JP2023084443A - Decorative sheet, packaging box, and package - Google Patents

Abstract

To provide a decorative sheet which has excellent durability while having water-resistant paper.SOLUTION: A decorative sheet 10 has water-resistant paper 11, a resin coat layer 12, a biaxially stretched polypropylene film 13, an adhesive layer 14, a PET film 16, and a metal film 18 in this order. The water-resistant paper 11 and the resin coat layer 12 are brought into direct contact with each other. The resin coat layer 12 is composed of a hot-melt adhesive containing a polyolefin-based resin.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to decorative sheets, packaging boxes, and packages.

BACKGROUND ART A plastic packaging bag is known as a packaging container for storing an item to be packaged. For example, Patent Literature 1 proposes a package having a packaging bag having an opening for storing wet tissues and taking out the wet tissues, and a releasable label attached around the opening.

On the other hand, in order to improve the decorativeness of the packaging container, there is known a decorative sheet provided with a plastic film having a metal film having metallic luster on a paper substrate. Patent Document 2 proposes a container using such a decorative sheet.

JP-A-2015-85968 JP 2019-5940 A

If plastic containers can be partially replaced with paper containers, waste can be reduced and resources can be effectively used. However, if the packaging container of the type in which the opening and closing label is repeatedly peeled and adhered as in Patent Document 1 is configured with the decorative sheet containing paper as in Patent Document 2, a large amount of material is applied to the portion where the opening and closing label is adhered. load. In the case of packaging an object containing moisture in such a packaging container, it is effective to improve the water resistance by using waterproof paper. However, it has been found that when water-resistant paper is used, a laminate such as a metal film provided on the water-resistant paper is easily peeled off, especially at the location where the opening/closing label is adhered.

The present disclosure provides a decorative sheet that has excellent durability while being equipped with waterproof paper. The present disclosure also provides packaging boxes and packages that have excellent durability.

In one aspect, the present disclosure includes water-resistant paper, a resin coat layer, a biaxially oriented polypropylene film, an adhesive layer, a PET film, and a metal film in this order, and the water-resistant paper and the resin coat layer. To provide a decorative sheet in direct contact with Since this decorative sheet is provided with a metal film, it is excellent in decorativeness. Since the surface of water-resistant paper is usually smooth, it tends to be difficult to adhere, but the decorative sheet has a resin coating layer that is in direct contact with the water-resistant paper. Since the resin coat layer is a resin layer that reinforces the surface of the water-resistant paper, the adhesion to the water-resistant paper can be sufficiently enhanced. In addition to the resin coat layer, a biaxially oriented polypropylene film, an adhesive layer, and a PET film are provided between the waterproof paper and the metal film. Therefore, it has excellent durability.

The resin coat layer in the decorative sheet is preferably made of a hot-melt adhesive containing a polyolefin resin. Such a resin coat layer has excellent adhesion to waterproof paper. Therefore, the durability of the decorative sheet can be further improved.

It is preferable that the resin component contained in the hot-melt adhesive is permeated into the waterproof paper by thermocompression bonding. As a result, the adhesive strength between the resin coat layer and the water-resistant paper is sufficiently increased, and the durability can be further increased.

It is preferable that the water-resistant paper has a pigment-containing layer, and the pigment-containing layer and the resin coat layer are in direct contact with each other. The decorativeness can be improved by having the pigment-containing layer. Since the pigment-containing layer usually contains a particulate pigment, it has a smooth surface and tends to be difficult to adhere to adjacent layers. Since the decorative sheet has a resin coat layer with excellent adhesion to water-resistant paper, it is possible to maintain sufficiently high durability.

The water-resistant paper preferably has a pigment-containing layer, and the resin component contained in the hot-melt adhesive permeates the pigment-containing layer. As a result, the adhesive strength between the resin coat layer and water-resistant paper, which usually tends to be difficult to adhere to, becomes sufficiently high, and the durability can be further enhanced.

