1') Plastic film / vapor deposition film / glossy printing layer / sealant layer (2') Plastic film / deposition film / gas barrier coating film / glossy printing layer / sealant layer (3') Plastic film / glossy printing layer / vapor deposition film / intermediate substrate layer / sealant layer (4') Plastic film / glossy printing layer / gas barrier coating film / vapor deposition film / intermediate substrate layer / sealant layer

[0068] <Intermediate base material layer> The intermediate substrate layer is a layer that is provided as necessary for the purpose of improving the strength and processability of the packaging material 1, changing the texture of the packaging material, or serving as a substrate for forming other layers. Examples of materials constituting the intermediate substrate layer include plastic films and paper. In the case of a plastic film, the same plastic film as that formed on the outer layer side of the glossy print layer 3a described above can be used. In the case of paper, it is possible to impart properties such as shapeability, flex resistance, and rigidity to the packaging material 1, and for example, highly sizable bleached or unbleached kraft paper, pure white roll paper, paperboard, various types of processed paper, etc. can be used. The basis weight of the paper is usually 50 to 600 g / m 2 Preferably, it is about 60 to 500 g / m 2 , and more preferably 70 to 450 g / m 2 When the packaging material 1 is used for soft packaging, the thickness is 150 g / m 2 For paper container applications such as paper cups and liquid paper containers, the thickness is preferably less than 200 g / m 2 More preferably, it is equal to or greater than this.

[0069] In consideration of heating in a microwave oven or retort processing, in order to increase the heat resistance of the packaging material, the intermediate base material layer is preferably one having excellent heat resistance. Specific examples of intermediate base material layers having excellent heat resistance include paper and various plastic films exemplified as the plastic films having excellent heat resistance.

[0070] <Adhesive layer> In the packaging material 1, from the viewpoint of improving the bonding strength between the layers, the constituent layers may be laminated via an adhesive layer 6. The adhesive layer can be formed by a method using a known dry lamination adhesive. Examples of adhesives for dry lamination include polyvinyl acetate adhesives, polyacrylic ester adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, cellulose adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives such as urea resin and melamine resin, phenol resin adhesives, epoxy adhesives, polyurethane adhesives (for example, cured products of polyol and isocyanate compounds), reactive (meth)acrylic acid adhesives, rubber adhesives such as chloroprene rubber, nitrile rubber, styrene-butadiene rubber, silicone adhesives, and inorganic adhesives such as alkali metal silicates and low-melting point glasses.

[0071] <Thermosoftening resin layer> As shown in FIG. 9, the packaging material 1 may have a thermosoftening resin layer 7 in a partial area between the plastic film and the sealant layer. 9, the heat-softening resin layer 7 is formed in a part near the edge of the packaging material 1, and is made of a resin that has a certain strength in a temperature environment below room temperature but loses the certain strength in a high temperature environment, so that when the packaging container is heated in a microwave oven and the pressure inside the container increases, a part of the sealant layer breaks down and a part of the heat-softening resin layer breaks down at the interface or breaks down cohesively, allowing steam to escape. This will be described in detail in the second embodiment of the automatic steaming mechanism.

[0072] Thermosoftening resins, that is, resins that have a certain strength in a temperature environment below room temperature but lose the certain strength in a high temperature environment, include resins with a melting point of 60 to 110°C, preferably 60 to 90°C, and specifically include ethylene-vinyl acetate copolymer resins, polyamide, soluble cellulose, polyethylene wax, etc., and a mixed resin of polyamide, soluble cellulose, and polyethylene wax is preferred. As a resin containing polyamide, soluble cellulose, and polyethylene wax, MWOP varnish (softening point: 105°C) manufactured by DIC Graphics Corporation can be used.

