adhesive labels

Abstract

To provide an adhesive label that firmly adheres to an adherend at the time of use for sticking but is not peeled off with the adherence of water at room temperature, and when peeling the same off, can be easily peeled off by adding warm water or hot water.SOLUTION: In an adhesive label having a surface substrate and at least an adhesive layer formed on one side of the surface substrate, the surface substrate is a paper substrate with a degree of Stockigt equal to or longer than 25 seconds, and when the adhesive label is soaked in water at 20°C for 300 seconds in a state where water is stuck on an adherend with impermeability, the adhesive label is not peeled off from the adherend, but when soaked in warm water at 60°C for 300 seconds, the adhesive is peeled off from the adherend.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive label, and more particularly to an adhesive label that is attached to an adherend such as a container, and that does not peel off when exposed to room temperature water, but can be easily peeled off from the adherend when exposed to warm water or hot water. [Background technology]

[0002]

[0003] Pressure-sensitive adhesive labels are used in a wide range of applications, including commercial, office, process control, logistics management, and home use. Generally, pressure-sensitive adhesive sheets are widely used, in which an adhesive layer is provided on one side of a surface substrate, and the adhesive layer is sandwiched between the surface substrate and a release sheet. Recently, pressure-sensitive adhesive labels without a release sheet have also been developed, in which a release agent or a mold release agent is applied to one side of a surface substrate, and an adhesive layer is provided and laminated on the other side.

[0003] The surface substrate may be paper, film, or metal foil. The release sheet may be a release sheet substrate coated with a release agent or mold release agent such as a silicone compound or a fluorine compound. The release sheet substrate may be a laminated paper obtained by laminating a resin film such as polyethylene onto a high-density base paper such as glassine paper, clay-coated paper, kraft paper, or high-quality paper, or a resin-coated paper obtained by providing a coating layer mainly composed of a water-soluble polymer such as polyvinyl alcohol or starch and a pigment on kraft paper or high-quality paper. Among these, polyethylene-laminated laminated paper is generally and widely used. The adhesive may be a rubber-based, acrylic-based, vinyl ether-based emulsion, or a solvent- or solventless-type adhesive.

[0004] One use of such adhesive labels is as a management label for plastic containers used as returnable boxes in various logistics departments. Plastic containers are generally made of molded polypropylene or polyethylene resins, due to their ease of molding, durability, chemical resistance, etc. Adhesive labels with printed or inscribed information necessary for logistics management are affixed to one or more surfaces of these plastic containers. However, they are fundamentally required to remain in place until the container is transported to its destination, i.e., to have strong adhesive properties to the surface of the substrate. The information on the adhesive label is read by a computer, but when a plastic container is reused, there are problems such as the computer misreading the information if a new management label is affixed over a previously used adhesive label. Therefore, when reusing the product, it is necessary to remove the adhesive label that was firmly attached to the product.

[0005] Recently, the movement to eliminate plastic has been accelerating as a measure against environmental issues, and stainless steel trays and containers are beginning to be used instead of plastic containers. These also use adhesive labels for management or display purposes, but just like plastic containers, adhesive labels that can firmly adhere to the substrate and can be easily removed from the substrate are required.

[0006] Recently, when plastic containers are reused, they are washed in an automatic washing machine, but as mentioned above, the adhesive strength of the adhesive labels is strong, so the adhesive labels cannot be removed by this washing, and the adhesive labels must be removed by hand, which is costly and time-consuming. Adhesive labels that can be removed by washing in an automatic washing machine have also been proposed (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-114382 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-89722 Summary of the Invention [Problem to be solved by the invention]

[0008] The adhesive labels in Patent Documents 1 and 2 use an adhesive whose adhesive strength weakens when it comes into contact with water, and therefore peel off even when water at room temperature or condensation water adheres to the label. The present invention aims to provide an adhesive label that adheres firmly when attached, maintains its adhesion even when water at room temperature adheres to the label, and can be easily removed with warm water or hot water. [Means for solving the problem]