The edgewick value when the decorative sheet is immersed in water at 23° C. for 24 hours is preferably 1.5 mg/mm ² or less. Such a decorative sheet is even more excellent in water resistance.

The decorative sheet preferably has ruled lines including recesses or through holes on at least one surface. By using such a decorative sheet, an assembly such as a packaging box can be easily produced.

The decorative sheet preferably has an ink layer between the waterproof paper and the resin coat layer. This makes it possible to improve the design.

In one aspect, the present disclosure provides a packaging box that includes a box made of any of the decorative sheets described above.

This packaging box includes a box made of any one of the decorative sheets described above. Therefore, it has excellent durability. Therefore, for example, even if the lid label, which has an adhesive sealing surface and seals the opening of the box, is repeatedly opened and closed, the decorative sheet constituting the box is sufficiently prevented from being damaged. be able to.

In one aspect, the present disclosure provides a package including the above packaging box and an item to be packaged housed in the packaging box. Since this package includes the packaging box described above, it has excellent durability.

It is possible to provide a decorative sheet having excellent durability while being equipped with waterproof paper. In addition, it is possible to provide a packaging box and package having excellent durability.

It is a sectional view showing a decoration sheet concerning one embodiment. 2 is a diagram schematically showing the internal structure of a pigment-containing layer of waterproof paper in the decorative sheet of FIG. 1. FIG. 4 shows the measurement results of infrared spectroscopic analysis (IR) on the release surface of the decorative sheet of Example 1. FIG. 4 shows the measurement results of infrared spectroscopic analysis (IR) on the release surface of the decorative sheet of Comparative Example 3. FIG.

An embodiment of the present invention will be described below with reference to the drawings as the case may be. However, the following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and overlapping descriptions are omitted in some cases.

The decorative sheet 10 of FIG. 1 comprises waterproof paper 11, resin coat layer 12, biaxially oriented polypropylene film 13, adhesive layer 14, PET film 16, and metal film 18 in this order. The water-resistant paper 11 comprises, from the surface 10A side of the decorative sheet 10, a resin layer 11a composed of resin, a paper layer 11b containing resin and paper material such as pulp, and a pigment-containing layer 11c containing pigment. have in order. "PET" is an abbreviation for polyethylene terephthalate.

From the viewpoint of improving water resistance, it is preferable that the resin layer 11a does not contain a pigment. The resin contained in the paper layer 11b and the resin forming the resin layer 11a may be of the same kind or may be different from each other. Acrylic resin is mentioned as resin which comprises the resin layer 11a, and resin contained in the paper layer 11b.

Pigments contained in the pigment-containing layer 11c include white pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, and light calcium carbonate. However, the types of pigments are not limited to these, and include various pigments such as purple pigments and blue pigments.

The pigment-containing layer 11c may contain one pigment alone, or may contain two or more pigments in combination. The pigment-containing layer 11c may contain particulate pigment together with a binder, a filler, a fluorescent dye, and the like for binding them together. The pigment-containing layer 11c may be a layer called a clay layer.

The basis weight of the waterproof paper 11 may be, for example, 100-800 g/m ² , and may be 200-600 g/m ² . This makes it possible to achieve both sufficient strength and good assemblability. The thickness of the waterproof paper 11 may be 100-800 μm, or may be 200-600 μm.

The edgewick value of the waterproof paper 11 measured by immersing it in water at 23° C. for 24 hours is preferably less than 4 mg/mm ² , more preferably less than 2 mg/mm ² , still more preferably 1.6 mg/mm 2 . less than ^mm2 . As a result, the water resistance of the decorative sheet 10 can be sufficiently enhanced.