[0073] The thickness of the thermosoftening resin layer is preferably 1 to 5 μm. By making the thickness of the thermosoftening resin layer 1 μm or more, the thermosoftening resin layer and the sealant layer can be easily destroyed when heated in a microwave oven. In addition, by making the thickness of the thermosoftening resin layer 5 μm or less, when the film-like packaging material is wound into a roll, it is possible to suppress the packaging material from stretching in that part due to the swelling occurring in the part.

[0074] The packaging material of the present invention described above can be used for various types of packaging materials, but since it can give the purchaser the impression of luxury of the contents, it can be suitably used as a packaging material for food or cosmetics, etc. Furthermore, since the packaging material of the present invention can impart a high level of design based on metallic luster even with a relatively small content of metal flakes, it does not encounter the problems of microwave heating that arise when a large amount of metal flakes are contained, and can be suitably used as a packaging material for microwave ovens.

[0075] [Packaging container] The packaging container of the present invention is at least partially formed from the packaging material of the present invention described above. By forming at least a part of a packaging container from the packaging material of the present invention, a packaging container with a luxurious feel due to its metallic luster can be obtained even if metal itself is not used. The packaging material of the present invention may be applied to any desired portion of a packaging container to which it is desired to impart a luxurious feel due to the metallic luster, and the entire packaging container may be formed from the packaging material, or alternatively, only a portion of the packaging container may be formed from the packaging material.

[0076] The type and use of the packaging container of the present invention are not particularly limited, but when selling the contents contained in the packaging container, the packaging container can impress upon the purchaser the luxury of the contents, and can be suitably used, for example, as a food container, a cosmetic container, etc. Examples of packaging containers include pouches and containers with lids, as well as cups and trays. These packaging containers include the above-mentioned packaging materials as a part of them. That is, these packaging containers may be formed of packaging materials that include paper as an intermediate base material layer. A specific example of the shape of the pouch is the shape of a pouch for use in a microwave oven shown in Fig. 6. The pouch may be a retort container (a container sterilized at high temperature and high pressure), or may be a packaging container for use in a microwave oven or a container other than a retort container. A specific example of the shape of a lidded container is one that has a container body having a storage section and a lid body joined to the container body so as to seal the storage section, and the lid body is formed from the packaging material. As described above, the packaging container can be suitably used for a microwave oven. The packaging container can also be used as a retort container. Of course, the packaging container can also be used as a retort container for a microwave oven.

[0077] When the packaging container is a container for use in a microwave oven or a retort container, the packaging material constituting the container preferably has a laminated structure of any one of the above-mentioned (1) to (4). In this case, the plastic film is preferably a polyester film alone, a polyamide film such as nylon, or a composite film containing at least one of a polyester film and a polyamide film. In this case, the intermediate substrate is preferably a polyester film alone, a polyamide film such as nylon alone, a composite film containing at least one of a polyester film and a polyamide film, or paper. In this case, the sealant layer is preferably made of a propylene-based resin such as a propylene homopolymer, an ethylene-propylene block copolymer, or an ethylene-propylene random copolymer, or HDPE. More specifically, in the case of a retort container or a container for use in a microwave oven, the packaging material constituting the container preferably has any one of the laminated structures (A1) to (A12) below. Note that " / " indicates the boundary between layers. In addition, in (A1) to (A12), PET and Ny are preferably stretched films.

[0078] (A1) PET / glossy printing layer / Ny / ethylene-propylene block copolymer (A2) PET / gas barrier layer / glossy printing layer / Ny / ethylene-propylene block copolymer (A3) PET / glossy print layer / gas barrier layer / Ny / ethylene-propylene block copolymer (A4) PET / glossy printing layer / PET / ethylene-propylene block copolymer (A5) PET / gas barrier layer / glossy printing layer / PET / ethylene-propylene block copolymer (A6) PET / glossy print layer / gas barrier layer / PET / ethylene-propylene block copolymer (A7) Co-extrusion stretched film (PET / Ny / PET) PET / glossy printing layer / PET / ethylene-propylene block copolymer (A8) Co-extrusion stretched film (PET / Ny / PET) / gas barrier layer / glossy printing layer / PET / ethylene-propylene block copolymer (A9) Co-extrusion stretched film (PET / Ny / PET) / glossy printing layer / gas barrier layer / PET / ethylene-propylene block copolymer (A10) PBT / glossy printing layer / Ny / ethylene-propylene block copolymer (A11) PBT / gas barrier layer / glossy printing layer / Ny / ethylene-propylene block copolymer (A12) PBT / glossy printing layer / gas barrier layer / Ny / ethylene-propylene block copolymer

