Adhesive sheets and labels

Abstract

To provide an adhesive sheet and label that are highly water-resistant and highly repositionable. [Solution] The adhesive sheet of the present invention is an adhesive sheet used for display labels, 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 an adhesive sheet and a display label.

Background Art

[0002] After being adhered to an adherend, a re-peelable adhesive sheet that can be easily peeled off is used for various labels and the like (see, for example, Patent Document 1).

[0003] Conventional adhesive sheets have widely used those having a plastic base material from the viewpoint of durability. In recent years, however, consideration for the environment has demanded the use of a paper base material.

[0004] However, an adhesive sheet using a paper base material has a problem that pulp fibers absorb water and bend in a direction like a bow when placed in a high-temperature and high-humidity environment. For example, Patent Document 2 discloses a printing label that can maintain the label shape when affixed even in a high-temperature and high-humidity environment by providing a resin layer between a paper-based base material and an adhesive layer.

[0005] However, in Patent Document 2, the peelability from the adherend has not been studied, and there are problems that when the adhesive sheet is peeled off from the adherend at high speed in a high-humidity environment, substrate breakage occurs, and when a water-wetted adhesive sheet is peeled off from the adherend, interfacial failure or cohesive failure of the resin occurs between the substrate and the resin layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The object of the present invention is to provide an adhesive sheet and a label that have excellent water resistance and excellent re-peelability. [Means for solving the problem]

[0008] These objectives are achieved by the present invention as described in (1) to (4) below. (1) An adhesive sheet used for display labels, 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.

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

[0010] (3) The adhesive sheet according to (1) or (2) above, wherein the thickness of the laminate layer is 15 μm or more.

[0011] (4) A base material made of a material containing pulp, 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, A label 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. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an adhesive sheet and a label that have excellent water resistance and excellent re-peelability.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic longitudinal sectional view showing a preferred embodiment of the adhesive sheet of the present invention. [Figure 2] It is a schematic longitudinal sectional view showing a preferred embodiment of the display label of the present invention. [Figure 3] It is a perspective view showing an embodiment in which the display label of the present invention is attached to an article.

Modes for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0015] [1] Adhesive sheet FIG. 1 is a schematic longitudinal sectional view showing a preferred embodiment of the adhesive sheet of the present invention.

[0016] The adhesive sheet 10 is used for a display label, 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 the adhesive sheet 10 having excellent water resistance and excellent re-peelability.

[0018] More specifically, for example, when the adhesive sheet 10 is peeled from an adherend at high speed in a high humidity environment, the breakage of the base material 11 can be prevented. Further, when the adhesive sheet 10 wetted with water is peeled from an adherend, the breakage of the base material of the base material 11 and the cohesive failure of the laminate layer 12 can be prevented.

[0019] 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.

[0020] 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.

[0021] For example, even if the wet tensile strength in the longitudinal direction of a test specimen of the substrate, as required by a test in accordance with JIS P8135, is 2.0 kN / m or more, if a laminate layer is not included, the substrate alone will lack sufficient strength, and substrate failure will occur when the adhesive sheet is peeled off from the adherend at high speed in a high-humidity environment.

[0022] Furthermore, regarding the substrate, even if the wet tensile strength in the longitudinal direction of the test specimen of the substrate, as required by testing in accordance with JIS P8135, is 2.0 kN / m or more, and even if it has a laminate layer, if the laminate layer does not contain thermoplastic resin, when peeling a wet adhesive sheet from the adherend, cohesive failure of the resin constituting the laminate layer may occur, or substrate failure may occur when peeling the adhesive sheet from the adherend at high speed in a high-humidity environment.

[0023] Furthermore, even if the adhesive sheet has a laminate layer and the laminate layer contains a thermoplastic resin, if the wet tensile strength in the longitudinal direction of the test specimen of the substrate, as required by the test in accordance with JIS P8135, is not 2.0 kN / m or higher, substrate failure will occur when the adhesive sheet is peeled off from the adherend at high speed in a high-humidity environment due to the low penetration strength of the substrate.

[0024] 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 the wet tensile strength in the longitudinal direction of the test piece of the base material 11, as determined by a test in accordance with JIS P8135, is 2.0 kN / m or more, thereby providing excellent water resistance and re-peelability. In this specification, the term "sheet" includes the concept of "film."