The edgewick value in this specification can be measured by the following procedure. A laminate film is attached to the entire front and back surfaces of the waterproof paper to be measured. Then cut into rectangles (15 mm x 100 mm) to obtain test samples. Measure the mass of the test sample prior to water immersion. After the test sample is immersed in water at 23° C. for 1-24 hours, it is removed from the water and the test sample is weighed. The edgewick value can be calculated by the following formula from the mass of the test sample before and after immersion in water.
Edgewick value = difference in mass of test sample before and after immersion / total area of 4 end faces of waterproof paper after cutting

Since the resin layer 11a of the waterproof paper 11 forming one surface 10A of the decorative sheet 10 is made of resin, it is possible to suppress the absorption of moisture from the surface 10A. In addition, in the modification, the resin layer 11a may not be provided, and the paper layer 11b may be exposed on the surface 10A. Since the paper layer 11b also contains a resin, sufficient water resistance can be maintained without the resin layer 11a.

The structure of the waterproof paper is not limited to the one described above, and various types of paper having improved water resistance due to the inclusion of a resin component can be used. The water-resistant paper may be produced by a known method, or a commercially available product may be used. Commercially available products include "N Mitsubishi Water Resistant" manufactured by Mitsubishi Paper Mills, Ltd., and "Ecovally V" and "Ecovally K" manufactured by Nippon Paper Industries Co., Ltd., and the like.

The resin coat layer 12 may be made of a hot melt adhesive. Hot-melt adhesives include those containing polyolefin-based resins, ethylene-vinyl acetate-based resins, acrylic-based resins, or urethane-based resins as resin components. Among them, the resin coat layer 12 is preferably made of a hot-melt adhesive containing a polyolefin resin. As a result, when the resin coat layer 12 and the biaxially stretched polypropylene film 13 are in direct contact with each other, their affinity is improved, and the adhesion between them can be further enhanced.

The polyolefin-based resin herein includes repeating units of olefin. For example, it may be a kind of polyolefin homopolymer (that is, polyethylene, polypropylene, etc.) or an olefinic copolymer. The olefinic copolymer has structural units derived from olefins and structural units derived from monomers other than olefins. Structural units derived from olefins may account for 50% by mass or more of the total resin.

More preferably, the resin coat layer 12 is made of a hot-melt adhesive containing a polyethylene-based resin. As a result, the flexibility is improved, the work of folding the decorative sheet is further facilitated, and the packaging box can be easily produced. Moreover, when the packaging box is produced, it is possible to sufficiently suppress the peeling of the layers at the bent portion. Moreover, if the hot-melt adhesive contains a polyethylene-based resin, the resin coat layer 12 and the biaxially stretched polypropylene film 13 can be press-bonded only by thermal lamination. Therefore, the manufacturing process of the decorative sheet 10 can be simplified. When manufacturing the decorative sheet, the resin coat layer 12 may be formed by using a commercially available hot melt adhesive, or by using a biaxially oriented polypropylene film on which a hot melt adhesive layer is formed, The resin coat layer 12 and the biaxially stretched polypropylene film 13 may be combined together. Examples of hot melt adhesives include "Lamitac MSOK" (trade name) manufactured by J Film Co., Ltd., and "7327KA/SA" (trade name) manufactured by Cosmo Film Japan LLC.

The polyethylene-based resin herein contains methylene repeating units. For example, it may be an ethylene homopolymer (that is, polyethylene) or an ethylene-based copolymer. Ethylene-based copolymers have structural units derived from ethylene and structural units derived from monomers other than ethylene. Structural units derived from ethylene may account for 50% by mass or more of the total resin.

The resin coat layer 12 and the pigment-containing layer 11c of the waterproof paper 11 are in direct contact. This allows the resin components forming the resin coat layer 12 to smoothly permeate into the waterproof paper 11 . The permeating resin component includes a resin component (for example, polyolefin resin) that constitutes the resin in the resin coat layer 12 . By infiltrating such a resin component to form a resin component-impregnated layer in the pigment-containing layer 11c of the water-resistant paper 11, the adhesive strength between the water-resistant paper 11 and the resin coating layer 12 can be sufficiently increased. The waterproof paper 11 containing such a resin component can improve the durability of the decorative sheet 10 .

