Adhesive sheets, packaging materials and packaging bodies

Abstract

To provide an adhesive sheet that is highly re-peelable and has excellent water vapor barrier properties, and to provide a packaging material and a package body equipped with the adhesive sheet. [Solution] The adhesive sheet of the present invention is an adhesive sheet used in packaging materials for storing items containing moisture, comprising a base material made of a pulp-containing material, a laminate layer provided on one side of the base material and made of a thermoplastic resin-containing material, and an adhesive layer provided on the side of the laminate layer opposite to the side facing the base material, characterized in that the wet tensile strength in the longitudinal direction of a test piece of the base material, as determined by a test in accordance with JIS P8135, is 2.0 kN / m or more.

Description

[Technical Field]

[0001] The present invention relates to adhesive sheets, packaging materials, and packaging bodies. [Background technology]

[0002] Re-peelable adhesive sheets that can be easily removed after being applied to a substrate are used in various types of packaging (see, for example, Patent Document 1).

[0003] Conventional adhesive sheets have widely used plastic base materials for durability reasons, but in recent years, there has been a growing demand for paper-based base materials due to environmental concerns.

[0004] However, adhesive sheets using paper substrates have poor water resistance, and peeling them off after getting wet can cause damage to the substrate, resulting in insufficient durability for repeated application and removal in packaging and other applications. Furthermore, paper substrates have a high degree of water vapor permeability, making it impossible to prevent water vapor from penetrating after the adhesive sheet has been applied to the substrate. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-127236 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide an adhesive sheet that is highly re-peelable and has excellent water vapor barrier properties, and to provide a packaging material and a package equipped with the adhesive sheet. [Means for solving the problem]

[0007] These objectives are achieved by the present invention as described in (1) to (6) below. (1) An adhesive sheet used in packaging materials for storing items containing moisture, A base material composed of pulp-containing materials, A laminate layer is provided on one side of the substrate and is made of a material containing a thermoplastic resin, The laminate layer comprises an adhesive layer provided on the side of the laminate layer opposite to the side facing the substrate, An adhesive sheet characterized in that the wet tensile strength in the longitudinal direction of the test specimen of the substrate, as determined by testing in accordance with JIS P8135, is 2.0 kN / m or more.

[0008] (2) The adhesive sheet according to (1) above, wherein an anchor coat layer is provided between the substrate and the laminate layer.

[0009] (3) The adhesive sheet according to (1) or (2) above, wherein the laminate layer contains a biomass-derived thermoplastic resin.

[0010] (4) The adhesive sheet according to any one of (1) to (3) above, wherein the thickness of the laminate layer is 2 μm or more and 100 μm or less.

[0011] (5) A packaging material for storing items containing moisture, having an adhesive sheet in at least part of it, The adhesive sheet comprises a base material made of a pulp-containing material, and a laminate layer provided on one side of the base material and made of a thermoplastic resin-containing material. The laminate layer comprises an adhesive layer provided on the side of the laminate layer opposite to the side facing the substrate, A packaging material characterized in that the wet tensile strength in the longitudinal direction of the test specimen of the base material, as determined by testing in accordance with JIS P8135, is 2.0 kN / m or more.

[0012] (6) A packaging body characterized by having the packaging material described in (5) above and the contents stored in a space formed inside the packaging material. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an adhesive sheet excellent in re-peelability and excellent in water vapor barrier properties, and also to provide a packaging material and a package provided with the adhesive sheet.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic longitudinal sectional view showing a first embodiment of the adhesive sheet of the present invention. [Figure 2] It is a schematic longitudinal sectional view showing a second embodiment of the adhesive sheet of the present invention. [Figure 3] It is a perspective view showing a preferred embodiment of the package (packaging material) of the present invention. [Figure 4] It is a perspective view showing another preferred embodiment of the package (packaging material) of the present invention.

Modes for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail. [1] Adhesive sheet <First Embodiment> First, a first embodiment of the adhesive sheet of the present invention will be described. FIG. 1 is a schematic longitudinal sectional view showing a first embodiment of the adhesive sheet of the present invention.

[0016] The adhesive sheet 10 is used for a packaging material 100 that stores a stored item 50 containing moisture, and includes a base material 11 made of a material containing pulp, a laminate layer 12 made of a material containing a thermoplastic resin and provided on one surface side of the base material 11, and an adhesive layer 13 provided on the surface side opposite to the surface of the laminate layer 12 facing the base material 11. And the wet tensile strength in the longitudinal direction of the test piece of the base material 11 obtained by a test conforming to JIS P8135 is 2.0 kN / m or more.

[0017] With such a configuration, it is possible to provide an adhesive sheet 10 excellent in re-peelability and excellent in water vapor barrier properties.

[0018] More specifically, for example, when peeling off an adhesive sheet 10 that has become wet with moisture from the stored item 50, it is possible to prevent the base material 11 from being damaged or at least a portion of the laminate layer 12 from remaining on the adherend side, allowing for stable and repeated application and removal many times. In addition, it is possible to prevent moisture from the stored item 50 from permeating through the adhesive sheet 10 and evaporating after the adhesive sheet 10 has been applied, thereby improving the preservation of the stored item 50.

[0019] Furthermore, the adhesive sheet 10 also has excellent water resistance, so for example, it can prevent liquid contained in the stored items 50 that contain moisture from leaking out of the packaging 900.

[0020] Furthermore, since the base material 11 is composed of a pulp-containing material instead of conventionally widely used plastics, the use of petroleum-derived materials can be reduced, contributing to environmental protection.

[0021] The excellent effects of the present invention are obtained when the adhesive sheet 10 has the above-described configuration, and cannot be obtained when it does not have the above-described configuration.

[0022] For example, if a laminate layer is not included, the base material alone will not have sufficient water resistance. When peeling off the adhesive sheet that has become wet due to moisture from the stored items, the base material may be damaged, or moisture from the stored items may permeate the adhesive sheet and evaporate after it has been applied.

[0023] Furthermore, if the laminate layer does not contain thermoplastic resin, the water resistance of the laminate layer will be low. When peeling off the adhesive sheet, which has become wet with moisture from the stored items, residue of the laminate layer may remain on the substrate side, or the substrate may be damaged. In addition, after the adhesive sheet is applied, moisture from the stored items may permeate the adhesive sheet and evaporate.

[0024] Furthermore, regarding the base material, if the wet tensile strength in the longitudinal direction of the test specimen of the base material, as required by testing in accordance with JIS P8135, is not 2.0 kN / m or higher, when peeling off the adhesive sheet that has become wet due to moisture from the stored contents, the base material will break due to its low penetration strength. In addition, the water resistance of the base material will be insufficient, and moisture from the stored contents will permeate the adhesive sheet and evaporate.

[0025] Therefore, in this adhesive sheet 10, a thermoplastic resin is included in the laminate layer 12 provided between the base material 11 and the adhesive layer 13, and by having a wet tensile strength in the longitudinal direction of the test piece of the base material 11, as required by a test in accordance with JIS P8135, of 2.0 kN / m or more, excellent re-peelability and water vapor barrier properties can be achieved. In this specification, the term "sheet" includes the concept of "film."

[0026] [1-1] Base material The base material 11 contains at least pulp.

[0027] Furthermore, the wet tensile strength in the longitudinal direction of the test specimen of base material 11, as required by testing in accordance with JIS P8135, is 2.0 kN / m or more.

[0028] This prevents the base material 11 from being damaged when peeling off the adhesive sheet 10, which has become wet with moisture from the stored items 50, from the adherend.

