Packaging material and packaging container

Abstract

To provide a packaging material whose poor appearance is not generated by heat of a microwave oven, that has highly excellent appearance by metallic gloss, and microwave oven resistance, and to provide a packaging container using the packaging material.SOLUTION: A packaging material 100 comprises a gas-phase metal evaporated film 122 on at least a part of one surface of a substrate 110. The gas-phase metal evaporated film 122 comprises a plurality of island parts each made of metal, and a sea part situated between the island parts. An area per one island is 4,400 nm2 or more and 94,000 nm2 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a packaging material and a packaging container using the packaging material.

Background Art

[0002] From the viewpoint of producing a high-class and luxurious feeling for the object to be packaged and creating an aesthetic appearance, the packaging material may be decorated with a high-luminance metallic luster.

[0003] As a means of applying a metallic luster, for example, it is generally practiced to form a metal layer such as a metal vapor deposition film or a metal foil on a base material. However, when a packaging material using a metal layer is heated in a microwave oven, there is a risk of causing malfunctions or accidents in the microwave oven, such as sparks occurring in the microwave oven or microwaves being reflected on the surface of the metal layer. There is also a problem that the contents in the packaging container cannot be sufficiently heated.

[0004] On the other hand, Patent Document 1 describes that a packaging material having a high aesthetic appearance and being less likely to deteriorate even when heated by a microwave oven can be obtained by forming a gloss layer with an ink agent containing a high-luminance aluminum paste at a predetermined concentration.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] However, a packaging material having a gloss layer formed with an ink agent has microwave oven suitability, but has inferior glossiness compared to a metal layer and is inferior in design as a packaging material. The present invention has been made to solve the above problems, and provides a packaging material having excellent aesthetics due to metallic luster and resistance to a microwave oven, and not causing appearance defects or the like by heating in a microwave oven, and a packaging container using the packaging material.

Means for Solving the Problems

[0007] As a result of intensive studies by the present inventors, it has been found that by forming a vapor-deposited metal film having a specific fine structure, a packaging material having excellent metallic luster and microwave oven suitability can be obtained. Specifically, the specific fine structure is an "island structure" having a plurality of island portions formed by deposition and growth of vapor-deposited metal and sea portions located between the island portions when the surface is observed with an electron microscope.

[0008] Furthermore, the present inventors have found that when the area of one island portion is within a specific range, damage to the packaging material due to heating in a microwave oven can be suppressed, and the shape and aesthetics can be maintained even after heating, thereby completing the present invention.

[0009] In order to solve the above problems, the present invention provides the following [1] to

[11] . [1] A packaging material having a vapor-deposited metal film on at least a part of one surface of a base material, wherein the vapor-deposited metal film has a plurality of island portions made of metal and sea portions located between the island portions, and the area of each island portion is 4,400 nm 2 or more and 94,000 nm 2 or less. [2] The packaging material according to [1], wherein the vapor-deposited metal film is an indium vapor-deposited film or a tin vapor-deposited film. [3] The packaging material according to [1] or [2], having a bright printing layer on the one surface side of the base material, wherein the bright printing layer contains at least one of a pearl pigment and metal flakes. [4] The packaging material according to any one of [1] to [3], wherein the base material is a paper base material. [5] The packaging material according to [4], having an adhesive layer between the base material and the vapor-deposited metal film. [6] A packaging container formed from the packaging material according to any one of [1] to [5]. A packaging container which is a box formed of the packaging material according to [7], [4] or [5]. The packaging container according to [7], which is an outer packaging box of a pouch. The packaging material according to any one of [1] to [3], wherein the base material is a plastic film. A packaging container formed of the packaging material according to

[10] and [9]. A packaging container which is a pouch formed of the packaging material according to

[11] and [9]. A container with a lid, comprising a container body having a storage portion and a lid body joined to the container body so as to seal the storage portion, wherein the lid body is formed of the packaging material according to [9]. [Effects of the Invention]

[0010] According to the present invention, a packaging material having a good metallic luster and excellent in appearance can be obtained. Further, the packaging material can be heated by a microwave oven, and damage due to heating is suppressed, so that the shape and appearance of the packaging material can be maintained. [Brief Description of the Drawings]

[0011]

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Mode for Carrying Out the Invention

[0012] [Packaging Material] The packaging material of the present invention has a vapor-phase metal deposition film on at least a part of one surface of a base material. The vapor-phase metal deposition film has a plurality of island portions made of metal and a sea portion located between the island portions. The area per island portion is 4,400 nm 2 or more and 94,000 nm 2 or less.

[0013] In the present invention, either a paper base material or a plastic film can be applied to the base material. FIGS. 1 to 3 are schematic cross-sectional views showing an embodiment of the packaging material of the present invention. The packaging materials in FIGS. 1 to 3 are examples when a paper base material is used as the base material. When a packaging material using a paper base material is used as a packaging container, the paper base material is located on the inner layer side.

[0014] The packaging material 100 in FIG. 1 has a metal decoration portion 120 on a part of one surface of a base material (paper base material) 110. The metal decoration portion 120 is composed of a vapor-phase metal deposition film 122, a coloring layer 124 provided on the surface of the vapor-phase metal deposition film 122 opposite to the paper base material 110, and an adhesive layer 126 laminated. The metal decoration portion 120 is arranged such that the adhesive layer 126 is on the base material 110 side. In the present invention, a configuration without providing a coloring layer can also be adopted. Further, as shown in FIG. 1, a pattern printing layer 128 may be further formed on the coloring layer 124.

[0015] In the packaging material 100 of FIG. 1, a pattern printing layer 130 is formed on the surface side of the paper base material 110 where the metal decoration portion 120 is provided. In FIG. 1, the metal decoration portion 120 is provided on the pattern printing layer 130. However, the metal decoration portion 120 may be directly provided on the paper base material 110, and the pattern printing layer 130 and the metal decoration portion 120 may be provided in parallel within the plane of the paper base material 110. As shown in FIG. 1, a top coat layer 132 may be further formed on the pattern printing layer 130. In this case, the metal decoration portion 120 is provided on the top coat layer 132.

[0016] The packaging material 200 of FIG. 2 is a modification of FIG. 1 and has a glitter printing layer 134 on the paper base material 110. In the packaging material 200 of FIG. 2, the glitter printing layer 134 is disposed on the surface side where the metal decoration portion 120 is provided. In FIG. 2, the glitter printing layer 134 is provided on the pattern printing layer 130, and the metal decoration portion 120 is provided on the glitter printing layer 134. However, the present invention is not limited to the configuration of FIG. 2. For example, the glitter printing layer 134 and the pattern printing layer 130 may be provided in parallel within the plane of the paper base material 110. Also, the pattern printing layer 130, the glitter printing layer 134, and the metal decoration portion 120 may be provided in parallel within the plane of the paper base material 110.

[0017] The glitter printing layer 134 may be provided at a distance from the metal decoration portion 120, or may be provided adjacent to the metal decoration portion 120 as shown in FIG. 2. When the glitter printing layer 134 and the metal decoration portion 120 are adjacent, they can be integrated to form one pattern.

[0018] In the configuration of FIG. 2, a top coat layer 132 may be formed on the pattern printing layer 130 and the glitter printing layer 134.

[0019] The packaging material 300 in FIG. 3 has a metal decoration part 120 provided on a paper base material 110, and a pattern printing layer 130 is further provided on the metal decoration part 120. In the case of FIG. 3, the metal decoration part 120 is composed of a vapor-phase metal deposition film 122 and an adhesive layer 126. In this configuration, a top coat layer 120 may be formed on the pattern printing layer 130.

[0020] FIGS. 4 and 5 are schematic cross-sectional views showing an embodiment of the packaging material of the present invention. The packaging 100 material in FIGS. 4 and 5 is an example when a plastic film is used as the base material 410. When making a packaging material using a plastic film into a packaging container, the plastic film is located on the outer layer side and the sealant layer is located on the inner layer side. The packaging material 400 in FIG. 4 has a metal decoration part 420 on a part of one surface of the plastic film 410. The metal decoration part 420 in FIG. 4 is composed of a vapor-phase metal deposition film 422 and a coloring layer 424 provided on the side opposite to the plastic film 410 of the vapor-phase metal deposition film 422 (the outer layer side of the vapor-phase metal deposition film 422). In the present invention, a configuration without providing a coloring layer can also be adopted. An overcoat layer may be provided on the plastic film 410 and the metal decoration part 420.