[0009] The present invention is as follows. (1) A pressure-sensitive adhesive label having at least a surface substrate and a pressure-sensitive adhesive layer formed on one surface of the surface substrate, The surface substrate is a paper substrate having a Stockigt sizing degree of 25 seconds or more, An adhesive label characterized in that when the adhesive label is attached to a water-impermeable substrate and immersed in water at 20°C for 300 seconds, the adhesive label does not peel off from the substrate, but when immersed in warm water at 60°C for 300 seconds. (2) The adhesive forming the adhesive layer is a polyethylene terephthalate film having a thickness of 50 μm and a thickness of 25 g / m 2 When a test sheet laminated with the adhesive is prepared, the adhesive strength of the test sheet to a SUS plate is 60 to 800 N / m, The adhesive label according to (1) is characterized in that when the test sheet is attached to a SUS plate and immersed in water at 20°C for 300 seconds, the test sheet does not peel off from the SUS plate, but when immersed in warm water at 60°C for 300 seconds, the test sheet peels off from the SUS plate. (3) The adhesive forming the adhesive layer is a polyethylene terephthalate film having a thickness of 50 μm and a thickness of 25 g / m 2When a test sheet laminated with the adhesive is prepared, the adhesive strength of the test sheet to a SUS plate is 60 to 800 N / m, An adhesive label according to (1) or (2), characterized in that when the test sheet is attached to a polypropylene plate and immersed in water at 20°C for 300 seconds, the test sheet does not peel off from the polypropylene plate, and when immersed in warm water at 60°C for 300 seconds, the adhesive label peels off from the polypropylene plate. (4) The pressure-sensitive adhesive label according to any one of (1) to (3), wherein the surface substrate is a paper substrate having a Stockigt sizing degree of 30 seconds or more. (5) The adhesive label according to any one of (1) to (4), wherein the adhesive layer contains an acrylic emulsion adhesive. DETAILED DESCRIPTION OF THE INVENTION

[0010] The pressure-sensitive adhesive label of the present invention is a pressure-sensitive adhesive label having at least a surface substrate and a pressure-sensitive adhesive layer formed on one surface of the surface substrate. The surface substrate must be a paper substrate with a Stoeckigt sizing degree of 25 seconds or more as specified in JIS P 8122:2004. It is preferably 30 seconds or more, more preferably 40 seconds or more. The upper limit is not particularly limited, but is about 500 seconds. By using such a surface substrate, when hot or warm water is applied, moisture penetrates from the surface of the paper substrate into the interior of the paper substrate, rather than reducing the strength of the paper substrate. Therefore, moisture penetrates from the periphery of the affixed adhesive label to the interface between the adhesive and the surface of the adherend, allowing the adhesive label to be peeled off without damaging the paper substrate. If the paper substrate is damaged, a portion of the paper substrate may remain on the adherend, or a portion of the adhesive may remain on the adherend.

[0011] The pressure-sensitive adhesive label of the present invention must not peel off from an adherend that is impermeable to water when the label is immersed in water at 20° C. for 300 seconds while attached to the adherend, and must peel off from the adherend when immersed in warm water at 60° C. for 300 seconds. This enables the pressure-sensitive adhesive label to not peel off in room temperature water, cold water, condensed water, or the like, which are not intended for peeling, but to peel off when warm water or hot water is applied for the purpose of peeling. In order to control the peelability by changing the water temperature, it is necessary to use a paper substrate having the specific Stockigt sizing degree mentioned above, and to use an adhesive whose adhesive strength at the interface between the adhesive layer and the adherend decreases when warm water is applied.

[0012] The adhesive is not particularly limited as long as, when made into an adhesive label, the adhesive label does not peel off from the adherend when attached to a water-impermeable adherend and is immersed in water at 20°C for 300 seconds, and the adhesive label peels off from the adherend when immersed in warm water at 60°C for 300 seconds.

[0013] The adhesive preferably has an adhesive strength to a SUS plate of 60 to 800 N / m, more preferably 100 to 600 N / m. The adhesive strength here refers to the adhesive strength of a test sheet prepared by laminating 25 g / m2 of adhesive to a 50 μm-thick polyethylene terephthalate sheet to form a test sheet, and the adhesive strength is a value in accordance with JIS-Z-0237. An adhesive strength of 60 N / m or more ensures sufficient adhesion to the adherend, while an adhesive strength of 800 N / m or less ensures stable peeling when hot water is applied.

[0014] Furthermore, among adhesives that satisfy the above adhesive strength, an adhesive is preferred that does not peel off from the SUS plate when the test sheet is attached to the SUS plate and immersed in water at 20°C for 300 seconds, and that peels off from the SUS plate when immersed in warm water at 60°C for 300 seconds. The use of such an adhesive in an adhesive label makes it suitable for use on containers made of stainless steel, etc. Note that "peeling of the test sheet" does not only mean that the test sheet floats up from the SUS plate, but also includes cases where the test sheet peels off when a gentle water flow is generated or the SUS plate is shaken while immersed.