[0079] In the case of containers for use in a microwave oven, the ethylene-propylene block copolymers constituting the sealant layers (A1) to (A12) above may be polyethylene resins such as LDPE, LLDPE, MDPE, and HDPE. When the automatic steam passing mechanism of the second embodiment described later is adopted in a microwave oven container, the above-mentioned heat-softening resin layer may be formed in a portion between the plastic film and the sealant layer.

[0080] (Pouch) Fig. 6 shows an example of a pouch which is one embodiment of the packaging container of the present invention. The pouch 10 in Fig. 6 is for use in a microwave oven and is a standing type pouch formed by heat sealing a body part 11 and a bottom part 12. As shown in Fig. 6, the body part 11 includes a pair of main sheets 13 consisting of a front main sheet 13a and a back main sheet 13b arranged opposite each other, and the vicinity of side edges 14 of the pair of overlapping main sheets 13 are heat sealed to each other. A bottom sheet 16 which forms the bottom part 12 is arranged between lower edges 15 of the pair of main sheets 13. A storage space 17 for storing contents is formed within the area surrounded by the pair of main sheets 13 and bottom sheet 16. The bottom sheet 16 is bent in a convex shape toward the storage space 17, and the vicinity of its peripheral edge is heat-sealed with the lower part of the overlapping main sheets 13. The bottom sheet 16 maintains the shape of the lower ends of the pair of main sheets 13, thereby imparting self-supporting properties to the pouch 10, making it possible to form a standing pouch. 6 has an opening 19 formed between upper edges 18 of front main sheet 13a and back main sheet 13b, and contents can be placed through opening 19. After the contents are placed inside, the packaging container can be sealed by heat sealing the vicinity of upper edge 18 where opening 19 is formed. When removing the contents from pouch 10, the vicinity of upper edge 18 is torn from notch 23 to open it.

[0081] The front main surface sheet 13a, the back main surface sheet 13b and the bottom surface sheet 16 of this pouch 10 can be formed from the packaging material 1. All of these sheets may be formed from the packaging material 1 having the glossy printed layer 3a containing metal flakes, or only any of the sheets that require metallic luster may be formed from the packaging material 1. Fig. 6 shows that the front main surface sheet 13a is formed from the packaging material 1 having a laminated structure as shown in Fig. 2, so as to have the glossy printed layer 3a and the picture printed layer 3b. In addition, sheets other than the sheet used for packaging material 1 may be, for example, packaging material 1 that does not have a glossy printed layer 3a containing metal flakes formed therein, or that does not include a printed layer.

[0082] (Automatic steaming mechanism) When the container is for use in a microwave oven, it is preferable that the container has an automatic steaming mechanism that automatically releases steam from within the storage space to the outside when the pressure inside the pouch increases due to steam generated by cooking the contents, such as food, thereby preventing the pouch from bursting. The automatic steaming mechanism is preferably formed near the periphery of the container.