[0021] The packaging material 400 in FIG. 4 has a pattern printing layer 430 formed on the side opposite to the surface of the plastic film 410 where the metal decoration part 420 is provided. A sealant layer 432 is formed on the surface of the pattern printing layer 430 opposite to the plastic film 410.

[0022] The packaging material 500 in FIG. 5 is a modified example of FIG. 4 and has a glitter printing layer 434 on the plastic film 410. The glitter printing layer 434 is arranged on the side opposite to the surface where the metal decoration part 420 is provided.

[0023] The glitter printing layer 434 may be provided at a distance from the location where the metal decoration part 420 is formed, or may be provided adjacent to it. When the glitter printing layer 434 and the metal decoration part 420 are adjacent, the two can be integrated to form one pattern.

[0024] Figure 6 is a perspective view when the packaging material of FIG. 1 is viewed from the outer layer side (top coat layer side). FIG. 6 is an example in which a pattern by printing is bordered by a metal decoration part. Reference numeral P is a pattern, and is, for example, a character, a figure, a number, a symbol, an animal, a character, or the like. In the packaging material 100, the metal decoration part 120 surrounds the pattern by the pattern printing layer 128, and further, a pattern printing layer 130 as a base is formed around the metal decoration part. As shown in FIG. 6, the metal decoration part 120 may surround the entire circumference of the pattern by the pattern printing layer 128, or may be formed so as to surround a part thereof.

[0025] Figure 7 is a perspective view when the packaging material of FIG. 2 is viewed from the outer layer side (top coat layer side). FIG. 7 is an example in which a part where a fluorescent printing layer and a vapor-phase metal deposition film are formed are integrated to form one pattern. Reference numeral Q is a pattern, and is, for example, a character, a figure, a number, a symbol, an animal, a character, or the like. In the packaging material 200, the fluorescent printing layer 134 surrounds the metal decoration part 120. Further, a pattern printing layer 130 is formed around the fluorescent printing layer 134. Particularly, when forming the metal decoration part by transfer as described later, if the vapor-phase metal deposition film and the fluorescent printing layer are adjacent to each other within the substrate surface, the three-dimensional effect of the metal decoration part is emphasized.

[0026] Note that the shape of the decoration, the arrangement of the metal decoration part, the pattern printing layer, and the fluorescent printing layer are examples, and the present invention is not limited thereto.

[0027] Hereinafter, the packaging material and the packaging container of the present invention will be described in detail. Note that the notation of the numerical range of "AA to BB" in this specification means "AA or more and BB or less".

[0028] 〔Packaging material using a paper substrate〕 <Paper substrate> Hereinafter, the configuration of each layer of the packaging material using a paper substrate will be described. The paper substrate is not particularly limited as long as it has formability, bend resistance, strength, etc. according to the packaging purpose. For example, various papers such as paper with strong sizing, bleached or unbleached, which is the main strength material, or pure white roll paper, kraft paper, cardboard, processed paper, milk carton paper, etc. can be used. When the packaging material is for microwave use, cardboard is usually used from the viewpoints of processability and use in a microwave. Examples of types of cardboard include those commonly used as cardboard for paper containers such as white cardboard, yellow cardboard, chipboard, and colored cardboard. Among these, white cardboards such as manila board paper and coated board paper are frequently used.

[0029] From the viewpoints of handleability and strength in printing, bending processing, etc., the thickness of the paper substrate is preferably 110 μm or more and 860 μm or less, and more preferably 260 μm or more and 640 μm or less. Also, from the viewpoints of handleability and strength in printing, bending processing, etc., the basis weight of the paper substrate is preferably 80 g / m 2 or more and 600 g / m 2 or less, and preferably 230 g / m 2 or more and 550 g / m 2 or less. Note that the paper substrate thickness in this specification is a value obtained as the average value of the thicknesses at 20 locations measured based on a photograph of the cross-section obtained by cutting the substrate perpendicular to the paper surface.

[0030] <Vapor-phase metal deposition film> Examples of metals constituting the vapor-phase metal deposition film include metals such as indium, tin, aluminum, nickel, copper, silver, gold, platinum, brass, chromium, and zinc, and alloys thereof. Among these, it is preferable to use one or more selected from indium, tin, aluminum, zinc, and alloys thereof. In particular, a vapor-phase metal deposition film using indium or tin has excellent metallic luster and good weather resistance. Furthermore, since indium and tin have low melting points, they tend to form an island structure when made into a deposition film.

[0031] An island structure is a film structure in which when observing the film surface with an electron microscope, multiple island portions where the deposited metal has precipitated and grown are observed. Specifically, it is the structure shown in FIG. 8. As shown in FIG. 8, when microscopically observing a vapor-phase metal deposition film within the substrate plane, a plurality of island portions (metal portions) are densely packed, and the island portions are separated by sea portions. That is, the sea portion is a region where no island portions are formed.

[0032] In the present invention, a vapor-phase metal deposition film is formed such that the area per island portion is 4,400 nm 2 or more and 94,000 nm 2 or less. When the area per island portion is less than 4,400 nm 2 the metallic luster is insufficient, and it becomes inferior in design as a packaging material.

[0033] On the other hand, when the area per island portion exceeds 94,000 nm 2 damage such as deformation, burning, peeling of the vapor-phase metal deposition film, and holes of the packaging material is likely to occur. For this reason, the following can be considered. When heating with a microwave oven, moisture evaporates from the paper substrate, and the paper substrate thermally contracts. Due to this contraction, the arrangement of the island portions of the vapor-phase metal deposition film on the paper substrate is disturbed. When the arrangement of the island portions is disturbed, adjacent island portions are likely to come into contact. In particular, since the paper substrate has a high water content, the contraction due to the evaporation of moisture is large, the arrangement of the island portions is disturbed, and the island portions are likely to come into contact. When adjacent island portions come into contact, it can be considered that the area of the island portions at that location has increased. The area of the new island portion (contact island portion) formed by the contact of adjacent island portions becomes larger as the area of the initial island portion is larger. When there are island portions with such a large area, the amount of heat generated during heating in the microwave oven becomes large. Therefore, it is considered that this leads to damage such as deformation, burning, peeling of the vapor-phase metal deposition film, and holes of the packaging material.

[0034] As described above, there is a correlation between the area (density) per island portion and the damage after heating with a microwave oven. The area per island portion is 4,400 nm 2 or more and 94,000 nm 2By doing the following, a packaging material having excellent metallic luster and range resistance can be obtained, and furthermore, the occurrence of damage after microwave heating can be suppressed. Considering the metallic luster, the area per island portion is preferably 24,000 nm 2 or more, and more preferably 30,000 nm 2 or more. Also, considering the microwave resistance, the area per island portion is preferably 76,000 nm 2 or less, and more preferably 69,000 nm 2 or less.

[0035] In this specification, the area per island portion is calculated by the following method. First, a surface photograph of the vapor-phase metal deposition film of the metal decoration part is taken with a scanning electron microscope (SEM). The photographing magnification is preferably 5,000 to 20,000 times. Next, a square frame in which 50 or more and 100 or less island portions are included is superimposed on the taken photograph. Let the length of one side of the frame be L [nm]. "L" represents the actual size on the sample and can be calculated based on, for example, the pixel size or scale bar of the SEM photograph. Next, the number of island portions (n1) entirely included in the frame, the number of island portions (n2) in which 1 / 2 or more and less than 1 of the area of the island portion is recognized to exist in the frame, and the number of island portions (n3) in which less than 1 / 2 of the area of the island portion is recognized to exist in the frame are counted. Based on the counted n1, n2, and n3, "n" represented by the following formula (i) is assumed to be the number of island portions existing in the frame. n = n1+(3n2 + n3) / 4 (i) Then, based on the length L [nm] of one side of the frame and the number (n) of island portions in the frame calculated by formula (i), "a" represented by the following formula (ii) is assumed to be the area per island portion [nm 2 in the frame. Note that the area per island portion a [nm 2 calculated in this way includes a slight area of the sea portion. However, as is clear from FIG. 8, the sea portion occupies a slight area in the plane, and the area a [nm per island portion2 Since the influence on the metallic luster is negligibly small, the influence of the sea area is ignored in this specification. a = L 2 / n (ii) Perform the above operation at 20 locations, and take the average value of "a" at the 20 locations as the area A [nm per island part in this specification. 2 shall be.