[0015] Furthermore, among adhesives that satisfy the above adhesive strength, an adhesive is preferred that, when the test sheet is attached to a polypropylene plate and immersed in 20°C water for 300 seconds, the test sheet does not peel off from the polypropylene plate, and when immersed in 60°C warm water for 300 seconds, the test sheet peels off from the polypropylene plate. The use of such an adhesive in an adhesive label makes it suitable for use on containers made of polypropylene, etc. Note that "peeling of the test sheet" does not only mean that the test sheet floats up from the polypropylene plate, but also that the test sheet peels off when it is immersed in water or when the SUS plate is shaken.

[0016] For both the SUS plate and the polypropylene plate, it is preferable to use an adhesive that does not peel off when immersed in water at 20°C, but peels off when immersed in warm water at 60°C for 300 seconds, as this will provide good adhesion and peelability for many materials. The pressure-sensitive adhesive label of the present invention is not limited to use on SUS plates or polypropylene plates, and can be applied to various materials as long as the adherend is water-impermeable. If the adherend is water-permeable, water may penetrate into the adherend during peeling, potentially destroying the adherend and making it difficult to separate the pressure-sensitive adhesive label.

[0017] The pressure-sensitive adhesive can be selected from various emulsion, solvent-based, or solventless pressure-sensitive adhesives such as rubber-based, acrylic-based, and vinyl ether-based adhesives, as long as they satisfy the above requirements. Among these, emulsion-based pressure-sensitive adhesives are preferred because they provide excellent hydrophilicity at the interface between the adherend surface and the pressure-sensitive adhesive layer. Acrylic emulsion-based pressure-sensitive adhesives are particularly preferred because they allow for easy control of adhesive strength and hydrophilicity. The following description will discuss acrylic emulsion-based pressure-sensitive adhesives as a representative example.

[0018] The components constituting the acrylic emulsion-type pressure-sensitive adhesive preferably contain a hydrophilic component. Examples include ethylenically unsaturated carboxylic acid-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, monoalkyl maleic acid, monoalkyl itaconic acid, and monoalkyl fumaric acid; alkoxyalkyl (meth)acrylates such as methoxyethyl acrylate and ethoxyethyl acrylate; carboxylic acid-modified rosin esters; caprolactone adducts of (meth)acrylic acid; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, (meth)acrylamide, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate. These components are preferably contained in an amount of approximately 5 to 20% by mass in the pressure-sensitive adhesive composition. A content of 5% by mass or more can enhance the hydrophilicity of the pressure-sensitive adhesive, while a content of 20% by mass or less can enhance adhesive strength.

[0019] Further components constituting the pressure-sensitive adhesive include copolymerizable monomers other than the hydrophilic monomers, such as butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and stearyl (meth)acrylate, which impart adhesiveness to the pressure-sensitive adhesive. Furthermore, components that adjust adhesive performance include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, cyclohexyl (meth)acrylate, glycidyl (meth)acrylate, vinyl acetate, vinyl propionate, vinyl chloride, styrene, ethylene, etc. These compounds can be used as appropriate, taking into consideration the balance of adhesive performance of the adhesive, but in terms of adhesiveness, cohesive strength, etc. of the adhesive, it is more preferable to use butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, methyl (meth)acrylate, or vinyl acetate.

[0020] When producing a copolymer to obtain a pressure-sensitive adhesive, at least one of (poly)alkylene glycol di(meth)acrylate, (poly)alkylene glycol mono(meth)acrylate, (poly)ethylene glycol, and (poly)propylene glycol may be added. When the copolymer is produced in the presence of these, the hydrophilicity of the pressure-sensitive adhesive can be increased and the molecular weight can be increased.

[0021] The method for producing the copolymer is not particularly limited, and the copolymer can be produced by a known method such as solution polymerization in the presence of water, a solvent, a chain transfer agent, a polymerization initiator, etc., or emulsion polymerization in an aqueous system in the presence of an emulsifier, a chain transfer agent, a polymerization initiator, a dispersant, etc.