[0029] As described above, the wet tensile strength in the longitudinal direction of the test specimen of base material 11, as required by the test in accordance with JIS P8135, should be 2.0 kN / m or more, but preferably 2.2 kN / m or more, more preferably 2.4 kN / m or more, and even more preferably 2.5 kN / m or more. This will allow the aforementioned effects to be exhibited more significantly.

[0030] [1-1-1] Pulp The base material 11 typically contains pulp as its main component. The pulp content in the base material 11 is not particularly limited, but is preferably 60.0% by mass or more and 99.0% by mass or less, more preferably 65.0% by mass or more and 98.0% by mass or less, and even more preferably 70.0% by mass or more and 97.0% by mass or less.

[0031] In this specification, "main component" means a component having a content exceeding 50.0% by mass.

[0032] The base material 11 is not particularly limited as long as it contains pulp, but the pulp is preferably natural pulp. Examples of natural pulp include wood pulp such as coniferous pulp and hardwood pulp, and bast fibers such as flax, hemp, paper mulberry, and mitsumata. In particular, the base material 11 preferably contains at least bleached coniferous kraft pulp and bleached hardwood kraft pulp. By including bleached coniferous kraft pulp, the pulp fibers (especially the fibers of the bleached coniferous kraft pulp) can be efficiently intertwined, thereby increasing the strength of the paper-based base material. Furthermore, by including bleached hardwood kraft pulp, the surface smoothness can be improved, which greatly contributes to improving printability.

[0033] In particular, when the ratio of bleached softwood kraft pulp and bleached hardwood kraft pulp in the base material 11 is such that the content of bleached softwood kraft pulp is XN [mass%] and the content of bleached hardwood kraft pulp is XL [mass%], it is preferable that the relationship 0.33 ≤ XN / XL ≤ 1.5 is satisfied, more preferably that the relationship 0.50 ≤ XN / XL ≤ 1.4 is satisfied, more preferably that the relationship 0.66 ≤ XN / XL ≤ 1.3 is satisfied, and even more preferably that the relationship 0.80 ≤ XN / XL ≤ 1.2 is satisfied.

[0034] The pulp constituting the base material 11 preferably contains bleached softwood kraft pulp and bleached hardwood kraft pulp, but may also contain other pulp components. However, the sum of the content of bleached softwood kraft pulp and bleached hardwood kraft pulp in relation to the total pulp content constituting the base material 11 is preferably 80.0% or more, more preferably 90.0% or more, and even more preferably 95.0% or more by mass.

[0035] [1-1-2] Wet paper strength enhancer The base material 11 preferably contains a wet strength enhancer in addition to the pulp described above. The wet strength enhancer has the function of improving the water resistance of the base material 11, particularly its paper strength when wet. By adding a wet strength enhancer to pulp fibers that are easily loosened by water, the bonds between the pulp fibers are maintained even when wet, making them less likely to loosen and increasing their strength.

[0036] Examples of wet-strength enhancers include polyamine resins, melamine-formaldehyde resins, and urea-formaldehyde resins. Among these, polyamine resins are preferred as the wet-strength enhancer.

[0037] Polyamine resins typically form crosslinked structures between pulp fibers. Furthermore, polyamine resins may form crosslinked structures with other polyamine resins, or with resin materials other than polyamine resins contained in the substrate 11.

[0038] Polyamine resins are compounds that have two or more amino or imino groups in their molecule. Examples of polyamine resins include resins obtained from so-called polyamines and epihalohydrins such as epichlorohydrin, and their derivatives. Such polyamine resins have epoxy groups as reactive groups. As an example of a polyamine resin, commercially available products such as WS-4011 (polyamine epichlorohydrin resin) from Seikoh PMC can be used. In addition, polyamide polyamine epihalo(chloro)hydrin resins can also be used as polyamine resins.

[0039] The content of the wet strength enhancer in the base material 11 is not particularly limited, but it is preferable that the content of the wet strength enhancer per 100 parts by mass of pulp is 0.5 parts by mass or more and 3.0 parts by mass or less, more preferably 0.7 parts by mass or more and 2.5 parts by mass or less, and even more preferably 1.0 part by mass or more and 2.0 parts by mass or less.

[0040] [1-1-3] Other ingredients The base material 11 may contain components other than pulp and wet strength enhancers. Hereinafter, such components will also be referred to as "other components" in this section. Examples of other components include sizing agents such as starch oxide, rosin-based sizing agents, and AKD (alkyl ketene dimer)-based sizing agents, resin materials other than wet strength enhancers (e.g., polyacrylamide (PAM) resin, urethane resin, acrylic resin, styrene acrylic resin, polyvinyl alcohol, etc.), colorants such as dyes and pigments, fixatives, papermaking aids, and flocculants. One or more of these may be used in combination. The resin material may be one that functions as a sizing agent.

[0041] As rosin-based sizing agents, for example, commercially available products such as the Sizepine N series and NT series from Arakawa Chemical Industries, Ltd., Harsize from Harima Chemicals, and the AL and CC series from Seikoh PMC, Ltd. can be used. The content of the rosin-based sizing agent in the base material 11 relative to 100 parts by mass of pulp can be, for example, 0.1 parts by mass or more and 3.5 parts by mass or less.

[0042] As AKD-based sizing agents, for example, those commercially available from Seikoh PMC as the AD series and from Arakawa Chemical Industries as the Sizing Pine K series can be used. The content of AKD-based sizing agent per 100 parts by mass of pulp in the base material 11 can be, for example, 0.1 parts by mass or more and 2.0 parts by mass or less.

[0043] As the urethane resin, for example, one commercially available from Daiichi Kogyo Seiyaku Co., Ltd. as Superflex 870 can be used. The content of urethane resin in the base material 11 relative to 100 parts by mass of pulp can be, for example, 0.1 parts by mass or more and 1.5 parts by mass or less.

[0044] However, the content of other components in the base material 11 is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 7.0% by mass or less.

[0045] [1-1-4] Other conditions The thickness of the substrate 11 is not particularly limited, but is preferably 30 μm or more and 190 μm or less, and more preferably 50 μm or more and 130 μm or less.

[0046] Furthermore, the substrate 11 may have a substantially uniform composition throughout, or it may have parts with different compositions, for example, it may be a laminate comprising multiple layers having parts with different compositions. More specifically, for example, the substrate may have a base and a print-receiving layer. In that case, it is preferable that the base satisfies the conditions of [1-1-1] to [1-1-3].

[0047] [1-1-4-1]Print receiving layer The presence of a print-receiving layer in the substrate 11 improves the printability of the adhesive sheet 10 when the adhesive sheet 10 has a print layer described later. The print-receiving layer is provided on the side of the substrate 11 opposite to the side facing the laminate layer 12 described later. The print-receiving layer may be composed of, for example, a binder resin, a filler, a water-resistant agent, etc., as needed.

[0048] By including a binder resin in the print-receiving layer, the adhesion of the print layer described later is improved, and the printability of the adhesive sheet 10 can be made excellent.

[0049] The binder resin constituting the print-receiving layer is not particularly limited as long as it exhibits a predetermined adhesion to the print layer, and may be either a water-soluble resin or a non-water-soluble resin. Examples of binder resins include styrene-butadiene copolymer (styrene-butadiene resin), acrylonitrile-butadiene copolymer, methacrylic acid-butadiene copolymer, polyurethane, acrylic acid ester copolymer, and other acrylic resins, as well as non-water-soluble resins such as polyvinyl acetate; and water-soluble resins such as polyvinyl alcohol and oxidized starch. From the viewpoint of water resistance, it is preferable that the binder resin be a non-water-soluble resin.