[0036] The area per island part can be adjusted, for example, by the deposition time (the area A increases as the deposition time is lengthened). In addition, the observation with a scanning electron microscope (SEM) is preferably performed after allowing the vapor deposition film to sufficiently adapt to an environment of a temperature of 23°C ± 5°C and a humidity of 40 to 65%. Further, the acceleration voltage during the photographing with a scanning electron microscope (SEM) is preferably in the range of 1 to 5 kV, and the pixel size of the image is preferably 5.0 to 10 nm.

[0037] <Adhesive layer> Between the paper substrate and the vapor-phase metal vapor deposition film, from the viewpoint of improving the adhesiveness between the two, the paper substrate and the vapor-phase metal vapor deposition film may be adhered via an adhesive layer. When forming a vapor deposition film with a transfer foil described later, the adhesive layer of the transfer foil can be used as the adhesive layer between the paper substrate and the vapor-phase metal vapor deposition film. The adhesive layer is composed of, for example, an adhesive such as a polyester-based resin, an acrylic-based resin, a vinyl chloride-based resin, a vinyl-based resin, a polyamide-based resin, a polyvinyl acetate-based resin, a rubber-based resin, an ethylene-vinyl acetate copolymer-based resin, a vinyl chloride-vinyl acetate copolymer resin, etc. The adhesive layer may be a pressure-sensitive adhesive layer (so-called adhesive layer) or a heat-sensitive adhesive layer (heat-sealing layer). The heat-sensitive adhesive layer (heat-sealing layer) is preferable in that the shape is less likely to change due to the pressure during transfer compared to the pressure-sensitive adhesive layer (adhesive layer), so it is easy to maintain the flatness of the vapor-phase metal vapor deposition film and easy to obtain good metallic luster after transfer. The thickness of the adhesive layer only needs to ensure sufficient adhesiveness between the paper substrate and the vapor-phase metal vapor deposition film, and is usually 0.2 to 10.0 μm, preferably 0.5 to 8.0 μm, more preferably 0.7 to 5.0 μm.

[0038] <Coloring layer> From the viewpoints of decorativeness and protection of the vapor-deposited metal film, it is preferable that the packaging material has a coloring layer. The coloring layer constitutes characters (product name, product display, quality display, etc.), graphics, photographs, symbols, patterns, designs, patterns, solid printing, etc., and together with the pattern printing layer, constitutes the pattern of the packaging material. When the packaging container is formed, the coloring layer is located on the outer layer side rather than the vapor-deposited metal film. Specifically, when a paper substrate is used, it is formed on the surface opposite to the substrate of the vapor-deposited metal film. The coloring layer may be provided in a part of the outer layer side of the vapor-deposited metal film, but it is preferably provided in the entire outer layer side of the vapor-deposited metal film.

[0039] The thickness of the coloring layer is appropriately set according to the desired decorativeness, and is usually 0.2 to 10.0 μm, preferably 0.5 to 8.0 μm, and more preferably 0.7 to 5.0 μm.

[0040] As the ink used for forming the coloring layer, a mixture obtained by appropriately mixing a binder resin with a colorant such as a pigment or a dye, an extender pigment, a solvent, a stabilizer, a plasticizer, a catalyst, a curing agent, etc. is used. The binder resin preferably has good adhesiveness to the surface of the vapor-deposited metal film. For example, acrylic resins, styrene resins, polyester resins, polyurethane resins, chlorinated polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl butyral resins, alkyd resins, petroleum resins, ketone resins, epoxy resins, melamine resins, fluorine resins, silicone resins, cellulose derivatives, rubber resins, etc. may be mentioned. These may be used alone or in combination of two or more. In addition, the coloring layer may contain other additives such as an antioxidant and an ultraviolet absorber within a range that does not interfere with the adhesiveness between the vapor-deposited metal film and the coloring layer.

[0041] <Pattern printing layer> The pattern printing layer is formed on a substrate for the purpose of enhancing the design of the packaging material. The pattern printing layer is a broad concept that includes, for example, characters (product names, product displays, quality displays, etc.), graphics, photographs, symbols, patterns, designs, solid printing, and the like. The pattern printing layer may be composed of one layer or multiple layers of two or more layers. Also, the pattern printing layer may be full-surface printing or partial printing on the substrate. The pattern printing layer and the vapor-phase metal deposition film may be formed by overlapping so that the pattern printing layer is located on the inner layer side of the vapor-phase metal deposition film when the packaging container is formed. Also, they may be formed by overlapping so that the pattern printing layer is located outside the vapor-phase metal deposition film when the packaging container is formed. Also, the pattern printing layer may be formed so as to be parallel in the same plane as the metal decoration part. The pattern printing layer can be formed, for example, by single-color or multi-color printing using process colors, or can also be formed by other special printing methods.

[0042] The thickness of the pattern printing layer is not particularly limited, but is usually preferably about 0.2 to 10 μm, more preferably 0.5 to 8 μm, and even more preferably 0.7 to 5 μm.

[0043] The pattern printing layer is usually formed by printing using an ink for forming a pattern printing layer, which mainly consists of a vehicle composed of a binder resin and a solvent, and to which a colorant such as a dye or a pigment is added and mixed. Examples of the printing method include gravure printing, offset printing, letterpress printing, silk screen printing, and the like. Among these, gravure printing is preferred.

[0044] As the colorant for the pattern printing layer, general-purpose dyes and pigments can be used (for example, inorganic pigments such as lead yellow, titanium yellow, bengala, cadmium red, ultramarine blue, cobalt blue, etc.; organic pigments such as quinacridone red, isoindolinone yellow, phthalocyanine blue, etc.). As the black pigment, general-purpose black pigments such as carbon black and titanium black can also be used. However, due to the microwave of the microwave oven, there is a risk that the parts where carbon black and titanium black of the packaging material for the microwave oven exist will be locally overheated. Therefore, attention such as suppressing the blending amount in the ink for forming the pattern printing layer is necessary. As other black pigments, for example, organic pigments such as perylene black and azomethine azo pigments; inorganic pigments such as iron oxides such as magnetite-type iron tetroxide and composite oxides of copper, chromium, zinc, etc. can be mentioned.

[0045] As the binder resin in the pattern printing layer, for example, polyolefin resins such as polyethylene-based resins and chlorinated polypropylene-based resins, poly(meth)acrylic resins, polyvinyl chloride-based resins, polyvinyl acetate-based resins, vinyl chloride-vinyl acetate copolymers, polystyrene-based resins, styrene-butadiene copolymers, vinylidene fluoride-based resins, polyvinyl alcohol-based resins, polyvinyl acetal-based resins, polyvinyl butyral-based resins, polybutadiene-based resins, polyester-based resins, polyamide-based resins, alkyd-based resins, epoxy-based resins, unsaturated polyester-based resins, thermosetting poly(meth)acrylic resins, melamine-based resins, urea-based resins, polyurethane-based resins, phenol-based resins, xylene-based resins, maleic acid resins, cellulose-based resins such as nitrocellulose, ethyl cellulose, acetyl butyl cellulose, ethyl oxyethyl cellulose, etc., rubber-based resins such as chlorinated rubber and cyclized rubber, petroleum-based resins, natural resins such as rosin and casein, etc. can be mentioned. These may be used alone or in combination of two or more.

[0046] Examples of the solvent in the ink for forming the pattern printing layer include alcohol solvents such as methanol, ethanol, normal propanol, isopropanol, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as methyl acetate, ethyl acetate, and normal propyl acetate; aliphatic hydrocarbon solvents such as normal hexane, normal heptane, and normal octane; alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and cycloheptane; aromatic solvents such as toluene and xylene; and mineral spirit. These may be used alone or in combination of two or more. In cases where there are concerns about the working environment during printing and the impact on the packaged product, it is particularly preferable not to contain aromatic solvents among these.