[0083] A first embodiment of the automatic steaming mechanism will be described with reference to Fig. 6. The pouch for use in a microwave oven shown in Fig. 6 has a first unsealed area 21 that is not heat sealed near the side edge 14 near the upper side of the container (pouch). The first unsealed area 21 reaches the side edge 14 and has an opening 22. The first unsealed area 21 also protrudes toward the storage space 17. The heat-sealed portion 25 also protrudes toward the storage space 17 to surround the first unsealed area 21 protruding toward the storage space 17, forming a protruding portion 25a. More specifically, the first unsealed area 21 and the storage space 17 are separated, and the protruding portion 25a is formed so as to be connected to the heat-sealed portion 25 for sealing the pouch. 6, the automatic steam passing mechanism 20 is formed by the opening 22, the first unsealed area 21, and the heat sealed portion (projecting portion 25a) projecting toward the storage space 17. Specifically, when the pressure inside the container increases due to heating, the portion of the heat sealed portion 25 where the projecting portion 25a is located receives a strong load, and the portion of the projecting area 25 peels off first, so that the storage space 17 and the first unsealed area 21 communicate with each other, allowing steam to escape to the outside. Further details of the automatic steaming mechanism of the type shown in FIG. 6 are described in JP 2015-120550 A, JP 2016-74457 A, and JP 2016-74458 A.

[0084] 6, a second unsealed area 23 is formed on the side edge 14 opposite to the first unsealed area 21. The second unsealed area 23 is formed from the viewpoint of improving the yield of the formation of the openings 22 in the first unsealed area 21 when a plurality of retort containers 10 are continuously formed and then cut into one by one, and is not necessarily required to be formed.

[0085] A second embodiment of the automatic steam mechanism will be described with reference to FIGS. The packaging container (pouch) 10 shown in Fig. 10 is a pouch made by heat-sealing the periphery of the edge of the packaging material (a packaging material having a heat-softening resin layer in a part near the edge between a plastic film and a sealant layer) shown in Fig. 9. Fig. 11 is a cross-sectional view taken along XI-XI of the heat-sealed portion 25 around the edge of the packaging container 10 in Fig. 10. 10, the heat-softening resin layer 7 must be formed from the inner edge to the outer edge of the heat-sealed portion 25 for sealing the pouch in at least a portion of the heat-sealed portion 25 of the packaging container 10. The strength of the heat-softening resin layer 7 provided in such a position is reduced by being heated to a high temperature in a microwave oven. 11, when the heat-softening resin layer 7 is heated in a microwave oven or the like and the internal pressure of the packaging container 10 increases due to the expansion of the air inside the packaging container 10 or the water vapor contained in the contents, a part of the sealant layer 4 breaks, starting from an arbitrary point "A" of the sealant layer 4 near the inner edge of the heat-sealed portion 25, and a part of the heat-softening resin layer 7 undergoes interfacial peeling or cohesive failure (the broken line with symbol B indicates the imaginary line where the sealant layer 4 breaks and the imaginary line where the heat-softening resin layer 7 undergoes interfacial peeling or cohesive failure). As a result, air and water vapor escape from the broken point, and the internal pressure of the packaging container 10 can be reduced. The automatic steam passing mechanism of the second embodiment can also be applied to a lidded container described later.

[0086] For the packaging material constituting the container equipped with the second embodiment of the automatic steaming mechanism, it is preferable to select a resin that is easily disintegrated as the resin constituting the sealant layer. Specifically, LLDPE is preferable. Furthermore, the packaging material constituting the container equipped with the second embodiment of the automatic steaming mechanism is preferably made to have any one of the laminated structures (B1) to (B6) below. Note that " / " means the boundary between the layers. Furthermore, in (B1) to (B6), it is preferable that PET and Ny are stretched films.

[0087] (B1) PET / glossy print layer / thermosoftening resin layer / LLDPE (B2) PET / gas barrier layer / glossy print layer / thermosoftening resin layer / LLDPE (B3) PET / glossy print layer / gas barrier layer / thermosoftening resin layer / LLDPE (B4) Ny / glossy print layer / thermosoftening resin layer / LLDPE (B5) Ny / gas barrier layer / glossy print layer / thermosoftening resin layer / LLDPE (B6) Ny / glossy print layer / gas barrier layer / thermosoftening resin layer / LLDPE