[0050] By including a filler in the print-receiving layer, the surface smoothness of the print-receiving layer can be improved, further enhancing the printability of the adhesive sheet 10.

[0051] Examples of fillers that make up the print-receiving layer include clay such as kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, zinc oxide, barium sulfate, and talc.

[0052] By including a water-resistant agent in the print-receiving layer, the water resistance of the entire adhesive sheet 10, particularly its water-resistant properties, can be improved through a synergistic effect with the aforementioned components.

[0053] Examples of water-resistant agents that make up the print-receiving layer include polyamine resins.

[0054] The polyamine resin can be any compound having two or more amino or imino groups in its molecule, but it is preferable that it is a compound that does not have an epoxy group in its molecule.

[0055] The print receiving layer may contain components other than binder resin, filler, and water-resistant agent, as needed. Examples of such components include isocyanate-based or epoxy-based crosslinking agents, oxidized starch, colorants such as dyes and pigments, fixatives, flocculants, defoamers, and dispersants.

[0056] As an antifoaming agent, for example, one that is commercially available from ADEKA as Pluronic® TR-701 (ethylenediamine polyoxyethylene-polyoxypropylene block polymer) can be used.

[0057] As a dispersant for the filler, for example, one that is commercially available from Toagosei Co., Ltd. as Aron T50 (acrylic acid-based dispersant) can be used.

[0058] However, the content of components other than binder resin, filler, and water-resistant agent in the print-receiving layer is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 7.0% by mass or less.

[0059] The thickness of the print receiving layer is not particularly limited, but is preferably 2 μm or more and 20 μm or less, and more preferably 4 μm or more and 15 μm or less.

[0060] The method for forming the print-receiving layer is not particularly limited. For example, the print-receiving layer can be formed by applying a coating solution containing the material for the print-receiving layer and optionally a solvent or dispersion medium to one side of the substrate 11 to form a coating film, and then drying the coating film.

[0061] [1-2] Laminate layer The laminate layer 12 contains at least a thermoplastic resin. This makes the laminate layer 12 highly water-resistant.

[0062] In particular, in the example shown in Figure 1, the adhesive sheet 10 is a laminate in which the base material 11, the laminate layer 12, and the adhesive layer 13 (described later) are stacked in this order.

[0063] This configuration prevents the base material 11 from being damaged when peeling off the adhesive sheet 10 that has become wet with moisture from the stored items 50, and also prevents moisture from the stored items 50 from permeating through the adhesive sheet 10 and evaporating after the adhesive sheet 10 has been applied.

[0064] [1-2-1]Thermoplastic resin The laminate layer 12 contains at least a thermoplastic resin. The thermoplastic resin used in the laminate layer 12 is not particularly limited, but examples include polyethylene, polypropylene, polystyrene, and ethylene vinyl acetate (EVA). Among these, the inclusion of polyethylene resin is preferable. Examples of polyethylene resins include branched low-density polyethylene resin (LDPE), linear low-density polyethylene resin (LLDPE), medium-density polyethylene resin (MDPE), very low-density polyethylene resin (VLDPE), and high-density polyethylene resin (HDPE). One or more of these can be selected and used in combination.

[0065] Furthermore, it is preferable that the laminate layer 12 contains a biomass-derived thermoplastic resin. By using a biomass-derived thermoplastic resin, the environmental burden can be reduced due to the carbon neutrality of the raw materials.

[0066] The biomass-derived thermoplastic resin is not particularly limited, but examples include polyethylene resins and polypropylene resins produced by polymerizing ethylene or propylene, which are produced from sugars derived from sugarcane or other raw materials, or from oils and fats derived from tall oil or other raw materials. Among these, it is preferable to include biomass polyethylene resin.

[0067] Commercial polyethylene resins may be used, such as Novatec® LL UF943, C6 SF941, HD HF313, HD HF111, HD HF560 from Nippon Polyethylene Co., Ltd., Sumikasen® CE3506 from Sumitomo Chemical Co., Ltd., Petrocene® 7300A from Tosoh Corporation, and Hyzex® 3300F, 3600F, 7000F, 7700F, 8000F, Neozex® 3510F, Ultzex® 3520L, 4020L, 4050, Evolu® SP4020, SP3530, SP4030, H SP4505, SP4005, SP3505 from Prime Polymer Co., Ltd. As biomass-derived polyethylene resins, Braskem's SBC818, SEB853, SPB681, etc., can be used. Furthermore, commercially available products to be mixed with these resins include, for example, low-density polyethylene resins such as Novatec® LL UF230 manufactured by Nippon Polyethylene Co., Ltd. However, the commercially available products that can be used in this invention are not limited to these.

[0068] The content of thermoplastic resin in the laminate layer 12 is preferably 90.0% by mass or more, more preferably 92.0% by mass or more, and even more preferably 93.0% by mass or more.

[0069] [1-2-2] Other ingredients The laminate layer 12 may contain components other than thermoplastic resin. Hereinafter, such components will also be referred to as "other components" in this section. Examples of other components include resins other than thermoplastic resin (hereinafter also referred to as "other resins" in this section), fillers (e.g., calcium carbonate, talc, clay, titanium dioxide, zinc oxide, barium sulfate, etc.), colorants such as dyes and pigments, fixatives, flocculants, dispersants, etc.

[0070] Other resins are not particularly limited and may be either water-soluble or non-water-soluble resins. Examples of resins include non-water-soluble resins such as polyester urethane resin, acrylic resin, urethane resin, acrylic urethane resin, styrene resin, styrene-butadiene resin, and polyester resin; and water-soluble resins such as polyvinyl alcohol. From the viewpoint of water resistance, non-water-soluble resins are preferred. Non-adhesive resins are also preferred.

[0071] Suitable non-water-soluble resins include, but are not limited to, styrene-butadiene (styrene-butadiene copolymer) resins and acrylic resins. These may be used individually or in combination of two or more.

[0072] Non-water-soluble resins may be commercially available products, such as Smartex® SN-309R (styrene-butadiene rubber latex, manufactured by A&L Japan, glass transition temperature 4°C), Smartex® SN-307R (styrene-butadiene rubber latex, manufactured by A&L Japan, glass transition temperature 10°C), JSR0693 (styrene-butadiene rubber latex, manufactured by JSR Corporation, glass transition temperature 20°C), and PRIMAL HA-16 (acrylic resin, manufactured by Dow Chemical Japan, glass transition temperature 35°C).

[0073] The content of other components in the laminate layer 12 is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 7.0% by mass or less.

[0074] [1-2-3] Other conditions The thickness of the laminate layer 12 is preferably 2 μm or more and 100 μm or less. In particular, as in this embodiment, when there is no anchor coat layer 14 as described later, the thickness of the laminate layer 12 is preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. This makes the water resistance of the laminate layer 12 even better, and prevents the base material 11 from being damaged when peeling off the adhesive sheet 10 that has been wet by the moisture in the stored items 50, and prevents the moisture in the stored items 50 from permeating through the adhesive sheet 10 and evaporating after the adhesive sheet 10 has been attached.

[0075] To further enhance the effects of the present invention and to simplify the manufacturing process, it is preferable that the laminate layer 12 be arranged over the entire surface of the adhesive sheet 10, but it may also be arranged over only a portion of it.

[0076] [1-3] Adhesive layer The adhesive layer 13 is the portion that comes into contact with and adheres to the substrate when the adhesive sheet 10 is attached to the substrate. The adhesive layer 13 is made of a material containing an adhesive and has adhesive properties.