[0022] Examples of polymerization initiators used in the polymerization include persulfates such as potassium persulfate and ammonium persulfate, azo compounds such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(2,4-dimethylvaleronitrile), peroxides such as hydrogen peroxide, benzoyl peroxide and lauryl peroxide, and so-called redox polymerization initiators consisting of a combination of ammonium persulfate with sodium sulfite or sodium acid sulfite. The amount of the polymerization initiator used is usually about 0.2 to 2 mass %, and more preferably about 0.3 to 1 mass %, based on the total amount of monomers used in the polymerization.

[0023] Examples of chain transfer agents added during copolymerization include alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, and N-dodecyl mercaptan; thioglycolic acid esters such as octyl thioglycolate, nonyl thioglycolate, 2-ethylhexyl thioglycolate, and 2-ethylhexyl β-mercaptopropionate; 2,4-diphenyl-4-methyl-1-pentene; and 1-methyl-4-isopropylidene-1-cyclohexene. Thioglycolic acid esters, 2,4-diphenyl-4-methyl-1-pentene, and 1-methyl-4-isopropylidene-1-cyclohexene are particularly preferred, as they result in copolymers with low odor. The amount of chain transfer agent used is adjusted to approximately 0.001 to 3% by mass of the total monomers to be polymerized. Organic solvents such as methanol, ethanol, and isopropyl alcohol can also be used.

[0024] The monomer concentration during polymerization is usually 30 to 70% by mass, preferably about 40 to 60% by mass. The polymerization reaction is usually carried out for 2 to 8 hours at a temperature of 60 to 100°C. Furthermore, wetting agents, leveling agents, thickeners, antifoaming agents, preservatives, etc. may be added as appropriate.

[0025] By adding a crosslinking agent to an acrylic emulsion-type pressure-sensitive adhesive, the strength of the pressure-sensitive adhesive layer can be increased while maintaining hydrophilicity. When the pressure-sensitive adhesive layer has a high film strength, the pressure-sensitive adhesive layer is maintained during peeling, allowing for smooth peeling without leaving adhesive residue on the adherend. Examples of crosslinking agents include epoxy-based crosslinking agents such as ethylene glycol diglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and pentaerythritol polyglycidyl ether; isocyanate-based crosslinking agents such as 1,2-ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate; and aluminum metal chelate-based crosslinking agents such as aluminum tris(acetylacetate), aluminum tris(ethylacetoacetate), aluminum acetoacetate aluminum diisopropylate, and aluminum monoacetylacetonate bis(ethylacetoacetate).

[0026] When these crosslinking agents are added, they are added in an amount of 0.1 to 1.5 parts by mass relative to 100% by mass of the adhesive composition. Adding a crosslinking agent has the effect of improving peel resistance due to strong adhesion to the adherend, but adding an excessive amount increases the crosslink density of the adhesive, weakening the adhesive strength of the resulting adhesive and making it less practical. Of these crosslinking agents, epoxy-based crosslinking agents in particular improve peelability in warm water, as they make the adhesive layer less likely to separate after crosslinking.

[0027] A hydrophilic plasticizer can be added to acrylic emulsion adhesives to adjust the adhesive's physical properties and prevent discoloration and deterioration over time. The addition of a hydrophilic plasticizer can also increase the adhesive's hydrophilicity and improve its releasability with warm water. Examples of hydrophilic plasticizing substances include alkanolamines such as triethanolamine, tripropanolamine, triisopropanolamine, N-methyldiethanolamine, and N,N-dibutylethanolamine; sugar alcohols such as glycerin, sorbitol, mannitol, dulcitol, iditol, erythritol, arabitol, and adonit; copolymers of polyethylene oxide or polypropylene oxide with polyhydric alcohols such as glycerin, xylitol trioxyisobutane, and sorbitol; polyether polyols such as polyethylene glycol and polypropylene glycol; copolymers of ethylene oxide and propylene oxide; and nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene polyoxypropylene glycol. Taking into consideration the adhesiveness and peelability in warm water, these substances are added in an amount of 10% by weight or less, more preferably in the range of 0.5 to 10% by weight, relative to 100% by weight of the adhesive. Among these hydrophilic plasticizing substances, alkanolamines and nonionic surfactants are particularly preferred, as they can produce adhesives with good adhesion and storage stability.

[0028] An adhesive that satisfies the requirement for an adhesive label that does not peel off from an adherend when immersed in water at 20°C for 300 seconds while attached to a water-impermeable adherend, and peels off from an adherend when immersed in warm water at 60°C for 300 seconds, may be obtained, for example, by using a known adhesive and adjusting the hydrophilicity, adhesiveness, etc., using a crosslinking agent, a hydrophilic plasticizing substance, etc., as described above.