[0088] (Container with lid) 7 and 8 show an example of an embodiment of the lidded container of the present invention. FIG. 7 is a top view, and FIG. 8 is a cross-sectional view taken along line IV-IV of FIG. 7. The lidded container 30 shown in FIGS. 7 and 8 includes a container body 32 in which a storage section 31 is formed, and a lid body 33 joined to the container body 32 so as to seal the storage section 31 of the container body 32. In FIG. 7, the shape of the container body 32 is substantially rectangular, but is not particularly limited. In addition, the method of forming the container body 32 is not particularly limited, and it may be, for example, a tray formed by injection molding or a container formed by deep drawing. Furthermore, since the material of the container body 32 is to be joined to the lid body 33, it is usually a thermoplastic resin such as PP or PET, and in particular, when it is a lidded container for use in a microwave oven, PP is preferably used from the standpoint of heat resistance, etc.

[0089] It is preferable that the lid body 33 of this lidded container 30 is formed from the packaging material 1 of the present invention. Note that Fig. 7 shows that the lid body 33 is formed so as to have a glossy printed layer 3a and a picture printed layer 3b in the packaging material 1 having a laminated structure as shown in Fig. 2.

[0090] From the viewpoint of making it easy to peel the lid 33 from the container body 32 and open the lidded container 30, it is preferable that the lid 33 has easy-peel properties, as described above in the explanation of the sealant layer 4 of the packaging material 1. The lid 33 and the container body 32 are joined together at a joining line 35 of the flange 34 of the container body 32. The joining line 35 may be formed by, for example, heat sealing the lid 33 and the flange 34 together, or may be formed by a separate component such as an adhesive layer.

[0091] When the covered container 30 is used in a microwave oven, it is preferable that the covered container 30 is equipped with an automatic steaming mechanism (a third embodiment of the automatic steaming mechanism) that automatically releases steam within the covered container 30 to the outside when the pressure within the covered container 30 increases due to steam generated by heating and cooking the contents, such as food, contained in the container body 32, thereby preventing the covered container 30 from bursting. For example, the flange portion 34 has a protruding portion 34a that protrudes toward the center of the container body 32, and the joining line 35 also has a protruding line 35a that is formed in a convex shape toward the center of the container along this protruding portion 34a. By forming the joining line 35 in this manner, the joining line 35 is easily peeled off from the protruding line 35a when the pressure inside the lidded container 30 increases due to heating, and the storage portion 31 of the container body 32 can be connected to the outside, allowing steam inside the lidded container 30 to escape to the outside. In the lidded container 30 shown in Figures 7 and 8, the protrusions 34a are formed on each of the opposing long sides of the flange portion 34, but it is not necessary for two protrusions 34a to be formed.

[0092] Furthermore, by using the packaging material shown in Figure 9 (a packaging material between the plastic film and the sealant layer and having a heat-softening resin layer in a portion near the edge) as the lid body 33 that constitutes the lidded container 30, steam can be allowed to escape when heated in a microwave oven for the same reasons as explained in the second embodiment of the automatic steaming mechanism described above.

[0093] <Cover> The lid of the present invention is formed from the packaging material of the present invention described above.

[0094] The packaging material constituting the lid body preferably has any one of the laminated structures (1) to (4) described above. Furthermore, when the lid is used as a microwave oven or retort container, it is preferable to use, as the plastic film, a polyester film alone, a polyamide film such as nylon, or a composite film containing at least one of a polyester film and a polyamide film. Furthermore, when the lid is used as a microwave oven or retort container, it is preferable to use, as the intermediate substrate layer, a polyester film alone, a polyamide film such as nylon alone, a composite film containing one or more of a polyester film and a polyamide film, or paper. In addition, when the lid is used as a microwave oven or retort container, it is preferable to use a film made of a resin that has both heat resistance and easy peel properties as the sealant layer. Such a film varies depending on the type of container, but when the container is made of a propylene-based resin, which is a general-purpose resin, it is preferable to use a film made of a resin that is a mixture of PP and one or more selected from PE, polybutene, and polystyrene. The sealant layer may be made of a multi-layer structure, and easy peel properties may be imparted only to the side of the sealant layer that is joined to the container body (the innermost layer in the packaging material).