[0025] [1-1] Base material The base material 11 contains at least pulp.

[0026] 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.

[0027] This prevents the substrate 11 from being damaged when peeling the adhesive sheet 10 from the adherend in a high-humidity environment.

[0028] 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.

[0029] [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.

[0030] In this specification, "main component" means a component having a content exceeding 50.0% by mass.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] [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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] [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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] [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.

[0045] 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].

[0046] [1-1-4-1]Print receiving layer The presence of a print-receiving layer in the substrate 11 allows for improved printability of the display label 100 when the adhesive sheet 10 is applied to the display label 100 described later. The print-receiving layer may be composed of, for example, a binder resin, filler, or water-resistant agent, as needed.

[0047] By including a binder resin in the print-receiving layer, the adhesion of the print layer described later is improved, resulting in superior printability for the display label 100.

[0048] 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.

[0049] 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 display label 100.

[0050] 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.

[0051] By including a water-resistant agent in the print-receiving layer, the water resistance of the entire label 100, particularly its water-resistant properties, can be improved through a synergistic effect with the aforementioned components. Examples of water-resistant agents that make up the print-receiving layer include polyamine resins.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] [1-2] Laminate layer The laminate layer 12 contains at least a thermoplastic resin. This makes the laminate layer 12 highly water-resistant.

[0060] The laminate layer 12 is provided between the base material 11 and the adhesive layer 13, which will be described later. 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, which will be described later, are stacked in this order.

[0061] This configuration prevents the resin constituting the laminate layer 12 from undergoing cohesive failure when the water-soaked adhesive sheet 10 is peeled off from the adherend.

[0062] Furthermore, because the laminate layer 12 is provided between the base material 11 and the adhesive layer 13 (described later), it is possible to prevent the pulp fibers of the base material 11 from absorbing water and bending the adhesive sheet 10 in one direction when wet or in a high-humidity environment.

[0063] [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.

[0064] 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.

[0065] The biomass-derived thermoplastic resin is not particularly limited, but examples include polyethylene resins and polypropylene resins produced by polymerizing ethylene or propylene produced from sugars made from sugarcane or other raw materials, or from oils and fats made from tall oil or other raw materials. Among these, it is preferable to include biomass polyethylene resin.

[0066] 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.

[0067] 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.

[0068] [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.

[0069] 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.

[0070] 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.

[0071] 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).

[0072] 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.

[0073] [1-2-3] Other conditions The thickness of the laminate layer 12 is preferably 15 μm or more, more preferably 20 μm to 200 μm, and even more preferably 30 μm to 100 μm. This allows the laminate layer 12 to exhibit sufficient water resistance, preventing interfacial fracture between the substrate 11 and the laminate layer 12, and preventing cohesive failure of the resin constituting the laminate layer 12 when peeling the wet adhesive sheet 10 from the adherend.

[0074] 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.

[0075] [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.

[0076] [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.

[0077] 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.

[0078] 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.

[0079] [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.

[0080] 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.

[0081] 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.

[0082] [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.

[0083] [1-4] Release Liner The surface of the adhesive layer 13 of the unused adhesive sheet 10 is preferably covered with a release liner (not shown).

[0084] This makes it easier to handle unused adhesive sheets 10 and effectively protects the adhesive layer 13 before it is attached to the substrate.

[0085] 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.

[0086] 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.

[0087] [1-5] Overall structure of the adhesive sheet 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.

[0088] [2] Label Next, a display label to which the adhesive sheet of the present invention is applied will be described. Figure 2 is a schematic longitudinal cross-sectional view showing a preferred embodiment of the label of the present invention. Figure 3 is a perspective view showing an embodiment in which the label of the present invention is affixed to an article.

[0089] The label 100 comprises a base material 11 made of a pulp-containing material, a laminate layer 12 made of a thermoplastic 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. Furthermore, the wet tensile strength in the longitudinal direction of the test specimen of the base material 11, as required by a test in accordance with JIS P8135, is 2.0 kN / m or more.

[0090] This configuration makes it possible to provide a label 100 that is highly water-resistant and highly re-peelable.

[0091] The display label 100 may, for example, be affixed to a product to show information to purchasers, consumers, etc., or it may be used for process control, logistics control, etc.