[0047] In addition, for forming the pattern printing layer, optional additives such as fillers, stabilizers, plasticizers, antioxidants, light stabilizers such as ultraviolet absorbers, dispersants, thickeners, desiccants, anti-settling agents, lubricants, antistatic agents, and crosslinking agents can be added as needed. These additives may be inorganic compounds or organic compounds.

[0048] <Top coat layer> In the packaging material of the present invention, a top coat layer may be formed on the outermost surface on the side opposite to the paper base material. The top coat layer may be formed over the entire surface of the paper base material or on a part thereof. The top coat layer has light transmissibility.

[0049] The packaging material is preferably formed from the viewpoints of surface protection for preventing scratches and dirt on the surfaces of the pattern printing layer, the glitter printing layer, and the colored layer, and imparting a glossy or matte feeling to the decoration by the pattern printing layer, the glitter printing layer, and the metal decoration part to enhance the luxurious feeling.

[0050] The topcoat layer can be formed by a known topcoat agent (overcoat agent). Examples of the topcoat agent include OP varnish (gloss varnish) that imparts a glossy feeling, matte OP varnish for dulling, etc., and they can be selected and used according to each purpose. Examples of the printing method include gravure printing, offset printing, letterpress printing, flexographic printing, silk screen printing, etc. Among these, gravure printing is preferred.

[0051] The thickness of the topcoat layer is preferably about 0.2 to 10 μm, more preferably 0.5 to 8 μm, and even more preferably 0.7 to 5 μm.

[0052] <Glossy printing layer> In the present invention, a glossy printing layer can be formed. Since the vapor deposition metal film and the glossy printing layer have different magnitudes of light diffusion, their specular reflection intensities are different. Therefore, the glossy printing layer has a different glossiness from the vapor deposition metal film, and by using them in combination, the design property of the packaging material can be enhanced.

[0053] The glossy printing layer is formed by printing with an ink for the glossy printing layer. The ink for the glossy printing layer usually uses a vehicle mainly composed of a binder resin and a solvent, and to this, an ink in which a pearl pigment, metal flakes, and further, if necessary, a colorant such as a dye or a pigment are added and mixed is used. Examples of the printing method include gravure printing, offset printing, letterpress printing, silk screen printing, etc. Among these, gravure printing is preferred.

[0054] The glossy printing layer may be formed on the entire surface of the area visible from the outer layer side of the packaging material for a microwave oven, or may be formed only on a part thereof. As illustrated in FIG. 2, the glossy printing layer and the vapor deposition metal film may be formed in an overlapping manner such that the glossy printing layer is located on the inner layer side of the metal decoration part when the packaging container is formed. Also, the glossy printing layer may be formed so as to be parallel in the same plane as the metal decoration part.

[0055] A pattern such as a picture, characters (such as a product name, product display, quality display, etc.), a figure, a symbol, a pattern, or a design may be formed by the bright printing layer. Further, the bright printing layer may be composed of one layer or may be composed of two or more layers. The bright printing layer may be provided separately from the metal decoration part or may be provided adjacent thereto. When the bright printing layer and the vapor-phase metal deposition film are adjacent to each other, the two can be integrated to form one pattern.

[0056] From the viewpoint of obtaining sufficient metallic luster, the thickness of the bright printing layer is preferably 0.5 to 10 μm, more preferably 0.8 to 8 μm, and still more preferably 1 to 5 μm. In addition, from the viewpoint of improving the adhesion to the paper substrate, an anchor coat layer may be formed on the paper substrate, and the bright printing layer may be formed in contact with the anchor coat layer. The anchor coat layer can have a known configuration, and examples of the constituent material include polyethyleneimine and two-component curable polyurethane.

[0057] The bright printing layer contains a pearl pigment and metal flakes. The pearl pigment and metal flakes provide the brightness of the bright printing layer, and a metallic luster is imparted to the packaging material for microwave oven use. From the viewpoints that the bright printing layer has a uniform metallic luster and the adhesion of the pearl pigment and metal flakes to the paper substrate, the total content of the pearl pigment and metal flakes in the bright printing layer is preferably 20 to 50% by mass in the bright printing layer, more preferably 25 to 48% by mass, and still more preferably 30 to 45% by mass.

[0058] When both a pearl pigment and metal flakes are contained in the bright printing layer, the content of the pearl pigment is preferably 40 to 90 parts by mass with respect to a total of 100 parts by mass of the pearl pigment and metal flakes. When the content of the pearl pigment is 90 parts by mass or less, a bright printing layer having sufficient metallic luster can be formed. Further, when it is 40 parts by mass or more, heat generation in the region where the bright printing layer of the packaging material is formed can be suppressed during use in a microwave oven. From the perspective of higher metallic luster, the content of the pearl pigment is preferably 80 parts by mass or less. Also, from the perspective of further suppressing heat generation in the area where the shiny printing layer of the packaging material is formed and ensuring sufficient safety during use in a microwave oven, it is preferably 65 parts by mass or more.

[0059] The pearl pigment is one in which a flaky matrix such as mica, aluminum, or glass is covered with a coating layer made of a high refractive index material such as titanium dioxide and has light transmissibility. For this reason, when the thin plate-like fine particles are arranged in layers, light is multiply reflected, and a metallic or pearl-like luster can be produced. Thus, the pearl pigment is not the metal itself but a colorant mainly composed of metal oxides that can produce a metallic luster. Examples of pearl pigments include white pearl pigments, interference pearl pigments, and colored pearl pigments. The white pearl pigment has a coating layer covering a matrix such as mica made of a colorless high refractive index material such as titanium dioxide, and the thickness of the coating layer is relatively small, about 0.1 to 0.15 μm. Since it reflects almost all wavelengths of light, it appears white or silver. The interference pearl pigment has a coating layer covering a matrix such as mica made of a colorless high refractive index material such as titanium dioxide, and the thickness of the coating layer is larger than that of the white pearl pigment and exceeds 0.15 μm. Due to this thickness, the reflected light and transmitted light change, producing various interference colors. It is sometimes called an iridescent pearl pigment or a polarized pearl pigment. The colored pearl pigment is colored. Examples include those in which the coating layer covering a matrix such as mica is made of a colored high refractive index material such as ferric oxide, those in which the periphery of the white pearl pigment is further covered with a colored high refractive index material such as ferric oxide or other colored pigments, or those in which pigments or other colorants are added to the coating layer covering a matrix such as mica.

[0060] The particle size of the pearl pigment is not particularly limited, and preferably has an average length of 5 to 60 μm, more preferably 5 to 30 μm. In the present specification, the average length of the pearl pigment and the metal flakes described below means the average value of the lengths of any 20 particles (pearl pigment or metal flakes) observed with an optical microscope or an electron microscope from the planar direction of the packaging material. The length of one pearl pigment or metal flake means the maximum length in the planar direction of one pearl pigment or metal flake.

[0061] The pearl pigment preferably has an aspect ratio defined by [average length / average thickness] of 25 to 300, more preferably 50 to 200. In the present specification, the average thickness of the pearl pigment and the metal flakes described below is determined as the average value of the thicknesses of any 20 pearl pigments or metal flakes observed with an optical microscope or an electron microscope on the cross-section of the packaging material. The thickness of one pearl pigment or metal flake means the average of t1 to t5 obtained by dividing the cross-sectional image of one pearl pigment or metal flake into five regions of equal length in the length direction and measuring the thicknesses (t1, t2, t3, t4, t5) at the central parts of each region.

[0062] Examples of the metal of the metal flakes include metals and alloys such as aluminum, gold, silver, brass, titanium, chromium, nickel, nickel chromium, and stainless steel. Among these, aluminum is preferable from the viewpoints of versatility and availability. The metal flakes can be obtained, for example, by peeling a metal thin film formed by vacuum-depositing the metal or alloy on a plastic film from the plastic film, pulverizing and stirring the peeled metal thin film, or by mixing the powder of the metal or alloy with a solvent and spreading and / or pulverizing the powder using a medium stirring mill, a ball mill, an attritor, etc. Further, those having their surfaces resin-coated can also be used.

[0063] From the perspective of uniform dispersibility in the lustrous printing layer, the average length of the metal flakes is preferably 0.2 to 50 μm, more preferably 1 to 30 μm, and even more preferably 2 to 20 μm. Also, from the perspective of handleability and high metallic luster, the average thickness is preferably 0.01 to 5 μm, more preferably 0.02 to 3 μm, and even more preferably 0.03 to 1 μm. Further, the aspect ratio defined by [average length / average thickness] of the metal flakes is preferably 25 to 400, more preferably 40 to 350, and even more preferably 60 to 300.