[0029] As mentioned above, the surface substrate is a paper substrate with a Stoeckigt sizing degree of 25 seconds or more. However, for example, paper substrates such as art paper, coated paper, cast paper, kraft paper, thermal paper, inkjet paper, impregnated paper, and kraft paper can be used, or even if the paper substrate is high-quality paper with a Stoeckigt sizing degree of less than 25 seconds, the Stoeckigt sizing degree can be adjusted to 25 seconds or more by coating with a coating liquid whose main component is a natural or synthetic resin and / or pigment, such as casein, dextrin, starch and its derivatives, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, or acrylic ester copolymer.

[0030] The adhesive label is generally in the form of an adhesive sheet in which an adhesive is coated on one side of the surface substrate and the adhesive is sandwiched between the surface substrate and a release sheet, but it may also be in the form of a tape in which a release agent is coated on the heat-sensitive layer side of thermal paper, or a releasable printable layer is provided on the printing surface of printing paper such as art paper or coated paper, and an adhesive layer is provided on the opposite side and laminated together, without using a release sheet. The release sheet is not particularly limited, and any known release sheet can be used.

[0031] The adhesive layer may be applied directly to the surface substrate, or may be applied to a release sheet and then attached to the surface substrate to transfer the adhesive layer to the surface substrate. Known coating methods can be used, such as a reverse roll coater, knife coater, air knife coater, bar coater, slot die coater, lip coater, or reverse gravure coater. The amount of adhesive applied after drying is 5 to 50 g / m. 2 It is adjusted within a range of about 5g / m 2 By setting the adhesive strength to 50g / m or more, sufficient adhesive strength to the adherend can be obtained. 2 By setting the following, peel stability can be obtained during peeling. [Example]

[0032] The present invention will be explained in more detail below with reference to examples, but it should be understood that the present invention is not limited to these examples. In the examples, all parts, ratios, coating amounts, etc. are expressed by weight of solid content unless otherwise specified.

[0033] "Surface base material" Surface substrate A: Commercially available coated printing paper (basis weight 84.9 g / m 2 , Steckigt size 17 seconds) Surface substrate B: Commercially available coated printing paper (basis weight 84.9 g / m 2 , Steckigt size degree 36 seconds) Surface substrate C: Commercially available coated printing paper (basis weight 89 g / m 2 , Steckigt size degree 209 seconds) Surface substrate D: Commercially available thermal recording paper (grammage 76 g / m 2 , Steckigt size degree 43 seconds)

[0034] "Manufacturing adhesive 1" An emulsified monomer mixture was prepared by mixing 75 parts of methoxyethyl acrylate, 20 parts of an acrylic acid caprolactone adduct (trade name: Aronix M-5300, manufactured by Toagosei Co., Ltd.), 220 parts of 2-ethylhexyl acrylate, 45 parts of acrylic acid, 20 parts of vinyl acetate, 20 parts of methyl (meth)acrylate, 6 parts of an anionic emulsifier (trade name: Emeral NC-35, manufactured by Kao Corporation), and 150 parts of ion-exchanged water.

[0035] Next, 150 parts of ion-exchanged water, 3 parts of potassium peroxide, and 3 parts of octyl mercaptan were charged into a flask equipped with a stirrer, cooler, dropping funnel, nitrogen inlet tube, and thermometer, and the temperature was raised to 80°C while purging with nitrogen, after which 1 / 6 of the emulsified monomer mixture was added dropwise. When the reaction rate reached 90%, the remaining monomer mixture was added dropwise over 3 hours to carry out polymerization. After completion of the dropwise addition, the mixture was aged at 80°C for 3 hours to complete the reaction. Next, 2 parts of triethanolamine, 3 parts of a nonionic surfactant (product name: Emulgen 810, manufactured by Kao Soap Co., Ltd.), and 28 parts of an ethylene-vinyl acetate-acrylic copolymer (product name: Sumikaflex S-3110, manufactured by Sumitomo Chemical Co., Ltd.) were added to 100 parts of this copolymer, and the mixture was stirred vigorously to obtain an acrylic emulsion-type pressure-sensitive adhesive. 0.5 parts of diglycerol polyglycidyl ether (product name: Denacol EX-421, manufactured by Nagase Chemicals Co., Ltd.) was added as a crosslinking agent to 100 parts of the acrylic emulsion-type pressure-sensitive adhesive obtained by the above method to produce a pressure-sensitive adhesive.