FIG. 2 schematically shows the internal structure of the pigment-containing layer 11c of the waterproof paper 11 in the decorative sheet 10. As shown in FIG. When the hot-melt adhesive that is heated and has fluidity is thermocompression bonded to the surface of the pigment-containing layer 11c, the resin component 63 contained in the hot-melt adhesive permeates into the pigment-containing layer 11c. The pigment-containing layer 11 c may contain the resin component only partially, or may have a concentration gradient portion in which the concentration of the resin component increases as it approaches the resin coat layer 12 . As a result, the strength at the boundary between the portion containing the resin component 63 and the portion not containing the resin component 63 can be sufficiently increased while the adhesion to the resin coat layer 12 is sufficiently increased.

The permeated resin component 63 agglomerates the pigment 61 and other components contained in the pigment-containing layer 11c and binds them together. As a result, the cohesive force of each component contained in the pigment-containing layer 11c is increased, and the durability of the pigment-containing layer 11c can be improved. In addition, the resin component 63 that permeates the pigment-containing layer 11 c also bonds with the resin component contained in the resin coat layer 12 . Thereby, the adhesive strength between the waterproof paper 11 and the resin coat layer 12 can be improved.

The thickness of the resin-impregnated layer formed by impregnating the pigment-containing layer 11c with the resin component 63 may be, for example, 10 μm or more, or may be 15 μm or more. By increasing this thickness, the durability of the pigment-containing layer 11c can be further increased. From the viewpoint of increasing the thickness of the resin-impregnated layer by promoting the permeation of the resin component 63 into the pigment-containing layer 11c, the hot-melt adhesive preferably has a low melting point.

Returning to FIG. 1, the thickness of the resin coat layer 12 is preferably 5 to 30 μm, more preferably 10 to 20 μm. As a result, the water-resistant paper 11 can be easily folded, and the cohesive force of the water-resistant paper 11 can be improved to sufficiently increase the durability.

It is preferable to provide an ink layer partially between the waterproof paper 11 and the resin coat layer 12 . This makes it possible to improve the design. Even if the ink layer is provided in a part between the water-resistant paper 11 and the resin coat layer 12, the other part between the water-resistant paper 11 and the resin coat layer 12 has high adhesion between the water-resistant paper 11 and the resin coat layer 12. It is attached by force. Therefore, even if an ink layer is partially provided between the waterproof paper 11 and the resin coat layer 12, good adhesiveness can be maintained.

The thickness of the biaxially stretched polypropylene film 13 is preferably 5-40 μm, more preferably 10-30 μm. As a result, it is possible to achieve both the ease of bending and the adhesive strength at a sufficiently high level.

The adhesive layer 14 has the function of bonding the biaxially oriented polypropylene film 13 and the PET film 16 together. Examples of adhesives contained in the adhesive layer 14 include polyvinyl alcohol-based adhesives, polyurethane-based adhesives, polyester-based adhesives, polyether-based adhesives, epoxy-based adhesives, polyethyleneimine-based adhesives, and polybutadiene-based adhesives. Adhesives are included. Among these, from the viewpoint of further improving water resistance, it is preferable to contain an epoxy-based adhesive. The thickness of the adhesive layer 14 is preferably 1-10 μm, more preferably 3-8 μm. This makes it possible to achieve both ease of bending and durability at a sufficiently high level.

The surface of the PET film 16 facing the adhesive layer 14 may be subjected to at least one treatment selected from chemical treatment, solvent treatment, corona treatment, plasma treatment, and ozone treatment. The thickness of the PET film 16 is not particularly limited, and may be, for example, 3-50 μm or 6-30 μm.

Metal film 18 may comprise aluminum, tin, indium, nickel, copper, silver, gold, platinum, brass, chromium or zinc, or alloys of these metals. One of these may be contained alone, or two or more of them may be contained in combination. The metal film 18 can be produced by, for example, a vacuum deposition method, a sputtering method, or an ion plating method. The thickness of the metal film 18 is preferably 10-100 μm. As a result, it is possible to manufacture the decorative sheet 10 having a metallic luster and excellent decorativeness at a low cost.