[0092] The display label 100 shown in Figure 2 consists of a base material 11, a laminate layer 12, an adhesive layer 13, and a printing layer 30, which will be described later. The printing layer 30 is printed on the side of the base material 11 opposite to the side facing the laminate layer 12 to form the display label 100.

[0093] [2-1] Printing layer In the display label 100 shown in Figure 2, the printed layer 30 is printed on the side of the substrate 11 opposite to the side facing the laminate layer 12.

[0094] The content displayed by the printing layer 30 is not particularly limited. For example, multiple display labels 100 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 by the printing layer 30 is not limited to letters and numbers, but may also include illustrations, photographs, graphs, or combinations thereof.

[0095] The printing layer 30 is not particularly limited in how it is formed 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. On the other hand, thermal transfer printing, inkjet printing, and electrophotographic (electrostatic) printing are suitable for printing variable information such as serial numbers.

[0096] The ink used to form the printed layer 30 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 30 is formed using photocurable ink (ultraviolet-curable ink, electron beam-curable ink), a suitable printed state can be maintained even when the display label 100 gets wet with water.

[0097] 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 the printed layer 30 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 the printed layer 30 to be manufactured more cheaply and efficiently while being environmentally conscious. In addition, the time required for ink drying can be reduced, resulting in improved productivity of the display labels 100.

[0098] In the illustrated configuration, the printing layer 30 is provided over the entire surface of the display label 100, but the printing layer 30 may be provided only on a portion of the surface of the display label 100.

[0099] The printed layer 30 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.

[0100] [2-2] Usage of display labels As shown in Figure 3, the display label 100 of this embodiment is used by being affixed to the article 500. The display label 100 is also called a POP label or eye-catching label, and when the labeled article 900, which has the display label 100 affixed to the article 500, is displayed in a store, it plays a role in attracting the attention of consumers.

[0101] Article 500 is a product displayed in a store, such as cosmetics, pharmaceuticals, or daily necessities, but is not particularly limited to any specific type of product. Therefore, the shape of Article 500 shown in the illustration is merely an example and will vary depending on the type of product; for example, it may be in the shape of a box or a bottle.

[0102] The label 100 may be affixed to containers used in bathrooms, such as shampoo bottles, containers used in washrooms, such as hand soap, or to the packaging of products stored in refrigerators or freezers, such as food. The label 100 has excellent water resistance and is re-peelable, even in high-humidity environments, when wet, or when covered with water droplets due to condensation.

[0103] Furthermore, because the label 100 has a laminate layer 12, the pulp fibers of the base material 11 absorb water when wet or in a high-humidity environment, preventing the label 100 from bending in one direction, and thus maintaining its appeal to consumers even when wet or in a high-humidity environment.

[0104] The display label 100 is attached to the article 500 in a way that it protrudes from it and has a printed layer 30 that displays information.

[0105] The display label 100 may have adhesive properties at the exposed portion 101 that protrudes from the article 500. However, in this embodiment, a non-adhesive masking layer, such as varnish, is formed on the surface of the adhesive layer 13 of the exposed portion 101 that protrudes from the article 500. This is a so-called adhesive-killing treatment, and the display label 100 does not have adhesive properties at the exposed portion 101 that protrudes from the article 500. Therefore, in this embodiment, only the attachment portion 102 can adhere to the article 500.

[0106] In contrast, by not forming an adhesive layer 13 on the exposed portion 101 protruding from the article 500, and instead forming the adhesive layer 13 only on the attachment portion 102, it is possible to attach only the attachment portion 102 to the article 500.

[0107] The size of the display label 100 is not particularly limited, but for example, 17.0 cm. 2 More than 50.0cm 2 The following applies, and the adhesive portion 102 is 8.0 cm 2 More than 22.0cm 2 The following applies. Furthermore, the size of the exposed portion 101 is not particularly limited, but considering attachment to the article 500, it may be, for example, 10.0% to 90.0% of the label area, or 20.0% to 80.0%.

[0108] The article 500 to which the label 100 of the present invention is affixed is not limited to goods; for example, labels affixed to articles other than goods to indicate some information are also included within the scope of the present invention.

[0109] Furthermore, the shape of the display label 100 of the present invention is not particularly limited, and it does not have to be rectangular as in the above embodiment, but may be any other shape.