[0064] As the binder resin in the lustrous printing layer, the same resins as those in the pattern printing layer can be used. For example, polyolefin resins such as polyethylene-based resins and chlorinated polypropylene-based resins, poly(meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinyl acetate-based resins, vinyl chloride-vinyl acetate copolymers, polystyrene-based resins, styrene-butadiene copolymers, vinylidene fluoride-based resins, polyvinyl alcohol-based resins, polyvinyl acetal-based resins, polyvinyl butyral-based resins, polybutadiene-based resins, polyester-based resins, polyamide-based resins, alkyd-based resins, epoxy-based resins, unsaturated polyester-based resins, thermosetting poly(meth)acrylic-based resins, melamine-based resins, urea-based resins, polyurethane-based resins, phenol-based resins, xylene-based resins, maleic acid resins, cellulose-based resins such as nitrocellulose, ethyl cellulose, acetyl butyl cellulose, and ethyl oxyethyl cellulose, rubber-based resins such as chlorinated rubber and cyclized rubber, petroleum-based resins, natural resins such as rosin and casein, etc. These can be used alone or in combination of two or more. The content of the binder resin in the lustrous printing layer depends on the other solid content except for the pearl pigment and the metal flakes. From the perspectives of adhesion to the substrates of the pearl pigment and the metal flakes and printing efficiency, etc., it is preferably 20 to 50% by mass, more preferably 25 to 48% by mass, and even more preferably 30 to 45% by mass, and preferably about the same as the total content of the pearl pigment and the metal flakes.

[0065] As the solvent used in the ink for the fluorescent printing layer, the same solvents as those for the pattern printing layer can be used. For example, alcohol solvents such as methanol, ethanol, normal propanol, isopropanol, propylene glycol monomethyl ether, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ester solvents such as methyl acetate, ethyl acetate, normal propyl acetate, aliphatic hydrocarbon solvents such as normal hexane, normal heptane, normal octane, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, cycloheptane, aromatic solvents such as toluene, xylene, and mineral spirit. These can be used alone or in combination of two or more. In addition, when there are concerns about the working environment during printing and the impact on the packaged products, among these, in particular, it is preferable not to contain aromatic solvents.

[0066] In addition, to the ink for the fluorescent printing layer, if necessary, for example, coloring agents, fillers, stabilizers, plasticizers, antioxidants, light stabilizers such as ultraviolet absorbers, dispersants, thickeners, drying agents, anti-settling agents, lubricants, antistatic agents, crosslinking agents and other optional additives can be added. These additives may be inorganic compounds or organic compounds.

[0067] <Method for manufacturing packaging material> In the case of a packaging material using a paper substrate as the substrate, the vapor phase metal deposition film is preferably formed by transfer. The transfer foil (transfer foil) has a structure having, for example, a release layer, a coloring layer, a vapor phase metal deposition film, and an adhesive layer on a base film.

[0068] As the base film, a general-purpose plastic film can be used. The thickness of the base film is about 5 to 30 μm.

[0069] The release layer is a layer that enables the colored layer, the vapor-phase metal deposition film, and the adhesive layer to be peeled off from the base film after transfer. When the release layer remains on the colored layer when peeled off from the base film, the release layer functions as a protective film and contributes to improving the wear resistance of the vapor-phase metal deposition film. The release layer is provided on at least a part of one surface of the base film, but from the viewpoint of uniformizing the releasability within the plane, it is preferable that the release layer is provided on the entire surface of the base film. The release layer is preferably mainly composed of a resin. The resin of the release layer is not particularly limited as long as it is a material with low adhesive force to the colored layer, and examples include general-purpose thermoplastic resins, cured products of thermosetting resin compositions, cured products of radiation-curable resin compositions, etc. Specifically, fluorine-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, polyolefin-based resins, polystyrene-based resins, polyurethane-based resins, cellulose-based resins, vinyl chloride-vinyl acetate copolymer resins, nitrocellulose, etc. can be mentioned. The release layer may contain waxes such as synthetic waxes and natural waxes in order to improve the releasability. As the synthetic wax, polyolefin waxes such as polyethylene wax and polypropylene wax are preferable. Among these, the cured product of a thermosetting resin composition is preferable, and a thermosetting resin composition containing acrylic polyol and isocyanate is more preferable. The thickness of the release layer is not particularly limited, but is usually about 0.1 to 1.0 μm. As a method for forming the release layer, for example, known methods such as gravure printing, offset printing, letterpress printing, and silk screen printing can be applied. In particular, gravure printing is preferable.

[0070] A colored layer is formed on the release layer. The colored layer is preferably provided at least at the location where the vapor-phase metal deposition film is formed. Also, considering productivity, it is more preferable that the colored layer is provided on the entire surface of the base film. The colored layer is mainly composed of a resin and a colorant. A dye or a pigment is used as the colorant and is adjusted to a desired color. The resin is selected in consideration of various physical properties (heat resistance, light resistance, wear resistance, etc.) of the vapor-phase metal deposition film after transfer. The coloring layer can be formed, for example, by single-color printing or multi-color printing. Examples of the printing method include gravure printing, offset printing, letterpress printing, silk screen printing, etc. Among these, gravure printing is preferred. When the coloring layer is not necessary, the above steps can be omitted.

[0071] A vapor-phase metal deposition film is formed on the coloring layer. When the coloring layer is not provided, a vapor-phase metal deposition film is formed on the release layer. Examples of the method for forming the vapor-phase metal deposition film include physical vapor deposition methods (PVD) such as vacuum evaporation, sputtering, and ion plating. Among these, the vacuum evaporation method, which can process any material, is preferred. That is, the vapor-phase metal deposition film includes a physical vapor deposition film, and among them, a vacuum evaporation film is preferred. The vapor-phase metal deposition film formed here has the island structure described above, and the area per island is 4,400 nm 2 or more and 94,000 nm 2 or less. The various formation conditions of the vapor-phase metal deposition film are appropriately set so as to have the above structure.

[0072] An adhesive layer is formed on the vapor-phase metal deposition film. The adhesive layer is made of a resin having good adhesion suitability with the object to be transferred. For example, the above-mentioned adhesives can be used. Also, as described above, the adhesive layer of the transfer foil is preferably a heat-sensitive adhesive layer (heat seal layer). If necessary, a tackifier, a pigment, etc. are added to the adhesive layer. The adhesive layer is formed by a known method so as to have a predetermined thickness. Examples of the method for forming the adhesive layer include gravure printing, offset printing, letterpress printing, silk screen printing, etc.

[0073] In the packaging material of the present invention, the above transfer foil is transferred onto a substrate by thermal transfer using a plate of a desired shape. As the transfer method, either an up-down type or a cylinder type can be adopted. Considering the material and surface state of the object to be transferred, the shape of the plate, the material of the adhesive layer, etc., conditions such as temperature and pressure are appropriately set.

[0074] [Packaging Material Using a Plastic Film] Hereinafter, the structure of each layer of the packaging material using a plastic film will be described. [Plastic Film] The plastic film is not particularly limited as long as it has processability, strength, heat resistance, etc. according to the packaging purpose. When the packaging material is for microwave oven use, the resin constituting the plastic film is required to have excellent heat resistance. Examples of resins constituting a plastic film with excellent heat resistance include polyester resins and polyamide resins. Specifically, examples include a single polyester film, a single polyamide film such as nylon, and a composite film containing one or more of a polyester film and a polyamide film. Examples of the composite film include PET / Ny / PET and a coextruded stretched film having a PET / Ny structure from the outer layer side when used as a packaging container. Further, as the composite film, it is also preferable to combine one or more of a polyester film and a polyamide film with one or more of an ethylene-vinyl alcohol copolymer film and a polyvinylidene chloride film.

[0075] The thickness of the plastic film is not particularly limited and can be appropriately set according to the use of the packaging material. Specifically, it is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, and still more preferably 12 μm or more and 25 μm or less.