A metal-deposited film or a metal-foil-laminated film in which the PET film 16 and the metal film 18 are integrated may be used. Thereby, the manufacturing process of the decorative sheet 10 can be simplified. An ink layer may be provided on the surface 10B of the decorative sheet 10 on the metal film 18 side. This makes it possible to obtain decorative sheets with various designs. Since the decorative sheet 10 has an excellent appearance, it can be suitably used as an exterior material for packaging containers, a plate material for packaging boxes, and the like.

An example of a method for manufacturing the decorative sheet 10 will be described. A resin coat layer 12 is formed on one surface of water-resistant paper 11 . For example, a hot-melt adhesive is applied to the surface of the waterproof paper 11 on the side of the pigment-containing layer 11c using a hot-melt coater or a hot-melt gun. A biaxially oriented polypropylene film 13 is laminated on the applied hot melt adhesive. Instead of this method, a laminate in which a hot-melt adhesive layer is provided on one side of the biaxially oriented polypropylene film 13 may be used. In this case, the water-resistant paper 11 and the laminate are pasted together so that the hot-melt adhesive layer and the pigment-containing layer 11c of the water-resistant paper 11 face each other. By using such a laminate, the manufacturing method can be simplified.

Adhesive is applied to one side of the biaxially oriented polypropylene film 13 bonded to the water-resistant paper 11, and the biaxially oriented polypropylene film 13 and the PET film 16 of metallized film or metal foil laminated film are bonded via the adhesive. to paste together. Thereby, the decorative sheet 10 having the PET film 16 and the metal film 18 on the adhesive layer 14 can be manufactured.

The decorative sheet 10 has good adhesion of each layer (film or film) between the waterproof paper 11 and the metal film 18 . Therefore, delamination of the decorative sheet 10 can be sufficiently suppressed even if the decorative sheet 10 is subjected to bending or continued to be used under conditions in which tensile stress is repeatedly generated along the stacking direction. For this reason, for example, it can be suitably used as a plate material for a packaging box to which a lid label is adhered. In particular, it is suitable as a plate material for a packaging box in which the lid label is repeatedly adhered and peeled off. Moreover, since the waterproof paper 11 is provided, the durability can be maintained even if it comes into contact with moisture. Therefore, the article to be packaged may be an impregnated body impregnated with water, an aqueous solution, an emulsion, or the like.

The decorative sheet 10 may be a paper pattern (mounting paper) having ruled lines on at least one of the surfaces 10A and 10B, which serve as starting points for folding. The ruled line may be a groove (recess), or the through hole may be formed in a perforation. As a result, the packaging box can be produced smoothly using the decorative sheet 10 .

The thickness of the decorative sheet 10 is preferably 500 to 700 μm, more preferably 500 to 600 μm, from the viewpoint of smooth folding and high rigidity of the packaging box. The decorative sheet 10 is folded so that the waterproof paper 11 is inside and the metal film 18 is outside. As a result, it is possible to obtain a packaging container and a packaging body that can maintain excellent durability even when an object containing moisture is packaged. Since such a packaging container and package have the metal film 18 on the outer surface side, they are excellent in cosmeticity. Moreover, since the waterproof paper 11 is included, the amount of plastic waste can be reduced and resources can be effectively used.

The edgewick value of the decorative sheet 10 when immersed in water at 23° C. for 24 hours is preferably 3.0 mg/mm ² or less, more preferably 2.0 mg/mm ² or less, and still more preferably 1.0 mg/mm 2 or less. 5 mg/mm ² or less. By reducing the edgewick value of the decorative sheet 10, the durability of the decorative sheet 10 against moisture can be increased. The edgewick value of the decorative sheet 10 can be measured by the same method as the edgewick value of the waterproof paper 11 .