[0110] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto.

[0111] For example, 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.

[0112] The adhesive sheet may have components other than the base material, 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, or between the base material and the laminate layer.

[0113] Furthermore, the adhesive sheet may have at least one coating layer on the side opposite to the side where the laminate layer of the substrate is provided.

[0114] The laminate layer may be placed on a portion of the surface direction of the label, but it is preferable to place it over the entire surface direction of the label. This further enhances water resistance and re-peelability, and also simplifies the manufacturing process. [Examples]

[0115] 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).

[0116] [3] Manufacturing of adhesive sheets (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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] (2) Formation of the laminate layer Next, biomass-derived polyethylene resin (SBC818, manufactured by Braskem) was heated to 310°C and extruded onto the side of the substrate opposite to the print-receiving layer using a T-die. Cooling water adjusted to a temperature of 23°C was passed through a water-cooling roll, and the surface of the water-cooling 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 (50 g / m²). 2 ). The thickness of the formed laminate layer was 50 μm.

[0122] (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.

[0123] 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 20 μm, and the mixture was dried at 90°C for 2 minutes to form an adhesive layer on the release liner.

[0124] 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 having a print-receiving layer and with the adhesive layer protected by the release liner. The thickness of the formed adhesive layer was 20 μm.

[0125] (4) Printing An adhesive sheet with a printed layer was obtained by printing a predetermined pattern on the side of the substrate opposite to the side facing the laminate layer using UV-curing ink (T&K TOKA, UV161).

[0126] (Example 2) An adhesive sheet was manufactured in the same manner as in Example 1, except that the thickness of the laminate layer was set to 15 μm.

[0127] (Comparative Example 1) An adhesive sheet was manufactured in the same manner as in Example 1, except that the thickness of the laminate layer was set to 10 μm.

[0128] (Comparative Example 2) An adhesive sheet was manufactured in the same manner as in Example 1, except that a laminate layer was not formed.

[0129] (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.

[0130] (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.

[0131] [5] Rating The adhesive sheets of each of the above-mentioned embodiments and comparative examples were evaluated as follows.

[0132] [5-1] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] ○: No substrate damage occurred. ×: Substrate failure occurred.

[0137] [5-2] Re-peelability after immersion in water After preparing the adhesive sheets for each of the above examples and comparative examples, test pieces of the adhesive sheet, cut to 25 mm x 300 mm, were attached to the surface of a PET container, which was the substrate, under conditions of 23°C and 50% RH (relative humidity).

[0138] After being left standing for one day in an environment of 23°C and 50% RH (relative humidity), the samples were immersed in 23°C water for 15 minutes, 30 minutes, and 1 hour, and then returned to an environment of 23°C and 50% RH (relative humidity). The samples taken immediately after removal were used as test samples.

[0139] Based on JIS Z0237, the adhesive was peeled off at a rate of 0.3 m / min using the 180° peeling method, and the amount of adhesive residue on the substrate was visually evaluated and assessed according to the following criteria.

[0140] ○: No adhesive residue was left on the adherend. ×: The laminate layer and adhesive layer remained on the substrate (interfacial fracture between the substrate and the laminate layer).

[0141] Only those samples that showed no adhesive residue after being soaked for 30 minutes or more and then peeled off (those that received a "○" rating) were deemed acceptable.

[0142] These results, along with the configuration of the adhesive sheets for each of the above-described examples and comparative examples, are summarized in Table 1.

[0143] Furthermore, when observing the printed side of the adhesive sheet in each of the above embodiments, even fine patterns were faithfully reproduced, indicating excellent printability.

[0144] [Table 1]

[0145] As is clear from Table 1, the adhesive sheets of each of the above embodiments had excellent water resistance and excellent re-peelability. In contrast, the adhesive sheets of each comparative example did not yield satisfactory results.

[0146] 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.

[0147] 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]

[0148] 10…Adhesive sheet 11...Base material 12…Laminating layer 13…Adhesive layer 30…printing layer 100... Display label 500...Goods 900… Labeled items

Claims

1. An adhesive sheet used for display labels, 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 the laminate layer contains a biomass-derived thermoplastic resin.

3. The adhesive sheet according to claim 1 or 2, wherein the thickness of the laminate layer is 15 μm or more.

4. 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, A label 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.

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