[0076] [Vapor-Phase Metal Deposition Film] In this packaging material as well, a vapor-phase metal deposition film similar to that of the paper substrate is formed. Regarding the method for calculating the area per island portion, the "metal-deposited film" refers to a plastic film on which a vapor-phase metal deposition film is formed.

[0077] When using a plastic film as the base material, shrinkage of the base material and the sealant layer occurs due to microwave heating. This shrinkage causes the arrangement of the island portions of the vapor-phase metal deposition film on the plastic film to become disordered, making it easier for adjacent island portions to come into contact with each other. In particular, in a packaging container having an automatic steam penetration mechanism, if a vapor-phase metal deposition film is formed near the automatic steam penetration mechanism, the vapor-phase metal deposition film will be exposed to high-temperature steam, and the plastic film will shrink, etc., making it easier for the arrangement of the island portions to become disordered.

[0078] As described above, there is a correlation between the area (density) per island portion and the damage after microwave heating. The larger the area per island portion, the more likely it is for damage such as deformation due to shrinkage, peeling of the vapor-phase metal deposition film, and holes to occur. The area per island portion is 4,400 nm 2 or more and 94,000 nm 2 or less. By doing so, a packaging material having excellent metallic luster and range resistance can be obtained, and furthermore, damage after microwave heating can be suppressed. Even when using a plastic film as the base material, considering the metallic luster and range resistance, the area per island portion is preferably 24,000 nm 2 or more, and more preferably 30,000 nm 2 or more. Also, considering the shrinkage of the packaging material due to heating, the area per island portion is preferably 76,000 nm 2 or less, and more preferably 69,000 nm 2 or less.

[0079] <Coloring layer> In this packaging material as well, from the viewpoints of decorativeness and protection of the vapor-phase metal deposition film, it is preferable to provide a coloring layer. In this case, the same coloring layer as that of the packaging material using a paper base material can be provided. The coloring layer is located on the outer layer side of the vapor-phase metal deposition film when formed into a packaging container. Specifically, when using a plastic film, it is formed between the metal deposition layer and the base material.

[0080] <Pattern printing layer> Also in this packaging material, for the purpose of enhancing the design property, a pattern printing layer similar to the case of using a paper base material is formed. The pattern printing layer may be a full-surface printing or a partial printing on the base material.

[0081] <Sealant layer> The sealant layer is located on the innermost layer when the packaging bag is formed, the inner layer side surface of the packaging bag contacts the object to be packaged, and protects the object to be packaged. When the object to be packaged is liquid, it is preferable that the sealant layer has permeability resistance to the liquid. Also, for the purpose of making it easier to form the packaging material into the form of a packaging bag, it is preferable that the inner layer side has heat sealability.

[0082] The thickness of the sealant layer is not particularly limited and is appropriately set according to the use of the packaging material and the type and properties of the object to be packaged, etc. Usually, it is preferably about 10 to 200 μm. When a packaging bag is formed with the packaging material, the thickness of the sealant layer is more preferably 15 to 150 μm, and still more preferably 20 to 100 μm.

[0083] As the material constituting the sealant layer, it is preferable to have heat resistance. For example, specifically, propylene-based resins such as propylene homopolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer, and high-density PE (HDPE) are mentioned, and one or more of these resins can be used. The sealant layer may be composed of a single layer or multiple layers of two or more layers. Also, when the packaging material is used for the lid of a container with a lid as described later, it is preferable to further have easy peelability. Easy peelability means, for example, the property that when opening a container with a lid, the lid can be easily peeled off from the container body. A sealant layer having easy peelability can be formed by mixing two or more resins, namely, one resin (a resin with good adhesion to the container body) and another resin (a resin with poor adhesion to the container body and incompatible with the one resin). Although such resins vary depending on the material of the container and cannot be generally stated, when the container body is formed of polypropylene, a sealant layer can be formed from a resin obtained by mixing polypropylene, which is one resin (a resin with good adhesion to the container body), and one or more selected from polyethylene, polybutene, and polystyrene, which are other resins (resins with poor adhesion to the container body and incompatible with the one resin), to impart easy peelability to a polypropylene container. Note that the sealant layer may have a multilayer structure, and easy peelability may be imparted only to the side joined to the container body of the sealant layer.

[0084] <Glossy printing layer> Also in this packaging material, for the purpose of enhancing the design, a glossy printing layer similar to the case of using a paper base material may be formed. The glossy printing layer may be a full-surface printing or a partial printing on the base material. The glossy printing layer may be provided separately from the metal decoration part or adjacent to it. When the glossy printing layer and the vapor-phase metal deposition film are adjacent, the two can be integrated to form one pattern. Also, as a pattern in which a pattern printing part is formed on a part of the periphery of the metal decoration part, it may be arranged such that a glossy printing part is formed on other parts.

[0085] <Manufacturing method of the packaging material> In the case of a packaging material using a plastic film as the base material, the coloring layer and the vapor-phase metal deposition film may be directly formed on the plastic film. In this case, a metal decoration part can be formed in a desired area using a pasting process. An example of the manufacturing method of the packaging material using the pasting process is shown below.

[0086] First, a pattern printing layer and a coloring layer are formed on a plastic film. At this time, a fluorescent printing layer may be further formed. The coloring layer can also be omitted. Further, an overcoat layer may be formed after each layer is formed. Thereafter, a paste processing ink (for example, an ink containing polyvinyl alcohol) is patterned and applied onto the pattern printing layer and the coloring layer (and the fluorescent printing layer) so that a metal decoration part having a desired shape is formed, and then dried. Examples of the coating method include gravure printing, offset printing, letterpress printing, silk screen printing, etc. Among these, gravure printing is preferable. A vapor-phase metal deposition film is formed on the substrate coated with the paste processing ink by the same method as described above. The vapor-phase metal deposition film formed here has the island structure described above, and the area per island is 4,400 nm 2 or more and 94,000 nm 2 or less. Various formation conditions of the vapor-phase metal deposition film are appropriately set so as to have the above structure. After forming the vapor-phase metal deposition film, the substrate is immersed in a solvent (for example, water) in which the paste processing ink is soluble. By this step, the vapor-phase metal deposition film is removed in the region where the paste processing ink is applied, and a pattern of the vapor-phase metal deposition film having a desired shape is formed. After patterning the vapor-phase metal deposition film as described above, a sealant layer is formed on the substrate.

[0087] As another example of the paste processing, after a paste processing ink having alkali resistance is patterned, applied, and dried on the vapor-phase metal deposition film in a desired shape, it is immersed in an alkaline solution (for example, a sodium hydroxide solution) to remove the vapor-phase metal deposition film in the uncoated region.

[0088] Also, in the case of a packaging material using a plastic film as a substrate, a metal decoration part may be formed by thermal transfer using the above foil.

[0089] 〔Packaging container〕 The packaging container of the present invention is formed from the above-described packaging material of the present invention. The type and use of the packaging container are not particularly limited, but when selling the contents contained in the packaging container, it is possible to impress the purchaser with a sense of luxury of the contents. In particular, the packaging container using the packaging material of the present invention can be suitably used for a packaging container for food that is heated in a microwave oven.

[0090] <Container> When a paper substrate is used as the substrate, an example of the packaging container of the present invention is a container (primary container) that directly houses the object to be packaged. Examples of the primary container include a tray, a carton, a liquid carton, a cup, and a fitting box. The container is heated in a microwave oven together with the container while directly housing various foods cooked by microwave heating.

[0091] FIG. 9 is a perspective view of a tray that is an example of the packaging container of the present invention. The tray 600 includes a bottom plate 602 and a side peripheral portion 604 connected to the bottom plate 602. In FIG. 9, the bottom plate 602 is rectangular, but the shape of the bottom plate can be appropriately set according to the shape required for the container, such as circular or elliptical. In FIG. 9, the shape of the opening 606 is the same as the shape (rectangular) of the bottom plate 602, but the present invention is not limited thereto, and the shape of the opening 606 and the bottom plate 602 may be different. For example, the bottom plate may be circular and the opening may be a rectangle with rounded corners. The sizes of the bottom plate 602 and the opening 606 do not necessarily have to match. For example, as shown in FIG. 9, the container may be designed such that the opening 606 is larger than the bottom plate 602. Also, in FIG. 9, the side peripheral portion 604 is composed of four plate-like members, but the number and shape of the members used for the side peripheral portion 604 are appropriately set according to the shape of the container.