[0077] [1-3-1] Adhesive As the adhesive constituting the adhesive layer 13, at least one can be selected from, for example, synthetic rubber-based adhesives such as styrene-isoprene-styrene block copolymer and styrene-butadiene-styrene block copolymer, acrylic acid ester copolymer, polyester resin-based adhesives, urethane resin-based adhesives, and ethylene-vinyl acetate copolymer.

[0078] The adhesive constituting the adhesive layer 13 is not particularly limited and may include, for example, solvent-based adhesives, emulsion-based adhesives, and hot-melt adhesives, but an emulsion-based adhesive is preferred. This allows for excellent adhesion of the label to the substrate and improved label productivity, while also reducing the amount of organic solvent used in the label manufacturing process, thereby reducing the environmental impact.

[0079] When the adhesive layer 13 is composed of a material containing an emulsion-type adhesive, it is particularly preferable that it is composed of a material containing an emulsion-type adhesive that has been crosslinked with a crosslinking agent. This allows the adhesive sheet 10 to have sufficiently high adhesion to the adherend, while also allowing the adhesive sheet 10 to be easily peeled off the adherend as needed.

[0080] [1-3-2] Other ingredients The adhesive layer 13 may contain components other than adhesives. Hereinafter, such components will also be referred to as "other components" in this section. Examples of other components include emulsifiers, tackifiers, and plasticizers.

[0081] Examples of tackifiers that can be used include rosin, rosinphenol resins and their ester compounds, hydrogenated rosin esters and other rosin-based resins, terpene resins, terpenephenol resins and aromatically modified terpene resins and other terpene-based resins, C5 petroleum resins, C9 petroleum resins and other tackifiers.

[0082] The content of other components in the adhesive layer 13 is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less.

[0083] [1-3-3] Other conditions The thickness of the adhesive layer 13 is not particularly limited as long as adhesiveness is achieved, but from the viewpoint of adhesiveness and thinness, it is usually, for example, between 10 μm and 100 μm.

[0084] [1-4] Other configurations The adhesive sheet 10 may have components other than the base material 11, anchor coat layer 14, laminate layer 12, and adhesive layer 13. For example, the adhesive sheet 10 may have a printed layer printed on the side of the base material 11 opposite to the side facing the laminate layer 12.

[0085] The content displayed on the printed layer is not particularly limited. For example, multiple adhesive sheets 10 may be mass-produced with the same content printed on them, or they may be individually printed with different content for individual identification, such as an ID number or serial number, or they may display catchphrases touting sales performance or efficacy, or they may display information about contests or new products. Furthermore, the information displayed on the printed layer is not limited to letters and numbers, but may also include illustrations, photographs, graphs, or combinations thereof.

[0086] The method of forming the printed layer is not particularly limited and can be formed by various printing methods such as flexographic printing, offset printing, letterpress printing, gravure printing, screen printing, inkjet printing, laser beam dry electrophotographic printing, and fused or sublimation thermal transfer printing. Flexographic printing, offset printing, letterpress printing, gravure printing, and screen printing are suitable for mass production of a fixed design or pattern. On the other hand, thermal transfer printing, inkjet printing, and electrophotographic (electrostatic) printing are suitable for printing variable information such as serial numbers.

[0087] The ink used to form the printed layer is not particularly limited and includes, for example, oil-based ink, water-based ink, and photocurable ink (ultraviolet-curable ink, electron beam-curable ink). In particular, when the printed layer is formed using photocurable ink (ultraviolet-curable ink, electron beam-curable ink), a suitable printed state can be maintained even when the adhesive sheet 10 gets wet with water.

[0088] Examples of UV-curable inks include those containing oligomers such as epoxy acrylate, urethane acrylate, and polyester acrylate, as well as UV polymerization initiators, colorants such as pigments, dispersants, additives, and monofunctional or polyfunctional monomers. When forming a printed layer with a UV-curable ink, the ink is used for printing, and then cured by irradiating it with UV light from a UV lamp. By using a photocurable ink, the manufacturing process can be made solvent-free, allowing for the production of printed layers more cheaply and efficiently while being environmentally conscious. In addition, the drying time required for the ink can be reduced, resulting in improved productivity of the adhesive sheet 10.

[0089] The printed layer may be provided on only a portion of the side of the substrate 11 opposite to the side facing the laminate layer 12, or it may be provided on the entire surface.

[0090] The printed layer may be formed before the adhesive sheet 10 is attached to the substrate, or it may be formed after the adhesive sheet 10 is attached to the substrate.

[0091] [1-5] Release Liner The surface of the adhesive layer 13 of the unused adhesive sheet 10 is preferably covered with a release liner (not shown).

[0092] This makes it easier to handle unused adhesive sheets 10 and effectively protects the adhesive layer 13 before it is attached to the substrate.

[0093] The release liner can be any paper, although not particularly limited; examples include high-quality paper, glassine paper, clay-coated paper, polyethylene laminated paper, etc.; polyester films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.; and plastic films such as polyolefin films such as polypropylene and polyethylene.

[0094] The thickness of the release liner is preferably 10 μm to 400 μm. Furthermore, a layer made of a release agent, such as silicone, may be provided on the surface of the release liner to improve the release properties of the adhesive layer 13. If such a layer is provided, its thickness is preferably 0.01 μm to 5 μm.

[0095] [1-6] Others Furthermore, each layer constituting the adhesive sheet 10 may have a substantially uniform composition throughout, or it may have parts with different compositions. For example, one of the layers constituting the adhesive sheet 10 may be a laminate comprising multiple layers having parts with different compositions from each other, or it may be composed of a gradient material whose composition changes in a gradual manner along the thickness direction.

[0096] <Second Embodiment> Next, a second embodiment of the adhesive sheet of the present invention will be described. Figure 2 is a schematic longitudinal cross-sectional view showing a second embodiment of the adhesive sheet of the present invention.

[0097] The following describes the second embodiment of the adhesive sheet, focusing on the differences from the previously described embodiment, and omitting explanations of similar matters.

[0098] In this embodiment, the adhesive sheet 10 has an anchor coat layer 14 provided between the base material 11 and the laminate layer 12.

[0099] This configuration provides better adhesion between the laminate layer 12 and the base material 11, and when peeling the adhesive sheet 10, which has been wet with moisture from the contents 50, from the substrate, it is possible to better prevent at least a portion of the laminate layer 12 from remaining on the substrate side.

[0100] Furthermore, the presence of the anchor coat layer 14 ensures high adhesion between the laminate layer 12 and the substrate 11 even after the adhesive sheet 10 has been wet. Therefore, even with a thinner laminate layer 12, the adhesive sheet 10 can maintain excellent water resistance and re-peelability. Thus, by providing the anchor coat layer 14, the amount of laminate layer 12, which is made of materials including thermoplastic resin derived from petroleum, can be reduced, contributing to the resolution of environmental problems.

[0101] [1-7] Anchor coat layer The anchor coat layer 14 has the function of providing excellent adhesion between the laminate layer 12 and the substrate 11, even after the adhesive sheet 10 has been wet with water.

[0102] [1-7-1] Resin The anchor coat layer 14 contains at least a resin. Examples of resins used in the anchor coat layer include modified polyethylene, modified polyolefins such as modified polypropylene, and modified acrylic.

[0103] Commercially available resins may be used for the anchor coat layer. Examples of modified polyethylene include Arrowbase SB-1200, SE-1200, SD-1200, etc., manufactured by Unitika Corporation. Examples of modified polypropylene include Arrowbase DA-1010, DC-1010, YA-6010, etc., manufactured by Unitika Corporation. Examples of modified acrylic include Polyment EK-350R, NK-100PM, NK-200PM, NK-350, NK-380, etc., manufactured by Nippon Shokubai Co., Ltd. However, the commercially available products that can be used in the present invention are not limited to these.