[0095] More specifically, the packaging material constituting the microwave oven lid preferably has any one of the laminated structures (C1) to (C11) below. Note that " / " indicates the boundary between layers. In (C1) to (C11), PET and Ny are preferably stretched films. (C1) PET / glossy print layer / Ny / sealant layer with easy peel properties (C2) PET / gas barrier layer / glossy printing layer / Ny / sealant layer with easy peel properties (C3) PET / glossy print layer / gas barrier layer / Ny / sealant layer with easy peel properties (C4) PET / glossy print layer / PET / sealant layer with easy peel properties (C5) PET / gas barrier layer / glossy print layer / PET / sealant layer with easy peel properties (C6) PET / glossy print layer / gas barrier layer / PET / sealant layer with easy peel properties (C7) Ny / glossy print layer / Ny / sealant layer with easy peel properties (C8) Ny / gas barrier layer / glossy printing layer / Ny / sealant layer with easy peel properties (C9) Ny / glossy print layer / gas barrier layer / Ny / sealant layer with easy peel properties (C10)Ny / glossy printing layer / EVOH / sealant layer with easy peel properties (C11)Ny / EVOH / glossy printing layer / sealant layer with easy peel properties

[0096] When the configuration of the second embodiment of the automatic steam passage mechanism described above is adopted for the lid body, the above-mentioned heat-softening resin layer may be formed in a portion between the plastic film and the sealant layer. EXAMPLES

[0097] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[0098] 1. Preparation of packaging materials [Example 1] One surface of a 12μm thick plastic film (PET film, Ra of both surfaces is 0.05μm or less) was subjected to a corona discharge treatment, and then a 10nm thick silicon oxide vapor deposition film was formed.Furthermore, after a plasma treatment using a mixture of oxygen and argon gas, a coating liquid mainly composed of ethyl silicate and polyvinyl alcohol was applied with a gravure roll coater to form a gas barrier coating film with a dry thickness of 300nm. Next, the gold ink for a glossy printing layer described below was gravure printed on the entire surface of the gas barrier layer and dried to form a glossy printing layer with a dry thickness of 1.5 μm. Next, a white pigment ink was gravure printed on the entire surface of the glossy printed layer and dried to form a white background printed layer having a dry thickness of 1.5 μm. Next, an intermediate substrate layer (oriented Ny, thickness 15 μm) was attached to the surface of the white background color printed layer by dry lamination using a polyurethane adhesive. Next, a sealant layer (CPP, a single-layer film of an ethylene-propylene block copolymer, thickness 70 μm) was attached to the surface of the intermediate base material layer by dry lamination using a polyurethane adhesive, thereby obtaining the packaging material of Example 1. The packaging material of Example 1 has, from the outer layer side, a plastic film, a vapor deposition film, a gas barrier coating film, a glossy printed layer, a white background color printed layer, an adhesive layer, an intermediate substrate layer, an adhesive layer, and a sealant layer.

[0099] <Gold ink for glossy printing layers> 9 parts by weight of a composition containing metal flakes and mineral spirits (Metal flake content is 85% by mass) (Metal flakes: non-leafing type aluminum flakes, aspect ratio 10, average thickness 0.68 μm) Organic yellow pigment 3 parts by weight ·Inorganic fine particles 2 parts by mass (Silica, average primary particle size: 20 nm) Binder resin 20 parts by weight (Polyurethane resin, melting point 140℃) Solvent 1 (mixture of propylene glycol monomethyl ether, n-propyl acetate, ethyl acetate, and isopropanol) 70 parts by weight Solvent 2 (mineral spirits) 6 parts by weight

[0100] [Examples 2 to 7], [Comparative Examples 1 to 5] Packaging materials of Examples 2 to 7 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that the metal flakes in the gold ink for the glossy printing layer were changed to those shown in Table 1.