The peel adhesive strength between the waterproof paper 11 and the resin coat layer 12 in the decorative sheet 10 is preferably 3 [N/15 mm] or more, more preferably 5 [N/15 mm] or more, and still more preferably 7. [N/15 mm] or more. In the decorative sheet 10 including the water-resistant paper 11, the surface of the pigment-containing layer 11c of the water-resistant paper 11 is smooth. Become. Therefore, the above-described decorative sheet 10 having a high peeling adhesive strength can suppress peeling between the waterproof paper 11 and the metal film 18, and thus has sufficiently excellent durability. The above-mentioned peel adhesive strength is a value measured by the measuring method (without water immersion) described in Examples.

The decorative sheet 10 may be assembled into a packaging box. A packaging box composed of the decorative sheet 10 having excellent durability and excellent water resistance may be used to package an impregnated body (wet tissue, etc.) in which a fibrous material is impregnated with a washing liquid such as alcohol or a lotion. . That is, the decorative sheet 10 may be used for packaging boxes for such impregnated bodies. The decorative sheet 10 can maintain sufficient durability even when it comes into contact with liquid such as water or alcohol. However, the application of the decorative sheet 10 is not limited to this.

A package according to one embodiment includes a packaging box and an item to be packaged housed in the packaging box. If the packaging box is composed of the decorative sheet 10, at least part of it can be recycled. The packaging box and the package including the same may be of a type that has an adhesive sealing surface and that repeatedly opens and closes the lid label that seals the opening of the box. In the case of such a packaging box, when the sealing surface of the lid label and the packaging box are repeatedly adhered and peeled off, a large load (tensile stress) is applied to the portion where the sealing surface of the lid label is adhered. If the decorative sheet 10 is used for such a portion, it is possible to sufficiently suppress delamination, breakage, etc. of the portion even if the cover label is repeatedly opened and closed. Therefore, even if the packaging box is not provided with a reinforcing film, the packaging box and the package have sufficiently excellent durability. Since it is not necessary to provide a reinforcing film, the manufacturing process of the packaging box (package) can be simplified, and the appearance of the packaging box (package) can be further improved.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the decorative sheet may have arbitrary layers. Also, the outer shape of the packaging box and package is not limited to those shown in the drawings.

The contents of the present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[Production of decorative sheet]
(Example 1)
Commercially available waterproof paper (“N Mitsubishi Water Resistant” manufactured by Mitsubishi Paper Mills, Ltd., weighing 350 g/m ² ) was prepared. This waterproof paper had a two-layer structure having a paper layer containing a paper material such as resin and pulp, and a pigment-containing layer containing a pigment (clay). A laminate (Lamitac MSOK (trade name) manufactured by J Film Co., Ltd.) in which a hot-melt adhesive layer containing a polyethylene resin is provided on one side of a biaxially oriented polypropylene film (thickness: 20 μm) was prepared. The hot-melt adhesive layer of the article and the pigment-containing layer of the water-resistant paper were placed facing each other, and the water-resistant paper and the laminate were superimposed, heated, and adhered to obtain a laminate.

A metal vapor deposition film in which an aluminum vapor deposition film (thickness: 10 to 100 nm) is formed on a PET film (thickness: 12 μm), and a polyurethane adhesive (main agent: AD391-A (trade name), curing agent: AD391-B) (trade name), both manufactured by Toyo-Morton Co., Ltd.) were prepared. By dry lamination, the laminate and the metallized film were adhered such that the PET film and the biaxially oriented polypropylene film faced each other through the adhesive. In this way, the waterproof paper, the resin coat layer composed of the hot melt adhesive, the biaxially oriented polypropylene film, the epoxy adhesive layer, the PET film, and the metal film (aluminum deposition film) are combined. A decorative sheet provided in this order was obtained.