[0104] The resin content in the anchor coat layer 14 is preferably 90.0% or more, more preferably 92.0% or more, and even more preferably 93.0% or more.

[0105] [1-7-2] Other ingredients The anchor coat layer 14 may contain components other than resin. Hereinafter, such components will also be referred to as "other components" in this section. Examples of other components include fillers (e.g., titanium dioxide, zinc oxide, barium sulfate, etc.), colorants such as dyes and pigments, fixatives, flocculants, dispersants, etc.

[0106] The content of other components in the laminate layer 12 is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, and even more preferably 7.0% by mass or less.

[0107] [1-7-3] Other conditions In particular, in the example shown in Figure 2, the adhesive sheet 10 is a laminate in which a base material 11, an anchor coat layer 14, a laminate layer 12, and an adhesive layer 13 are stacked in this order. In the illustrated configuration, the interface between the base material 11 and the anchor coat layer 14 is shown as a plane, but normally, a part of the anchor coat layer 14 penetrates the base material 11.

[0108] The amount of anchor coat layer 14 applied is not particularly limited, but is 0.5 g / m². 2 Preferably, it is 1.0 g / m 2 The above is more preferable. This makes it possible to improve the adhesion between the laminate layer 12 and the substrate 11 even after the adhesive sheet 10 has been wet with water.

[0109] Furthermore, the amount of anchor coat layer 14 applied is not particularly limited, but is 3.0 g / m². 2 Preferably, it is 2.0 g / m 2 The following is more preferable. This makes it possible to reduce the thickness of the adhesive sheet 10, thereby reducing the amount of raw materials used, and also makes storage and handling after manufacturing easier.

[0110] Furthermore, when the anchor coat layer 14 is provided, the combined thickness of the laminate layer 12 and the anchor coat layer 14 can be made thinner than the thickness of the laminate layer 12 when the laminate layer 12 alone is used to achieve the same level of water resistance and re-peelability. Therefore, when the anchor coat layer 14 is provided, the amount of petroleum-derived materials used in the manufacture of the adhesive sheet 10 can be reduced, contributing to the resolution of environmental problems, and the thinner adhesive sheet 10 can be made easier to handle.

[0111] As mentioned above, the thickness of the laminate layer 12 is preferably 2 μm or more and 100 μm or less. In particular, when an anchor coat layer 14 is present, as in this embodiment, the thickness of the laminate layer 12 is preferably less than 50 μm, more preferably 30 μm or less, and even more preferably 20 μm or less. This reduces the amount of laminate layer 12 made of materials containing thermoplastic resin, suppresses the use of petroleum-derived materials, and contributes to solving environmental problems.

[0112] Furthermore, the thickness of the laminate layer 12 is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. This allows the laminate layer 12 to impart superior re-peelability and water vapor barrier properties to the adhesive sheet 10.

[0113] [2] Packaging (packaging material) Next, we will describe a package (packaging material) to which the adhesive sheet of the present invention is applied. Figure 3 is a perspective view showing a preferred embodiment of the packaging material of the present invention.

[0114] The packaging material 100 for storing the contents 50 containing moisture has an adhesive sheet 10 in at least part of it. The adhesive sheet 10 comprises a base material 11 made of a pulp-containing material, a laminate layer 12 made of a polyethylene resin-containing material provided on one side of the base material 11, and an adhesive layer 13 provided on the side of the laminate layer 12 opposite to the side facing the base material 11. The adhesive sheet 10 is characterized in that the wet tensile strength in the longitudinal direction of a test piece of the base material, as determined by a test in accordance with JIS P8135, is 2.0 kN / m or more.

[0115] The packaging body 900 is characterized by having a packaging material 100 and a stored item 50 housed in a space formed inside the packaging material 100.

[0116] With this configuration, even if the adhesive sheet 10 gets wet due to the moisture in the contents 50, it has the stability to allow for repeated attachment and removal, and it prevents the moisture in the contents 50 from permeating through the adhesive sheet 10 and evaporating, thereby providing a packaging material 100 and a package 900 with excellent preservation properties for the contents 50.

[0117] [2-1] Composition of the packaging The packaging 900 shown in Figure 3 is characterized by having a packaging material 100 and a stored item 50 housed in a space formed inside the packaging material 100.

[0118] The stored items 50 are not particularly limited, but in this embodiment, they are liquid-impregnated sheets (wet sheets), and multiple sheets (for example, 6 to 100 sheets) of such sheets are stored in a desired folded state. Specific examples of liquid-impregnated sheets include wet wipes, makeup remover sheets, face masks, oil-blotting papers, medicated papers, antibacterial sheets, baby wipes, car cleaning sheets, window cleaning sheets, toilet cleaning sheets, etc.

[0119] [2-2] Composition of packaging materials The packaging material 100 shown in Figure 3 consists of a packaging material body 30 having a space inside for storing the contents 50, and a lid body 40 that closes the opening 20 for removing the contents 50 from the packaging material body 30. The packaging material body 30 is the object to which the lid body 40 is attached.

[0120] The lid 40 is made of the adhesive sheet 10 described above. Preferably, the adhesive sheet 10 that makes up the lid 40 satisfies the conditions of [1] described above.

[0121] [2-2-1] Packaging material body The packaging material body 30 has a space inside for storing contents 50, i.e., multiple sheets, and is formed into a bag shape by appropriately molding and joining sheet material 31 (film) of a desired shape. For example, the openings at both ends of a tubular sheet material 31 are sealed by fusion (heat fusion, high-frequency fusion, ultrasonic fusion, etc.) or adhesive to form a sealed part and create a bag shape.

[0122] The sheet material 31 is preferably flexible, and its constituent materials include, for example, polyethylene, polypropylene, modified polyolefins such as modified polyethylene and modified polypropylene, polyolefins such as ethylene-vinyl acetate copolymer (EVA); polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate; and various resin materials such as acetate resin, acrylonitrile-butadiene-styrene copolymer (ABS), polystyrene, polyvinyl chloride, polyamide, polyesteramide, polyether, polyimide, polyamideimide, poly-p-phenylene sulfide, and polyether ester. One or more of these can be selected and used in combination.

[0123] Furthermore, the sheet material 31 may be a single layer or a laminate of multiple layers. When the sheet material 31 is composed of a laminate, an example is a laminate of two or more different resins from the resin materials exemplified above.

[0124] Furthermore, as the sheet material 31, an adhesive sheet 10 without the formation of an adhesive layer 13 can also be used. Since the base material 11 of the adhesive sheet 10 contains pulp, using it in the sheet material 31 can reduce the use of petroleum-derived materials and contribute to environmental protection.

[0125] Furthermore, the sheet material 31 may be subjected to various surface treatments, such as surface treatments to improve adhesion with the adhesive layer 13. For example, at least the portion of the sheet material 31 to which the adhesive layer 13 is attached may be subjected to a surface treatment to improve adhesion and airtightness with the adhesive layer 13.

[0126] Furthermore, the surface of the sheet material 31 may be provided with various functional layers, such as a printing layer (printing coating layer) for printing characters or figures, a protective layer, or a layer for improving surface properties (gloss, etc.). Such functional layers may be provided on the side of the lid 40 opposite to the side facing the packaging material body 30.