[0101] 2. Evaluation 2-1. Beautiful appearance with metallic luster In a room equipped with multiple fluorescent lights on the ceiling, the curtains were closed to block external light, and under the illumination of the multiple fluorescent lights, the packaging materials of Examples 1 to 7 and Comparative Examples 1 to 5 were observed from the plastic film side while tilted in various directions, and the aesthetic appearance due to the metallic luster was evaluated. Twenty subjects evaluated the product and calculated the average scores, with a score of 3 for products in which the metallic luster could be felt in every direction and the aesthetic appearance based on the metallic luster was good, a score of 2 for products that were neither good nor bad, and a score of 1 for products in which the metallic luster could not be felt in many directions and the aesthetic appearance based on the metallic luster was insufficient. The results are shown in Table 1. <Evaluation criteria> AA: Average score of 2.7 or higher A: Average score is between 2.5 and 2.7 B: Average score is between 1.5 and 2.5 C: Average score is less than 1.5

[0102] 2-2. Microwave resistance Twenty pouches having the structure shown in FIG. 6 were produced using the packaging materials of Examples 1 to 7 and Comparative Example 5, and sealed. The 20 pouches were subjected to high retort treatment at 135°C for 30 minutes using a batch-type spray-type (hot water shower-type) retort device, and then heated in a microwave oven at 600W for 2 minutes. After heating in the microwave oven, samples that showed no holes were rated as "A," and samples that showed at least one hole were rated as "C." The results are shown in Table 1.

[0103] [Table 1]

[0104] From the results in Table 1, it can be confirmed that the packaging materials of Examples 1 to 7 have a high level of design based on metallic luster from all directions without using a metal layer. It can also be confirmed that the packaging materials of Examples 1 to 7 can suppress deterioration due to microwave heating after high retort processing. [Explanation of symbols]

[0105] 1 Packaging material 2. Plastic film 3a Glossy printing layer 3b Pattern printing layer 3d white background printing layer 4 Sealant Layer 5. Intermediate substrate layer 6 Adhesive layer 7 Thermoplastic resin layer 10 Packaging containers 11 Torso 12 Bottom 13 Main sheet 14 Side edges 15 Lower edge 16 Bottom sheet 17 Containment Space 18 Upper edge 19 Aperture 20 Automatic steaming mechanism 21 First unsealed area 22 Aperture 23 Second unsealed area 24 Notches 25 Heat seal section 25a Overhang 30 Container with lid 31 Storage unit 32 Container body 33 Lid 34 Flange section 35 Joint Line

Claims

1. A packaging material having a configuration in which at least a plastic film, a glossy printed layer, and a sealant layer are laminated in this order from the outer layer side, the glossy printed layer contains a binder resin and metal flakes, and the metal flakes have an average thickness of 0.02 to 1.00 μm and an aspect ratio defined by [average length / average thickness] of 5 to 75, and the glossy printed layer further contains inorganic particles having an average primary particle diameter of 1 to 100 nm.

2. 2. The packaging material according to claim 1, wherein the metal flakes have an average thickness of 0.05 to 0.75 μm and an aspect ratio defined as [average length / average thickness] of 10 to 45.

3. 3. The packaging material according to claim 1, wherein the metal flakes are non-leafing type metal flakes.

4. The packaging material according to any one of claims 1 to 3, which is for use in a microwave oven.

5. A packaging container, at least a part of which is formed from the packaging material according to any one of claims 1 to 3.

6. The packaging container of claim 5, wherein the packaging container is a pouch.

7. 6. The packaging container according to claim 5, which is a lidded container comprising a container body having a storage section and a lid body joined to the container body so as to seal the storage section, the lid body being formed from the packaging material.

8. The packaging container according to any one of claims 5 to 7, which is for use in a microwave oven.

9. The packaging container according to any one of claims 5 to 8, which is a retort container.

10. A lid body formed from the packaging material according to any one of claims 1 to 3.

Images