(Example 2)
Commercially available waterproof paper (“Ecobarry K” manufactured by Nippon Paper Industries Co., Ltd., weight: 400 g/m ² ) was prepared. As shown in FIG. 1, this water-resistant paper is a laminate having a resin layer 11a made of resin, a paper layer 11b containing resin and paper material such as pulp, and a pigment-containing layer 11c containing pigment (clay). had a structure. A decorative sheet was produced in the same manner as in Example 1, except that this waterproof paper was used. The decorative sheet of Example 2 had the laminated structure shown in FIG.

(Comparative example 1)
The water-resistant paper used in Example 1 was used as Comparative Example 1.

(Comparative example 2)
General paper (basis weight: 310 g/m ² , OK FACE PRO (trade name), manufactured by Oji Paper Co., Ltd.), which is not waterproof paper, was prepared. By dry lamination, the general paper and the metal-deposited film were adhered together with the PET film and the general paper facing each other via a polyurethane-based adhesive (coating amount: 4.3 g/m ² ). Thus, a decorative sheet having a laminated structure consisting of ordinary paper, an adhesive layer, a PET film and a metal film (aluminum deposition film) was obtained.

(Comparative Example 3)
A decorative sheet was produced in the same manner as in Example 1, except that the resin coat layer and the biaxially oriented polypropylene film were not provided. That is, a decorative sheet was obtained by adhering a pigment-containing layer of water-resistant paper and a PET film of metallized film with a polyurethane-based adhesive. This decorative sheet had a laminated structure consisting of waterproof paper, an adhesive layer, a PET film and a metal film (aluminum deposition film).

(Comparative Example 4)
The water-resistant paper used in Example 2 was used as Comparative Example 4.

[Measurement of edgewick value]
A laminate film was attached to the entire front and back surfaces of the decorative sheets obtained in each example and each comparative example. It was then cut into rectangles (15 mm x 100 mm) to obtain test samples. Subsequently, the mass of the test sample before water immersion was measured. After that, it was immersed in water at 23° C. for 1 to 24 hours, removed from the water, and the mass of the test sample was measured. The edgewick value was calculated by the following formula from the mass of the test sample before and after immersion in water. The results were as shown in Table 1.
Edgewick value = difference in mass of test sample before and after immersion/total area of four end faces of decorative sheet after cutting

[Measurement of peel adhesive strength]
The decorative sheets obtained in each example and each comparative example were cut to obtain rectangular (15 mm×100 mm) test samples. The peel adhesive strength of each decorative sheet was measured according to JIS K 6854-1:1999. The test samples after measuring the Edgewick value were also measured in the same manner. The specific procedure for measuring the peel adhesive strength was as follows. After peeling the interlayer (interface between waterproof paper and resin coat layer) at the edge, using a tensile tester under the conditions of angle: 180 °, tensile speed: 300 mm / min, and 20 ° C., peel adhesion strength between layers was measured. Table 1 shows the measurement results of the peel adhesive strength. In Table 1, "without water immersion" is the measured value when the edgewick test is not performed, and "after water immersion" is the measured value after the edgewick test is performed. The numerical unit of the edgewick value in Table 1 is "mg/mm ² ", and the numerical unit of the peel adhesive strength is "N/15 mm".

Comparing the edgewick values of Example 1 and Comparative Examples 1, 2 and 3 using the same waterproof paper, the edgewick value of Example 1 having a resin coat layer and a biaxially oriented polypropylene film was the lowest. A similar tendency was observed when comparing Example 2 and Comparative Example 4 using the same waterproof paper. From this, it was confirmed that the edgewick value can be reduced by providing the resin coat layer and the biaxially stretched polypropylene film.

From the results of the peel adhesive strength, it was confirmed that Examples 1 and 2 had sufficiently higher adhesive strength than Comparative Examples 1-4. Moreover, it was confirmed that Examples 1 and 2 could maintain sufficient durability even in contact with moisture.