[0092] In the case of a container (primary container) using a paper substrate, it is preferable that a sealant layer is provided on the inner surface side of the paper substrate (the surface opposite to the surface on which the pattern printing layer of the paper substrate is formed). As the sealant layer, polyester-based resins, polyolefin-based resins, etc. are preferably used. Among them, it is particularly preferable that the sealant layer contains polyethylene terephthalate (PET) or polypropylene (PP) as the main component. The thickness of the sealant layer is not particularly limited, but is preferably about 10 to 200 μm.

[0093] In the container, the metal decoration part is appropriately determined according to the desired decorative effect and is not particularly limited, but it is preferable that the metal decoration part is arranged at least on the side peripheral part of the container. For example, in the container 600 of FIG. 9, it is preferable that the metal decoration part is arranged on the outer surface S of the side peripheral part.

[0094] <Packing box> When using a paper substrate as the substrate, an example of the packaging container of the present invention is a packing box. The shape of the packing box is not particularly limited, and examples include a rectangular parallelepiped shape, a cylindrical shape, a conical shape, etc.

[0095] The packing box of the present invention can be preferably used, for example, as an outer packing box for a pouch filled with contents to be heated by a microwave oven. Specifically, this packaging box can be preferably used when heating the entire outer packaging box in a microwave oven while accommodating a pouch filled with various foods (such as retort foods and frozen foods, etc.) to be cooked by microwave heating. In this case, it is preferable that the pouch is provided with an automatic steam venting mechanism that opens due to the internal steam pressure increased by microwave heating. The packaging box preferably has an unsealing cut line and a fold line for deforming it into an unsealed state to hold the automatic steam venting mechanism at a position higher than the contents. For example, it is preferably configured to be placed in a microwave oven in an unsealed state opened in the manner shown in FIG. 10. By being configured in such a manner, the shape of the outer packaging box is maintained after microwave heating, and leakage of the filling or rupture of the pouch due to pressurization by the steam in the pouch is prevented, so that microwave heating and cooking of the food filled in the pouch can be safely performed.

[0096] The packaging box 700 shown in FIG. 10 is an outer packaging box that accommodates the pouch 730 and is in a rectangular parallelepiped shape in the unopened state. FIG. 10 shows the form when it is opened and placed in a microwave oven. First, the packaging box 700 containing the pouch 730 is opened along an unsealing cut line 720 that extends from one side panel 704 through the front panel 702 to the other side panel 704 facing the one side panel 704. Then, the upper part 710 of the box including the top panel 708 is folded back along a fold line 722 provided on the rear panel 706 (see the broken line arrow in the figure), and the side L1, which is the boundary line between the front panel 702 and the top panel 708, and the side L2, which is the boundary line between the rear panel 706 and the bottom panel 712, are placed in contact with the table surface in the microwave oven. If the packaging box 700 for microwave oven can be placed in the microwave oven while maintaining such a deformed unsealed state, the automatic steam venting mechanism 732 provided at the upper part of the pouch 730 can be held at a position higher than the contents in the pouch 730. The shape of the packaging box 700 is not particularly limited, and the forms and positions of the opening cut line 720 and the folding line 722 are not limited to the modes shown in FIG. 10. For example, it can also be in the form as described in JP-A-2006-44695, JP-A-2012-201375, JP-A-2012-201376, etc.

[0097] In the packaging box, the metal decoration part is appropriately determined according to the desired decoration effect and is not particularly limited. However, when placed in a microwave oven, it is preferable that the metal decoration part is arranged at least on the side peripheral part of the packaging box. For example, in the packaging box 700 of FIG. 10, it is preferable that the metal decoration part is arranged on the front panel 702.

[0098] When using a plastic film as the base material, the packaging container of the present invention includes, for example, pouches and containers with lids, as well as cups, trays, etc. These packaging containers may be entirely composed of the packaging material of the present invention, or may include the packaging material of the present invention in a part of the packaging container.

[0099] <Pouch> Specific shapes of the pouch include, for example, the shape of a pouch for a microwave oven. Note that the pouch may be a retort container (a container sterilized at high temperature and high pressure), and further may be a container other than a packaging container for a microwave oven or a retort container.

[0100] FIG. 11 shows an example of a pouch which is an embodiment of the packaging container of the present invention. The pouch 800 in FIG. 11 is a standing pouch formed by heat-sealing a body part 802 and a bottom part 804. As shown in FIG. 11, the body part 802 includes a pair of main surface sheets 806 composed of a front main surface sheet 806a and a back main surface sheet 806b arranged opposite to each other, and the side edges 810 of the pair of overlapped main surface sheets 806 are heat-sealed to each other in the vicinity. A bottom surface sheet 808 forming the bottom part 804 is arranged between the lower edges 812 of the pair of main surface sheets 806. And a storage space 816 for storing contents is formed within a region surrounded by a pair of main surface sheets 806 and a bottom surface sheet 808. The bottom surface sheet 808 is bent convexly toward the storage space 816 side, and its vicinity of the periphery is heat-sealed together with the lower part of the overlapping main surface sheet 806. That is, the heat-sealing part 820a forms the storage space 816, and by the bottom surface sheet 808 holding the shape of the lower ends of the pair of main surface sheets 806, the pouch 800 is given self-standing property and can be made into a standing-type pouch.

[0101] In the pouch 800 of FIG. 11, an opening 818 is formed between the upper edges 814 of the front main surface sheet 806a and the back main surface sheet 806b, and the contents can be stored through the opening 818. After storing the contents, the packaging container can be sealed by heat-sealing the vicinity of the upper edge 814 where the opening 818 is formed to form a heat-sealing part 820b. When taking out the contents from the pouch 800, it is opened by tearing the vicinity of the upper edge 814 from the notch 822.

[0102] At least one of the front main surface sheet 806a and the back main surface sheet 806b of this pouch 800 can be used as the packaging material of the present invention. That is, the sealant layer in the packaging material of the present invention is made the inner layer side (the storage space 816 side) and heat-sealed.

[0103] The metal decoration part is appropriately determined according to a desired decorative effect and is not particularly limited. In addition, as for sheets other than the sheet on which the packaging material of the present invention is used (the front main surface sheet, the back main surface sheet, or the bottom surface sheet), for example, those having only a pattern printing layer formed thereon, those provided with a pattern printing layer and a glitter printing layer, those not provided with a pattern printing layer and a glitter printing layer, etc. can be used.

[0104] The pouch may be provided with a known automatic steam venting mechanism (reference numeral 830 in FIG. 11). The automatic steam venting mechanism is configured to automatically release the steam in the accommodation space to the outside when the pressure inside the pouch rises due to the steam generated by heat-cooking the contents such as food, thereby preventing the pouch from bursting. For example, the automatic steam venting mechanism described in JP-A-2018-127257 or the like can be applied.

[0105] <Lid> As an example of the packaging container of the present invention, a container with a lid specifically has a configuration including a container body having a storage portion and a lid joined to the container body so as to seal the storage portion, and an example is a lid formed of the packaging material of the present invention. In this case, it is preferable that the entire lid is formed of the packaging material of the present invention. The container body is not particularly limited, and may include a part of the container containing the packaging material of the present invention. Further, the container body may be formed so as to include an intermediate base material layer. When the packaging material of the present invention is used for the lid, the sealant layer is arranged so as to face the container body. In the lid, the metal decoration portion is appropriately determined according to a desired decoration effect and is not particularly limited. Further, the lid may be provided with a known automatic steam venting mechanism. For example, the automatic steam venting mechanisms described in JP-A-2017-124860, JP-A-2018-193119, etc. can be applied. When the packaging material of the present invention is used, even if a metal decoration portion is provided in the automatic steam venting mechanism and in the vicinity of the automatic steam venting mechanism, deformation, holes, and other damages in the vicinity of the automatic steam venting mechanism after microwave heating are suppressed.

Examples

[0106] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples.

[0107] 1. Measurement and evaluation The following evaluations and measurements were performed on the metal-like decorative member. The results are shown in Table 1.