[0127] The thickness of the sheet material 31 is not particularly limited, but is preferably 15 μm or more and 500 μm or less, and more preferably 20 μm or more and 100 μm or less.

[0128] The packaging body 30 has an opening 20 formed for removing the contents 50, which is a sheet, when in use. Figure 3 shows the state after the lid 40 has been opened and the opening 20 has been formed. The top of the packaging body 30 has a linearly arranged easy-break section 21, which consists of, for example, a half-cut, a notch (V-shaped groove), or a perforation. This easy-break section 21 has a lower breaking strength than other parts of the sheet material 31 (near the easy-break section 21), and when an external force is applied, the sheet material 31 breaks at this easy-break section 21 and is opened. In Figure 3, the easy-break section 21 after opening is formed in a shape corresponding to the contour of the opening 20 (for example, circular, elliptical, oval, or square), and after the easy-break section 21 is broken, the part of the sheet material 31 surrounded by the easy-break section 21 (the part inside the easy-break section 21) becomes a broken fragment 22.

[0129] [2-2-2] Lid The lid 40 is for sealing the opening 20 formed in the packaging material body 30, and is made of an adhesive sheet 10.

[0130] As shown in Figure 3, the lid 40 has a base end 41 and a tab 42 at the opposite end (tip). When the tab 42 is pinched with the fingers and the lid 40 is lifted upward from the tip side, the inner part of the easily breakable portion 21, i.e., the portion that will become the broken fragment 22, remains attached to the surface of the lid 40 facing the packaging material body 30 and is lifted together with the lid 40, causing the easily breakable portion 21 to gradually break and the opening 20 to be formed (opened).

[0131] During this operation, as shown in Figure 3, the base end 41 of the lid 40 may remain attached to the packaging body 30 without detaching. This ensures that when the contents 50 are removed from the opening 20, the lid 40 remains connected to the packaging body 30 at its base end 41. Alternatively, the base end 41 of the lid 40 may be completely detached from the packaging body 30.

[0132] Once the packaging 100 is opened as described above, the top sheet of the contents 50 can be pinched with your fingers and removed through the opening 20. While sheets are usually removed one at a time, multiple sheets may be removed simultaneously.

[0133] After removing the sheet, the lid 40 is returned to its original state. That is, the lid 40 is reattached to the outer circumference of the opening 20 formed in the packaging body 30. This seals the opening 20. At this time, it is preferable that the broken fragments 22 return to the opening 20 and seal it, and that the lid 40 is tightly attached to the outer circumference of the opening 20 without any gaps. This ensures that the packaging 100 is airtight, preventing dust, dirt, bacteria, etc. from entering the packaging 100 from the outside during storage and contaminating the contents 50. Furthermore, since the adhesive sheet 10 that constitutes the lid 40 has excellent water vapor barrier properties, it is possible to prevent moisture from the contents 50 from permeating through the adhesive sheet 10 and volatilizing outside the packaging 100 during subsequent storage, thereby improving the preservation of the contents 50.

[0134] When sealing the opening 20, it is preferable that the broken fragments 22 return to the opening 20 and the lid 40 adheres tightly to the outer circumference of the opening 20 without any gaps. However, when returning the lid 40 to its original position, the positions of the broken fragments 22 and the opening 20 may become misaligned. In that case, the portion of the lid 40 facing the packaging material body 30 to which the broken fragments 22 are not attached overlaps with the opening 20, causing the lid 40 to come into contact with the contents 50 and become wet with moisture from the contents 50. However, since the adhesive sheet 10 that makes up the lid 40 has excellent water vapor barrier properties, it is possible to effectively prevent moisture from the contents 50 from permeating through the lid 40 and volatilizing outside the packaging material 100, thus preventing the contents 50 from drying out.

[0135] When removing a sheet from the state where the opening 20 is sealed by the lid 40, pinch the tab 42 with your fingers and lift the lid 40 upward from the front end, and the lid 40 will peel off from the main body of the packaging material 30. Since the easily breakable portion 21 has already broken, the broken fragment 22 will remain attached to the lid 40 and will be lifted together with the lid 40, gradually exposing the opening 20 from the front end. In this way, the packaging material 100 will open again. This will allow you to remove the top sheet once more.

[0136] The adhesive sheet 10 that makes up the lid 40 has excellent re-peelability even after getting wet. Therefore, when sealing the opening 20, even if the position of the broken fragments 22 and the opening 20 are misaligned and the lid 40 gets wet with moisture from the contents 50, it is possible to prevent the base material 11 from being damaged or at least a part of the laminate layer 12 from remaining on the packaging body 30 when peeling it off.

[0137] After removing the sheet, the lid 40 is reattached to the outer periphery of the opening 20. This reseals the opening 20. In this way, the sheet is removed multiple times, and each time a sheet is removed, the lid 40 is peeled off and reattached to the packaging body 30. In other words, in the packaging 900, the lid 40 is repeatedly peeled off and reattached to the packaging body 30. This number of times may correspond to the number of sheets stored in the unused packaging 100.

[0138] Even if the lid 40 becomes wet due to moisture from the stored items 50 after repeated attachment and removal, the adhesive sheet 10 that makes up the lid 40 has excellent re-peelability after getting wet, so it can be reliably attached and removed many times.

[0139] The adhesive layer 13 constituting the lid 40 may be arranged over the entire surface of the lid 40, or it may be arranged over only a portion of the surface of the lid 40.

[0140] For example, by placing a highly adhesive adhesive composition that does not require re-peeling at the base end 41 of the lid 40, and a re-peelable adhesive layer 13 on the parts other than the base end 41, it is possible to prevent the lid 40 from detaching from the packaging body 30 when removing the sheet, and to make opening and closing the lid 40 easier.

[0141] [2-3] Other configuration examples Figure 4 is a perspective view showing another preferred embodiment of the packaging material of the present invention. The packaging material and packaging according to other preferred embodiments of the present invention will be described below, but the same matters as described above will be omitted, and the focus will be on the differences.

[0142] The packaging material 100 shown in Figure 4 consists of a packaging material body 30 and a lid 40, and an opening 20 is pre-formed on the top of the packaging material body 30 in an unused state.

[0143] In the packaging 900 of this embodiment, there is no need to break the easily breakable portion 21 to form the opening 20 when opening the package for the first time from an unused state. Therefore, there is an advantage that the first opening can be done with less force, similar to the second opening and subsequent openings.

[0144] In this embodiment, since there is no component corresponding to the broken fragment 22 in Figure 3, when the opening 20 shown in Figure 4 is sealed with the lid 40, the lid 40 comes into contact with the stored item 50 and becomes wet with the moisture from the stored item 50. However, since the adhesive sheet 10 that makes up the lid 40 has excellent re-peelability and water vapor barrier properties even after getting wet, in this embodiment as well, adhesion and peeling can be stably repeated many times, preventing the moisture from the stored item 50 from permeating through the lid 40 and volatilizing outside the packaging material 100, and allowing the stored item 50 to be stored stably.

[0145] In the configuration shown in Figure 4, the adhesive layer 13 constituting the lid 40 is arranged over the entire surface of the adhesive sheet 10. However, the adhesive layer 13 constituting the lid 40 may be arranged over only a portion of the surface of the adhesive sheet 10. For example, by selectively forming the adhesive layer 13 on the surface of the lid 40 facing the packaging body 30, excluding the portion that overlaps with the opening 20 during sealing, the contact area between the contents 50 and the adhesive layer 13 can be reduced, effectively preventing a portion of the adhesive layer 13 from adhering to the contents 50.

[0146] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto. For example, any combination of the configurations in each embodiment is also included in the present invention.