After measuring the peel adhesion strength of Examples 1 and 2 and Comparative Example 3, the peel surface of each measurement sample was visually observed. It was confirmed that IR measurement was performed on the peeled surfaces of Example 1 and Comparative Example 3 (both samples were not immersed in water). FIG. 3 shows the IR measurement results of the release surface of the decorative sheet of Example 1 (absorption spectrum "1" for the release surface on the waterproof paper side, absorption spectrum "2" for the release surface on the metal film side). . FIG. 3 also shows the absorption spectrum of the pigment-containing layer side of the waterproof paper used in Example 1 as a control "3". According to this result, the water-resistant paper itself (absorption spectrum 3), which is the control, does not have an absorption peak near 2900 cm ⁻¹ , whereas the peeling surface of the water-resistant paper side (absorption spectrum 1) and the metal film side show a An absorption peak was detected near 2900 cm ⁻¹ in both planes (absorption spectrum 2). It is considered that this absorption peak originates from the stretching vibration of the carbon-hydrogen bond of alkane by the resin component constituting the resin coating layer (polyethylene resin).

That is, in the decorative sheet of Example 1, the pigment-containing layer of the waterproof paper was peeled off, but a peak derived from the resin component constituting the resin coating layer was also detected on the peeled surface of the waterproof paper side. , it is shown that the resin component contained in the polyethylene resin permeates the waterproof paper. It is considered that the adhesion between the water-resistant paper and the resin-coated layer is improved and the water resistance is also improved by containing the resin component derived from the resin coat layer adjacent to the water-resistant paper.

FIG. 4 shows IR measurement results of the release surface of the decorative sheet of Comparative Example 3 (the release surface on the waterproof paper side and the release surface on the metal film side). FIG. 4 also shows the IR measurement results of the pigment-containing layer side of the waterproof paper used in Example 1 as a control. The meanings of symbols 1, 2 and 3 in FIG. 4 are the same as in FIG. In Comparative Example 3, the waterproof paper itself was torn and peeled off, but both the peeled surface on the waterproof paper side and the peeled surface on the metal film side showed the same spectrum as the waterproof paper itself. Therefore, it is considered that the resin component does not permeate from the adjacent adhesive layer to the pigment-containing layer of the waterproof paper.

According to the present disclosure, it is possible to provide a decorative sheet having excellent durability while being equipped with waterproof paper. In addition, it is possible to provide a packaging box and a packaging body having excellent durability while being equipped with waterproof paper.

DESCRIPTION OF SYMBOLS 10... Decorative sheet 10A, 10B... Surface 11... Waterproof paper 11a... Resin layer 11b... Paper layer 11c... Pigment-containing layer 12... Resin coat layer 13... Biaxially oriented polypropylene film 14... Adhesive Layer, 16... PET film, 18... Metal film.

Claims (9)

A decorative sheet comprising water-resistant paper, a resin coat layer, a biaxially oriented polypropylene film, an adhesive layer, a PET film, and a metal film in this order, wherein the water-resistant paper and the resin coat layer are in direct contact. . 2. The decorative sheet according to claim 1, wherein said resin coat layer comprises a hot-melt adhesive containing polyolefin resin. 3. The decorative sheet according to claim 2, wherein the resin component contained in the hot-melt adhesive permeates the waterproof paper. 4. The decorative sheet according to claim 2, wherein said water-resistant paper has a pigment-containing layer, and a resin component contained in said hot-melt adhesive permeates said pigment-containing layer. The decorative sheet according to any one of claims 1 to 4, which has an edgewick value of 1.5 mg/mm ² or less when immersed in water at 23°C for 24 hours. 6. The decorative sheet according to any one of claims 1 to 5, having ruled lines including recesses or through holes on at least one surface. The decorative sheet according to any one of claims 1 to 6, comprising an ink layer between the waterproof paper and the resin coat layer. A packaging box comprising a box made of the decorative sheet according to any one of claims 1 to 7. A package comprising: the packaging box according to claim 8; and an object to be packaged accommodated in the packaging box.

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