[0108] 1-1. Calculation of the area per island of the vapor-phase metal deposition film According to the procedure described in the main text of the specification, a surface photograph of the vapor-phase metal deposition film of each test piece was taken with a scanning electron microscope (SEM), and the area per island of the vapor-phase metal deposition film [nm 2 was calculated. As the scanning electron microscope (SEM), Model S-4800 manufactured by Hitachi High-Technologies Corporation was used, the acceleration voltage was 5 kV, the pixel size was 9.9 nm, and the working distance (WD) was 15.0 mm. In the case of the transfer foil, the test piece was collected from the state before forming the adhesive layer after forming the colored layer and the vapor-phase metal deposition film, and a surface photograph was taken. In the case of the packaging material using a plastic film as the base material, the test piece was collected from the state before forming the sealant layer after forming the colored layer and the vapor-phase metal deposition film on the base material, and a surface photograph was taken.

[0109] 1-2. Metal gloss evaluation (initial gloss) For the test pieces collected from each packaging material, the metal gloss of the vapor-phase metal deposition film was visually evaluated. Twenty people evaluated it, with 2 points for those with good metal gloss, 1 point for those that could not be clearly classified either way, and 0 points for those with insufficient metal gloss, and the average score was calculated. Then, the samples were ranked according to the following criteria for each average score. A: Average score is 1.5 or more B: Average score is 1.0 or more and less than 1.5 C: Average score is less than 1.0

[0110] 1-3. Appearance evaluation after heating in a microwave oven After the evaluation in 1-2 was carried out, each test piece was placed on the flat table of a microwave oven with an output of 600 W, and the microwave oven was operated for 20 seconds. Then, the test piece was taken out and the appearance was observed. The judgment criteria were as follows. A: Even when observed carefully, no change before and after heating can be confirmed. B: When observed carefully, slight discoloration or deformation can be confirmed, but there is no problem in practical use. C: Local burning, holes, large deformation, damage such as peeling of the vapor-phase metal deposition film, etc. were confirmed.

[0111] 2. Production of Packaging Material 2-1. Production of Transfer Foil On one surface of a plastic film (PET film) with a thickness of 12 μm, a coating liquid for a silicone-based release layer was applied over the entire surface and dried to form a release layer. The thickness of the release layer was 1 μm. On the release layer, a coating liquid for a colored layer containing a yellow-based pigment was applied over the entire surface and dried to form a colored layer. The thickness of the colored layer was 1 μm. Next, an indium vapor deposition film (vapor-phase metal deposition film) was formed on the colored layer by vacuum deposition. The deposition time was adjusted so that the area per island portion of the indium vapor deposition film (nm 2 ) would be the value shown in Table 1. Next, a coating liquid for a heat-sensitive adhesive layer containing a urethane resin-based adhesive was applied on the indium vapor deposition film and dried to form a heat-sensitive adhesive layer. The thickness of the heat-sensitive adhesive layer was 1 μm.

[0112] 2-2. Production of Packaging Material [Examples 1 to 6, Comparative Examples 1 to 2] On the surface of a paper substrate (coated paper with a thickness of 200 μm), a pattern printing layer with a thickness of 1.6 μm was formed by gravure printing using an ink for a pattern printing layer having the following composition. Thereafter, the transfer foil formed in 2-1 was transferred by heat transfer. The size of the foil portion after transfer was a circle with a diameter of 5 cm. After transfer, the base film was peeled off. Next, an OP varnish having the following composition was used to form a top coat layer with a thickness of 1.6 μm by gravure printing on the surfaces of the pattern printing layer and the colored layer, thereby obtaining the packaging materials of Examples 1 to 6 and Comparative Examples 1 to 2. Test pieces measuring 10 cm × 10 cm were cut out from the packaging materials of Examples 1 to 6 and Comparative Examples 1 to 2 so that the above foil portion was located substantially at the center. <Ink for Pattern Printing Layer> · Organic pigment (red) 10 parts by mass · Binder resin (main component: nitrocellulose) 10 parts by mass · Solvent (mixed solvent of ethyl acetate, methyl ethyl ketone, normal propyl acetate, isopropanol, methanol, and propylene glycol monomethyl ether) 70 parts by mass <OP varnish> An ink composition obtained by dispersing an acrylic thermosetting resin composition in an aqueous solvent (mixed solvent of water and isopropanol with a mass ratio of 3:7)

[0113] Reference Examples 1 to 4 , Comparative Examples 3 to 4 On one surface of a plastic film (PET film with a thickness of 12 μm), the above ink for pattern printing layer and coating liquid for coloring layer were applied and dried to form a pattern printing layer and a coloring layer. Thereafter, an ink for pasting process (polyvinyl alcohol) was applied on the pattern printing layer and the coloring layer and dried. The coating liquid for coloring layer and the ink for pasting process were applied in a patterned manner so that the metal decoration part would have the shape described later. Thereafter, an indium vapor deposition film (vapor-phase metal vapor deposition film) was formed by vacuum vapor deposition. The deposition time was adjusted so that the area per island of the indium vapor deposition film (nm 2 ) would be the value shown in Table 2. Next, the substrate after indium vapor deposition was immersed in water. Thereby, a metal decoration part with a circular pattern having a diameter of 5 cm was formed. Thereafter, CPP (single-layer film of ethylene-propylene block copolymer, thickness 70 μm) was laminated as a sealant layer by the dry lamination method, Reference Examples 1 to 4 , and packaging materials of Comparative Examples 3 to 4 were obtained. Reference Examples 1 to 4 , From the packaging materials of Comparative Examples 3 to 4, a test piece of 10 cm × 10 cm was cut out so that the above indium long film part was located substantially at the center.

[0114] 3. Results

[0115]

Table 1

[0116]

Table 2

[0117] Examples 1 to 6. Reference Examples 1 to 4 The packaging materials all had good initial gloss and good appearance after microwave heating. In particular, the packaging materials of Examples 2 to 5, Reference Examples 2 to 3 had excellent initial gloss and were further excellent in microwave heating resistance. In contrast, in Comparative Examples 1 and 3, although the initial gloss was good, the packaging material was greatly curved after microwave heating, and partial peeling of the metal vapor deposition part was confirmed. In Comparative Examples 2 and 4, the initial gloss was insufficient.

Explanation of Reference Numerals

[0118] 100, 200, 300, 400, 500: Packaging material 110: Paper substrate 120, 420: Metal decoration part 122, 422: Gas-phase metal vapor deposition film 124, 424: Coloring layer 126: Adhesive layer 130, 430: Pattern printing layer 132: Top coat layer 134, 434: Glitter printing layer 600: Container 602: Bottom plate 604: Side peripheral part 606: Opening 410: Plastic film 432: Sealant layer 700: Packaging box 702: Front panel 704: Side panel 706: Rear panel 708: Top panel 710: Upper part of the box 712: Bottom panel 720: Opening cut line 722: Fold line 730, 800: Pouch 732, 830: Automatic ventilation mechanism 802: Body 804: Bottom 806: Main surface sheet 806a: Front main surface sheet 806b: Back main surface sheet 808: Bottom sheet 810: Side edge 812: Lower edge 814: Upper edge 816: Accommodation space 818: Opening 820a, 820b: Heat seal part 822: Notch

Claims

1. A packaging material having a vapor-phase metal deposition film on at least a part of one surface of a base material, wherein the base material is a paper base material, The vapor-phase metal deposition film has a plurality of island portions made of metal and a sea portion located between the island portions, and the area per island portion is 4,400 nm ２ or more and 94,000 nm ２ or less (however, excluding the packaging material (wherein the surface of the packaging material has a substrate film layer on the surface having the vapor-phase metal deposition film of the substrate)).).

2. The area per island part is 24,000 nm ２ or more and 94,000 nm ２ or less. The packaging material according to claim 1.

3. The packaging material according to claim 1 or claim 2, wherein the vapor-phase metal deposition film is an indium deposition film or a tin deposition film.

4. having a bright printing layer on the one surface side of the base material, The packaging material according to any one of claims 1 to 3, wherein the bright printing layer contains at least one of a pearl pigment and metal flakes.

5. The packaging material according to claim 4, having an adhesive layer between the base material and the vapor-phase metal deposition film.

6. A packaging container formed from the packaging material according to any one of claims 1 to 5.

7. A packaging container which is a box formed of the packaging material according to claim 4 or claim 5.

8. The packaging container according to claim 7, which is an outer packaging box for a pouch.

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