[0147] Furthermore, the adhesive sheet of the present invention may be manufactured by any method, and is not limited to those manufactured by the methods described in the embodiments above.

[0148] The adhesive sheet may have components other than the base material, anchor coat layer, laminate layer, and adhesive layer. For example, the adhesive sheet may have at least one intermediate layer provided between the laminate layer and the adhesive layer.

[0149] Furthermore, the adhesive sheet may have at least one coating layer on the side opposite to the side facing the laminate layer of the substrate.

[0150] The laminate layer or anchor coat layer may be positioned on a portion of the surface direction of the adhesive sheet, but it is preferable that it be positioned over the entire surface direction of the adhesive sheet. This further enhances the effects of re-peelability and water vapor barrier properties, and also simplifies the manufacturing process.

[0151] The packaging material shown in Figure 3 was composed entirely of a flexible sheet material, but the present invention is not limited to this. For example, the packaging material may be composed of a box-shaped structure (housing) with an opening (whether open or unopened) formed in a part thereof (for example, the top).

[0152] The lid is not limited to the shape shown in Figure 3; for example, it may be circular, elliptical, or oval-shaped, and may have slits. [Examples]

[0153] The present invention will be described in detail below based on specific examples, but the present invention is not limited thereto. In the following examples, unless the temperature conditions are specified, the treatments and measurements were performed at room temperature (23°C, 50% RH).

[0154] [3] Manufacturing of adhesive sheets and packaging materials (Example 1) (1) Manufacturing of base material 50 parts by mass of bleached softwood kraft pulp and 50 parts by mass of bleached hardwood kraft pulp were beaten in water using the Schoper-Rigler method to achieve a beat degree of 25°SR, and this was dispersed in water to obtain a pulp slurry with a concentration of approximately 2.7% by mass.

[0155] Next, to obtain the composition, the following were added to 100 parts by mass of pulp in the pulp slurry in the above proportions: 1.3 parts by mass of polyamine resin (Seiko PMC Co., Ltd., wet paper strength enhancer, WS-4011), which had been pre-activated with sodium hydroxide; 3.96 parts by mass of PAM (Arakawa Chemical Industries, Ltd., internal paper strength enhancer, Polystron 191); 0.6 parts by mass of sizing agent (Arakawa Chemical Industries, Ltd., Sizing Pine CA-956); and 0.3 parts by mass of aluminum sulfate (aluminum sulfate). Then, this composition was used to make paper using a long-wire multi-cylinder paper machine to obtain paper material.

[0156] Furthermore, a base was obtained by applying a composition containing 2.6 parts by mass of oxidized starch (Oji Corn Starch Co., Ltd., Oji Ace A), 0.18 parts by mass of styrene acrylic resin (Seiko PMC Co., Ltd., emulsion-type surface sizing agent, SE2325), 0.1850 parts by mass of acrylic resin (Arakawa Chemical Industries, Ltd., surface paper quality improver, Polymerset 305A), and water, in the above proportions, to both sides of the paper material using a sizing press (S / P) and drying it.

[0157] Next, on one side of the base, the following was applied by air knife coating (A / K): 8.68 parts by mass of flattened kaolin (manufactured by Imerys, Astracoat), 0.04 parts by mass of polyoxyethylene-polyoxypropylene block polymer (manufactured by ADEKA, nonionic surfactant, Pluronic® TR-701), 0.02 parts by mass of acrylic acid dispersant (manufactured by Toagosei Co., Ltd., Aron T50), and calcium carbonate (manufactured by Okutama Kogyo Co., Ltd., Tamapearl TP123) A substrate was obtained by applying a composition containing the following in proportions: 2.17 parts by mass of : 2.17 parts by mass, styrene-butadiene resin (manufactured by Nippon A&L Co., Ltd., Smartex SN-309R): 1.63 parts by mass, oxidized starch (manufactured by Oji Corn Starch Co., Ltd., Oji Ace A): 0.43 parts by mass, polyamine resin (manufactured by Sumitomo Chemical Co., Ltd., Sumirez Resin SPI-102A): 0.02 parts by mass, and pure water, and then applying a supercalender to form a print-receiving layer.

[0158] The thickness of the formed print-receiving layer is 10 μm, and the thickness of the substrate including the print-receiving layer is 80 g / m².2 Furthermore, the wet tensile strength in the longitudinal direction of the test specimen of the substrate, as required by testing in accordance with JIS P8135, was 2.5 kN / m.

[0159] (2) Formation of anchor coat layer and laminate layer Next, Arrowbase SE-1200, manufactured by Unitika Corporation, was diluted with water as a modified polyethylene resin to obtain an anchor coat composition (solid content 1% by mass). The above anchor coat composition was applied to the side of the substrate opposite to the print receiving layer using an offset gravure coater, and the thickness of the anchor coat layer after drying was 1 g / m². 2 The coating was applied in this manner and dried at 90°C for 1 minute to obtain an anchor coat layer (1 g / m²). 2 ).

[0160] Next, biomass-derived polyethylene resin (SBC818, manufactured by Braskem) was heated to 310°C and extruded using a T-die onto the surface opposite to the substrate of the anchor coat layer. Cooling water adjusted to a temperature of 23°C was passed through a water-cooled roll, and the surface of the water-cooled roll was brought into contact with the polyethylene resin on the substrate, thereby cooling and solidifying the molten polyethylene resin to obtain a laminate layer (20 g / m²). 2 ). The thickness of the formed laminate layer was 20 μm.

[0161] (3) Formation of the adhesive layer An emulsion-type adhesive composition (repositionable adhesive composition) with a solid content of 55% by mass was prepared, comprising an acrylic copolymer (monomer mass ratio, 2-ethylhexyl acrylate:methacrylic acid = 100:2) as an acrylic adhesive, an oxazoline-based crosslinking agent, a carbodiimide-based crosslinking agent, and a tackifying resin as crosslinking agents.

[0162] Next, the above-mentioned adhesive composition (repositionable adhesive composition) was applied to the release-treated surface of the release liner (glassine paper treated with silicone) using a roll coater so that the thickness of the adhesive layer after drying would be 25 μm. The mixture was then dried at 90°C for 2 minutes to form an adhesive layer on the release liner.

[0163] Subsequently, the adhesive layer formed on the release liner as described above was bonded to the surface of the laminate layer, and the sheet was left to stand for one week at 23°C and 50% RH (relative humidity) to obtain an adhesive sheet in which the adhesive layer was protected by the release liner. The thickness of the formed adhesive layer was 25 μm.

[0164] (Example 2) An adhesive sheet was manufactured in the same manner as in Example 1, except that the anchor coat layer was not formed and the thickness of the laminate layer was set to 50 μm.

[0165] (Comparative Example 1) In the manufacturing of the base material, an adhesive sheet was manufactured in the same manner as in Example 1, except that polyamine resin was not added, the thickness of the laminate layer was set to 50 μm, and the anchor coat layer was not formed.

[0166] (Comparative Example 2) An adhesive sheet was manufactured in the same manner as in Example 1, except that a laminate layer and an anchor coat layer were not formed.

[0167] (Comparative Example 3) An adhesive sheet was manufactured in the same manner as in Example 1, except that polyamine resin was not added during the manufacturing of the base material, and the laminate layer and anchor coat layer were not formed.

[0168] (Comparative Example 4) An adhesive sheet was manufactured in the same manner as in Example 1, except that styrene-butadiene resin was used instead of polyethylene resin in the formation of the laminate layer, the thickness of the laminate layer was set to 50 μm, and the anchor coat layer was not formed.