[0036] "Manufacturing adhesive 2" An adhesive was produced in the same manner as in the production of adhesive 1, except that diglycerol polyglycidyl ether was not added.

[0037] "Manufacturing adhesive 3" An adhesive was produced in the same manner as in the production of adhesive 1, except that the amount of diglycerol polyglycidyl ether added was changed to 0.1 parts.

[0038] "Manufacturing adhesive 4" An adhesive was produced in the same manner as in the production of adhesive 1, except that the amount of diglycerol polyglycidyl ether added was changed to 1.5 parts.

[0039] "Adhesive 5" A commercially available removable acrylic adhesive (product name: ATR-715, manufactured by Saiden Chemical Industries, Ltd.) was prepared.

[0040] "Adhesive 6" A commercially available medium-tack acrylic adhesive (product name: BPS1109, manufactured by Toyochem Co., Ltd.) was prepared.

[0041] "Creating a test sheet" Adhesives 1 to 5 were applied to polyethylene laminated release paper in a coating amount of 25 g / m after drying. 2The adhesive layer was formed by laminating a 50 μm thick polyethylene terephthalate film (product name: E5100, manufactured by Toyobo Co., Ltd.) to obtain a test sheet with a release liner. Evaluation was performed by peeling off the release liner to expose the adhesive layer. The obtained test sheet was subjected to the following evaluations, and the results are shown in Table 1.

[0042] "Adhesion" Adhesion to SUS plates Measurement is based on JIS-Z-0237 I followed the instructions.

[0043] "20℃ water immersion test" After the test sheet was attached to the SUS plate and left for 24 hours, it was immersed in water at 20°C and the condition of the test sheet was visually evaluated. After the test sheet was attached to the polypropylene plate and left for 24 hours, it was immersed in water at 20°C and the condition of the test sheet was visually evaluated. (Evaluation criteria) ◎: The test sheet did not float even after 300 seconds, and no water infiltrated from around the test sheet. ○: The test sheet does not float even after 300 seconds, but there is a small amount of water seeping in from the periphery of the test sheet. △: After 300 seconds, the test sheet lifted slightly. ×: Test sheet peels off within 300 seconds

[0044] "60℃ water immersion test" After the test sheet was attached to the SUS plate and left for 24 hours, it was immersed in water at 60°C and the condition of the test sheet was visually evaluated. After the test sheet was attached to the polypropylene plate and left for 24 hours, it was immersed in water at 60°C and the condition of the test sheet was visually evaluated. (Evaluation criteria) ◎: Test sheet peels off within 180 seconds ○: The test sheet peels off within 300 seconds but more than 180 seconds. △: The test sheet has not peeled off after 300 seconds, but it peels off when lightly stirred. ×: The test sheet does not lift even after 300 seconds, and the test sheet does not peel off even when lightly stirred.

[0045] [Table 1]

[0046] Comparative Example 1 (Making adhesive labels) The obtained adhesive 1 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate A to obtain an adhesive label.

[0047] Example 1 (Making adhesive labels) The obtained adhesive 1 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate B to obtain an adhesive label.

[0048] Example 2 (Making adhesive labels) The obtained adhesive 1 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate C to obtain an adhesive label.

[0049] Example 3 (Making adhesive labels) The obtained adhesive 1 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate D to obtain an adhesive label.

[0050] Example 4 (Making adhesive labels) The obtained adhesive 2 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate B to obtain an adhesive label.

[0051] Example 5 (Making adhesive labels) The obtained adhesive 3 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate B to obtain an adhesive label.

[0052] Example 6 (Making adhesive labels) The obtained adhesive 4 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate B to obtain an adhesive label.

[0053] Comparative Example 2 (Making adhesive labels) The obtained adhesive 5 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate B to obtain an adhesive label.

[0054] Comparative Example 3 (Making adhesive labels) The obtained adhesive 6 was applied to a commercially available polyethylene laminated release paper at a dry weight of 25 g / m 2 After drying, the resulting mixture was attached to surface substrate B to obtain an adhesive label.

[0055] The obtained adhesive labels were evaluated as follows.

