Packaging materials

Abstract

To provide a packaging material which allows a content to be safely and sufficiently heated by a microwave oven, and has excellent designability due to a high level of metallic luster, and to provide a packaging container and its lid using the packaging material.SOLUTION: A packaging material is obtained by laminating a plurality of layers including a brilliant print layer. The brilliant print layer contains metal flakes, and the area of the metal when the brilliant print layer is viewed from the surface is 20% to 65% of the total area.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a packaging material, a packaging container, and a lid body in which a plurality of layers including a glittering printed layer containing metal flakes are laminated.

Background Art

[0002] From the viewpoint of creating a luxurious and upscale appearance for the packaged object to produce an aesthetic effect, packaging materials may be decorated with high-brightness metallic luster in some cases. As such a decoration means, for example, forming a metal layer such as a metal deposited film or a metal foil is generally performed.

[0003] However, there is a problem that the cost of packaging materials using a metal layer increases. Further, among metal layers, a metal deposited film has a problem of poor production efficiency because it cannot be produced in-line with other layers constituting the packaging material, and a metal foil among metal layers has a problem of difficult handleability. Furthermore, when a packaging material using a metal layer is heated in a microwave oven, microwaves in the microwave oven generate electric current on the surface of the metal layer, causing overheating and sparks, which poses a risk of damaging the container or leading to failures or accidents of the microwave oven. In addition, there is a problem that microwaves are absorbed by the metal layer, and the contents inside the packaging container may not be sufficiently heated in some cases.

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

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, packaging materials with a glossy layer formed from aluminum paste, as described in Patent Document 1, frequently exhibited a certain degree of metallic luster, but could not be said to possess a high level of metallic luster.

[0007] The present invention aims to solve the aforementioned problems and to provide a packaging material that allows the contents to be safely and thoroughly heated by a microwave oven and has excellent design qualities due to its high level of metallic luster, as well as a packaging container and lid using the said packaging material. [Means for solving the problem]

[0008] The packaging material according to the present invention is a packaging material having multiple layers laminated together, including a glossy printed layer. The structure comprises a plastic film, a printed layer, an adhesive layer, and a sealant layer, laminated in this order from the outer layer side, wherein the printed layer and the adhesive layer are adjacent to each other, and the printed layer is the glossy printed layer. The aforementioned glossy printing layer is made of metal flakes and binder resin It contains, The image was obtained by measuring a 250 μm × 250 μm area with a 1000x optical microscope and then binarizing the resulting image. The aforementioned glossy printing layer The aforementioned packaging material The aforementioned problem is solved by ensuring that the area of ​​metal as seen from the surface is between 20% and 65% of the total area. [Effects of the Invention]

[0009] According to the packaging material of claim 1, the glossy printing layer is made of metal flakes and binder resin It contains, The image was obtained by measuring a 250 μm × 250 μm area with a 1000x optical microscope and then binarizing the resulting image. The glossy printing layer Packaging materials By having a metal surface area of ​​20% to 65% of the total surface area, it is possible to achieve a high level of metallic luster while safely and thoroughly heating the contents in a microwave oven. The glossy printing layer Packaging materials If the visible surface area of ​​metal is less than 20% of the total surface area, sufficient metallic luster cannot be obtained. If it exceeds 65%, there is a high possibility that microwaves will generate an electric current in the layer of metal flakes, causing overheating and sparks, or that the microwaves will be absorbed, preventing sufficient heating of the contents inside the packaging container. Furthermore, if the concentration of metal flakes is high, the metal flakes may accumulate on the doctor blade when the ink is scraped during the printing process, and these accumulated metal flakes may adhere to the printed material as foreign matter. Therefore, an area ratio of 20-50% is preferred, and 20-40% is more preferred.

[0010] According to the configuration described in claim 2, the metal flakes have an aspect ratio expressed as average particle size / thickness of 100 or more, which suppresses diffuse reflection and allows for an even higher level of metallic luster. [Brief explanation of the drawing]

[0011] [Figure 1] Cross-sectional view of a packaging material according to one embodiment of the present invention. [Modes for carrying out the invention]

[0012] The packaging material according to the present invention comprises a plurality of layers including a glossy printed layer, for example, a plastic film, a printed layer, an adhesive layer, and a sealant layer, which are laminated in this order from the outer layer side, with the printed layer and the adhesive layer being adjacent to each other, and the printed layer having a glossy printed layer containing metal flakes and a binder resin.

[0013] As shown in Figure 1, the thickness-direction lamination structure of the packaging material 100 according to one embodiment of the present invention consists of a plastic film 110, a printed layer (a printed layer having a glossy printed layer 121), an adhesive layer 131, and a sealant layer 150, which are laminated in this order from the outer layer side (the top of the figure is the outer layer side, and the bottom is the inner layer side). Furthermore, the packaging material 100 has an intermediate material layer 140 and other adhesive layers 132 between the printing layer and the sealant layer 150. Furthermore, the printed layer may be a glossy printed layer 121 covering the entire surface of the packaging material 100 or only a part of it, a pattern printed layer may be provided on the outer side of the glossy printed layer 121, a pattern printed layer may be provided in parallel with the glossy printed layer 121, or a solid printed layer may be provided on the inner side of the glossy printed layer 121. Further, patterns such as characters, figures, symbols, designs, and motifs may be formed by the glittery printed layer 121. Furthermore, a gas barrier layer may be formed between the plastic film 110 and the printed layer, or between the printed layer and the sealant layer 150.