[0169] [4] Rating The adhesive sheets of each of the above-mentioned embodiments and comparative examples were evaluated as follows.

[0170] [4-1] Re-peelability after standing in a high-humidity environment The adhesive sheets (adhesive sheets protected by a release liner) of each of the above examples and comparative examples were cut to a size of 25 mm in width and 150 mm in length to be used as test specimens.

[0171] The release liner was peeled off the obtained test specimen, and the exposed adhesive layer was attached to a polyester plate (PET plate) and pressed down by passing a 2kg roller back and forth once.

[0172] Next, the samples were left to stand for one day at 23°C and 50% RH (relative humidity), then left to stand for seven days at 40°C and 80% RH (relative humidity), and finally returned to 23°C and 50% RH (relative humidity) for one day.

[0173] Subsequently, the adhesive sheet was peeled off by hand at a peeling speed of 30 m / min and a peeling angle of 180°. The areas where the adhesive sheet had been peeled off the container were observed and evaluated based on the following criteria.

[0174] A: No substrate damage occurred. B: Slight damage to the substrate occurred. C: Significant substrate failure occurred.

[0175] [4-2] Wet Contents Test After preparing the adhesive sheets for each of the above examples and comparative examples, test pieces of the adhesive sheets, cut to 25 mm x 150 mm, were attached to a PET plate, which was the substrate, under conditions of 23°C and 50% RH (relative humidity).

[0176] Next, after being left to stand for one day in an environment of 23°C and 50% RH (relative humidity), the entire PET plate with the adhesive sheet test piece attached was wrapped in a wet wipe, and then the whole thing was wrapped in food wrap film. After being left to stand for three days in a 40°C dry environment, it was returned to an environment of 23°C and 50% RH (relative humidity) and left to stand for one day.

[0177] Afterward, the food wrap and wet wipes were removed, and the adhesive sheet was peeled off the PET plate by hand at a speed of 0.3 m / min. The areas where the adhesive sheet had been removed from the PET plate were observed, and the re-peelability after getting wet was evaluated based on the following criteria.

[0178] A: No substrate damage occurred. B: Slight damage to the substrate occurred. C: Substrate failure occurred. D: Significant substrate failure occurred.

[0179] [4-3] Weight change rate The water vapor barrier properties were evaluated by placing the packaging bodies equipped with the adhesive sheets of each of the above examples and comparative examples in a high-temperature environment and comparing the weight of the contents inside the packaging before and after placement.

[0180] After preparing the adhesive sheets for each of the above examples and comparative examples, test pieces of the adhesive sheets, cut to 25 mm x 150 mm, were attached to the opening of the packaging body of the embodiment shown in Figure 4, which contained wet wipes as its contents, under conditions of 23°C and 50% RH (relative humidity).

[0181] Next, the samples were left to stand for one day at 23°C and 50% RH (relative humidity), then left to stand for seven days at 70°C in a dry environment, and finally returned to 23°C and 50% RH (relative humidity) for one day.

[0182] Subsequently, the weight of the wet wipes removed from the packaging was measured, and the percentage change in the weight of the wet wipes before and after being left in the high-temperature environment was determined.

[0183] More specifically, the weight change rate was calculated using the following formula. Weight change rate (%) = (W0 - W) × 100 / W0 W0: Weight of the wet wipes before being left to stand in the high-temperature environment described above. W: Weight of the wet wipes after being left to stand in the high-temperature environment described above. Evaluation was performed based on the following criteria from the calculated weight change rate. The smaller the value of the weight change rate, the better the water vapor barrier property.

[0184] A: The weight change rate is less than 2.0% B: The weight change rate is 2.0% or more and less than 5.0% C: The weight change rate is 5.0% or more and less than 7.5% D: The weight change rate is 7.5% or more and less than 10.0% E: The weight change rate is 10.0% or more

[0185] [4-4] Water vapor permeability The water vapor permeability of each of the above-mentioned examples and comparative examples of the adhesive sheet was measured to evaluate the water vapor barrier property.

[0186] ] For each of the above-mentioned examples and comparative examples of the adhesive sheet, the water vapor permeability was determined under the conditions of 40 °C and 90% RH (relative humidity) by a test in accordance with JIS Z 0208, and evaluation was performed according to the following criteria. The lower the numerical value of the water vapor permeability, the better the water vapor barrier property.

[0187] A: The water vapor permeability is less than 20 g / m 2 ·day B: The water vapor permeability is 20 g / m 2 ·day or more and less than 100 g / m 2 ·day C: The water vapor permeability is 100 g / m 2 ·day or more and less than 300 g / m 2 ·day D: The water vapor permeability is 300 g / m 2 ·day or more and less than 1000 g / m 2 ·day E: The water vapor permeability is 1000 g / m 2 ·day or more

[0188] These results are summarized in Table 1 together with the compositions of the adhesive sheets of the above-mentioned examples and comparative examples.

[0189]

Table 1

[0190] As is clear from Table 1, the adhesive sheets of each of the above embodiments exhibited excellent re-peelability and superior water vapor barrier properties. In contrast, the adhesive sheets of each comparative example did not yield satisfactory results.

[0191] Furthermore, in the manufacturing of the base material, the adhesive sheets were manufactured in the same manner as in the above-described examples and comparative examples, except that the wet tensile strength in the longitudinal direction of the base material test specimen, as required by a test in accordance with JIS P8135, was varied within the range of 2.0 kN / m to 4.0 kN / m. When these adhesive sheets were evaluated in the same manner as described above, the same results were obtained.

[0192] Furthermore, adhesive sheets were manufactured in the same manner as in the above examples and comparative examples, except that polypropylene resin was used instead of polyethylene resin in the formation of the laminate layer. When these adhesive sheets were evaluated in the same manner as described above, the same results were obtained. [Explanation of Symbols]

[0193] 10…Adhesive sheet 11...Base material 12…Laminating layer 13…Adhesive layer 14…Anchor coat layer 20…Aperture 21…Easily breakable parts 22... Fragments 30…Packaging material body 31…Sheet material 40... Lid 41...Proximal end 42... Tabs 50...Storage items 100...Packaging material 900...packaging

Claims

1. An adhesive sheet used as packaging material for storing items containing moisture, A base material composed of pulp-containing materials, A laminate layer is provided on one side of the substrate and is made of a material containing a thermoplastic resin, The laminate layer comprises an adhesive layer provided on the side of the laminate layer opposite to the side facing the substrate, An adhesive sheet characterized in that the wet tensile strength in the longitudinal direction of the test specimen of the substrate, as determined by testing in accordance with JIS P8135, is 2.0 kN / m or more.

2. The adhesive sheet according to claim 1, wherein an anchor coat layer is provided between the substrate and the laminate layer.

3. The adhesive sheet according to claim 1 or 2, wherein the laminate layer contains a thermoplastic resin derived from biomass.

4. The adhesive sheet according to claim 1 or 2, wherein the thickness of the laminate layer is 2 μm or more and 100 μm or less.

5. A packaging material for storing items containing moisture, having an adhesive sheet in at least part of it, The adhesive sheet comprises a base material made of a pulp-containing material, a laminate layer provided on one side of the base material and made of a thermoplastic resin-containing material, and an adhesive layer provided on the side of the laminate layer opposite to the side facing the base material. A packaging material characterized in that the wet tensile strength in the longitudinal direction of the test specimen of the base material, as determined by testing in accordance with JIS P8135, is 2.0 kN / m or more.

6. A packaging body characterized by comprising the packaging material described in claim 5 and the contents stored in a space formed inside the packaging material.

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