[0056] "20℃ water immersion test" SUS plates, polypropylene plates, and glass plates were prepared as adherends, and after adhesive labels were attached and left for 24 hours, they were immersed in water at 20°C, and the state of the adhesive labels was visually evaluated. (Evaluation criteria) ◎: The adhesive label did not lift even after 300 seconds, and no water penetrated from around the label. ○: The adhesive label did not lift even after 300 seconds, but there was some water penetration around the label. △: After 300 seconds, there is some lifting of the adhesive label. ×: The adhesive label peels off within 300 seconds "60℃ water immersion test" SUS plates, polypropylene plates, and glass plates were prepared as adherends, and after adhesive labels were attached and left for 24 hours, they were immersed in 60°C water and the condition of the adhesive labels was visually evaluated. (Evaluation criteria) ◎: The adhesive label peels off within 180 seconds ○: The adhesive label peels off within 300 seconds but more than 180 seconds. △: The adhesive label has not peeled off after 300 seconds, but the adhesive label peels off when the adherend is shaken ×: The adhesive label does not lift even after 300 seconds, and the adhesive label does not peel off when the adherend is shaken.

[0057] [Table 2]

[0058] Thus, the pressure-sensitive adhesive label of the present invention exhibited sufficient adhesion to the adherend, did not peel off when water at 20° C. was applied, and was easily peeled off when warm water was applied. Furthermore, the adherend is not limited to SUS plates, and can be applied to a variety of other objects such as metal containers, plastic containers, and glass containers.

Claims

1. A pressure-sensitive adhesive label having at least a surface substrate and a pressure-sensitive adhesive layer formed on one surface of the surface substrate, The surface substrate is a paper substrate having a Stockigt sizing degree of 25 seconds or more, An adhesive label characterized in that when the adhesive label is attached to a water-impermeable adherend and immersed in water at 20°C for 300 seconds, the adhesive label does not peel off from the adherend, but when immersed in warm water at 60°C for 300 seconds, the adhesive label peels off from the adherend, the pressure-sensitive adhesive layer contains an acrylic emulsion-type pressure-sensitive adhesive and a hydrophilic plasticizing substance, The adhesive label has an additive amount in the adhesive layer of 0.5 to 10% by weight relative to 100% by weight of the adhesive.

2. The adhesive forming the adhesive layer is a polyethylene terephthalate film having a thickness of 50 μm and a thickness of 25 g / m ２ When a test sheet having the adhesive laminated thereon is prepared, the adhesive strength of the test sheet to a SUS plate in accordance with JIS-Z-0237 is 60 to 800 N / m, 2. The adhesive label according to claim 1, wherein the adhesive is such that when the test sheet is attached to a stainless steel plate and immersed in water at 20°C for 300 seconds, the test sheet does not peel off from the stainless steel plate, but when immersed in warm water at 60°C for 300 seconds, the test sheet peels off from the stainless steel plate.

3. The adhesive forming the adhesive layer is a polyethylene terephthalate film having a thickness of 50 μm and a thickness of 25 g / m ２ When a test sheet having the adhesive laminated thereon is prepared, the adhesive strength of the test sheet to a SUS plate in accordance with JIS-Z-0237 is 60 to 800 N / m, 3. The adhesive label according to claim 1, wherein the adhesive is such that when the test sheet is attached to a polypropylene plate and immersed in water at 20°C for 300 seconds, the test sheet does not peel off from the polypropylene plate, but when immersed in warm water at 60°C for 300 seconds, the test sheet peels off from the polypropylene plate.

4. 4. The adhesive label according to claim 1, wherein the surface substrate is a paper substrate having a Stockigt sizing degree of 30 seconds or more.

5. An adhesive label described in any one of claims 1 to 4, wherein the hydrophilic plasticizing substance is at least one selected from the following hydrophilic plasticizing substances: (hydrophilic plasticizing substance) Nonionic surfactants selected from alkanolamines such as triethanolamine, tripropanolamine, triisopropanolamine, N-methyldiethanolamine, and N,N-dibutylethanolamine; sugar alcohols such as glycerin, sorbitol, mannitol, dulcite, idite, erythritol, arabitol, and adonite; copolymers of polyethylene oxide or polypropylene oxide with polyhydric alcohols such as glycerin, xylitol trioxyisobutane, and sorbitol; polyether polyols such as polyethylene glycol and polypropylene glycol; copolymers of ethylene oxide and propylene oxide; polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene polyoxypropylene glycols.

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