[0014] The plastic film 110 functions as a base material on the outer layer side of the packaging material 100, and is composed of a light-transmitting material so that the glittery printed layer 121 can be visually recognized from the exterior. Examples include polyolefin resins such as polyethylene (PE)-based and polypropylene (PP)-based resins, 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, polyvinylidene chloride resins (PVDC), and the like. The plastic film may be uniaxially stretched 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.

[0015] From the perspective of microwave heating and retort treatment, the plastic film 120 preferably has excellent heat resistance, and polyester resins, polyamide resins and the like with excellent heat resistance are suitable. Further, other specific examples of plastic films with excellent heat resistance 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 co-extruded stretched film having a configuration of PET / Ny from the outer layer side. Further, as the composite film, one or more of a polyester film and a polyamide film may be combined with one or more of an ethylene-vinyl alcohol copolymer film and a polyvinylidene chloride film.

[0016] The glitter pigment used in the glitter print layer 120 contains metal flakes. When the glitter print layer 120 is viewed from the surface, the area of the metal accounts for 20% to 65% of the total area. The metal flakes are flat and scaly, and have an aspect ratio represented by average particle size / thickness of 100 or more. Examples of the material of 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 peeling a metal thin film formed by vacuum-depositing the aforementioned metal or alloy on a plastic film from the plastic film, then pulverizing and stirring the peeled metal thin film, or by mixing the aforementioned metal or alloy powder with a solvent, and spreading and / or pulverizing the powder using a medium stirring mill, a ball mill, an attritor or the like, and further, those whose surfaces are coated with a resin can also be used.

[0017] When the glitter print layer 120 is viewed from the surface, the relationship between the area ratio of the metal to the total area, the glitter feeling, and the microwave resistance is as shown in Table 1 below. [Table 1] The metal flakes are aluminum flakes having an average particle size of 9 μm, a thickness of 0.08 μm, and an aspect ratio of 113. The area ratio was calculated by measuring a 250 μm × 250 μm area with a 1000x optical microscope and then binarizing the resulting image. The luminosity was assessed through a sensory test conducted by 20 panelists who examined the appearance. For the sensory evaluation, each sample was rated on a four-point scale: (1 point) no metallic luster at all, (2 points) slight metallic luster, (3 points) metallic luster, and (4 points) strong metallic luster. The average score of 20 people was used to determine the ratings: ◎ for 3.5 points or higher, ○ for 2.5 points or higher but less than 3.5 points, △ for 1.5 points or higher but less than 2.5 points, and × for less than 1.5 points. Microwave resistance was tested by placing the packaging material in a pouch, heating it at 1900W for 1 minute, and then inspecting the surface of the pouch. Products with no abnormalities were marked with ○, while those showing signs of overheating or melting due to sparks were marked with ×.

[0018] As can be seen from Table 1, a sufficient metallic luster can be obtained if the area ratio is 20% or more. Furthermore, regarding microwave resistance, melting marks were observed at a surface area ratio of 75%, but not at a surface area ratio of 65% or less. Therefore, even considering the possibility of uneven distribution of metal flakes or uneven distribution of microwaves, there should be no problem using the microwave if the surface area ratio is 65% or less.

[0019] The relationship between the aspect ratio, glossiness, and microwave resistance of metal flakes is shown in Table 2 below. [Table 2] Packaging materials containing aluminum flakes of each aspect ratio, each with a surface area ratio of 20%, were created and evaluated for glossiness and microwave resistance in the same manner as described above.

[0020] As can be seen from Table 2, regarding luster, metallic luster cannot be obtained at aspect ratios of 90 or less, but sufficient metallic luster can be obtained at aspect ratios of 112.5 or higher. Therefore, it can be concluded that a practical metallic luster can be obtained at aspect ratios of 100 or higher. Furthermore, regarding microwave resistance, there are no issues with any aspect ratio when the surface area ratio is 20%. [Explanation of Symbols]

[0021] 100 Packaging materials 110 Plastic film 121 Glitter printing layer 131 Adhesive layer 132 Adhesive layer 140 Intermediate material layer 150 sealant layer

Claims

1. A packaging material comprising multiple layers including a glossy printed layer, The structure comprises a plastic film, a printed layer, an adhesive layer, and a sealant layer, laminated in this order from the outer layer side, wherein the printed layer and the adhesive layer are adjacent to each other, and the printed layer is the glossy printed layer. The aforementioned glossy printing layer contains metal flakes and binder resin, A packaging material characterized in that the metallic area of ​​the glossy printed layer, when viewed from the surface of the packaging material, is 20% to 65% of the total area, calculated by binarizing an image obtained by measuring a 250 μm x 250 μm area with a 1000x optical microscope.

2. The packaging material according to claim 1, characterized in that the metal flakes have an aspect ratio expressed as average particle size / thickness of 100 or more.

3. A packaging container in which at least a portion is formed of the packaging material described in claim 1 or 2.

4. A lid, at least in part, formed from the packaging material described in claim 1 or 2.

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